No abstract

This work involved the development of a high energy density flexible zinc-air battery by means of an inexpensive screen-printing technique. A very thin and highly porous cathode gas diffusion layer (GDL) fabricated by screen-printing of carbon black ink promoted oxygen permeability, resulting in a better and more efficient three-phase reaction zone. Moreover, a cathode current collector (printed using nano-silver ink) also functioned as a catalyst layer. The incorporation of this layer enabled the printed battery to be capable of high rates of discharge by promoting oxygen reduction reaction which has a decisive impact on its performance. The thickness of the GDL can be manipulated by adjusting the composition of the carbon black ink. The fabricated battery with 30 μm GDL provided an open-circuit voltage of 1.45 V and 15 -185 mA·cm −2 ohmic loss zone and demonstrated high energy density of 682 Wh·kg −1 . Furthermore, the battery was tested for its flexibility by bending it and discharging it at 2.0 mA·cm −2 . The results showed that upon bending, the battery showed no difference in characteristics of voltage or discharging time. A battery is used as an energy source for many portable devices. However, an important drawback of batteries used today is that they have low energy density whereas high energy density batteries are relatively expensive. In addition, safety and environmental impacts throughout their life cycle are also important issues. Many researchers, therefore, focus on the fabrication of a high energy density battery having lower costs and being more environmental friendly. Zinc-air batteries hold the greatest promise for future energy applications.2 These batteries use relatively inexpensive and environmentally friendly raw materials. Moreover, they have high energy densities (1,084 Wh·kg −1 ). In addition, they use an aqueous solvent and zinc (Zn) 3 which is relatively stable in an aqueous and alkaline media without significant corrosion.Zn-air battery cells basically consist of current collectors for both anode and cathode, an anode electrode containing zinc metal, a cathode electrode consisting of a gas diffusion layer (GDL) and a catalyst layer, and a separator soaked with electrolyte. All these components must be developed to ensure high performance of battery and ease of fabrication.Printing is a promising technique to fabricate electronic devices [4][5][6][7] and batteries due to its simplicity and environmental friendliness. 10 fabricated a Zn-air battery based on paper and polyethylene naphthalate (PEN) substrates by screen-printing a zinc/carbon/polymer composite anode, polymerising a poly(3,4-ethylenedioxythiophene) (PEDOT) cathode and inkjet-printing a lithium chloride electrolyte. The battery on PEN substrate provided a discharge capacity of 1.4 mAh·cm −2 . However, the battery on paper substrate showed an open-circuit voltage of 1.2 V and a discharge capacity of 0.5 mAh·cm −2 . The performance of the thin-film Zn-air battery was further improved using sodium silicate as a binder for...

Self‐discharge caused by hydrogen evolution reaction (HER) coinciding with corrosion of the zinc anode is a major drawback of printed zinc‐air batteries. Thus, this work aims at suppressing self‐discharge of flexible printed zinc‐air batteries by coating thin layer of aluminum oxide (Al2O3) onto the surface of zinc particles. The Al2O3 coating layer was directly synthesized onto the zinc particles by a low‐cost and facile sol–gel method. The Al2O3 coating effectively mitigated HER of the zinc particles, and delayed the corrosion of the zinc anode. Further, the effects of the thickness of Al2O3 layer on corrosion behavior of the zinc anode in 9 M potassium hydroxide as well as performance of the batteries were investigated. With a proper thickness of Al2O3 coating, corrosion of the battery was considerably suppressed without sacrificing the battery performance. (a) Photographic image of the fabricated battery, (b) transmission electron microscopic image of zinc particle coated with Al2O3.

No abstract