Development of polymer-based artificial solid electrolyte interphase for safer Li-metal batteries: Challenges, strategies and prospects

As the demand for electric vehicles and other high-energy-density energy storage grows, traditional graphite anodes are not sufficient to meet future needs. Lithium metal batteries have attracted increasing attention due to their high specific capacity and low redox potential. However, safety and durability issues due to the growth of lithium dendrites, infinite volume change, high reactivity, and continuous loss of lithium during cycling have seriously hindered their commercialization in lithium metal batteries. Forming a stable solid electrolyte interface (SEI) is an effective way to overcome these shortcomings. Among these SEI formers, organic polymers are the ideal choice for surface passivation of lithium metal due to their chemical/electrochemical stability and mechanical strength. Polymer-based SEI effectively suppresses dendrite growth and volume changes, thus forming a uniform lithium layer during lithium deposition. In the past decades, research has focused on the polymer modification of lithium metal anodes. This paper systematically discusses the design strategy, research status, and main scientific issues of polymer materials for protecting lithium metal anodes from the perspective of SEI film attribution. Finally, we highlight the design principles of high-performance polymer-based SEIs and prospect their future development.