Engineering researchers have found that alkali metal additives, such as potassium ions, can prevent lithium microstructure proliferation during battery use. They used a combination of microscopy, nuclear magnetic resonance, and computational modeling to discover that adding small amounts of potassium salt to a conventional lithium battery electrolyte produces unique chemistry at the lithium/electrolyte interface, and modulates degradation during battery operation, preventing the growth of microstructures and leading to safer, longer lasting batteries.