Researchers from Rice University in Texas, US, have created a re-chargeable lithium-ion battery that can be constructed by painting or spray-coating its component layers.
The Rice researchers have taken a conventional lithium-ion battery and designed it as a five-layer device that is spray-painted in a sequence of two electrodes with respective current collectors and electrolyte.
This form of battery fabrication could enable energy storage to be designed and integrated into more products and applications, for example photovoltaic (PV) cells integrated with their own storage function.
The concept of creating hybrid PV-energy storage devices has been taken up by several universities and research institutes around the world.
Recently, scientists from the Amrita Center for Nanoscience and Molecular Medicine in India, announced a prototype solar cell and supercapacitor integrated in one tile, able to charge a smart phone with several days of storage. The device, based on nanoscale thin films, could in future be made thinner, lighter and even flexible, opening up renewable energy generation and storage for different applications and products that get their power, wirelessly, from renewable sources of electricity.
In the Rice researchers' project nine connected batteries spray-painted onto tiles were then attached to a small silicon solar cell that generated energy from a white lamp. The system provided 2.4 volts, used to power a small LED sign for several hours, going through dozens of charge cycles without significant decay in capacity. The team have also tried out their technique on various substrate materials.
Imprint Energy is a start-up in the US developing a screen printable battery for micro-power applications, but with a view to replacing lithium polymer/thin film batteries for small/portable electronics in the 30mAh-1Ah range.
Increasingly solar panels are being produced using thin film/ OPV technologies and novel printable and paintable battery formats could be matched, or integrated, into a solar module. However, according to Imprint Energy such applications will not be commercially viable for another 10 years, where reliability and product lifetimes will require significant development and testing to achieve.
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