Rechargeable batteries now have six times more capacity, researchers build prototype

New research in the rechargeable battery sphere has resulted in an alkali metal chlorine battery that can hold up to six times more charge than today’s normal lithium ion batteries. The discovery was published on August 25, 2021. After the discovery, the research team finds itself closer to two goals: accelerating the battery to the point that electronic devices only need to be recharged once a week and making electronic vehicles that can travel six times longer without recharging.

Rechargeable batteries are based on the reaction between two chemicals and their reverse reaction. The cycle of reactions, initiated by the electric current, produces and stores charge. Stanford University chemistry professor Hongjie Dai likened it to a rocking chair. Talking about the new prototype, Dai told Stanford News: “What we have here is a high rocking rocking chair.” The round-trip reactions in the new type of battery involve the compounds sodium chloride or lithium chloride.

​​Regular disposable batteries are made of lithium and thionyl chloride and discharge energy much faster. Professor Hongjie Dai and doctoral candidate Guanzhou Zhu initially wanted to improve existing battery technologies while still using thionyl chloride. However, they soon realized that a reaction involving chlorine and sodium chloride (common salt) was showing signs of stable rechargeability.

Previous studies with chlorides often resulted in poor battery performance. This is because once a chloride turns to chlorine, it is difficult to convert it back to its chloride form efficiently.

The researchers found a solution using a positive electrode made of an advanced porous carbon material from collaborators at Taiwan’s National Chung Cheng University. Nanopores store and protect chlorine molecules when sodium chloride breaks down during charging. When the battery needs to be discharged, chlorine is used to form sodium chloride. According to Guanzhou Zhu, this cycle can be repeated up to 200 times and “there is still room for improvement.”

The researchers achieved high energy density in these batteries: 1,200 milliamperes/hour per gram of positive electrode material. In contrast to this, conventional lithium ion batteries have a capacity of only 200 milliamps/hour per gram. Therefore, the prototype has six times the capacity. The research was published in the journal Nature

These batteries, if developed in the right way, can be used in future satellites and remote controls, to guarantee the longevity of the equipment. For now, many improvements are needed to make these batteries commercially available.


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