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StorageX Initiative is a cross-campus effort of the Precourt Institute for Energy.

Strain Engineering of Fast Charging Solid State Batteries

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PI: Wendy Gu, Mechanical Engineering ; William Chueh,  Materials Science and Engineering

 

Solid state batteries (SSBs) with lithium metal anode and non-flammable solid electrolytes (SEs) are attractive options for electric vehicles due to their high energy density (3860 mAh/g for Li metal) and potentially higher safety. Compared with conventional lithium-ion batteries, lithium-metal SSBs can have 70% and 40% increase in volumetric and gravimetric energy density, respectively[1]. However, lithium penetrations (also known as “dendrites”) that enter the solid electrolytes during charging may cause cell shorting. This problem is exacerbated by high charging rates. Here, we propose that the lithium penetration behavior of a garnet solid electrolyte, Ta-doped LLZO (Li6.6La3Ta0.4Zr1.6O12) can be minimized by applying mechanical strain. We hypothesize that an externally applied strain field can be coupled with the electrochemical driving force during lithium plating to enable robust and reliable SEs. Using fracture mechanics, we predict that compressive strain acting on pre-existing defects will inhibit the crack propagation of LLZO. These ideas will be investigated though experimental setups that allow us to apply compressive strain locally, globally, and on the surface of SEs. Electrochemical plating of lithium will be conducted simultaneously, at different strain levels to reveal the effect on battery performance. Finite element simulations will be used to understand internal stresses and strains within the devices.