Thermally Engineered Rice Husk-Derived Carbon Anodes with Metal Oxide Hybridization

Valorization of agricultural residues into high-performance energy storage materials offers a sustainable pathway for circular resource utilization and reduced reliance on critical raw materials. Herein, we report the synthesis and evaluation of rice husk-derived carbon anodes for lithium-ion batteries, demonstrating the influence of thermal processing on structure and electrochemical performance and then compositing the higher performing electrode with metal oxide. First two distinct carbons were produced via thermal treatment at 1000 and 1900 °C, yielding leached low-temperature (LLT) and leached high-temperature (LHT) carbons with contrasting nanostructures. The ex-situ electrochemical impedance spectroscopy, ultraviolet photoelectron spectroscopy, and scanning electron microscopy reveal how thermal history governs structural order, surface chemistry, charge-transfer behavior, and solid electrolyte interphase (SEI) formation. LLT exhibits a high reversible lithiation capacity (650 mAh g−1 at the 2nd cycle), arising from its highly disordered, high-surface-area carbon framework that enables defect- and surface-driven lithium storage, albeit with increased interfacial reactivity. In contrast, LHT delivers a lower reversible capacity (∼220 mAh g−1) but superior cycling stability and near-unity coulombic efficiency (≈100%), retaining 97% of its capacity after 65 cycles, attributable to lithium intercalation within more ordered graphitic domains and the formation of a thinner, more stable SEI, consistent with EIS observations. Furthermore, rational hybridization of LLT with MnO2 (30 wt %) significantly enhances reversible lithiation (∼992 mAh g−1 at the 2nd cycle), demonstrating that controlled compositing can synergistically improve electrochemical performance. Overall, this work establishes a scalable framework for tailoring waste-derived carbon anodes through controlled thermal processing and metal-oxide compositing, advancing sustainable materials strategies for next-generation lithium-ion batteries.