Promoting Low‐Voltage Li ₂ C ₂ O ₄ Prelithiation via CoSe ₂ /NC Catalyst in Lithium‐Ion Batteries

Self‐sacrificial lithium oxalate (Li 2 C 2 O 4 ) 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 (CoSe 2 /NC). Incorporating 10 wt.% CoSe 2 /NC significantly enhances the reactivity of Li 2 C 2 O 4 , 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) || LiFePO 4 (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%.