Stabilizing the dual electrode interface via a crosslinked gelatin nonwoven separator for durable lithium metal batteries

The uncontrollable dendrite growth of lithium anode and active material dissolution of transition metal oxides cathodes severely hinder the development of lithium metal batteries. An effective strategy to address these issues is optimizing the separator to regulate ion transport and trap the lost active component. Herein, a crosslinked gelatin nonwoven (CGN) separator is elaborately fabricated through electrospinning and in-situ vapor phase crosslinking process to manipulate the dual electrode interface. Benefitting from the characteristic composition of gelatin, and porous structure of electrospun nonwoven, the CGN separator exhibits excellent interface wettability and low interface resistance, featuring a high Li⁺ transference number of 0.70 and high ionic conductivity of 3.75 mS/cm. As expected, the symmetrical Li/Li cells present stable cycling behavior for 1900 h at 0.5 mA/cm² with low overpotential of 20 mV. The optimized LiMn₂O₄/Li cells deliver high reversible capacity of 103 mAh/g as well as high capacity-retention ratio of 83.7 % after 100 cycles at 0.3 C, which can be effectively attributed to the strong interaction between CGN separator and Mn ions to prevent the loss of active Mn component. This study indicates the application potential of protein-based electrospun membrane for high-performance lithium metal batteries.