An Effective Electrolyte Strategy To Improve the High-Voltage Performance of LiCoO2 Cathode Materials

According to the theoretical calculations and combining the advantages of different solvents, an effective electrolyte capable of effectively improving the high-voltage performance of LiCoO2 (LCO) cathode materials has been designed. The electrolyte utilizes dimethyl sulfone, which can be preferentially oxidized and form a stable protective layer on the surface of the positive electrode material during the cycles. Compared with the conventional electrolyte, by use of our designed electrolyte, the capacity retention rate increases from the original 38.1% up to 87.1% after cycling for 300 times at 4.45 V, and the capacity retention rate is also effectively promoted from the previous 21.0% up to 74.9% after 300 cycles under a higher voltage of 4.55 V. The experimental results show that use of this electrolyte can effectively inhibit the dissolution of transition metal ions in LiCoO2 materials, thereby ensuring the structural stability of the cathode material and greatly improving the electrochemical performance. As can be seen from a series of tests, the effective electrolyte system we designed is very promising.