Lee Yoon-Seok, Park Jinyong, Ok Jung-Woo, Kim Seongjun, Shin Byung-Hyun, Yoon Jang-Hee
Semiconductor-Specialized University, Pusan National University, Busan 46241, Republic of Korea.
Busan Center, Korea Basic Science Institute, Busan 46742, Republic of Korea.
Materials (Basel). 2024 Aug 19;17(16):4107. doi: 10.3390/ma17164107.
Lithium-ion batteries are superior energy storage devices that are widely utilized in various fields, from electric cars to small portable electric devices. However, their susceptibility to thermal runaway necessitates improvements in battery case materials to improve their safety. This study used electrochemical analyses, including open-circuit potential (OCP), potentiodynamic polarization, and critical pitting temperature (CPT) analyses, to investigate the corrosion resistance of super duplex stainless steel (SAF 2507) applied to battery cases in relation to post-weld heat treatment (PWHT) time. The microstructure during the manufacture, laser welding, and PWHT was analyzed using field-emission scanning electron microscopy, X-ray diffraction, and electron backscatter diffraction, and the chemical composition was analyzed using dispersive X-ray spectroscopy and electron probe micro-analysis. The PWHT increased the volume fraction of austenite from 5% to 50% over 3 min at 1200 °C; this increased the OCP from -0.21 V to +0.03 V, and increased the CPT from 56 °C to 73 °C. The PWHT effectively improved the corrosion resistance, laying the groundwork for utilizing SAF 2507 in battery case materials. But the alloy segregation and heterogeneous grain morphology after PWHT needs improvement.
锂离子电池是性能卓越的储能装置，广泛应用于从电动汽车到小型便携式电子设备等各个领域。然而，它们易发生热失控，因此需要改进电池外壳材料以提高其安全性。本研究采用包括开路电位（OCP）、动电位极化和临界点蚀温度（CPT）分析在内的电化学分析方法，研究应用于电池外壳的超级双相不锈钢（SAF 2507）相对于焊后热处理（PWHT）时间的耐腐蚀性。使用场发射扫描电子显微镜、X射线衍射和电子背散射衍射分析制造、激光焊接和PWHT过程中的微观结构，并使用能量色散X射线光谱和电子探针微分析来分析化学成分。在1200℃下，PWHT在3分钟内将奥氏体的体积分数从5%提高到50%；这使OCP从-0.21V提高到+0.03V，并使CPT从56℃提高到73℃。PWHT有效地提高了耐腐蚀性，为在电池外壳材料中使用SAF 2507奠定了基础。但PWHT后的合金偏析和不均匀晶粒形态需要改进。
