Title: Enabling high rate capability, low internal resistance, and excellent cyclability for vanadium redox flow batteries utilizing ultrafast laser-structured graphite felt

Abstract

The electrochemical performance of vanadium redox flow batteries (VRFBs) was enhanced via laser-patterned graphite felt (GF) electrodes. The laser-structured GF electrodes engineered via preparing a series of well-ordered microscopic channel structures with an average width of 200 μm, creating a three-dimensional carbon framework. The ultrafast laser patterning increased the porosity by 10%, as compared to pristine electrode. The analysis of the overpotential distribution using electrochemical impedance spectroscopy revealed that the electrode polarization involving charge transfer and diffusion resistance is strongly alleviated with the aid of carbon micro-perforation. The advanced design of laser-structured GF electrode also exhibits high rate capability, low internal resistance, and excellent cyclability. The improved performance was attributed to the synergistic effect involving (i) high electrochemically active surface area for rapid electrochemical reactions (i.e., V(II)/V(III) and V(IV)/V(V) redox couples) and (ii) excellent transport properties for facile electron/ion/species transport. The micro-scale channels created with the laser-ablation technique act as capillary structures and enabled homogeneous and rapid wetting of GF electrodes as formulated with the classical Washburn equation. The VRFB equipped with the laser-structured GF electrodes delivered a high discharge capacity with exceptional capacity retention upon extended cycling (>84.9%). In conclusion, accordingly, the design of laser-structured electrode paves the pathwaymore » towards finely tuning the electrode internal microstructure for improved cyclability, durability, and capacity retention in various electrochemical energy storage/conversion devices (e.g. all-vanadium redox flow batteries).« less

Authors:

Daugherty, Michael C. ^[1]; Hsieh, Chien-Te ^[2]; Aaron, Doug S. ^[1]; Ashraf Gandomi, Yasser ^[3]; Li, Jianlin  ^[4];

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Zheng, Yijing ^[5]; Pfleging, Wilhelm ^[6]

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+ Show Author Affiliations

1. Univ. of Tennessee, Knoxville, TN (United States)
2. Univ. of Tennessee, Knoxville, TN (United States); Yuan Ze Univ., Taoyuan (Taiwan)
3. Massachusetts Inst. of Technology, Cambridge, MA (United States)
4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
5. Karlsruhe Inst. of Technology (KIT) (Germany)
6. Karlsruhe Inst. of Technology (KIT) (Germany); Karlsruhe Nano Micro Facility (KNMF), Eggenstein-Leopoldshafen (Germany)

Publication Date:

Sat Apr 04 00:00:00 EDT 2020

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE; Ministry of Science and Technology of Taiwan (MOST); German Research Foundation (DFG)

OSTI Identifier:

1609038

Grant/Contract Number:  

AC05-00OR22725

Resource Type:

Accepted Manuscript

Journal Name:

Electrochimica Acta

Additional Journal Information:

Journal Volume: 344; Journal Issue: C; Journal ID: ISSN 0013-4686

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

25 ENERGY STORAGE; Vanadium redox flow battery; Ultrafast laser structuring; Graphite felt; Electrochemical performance; Electrode design