Recent progress of multilayer polymer electrolytes for lithium batteries

The significant market for electric vehicles and portable electronic devices is driving the development of high-energy-density solid-state lithium batteries. However, the solid electrolyte is still the main obstacle to the development of solid-state lithium batteries, mainly due to the lack of a single solid electrolyte that is compatible with both high-voltage cathodes and lithium metal anodes. These problems can potentially be solved with multilayer electrolytes. The property of each layer of the electrolyte can be tuned separately, which not only meets the different needs of the cathode and anode but also makes up for the shortcomings of each layer of the electrolyte, thereby achieving good mechanical properties and chemical and electrochemical stability. This review first presents a brief introduction to homogeneous single-layer electrolytes. The design principles of multilayer polymer electrolytes and the application of these principles using examples from recent work are then introduced. Finally, several suggestions as guides for future work are given.