Vacuum-Assisted Impurities Removing Triggered Electronic Configuration Reconstruction of Spent NCM for Ultrafast Lithium Storage.

Attracted by ∼100% element recovery rate, direct regeneration of spent NCM (SNCM) has been deemed as next-generation recycling strategy. However, practical SNCM is always mixed with inactive impurities (PVDF and conductive carbon), which introduces undesirable heteroatoms and serious secondary damage, resulting in inferior performance. Herein, we propose a vacuum-assisted impurities removing strategy to upcycle SNCM with tailored spin states of vital elements. Accompanied with triggered electronic configuration reconstruction of Ni/Mn species, the as-formed strengthened Ni2+-O2--Mn4+ superexchange brings about built-in electric field and robust lattice structures with minor distortions. Meanwhile, oxygen vacancy formation energy increases about 1.1 eV, and electron localization effect is greatly alleviated, leading to durable stability and rapid reaction kinetics. The as-optimized samples exhibit high capacity retention of 93.5% at 1.0 C after cycling. Even at ultra-high rates of 8.0 C and 10.0 C, they could retain 116.7 and 110.4 mAh g-1. Assisted by kinetics analysis and in/ex situ measurements, enhanced Li-diffusion and eliminated internal strains are revealed. Moreover, this strategy could be applied to upcycle spent NCM613, Ni65 and NCM811. This work is expected to illustrate the advantages of electronic configuration reconstruction and superexchange interaction creation during regeneration, meanwhile offer full-process regeneration strategies toward upcycled NCM.