Effect of Fluorine Substitution in Li₃YCl₆ Chloride Solid Electrolytes for All-solid-state Battery

Abstract

All-solid-state batteries experience irreversible capacity loss particularly in the initial potential cycle, owing to electrolyte decomposition at the electrode/electrolyte interface. A strategy for expanding the oxidation stability of electrolytes is replacing the anion with fluorine. However, fluorine substitution has a negative influence on ionic conductivity. In this study, we introduced trace amounts of fluorine into Li₃YCl₆ solid electrolytes which exhibit high ionic conductivities and wide potential windows. The effect of replacement on ionic conductivity, oxidation stability, and charge–discharge characteristics were studied. The trace amounts of fluorine in Li₃YCl₆ did not reduce the conductivity, but improved the apparent oxidation stability. The decomposed product of LiF from the fluorine-substituted electrolyte disturbed the formation of a high-resistance layer at the electrode/electrolyte interface. The initial charge–discharge efficiency of the uncoated LiCoO₂ cathode was improved by the trace amount of fluorine replacement in the Li₃YCl₆ solid electrolyte.

1. Introduction

All-solid-state lithium-ion batteries (SSBs) using a flame-retardant solid electrolyte, which is different from conventional lithium-ion batteries that use liquid electrolytes, are attracting considerable attention for their improved safety. In addition, because the transport number of solid electrolytes is almost 1,^1,2 high-rate charge–discharge is expected due to the suppression of electrolyte concentration change.^3–5 However, irreversible capacity loss occurs in SSBs especially during the first charge–discharge process.^6,7 This is due to the formation of high-resistance layers associated with the decomposition reaction of the electrolytes at the electrode/electrolyte interface.⁸ In a cell using a sulfide-based solid electrolyte with the cathode active material LiNi_0.8Co_0.1Mn_0.1O₂, a high-resistance layer is formed owing to the oxidation of the solid electrolyte at 3.8 V vs. Li⁺/Li during the first charging process.⁷ Therefore, solid electrolytes with high oxidation stability are required to suppress the irreversible capacity loss during the first charge-discharge process.

Solid electrolytes have been studied mainly in sulfide and oxide materials. Although sulfide-based materials exhibit high ionic conductivity of approximately 10⁻²–10⁻³ S cm⁻¹,^9–11 the narrow potential window below 3 V requires coatings such as LiNbO₃ and Li₃PO₄ on cathode active materials.^12–14 Coating reagent including LiNbO₃ was necessary between the sulfide electrolyte and the oxide cathode to avoid the space-charge layer that causes a large interface resistance.^12,15–17 However, coating reagents have a low ionic conductivity, which restricts Li⁺ transfer. Therefore, exploring novel strategies that do not require a coating agent is essential. Halide-based materials, which have been gaining attention since the study of the high Li⁺ conductor Li₃YCl₆,¹⁸ have wide potential windows and are stable as oxide-based cathode materials.¹⁹ Among them, fluoride-based materials show a low ionic conductivity of approximately 10⁻⁶ S cm⁻¹; however, they have a wide potential window of above 6 V.^17,20 Chloride-based materials, such as Li₃InCl₆ and Li₃YCl₆, also have a relatively high ionic conductivity of approximately 10⁻³–10⁻⁴ S cm⁻¹, and wide potential windows of above 4 V.^17,18,21 Because chloride-based materials have oxidation stability without the need for coating on the cathode active material, high Li⁺ conductivity can be expected between the electrode and the electrolyte.²²

Considering the improvement in the oxidation stability of solid electrolytes using chloride-based electrolytes, Li₃InCl_4.8F_1.2, which is a chloride-based Li₃InCl₆ material substituted with fluorine, has improved electrochemical stability.²³ Li₃InCl_4.8F_1.2 can improve the charge–discharge capacity by suppressing further interface reaction at high voltage by forming cathode electrolyte interface layers mainly composed of LiF during charge–discharge. However, when introducing 20 % fluorine into Li₃YCl₆, fluoride ions with short and strong bonds with lithium ions compared to chloride ions cause local distortion in the lithium-ion configuration, resulting in a decrease of ionic conductivity from 1.3 × 10⁻³ to 5.1 × 10⁻⁴ S cm⁻¹.²³ The origin of the apparent high oxidation stability can be explained by the decomposition products of LiF. This motivated us to introduce trace amounts of fluorine in chloride electrolytes. In addition, the reported Li₃InCl₆ electrolytes show poor reduction stability and cannot be in direct contact with the indium-lithium alloy. In this study, the effect of 0.5 % fluorine substitution into the chloride-based solid-state electrolyte Li₃YCl₆ was examined. The slight replacement effects on the ionic conductivity, oxidation stability, and charge–discharge properties are discussed with the observing decomposed products measured by hard X-ray photoelectron spectroscopy.

