Graphite felt modified with bismuth nanoparticles as negative electrode in a vanadium redox flow battery

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Vanadium redox flow batteries (VRFBs) are promising for large-scale energy storage.
• Improving the efficiency and cycle life of VRFBs is crucial for their commercial viability.
• The negative electrode is a key component affecting VRFB performance, particularly concerning V(3+)/V(2+) redox reactions and parasitic hydrogen evolution.

Purpose of the Study:

• To investigate the electrochemical performance of graphite felt modified with bismuth nanoparticles as a negative electrode in VRFBs.
• To elucidate the mechanism by which bismuth nanoparticles influence the redox reactions and Coulombic efficiency.
• To assess the long-term cycling stability of the bismuth-modified electrode.

Main Methods:

• Electrochemical characterization of bismuth-modified graphite felt electrodes.
• Cyclic voltammetry and galvanostatic cycling to evaluate performance.
• Analysis of reaction mechanisms and intermediate species.

Main Results:

• The bismuth-modified graphite felt electrode demonstrated excellent electrochemical performance.
• High reversibility of the V(3+)/V(2+) redox reactions was observed.
• Significant improvement in long-term cycling stability and Coulombic efficiency due to inhibited hydrogen evolution.

Conclusions:

• Bismuth nanoparticles play a crucial role in enhancing VRFB negative electrode performance.
• The proposed mechanism involves Bi nanoparticles favoring the formation of BiHx, an intermediate that promotes V(3+) to V(2+) reduction and suppresses hydrogen evolution.
• This modification leads to a highly reversible and efficient VRFB process, addressing key limitations in current technology.