The Super-Iron Boride Battery

Licht, Stuart; Yu, Xingwen; Wang, Yufei; Wu, Huiming

doi:10.1149/1.2839554

Cited by 27 publications

(37 citation statements)

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“…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.…”

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The Net Discharge Mechanism of the VB₂/Air Battery

Stuart

Hohenadel

et al. 2014

J. Electrochem. Soc.

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The electrochemical discharge of VB 2 is a unique process that involves the multiple electron per molecule oxidation of the tetravalent transition metal ion, V (+4 → +5), and each of the two borons 2×B (−2 → +3), corresponding to a net 11 electron discharge mechanism of the VB 2 /air cell as described by the overall cell reaction: VB 2 + 11/4O 2 → B 2 O 3 + 1 2 V 2 O 5 . However, in the presence of alkaline electrolytes, the discharge products include alkali salts associated with vanadaic and boric acid. In this study, we used FTIR, XRD, and coulombic efficiency measurements to probe the discharge products of high capacity cells and isolate KVO 3 as the principal vanadium discharge product. Additionally, we show that K 2 B 4 O 7 is the probable borate product. From FTIR analysis in KOH electrolyte, it is evident that the alkaline VB 2 /air discharge reaction is: VB 2 + 11/4O 2 + 2KOH → 1 2 K 2 B 4 O 7 + KVO 3 + H 2 O. XPS shows that the surface structure of nanoscopic VB 2 is very different from macroscopic VB 2 , which may contribute to the improved electrochemical properties of the nanoscopic material. The understanding of the discharge process and factors affecting performance contribute to furthering the development of extremely high capacity VB 2 /air batteries that utilize multi-electron processes. Metallic zinc has been used as an anode material in the majority of aqueous primary systems due to zinc metal's high two-electron oxidation capacity and effective discharge. The zinc-carbon battery, known as the Leclanché cell, was first introduced in the 19 th century as a low-cost solution for early energy storage needs. The zinc cell, which produced approximately 65 Wh kg −1 , was ideal only for low-rate discharges.1,2 Until the development of the zinc/alkaline/manganese dioxide battery and the zinc/air cell, there was little improvement in primary batteries. The alkaline Zn/MnO 2 cell has since dominated primary electrochemical storage, providing 145 Wh kg −1 . Although more expensive than the zinc-carbon battery, the alkaline cell improved performance by increasing energy densities and power capabilities. The zinc/air battery, using external O 2 as the battery active cathode reactant further improves the energy density of primary battery systems. It would be useful for electronic devices to have even higher energy storage densities than that available with zinc/air batteries.3 Most metal/air batteries to date have been unsuccessful in reaching the high-energy densities that are made possible by multi-electron oxidations, due to material passivation or chemical instabilities. 4 To provide high energy density cells, there has been an effort to develop high-capacity multi-electron per molecule charge storage processes.5-21 Vanadium diboride (VB 2 ) undergoes a multiple electron oxidation process, which to its completion involves an extraordinary 11 electron per molecule oxidation, including oxidation of the tetravalent transition metal ion, V(+4 → +5), and each of the two borons 2xB(−2 → +3). VB 2 has an intri...

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The Net Discharge Mechanism of the VB₂/Air Battery

Stuart

Hohenadel

et al. 2014

J. Electrochem. Soc.

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“…These results show that the coexisting transition metal and boride in the metal borides co-activate each other in the ball-milling process, thereby significantly enhancing their electrochemical performances. Metal borides have received considerable attention recently because of their high specific capacities as anode materials in both alkaline and neutral electrolytes [1][2][3][4][5][6][7][8]. In our earlier work, crystalline VB 2 was found to deliver a very high discharge capacity of above 3100 mAh g −1 through a simultaneous 11-electron electrochemical oxidation; this is probably the highest specific capacity observed so far for aqueous anode materials [1].…”

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Mechanochemical synthesis and high-capacity performances of transition-metal borides as aqueous anode materials

