In Situ Growth and Electrochemical Activation of Copper-Based Nickel–Cobalt Hydroxide for High-Performance Energy Storage Devices

Abstract

Herein, an effective electrochemical activation strategy is designed to enhance the overall energy storage performance of copper-based (Cu-based) nickel−cobalt hydroxide (NiCo−OH). The long-term cyclic voltammetry (CV) cycling process in an alkaline electrolyte triggered the in situ transformation from Cu-doped NiCo−OH (Cu/NiCo−OH) to electrochemically activated CuO-doped NiCo−OH (EA-CuO/NiCo−OH) on a porous Cu foam (CF) substrate, together with the significantly increased charge storage capacity.Benefiting from fast electron/ion transfer, abundant surface defects, and powerful synergistic effect contributed by the unique self-supported heterostructure, the EA-CuO/NiCo−OH electrode can achieve a high areal capacity of 4.186 C cm −2 under 5 mA cm −2 , with excellent rate performance (67.5% of initial capacity under 50 mA cm −2 ) and long life span (84.8% of initial capacity after 5000 cycles). The as-fabricated EA-CuO/NiCo−OH//AC hybrid supercapacitor device shows a maximum energy density of 0.648 mW h cm −2 and an outstanding cycling stability (93.4% of initial capacity after 8000 cycles). The superior energy storage performance underpins the high potential of the reported electrochemical activation strategy for developing advanced Cu-based and bimetallic hydroxide-derived electrode materials.

Effect of Microwave Power and Cu Doping on MnO2 Nanostructures and Its Supercapacitor Performance

“…SCs are classified based on their electrode material energy storage mechanism as electric double-layer capacitor (EDLC) type and pseudocapacitor type . The charge storage mechanism in the EDLC type of the electrode material responsible for high power density is based on charge separation between the interface of the electrode and the electrolyte, which is higher for materials with high specific surface area, e.g., carbonaceous materials. , Carbonaceous materials in the form of carbon quantum dots, carbon nanotubes, graphene, porous carbon, carbon nanofibers, and carbon cloth provide high conductivity, mechanical strength, and flexibility to electrochemical energy storage devices. , The pseudocapacitive-type electrode materials store charges by the redox reactions of the transition metal oxide materials, i.e., MnO 2 , RuO 2 , TiO 2 , MoO 3 , WO 3 V 5 O 12 /VO 2 , etc. − Hybrid supercapacitors, which have the combined effect of EDLC and pseudocapacitive behavior, have superior energy storage performance. Energy storage performance can be enhanced by tuning the porosity of the electrode active materials.…”

“…10 The charge storage mechanism in the EDLC type of the electrode material responsible for high power density is based on charge separation between the interface of the electrode and the electrolyte, which is higher for materials with high specific surface area, e.g., carbonaceous materials. 11,12 Carbonaceous materials in the form of carbon quantum dots, carbon nanotubes, graphene, porous carbon, carbon nano-fibers, and carbon cloth provide high conductivity, mechanical strength, and flexibility to electrochemical energy storage devices. 13,14 The pseudocapacitive-type electrode materials store charges by the redox reactions of the transition metal oxide materials, i.e., MnO 2 , RuO 2 , TiO 2 , MoO 3 , WO 3 V 5 O 12 / VO 2 , etc.…”