The storage behavior of active material from lithium-ion battery recycling was investigated in this master's thesis. For this reason, the storage behaviour of active material was investigated as part of this master's thesis and possible causes for solidification were sought. Hypotheses based on literature were formulated and tested experimentally. The focus was on four active materials: PSP (internal designation of the project partners), Lithium-nickel-manganese-cobalt-oxide (NMC), HL (internal designation of the project partners) and Lithium-iron-phosphate (LFP). The composition of the active material was analyzed using mass spectrometer (MS) screening, atom emission spectroscopy and X-ray fluorescence analysis (XRF). An X-ray diffraction (XRD) analysis was carried out to clarify the crystal phases of the different materials. A wide variety of tests and investigations were carried out on the storage behaviour of active material. The samples were stored for 50 days in St. Michael in the Digital Waste Research Lab of the Chair of Waste Processing Technology and Waste Management for a long-term outdoor test under a shed roof. The humidity during storage was not sufficient for solidification. Solidification tests showed that three out of four samples reacted with deionized water and formed porous, easily breakable lumps. The hardness of the reacted samples is below 1 on the Mohr hardness scale, as the reacted samples were too unstable for testing. A pH value measurement of the active material mixed with deionized water showed no significant change. When measuring the conductivity of the mixture, an increase in specific conductivity was observed, except for the LFP active material. A white crystalline substance was found at the edge of the samples after the reaction with deionized water. The white crystalline substance was analyzed qualitatively with an XRF handheld, and it was found that the substance contained bromine (Br). Furthermore, it is assumed that these are NaBr and/or CaBr2.