First rechargeable solar battery

Integrating the function of a solar panel that captures light, and a cheap battery that stores energy into one hybrid device, researchers have successfully invented the world's first solar battery.

The device will help bring down the costs of renewable energy by 25 percent, the researchers said.

The key to the innovation is a mesh solar panel that allows air to enter the battery, and a special process for transferring electrons between the solar panel and the battery electrode.

Inside the device, light and oxygen enable different parts of the chemical reactions that charge the battery.

"The state of the art is to use a solar panel to capture the light, and then use a cheap battery to store the energy," said Yiying Wu, a professor of chemistry and biochemistry at The Ohio State University in the US.

"We have integrated both functions into one device. Any time you can do that, you reduce cost," he added.

The invention also solves a longstanding problem in solar energy efficiency, by eliminating the loss of electricity that normally occurs when electrons have to travel between a solar cell and an external battery.

Typically, only 80 percent of electrons emerging from a solar cell make it into a battery.

"With this new design, light is converted to electrons inside the battery, so nearly 100 percent of the electrons are saved," the researchers said.

The study appeared in the journal Nature Communications.