The need to recycle critical materials from spent lithium-ion batteries is undisputed. However, non-critical and currently low-cost elements such as manganese are often neglected. Looking at the development of this technology, however, it is evident that the demand for high-purity manganese for battery production will also increase enormously. The tendency towards active materials with higher manganese contents leads to the conclusion that this element should already be taken into consideration at this stage of the development of recycling processes. This evolution is based on the lower costs per kWh for the active material used and is therefore a highly probable scenario, especially with regard to the cost situation for battery materials. The recovery of manganese from active materials has so far been carried out in the research work mainly by means of solvent extraction, whereby this process entails many technological prerequisites in addition to the high price of the technique itself. When classical precipitation methods using sodium hydroxide or carbonate were used alternatively, only an inconsistent product with a high content of impurities could be obtained. This research work therefore deals with the selective recovery of manganese by means of photocatalytic oxidation. It makes utilization of the natural oxidation cycle of manganese, which is strongly dependent on the pH value, and shows that the efficiencies of this process are quite promising for the application in the field of battery recycling.