| 1. |
- Elbouazzaoui, Kenza, et al.
(författare)
-
NASICON-type Li0.5M0.5Ti1.5Fe0.5(PO4)3 (M = Mn, Co, Mg) phosphates as electrode materials for lithium-ion batteries
- 2021
-
Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 399
-
Tidskriftsartikel (refereegranskat)abstract
- A correlation between the crystal structure, the ionic conductivity and the electrochemical performance in Lithium-ion batteries was established for a series of NASICON-type phosphates Li0.5M0.5Ti1.5Fe0.5(PO4)(3) (M = Mn, Co, Mg). These electrode materials, where the M1 site contains both lithium and the divalent cation M, were prepared using a simple sol-gel process while controlling the pH and the final synthesis temperature. The three phosphates crystallize in the rhombohedral system (S.G. R-3c) with comparable unit cell parameters but with slight difference in the local distortion of the PO4 tetrahedra as confirmed by the Raman study. The ionic conductivities of the Li0.5M0.5Ti1.5Fe0.5(PO4)(3) materials were measured at different temperatures using a wide range of frequencies. Mn-based phosphate shows the best features for application as electrode material for Li-ion batteries in term of the conductivity at room temperature and the activation energy of Li+ conduction process. The initial discharge capacity of 100 mAh.g(-1) was obtained for the Mg-based phosphate, 104.3 mAh.g(-1) for the Co-based material while the Mn-based material delivers the best first discharge capacity of 125.3 mAh.g(-1) with the lowest polarization in relation with its better conduction properties. This result was also confirmed by the rate capability tests where Mn-based phosphate shows enhanced electrochemical performance even at fast rate of 5C.
|
|
| 2. |
- Dahbi, Mohammed, et al.
(författare)
-
A delithiated LiNi0.65Co0.25Mn0.10O2 electrode material : A structural, magnetic and electrochemical study
- 2009
-
Ingår i: Electrochimica Acta. - : Elsevier Ltd. - 0013-4686 .- 1873-3859. ; 54:11, s. 3211-3217
-
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.
|
|
| 3. |
- Dahbi, Mohammed, et al.
(författare)
-
Combustion synthesis and electrochemical performance of Li2FeSiO4/C cathode material for lithium-ion batteries
- 2012
-
Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 205, s. 456-462
-
Tidskriftsartikel (refereegranskat)abstract
- A novel preparation technique was developed for synthesizing Li2FeSiO4/C nanoparticles through combustion of reaction mixtures containing silicon source. Li and Fe sources that operate as oxidizers and sucrose that act as a fuel. A systematic investigation of the synthesis parameters, such as the effect of the fuel content, on purity, morphology and electrochemical properties of the samples was performed. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area (BET) and electrochemical measurements, respectively. Among the synthesized cathode materials, Li2FeSiO4 obtained with 1.5 mol of sucrose, showed the best electrochemical performance in terms of discharge capacity, cycling stability and rate capability. Discharge capacity of 130 mAh/g at C/20, 88 mAh/g at C/2 and 44 mAh/g at 2C were obtained with no capacity fading after 50 cycles.
|
|
| 4. |
- Dahbi, Mohammed, et al.
(författare)
-
Effect of manganese on the structural and thermal stability of Li 0.3Ni0.7 - yCo0.3−yMn2yO2 electrode materials (y =0 and 0.05)
- 2011
-
Ingår i: Solid State Ionics. - : Elsevier. - 0167-2738 .- 1872-7689. ; 203:1, s. 37-41
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal and structural stabilities of Li(0.3)Ni(0.7)Co(0.3)O(2) and Li(0.3)Ni(0.65)Co(0.25)Mn(0.10)O(2) chemically delithiated cathode materials were studied by X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry. The structure of the Li(0.3)Ni(0.7)Co(0.3)O(2) layered material (S.C. R-3 m) transforms first to the spinel-type structure (S.C. Fd3m) and then to the completely disordered Ni0-type structure (S.C. Fm3m). These structural transitions were accompanied by 10.2% oxygen loss and leads to an exothermic reaction, activated by the electrolyte, more energetic than that of Li(0.3)Ni(0.65)Mn(0.10)O(2) manganese substituted electrode. Furthermore, no structural changes were observed during the thermal treatment of Li(0.3)Ni(0.65)Co(0.25)Mn(0.10)O(2) and relatively lower oxygen loss was recorded. The obtained results prove the positive effect of manganese substitution on the electrochemical features of Li(0.3)Ni(0.7)Co(0.3)O(2).
|
|
| 5. |
- Dahbi, Mohammed, et al.