2. Experimental

2.1 Synthesis of Li₃YCl₆ and Li₃YCl_5.97F_0.03

Li₃YCl₆ compounds were synthesized by mechanochemical milling of LiCl (>99.0 %, FUJIFILM Wako Pure Chemical Corporation) and YCl₃ (Strem Chemicals, Inc.). LiCl : YCl₃ (3 : 1 molar ratio) was weighed in an Ar atmosphere glove box, mixed using an agate mortar, and then the mixed powder and 5 mm diameter zirconia balls were placed in a zirconia pot. The sealed pots were planetary ball milled at 500 rpm for 52 h. To prepare F-substituted Li₃YCl₆, we added YF₃ (Sigma-Aldrich) as a precursor with a molar ratio of LiCl : YCl₃ : YF₃ = 3 : 0.99 : 0.01, which is expressed as Li₃YCl_5.97F_0.03 according to the starting composition in the following sections. The synthesis of Li₃YCl₆ and Li₃YCl_5.97F_0.03 did not require annealing.

2.2 Material characterization

Synchrotron X-ray powder diffraction (SXRD) was conducted at the beamline BL5S2 of the Aichi Synchrotron Radiation Center with a wavelength of 0.75 Å (1 Å = 0.1 nm). To prevent a reaction with moisture and oxygen, the samples were filled in a capillary in an Ar atmosphere. F K-edge X-ray absorption spectra (XAS) were recorded at beamline BL1N2 of the Aichi Synchrotron Radiation Center and beamline BL-2 of the Ritsumeikan University SR Center. Li₃YCl_5.97F_0.03 was placed in the measurement chamber in an atmospheric non-exposed environment, and analyzed under vacuum in fluorescence yield mode. The reference YF₃ and LiF samples were investigated in total electron yield mode.

2.3 Electrochemical characterization

Powder samples were cold pressed at 314 MPa in a 10 mm-diameter-cylinder, and electrochemical impedance spectroscopy (EIS) measurements were conducted in the frequency range of 500 kHz–1 Hz with an amplitude of 10 mV. To evaluate the oxidation stability of the prepared solid electrolytes (SEs), Li₃YCl₆ and Li₃YCl_5.97F_0.03, Li|SE|SE-AB(acetylene black)|Pt cells were prepared. Linear sweep voltammetry (LSV) measurements were performed at 298 K and a scan rate of 0.1 mV s⁻¹. Pt and Li were used as working and counter electrodes, respectively. After the SE was cold-pressed at 125 MPa, the SE-AB layer, which is a mixture of conductive aid AB (Strem Chemicals, Inc.) and SE, was cold-pressed onto the SE pellet at 345 MPa. The increased contact area between the electrolyte and AB, which is electronic conductive additive, significantly promotes the decomposition reaction rate of the electrolytes, accurately assess the stability of the solid electrolytes. Furthermore, using the cells with the same configuration for the LSV measurements, the samples after applying 5 V for 10 h were analyzed by hard X-ray photoemission spectroscopy (HAXPES). HAXPES measurements were conducted at the beamline BL46XU at SPring-8. The samples were then transferred to a measurement chamber without air exposure. The measurements were performed under vacuum using 8 keV-X-rays at X-ray incidence angles of 10°. To perform charge–discharge tests, In-Li|SE|LiCoO₂ cells were assembled. Cathode composite electrodes were prepared by mixing LiCoO₂ (TOSHIMA Manufacturing Co., Ltd.), SE, and AB in a weight ratio of 1 : 1 : 0.1. Two-layer pellets of 20 mg cathode and 60 mg SE were cold-pressed at 314 MPa, and then the In-Li foil was attached by pressing at 314 MPa. The charge–discharge tests were performed at a current density of 0.033 mA cm⁻², which corresponds to 273 mAh g⁻¹ LiCoO₂ and an approximate 0.01 C rate with upper and lower voltage limits of 4 and 2 V at 298 K. EIS measurements were performed at 3.5 V after one charge–discharge cycle.

