Is rhubarb a miracle technology to recycle batteries?

Scientists from Chalmers University in Gothenburg have developed a breakthrough method for recycling used battery packs, not by complex and dangerous chemical additives but by activating a substance found in rhubarb, white beans, or paprika. The researchers have ties with Volvo and Northvolt.

“Until now, no one has succeeded in finding the right formula for recycling these high rates of lithium and separating the aluminum component,” says the press release from Chalmers University.

The new and effective method applied by the researchers uses oxalic acid and makes it possible to recuperate 98% of the lithium from the discarded battery and 100% of the used aluminum. Another benefit is that the losses of cobalt, nickel, and manganese are minimal.

Bottlenecks

Martina Petranikova, head of the innovative research project, clarifies the obstacles of conventional recycling methods, which rely on chemicals dangerous to the environment. On top of that, “one of the bottlenecks is to get rid of residual material like aluminum,” she adds. The newly discovered method offers an alternative with higher performance and a lower ecological impact.

In the traditional process, hydrometallurgy, the battery cells are dropped in an inorganic acid from which the impurities, like aluminum and copper, are extracted in several phases. These intermediate steps cause spillage while losing a fraction of the precious lithium bit by bit – roughly 17%.

 By inverting this traditional process, the Swedish researchers first separated the lithium and aluminum from the other materials. It’s still hydrometallurgy, but as the active material oxalic acid is found in vegetables, it has a significantly lower ecological footprint, while the share of aluminum is fully recuperated. It’s also cheaper.

‘Easy to scale up’

The whole process looks like brewing coffee. The first separation phase is a filtration process that leaves a liquid containing aluminum and lithium on the one hand and the other rare metals in a pulverized form on the other. In the final step, the lithium is isolated from the aluminum. The procedure looks a lot like cooking but is unique and unprecedented.

“This method can easily be scaled up,” adds Petranikova, “so we think it will be put to good use in the industry in the forthcoming years.” The research department of Chalmers University runs joint development programs with both automaker Volvo and battery manufacturer Northvolt.