Recovery of Degraded Ni-Rich NMC811 Particles for Lithium-Ion Batteries

Nickel-rich cathode materials attract a lot of attention due to their high energy density. However, their sensitivity to air and moisture hinders their practical applications. Exposing Ni-rich NMC in the air will produce by-products that are not conducive to lithium-ion transmission. Water washing can be used to remove by-products on the surface, but it can also introduce new problems, such as the generation of NiO on the particle surface, which will reduce the electrochemical performance of the material. In this study, Al2O3 atomic layer deposition (ALD) was applied on degraded NMC811 particles to recover the electrochemical performance of the degraded NMC811 particles, which had been exposed to moisture. XPS and XRD analysis verified that the Al2O3 ALD coating removed the contaminant components on the particle surface, such as LiOH and Li2CO3, as well as reactivation of inactive Ni due to reaction with moisture. Furthermore, the coating film can also inhibit side reactions during the charge and discharge process and enhance the cycling stability.