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

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 (Li₂CO₃) is not considered as a candidate. Herein, an effective cathode lithium compensation agent, the recrystallized Li₂CO₃ combined with large specific surface area disordered porous carbon (R-LCO@SPC) is prepared. The screened SPC makes it easier for nano-sized Li₂CO₃ 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 Li₂CO₃, thus greatly reducing the decomposition potential of Li₂CO₃ (4.0 V) and releasing high irreversible capacity (580 mAh g^-1) compared to the unmodified Li₂CO₃ (nearly no capacity above 4.6 V). Meantime, the Li₂CO₃ 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.