Modification of lithium-rich manganese-based cathode materials by continuous coating formed by surface treatment of sodium dodecyl sulfate to improve electrochemical performance

With the development of new energy devices, the demand for electrode materials with high energy density (> 400 Wh/kg) is increasing day by day. Lithium-rich manganese-based cathode materials (LRMC) which meet the requirements are considered one of the most promising materials for the next generation of lithium-ion batteries, and have attracted wide attention. However, LRMC still faces some key scientific problems that need to be addressed, such as interface side reactions, poor rate performance, rapid voltage and capacity attenuation, and low first coulomb efficiency. The continuous Na2SO4-coated lithium-rich manganese-based cathode material Li1.2Ni0.13Co0.13Mn0.54O2 (S-LRMC) was synthesized using sodium dodecyl sulfate (SDS). SDS is composed of hydrophobic aliphatic hydrocarbon groups and hydrophilic sulfate carboxyl groups, so it can form a micelle-like coating on the surface of LRMC materials in aqueous solution. The uniform Na2SO4 coating formed after calcination can effectively inhibit the side reaction between electrode material and electrolyte and reduce the dissolution of transition metal ions. As a result, capacity retention, rate performance and discharge specific capacity are improved. After 100 cycles at 1 C, the specific discharge capacity of 4% S-LRMC is 187.8 mAh g(-1) (LRMC is (1)38.3 mAh g(-1)), and the capacity retention is 87.35%. Even at a high current density of 5 C, the material still has a specific discharge capacity of 143.6 mAh g(-1), which proves that the electrochemical performance of the material is excellent. Therefore, this study provides a new solution for improving the structural stability and electrochemical performance of lithium ion batteries.