Cobalt Hydroxide Nanosheets Grown on Carbon Nanotubes Anchored in Wood Carbon Scaffolding for High-Performance Hybrid Supercapacitors

A novel green and sustainable self-supporting electrode for an excellent performance hybrid supercapacitor (HSC) based on hybridizing Co(OH)2 nanosheets with carbon nanotube (CNT) arrays in wood carbon scaffolding made of Chinese fir waste is designed. The composite electrode has an area specific capacity as high as 4.17 mA h cm–2 due to the synergy of the wood carbon scaffolds, CNTs, and Co(OH)2 nanosheets. The HSC constructed with the composite electrode and the CNT/carbonized wood electrode obtains a specific capacitance of 2.88 F cm–2, and after 11,000 cycles, the capacity retention rate of the HSC is still 97.8%, and its maximum energy and power density are 0.78 mW h cm–2 and 34.40 mW cm–2, respectively. The in situ growth of CNTs in carbonized wood can avoid aggregation and provide fast electron-transfer paths, and CNTs are wrapped by Co(OH)2 nanosheets by electrochemical deposition to obtain excellent electrochemical energy storage performance. This novel family of wood-derived materials represents a general and abundant candidate toward real-world energy storage applications.