Study on a direct hydrazine borane fuel cell based on an anion exchange membrane

Abstract

The reason for the higher performance of the anion exchange membrane-type direct hydrazine borane (N₂H₄BH₃) fuel cell compared to that of the cation exchange membrane-type direct hydrazine borane fuel cell is systematically investigated. The carbon-supported cobalt hydroxide (Co(OH)₂–C–PPY) catalyzes N₂H₄BH₃ to produce H₂O and BO₂⁻. The anode electrode based on ionomer XC-1 shows a higher volume percentage of hydrophilic pores (36.2%) than the electrode based on Nafion (21.7%) and reduces the mass transfer resistance from 9625 to 6988 s cm⁻¹. The cathode electrode based on XC-1 + Pention D72 ionomer shows a higher volume percentage of hydrophobic pores (23.3%) than the electrode based on Nafion (22.0%) and reduces the mass transfer resistance from 73 to 18 s cm⁻¹. The anion exchange membrane Pention-72-15cl presents a higher ionic conductivity of 173 mS cm⁻¹ than Nafion 211 (78 mS cm⁻¹). The optimized anion exchange membrane-type direct hydrazine borane fuel cell achieves a high performance of 244 mW cm⁻². The result indicates that an effective way to improve the performance of direct liquid fuel cells is to optimize the microstructure and hydrophobicity of the electrode and enhance the mass transfer of the cathode and anode.