Synthesis and Characterization of Copper Dendritic Structures Obtained by Electrocrystallization at High Current Density

Dendritic copper structures were synthesized by electrocrystallization from a sulfate electrolyte (0.31 M CuSO₄ + 1.53 M H₂SO₄) at a high cathode current density of 20 A/dm² under conditions of concurrent hydrogen evolution. The obtained deposits are approximately 200 μm in thickness. The multilevel void architecture of the dendritic copper was characterized using scanning electron microscopy combined with image processing and statistical analysis. Interdendritic voids were approximated by area-equivalent fitted ellipses, enabling quantitative assessment of pore size distributions. Analysis by quantity revealed three distinct void populations with peak maxima at 2.41 μm, 5.06 μm, and 10.93 μm, accounting for 23%, 34%, and 42% of voids, respectively. Area-weighted analysis identified four void populations with peak maxima at 15.9 μm, 33.4 μm, 46.0 μm, and 72.2 μm, contributing 54%, 16%, 19%, and 4% of the total void area. The estimated pore density was 2529 pores/mm², the total void area fraction was found to be 0.3054, with an average void area of 108.46 μm² corresponding to an effective diameter of 11.75 μm. A distinct category of through-pores was identified, defined as voids with an effective diameter ≥ 20 μm through which the underlying substrate surface becomes visible in SEM images. These through-pores, formed by the coalescence of hydrogen bubbles generated during the hydrogen evolution reaction, occupy approximately 39% of the total void area and provide significantly enhanced filtration and diffusion characteristics compared to smaller pores. The hierarchical void structure, combining numerous small pores for high surface area with larger interconnected channels for efficient transport, makes these dendritic copper films promising candidates for application as current collectors in lithium-ion batteries.