SONOCHEMICAL SYNTHESIS OF AU/PD NANOPARTICLES ON THE SURFACE OF LIFEPO /C CATHODE MATERIAL FOR LITHIUM-ION BATTERIES
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Japanese Journal of Applied
Physics
BRIEF NOTE
Sonochemical synthesis of Au/Pd nanoparticles on the surface of
LiFePO₄/C cathode material for lithium-ion batteries
To cite this article: Kotaro Yoshida et al 2021 Jpn. J. Appl. Phys. 60 SDDD06
View the article online for updates and enhancements.
This content was downloaded from IP address 46.4.80.155 on 19/09/2021 at 20:26Japanese Journal of Applied Physics 60, SDDD06 (2021) BRIEF NOTE
https://doi.org/10.35848/1347-4065/abeff1
Sonochemical synthesis of Au/Pd nanoparticles on the surface of LiFePO₄/C
cathode material for lithium-ion batteries
Kotaro Yoshida1, Hirokazu Okawa2*, Yuki Ono3, Takahiro Kato2 , and Katsuyasu Sugawara2
1
Department of Engineering Science, Akita University, Akita 010-8502, Japan
2
Graduate School of Engineering Science, Akita University, Akita 010-8502, Japan
3
Graduate School of Engineering and Resource Science, Akita University, Akita 010-8502, Japan
*
E-mail: okawa@mine.akita-u.ac.jp
Received December 2, 2020; revised January 25, 2021; accepted March 18, 2021; published online April 6, 2021
With the aim of investigating the deposition of Au/Pd core–shell nanoparticles (NPs) on cathode materials to decrease charge transfer resistance,
Au/Pd core–shell NPs were successfully synthesized and deposited on LiFePO4 coated with carbon (LiFePO4/C) using ultrasound irradiation.
Transmission electron microscopy observation confirmed that dispersed Au/Pd NPs with an average particle size of 7.2 nm were deposited on
LiFePO4/C. An X-ray diffraction measurement evidenced a peak shifting from 38.2° to 39.1° upon calcination at 400 °C in Ar atmosphere, which
can be attributed to the phase transition of the Au/Pd NPs from core–shell to alloy. © 2021 The Japan Society of Applied Physics
Lithium iron phosphate (LiFePO4, LFP) is a very attractive having a core–shell structure on the surface of LFP/C using
cathode material for lithium-ion batteries because of its high ultrasound irradiation. Benefiting from the high dispersion
volumetric capacity (589 mAh cm−3) and its high thermal characteristics of Au NPs deposited on the LFP/C surface,
stability by P–O covalent bonding.1,2) Unfortunately, LFP dispersed Au/Pd core–shell NPs with a smaller size than that
shows low electronic conductivity (1.0 × 10−8–10−10 S m−1) of Au NPs can be expected to be obtained at the same
and low ion diffusivity,3) which limits its practical utilization. molarity of the metal ions.
To overcome these problems, several approaches including In our previous study, we investigated the optimum
miniaturization of LFP grains,4,5) covering LFP grains with synthesis conditions for Au/Pd NPs, such as 2-propanol
carbon as current collector (LFP/C),6–8) or doping other concentration and ultrasound irradiation time, and confirmed
elements into the lattice of LFP9,10) have been studied. In the deposition of Au/Pd NPs on the carbon surface.23) In this
addition, the deposition of noble metal nanoparticles (NPs) study, we observed the size and morphology of Au/Pd NPs
on the LFP surface to improve the electronic conductivity has deposited on acetylene black (AB), and investigated the
been examined. In this regard, Morales et al. reported Au deposition of Au/Pd NPs on the LFP/C surface which could
sputtering on LFP grains with a theoretical thickness of be a reductant for Au(III) and Pd(II). Finally, we confirmed
25 nm, resulting in an improvement of the electronic an effect of LFP/C on the synthesis of Au/Pd NPs using
conductivity.11) However, the battery performance was not ultrasound irradiation. At first, we investigated the synthesis
