Superionic conduction electrolyte through in situ structural transformation in electrochemical cell

High ionic conductivity at reduced temperatures may allow electrochemical cell applications to be efficiently scaled up. Herein, we introduce an approach that exploits electrode-electrode synergy and in situ structural transformation to increase the ionic conductivity of an electrolyte within the electrochemical cell. This transformation is based on the formation of a Li₂TiO₃-Li₂CO₃ heterostructure electrolyte via the combination of a TiO₂ semiconductor precursor, polystyrene spheres as the soft skeleton, and the lithium-based electrode LiNi_0.8Co_0.15Al_0.05O₂. The unique surface and interface of the heterostructure electrolyte enable the formation of long-range ion transport channels that lower electrode impedance, resulting in a superior ionic conductivity of 0.23 S cm⁻¹ at 550 °C and a high-power density of 1239 mW cm⁻². Our general method to form superionic electrolytes shows potential in fuel cell technologies.