Synergistically Suppressing Lithium Dendrite Growth by Coating Poly-l-Lactic Acid on Sustainable Gel Polymer Electrolyte

Lithium (Li) metal batteries are promising candidates in next-generation high-power energy storage devices. However, Li dendrite growth induces great safety issues. Herein, inspired by the high electrolyte uptake, high polarity of the cellulose derivative, and excellent mechanical properties of poly-l-lactic acid (PLLA), a sustainable multifunctional gel polymer electrolyte (GPE) through coating a thin PLLA film on the natural polymer is proposed for Li dendrite suppression and cycling stability improvement. In addition, PLLA film coating can also enhance the thermal stability and interfacial interaction between the PLLA-coated GPEs and Li metal, thus improving the safety of the batteries. Due to these unique beneficial features, the green GPEs enable stable cycling of the Li metal anode with an enhanced Li⁺ transference number and coulombic efficiency during extended cycles and increases the lifetime by inhibiting short-circuit failures even under a high energy density and extensive Li metal deposition.