| ZHANG Liuyan,HAO Xiaoyu,WANG Yang,YANG Ying,GU Hongtao,CHU Songchao,WU Junwei,ZHEN Jun.Microstructure and Performance Regulation of Cu Seed Layer by Magnetron Sputtering for Composite Current Collector Used in Lithium Battery[J],54(10):1-12 |
| Microstructure and Performance Regulation of Cu Seed Layer by Magnetron Sputtering for Composite Current Collector Used in Lithium Battery |
| Received:January 22, 2025 Revised:April 27, 2025 |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2025.10.001 |
| KeyWord:composite current collectors magnetron sputtering Cu seed layer electrical properties adhesion |
| Author | Institution |
| ZHANG Liuyan |
Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials,School of Materials Science and Engineering, Anhui University of Technology, Anhui Ma'anshan , China |
| HAO Xiaoyu |
Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials,School of Materials Science and Engineering, Anhui University of Technology, Anhui Ma'anshan , China |
| WANG Yang |
Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials,School of Materials Science and Engineering, Anhui University of Technology, Anhui Ma'anshan , China |
| YANG Ying |
Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials,School of Materials Science and Engineering, Anhui University of Technology, Anhui Ma'anshan , China |
| GU Hongtao |
Anhui Tongfeng Electronics Co., Ltd., Anhui Tongling , China |
| CHU Songchao |
Anhui Tongfeng Electronics Co., Ltd., Anhui Tongling , China |
| WU Junwei |
Jiangsu Yinglian Composite Collector Co., Ltd., Jiangsu Yangzhou , China |
| ZHEN Jun |
Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials,School of Materials Science and Engineering, Anhui University of Technology, Anhui Ma'anshan , China |
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| Abstract: |
| In this work, nanoscale Cu seed layers were deposited on PP substrates by DC magnetron sputtering technique, aiming to solve the conductivity and bonding issues of composite Cu foils applied in current collectors for lithium-ion batteries. Cu films with low resistivity and favorable adhesion performance were obtained by regulating process parameters such as substrate temperature, gas flow, sputtering power, etc. The surface morphology of Cu films was analyzed by field emission scanning electron microscope (FESEM). The four point probe meter was employed to test the film square resistance, and the resistivity was subsequently calculated. The adhesion strength was qualitatively assessed based on the cross-cut test method. With the increase of the substrate temperature, the grain sizes of the films increased, followed by the decrease of the film resistivity as well as adhesion strength. As the gas flow increased, the deposition rate initially increased and then decreased. Under low-pressure conditions, black spots appeared on the film surface. EDS analysis indicated that these black spots were not surface oxides, but rather the result of the film being too thin and incomplete island-to-island connectivity. The resistivity showed a trend of initially decreasing and then increasing, which was attributed to the presence of these microscopic defects that enhanced electron scattering within the film. Therefore, copper films deposited under low-pressure conditions typically exhibited higher resistivity, while the adhesion strength between the film and the substrate gradually improved. As the sputtering power (1, 1.5, 2, and 2.5 kW) increased, the deposition rate of the film significantly increased. The XRD results for the 2.5 kW showed only a weak Cu (111) diffraction peak, indicating that the Cu (111) plane with the lowest surface energy, preferentially grew during the early stages of film formation. At sputtering powers of 1 kW and 1.5 kW, micro-pores and cracks appeared on the surfaces of Cu films deposited on Si and PP substrates, respectively. By adjusting the deposition time for the 1 kW and 1.5 kW samples, the surface became smooth when the film thickness reached approximately 80 nm, and the observed micro-pores or cracks were attributed to insufficient film thickness. A comparison of the cross-hatch test results for Cu films of the same thickness but under different sputtering powers revealed that as the power increased, the adhesion strength between the film and the substrate decreased. Based on the microstructure, electrical and bonding properties of Cu seed layers, the optimal deposition parameters were found as follows:substrate temperature of −15 ℃, gas flow (pressure) of 400 mL/min (0.24 Pa), sputtering power of 1.5 kW, and Cu thickness of approximately 80 nm. Under the above deposition conditions, the Cu film exhibited a dense microstructure, and the resistivity was as low as 9.72×10−8 Ω.m. Besides, the bonding strength was rated as level 1. The microstructure and properties of Cu films were significantly affected by the substrate temperature, gas flow as well as sputtering power. Hence, the Cu seed layers for composite current collectors could be obtained by regulating deposition process with excellent performance. |
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