Characterising Lithium-Ion Electrolytes via Operando Raman Microspectroscopy

AbstractKnowledge of electrolyte transport and thermodynamic properties in Li-ion and beyond Li-ion technologies is vital for their continued development and success. Here, we present a method for fully characterising electrolyte systems. By measuring the electrolyte concentration gradient over time via operando Raman microspectroscopy, in tandem with potentiostatic electrochemical impedance spectroscopy, the Fickian “apparent” diffusion coefficient, transference number, thermodynamic factor, ionic conductivity and resistance of charge-transfer were quantified within a single experimental setup. Using lithium bis(fluorosulfonyl)imide (LiFSI) in tetraglyme (G4) as a model system, our study provides a visualisation of the electrolyte concentration gradient; a method for determining key electrolyte properties, and a necessary technique for correlating bulk intermolecular electrolyte structure with the described transport and thermodynamic properties.

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Characterising Lithium-Ion Electrolytes via Operando Raman Microspectroscopy

10.26434/chemrxiv.13359344 ◽

2020 ◽

Author(s):

Jack Fawdon ◽

Johannes Ihli ◽

Fabio La Mantia ◽

Mauro Pasta

Keyword(s):

Thermodynamic Properties ◽

Concentration Gradient ◽

Electrolyte Concentration ◽

Electrochemical Impedance ◽

Lithium Ion ◽

Transference Number ◽

Model System ◽

Raman Microspectroscopy ◽

Apparent Diffusion ◽

Li Ion

<div><div><div><p>Knowledge of electrolyte transport and thermodynamic properties in Li-ion and ”beyond Li-ion” technologies is vital for their continued development and success. Here, we present a method for fully characterising electrolyte systems. By measuring the electrolyte concentration gradient over time via operando Raman microspectroscopy, in tandem with potentiostatic electrochemical impedance spectroscopy, the Fickian ”apparent” diffusion coefficient, transference number, thermodynamic factor, ionic conductivity and resistance of charge-transfer were quantified within a single experimental setup. Using lithium bis(fluorosulfonyl)imide (LiFSI) in tetraglyme (G4) as a model system, our study provides a visualisation of the electrolyte concentration gradient; a method for determining key electrolyte properties, and a necessary technique for correlating intermolecular electrolyte structure with the described transport and thermodynamic properties.</p></div></div></div>

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Synthesis and Electrochemical Properties of Spherical LiFePO4/C Composite via Spray Drying

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1120-1121.554 ◽

2015 ◽

Vol 1120-1121 ◽

pp. 554-558 ◽

Cited By ~ 1

Author(s):

Juan Mei Wang ◽

Bing Ren ◽

Ying Lin Yan ◽

Qing Zhang ◽

Yan Wang

Keyword(s):

Diffusion Coefficient ◽

Electrochemical Properties ◽

Spray Drying ◽

Electrochemical Impedance ◽

Retention Rate ◽

Lithium Ion ◽

Constant Current ◽

Ion Diffusion ◽

Electrochemical Tests ◽

Li Ion

In this work, spherical LiFePO4/C composite had been synthesized by co-precipitation and spray drying method. The structure, morphology and electrochemical properties of the samples were characterized by X-ray diffraction (XRD), scanning electron micrograph (SEM), transmission electron microscope (TEM), constant current charge-discharge tests and electrochemical impedance spectroscopy (EIS) tests. The spherical LiFePO4/C particles consisted of a number of smaller grains. The results showed that the morphology of LiFePO4/C particles seriously affected the Li-ion diffusion coefficient and electrochemical properties of lithium ion batteries. Electrochemical tests revealed the spherical LiFePO4/C composite had excellent Li-ion diffusion coefficient which was calculated to be 1.065×10-11 cm2/s and discharge capacity of 149 (0.1 C), 139 (0.2 C), 133 (0.5 C), 129 (1 C) and 124 mAhg-1(2 C). After 50 cycles, the capacity retention rate was still 93.5%.

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Broadband Impedance Measurement of Lithium-Ion Battery in the Presence of Nonlinear Distortions

Energies ◽

10.3390/en13102493 ◽

2020 ◽

Vol 13 (10) ◽

pp. 2493

Author(s):

Jussi Sihvo ◽

Tomi Roinila ◽

Daniel-Ioan Stroe

Keyword(s):

