Fe-based hybrid electrocatalysts for nonaqueous lithium-oxygen batteries

Abstract

Lithium–oxygen batteries promise high energy densities, but are confronted with challenges, such as high overpotentials and sudden death during discharge–charge cycling, because the oxygen electrode is covered with the insulating discharge product, Li2O2. Here, we synthesized low–cost Fe–based nanocomposites via an electrical wire pulse process, as a hybrid electrocatalyst for the oxygen electrode of Li–O2 batteries. Fe3O4-Fe nanohybrids–containing electrodes exhibited a high discharge capacity (13,890 mA h gc −1 at a current density of 500 mA gc −1), long cycle stability (100 cycles at a current rate of 500 mA gc −1 and fixed capacity regime of 1,000 mA h gc −1), and low overpotential (1.39 V at 40 cycles). This superior performance resulted from the good electrical conductivity of the Fe metal nanoparticles during discharge–charge cycling, which could enhance the oxygen reduction reaction and oxygen evolution reaction activities. We have demonstrated the increased electrical conductivity of the Fe3O4-Fe nanohybrids using electrochemical impedance spectroscopy.

Magnéli-Phase Ti4O7 Nanosphere Electrocatalyst Support for Carbon-Free Oxygen Electrodes in Lithium–Oxygen Batteries

“…We investigated EIS analysis for a more secure approach (Figure S10 and Table S1 in the Supporting Information). In the Li–O 2 battery, the semicircle in the middle frequency region indicates the charge transfer resistance ( R ct ), which is associated with the charge transfer reaction at the electrode/electrolyte interface …”

“…In the Li−O 2 battery, the semicircle in the middle frequency region indicates the charge transfer resistance (R ct ), which is associated with the charge transfer reaction at the electrode/ electrolyte interface. 41 R ct is related to the rate coefficient of the chemical reaction in the oxygen electrode. Decreased R ct represents an efficient oxygen diffusion pathway and less agglomeration of the oxygen electrode.…”

Rational design of porous Ru‐doped CuO nanoarray on carbon cloth: Toward reversible catalyst layer for efficient Li‐O 2 batteries

“…After the subsequent charge process, the Ru‐CuO/RuO 2 @CC cell again has a smaller R ct (40.3 Ω cm −2 ) than the CuO/RuO 2 ‐P@CC cell (68.5 Ω cm −2 ). Since R ct is inversely proportional to the rate coefficient of chemical reaction, porosity, and O 2 concentration in the cathode, 38‐41 the decrease in R ct indicates that the oxygen diffusion pathway is facilitated by the porous structure of the Ru‐CuO/RuO 2 @CC. During ORR process, the reduced oxygen species (O 2 + n e − → O 2 n − , n = 1 or 2) diffuse in active contact area between the catalyst and the electrolyte.…”

Recent Progress on Catalysts for the Positive Electrode of Aprotic Lithium-Oxygen Batteries †

“…As discussed above, the morphology and physicochemical property of discharge product can effectively influence the charging performance of Li-O 2 batteries. Some pioneer works have revealed that catalysts determined the deposition process and finally affected the morphology of discharge product by the different adsorption ability toward LiO 2 intermediate [93][94][95][96]. Adopting such strategy, several relative works were published.…”