3. Results and Discussion

3.1 Characterization of prepared solid electrolyte

Figure 1a shows the SXRD patterns of Li₃YCl₆ and Li₃YCl_5.97F_0.03. The X-ray diffraction pattern of the synthesized Li₃YCl₆ had a trigonal phase $P\bar{3}m1$.^18,24 The diffraction peaks of Li₃YCl_5.97F_0.03 in which fluorine is expected to be substituted are similar to those of Li₃YCl₆, and no impurities were detected. The synthesized Li₃YCl_5.97F_0.03 had the same crystal structure as Li₃YCl₆, indicating the successful replacement of fluorine into Li₃YCl₆. The calculated lattice constants were a, b = 11.2170(9) and c = 6.0427(7) Å for Li₃YCl₆, and a, b = 11.220(1), and c = 6.0484(8) Å for Li₃YCl_5.97F_0.03. In addition, peak broadening including the 330 diffraction line, was observed in Li₃YCl_5.97F_0.03 (Figs. S1a and S1b). Because (110), (220), and (330) planes in Li₃YCl₆ contain chloride ions, the effect of fluorine substitution is observed in the 330 diffraction line which corresponds to the interplanar spacings of (110), (220), and (330) planes (Fig. S1c). The peak broadening corresponds to the local distortion of the chloride sites caused by fluoride ions replacement. Proof of such a trace amount of fluoride ion replacement can also be detected by F K-edge XAS. In Fig. 1b, the F K-edge XAS spectrum of Li₃YCl_5.97F_0.03 is compared with the spectra for the YF₃ and LiF reference samples. The spectra originate from the electron transition from the fluorine 1s to 2p orbitals. An absorption peak was observed near 690 eV for YF₃, which was used as a raw material for the fluorine source. In contrast, the spectrum for Li₃YCl_5.97F_0.03 contains an additional absorption peak near 689 eV on the lower-energy side. If YF₃ is not substituted with Li₃YCl₆, the spectrum for Li₃YCl_5.97F_0.03 should be identical to that for YF₃. Furthermore, this component on the lower-energy side is different from that for the LiF. Thus, F K-edge XAS indicated the replacement of fluorine in Li₃YCl_5.97F_0.03. From these results, we conclude that Li₃YCl_5.97F_0.03 has the same crystal structure as Li₃YCl₆ and contains trace amounts of fluorine.

Figure 1.

(a) SXRD patterns of Li₃YCl₆ and Li₃YCl_5.97F_0.03. The diffraction lines are assigned to the reported trigonal phase $P\bar{3}m1$.^18,24 (b) F K-edge XAS of Li₃YCl_5.97F_0.03 with the spectra of YF₃ and LiF referenced samples.

3.2 Ionic conductivity

The ionic conductivities of Li₃YCl₆ and Li₃YCl_5.97F_0.03 were measured using EIS. Figure 2a shows the Nyquist plots of EIS spectra of Li₃YCl₆ and Li₃YCl_5.97F_0.03 at 298 K. The ionic resistance was calculated from the minimum points after the semicircles on the high frequency side.²⁵ Figure 2b shows Arrhenius plots for the ionic conductivity (σ) times temperature (T) of Li₃YCl₆ and Li₃YCl_5.97F_0.03 in the temperature range of 278–348 K. The Arrhenius equation is expressed as follows:   

\begin{equation} \sigma T = A \exp(-E_{\text{a}}/kT), \end{equation} (1)

where A is the frequency factor, k is Boltzmann’s constant, and E_a is the activation energy. The ionic conductivities for Li₃YCl₆ and Li₃YCl_5.97F_0.03 at 298 K are 2.24 × 10⁻⁴ and 2.39 × 10⁻⁴ S cm⁻¹, respectively. The activation energies for Li₃YCl₆ and Li₃YCl_5.97F_0.03 calculated from the slope of the Arrhenius plot are 0.47 and 0.46 eV, respectively. Therefore, a trace amount of fluorine replacement of 0.5 % does not decrease the ionic conductivity. In contrast, the ionic conductivity decreased in samples with more fluorine replacement (Fig. S2).

