Solid-state batteries use solid electrodes and a solid electrolyte, instead of the liquid or polymer gel electrolytes found in lithium-ion or lithium polymer batteries. The solid electrolyte is a key component of solid-state batteries, and materials proposed for use as solid electrolytes include ceramics (e.g., oxides, sulfides, phosphates), and solid polymers. The solid electrolyte plays a role of a separator as well, keeping the cathode and anode apart.

Solid-state batteries have several advantages over conventional lithium-ion batteries, such as higher energy density, longer lifespan, faster charging, and smaller size. They are also potentially safer, with higher energy densities, but at a much higher cost. However, challenges to widespread adoption include energy and power density, durability, material costs, sensitivity, and stability.

In summary, solid-state batteries are made of solid electrodes and a solid electrolyte, which can be made of ceramics or solid polymers. They offer several advantages over conventional lithium-ion batteries, but there are still challenges to overcome before they can be widely adopted.