Li Zhi, Cao Shuang, Chen Jiarui, Wu Lei, Chen Manfang, Ding Hao, Wang Ruijuan, Guo Wei, Bai Yansong, Liu Min, Wang Xianyou
National Base for International Science & Technology Cooperation, National Local Joint Engineering Laboratory for Key Materials of New Energy Storage Battery, Hunan Province Key Laboratory of Electrochemical Energy Storage & Conversion, School of Chemistry, Xiangtan University, Xiangtan, 411105, China.
College of New Energy, Ningbo University of Technology, Ningbo, Zhejiang, 315336, China.
Small. 2024 Nov;20(44):e2400641. doi: 10.1002/smll.202400641. Epub 2024 Jul 11.
Li-rich manganese-based cathode (LRMC) has attracted intense attention to developing advanced lithium-ion batteries with high energy density. However, LRMC is still plagued by poor cyclic stability, undesired rate capacity, and irreversible oxygen release. To address these issues, herein, a feasible polyvinylidene fluoride (PVDF)-assisted interface modification strategy is proposed for modulating the surface architecture and electronic conductivity of LRMC by intruding the F-doped carbon coating, spinel structure, and oxygen vacancy on the LRMC, which can greatly enhance the cyclic stability and rate capacity, and restrain the oxygen release for LRMC. As a result, the modified material delivers satisfactory cyclic performance with a capacity retention of 90.22% after 200 cycles at 1 C, an enhanced rate capacity of 153.58 mAh g at 5 C and 126.32 mAh g at 10 C, and an elevated initial Coulombic efficiency of 85.63%. Moreover, the thermal stability, electronic conductivity, and structure stability of LRMC are also significantly improved by the PVDF-assisted interface modification strategy. Therefore, the strategy of simultaneously modulating the surface architecture and the electronic conductivity of LRMC provides a valuable idea to improve the comprehensive electrochemical performance of LRMC, which offers a promising reference for designing LRMC with high electrochemical performance.
富锂锰基正极材料（LRMC）在开发具有高能量密度的先进锂离子电池方面引起了广泛关注。然而，LRMC仍然受到循环稳定性差、倍率性能不理想和不可逆氧释放的困扰。为了解决这些问题，本文提出了一种可行的聚偏氟乙烯（PVDF）辅助界面改性策略，通过在LRMC上引入F掺杂碳涂层、尖晶石结构和氧空位来调节LRMC的表面结构和电子导电性，这可以大大提高LRMC的循环稳定性和倍率性能，并抑制其氧释放。结果，改性材料具有令人满意的循环性能，在1 C下循环200次后容量保持率为90.22%，在5 C下倍率性能增强至153.58 mAh g，在10 C下为126.32 mAh g，初始库仑效率提高到85.63%。此外，PVDF辅助界面改性策略还显著提高了LRMC的热稳定性、电子导电性和结构稳定性。因此，同时调节LRMC表面结构和电子导电性的策略为改善LRMC的综合电化学性能提供了有价值的思路，为设计具有高电化学性能的LRMC提供了有前景的参考。
