Crystallinity‐Engineered Three‐Dimensional Graphitic Carbon Tube Grids as Load‐Tolerant Electrodes for AC Line‐Filtering Capacitors

ABSTRACT Three‐dimensionally (3D) architected carbons with oriented nanopores provide a promising platform for AC line‐filtering electric double‐layer capacitors (EDLCs). However, their performance, particularly at high electrode loading, is fundamentally constrained by insufficient electronic conduction—an intrinsic but largely overlooked limitation. Here, we develop a crystallinity‐engineered, highly conductive 3D graphitic carbon tube grid (3D‐GCTG) using a 3D nickel nanorod grid (3D‐NiNRG) as both structural template and catalytic framework. A central advance lies in elucidating and resolving structural collapse and granulation in 3D‐NiNRG during catalytic graphitization, enabling a fully interconnected, well‐graphitized carbon network with a predefined 3D microstructure. A direct comparison between two carbon tube grids with identical structures and thicknesses but different crystallinities unambiguously reveals the crystallinity‐enabled enhancement in frequency response. This synergistic ion‐electron transport allows the 3D‐GCTG to function as a load‐tolerant electrode, effectively decoupling areal capacitance from phase angle. In a two‐electrode configuration, the 3D‐GCTG maintains a phase angle below −80° at 120 Hz even at 40 µm, delivering a high areal capacitance of 3.77 mF cm −2 , a 3.6‐fold improvement over the previously reported non‐graphitized counterpart. This work establishes graphitization‐enabled transport engineering as a general strategy for overcoming the long‐standing capacitance‐response trade‐off, offering a versatile platform for high‐performance AC‐filtering EDLCs.