Realizing long-term cycling stability and superior rate performance of 4.5 V–LiCoO2 by aluminum doped zinc oxide coating achieved by a simple wet-mixing method

Abstract

The thermodynamic instability of the layered structure and severe side reactions with liquid carbonate electrolytes have been considered as the key obstacles for the practical application of LiCoO2 (LCO) at voltages of above 4.5 V (versus Li/Li+). Here, we have developed a facile wet-mixing synthetic method which can realize thin and uniform surface coating of aluminum doped zinc oxide (AZO) on LCO particles. The half-cells employing the AZO modified LCO display excellent 4.5 V cycle performance with the discharge capacity retention of 80% after 650 cycles and superior rate capability of 8C capacity of 100 mAh g−1. Combined with surface structure characterizations and bond valence calculations, it is revealed that the stabilized surface and superior kinetic properties contribute to the performance enhancement of AZO modified LCO at 4.5 V. This work demonstrates AZO a suitable coating material for surface protection of cathode materials for high-voltage applications. The preparation method developed in this work is also suitable for mass production and applicable to fabrication of other types of battery materials.