Coupling of 3D Porous Hosts for Li Metal Battery Anodes with Viscous Polymer Electrolytes

Abstract

As the energy storage markets demand increased capacity of rechargeable batteries, Li metal anodes have regained major attention due to their high theoretical specific capacity. However, Li anodes tend to have dendritic growth and constant electrolyte consumption upon cycling, which lead to safety concerns, low Coulombic efficiency, and short battery lifetime. In this work, both conductive and non-conductive 3D porous hosts were coupled with a viscous (melt) polymer electrolyte. The cross-section of the hosts showed good contact between porous hosts and the melt polymer electrolyte before and after extensive cycling, indicating that the viscous electrolyte successfully refilled the space upon Li stripping. Upon deep Li deposition/stripping cycling (5 mAh cm−2), the non-conductive host with the viscous electrolyte successfully cycled, while the conductive host allowed rapid short circuiting. Post-mortem cross-sectional imaging showed that the Li deposition was confined to the top layers of the host. COMSOL simulations indicated that current density was higher and more restricted to the top of the conductive host with the polymer electrolyte than the liquid electrolyte. This resulted in quicker short circuiting of the polymer electrolyte cell during deep cycling. Thus, the non-conductive 3D host is preferred for coupling with the melt polymer electrolyte.