Direct recycling of lithium iron phosphate batteries "DiLiRec"

The recycling of lithium-ion batteries and production waste is a key factor in securing the future supply of raw materials and thus Germany's technological sovereignty. Activities to date have largely focused on the recovery of nickel and cobalt from NCM and NCA cathode materials. In contrast, the joint project "DiLiRec" is developing sustainable recycling processes for the cathode material lithium iron phosphate (LFP) on the basis of optimized black mass extraction. The LFP cathodes of large-format round cells in particular offer high recycling potential.

With the help of efficient battery cell sorting, dismantling and electrode stripping as well as systematic recording of material and process data in the battery recycling sub-processes, the prerequisites for cost-effective LFP recycling are created. In addition, artificial intelligence (AI) controls the semantic data acquisition and supports the entire design of the process chain in terms of economic efficiency.

In the joint project "DiLiRec", two methods for recovering lithium iron phosphate from cylindrical cells are being investigated. In direct recycling, the aim is to fully recover the LFP as an active material and reuse it in processed form. In the standard recycling process, precursors of the LFP synthesis are to be isolated and used as secondary raw materials. In contrast to other battery cell chemistries such as NCM and NCA, less complex and energy-intensive hydrometallurgical steps can be used to recover the lithium from LFP. Futhermore, direct recycling of LFP appears promising due to its material properties.

One focus of Fraunhofer IKTS in the project is on defining the requirements for the black mass and the possible recyclates in terms of their purity and properties. In addition, Fraunhofer IKTS uses its extensive expertise in the field of characterization to chemically and morphologically investigate recyclates, black mass and by-products from hydrometallurgical and mechanical processing. In order to determine the influence of possible impurities on electrochemical performance, both established methods – ICP-OES, XRF, XRD and SEM-EDX – as well as electrochemical methods. With knowledge of tolerable contaminations, upstream processes can be adapted in terms of energy and material use if necessary.

Furthermore, IKTS will carry out a technology comparison for the different process routes. The material data collected will be used to balance material and energy flows and the environmental impact of the various recycling scenarios will be ecologically assessed (life cycle assessment, LCI, LCA). In addition, IKTS identifies and evaluates recycling options for by-product streams, such as iron(III) phosphate, so that as little material as possible is removed from the material cycle and thus contributes to a circular economy.