In-situ activated pore structure engineering via Ca(AC)2 template towards high areal capacity for wood-derived thick carbon electrode in lithium-ion batteries

Natural woods are increasingly recognized as promising green candidates for high areal capacity wood-based hard carbon thick electrodes (WHCTEs). Their unique 3-D transport network features abundant straight, open channels aligned along the longitudinal direction, which has attracted significant attention in recent years. However, direct carbonization yields underdeveloped pore structures, restricting electrochemical active surfaces and lithium storage performance. To address this issue, calcium acetate (Ca(AC)₂) was employed as a templating agent to engineer hierarchical porous architectures. Systematic studies reveal adjustable Ca(AC)₂ dosage effectively modulates pore structures, with BET analysis confirming meso-/macropore distributions (2–130 nm) in all samples. This optimized porosity reduces electrode impedance and enhances lithium storage, delivering record areal capacities of 6.81/3.89 mAh cm^-2 at 0.1/1.0 mA cm^-2, which is 190%/110% higher than commercial graphite electrode (3.5–3.6 mAh cm^-2. Kinetic analysis further identifies an “adsorption-insertion” dual lithium storage mechanism. The widely distributed porosity significantly contributes to performance improvements, demonstrating a viable strategy for developing sustainable WHCTEs. These findings provide critical insights for designing thick carbon electrodes in alkali-metal-ion batteries.