Influence of Mechanical Performance of Elastomeric Electrolytes on the Stability of Lithium Metal Batteries

The mechanical properties of polymer electrolytes play an important role in determining the stability of lithium metal batteries (LMBs) due to the substantial volume fluctuations of the lithium (Li) anode and dendritic Li growth. We systematically investigate the influence of the mechanical characteristics of elastomeric electrolytes on the cycling performance of LMBs over a wide temperature range, including both ambient and low-temperature conditions. The elastomeric electrolytes feature a bicontinuous architecture composed of elastomeric and plastic crystal phases, allowing selective tuning of their mechanical properties by modulating the crosslinking density. The elastomeric electrolytes maintain a high ionic conductivity through the plastic crystal phase, achieving ~1.1 and 0.24 mS cm^–1 at 25 and −10 °C, respectively. At an optimal crosslinking density, the electrolyte exhibits a balanced combination of toughness, adhesion energy, and elastic recovery, enabling a superior cycling performance in Li||LiNi_0.8Co_0.1Mn_0.1O₂ full cells. In contrast, elastomeric electrolytes with low crosslinking density suffer from plastic deformation and interfacial contact loss with the Li anode, while excessively crosslinked systems exhibit brittleness and are prone to fracture, both leading to inferior cycling stability.