The main purpose of the study is to investigate the battery properties behind the electrical and magnetic properties. The first part of the study is about the fabrication of Cr-doped Na0.67Fe0.5Mn0.5O2 and the structural properties of the powders, which were investigated by XRD, EXAFS, FTIR and Raman Spectroscopy. Temperature-dependent resistivity measurements showed that room temperature resistivity values increased with Cr-ion content and all samples show an exponential decrease with increasing temperature. The magnetic properties of the Cr-doped samples were investigated, and it was found that the Cr ions strongly affected the magnetic structure of the samples. The second part of the study is about battery performance using the samples as cathode materials. Hence, CR2032 coin cells were fabricated by using the Cr-doped samples and the CV measurements showed that a high level doping of Cr ions in the structure prevented Na diffusion in the cells. The obtained CV graphs were discussed from the viewpoint of lattice dynamics. The EIS and cycling properties showed that Cr-ions in Na0.67Fe0.5Mn0.5O2 decrease of the capacity fade of the cells.