Performance characteristics of a liquid e-fuel cell

A Passive Fuel Cell Fed with an Electrically Rechargeable Liquid Fuel

“…It is also found that, in comparison to the discharge curve obtained at the first cycle, the cell voltage at the last cycle is slightly lower. Such a phenomenon may be ascribed to the crossover of reactive species across the membrane inducing the accumulation of vanadium ions at the cathode side, which thereby block the reactive surface of the catalysts and enlarges overpotential loss. ,, Furthermore, it is worth mentioning that an unexpected gas evolution phenomenon was observed at the anode side during the test, which can also obstruct the reactive surface at the anode and hamper the mass transport of reactants, resulting in the fluctuation of cell voltage as demonstrated in the discharge curves. , This phenomenon is later proved as a spontaneous hydrogen evolution reaction and discussed extensively in the next section. Such a reaction accompanied by the inevitable crossover of e-fuel through the membrane would result in the loss of reactive species, which thereby lead to the loss of Faradaic efficiency and further reduces the energy efficiency of the cell.…”

“…Here, to study the long-term operation behavior of this system, the passive fuel cell has been tested at 5.0 mA cm −2 and refueled for 25 times. The discharge curves are as shown in Figure 4a, while the associated efficiencies, Faradaic, voltage, and energy efficiencies, are calculated using the equations as reported before 15 and as shown in Figure 4b. The cell is found to achieve a stable operation for over 350 h, with little difference between the discharge curves obtained at the first and last cycle, indicating the excellent long-term stability of this system.…”

“…Such a phenomenon may be ascribed to the crossover of reactive species across the membrane inducing the accumulation of vanadium ions at the cathode side, which thereby block the reactive surface of the catalysts and enlarges overpotential loss. 14,15,21 Furthermore, it is worth mentioning that an unexpected gas evolution phenomenon was observed at the anode side during the test, which can also obstruct the reactive surface at the anode and hamper the mass transport of reactants, resulting in the fluctuation of cell voltage as demonstrated in the discharge curves. 22,23 This phenomenon is later proved as a spontaneous hydrogen evolution reaction and discussed extensively in the next section.…”

“…All experiments were conducted at ambient condition. For the long-term operation behavior test, the Faradaic, voltage, and energy efficiencies are calculated using the following equations: i ( t ) is the discharging current, while c init and V represents the initial concentration of e-fuel and volume of e-fuel, respectively. E av and E theo is the average discharging voltage and theoretical average voltage calculated based on the Nernst equation, respectively.…”

“…Recently, a novel concept named the electrically rechargeable liquid fuel (e-fuel), which possesses many advantages such as rechargeability and superior reactivity over the conventional liquid alcohol fuels, was presented. − Potential liquid e-fuel can be prepared from diverse kinds of material, and it has been reported in recent studies that the e-fuel containing vanadium ions is capable of achieving a better performance including much higher peak power density and energy efficiency than conventional direct liquid fuel cells do. − …”