The Net Discharge Mechanism of the VB<sub>2</sub>/Air Battery

Stuart, Jessica; Hohenadel, Amelia; Li, Xuguang; Han, Xijiang; Parkey, Jeff; Rhodes, Christopher P.; Licht, Stuart

doi:10.1149/2.0801501jes

Cited by 29 publications

(29 citation statements)

References 27 publications

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“…8 The VB 2 anode discharges all 11 of its electrons at a singular voltage plateau, in accordance with: [8][9][10] Anode :…”

Section: 2mentioning

confidence: 78%

“…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.…”

Section: Methodsmentioning

confidence: 99%

“…The thermodynamic (intrinsic battery) potential of Equation 3 is 1.55 V. [8][9][10] The experimental VB 2 /air battery is observed to discharge at a fraction of this intrinsic potential. An advance of the VB 2 anode has been the synthesis of active, nanoscopic (∼400 nm particle size) material compared to commercially available macroscopic (∼5,000 nm) material.…”

mentioning

confidence: 97%

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Higher Capacity, Improved Conductive Matrix VB₂/Air Batteries

Lefler

Stuart

Parkey

et al. 2016

J. Electrochem. Soc.

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Transition metal borides, such as VB 2 , have been investigated as alternative, higher capacity anode materials. The VB 2 high capacity is due to the capability to undergo a 4060 mAh/g formula weight multiple electron (11 e − ) alkaline oxidative discharge at a singular discharge potential plateau. With a comparable formula weight (10% higher) to zinc, VB 2 has an intrinsic gravimetric capacity five fold higher than the 2 e − oxidation of the widely used zinc alkaline anode. One challenge to the implementation of VB 2 /air batteries is that resistive oxide products impede the discharge depth, and only thin anode batteries (for example 10 mAh in a 1 cm diameter cell) had been demonstrated to discharge effectively. This study demonstrates that (i) smaller particle size (nano-VB 2 , as opposed to macroscopic VB 2 ) helps to alleviate this effect and (ii) a stacked anode compartment configurations improve the anode conductive matrix significantly, resulting in an increase in the coulombic efficiency of high capacity, thicker anodes in VB 2 /air batteries. Combined, these effects provide a 50% relative increase in the coulombic efficiency (from 50% to 75% at an 0.4 V discharge cutoff) of a 30 mAh coin cell, and increase the coulombic efficiency of the 100 mAh cell to 50%. Higher energy density portable power is needed for consumer electronic, medical, and military devices, and drives the need for increased energy density batteries. Zinc-air batteries are primary batteries with the highest commercial energy capacity. They provide a practical capacity of up to 1,756 Wh/L, which is 5-fold higher than that of rechargeable Li-ion batteries and 10-fold higher than conventional alkaline primary (zinc anode/manganese dioxide cathode) batteries. 1,2The capacity of zinc is limited by its oxidative discharge, which releases two electrons per zinc, leading to an intrinsic capacity of 820 mAh/g (=2 * FW/Faraday * mAh). Transition metal borides have been investigated as alternative, potentially higher capacity anode materials due to their ability to undergo oxidative discharge processes that release multiple electrons per molecule. The highest capacity of these materials, vanadium diboride, has an alkaline capacity per VB 2 (FW 72.561 g/mol) intrinsic capacity of 4060 mAh/g (charge/FW), approximately five times that of zinc. [3][4][5][6][7][8][9] As with the zinc anode, the borides can chemically react to generate hydrogen, and this causes a parasitic loss of battery capacity. In 2007, we noted that a zirconia overlayer impedes this parasitic reaction and promotes the battery discharge reaction.3,8 VB 2 coupled with an air cathode results in a battery material that is among the highest energy density of any primary battery (5,300 kWh/kg). 8 The VB 2 anode discharges all 11 of its electrons at a singular voltage plateau, in accordance with: [8][9][10] Anode :The thermodynamic (intrinsic battery) potential of Equation 3 is 1.55 V. [8][9][10] The experimental VB 2 /air battery is observed to discharge at a fraction of this intrinsic ...

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“…8 The VB 2 anode discharges all 11 of its electrons at a singular voltage plateau, in accordance with: [8][9][10] Anode :…”

Section: 2mentioning

confidence: 78%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 97%

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Higher Capacity, Improved Conductive Matrix VB₂/Air Batteries

Lefler

Stuart

Parkey

et al. 2016

J. Electrochem. Soc.

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“…Our recent study of the discharge mechanism of VB 2 determined specific discharge products and provided an updated reaction for the anodic discharge process. 18 From the data in Figure 1, it is evident in the figure that the specific capacity of the TiB 2 /air cell improves with increasing carbon content in the anode mix. Using the 30 wt% carbon mixture, a coulombic efficiency (experimental specific capacity/theoretical specific capacity) of ∼40% was obtained.…”

Section: Resultsmentioning

confidence: 94%

“…13,16 Our recent work supports that the higher specific capacity and voltage of nanoscopic VB 2 compared to macroscopic VB 2 is related to the higher degree of vanadium and boron at the surface region for nanoscopic VB 2 compared to predominately oxide species at the surface region of macroscopic VB 2 based on X-ray photoelectron spectroscopic analysis. 18 Shown in Figure 7 are high capacity (30 mAh) VB 2 anodes prepared with either nanoscopic or macroscopic vanadium diboride, which were used as a baseline for comparison with the composites. It is evident from the data in the figure that for the 30 mAh cells, the nanoscopic VB 2 discharges at a higher voltage and to a higher discharge capacity than the comparable cell prepared with the macroscopic VB 2 .…”

