Flexible, Stackable, and Fully Active Thick Electrode with Scalable 3D Topology Braid Structure Enables Supercontinuous Electron/Ion Transport

Abstract Thick electrode design is critical for achieving high energy/power density storage. However, it remains a huge challenge to design a fully‐active thick electrode with supercontinuous electron/ion transport channels by a cost‐effective method. Herein, a flexible, stackable, and fully‐active, fully‐microporous carbon cloth (FMCC) cathode is developed from cotton cloth by a facile strategy for lithium‐ion capacitors (LICs). Fully microporous structure achieves a large specific surface area while retaining a self‐supporting structure. The bi‐directional woven hollow fiber bundle structure achieves supercontinuous ion/electron transport. Significantly, the FMCC can be flexibly stacked in multiple layers to form a 3D topological network structure, achieving a high‐performance thick electrode design. Consequently, the 5‐layer FMCC delivers ultrahigh area‐specific capacity of 1.53 mA h cm ⁻² even at 1 A g ⁻¹ with almost undiminished mass‐specific capacity compared to single‐layer FMCC. Furthermore, a 4.9 V LIC is assembled based on a carbon cloth cathode/anode with a thick electrode design, realizing an excellent energy/power density. Assembled flexible LIC delivers stable power output even under bending/cutting conditions due to the unique electrode structure. In addition, the charge/discharge mechanism and structure–activity relationship of the FMCC are revealed in detail, which provides a constructive view for designing flexible, fully‐active thick electrodes.