An international research team lead by Stanford University has invented a new form of rechargeable battery that can store 6 times the present battery, according to foreign media sources. The research will speed the use of rechargeable batteries and allow battery researchers to continue to achieve their goals in this field, which include developing a high-performance rechargeable battery that can charge mobile phones only once a week and increasing the range of electric cars six times.
Alkali metal chloride batteries are a new form of battery that has been developed. The study, conducted by Stanford University chemistry professor Hongjie Dai and Ph.D. student Guanzhou Zhu, is based on the chemical conversion of sodium chloride (Na/Cl2) or lithium chloride (Li/Cl2) back and forth to chlorine.
During the transfer of electrons from one side of a rechargeable battery to another, the chemical component is restored to its original state, ready to be used again when the battery is recharged. Not so for non-rechargeable batteries. Once they have been exhausted, their chemistry cannot be reestablished.
“A rechargeable battery is a bit like a rocking chair. It tips in one direction, but then rocks back when you add electricity,” Dai explained. “What we have here is a high-rocking rocking chair.”
On August 25, 2021, the discovery was published in the journal Nature. As a result of the discovery, the team of researchers is now closer to two goals: to accelerate battery power so that electronic gadgets will only need to be recharged once a week, and to create electric cars that can travel six times further without a recharge.
Chlorine is too reactive to be efficiently converted back into a chloride, which is why no high-performance rechargeable sodium-chlorine or lithium-chlorine battery has ever been developed. A few others were able to accomplish some level of rechargeability, but the battery performance was poor.
Batteries that are intended for one-time use are made of lithium and thionyl chloride, and they lose their energy considerably more quickly. They aimed to improve existing battery technology while using thionyl chloride. However, they soon realized that a reaction combining chlorine and sodium chloride (common salt) was showing symptoms of stable rechargeability.
Studies with chlorides in the past generally led to poor battery performance. Due to the fact that once a chloride breaks down into chlorine, it’s very hard and time-consuming to convert it back to its original chloride form.
As a solution, researchers used an improved porous carbon positive electrode developed by collaborators at the National Chung Cheng University of Taiwan (NCCU). While charging, sodium chloride breaks down and releases chlorine molecules into the nanopores, which store and preserve the chlorine molecules. In order to discharge the battery, the chlorine is converted to sodium chloride. This cycle, according to Guanzhou Zhu, can be repeated up to 200 times, and “there’s still opportunity for development.”
These batteries have a high energy density of 1,200 milliamp hours per gram of positive electrode material, according to the researchers who developed them. Conventional lithium-ion batteries, on the other hand, only have a capacity of 200 milliamp hours per gram of material. As a result, the prototype boasts a six-fold capacity increase.
Satellites and remote sensors, for example, are expected to utilize the battery in the future. Many satellites are stranded in space because their batteries have died. To make them even more useful, future satellites equipped with long-lasting rechargeable batteries can be fitted with solar chargers.
But for now, the working prototype they created may still be adequate for small common electronic items, such as hearing aids or remote controls. A lot more work needs to be done in terms of designing battery structures, boosting energy density, expanding battery scale, and maximizing the number of cycles for consumer devices or electric cars in general.
