Abstract
Natural wood is an excellent biomass source for producing hard carbon, a high-performing material for sodium-ion battery (SIB) anodes. Commercial wood products are often treated with copper-based preservatives to improve their durability and service life, but these pose environmental risks when disposed of in landfills. This study hypothesized that copper-treated wood can be transformed into hard carbon for use as a SIB anode material. We tested this hypothesis by pyrolyzing untreated and copper-based treated wood into hard carbon, analyzing its microstructure, and evaluating its electrochemical performance as an anode material in SIB coin cells. The produced hard carbons demonstrated satisfactory electrochemical performance, surpassing the commercially tested counterpart in terms of reversible capacity. Copper (II) content of the treated wood was reduced to metallic copper during pyrolysis and triggered the formation of carbon whisker on wood surfaces, which increased the conductivity of the hard carbon but inversely influenced its electrochemical performance by slightly increasing the irreversible capacity of the batteries. It is concluded that recycling copper containing wood into hard carbon for SIBs offers a promising, sustainable alternative to conventional waste disposal. In addition to improving properties like porosity and conductivity, the process also generates carbon whiskers, offering further potential for applications in energy storage, the process industry, and beyond.