Regenerated Ni-Doped LiCoO₂ from Spent Lithium-Ion Batteries as a Stable Cathode at 4.5 V

In the context of the increasing number of spent lithium-ion batteries, it is urgent to explore cathode regeneration and upcycling solutions to reduce environmental pollution, promote resource reuse, and meet the demand for high-energy cathode materials. Here, a closed-loop recycling method is introduced, which not only reclaims cobalt and lithium elements from spent lithium-ion batteries but also converts them into high-voltage LiCoO 2 (LCO) materials. This approach involved pretreatment, chlorination roasting, water leaching, and ion doping to regenerate nickel-doped LCO (Ni–RLCO) materials. The doping of nickel effectively enhances the electrochemical stability of the LCO cathode at 4.5 V. The Ni–RLCO cathode exhibited a high discharge specific capacity of 185.28 mAh/g at a rate of 0.5 C with a capacity retention of 86.3% after 50 cycles and excellent rate capacity of 156.21 mAh/g at 2 C. This work offers a approach in significance for upcycling spent LCO into high-energy-density batteries with long-term cycling stability under high voltage.