The recycling of spent lithium-ion batteries is an effective approach to alleviating environmental concerns and promoting resource conservation. LiFePO₄ batteries have been widely used in electric vehicles and energy storage stations. Currently, lithium loss, resulting in formation of Fe(III) phase, is mainly responsible for the capacity fade of LiFePO₄ cathode. Another factor is poor electrical conductivity that limits its rate capability. Here, we report the use of a multifunctional organic lithium salt (3,4-dihydroxybenzonitrile dilithium) to restore spent LiFePO₄ cathode by direct regeneration. The degraded LiFePO₄ particles are well coupled with the functional groups of the organic lithium salt, so that lithium fills vacancies and cyano groups create a reductive atmosphere to inhibit Fe(III) phase. At the same time, pyrolysis of the salt produces an amorphous conductive carbon layer that coats the LiFePO₄ particles, which improves Li-ion and electron transfer kinetics. The restored LiFePO₄ cathode shows good cycling stability and rate performance (a high capacity retention of 88% after 400 cycles at 5 C). This lithium salt can also be used to recover degraded transition metal oxide-based cathodes. A techno-economic analysis suggests that this strategy has higher environmental and economic benefits, compared with the traditional recycling methods.

废旧锂离子电池的回收利用是缓解环境问题和促进资源节约的有效途径。LiFePO ₄电池已广泛应用于电动汽车和储能站。目前，导致形成Fe(III)相的锂损失是造成LiFePO ₄正极容量衰减的主要原因。另一个因素是导电性差，这限制了它的倍率能力。在这里，我们报告了使用多功能有机锂盐（3,4-二羟基苯甲腈二锂）通过直接再生来恢复用过的 LiFePO _4阴极。降解的LiFePO ₄颗粒与有机锂盐的官能团很好地偶联，使锂填充空位和氰基形成还原气氛以抑制Fe(III)相。同时，盐的热解会产生覆盖 LiFePO ₄颗粒的无定形导电碳层，从而改善锂离子和电子转移动力学。恢复后的 LiFePO ₄正极表现出良好的循环稳定性和倍率性能（在 5 C 下循环 400 次后容量保持率高达 88%）。这种锂盐还可用于回收退化的过渡金属氧化物基阴极。技术经济分析表明，与传统的回收方法相比，该策略具有更高的环境和经济效益。