FUTURE BRIEF: Towards the battery of the future - Science for Environment Policy - Europa EU
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
Science for Environment Policy
FUTURE BRIEF:
Towards the battery
of the future
September 2018
Issue 20
Environment
Science for Environment Policy This Future Brief is written and edited by the Science
Communication Unit, University of the West of England
Towards the battery of the future
(UWE), Bristol
Email: sfep.editorial@uwe.ac.uk
Printed by the Publications Office in Luxembourg.
Luxembourg: Publications Office of the European Union, 2018 To cite this publication:
Science for Environment Policy (2018) Towards the battery
Reuse is authorised provided the source is acknowledged. of the future. Future Brief 20. Brief produced for the European
Commission DG Environment by the Science Communication
The reuse policy of European Commission documents is regulated by Decision Unit, UWE, Bristol. Available at:
2011/833/EU (OJ L 330, 14.12.2011, p. 39). For any use or reproduction of http://ec.europa.eu/science-environment-policy
photos or other material that is not under the EU copyright, permission must
be sought directly from the copyright holders.
Acknowledgements
Print ISBN 978-92-79-84039-5 ISSN 2363-2771 We wish to thank the scientific advisor, Dr Jens Peters, Helmholtz
doi:10.2779/503230 KH-BB-18-006-EN-C Institute Ulm (HIU) for Electrochemical Energy Storage;
Karlsruhe Institute of Technology (KIT), for his input to this
PDF ISBN 978-92-79-84040-1 ISSN 2363-278X report. Final responsibility for the content and accuracy of the
doi:10.2779/674936 KH-BB-18-006-EN-N report, however, lies solely with the author.
Images:
Reproduced with permission by the relevant author or publisher, or otherwise publicly authorised
for use, as follows:
Pages 4&8: Fig. 1 Key components of a battery. Designed by Science Communication Unit, UWE,
Bristol
Page 7: Batteries for renewable energy storage © getty images/Petmal
About Science for Environment Policy
Page 10: Electric vehicle charging © getty images/https://www.facebook.com/PlargueDoctor/
Science for Environment Policy is a free news
Page 13: Lithium-ion batteries © getty images/SVproduction
and information service published by the European
Page 14: Congolese raw material © getty images/Nada3 Commission’s Directorate-General Environment,
Page 15: Mine tailings © getty images/francisblack which provides the latest environmental policy
Page 18: Fig. 2 Battery production chain © MEET Battery Research Center, University of relevant research findings.
Münster
Page 22: Waste batteries at a metal recycling scrap yard © getty images/tfoxfoto Future Briefs are a feature of the service which
Page 26: Waste cylindrical batteries © getty images/kemalbas provide expert forecasts of environmental policy
Page 27: NASICON battery crystal structure © CC by 4.0. Materialscientist issues on the horizon. In addition to Future Briefs,
Page 28: Redox flow batteries © Application Center Redox-Flow at the Fraunhofer Institute for Science for Environment Policy also publishes a
regular News Alert which is delivered by email
Chemical Technology ICT
to subscribers and provides accessible summaries
Page 31: Fig. 3 Printed battery diagram. Adapted from Nguyen, Fraiwan and Choi, 2014 by
of key scientific studies.
Science Communication Unit, UWE, Bristol
Page 32: Flexen printed battery © University of Cambridge
http://ec.europa.eu/science-environment-policy
Page 34: Battery applications © getty images/TarikVision.
Keep up-to-date
Neither the European Commission nor any person acting on behalf of the Subscribe to Science for Environment Policy’s
Commission is responsible for the use that might be made of the following News Alert by emailing:
information. The contents and views included in Science for Environment Policy sfep@uwe.ac.uk
are based on independent research and do not necessarily reflect the position
of the European Commission. Or sign up online at:
http://ec.europa.eu/science-environment-policy
© European Union 2018
T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
3
Contents
Executive summary 2
Introduction 4
Section 1. Introduction to batteries 6
1.1 How a battery works: the basics 6
1.2 Battery architecture 7
1.3 Rechargeability 7
1.4 Energy, power and energy management 7
1.5 The future evolution of battery design 8
Section 2. Environmental issues for batteries 10
2.1 Material issues 10
2.2 Energy issues: production and charging 18
2.3 Lifespan 20
2.4 End-of-Life (EoL) treatment 21
Section 3. Case studies 25
Case study 1: Solid-state lithium 25
Case study 2: Redox flow batteries 26
Case study 3: Printed batteries 29
Summary 31
References 33
T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
4
Executive summary
This Future Brief from Science for Environment
Policy provides an overview of technical aspects
of battery design and production which enable
the environmental footprint of batteries to be
lowered. It highlights how battery technologies
are evolving to deliver better performing
batteries. High-quality and technologically
innovative batteries are imperative for the EU
in the context of its move towards a low-carbon,
climate-friendly and more circular economy.
Batteries bring a number of environmental advantages. in the longer term, or in the event of a dramatic,
By enabling a greater share of renewable energy in the unexpected increase in resource demand. The
power sector, they help avoid negative environmental vulnerable supply chains for many of these materials
impacts of fossil fuel-or nuclear-based power, such should also be acknowledged.
as air pollution and its corresponding effects on
human and ecological health, as well as greenhouse In addition, concerns remain surrounding the
gas (GHG) emissions. Furthermore, materials in toxicity and safety (e.g. flammability) of certain
batteries can be recovered and recycled, some of them battery components. For instance, there are issues
indefinitely – unlike fossil fuels, which are burned relating to some of the materials used in lithium-
and lost forever when used for energy production. ion technologies, including active materials in the
electrodes and electrolytes, notably cobalt, as well
However, manufacturing and using batteries, as the substances that bind electrode materials
as well as the way they are treated at the end of together.
