Method for improving performance of direct sodium borohydride fuel cell

A sodium borohydride, fuel cell technology, applied in the field of electrochemical applications, can solve the problems of reducing battery fuel utilization, reducing battery operating voltage, reducing fuel utilization, etc., to reduce charge transfer resistance, improve performance, and inhibit hydrolysis. Effect

Inactive Publication Date: 2009-11-25
CHONGQING UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, there are two prominent technical problems in the working process of DBFC: firstly, the direct oxidation of sodium borohydride in the alkaline system is accompanied by its own hydrolysis, which causes the negative electrode to generate "mixed potential" and reduces the working voltage of the battery; Competition between hydrolysis and oxidation also reduces the fuel efficiency of the cell
Secondly, the "penetration" phenomenon produced by borohydride radicals reaching the surface of the cathode through the diaphragm will cause battery fuel loss and positive electrode polarization, making the number of electron transfers in the electrochemical oxidation of sodium borohydride less than eight electrons, which not only reduces fuel consumption. utilization, also reduces the performance of the battery

Method used

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  • Method for improving performance of direct sodium borohydride fuel cell
  • Method for improving performance of direct sodium borohydride fuel cell
  • Method for improving performance of direct sodium borohydride fuel cell

Examples

Experimental program
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Effect test

Embodiment 1

[0028] Weigh sodium borohydride and dissolve it in 1.5mol / L sodium hydroxide solution to make 0.27mol / L sodium borohydride solution, and then add 0μmol / L; 10μmol / L; 30μmol / L; 50μmol / L of sodium oxalate, mixed well and used as electrolyte for direct sodium borohydride fuel cell. By 0.24cm 2 The platinum sheet is the working electrode, the mercury mercury oxide electrode is the reference electrode, and the graphite rod is the auxiliary electrode. Cyclic voltammetry is used for performance testing.

[0029] Because there are lone pairs of electrons on the carboxyl group in the sodium oxalate molecule, it is easy to adsorb on platinum, the chemical formula is Pt, so that the borohydride on the electrode surface, the chemical symbol is BH 4 - , The combined amount is reduced, and there are enough catalytic points on the electrode to oxidize BH 4 - , So the current of oxidation peak a1 increases. The size of the oxidation peak current changes with the concentration of sodium oxalate....

Embodiment 2

[0031] Weigh sodium borohydride and dissolve it in 1.5mol / L sodium hydroxide solution to make 0.27mol / L sodium borohydride solution, and then add 0μmol / L; 30μmol / L; 60μmol / L; 90μmol / L of urea, mixed well and used as the electrolyte of direct sodium borohydride fuel cell. By 0.24cm 2 The platinum sheet is the working electrode, the mercury mercury oxide electrode is the reference electrode, and the graphite rod is the auxiliary electrode. Cyclic voltammetry and AC impedance spectroscopy at -0.4V activation potential are used for performance testing.

[0032] Cyclic voltammetry test shows that when 60μmol / L of urea is added, the current of oxidation peak a1 directly oxidized by sodium borohydride is the largest, and the current of oxidation peak b2 in the flyback process is the lowest, see figure 2 . In the AC impedance spectroscopy, when adding different concentrations of urea, the electrochemical impedance spectroscopy of sodium borohydride on the platinum electrode is obviously...

Embodiment 3

[0035] Weigh sodium borohydride and dissolve it in 1.5mol / L sodium hydroxide solution to make 0.27mol / L sodium borohydride solution, and then add 0μmol / L; 30μmol / L sodium oxalate; 60μmol / L Urea; 0.3μmol / L thiourea; 1mmol / L ethanol, mixed well and used as electrolyte for direct sodium borohydride fuel cell. By 0.24cm 2The platinum sheet is the working electrode, the mercury mercury oxide electrode is the reference electrode, and the graphite rod is the auxiliary electrode. Performance tests are performed by cyclic voltammetry, AC impedance spectroscopy at -0.4V activation potential, open circuit potential, and constant current discharge.

[0036] In AC impedance spectroscopy, the size of the electrochemical impedance arc diameter in the high frequency region is in order: urea Figure 4 . It shows that the addition of 60μmol / L urea can reduce the energy barrier to be overcome in the electrochemical oxidation of sodium borohydride and enhance NaBH 4 -The conductivity of the NaOH solu...

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Abstract

Method for improving performance of direct sodium borohydride fuel cell, the technical scheme is that, at a temperature range of 293.15 to 313.15 K, adding ureophil or sodium oxalate into alkaline solution of sodium borohydride and mixing uniformly, then the mixture is used as electrolyte of direct sodium borohydride fuel cell, testing shows that electrochemical performance of the fuel cell is improved obviously. Direct sodium borohydride fuel cell according to the invention, the added ureophil or sodium oxalate into alkaline solution of sodium borohydride can inhibit hydrolysis of sodium borohydride effectively and overcome penetration of boron-hydrogen ion, and improve performace of direct sodium borohydride fuel cell.

Description

Technical field [0001] The invention belongs to the field of electrochemical applications, and specifically relates to a method for improving the performance of direct sodium borohydride fuel cells, which can inhibit the hydrolysis of fuel sodium borohydride and overcome the "penetration" of borohydride ions, thereby improving the direct sodium borohydride fuel cell Performance. Background technique [0002] Direct sodium borohydride fuel cell, abbreviated as DBFC, is a fuel cell that uses sodium borohydride as a fuel and directly participates in the electrochemical reaction of the negative electrode. The difference between direct sodium borohydride fuel cell, abbreviated as IBFC, and DBFC Need to go through the intermediate step of producing hydrogen, the fuel is directly input into the anode of the fuel cell to generate electricity. In other words, the free energy converted into reaction heat in IBFC when sodium borohydride is hydrolyzed to produce hydrogen can be used in DBFC ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M8/00H01M8/08
CPCY02E60/50
Inventor 余丹梅陈昌国雷淑
Owner CHONGQING UNIV
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