Cathode For Lithium-Oxygen Batteries Research Articles

Nitrogen-containing mesoporous carbon cathode for lithium-oxygen batteries: The influence of Nitrogen on oxygen reduction reaction

The direct effect of nitrogen content and various nitrogen species on oxygen reduction reaction (ORR) activities in non-aqueous lithium-oxygen (Li-O2) batteries are systematically investigated. Mesoporous carbon (MC) with various nitrogen species is prepared through heat treatment of N-containing precursor under different temperature. The effect of the heat treatment temperature on the performance of carbon materials in Li-O2 battery is investigated. The bonding state of nitrogen atoms is found to have a significant effect on the ORR activity. The ORR activity in Li-O2 battery is proved to be dependent on the quaternary N content while the total N content in the carbon material does not play a crucial role in the ORR process.

Metal-Free Mesoporous Cathode for Lithium-Oxygen Batteries: Noble Carbons As Bifunctional Catalyst

The use of renewable energy is an urgent and serious request to ensure the energy supply in the 21st century.1 The rechargeable lithium-oxygen batteries (LOBs) are one of the most promising secondary batteries to be applied to smart grid and electronic vehicles which are electrified from mixed energy generated by renewable and traditional fossil fuels. However, LOBs are suffering from unoptimized combinations of catalysts and electrolytes: 1) carboneous materials, which are good oxygen reduction reaction (ORR) catalysts and support for other catalysts, are one of main causes of side-reactions associated with electrolyte decomposition and 2) from point of commercial viability, the price of LOBs should be affordable: We cannot use expensive noble metals.2-4 Here, we show that mesoporous nitrogen doped carbons (meso-NdCs) as efficient bifunctional catalysts which can process well both ORR and oxygen evolution reaction (OER).5 The meso-NdCs were synthesized by carbonization of all-organic ionic liquid and using SiO2 nanoparticles (14 nm of diameter) as a hard template. The electrochemical properties of meso-NdCs are characterized by galvanostatic charge-discharge curves. The formation/de-formation of lithium peroxide and other side products were checked by ex-situ X-ray diffractometer and ex-situ Fourier-transform infrared spectroscopy. As the results, the meso-NdCs shows good catalytic activities in both ORR and OER. Especially at OER, meso-NdCs show the recharge plateau at 3.7 V versus Li/Li+: the lowest overpotential as non-metal catalyst (0.7 V). Indeed, we found that the cycle property can be improved by synthetic condition due to higher conductivity enhanced by enrichment of atomic graphitic parts. Indeed, stability against active reduced oxygen species and fewer defects could give positive effects for this better electrochemical property. This study suggests that by changing the amount of dopant and the degree of graphitization, we can control both an electrochemical catalytic activity and the cycling property of the carboneous materials as possible catalysts in LOBs.We propose that meso-NdCs are the new candidate as affordable, efficient, metal-free bifunctional catalysts to be used in rechargeable energy storage devices. This is very important because several elements, such as sulfur and phosphor, are promising candidates to be doped in and improve the electrochemical catalytic properties of carbon, which is considered as an unfavorable catalyst for LOBs so far. S. Chu, A. Majumdar, Nature 2012, 488, 294-303.S. A. Freunberger, Y. Chen, Z. Peng, J. M. Griffin, L. J. Hardwick, F. Bardé, P. Novák, P. G. Bruce, J. Am. Chem. Soc. 2011, 133, 8040-8047J. Christensen, P. Albertus, R. S. Sanchez-Carrera, T. Lohmann, B. Kozinsky, R. Liedtke, J. Ahmed, A. Kojic, J. Electrochem. Soc. 2012, 159, R1-R30.Y.-C. Lu, B. M. Gallant, D. G. Kwabi, J. R. Harding, R. R. Mitchell, M. S. Whittingham, Y. Shao-Horn, Energy Environ. Sci. 2013, 6, 750-768.K. Sakaushi, T.-P. Fellinger, M. Antonietti, manuscript submitted.

