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. NiCo2O4 (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 high-performance 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 mAh g(-1) at 1.0 A g(-1) and a superior rate capacity of 201.4 mAh g(-1) at 20 A g(-1). More importantly, a flexible ASS ZIBs device is manufactured using a solid polymer electrolyte of a poly (vinylidene fluoride hexafluoro-propylene) (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 degrees C. Furthermore, the flexible ASS ZIBs achieves an impressive energy density as high as 578.1 W h kg(-1) with a peak power density of 33.6 kW 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. (C) 2022 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.