Rearrangement on Surface Structures by Boride to Enhanced Cycle Stability for LiNi0.80Co0.15Al0.05O2 Cathode in Lithium Ion Batteries

The side reaction between the active material and liquid-electrolyte cause structural damage and particle pulverization is one of the important factors leading to the capacity decay of LiNi0.80Co0.15Al0.05O2 (NCA) materials in Li ion batteries (LIBs). Surface modification is an effective strategy for NCA cathodes, which could alleviate the degradation associated with surface processes. Herein, a surface structure rearrangement of NCA cathode secondary particles was reported by in-situ forming a solid electrolyte LiBO2. The LiBO2 is beneficial for alleviating the stress during charge/discharge process, thereby slowing down the rate of cracks formation in the secondary particles, which facilitates the Li+ de-intercalation as well as prevents penetration of the liquid-electrolyte into the interior of the particles. As a result, the surface structure rearrangement NCA (RS-NCA) delivers a high discharge capacity of 202.5 mAh g(-1) at 0.1 C, and exhibits excellent cycle stability with discharge capacity retaining 148 mAh g(-1) after 200 cycles at 2 C. This surface structure rearrangement approach provides a new viewpoint in designing high-performance high-voltage LIBs. (C) 2019 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.