A Novel Coating Layer of Mesoporous Silica on LiNi0.8Co0.1Mn0.1O2 (NCM811) Cathode Material for Advanced Lithium-Ion Batteries

Abstract

NCM811 cathode material has many commercial features such as reasonable price, environmental friendliness and high specific capacity, yet it suffers from capacity attenuation during cycling. Silica (SiO2) coating strategy is a valid approach to enhance the capacity retention of NCM811. However, the insulating nature of coating layer reduces the electrochemical performance. Herein, a novel route is developed to alleviate this issue by using a mesoporous layer instead of bulk layer. The mesoporous layer is prepared by condensing a mixture of fine templates (Cetyltrimethylammonium bromide, CTAB) and tetraethyl orthosilicate (TEOS) on NCM811 particles and calcining them to remove templates. The structure, morphology, surface chemical state and electrochemical performance of samples are widely investigated. Results indicate that the mesoporous layer (SiO2-20 wt.% of CTAB) exhibits discharge capacities of 210 and 138 mAh g(-1) at 0.1 C and 5C over 2.7-4.3 V, while those of bulk SiO2 coated sample are only 189 and 98 mAh g(-1), respectively. This mesoporous layer offers a capacity maintenance of 87.3 % after 100 cycles, compared to only 69.3 % for pure NCM811 at 1 C. The mesoporous layer not only improves the discharge capacity of NCM811 but also reduces its capacity fading.