their life, also has environmental impacts. This
report explores aspects of battery design and There are many means of addressing these material
manufacturing which may be considered in issues in future battery designs. For instance,
support of ambitions to develop batteries that are increasing the energy density of batteries (i.e. the
high-performing and have minimal environmental amount of energy stored per litre or kilogram of
impact. battery) not only offers important benefits for
battery performance, but also reduces pressure
Many of these considerations relate to the materials on resources and the impacts caused by battery
used to produce batteries. There appear to be production, as less material overall is needed to
sufficient reserves of most of the key constituents produce the same capacity of battery.
of lithium-ion batteries – the most quickly growing
form of technology on the battery market – to meet Various alternatives to toxic materials and/or
near-term and predicted increases in demand for materials with limited or risky supply are also
batteries stemming from the rapid rise of electric being explored by scientists. Some discussed in this
mobility. However, we cannot rely on these reserves
T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
5
report include sulphur, oxygen and sodium as active recycling), and avoid the potentially toxic impacts
cathode materials. Technologies based on these of landfilling and incineration. Design features
materials could potentially lower the environmental which make batteries easy to disassemble are
impact as well as increase the performance, but they important in supporting recycling and re-use.
must overcome some major research hurdles before
they can be considered market-ready. There are also Batteries are expected to simultaneously fulfil a large
challenges, as well as promising developments, in number of criteria in order to meet challenging
finding suitable substitutions for cobalt, used in combinations of consumer demands, such as high
lithium-ion cathodes, and fluorinated binders. power and high-energy density, long life, low cost
and excellent safety, and with minimal negative
The energy needed to manufacture and charge environmental impact. As this report demonstrates,
batteries is another important consideration. there are certainly many opportunities to make
The energy-intensive production of lithium-ion improvements on existing technologies.
batteries is associated with high environmental
impacts derived from electricity production, Many promising developments are taking place
such as emissions of GHGs and air pollutants. in the ongoing evolution of batteries. This report
Considerable environmental benefits can, presents three case studies of emerging forms
therefore, be reaped by powering battery of battery: solid-state lithium-ion, redox flow
production facilities with renewable energy, and in batteries and printed batteries. These illustrate the
locating battery plants in countries with relatively potential of new battery technologies in meeting
clean energy mixes. societal needs, such as effective energy storage,
and in creating new opportunities for new types of
The environmental impacts incurred by the energy products. The case studies also demonstrate some
used to charge batteries can be reduced by increasing of the pros and cons of different combinations of
roundtrip efficiency, that is, the ratio of energy that design parameters.
discharges from a battery, compared with how
much is put in during charge. An important goal is It is increasingly evident that, for batteries, one size
to minimise the amount of energy that is lost during does not fit all. It is, therefore, important to identify
these charging cycles. the most appropriate type of battery for a particular
application, in terms of both performance and
Extending the lifespan of batteries is also key to environmental quality. This report does not, and
reducing costs, pressures on resources and negative cannot, predict which battery technologies will
impacts of both manufacturing and recycling by come to dominate in future, or which offer the best
reducing the number of times that a battery needs environmental profile. Instead, it serves to highlight
to be replaced. Lifespan can be extended through areas of battery design where improvements can
technological enhancements, as well as by re-using help ensure that future battery technologies are
older batteries, for example, repurposing ex-vehicle as environmentally sustainable as possible and
batteries for stationary energy storage applications. continue to fulfil their valuable purpose.
Re-use and recycling are part of a circular economy
approach. These lower the impacts of resource
consumption and manufacture, provide a secure
supply of secondary materials (in the case of
T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
6
Introduction
It is difficult to overstate the importance of batteries presenting a selection of promising technologies in
to our future as we currently envisage it. Batteries case studies, discussing their potential performance,
are critical in efforts to cut greenhouse gas (GHG) uses and characteristics which contribute to their
emissions and mitigate dangerous levels of climate environmental profile.
change through their role in bringing secure supplies
of clean, low-carbon energy to our homes, businesses The European policy context for batteries
and vehicles. Batteries are also hugely important in
helping power the expanding digital economy and Batteries are a cross-cutting issue, relevant to many
an ever-growing number of portable electronics. areas of policy, including transport, climate action,
energy, waste and resources. Their development,
The use of batteries allows greater penetration of production and use are imperative for Europe in
(intermittent) renewables in the power sector and, the context of its move towards a secure, affordable
thus, helps avoid the negative environmental impacts and climate-friendly energy supply, as part of the
of fossil fuel- or nuclear-based power. This has Energy Union1 strategy, and the competitiveness of
particular environmental advantages for air quality its automotive sector.
and human health, as well as the climate. In relation
to resource efficiency, materials in batteries can be The European Commission has recently proposed
recovered and recycled, some of them indefinitely, that the EU takes up the challenge of becoming a global
whereas fossil fuels – which are valuable for purposes leader in sustainable cell and battery manufacturing,
other than energy production – are burned and lost able to compete with current manufacturing bases
forever. (mainly in Asia). In support of this ambitious goal,
the European Commission launched the European
Battery numbers are set to grow dramatically, Battery Alliance2 cooperation platform in October
particularly with the increase in electric mobility 2017 and endorsed a Strategic Action Plan on
(e-mobility). However, manufacturing and using Batteries3 in May 2018 as part of the Europe
batteries, as well as the way they are treated at the on the Move4 package of sustainable mobility
end of their life, also has environmental impacts. initiatives. The Action Plan aims to put Europe on
a firm path towards leadership in this key industry,
To alleviate these pressures, work is needed to better supporting jobs and growth in a circular economy,
integrate batteries into a circular economy and cut whilst ensuring clean mobility and an improved
their consumption of resources, including their use environment and quality of life for EU citizens.
of some toxic and critical raw materials. Furthermore,
emissions of GHGs and pollutants associated with The Commission promotes a cross-border
their production and use should be reduced. and integrated European approach to battery
manufacturing, which focuses on sustainability
This Future Brief from Science for Environment throughout the value chain, starting with the
Policy provides an overview of technical aspects of extraction and processing of raw materials for
battery design and production which enable the batteries, through to the design and manufacturing
environmental footprint of batteries to be lowered. It phase, and their use, recycling and disposal in a
also shines a light on the future of batteries, by circular economy context.
