Nanostructured Carbon Fiber Current Collector Enabling High Mass-Loading Electrodes for High-Performance Electrochemical Desalination

Abstract

Capacitive deionization (CDI) is a promising desalination technology for relieving freshwater shortage. However, designing and fabricating high mass-loading and high-performance CDI electrodes, so as to meet the practical demand (~ 10 mg cm⁻²) and to improve the areal capacity of CDI devices, still remain challenging. Herein, we propose a current collector-structuring strategy to fabricate MnO₂@CSA and BiOCl@CSA electrodes, via pre-constructing highly ordered porous carbon nanosheet arrays on carbon fibers (CSA) and then depositing MnO₂ or BiOCl. It was demonstrated that compared with conventional planar current collector, the surface nanostructuring of carbon fibers can effectively reduce the thickness of the active material layer by approximately 26-fold at high mass loadings (> 20 mg cm⁻²), thereby greatly shortening both ion and electron transport distances. Meanwhile, the open 3D array network of MnO₂@CSA and BiOCl@CSA electrodes endows them with fast kinetics for ion diffusion and adsorption. Consequently, with an overall mass loading of approximately 24 mg cm⁻², the MnO₂@CSA||BiOCl@CSA cell delivers impressive areal and gravimetric salt adsorption capacities (0.72 mg cm⁻² and 30.8 mg g⁻¹), along with excellent cycling stability. Our study reveals that rational design of the current collector microstructure can significantly enhance the mass-loading and desalination performance of CDI electrodes, thereby better meeting practical requirements and offering great promise for CDI applications.

Graphical abstract

Keywords

Capacitive deionization / Current collector / Mass loading / Carbon array / Carbon fiber

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Funding

Natural Science Foundation of China (22072070)

Natural Science Foundation of China(U1910208)

Natural Science Foundation of Shandong Province(ZR2023QB034)

Shanxi Province Transformation Program of Scientic and Technological Achievements(No. 202304021301032)

Shanxi Province Special Project for Scientific and Technological Cooperation and Exchange(No. 202404041101024)

RIGHTS & PERMISSIONS

Donghua University, Shanghai, China