A team of researchers from Nanjing University of Posts & Telecommunications has developed a polymer electrolyte that facilitates the rapid transport of lithium ions and promotes exceptional mechanical flexibility
The advantages of elastic lithium-ion batteries
The era of flexible electronics has officially begun. Although the first significant advances in this area date back to the 1950s, flexible electronic circuits have received the proper attention only recently. And with the growth of end applications, the need for compatible power supports has also increased. The new elastic lithium-ion battery created at Nanjing University of Posts & Telecommunications, China, is part of this research line.
This is not the first time we hear about “soft” batteries. In 2019, the Hong Kong Polytechnic University created a prototype lithium sulphur battery on fabric that could be bent over 1,000 times with a radius of curvature below a millimetre. In 2021, the University of British Columbia developed a rechargeable “rubber” for wearable electronics that could withstand even washing in water. In 2023, Hong Kong Polytechnic University scientists presented a 15% stretchable battery that still works perfectly.
From China the lithium battery that stretches by 5000%
These are just some of the results achieved over the years and partially overtaken by new Chinese research. The Nanjing University of Posts & Telecommunications team has created an electrical storage device that can be stretched by 5,000%. And can maintain its capacity after almost 70 loading/discharge cycles.
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The secret to success? The approach. Instead of integrating the different components into a flexible base, scientists have made the same elastic.
“So far, prototypes of truly elastic batteries have shown moderate elasticity, complex assembly processes or limited energy storage capacity, especially over time with repeated loads and discharges,” the press release published by the American Chemical Society states. “The latter may be due to a weak connection between the electrolytic layer and the electrodes or to the instability of the fluid electrolyte, which can move when the battery changes shape. So, instead of using a liquid, Wen-Yong Lai and his colleagues wanted to incorporate the electrolyte into a polymer layer melted between two flexible electrode films to create an excellent and elastic battery.”
A new recipe for electrochemical accumulation
The two electrodes were created from a thin conductive paste film containing silver nanowires, black coal and lithium-based cathode or anode materials. A layer of polydimethylsiloxane, a silicone commonly used in contact lenses, was then applied to the film. So, a lithium salt, a highly conductive liquid and the ingredients were added to create an elastic polymer. “When activated by light, these components combine to form a solid, rubber layer that can stretch up to 5000% of its original length and carry lithium ions. Finally, the battery was covered with another film of electrodes and the entire device was sealed in a protective coating.”
The research is only at the beginning, and the authors believe that there are resolute improvements, but the first results appear already interesting. The new elastic lithium-ion battery hastened its initial capacity for 67 charging and discharge cycles.
The research was published in ACS Energy Letters.
