Improving Cycling Performance of Anode-Free Lithium Batteries by Pressure Control

Abstract

For the anode-free Lithium (Li) batteries (AFLBs), an uniform/dense Li deposition is ideal to stabilize the interface with a solid electrolyte interface (SEI) layer between copper current collector and liquid electrolyte, and minimize the electrolyte/lithium consumption for long-term cell operation. Unlike in the case of Li-ion or Li-metal battery systems where Li metal foil and graphite anode can serve as a cushion to uniformly distribute the pressure, the deposited Li in AFLB is much more sensitive to the pressures and current distribution applied on the copper foil electrode in the AFLBs. We found that the commercial coin cell components lead to a non-uniform/porous Li deposition and further a brittle SEI layer after the cell was charged to 4.5V and discharged to 3.5V, respectively. This non-uniform interface results in poor cycling performance of AFLB coin cells. In this work, we optimized the internal pressure in the coin cells and revealed the internal pressure effect on stabilizing a SEI layer and improving AFB cycling performance.