Direct borohydride fuel cells

B. H. Liu, S. Suda, Hydrogen storage alloys as the anode materials of the direct borohydride fuel cell , J. Alloys Compd. 454 (2008) 280-285. 

The product of the decomposition is, like in the Millennium Cell system, sodium metaborate. The system shows the same problems for the regeneration of NaBH4 from an aqueous solution of metaborate as described below. One advantage of the direct borohydride fuel cell systems is that platinum as catalyst is not needed. Unfortunately, depending on the temperature of the solution, some hydrogen gas is produced in a side reaction. However, this hydrogen can be piped out or can be used as additional fuel in a subsequent PEM fuel cell. 

The protide transition to proton has also been successfully applied to the development of a new type of fuel cell, the Direct Borohydride Fuel Cell (DBFC). The principle of the DBFC is briefly summarized by the following equation ... 

Compact hydrogen storage devices have been developed for use with small PEMFC in the past few years. The cost effectiveness will be improved significantly by applying BHJ solutions as the hydrogen fuel source to handy or mobile electronic devices such as portable computers, PDA, CD-cameras and UPS. The fuel cost even now is estimated to be very reasonable for such compact devices with capacity ranges from a few tens to a few hundred watts. The borohydride fuel costs, estimated from today s market price are shown in Fig. 6.47 for the PEMFC and in Fig. 6.48 for the DBFC (direct borohydride fuel cell). 

Wee J-H (2006) Which type of fuel cell is more competitive for portable application direct methanol fuel cells or direct borohydride fuel cells J Power Sources 161 1-10... 

Fuel cells are usually open systems, and their energy density and specific energy is largely based on the storage of fuel (and oxidant in the case of air-independent systems). Of the fuel cell types considered here, hydrogen PEMs, PAFCs and hydrogen AFCs use hydrogen as fuel, direct methanol fuel cells (DMFC) use aqueous methanol solution or pure methanol, and (alkaline) direct borohydride fuel cells (DBFC) use sodium borohydride solution as the liquid fuel. 

Ponce-de-Leon C, Kulak A, Williams S, Jimenez IM, Walsh FC (2011) Improvements in direct borohydride fuel cells using three-dimensional electrodes. Catal Today 170 148-154... 

The price of sodium borohydride is currently too high by far for a practical application. Compared with hydrogen production from natural gas its price is 130 times higher. However, the idea of applying sodium borohydride as a fuel has the prerequisite of recycling the sodium borate product, and this could lower the price on the basis of mass production [98]. An alternative to hydrogen generation from sodium borohydride is the direct borohydride fuel cell, which is not within the scope of this book, so will not be discussed. 

FUEL CELLS USING INORGANIC LIQUIDS AS FUELS 4.12.1 Direct Borohydride Fuel Cells... 

Liu B. H., Z. P. Li, Current status and progress in direct borohydride fuel cell technology development, J. Power Sources, 187, 291 (2009). 

Ponce de Le6n, C., F. C. Walsh, D. Pletcher, D. J. Browning, J. B. Lakeman, Direct borohydride fuel cells, J. Power Sources, 155, 172 (2006). 

Ma, J. Choudhury, N. A. Sahai, Y, A comprehensive review of direct borohydride fuel cells. Renewable... 

Ma J, Liu Y, Zhang P et al (2008) A simple direct borohydride fuel cell with a cobalt phthalocyanine catalyzed cathode. Electrochem Commun 10 100-102... 

The redox potential in Eq. (6.14) is -0.4 V versus a reversible hydrogen electrode (RHE). Although BH4 is more resistant to hydrolysis than other hydrides such as alanates, the hydrolysis of BHa" (Eq. (6.15)) readily occurs in the presence of some catalysts. In particular, platinum-based catalysts, which are common anodes in direct borohydride fuel cells (DBFCs), cause significant decomposition of BH4". 

Wee, J.H. (2006) A comparison of sodium borohydride as a fuel for proton exchange membrane fuel cells and for direct borohydride fuel cells. Journal of Power Sources, 155, 329-339. 

Choudhury, N.A., Raman, R.K., Sampath, S. and Shukla, A.K. An alkaline direct borohydride fuel cell with hydrogen peroxide as oxidant, J. Power Sources, 143 (2005) 1-8. 

Gyenge, E. Electrooxidation of borohydride on platinum and gold electrodes implications for direct borohydride fuel cells , Electrochim. Acta, 49 (2004) 965-978. 

The direct borohydride fuel cell (DBFCs) usually operates in one single alkaline environment since the BH4 ion is imstable in neutral and acidic media. The theoretical OCV of a conventional DBFC in a single alkaline solution is 1.64 V. An acid-alkaline hybrid DBFCs can have oxidation of BH4" in alkaline and reduction of O2 (or H2O2) in acid. The theoretical OCV of this acid-alkaline hybrid DBFCs can reach as high as 3.0 V. The reactions are... 

A schematic of an alkaline direct borohydride fuel cell coupled with acidic peroxide cathode and separated by a LISICON membrane. (From Y. Wang, P. He and H. Zhou, A novel direct borohydride fuel cell using an acid-aUtallne hybrid electrolyte. Energy Environ. Sci. 3, 2010, 1515-1518. Reproduced by permission of The Royal Society of Chemistry.)... 

D. Santos and C. Sequeira, Zinc anode for direct borohydride fuel cells, /. Electrochem. Soc. 157,2010, B13-B19. 

Y. Wang, R He and H. Zhou, A novel direct borohydride fuel cell using an add-alkaline hybrid electrolyte. Energy Environ. Sci. 3, 2010,1515-1518. 

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