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

Graphical The lithium-rich layered oxides (LLOs, Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 ) were successfully prepared based on a dual modification strategy, by co doped with anions and cations and coated with lithium carbonate coating. It founds that modified LLOs possess excellent electrochemical performance. Lithium-rich layered oxides (LLOs, Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 ) 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 −1 first turn discharge capacity, in addition to 216.9 mAh g −1 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 3 2− , 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.