A more stable lithium anode by mechanical constriction for solid state batteries

Abstract

In solid state batteries, lithium dendrites form when the applied current density is higher than a critical value. The critical current density is often reported as 1–2 mA cm⁻² at an external pressure of around 10 MPa. In this work, a more advanced mechanical constriction technique is applied on a solid-state battery constructed with Li₁₀GeP₂S₁₂ (LGPS) as the electrolyte and a lithium metal/graphite composite as the anode, where the graphite layer was applied to prevent (electro-)chemical reactions between Li metal and LGPS, as well as a short-circuit upon the application of pressure. The decomposition pathway of LGPS at the anode interface is modified by this mechanical constriction design, and the growth of lithium dendrites is inhibited, leading to excellent rate and cycling performances. No short-circuit or lithium dendrite formation is observed for batteries cycled at a current density up to 10 mA cm⁻².