1. https://ec.europa.eu/commission/priorities/energy-union-and-climate_en
2. https://ec.europa.eu/growth/industry/policy/european-battery-alliance_en
3. https://ec.europa.eu/transport/sites/transport/files/3rd-mobility-pack/com20180293-annex2_en.pdf
4. https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=COM%3A2018%3A293%3AFIN
T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
7
The Batteries Directive5, the only piece of EU high levels of recycling established by the Batteries
legislation exclusively dedicated to batteries, aims Directive.
to minimise the environmental impact of batteries.
The Directive assumes that pollution caused by The European Strategic Energy Technology Plan
the substances contained in batteries is the main (SET-Plan)8, defines research and development
source of negative impacts on the environment priorities on energy and includes a specific Action
These impacts can arise if batteries are landfilled, on Batteries. This Plan is dedicated to promoting
incinerated or improperly disposed of at the end of the competitiveness of EU industry in the global
their life. battery sector as a contribution to the development
and deployment of low-carbon technologies. This is
Faced with these risks, the Directive adopts a achieved through coordination of national research
twofold approach: reducing the use of hazardous efforts and helping to finance projects. In addition,
substances in the composition of batteries on the a New European Technology and Innovation
one hand and, on the other hand, ensuring that Platform on Batteries will be soon established to
batteries are properly managed at the end of their facilitate closer co-ordination of national, private
life (for instance, the incineration of automotive and EU efforts (as described in Europe on the Move
and industrial batteries is prohibited). The Directive documents).
is currently undergoing review6 and, as a result,
will contribute to an innovative and future-proof Numerous research and innovation projects have also
regulatory framework for batteries. been supported by the successive EU's Framework
Programmes for Research and Innovation. A
With regards to the colllection of automotive recently published report9 (Projects for Policy series)
batteries, the End-of-life Vehicles Directive7 has draws the main policy conclusions on the basis of
been instrumental. It has contributed to meeting the 135 projects supported, which received a total of
€555 million in EU and private funds.
5. http://ec.europa.eu/environment/waste/batteries/index.htm
6. http://ec.europa.eu/environment/waste/batteries/evaluation.htm
7. https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:02000L0053-20130611&qid=1405610569066&from=EN
8. https://ec.europa.eu/energy/en/topics/technology-and-innovation/strategic-energy-technology-plan
9. https://trimis.ec.europa.eu/content/batteries-major-opportunity-sustainable-society
T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
8
Section 1. An introduction to batteries
This section introduces key technical concepts to aid 1.1 How a battery works: the basics
comprehension of the report. It also outlines some
of the main issues that influence the development of A battery converts chemical energy into electrical
new battery technologies. energy. It is typically made of three major active
components: an anode, a cathode and an electrolyte.
Batteries come in many shapes and sizes – from the These are each made of a different material and, in very
size of a postage stamp to the scale of a warehouse basic terms, chemical reactions between the materials
– and use numerous chemical compositions. generate energy.
This diversity creates a range of opportunities for
energy management and for powering electronics The chemical reactions mainly occur when the battery
and vehicles. It also presents varied challenges is plugged into an external circuit that connects the
in determining their environmental impact or anode and cathode, for example, when it is placed
appropriate end-of-life handling (i.e. recycling). into a mobile phone or a car.
e e
Electrons flow from anode to cathode through external
circuit - providing energy to electrical items in the circuit
Ions flow from anode to cathode through electrolyte
e e
i
i i
Anode Electrolyte Cathode
Figure 1. Diagram illustrating key components of a battery, and the flow of ions
and electrons in an electrical circuit
T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
9
The reactions cause electrons and ions to build discharged because the reactions slowly transform
up at the anode. The electrons flow towards the the materials into other chemicals, until they can no
cathode through the external circuit where they longer react. However, it is possible to reverse this
provide electrical power en route (to the phone or car, chemical transformation by providing electric energy
for instance). which switches the direction of both the electrons’
and ions’ flow. Rechargeable batteries, which are
The ions also flow towards the cathode, able to host the chemical reactions involved in two
but through the electrolyte which separates the anode directions, are also known as secondary batteries.
(also known as the negative electrode) and the Non-rechargeable, single-use batteries, are known
cathode (also known as the positive electrode). The as primary batteries.
ions and electrons recombine at the cathode to
complete the circuit and keep the reactions running. Historically, primary batteries have been used to
provide short-term, grid-independent energy to
1.2 Battery architecture portable applications, such as portable electronics.
Until recently, secondary batteries (based on lead-
The anode, cathode and electrolyte make up one cell, acid technologies) have been predominantly used
along with other key components, such as the in automotive applications. Recent years have also
binder, which holds particles of the active material seen the arrival of lighter, energy-dense secondary
together. A battery can be made up of one or more batteries, mostly based on lithium technologies,
cells which are connected to increase the voltage which have contributed to the spread of connected
and/or the total storage capacity of the assembly. communication devices, such as smartphones and
laptops.