(författare)
-
Electrochemical behavior of LiNi1-y-zCoyMnzO2 probed through structural and magnetic properties
- 2012
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 111:2, s. 023904-
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated LixNi1-y-zCoyMnzO2 compounds with y = 1/3, 0.25, 0.2, 0.1 and z = 1/3, 0.2, 0.1, 0.05 in order to study the influence of Ni and Mn concentration, cationic disorder, and crystallite size on the magnetic and charge/discharge behavior. The samples have been studied by means of x-ray diffraction, scanning electron microscopy, voltammetry, cycling capacity, and magnetometry. The discharge capacity increases with increasing Ni concentration as does the number of ferromagnetic interactions. With higher Mn concentration a higher capacity is observed together with formation of strong antiferromagnetic interactions driving the magnetic frustration to lower temperatures. Our results show that for sufficiently low Co concentrations a stable and magnetically more ordered structure can be obtained with excellent electrochemical properties, although a relatively large amount of Ni is present.
|
|
| 6. |
- Doubaji, Siham, et al.
(författare)
-
Synthesis and characterization of a new layered cathode material for sodium ion batteries
- 2014
-
Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 266, s. 275-281
-
Tidskriftsartikel (refereegranskat)abstract
- Owing to the high abundance of sodium and its low cost compared to lithium, sodium ion batteries have recently attracted a renewed interest as possible candidates for stationary and mobile energy storage devices. Herein, we present a new sodium ion intercalation material, Na5CO2/3Mn2/9Ni1/9O2, which has been synthesized by a sol gel route in air followed by a heat treatment at 800 degrees C for 12 h. Its structure has been studied by X-ray diffraction showing that the material crystallized in a P2-type structure (space group P6(3)/mmc). As far as the electrochemical properties of NaxCo2/3Mn2/9Ni1/9O2 as positive electrode are concerned, this compound offers a specific capacity of 110 mAh g(-1) when cycled between 2.0 and 4.2 V vs. Na+/Na. The electrodes exhibited a good capacity retention and a coulombic efficiency exceeding 99.4%, as well as a reversible discharge capacity of 140 mAh g(-1) when cycled between 2.0 and 4.5 V. These results represent a further step towards the realization of efficient sodium ion batteries, especially considering that the synthesis method proposed here is simple and cost effective and that all the electrochemical measurements were carried out without any use of additives or any optimization for both the materials and the cell components.
|
|
| 7. |
- Hollmark, Håkan M., et al.
(författare)
-
Resonant Soft X-Ray Emission Spectroscopy and X-Ray Absorption Spectroscopy on the Cathode Material LiNi0.65Co0.25Mn0.1O2
- 2010
-
Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 157:8, s. A962-A966
-
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.
|
|
| 8. |
- Lasri, Karime, et al.
(författare)
-
Intercalation and conversion reactions in Ni0.5TiOPO4 Li-ion battery anode materials
- 2013
-
Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 229, s. 265-271
-
Tidskriftsartikel (refereegranskat)abstract
- The Ni0.5TiOPO4/C composite Li-ion battery anode material has been prepared by a sol-gel method with a subsequent pyrolysis step for the formation of C-coating. The resulting sub-micronsized particles displayed a narrow particle size distribution and a corresponding high electrochemical activity which, in turn, facilitates in-depth analysis of the electrochemical behavior of the material. It is shown that by limiting the degree of lithiation in the material, the redox potential in subsequent cycles is substantially affected. Ex-situ XRD reveals a gradual evolution of the structure during cycling of the material, with lower crystallinity after the first discharge cycle. By correlating the electrochemical properties with the structural studies, new insights into the electrochemical behavior of the Ni0.5TiOPO4/C anode material are achieved, suggesting a combination of intercalation and conversion reactions.
|
|
| 9. |
- Liu, Jia, et al.
