PDF Publication Title:
Text from PDF Page: 016
full cell is built with LiCoO2 (20 vol % and 10.2 M) as the catholyte versus Li4Ti5O12 (10 vol % and 2.3 M) as the anolyte, and the specific capacity based on Li4Ti5O12 can reach $170 mAh g1 at 1/8 C, approaching its theoretical capacity. The authors further calculated the theoretical energy densities of different electrode combina- tions. It is estimated that the LiCoO2/Li4Ti5O12 system can achieve 397 Wh L1, while the LiNi0.5Mn1.5O4/Li4Ti5O12 alternative can reach 353 Wh L1 and the LiCoO2/ graphite pair can deliver 615 Wh L1. It is also evidenced that such a RFB can operate at relatively low flow rates with minimized energy consumption on pumping. Since then, some other types of electrode materials for Li-ion batteries have been explored in RFB applications. Tarascon and coworkers reported the Si-based anolyte consisting of 100 nm Si nanoparticles, carbonate Li-ion electrolytes, and conductive ad- ditives.75 Capacity up to 2,800 mAh g1 was delivered with high Coulombic efficiency (>98%) and low polarization (<150 mV) in a half-cell test. Biendicho et al. investigated LiNi1/3Co1/3Mn1/3O2-based suspensions in similar semi-solid RFBs and also investigated the cell resistance in detail via impedance spectroscopy.76 Notably, the improved concentration of redox species is inevitably accompanied by higher viscosities, which give rise to higher driving pressures and greater flow resis- tance. The sluggish reaction and diffusion dynamics further aggravate the potential hysteresis. More seriously, the flow channel may be blocked considering the possible precipitation of bulky aggregates. To alleviate the serious polarization issue, Chiang and coworkers further investigated a percolating nanoscale conductor networks by incorporating 3D conductive carbon particles (Ketjenblack) into the flowable electrodes (Figure 8B).77 In conventional cell architectures, redox reactions can only occur on the current collectors, and concentration polarization contributes greatly to the potential hysteresis especially in highly viscous electrolytes. In this work, the electrode materials are well distributed in the conducting framework, and the electroactive zone is extended throughout the cell volume. When sulfur is paired with Li metal to build the proof-of-concept battery, the suspension electrode delivers a capacity of 1200 mAh g1 at 1/4 C, which is almost six times more than that in a conventional RFB architecture. Likewise, Lu et al. further optimized the catholyte by preparing the sulfur-impregnated carbon composite.78 Different from the mechanically mixed sulfur-carbon composite suspension, sulfur was infiltrated into carbon via heat treatment, leading to improved electrical contact and decreased vis- cosity (Figure 8C). Therefore, a high volumetric capacity of 294 Ah L1 was delivered with a long battery life over 4,100 cycles, high Columbic efficiency (>90%), and high energy efficiency (>80%). Meanwhile, it is noted that a microporous membrane is adopted as the separator in those suspension systems, which is much more cost effective than ion-selective membranes used in commercial RFBs. The redox reactions of semi-solid suspensions can also proceed via the addition of redox species shuttling back and forth as mobile catalysts. In the presence of redox molecules as mediators, the electrode materials in suspensions can be reversibly lithiated and delithiated via redox targeting reactions without being electrically con- tacted to the current collector. In the new-concept cell structure, the redox targeting reactions can circumvent circulation of highly viscous suspensions containing large amounts of conductive carbon. The operation of such a battery system relies on well-matched potentials between the electrode materials and redox mediators. Ac- cording to the working principle, the redox potentials of the two redox mediators should straddle that of the electrode material to enable both the lithiation and de- lithiation processes.79 After rational screening of the electrodes and mediators, Wang et al. built a redox flow Li battery in which LiFePO4 and TiO2 functioned as Chem 5, 1964–1987, August 8, 2019 1979PDF Image | Development of Redox Flow Batteries Based on New Chemistries
PDF Search Title:
Development of Redox Flow Batteries Based on New ChemistriesOriginal File Name Searched:
PIIS2451929419302207.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 |