Abstract
Here, we report new gas diffusion electrodes (GDEs) prepared by mixing two different pore size carbonaceous matrices and pure and silver-doped manganese dioxide nanopowders, used as electrode supports and electrocatalytic materials, respectively. MnO2 nanoparticles are finely characterized in terms of structural (X-ray powder diffraction (XRPD), energy dispersive X-ray (EDX)), morphological (SEM, high-angle annular dark field (HAADF)-scanning transmission electron microscopy (STEM)/TEM), surface (Brunauer Emmet Teller (BET)-Barrett Joyner Halenda (BJH) method) and electrochemical properties. Two mesoporous carbons, showing diverse surface areas and pore volume distributions, have been employed. The GDE performances are evaluated by chronopotentiometric measurements to highlight the effects induced by the adopted materials. The best combination, hollow core mesoporous shell carbon (HCMSC) with 1.0% Ag-doped hydrothermal MnO2 (M_hydro_1.0%Ag) allows reaching very high specific capacity close to 1400 mAh·g−1. Considerably high charge retention through cycles is also observed, due to the presence of silver as a dopant for the electrocatalytic MnO2 nanoparticles.
Highlights
Electrochemical power suppliers, capable of storing high quantities of energy, have always been one of the most challenging topics in electrochemistry
MnO2 powders are widely used as cathodic material in batteries [16,17,35]; their electrochemical reactivity generally depends on morphological and structural (crystalline phases, presence of defects [36,37])
This result is fully in agreement with what was reported by Benhaddad et al [38], who synthesized powders consisting of assembled straight needles characterized by similar average sizes
Summary
Electrochemical power suppliers, capable of storing high quantities of energy, have always been one of the most challenging topics in electrochemistry. Air-cathode structures and the employed material morphologies are crucial to assess from both electrochemical [3,4,5] and morphological/structural [6] techniques In these systems, current density, electrolyte composition and discharge products The usage of propylene carbonate (PC), and in general of organic carbonates, is still an open debate and studies on the mechanism and by-product formation of carbonate solvent degradation in Li/air batteries are going on [27] To overcome this problem, aprotic electrolytes (such as DMSO or tetraethylene glycol dimethyl ether (TEGDME)) have been used lately in Li-O2 batteries [28,29,30]. Taking into account all of the shortcomings related to the use of non-aqueous electrolytes [17,33,34], LiClO4 in PC (a low cost material) has been employed aiming at evaluating the performance of both pure and doped manganese dioxide-based nanomaterials, as electrocatalysts
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