Atomic structure of sensitive battery materials and interfaces revealed by cryo–electron microscopy

TLDR

Cryo-electron microscopy preserves the native state of beam‑sensitive battery materials, enabling atomic resolution of lithium atoms and their interfaces with the solid electrolyte interphase. Using cryo‑EM, the authors observed lithium dendrites forming faceted, single‑crystalline nanowires that grow along <111>, <110>, or <211> directions, change direction at kinks without defects, and exhibit distinct SEI nanostructures depending on the electrolyte.

Abstract

Whereas standard transmission electron microscopy studies are unable to preserve the native state of chemically reactive and beam-sensitive battery materials after operation, such materials remain pristine at cryogenic conditions. It is then possible to atomically resolve individual lithium metal atoms and their interface with the solid electrolyte interphase (SEI). We observe that dendrites in carbonate-based electrolytes grow along the <111> (preferred), <110>, or <211> directions as faceted, single-crystalline nanowires. These growth directions can change at kinks with no observable crystallographic defect. Furthermore, we reveal distinct SEI nanostructures formed in different electrolytes.