Scientists Develop New Flexible Lithium-ion Batteries That Can Be Cut Without Igniting

- Nov 15, 2019-

According to foreign media reports, a group of researchers at the Johns Hopkins Applied Physics Laboratory designed a flexible lithium-ion battery that was cut, immersed, and simulated by ballistic impact. The battery works fine under extreme conditions, and now the battery won't catch fire.

Current lithium-ion batteries are made of flammable and combustible materials, and are prone to catastrophic fires and explosions, most of which occur suddenly without any discernable warnings. Due to the danger, the Samsung Galaxy Note7 mobile phone is banned from use on the aircraft. The Navy also prohibits the use of electronic cigarettes on ships and submarines to mitigate the danger of such flammable equipment.

As such batteries have become the preferred energy storage tool for applications such as portable electronics, electric vehicles and grid storage, increasing their safety will mark a major shift in the way lithium-ion batteries are produced and used.

Recently, in the journal Chemical Communications, a research team led by Konstantinos Gerasopoulos of the APL Research and Exploration and Development Department announced the discovery of a new type of water-in-salt (WiS) and water-in-bisalt (WiBS) electrolytes. When combined with a polymer matrix, it can reduce water activity, increase battery energy, extend its life cycle, and eliminate flammable, toxic, and highly active solvents in current lithium-ion batteries. The researchers say the electrolyte is a safe and powerful alternative.

Gersopoulos, senior research scientist and principal researcher at APL, said: "From mobile phones to automobiles, lithium-ion batteries have become a common commodity in everyday life. Continued improvement of its safety is essential to further promote the development of energy storage technology. Since the 1990s At the beginning, since the commercialization of lithium-ion batteries, the shape factor has not changed much. We still use the same cylindrical or diamond-shaped battery cells, in which the liquid electrolyte and the required sealed package have such a large shape. relationship."

“Our research team is working to replace flammable liquid electrolytes with a polymer with improved safety and form factor, and recent papers show that water-based flexible polymer lithium-ion batteries can be manufactured and operated in open air. And its usability and performance have improved."

In the new study, the team overcame the limitations of liquid WiBS electrolytes. Liquid WiBS electrolytes are inherently safe due to the presence of water, but their energy is limited and is not compatible with most commercial anode materials. Researchers have developed "stable, WiBS-based aqueous gel polymer electrolytes (GPEs). In the presence of WiBS, researchers have made UV-mediated polymerization of water-soluble acrylates to make such electrolytes."

Scientists have shown that the UV curing process and the integration of WiBS in the polymer improve the retention of free water, which is coordinated by the polymer to enhance its electrochemical stability. "We have demonstrated for the first time that low-cost anode nano-scale lithium titanate (Li4Ti5O12, LTO), which is widely used on the market, can be used in water-based polymer lithium-ion batteries and can be reliably cycled more than 100 times," the researchers said.

In 2017, researchers developed a breakthrough flexible battery, and the new polymer electrolyte developed this time further enhances the damage tolerance of this battery.

Gerasopoulos said: "The first generation of flexible batteries is not as stable in size as the batteries we now manufacture. The UV-cured polymer we developed is an independent, mechanically strong film similar to contact lenses. These batteries are completely exposed. In the air, you can work for a few days in a row. You can burn, cut, or otherwise put pressure on them, and they will still work."

“We have successfully improved the mechanical strength and electrochemical stability of GPE and are able to transition this new supersaturated hydrogel polymer electrolyte (GPE) from proof of concept to practical application.”

Jeff Maranchi, regional director of APL Materials Science, said: "Our team is constantly improving the safety and performance of flexible lithium-ion batteries, and we hope to turn this new research into a prototype within a year."