Giant energy absorption capacity of graphene-based carbon honeycombs

Cellular energy absorbing materials (EAMs) are used in a wide range of important applications from aircrafts to helmets. The energy absorption capacities (EAC) of the conventional EAMs (e.g., aluminum foams, steel foams, cellular bulk metallic glasses, and carbon nanotube buckypaper) are generally on the order of 1-100 J/g, and it remains a challenge to find new EAMs with higher EACs. Here we reveal via molecular dynamics simulations that, in the in-plane direction, graphene-based carbon honeycombs (GCHs) have an extremely large EAC, up to 2400 J/g, much higher than those of all aforementioned cellular EAMs. In the out-of-plane direction, GCHs also possess a high anti-penetration EAC of 3400 J/g, which is close to that of graphene and ∼10 times higher than that of steel sheets. The giant EAC of GCHs originates from their three-dimensional graphene structures consisting of high-energy sp2 and sp3 bonds which provide a high plateau stress in a long strain range. Our findings may open up opportunities for designing light, thin, yet exceptionally strong energy absorbing systems.