Interfacial pre-activation of lithium oxalate via d-p hybridization in intermetallic NiBi₃ for cathode prelithiation

Lithium oxalate (Li₂C₂O₄) is regarded as a promising prelithiation agent due to its high specific capacity and cost-effectiveness. However, its intrinsically poor electronic conductivity and sluggish reaction kinetics result in a high lithium liberation potential (typically above 4.5 V), which challenges the stability of electrolytes and electrode materials, and deteriorates overall battery performance. In this work, the intermetallic NiBi₃ catalyst with metallic conductivity and strong interfacial interaction is introduced to promote the low-potential decomposition of Li₂C₂O₄. Benefiting from the synergistic electronic effect between Ni and Bi, the incorporation of Bi effectively modulates the electronic structure of Ni sites viad-p orbital hybridization, thereby enhancing the adsorption and activation of Li₂C₂O₄, weakening the Li₂C₂O₄ framework and facilitating its decomposition. When coupled with ultrahigh-Ni NCM96 cathodes, the NiBi₃-Li₂C₂O₄ prelithiation system provides higher charge capacity (273.3 mAh g^-1) and improved reaction kinetics compared to the pristine counterpart. Furthermore, full-cell configurations based on SiO_x anodes exhibit enhanced lithium compensation capability, maintaining a capacity retention of 52.9% after 150 cycles at 0.5C. These results demonstrate that intermetallic NiBi₃ is an efficient catalyst for activating Li₂C₂O₄ and provides a viable strategy for developing high-performance cathode prelithiation systems.