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.