Lithium-ion capacitor using rice husk-derived cathode and anode active materials adapted to uncontrolled full-pre-lithiation

Rice husk (RH), agricultural waste produced from rice harvest, is investigated as a potential source for cathode and anode active materials in lithium-ion capacitors (LICs). A carbonized mixture composed of pre-heated RH and beet sugar is subjected to silica removal via immersion in NaOH solution followed by activation using CO₂ gas. This yields activated carbon with a specific surface area of 1801 m² g⁻¹ as the cathode active material. The anode active material is produced by carbonizing RH and partly removing 41 mass% of silica. The charge-discharge performances of a three-electrode LIC full-cell, using the RH-derived cathode and anode active materials with Li metal as the reference electrode, are evaluated under the uncontrolled full-pre-lithiation in comparison with similar three-electrode LIC full-cells using a commercial cathode and anode (graphite or hard carbon) active materials. The results of charge-discharge tests reveal that excellent rate and cycling stabilities are obtained from the LIC using RH-derived active materials in comparison with those using commercial active materials. Postmortem material characterizations suggest that the performance stability of the RH-derived LIC is attributed to the passivation ability of silica for excessive Li delivered via the full pre-lithiation process.