A self-healing plastic ceramic electrolyte by an aprotic dynamic polymer network for lithium metal batteries.

Oxide ceramic electrolytes (OCEs) have great potential for solid-state lithium metal (Li) battery applications because, in theory, their high elastic modulus provides better resistance to Li dendrite growth. However, in practice, OCEs can hardly survive critical current densities higher than 1 mA/cm. Key issues that contribute to the breakdown of OCEs include Li penetration promoted by grain boundaries (GBs), uncontrolled side reactions at electrode-OCE interfaces, and, equally importantly, defects evolution (e.g., void growth and crack propagation) that leads to local current concentration and mechanical failure inside and on OCEs. Here, taking advantage of a dynamically crosslinked aprotic polymer with non-covalent -CH⋯CF bonds, we developed a plastic ceramic electrolyte (PCE) by hybridizing the polymer framework with ionically conductive ceramics. Using in-situ synchrotron X-ray technique and Cryogenic transmission electron microscopy (Cryo-TEM), we uncover that the PCE exhibits self-healing/repairing capability through a two-step dynamic defects removal mechanism. This significantly suppresses the generation of hotspots for Li penetration and chemomechanical degradations, resulting in durability beyond 2000 hours in Li-Li cells at 1 mA/cm. Furthermore, by introducing a polyacrylate buffer layer between PCE and Li-anode, long cycle life >3600 cycles was achieved when paired with a 4.2 V zero-strain cathode, all under near-zero stack pressure.