Advanced MnOx/MnWO4 hetero-nanoflakes with abundant oxygen vacancies for high-performance flexible asymmetric supercapacitors with high energy density

Abstract

FSCs have attracted considerable attention owing to their high power density, long cycling lifespan and high environmental friendliness. However, the low capacitance of anode materials restricts the development of FSCs. Herein, novel MnO_x/MnWO₄@C nanoflakes with the optimal W-doping content were successfully achieved, which integrated abundant oxygen vacancies induced by W-doping, high electrical conductivity by conductive carbon layers and high surface area by the ultra-large nanoflake morphology. Benefiting from the synergistic effect of abundant redox active centers, fast charge mobility and good structural stability, MnO_x/MnWO₄@C anodes exhibit outstanding electrochemical performances with a high specific capacitance of 888.63 mF cm⁻² at 0.1 mA cm⁻², a predominant rate capacity of 173.3 mF cm⁻² at an ultrahigh current density of 80 mA cm⁻². More impressively, the FSCs assembled with MnO_x/MnWO₄@C anodes and NCM-41 cathodes provide a high energy density of 48.49 mW h cm⁻² at a power density of 4320 mW cm⁻² and long cycling stability, which highlights their great potential for high energy storage.