Elastic and plastic mechanical properties of lithium measured by nanoindentation

Abstract

Metallic lithium is the desired anode material for high energy density solid state batteries and shows a factor of four range in elastic modulus and two orders of magnitude difference in creep properties dependent on sample preparation and testing method. In this paper we use in-situ nanoindentation to measure the anisotropic mechanical properties from the BCC crystal structure and the effect of strain-rate and temperature, which have an impact on battery cycle performance. This work clarifies the reasons for the range of property values reported in the literature with a global equation for yield strength with strain-rate. From this information conclusions can be drawn around variables to optimise in order to minimise the required pressure for a chosen stripping critical current in solid state batteries.

Keywords

• Lithium metal
• Mechanical properties
• Nanoindentation