Challenges ahead in the development of solid-state batteries

Solid-state batteries offer the potential for high energy density and improved safety when compared to conventional Li-ion batteries, brought by replacement of liquid electrolytes with solid lithium-ion conductors. While concepts using polymer electrolytes have entered niche markets, transitioning to industrial-scale manufacturing faces major hurdles. Critical challenges include electrolyte selection (with different families of compounds exhibiting different advantages and drawbacks), compatibility with electrode active materials and interface engineering, processing aspects and long-term performance. This perspective outlines the current state-of-the-art and critical aspects across the main classes of solid electrolytes and a development timeline to raise solid state batteries' readiness and industrial uptake, from short-term interface stability improvements to long-term mass-market adoption. • Solid-state batteries promise higher energy density and improved safety. • Key advances in materials and design suggest viable paths to scalable solutions. • Transition from lab to industry requires addressing interconnected challenges.