Synergistic enhancement of electric double layers and faradaic reactions in capacitive deionization: The role of NTP@C composite

Capacitive Deionization (CDI) has received attention for its energy efficiency and minimal environmental impact, but it faces practical limitations due to the constrained desalination capacity of conventional systems. Our study addresses this challenge by introducing a novel electrode material, NaTi2(PO4)3 (NTP) coated with interconnected mesoporous carbon (NTP@C). This innovative material leverages the synergistic effects of electric double layers and faradic reaction conversion faradic. Unlike traditional carbon coating, our new strategy significantly changes the shape of NTP from coral to ellipse, significantly shortening the diffusion path of sodium ions (Na+), thus accelerating the mass transfer kinetics. Comprehensive morphological, structural, and electrochemical analyses reveal that NTP@C outperforms traditional electrodes in terms of electrochemical stability, ion transmission rates, and desalination capacity. At 1.8 V and 3 g/L NaCl concentration, NTP@C achieves a remarkable salt adsorption capacity of 233.07 mg g−1, with a desalination capacity growth rate of 188 % between 1.4 V and 1.6 V—surpassing the 159 % growth rate of NTP. Additionally, NTP@C exhibits higher cycle performance, maintaining 89.42 % stability over 50 cycles compared to NTP's 74.39 %. The innovative carbon coating technique prevents NTP particle agglomeration, enhances conductivity, and increases the specific surface area, culminating in a unique interconnected and wrapped carbon structure. This results in an exceptional synergy between the electric double layer and faradic reaction conversion faradic, propelling NTP@C to outstanding desalination performance and cycle stability.