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

Sodium-ionbatteries (SIBs) have garnered extensive attentionsin recent years as a low-cost alternative to lithium-ion batteries.However, achieving both high capacity and long cyclability in cathodematerials remains a challenge for SIB commercialization. P3-type Na0.67Ni0.33Mn0.67O2 cathodesexhibit high capacity and prominent Na+ diffusion kineticsbut suffer from serious capacity decay and structural deteriorationdue to stress accumulation and phase transformations upon cycling.In this work, a dual modification strategy with both morphology controland element doping is applied to modify the structure and optimizethe properties of the P3-type Na0.67Ni0.33Mn0.67O2 cathode. The modified Na0.67Ni0.26Cu0.07Mn0.67O2 layeredcathode with hollow porous microrod structure exhibits an excellentreversible 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 pathwayand releases stress during cycling, leading to excellent rate performanceand high cyclability. For another, Cu doping at the Ni site reducesthe Na+ diffusion energy barrier and mitigates unfavorablephase transitions. This work demonstrates that the electrochemicalperformance of P3-type cathodes can be significantly improved by applyinga dual modification strategy, resulting in reduced stress accumulationand optimized Na+ migration behavior for high-performanceSIBs.

Automated summary

Sodium-ion batteries (SIBs) have attracted attention as a low-cost alternative to lithium-ion batteries, but achieving high capacity and long cyclability in cathode materials is challenging. This study applies a dual modification strategy of morphology control and element doping to enhance the structure and properties of P3-type Na0.67Ni0.33Mn0.67O2 cathodes. The modified Na0.67Ni0.26Cu0.07Mn0.67O2 cathode with a hollow porous microrod structure exhibits excellent reversible capacity and cyclability. The specific morphology reduces the Na+ diffusion pathway and releases stress, resulting in high rate performance and long cycling stability. Cu doping at the Ni site reduces the Na+ diffusion energy barrier and mitigates unfavorable phase transitions. This work demonstrates the significant improvement of P3-type cathode performance through a dual modification strategy for high-performance SIBs.