Matt McDowell is an expert in electrochemical materials and devices. On this episode, we talk about everything batteries — how they work, the state-of-the-art, what still needs to be improved, and what options are on the table for future technologies. We also discuss Matt and his students’ use of in situ experiments — those able to make measurements of a device while it is operating — and how they use this capability to understand the atomic scale details that govern battery performance and failure. We also ponder if batteries will ever be used as the main source of energy in airplanes and, if so, what it will take to get there. (Recorded on February 1, 2018. Edited by Andrew Cannon)