Application of electrochemical methods in corrosion and battery research.

摘要

Various electrochemical methods have been applied in the development of corrosion protection methods for ammonia/water absorption heat pumps and the evaluation of the stability of metallic materials in Li-ion battery electrolyte.; Rare earth metal salts (REMSs) and organic inhibitors have been evaluated for corrosion protection of mild steel in the baseline solution of 5 wt% NH ₃ + 0.2 wt% NaOH to replace the conventionally used toxic chromate salt inhibitors.; Cerium nitrate provided at least comparable corrosion inhibition efficiency as dichromate in the baseline solution at 100°C. The cerium (IV) oxide formed on mild steel through the cerating process exhibited increasing corrosion protection for mild steel with prolonged exposure time in the hot baseline solution. The optimum cerating process was found to be first cerating in a solution of 2.3 g/L CeCl₃ + 4.4 wt% H₂O₂ + appropriate additives for 20 minutes at pH 2.2 at room temperature with 30 minutes solution aging prior to use, then sealing in 10% sodium (meta) silicate or sodium molybdate at 50°C for 30 minutes.; Yttrium salts provided less corrosion protection for mild steel in the baseline solution than cerium salts. Glycerophosphate was found to be a promising chromate-free organic inhibitor for mild steel; however, its thermostability in hot ammonia/water solutions has not been confirmed yet.; The stability of six metallic materials used in Li-ion batteries has been evaluated in 1M lithium hexafluorophosphate (LiPF₆) dissolved in a 1:1 volume mixture of ethylene carbonate and diethyl carbonate at 37°C in a dry-box. Aluminum is the most stable material, while Copper is active under anodic potentials and susceptible to localized corrosion and galvanic corrosion. The higher the concentration of the alloying elements Al and/or V in a titanium alloy, the higher was the stability of the titanium alloy in the battery electrolyte. 90Pt-10Ir can cause decomposition of the electrolyte resulting in a low stable potential window.