Improved structural design of single- and double-wall MnCo₂O₄ nanotube cathodes for long-life Li–O₂ batteries

Abstract

Developing a cathode material with a stable pore structure and efficient bifunctional activity toward oxygen electrochemistry is the key to achieve practical and high-performance Li-O2 batteries. Here, hierarchically porous MnCo2O4 nanotubes with single- or double-wall architecture are fabricated through a facile electrospinning technique, by adjusting the concentration of the electrospinning solution. The electrochemical measurements indicate that both types of nanotubes possess excellent catalytic abilities toward oxygen reduction and evolution reactions in alkaline aqueous or non-aqueous media. When used as air-electrode catalysts for Li-O2 batteries, both single- and double-wall MnCo2O4 nanotubes show significantly improved electrochemical performance. In particular, the novel double-wall MnCo2O4 nanotubes (DW-MCO-NT), with a high surface area and a large pore volume almost twice as big as the single-wall nanotubes, can offer numerous catalytically active sites as well as sufficient space to deposit discharge products. The DW-MCO-NT based Li-O2 batteries can deliver a maximum discharge capacity of 8100 mA h g-1, with a potential plateau at 2.77 V, and achieve an excellent cyclability over 278 cycles, under strict conditions of 1000 mA h g-1 at 400 mA g-1 within 2.6-4.3 V. Moreover, the XRD and SEM analyses show that the dominant discharge product with a particulate shape is crystal Li2O2 and is prone to being completely decomposed, endowing the MnCo2O4 nanotube-based Li-O2 battery with a long cycle life.

One‐Step Route Synthesized Co2P/Ru/N‐Doped Carbon Nanotube Hybrids as Bifunctional Electrocatalysts for High‐Performance Li–O2 Batteries

“…Whereas the value for the Co 2 P/CNT electrode falls sharply to 45.3%. To be best of our knowledge, this is the best capacity retention performance that has been reported so far and the comparison of capacity retention performance between this work and some reported catalytic cathodes for the aprotic LOBs has been given in Table S1 in the Supporting Information …”

Tunable Cationic Vacancies of Cobalt Oxides for Efficient Electrocatalysis in Li–O2 Batteries

“…[3,24,26] To further improve catalytic activity of cobalt oxides, surface engineering (e.g., doping, vacancy, strain effect) is usually applied to modulate the atom arrangement and electronic properties for boosting the performance of Li-O 2 batteries. [27][28][29][30][31] Notably, the existence of vacancies can change the surface charge distribution to affect electrical conductivity and band structure. The newly generated catalytic sites would be created due to the lower coordination number.…”

Al2O3 Coatings on Zinc for Anti-Corrosion in Alkaline Solution by Electrospinning

“…We also measured the surface porosity of the coatings from SEM by using Image software (Java version) image processing as shown in Figure 5b. The surface porosity calculated from SEM is a little smaller than the total coating porosity calculated from Equation (4). Apparently, the coating porosity decreases with increasing thickness.…”

“…where P R , R 0 p and R p correspond to the total coating porosity, polarization resistance of the uncoated and coated zinc substrate, respectively. Table 1 shows the resulting coating porosity values obtained from Equation (4). We also measured the surface porosity of the coatings from SEM by using Image software (Java version) image processing as shown in Figure 5b.…”