Towards superior cyclability of LiNi0.8Co0.15Al0.05O2 cathode material for lithium ion batteries via yttrium modification

Abstract

The surface instability and the structure degradation in Ni-rich cathode materials have been considered to the primary issues causing the severe capacity fading. In this study, a viable and effective approach to fabricate the yttrium modified LiNi0.8Co0.15Al0.05O2 (NCA) cathode materials with higher electrochemical performance by solid-state method is reported. The yttrium modified materials exhibit a notably enhanced electrochemical performance, which delivers a discharge capacity of 169.8 mAh g−1 over 3.0–4.3 V at 1 C corresponding capacity retention of 95.3% after 200 cycles. Besides, the capacity of the modified materials at higher rate (8 C) increase to 156.9 mAh g−1. With a careful and in-depth investigation, we found that the improved electrochemical performance can be attributed to the Y doping, which provides a powerful Y-O bond in the transition metal layers and effectively improves the structure stability. Additionally, the Ni2+ existing in the Li slabs to some extent exert a positive effect on suppressing the further cation migration and stabilizing the lithium slabs. Based on our work, we believe the modification strategy has the potential application in the cathode materials.