Top–Down Strategy Enabling Elastic Wood Nanocarbon Sponges with Wrinkled Multilayer Structure and High Compressive Strength for High‐Performance Compressible Supercapacitors

Abstract 3D porous carbon electrodes have attracted significant attention for advancing compressible supercapacitors (SCs) in flexible electronics. The micro‐ and nanoscale architecture critically influences the mechanical and electrochemical performance of these electrodes. However, achieving a balance between high compressive strength, electrochemical stability, and cost‐effective sustainable production remains challenging. Here, a superelastic wood nanocarbon sponge (WNCS) with a wrinkled multilayer structure is developed via a facile “top–down” design on natural wood. These unique wrinkled nanolayers effectively alleviate stress concentration through elastic deformation, resulting in a high compressive strength of 580.6 kPa at 70% reversible strain. The significantly increased specific surface area, coupled with abundant micro‐mesopores and highly graphitized nanocarbon, promotes rapid ion/electron transport, enabling the WNCS to achieve an ultrahigh capacitance of 4.21 F cm −2 at 1 mA cm −2 , along with excellent cyclic stability and rate capability. Furthermore, an asymmetric supercapacitor (ASC) using a WNCS anode and a NiCo‐layered double hydroxide cathode retains 71.8% of its initial capacitance after 1000 compression cycles and withstands stress up to 1.03 MPa without capacitance degradation. This sustainable, cost‐effective WNCS shows great promise for flexible, compressible, and wearable electrochemical energy systems.