Analyzing void formation and rewetting of thin in situ-formed Li anodes on LLZO

Abstract

•The stripping behavior of thin Li was correlated with current density and thickness •Two regimes of thin Li stripping behavior were identified •The effect of Li void formation during unstable stripping is not fully recovered •De-wetted Li/solid electrolyte interfaces can be reestablished by a thermal treatment The transition from laboratory-scale thick Li-metal anodes (>500 μm) to thin (∼10–30 μm) Li anodes is necessary for the successful implementation of Li-metal solid-state batteries (LMSSBs). However, the mechanical deformation of Li along an interface depends on its thickness, making it essential to understand the interface mechanics between thin Li layers and solid electrolytes. We investigate the stripping behavior of thin Li electrodes that are formed using in situ plated (anode-free) Li on Li7La3Zr2O12 garnet-type solid electrolytes. We demonstrate that the accessible discharge capacity increases as current density decreases and the Li anode thickness increases. It is shown that two different mechanisms restrict the stripping of thin Li electrodes, depending on the current density. We demonstrate that de-wetted Li/LLZO interfaces during stripping can be reestablished using a thermal treatment. This approach could be integrated into future charging protocols, and the findings provide insight into LMSSB design, implementation, and operation. The transition from laboratory-scale thick Li-metal anodes (>500 μm) to thin (∼10–30 μm) Li anodes is necessary for the successful implementation of Li-metal solid-state batteries (LMSSBs). However, the mechanical deformation of Li along an interface depends on its thickness, making it essential to understand the interface mechanics between thin Li layers and solid electrolytes. We investigate the stripping behavior of thin Li electrodes that are formed using in situ plated (anode-free) Li on Li7La3Zr2O12 garnet-type solid electrolytes. We demonstrate that the accessible discharge capacity increases as current density decreases and the Li anode thickness increases. It is shown that two different mechanisms restrict the stripping of thin Li electrodes, depending on the current density. We demonstrate that de-wetted Li/LLZO interfaces during stripping can be reestablished using a thermal treatment. This approach could be integrated into future charging protocols, and the findings provide insight into LMSSB design, implementation, and operation.