The cells can be assembled into a module, and the
modules then placed in a pack, to be inserted into 1.4 Energy, power and energy
the application (e.g. a car). Other key auxiliary management
components, such as cooling equipment or a battery
management system (an electronic system within Different forms of battery will have different energy-
the battery pack for controlling and monitoring the to-power (E/P) ratios. Power refers to the amount
battery), may be needed as part of the overall battery of electricity that can be instantaneously released by
system. a battery, whereas energy is the amount of electricity
stored over time. The ratio is determined by layout,
There are, thus, a number of important components materials and other factors, and affects a battery’s
of batteries and battery systems that do not directly suitability for different applications.
take part in chemical reactions, but which are still
needed to allow its proper functioning. For instance, high energy is a primary concern for
portable electronics, to extend usage time between
1.3 Rechargeability charges, whereas stationary batteries in the electricity
grid, notably batteries used to balance the difference
The materials used for the electrodes and between electricity supply and demand (frequency
electrolyte determine the lifespan and rechargeability regulation), primarily need high power output for
of a battery. In broad terms, batteries become short times. Electric vehicles require both high power
T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
10
(for acceleration) and high energy (to enable a long 1.5 The future evolution of
driving range). battery design
Secondary batteries are also used in the energy sector To meet the future needs of our society,
to store energy from external sources, including a huge improvement in the performance
intermittent renewable supplies (e.g. wind or solar), of batteries is key, with new designs that
and release it when needed. In this usage, these meet specific purposes. Although batteries were,
batteries play a critical role in efforts to mitigate initially, a simple technology, their development
climate change and are often referred to as energy has been very slow compared with other areas of
storage devices, although, technically speaking, electronics. A major research hurdle lies in finding
all batteries store energy. High energy storage is suitable materials for electrodes and electrolytes
a critical consideration for these batteries. Power – that actually work well together without undue
output capabilities are a smaller consideration for compromise to other aspects of a battery’s design.
such applications. There is much trial and error in selecting the best
combination of design parameters.T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
11
The competitiveness of batteries also depends From the perspective of improving environmental
on whether they meet challenging sets of performance, circular economy considerations
consumer demands, whether those are to enable a are particularly important, as re-use and recycling
competitively-priced electric car with a large driving can alleviate many environmental pressures across
range, or to provide more affordable, maintenance- the lifecycle of batteries – including GHG and
free technologies for grid storage (Grey and toxic emissions during production and use, and
Tarascon, 2017). In many cases, and certainly for resource consumption (see Section 2.4). To fully
e-mobility batteries, this means simultaneously embrace these considerations, a new approach to
fulfilling a number of criteria, such as high power battery development is needed in which features
and high-energy density, long autonomy, long life, that support recycling and re-use are built in to the
low cost and excellent safety, while also minimising battery’s basic design (see Section 2.4.3).
their negative environmental impact, for example,
by ensuring that they are easy to re-use and recycle Clearly, technology is only part of the solution to
and based upon abundant resources. At present, no lowering batteries’ environmental impacts. Socio-
battery ticks all these boxes. economic changes also need to be considered, such
as recycling behaviour, consumer behaviour, waste
However, progress is taking place in battery design, management infrastructure and the economic
and there are many promising developments factors that determine whether a recyclable
in the ongoing evolution of batteries which material is actually recycled or not. Both policy
enable improved performance and a better action and technological research are, therefore,
environmental profile. As this report highlights, key. In addition, opportunities to avoid batteries by
many opportunities to reduce the environmental using alternative systems to store energy can also be
footprint of batteries are, very often, accompanied explored.
by better performance. Thus, there are both trade-
offs and synergies to be found among many design A combination of battery technologies is likely
considerations. to be in use in the future, although it is not yet
possible to say which these will be, or to identify
Ultimately, it may not be possible to develop which type(s) will be the most environmentally
the ‘ideal’ battery, which meets all the desired sustainable. However, it is possible to highlight
criteria, and the choice of battery for any given use which areas of battery design need attention in
will involve some compromise. It is increasingly order to ensure that future battery technologies
evident that, for batteries, one size does not fit are as sustainable as possible, whilst continuing
all, and so what is important is to identify the to fulfil their valuable purpose. This report draws
most appropriate type of battery for a particular attention to those areas.
application, in terms of both performance and
environmental quality.T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
12
Section 2. Environmental issues for batteries
While batteries can potentially make our economy and the environmental impacts of the emissions.
greener by reducing our reliance on fossil fuels, we Nonetheless, LCA serves as a useful tool to highlight
also need to consider the environmental footprint ‘hotspots’ of potential environmental pressures,
of batteries themselves. This section highlights while also providing a general picture of overall
existing environmental issues with current battery environmental performance.
technologies, particularly lithium-ion (see Box 1),
and discusses how they could be addressed in the 2.1 Material issues
design of future batteries, including those currently
in development. A wide range of materials are used to make electrodes
and electrolytes, which can present issues in relation
This is not an exhaustive list of issues, and does not to resource availability, toxicity, safety, production
identify the ‘greenest’ battery, but presents a number and recycling or disposal impacts. Electrode
of priority areas. It also shows some of the challenges materials are particularly important to improving
and opportunities associated with balancing the environmental profile of batteries (Larcher and
performance and sustainability characteristics. Tarascon, 2015).
Lifecycle analysis (LCA) 2.1.1 Resource availability
This section draws heavily on lifecycle analysis Soaring demand for batteries, alongside the huge
(LCA) research, which aims to calculate a product’s size of future energy storage installations, is going to
environmental footprint across a range of impacts, increase pressure on material resources. It is generally
including energy consumption, GHG emissions and accepted that there are sufficient reserves of most
effects of pollution, and over the product’s lifecycle of the key constituents of batteries. However, their
– from raw material acquisition or generation from supply in raw form is clearly not endless and may
natural resources to final disposal. one day become a problem unless action is taken.
LCA can also be used to develop environmental This is particularly true for lithium-ion technologies,
labelling systems for products. Technical guidance which are expected to meet an important part of near-
for conducting Product Environmental Footprint term demand for batteries. Research suggests that there
assessments for rechargeable batteries has been are enough reserves of most of the main ingredients of
recently published10 (see Box 3). lithium-ion electrodes to meet a modest but foreseeable
rise in demand over the next decade (e.g. 10 % share
LCA does carry various uncertainties; the models of electric vehicles in the global fleet), namely lithium,
used do not capture the full picture in a number of manganese, nickel and natural graphite (Olivetti et al.,
ways, for instance, they simplify the industrial value 2017).
chain from the mine to the battery, the emissions
produced during each step of the value chain,
10. http://ec.europa.eu/environment/eussd/smgp/pdf/PEFCR_Batteries.pdfT O W A R D S T H E B A T T E R Y O F T H E F U T U R E
13
BOX 1.