significantly improved because Au hampers the lithium-ion of Au/Pd NPs on the surface of AB using ultrasound
diffusion from/into LFP. Synthesis of metal NPs using irradiation. 0.02 g of AB (Denka corp.) was added into a
ultrasound irradiation is possible.12,13) Okawa et al. reported flask containing 40 ml of 2-propanol (Wako) solution
that Au NPs were synthesized and deposited on the surface of (0.325 M). 2-propanol can enhance the reduction of Au(III)
carbon of LFP/C using ultrasound irradiation.14) The synthe- to Au and Pd(II) to Pd using ultrasound irradiation24) and
sized Au NPs were dispersed on LFP/C and the design of facilitate the dispersion of carbon, which is hydrophobic in
depositing Au NPs on carbon was able to avoid intercept of the reaction solution. Dissolved gas in the solution was
Au for lithium-ion diffusion during charge/discharge. purged with Ar (100 ml min−1) for 30 min. Considering the
Saliman et al. also synthesized and deposited Pd NPs on report by Saliman et al., in which the best battery character-
LFP/C using ultrasound irradiation.15) However, at a differ- istic was attained using a 0.5 mM solution of Pd(II),15) a
ence with Au NPs, these primary particles were agglomer- solution containing 0.25 mM Au(III) and 0.25 mM Pd(II) was
ated. Nevertheless, the charge transfer resistance was suc- prepared in the flask by mixing 5 ml of a 2.5 mM Au(III)
cessfully decreased and battery characteristics were improved solution prepared using hydrogen tetrachloroaurate(III) tetra-
by using both noble metal NPs. hydrate (Wako) and ion-exchanged water and 5 ml of a
The synthesis of Au/Pd core–shell NPs using ultrasound 2.5 mM Pd(II) solution prepared using palladium(II) sodium
irradiation has also been reported.16–22) Nitani et al. reported chloride trihydrate (Wako) and ion-exchanged water. These
that Au/Pd core–shell NPs with an average particle size of Au(III) and Pd(II) solutions were added into the 2-propanol
8.3 nm were synthesized from HAuCl4 and Na2PdCl4 using solution and the total amount of the reaction solution in the
ultrasound irradiation.16) The particle size and deposition flask was 50 ml. After that, ultrasonic irradiation was
characteristics of NPs are known to depend on the concen- performed at approximately 20 °C using an ultrasonic gen-
tration of Au and Pd ions. Mizukoshi et al. reported that Au/ erator (KAIJO TA-4021, 200 W) with a submersible trans-
Pd core–shell NPs synthesized with a high Pd content tend to ducer (KAIJO) at a frequency of 200 kHz for 20 min. The
be relatively smaller and exhibit finer dispersion than those experimental setup was the same as that used by Saliman
with a high Au content.17) et al.15) The ultrasound was indirectly irradiated from the
Despite these advances, the deposition of Au/Pd core–shell bottom of the flask through water in a tank, and
NPs on cathode materials to decrease charge transfer the ultrasound power that reached the reaction solution in
resistance has not been studied yet. With this aim, we study the flask was determined to be 8.7 W by calorimetry method.
in this paper the synthesis and deposition of Au/Pd NPs Au/Pd NPs deposited on AB (AB·Au·Pd) were thereby
SDDD06-1 © 2021 The Japan Society of Applied PhysicsJpn. J. Appl. Phys. 60, SDDD06 (2021) K. Yoshida et al.
sonochemically synthesized. Then, the sample was passed particle size was calculated by counting the sizes of 100
through a 0.2 μm pore size membrane filter (Merck Millipore particles in TEM images. Moreover, Au/Pd NPs heated at
Ltd.). Inductively coupled plasma measurement was con- 100 °C–500 °C were observed using TEM, and the sizes of
ducted to confirm the concentrations of Au and Pd in the these particles increased with an increase in the temperature.
