Flower‐like NiCo‐carbonate Hydroxides for High‐performance Solid‐state Hybrid Supercapacitor

Abstract Compared to the traditional transition metal layered double hydroxides, transition metal layered carbonate double hydroxides (TMC‐LDHs) possess superior electrochemical performance in theory. But TMC‐LDHs have not received its deserved attention, especially for application in the energy storage field. In this work, a flower‐like TMC‐LDH (Ni 0.75 Co 0.25 (CO 3 ) 0.125 (OH) 2 , NCCO) material was successfully prepared by hydrothermal method, which exhibits a high specific capacity of 306.8 mAh g −1 (0.52 mAh cm −2 ) at 0.5 A g −1 with capacity retention of 70.5 % after 2000 cycles. The solid‐state hybrid supercapacitor device NCCO//PVA/KOH//IHPC based on the prepared NCCO material and an interconnected hierarchical porous carbon (IHPC) delivers a high specific energy of 50.96 Wh kg −1 at a specific power of 1.06 kW kg −1 , and a high specific energy of 36.39 Wh kg −1 still can be delivered at a high specific power of 10.49 kW kg −1 . More than 181.2 % of initial specific capacity is retained after 12000 cycles. The specific energy, energy retention under large specific power, and the cycle stability of the assembled device are better than most of the solid‐state hybrid supercapacitors that have been reported. These results demonstrate the promising prospect of the TMC‐LDH material in the practical application in advanced solid‐state supercapacitors.