Microwave-assisted synthesis of hybrid supercapacitors consisting of Ni, Co-layered double hydroxide shell assembled around wood-derived activated carbon fiber core

• NiCo-LDH nanorod arrays microsphere are spontaneously fabricated on melt-spinning ACFs. • The synergistic effect contributes to improved electrochemical performance. • A capacitance of 1453.3 F g −1 at 1 A g −1 were obtained by NiCo-LDH@ACF-120 electrodes. • The supercapacitor device shows high energy density of 52.2 Wh kg −1 at 800 W kg −1 . • The capacitance retention of supercapacitor device is 79.8 % after 10 000 cycles. Activated carbon fibers (ACFs) are prepared from the discarded fir wood using two-step melt-spinning and CO 2 activation post-treatment. Then, composites composed of these ACFs and Ni, Co-layered double hydroxides (NiCo-LDH@ACF) are synthesized by a microwave-assistant hydrothermal strategy. NiCo-LDHs agglomerated around ACFs, forming core-shell structures with sheet- or microsphere-like morphologies, which provide large surface area, hierarchical porosity, and numerous active sites for efficient charge and mass transfer. The NiCo-LDH@ACFs are used as an active material to construct the supercapacitors, the highest of capacitance and the corresponding rate performance of which are equal to 1453.3 F/g at 1 A/g and 78% at 10 A/g by microwave-assistant hydrothermal at 120 °C, respectively. We also use this material to assemble an asymmetric supercapacitor using activated carbon derived from fir bark as a negative electrode. The resulting device demonstrates excellent capacitance (equal to 146.9 F/g at 1.6 V), very high energy density (equal to 52.2 Wh/kg at 800 W/kg), and cycle life (judging by the 79.8% capacitance retention after 10000 cycles).