A RuO₂ nanoparticle-decorated buckypaper cathode for non-aqueous lithium–oxygen batteries

Abstract

We report a non-aqueous lithium-oxygen battery with its cathode made of a RuO2 nanoparticle-decorated buckypaper (weaved with carbon nanotubes). Compared with conventionally slurry-formed cathodes, the present cathode has two striking features: i) no binder is required, avoiding the problems of surface-loss and instability due to the introduction of a polymeric binder; and ii) no additional current collector is needed, increasing the practical specific capacity. The present battery demonstrates a discharge plateau of 2.56 V and a charge plateau of 4.10 V at a current density of 0.4 mA cm -2 , with a discharge capacity of 4.72 mAh cm -2 (1150 mAh gcathode -1 ). It is also shown that at a fixed capacity of 2.0 mAh cm -2 , the energy efficiency of the battery reaches 71.2%, 65.4%, and 58.0% at the current densities of 0.2, 0.4, and 0.8 mA cm -2 , respectively. Furthermore, the battery is able to operate for 50 cycles at a fixed capacity of 1.0 mAh cm -2 , showing good cycling stability. The results suggest that the RuO2 nanoparticle-decorated buckypaper cathode offers the promise for a high-practical specific capacity, high-energy efficiency, and stable electrode in non-aqueous lithium-oxygen batteries.

Paramecium‐Like Iron Oxide Nanotubes as a Cost‐Efficient Catalyst for Nonaqueous Lithium‐Oxygen Batteries

“…At 200–1000 mA g −1 , the discharge overpotential increases from 0.18 to 0.22 V and the specific capacity decreases from 8050 to 3940 mAh g −1 ; however, the charge overpotential increases from 0.83 to 0.95 V, which indicates that the battery with the FNT/SP cathode exhibits a good rate capability. In addition, the charge overpotential is much lower than that of previous work (Table S1) and is even comparable to that of some noble‐metal‐based catalysts . The excellent catalytic activities for the OER and ORR of the Li–O 2 batteries with the FNT/SP cathode arise mainly from the following advantages of the paramecium‐like FNTs catalyst: 1) the nanowires coated on the surface can extend the electrode–electrolyte area to enhance the Li ion delivery; 2) the open morphology of the FNTs can offer short diffusion channels for oxygen and electrolyte in the electrode to ensure the fast and uniform distribution of oxygen and electrolyte (Figure ); 3) the electron transport can be facilitated by the tubular structure and the nanowires on the surface.…”

“…Conversely, after full charge, the three peaks related to Li 2 O 2 disappear and the (1 0 4) and (1 1 0) peaks of Fe 2 O 3 reappear, which indicates that Li 2 O 2 is totally or partially decomposed. The Li 1s XPS spectra of the cathodes after discharge and charge are presented in Figure d. After discharge, the Li 1s regions in the spectra of the FNT/SP, FNP/SP, and SP cathodes are located at similar positions and consist of two parts: the main discharge product, Li 2 O 2 (Li 1s: binding energy (BE)=54.5 eV), and some side products, lithium carbonate species (Li 1s: BE=55.3 eV), formed by the corrosion of the carbon cathode or the decomposition of the electrolyte. In contrast, the Li 1s peaks that correspond to Li 2 O 2 in the three cathodes disappear at full charge, which indicates the decomposition of Li 2 O 2 for all cathodes.…”

“…With cycling, the charge voltage remains at a high level (>4.25 V), and after 40 cycles before the battery is fully charged, the voltage reaches the cutoff voltage of 4.5 V, which indicates that some discharge products (Li 2 O 2 ) remain undecomposed. Additionally, under such a high charge voltage (>4.5 V), the decomposition of the organic electrolyte and the corrosion of the pure carbon cathode would occur to form byproducts (e.g., Li 2 CO 3 , RCOOLi, or LiF) . Not only irreversible products but undecomposed Li 2 O 2 would accumulate and cover the surface of the cathode, which decreases the number of active sites and leads eventually to the discharge capacity decay in the 42nd cycle.…”

A Review of Carbon-Composited Materials as Air-Electrode Bifunctional Electrocatalysts for Metal–Air Batteries

“…Apart from perovskite oxides and spinel oxides, other oxides, such as CoO [145,146], MnO 2 [147,148], and RuO 2 [149,150], have also been used to prepare effective carbon-composited bifunctional catalysts to tackle the sluggish kinetics of ORR and OER in MABs. Based on a novel strategy to improve the catalytic performance of CoO through the integration of dotted carbon species and oxygen vacancies, Gao et al [145] designed and synthesized a carbon-dotted CoO with oxygen vacancies (CoO/C) for LAB cathodes using a simple calcination of a formed pink precipitate of ethanolmediated Co(Ac) 2 ·4H 2 O.…”

Bi2S3/Ketjen Black as a Highly Efficient Bifunctional Catalyst for Long‐Cycle Lithium‐Oxygen Batteries

“…[2,[4][5][6] To solve these dilemmas, a cathode with a highly efficient catalytic performance for oxygen reduction reaction (ORR)/ oxygen evolution reaction (OER) is necessary. [7,8] So far, many kinds of catalysts, such as carbon materials and metal compounds, have been applied in LiÀ O 2 batteries and have shown the good bifunctional ORR/OER catalytic activity. [9][10][11][12][13] On one hand, carbon materials, such as porous carbon, [14,15] multiwalled carbon nanotubes (MWCNTs) [2,3] and graphene, [12,16] inherently possess the excellent ORR catalytic effect due to the high electrical conductivity and large specific surface area.…”