Figure 2.

(a) Nyquist plots from EIS of Li₃YCl₆ and Li₃YCl_5.97F_0.03 in 298 K. (b) Arrhenius plots for the ionic conductivity (σ) times temperature (T) of Li₃YCl₆ and Li₃YCl_5.97F_0.03 in the temperature range of 278 to 348 K.

3.3 Oxidation stability

The electrochemical stability of the Li|SE|SE-AB|Pt cell was evaluated by LSV measurements at a scan rate of 0.1 mV s⁻¹ and 5 V vs. the Li counter electrode (Fig. 3). The anodic current corresponding to the phase separation of Li₃YCl₆ and Li₃YCl_5.97F_0.03 is observed as approximately 3.8 V. Focusing on this reaction, the oxidation current of Li₃YCl_5.97F_0.03 is observed at a higher voltage side than that of Li₃YCl₆. The current density at 5 V for Li₃YCl₆ was 232 µA cm⁻², which is higher than that for Li₃YCl_5.97F_0.03 (188 µA cm⁻²). The observed phase separation of Li₃YCl₆ is expressed as Eq. 2.^24,26   

\begin{equation} \text{Li$_{3}$YCl$_{6}$}\to \text{YCl$_{3}$} + 3\ \text{LiCl} \end{equation} (2)

Further, the assumed phase separation of Li₃YCl_5.97F_0.03 is   

\begin{equation} \text{Li$_{3}$YCl$_{5.97}$F$_{0.03}$}\to \text{YCl$_{3}$} + \text{2.97 LiCl} + \text{0.03 LiF}, \end{equation} (3)

where LiF was additionally formed compared with the system not substituted with fluorine. According to the first-principles calculations of on fluorine-containing chloride Li₃InCl_4.8F_1.2, LiF is formed at a lower potential in phase separation.²³ The formation of fluoride LiF via fluorine replacement can improve the oxidation stability of SE.

Figure 3.

LSV profiles of Li|SE|SE-AB|Pt cells using Li₃YCl₆ or Li₃YCl_5.97F_0.03 SEs at 298 K with a sweep rate of 0.1 mV s⁻¹.

To confirm the decomposition products in the LSV measurements, the chemical state was analyzed by HAXPES measurements, which can detect signals at depths of tens of nanometers.²⁷ Using the same Li|SE|SE-AB|Pt cell as that used for the LSV measurements, the SE-AB layer was analyzed after applying a voltage of 5 V for 10 h. Because the insulating SE disturbed the energy calibration using the C 1s spectra, the binding energy was corrected using the main peak of Li 1s as the reported energy of Li₃YCl₆ (56.6 V). Figure 4 shows the Li 1s spectra of the SE-AB layer using Li₃YCl₆ and Li₃YCl_5.97F_0.03 in the pristine state and after oxidation of 5 V. After oxidation at 5 V, the Li₃YCl₆ consisted of only one component. This is because the reported binding energies of Li₃YCl₆ and LiCl are almost identical and cannot be distinguished.²⁶ The observed full-width half maximum of Li₃YCl₆ after applying 5 V is 2.28 eV, which is slightly broader than that for Li₃YCl₆ (2.08 eV) in the initial state. Therefore, the Li 1s spectrum of Li₃YCl₆ after applying 5 V is components of the Li₃YCl₆ electrolyte and LiCl decomposition product. In contrast, the Li₃YCl_5.97F_0.03 after applying 5 V consisted of two components. Considering the lower binding energy of LiF compared to Li₃YCl₆ and LiCl,²⁸ the SE-AB layer from the oxidized Li₃YCl_5.97F_0.03 contains LiF. Therefore, the improvement in the apparent oxidation stability of Li₃YCl_5.97F_0.03 is attributed to the formation of a fluorine-derived decomposition product, LiF, which is different from Li₃YCl₆ on the electrode interface, suppressing further decomposition reaction of the solid electrolyte.

Figure 4.

