Construction of Hydrophilic Percolation Networks in Physical Wet‐Mixed Carbon Electrodes for High‐Rate Capacitive Deionization

Capacitive deionization (CDI) using activated carbon (AC) electrodes holds great promise for seawater desalination, yet its practical application is severely constrained by the intrinsic hydrophobicity of carbon surfaces. Herein, we propose a solid‐state superhydrophilic modulation strategy that physically wet‐mixes superhydrophilic MOF‐derived hollow carbon nanocages (CMNC) with commercial AC to obtain a carbon‐based pseudocapacitive electrode composite. This simple blending directly imparts superhydrophilicity to the AC surface (contact angle as low as 5.11°) through constructing hydrophilic percolation networks, which effectively alleviates the diffusion limitation of Cl − ions by optimizing interfacial wettability, while preserving the intrinsic electrochemical performance of the metal‐organic framework‐derived (MOF‐derived) nanocages despite dilution. The blending of the CMNC with different nanocarbons (activated carbon/AC, carbon nanotube/CNT, graphene oxide/GO) and its impact on wettability and CDI performance were also examined. The optimal CMNC 1 AC 1 electrode (mass ratio 1:1) achieves a salt adsorption capacity of 57.2 mg g −1 , a desalination rate of 1.91 mg g −1 min −1 , and a charge efficiency of 87.46% in 500 mg L −1 NaCl at 1.2 V. This performance approaches that of pure CMNC and far exceeds AC, yet utilizes only half the MOF‐derived material, demonstrating the synergistic coupling of high surface area of AC and pseudocapacitive activity of CMNC within the hydrophilic percolation network. The system is further extendable to solar‐powered desalination and simultaneous removal of multiple pollutants, showing the potential for addressing complex wastewater. Most importantly, this physical wet‐mixing strategy enables carbon‐based composite electrodes to achieve performance comparable to advanced MOF‐derived materials at substantially reduced cost and processing complexity. This work provides a scalable and cost‐effective concept of using solid‐state superhydrophilic modifiers to overcome the Cl − diffusion bottleneck in low‐cost carbon electrodes for high‐performance capacitive deionization.