Copper Foil Chips (D=10-16 mm, T = 4-15 um) as Anode-Free Battery Current Collector, 100 pcs/bag, CAFBCCCFC

Copper foil chips (precision-punched or cut discs, squares, or custom geometric pieces of copper foil) are widely used in laboratory-scale and small-format prototyping—such as coin cells, Swagelok cells, and custom test fixtures—for anode-free (zero-excess) battery configurations. In an anode-free system, there is no active anode material on the negative electrode during assembly. Instead, the copper foil chip serves as the bare current collector substrate onto which alkali metal (Li, Na, or Zn) electroplates directly from the electrolyte during the initial charging cycle.

The critical engineering factors for foil chips in anode-free cells are: (1) Danger of Edge Burrs (Mechanical Punching Defects): When copper foil chips are mechanically punched using standard die cutters, the shearing action often leaves microscopic, razor-sharp burrs or rolling lips along the perimeter. In standard lithium-ion batteries with thick graphite anodes, these minor edge defects are easily buffered. However, in anode-free configurations, these sharp burrs act as severe electric field hotspots, causing intense local current concentration and triggering immediate dendritic short-circuiting during initial metal plating. (2) Surface Oxidation and Native Contaminants: Raw copper foils naturally develop a passive cuprous/cupric oxide (Cu2O/CuO) layer and carry residual rolling oils.These surface contaminants increase interfacial resistance and alter the initial nucleation overpotential, leading to non-uniform, patchy metal deposition rather than smooth, planar plating. (3) Interfacial Wettability and Nucleation Barriers: Bare copper has a high lattice mismatch and interfacial energy with certain plated metals, which can encourage 3D island growth (Volmer-Weber mechanism) and dendrite formation rather than uniform 2D layer-by-layer growth.

References: 

1. Y. Shen, et al. Homogenized Current Collector Surface for High Reversibility Anode-Free Zinc Metal Batteries, Adv. Funct. Mater., 2025, 35, 2504042
2. Y. Chen, et al. Grain-Optimized Copper Current Collectors for Highly Stable Anode-Free Sodium Batteries, 2026, 38, e22541
3. J. Feng, et al., A cross-scale collaborative design of copper current collectors for practical anode-free lithium metal batteries, EES Batteries (2026) 2 (2): 425–445.