A novel strategy to electrodeposit high-quality copper foils using composite additive and pulse superimposed on direct current

Abstract

As a crucial material for fabrication of lithium-ion battery current collector, the properties of electrodeposited copper foil are closely related to the battery performances. How to improve its properties is thus of great importance for battery design and manufacturing. In this paper, we reported a novel composite additive, consisting of collagen, glycerol, hydroxyethyl cellulose, and sodium polydisulfide dipropane sulfonate, for electrodeposition of high-quality copper foil from conventional acid copper sulfate bath. Meanwhile, a pulse superimposed on direct current was used during the preparation process of copper foil. It was demonstrated that the additive could improve the foil’s performances, through changing the kinetic parameters of copper electrodeposition in sulfate bath. The optimized bath has a higher allowable current density during superimposed current electrodeposition, in contrast to the situation in direct current electrodeposition. This may then lead to an increase in deposition rate of copper foil, and a further improvement in surface roughness, grain size, residual stress, as well as elongation. Specially, the superimposed current offers a number of adjustable parameters for modulating copper foil’s properties in a wide range.