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 co...