固体電池の亀裂進展を測定する新技術を開発（Why solid-state batteries keep short-circuiting）

2026-03-25 マサチューセッツ工科大学（MIT）

Researchers used a new visual technique to measure stress in a material as a dendrite crack grows. Here, the four graphs have the same data with different color schemes. Brighter colors correspond to higher stress, and a bowtie-shaped pattern can be seen at the crack tip.Credits:Image: Courtesy of the researchers

＜関連情報＞

• https://news.mit.edu/2026/why-solid-state-batteries-keep-short-circuiting-0325
• https://www.nature.com/articles/s41586-026-10279-z

固体電解質中では、デンドライトの成長に伴って電気化学的腐食が発生する Electrochemical corrosion accompanies dendrite growth in solid electrolytes

Cole D. Fincher,Colin Gilgenbach,Christian Roach,Rachel Osmundsen,Aubrey Penn,Michael D. Thouless,W. Craig Carter,Brian W. Sheldon,James M. LeBeau & Yet-Ming Chiang
Nature  Published:25 March 2026
DOI:https://doi.org/10.1038/s41586-026-10279-z

Abstract

Charging rates, cycling performance and safety of solid-state batteries using metal negative electrodes are often limited by dendrites^1,2,3, the growth of which depends on coupling between electrochemical and mechanical driving forces. Previously, it has been assumed that dendrites propagate when plating-induced stresses reach the fracture stress of the solid electrolyte. Here we show that dendrites can propagate at far lower stresses. Using operando birefringence microscopy⁴, we directly measure stresses around growing dendrites in garnet Li_6.6La₃Zr_1.6Ta_0.4O₁₂, a highly stable solid electrolyte^5,6,7. Plating-induced stresses are present throughout growth and approach the mechanical fracture stress for the slowest-growing dendrites. As current densities and dendrite velocities increase, the stresses accompanying dendrite growth surprisingly decrease, with dendrite propagation occurring at stresses up to 75% lower than under mechanical load alone. Cryogenic scanning transmission electron microscopy (STEM) of dendrites propagated at high current reveals electrolyte decomposition to new phases, associated with which is a net molar volume contraction. The electrochemically induced mode of embrittlement may be mitigated through understanding and control of the nature of phase transitions accompanying instability.