Ag–Sn dual-modified LiNi0.8Co0.1Mn0.1O2 as cathode for lithium storage

Abstract

The structural decomposition and inevitable capacity decay during cycling hinder the further commercial application of LiNi0.8Co0.1Mn0.1O2 (NCM811). In this paper, Ag–Sn dual-modification is first adopted to promote the structural stability and the electrochemical property of NCM811. First, there form Li2SnO3 phase coated NCM811, and most Li2SnO3 phases exist on the outer surface of NCM811 sphere during the first-step Sn modification. Then, a slightly uneven Ag coating layer generate on the surface of Li2SnO3 coated NCM811 and more Li2SnO3 phase diffuses into the NCM811 sphere after the second-step of Ag-modification. Meanwhile, the mixing degree of Li+/Ni2+ and residual lithium on the surface of NCM811 are reduced by the Ag–Sn dual-modification. After proving, the Ag–Sn dual-modification is beneficial for improving the electronic conductivity, accelerating the diffusion of Li+ and suppressing the decomposition of electrolyte, thereby enhancing the electrochemical performance. Consequently, the Ag–Sn dual-modified NCM811 reveals a splendid discharge capacity of 193.3 mA h g−1 at 1 C rate, and with retention of 89.4% after 90 cycles between 2.8 and 4.3 V, exhibiting well-enhanced cycling stability with the comparison of pure NCM811 (183.7 mAh g−1, 87.9%). This efficient dual-modification strategy provides a reference scheme for the commercial application of NCM811.