Artificial interface layer construction and sodium storage performance of P2-type layered oxide cathode
P2-type Na2/3Ni1/3Mn2/3O2(P2-NNMO)has high working voltage,good safety,and low cost,making it a promising cathode material for sodium ion batteries.To solve the problem of sodium deficiency of P2-NNMO cathode and the interface between P2-NNMO cathode and electrolyte,an inorganic-rich artificial interface layer was constructed on P2-NNMO cath-ode via a chemical pre-sodiation method(spontaneous redox reaction between P2-NNMO cathode and sodium biphenyl),with which extra sodium ions insert the oxide cathode host structure.The results showed that the artificial interface layer formed by pre-sodiation contained NaF,shielded cathode material solvent corrosion and transition metal dissolution,and im-proved the diffusion kinetics of Na+.The modified cathode(P2-NNMO@CEI)delivered the discharge specific capacity of 95.1 mA∙h/g and the coulombic efficiency of 88.5%within the voltage of 2～4 V at the current density of 20 mA/g and pos-sessed capacity retention of 84.2%after 280 cycles at the current density of 50 mA/g.This study provided an effective method for surface modification of layered oxide cathode and further provided a new concept and direction for designing in-terfaces of electrode materials toward real applications.
cathode electrolyte interfacecycling stabilitylayered oxidessodium ion batteries
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