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.
Corrosion resistance of metals and alloys toward liquid metals determines the service performances and lifetime of the devices using liquid metals. This paper studies the static corrosion behaviors of iron, chromium, nickel, low carbon steel, and four types of stainless steels (SS410, SS430, SS304, and SS316L) in liquid Sb-Sn at 500°C, aiming to screen corrosion-resistant stainless steel for Li||Sb-Sn liquid metal batteries (LMBs). The corrosion rates of Fe and Ni are 0.94 μm/h and 6.03 μm/h after 160 h measurement, respectively. Cr shows a low corrosion rate of < 0.05 μm/h, which is due to the formation of a relatively stable Cr-Sb layer that may be able to prevent the interdiffusion between the solid substrate and liquid Sb-Sn. Ni has a high corrosion rate because the formed Ni-Sb and Ni-Sn compounds are soluble in the liquid Sb-Sn. The corrosion products of both pure metals and SS can be predicted by thermodynamic and phase diagram analysis. Among the four types of stainless steel, SS430 shows the best corrosion resistance toward liquid Sb-Sn with a corrosion rate of 0.19 μm/h. Therefore, a liquid Sb-Sn resistant material should have a high Cr content and a low Ni content, and this principle is applicable to design metallic materials not only for LMBs but also for other devices using liquid Sb- and Sn-containing liquid metals.
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