Controllable Electroless Deposition and Physicochemical Properties of 1 μm Copper Coating on Inert PI Film

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Conventional electrolytic copper foil is a standard current collector in lithium-ion batteries (LIBs).
• There is a need for lightweight alternatives to enhance battery performance and energy density.
• Composite copper foils offer a potential solution due to their tunable properties.

Purpose of the Study:

• To optimize an electroless copper plating route for fabricating ultrathin composite copper foil.
• To evaluate the feasibility of using this composite foil as a lightweight current collector for LIBs.
• To assess the electrochemical performance and energy density improvements in LIBs utilizing the new foil.

Main Methods:

• Systematic optimization of NaOH modification and AgNO3 activation processes on polyimide (PI) film.
• Electroless copper plating with optimized concentrations of formaldehyde (HCHO) and copper sulfate (CuSO4).
• Incorporation of benzotriazole as an antioxidant to improve corrosion resistance.

Main Results:

• Established optimal conditions for PI film modification and activation for copper deposition.
• Achieved a "copper (1 μm)-polymer (4 μm)-copper (1 μm)" sandwich structure with excellent tensile strength and ductility.
• Demonstrated a 50.1% weight reduction compared to conventional 6 μm electrolytic copper foil.
• Composite foil exhibited comparable electrochemical performance, leading to increased mass energy density from 351.9 to 368.9 Wh/kg in LIBs.

Conclusions:

• The developed electroless plating method is engineered for feasible production of lightweight composite copper foils.
• These foils show significant potential as advanced current collectors for high-energy-density lithium-ion batteries.
• The composite copper foil represents a viable, high-performance alternative to traditional copper foils.