Lithium-ion: today’s battery of choice
Lithium-ion technologies are the fastest growing
form of battery on the worldwide market, with
the potential to dominate the market in the
short term. At the global and EU level, lead-
acid technologies are expected to still prevail in
2025 in terms of volume, but the lithium-ion
market is expected to become greater in terms
of value from 2018 onwards.
Lithium-ion batteries have been used for some
time in portable electronics, but they have recently
become the technology of choice for e-mobility.
Lithium cells developed for the e-mobility sector
are, very often, also used in other applications –
namely stationary energy applications – given the
economies of scale this sector creates, although
lower performance cells (for example, in terms of
energy and power density) are also able to meet
the needs of stationary applications.
Lithium-ion is not a single technology, but a family of technologies. Although they
all rely on lithium as the shuttling ion (i.e. the ion that moves between cathode and
anode), different versions of the technology combine the lithium with a variety of
other materials to confer different properties.
Each type of lithium-ion battery is typically referred to as some form of abbreviation of
its active cathode materials, for instance, Lithium Cobalt Oxide, one of the most common
types (used in portable batteries, for instance), is called ‘LCO’, while Lithium Nickel
Manganese Cobalt Oxide is named ‘NMC’ (increasingly used in mobility applications).
The use of lithium-ion batteries is expected to accelerate in the near future. Their design
is likely to evolve during this time, but scientists believe that they may soon reach
their performance limits, particularly in terms of their energy density. Thus, in addition
to efforts to develop future evolutions of lithium-ion, the quest is now on to identify
potential alternatives that offer better performance with an improved environmental
profile.T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
14
extreme scenario
calculations suggest
(Weil, Ziemann and
Peters, 2018, Vaalma et
al., 2018).
In addition, although
lithium, manganese,
nickel and natural
graphite may currently
have abundant deposits,
they are mined in a
very small selection of
countries (primarily
outside the EU),
which creates potential
supply risks (European
Commission, 2018).
Another important
issue is the significant
quantity of critical
raw materials for the
EU (defined as those
which are both of high
economic importance
for the EU and have
a high risk of supply
disruption)11 embedded
in many battery
However, despite available reserves, concerns technologies, such as antimony, cobalt, natural
remain surrounding the supply of battery materials, graphite, indium and some rare earth elements,
especially if there is a sharp increase in demand which depending on the battery’s chemistry (Mathieux et
pushes up market prices. Further, there are unlikely al., 2017).
to be enough reserves of cobalt, and potentially
lithium, for 100% electrification of the world’s
vehicle fleet under continuous growth conditions,
11. http://ec.europa.eu/growth/sectors/raw-materials/specific-interest/critical_enT O W A R D S T H E B A T T E R Y O F T H E F U T U R E
15
2.1.2 Environmental impacts reflected in LCAs, because toxic substances leak
from mine tailings. It is also responsible for high
2.1.2.1 Electrode materials levels of sulphur oxide emissions which are released
during the smelting step of virgin cobalt and nickel
Mineral extraction and metal refining represent recovery (Dunn et al., 2015).
the most important contributors, among life-cycle
stages, towards the total environmental impacts Cobalt and nickel are often mined in countries with
incurred during the lifecycle of any type of battery. less stringent environmental and health and safety
regulations than in Europe. Significant social issues
In the case of lead production for batteries and are also associated with cobalt mining, such as the use
sheets, it is estimated that the main contributors of child labour and dangerous working conditions
to environmental impact are mining and (Tsurukawa, Prakash and Manhart, 2011). While
concentration, and smelting (Davidson, Binks and there are significant uncertainties in available toxicity
Gediga, 2016). In the case of lithium-ion batteries, data, it can be agreed that efforts to minimise leakage
the mining of some electrode materials, particularly of toxic substances from mine tailings will benefit the
cobalt (see Box 2) and nickel, significantly increases environmental performance of batteries (NordelÖf et
the environmental footprint of these batteries as al., 2014).
12. https://www.ila-lead.org
13. https://echa.europa.eu/candidate-list-tableT O W A R D S T H E B A T T E R Y O F T H E F U T U R E
16
BOX 2.
Cobalt
Cobalt is a cathode material in lithium-ion batteries that needs addressing urgently.
It has a risky supply chain, partly due to geopolitical issues. The majority (64%) of
the world’s cobalt is mined in the Democratic Republic of Congo, a politically instable
country, as a by- or co-product of copper or nickel, and so its supply also depends on
demand for these parent materials. There are notable industry efforts to lower the
cobalt content of batteries, but if electric vehicles are to make up a significant share of
the fleet, cobalt will remain in demand and risks associated with its supply will persist
(Olivetti et al., 2017).
Cobalt is important in giving lithium-ion batteries their high energy density and is,
therefore, difficult to substitute. Cobalt-free cathodes are available, which are lower in
energy density but are suitable for certain applications (see Section 2.1.3.2).
Increasing the efficiency in the use of the resources The sulphuric acid used in lead-acid batteries is a
concerned, through recycling or re-using, is the good example of this problem. However, lithium-
most obvious way to reduce the impact of extractive ion batteries are not risk-free either. As well as being
activities. Lead may be considered a success story, in highly flammable, current lithium-ion electrolytes
this respect. According to data from the International are potentially able to form a toxic atmosphere if
Lead Association12, more secondary (recycled) lead accidentally released in a (semi-) enclosed space, such as
than primary (raw) lead is used globally and within the a garage, tunnel (in the event of a car crash, for instance)
EU. It should be noted, however, that the European or recycling facilities (Lebedeva and Boon-Brett, 2016).
