Origami folding enables ultrahigh and reversible mechanical energy storage in pillared graphene

The ability to accommodate large deformation while maintaining full structural recoverability remains a challenge in the design of lightweight mechanical energy storage materials. Here, we demonstrate through molecular dynamics simulations that pillared graphene, a three-dimensional nanostructure made of parallel graphene sheets interconnected by vertically aligned carbon nanotubes, can achieve an unprecedented combination of ultrahigh mechanical energy storage and complete structural recovery up to 38% compressive strain. This exceptional performance stems from a unique deformation mechanism wherein the graphene layers undergo reversible Miura origami-like folding, generating an extended stress plateau together with pronounced auxetic behavior. Parametric analyses further reveal distinct roles of geometric parameters: inter-pillar distance governs the transition between global and localized folding modes, while pillar height independently modulates the elastic modulus without compromising deformation reversibility. Our findings establish a design paradigm for high-capacity energy storage and mechanical buffering systems, and highlight architecturally guided deformation as an effective strategy for exploiting the elastic potential of carbon-based nanomaterials.