Bioinspired “Enoki Mushroom-like” Hollow Nanorods Architectured NiO@Carbon Hybrid Foam for High-Performance Compressible Supercapacitors

Supercapacitors with excellent flexibility and compressibility hold broad development prospects for wearable electronics. Three-dimensional (3D) carbon materials, characterized by rich porous structures and outstanding mechanical properties, offer significant advantages in such supercapacitors. However, the fabrication of carbon materials possessing both excellent mechanical and electrochemical performance simultaneously remains challenging. Herein, we develop a bioinspired NiO@carbon hybrid foam (NiO@CCF) via a scalable dip-coating and carbonization strategy. The obtained NiO@CCF features unique “enoki mushroom-like” hollow nanorods in situ grown during pyrolysis, endowing it with ultralow density, intrinsic superhydrophilicity, full compressibility recovery, and exceptional mechanical stability. As a binder-free electrode, NiO@CCF delivers a remarkable specific capacitance of 372.75 F/g, 330% higher than that of pristine carbon foam (86.36 F/g). This is attributed to synergistic effects: (i) hierarchical porosity (with a high surface area of 1156 m2/g) providing abundant active sites, (ii) reversible Faradaic reactions enhancing pseudocapacitance, and (iii) accelerated ion/electron transport through the hollow nanorod architecture. The assembled solid-state asymmetric supercapacitor achieves a high energy density of 46.68 Wh/kg, while exhibiting a 386% volumetric capacitance increase (1.54 → 7.49 F/cm3) under 80% compression. This work provides a cost-effective paradigm for high-performance compressible supercapacitors, advancing their applicability in wearable energy storage.