Upcycling spent polycrystal LiNi1/3Co1/3Mn1/3O2 cathodes into single-crystal Ni-rich materials via the “four-in-one” upcycling regeneration strategy

Abstract

Faced with the upcoming wave of retired lithium-ion batteries, effective recycling strategies are essential to address resource shortages, environmental pollution, and the demand for high-energy-density cathode materials. This paper proposes a simple, environmentally friendly, and scalable “four-in-one” upcycling repair strategy, which realizes lithium supplementation, component upgrading, crystal structure regulation, and Mo gradient doping through mechanochemical synergistic gradient sintering. The waste polycrystalline LiNi_1/3Co_1/3Mn_1/3O₂ was successfully transformed into the sub-micron single crystal LiNi_0.8Co_0.1Mn_0.1O₂. Compared with traditional direct recycling, this approach increases economic benefit by 52%, and the material regenerated in the upper cycle has superior electrochemical performance and mechanochemical stability compared to commercial LiNi_0.8Co_0.1Mn_0.1O₂. It has a high specific discharge capacity of 185.7 mAh g⁻¹ at 0.1C and still maintains a capacity retention rate of 84.77% after 100 cycles at 1C, proving the superior rate performance of 125.1 mAh g⁻¹ at a high rate of 5C, while maintaining the integrity of the body structure and inhibiting the degradation of the particle surface. This research is expected to establish a new technological paradigm that is environmentally friendly, value-added, and scalable, providing meaningful guidance for the upgrading and recycling of waste low-nickel polycrystalline materials into high-performance nickel-rich single-crystal cathode materials.