filtrate. The absence of Au and Pd in the filtrate indicated that Cybula et al. have also reported the growth of the Au/Pd
all Au and Pd were deposited on AB. The sample was dried core–shell NPs by heating.25) The average sizes of Au/Pd
in vacuum at 55 °C overnight and then subjected to powder NPs heated at 100 °C, 200 °C, 300 °C, 400 °C, 500 °C were
X-ray diffraction (XRD) measurement. determined to be 8.6, 8.7, 11.2, 18.5 and 21.3 nm, respec-
Figure 1 shows the XRD patterns of the sample (left) and tively. Next, we investigated the deposition of Au/Pd NPs on
magnification in a 2θ range of 37°–42° showing the peaks the surface of LFP/C (LFP/C·Au·Pd) using ultrasound. LFP/
attributed to Au and Au/Pd (right). The XRD peak of the C [carbon amount in LFP/C: 2 wt%, median diameter (D50):
sample after ultrasound irradiation is denoted as “Before 2–4 μm] was purchased from TATUNG FINE CHEMICALS
heating” in Fig. 1. The presence of peaks corresponding to CO. The synthesis of LFP/C·Au·Pd was conducted similarly
carbon and Au was confirmed from Fig. 1(a). However, a as that of AB·Au·Pd, except using 0.1 g of LFP/C instead of
peak corresponding to Pd was not observed. It is known that carbon. After filtration and vacuum drying, the obtained LFP/
the peak of Pd could not be detected for thin Pd coatings on C·Au·Pd sample was subjected to XRD measurement. The
the surface of Au NPs. Nakazawa et al. reported that a peak result is shown in Fig. 3 (left). The XRD pattern of LFP was
corresponding to Au shifted due to the formation of an Au/Pd retained after the LFP/C·Au·Pd synthesis process using
alloy after calcination of Au/Pd core–shell NPs immobilized ultrasound, which indicates that ultrasonic irradiation did
on a porous silica matrix at 400 °C in H2 gas atmosphere.18) not alter the olivine structure of LFP. In addition, peaks
The peak shift would come from alloying of Au and Pd from attributable to Au were observed, whereas no peak of Pd was
core–shell structure. Therefore, we investigated the occur- detected. Therefore, the formation of a core–shell structure of
rence of a similar peak shifting in the XRD patterns of the Au/Pd NPs was confirmed, which underwent peak shifting
synthesized Au/Pd NPs upon heating at different tempera- upon heating. The XRD patterns of LFP/C·Au·Pd heated at
tures (100 °C, 200 °C, 300 °C, 400 °C, and 500 °C) for 1 h in 300 °C and 400 °C in Ar gas atmosphere for 1 h are shown in
Ar atmosphere [Figs. 1(b)–1(f)]. Although a peak around Fig. 3 (right), revealing a peak broadening and shifting from
25.6° corresponding to carbon did not shift by heating, the 38.2° to around 39° after calcination at 400 °C. Figures 2(b)
peak at 38.2° corresponding to Au shifted to higher values and 2(g) show the results of TEM observation of the Au/Pd
above 300 °C, eventually reaching 39.1° corresponding to NPs deposited on LFP/C without calcination. Moreover, Au
Au/Pd at 400 °C, which can be attributed to the formation NPs synthesized using concentrations of 0.25 and 0.5 mM,
change from an Au/Pd core–shell structure to an Au/Pd alloy. and Pd NPs synthesized with a concentration of 0.5 mM were
This result suggests that the synthesized Au/Pd NPs could observed to compare the particle size upon deposition
have a core–shell structure. The presence of spherical NPs [Figs. 2(c)–2(e) and 2(h)–2(j)]. Au/Pd NPs and both types
with an average size of 8.6 ± 0.59 nm was confirmed by the of Au NPs were confirmed to be deposited on the surface of
transmission electron microscopy (TEM) images of LFP/C and dispersed, whereas particle agglomeration on
AB·Au·Pd shown in Figs. 2(a) and 2(f), indicating the LFP/C was observed for Pd NPs. The average particle sizes
successful deposition of Au/Pd NPs on carbon. The average of the 0.5 mM Au/Pd NPs on LFP/C, 0.25 mM Au NPs,
0.5 mM Au NPs, and 0.5 mM Au/Pd NPs on AB are shown
in Table I. The average particle size of Au/Pd NPs on AB
was larger than that of Au/Pd NPs on LFP/C. Meanwhile, the
(f) average particle size of Au/Pd NPs on LFP/C was very
similar to that of 0.25 mM Au NPs on LFP/C, which suggests
(e)
that Au NPs were coated by thin Pd layers during reduction
(d)
(f) of Pd(II), hindering the growth of Au/Pd core–shell NPs. The
(c)
average particle sizes of Au/Pd NPs on LFP/C and Au/Pd on
(b)
AB were different even for the same concentration of Au and
(a) (e) Pd. It can be considered that LFP can contribute to the
reduction of Au(III) because the redox potential of Au is
(d)
higher than that of LFP (LFP: 0.41 V versus SHE, Au(III)/
(c)
Au: 1.52 V versus SHE, Pd(II)/Pd: 0.92 V versus SHE).
