| 1. |
- Hollmark, Håkan M., et al.
(författare)
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Resonant Soft X-Ray Emission Spectroscopy and X-Ray Absorption Spectroscopy on the Cathode Material LiNi0.65Co0.25Mn0.1O2
- 2010
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 157:8, s. A962-A966
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Tidskriftsartikel (refereegranskat)abstract
- We present a study of the charge-state behavior of the Li-ion battery cathode material LixNi(0.65)Co(0.25)Mn(0.1)O(2) as observed by X-ray absorption spectroscopy (XAS) and resonant soft X-ray emission (RSXE). A set of six identical Li//LixNi0.65Co0.25Mn0.1O2 batteries has been cycled and is studied in different states of charge in the range of x = 1.0, ... ,0.2 before disassembly in an Ar glove box. Site and symmetry selective information about the electronic structure of the conduction and valence bands reveals that Ni as well as Co ions participate in the uptake and release of the extra electron charge that the inserted Li ions provide, but the Ni ion is much less than expected. The net amount of charge on the oxygen varies approximately 0.24 charge units in the range of x, and dramatic changes in the hybridization are evident in XAS and in particular in RSXE at the O K edge. We attribute this to a strong screening behavior of the Li ions between the oxide layers. Structural integrity effects limit the extraction of Li ions to a value of about x = 0.2-0.4. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3454739] All rights reserved.
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| 2. |
- Kam, Kinson C., et al.
(författare)
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Synthesis and electrochemical properties of nanostructured Li(2)FeSiO(4)/C cathode material for Li-ion batteries
- 2011
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Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738 .- 1872-7689. ; 192:1, s. 356-359
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Tidskriftsartikel (refereegranskat)abstract
- Nanostructured Li(2)FeSiO(4)/C was synthesized by high-energy ball-milling and the amorphous citrate-assisted techniques. Similar redox behaviour is observed for samples prepared by the amorphous citrate-assisted route followed by a 4 h heat treatment: 0.3 V polarization and more sloping behaviour was observed when cycling between 2.0 V and 3.7 V at 60 degrees C; lower capacity fade is also observed compared to Li(2)FeSiO(4)/C prepared by the solid-state reaction technique. A discharge capacity of 102 mA h g(-1) is obtained for samples prepared by the high-energy ball-milling method, while capacities decrease from 95 to 77 mA h g(-1) using the amorphous citrate method for heat-treatment times increasing successively from 4 h to 18 h.
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| 3. |
- Renman, Viktor, et al.
(författare)
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Structural-electrochemical relations in the aqueous copper hexacyanoferrate-zinc system examined by synchrotron X-ray diffraction
- 2017
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 369, s. 146-153
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Tidskriftsartikel (refereegranskat)abstract
- The storage process of Zn2+ in the Prussian blue analogue (PBA) copper hexacyanoferrate (Cu[Fe(CN)(6)](2/3)-nH(2) O-CuHCF) framework structure in a context of rechargeable aqueous batteries is examined by means of in operando synchrotron X-ray diffraction. Via sequential unit-cell parameter refinements of time-resolved diffraction data, it is revealed that the step-profile of the cell output voltage curves during repeated electrochemical insertion and removal of Zn2+ in the CuHCF host structure is associated with a non-linear contraction and expansion of the unit-cell in the range 0.36 < x < 1.32 for Znx/3Cu[Fe(CN)(6)](2/3)-nH(2)O. For a high insertion cation content there is no apparent change in the unit-cell contraction. Furthermore, a structural analysis with respect to the occupancies of possible Zn2+ sites suggests that the Fe(CN)(6) vacancies within the CuHCF framework play an important role in the structural-electrochemical behavior of this particular system. More specifically, it is observed that Zn2+ swaps position during electrochemical cycling, hopping between cavity sites to vacant ferricyanide sites.
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| 4. |
- Tan, Semra, et al.
