On the flip side, batteries in our devices have to be recharged and renewable energy is the best way to accomplish that.

But what if a battery could generate the energy needed to recharge it? That's just what researchers at Kogakuin University in Japan have created. The group has developed a thin, translucent lithium-ion battery that recharges itself when exposed to direct sunlight.

Instead of plugging into a separate solar panel, the translucent battery functions both as a rechargeable battery and as a photovoltaic cell. The researchers hope that in the near future the technology will evolve into large, transparent smart windows for buildings that can generate and store energy.

This team had previously unveiled a translucent lithium-ion battery four years ago that recharged with a connected solar panel.