Novel sulfonated polyimide/ZrO₂composite membrane as a separator of vanadium redox flow battery

Abstract

Sulfonated polyimide (SPI) and ZrO 2 are blended to prepare a series of novel SPI/ZrO 2 composite membranes for vanadium redox flow battery (VRFB) application. Results of atomic force microscopy and X-ray diffraction reveal that ZrO 2 is successfully composited with SPI. All SPI/ZrO 2 membranes possess high proton conductivity (2. ). SPI/ZrO 2 -15% membrane is determined as the optimum one on account of its higher proton selectivity and improved chemical stability. The VRFB with SPI/ZrO 2 -15% membrane presents higher coulombic efficiency and energy efficiency than that with Nafion 117 membrane at the current density, which ranged from 20 to 80 mA cm À2. Cycling tests indicate that the SPI/ZrO 2 -15% membrane has good operation stability in the VRFB system.

Synthesis and properties of branched sulfonated polyimides for membranes in vanadium redox flow battery application

“…L is distance (cm) between both potential-sensing electrodes. Test VO 2+ permeability by similar procedures at room temperature [39]. The VO 2+ permeability is determined using Eq.…”

Recent development of polymer membranes as separators for all-vanadium redox flow batteries

“…The membrane separator is the key material for commercialization of redox batteries because it decides the 45 performance (both cyclability and efficiencies), and its cost can be up to 20 % of the whole battery system. 3 Thus, many research groups all over the world focus on investigating, finding and developing the right membrane for VRFBs, which provides good performance but low cost.…”

“…However, water loss due to acid presence lead to significant decrease of the proton mobility. Thus, acid and water contents in the membrane 45 are crucial parameters which define ionic conductivity of the membrane. When VO 2+ is in the membrane equilibrated in diluted acid, it can compete and reduce proton concentration and proton mobility, leading to the decrease in membrane conductivity.…”

“…As a consequence, VO 2+ permeability drops dramatically. In fact, proton conductivity and VO 2+ permeability are not dependable on the existence of GO phase, 45 thus it is reasonable to conclude that the preparation method leads to the desired changes in parameters, not because of the introduction of GO phase. On the other hand, Kim et al investigated the properties of sulfonated graphene oxide (sGO)/Nafion composite membranes in VRFBs.…”

Sulfonated poly(imide-siloxane) membrane as a low vanadium ion permeable separator for a vanadium redox flow battery

“…The VO 2+ permeability measurement was conducted in a membraneseparated cell using the standard procedure as reported in the literature at 25°C. 12 The VO 2+ permeability was determined using equation (6):…”