PDF Publication Title:
Text from PDF Page: 013
2. MembranedevelopmentforV/VsystemSystem The ion exchange membrane is one of the most important components in the RFB system; it prevents the crossover of the active materials in the positive and negative electrolyte while allowing proton transport to complete the circuit. Perflourinated polymers such as Nafion (Dupont) have been often used in the VRB system because of their excellent chemical stability in the highly oxidative V5+ environment and high proton conductivity. The high price of the Nafion membrane, however, accounts for over 40% of the cell stack cost[24]. As such, search for low-cost substitutes has been a major effort in advancing the redox flow batteries. Several lower-cost non- perfluorinated polymer membranes were evaluated by others for the VRBs. So far there has been no low-cost alternative that can match the Nafion membranes in terms of conductivity, selectivity and chemical stability.[35,36] In the first quarter, PNNL extensively explored the replacement of the expensive perfluorinated Nafion® ion exchange membrane by low-cost hydrocarbon-based membrane. we have previously developed a sulfonated poly(arylene ether) membrane (S-Radel) having one order of magnitude lower permeability of VO2+ than Nafion 117, which resulted in higher coulombic efficiency and lower capacity loss per cycle.19 However, the cell performance declined rapidly after 40 cycles due to physical and/or chemical degradation by VO2+.36 In a continuous collaboration with the membrane team at the Pennsylvania State University, University Park, PA, we developed partially fluorinated sulfonated poly(arylene ether) (SFPAE) copolymers with a range of ion exchange capacities (IECs) as chemically stable proton exchange membranes for vanadium redox flow battery (VRFB) applications. Fluorinated poly(arylene ether)s (FPAE) were successfully synthesized by reacting decafluorobiphenyl and biphenol A at room temperature for 24h. The influence of IEC on membrane water uptake, mechanical properties, thermal and oxidative stability, proton conductivity, and VO2+ permeability was studied. Improved stability was observed for SFPAEs as compared to non-fluorinated samples. SFPAE-1.8 with optimized proton conductivity to vanadium permeability selectivity was selected for evaluation in VRFB and compared to the performance of a cell with NAFION® N212 membrane. VRFB with SFPAE-1.8 membrane had higher coulombic efficiencies, voltage efficiencies and energy efficiencies than VRFB with N212 membrane under all tested current densities. The capacity fade of VRFB with SFPAE-1.8 membrane was 1.1 mAh per cycle, which was about 7 times lower than the fade experienced in a VRFB with an N212 membrane. The cycling performance comparison of VRB with N212 and membranes at 50mA/cm2 are provided at Figure 6. From a cost effective of view, SFPAE-1.8 is about 30% of the cost of the NAFION® N212. This work demonstrates our progress towards high-performance, low-cost, long-lifetime ion exchange membranes for electrochemical energy storage devices. 10PDF Image | Redox Flow Batteries for Stationary Electrical Energy Storage
PDF Search Title:
Redox Flow Batteries for Stationary Electrical Energy StorageOriginal File Name Searched:
PNNL-21174.pdfDIY PDF Search: Google It | Yahoo | Bing
Salgenx Redox Flow Battery Technology: Salt water flow battery technology with low cost and great energy density that can be used for power storage and thermal storage. Let us de-risk your production using our license. Our aqueous flow battery is less cost than Tesla Megapack and available faster. Redox flow battery. No membrane needed like with Vanadium, or Bromine. Salgenx flow battery
| CONTACT TEL: 608-238-6001 Email: greg@salgenx.com | RSS | AMP |