Designing Better Li Metal Anodes for Solid-State Batteries Using a Combined Experiment/Theory Approach

Abstract

Solid-state batteries have the potential to transform energy storage by providing significantly higher energy densities and improved safety compared to conventional Li-ion batteries. Robust high-capacity Li metal anodes are necessary to realize this technology, but current Li metal anode designs suffer from significant degradation over time due to non-uniform Li plating/stripping and loss of contact with the solid electrolyte during cycling. Carbon scaffold hosts have been shown to mitigate this problem in liquid electrolyte systems by creating a uniform electric field and providing abundant Li nucleation sites, but they have not been well explored in solid-state systems, which require the fabrication of more complicated mixed ion/electron conducting scaffolds to provide transport of both Li ions and electrons throughout the anode. We investigated the effect of scaffold architecture and chemistry on the resulting Li morphology and electrochemical performance using a combined experiment/theory approach. Carbon scaffolds with well-controlled geometries and varied porosities were fabricated using 3D printing and then characterized by SEM, Raman, and XPS before cycling in cells to evaluate their performance as hosts for uniform Li plating/stripping. Atomistic and mesoscale modeling were used to predict how scaffold chemistry and microstructure affect Li nucleation probability and the formation of current density/stress hotspots that can lead to dendrite growth, and these results were used to help guide scaffold design. This work provides further insight into the relationship between anode architecture and Li metal cycling stability in solid-state batteries and demonstrates progress toward an anode-free configuration, which promises to simplify cell manufacturing, decrease cost, and increase energy density by plating the Li metal anode directly from the cathode in situ.Lawrence Livermore National Laboratory is operated by Lawrence Livermore National Security, LLC, for the U.S. Department of Energy, National Nuclear Security Administration under Contract DE-AC52-07NA27344.