Synthesis of high-performance nickel hydroxide nanosheets/gadolinium doped-α-MnO2 composite nanorods as cathode and Fe3O4/GO nanospheres as anode for an all-solid-state asymmetric supercapacitor

The wide use of manganese dioxide(MnO₂)as an electrode in all-solid-state asymmetric supercapacitors(ASCs)remains challenging because of its low electrical conductivity.This complication can be circumvented by introducing trivalent gadolinium(Gd)ions into the MnO₂.Herein,we describe the successful hydrothermal synthesis of crystalline Gd-doped MnO₂ nanorods with Ni(OH)₂ nanosheets as cathode,which we combined with Fe₃O₄/GO nanospheres as anode for all-solid-state ASCs.Electrochemical tests dem on strate that Gd dopi ng sign ifica ntly affected the electrochemical activities of the MnO₂,which was further enhanced by introducing Ni(OH)₂.The GdMnO₂/Ni(OH)₂ electrode offers sufficient surface electrochemical activity and exhibits excellent specific capacity of 121.8 mA h g^-1,at 1A g^-1,appealing rate performance,and ultralong lifetime stability(99.3%retention after 10,000 discharge tests).Furthermore,the GdMnO₂/Ni(OH)₂//PVA/KOH//Fe₃O₄/GO solid-state ASC device offers an impressive specific energy density(60.25 W h kg^-1)at a high power density(2332 W kg^-1).This investigation thus shows its large potential in developing novel approaches to energy storage devices.