While Au(III) is reduced, Fe(II) in LFP would be oxidized to
(b) Fe(III), and lithium would be deintercalated from LFP
according to the following reaction,
(a) LiFe (II) PO4 / C Li+ + Fe (III) PO4 / C + e-.
If lithium is deintercalated from LFP/C during the synthesis
of the Au/Pd core–shell structure, the specific capacity of the
first cycle of charge in the charge–discharge process, which
Fig. 1. (Color online) X-ray diffraction patterns of acetylene black-
deposited Au/Pd nanoparticles before (a) and after heating at 100 °C (b),
corresponds to the lithium desorption reaction, should be
200 °C (c), 300 °C (d), 400 °C (e), and 500 °C (f) for 1 h in Ar. Left: full lower than that of the second cycle of charge. To investigate
profiles and right: enlarged profiles in a range of 2θ = 37°–42°. this hypothesis, a battery cell was fabricated using
SDDD06-2 © 2021 The Japan Society of Applied PhysicsJpn. J. Appl. Phys. 60, SDDD06 (2021) K. Yoshida et al.
(a) (b) (c) (d) (e)
(f) (g) (h) (i) (j)
Fig. 2. Transmission electron microscopy micrographs of Au/Pd nanoparticles (NPs) on acetylene black (a), (f), Au/Pd NPs on carbon-coated LiFePO4 (LFP/
C) (b), (g), 0.25 mM Au NPs on LFP/C (c), (h), 0.5 mM Au NPs on LFP/C (d), (i), and 0.25 mM Pd NPs on LFP/C (e), (j), respectively.
Fig. 3. (Color online) Left: X-ray diffraction patterns of carbon-coated LiFePO4 (LFP/C) before and after depositing Au/Pd nanoparticles. Right: enlarged
profiles in a range of 2θ = 35°–40° before and after heating LFP/C·Au·Pd at 300 °C and 400 °C for 1 h in Ar atmosphere.
Table I. Average particle sizes of sonochemically synthesized 1. Au/Pd
NPs on LFP/C (0.5 mM), 2. Au NPs on LFP/C (0.25 mM), 3. Au NPs on In summary, the deposition of Au/Pd core–shell NPs on
LFP/C (0.5 mM) and 4. Au/Pd NPs on AB (0.5 mM), and concentrations of
carbon-coated LFP using ultrasound irradiation was studied.
utilized Au(III) and Pd(II) for each synthesis experiment.
A TEM analysis revealed that the average size of Au/Pd NPs
Concentration deposited on LFP/C was 7.2 nm. An XRD peak shifting from
(mM) 38.2° corresponding to Au to 39.1°, which can be attributed
Average particle size of Au Pd to Au/Pd alloy, was observed after calcination of LFP/
No. Sample deposited metal (III) (II) C·Au·Pd at 400 °C in Ar atmosphere, indicating that a phase
1. LFP/C·Au·Pd 7.2 ± 3.0 0.25 0.25 transition from core–shell structure to alloy occurred. These
2. LFP/C·Au 7.1 ± 4.2 0.25 — results showed that dispersed Au/Pd core–shell NPs were
3. LFP/C·Au 10.8 ± 2.7 0.5 — successfully deposited on LFP/C using ultrasound irradiation.
4. AB·Au·Pd 8.6 ± 0.6 0.25 0.25 Further work on the battery performance of LFP/C·Au·Pd is
currently underway in our laboratory.
ORCID iDs Takahiro Kato https://orcid.org/0000-0002-1402-3786
LFP/C·Au·Pd as the cathode, lithium metal as the anode, and
1 M LiPF6 in a 1:1 (by volume) solution of ethylene
carbonate/dimethyl carbonate as the electrolyte, and measure- 1) N. Nitta, F. Wu, J. T. Lee, and G. Yushin, Mater. Today 18, 5 (2015).
ment was performed at a constant current of 0.5 C and a cut- 2) A. Yamada, S. C. Chung, and K. Hinokuma, J. Electrochem. Soc. 148, A224
off voltage of 2.0–4.0 V. The charge capacity difference (2001).
