Dual‐Functional Stacked Polymer Fibers for Stable Lithium Metal Batteries in Carbonate‐Based Electrolytes

Lithium (Li) metal has long been thought to be an ideal anode material for high‐energy‐density Li metal batteries (LMBs). Nonetheless, a variety of safety risks and short cycle life due to uncontrollable Li dendrite growth limit its practical application. Here, a novel polymer‐based 3D host composed of stacked polymer fibers (SPF) is purposefully designed using a simple electrospinning method to achieve dual‐functional properties that endow bottom‐up Li filling and morphologically regulate Li metal deposition over the host structure. As a result, the SPF allows for uniform Li‐ion flux in the electrode, leading to densely packed Li deposition and further stable cycling in conventional carbonate‐based electrolytes. Besides, a full cell paired with LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode results in a high‐energy‐density battery with a low negative/positive capacity ratio and a wide operating temperature range. This study presents a rational design for improving the stability and safety of Li metal anodes in conventional carbonate‐based electrolytes for advanced LMBs. Stacked polymer fibers with dual‐functional properties are fabricated using a simple electrospinning method, and they serve as an excellent 3D host. The incorporation of two different fibers suppresses lithium dendrites, allowing for uniformly deposited/dissolved Li metal up to 10 mAh cm−2 with densely packed morphology inside the host. The full cell improves cycle stability under a variety of operating conditions.