Pushing the limits of sodium borohydride hydrolysis for on-board hydrogen generation systems

•SBH hydrolysis with 6.33 wt% hydrogen density is demonstrated.•After methanation, the produced hydrogen gas is suitable for PEMFC.•Regeneration feasibility of the product is better than commercial borax.•Reaction product can be regenerated without expensive reducing agent.•50 g/L(system) of volumetric hydrogen density is expected in automobile scale.