| 1. |
- Haridas, Anupriya K., et al.
(author)
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An Electrospun Core–Shell Nanofiber Web as a High-Performance Cathode for Iron Disulfide-Based Rechargeable Lithium Batteries
- 2018
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 11:20, s. 3625-3630
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Journal article (peer-reviewed)abstract
- FeS2/C core–shell nanofiber webs were synthesized for the first time by a unique synthesis strategy that couples electrospinning and carbon coating of the nanofibers with sucrose. The design of the one-dimensional core–shell morphology was found to be greatly beneficial for accommodating the volume changes encountered during cycling, to induce shorter lithium ion diffusion pathways in the electrode, and to prevent sulfur dissolution during cycling. A high discharge capacity of 545 mAh g−1 was retained after 500 cycles at 1 C, exhibiting excellent stable cycling performance with 98.8 % capacity retention at the last cycle. High specific capacities of 854 mAh g−1, 518 mAh g−1, and 208 mAh g−1 were obtained at 0.1 C, 1 C, and 10 C rates, respectively, demonstrating the exceptional rate capability of this nanofiber web cathode.
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| 2. |
- Xiong, Shizhao, 1985, et al.
(author)
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Role of organic solvent addition to ionic liquid electrolytes for lithium–sulphur batteries
- 2015
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In: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069.
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Journal article (peer-reviewed)abstract
- We investigate the role of the addition of an organic solvent to an ionic liquid electrolyte for the performance of lithium–sulphur (Li–S) batteries. We find that with a mixed electrolyte, formed by adding 10 wt% 1,3-dioxolane (DIOX) to an ionic liquid, the capacity of a Li–S cell is more than doubled, the rate capability and the cycling performance considerably improved, compared to a cell utilizing a neat ionic liquid electrolyte. The improved performance can be correlated with an enhanced ion transport, evidenced by an increased ionic conductivity and higher limiting current density, directly related to a decrease in viscosity and glass transition temperature of the mixed electrolytes. We show that this in turn is linked to a change in the local environment of the Li-ions where the organic solvent is incorporated in the coordination shell. In addition we show that the mixed electrolytes have a considerably higher thermal stability, in particular a dramatically increased flash point, and improved low temperature properties with respect to a conventional organic solvent based electrolyte currently used for Li–S batteries.
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| 3. |
- Agostini, Marco, 1987, et al.
(author)
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Free-Standing 3D-Sponged Nanofiber Electrodes for Ultrahigh-Rate Energy-Storage Devices
- 2018
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In: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 10:40, s. 34140-34146
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Journal article (peer-reviewed)abstract
- We have designed a self-standing anode built-up from highly conductive 3D-sponged nanofibers, that is, with no current collectors, binders, or additional conductive agents. The small diameter of the fibers combined with an internal spongelike porosity results in short distances for lithium-ion diffusion and 3D pathways that facilitate the electronic conduction. Moreover, functional groups at the fiber surfaces lead to the formation of a stable solid-electrolyte interphase. We demonstrate that this anode enables the operation of Li-cells at specific currents as high as 20 A g-1 (approx. 50C) with excellent cycling stability and an energy density which is >50% higher than what is obtained with a commercial graphite anode.
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| 4. |
- Agostini, Marco, 1987, et al.
(author)
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Rational Design of Low Cost and High Energy Lithium Batteries through Tailored Fluorine-free Electrolyte and Nanostructured S/C Composite
- 2018
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 11:17, s. 2981-2986
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Journal article (peer-reviewed)abstract
- We report a new Li–S cell concept based on an optimized F-free catholyte solution and a high loading nanostructured C/S composite cathode. The Li2S8present in the electrolyte ensures both buffering against active material dissolution and Li+conduction. The high S loading is obtained by confining elemental S (≈80 %) in the pores of a highly ordered mesopores carbon (CMK3). With this concept we demonstrate stabilization of a high energy density and excellent cycling performance over 500 cycles. This Li–S cell has a specific capacity that reaches over 1000 mA h g−1, with an overall S loading of 3.6 mg cm−2and low electrolyte volume (i.e., 10 μL cm−2), resulting in a practical energy density of 365 Wh kg−1. The Li–S system proposed thus meets the requirements for large scale energy storage systems and is expected to be environmentally friendly and have lower cost compared with the commercial Li-ion battery thanks to the removal of both Co and F from the overall formulation.
