Method of fabricating nanoporous Zn anodes and the applications in Zn batteries
A method of making a free-standing nanoporous Zn is provided. The method includes compacting a predetermined amount of Zn compound precursor into a form of an anode; controlling a thickness of the Zn compound precursor to obtain desirable porosity; and reducing the Zn compound precursor in an electrochemical cell having an electrolyte at a predetermined volage against a reference electrode to obtain a nanoporous Zn anode. The nanoporous Zn includes continuous metal ligaments and pores each having a uniform width of around a few hundred nanometers. The nanoporous Zn may serve as an anode in a rechargeable Zn battery having the nanoporous Zn anode coupled to a conductive substrate, a physical block, an electrolyte, a reference electrode, and a cathode electrode, to deliver a high areal capacity and a long cycle life.
1 . A method of making a free-standing nanoporous Zn, comprising:
compacting a predetermined amount of Zn compound precursor into a form of an anode;
controlling a thickness of the Zn compound precursor to adjust porosity; and
electrochemically reducing the Zn compound precursor to metallic zinc by applying a controlled reduction voltage against a reference electrode, thereby converting the Zn compound precursor to a free-standing nanoporous metallic Zn anode.
2 . The method of claim 1 , wherein the Zn compound precursor is selected from zinc oxide, zinc carbonate, zinc chloride, zinc acetate, and combinations of any of them.
3 . The method of claim 2 , wherein the Zn compound precursor further comprises an additive selected from carbon black, carbon fiber, bismuth oxide, tin oxide, and calcium hydroxide.
4 . The method of claim 1 , wherein the compacting a predetermined amount of Zn compound precursor comprises compacting the predetermined amount of Zn compound precursor onto a conductive substrate.
5 . The method of claim 4 , wherein the conductive substrate is a Sn-plated Cu foam or a copper foam/foil.
6 . The method of claim 1 , wherein the controlling a thickness of the Zn compound precursor comprises configuring a physical block that is a rigid perforated plate to control the thickness of the Zn compound precursor to adjust porosity.
7 . The method of claim 6 , wherein the physical block is made of a material selected from polyproplene, high-density polyethylene, and acrylic resin.
8 . The method of claim 1 , wherein the electrolyte is an alkaline solution of potassium hydroxide.
9 . The method of claim 1 , wherein the controlled reduction voltage is in a range between −1.55 V and −1.6 V.
10 . The method of claim 1 , wherein the electrolyte is an alkaline solution of sodium hydroxide or lithium hydroxide.