Boosting the Energy Density of “Anode‐Free” Lithium Metal Batteries via Electrospun Polymeric Scaffolds

Abstract While “anode‐free” or “zero‐excess” battery designs may maximize the obtainable energy density of batteries based on metal deposition, occurring losses of capacity are not replenished by a negative electrode metal reservoir, limiting cycle life and maintenance of the initially superior energy density. In addition to modifications of electrolyte constituents and negative electrode surfaces, the employment of host structures that accommodate lithium metal deposits denotes a feasible approach to boost the reversibility of lithium inventory. By combining a highly porous and lightweight scaffold of an electrospun polymer with a thin separator, a cell design is introduced that simultaneously boosts lithium reversibility and projected energy density of “anode‐free” lithium metal batteries. Though “cell breathing” and swelling upon cycling are still observed, the favorable dielectric properties of scaffold‐decorated copper evidently reduce the extent of “dendritic” and electronically insulated (“dead”) lithium metal deposits, thus prolonging the cycle life of “anode‐free” lithium metal batteries. Demonstrating that porous scaffold structures are indeed able to enhance the energy densities of “anode‐free” lithium metal batteries despite an increased negative electrode volume represents an important step for the viability and applicability of such host structure concepts.