Piezoelectric Mechanism and a Compliant Film to Effectively Suppress Dendrite Growth.

We show a piezoelectric mechanism that effectively suppresses dendrite growth using a compliant piezoelectric film as a separator or coating. When an electrode surface starts to lose stability upon lithium deposition, any protrusion causes film stretching, generating a local piezoelectric overpotential that suppresses deposition on the protrusion. Lithium ions thus spontaneously deposit to a flat surface. By proposing a theory that couples electrochemistry and piezoelectricity, we quantify the suppression effect and growth morphology. We find that the dendrite-suppression capability is over 5 × 105 stronger than the limit of mechanical blocking by any separators or solid-state electrolytes. Surprisingly, the mechanism ensures deposition to form a flat surface even if the initial substrate surface has significant protrusions, suggesting its robustness and effectiveness against manufacturing defects. We show that the mechanism is so strong that even a weak piezoelectric material is highly effective, opening up a wide range of materials.