Using X-Ray Diffraction to Map the Electrochemical Spatial Inhomogeneity within Li-Ion Batteries

The complexity of layered-spinel yLi2MnO3·(1 – y)Li1+xMn2–xO4 (Li:Mn = 1.2:1; 0 ≤ x ≤ 0.33; y ≥ 0.45) composites synthesized at different temperatures has been investigated by a combination of x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), and nuclear magnetic resonance (NMR). While the layered component does not change substantially between samples, an evolution of the spinel component from a high to a low lithium excess phase has been traced with temperature by comparing with data for pure Li1+xMn2–xO4. The changes that occur to the structure of the spinel component and to the average oxidation state of the manganese ions within the composite structure as lithium is electrochemically removed in a battery have been monitored using these techniques, in some cases in situ. Our 6Li NMR results constitute the first direct observation of lithium removal from Li2MnO3 and the formation of LiMnO2 upon lithium reinsertion.

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Electrochemical Behavior of LiCo(1-x)MnxO2 Crystalline Powders

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.895.334 ◽

2014 ◽

Vol 895 ◽

pp. 334-337

Author(s):

Azira Azahidi ◽

Norlida Kamarulzaman ◽

Kelimah Elong ◽

Nurhanna Badar ◽

Nurul Atikah Mohd Mokhtar

Keyword(s):

Partial Substitution ◽

Li Ion Batteries ◽

X Ray Diffraction ◽

Capacity Retention ◽

X Ray ◽

Capacity Loss ◽

Transition Metal Element ◽

Metal Element ◽

Li Ion ◽

Mn Doped

LiCoO2 is a well-known cathode material used in commercial Li-ion batteries but it has its own limitations in terms of cost and toxicity. Improvement of the material by partial substitution of Co with other transition metals is one of the alternative and effective ways to overcome the limitations and improve the electrochemical performance of cathode materials. The transition metal element used for the substitution has to be cheaper and non-toxic thus Mn is chosen here. LiCo(1-x)MnxO2 (x= 0.1, 0.2, 0.3) we synthesized by a novel route using a self-propagating combustion (SPC) method. The samples are analyzed using X-Ray Diffraction (XRD) for phase purity and Field Emission Scanning Electron Microscopy (FESEM) for morphology and particle size studies. The materials obtained are phase pure. In terms of electrochemical activity, though it does not show better first cycle discharge capacity, the Mn doped materials have improved capacity retention. Results showed that LiCo0.9Mn0.1O2 and LiCo0.8Mn0.2O2 exhibited less than 8 % capacity loss in the 20th cycle compared to 12 % for LiCoO2.

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Structure and Stability of Olivine Phase FePO4

MRS Proceedings ◽

10.1557/opl.2011.1339 ◽

2011 ◽

Vol 1333 ◽

Cited By ~ 1

Author(s):

Gene M. Nolis ◽

Natalya A. Chernova ◽

Shailesh Upreti ◽

M. Stanley Whittingham

Keyword(s):

Gravimetric Analysis ◽

Li Ion Batteries ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

Absorption Data ◽

X Ray ◽

Residual Amount ◽

Low Toxicity ◽

Li Ion ◽

Trigonal Phase

ABSTRACTLiFePO4 has shown considerable promise as a cathode material in Li-ion batteries due to its stability, low toxicity and high cyclability. However, the data on thermodynamic stability of olivine phase FePO4 (o-FePO4), the delithiated form of o-LiFePO4, remains scarce and contradictory. In this work, o-FePO4 was synthesized by chemical delithiation of o-LiFePO4 and characterized structurally and thermally. X-ray diffraction and absorption data indicate pure olivine phase, but with residual amount of Fe2+, most likely due to incomplete delithiation. Differential scanning calorimetry and thermal gravimetric analysis reveal that o-LixFePO4 decomposes exothermally above 550 °C with about 9% weight loss, the products being trigonal phase FePO4, Fe7(PO4)6, and LiPO3.

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Electrochemical and electron microscopic characterization of Super-P based cathodes for Li–O2 batteries

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.4.74 ◽

2013 ◽

Vol 4 ◽

pp. 665-670 ◽

Cited By ~ 9

Author(s):

Mario Marinaro ◽

Santhana K Eswara Moorthy ◽

Jörg Bernhard ◽

Ludwig Jörissen ◽

Margret Wohlfahrt-Mehrens ◽

...

Keyword(s):

Lithium Salt ◽

Electrochemical Impedance ◽

Ex Situ ◽

Cathode Side ◽

Li Ion Batteries ◽

X Ray Diffraction ◽

Electron Microscopic ◽

X Ray ◽

Li Ion

Aprotic rechargeable Li–O2 batteries are currently receiving considerable interest because they can possibly offer significantly higher energy densities than conventional Li-ion batteries. The electrochemical behavior of Li–O2 batteries containing bis(trifluoromethane)sulfonimide lithium salt (LiTFSI)/tetraglyme electrolyte were investigated by galvanostatic cycling and electrochemical impedance spectroscopy measurements. Ex-situ X-ray diffraction and scanning electron microscopy were used to evaluate the formation/dissolution of Li2O2 particles at the cathode side during the operation of Li–O2 cells.

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Lithium chromium pyrophosphate as an insertion material for Li-ion batteries

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s2052520615017539 ◽

2015 ◽

Vol 71 (6) ◽

pp. 661-667 ◽

Cited By ~ 3

Author(s):

Martin Reichardt ◽

Sébastien Sallard ◽

Petr Novák ◽

Claire Villevieille

Keyword(s):

Sol Gel ◽

Insertion Reaction ◽

Li Ion Batteries ◽

Conductivity Measurements ◽

X Ray Diffraction ◽

Theoretical Limit ◽

X Ray ◽

Electrochemically Active ◽

Carbon Coated ◽

Li Ion

Lithium chromium pyrophosphate (LiCrP2O7) and carbon-coated LiCrP2O7 (LiCrP2O7/C) were synthesized by solid-state and sol–gel routes, respectively. The materials were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and conductivity measurements. LiCrP2O7 powder has a conductivity of ∼ 10−8 S cm−1, ∼ 104 times smaller than LiCrP2O7/C (∼ 10−4 S cm−1). LiCrP2O7/C is electrochemically active, mainly between 1.8 and 2.2 V versus Li+/Li (Cr3+/Cr2+ redox couple), whereas LiCrP2O7 has limited electrochemical activity. LiCrP2O7/C delivers a reversible specific charge up to ∼ 105 mAh g−1 after 100 cycles, close to the theoretical limit of 115 mAh g−1. Operando XRD experiments show slight peak shifts between 2.2 and 4.8 V versus Li+/Li, and a reversible amorphization between 1.8 and 2.2 V versus Li+/Li, suggesting an insertion reaction mechanism.

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