Synergy Between Metal Oxide Nanofibers and Graphene Nanoribbons for Rechargeable Lithium‐Oxygen Battery Cathodes

Abstract

The challenges for rechargeable lithium‐oxygen batteries of low practical capacity and poor round‐trip efficiency urgently demand effective cathode materials to overcome the limitations. However, the synergy between the multiple active materials is not well understood. Here, findings of the synergistic effect between electrospun zinc oxide (ZnO) nanofibers and graphene nanoribbons (GNRs) unzipped from carbon nanotubes (CNTs) as cathode materials in rechargeable lithium‐oxygen batteries are described. Furthermore, the overpotentials and discharge capacities are tuned by the surface defect states of ZnO nanofibers and Pt nanocrytals in GNRs. It is observed that the optimized zinc oxide nanofibers hybridized with GNRs achieved a high reversible capacity of 6300 mAh g‐1carbon and enhanced stable cyclability under specific 50% of full discharge capacities. This report demonstrates that the ZnO nanofibers with a high degree of defects and hydrophilicity of the surface may be a promising cathode component for rechargeable lithium‐oxygen batteries and the optimum synergy between ZnO nanofibers and GNRs can balance the discharge capacity and cycle life.

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

“…The cyclic voltammograms (CV) measurements are performed to study the electrochemical catalytic activity of Co 2 P/Ru/CNT, Co 2 P/CNT, and Co/CNT. As presented in Figure a, the CV behaviors display one distinct reduction peak ascribed to the formation of Li 2 O 2 (ORR, O 2 + 2Li + + 2e − → Li 2 O 2 ), and without distinct oxidation peak related with the decomposition of discharge products (OER, Li 2 O 2 → O 2 + 2Li + + 2e – ), respectively, indicating a redox reaction pathway . The enlarged CV curves of the three electrodes within a voltage window of 2.5–3.5 V are shown in Figure b.…”

A Critical Review on Functionalization of Air‐Cathodes for Nonaqueous Li–O2 Batteries

“…The hydrophobicity/hydrophilicity surface characterization of the binders is a paramount parameter to consider in order not to compromise the wettability of the air‐cathode and the electrolyte, securing safe arrival/departure of active species to/from the catalytically active sites during the formation/decomposition processes . Hydrophilic properties may also support three‐phase boundary reaction zones . When superoxide anion radicals were chemically generated to study the stability of poly(vinylidene fluoride) (PVDF) polymer binder, it was concluded that PVDF reacts with superoxide anion radical, resulting in dehydrofluorination with the formation of LiF and H 2 O 2 …”

The critical contribution of unzipped graphene nanoribbons to scalable silicon–carbon fiber anodes in rechargeable Li-ion batteries

“…In that image, GNR edges are marked by red dashed lines for ease of detection. Since nanostructured carbons like GNRs or CNTs combust at a little higher temperature compared to carbon made from PVA polymer, [30,45,46] GNRs, carbon and silicon content of fibers could be calculated by thermogravimetric analysis (TGA) (see Figure S5). From TGA results, GNRs content in the GNR/ Si/C fibers is estimated to be about 5 wt% (SiNPs: 72 wt% and carbon: 23 wt%), while Si/C fibers have 72 wt% SiNPs and 28 wt% carbon.…”

“…Kumta and co-workers produced a hybrid silicon/CNTs anodes that possess efficient conducting channels [22]. Recently, 2-D graphene structures have gained a lot of attention for use in composite Si anodes due to their excellent conductivity and unique edge morphology [23][24][25][26][27][28][29][30]. Yushin group used graphene granules to form 3-D structured anodes [31,32] and Korgel and co-workers demonstrated stable cycling in a graphene-supported silicon anode [33,34].…”