(författare)
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Poly(ether amine) and cross-linked poly(propylene oxide) diacrylate thin-film polymer electrolyte for 3D-microbatteries
- 2010
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Ingår i: Electrochemistry communications. - : Elsevier BV. - 1388-2481 .- 1873-1902. ; 12:11, s. 1498-1500
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a novel thin-film electrolyte of a 2:1 blend of polyetheramine (glyceryl poly(oxypropylene)) and cross-linked oligomeric poly(propylene oxide) diacrylate with LiTFSI. The polyetheramine acts as a surfactant, and can thereby be applied as a conformal coating on complex surfaces-here demonstrated for porous LiFePO4 cathodes-making it useful for 3D-microbatteries. The poly(propylene oxide) diacrylate blends with the surfactant and is easily UV cross-linked, thereby ensuring good mechanical stability. Electrolytes, ∼ 2 μm thick, were casted onto LiFePO 4 cathodes and cycled against metallic lithium, displaying stable discharge capacities of ∼ 8 mAh/g at room temperature and ∼ 120 mAh/g at 60 °C. The electrolyte showed conductivities of 3.45 × 10 - 6 and 5.80 × 10- 5 S cm- 1 at room temperature and 60 °C, respectively.
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| 5. |
- Cheah, Seng Kian, et al.
(författare)
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Self-Supported Three-Dimensional Nanoelectrodes for Microbattery Applications
- 2009
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Ingår i: Nano letters (Print). - : American Chemical Society. - 1530-6984 .- 1530-6992. ; 9:9, s. 3230-3233
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Tidskriftsartikel (refereegranskat)abstract
- A nanostructured three-dimensional (3D) microbattery has been produced and cycled in a Li-ion battery. It consists of a current collector of aluminum nanorods, a uniform layer of 17 nm TiO2 covering the nanorods made using ALD, an electrolyte and metallic lithium counter electrode. The battery is electrochemically cycled more than 50 times. The increase in total capacity is 10 times when using a 3D architechture compared to a 2D system for the same footprint area.
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| 6. |
- Dahbi, Mohammed, et al.
(författare)
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A delithiated LiNi0.65Co0.25Mn0.10O2 electrode material : A structural, magnetic and electrochemical study
- 2009
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Ingår i: Electrochimica Acta. - : Elsevier Ltd. - 0013-4686 .- 1873-3859. ; 54:11, s. 3211-3217
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Tidskriftsartikel (refereegranskat)abstract
- A crystalline LiNi0.65Co0.25Mn0.10O2 electrode material was synthesized by the combustion method at 900 °C for 1 h. Rietveld refinement shows less than 3% of Li/Ni disorder in the structure. Lithium extraction involves only the Ni2+/Ni4+ redox couple while Co3+ and Mn4+ remain electrochemically inactive. No structural transition was detected during cycling in the whole composition range 0 < x < 1.0. Furthermore, the hexagonal cell volume changes by only 3% when all lithium was removed indicating a good mechanical stability of the studied compound. LiNi0.65Co0.25Mn0.10O2 has a discharge capacity of 150 mAh/g in the voltage range 2.5–4.5 V, but the best electrochemical performance was obtained with an upper cut-off potential of 4.3 V. Magnetic measurements reveal competing antiferromagnetic and ferromagnetic interactions – varying in strength as a function of lithium content – yielding a low temperature magnetically frustrated state. The evolution of the magnetic properties with lithium content confirms the preferential oxidation of Ni ions compared to Co3+ and Mn4+ during the delithiation process.
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| 7. |
- Sisbandini, Ciptanti, et al.
(författare)
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Effect of Short-Chain Amine Coatings on the Performance of LiFePO4 Li-Ion Battery Cathodes
- 2009
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Ingår i: Electrochemical and solid-state letters. - : The Electrochemical Society. - 1099-0062 .- 1944-8775. ; 12:5, s. A99-A101
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Tidskriftsartikel (refereegranskat)abstract
- Thispaper probes the coating of LiFePO4 (Phostech Lithium) particles bythe self-adsorbance of surfactant molecules. The presence of the short-chainamines: hexadecylamine and polyetheramine [glyceryl poly(oxypropylene)triamine] on the particles isconfirmed qualitatively by X-ray photoelectron spectroscopy analysis, and the Brunauer–Emmett–Tellersurface area of the amine-coated LiFePO4 decreases with increasing amountsof amine on the surface. LiFePO4 with a 1 wt % polyetheraminecoating exhibits a capacity of ~160 mAh/g, i.e., 13% higher thancould be achieved with the as-received LiFePO4. A small amountof oligomeric coating would thus appear to be capable ofincreasing ion transport close to the particle surface.
