Non-precious transition metal based electrocatalysts for vanadium redox flow batteries: Rational design and perspectives

Electron‐Deficient Sites for Improving V2+/V3+ Redox Kinetics in Vanadium Redox Flow Batteries

“…Long‐term cycling tests were carried out to further evaluate the durability of the catalyst. [ 31 ] The cell with TiB 2 ‐GF exhibits no obvious degradation on both the VE and EE at 150 mA cm −2 within 300 cycles (Figure 5h and Figure S25, Supporting Information). The EE of the cell with TiB 2 ‐GF retains 74.20% at 150 mA cm −2 after 300 cycles, improved by 14.06% over the pristine cell (60.14%).…”

Electrochemically induced catalytic adsorption sites in spent lithium-ion battery cathodes for high-rate vanadium redox flow batteries

“…[15][16][17][18][19] Transition metal oxides have attracted signicant attention as electrocatalysts because of the variable oxidation state of a transition metal that facilitates the redox reaction and the oxygen vacancy, which increases the electrochemical activity as an active site. 20,21 Oxygen vacancies have been intentionally employed in transition metal oxides as active sites for several electrochemical reactions in the eld of defect engineering. [22][23][24][25][26][27][28] There are reports of the introduction of oxygen vacancies in transition metal oxides using lithium electrochemical tuning (LiET).…”

High power zinc iodine redox flow battery with iron-functionalized carbon electrodes

“…One way to overcome these limitations is to decrease the resistance of the electrodes and increase the electrochemical reaction rates at the electrode-electrolyte interface by incorporating redox-active transition metals particles into the inert carbon electrodes. 10 Previously, we demonstrated that the power density increases by 140% (and energy density by 57%) when carbon electrodes contain redox-active iron nanoparticles using a ''stationary'' RFB with iron-based redox electrolytes. 22 The activity of the embedded nanoparticles arises from the Fe 2+ /Fe 3+ redox couple (0.77 V vs. SHE), which has been shown to accelerate reactions at the electrode-electrolyte interface.…”

“…One way to overcome these limitations is to decrease the resistance of the electrodes and increase the electrochemical reaction rates at the electrode–electrolyte interface by incorporating redox-active transition metals particles into the inert carbon electrodes. 10…”

“…Despite these advantages, VRFBs suffer from the high cost and limited availability of vanadium, the need for expensive separators, and the use of corrosive electrolytes. 10,11 Although vanadium ions are present on both sides of the battery, the performance can be limited by electrolyte crossover and self-discharge because a different set of redox couples exist on each side of the cell, V 4+ /V 5+ on the positive and V 2+ /V 3+ on the negative electrode. 12,13 The zinc iodine (ZI) RFB chemistry, a low-cost and environmentally friendly alternative to vanadium, has demonstrated potential for large-format batteries because of its high electrochemical activity.…”