PDF Publication Title:
Text from PDF Page: 082
Modification Along this thesis, several modifications on the VRFB electrodes have been done, as improvements by different metal oxides configurations on the negative (TiO2, TiO2:H, TiO2:Nx) and positive (CeO2) electrodes, in order to enhance the reachable capacity, power density, efficiencies, operational current density and stability of the battery, which will be described in the ongoing chapter. 6.1 Electrodes developed Recently, intensive efforts have been made to improve the state-of-the-art over the negative electrode materials for VRFB systems, as shown in Table 6.1. For example, Li et al.169 achieved an excellent Energy efficiency (EE) value (ca. 78%) and Coulombic efficiency (CE) value (ca. 98%) at 150 mA/cm2 after 4 cycles, using a low-cost Bi as electrocatalyst. The same authors170 have proposed Niobium Oxide (V) Wolframium doped, Nb2O5(W), as an electrocatalyst, demonstrating outstanding performance and leading to 98.5% of CE and 78.7% of EE value at the same current density mentioned before, after more than 50 cycles. This is the best EE value ever reported in the literature. As an alternative strategy, Park et al.171 demonstrated the successful introduction of N- and O- containing groups on a surface of a felt electrode by means of corn protein as precursor, achieving a performance up to 68.8% of EE value and 98.8% of CE value at 150 mA/cm2 over 5 cycles. Despite the significant progress that has been made through the use of a new catalyst for high-efficiency negative electrodes in VRFB, the electrolyte- utilization ratio (i.e. specific discharge capacity and theoretical capacity ratio) is quite low, achieving up to a maximum of 64% of theoretical capacity169. In this regard, further improvement to reduce parasitic reactions in the negative half-cell reaction, as HER (i.e. high CE values), is still necessary, as well as a high storage capacity to guarantee high performance systems for a long cycle life. Although the study of long-term stability at several rate capabilities is rarely discussed in the literature (up to 50 cycles)170, Haipeng Zhou et al have reached up to 200 cycles for 100 mA/cm2 172. Following this behaviour we focused deeper on a high stability of our electrode applying larger current densities. Table 6.1.- Electrochemical performance in single cell conditions comparative for different treated electrodes based on physical and chemical modifications on carbonaceous structures. Reagent & Treatment Conditions Parameters of VRFB single cell or activation method Electrode size /cm [VOSO4] /M Max. j / mA cm-2 CE/ VE/ EE/ %%% Ref Electrolyte Utilization ratio Cyclesmax. Corona + 4A,15sx2+30%H2O2, 5x5 1.7 145.8 96.7 70.3 68.0 96.1 20 173 H2O2 1 h (32mA/cm2) N-doped Corn protein-derived and 2.5 x 2.5 2 150 98.0 70.0 68.6 37.3 80 171 81PDF Image | Redox Flow Batteries Vanadium to Earth Quinones
PDF Search Title:
Redox Flow Batteries Vanadium to Earth QuinonesOriginal File Name Searched:
FJVG_TESIS.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)