Construction of polyaniline/MnO2 core-shell nanocomposites in carbonized wood tracheids for high-performance all-solid-state asymmetric supercapacitors

Abstract

Polyaniline (PANI) nanomaterials or carbon nanotubes (CNTs) are first synthesized on the tracheid wall of activated wood carbon (AWC) to obtain PANI@AWC and CNT@AWC, respectively. Then MnO2 nanosheets are electrodeposited on the outer surface of the PANI nanomaterials to form a core-shell structure. The introduction of PANI in wood tracheids not only increases the loading of MnO2, but also improves the electrical conductivity and structural stability, and the core-shell structure can synergistically store energy. Then using the MnO2/PANI@AWC composite electrode as an anode and using CNT@AWC as a cathode, a high-performance all-solid-state asymmetric supercapacitor with high energy density and high cycling stability is successfully constructed. This supercapacitor has a wide working voltage of 0–1.8 V and a high energy density of 0.875 mWh cm−2 at 9 mW cm−2. The capacitance retention rate is as high as 93.21 % after 10,000 charge-discharge cycles. Therefore, wood-based composites with aligned tracheids have great potential in the development of high-power and high-energy-density energy storage devices.