Bio-inspired sun battery stores solar energy as heat, outpacing lithium-ion density

UC Santa Barbara chemists report a bio-inspired pyrimidone molecule for molecular solar thermal (MOST) energy storage that captures sunlight, stores it in chemical bonds, and releases it as heat on demand. With an energy density over 1.6 MJ/kg—roughly twice that of lithium-ion batteries—the material can boil water under ambient conditions, enabling practical off-grid heating and solar-collector systems without bulky batteries. The approach functions like a rechargeable solar battery, with energy stored photochemically and released on trigger; the concept is reusable and recyclable and could transform how we store daytime sun for use later.