Solid-state lithium metal batteries (SSBs) are promising for electric vehicles because of their potential to provide high energy density and enhanced safety. However, these batteries face short-circuit challenges caused by uncontrolled lithium dendrite growth during cycling. Using operando scanning electron microscopy and phase-field simulations, we determined that failure of SSBs is closely linked to the fatigue of the lithium metal anode, which markedly contributes to interface degradation and dendrite growth in SSBs. This fatigue follows the Coffin-Manson equation in mechanics, indicating that it is an innate characteristic. Clarifying the essential role of fatigue provides a physical basis for understanding failures of SSBs and paves the way to extending their lifespan.

Sodium metal anodes (SMAs) suffer from extremely low reversibility (95% with conventional NaPF ₆ salt at a regular concentration (1.0 M). The peculiar role of FEC is firstly unraveled via its involvement into the solvation structure, where a threshold FEC concentration with a coordination number>1.2 is needed in guaranteeing high Na reversibility over the long-term. Specifically, by incorporating an average number of 1.2 FEC molecules into the primary Na ⁺ solvation sheath, lowest unoccupied molecular orbital (LUMO) levels of such Na ⁺ -FEC solvates undergo further decrease, with spin electrons residing either on the O=CO(O) moiety of FEC or sharing between Na ⁺ and its C=O bond, which ensures a prior FEC decomposition in passivating the Na surface against other carbonate molecules. Further, by adopting cryogenic transmission electron microscopy (cryo-TEM), we found that the Na filaments grow into substantially larger diameter from ~400 nm to >1 μ m with addition of FEC upon the threshold value. A highly crystalline and much thinner (~40 nm) solid-electrolyte interphase (SEI) is consequently observed to uniformly wrap the Na surface, in contrast to the severely corroded Na as retrieved from the blank electrolyte. The potence of FEC is further demonstrated in a series of “corrosive solvents” such as ethyl acetate (EA), trimethyl phosphate (TMP), and acetonitrile (AN), enabling highly reversible SMAs in the otherwise unusable solvent systems.

Artificially structured coatings are widely employed to minimize materials deterioration and corrosion, the annual direct cost of which is over 3% of the gross domestic product (GDP) for industrial countries. Manufacturing higher performance anticorrosive coatings is one of the most efficient approaches to reduce this loss. However, three-dimensional (3D) structure of coatings, which determines their performance, has not been investigated in detail. Here we present a quantitative nano-scale analysis of the 3D spatial structure of an anticorrosive aluminium epoxy barrier marine coating obtained by serial block-face scanning electron microscopy (SBFSEM) and ptychographic X-ray computed tomography (PXCT). We then use finite element simulations to demonstrate how percolation through this actual 3D structure impedes ion diffusion in the composite materials. We found the aluminium flakes align within 15° of the coating surface in the material, causing the perpendicular diffusion resistance of the coating to be substantially higher than the pure epoxy.

High-resolution three-dimensional structure of chromosomes in a human prophase nucleus from electron microscopy.