Stable Cycling Performance of P2/O3-Type Layered Oxide Cathodes Through Li/Sn Co-Doping for Sodium-Ion Batteries.

Abstract

Sodium-ion battery (SIBs) has become a substitute for lithium-ion battery with low cost and abundant resources. Among the cathode materials, manganese-based layered oxides, including O3-type and P2-type oxides, have broad application prospects because of their high capacity and energy density. However, these materials often face the challenges of poor stability and low capacity in practical applications. This study through the design and synthesis of a new type of composite high entropy: P2/O3-Na_0.75Li_0.05Cu_0.10Fe_0.30Mn_0.50Sn_0.05O₂ to solve these limitations. The material uses Li⁺ to increase ionic conductivity and activate deep anionic redox. Sn⁴⁺ prevents charge delocalization and contributes to structural stability. Electrochemical tests showed that the specific capacity was 110 mAh g^-1 at 0.1C (1C = 200 mA g^-1), 58 mAh g^-1 at 3C, and the capacity retention rate was 80.91% after 500 cycles. This composite represents a new strategy for optimizing manganese base form oxides, providing insights for improving performance and stability.