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Updated: Jun 9, 2026
09:49
A Protocol for Electrochemical Evaluations and State of Charge Diagnostics of a Symmetric Organic Redox Flow Battery
Published on: February 13, 2017
Development of a Stable Electrolyte for Dendrite Suppression and High-Performance Zn-I2 Redox Flow Battery
Aparnasree Moothedath1,2, Mohanraj Madeshwaran2,3, Anjana Puthanpurayil Jayarajan4
1Department of Chemistry, Amrita School of Physical Sciences Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore, India.
Small (Weinheim an Der Bergstrasse, Germany)
|June 8, 2026
Summary
Ammonium chloride enhances zinc-iodide flow batteries by improving stability and efficiency. This electrolyte addition prevents issues like dendrite growth, enabling over 1000 stable cycles.
Area of Science:
- Electrochemistry
- Materials Science
- Energy Storage
Background:
- Zinc-iodide (Zn-I2) redox flow batteries offer low cost and high energy density.
- Key challenges include low iodine utilization, shuttle effect, and anode degradation (Zn dendrites, dead Zn).
- These issues limit long-term cycling stability and practical application.
Purpose of the Study:
- To enhance the performance and cycling stability of Zn-I2 flow batteries.
- To investigate the role of ammonium chloride (NH4Cl) as a neutral supporting electrolyte.
- To mitigate issues like iodine precipitation and zinc anode instability.
Main Methods:
- Utilizing a bifunctional ammonium chloride (NH4Cl) supporting electrolyte in both catholyte (KI + NH4Cl) and anolyte (ZnCl2 + NH4Cl).
- Analyzing the formation of the I2Cl- complex to reduce iodine precipitation.
- Evaluating anode stability and dendrite formation mitigation strategies.
Main Results:
- The NH4Cl-modified flow cell demonstrated remarkable stability over 1000 cycles at 30 mA cm-2.
- Achieved high coulombic efficiency (CE) of 93.83% and energy efficiency of ~75%.
- Reached a maximum power density of 74.8 mW cm-2, significantly outperforming cells without NH4Cl.
Conclusions:
- Ammonium chloride is a safe, low-cost, and effective supporting electrolyte for Zn-I2 flow batteries.
- NH4Cl successfully suppresses iodine precipitation and anode degradation, leading to enhanced stability.
- The improved Zn-I2 flow cell shows significant potential for efficient and durable energy storage.
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