Addressing Porosity-Packing Density Trade-offs in Carbon Aerogels via Binderless Densification for Hydrogen Storage

Hydrogen storage in porous carbons is fundamentally constrained by the trade-off between high porosity and efficient packing density, which limits achievable volumetric capacity. Here, we address this porosity-packing density trade-off in carbon aerogels through a binderless densification strategy that preserves micro- and mesoporosity while substantially increasing bulk density. Building on ultraporous carbon aerogels, controlled densification was achieved through in situ shaping during gel processing, allowing precise tuning of pore connectivity, bulk density, and microstructure. Through systematic microstructural optimization, the densified aerogels reached up to 2895 m 2 /g in BET surface area, 2320 m²/g in microporous surface area, and 1.15 cm³/g in pore volume. Notably, in situ DIW-printed monolith achieved H 2 storage capacities of 1.8 wt % and 6.9 g/L at 298 K and 5.9 wt % and 36 g/L at 77 K, both at 100 bar, representing record volumetric capacities for aerogel-based carbon sorbents under comparable conditions. It was also shown that the densified monolith exhibited ∼38% greater volumetric uptake than its powder counterpart. These results demonstrate that controlled, binderless densification provides an effective pathway for overcoming porosity-packing density limitations in carbon aerogels and advances their viability for next-generation H 2 storage applications.