Spray-on Rechargeable Batteries Could Store Energy Anywhere

A team of mechanical engineers has published a paper demonstrating its latest invention -- spray-on rechargeable batteries that could be combined with solar cells to create self-sufficient, energy conversion-storage devices.

By Liat Clark, Wired UK

A team of mechanical engineers has published a paper demonstrating its latest invention -- spray-on rechargeable batteries that could be combined with solar cells to create self-sufficient, energy conversion-storage devices.

[partner id="wireduk"] The paper, published in Nature Scientific Reports, explains that by breaking down the different components of a battery -- the electrodes, separator, electrolyte and current collectors -- and rendering them into liquid form, we could revolutionize the way we power our devices. Rather than being tied to fixed shapes and sizes, batteries could one day take on practically any form, and be applied almost anywhere.

The technology, it says, would enable, "widespread renewable energy capture, storage and utilization."

Lithium-ion batteries are made by tightly rolling up the various battery components in layers before encasing them in rectangular or cylindrical packaging. The engineers, from Rice University in Texas, devised their own unique version of a multilayer battery by painting these individual battery components (two current collectors, a cathode, an anode and a polymer separator) on to select surfaces in layers. These layers included paints made from lithium cobalt oxide (a positive electrode), lithium titanium oxide (a negative electrode) and conductive single-walled nanotubes (a current collector). The special polymer paint blend helped achieve superior conductivity by forming the micro-porous layer required in a lithium battery.

The final paints were layered on to glass, stainless steel, glazed ceramic tiles and flexible polymer sheets -- the resulting "batteries" worked just as well as the regular version. The team even picked out a choice ceramic mug, spray-painted the word "rice" in capital letters using a stencil, and demonstrated its efficiency as a battery.

Even more complex battery structures could be created, the paper added, using different nozzle fixtures on the spray cans.

The team went on to propose that by fitting a "Lego unit" -- a series of these batteries grouped together -- to a series of solar cells, a new and independent type of energy conversion-storage devices could be created. This was tested by fitting nine spray-painted ceramic tiles together, then gluing polycrystalline silicon solar cells to this "Lego unit". One of the cells was charged-up by illuminating it with a white light -- the current from this passed through to the other cells and, together, the nine cells had enough power to charge 40 red LED lights for more than six hours.

The paper concluded that these "Lego cells… could be used to convert any outdoor surface to an energy conversion-storage device".

The main drawback of the ingenious spray-paint system is that lithium-ion batteries need oxygen-free, dry conditions to be created since they are made using toxic, flammable and corrosive materials. The paper suggests further research is needed to develop electrodes less sensitive to moisture and oxygen, as well as paints that could completely protect the spray-painted batteries from these elements. If the latter were achieved, the engineers foresee the paints being used at a large scale in industrial environments.

Image: ZERØ/Flickr

Source: Wired.co.uk