Mn_3O_4/carbon nanotube nanocomposites recycled from waste alkaline Zn–MnO_2 batteries as high-performance energy materials

Alkaline zinc manganese dioxide (Zn–MnO_2) batteries are widely used in everyday life. Recycling of waste alkaline Zn–MnO_2 batteries has always been a hot environmental concern. In this study, a simple and costeffective process for synthesizing Mn_3O_4/carbon nanotube (CNT) nanocomposites from recycled alkaline Zn–MnO_2 batteries is presented. Manganese oxide was recovered from spent Zn–MnO_2 battery cathodes. The Mn_3O_4/CNT nanocomposites were produced by ball milling the recovered manganese oxide in a commercial multi-wall carbon nanotubes (MWCNTs) solution. Scanning electron microscopy (SEM) analysis demonstrates that the nanocomposite has a unique three-dimensional (3D) bird nest structure. Mn_3O_4 nanoparticles are homogeneously distributed on MWCNT framework. Mn_3O_4/CNT nanocomposites were evaluated as an anode material for lithium-ion batteries, exhibiting a highly reversible specific capacitance of *580 mAh·g~(-1) after 100 cycles. Moreover, Mn_3O_4/CNT nanocomposite also shows a fairly positive onset potential of -0.15 V and quite high oxygen reducibility when considered as an electrocatalyst for oxygen reduction reaction.