Fe[sbnd]N[sbnd]C catalyst modified graphene sponge as a cathode material for lithium-oxygen battery

The cathode of a lithium-oxygen battery needs the synergism of a porous conducting material and a catalyst to facilitate the formation and decomposition of lithium peroxide. Here we introduce a graphene sponge (GS) modified with FeNC catalyst for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). The porous, 3-dimensional conductive and free standing nature of the graphene sponge makes it become excellent skeleton of cathode for lithium-oxygen battery. The FeNC catalyst nanoparticles dispersed uniformly on the graphene sheets show excellent catalytic reactivity in both discharge and charge processes. This kind of composite material greatly improves the capacity and cyclability of the lithium-oxygen battery. With dimethyl sulphoxide as electrolyte, the capacity reaches 6762mAhg−1 which is twice of the pure graphene sponge. In addition, the cell containing FeNGS air electrode exhibits stable cyclic performance and effective reduction of charge potential plateau, indicating that FeNGS is promising as an OER catalyst in rechargeable lithium-air batteries.

Nanosized Carbon‐Supported Manganese Oxide Phases as Lithium–Oxygen Battery Cathode Catalysts

AbstractThe poor discharge and recharge efficiency demonstrated by lithium–air batteries renders the search for highly active and inexpensive oxygen reduction and evolution catalysts crucial to the development of these energy‐storage and conversion devices. Previous works have shown that manganese oxides are promising lithium–oxygen cathode catalysts, which is in agreement with their remarkable activities for the reduction and evolution of oxygen in aqueous media. Motivated by these resembling catalytic behaviors, we prepared and characterized a number of manganese oxide modifications directly on carbon black and attempted to correlate their oxygen reduction and evolution activities in aprotic and aqueous electrolytes. Although our results cannot confirm this correlation, they provide valuable insight into the reaction mechanisms at play in each medium. More precisely, in 0.1 M potassium hydroxide, the reduction of oxygen is related to the reduction of a manganese(III) intermediate whereas the oxidation of hydrogen peroxide (which was regarded as a mimic of the lithium peroxide produced upon lithium–oxygen battery discharge) correlates with the transition between manganese(II) and manganese(III) phases. In the aprotic medium, manganese oxide cathodes prefilled with lithium peroxide showed a strong catalytic effect but were not active in the oxidation of lithium peroxide produced in the previous discharge. This discrepancy is thought to arise from the stark differences in the sizes and morphologies of the lithium peroxide involved in each test, which implies that the catalytic activity of a material for the oxidation of lithium peroxide prefilled on electrodes is not indicative of its behavior in the charging of a real lithium–oxygen cell.

Eco-friendly water-borne conducting polyaniline

Among the intrinsically conductive polymers, polyanilines have been of great interest in the past decades due to their wide applications in many fields, thanks to their reasonably good conductivity, easy preparation, and special redox properties. Ever-increasing environmental considerations make the processing of polyanilines shift from toxic organic solvent-based system to eco-friendly water-based system. The present paper reviews the synthesis of water-borne conducting polyanilines, and possible applications are discussed including supercapacitor electrode material, metal free corrosion protection coating, lithium oxygen battery cathode material and ultraviolet curable resin.

Effect of porosity on electrochemical properties of carbon materials as cathode for lithium-oxygen battery

Porosity effect of carbon materials on the electrochemical performances as cathode materials in non-aqueous Li-oxygen cells has been investigated. A carbon aerogel material is chosen to represent mesoporosity and a couple of activated carbon materials are selected to represent microporosity. Carbon aerogel shows at least ten times higher discharge capacity (4155 mAh g−1) than activated carbons. It is found that as much as 61% of pore volume of carbon aerogel is filled with discharge products (Li2O2) while less than 18% of pore volume is occupied with Li2O2 at the end of discharge in activated carbons, indicating that mesopore is more effective than micropore. In another experiments, the electrolyte impregnated electrode shows a capacitor-like discharge behavior, meaning it is necessary to have some open pore for the oxygen supply even though they are micropores.