High-Capacity CuSi₂P₃-Based Semisolid Anolyte for Redox Flow Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Redox flow batteries (RFBs) offer decoupled energy and power but suffer from low energy density.
• Semisolid flow batteries (SSFBs) present a solution with higher energy density, yet research on semisolid anolytes remains limited.
• The development of advanced anolytes is crucial for the widespread adoption of SSFBs.

Purpose of the Study:

• To synthesize and characterize a novel semisolid anolyte for SSFBs.
• To investigate the impact of binder addition on the anolyte's performance and suspension stability.
• To evaluate the electrochemical performance of the developed anolyte in full-cell configurations.

Main Methods:

• Synthesis of a CuSi2P3@C-LiPAA composite anolyte using high-energy mechanical ball milling and impregnation.
• Preparation of semisolid anolytes with and without binder for performance evaluation.
• Assembly and testing of single-cell SSFBs using the synthesized anolyte paired with different catholytes (MPT and LFP).

Main Results:

• The synthesized CuSi2P3@C-LiPAA semisolid anolyte achieved a record volumetric capacity of 400 Ah L⁻¹ (static) and 320 Ah L⁻¹ (intermittent-flow).
• Binder addition improved particle connectivity and suspension uniformity, leading to stable electrochemical performance.
• Full cells demonstrated a 3 V single-cell voltage and over 100 stable cycles with 99% coulombic efficiency when paired with MPT or LFP catholytes.

Conclusions:

• The developed CuSi2P3-based semisolid anolyte shows significant potential for high-energy-density SSFBs.
• The binder incorporation strategy offers a pathway for optimizing semisolid suspensions for various active materials.
• This work advances the application of SSFBs by addressing the critical need for high-performance anolytes.