Dendrite initiation and deflection in biaxially compressed solid electrolytes

Lithium metal solid-state batteries offer advantages of high energy density and improved safety compared with lithium ion batteries. However, solid-state batteries fail through short-circuiting even at low charging rates (<1 mA/cm2) due to lithium dendrite initiation and propagation. The location of dendrite initiation is still under debate, particularly between initiation at the surface and within the interior of the solid electrolyte. Here, we develop an in-plane biaxial compression method that provides direct evidence of dendrite initiation within the interior of garnet solid electrolytes. The biaxial compression also deflects dendrite propagation to be perpendicular to the electric field direction and prevents short-circuiting at extreme fast charging of 100 mA/cm2. This approach demonstrates the use of mechanics to address pressing challenges in next generation batteries.