Thin and Flexible Nickel Based Current Collectors Developed By Electroless Deposition for Energy Storage Devices

Abstract

The rapid development in portable and wearable consumer electronics for recreation, fitness and medicines requires thin, light weight and flexible solid state energy storage devices to improve the user experience and safety. Among the key components for solid state energy storages, relatively little effort has been made to the development of flexible current collectors. A polyethylene terephthalate (PET) film here was metallized by a simple and inexpensive electroless nickel deposition to form thin and flexible current collector for solid state energy storage devices. The PET was etched in butylamine, followed by surface activation of reduced nickel particles by sodium borohydride. The electroless nickel was then conducted in a commercial available plating bath. The chemical composition of the developed nickel on PET (Ni-PET) current collector was characterized by EDX and XPS, which showed a high P nickel deposition. SEM images suggested an island growth during the film formation. The electrochemical characterizations showed that the Ni-PET can be used both as current collectors for electrochemical capacitors (EC) and as electrodes for batteries (Fig. 1a) in the respective potential regions. The electrochemical performance of the Ni-PET current collector was similar to that of Ni foil but with less hydrogen evolution at low potential, and the flexibility was also better than that of a metallic Ni foil. The resistance of the Ni-PET current collector almost remained the same under compression but increased under tension. Nonetheless, the shape and conductivity can be recovered when the applied force was released. The carbon nanotube was coated on the Ni-PET to form an electrochemical capacitor electrode and showed high chemical stability in both liquid and solid electrolytes (Fig. 1b), suggesting a promising application in solid energy storage devices. Figure 1