Separator Dependency on Cycling Stability of Lithium Metal Batteries Under Practical Conditions

Development of practical lithium (Li) metal batteries (LMBs) remains challenging despite promises Li anodes (LMAs), owing to dendrite formation and highly reactive surface nature. Polyolefin separators used in LMBs may undergo severe mechanical chemical deterioration when contacting with LMAs. To identify the best polyolefin separator for LMBs, this study investigated separator-deterministic cycling stability under conditions, redefined key influencing factors, including pore structure, stability, affinity, using 12 different commercial separators, polyethylene (PE), polypropylene (PP), coated separators. At extreme compression triggered by LMA swelling, isotropic stress release balancing machine direction transverse tensile strengths was found be crucial mitigating cell short-circuiting. Instead PP a PE that possesses high elastic modulus connected structure can uniformly regulate swelling. The ceramic coating reinforced short-circuiting resistance, while efficiency degraded rapidly detrimental interactions between ceramics This identified design principle respect affinity toward LMAs elucidating impacts modification on performance.