Hydrogen supply system employing direct decomposition of solid-state NaBH4

Under the overarching aim to develop an onboard hydrogen generation system for portable fuel cell application, a hydrogen supply system that exploits the direct decomposition of solid-state NaBH4 was designed and integrated into a model fuel cell for evaluation of the system performance. The operation characteristics were evaluated based on measurement of the hydrogen yield and performance parameters including the HCl concentration and HCl/NaBH4 reaction ratio. A hydrogen yield of 95% was obtained at hydrogen supply rates higher than 650 ml/min. The gravimetric hydrogen density was highest when a 4.0 N HCl solution was used, given that the HCl/NaBH4 reaction ratio was lowest at this HCl concentration. The system performance was not affected by concentration fluctuations due to aging of the HCl solution. A stable hydrogen supply rate was achieved by optimization of the operating conditions such as the reactor pressure. The hydrogen supply system stably operated a 100 W fuel cell under various load conditions.