3) S. Chung, J. T. Blocking, and Y. Chiang, Nat. Mater. 1, 123 (2002).
between the first and the second cycle was 23 mAh g−1. This
4) N. Zhao, Y. Li, X. Zhao, X. Zhi, and G. Liang, J. Alloys Compd. 683, 123
electrical capacity would correspond to the reduction of (2016).
17.7% of 0.25 mM Au(III) by LFP. Therefore, it can be 5) J. Li, Q. Qu, L. Zhang, L. Zhang, and H. Zheng, J. Alloys Compd. 579, 377
concluded that a part of Au(III) was reduced to Au in the (2013).
6) Z. Chen and J. R. Dahn, J. Electrochem. Soc. 149, A1184 (2002).
flask by LFP, which would explain the difference in the 7) H. C. Shin, W. I. Cho, and H. Jang, Electrochim. Acta 52, 1472 (2006).
average particle size between Au/Pd NPs deposited on LFP/C 8) N. Ravet, N. Chouinard, J. F. Magnan, S. Besner, M. Gauthier, and
and Au/Pd NPs deposited on AB. M. Armand, J. Power Sources 97–98, 503 (2001).
SDDD06-3 © 2021 The Japan Society of Applied PhysicsJpn. J. Appl. Phys. 60, SDDD06 (2021) K. Yoshida et al.
9) Y. Huang, Y. Xu, and X. Yang, Electrochim. Acta 113, 156 (2013). 18) T. Nakazawa, H. Nitani, S. Tanabe, K. Okitsu, S. Seino, Y. Mizukoshi, and
10) A. Örnek and O. Efe, Electrochim. Acta 166, 338 (2015). T. A. Yamamoto, Ultrason. Sonochem. 12, 249 (2005).
11) J. Morales, R. Trócoli, E. Rodríguez-Castellón, S. Franger, and J. Santos- 19) Y. Mizukoshi, K. Sato, T. J. Konno, and N. Masahashi, Appl. Catal. B 94,
Peña, J. Electroanal. Chem. 631, 29 (2009). 248 (2010).
12) Y. Mizukoshi, F. Hori, and K. Okitsu, Jpn. J. Appl. Phys. 57, 0102A5 20) F. Hori, T. Kojima, S. Tanaka, T. Akita, T. Iwai, T. Onitsuka, N. Taguchi,
(2018). and A. Iwase, Phys. Status Solidi C 4, 3895 (2007).
13) Y. Tanaka, H. Okawa, Y. Ono, T. Enkhtuya, T. Galya, T. Kato, and 21) T. Akita, N. Hase, N. Taguchi, S. Tanaka, M. Kohyama, and F. Hori, J.
K. Sugawara, Jpn. J. Appl. Phys. 58, SGGD17 (2019). Phys.: Conf. Ser. 100, 012014 (2008).
14) H. Okawa, Y. Ono, Y. Tanaka, T. Kato, and K. Sugawara, J. Soc. Powder 22) K. Okitsu, Y. Mizukoshi, H. Bandow, Y. Maeda, T. Yamamoto, and
Technol. Jpn. 56, 117 (2019) [in Japanese]. Y. Nagata, Ultrason. Sonochem. 3, S249 (1996).
15) M. A. Saliman, H. Okawa, M. Takai, Y. Ono, T. Kato, K. Sugawara, and 23) K. Yoshida, H. Okawa, Y. Ono, T. Kato, and K. Sugawara, Proc. 41th
M. Sato, Jpn. J. Appl. Phys. 55, 07KE05 (2016). Symp. UltraSonic Electronics (USE2020), 2020, p. 3Pa4-2.
16) H. Nitani, M. Yuya, T. Ono, T. Nakagawa, S. Seino, K. Okitsu, 24) Y. Nagata, Y. Mizukoshi, K. Okitsu, and Y. Maeda, Radiat. Res. 146, 333
Y. Mizukoshi, S. Emura, and T. A. Yamamoto, J. Nanopart. Res. 8, 951 (1996).
(2006). 25) A. Cybula, J. B. Priebe, M. Pohl, J. W. Sobczak, M. Schneider, A. Zielińska-
17) Y. Mizukoshi, K. Sato, J. Kugai, T. A. Yamamoto, T. J. Konno, and Jurek, A. Brückner, and A. Zaleska, Appl. Catal. B 152–153, 202
N. Masahashi, J. Exp. Nanosci. 10, 235 (2015). (2014).
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