A Gas Diffusion Layer Impregnated with Mn<sub>3</sub>O<sub>4</sub>‐Decorated N‐Doped Carbon Nanotubes for the Oxygen Reduction Reaction in Zinc‐Air Batteries

2020

ChemElectroChem

Self Cite

ZnÀ Co oxide (ZnCoO x ), ZnÀ Mn oxide (ZnMnO x ), ZnÀ MnÀ Co oxide (ZMCO), and ZnÀ CoÀ Fe oxide (ZCFO) nanoparticles were successfully synthesized on nitrogen-doped carbon nanotubes in a one-pot process. Porous carbon paper was simultaneously impregnated with the catalysts during synthesis and used as air electrodes for Zn-air batteries. ZnMnO x /N-CNT catalysts had the best ORR performance in half-cell LSV experiments with a more positive onset potential than that of PtÀ Ru/C (À 0.067 V and À 0.078 V vs Hg/HgO, respectively). ZCFO/N-CNT catalysts had the best activity towards OER among the Zn-based oxide catalysts in half-cell linear sweep voltammetry (LSV) testing with an onset potential of 0.62 V vs Hg/HgO. Round-trip efficiencies from battery rate tests at a current density of 20 mA cm À 2 were 55.3 %, 57.5 %, 58.7 %, and 58.3 % for ZnCoO x /N-CNT, ZnMnO x / N-CNT, ZMCO/N-CNT, and ZCFO/N-CNT, respectively. Bifunctional cycling of the catalysts was done in a homemade Zn-air battery at a current density of 10 mA cm À 2 for 200 cycles. The final round trip efficiencies for ZnCoO x /N-CNT, ZnMnO x /N-CNT, ZMCO/N-CNT, and ZCFO/N-CNT were 55.8 %, 56.6 %, 54.2 %, and 55.0 %, respectively. All catalysts except ZCFO/N-CNT compared favorably with PtÀ Ru/C in terms of round-trip efficiency after cycling (55.3 %). Incorporation of Zn into the metal oxide particles showed improved catalytic activity for ZnCoO x /N-CNT and ZnMnO x /N-CNT compared with MnO x /N-CNT and CoO x /N-CNT catalysts prepared via the same technique.

Section: Introductionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Zn‐Based Oxides Anchored to Nitrogen‐Doped Carbon Nanotubes as Efficient Bifunctional Catalysts for Zn‐Air Batteries

Aasen

Shen²,

2020

ChemElectroChem

Self Cite

“…Our previous work reported excellent ORR performance for a gas diffusion layer (GDL) impregnated with Mn 3 O 4 decorated N‐CNTs . The catalyst was loaded into the GDL by a simple soaking and filtering process, where the GDL was used in place of filter paper.…”

Section: Introductionmentioning

confidence: 99%

(Co,Fe)₃O₄ Decorated Nitrogen‐Doped Carbon Nanotubes in Nano‐Composite Gas Diffusion Layers as Highly Stable Bifunctional Catalysts for Rechargeable Zinc‐Air Batteries

Aasen

Clark

2019

Batteries & Supercaps

Self Cite

Co,Fe) 3 O 4 nanoparticles are decorated onto N-doped carbon nanotubes at room temperature through a simple mixing process and are simultaneously deposited within a porous gas diffusion layer (GDL) by an impregnation technique. The (Co, Fe) 3 O 4 nanoparticles are identified as the spinel phase through transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The composite GDL is used as the air electrode for Zn-air batteries and shows excellent performance as a bifunctional catalyst with initial discharge and charge potentials of 1.19 V and 2.00 V, respectively, at 20 mA cm À 2 . Cycling performance of the impregnated electrode compares favourably with benchmark Pt-RuO 2 catalysts at both 10 mA cm À 2 and 20 mA cm À 2 . The (Co,Fe) 3 O 4 /N-CNT impregnated GDL had a final discharge/charge efficiency of 58.5 % after 100 h (200 cycles) of bifunctional cycling at 10 mA cm À 2 , which is superior to that of Pt-RuO 2 (55.3 % efficiency). The cycling efficiency for (Co,Fe) 3 O 4 /N-CNT impregnated GDL at 20 mA cm À 2 is also better than that for PtÀ Ru (53.5 % vs 41.3 % after 50 h (100 cycles)). The result is a simple and easily scalable one-pot electrode synthesis method for high performing bifunctional air electrodes for Zn-air batteries.

“…Of the different Mn oxide phases that have been studied, there have only been a handful of instances where Mn 3 O 4 has been used as a cathode material for ZIBs . Mn 3 O 4 has been extensively studied for Zn‐air batteries and has been shown to be a good oxygen reduction reaction (ORR) catalyst for the air electrode in Zn‐air batteries …”

Section: Introductionmentioning

confidence: 99%

Electrodeposited Manganese Oxide on Carbon Paper for Zinc‐Ion Battery Cathodes

Dhiman

2019

Batteries & Supercaps

Self Cite

Nano‐crystalline, flake‐like Mn oxide was electrodeposited onto carbon paper (CP) using a pulsed electrodeposition technique. The electrodeposited Mn oxide was identified as Mn3O4 through a combination of X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), and Raman spectroscopy. The Mn3O4 on CP was used as a cathode for Zn‐ion batteries (ZIBs) and showed excellent cyclability at a current density of 1 A g−1 with a capacity retention of 139 % after 200 cycles. Electron microscopy was used to characterize the microstructural changes of the cathode at various stages during discharge/charge cycling. This work in combination with the electrochemical results suggests a two‐step reaction mechanism involving both intercalation and conversion reactions. The results demonstrate that electrodeposition of the cathode material is a simple, quick, and potentially scalable electrode synthesis method for producing high performing Zn‐ion electrodes without the use of binders or other additives.