Influence of Binders and Solvents on Stability of Ru/RuO_x Nanoparticles on ITO Nanocrystals as Li-O₂ Battery Cathodes

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• 作者：Dr. Svetoslava Vankova ; Dr. Carlotta Francia ; Dr. Julia Amici ; Dr. Juqin Zeng ; Prof. Silvia Bodoardo ; Prof. Nerino Penazzi ; Dr. Gillian Collins ; Dr. Hugh Geaney and Dr. Colm O'Dwyer
• 刊名：ChemSusChem
• 出版年：2017
• 出版时间：February 8, 2017
• 年：2017
• 卷：10
• 期：3
• 页码：575-586
• 全文大小：2604K
• ISSN：1864-564X

文摘

Fundamental research on Li–O₂ batteries remains critical, and the nature of the reactions and stability are paramount for realising the promise of the Li–O₂ system. We report that indium tin oxide (ITO) nanocrystals with supported 1–2 nm oxygen evolution reaction (OER) catalyst Ru/RuO_x nanoparticles (NPs) demonstrate efficient OER processes, reduce the recharge overpotential of the cell significantly and maintain catalytic activity to promote a consistent cycling discharge potential in Li–O₂ cells even when the ITO support nanocrystals deteriorate from the very first cycle. The Ru/RuO_x nanoparticles lower the charge overpotential compared with those for ITO and carbon-only cathodes and have the greatest effect in DMSO electrolytes with a solution-processable F-free carboxymethyl cellulose (CMC) binder (<3.5 V) instead of polyvinylidene fluoride (PVDF). The Ru/RuO_x/ITO nanocrystalline materials in DMSO provide efficient Li₂O₂ decomposition from within the cathode during cycling. We demonstrate that the ITO is actually unstable from the first cycle and is modified by chemical etching, but the Ru/RuO_x NPs remain effective OER catalysts for Li₂O₂ during cycling. The CMC binders avoid PVDF-based side-reactions and improve the cyclability. The deterioration of the ITO nanocrystals is mitigated significantly in cathodes with a CMC binder, and the cells show good cycle life. In mixed DMSO–EMITFSI [EMITFSI=1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide] ionic liquid electrolytes, the Ru/RuO_x/ITO materials in Li–O₂ cells cycle very well and maintain a consistently very low charge overpotential of 0.5–0.8 V.