Strategies toward enhanced low-pressure volumetric hydrogen storage in nanoporous cryoadsorbents

The volumetric hydrogen capacity remains one of the most challenging criteria for on-board hydrogen storage system requirements. Here a new concept for hydrogen storage of porous aromatic frameworks (PAFs) impregnated with lithium-decorated fullerenes (Li6C60) is described. The loading of Li6C60 and the effect on the adsorption of hydrogen (H2) has been investigated by molecular simulation. It is shown that the incorporation of Li6C60 can enhance the volumetric capacity of H2 from 12 to 44 g L(-1), a 260% increase at 10 bar and 77 K. The impregnation of Li6C60 increases the heat of adsorption and surface area at the cost of the available pore volume. However, the increase in adsorbed hydrogen outweighs any pore volume loss under optimized Li6C60 loading and operating conditions. In addition, the H2 volumetric uptake is shown to correlate with the volumetric surface area at all pressures whereas the H2 gravimetric uptake correlates with the heat of adsorption at low pressures, surface area at moderate pressures, and pore volume at high pressures.