Li 1s HAXPES data of SE-AB composite electrode layer using Li₃YCl₆ or Li₃YCl_5.97F_0.03 SEs in the pristine state and after oxidation of 5 V.

3.4 Charge-discharge of In-Li|SE|LiCoO₂ batteries

Figure 5 shows the first charge–discharge profiles of the In-Li|SE|LiCoO₂ cell at 298 K and 0.01 C rate. The first discharge capacity is 123(2) mAh g⁻¹ for Li₃YCl₆ and 131(1) mAh g⁻¹ for Li₃YCl_5.97F_0.03, and the first charge–discharge efficiency is 69(1) % for Li₃YCl₆ and 73(2) % for Li₃YCl_5.97F_0.03, with the standard deviations in parentheses. Although the difference between Li₃YCl₆ and Li₃YCl_5.97F_0.03 is small, we have confirmed the reproducibility. Fluorine substitution results in an improvement in the initial charge–discharge efficiency. Furthermore, the profile of Li₃YCl_5.97F_0.03 shows a decreased polarization, where a small hump can be observed near 3.5 V. This hump was caused by the well-known phase transition between the trigonal and monoclinic phases of Li_xCoO₂.^29,30 The observed low polarization and hump originate from the suppression of the formation of a thick resistance layer at the electrode/electrolyte interface by fluorine substitution in Li₃YCl₆. An improved cycling property for the fluorine-substituted Li₃YCl₆ electrolyte could be anticipated. This study limits the discussion to the first cycle, which confirms the reproducibility of the data. The cycle characteristics are important for the study of all-solid-state batteries, and further research is required.

Figure 5.

First charge-discharge profiles of the In-Li|SE|LiCoO₂ cells using Li₃YCl₆ or Li₃YCl_5.97F_0.03 SEs at 298 K and 0.01 C rate.

The decreased interface resistance can be demonstrated by EIS after the initial charge–discharge cycle. Figures 6a and 6b shows the Nyquist plot of the In-Li|SE|LiCoO₂ cell before the charge–discharge test and at 3.5 V after the initial cycle. As shown in Fig. 6a, the resistances of Li₃YCl₆ and Li₃YCl_5.97F_0.03 before the charge–discharge test are almost similar, which corresponds to the ionic conductivity shown in Fig. 2a. In Fig. 6b, the semicircle on the high-frequency side can be assigned to the resistance from the solid electrolyte, and the low-frequency side is attributed to the charge-transfer resistance at the electrode/electrolyte interface.^25,31,32 Although almost no difference can be confirmed on the high-frequency side, Li₃YCl_5.97F_0.03 has a lower charge-transfer resistance than Li₃YCl₆. Li₃YCl_5.97F_0.03 suppresses the formation of a highly resistant decomposed product at the electrode/electrolyte interface, which improves the charge–discharge efficiency.

Figure 6.

Nyquist plot of the In-Li|SE|LiCoO₂ cells using Li₃YCl₆ or Li₃YCl_5.97F_0.03 SEs (a) before the charge-discharge test and (b) at 3.5 V after the initial charge-discharge cycle.

4. Conclusion

Li₃YCl_5.97F_0.03, in which fluorine is substituted into Li₃YCl₆, showed the same conductivity as that of Li₃YCl₆. The oxidation current of Li₃YCl_5.97F_0.03 was observed at a higher voltage than that of Li₃YCl₆, implying improved apparent oxidation stability by fluorine replacement. HAXPES measurements indicate the formation of LiF as a phase separation product in the fluorine-substituted Li₃YCl_5.97F_0.03. Li₃YCl_5.97F_0.03 exhibits a higher initial discharge capacity and efficiency with a lower charge-transfer resistance than Li₃YCl₆. The small amount of fluorine substitution improves the apparent oxidation stability of the solid electrolyte and suppresses further decomposition of the SE by the formation of the fluorine-derived decomposition product LiF without significantly affecting the ionic conductivity.

Acknowledgment

The SXRD experiments were performed at the beamline BL5S2 of Aichi Synchrotron Radiation Center (proposal nos. 2021D6040). The HAXPES measurements were performed at the beamline BL46XU of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2021B1725, 2021B1936).