Chemicals Agency (ECHA) recently added lead metal This is due to the solvents they use and the formation of
on to its Candidate List of Substances of Very High hydrogen fluoride (HF), a highly toxic14 and corrosive
Concern (SVHCs)13 due to its toxic properties, in decomposition product of the lithium salt (LiPF6)
addition to already listed lead compounds. commonly used in the electrolytes. HF forms when
the salt comes into contact with atmospheric moisture
2.1.2.2 Electrolyte risks or traces of water.
The type of electrolyte used has a major impact on 2.1.2.3 Binders
the performance of a battery, but a compromise may
need to be reached between electrolyte performance Binders hold the components of the battery together.
and safety. Some substances used in electrolytes can They are environmentally problematic because they
potentially have negative impacts on human health. are typically made of fluorinated substances, whoseT O W A R D S T H E B A T T E R Y O F T H E F U T U R E
17
production is energy-intensive and associated with of reducing pressure on resources and the toxic
the emission of ozone-depleting substances (Peters impacts caused by their production. Likewise, the
& Weil, 2017). Furthermore, they need volatile and switch to more abundant, less harmful materials
toxic solvents for processing, are unsuitable for recycling will also help ensure the better use of resources.
and do not biodegrade (Richa, Babbitt, Gaustad, &
Wang, 2014). 2.1.3.1 Energy density
Binders also present some safety concerns: at high Energy density is critical for portable electronics and
temperatures (for example, if a lithium-ion battery e-mobility, where large, heavy batteries are impractical
overheats or catches fire), together with lithium salts, or undesirable. It is also of relative importance for
they can contribute to the formation of HF (Larsson stationary batteries in homes with limited space. These
et al., 2017). applications need as much energy as possible per unit
of volume (measured in litres) and weight (measured in
2.1.3 Material issues: going forwards kg). Higher energy density also allows smaller, lighter
batteries to be used in appliances, thereby also enabling
An obvious means to reduce both our reliance on smaller, lighter appliances. Additionally, a high density
limited resources and the negative impacts of mining, battery can work longer on single charging than a
no matter where extractive activities take place, is same-sized battery with lower density, meaning that
to increase the supply of secondary (recycled) raw the battery needs recharging less often – this is critical
materials. The way batteries are handled at their end- in extending the range of electric vehicles, for instance.
of-life also affects their toxicity; recycling and other
forms of end-of-life treatment are discussed in detail in A higher density is also associated with lower
Section 2.4. production impacts; for a low-energy-density battery, a
greater amount of battery is needed to provide the same
The development of higher density batteries, amount of energy, increasing the impacts accordingly.
which need less material overall, is another means
Battery Advanced Sodium- Sodium- Lithium- Redox flow
lead-acid sulphur nickel-chlorine ion
Energy density 25-50 120-150 95-120 100-200 10-50
(Wh/kg)
Table 1. Gravimetric energy density (Wh/kg) of main battery technologies used for energy storage.
Adapted from: Alotto, Guarnieri and Moro (2014).
14. https://emergency.cdc.gov/agent/hydrofluoricacid/basics/facts.aspT O W A R D S T H E B A T T E R Y O F T H E F U T U R E 18 Figure 2. Schematic illustration of a battery’s production chain, from the material level via the battery cell, to the battery system level. In each step, inactive components are added and assembled into a key ‘building block’ for the battery system, which ‘dilute’ the energy provided by the active materials. In assessing energy density, it is important to consider energy output, certain inactive materials or minimum each step in a battery’s production chain, that is, the amounts are essential to ensure key performance and process of assembling parts for the complete battery safety requirements. Studies often report on the system, including peripheral components, such as the energy density of new battery technologies based battery management system (Placke et al., 2017). The on laboratory tests on the active materials alone. It chain begins with the ‘active’ materials used in the anodes is challenging to predict what the energy density of and cathodes, which give the battery its source of energy those technologies will be if and when they eventually through chemical reactions. Each additional ‘inactive’ come into commercial use. For more realistic component, such as binder (see Section 2.1.2.3) or projections of density, it is important to predict the housing system, added to the battery ‘dilutes’ the energy effects of the wider battery pack or system on density density in the process of achieving the final battery (Berg et al., 2015), while also recognising that these (see Figure 2). While the weight and volume of these predictions carry uncertainties. inactive components must be minimal for a maximum
T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
19
There is a limit to the effects of active materials’ would drastically reduce their energy density
chemistry on energy density. Thus, further (Gallagher et al., 2014).
improvements are needed to inactive cell material
components, which reduce the weight and volume, as • Sodium-ion. This is ‘without a doubt the most
well as changes in how the whole battery is engineered appealing alternative to lithium-based battery
and organised on a system level (Placke et al., 2017). technology, from the viewpoint of sustainability’
(Grey and Tarascon, 2017). It contains no
2.1.3.2 Alternative materials lithium, and sodium is an abundant resource
that is not associated with any geopolitical
Future cathode materials: examples issues. It is less energy dense than lithium-
ion, but progress is expected and it has good
In conjunction with the pursuit of greater energy potential for stationary energy storage systems
density, scientists are also exploring technologies which where weight and volume are less critical.
use more plentiful and/or safer cathode materials. The This chemistry could also have potential to
following examples of developing technologies briefly meet transport sector needs in the long run,
illustrate the use of some of these materials in relation according to the European SET-plan on
to their abundance, toxicity and energy density: Batteries (see Introduction). Its current lower
energy density does increase demand for other
• Lithium-sulphur. These are considered one of components for providing the same storage
the most promising next-generation batteries capacity, however. In a LCA study, evaluated
for electric vehicles. While they still contain that, overall, sodium-ion batteries have fewer
lithium, they avoid nickel and cobalt. Further, toxic impacts than lithium-ion batteries.
they use sulphur in the cathode which is
cheap and abundant. calculate that the toxic It should be noted that these technologies are not yet
impacts of a lithium-sulphur battery are 22% ready for market application and significant research
lower than for a standard lithium-ion battery efforts are needed, in particular to address safety issues,
(NMC111), mainly because they avoid nickel long-term quality and their lifespan.
and cobalt mining and production activities.
