高倍率长寿命P2型钠离子电池正极材料OA

Cathode materials play a critical role in determining the energy density,cycle life,and cost-effectiveness of sodium-ion batteries(SIBs).Among various candidates,P2-type layered oxide cathodes exhibit superior high-rate charge/discharge performance due to their open Na+diffusion channels,making them particularly suitable for applications requiring rapid power delivery,such as starter batteries and grid frequency regulation.However,while the conventional P2-type Na0.67Ni0.33Mn0.67O2(P2-NNMO)cathode demonstrates high energy density,the strong O2--O2-electrostatic repulsion within the transition metal layer during high-voltage charging induces an irreversible P2 → O2 phase transition accompanied by approximately 20%volume strain.This results in severe lattice distortion and structural collapse.Additionally,oxygen oxidation at high voltages contributes to charge compensation,reducing electrochemical reaction reversibility and accelerating structural degradation.Consequently,the P2-NNMO cathode suffers from rapid capacity decay and poor cycling stability,hindering its practical application.To overcome these challenges,we developed a multi-element doping strategy to design a P2-Na0.67Zn0.05Ni0.23Fe0.1Mn0.57Ti0.05O2(P2-NZNFMTO)layered oxide cathode.The synergistic doping of Zn2+,Ti4+,and Fe3+enables concurrent optimization of structural and electrochemical properties.Specifically,Zn2+doping enhances the O2--Na+-O2-electrostatic interaction,promoting the formation of local"Na+pillars"within the Na layer to mitigate volume variation and phase transitions during cycling.Ti4+doping disrupts Na+/vacancy ordering,significantly improving Na+diffusion kinetics.The incorporation of Zn2+,Ti4+,and Fe3+also alleviates the Jahn-Teller distortion associated with Ni2+/Ni3+,enhancing cycling performance while reducing material costs.The P2-NZNFMTO cathode exhibits exceptional electrochemical performance,demonstrating 96.7%capacity retention after 100 cycles at 1C rate with a high cut-off voltage of 4.3 V.Even at a high rate of 3C,it maintains over 85%capacity retention after 300 cycles.In-situ X-ray diffraction(XRD)and galvanostatic intermittent titration technique(GITT)analyses confirm its excellent structural stability and rapid Na+transport capability at high voltages.This multi-element synergistic doping strategy establishes a novel design principle and theoretical foundation for developing high-voltage,long-cycle-life,and high-power SIB cathodes.