High rate and ultralong life flexible all-solid-state zinc ion battery based on electron density modulated NiCo2O4 nanosheets

The development of zinc ion batteries (ZIBs) with large capacity,high rate,and durable cathode material is a crucial and urgent task.Ni Co2O4(NCO) has received ever-growing interest as a potential cathode material for ZIBs,owing to the high theoretical capacity,rich source,cost-effective,and versatile redox nature.However,due to the slow dynamics of the NCO electrodes,its practical application in highperformance systems is severely limited.Herein,we report an electron density modulated NCO nanosheets (N-NCO NSs) with high-kinetics Zn2+-storage capability as an additive-free cathode for flexible all-solid-state (ASS) ZIBs.By virtue of the enhanced electronic conductivity,improved reaction kinetics,and increased active sites,the optimized N-NCO NSs electrode delivers a high capacity of 357.7 m Ah g-1at 1.0 A g-1and a superior rate capacity of 201.4 m Ah g-1at 20 A g-1.More importantly,a flexible ASS ZIBs device is manufactured using a solid polymer electrolyte of a poly (vinylidene fluoride hexafluoropropylene)(PVDF-HFP) film.The flexible ASS ZIBs device shows superb durability with 80.2%capacity retention after 20,000 cycles and works well in the range of-20–70°C.Furthermore,the flexible ASS ZIBs achieves an impressive energy density as high as 578.1 W h kg-1with a peak power density of 33.6 k W kg-1,substantially outperforming those latest ZIBs.This work could provide valuable insights for constructing high-kinetics and high-capability cathodes with long-term stability for flexible ASS ZIBs.