scholarly journals In operando tracking phase transformation evolution of lithium iron phosphate with hard X-ray microscopy

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Jiajun Wang ◽  
Yu-chen Karen Chen-Wiegart ◽  
Jun Wang
Keyword(s):  
Phase Transformation ◽  
Lithium Iron Phosphate ◽  
Iron Phosphate ◽  
X Ray ◽  
In Operando

Insight into microstructural and phase transformations in electrochemical sodiation–desodiation of a bismuth particulate anode

2017 ◽  
Vol 5 (40) ◽  
pp. 21536-21541 ◽  
Author(s):  
Chek-Hai Lim ◽  
Baskar Selvaraj ◽  
Yen-Fang Song ◽  
Chun-Chieh Wang ◽  
Jian-Ting Jin ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
X Ray ◽  
In Operando ◽  
Delayed Phase ◽  
Insight Into

In operando synchrotron X-ray analyses reveal unique delayed phase transformation and particle fracturing processes of a Bi anode for Na-ion batteries.

scholarly journals A mechanism of defect-enhanced phase transformation kinetics in lithium iron phosphate olivine

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Liang Hong ◽  
Kaiqi Yang ◽  
Ming Tang
Keyword(s):  
Phase Transformation ◽  
Surface Reaction ◽  
Lithium Iron Phosphate ◽  
Active Surface ◽  
Iron Phosphate ◽  
Active Surface Area ◽  
General Strategy ◽  
Transformation Rate ◽  
Kinetic Regime ◽  
Antisite Defects

AbstractAntisite defects are a type of point defect ubiquitously present in intercalation compounds for energy storage applications. While they are often considered a deleterious feature, here we elucidate a mechanism of antisite defects enhancing lithium intercalation kinetics in LiFePO4 by accelerating the FePO4 → LiFePO4 phase transformation. Although FeLi antisites block Li movement along the [010] migration channels in LiFePO4, phase-field modeling reveals that their ability to enhance Li diffusion in other directions significantly increases the active surface area for Li intercalation in the surface-reaction-limited kinetic regime, which results in order-of-magnitude improvement in the phase transformation rate compared to defect-free particles. Antisite defects also promote a more uniform reaction flux on (010) surface and prevent the formation of current hotspots under galvanostatic (dis)charging conditions. We analyze the scaling relation between the phase boundary speed, Li diffusivity and particle dimensions and derive the criteria for the co-optimization of defect content and particle geometry. A surprising prediction is that (100)-oriented LiFePO4 plates could potentially deliver better performance than (010)-oriented plates when the Li intercalation process is surface-reaction-limited. Our work suggests tailoring antisite defects as a general strategy to improve the rate performance of phase-changing battery compounds with strong diffusion anisotropy.

Enhancement of Lithium Battery Performance by Thickness Anode Film Modification

2015 ◽  
Vol 827 ◽  
pp. 156-161
Author(s):  
Rani Cahyani Fajaryatun ◽  
Therecia Wulan Sukardi ◽  
Arif Jumari ◽  
Agus Purwanto
Keyword(s):  
Polyvinylidene Fluoride ◽  
Lithium Battery ◽  
Lithium Iron Phosphate ◽  
Iron Phosphate ◽  
Electrochemical Performances ◽  
X Ray Diffraction ◽  
Battery Voltage ◽  
X Ray ◽  
Mesocarbon Microbeads ◽  
Anode Film

A lithium battery was composed of anode, cathode, and separator. The performance of lithium battery was influenced by the thickness of film, the composition of material, and the effect of surfactant and binder. This research investigated the effect of the anode film thickness to the electrochemical performances of lithium battery. Mesocarbon microbeads (MCMB) and lithium iron phosphate (LiFePO4) were used respectively as anode and cathode. Mesocarbon microbeads, carbon black (conductive agent), polyvinylidene fluoride (PVDF) as a binder and N-methyl-2-pyrrolidone (NMP) as a solvent were mixed well to produce slurry. The slurry were then coated, dried and pressed. The anode had various thickness of 50 μm, 70 μm, 100 μm, and 150 μm. The cathode film was made with certain thickness. The performance of lithium battery was examined by Eight Channel Battery Analyzer, the composition of the anode sample was examined by XRD (X-Ray Diffraction), and the crystal structure of the anode sample was analyzed by SEM (Scanning Electron Microscope). The research showed that the thickness of anode film of 100 μm gave the best performance. The battery performance decreased if the thickness was more than 100 μm. The best performance of battery voltage were between 3649 mV and 3650 mV.