However, lithium-sulphur batteries currently Moreover, material abundance, energy density and
have low volumetric energy density (i.e. they toxicity clearly form only part of the environmental
are lightweight but big). picture. For example, although lithium-sulphur
batteries may be less toxic than lithium-ion batteries,
• Lithium-air. These use oxygen, an unlimited when a wider range of environmental impacts are
resource, for the positive electrode. In theory considered (e.g. GHG emissions), they are unlikely to
they could reach energy densities ten times be more environmentally friendly overall than lithium-
greater than most batteries currently on the ion batteries. This is owing in part to more energy-
market, based on assessments of their active intensive production processes and solvents needed
materials alone. However, at a system level, to manufacture the cathode (Cerdas et al. 2018).
they are likely to require significant peripheral Purifying oxygen for lithium-air batteries is similarly
components to avoid the pure oxygen energy-intensive (Larcher and Tarascon, 2015; Grey
degrading in ambient air, such as oxygen tanks and Tarascon, 2017).
or air separation units, which, in practice,T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
20
Non-fluorinated binders 2.2 Energy issues: production
and charging
Greener alternatives to fluorinated binders
are in development and use (to some extent).
Carboxymethylcellulose is a promising alternative
2.2.1 Source of energy for production
in terms of ensuring good performance of lithium-
The carbon-intensity of energy used to
ion batteries, while also being much cheaper than
manufacture batteries has a significant impact
conventional binders, such as polyvinylidene
on their environmental footprint. Lithium-ion
fluoride. It is made of cellulose, which is derived
battery production is very energy-intensive and
from plants and is thus renewable, and is water-
involves a series of complicated manufacturing
soluble – so toxic solvents are not needed. Studies
processes, including cell assembly in severe dry
have found it to have comparable, or even superior,
room conditions, with extremely low humidity, in
performance to conventional binders in lithium-
order to avoid the formation of HF (see Section
ion batteries ( Jeong et al., 2012; Mancini et al.,
2.1.2.2)
2011). It is already successfully used in lithium-
ion anodes, but is not suitable for all technologies
Around 328 Wh of energy is needed to produce
as some electrodes are moisture sensitive or water
just 1 Wh of lithium-ion battery capacity – this
soluble (Larcher and Tarascon, 2015). It is also, at
is the average figure taken from 19 studies which
present, unsuitable for cathodes, however, there is
assessed cumulative energy demand for seven types
promising research to indicate that it will probably
of lithium-ion battery (Peters et al., 2017). The
become feasible in future (Chen et al., 2017).
total mean GHG emissions associated with the
Cobalt substitution production of 1 Wh of storage capacity are 110 g of
CO2eq, according to same review.
Lithium-ion battery manufacturers are gradually
reducing the cobalt content of cathodes. Non- Lithium-ion batteries are usually manufactured
cobalt-containing cathodes, such as manganese in Asian countries with an electricity mix that is
spinels (LMO) and lithium-iron-phosphate different to most European countries. It is possible
(LFP), are also available. They have a lower energy to compare the GHG emissions of manufacturing
density, but are attractive for some applications. batteries based on different energy sources. Thus,
For instance, the high stability and high power for instance, NMC lithium-ion cells for electric
capability of LFP makes it a contender for large vehicles that are currently manufactured in South
scale applications, such as those in electric grids. Korea, which has an energy mix dominated by coal,
At present, some consider LFP the most attractive nuclear and gas, have a global warming potential
electrode material, sustainability-wise (Larcher that is 60% higher than if they were produced
and Tarascon, 2015). with a 100% hydropower-based electricity supply
(Ellingsen et al., 2014).
15. https://www.wired.com/story/ev-green-battery-factory-in-the-netherlands-competes-with-the-gigafactory/T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
21
The most efficient way of reducing GHG are very efficient, at over 90%. Over a battery’s
emissions from the production of batteries is to lifetime, a 10% loss is still responsible for some
manufacture cells in facilities powered entirely by significant environmental impacts, however, which
renewable energy sources (Ellingsen, Hung and can be as great as the impacts of production of
StrØmman, 2017). Promisingly, there are some the battery itself, in terms of energy demand and
notable new ‘gigafactories’ (large battery factories) GHG emissions. The internal inefficiencies for
in development, including what is reported to be every 1 kWh of electricity stored in the battery
Europe’s largest battery factory when it is fully cause 0.3 kWh of energy demand and emissions
running in 2023 in Sweden, which is expected to of 46.7 g CO2eq, assuming an average European
be powered by hydroelectricity15. electricity mix for 2012 (Peters et al., 2017).
Although emissions vary according to the local Small efficiency improvements can lead to sizeable
source of energy for the production plant, in the environmental gains. For instance, just a 2%
long term it can be expected that emissions will improvement in efficiency, from 90% to 92%,
fall with increased adoption of renewable sources would lead to a 7% reduction across a range of
of energy and the development of new and cleaner environmental impacts associated with producing
technologies. the electricity used to charge batteries (assuming
a European electricity mix). These include
2.2.2 Roundtrip efficiency potential toxic impacts of pollutants on humans,
eutrophication of marine and fresh waters, and
‘Roundtrip efficiency’ refers to the amount of impacts of acidifying pollutants on ecosystems
energy that comes out during discharge of a (Peters et al., 2016).
secondary battery (e.g. when it is used to power an
appliance), compared with how much was put in to Although roundtrip efficiency is important, it should
charge it. The battery loses some energy during each be noted that it can come with trade-offs. In the
one of these charging cycles. A higher roundtrip case of vanadium redox flow batteries, for instance,
efficiency means that less energy is lost during these (see Case Study 2), additional materials or energy
cycles, which lowers the environmental impact inputs may be needed to increase efficiency, such as
associated with the production of energy used for adding sulphuric acid to reduce internal resistance
charging, such as GHG emissions from fossil fuel (Arbabzadeh et al., 2016).
