Emerging materials for next-generation energy storage: A roadmap to solid-state and beyond

The global shift toward renewable energy integration and the electrification of transportation is driving an urgent demand for advanced energy storage technologies that deliver higher energy density, improved safety, longer cycle life, and environmental sustainability. Among the most promising candidates, solid-state batteries (SSBs) offer a transformative leap beyond traditional lithium-ion systems by replacing flammable liquid electrolytes with solid-state ion conductors. This change enables the use of high-capacity lithium metal anodes, improves thermal stability, and enhances device safety. However, the realization of commercial SSBs is contingent on overcoming key material and engineering challenges. This review provides a comprehensive overview of emerging materials pivotal to the next generation of energy storage. We examine the landscape of solid electrolytes, including ceramic oxides (e.g., garnet-type, perovskites, NASICON), sulfide-based systems (e.g., Li₁₀GeP₂S₁₂, argyrodites), and polymer-based electrolytes, highlighting their ionic conductivity, electrochemical stability, processability, and limitations. In parallel, we explore innovations in high-capacity anode and cathode materials, such as silicon-based composites and high-voltage oxides, and strategies for interface engineering, including artificial interphases and in situ-forming layers, to mitigate interfacial resistance and enhance mechanical compatibility. Furthermore, we address composite and hybrid designs, fabrication strategies, and scalability considerations that are critical to industrial adoption. The review also extends beyond solid-state systems, covering frontier technologies such as lithium–sulfur, lithium–air, and multivalent-ion batteries, which promise even greater energy densities and sustainability. By mapping current advances and outlining a roadmap to commercialization, this article underscores the multidisciplinary innovations necessary to power the energy landscape of the future.