Rechargeable alkaline Zn–Cu batteries enabled by carbon coated Cu/Bi particles

In this work, we demonstrate using Cu as the cathode active material in alkaline Zn batteries by forming nanoscale carbon coated Cu/Bi particles through the carbonization of dopamine coated CuO/Bi2O3. The resulting particles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), elemental analysis (EA), and Raman spectroscopy. The carbon coating was found to be roughly 20 nm thick with a mass loading of ∼8 wt%. When cycled versus pasted Zn anodes, the Cu/Bi@C cathodes provided 200 cycles at ∼300 mAh/g and ∼100 Wh/L. SEM, EDS, XRD, and optical images were used to track changes in the electrode structure and morphology over the first 50 cycles. Solubility of Cu and Bi species was found to decrease the capacity during the first 10 cycles, followed by minimal losses thereafter. The carbon coating enables consistent cycling performance and prevents the formation of detrimental Cu2O structures found in passivated Zn/CuO batteries. This work exemplifies the benefits of nanoscale carbon coatings for Cu particles providing further insight into methods for realizing a Cu based cathode for rechargeable alkaline Zn batteries.