Transmission electron microscopy (TEM) investigations of Mn-oxide rich cathodic material from spent disposable alkaline batteries

Transmission electron microscopy (TEM) techniques were used to investigate the spent cathodic material of a single common brand of disposable alkaline batteries. Mn-oxide particles are anhedral and irregular in shape and compose an estimated 99–95% of the <10 μm size fraction of sample material. Diameters of particles vary widely and typically are between 50 nm and 3 μm; however, most particles are approximately 200–400 nm in diameter. Chemical composition varies for Mn-oxide particles with concentrations being SiO2 (0.00–1.52 wt%), TiO2 (0.49–4.58 wt%), MnO (65.85–92.06 wt%), ZnO (1.00–7.53 wt%), K2O (4.97–20.48 wt%) and SO3 (0.43–2.21 wt%). Discrete prismatic zinc crystals occur and vary from a maximum of approximately 0.8 μm long × 0.15 μm wide, to 100 nm long × 20 nm wide. Titanium metal was also observed in samples and composes approximately 0.25–1.0% of the <10 μm size fraction of sample material. Results of this study suggest that battery components may be recycled in some special applications. Examples are low energy-low material requirement products such as paint pigments and Zn nanoparticles. This investigation provides detailed constraints on the nature of spent cathodic materials to improve existing recycling methods and develop new technologies.