Liu Kailin, Zhang Qiangfeng, Lu Zheng, Zhu Haipeng, Song Miao, Chen Libao, Zhang Chunxiao, Wei Weifeng
Powder Metallurgy Research Institute, Central South University, Changsha, Hunan 410083, P. R. China.
State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, P. R. China.
ACS Appl Mater Interfaces. 2024 Mar 27;16(12):14902-14911. doi: 10.1021/acsami.4c00291. Epub 2024 Mar 14.
Li-rich Mn-based layered oxides (LMLOs) are expected to be the most promising high-capacity cathodes for the next generation of lithium-ion batteries (LIBs). However, the poor cycling stability and kinetics performance of polycrystalline LMLOs restrict their practical applications due to the anisotropic lattice stress and crack propagation during cycling. Herein, B-doped micron-sized single-crystal Co-free LMLOs were obtained by molten-salt (LiNO and HBO)-assisted sintering. The results reveal that the low-melting-point molten salt can serve as liquid-phase media to improve the efficiency of atomic mass transfer and crystal nucleation and growth. The modified single-crystal LMLO cathodes can resist the accumulation of anisotropic stress and strain during the cycling and reduce interface side reactions, thus achieving excellent high-voltage stability and kinetics performance. The reversible specific capacity of the single crystals is 210.8 mAh g at 1C with a voltage decay rate of 1.95 mV/cycle and up to 161.1 mAh g at 10C with a capacity retention of 81.06% after 200 cycles.
富锂锰基层状氧化物（LMLOs）有望成为下一代锂离子电池（LIBs）中最具潜力的高容量正极材料。然而，多晶LMLOs较差的循环稳定性和动力学性能限制了其实际应用，这是由于循环过程中的各向异性晶格应力和裂纹扩展所致。在此，通过熔盐（LiNO₃和H₃BO₃）辅助烧结制备了B掺杂的微米级单晶无钴LMLOs。结果表明，低熔点熔盐可作为液相介质，提高原子质量传递以及晶体成核和生长的效率。改性后的单晶LMLO正极在循环过程中能够抵抗各向异性应力和应变的积累，并减少界面副反应，从而实现优异的高电压稳定性和动力学性能。单晶在1C下的可逆比容量为210.8 mAh g，电压衰减速率为1.95 mV/循环；在10C下可达161.1 mAh g，200次循环后容量保持率为81.06%。
