An environmentally degradable battery could make electronic devices, land and air vehicles safer and alleviate the difficulties associated with e-waste disposal.
Today, the vast majority of batteries still contain materials that continue to pose environmental problems when they reach the end of their useful life. Researchers at Nanyang Technological University (NTU) in Singapore recently successfully tested a prototype of a new type of battery that is not only extremely simple in design, but also easy to manufacture and, once discharged, can be broken down by micro-organisms in the soil within a month.
The battery has a sandwich structure: a sheet of cellulose in the middle, reinforced with hydrogel to fill the gaps between the fibres and thus completely insulate the two electrodes from each other. The electrodes are screen-printed on both sides of this 0.4 mm thick sheet of cellulose. The material for printing the anode is made from zinc and carbon black, while the cathode can be made from manganese or nickel, depending on the two different prototypes. After the printing phase is completed, the battery is immersed in an electrolyte solution and then the electrodes are coated with a thin layer of gold to increase their conductivity. The researchers say that metals other than manganese and zinc could also be suitable as cathodes.
Using the current prototype of the paper-based battery, which measures 4×4 centimetres, the Singapore researchers have managed to operate a small electric fan for 45 minutes, and tests show that the power source can run continuously without any failure and with unchanged output power even if it is twisted, bent or even a piece is cut off.
“We believe that the paper battery we have developed has the potential to help solve the problems associated with electronic waste, as our printed paper battery is non-toxic and requires no aluminium or plastic casing for any of its components. The avoidance of packaging layers also allows our battery to store more energy within a smaller system,” summarized Lee Seok Woo, an assistant professor at Nanyang Technological University, who is one of the leaders of the research and one of the co-authors of the summary study.
The Singaporean innovation could usher in a whole new way of battery production: a technology that would make it possible to create smaller batteries of the right capacity, size and shape from a single large battery plate by simply slicing and dicing, without compromising efficiency.