Flow-electrode capacitive deionization utilizing three-dimensional foam current collector for real seawater...

Area of Science:

• Electrochemistry
• Materials Science
• Environmental Engineering

Background:

• Capacitive deionization (CDI) is a promising technology for water desalination.
• Traditional CDI devices face limitations in charge transfer efficiency and effective charging range.
• Flow-electrode CDI (FCDI) offers improved performance but requires optimized current collectors.

Purpose of the Study:

• To develop and evaluate a three-dimensional (3D) carbon coated nickel foam as a current collector for FCDI devices.
• To enhance the charge transfer ability and overall desalination efficiency of FCDI systems.
• To demonstrate the effectiveness of the 3D foam current collector for real seawater desalination.

Main Methods:

• Fabrication of a 3D carbon coated nickel foam current collector.
• Integration of the 3D foam into a flow-electrode capacitive deionization (FCDI) device.
• Performance evaluation using NaCl solutions and real seawater samples, including salt removal efficiency (SRE), average salt removal rate (ASRR), and charge efficiency (CE).
• Comparison with traditional current collectors (titanium mesh and graphite plate) using computational fluid dynamics (CFD) simulations.

Main Results:

• The CF-FCDI device with 3D carbon coated nickel foam achieved 99.8% SRE, 3.29 µmol cm⁻² min⁻¹ ASRR, and 97.0% CE for 3.5 g L⁻¹ NaCl solution.
• The 3D foam structure enhanced charge transfer by increasing contact area and eliminating charging range restrictions.
• Simulations confirmed the superior competitiveness of the 3D foam current collector over titanium mesh and graphite plate.
• Excellent desalination performance was validated with simulated and real seawater samples from the Yellow Sea and South China Sea.

Conclusions:

• The 3D carbon coated nickel foam is a highly effective current collector for FCDI devices.
• This novel approach significantly enhances charge transfer and desalination efficiency, particularly for real seawater.
• The study presents a new strategy for advancing FCDI technology for efficient and practical water desalination.