Improved Rate Capability and Thermal Stability of LiNi0.5Co0.2Mn0.3O2 Cathode Materials via Nanoscale SiP2O7 Coating

Abstract

In order to overcome the inherent problems of LiNiO2, many method, such as coating and doping have been investigated. However, none of previous studies have not been reported to solve both rate capability at higher rates and thermal stability of the Ni-based cathode materials simultaneously. Here, we report the LiδPyOz–coated LiNi0.5Co0.2Mn0.3O2 cathode materials doped with P and Si ions which possesses both higher rates and thermal stability. It was prepared by direction reaction of LiOH and SiP2O7-coated Ni0.5Co0.2Mn0.3(OH)2 precursors. The coated cathodes exhibited quite impressive results; rate capability was improved by almost 100% at a 7C rate compared to pristine LiNi0.5Co0.2Mn0.3O2. Furthermore, the amount of heat generation at 4.5V charge cut-off as a result of the evolution of oxygen was reduced by 79%, compared to pristine LiNi0.5Co0.2Mn0.3O2 sample. Overall, this coating method is also applicable to other bulk cathodes, such as LiMn2O4 and LiCoO2 which need to improve electrochemical properties both at room and elevated temperatures.