(371c) Using Surface Thermochemistry and Band Alignment to Stabilize Interfaces in Solid-State Batteries | AIChE

(371c) Using Surface Thermochemistry and Band Alignment to Stabilize Interfaces in Solid-State Batteries

Authors 

Warburton, R. - Presenter, Yale University
Greeley, J., Purdue University
Undesired side reactions at the electrode–electrolyte interface limit the practical implementation of solid-state battery technology. Strategies to mitigate solid–solid interfacial reactivity have been developed; however, many fundamental design principles are based on bulk materials properties, which may not be fully representative of the relevant surface and interface chemistry. Here, we use density functional theory (DFT) calculations and ab initio molecular dynamics (AIMD) to describe molecular mechanisms of interfacial reactivity between a Li metal anode and a lithium lanthanum titanate (LLTO) solid electrolyte. Grand canonical thermodynamic analyses are used to develop rational molecular models of the explicit Li/LLTO interface that are likely to exist under the conditions of a lithium ion battery. The dynamics of these interfaces are probed using AIMD, elucidating pathways for bond-breaking, redox chemistry, and interfacial reconstruction. We find that the insights gained from AIMD modeling of the Li/LLTO interface align well with the driving forces for electron transfer implied by computed surface band edge positions. These computational analyses are used to propose La2O3 as a suitable interlayer coating based on its thermodynamic stability and interfacial band alignment with Li and LLTO. These predictions are supported by X-ray scattering experiments for Li deposition on untreated and La2O3-coated LLTO thin films, suggesting that the La2O3 interlayer inhibits redox chemistry and reconstruction at the Li/LLTO interface. Descriptors based on interfacial thermochemistry and electrostatics represent opportunities to develop tailored solid–solid interfaces in solid-state batteries.