Batteries and clocks are things we all use every day. But this episode may cause you to think about them in new ways. We'll trace the development of a solid battery electrolyte for lithium ions to pass through. It allows a threefold performance improvement over current lithium ion batteries. And we'll see a demonstration confirming Einstein's idea that gravity alters the speed of time itself! It's done with optical lattice atomic clocks, and their secret ingredient: strontium.