Section: Resultsmentioning

confidence: 99%

High Energy Capacity TiB₂/VB₂Composite Metal Boride Air Battery

Stuart

Lefler

Rhodes

et al. 2015

J. Electrochem. Soc.

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Transition metal borides, such as VB 2 and TiB 2 , are studied as battery anode materials both individually and as a composite anode for an air cathode battery. The combination of VB 2 and TiB 2 is shown to enhance anodic battery performance. In alkaline media, VB 2 and TiB 2 anodically discharge to yield respectively 11 and 6 electrons per molecule with VB 2 intrinsic gravimetric charge capacity of 4,060 mAh/g and 2,314 mAh/g for TiB 2 , 3 to 5 fold higher than a conventional zinc anode. With an air cathode using external O 2 , these boride/air batteries discharge at ∼1 V, and exhibit unusually high, primary battery energy capacities. We show that the coulombic efficiency attained by the TiB 2 anode in boride/air batteries is not a strong function of the anode capacity per unit area (cm 2 ) of anode, while the efficiency of the VB 2 anode decreases with increasing anode capacity. The discharge of VB 2 shows a unique singular voltage plateau, indicating that the 11 electrons discharge at a similar potential. Two voltage plateaus are observed during the TiB 2 discharge indicating the possibility of a two-step anodic oxidation. The combination of VB 2 and TiB 2 exhibits evidence of a synergistic increase of the capacity and discharge voltage of boride/air batteries. The development of improved energy density battery systems is driven by emerging technological demands of longer operational time and lighter weight for medical, military and consumer electronic devices. A principal focus of battery research in the past decade has been the advancement of the energy capacity of rechargeable Li-ion batteries, which have a capacity of 100 to 200 Wh/kg. Despite this, the capacity of rechargeable batteries remains approximately 5-fold lower than that of primary batteries. The highest commercial primary battery energy capacity is exhibited by zinc/air batteries.1 Replacement of the air battery's zinc electrode by a higher capacity anode material has the potential to further increase the energy capacity. New materials, such as metal borides, have been studied due to their demonstrated high capacities as anodes for primary alkaline batteries. Of the large number of borides that have been investigated as anodes in alkaline media, TiB 2 and VB 2 exhibit the highest stability and demonstrated anodic capacity.2-9 Although Zn, TiB 2 , and VB 2 have similar formula weights (65.39, 69.49. 72.56 g/mol), the Zn oxidative discharge releases only two electrons, whereas TiB 2 and VB 2 are observed to discharge up to 6 and 11 electrons, respectively. While the conventional Zn anode has an intrinsic capacity of 820 mAh/g (2*FW/Faraday*mAh), TiB 2 and VB 2 have respective intrinsic capacities of 2,314 and 4,060 mAh/g. Coupled with an air cathode, vanadium diboride has been reported to have among the highest energy density of any primary battery (5,300 kWh/kg). 9 The 11 electron discharge reaction of the VB 2 /air battery is given by the following half cell and full cell reactions: It is interesting to note that VB 2 discharges each of its 11...

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Metal Borides: Versatile Structures and Properties

Albert

Hofmann

2017

Handbook of Solid State Chemistry

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Borides represent an important class of inorganic solids. Often they exhibit interesting properties and can be used either as structural and functional materials or as catalysts. Boron is a non‐metallic, light element with three valence electrons. Its ability to form multi‐centred bonds to overcome the electron deficiency is huge, and it manifests itself in an enormous variety of complicated structures. Many metals react with boron and form borides. Metal borides (MxBz, MxM′yBz, etc.; M, M′ = metals) are binary or multinary compounds in which boron is the most electronegative partner. The huge variety of boride structures is known. It is reasonable to distinguish between, on the one hand, the more metal‐rich borides in which boron atoms are either isolated or they form dumbbells or chains and, on the other side, the boron‐rich materials that display very exotic framework structures, often consisting of beautiful deltahedra. In between there are the layered structures with two‐dimensional arrays of boron atoms. The degree of dimensionality of the arrangement of the boron atoms correlates closely with the (non)metallic character of the borides. Thus, the structural diversity is reflected by an extreme variability of electrical properties between metallic and ceramic. The huge influence of the boron atom structure on the electronic structure of the metal borides is quite unique. It has its origin in the special electron‐deficient character of the boron atom that often leads to a very special bonding situation in boron compounds.

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The Net Discharge Mechanism of the VB₂/Air Battery

Cited by 29 publications

References 27 publications

Higher Capacity, Improved Conductive Matrix VB₂/Air Batteries

Higher Capacity, Improved Conductive Matrix VB₂/Air Batteries

High Energy Capacity TiB₂/VB₂Composite Metal Boride Air Battery

Metal Borides: Versatile Structures and Properties

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The Net Discharge Mechanism of the VB2/Air Battery

Cited by 29 publications

References 27 publications

Higher Capacity, Improved Conductive Matrix VB2/Air Batteries

Higher Capacity, Improved Conductive Matrix VB2/Air Batteries

High Energy Capacity TiB2/VB2Composite Metal Boride Air Battery

Metal Borides: Versatile Structures and Properties

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Product

Resources

About

The Net Discharge Mechanism of the VB₂/Air Battery

Higher Capacity, Improved Conductive Matrix VB₂/Air Batteries

Higher Capacity, Improved Conductive Matrix VB₂/Air Batteries

High Energy Capacity TiB₂/VB₂Composite Metal Boride Air Battery