Boosting the Electrochemical Performance of High-Voltage LiCoO2 Cathode by a Dual-Coating Strategy

In this study, by using the solid and liquid coating method, LiCoO2 wasdual-coated by lithium titanate (Li4Ti5O12) and polypyrrole (PPy). The coating layers not only protect the surface of LiCoO2 at high voltage but also increase its ion conductivity and electronic conductivity. According to the result of the electrochemistry test, when the mass ratio of active material, conductive agent, and binder was 80:10:10, the capacity retention of the modified material after 300 cycles at 0.5C (1C= 180 mA.g(-1)) was 76.9%. Its reversible capacity was 150 mAh.g(-1) at 5C current density. Due to the improvement of electric conductive of dual-coated LiCoO2, when this mass ratio was 90:3:7, the capacity retention after 200 cycles at 0.5C was 82.8%. Its reversible capacity was 130 mAh.g(-1) at 5C current density. As shown in X-ray photoelectron spectra, the coating layers can keep stability during cycling and prevent side reactions on the surface.