Data Availability Statement

The data that support the findings of this study are openly available under the terms of the designated Creative Commons License in J-STAGE Data at https://doi.org/10.50892/data.electrochemistry.22180240.

• 1) All-solid-state batteries experience irreversible capacity loss particularly in the initial potential cycle, owing to electrolyte decomposition at the electrode/electrolyte interface. A strategy for expanding the oxidation stability of electrolytes is replacing the anion with fluorine. However, fluorine substitution has a negative influence on ionic conductivity. In this study, we introduced trace amounts of fluorine into Li₃YCl₆ solid electrolytes which exhibit high ionic conductivities and wide potential windows. The effect of replacement on ionic conductivity, oxidation stability, and charge–discharge characteristics were studied. The trace amounts of fluorine in Li₃YCl₆ did not reduce the conductivity, but improved the apparent oxidation stability. The decomposed product of LiF from the fluorine-substituted electrolyte disturbed the formation of a high-resistance layer at the electrode/electrolyte interface. The initial charge–discharge efficiency of the uncoated LiCoO₂ cathode was improved by the trace amount of fluorine replacement in the Li₃YCl₆ solid electrolyte.

CRediT Authorship Contribution Statement

Mariya Yamagishi: Data curation (Lead), Investigation (Lead), Writing – original draft (Lead)

Chengchao Zhong: Investigation (Supporting), Supervision (Equal), Writing – review & editing (Equal)

Daisuke Shibata: Data curation (Supporting)

Mayu Morimoto: Data curation (Supporting), Investigation (Supporting)

Yuki Orikasa: Conceptualization (Equal), Project administration (Lead), Supervision (Lead), Writing – review & editing (Lead)

Conflict of Interest

The authors declare no competing financial interests.

