| 1. |
- Kim, Jae-Kwang, 1978, et al.
(författare)
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Electrochemical properties of a full cell of lithium iron phosphate cathode using thin amorphous silicon anode
- 2014
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Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738. ; 268:Part B, s. 256-260
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Tidskriftsartikel (refereegranskat)abstract
- Carbon-coated lithium iron phosphate (LiFePO4/C) with uniform carbon coating was synthesized by a mechanical activation method. Silicon negative electrode material was obtained in the form of thin films of amorphous silicon on a Cu foil substrate by vertical deposition technique. The electrochemical performance of the full cell, LiFePO4/C-Si, was tested with 1 M LiPF6 in EC/DMC at 0.5 and 1 C-rates. The cell exhibited an initial discharge capacity of 143.9 mAh g(-1) at 0.5 C-rate at room temperature. A reasonably good cycling performance under a high current density of 1 C-rate could be obtained with the full cell.
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| 2. |
- Haridas, Anupriya K., et al.
(författare)
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A flexible and free-standing FeS/sulfurized polyacrylonitrile hybrid anode material for high-rate sodium-ion storage
- 2020
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 385:1 April
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Tidskriftsartikel (refereegranskat)abstract
- Sodium-ion based energy storage systems have attracted extensive attention due to the similarities in the mechanism of operation with lithium-ion batteries along with the additional benefit of low cost and high abundance of sodium resources. Iron sulfide-based electrodes that operate via conversion mechanism have shown ample potential for high energy sodium-ion storage. However, the problems related with tremendous volume changes and the dissolution of sodium polysulfides in the electrolyte deteriorate the cycle life and limit their application in sodium-ion batteries (SIBs). Herein, a hybrid anode material, FeS/SPAN-HNF, with iron sulfide (FeS) nanoparticles decorated in a sulfurized polyacrylonitrile (SPAN) fiber matrix is demonstrated as flexible and free-standing anode material for high-rate SIBs. Unlike previous strategies in which FeS is encapsulated in an electrochemically inactive carbon matrix, this study utilizes SPAN, an electrochemically active material, as a dual functional matrix that can efficiently buffer volume expansion and sulfur dissolution of FeS nanoparticles as well as provide significant capacity improvement. The as-designed electrode is self-standing and flexible, without current collectors, binders or additional conductive agents, thus rendering enhanced practical capacity and energy density. This electrode showed a high reversible capacity of 782.8 mAh g−1 at 200 mA g−1 with excellent high rate capability, maintaining 327.5 mAh g−1 after 500 cycles at 5 A g−1, emphasizing promising prospects for the development of flexible and high energy density SIBs.
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| 3. |
- Haridas, Anupriya K., et al.
(författare)
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Boosting High Energy Density Lithium-Ion Storage via the Rational Design of an FeS-Incorporated Sulfurized Polyacrylonitrile Fiber Hybrid Cathode
- 2019
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 11:33, s. 29924-29933
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Tidskriftsartikel (refereegranskat)abstract
- In order to satisfy the escalating energy demands, it is inevitable to improve the energy density of current Li-ion batteries. As the development of high-capacity cathode materials is of paramount significance compared to anode materials, here we have designed for the first time a unique synergistic hybrid cathode material with enhanced specific capacity, incorporating cost-effective iron sulfide (FeS) nanoparticles in a sulfurized polyacrylonitrile (SPAN) nanofiber matrix through a rational in situ synthesis strategy. Previous reports on FeS cathodes are scarce and consist of an amorphous carbon matrix to accommodate the volume changes encountered during the cycling process. However, this inactive buffering matrix eventually increases the weight of the cell, reducing the overall energy density. By the rational design of this hybrid composite cathode, we ensure that the presence of covalently bonded sulfur in SPAN guarantees high sulfur utilization, while effectively buffering the volume changes in FeS. Meanwhile, FeS can compensate for the conductivity issues in the SPAN, thereby realizing a synergistically driven dual-active cathode material improving the overall energy density of the composite. Simultaneous in situ generation of FeS nanoparticles within the SPAN fiber matrix was carried out via electrospinning followed by a one-step heating procedure. The developed hybrid cathode material displays enhanced lithium-ion storage, retaining 688.6 mA h g(FeS@SPAN composite)-1 at the end of 500 cycles at 1 A g-1 even within a narrow voltage range of 1-3.0 V. A high discharge energy density > 900 W h kg(FeS@SPAN composite)-1, much higher than the theoretical energy density of the commercial LiCoO2 cathode, was also achieved, revealing the promising prospects of this hybrid cathode material for high energy density applications.
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| 4. |
- Kim, Jae-Kwang, 1978, et al.
(författare)
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2,3,6,7,10,11-Hexamethoxytriphenylene (HMTP): A new organic cathode material for lithium batteries
- 2012
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Ingår i: Electrochemistry Communications. - : Elsevier BV. - 1388-2481. ; 21:1, s. 50-53
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Tidskriftsartikel (refereegranskat)abstract
- We propose a new organic cathode material for rechargeable lithium battery applications: 2,3,6,7,10,11-hexamethoxytriphenylene (HMTP). HMTP is composed of six methoxy functional groups substituted onto a central triphenylene moiety. The cell, incorporating 40 wt.% of organic cathode material, exhibits full specific capacity at current densities up to 3 C. The main advantage of HMTP as organic cathode material lies in a stable cell performance and negligible self discharge, even though the capacity is lower, similar to 66 mAh/g, compared to other organic cathode materials. Cells with the HMTP cathode showed >95% retention of the initial discharge capacity after 50 cycles at 1 C and self-discharge was not observed during a full month of open circuit voltage measurements. The latter is due to the fact that the nature of the HMTP radical is fundamentally different from other organic cathode materials' radicals.
