镍酸锂（Li₂NiO₂）作为一种正极补锂剂，用于补偿锂离子损失，以提高锂离子电池的循环寿命。然而，Li₂NiO₂补锂剂存在成本高、脱锂动力学较差的问题。本文研究了基于高温固相法合成的低成本铜（Cu）取代型Li₂Ni_1-xCu_xO₂（x = 0, 0.2, 0.3, 0.5, 0.7）补锂剂对石墨/磷酸铁锂电池结构、形貌和电化学性能的影响。晶体结构精修结果表明，Cu取代策略有利于消除NiO_x杂质相，弱化Li-O键。理论计算结果显示Cu取代可提高补锂剂电子电导率。同时，电化学分析证实Cu取代有利于降低脱锂电位，提高脱锂容量。其中，最优比例的Li₂Ni_0.7Cu_0.3O₂具有437 mAh·g^-1的高脱锂容量，较Li₂NiO₂提升约8%。此外，设计了容量为3000 mAh的石墨/磷酸铁锂软包电池，采用2 wt% Li₂Ni_0.7Cu_0.3O₂补锂剂，其1000次循环的可逆容量、能量密度和循环寿命显著提高；其首圈放电容量提升6.2 mAh·g^-1，0.5 P循环1000圈容量保持率提升约5%。对循环后的电池进行拆解分析后发现Li₂Ni_0.7Cu_0.3O₂添加剂可以减少固体电解质界面（SEI）的分解、改善脱嵌锂的均一性，从而提高石墨负极与电解液之间的界面稳定性，抑制析锂。综上，与Li₂NiO₂相比，Li₂Ni_0.7Cu_0.3O₂具有成本低、脱锂电压低和预锂化容量高的优点，是极具前景的下一代锂离子电池正极补锂剂材料。

Lithium nickel oxide (Li₂NiO₂), as a sacrificial cathode prelithiation additive, has been used to compensate for the lithium loss for improving the lifespan of lithium-ion batteries (LIBs). However, high-cost Li₂NiO₂ suffers from inferior delithiation kinetics during the first cycle. Herein, we investigated the effects of the cost-effective copper substituted Li₂Ni_1-xCu_xO₂ (x = 0, 0.2, 0.3, 0.5, 0.7) synthesized by a high-temperature solid-phase method on the structure, morphology, electrochemical performance of graphite‖LiFePO₄ battery. The X-ray diffraction (XRD) refinement result demonstrated that Cu substitution strategy could be favorable for eliminating the NiO_x impurity phase and weakening Li-O bond. Analysis on density of states (DOS) indicates that Cu substitution is good for enhancing the electronic conductivity, as well as reducing the delithiation voltage polarization confirmed by electrochemical characterizations. Therefore, the optimal Li₂Ni_0.7Cu_0.3O₂ delivered a high delithiation capacity of 437 mAh·g^-1, around 8% above that of the pristine Li₂NiO₂. Furthermore, a graphite‖LiFePO₄ pouch cell with a nominal capacity of 3000 mAh demonstrated a notably improved reversible capacity, energy density and cycle life through introducing 2 wt% Li₂Ni_0.7Cu_0.3O₂ additive, delivering a 6.2 mAh·g^-1 higher initial discharge capacity and achieving around 5% improvement in capacity retentnion at 0.5P over 1000 cycles. Additionally, the post-mortem analyses testified that the Li₂Ni_0.7Cu_0.3O₂ additive could suppress solid electrolyte interphase (SEI) decomposition and homogenize the Li distribution, which benefits to stabilizing interface between graphite and electrolyte, and alleviating dendritic Li plating. In conclusion, the Li₂Ni_0.7Cu_0.3O₂ additive may offer advantages such as lower cost, lower delithiation voltage and higher prelithiation capacity compared with Li₂NiO₂, making it a promising candidate of cathode prelithiation additive for next-generation LIBs.