Footnotes

C. Zhong and Y. Orikasa: ECSJ Active Members

References

• 1)  K. Minami, F. Mizuno, A. Hayashi, and M. Tatsumisago, Solid State Ionics, 178, 837 (2007).
• 2)  H. Buschmann, J. Dölle, S. Berendts, A. Kuhn, P. Bottke, M. Wilkening, P. Heitjans, A. Senyshyn, H. Ehrenberg, A. Lotnyk, V. Duppel, L. Kienle, and J. Janek, Phys. Chem. Chem. Phys., 13, 19378 (2011).
• 3)  Y. Kato, S. Hori, T. Saito, K. Suzuki, M. Hirayama, A. Mitsui, M. Yonemura, H. Iba, and R. Kanno, Nat. Energy, 1, 16030 (2016).
• 4)  K. Kandori, H. Yamashige, N. Furuta, T. Nonaka, and Y. Orikasa, Electrochemistry, 87, 182 (2019).
• 5)  Y. Orikasa, K. Yamamoto, T. Shimizu, and Y. Uchimoto, Chem. Phys. Rev., 3, 011305 (2022).
• 6)  G. Oh, M. Hirayama, O. Kwon, K. Suzuki, and R. Kanno, Chem. Mater., 28, 2634 (2016).
• 7)  R. Koerver, I. Aygün, T. Leichtweiß, C. Dietrich, W. Zhang, J. O. Binder, P. Hartmann, W. G. Zeier, and J. Janek, Chem. Mater., 29, 5574 (2017).
• 8)  W. Zhang, D. A. Weber, H. Weigand, T. Arlt, I. Manke, D. Schröder, R. Koerver, T. Leichtweiss, P. Hartmann, W. G. Zeier, and J. Janek, ACS Appl. Mater. Interfaces, 9, 17835 (2017).
• 9)  A. Sakuda, A. Hayashi, and M. Tatsumisago, Sci. Rep., 3, 2261 (2013).
• 10)  M. Tatsumisago, M. Nagao, and A. Hayashi, J. Asian Ceram. Soc., 1, 17 (2013).
• 11)  A. Hayashi, A. Sakuda, and M. Tatsumisago, Front. Energy Res., 4, 25 (2016).
• 12)  N. Ohta, K. Takada, I. Sakaguchi, L. Zhang, R. Ma, K. Fukuda, M. Osada, and T. Sasaki, Electrochem. Commun., 9, 1486 (2007).
• 13)  K. Chen, K. Yamamoto, Y. Orikasa, T. Uchiyama, Y. Ito, S. Yubuchi, A. Hayashi, M. Tatsumisago, K. Nitta, T. Uruga, and Y. Uchimoto, Solid State Ionics, 327, 150 (2018).
• 14)  Y. Morino, Electrochemistry, 90, 027001 (2022).
• 15)  K. Takada, N. Ohta, L. Zhang, K. Fukuda, I. Sakaguchi, R. Ma, M. Osada, and T. Sasaki, Solid State Ionics, 179, 1333 (2008).
• 16)  N. Kamaya, K. Homma, Y. Yamakawa, M. Hirayama, R. Kanno, M. Yonemura, T. Kamiyama, Y. Kato, S. Hama, K. Kawamoto, and A. Mitsui, Nat. Mater., 10, 682 (2011).
• 17)  W. D. Richards, L. J. Miara, Y. Wang, J. C. Kim, and G. Ceder, Chem. Mater., 28, 266 (2016).
• 18)  T. Asano, A. Sakai, S. Ouchi, M. Sakaida, A. Miyazaki, and S. Hasegawa, Adv. Mater., 30, 1803075 (2018).
• 19)  C. Wang, J. Liang, J. T. Kim, and X. Sun, Sci. Adv., 8, eadc9516 (2022).
• 20)  M. Feinauer, H. Euchner, M. Fichtner, and M. A. Reddy, ACS Appl. Energy Mater., 2, 7196 (2019).
• 21)  X. Li, J. Liang, N. Chen, J. Luo, K. R. Adair, C. Wang, M. N. Banis, T.-K. Sham, L. Zhang, S. Zhao, S. Lu, H. Huang, R. Li, and X. Sun, Angew. Chem., Int. Ed., 58, 16427 (2019).
• 22)  L. Zhou, T.-T. Zuo, C. Y. Kwok, S. Y. Kim, A. Assoud, Q. Zhang, J. Janek, and L. F. Nazar, Nat. Energy, 7, 83 (2022).
• 23)  S. Zhang, F. Zhao, S. Wang, J. Liang, J. Wang, C. Wang, H. Zhang, K. Adair, W. Li, M. Li, H. Duan, Y. Zhao, R. Yu, R. Li, H. Huang, L. Zhang, S. Zhao, S. Lu, T.-K. Sham, Y. Mo, and X. Sun, Adv. Energy Mater., 11, 2100836 (2021).
• 24)  T. H. Wan and F. Ciucci, ACS Appl. Energy Mater., 4, 7930 (2021).
• 25)  K. Ariyoshi, A. Mineshige, M. Takeno, T. Fukutsuka, T. Abe, S. Uchida, and Z. Siroma, Electrochemistry, 90, 102008 (2022).
• 26)  L. M. Riegger, R. Schlem, J. Sann, W. G. Zeier, and J. Janek, Angew. Chem., Int. Ed., 60, 6718 (2021).
• 27)  Y. Takanashi, Y. Orikasa, M. Mogi, M. Oishi, H. Murayama, K. Sato, H. Yamashige, D. Takamatsu, T. Fujimoto, H. Tanida, H. Arai, T. Ohta, E. Matsubara, Y. Uchimoto, and Z. Ogumi, J. Power Sources, 196, 10679 (2011).
• 28)  S. Leroy, H. Martinez, R. Dedryvère, D. Lemordant, and D. Gonbeau, Appl. Surf. Sci., 253, 4895 (2007).
• 29)  G. G. Amatucci, J. M. Tarascon, and L. C. Klein, J. Electrochem. Soc., 143, 1114 (1996).
• 30)  A. Van der Ven, M. K. Aydinol, G. Ceder, G. Kresse, and J. Hafner, Phys. Rev. B, 58, 2975 (1998).
• 31)  S. Wang, W. Zhang, X. Chen, D. Das, R. Ruess, A. Gautam, F. Walther, S. Ohno, R. Koerver, Q. Zhang, W. G. Zeier, F. H. Richter, C.-W. Nan, and J. Janek, Adv. Energy Mater., 11, 2100654 (2021).
• 32)  K. Ariyoshi, Z. Siroma, A. Mineshige, M. Takeno, T. Fukutsuka, T. Abe, and S. Uchida, Electrochemistry, 90, 102007 (2022).