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| 5. |
- Kim, Jae-Kwang, 1978, et al.
(författare)
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An Imidazolium based ionic liquid electrolyte for lithium batteries
- 2010
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 195:22, s. 7639-7643
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Tidskriftsartikel (refereegranskat)abstract
- An electrolyte for lithium batteries based on the ionic liquid 3-methy-1-propylimidazolium bis(trifluoromethysulfony)imide (PMIMTFSI) complexed with lithium bis(trifluoromethysulfony)imide (LiTFSI) at a molar ratio of 1:1 has been investigated. The electrolyte shows a high ionic conductivity (1.2 × 10−3 S cm−1) at room temperature. Over the whole investigated temperature range the ionic conductivity is more than one order of magnitude higher than for an analogue electrolyte based on N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide (Py14TFSI) complexed with LiTFSI and used here as a benchmark. Raman results indicate furthermore that the degree of lithium coordinated TFSI is slightly lower in the electrolyte based on PMIMTFSI and thus that the Li+ charge carriers should be higher than in electrolytes based on Py14TFSI. An ionic liquid gel electrolyte membrane was obtained by soaking a fibrous fully interconnected membrane, made of electrospun P(VdF-HFP), in the electrolyte. The gel electrolyte was cycled in Li/ionic liquid polymer electrolyte/Li cells over 15 days and in Li/LiFePO4 cells demonstrating good interfacial stability and highly stable discharge capacities with a retention of >96% after 50 cycles (146 mAh g−1).
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| 6. |
- Kim, Jae-Kwang, 1978, et al.
(författare)
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Characterization of N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide-based polymer electrolytes for high safety lithium batteries
- 2013
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 224:15 Feb. 2013, s. 93-98
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Tidskriftsartikel (refereegranskat)abstract
- Poly(vinylidene difluoride-co-hexafluoropropylene) (PVdF-HFP) membrane was prepared by electrospinning. The membranes served as host matrices for the preparation of ionic liquid-based polymer electrolytes (ILPEs) by activation with non-volatile, highly thermally stable, and safe room temperature ionic liquid (RTIL) electrolytes; N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide (Py14TFSI) complexed with 1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). In this work, the first combination of electrospun PVdF-HFP fiber polymer host and pyrrolidinium-based ionic electrolyte was employed for highly stable lithium batteries. The ILPE exhibited low Li+-TFSI coordination, low crystallinity, high thermal stability, high electrochemical stability, and high ionic conductivity with a maximum of 1.1 x 10(-4) S cm(-1) at 0 degrees C. The ILPE exhibited good compatibility with a LiFePO4 electrode on storage and good charge-discharge performance in Li/ILPE/LiFePO4!
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| 7. |
- Kim, Jae-Kwang, 1978, et al.
(författare)
-
Effect of carbon coating methods on structural characteristics and electrochemical properties of carbon-coated lithium iron phosphate
- 2014
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Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738. ; 262, s. 25-29
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Tidskriftsartikel (refereegranskat)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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| 8. |
- Kim, Jae-Kwang, 1978, et al.
(författare)
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Highly porous LiMnPO4 in combination with an ionic liquid-based polymer gel electrolyte for lithium batteries
- 2011
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Ingår i: Electrochemistry Communications. - : Elsevier BV. - 1388-2481. ; 13:10, s. 1105-1108
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Tidskriftsartikel (refereegranskat)abstract
- A porous well defined LiMnPO(4) cathode material is synthesized by a sol-gel method. The electrochemical performance of the cathode material is evaluated in a cell with an ionic liquid-based polymer electrolyte (0.5 M LITFSI in EMlmTFSI) and a lithium metal electrode. The results are compared to a cell with a traditional organic carbonate-based electrolyte (1 M LiPF(6) in EC/DMC). The cell with the ionic liquid-based polymer electrolyte presents an enhanced electrochemical intercalation performance of lithium ions, a high electrochemical stability window of 5 V, and an excellent cycling ability as compared with the organic based counterpart. Furthermore, the ionic liquid-based polymer gel electrolyte effectively prevents the dissolution of manganese - otherwise a common problem.
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| 9. |
- Kim, Jae-Kwang, 1978, et al.
(författare)
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Improving the stability of an organic battery with an ionic liquid-based plymer electrolyte
- 2012
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 2:26, s. 9795-9797
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Tidskriftsartikel (refereegranskat)abstract
- A gel polymer electrolyte based on the ionic liquid {N-butyl-N-methyl-pyrrolidiniumbis(trifluoromethanesulfonyl) imide (Py14TFSI) and lithium bis(trifluoromethanesulfony)imide (LiTFSI)} is shown to prevent the dissolution from an organic electrode. The composite cell shows high energy efficiency although poor cycle stability is exhibited at very high current density (10 C-rate).
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| 10. |
- Kim, Jae-Kwang, 1978, et al.
(författare)
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Nano-fibrous polymer films for organic rechargeable batteries
- 2013
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 1:7, s. 2426-2430
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Tidskriftsartikel (refereegranskat)abstract
- We propose a nano-fibrous polymer (NFP) film, fabricated by electrospinning poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA), as a key component in high performance organic batteries. The new strategy with a NFP film enables extraordinary rate capability and excellent cyclability, due to its special morphology. Moreover, the NFP film enhances the flexibility of the electrode at a low cost and prevents dissolution of PTMA into the electrolyte.
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