(författare)
-
Accelerated Electrochemical Decomposition of Li2O2 under X-ray Illumination
- 2013
-
Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 4:23, s. 4045-4050
-
Tidskriftsartikel (refereegranskat)abstract
- This work presents the first report detailing the effect of X-rays on the electrochemical decomposition of Li2O2, which is the main reaction during the charging process in a Li-O-2 battery. An operando synchrotron radiation powder X-ray diffraction (SR-PXD) experiment was performed. The results indicate that the electrochemical decomposition of Li2O2 is dramatically accelerated under X-ray irradiation. The accelerated decomposition of Li2O2 follows a zero-order reaction, and the decomposition rate constant is proportional to the intensity of X-ray used. A mechanism for the electrochemical decomposition of Li2O2 under X-ray irradiation is proposed. These results give an insight into the charging process in Li-O-2 batteries.
|
|
| 10. |
|
|
| 11. |
- Saadoune, Ismael, et al.
(författare)
-
Effect of the synthesis temperature on the structure and electrochemical behaviour of the LiNi0.65Co0.25Mn0.1O2 positive electrode material
- 2008
-
Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738 .- 1872-7689. ; 178:31-32, s. 1668-1675
-
Tidskriftsartikel (refereegranskat)abstract
- Three kinds of LiNi0.65Co0.25Mn0.1O2 samples were prepared using a combustion method at different synthetic conditions (C1: 900 °C/1 h; C2: 900 °C/12 h and C3: 1000 °C/12 h). The samples were characterized using X-ray diffraction, scanning electron microscopy and magnetization measurements before their use as positive electrode material in lithium-ion batteries. Sample C1 presents the most ordered structure with less than 3% of nickel ions in the lithium plane. Increasing synthesis temperature and/or time lead to an increase of the Li/Ni disorder. The amount of extra-nickel ions in the lithium plane strongly affects the magnetic behaviour and the electrochemical performances of the prepared material. LiNi0.65Co0.25Mn0.1O2 prepared at 900 °C for 1 h presents the best cycling properties.
|
|
| 12. |
- Wikberg, J. Magnus, et al.
(författare)
-
Magnetic order, aging, and spin frustration in a percolating spin system, LiNi0.8Co0.1Mn0.1O2
- 2010
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 108:8, s. 083909-
-
Tidskriftsartikel (refereegranskat)abstract
- Structural and magnetic properties of the Li layered oxide, LiNi0.8Co0.1Mn0.1O2, have been studied by means of x-ray diffraction, dc magnetization, ac linear, and nonlinear susceptibility as well as by magnetic aging and temperature cycling experiments. A percolating spin system interacting via antiferromagnetic and ferromagnetic superexchange interactions of different strength induce a ferrimagnetic quasilong-range order with a transition temperature Tc ≈ 70 K, a Weiss temperature of −25 K and an effective magnetic moment of 2.07 μB. On cooling below Tc the two-dimensional (2D) triangular lattice built up of edge-sharing metal oxide octahedras first exhibits a 2D spin glass like behavior followed by complete spin frustration in three dimensions below 30 K. The findings correlate well with expectations for a ferrimagnetic reentrant cluster glass system as well as with predictions of the percolating cluster model.
|
|
| 13. |
- Wikberg, J. Magnus, et al.
(författare)
-
Magnetic order and frustrated dynamics in Li(Ni0.8Co0.1Mn0.1)O-2 : a study by mu+SR and SQUID magnetometry
- 2012
-
Ingår i: 12TH INTERNATIONAL CONFERENCE ON MUON SPIN ROTATION, RELAXATION AND RESONANCE (MUSR2011). - : Elsevier BV. ; , s. 202-205
-
Konferensbidrag (refereegranskat)abstract
- Recently, the mixed transition metal oxides of the form Li(Ni1-y-zCoyMnz)O-2, have become the center of attention as promising candidates for novel battery material. These materials have also revealed very interesting magnetic properties due to the alternate stacking of planes of metal oxides on a 2D triangular lattice and the Li-layers. The title compound, Li(Ni0.8Co0.1Mn0.1)O-2, has been investigated by both magnetometry and measurements and mu+SR. We find the evolution of localized magnetic moments with decreasing temperature below 70 K. The magnetic ground state (T = 2 K) is, however, shown to be a frustrated system in 3D, followed by a transition into a possible 2D spin-glass above 22 K. With further increasing temperature the compound show the presence of remaining correlations with increasing effective dimensionality all the way up to the ferrimagnetic transition at T-C = 70 K.
|
|
