Abstract: Described herein are devices and methods for flash freezing samples while applying an in situ electrical current or bias. Advantageously, the present application is directed towards materials, such as batteries or electrochemical cells, where applying an electrical current or bias leads to dynamic changes to the structure and chemistry of constituent materials, which underpin device performance and degradation. By concurrently applying electrical current or bias and flash freezing the sample, transient structures in the anode, cathode, or electrolyte can be observed with a high degree of temporal resolution at an atomic scale.