Pressure-induced interfacial contacts and the deformation in all solid-state Li-ion batteries

In this paper, we use a combination of computational models and experiments to study the effects of stack pressure on interfacial contacts and deformation of solid state electrolytes in an all solid state battery (ASSB). The induced strain distributions in the LiBH₄–LiNH₂ based all solid-state battery are measured using a combination of in-situ optical microscopy and digital image correlation (DIC) techniques, while the contact strains and stresses are computed using analytical and computational finite element models. The results show that moderate pressure improves the interfacial contacts and battery electrochemical performance characteristics with low induced strains in the electrolyte, while high pressure induces large axial and shear strains that can cause failure by yielding or cracking phenomena, in addition to the degradation of electrochemical performance characteristics. The highest room temperature conductivity of 9 × 10⁻⁵ Scm⁻¹ was obtained at a stack pressure of 0.26 MPa. The implications of the results are discussed for the design and fabrication of robust all solid state batteries with improved performance characteristics.