Titanium Nitride Nanorods Array‐Decorated Graphite Felt as Highly Efficient Negative Electrode for Iron–Chromium Redox Flow Battery

Abstract

Iron‐chromium redox flow batteries have attracted widespread attention because of their low cost. However, the performance of these batteries is still lower than that of vanadium redox flow batteries due to the poor electrochemical activity of Cr3+/Cr2+ redox couples on graphite felt electrodes. Herein, binder‐free TiN nanorods array—decorated 3D graphite felt composite electrode—is demonstrated. The dendrite‐like TiN nanorods array increases the specific surface area of the electrode. The nitrogen and oxygen elements on the surface provide more adsorption sites and electrochemically active sites for Cr3+/Cr2+. The contact resistance of the composite electrode is effectively reduced and its homogeneity and stability are improved by avoiding the use of a binder and mixing process. A battery prepared using the TiN nanorods array‐decorated 3D graphite felt electrode has enabled the maximum power density to be 427 mW·cm‐2, which is 74.0% higher than a battery assembled with TiN nanoparticles bonded to graphite felt. At a current density of 80 mA·cm‐2, the TiN nanorods battery exhibits the highest coulombic efficiency of 93.0%, voltage efficiency of 90.4%, and energy efficiency of 84.1%. Moreover, the battery efficiency and composite electrode structure remains stable during a redox flow battery cycle test.

Titanium nitride (TiN) as a promising alternative to plasmonic metals: a comprehensive review of synthesis and applications

“…Recently, Liu et al (2023) developed a binder-free composite electrode by growing TiN nanorods arrays on 3D graphite felt. 189 This composite electrode exhibited improved electrochemical activity, leading to a significant increase in maximum power density (427 mW cm −2 , 74.0% higher compared to TiN nanoparticles). The electrode also demonstrated excellent coulombic efficiency (93.0%), voltage efficiency (90.4%), and energy efficiency (84.1%) at a current density of 80 mA cm −2 .…”

The design engineering of nanocatalysts for high power redox flow batteries

“…In tandem with the integration of nanometal catalysts into iron-chromium RFBs, the exploration of metal oxides and metal nitrides as catalysts has gained attention, aiming to bolster the reaction kinetics of Cr 3+ /Cr 2+ and consequently augment the energy efficiency of batteries. 12,74 Dendritic TiN electrode materials grown in situ on graphite felt can significantly improve the electrochemical kinetics due to their magnified specific surface area and abundant catalytic active sites. 74 The combination of nitrogen and oxygen moieties on the surface facilitated an increase in both adsorption sites and electrochemical active sites pertinent to the Cr 3+ /Cr 2+ redox couple.…”

“…12,74 Dendritic TiN electrode materials grown in situ on graphite felt can significantly improve the electrochemical kinetics due to their magnified specific surface area and abundant catalytic active sites. 74 The combination of nitrogen and oxygen moieties on the surface facilitated an increase in both adsorption sites and electrochemical active sites pertinent to the Cr 3+ /Cr 2+ redox couple. The resultant iron-chromium RFBs, fashioned using 3D graphite felt electrodes modified with TiN nanorod arrays, demonstrated a striking maximum power density of 427 mW cm −2 .…”

Reduced graphene oxide/MXene hybrid decorated graphite felt as an effective electrode for vanadium redox flow battery

“…However, the utilization of graphite felt still faces challenges due to its poor electrochemical activity, leading to insufficient active sites for vanadium redox reactions. 15,16 To improve the reaction kinetics of three-dimensional porous electrodes, various methods have been reported, including surface modications to introduce chemical groups (e.g., thermal treatment, 17 acid treatment, 18 and microwave radiation treatment 19 ), surface etching to improve the surface area or pore structures (CO 2 etching, 20,21 water etching, 22 KOH etching 23,24 ), and catalyst loading to enhance catalytic activity of electrode. Among these methods, loading catalysts on electrode to enhance electrode reaction kinetics is the most effective and commonly used approach.…”