Overpotential-Dependent Phase Transformation Pathways in Lithium Iron Phosphate Battery Electrodes

2010 ◽  
Vol 22 (21) ◽  
pp. 5845-5855 ◽  
Author(s):  
Yu-Hua Kao ◽  
Ming Tang ◽  
Nonglak Meethong ◽  
Jianming Bai ◽  
W. Craig Carter ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Lithium Iron Phosphate ◽  
Iron Phosphate ◽  
Transformation Pathways

Comparison between Different LiFePO4 Synthesis Routes

2007 ◽  
Vol 555 ◽  
pp. 225-230 ◽  
Author(s):  
D. Jugović ◽  
N. Cvjetićanin ◽  
M. Mitrić ◽  
S. Mentus
Keyword(s):  
Electron Microscopy ◽  
Lithium Iron Phosphate ◽  
Ultrasonic Spray Pyrolysis ◽  
Iron Phosphate ◽  
X Ray ◽  
Synthesis Conditions ◽  
Microstructural Parameters ◽  
Ultrasonic Spray ◽  
Synthesis Routes ◽  
Scanning Electron

Olivine-type lithium iron phosphate (LiFePO4) powders were synthesized applying three different methods: solid state reaction at high temperature, ultrasonic spray pyrolysis, and sonochemical treatment. The samples were characterized by X-ray powder diffraction (XRPD). Particle morphologies of the obtained powders were determined by scanning electron microscopy (SEM). It was found that structural and microstructural parameters of this material were strongly dependent on the synthesis conditions. We present here the results obtained upon optimization of each procedure for designing this cathode material.

Effect of Niobium Doping on Electrochemical Properties of Microwave Synthesized Carbon Coated Nanolithium Iron Phosphate for High Rate Underwater Applications

2018 ◽  
Vol 16 (2) ◽  
Author(s):  
A. Srinivas Kumar ◽  
T. V. S. L. Satyavani ◽  
M. Senthilkumar ◽  
P. S. V. Subba Rao
Keyword(s):  
Solid Solution ◽  
Lithium Iron Phosphate ◽  
Electrochemical Impedance ◽  
Rate Capability ◽  
Lithium Ion ◽  
Iron Phosphate ◽  
High Rate ◽  
X Ray ◽  
Niobium Doping ◽  
Carbon Coated

Lithium iron phosphate (LiFePO4) for lithium-ion batteries is considered as perfect cathode material for various military applications, especially underwater combat vehicles. For deployment at high rate applications, the low conductivity of LiFePO4 needs to be improved. Cationic substitution of niobium in the native carbon coated LiFePO4 is one of the methods to enhance the conductivity. In the present work, how the niobium doped solid solution could be formed is studied. Nanopowders of LiFePO4/C and Li1−xNbxFePO4/C (x = 0.05, 0.1, 0.15, 0.16) are synthesized from precursors using microwave synthesis. The solid solution formation up to (x = 0.15) Li1−xNbxFePO4/C without impurity phases is confirmed by X-ray diffraction (XRD) pattern and Fourier transform infrared spectroscopic (FTIR) results. Particle distribution is obtained by scanning electron microscope from the synthesized powders. Energy dispersive X-ray spectrometer (EDS) results qualitatively confirmed the presence of niobium. Also, direct current (dc) conductivities are measured using sintered pellets and activation energies are calculated using Arrhenius equation. The dependence of conductivity and activation energy of LiFePO4/C on variation of niobium doping is investigated in this study. CR2032 type coin cells are fabricated with the synthesized materials and subjected to cyclic voltammetry studies, rate capability and cycle life studies. Diffusion coefficients are obtained from electrochemical impedance spectroscopy studies. It is observed that room temperature dc conductivity improved by niobium doping when compared to LiFePO4/C (0.379 × 10−2 S/cm) and is maximum for Li0.9Nb0.1FePO4/C (40.58 × 10−2 S/cm). It is also observed that diffusion coefficient of Li+ in Li0.9Nb0.1FePO4/C (13.306 × 10−9 cm2 s−1) improved by two orders of magnitude in comparison with the pure LiFePO4 (10 − 12 cm2 s−1) and carbon-coated nano LiFePO4/C (0.632 × 10−11 cm2 s−1). Cells with Li0.9Nb0.1FePO4/C are able to deliver useful capacity of around 104 mAh/g at 10 C rate. More than 500 cycles are achieved with Li0.9Nb0.1FePO4/C at 20 C rate.

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