Single-crystallization of electrolytic copper foils

• Published in: Journal of materials science & technology Vol. 176; pp. 112 - 118
• Main Authors: Li, Xingguang, Zhao, Mengze, Guo, Quanlin, Zhao, Chong, Ding, Mingchao, Zou, Dingxin, Ding, Zhiqiang, Zhang, Zhiqiang, He, Menglin, Liu, Kehai, Wu, Muhong, Zhang, Zhihong, Wang, Enge, Fu, Ying, Liu, Kaihui, Zhang, Zhibin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 20-03-2024
• Subjects: electrolytic copper foil; facet copy; grain growth; mechanical property; single-crystallization; facet copy; single-crystallization; grain growth; mechanical property; electrolytic copper foil
• ISSN: 1005-0302; 1941-1162
• DOI: 10.1016/j.jmst.2023.07.039

•Single-crystal electrolytic copper foils, with thickness up to 500 μm and facets including both low and high index ones, are first obtained through facet copy from a single-crystal template,•Crystallographic characterizations clearly visualize the facet copy process, where a seed that copy the orientation of the template first grow vertically, and then spread out.•The single-crystal electrolytic Cu foils exhibit remarkably improved mechanical properties than the original ones (elongation-to-fracture: 105% vs. 24%, average numbers of cycles to failure: 1600 vs. 200, and electrical conductivity of 102.6% of the international annealed copper standard (IACS) vs. 98.5%).
Depending on the production process, copper (Cu) foils can be classified into two types, i.e., rolled copper (r-Cu) foils and electrolytic copper (e-Cu) foils. Owing to their high electrical conductivity and ductility at low cost, e-Cu foils are employed extensively in modern industries and account for more than 98% of the Cu foil market share. However, industrial e-Cu foils have never been single-crystallized due to their high density of grain boundaries, various grain orientations and vast impurities originating from the electrochemical deposition process. Here, we report a methodology of transforming industrial e-Cu foils into single crystals by facet copy from a single-crystal template. Different facets of both low and high indices are successfully produced, and the thickness of the single crystal can reach 500 μm. Crystallographic characterizations directly recognized the single-crystal copy process, confirming the complete assimilation impact from the template. The obtained single-crystal e-Cu foils exhibit remarkably improved ductility (elongation-to-fracture of 105% vs. 25%), fatigue performance (the average numbers of cycles to failure of 1600 vs. 200) and electrical property (electrical conductivity of 102.6% of the international annealed copper standard (IACS) vs. 98.5%) than original ones. This work opens up a new avenue for the preparation of single-crystal e-Cu foils and may expand their applications in high-speed, flexible, and wearable devices.
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