Effect of manufacturing conditions on the electrochemical properties of Mg-9%Al-3%Ca alloy ribbons for magnesium batteries using the single-roll rapid solidification method

In recent years, there has been much anticipation for the development of large-capacity rechargeable batteries as a power source for automobiles and other transportation equipment. Our research team is developing battery materials and establishing manufacturing conditions for ribbons using a single-roll rapid solidification method. In this study, we investigated the characteristics of magnesium batteries by evaluating the electrochemical properties of ribbons produced in a previous report and observing their surface structure after charging and discharging. As a result, an increase in overvoltage and current density was observed with increasing roll peripheral speed during CV measurement. This is thought to be due to the increase in cooling rate and the crystal orientation becoming basal-oriented as roll peripheral speed rises. SEM observation of the ribbon surface after electrochemical activation revealed dissolution grooves corresponding to charge-discharge cycles. After discharge, the ribbon surface retained a second phase with a network structure composed of Mg2Ca (C14), Al2Ca (C15) and (Mg, Al) 2Ca (C36), and it was confirmed that α -Mg was preferentially dissolved. Furthermore, after charging, magnesium ions migrated from the positive electrode to the negative electrode, but some did not fully return to the network-like cell interior and instead accumulated on the upper part of the porous layer.