Untreated bamboo biochar as anode material for sustainable lithium ion batteries

Biochar, a carbon-rich material derived from lignocellulose biomass through pyrolysis, is being considered for lithium-ion battery (LIB) applications due to its sustainable sourcing, manufacturing, and favourable electrochemical properties. A biochar-based anode is a greener alternative to conventional materials, potentially reducing the environmental and financial costs of LIB production. Minimizing cost and simplifying the manufacturing process for LIBs drive the development of new scalable production of plant-based products to create greener anodes for lithium batteries. In this work, bamboo-based biochar (BCs) was prepared through an optimized slow pyrolysis route with two thermal treatments at 800 °C (B800) and 1000 °C (B1000), and used as a LIB anode. Compared to B1000, B800 presented higher d-spacing (d₀₀₂ = 0.3657 nm) and graphitic crystallite size (L_a = 13.8 nm), smaller pore sizes (38 Å) with higher surface area (310 m²/g), and a higher concentration of permanent free radicals (PFRs) centered on the carbon (1.85 × 10¹⁸ spin/g). Although B1000 is slightly more conductive than B800, the physicochemical properties of B800 could enhance the lithiation of the pseudographitic structures and facilitate the reduction of Li⁺ ions due to the presence of PFRs. The half-cell LIB using B800 presented a reversible capacity of about 250 mA h/g at C/5 and long-term stability up to 450 cycles. This study highlights the potential of bamboo-based biochar as a viable and environmentally friendly anode material for the next generation of high-performance LIBs.