Liquid electrolyte: The nexus of practical lithium metal batteries

The specific energy of commercial lithium (Li)-ion batteries is reaching the theoretical limit. Future consumer electronics and electric vehicle markets call for the development of high energy density Li metal batteries, which have been plagued by poor cyclability. Electrolyte engineering can afford a promising approach to address the issues associated with Li metal batteries and has recently resulted in much improved cycle life under practical conditions. However, gaps still exist between the performance of current Li metal batteries and those required for commercial applications. Further improvements will require systematic analysis of existing electrolyte design methodologies. In this review, we first summarize recent approaches of advanced electrolytes for Li metal batteries paired with high-voltage cathodes. We then extract common features among these advanced electrolytes and finally discuss the future rational design directions and strategies.