Nitrogen-doped carbon spheres-decorated graphite felt as a high-performance electrode for Fe based redox flow batteries

Anarghya Dinesh,Mylarapattana Shankaranarayana Anantha,Mysore Sridhar Santosh,Muniswamy Narendra Kumar,Krishna Venkatesh,Handanahalli Basavarajaiah Muralidhara

doi:10.1016/j.diamond.2021.108413

Anarghya Dinesh, Mylarapattana Shankaranarayana Anantha + Show 4 more

Open Access

https://doi.org/10.1016/j.diamond.2021.108413

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Abstract

In this paper, the performance of Fe-based redox flow batteries (IRFBs) was dramatically improved by coating N-doped carbon spheres (NDCS) on the graphite felt electrodes. NDCS was synthesized by the single-step hydrothermal method using dextrose and ammonia as a precursor and coated over graphite felt electrodes by electrostatic spraying. The weight of NDCS required for the modification of the electrode to achieve the effective performance of the battery was studied using electrochemical techniques. Cyclic voltammetry (CV) and potentiodynamic polarization study was used to evaluate the kinetic reversibility and linear polarization resistance offered by the electrode towards electrolyte. The characterizing features of the NDCS, untreated graphite felt (UGF) electrode and optimized modified graphite felt (MGF) electrode were analyzed using SEM, EDAX, XRD, and Raman spectroscopy. The charge-discharge studies were performed for the 132 cm2 IRFB using a 2 mg/cm2 MGF electrode as a positive electrode by varying the current densities from 20 to 60 mA/cm2. The cell resulted in an average coulombic efficiency (CE) of 93%, voltaic efficiency (VE) of 72%, and energy efficiency (EE) of 68% for 15 cycles at the current density of 30 mA/cm2. The improvement in the performance of the IRFB is due to the presence of electrochemically active nitrogen-bearing carbon catalysts. In this paper, the pioneering effort has been made to improve the efficiency of the IRFB with an active area of 132 cm2 using glycine as the ligand.

Highlights

Storage of energy harvested from renewable sources of energy such as wind, solar, hydro, etc is of major interest in the current scenario [1, 2]
The results indicate the shift in the oxidation peak potential of 2 mg/cm2 modified graphite felt (MGF) electrode towards a negative direction as shown in the figure
The Iron redox flow batteries (IRFBs) are considered as the futuristic way of energy storage devices, with environmental-friendly and cost-effective electrolyte

Summary

Introduction

Storage of energy harvested from renewable sources of energy such as wind, solar, hydro, etc is of major interest in the current scenario [1, 2]. Carbon-based electrodes are the majorly used in the field of redox flow batteries because of their low cost, high stability, corrosion resistance, and high conductivity These are poor in kinetic reversibility and electrochemical activity [17, 18]. The recent studies carried out for the electrode modification in IRFB using nitrogen-doped carbon particles and metal oxide composite reported good cycle life and kinetic reversibility towards Fe3+/Fe2+ reaction using ascorbic acid and glycine as the ligand respectively [18, 19]. There are no reports available on the modification of electrode for IRFBs with a larger active area of the cel l [13, 15, 32, 33] This is novel and potential work in the field of IRFBs to propose an effective catalyst for the modification of a positive electrode to increase the battery efficiencies.

Findings

Result and Discussion Electrochemical measurements

Conclusion