Polymer Electrolytes for High Energy Density Ternary Cathode Material-Based Lithium Batteries

Layered transition metal oxides such as LiNixMnyCo1−x−yO2 and LiNixCoyAl1−x−yO2 (NCA) (referred to as ternary cathode material, TCM) are widely recognized to be promising candidates for lithium batteries (LBs) due to superior reversible capacities, high operating voltages and low production costs. However, despite recent progress toward practical application, commercial TCM-based lithium ion batteries (LIBs) suffer from severe issues such as the use of flammable and hazardous electrolytes, with one high profile example being the ignition of NCA-based LIBs used in Tesla Model S vehicles after accidents, which jeopardizes the future development of TCM-based LBs. Here, the need for TCM and flammable liquid electrolytes in TCM-based LBs is a major obstacle that needs to be overcome, in which conflicting requirements for energy density and safety in practical application need to be resolved. To address this, polymer electrolytes have been demonstrated to be a promising solution and thus far, many polymer electrolytes have been developed for high-performance TCM-based LBs. However, comprehensive performances, especially long-term cycling capabilities, are still insufficient to meet market demands for electric vehicles, and moreover, comprehensive reviews into polymer electrolytes for TCM-based LBs are rare. Therefore, this review will comprehensively summarize the ideal requirements, intrinsic advantages and research progress of polymer electrolytes for TCM-based LBs. In addition, perspectives and challenges of polymer electrolytes for advanced TCM-based LBs are provided to guide the development of TCM-based power batteries.