为了缓解锂离子电池工业原材料短缺和废电池的环境污染问题，实现废锂电池材料的闭环循环利用变得越来越重要。本文以废三元正极材料和废锰酸锂正极材料为研究对象，针对循环利用流程长、能耗高、循环利用产品性能差等共性问题，进行了以高电化学性能为导向的直接修复和升级循环利用研究，实现了废正极材料的短流程、低能耗的直接修复和能量密度升级。主要创新成果如下： 探索了固态煅烧法结合机械活化直接修复废正极材料的可行性。固态煅烧法修复后的材料具有电化学活性但库伦效率仍然不稳定。固态煅烧法修复后的NCM523在0.1C条件下表现出132.2 mAh?g-1的放电比容量，在1 C条件下循环200次后放电容量保持率为91.02%。但由于固态煅烧法修复过程中补充的锂元素未能靶向进入缺陷位点，修复后的材料库伦效率波动较大。 提出了乙醇-硝酸锂溶剂热直接修复废三元正极材料的新方法。溶剂热法可以实现废正极材料组成和结构的修复。修复后的材料R-NCM523具有稳定的库伦效率和高电化学性能。在0.1C条件下放电容量达到142.7 mAh·g-1，在1C条件下循环400次后，容量保持率达到90.23%，库伦效率保持近100%。理论计算和原位表征表明，溶剂热法修复后的材料具有稳定的结构和低锂离子扩散能垒 (0.078 eV)。 提出了高构型熵改善再生高镍正极材料结构稳定性的新思路。研究表明，通过共沉淀法再生的高熵高镍正极材料HE-NCM811在不同充电状态下都具有良好的层状结构和稳定的电化学性能。HE-NCM811在0.1C下具有189.1 mAh?g-1放电比容量。在0.1C激活两次后1C循环58次，容量保持率达到99.69%，库伦效率接近100%。 制备了高熵无钴高镍正极材料，并利用非晶相SiO2作为载体负载S8作为改性剂 (S@SiO2)进行了表面改性，实现了无钴高镍正极材料表面和体相结构稳定性的改善，最后，将该策略成功应用于再生高熵无钴高镍正极材料。高熵策略结合S@SiO2包覆使得再生高熵无钴高镍正极材料在0.1C下的放电比容量达到227.4 mAh·g-1。在1C下循环100次后容量保持率达到94.36%。机理研究表明，高熵策略结合S@SiO2包覆能有效稳定无钴高镍材料的结构，降低锂离子扩散能垒并抑制裂纹以及Ni、Mn和O缺陷的形成。

In order to alleviate the shortage of raw materials in the lithium-ion battery industry and the environmental pollution caused by spent batteries, it is becoming increasingly important to achieve closed-loop recycling of spent lithium-ion battery materials. This article takes spent ternary cathode materials and spent lithium manganese oxide cathode materials as research objects, and focuses on common problems such as long recycling process, high energy consumption, and poor performance of recycled products. An upgraded recycling research guided by high electrochemical performance is carried out, achieving direct repair and energy density upgrading of spent cathode materials with short process and low energy consumption. The main innovative achievements are as follows:Explored the feasibility of using solid-state sintering combined with mechanical activation to directly repair waste cathode materials. The material repaired by solid-state sintering has electrochemical activity, but the Coulombic efficiency is still unstable. The NCM523 repaired by solid-state sintering showed a discharge specific capacity of 132.2 mAh?g-1 at 0.1C. At 1C, the capacity retention rate of 91.02% can be obtained after 200 cycles. However, due to the lack of targeted entry of lithium elements into defect sites during the solid-state sintering repair process, the Coulombic efficiency of the repaired material fluctuates greatlyA new method of ethanol-lithium nitrate solvent thermal direct repair of spent ternary cathode materials has been proposed. The solvent thermal method can achieve the repair of the composition and structure of spent cathode materials. The repaired material R-NCM523 has stable Coulombic efficiency and high electrochemical performance. The R-NCM523 has 142.7 mAh·g-1 at 0.1C. After 400 cycles at 1C, the capacity retention rate reached 90.23% and the Coulombic efficiency remained nearly 100%. Theoretical calculations and in situ characterization indicate that the material repaired by solvent thermal method has a stable structure and low lithium-ion diffusion energy barrier (0.078 eV).A new approach has been proposed to improve the structural stability of regenerated high nickel cathode materials with high configuration entropy. Research has shown that the high entropy and high nickel cathode material HE-NCM811 regenerated by co precipitation method exhibits good layered structure and stable electrochemical performance under different charging states. HE-NCM811 has a discharge specific capacity of 189.1 mAh?g-1 at 0.1C. After activating twice at 0.1 C and cycling 58 times at 1C, the capacity retention of 99.69% can be obtained, and the Coulombic efficiency approached 100%.A high entropy cobalt free high nickel cathode material was prepared, and amorphous SiO2 was used as a carrier to load S8 as a modifier (S@SiO2) for surface modification, achieving improved surface and bulk structural stability of cobalt free high nickel cathode materials. Finally, this strategy was successfully applied to the regeneration of high entropy cobalt free high nickel cathode materials. The high entropy strategy combined with S@SiO2 coating resulted in a discharge specific capacity of 227.4 mAh·g-1 for the regenerated high entropy cobalt free high nickel cathode material at 0.1C. The capacity retention rate is 94.36% at 1C after 400 cycles. Mechanism studies have shown that the high entropy strategy combined with S@SiO2 coating can effectively stabilize the structure of cobalt free high nickel materials, reduce the lithium-ion diffusion energy barrier, and suppress the formation of cracks and Ni, Mn, and O defects.