Stable Positive Current Collectors for Li||Sb–Sn Liquid Metal Batteries

The corrosion of a liquid Sb–Sn alloy on a positive current collector (PCC) can seriously affect the performance of Li||Sb–Sn liquid metal batteries (LMBs) and hinder their industrial applications. This work systematically investigated Ti, Mo, and W as the PCCs of Li||Sb–Sn LMBs corrosion behaviors and electrochemical properties. The corrosion mechanism and cell performance recession reason are illuminated based on compatibility analysis and electrochemical measurements. Ti and Mo are more easily dissolved in the liquid Sb–Sn alloy than W, forming Ti–Sb–Sn and Mo–Sb–Sn corrosion products. The average corrosion rates of Ti, Mo, and W in the liquid Sb-Sn alloy are 0.105, 0.068, and 0.014 mm/a, respectively. These corrosion behaviors not only affect the cell voltage and capacity to varying degrees but also may cause potential security liability. Hence, W is an admirably stable PCC of Li||Sb–Sn LMBs, which can also serve as an electroconductive and corrosion-resistant protective coating to reduce cost and solve the forming problem.