Blocky electrode prepared from nickel-catalysed lignin assembled woodceramics

Blocky woodceramic electrode materials are prepared by Ni(NO₃)₂ catalysis and K₂CO₃ activation with waste poplar wood which is self-assembled with pulping black liquor lignin. The results show that the natural hierarchical pore structure of wood can be well preserved, and the activation, catalytic graphitisation, and Ni²⁺ doping are accomplished simultaneously in the sintering process. Meanwhile, some of the lignin which self-assembled onto the pore surface of wood and on the crystal surface of activator and catalyst is transformed into carbon nanosheet and multilayer graphene, and some present an orderly arrangement according to the original form of the crystal. Ni²⁺ doping not only builds the basic form of electrode but also reduces the stacks of carbon nanosheet and multilayer graphene. Meanwhile, activation can improve the pore structure, providing more channels for the storage and transmission of electrons and ions. At the current density of 0.25 A g⁻¹, the specific capacitance of the sample can reach 150.8 F g⁻¹.