Abstract
The O3-Na0.85Ni0.2Fe0.4Mn0.4O2 layered oxide cathode material possesses the advantages of high spe-cific capacity,low cost,and simple synthesis.However,sluggish kinetics and complicated phase tran-sition caused by the large size difference between Na+and tetrahedral gaps lead to poor rate and cy-cling performance.Therefore,a scalable and feasible strategy was proposed to modulate local chem-ical environment by introducing Mg2+and B3+into O3-Na0.85Ni0.2Fe0.4Mn0.4O2,which can distinctly improve kinetic transport rate as well as electrochemical performance.The capacity retention of O3-(Na0.82Mg0.04)(Ni0.2Fe0.4Mn0.4)B0.02O2(NFMB)increases from 43.3％and 12.4％to 89.5％and 89.0％at 1 C and 3 C after 200 cycles,respectively.Moreover,the electrode still delivers high rate capacity of 93.9 mAh/g when current density increases to 10 C.Mg2+ions riveted on Na layer act as a"pillar"to stabi-lize crystal structure and inhibit structural change during the desodiumization process.B3+ions entering tetrahedral interstice of the TM layer strengthen the TM-O bond,lower Na+diffusion energy barrier and inhibits the slip of TM layer.Furthermore,the assembled full batteries with the modified cathode ma-terial deliver a high energy density of 278.2 Wh/kg with commercial hard carbon as anode.This work provides a strategy for the modification of high-performance SIB layered oxide materials to develop the next-generation cost-effective energy storage grid systems.
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