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 NaNiMnO 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 NaNiMnO cathode. The modified NaNiCuMnO layered cathode with hollow porous microrod structure exhibits an excellent reversible capacity of 167.5 mAh g at 150 mA g and maintains a capacity above 95 mAh g after 300 cycles at 750 mA g. 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.