Effect of pulse electrodeposition process on the microstructure and properties of electrolytic copper foil as anode current collectors

Abstract

• Optimizing pulsed process parameters significantly enhances the mechanical properties of copper foil. • SPS significantly improves the tensile strength of pulsed electrodeposited copper foil, reaching up to 640 MPa. • The synergistic effect of the pulsed process and SPS refines the grain structure , reduces the thickness of nano-twin lamellae, and enhances the mechanical properties of the copper foil. Developing new pulsed electrodeposition process for preparing high-strength electroplated copper foil as anode current collector for lithium-ion batteries is a highly promising research direction. This study reveals that appropriate pulsed electrodeposition process parameters, such as electrolyte temperature, current density, duty cycle and additives, can significantly enhance the tensile strength and elongation of copper foil. Under the same conditions, the mechanical properties of copper foil prepared by adding bis-(3-sulfonpropyl)-disulfide (SPS) are the most significant improvement, the tensile strength of electroplated copper foil reaches 640 MPa, while it is only 450 MPa by direct current electrodeposition. The main reason for the improvement in mechanical properties is the significant increase in the number of twins and dislocations under the combined effect of pulsed deposition and SPS, as well as the noticeable reduction in the thickness of twin lamellae and grain size. Electrolytic copper foil with a tensile strength as high as 640 MPa was prepared using the pulse electrodeposition method with a single SPS additive. The addition of SPS significantly increased the number of twins in the copper foil, reduced the thickness of the twin lamellae, and refined the grain size. The performance improvement is attributed to the SPS additive accelerating the reduction and nucleation of copper ions during the pulse electrodeposition process, limiting the expansion direction of the twins, and promoting the formation of more and smaller nanolayer twins.