Li Fangyan, Jiao Yiding, Yang Shuo, Mao Wei, Tao Qiantu, Bai Chenyu, He Er, Li Luhe, Ye Tingting, Li Yiran, Wang Jiacheng, Ren Junye, Wang Yuanzhen, Gao Rui, Li Qianming, Lu Jiang, Song Jie, Ma Jing, Deng Yu, Wang Peng, Zhang Ye
National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, Chemistry, Biomedicine Innovation Center, Collaborative Innovation Center of Advanced Microstructures, College of Engineering and Applied Sciences, Nanjing University, Nanjing, 210023, China.
Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China.
Small. 2024 Nov;20(47):e2406116. doi: 10.1002/smll.202406116. Epub 2024 Aug 28.
LiMnO spinel is emerging as a promising cathode material for lithium-ion batteries, largely due to its open framework that facilitates Li diffusion and excellent rate performance. However, the charge-discharge cycling of the LiMnO cathode leads to severe structural degradation and rapid capacity decay. Here, an electrochemical activation strategy is introduced, employing a facile galvano-potentiostatic charging operation, to restore the lost capacity of LiMnO cathode without damaging the battery configuration. With an electrochemical activation strategy, the cycle life of the LiMnO cathode is extended from an initial 1500 to an impressive 14 000 cycles at a 5C rate with Li metal as the anode, while increasing the total discharge energy by ten times. Remarkably, the electrochemical activation enhances the diffusion kinetics of Li, with the diffusion coefficient experiencing a 37.2% increase. Further investigation reveals that this improvement in capacity and diffusion kinetics results from a transformation of the redox-inert LiMnO rocksalt layer on the surface of degraded cathodes back into active spinel. This transformation is confirmed through electron microscopy and corroborated by density functional theory simulations. Moreover, the viability of this electrochemical activation strategy has been demonstrated in pouch cell configurations with Li metal as the anode, underscoring its potential for broader application.
LiMnO 尖晶石正成为一种有前景的锂离子电池正极材料，这主要归功于其开放框架有利于锂离子扩散以及出色的倍率性能。然而，LiMnO 正极的充放电循环会导致严重的结构退化和快速的容量衰减。在此，引入了一种电化学活化策略，采用简便的恒电流 - 恒电位充电操作，以恢复 LiMnO 正极损失的容量，同时不损坏电池结构。通过电化学活化策略，以锂金属为阳极时，LiMnO 正极在 5C 倍率下的循环寿命从最初的 1500 次延长至令人印象深刻的 14000 次，同时总放电能量增加了十倍。值得注意的是，电化学活化增强了锂离子的扩散动力学，扩散系数提高了 37.2%。进一步研究表明，容量和扩散动力学的这种改善源于退化正极表面氧化还原惰性的 LiMnO 岩盐层转变回活性尖晶石。这种转变通过电子显微镜得到证实，并得到密度泛函理论模拟的佐证。此外，这种电化学活化策略在以锂金属为阳极的软包电池配置中已得到验证，突出了其更广泛应用的潜力。
