Synergistic Chloride-Choline Bitartrate Strategy for Ultralight Copper Powders with Enhanced Mechanical Stability and Ultralow Apparent Density

This study developed a synergistic strategy using chloride ions (Cl⁻) and choline bitartrate (CBT) as binary additives to address the longstanding trade-off between high specific surface area and structural stability in ultralight copper powders (UCPs). Multiscale electrochemical analyses and morphological characterization revealed that the Cl⁻-CBT pair modulated copper electrodeposition kinetics via dynamic coordination and interfacial adsorption, enabling control of dendritic growth. At a Cl⁻:CBT molar ratio of 1:1, the system promoted three-dimensional instantaneous nucleation, reduced charge transfer resistance by 27.3%, and constructed a fractal dendritic architecture with balanced branch density and structural integrity. This strategy mitigated excessive dendrite thinning and structural collapse and improved mechanical robustness. Under a benchmark factory process conditions, the synthesized UCP (P-Cl-CBT) exhibited ultralow apparent density (0.41 g cm⁻³), refined median particle size (D50, 44.25 μm), and enhanced process efficiency (3.3% higher current efficiency, 5.9% lower energy consumption). In vibration testing (24 h, 2.5 Hz, 20 mm amplitude), the fractal framework retained >95% structural integrity, with negligible changes in D50 (Δ=-2.69%) and apparent density (Δ=+2.4%). Elemental and crystallographic analyses indicated negligible additive incorporation and preservation of the face-centered cubic (FCC) structure, consistent with high purity.