摘要
P2-type layered metal oxides have been considered as one of the promising cathode candidates for high-performance Na-ion batteries(SIBs).However,it is still challenging to balance the contradiction of high energy density and long cycle life due to the structural degradation and sluggish ion diffusion dynamics.Here,the hierarchical P2-Na2/3Ni1/3Mn2/3O2 hollow microspheres assembled by nanosheets are constructed via a self-template approach.The obtained nanosheets with more exposed electrochemical active planes serving as desodiation/sodiation reactors can provide substantial Na+channels,shorten the diffusion pathways,and accommodate the volume changes during charge/discharge process.Benefiting from the facile Na+diffusion paths and optimal architecture modulation,the cathode delivers a high initial Coulombic efficiency of 96.0%with a high energy density of 299.7 Wh·kg^(−1).The highly reversible structural evolutions processes are verified by galvanostatic intermittent titration technique(GITT)and operando electrochemical impedance spectroscopy(EIS)measurement,which would significantly improve the cycle stability(83.3%capacity retention at 1.0 C over 500 loops).Furthermore,the full cell assembled by hard carbon presents a high reversible capacity of 71 mAh·g^(−1)at 0.2 C and promising capacity retention(91.5%after 50 cycles).The designing concept of morphological configuration in this work paves an accessible route for building high-performance electrode materials.
基金
supported by the National Natural Science Foundation of China(No.91963109)
the Fundamental Research Funds for the Central Universities(No.2172019kfyRCPY100).