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| 5. |
- Agostini, Marco, 1987, et al.
(author)
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Stabilizing the Performance of High-Capacity Sulfur Composite Electrodes by a New Gel Polymer Electrolyte Configuration
- 2017
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In: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 10:17, s. 3490-3496
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Journal article (peer-reviewed)abstract
- Increased pollution and the resulting increase in global warming are drawing attention to boosting the use of renewable energy sources such as solar or wind. However, the production of energy from most renewable sources is intermittent and thus relies on the availability of electrical energy-storage systems with high capacity and at competitive cost. Lithium–sulfur batteries are among the most promising technologies in this respect due to a very high theoretical energy density (1675 mAh g?1) and that the active material, sulfur, is abundant and inexpensive. However, a so far limited practical energy density, life time, and the scaleup of materials and production processes prevent their introduction into commercial applications. In this work, we report on a simple strategy to address these issues by using a new gel polymer electrolyte (GPE) that enables stable performance close to the theoretical capacity of a low cost sulfur–carbon composite with high loading of active material, that is, 70 % sulfur. We show that the GPE prevents sulfur dissolution and reduces migration of polysulfide species to the anode. This functional mechanism of the GPE membranes is revealed by investigating both its morphology and the Li-anode/GPE interface at various states of discharge/charge using Raman spectroscopy.
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| 6. |
- Amin, Muhammad, 1979, et al.
(author)
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Coin-cell Supercapacitors Based on CVD Grown and Vertically Aligned Carbon Nanofibers (VACNFs)
- 2017
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In: International Journal of Electrochemical Science. - : Elsevier BV. - 1452-3981. ; 12:7, s. 6653-6661
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Journal article (peer-reviewed)abstract
- Complete supercapacitors (SCs) comprising vertically aligned carbon nanofibers (VACNFs) as electrode materials have been assembled as coin-cells. The VACNFs were grown directly onto the current collector by direct current plasma enhanced chemical vapor deposition (DC-PECVD), thereby providing excellent contact with the current collector, but also eliminating the need of any binder. The vertical alignment facilitates fast ion transport and the electrolyte to access the entire surface of the CNFs. The morphology of the VACNFs was evaluated by scanning electron microscopy (SEM), while the performance was assessed by several methods: cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and device related cycling by galvanostatic charge/discharge. The capacitance, 3.64 mF/cm2 , is >15 times higher than the capacitance of a coin-cell without CNFs and the cyclic performance shows these proof-of-concept SCs to retain >80% of the capacitance after 2000 full charge/discharge cycles. The direct growth of VACNFs as electrodes at the current collector opens pathways for SC production using existing coin-cell battery production technology.
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| 7. |
- Kerner, Manfred, 1984, et al.
(author)
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Towards more thermally stable Li-ion battery electrolytes with salts and solvents sharing nitrile functionality
- 2016
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In: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 332, s. 204-212
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Journal article (peer-reviewed)abstract
- The overall safety of Li-ion batteries is compromised by the state-of-the-art electrolytes; the thermally unstable lithium salt, lithium hexafluorophosphate (LiPF6), and flammable carbonate solvent mixtures. The problem is best addressed by new electrolyte compositions with thermally robust salts in low flammability solvents. In this work we introduce electrolytes with either of two lithium nitrile salts, lithium 4,5-dicyano-1,2,3-triazolate (LiDCTA) or lithium 4,5-dicyano-2-trifluoromethylimidazolide (LiTDI), in solvent mixtures with high flashpoint adiponitrile (ADN), as the main component. With sulfolane (SL) and ethylene carbonate (EC) as co-solvents the liquid temperature range of the electrolytes are extended to lower temperatures without lowering the flashpoint, but at the expense of high viscosities and moderate ionic conductivities. The anodic stabilities of the electrolytes are sufficient for LiFePO4 cathodes and can be charged/discharged for 20 cycles in Li/LiFePO4 cells with coulombic efficiencies exceeding 99% at best. The excellent thermal stabilities of the electrolytes with the solvent combination ADN:SL are promising for future electrochemical investigations at elevated temperatures (> 60 degrees C) to compensate the moderate transport properties and rate capability. The electrolytes with EC as a co-solvent, however, release CO2 by decomposition of EC in presence of a lithium salt, which potentially makes EC unsuitable for any application targeting higher operating temperatures.
