A Sulfonated Polyimide/Nafion Blend Membrane with High Proton Selectivity and Remarkable Stability for Vanadium Redox Flow Battery.

Jinchao Li,Jun Liu,Jun Long,Zhen He,Suqin Liu,Yaping Zhang,Wenjie Xu,Wenheng Huang

doi:10.3390/membranes11120946

Jinchao Li, Jun Liu + Show 6 more

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https://doi.org/10.3390/membranes11120946

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Abstract

A sulfonated polyimide (SPI)/Nafion blend membrane composed of a designed and synthesized SPI polymer and the commercial Nafion polymer is prepared by a facile solution casting method for vanadium redox flow battery (VRFB). Similar molecular structures of both SPI and Nafion provide good compatibility and complementarity of the blend membrane. ATR-FTIR, 1H-NMR, AFM, and SEM are used to gain insights on the chemical structure and morphology of the blend membrane. Fortunately, the chemical stability of the SPI/Nafion blend membrane is effectively improved compared with reported SPI-based membranes for VRFB applications. In cycling charge-discharge tests, the VRFB with the as-prepared SPI/Nafion blend membrane shows excellent battery efficiencies and operational stability. Above results indicate that the SPI/Nafion blend membrane is a promising candidate for VRFB application. This work opens up a new possibility for fabricating high-performance SPI-based blend membrane by introduction of a polymer with a similar molecular structure and special functional groups into the SPI polymer.

Highlights

Clean and renewable energy sources such as wind and sunlight have gained much attention due to their low environmental impact, abundant reserve, and extensive distribution [1]
The sulfonated polyimide (SPI) polymer needs to be dissolved in an organic solvent before addition of Nafion solution during preparation of SPI/Nafion blend membrane
It is observed that the SPI polymer can be dissolved in various common organic solvents such as m-cresol, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N-methyl-2pyrrolidone (NMP), and N,N-dimethylacetamide (DMAc) to form clear and homogeneous solutions

Summary

Introduction

Clean and renewable energy sources such as wind and sunlight have gained much attention due to their low environmental impact, abundant reserve, and extensive distribution [1]. These renewable energy sources are unpredictable and fluctuant with time and season. An ideal PCM should possess a low vanadium ion permeability, high proton conductivity, excellent chemical stability, and low cost [9,10]. The most widely used PCMs are perfluorosulfonic acid membranes, such as Nafion series membranes from DuPont Co., USA, which possess excellent proton conductivities and chemical stability [11,12,13].

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