Mesh-Supported Porous Film as a Reservoir for Insoluble Additives and Facilitator of Stable Li Accommodation in Li-Metal Anodes

An anode structure is proposed for Li-metal secondary batteries. The anode structure comprises a porous film that serves as a reservoir to continuously supply electrolyte-insoluble additives and a mesh-type spacer that mechanically supports the film and also provides space for stable Li storage. Specifically, LiNO3, an effective additive for controlling the solid–electrolyte interphase (SEI) layer of the Li-metal anode but barely soluble in commercial electrolytes using carbonate-based ester solvents, is embedded in the polymer film for achieving its continuous supply. The film is prepared to be porous to ensure Li-ion transport. However, the increased film porosity and high additive content degrade the physical stability and flexibility of the film. To counteract this, a polymer mesh is integrated into the film as a mechanical support, realizing a high LiNO3 loading and high film porosity, which are crucial for sufficient LiNO3 supply and Li-ion transport kinetics. Additionally, the polymer mesh provides a fixed-height space for Li accommodation, maintaining a consistent electrode thickness during charge/discharge processes. This integrated anode structure, realized through a low-cost and simple process, addresses the technical challenges of SEI layer control and electrode thickness stabilization in Li-metal anodes, offering a practical solution for Li-metal secondary batteries.