Understanding the Mechanism of MgF2 Modification on the Electrochemical Performance of Lithium-Rich Layered Oxides

In this paper, lithium rich manganese based cathode materials were successfully modified by MgF2 and the corresponding function mechanism was studied in detail. The MgF2 coating inhibits the activation of Li2MnO3 and induces the formation of spinel phase. The MgF2-3 shows an enhanced initial discharge capacity of 282.6 m Ah g(-1) and an improved coulombic efficiency of 87.15% compared to 267.8 m Ah g(-1) and 74.41% for the pristine sample, respectively. The MgF2 modification can effectively inhibit HF corrosion, reduce side effects and improve cycle performance. The MgF2-3 shows a discharge capacity of 205.6 m Ah g(-1) with a retention of 80.03% and a voltage of 442.2 mV after 200 cycles, while for the pristine is only 147.9 m Ah g(-1), 66.71%, 672.3 mV, respectively.