Electrochemical Performance of SiC Composite Anode in Aluminum-Air Battery

The commercial pure aluminum (1A95) and its micro-alloyed with Mg and further particle composited with SiC were prepared using the vortex casting method, their electrochemical performances as the anodes in Aluminum-air batteries were investigated using open-circuit potential (OCP), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and galvanostatic discharge. The results indicate that Al-Mg/SiC composite anode shows much better corrosion resistance and discharge performance than others. Impedance spectra and surface observation show that SiC addition obviously changed the anode dissolution morphology, which means that the SiC particles serve as attachment points for hydroxide products and impurities and reduce the parasitic corrosion reactions. As SiC particles fall off the substrate, SiC shedding disrupts the Al(OH)3 film, reducing the accumulation of hydrogen molecules on the pore surface, the more fresh surface is exposed, which promoted the corrosive effect of the anode. So, the Al-Mg/SiC composite anode has higher electrochemical activity and the open-circuit potential shifts more negatively. Even though the shedding of SiC particles might cause a relatively higher rate of dissolution during the spontaneous oxide growth/oxide dissolution process, the formation of MgAl2O4 cladding SiC particles reduces the Al/SiC interface energy, lowers corrosion rate and improves the composite anode efficiency and capacity density.