As the world transitions to renewable electricity and electrifies more of its energy demand, power generation and use are being transformed, with batteries taking center stage. They are already indispensable in portable electronics and have become the key enabling technology for electric vehicles, where very high energy density is critical. However, conventional lithium-ion batteries are constrained by important drawbacks: the flammability of liquid electrolytes, the limited energy density, and the reliance on scarce raw materials. Solid-state batteries have emerged as suitable alternative for next-generation devices, aiming to overcome these challenges by replacing the liquid electrolyte with a solid-state one, either inorganic, polymeric or composite/hybrid.