Dual Modification of P3-Type Layered Cathodes to Achieve High Capacity and Long Cyclability for Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have garnered extensive attentions in recent years as a low-cost alternative to lithium-ion batteries. However, achieving both high capacity and long cyclability in cathode materials remains a challenge for SIB commercialization. P3-type Na_0.67Ni_0.33Mn_0.67O₂ cathodes exhibit high capacity and prominent Na⁺ diffusion kinetics but suffer from serious capacity decay and structural deterioration due to stress accumulation and phase transformations upon cycling. In this work, a dual modification strategy with both morphology control and element doping is applied to modify the structure and optimize the properties of the P3-type Na_0.67Ni_0.33Mn_0.67O₂ cathode. The modified Na_0.67Ni_0.26Cu_0.07Mn_0.67O₂ layered cathode with hollow porous microrod structure exhibits an excellent reversible capacity of 167.5 mAh g^-1 at 150 mA g^-1 and maintains a capacity above 95 mAh g^-1 after 300 cycles at 750 mA g^-1. For one thing, the specific morphology shortens the Na⁺ diffusion pathway and releases stress during cycling, leading to excellent rate performance and high cyclability. For another, Cu doping at the Ni site reduces the Na⁺ diffusion energy barrier and mitigates unfavorable phase transitions. This work demonstrates that the electrochemical performance of P3-type cathodes can be significantly improved by applying a dual modification strategy, resulting in reduced stress accumulation and optimized Na⁺ migration behavior for high-performance SIBs.