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| 8. |
- Sisbandini, Ciptanti, et al.
(författare)
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The Mechanism of Capacity Enhancement in LiFePO4 Cathodes Through Polyetheramine Coating
- 2009
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 156:9, s. A720-A725
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Tidskriftsartikel (refereegranskat)abstract
- Thispaper addresses the possible mechanisms underlying the capacity enhancement throughpolyetheramine [PEA, glyceryl poly(oxypropylene)triamine] coating on LiFePO4 (Phostech Lithium) particlesurface. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared studieshave confirmed the presence of PEA on the surface bythe appearance of the N 1s peak in the XPSspectra and bands in the 2850–2960 cm−1 wavenumber range of theIR spectra. Potentiostatic measurements in organic electrolytes have shown thatthe discharge capacity is increased ca. 12% compared to theas-received material, i.e., more Fe2+/Fe3+ ions are utilized during theredox process. This is due to better wettability of theelectrolyte to the particle surface, which is indicated by theslower sedimentation of coated particles. Furthermore, cyclic voltammetry has shownthat PEA-coated particles display higher capacity than the as-received materialalso in an aqueous electrolyte, which to some extent canbe explained by the difference in wettability between the materials,but also by the protection of LiFePO4 from spontaneous formationof a Li3PO4 surface layer and Fe3+-containing solids when incontact with water.
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| 9. |
- Oltean, Gabriel, et al.
(författare)
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Towards Li-ion batteries operating at 80 °C: Ionic liquid versus conventional liquid electrolytes
- 2018
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Ingår i: Batteries. - : MDPI AG. - 2313-0105. ; 4, s. 2-6
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Tidskriftsartikel (refereegranskat)abstract
- Li-ion battery (LIB) full cells comprised of TiO2-nanotube (TiO2-nt) and LiFePO4 (LFP)electrodes and either a conventional organic solvent based liquid electrolyte or an ionic liquid basedelectrolyte have been cycled at 80 °C. While the cell containing the ionic liquid based electrolyteexhibited good capacity retention and rate capability during 100 cycles, rapid capacity fading was found for the corresponding cell with the organic electrolyte. Results obtained for TiO2-nt and LFP half-cells indicate an oxidative degradation of the organic electrolyte at 80 °C. In all, ionic liquidbased electrolytes can be used to significantly improve the performance of LIBs operating at 80 °C.
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| 10. |
- Ojwang, Dickson O., et al.
(författare)
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Structure Characterization and Properties of K-Containing Copper Hexacyanoferrate
- 2016
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 55:12, s. 5924-5934
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Tidskriftsartikel (refereegranskat)abstract
- Copper hexacyanoferrate, Cu-II[Fe-III(CN)(6)](2/3)center dot nH(2)O, was synthesized, and varied amounts of IC ions were inserted via reduction by K2S2O3 (aq). Ideally, the reaction can be written as Cu-II[Fe-III(CN)(6)](2/3)-nH(2)O + 2x/3K(+) + 2x/3e(-)K(+) <-> K-2x/3 Cu-II[Fe-x(II).Fe-1-x(II),(CN)(6)](2/3)-nH(2)O. Infrared, Raman, and Mossbauer spectroscopy studies show that Fe-II is continuously reduced to Fell with increasing x, accompanied by a decrease of the a-axis of the cubic Fn (3) over barm unit cell. Elemental analysis of K by inductively coupled plasma shows that the insertion only begins when a significant fraction similar to 10% of the Fe-III, has already been reduced. Thermogravimetric analysis shows a fast exchange of water with ambient atmosphere and a total weight loss of similar to 26 wt % upon heating to 180 degrees C, above which the structure starts to decompose. The crystal structures of Cu-III[Fe-III(CN)(6)](2/3)center dot nH(2)O and K2/3Cu[Fe(CN)(6)](2/3)center dot nH(2)O were refined using synchrotron X-ray powder diffraction data. In both, one-third of the Fe(CN)(6) groups are vacant, and the octahedron around Cull is completed by water molecules. In the two structures, difference Fourier maps reveal three additional zeolitic water sites (8c, 32f, and 48g) in the center of the cavities formed by the-Cu-N-C-Fe- framework. The K-containing compound shows an increased electron density at two of these sites (32f and 48g), indicating them to be the preferred positions for the K+ ions.
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