Dual Strategies with Anion/Cation Co-Doping and Lithium Carbonate Coating to Enhance the Electrochemical Performance of Lithium-Rich Layered Oxides.

Lithium-rich layered oxides (LLOs, Li Mn Ni Co O ) are widely used as cathode materials for lithium-ion batteries due to its high specific capacity, high operating voltage and low cost. However, the LLOs are faced with rapid decay of charge/discharge capacity and voltage, as well as interface side reactions, which limit its electrochemical performance. Herein, the dual strategies of sulfite/sodium ion co-doping and lithium carbonate coating were used to improve it. It founds that modified LLOs achieve 88.74 % initial coulomb efficiency, 295.3 mAh g first turn discharge capacity, in addition to 216.9 mAh g at 1 C, and 87.23 % capacity retention after 100 cycles. Mechanism research indicated that the excellent electrochemical performance benefits from the doping of both Na and SO , and it could significantly reduce the migration energy barrier of Li and promote Li migration. Meanwhile, anion and cation are co-doped greatly reduces the band gap of LLOs and increase its electrical conductivity, and its binding effect on Li is weakened, making it easier for Li to shuttle through the material. In addition, the lithium carbonate coating significantly inhibits the occurrence of interfacial side reactions of LLOs. This work provides a theoretical basis and practical guidance for the further development of LLOs with higher electrochemical performance.