Duesenfeld system targets battery cell scrap

German recycling technology developer Duesenfeld is offering a system for recycling lithium-ion batteries it says creates not only marketable metals but also supplies marketable graphite and electrolytes.

“Our focus is on recycling the batteries as completely as possible,” the research and technology licensing company saysing, adding it has achieved a recycling rate of 72 percent of lithium-ion battery materials in its mechanical recycling stage.

Following that, the creation of Duesenfeld Black during its hydrometallurgical step increases the material recycling rate to 91, according to the company.

“Only the separator film and the high boiler portion of the electrolyte are not recovered at the moment,” its says of the three-stage process it is offering to the battery recycling and production sector.

Duesenfeld combines mechanical, thermodynamic and hydrometallurgical processes in its patented process, which starts with the discharging of end-of-life batteries. According to the company, the process achieves the highest material recovery rates with low energy consumption while avoiding pollutants.

Those outcomes are made possible by a process with low temperatures in which toxic hydrogen fluorides are not produced, according to Duesenfeld.

The firm also says exhaust gas scrubbing is not necessary in its mechanical processing step and that fluorides are removed in a targeted and safe manner during the hydrometallurgy stage.

Duesenfeld's definition of recycling does not include uses such as in paving materials, but says all metals are recovered with high recovery rates in the form of high-quality secondary raw materials up to battery quality.

The company's process starts with a patented “deep discharge” technique for end-of-life lithium-ion batteries, and the recovery of the embedded energy.

Duesenfeld calls the mechanical recycling stage “a demanding task” in part because of the flammable nature of lithium-ion batteries and contained ingredients.

"[After disassembly,] the batteries are comminuted under an inert gas atmosphere and the solvent of the electrolyte is recovered from the comminuted material by vacuum distillation,” Duesenfeld says of its process. The resulting used solvent can be sent to chemical industry customers for further processing.

Shredded dry electrode scrap generated by battery cell production can be taken to a sorting stage where the material is separated into different fractions on the basis of physical properties such as grain size, density and magnetic and electrical properties, and then they are further processed metallurgically.

The resulting iron, copper and aluminum fractions are sold to established markets while the Duesenfeld Black (black mass), which contains the electrode active materials and the conductive salt, head toward the hydrometallurgical process developed by Duesenfeld. During that process, cobalt, lithium, nickel, manganese and graphite are recovered from the mixed material.

In a pilot project, Duesenfeld says a recycling rate of more than 90  was achieved for an industrial nickel manganese cobalt (NMC) cathode scrap stream, with what it calls an extremely low fraction of aluminum impurities.

The firm says laboratory testing has shown that cells with 26 percent recycled content were certified as having a performance comparable to that of reference (primary materials) cells.