Sophora-like Nickel–Cobalt Sulfide and Carbon Nanotube Composites in Carbonized Wood Slice Electrodes for All-Solid-State Supercapacitors

Abstract

As a naturally ordered porous material, wood has many unique advantages in the field of energy storage. After carbonization, it can be directly loaded with active materials to form a self-supporting electrode material without a conductive agent and binder. Here, carbon nanotube (CNT) arrays are grown in wood tracheids by chemical vapor deposition, and nickel–cobalt sulfide (NCS) nanosheets are deposited on CNTs by electrochemical deposition to build self-supporting electrodes. CNTs are similar to the inflorescence axis to distribute nutrients, which is an excellent passage for electron transportation; NCS nanosheets, similar to Sophora flowers, exhibit better electrochemical properties after compounding with CNTs. The composite electrode based on NCS and CNTs in a carbonized wood slice (CWS) achieves an excellent specific capacity of 8.62 F cm–2 at 5 mA cm–2. The all-solid-state hybrid supercapacitor assembled with NCS/CNT@CWS as the cathode and CNT@CWS as the anode expresses a high specific capacitance of 0.85 F cm–2 at 5 mA cm–2, and the capacitance is retained at 92.86% even after 10,000 cycles.