Engineering solid-state batteries for dendrite deflection The insights described above are transferable to realistic solid-state battery architectures. Beyond externally applied stresses, the required in-plane stresses necessary to deflect dendrites can be produced by other means. As one example, we show that thermal expansion mismatches are easily capable of producing the desired in-plane residual stresses within layers of a prototypical solid-state lithium battery in which the solid-electrolyte layer is bounded by a lithium metal negative electrode and an oxide cathode (Fig. ). Assuming no delamination between the Li -solid electrolyte and solid electrolyte -cathode interfaces, a thermal expansion mismatch between layers will result in a residual stress. However, the very low yield stress of Li metal (~1 MPa indicates that it will flow to relieve the resulting stress. On the other hand, a non-ductile solid electrolyte and cathode will support thermal expansion mismatch stresses. To achieve high energy density and fast charging, it is furthermore desirable that the electrolyte be thin relative to the cathode. In this case, the residual stress will be primarily borne by the solid electrolyte, as desired. If the cathode has a higher coefficient of thermal expansion than the electrolyte, the electrolyte will experience a residual compressive stress after cooling from the stress-free state at elevated temperature. An alternate approach to producing the requisite compressive biaxial stress in a solid-electrolyte layer is to laminate two solid-electrolytes with different thermal expansion coefficients (Fig. ), in which case the electrolyte of lower 𝛼𝛼 receives the compressive stress. In both cases, the residual compressive stress is expressed as: