Xu Weiliang, Dang Rongbin, Zhou Lin, Yang Yang, Lin Ting, Guo Qiubo, Xie Fei, Hu Zilin, Ding Feixiang, Liu Yunpeng, Liu Yuan, Mao Huican, Hong Juan, Zuo Zhanchun, Wang Xiaoqi, Yang Rui, Jin Xu, Hou Xueyan, Lu Yaxiang, Rong Xiaohui, Xu Ning, Hu Yong-Sheng
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
College of Mechanical Engineering, Yancheng Institute of Technology, Yancheng, Jiangsu, 224051, P. R. China.
Adv Mater. 2023 Oct;35(42):e2301314. doi: 10.1002/adma.202301314. Epub 2023 Sep 19.
The deposition of volatilized Na on the surface of the cathode during sintering results in the formation of surface residual alkali (NaOH/Na CO NaHCO ) in layered cathode materials, leading to serious interfacial reactions and performance degradation. This phenomenon is particularly evident in O3-NaNi Cu Mn Ti O (NCMT). In this study, a strategy is proposed to transform waste into treasure by converting residual alkali into a solid electrolyte. Mg(CH COO) and H PO are reacted with surface residual alkali to generate the solid electrolyte NaMgPO on the surface of NCMT, which can be labeled as NaMgPO4@NaNi Cu Mn Ti O -X (NMP@NCMT-X, where X indicates the different amounts of Mg and PO ). NaMgPO acts as a special ionic conductivity channel on the surface to improve the kinetics of the electrode reactions, remarkably improving the rate capability of the modified cathode at a high current density in the half-cell. Additionally, NMP@NCMT-2 enables a reversible phase transition from the P3 to OP2 phase in the charge-discharge process above 4.2 V and achieves a high specific capacity of 157.3 mAh g and outstanding capacity retention in the full cell. The strategy can effectively and reliably stabilize the interface and improve the performance of layered cathodes for Na-ion batteries (NIBs).
烧结过程中挥发的钠在阴极表面沉积，导致层状阴极材料中形成表面残留碱（NaOH/Na₂CO₃/NaHCO₃），引发严重的界面反应并导致性能退化。这种现象在O3-NaNi₀.₅Cu₀.₂Mn₀.₃Ti₀.₀O₂（NCMT）中尤为明显。在本研究中，提出了一种变废为宝的策略，即将残留碱转化为固体电解质。Mg(CH₃COO)₂和H₃PO₄与表面残留碱反应，在NCMT表面生成固体电解质NaMgPO₄，可标记为NaMgPO₄@NaNi₀.₅Cu₀.₂Mn₀.₃Ti₀.₀O₂-X（NMP@NCMT-X，其中X表示Mg和PO₄³⁻的不同用量）。NaMgPO₄作为表面特殊的离子传导通道，改善电极反应动力学，显著提高改性阴极在半电池高电流密度下的倍率性能。此外，NMP@NCMT-2在4.2 V以上的充放电过程中实现了从P3到OP2相的可逆相变，并在全电池中实现了高达(Capacity retention)的高比容量和出色的容量保持率。该策略能够有效且可靠地稳定界面，提高钠离子电池（NIBs）层状阴极的性能。
