Fabrication of VB₂/Air Cells for Electrochemical Testing

Abstract

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for synthesizing nanoscopic VB 2 is presented as well as step-by-step procedure for applying a zirconium oxide coating to the VB 2 particles for stabilization upon discharge. The process for disassembling existing zinc/air cells is shown, in addition construction of the new working electrode to replace the conventional zinc/air cell anode with a the nanoscopic VB 2 anode. Finally, discharge of the completed VB 2 /air battery is reported. We show that using the zinc/air cell as a test bed is useful to provide a consistent configuration to study the performance of the high-energy high capacity nanoscopic VB 2 anode. Video LinkThe video component of this article can be found at

The Net Discharge Mechanism of the VB2/Air Battery

“…19 Recently, we reported on the improved voltage and 11 electron discharge efficiency of 5 mAh VB 2 /air batteries using this nanoscopic compared to macroscopic particle sized VB 2 within the anode construction. [19][20][21] As seen in Figure 1, nanoscopic VB 2 cells discharged to 70-74% coulombic efficiency over a load 3000 and exhibited an initial potential of 0.9 V. This compares to 4 , pK1,2,3 = 3.8, 7.8 and 13.0). In solution, the products will vary with hydroxide concentration and depth of discharge, including hydrogen and metal cation containing species, such as in either a KOH or NaOH electrolyte: K x H z BO 3 3-x-z or Na x H z BO 3…”

“…The intrinsic volumetric anodic capacity of the VB 2 anode (20.7 kAh L −1 ) is tenfold higher than that of the lithium anode (2.06 kAh L −1 ). [13][14][15][16][17][18][19][20][21] A VB 2 anode within a battery can be coupled with oxygen from external air to provide extremely high energy density VB 2 /air batteries. 17 The anode half cell, cathode half cell, and full cell reactions based on generalized discharge products 19 The VB 2 /air battery has a theoretical discharge potential of 1.55 V, as calculated from the thermodynamic free energy of the cell reactants and products.…”

Higher Capacity, Improved Conductive Matrix VB2/Air Batteries

“…For example, under the same load, a 2.5, 5, 10 or 30 mAh VB 2 /air cell discharged to 80%, 60%, 50% or 30 to 40% columbic efficiency respectively. 9,12,13 In this study, we provide a path to ameliorate this effect through advanced anode configurations with an improved conductive matrix. …”

“…The cell fabrication is as previously delineated. [9][10][11][12][13] In brief, the air electrode from the PowerOne P675 battery is kept intact and reused. The Zn anode of the PowerOne P675 cells was removed by opening the existing cell, removing the anode active material, and using the separator and cathode as received for the VB 2 /air battery.…”

“…[11][12][13] One challenge to the implementation of VB 2 /air batteries is that only thin anode batteries (for example 10 mAh in a 1 cm diameter coin * Electrochemical Society Student Member.…”