combustion. In addition, by reducing the loss of
waste heat, a high roundtrip efficiency can lead to As with manufacturing, the energy source used
increased energy density (see Section 2.1.3.1) of to charge secondary batteries – whether carbon-
the whole battery system, because it reduces the intensive or low-carbon – will strongly influence
size of auxiliary equipment used for cooling. the environmental impacts of battery usage. It can
be expected that these impacts will fall per unit of
Typical lead-acid batteries have an efficiency over output in the future as the share of renewable energy
70-80% (Reddy, 2010), i.e. 20-30% of energy is in the electricity mix increases in concurrence with
lost during charging cycles. Lithium-ion batteries ongoing battery development for energy storage.T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
22
2.3 Lifespan
A long battery lifespan reduces the number of In reducing environmental impact, increasing
times that a battery needs to be replaced. This is lifespan is one of the most important aspects
particularly critical for usage in energy storage of battery design to focus on when developing
and electric vehicles, which have longer lifespans alternatives to lithium-ion batteries. This can be
than most portable electronics. As well as reducing illustrated using the example of sodium-ion batteries,
costs, a long lifespan reduces pressures on resources an emerging technology (see Section 2.1.3.2).
and any negative impacts of both manufacturing Their cycle life is not yet clear, but at 2000 cycles,
and recycling, such as energy consumption. In they would be environmentally comparable to a
addition, it can extend the use of the device in number of lithium-ion batteries per kWh of storage
which the battery is placed, for instance, it may capacity. At 3000 cycles, however, they would be
reduce instances of consumers discarding working environmentally superior to nearly all lithium-
smartphones due to battery End-of-Life (EoL). ion batteries, with the exception of the LFP–LTO
type (LFP cathode and LTO anode) which has an
A battery’s lifespan can be measured in two ways: exceptionally high cycle life of 13,850 (Peters et al.,
1.) in terms of ‘calendar years’, which is the length 2016).
of time a battery can be stored with minimal
discharges before its capacity diminishes, and New ‘in situ’ methods to monitor batteries in
2.) in terms of its ‘cycle life’, that is, the number of operation for signs of degradation, i.e. monitoring
times it can be recharged and discharged before it systems within a battery itself, could provide
becomes unsuitable for a given application. This information that helps extend the lifespan of
is usually when it can only be charged up to 80% batteries in several ways (Grey and Tarascon,
of initial capacity, given that the battery degrades 2017). Firstly, improved monitoring could provide
quickly after this point.T O W A R D S T H E B A T T E R Y O F T H E F U T U R E
23
insights that inform the design of new materials Although no official data are reported to the
and improvements to existing technologies. European Commission, it can be stated that
Monitoring could also be used to perform a ‘health the level of recycling of lead-acid automotive
check’ on batteries in use: sensors inside a cell could batteries within the EU is very high16. Several
transmit information on battery faults to the ‘outside factors explain this high level. Lead-acid batteries
world’ through an optical fibre, allowing the fault to are relatively simple products, with few materials
be repaired. This ‘health check’ could also support and a basic design that is standardised across the
a market for second-hand batteries, by verifying the market. In addition, a well-established professional
history of each battery and allowing appropriate network ensures high levels of collection of spent
pricing and insurance as it enters new applications. batteries, which lowers costs and increases benefits
It should be noted, however, that these monitoring for recyclers.
systems are likely to come with trade-offs, such
as increased demand for materials or additional Conversely, recycling lithium-ion batteries is
recycling challenges. technologically challenging, for many reasons.
They contain a large number of blended materials,
which makes recycling more complex than for
2.4 End-of-Life (EoL) treatment simpler technologies like lead-acid, and a battery
pack for an electric vehicle or energy storage is
Circular economy End-of-Life (EoL) approaches,
likely to contain 100 or more individual cells. The
such as re-use and recycling, provide a number of
array of chemical compositions for the electrodes,
environmental benefits. Recycling provides a secure
which vary by manufacturer and battery function,
and domestic source of secondary raw materials,
adds a further complication, especially as the
and reduces environmental impacts associated with
composition is not labelled for the recycler’s
extracting raw materials, such as GHG emissions
information. It is difficult for recycling companies
and the ecological and toxic impacts of mining.
to adapt to the continually evolving composition of
By increasing the lifespan of batteries, re-using can
electrodes, which may never standardise (Gaines,
contribute to a more efficient use of resources.
2014; Heelan et al., 2016). Moreover, the two main
methods of recycling for lithium-ion batteries are
2.4.1 Recycling
energy intensive.
In addition to increasing the efficiency in the use of
Spent lithium-ion batteries are a pressing concern,
resources, recycling provides direct environmental
given their high number. Globally, it is predicted
benefits. For instance, the GHG emissions of
that there will be over 25 billion by just 2020,
an LMO lithium-ion battery could be reduced
driven largely by the rise in electric vehicles
by up to 50% over its lifetime if it used recycled
(Zeng, Li and Singh, 2014). Within the EU,
cathode, aluminium, and copper instead of entirely
these batteries cannot be landfilled as they leach
virgin materials (Dunn et al., 2012). Moreover,
substances that are potentially toxic and can also
recycling LCO batteries results in a reduction
explode. Likewise, they cannot be incinerated as
in SOx emissions by almost 100%, largely because
the ashes remain toxic in landfill (Winslow, Laux
it avoids the SOx-intensive smelting step of virgin
and Townend, 2018).
cobalt recovery (Dunn et al., 2015).
16. EUROBAT estimates it at 99.5 %: http://www.eurobat.org/environment-health-safety/recyclingYou can also read
