PO43-掺杂和AlF3包覆协同增强Li1.2Ni0.13Co0.13Mn0.54O2正极材料电化学性能

本研究采用PO₄^3-掺杂和AlF₃包覆的协同改性策略制备了P-LNCM@AlF₃正极材料(P=PO₄^3- ，LNCM=Li_1.2Ni_0.13Co_0.13Mn_0.54O₂)，提高了LNCM的结构稳定性以及抑制了界面副反应。其中，大四面体的PO₄^3-聚阴离子掺杂在晶格中抑制了过渡金属离子的迁移，降低体积变化，从而稳定了晶体结构，而且PO₄^3-掺杂能够扩大锂层间距，促进Li⁺的扩散，从而提升材料的倍率性能。此外，AlF₃包覆层能抑制材料与电解液的副反应从而提升界面稳定性。基于以上优势，P-LNCM@AlF₃正极表现出了优异的电化学性能。在1C电流密度下表现出了179.2 mAh·g^-1的放电比容量，循环200圈后仍有161.5 mAh·g^-1的放电比容量，容量保持率可达90.12%。即使在5C的高电流密度下仍可提供128.8 mAh·g^-1的放电比容量。

PO43- doping and AlF3 coating synergistically enhancing electrochemical properties of Li1.2Ni0.13Co0.13Mn0.54O2 cathode material

The lithium-rich manganese-based material (Li_1.2Ni_0.13Co_0.13Mn_0.54O₂, LNCM) is susceptible to structural transformations and interfacial side reactions during charge and discharge, leading to rapid capacity decay and posing significant challenges for its commercial application. In this study, a synergistic modification strategy involving PO₄^3- (P) doping and AlF₃ coating was employed to prepare the P-LNCM@AlF₃ cathode material, which enhances the structural stability of LNCM and suppresses interfacial side reactions. Among them, the large tetrahedral PO₄^3- polyanion doping in the lattice can inhibit the migration of transition metal ions and reduce the volume change due to its stronger bonding with transition metal ions compared to oxygen, thus stabilizing the crystal structure. Moreover, the PO₄^3- doping can expand the lithium layer spacing and promote the diffusion of Li⁺, thus enhancing the multiplicative performance of the material. In addition, the AlF₃ nanolayer coating on the surface of the active material reduces its contact with the electrolyte, which can inhibit the side reaction between the material and the electrolyte and thus enhance the interfacial stability. Based on these advantages, the P-LNCM@AlF₃ cathode exhibited excellent electrochemical performance. It exhibited a discharge specific capacity of 179.2 mAh·g^-1 at a current density of 1C and 161.5 mAh·g^-1 after 200 cycles, with a capacity retention rate of 90.12%. Even at a high current density of 5C, a discharge capacity of 128.8 mAh·g^-1 could be achieved.