268 research outputs found
Development of stripper harvester for paddy
Konkan is the coastal part of Maharashtra between Western Ghat and Arabian seacoast. Rice is a major crop grown over 3.86 lakh hectares. Stripper harvesting technology, which strips only seeds and keeps straw erect-ed in the field present bright prospect for the development of small, light, efficient mechanism by reducing number of operation with increased capacity and lesser power compared to conventional cutter bar combine harvester. The big machines like combine harvester and high capacity threshers for harvesting and threshing have limitations. A proto-type of paddy stripper harvester was developed considering the limitation of Konkan like small, fragmented land, hilly, terrace farming and high rainfall. It consisted of stripping mechanism, grain tank, hydraulic system, steering system, gear box, engine, cage wheel and chassis. The arrangement of V-belt and set of pulleys were made to transmit power from gear box to stripper rotor. The effect of forward speed and peripheral speed on shattered and un-stripped grain loss was studied. The shattered grain loss was decreased with increase in forward speed whereas decreased initially and then increased with increase in peripheral speed. The un-stripped grain loss was decreased with increase in forward and peripheral speed. The performance of the developed prototype was found better at forward speed of 2.25 km/h and peripheral speed of 19.78 m/s. During final testing of prototype, shattered and un-stripped grain loss was found 5.95 and 1.89 %, respectively. The average field capacity and field efficiency of paddy stripper harvester machine was found 0.14 ha/h and 69.38 per cent respectively
Deactivation of carbon electrode for elimination of carbon dioxide evolution from rechargeable lithium-oxygen cells
Carbon has unfaired advantages in material properties to be used as electrodes. It offers a low cost, light weight cathode that minimizes the loss in specific energy of lithium-oxygen batteries as well. To date, however, carbon dioxide evolution has been an unavoidable event during the operation of non-aqueous lithium-oxygen batteries with carbon electrodes, due to the reactivity of carbon against self-decomposition and catalytic decomposition of electrolyte. Here we report a simple but potent approach to eliminate carbon dioxide evolution by using an ionic solvate of dimethoxyethane and lithium nitrate. We show that the solvate leads to deactivation of the carbon against parasitic reactions by electrochemical doping of nitrogen into carbon. This work demonstrates that one could take full advantage of carbon by mitigating the undesired activity. © 2014 Macmillan Publishers Limited. All rights reserved.open8
Hierarchical urchin-shaped alpha-MnO2 on graphene-coated carbon microfibers: a binder-free electrode for rechargeable aqueous Na-air battery
With the increasing demand of cost-effective and high-energy devices, sodium-air (Na-air) batteries have attracted immense interest due to the natural abundance of sodium in contrast to lithium. In particular, an aqueous Na-air battery has fundamental advantage over non-aqueous batteries due to the formation of highly water-soluble discharge product, which improve the overall performance of the system in terms of energy density, cyclic stability and round-trip efficiency. Despite these advantages, the rechargeability of aqueous Na-air batteries has not yet been demonstrated when using non-precious metal catalysts. In this work, we rationally synthesized a binder-free and robust electrode by directly growing urchin-shaped MnO2 nanowires on porous reduced graphene oxide-coated carbon microfiber (MGC) mats and fabricated an aqueous Na-air cell using the MGC as an air electrode to demonstrate the rechargeability of an aqueous Na-air battery. The fabricated aqueous Na-air cell exhibited excellent rechargeability and rate capability with a low overpotential gap (0.7 V) and high round-trip efficiency (81%). We believe that our approach opens a new avenue for synthesizing robust and binder-free electrodes that can be utilized to build not only metal-air batteries but also other energy systems such as supercapacitors, metal-ion batteries and fuel cells.ope
Seed-mediated atomic-scale reconstruction of silver manganate nanoplates for oxygen reduction towards high-energy aluminum-air flow batteries
