Gel Adsorbed Redox Mediators Tempo as Integrated Solid‐State Cathode for Ultra‐Long Life Quasi‐Solid‐State Na–Air Battery

Abstract

In metal–air batteries, the integrated solid‐state cathode is considered a promising design because it can solve the problem of high interfacial resistance of conventional solid‐state cathodes. However, solid discharge products cannot be efficiently decomposed in an integrated solid‐state cathode, resulting in batteries that are unable to operate for long periods of time. Herein, an integrated solid‐state cathode (Gel‐Tempo cathode) of sodium–air batteries (SABs) capable of promoting efficient decomposition of discharge product Na2O2 is designed. The Gel‐Tempo cathode is synthesized by cationic–π interaction of redox mediator 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (Tempo) and ionic liquid with carbon nanotubes. The Gel‐Tempo cathode serves multiple functions as a redox mediator, flame retardancy, and high stability to air. In quasi‐solid‐state SABs, the Gel‐Tempo cathode reduces overpotential to 1.15 V and improves coulomb efficiency to 84.5% (at a limited discharge capacity of 3000 mAh g−1) compared to gel cathodes. Experiments and density functional theory calculations indicate that Tempo significantly reduces the Gibbs free energy in the decomposition reaction of Na2O2, and high Tempo content is more conducive to enhancing the decomposition kinetics of Na2O2 and hence resulting in an ultra‐long cycle life (1746 h). This work is crucial to promote practical applications of SABs, providing guidelines for functionalization design of integrated solid‐state cathodes for metal–air batteries.

Mo‐Doped BiVO4 as a Fast Electrode Reaction Kinetics Catalyst in Na−O2 Batteries

“…What's more, it shows a lower work function obtained in Mo-dope BiVO 4 than pure BiVO 4 , representing the easier electron extraction, namely the fine light excitation and conductivity for the doped one (Figure 6c and S9). It is well known that the whole charging polarization of NaÀ O 2 batteries is determined by Na 2 O 2 decomposition as the following successive steps: [33] Na…”

“…What's more, it shows a lower work function obtained in Mo‐dope BiVO 4 than pure BiVO 4 , representing the easier electron extraction, namely the fine light excitation and conductivity for the doped one (Figure 6c and S9). It is well known that the whole charging polarization of Na−O 2 batteries is determined by Na 2 O 2 decomposition as the following successive steps: [33] $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr {\rm Na}{_{2}}{\rm O}{_{2}}+{\rm O}{_{2}}={\rm 2NaO}{_{2}}\hfill\cr}}$$$ $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr {\rm NaO}{_{2}}={\rm Na}+{\rm O}{_{2}}\hfill\cr}}$$$ …”

Enhancing Electrocatalytic Kinetics via Synergy of Co Nanoparticles and Co/Ni–N4–C- and N-Doped Porous Carbon

“…33,34 Moreover, the Co 2p high-resolution spectra in Figure 3d show one satellite peak of Co 2p 1/2 (793.5 and 796.4 eV) and Co 2p 3/2 (778.6 and 781.1 eV) at 785.5 eV, indicating the coexistence of Co and Co 2+ . 35,36 The ORR and OER performances of as-prepared catalysts and the reference samples (Ru−C and/or Pt−C) were probed by the linear sweep voltammetry (LSV) test. To obtain the optimal catalyst, the ratio of yeast and ZIF, as well as the annealing temperature, were chosen as the optimization conditions.…”

“…Figure b shows the N 1s spectrum, where N 1s can be antifolded to four peaks at 398.5, 400.4, 401.7, and 405.6 eV, corresponding to pyridine–N (34%), pyrrole–N (34%), graphite–N (24%), metallic–N (2%) and nitrogen–N (6%), respectively . The Ni 2p spectra of B-700 (Figure c) show four peaks at Ni 2p 1/2 (871.0 and 872.8 eV) and Ni 2p 3/2 (854.7 and 860.3 eV), with three additional satellite peaks at 863.6, 869.8, and 882.0 eV. , Moreover, the Co 2p high-resolution spectra in Figure d show one satellite peak of Co 2p 1/2 (793.5 and 796.4 eV) and Co 2p 3/2 (778.6 and 781.1 eV) at 785.5 eV, indicating the coexistence of Co and Co 2+ . , …”