Design of thin solid-state electrolyte films for safe and energy-dense batteries

The demand for high-performance electric vehicle (EV) batteries, specifically all-solid-state lithium batteries (ASSLBs), has been on the rise. Although notable advancements have taken place, there's still a noticeable gap to achieve the targets set by the U.S. Department of Energy (DOE). Designing and fabricating thin solid-state electrolytes (SSEs) are crucial to achieve high energy densities and boost the practical application of ASSLBs. However, the thickness reduction in SSEs introduces challenges such as a heightened risk of dendrite growth. This review focuses on reducing the thickness of SSEs to boost the energy density and overall efficiency of ASSLBs. Strategies such as optimizing manufacturing processes for thin SSE films and enhancing mechanical strength and ion conductivity at room temperature for thin SSE films are critically reviewed. The review highlights the cost-effective and scalable methods to produce thin SSEs, and discusses future opportunities in this burgeoning area, ranging from fundamental research to practical applications, to further accelerate the transition from conventional lithium-ion batteries to ASSLBs.