State-of-the-art of solid-state electrolytes on the road map of solid-state lithium metal batteries for e-mobility

Solid-state lithium metal batteries (SSLMB) are regarded as the most promising among lithium batteries to serve the automotive industry with their lighter weight, safety, durability, higher energy density, and faster rate of charge enabling e-mobility. Regarding battery components, novelty in electrode materials is through improving materials from conventional lithium batteries; however, the fundamental differentiator for SSLMB is the solid-state electrolytes (SSEs). SSE development is reviewed here with three main subcategories taking the stage, viz. ceramic electrolytes, polymer electrolytes, and soft sulfur-based electrolytes, and hybrid solutions derived from the combinations above. Lithium dendritic issues remain as the major bottleneck in the development of lithium metal batteries (LMBs) although SSEs are being utilized in the cells. Based on the existing investigations, this paper presents a comprehensive review on the factors that may cause the formation and propagation of the lithium dendrites in SSEs, the lithium dendrites growth mechanisms, and approaches to mitigate the issues. Herein, the key players are also being reviewed along with their recent progresses in researching and developing a viable technology of solid-state battery (SSB) toward mass-production and commercialization into the market. Perspectives and insights for further exploration in this research area are also presented within this Review.