Li nucleation in anode-free solid-state Batteries: The role of interfacial mechanics

Anode-free solid-state batteries (AFSSBs) enable higher energy density without the need for excess lithium compared to conventional all solid-state batteries. However, heterogeneous nucleation at the interface of the current collector (CC) and solid electrolyte (SE) is prone to inducing Li dendrites, which hinders AFSSBs development. Delamination of the CC–SE interface, which involves interfacial work of adhesion, is required during the nucleation process. Herein, a thermodynamic model of heterogeneous nucleation related to interfacial work of adhesion and a bulge model of Li nucleation are established and Li nucleation and plating experiments are performed to investigate the effect of the work of adhesion on Li nucleation behavior. The results demonstrate that increasing the work of adhesion of the CC–SE interface extends the nucleation time while increasing the Li radius and decreasing the number density of Li nuclei. Larger Li nuclei reduce the pressure within the CC, which diminishes the driving force (overpotential) of nucleation and likelihood of short-circuiting. The study findings suggest that stronger work of adhesion facilitates homogeneous Li nucleation, providing insight for optimizing the interface in AFSSBs.