Rich‐Carbonyl Carbon Catalysis Facilitating the Li ₂ CO ₃ Decomposition for Cathode Lithium Compensation Agent

Abstract The active lithium loss of lithium‐ion batteries can be well addressed by adding a cathode lithium compensation agent. Due to the poor conductivity and electrochemical activity, lithium carbonate (Li ₂ CO ₃ ) is not considered as a candidate. Herein, an effective cathode lithium compensation agent, the recrystallized Li ₂ CO ₃ combined with large specific surface area disordered porous carbon (R‐LCO@SPC) is prepared. The screened SPC makes it easier for nano‐sized Li ₂ CO ₃ to adsorb and decompose on carbon substrate, meantime, exposing plenty of catalytic active sites of C═O, which can significantly improve the electrochemical activity and conductivity of Li ₂ CO ₃ , thus greatly reducing the decomposition potential of Li ₂ CO ₃ (4.0 V) and releasing high irreversible capacity (580 mAh g ⁻¹ ) compared to the unmodified Li ₂ CO ₃ (nearly no capacity above 4.6 V). Meantime, the Li ₂ CO ₃ can disappear completely without any by‐product after the initial cycle accompanied by partially dissolved in electrolyte, optimizing the composition of SEI. The resultant lithium compensation agent applied to LMFP//graphite full cell exhibits a 19.1% increase in energy density, enhancing the rate and cycling performance, demonstrating great practical applications potential in high energy density lithium‐ion batteries.