Aluminum-air batteries are promising candidates for next-generation high-energy-density storage, but the inherent limitations hinder their practical use. Here, we show that silver nanoparticle-mediated silver manganate nanoplates are a highly active and chemically stable catalyst for oxygen reduction in alkaline media. By means of atomic-resolved transmission electron microscopy, we find that the formation of stripe patterns on the surface of a silver manganate nanoplate originates from the zigzag atomic arrangement of silver and manganese, creating a high concentration of dislocations in the crystal lattice. This structure can provide high electrical conductivity with low electrode resistance and abundant active sites for ion adsorption. The catalyst exhibits outstanding performance in a flow-based aluminum-air battery, demonstrating high gravimetric and volumetric energy densities of similar to 2552 Wh kg(Al)(-1) and similar to 6890 Wh I-Al(-1) at 100 mA cm(-2), as well as high stability during a mechanical recharging process
Tuning the Catalytic Activity of Graphene Nanosheets for Oxygen Reduction Reaction via Size and Thickness Reduction
Currently, the fundamental factors that control the oxygen reduction reaction
(ORR) activity of graphene itself, in particular the dependence of the ORR
activity on the number of exposed edge sites remain elusive, mainly due to
limited synthesis routes of achieving small size graphene. In this work, the
synthesis of low oxygen content (< 2.5 +/-0.2 at %), few layer graphene
nanosheets with lateral dimensions smaller than a few hundred nm was achieved
using a combination of ionic liquid assisted grinding of high purity graphite
coupled with sequential centrifugation. We show for the first time, that the
graphene nanosheets possessing a plethora of edges exhibited considerably
higher electron transfer numbers compared to the thicker graphene
nanoplatelets. This enhanced ORR activity was accomplished by successfully
exploiting the plethora of edges of the nanosized graphene as well as the
efficient electron communication between the active edge sites and the
electrode substrate. The graphene nanosheets were characterized by an onset
potential of -0.13 V vs. Ag/AgCl and a current density of -3.85 mA/cm2 at -1 V,
which represent the best ORR performance ever achieved from an undoped carbon
based catalyst. This work demonstrates how low oxygen content nanosized
graphene synthesized by a simple route can considerably impact the ORR
catalytic activity and hence it is of significance in designing and optimizing
advanced metal-free ORR electrocatalysts.Comment: corresponding author: [email protected], ACS Applied
Materials and Interfaces 201
Synergistic effect of quinary molten salts and Ruthenium catalyst for high-power-density Lithium-carbon dioxide cell
With a recent increase in interest in metal-gas batteries, the lithium-carbon dioxide cell has attracted considerable attention because of its extraordinary carbon dioxide-capture ability during the discharge process and its potential application as a power source for Mars exploration. However, owing to the stable lithium carbonate discharge product, the cell enables operation only at low current densities, which significantly limits the application of lithium-carbon dioxide batteries and effective carbon dioxide-capture cells. Here, we investigate a high-performance lithium-carbon dioxide cell using a quinary molten salt electrolyte and ruthenium nanoparticles on the carbon cathode. The nitrate-based molten salt electrolyte allows us to observe the enhanced carbon dioxide-capture rate and the reduced discharge-charge over-potential gap with that of conventional lithium-carbon dioxide cells. Furthermore, owing to the ruthernium catalyst, the cell sustains its performance over more than 300 cycles at a current density of 10.0Ag(-1) and exhibits a peak power density of 33.4mWcm(-2). Lithium-carbon dioxide cells are challenging due to the sluggish electron transfer in the Lithium carbonate in aprotic electrolyte. Here, the authors report synergistic effect of molten salt electrolyte and Ruthenium catalyst to enhance the electrochemical performance of Lithium-carbon dioxide batterie
Comparative study of the implementation of tin and titanium oxide nanoparticles as electrodes materials in Li-ion batteries
Transition metal oxides potentially present higher specific capacities than the current anodes based on carbon, providing an increasing energy density as compared to commercial Li-ion batteries. However, many parameters could influence the performance of the batteries, which depend on the processing of the electrode materials leading to different surface properties, sizes or crystalline phases. In this work a comparative study of tin and titanium oxide nanoparticles synthesized by different methods, undoped or Li doped, used as single components or in mixed ratio, or alternatively forming a composite with graphene oxide have been tested demonstrating an enhancement in capacity with Li doping and better cyclability for mixed phases and composite anodes
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