EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Solid electrolytes are a key component in enabling new technological advances for rechargeable batteries by mitigating many of the challenges associated with the use of liquid organic electrolytes. One of the key properties of solid electrolytes is their ability to transport ions between anode and cathode. This ion migration is usually characterized by measuring the ionic conductivity by means of impedance spectroscopic measurements. However, the ionic conductivity is proportional to both the density and the mobility of mobile ions. Only the mobility represents the actual velocity of the mobile ions.

We show how measuring temperature-dependent current transients can be used to independently quantify mobility and density of mobile ions in solid electrolytes in addition to the electronic conductivity. Using this method, we show that co-sputtering Li7La3Zr2O12 (LLZO) with Li2O increases the number of mobile lithium ions within amorphous LLZO, which reduces the electrostatic interaction between the disordered Zr-O and La-O chains and the lithium ions, thus decreasing the activation energy for ion migration. Finally, we quantify the changes in ion density and mobility upon doping crystalline LLZO with Al and Ga. The proposed approach in the quantification of mobile ions can be extended to other mixed ionic-electronic conductors for a better understanding of ion migration and the influence on battery performance.