Borohydride fuel cell

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. 

Alternatively, NaBH4 could be used in borohydride fuel cell systems, where the borohydride is directly oxidized [53]. Such systems have a slightly higher potential of = 1.64 V, compared to the PEM fuel cell with hydrogen gas as energy source. The reaction at the cathode is described as follows (Eq. (5.15)) ... 

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). 

Fig. 8.22 Cell polarization and power density curves for the borohydride fuel cell at 50°C, 70°C and 85°C. Anode 0.2g alloycm , 10wt% NaBH4 in 20wt% NaOH at a flow rate of0.2Lmin h Cathode 2 mg Ptcm , humidified O2 at 0.21 min (1 atm).

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... 

A problem associated with borohydride fuel cells is the fact that both reactants fundamentally may undergo catalytic decomposition, which leads to a lower utilization efficiency. Also, gaseous decomposition products may hamper access of the liquid reactants to the catalyst. 

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). 

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