Researchers create cathodes for safer and more energy-dense lithium-ion batteries

Scientists from the US military state that they can make safer and more energy-dense lithium-ion batteries based on a different chemical composition of the cathodes. In this case, aqueous electrolyte and no transition metals such as cobalt or nickel are used.

In contrast to regular lithium-ion batteries, the invention is based on an aqueous electrolyte, in which a salt solution is used. This is inherently safer than the liquid electrolytes of regular lithium-ion batteries, which use lithium salt in a solution. Because of this water base there is no risk of ignition or explosion, but traditionally there is, among other things, the disadvantage of a less high energy density. The researchers have now eliminated the latter with a specific chemical composition of the cathodes, which combines the safety advantage of aqueous electrolytes with a high energy density.

The different chemical composition of the cathodes uses the redox reactions of halogens to store charges, in this case bromine and chlorine. Of these elements, their property is used to stabilize the oxidation products in the layered structure of the graphite. In this way a highly concentrated composition is achieved, which is not only very reversible but also leads to a high energy density.

According to the researchers, this provides excellent charge stability and an energy density of 460Wh/kg, which is in fact the total mass of the cathode and anode. They state that this is at least in line with the best regular lithium-ion batteries that use combustible electrolytes and transition metals in the cathodes. According to the scientists, it is about a 25 percent higher energy density compared to that of normal smartphone batteries.

The scientists describe that soldiers, who still have to carry many kilos of batteries, can, based on their invention, be able to take much lighter batteries with them that are also safer. It could also provide better batteries for consumer electronics and electric cars, they say, not only from an energy density and safety point of view, but also because of the absence of toxic and sometimes expensive transition metals, such as nickel and cobalt.

Professor Jeff Dahn and a specialist in battery technology, who is quoted in the scientists’ report, says that it remains to be seen whether it will be possible to develop sustainable, commercial battery cells based on the technology, but he nevertheless states that he is “very enthusiastic about this research’. The researchers acknowledge that in any case more research is needed to scale up the invention in order to arrive at actually usable batteries that can be produced on a large scale.