Void Nucleation

Formation Process

When lithium ions are stripped from the anode during cell discharge, they leave behind atomic vacancies that can coalesce if the transport rate of the lithium atoms is slower than the stripping current. This mismatch creates tiny empty spaces at the interface between the metal anode and the solid electrolyte. These nucleated voids act as barriers to subsequent ionic flow, forcing the remaining current to concentrate in the contact regions.

Sourcing Standards

Sourcing specifications for solid-state battery separators and polymer protection layers require properties that resist or suppress this void formation. Suppliers must provide materials that can maintain uniform mechanical pressure across the interface to encourage the plastic flow of lithium. This ensures that the nucleated voids are continuously closed, extending the cycle life of the purchased battery cells.

Cavity Formation

Lowering the operating current density below a certain threshold allows atomic diffusion to match the stripping rate, preventing the initial accumulation of vacancies. Below a threshold current density, atomic diffusion is fast enough to replenish the vacancies, preventing the creation of voids.