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| 8. |
- Kim, Jae-Kwang, 1978, et al.
(author)
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Effect of carbon coating methods on structural characteristics and electrochemical properties of carbon-coated lithium iron phosphate
- 2014
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In: Solid State Ionics. - : Elsevier BV. - 0167-2738. ; 262, s. 25-29
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Journal article (peer-reviewed)abstract
- The potential of LiFePO4 as cathode material has not been fully exploited due to its intrinsic poor electronic and ionic conductivities. Attempts have been made to improve these properties of which coating of the active carbon on the particle surface is the most viable method so far. Phase-pure LiFePO4 and two LiFePO4/C composites were synthesized by mechanical activation process employing two different methods: (i) direct addition of acetylene black carbon and (ii) addition of sucrose as carbon precursor. The samples were well characterized by various techniques like elemental analysis, Brunauer-Emmett-Teller (BET) method, scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and Raman spectroscopy to establish their composition, morphology, particle size and surface area. The structure of these samples is investigated as olivine structure space group Prima by X-ray powder diffraction. Transmission electron microscopy (TEM) confirms that the carbon nanocoating on the LiFePO4 particles has no visible dislocations and fractures. The electrochemical performance of LiFePO4/C is significantly affected by the nature of the carbon nanocoating, which in turn is affected by the choice of synthesis method.
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| 9. |
- Kim, Jae-Kwang, 1978, et al.
(author)
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Rechargeable-hybrid-seawater fuel cell
- 2014
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In: NPG Asia Materials. - : Springer Science and Business Media LLC. - 1884-4049 .- 1884-4057. ; 6:11, s. Article number e144-
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Journal article (peer-reviewed)abstract
- A novel energy conversion and storage system using seawater as a cathode is proposed herein. This system is an intermediate between a battery and a fuel cell, and is accordingly referred to as a hybrid fuel cell. The circulating seawater in this opencathode system results in a continuous supply of sodium ions, which gives this system superior cycling stability that allows the application of various alternative anodes to sodium metal by compensating for irreversible charge losses. Indeed, hard carbon and Sn-C nanocomposite electrodes were successfully applied as anode materials in this hybrid-seawater fuel cell, yielding highly stable cycling performance and reversible capacities exceeding 110 mAh g-1 and 300 mAh g-1, respectively.
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| 10. |
- Lim, Du Hyun, 1983, et al.
(author)
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An Electrospun Nanofiber Membrane as Gel-Based Electrolyte for Room-Temperature Sodium–Sulfur Batteries
- 2018
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In: Energy Technology. - : Wiley. - 2194-4296 .- 2194-4288. ; 6:7, s. 1214-1219
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Journal article (peer-reviewed)abstract
- We report on the synthesis and characterization of an electrospun gel polymer electrolyte (GPE) membrane based on polyacrylonitrile nanofibers (PAN) swollen in a polyethylene glycol dimethyl ether/Na-salt electrolyte solution, for application in room temperature sodium–sulfur (Na–S) batteries. The membranes show a high ionic conductivity, wide electrochemical stability window, and good thermal stability. We demonstrate the performance of the membrane in an Na–S cell using a sulfur–carbon nanotubes composite cathode and Na metal as anode. Our results show that the GPE membrane stabilizes the Na metal anode resulting in stable cycling behavior. The capacity of the Na–S cell, using the GPE membrane and operating at room temperature, is approximately 500 mAh g−1over 40 cycles. The selected electrolyte configuration also provides improved safety by replacing the highly reactive sodium perchlorate (NaClO4) salt previously used in literature. All these benefits make the gel-polymer electrolyte membrane a very promising system for application in room-temperature sodium and sodium–sulfur batteries.
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