The vastly increasing material demand for the production of EV batteries and energy storage systems as well as the new EU regulatory framework for battery material recycling quotas has led to an increasing interest in the use of recycled materials in the battery production. The development of sustainable material concepts for battery production has therefore gained significant importance. This is particularly evident in the case of cathode active materials due to the limited availability of valuable metals required for the production. Nickel-rich layered oxides, among others, have attracted considerable interest as cathode active materials due to their high usable capacity. Their significant potential for next generation batteries, as well as their potential negative environmental impact, makes effective recycling and resynthesis strategies highly attractive. The aim is to convert cathode active materials from spent batteries into metal salts (e.g. nickel sulphate), enabling the resynthesis of cathode active materials with comparable electrochemical performance to materials synthesized from primary metal salts.
The objective of this study was to investigate the impact of different material sources on the synthesis process and the product in order to establish a process that is robust to impurities in the starting materials. Metal sulfates (nickel sulphate, cobalt sulphate, manganese sulphates) from two primary and two recycled sources were used as educts for the synthesis of lithium nickel manganese cobalt oxides (NCM622). The cathode active material is produced through a three-stage process. First, the hydroxide precursor is synthesized by co-precipitation. The precursor is then washed and dried. In the final stage, the precursor is lithiated, calcinated, and crushed to obtain the cathode active material. The synthesized precursor and cathode active material were analyzed regarding their morphology (SEM), material composition (ICP-OES), particle size (laser diffraction) and crystallinity (XRD). It was found, that cathode active materials synthesized from the recycled educts exhibit similar characteristics as those from primary educts. The targeted crystal structure and stoichiometry was achieved with all materials. This shows, that the selected process is robust against minor impurities and can be used to synthesize cathode active materials from recycled sources.