flexible battery

Flexible battery promises 10 times improved energy density

Image credit: University Of California - San Diego

Scientists have developed a rechargeable silver oxide-zinc battery that they claim has a five to 10 times greater energy density than alternatives.

The battery is also easier to manufacture than other flexible batteries, which need to be manufactured in sterile conditions under vacuum. This new design can be screenprinted in normal lab conditions.

The researchers from the University Of California San Diego and start-up company ZPower envisage their battery being used in flexible, stretchable electronics for wearables, as well as soft robotics.

“Our batteries can be designed around electronics, instead of electronics needing to be designed around batteries,” said Lu Yin, one of the lead researchers.

The battery is claimed to achieve about 50 milliamps per square centimetre at room temperature: around 10-20 times greater than the areal capacity of a typical lithium-ion battery, something which the researchers believe has never before been obtained.

The prototype also has a higher capacity than any of the flexible batteries currently available on the market due to its lower impedance (the resistance of an electric circuit or device to alternative current). The lower the impedance, the better the battery performance against high current discharge.

“As the 5G and Internet of Things' (IoT) market grows rapidly, this battery that outperforms commercial products in high current wireless devices will likely be a main contender as the next-generation power source for consumer electronics” said researcher Jonathan Scharf.

The batteries have already been used to power a flexible display system equipped with a microcontroller and Bluetooth modules, where it performed better than commercially available Lithium coin cells.

The printed battery cells were also recharged for over 80 cycles without showing any major signs of capacity loss and remained functional in spite of repeated bending and twisting.

“Our core focus was to improve both battery performance and the manufacturing process,” said researcher Ying Shirley Meng.

To create the battery, the researchers used a proprietary cathode design and chemistry. They printed the battery onto a polymer film that is chemically stable, elastic and has a high melting point that can also be heat sealed.

The team is already at work on the next iteration of its battery, aiming for cheaper, faster charging devices with even lower impedance that could be used in 5G devices and in soft robotics, where high power and customisable, flexible form factors are required.

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