Mechanochemically synthesized amorphous superionic systems for solid-state batteries

Abstract

Solid-state electrochemical cells of the type Ag|a-SIC|I2 are fabricated using mechanochemically synthesized amorphous superionic conductors (a-SICs), AgI–Ag2O–MxOy (MxOy=B2O3, V2O5, CrO3) as electrolytes. The typical value of the conductivity of these systems is in the range 10−2 to 10−3 Ω−1 cm−1 and the transport number of Ag+ ions is near unity.

The mechanochemically synthesized powders were directly used as electrolytes. Constant load characteristics for various loads confirm the thermodynamic stability and competency of these materials as electrolytes. The cells are discharged at low (J∼65 μA/cm2) and high (J∼105 μA/cm2) drain currents and nominal cell capacities and energy densities were obtained. Nominal cell capacities for all these cells for low current discharge rates were found within 6–7% of the theoretical capacity of Ag/I2 cell. Whereas, for high discharge rates, ∼3–4% of the theoretical value. A current density of ∼500 μA/cm2 can be drawn safely without any serious polarization.