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Oxyfluoride Cathode for All-Solid-State Fluoride-Ion Batteries with Small Volume Change Using Three-Dimensional Diffusion Paths
Chemistry of Materials ( IF 7.2 ) Pub Date : 2022-11-14 , DOI: 10.1021/acs.chemmater.2c02736
Yanchang Wang 1 , Tsuyoshi Takami 1 , Zhuoran Li 1 , Kentaro Yamamoto 1 , Toshiyuki Matsunaga 1 , Tomoki Uchiyama 1 , Toshiki Watanabe 1 , Hidenori Miki 1, 2 , Toshihiko Inoue 2 , Hideki Iba 2 , Uichiro Mizutani 3 , Hirokazu Sato 4 , Kazuhiko Maeda 5 , Hiroshi Kageyama 6 , Yoshiharu Uchimoto 1
Affiliation  

All-solid-state fluoride-ion batteries (FIBs) are expected to become the next generation of battery systems owing to their outstanding energy storage characteristics. However, the volume expansion of the cathode that accompanies the insertion of fluoride ions remains an urgent issue to be addressed. Even if an intercalation-type cathode is applied in FIBs, fluoride-ion insertion into the interstitial sites of two-dimensional materials such as LaSrMnO4 still leads to non-negligible volume expansion. Here, we report a novel intercalation-type material, Sr3Fe2O5F2, possessing the Ruddlesden–Popper structure as a cathode material for FIBs that features not only interstitial sites but also anion vacancies as three-dimensional (3D) percolation sites to accommodate fluoride ions. This material exhibits a relatively high capacity of 118 mAh g–1 and good cycling stability over 70 cycles. Fe2+/Fe3+ redox reactions are responsible for charge compensation during the charging and discharging processes. The crystal structure during the charging process changes from Sr3Fe2O5F0.46 to Sr3Fe2O5F2 by using the 3D percolation sites with an extremely small volume change of approximately 0.17% and thereafter changes to Sr3Fe2O5F3 with a P4/mmm symmetry by using interstitial sites with a large volume change of approximately 11%. Our findings should pave the way for the design of new cathodes with excellent cycling stability and minimal volume expansion based on the percolation mechanism.

中文翻译:

使用三维扩散路径的体积变化小的全固态氟化物离子电池的氧氟化物阴极

全固态氟离子电池(FIB)由于其出色的储能特性有望成为下一代电池系统。然而,伴随氟离子插入的正极体积膨胀仍然是一个亟待解决的问题。即使在 FIB 中应用插层型阴极,氟化物离子插入二维材料(如 LaSrMnO 4 )的间隙位置仍会导致不可忽略的体积膨胀。在这里,我们报告了一种新型插层型材料 Sr 3 Fe 2 O 5 F 2,拥有 Ruddlesden-Popper 结构作为 FIB 的阴极材料,它不仅具有间隙位点,而且还具有阴离子空位作为三维 (3D) 渗透位点以容纳氟离子。这种材料表现出 118 mAh g –1的相对高容量和超过 70 个循环的良好循环稳定性。Fe 2+ /Fe 3+氧化还原反应负责充电和放电过程中的电荷补偿。充电过程中晶体结构由Sr 3 Fe 2 O 5 F 0.46变为Sr 3 Fe 2 O 5 F 2通过使用具有大约 0.17% 的极小体积变化的 3D 渗滤点,然后通过使用具有大约 11% 的大体积变化的间隙位点变为具有P 4 / mmm对称性的 Sr 3 Fe 2 O 5 F 3 。我们的研究结果应该为设计具有出色循环稳定性和基于渗透机制的最小体积膨胀的新型正极铺平道路。
更新日期:2022-11-14
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