How Does External Pressure Shape Li Dendrites in Li Metal Batteries?

摘要

High-energy density lithium metal batteries have achieved great progress as next-generation rechargeable cells. However, the huge gap in the switching from coin to pouch cells hinders their practical application. External pressure, as one discrepancy between coin and pouch cells, plays an important role in the performance of Li metal anodes. Herein the mechanism for the impact of external pressure on Li dendrites is revealed and quantified by a mechano-electrochemical phase field model. Two influence approaches are outlined as: 1) Inhibiting the progress of electroplating reactions, which lower the rate performance of cells; 2) Shaping the morphology of Li dendrites to be smooth and dense but increasing the mechanical instability. Furthermore, a phase diagram of routine electrolytes (including electrolyte-immersed separators and solid polymer electrolytes) with respect to various external pressures is established, giving rational guidance for designing pressure management systems in working batteries.