Promoting Low-Voltage Li₂C₂O₄ Prelithiation via CoSe₂/NC Catalyst in Lithium-Ion Batteries

Self-sacrificial lithium oxalate (Li₂C₂O₄) offers high capacity, clean decomposition, and low cost, making it a promising lithium supplement for lithium-ion batteries. However, its decomposition potential, which exceeds 4.8 V, poses significant challenges to the stability and compatibility of existing electrolyte systems. In this work, the ZIF-67 metal–organic framework (MOF) is employed as a template to synthesize cobalt selenide anchored on a nitrogen-doped carbon matrix (CoSe₂/NC). Incorporating 10 wt.% CoSe₂/NC significantly enhances the reactivity of Li₂C₂O₄, lowering its decomposition potential from 4.8 to 4.24 V. Even with only a 5 wt.% addition, the decomposition potential drops below 4.28 V at 30°C. In addition, the products generated during the decomposition of lithium oxalate help optimize the cathode and anode solid electrolyte interphase. As a result, the specific capacities of graphite (Gr) || LiFePO₄ (LFP) and silicon/carbon (Si/C) || LFP full cells with the composite lithium replenisher increase by 13.13% and 12.05%, respectively. Additionally, the capacity retention of Si/C || LFP full cells at 0.3 C after 100 cycles improves from 76.83% to 90.46%.