High-Dielectric Polymer Coating for Uniform Lithium Deposition in Anode-Free Lithium Batteries

Abstract

The use of lithium metal either in an anode or anode-free configuration is envisaged as the most promising way to boost the energy density of the current lithium-ion battery system. Nevertheless, the uncontrolled lithium dendritic growth inhibits practical utilization of lithium metal as an anode due to safety concerns and low Coulombic efficiency. In this work, we show that when a high-dielectric SEI is coated on a current collector, it can effectively promote a uniform lithium deposition by decreasing the overpotential between the surfaces, lowering the local current density and suppressing lithium protrusions. Using a PVDF (polyvinylidene difluoride)-based dielectric medium, it is demonstrated that varying the dielectric properties of PVDF by crystallinity control can regulate the lithium deposition mechanisms. Moreover, when the dielectric properties of PVDF film are tailored by the inclusion of dielectric nanoparticles, a selective formation of high dielectric beta-PVDF phase is induced during its film formation (LiF@PVDF), which synergistically promotes uniform lithium deposition/stripping in an anode-free half-cell setup.