An orbital-coupling-driven bifunctional prelithiation additive for enhanced practical Li-ion full cells

Prelithiation has been widely recognized as an effective strategy to compensate for active lithium loss and enhance the energy density of lithium-ion batteries. This work develops a highly efficient Ti-doped cathode prelithiation additive, 2% Ti-doped Li₂NiO₂ (Ti 2-LNO). As demonstrated, such a prelithiation material delivers a lasting ion-electron bifunctional bridge: it efficiently replenishes the irreversible lithium loss of LiFePO₄ during the initial cycle and transforms into Ti 2-LiNiO₂ thereafter. Notably, the orbital coupling at the interface between Ti 2-LiNiO₂ and LFP forms an efficient electron transport channel; meanwhile, the incorporation of Ti 2-LiNiO₂ contributes to the formation of a stable, LiF-rich and low-impedance cathode/electrolyte interphase (CEI), thereby optimizing ion-electron synergistic transport, accelerating interfacial charge transfer, and alleviating both electrochemical and concentration polarization at high rates. Compared with the conventional Li‖LiFePO₄ half-cell, enabled by the synergistic effect of efficient lithium compensation and capturing the sluggish electrons in LFP to achieve rapid electron transfer, the cell with a 10 wt% Ti 2-LNO additive exhibits significantly improved rate capability, delivering a high reversible capacity of 87.2 mA h g^-1 at 5C after 1000 cycles. Furthermore, a practical graphite‖LiFePO₄ with 10 wt% Ti 2-LNO full cell (N/P = 1.2) exhibits enhanced cycle stability, retaining 98.60% of its initial capacity after 200 cycles at 0.5C. This work presents a design concept for high-performance cathode prelithiation additives that synergistically couples efficient Li⁺ compensation with accelerated ion-electron transport kinetics, enabling high-power and long-life Li-ion full cells.