Abstract
Solid-state batteries offer the promise of improved energy density and safety compared to lithium-ion batteries, but electro-chemo-mechanical evolution and degradation of materials and interfaces can play an outsized role in limiting their performance. Here, I will present my group’s recent work on understanding structural evolution, interfacial dynamics, and chemo-mechanics in solid-state batteries with both lithium metal and alloy-based anodes. Lithium metal batteries are especially beneficial if used in an “anode-free” configuration in which there is no lithium initially present at the anode current collector. Using X-ray tomography, cryo-FIB, and finite-element modeling, we show that lithium metal anode-free solid-state batteries are intrinsically limited by current concentrations at the end of stripping due to localized lithium depletion. This causes accelerated short circuiting compared to lithium-excess cells. Based on these results, the beneficial influence of metal alloy interfacial layers on controlling lithium evolution and mitigating contact loss from localized lithium depletion will be introduced and discussed. In the second part of the talk, the characteristics of dense, foil-based alloy anodes are introduced. Alloy foils such as aluminum and tin are shown to exhibit improved interfacial stability and better long-term cycling in solid-state batteries compared to liquid-cell batteries due to reduced solid-electrolyte interphase formation. A new design for multiphase aluminum foil alloy anodes is introduced, in which microstructural control over the foil is shown to play a key role in significantly improving reversibility in solid-state batteries. This anode design mitigates chemo-mechanical degradation and offers a paradigm that does away with slurry coating, potentially reducing manufacturing costs. The influence of stack pressure on electrode evolution is investigated. Taken together, these findings show the promise of both lithium metal and alloy anodes for solid-state batteries, with divergent reaction mechanisms giving rise to different operating conditions necessary for each class of materials.
Published Version
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