Scientists Develop a “Liquid Battery” That Stores Sunlight and Converts It into Heat

Researchers at the University of California, Santa Barbara, have created a new type of liquid material that captures sunlight and stores it as thermal energy.

The innovation is based on an organic molecule called pyrimidone, whose structure resembles a component of DNA.

When exposed to ultraviolet light, the molecule changes its shape, storing energy, and later returns to its original state, releasing heat when needed.

A Molecular “Solar Spring”

Scientists compare the mechanism to photochromic sunglasses: they darken in sunlight and become clear indoors.

Similarly, pyrimidone undergoes a reversible structural transformation — but instead of changing color, it stores energy.

After absorbing sunlight, the molecule twists like a spring, locking energy within its chemical bonds.

When triggered by heat or a catalyst, it relaxes back, releasing the stored thermal energy.

Compact and Long-Term Stable

The research team simplified the molecular structure, removing unnecessary elements to make it lightweight and compact.

As a result, the material can retain stored energy for years without significant losses.

Computer simulations, conducted in collaboration with scientists from UCLA, helped explain its remarkable stability and efficiency.

Energy Density Advantage

Pyrimidone demonstrates an energy density exceeding 1.6 MJ/kg — nearly double that of conventional lithium-ion batteries.

Laboratory tests showed that the released heat is strong enough to boil water.

Potential Applications

This technology could be used for off-grid heating systems.

Since the material is water-soluble, it could circulate through rooftop solar collectors, store energy during the day, and release heat at night.

Such advancements represent a promising step forward in renewable energy storage.