Lithium Free Flexible Batteries

Rice Flex Battery
Thin-film battery attached to a polymer backing can retain its properties after being flexed 1,000 times. Credit: Jeff Fitlow/Rice University

Chemists at Rice University have developed a material that can function as an ultra-thin and flexible rechargeable battery and contains no lithium. Lithium is a common element used in many rechargeable batteries today. Lithium ion batteries can hold a lot of charge in a small package and can be reused and recharged over and over with little loss in capacity. Lithium also reacts exothermically with water, so ruptured batteries are a serious concern. The Rice University material keeps the benefits of lithium ion batteries without the lithium.

Their material consists of layers of nanoporous nickel-fluoride electrodes sandwiching a solid electrolyte. It is constructed by depositing nickel onto a polymer backing and chemically etching nanometer holes to increase surface area. The backing is removed and the electrodes are layered around an potassium hydroxide and polyvinyl alcohol electrolyte.

Capacity can be scaled up by simply adding more layers. Each nickel-fluoride layer is only a micron thick and the finished product is only a tenth of a millimeter thick. These thin batteries would be ideal for wearable powered products since they can withstand flexing and still retain their capacitance. They also show promise to possibly replace lithium ion batteries in some devices.

Manufacture techniques and testing of this material was published online on the Journal of the American Chemical Society‘s website on April 15, 2014.