Exocarp-Mesocarp-Endocarp Anatomical Engineering: Oxidation and Activation Tailoring Micromesoporous Alliance Addressing Ion Diffusion/Storage Dilemma

Biomass-derived porous carbon is an attractive capacitive material due to its controllable porous structure and surface chemistry. However, the microstructural heterogeneity of hierarchical pericarp-derived porous carbon (Pc) has long been overlooked. Herein, the pericarp was physically dissected into the exocarp (Ex), mesocarp (Me), and endocarp (En) by utilizing the structural differences among hierarchical <i>Kigelia africana</i> fruits. Ex-Pc, Me-Pc, and En-Pc are fabricated via an oxidation and activation method. Ex-Pc, Me-Pc, and En-Pc exhibit honeycomb-like, tubular, and ruptured tubular structures, respectively, and present different specific surface areas and pore size distributions. Among them, the specific capacitance of Ex-Pc is 648.0 F g^-1 at a current density of 1 A g^-1, which is much higher than that of Me-Pc (149.1 F g^-1) and En-Pc (191.4 F g^-1). The nanoscale honeycomb-like structure of Ex-Pc makes its micropores more accessible and its surface groups more exposed, which enhances its electrochemical performance. Its specific capacitance maintains as high as 525.0 F g^-1 even at 50 A g^-1. The assembled Ex-Pc-based symmetric supercapacitor achieves high energy density of 16.6 Wh kg^-1 at a power density of 69.4 W kg^-1, and demonstrates a capacitance retention of 95.1% after 43,000 cycles. This work validates the feasibility of enhancing capacitance by exocarp-mesocarp-endocarp anatomical engineering and opens a gap for preparing homogeneous biomass-derived porous carbon microstructures.