2012

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Transition-metal borides MB 0.5 (M = Co, Mo, V) were synthesized by high-speed mechanical ball-milling of the corresponding elemental metals and boron, and investigated as aqueous anode materials. The as-synthesized borides can achieve an excellent discharge capacity, about twice that of their parent transition metals. The metal boride electrodes also exhibit polarizations about 100-300 mV lower than those of their parent metals. The galvanostatic discharge curve of CoB 0.5 shows a single discharge voltage plateau as a result of simultaneous electro-oxidation of elemental cobalt and/or amorphous cobalt boride. Both MoB 0.5 and VB 0.5 show two well-defined voltage plateaus, corresponding to the electro-oxidation of the corresponding metal and boride. These results show that the coexisting transition metal and boride in the metal borides co-activate each other in the ball-milling process, thereby significantly enhancing their electrochemical performances. Metal borides have received considerable attention recently because of their high specific capacities as anode materials in both alkaline and neutral electrolytes [1][2][3][4][5][6][7][8]. In our earlier work, crystalline VB 2 was found to deliver a very high discharge capacity of above 3100 mAh g −1 through a simultaneous 11-electron electrochemical oxidation; this is probably the highest specific capacity observed so far for aqueous anode materials [1]. The effective electro-activation of crystalline borides represented by VB 2 is attributed to at least two factors. One is the improved electronic conductivity of the boron component as a result of the alternating boron layers and transition metal (TM) layers in the MB 2 lattice. The other is the synergistic effects of boron and TM: electron donation from the TM atoms to the boron atoms weakens the bonds between the boron atoms, resulting in electrochemical activation of boron. Conversely, the activation of boron alleviates the passivation of the TM and leads to TM activation. These activations ensure electro-oxidation of both TM and boron in the TM borides, resulting in the very high-capacity output of the borides.To test the potential of other types of metal borides for high-capacity anode materials, we synthesized a series of MB 0.5 (M = Co, Mo, and V) by mechanical ball-milling and investigated their electrochemical properties as aqueous anodes. In this paper, we report the synthesis, polarization behaviors, and high-capacity performances of these MB 0.5 compounds. The mechanisms of electrochemical activation of the borides are also discussed. Experimental Preparation of MB 0.5The MB 0.5 borides (M = Co, Mo, and V) were prepared by mechanical ball-milling a mixture of the elemental TM (Co, Mo, or V) and boron powders in a TM:boron atomic ratio of

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“…Using this approach for macroscopic VB 2 , we have been able to largely mitigate the VB 2 self-discharge through using a zirconia overlayer. 3,9 Stored at 45• C for one week, an uncoated VB 2 alkaline anode loses 10% of its original charge capacity, however with a 1% ZrO 2 coating the anode retains 100% of that capacity. …”

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“…Using this approach for macroscopic VB 2 , we have been able to largely mitigate the VB 2 self-discharge through using a zirconia overlayer. 3,9 Stored at 45…”

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“…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][3][4][5][6][7][8][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.…”

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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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The Super-Iron Boride Battery

Cited by 27 publications

References 20 publications

The Net Discharge Mechanism of the VB₂/Air Battery

The Net Discharge Mechanism of the VB₂/Air Battery

Mechanochemical synthesis and high-capacity performances of transition-metal borides as aqueous anode materials

High Energy Capacity TiB₂/VB₂Composite Metal Boride Air Battery

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The Super-Iron Boride Battery

Cited by 27 publications

References 20 publications

The Net Discharge Mechanism of the VB2/Air Battery

The Net Discharge Mechanism of the VB2/Air Battery

Mechanochemical synthesis and high-capacity performances of transition-metal borides as aqueous anode materials

High Energy Capacity TiB2/VB2Composite Metal Boride Air Battery

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Product

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The Net Discharge Mechanism of the VB₂/Air Battery

The Net Discharge Mechanism of the VB₂/Air Battery

High Energy Capacity TiB₂/VB₂Composite Metal Boride Air Battery