Electronic-State Engineering of Transition Metals Regulates Decomposition Kinetics of Li₂C₂O₄ for Cathode...

Lithium oxalate (Li₂C₂O₄) is a promising cathode prelithiation reagent but suffers from a high activation voltage (>4.6 V). Herein, we establish a component-electronic structure-activity correlation by constructing a series of transition metal-loaded N,S co-doped carbon catalysts (M/NSC, M = Fe, Co, Ni, Ru, Rh, Ir). Distinct catalytic behaviors originate from metal-dependent electronic structures and their interactions with N/S co-doped carbon. Interestingly, the Fe-group metals exhibit stronger electronic coupling and higher redox flexibility than 4d/5d noble metals, resulting in more effective activation of Li₂C₂O₄. The Co/NSC achieves the lowest decomposition voltage (4.17 V), attributed to uniform Co dispersion, optimized Co-N/S coordination, and defect-induced charge-transfer enhancement. The Co/NSC-Li₂C₂O₄ composite ensures nearly complete decomposition and delivers superior prelithiation performance. When applied to commercial LFP and NCM9055 cathodes, the Gr|| LiFePO₄ system shows a 22% capacity increase, meanwhile the Gr/SiC||NCM9055 cell achieves an initial coulombic efficiency (ICE) enhancement from 77% to 85.6%. This work highlights electronic-structure engineering as an effective strategy for enabling practical lithium compensation in high-energy lithium-ion batteries.