PDF Publication Title:
Text from PDF Page: 005
Introduction The demand for large-scale electrical energy storage (EES) devices has been growing for both improved efficiency and flexibility of the current grid infrastructure and to enable a higher penetration of stochastic renewable sources such like solar and wind onto the grid. Among the most promising technologies for the grid-scale EES are redox flow batteries (RFBs), which are capable of storing a large quantity of electricity (multi-MWs/MWhs) in a relatively simple and straightforward design.1,2 There are several RFB technologies including polysulfide/bromide,3,4 all vanadium,5-8 Fe/Cr,9 and etc2, however, the all-vanadium redox flow battery (VRFB) has received significant attention because of its excellent electrochemical reversibility, high round-trip efficiency, and negligible cross-contamination between positive and negative electrolytes.10 Systems up to multi-MWs have been demonstrated for grid applications and renewable integration.10 Even though the VRFB technology has several advantages over the conventional Li ion or lead acid batteries, high capital cost is one major challenge for the widespread deployment of VRFB’s. The high cost of these systems can be attributed to several factors, including the use of expensive vanadium, costly Nafion® membrane and the need of an additional heat exchanger system to help maintain the electrolyte temperature between 25 and 35 oC in order to prevent precipitation of the conventional pure sulfate electrolyte. Recently, PNNL scientists11 made a dramatic improvement in the thermal stability and solubility of the conventional pure sulfate VRFB system by developing a mixed acid (hydrochloric and sulfuric acid) supporting electrolyte. In small-scale, single flow cell tests, electrolytes with up to 2.5 M vanadium in the mixed acid electrolyte (vs. < 1.6 M for the conventional VRFB) demonstrated stable charge/discharge cycling operation over a temperature range of -5 ~ 50 °C. In addition to the increased concentration, the addition of chloride ions also reduced the viscosity of the electrolyte12, potentially reducing the power consumption required for pumping the electrolyte through the cell. In FY12, PNNL demonstrated a 1 kW / 1 kWh scale prototype stack and system in order to validate the improved mixed acid electrolyte in a larger scale system. This system successfully increased the maximum operating current density of the stack from 50 to 80 mA/cm2 (>50% increase) while achieving a ~ 25% increase in the energy density of the system through the enhanced vanadium solubility of the mixed acid electrolyte. As tested, the 1.0 kW /1.0 kWh prototype system was able to deliver a continuous power of 1.1 kW in the operating range of 5PDF Image | High Current Density Redox Flow Batteries
PDF Search Title:
High Current Density Redox Flow BatteriesOriginal File Name Searched:
PNNL-23819-4.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 (Standard Web Page)