Electrochemical Impedance ◽

Equivalent Circuit Model ◽

Impedance Measurement ◽

Lithium Ion ◽

Li Ion Battery ◽

Third Order ◽

Impedance Measurements ◽

Nonlinear Distortions ◽

Measured Impedance ◽

Li Ion

The impedance of a Lithium-ion (Li-ion) battery has been shown to be a valuable tool in evaluating the battery characteristics such as the state-of-charge (SOC) and state-of-health (SOH). Recent studies have shown impedance-measurement methods based on broadband pseudo-random sequences (PRS) and Fourier techniques. The methods can be efficiently applied in real-time applications where the conventional electrochemical-impedance spectroscopy (EIS) is not well suited to measure the impedance. The techniques based on the PRS are, however, strongly affected by the battery nonlinearities. This paper presents the use of a direct-synthesis ternary (DST) signal to minimize the effect caused by the nonlinearities. In such a signal, the second- and third-order harmonics are suppressed from the signal energy spectrum. As a result, the effect of the second- and third-order nonlinearities are suppressed from the impedance measurements. The impedance measurements are carried out for a nickel manganese cobalt Li-ion battery cell. The performance of the method is compared to the conventional EIS, as well as to other PRS signals which are more prone to battery nonlinearities. The Kronig–Kramers (K–K) transformation test is used to validate the uniqueness of the measured impedance spectra. It is shown that the measurement method based on the DST produces highly accurate impedance measurements under nonlinear distortions of the battery. The method shows a good K–K test behavior indicating that the measured impedance complies well to a linearized equivalent circuit model that can be used for the SOC and SOH estimation of the battery. Due to the good performance, low measurement time, and simplicity of the DST, the method is well suited for practical battery applications.

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Experimental study on influence of temperature and C-rate of discharge on performance of in-house fabricated 30Ah Li-ion prismatic cell made with LFP and MCMB

Journal of Electrochemical Energy Conversion and Storage ◽

10.1115/1.4050938 ◽

2021 ◽

pp. 1-20

Author(s):

T. V. S. L. Satyavani ◽

Mathiyazhagan Senthilkumar ◽

G. Dharma Prasad Rao ◽

Navneet Kumar ◽

Adapaka Srinivas Kumar

Keyword(s):

Experimental Study ◽

Lithium Iron Phosphate ◽

Electrochemical Impedance ◽

Temperature Drop ◽

Lithium Ion ◽

High Rate ◽

Transfer Resistance ◽

Influence Of Temperature ◽

Different Temperatures ◽

Li Ion

Abstract Experimental study was carried out to quantify the influence of temperature and different C-rate of discharge on in-house fabricated Lithium-ion (Li-ion) cell. 30Ah Li-ion cell is made of Lithium Iron Phosphate (LFP) cathode and Meso Carbon Micro Beads (MCMB) anode in prismatic configuration. Capability of Li-ion cell is defined by discharge capacity, voltage & power at different C-rate of discharge. Influence of 4 different current rates (C/5, C/2, 1C & 2C) at 5 different temperatures (−20, 0, 20, 40 and 60 °C) were studied. High discharge rate increases current density of cell which affect mass transport at electrode surface and electrolyte. Increased ohmic and concentration polarization at high rate of discharge decrease the original capacity. Average discharge voltage of cell is reduced gradually as operating temperature drop to below 20 °C. Electrochemical Impedance (EI) were measured on Li-ion cell in different frequency domain at different temperatures (−20, 0, 20 and 60 °C). The obtained impedance spectra were examined with an equivalent circuit using Zman software. The ohmic and charge transfer resistance displayed a solid dependence with respect to temperature.

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Insights into Ionic Liquid Electrolyte Transport and Structure via Operando Raman Microspectroscopy

10.33774/chemrxiv-2021-578hl ◽

2021 ◽

Author(s):

Jack Fawdon ◽

Gregory Rees ◽

Fabio La Mantia ◽

Mauro Pasta

Keyword(s):

Ionic Liquid ◽

Rate Capability ◽

Transference Number ◽

High Viscosity ◽

Liquid Electrolyte ◽

Raman Microspectroscopy ◽

Concentration Gradients ◽

Ionic Liquid Electrolyte ◽

Apparent Diffusion ◽

First Time

Ionic liquid electrolytes (ILEs) have become popular in various advanced Li-ion battery chemistries because of their high electrochemical and thermal stability, and low volatility. However, due to their relatively high viscosity and poor Li+ diffusion, it is thought large concentration gradients form, reducing their rate capability. Here, we utilised operando Raman microspectroscopy to visualise ILE concentration gradients for the first time. Specifically, using lithium bis(fluorosulfonyl)imide (LiFSI) in N-propyl- N-methylpyrrolidinium FSI, its "apparent" diffusion coefficient, lithium transference number, thermodynamic factor, ionic conductivity and resistance of charge-transfer against lithium metal, were isolated. Furthermore, the analysis of these concentration gradients led to insights into the bulk structure of ILEs, which we propose is composed of large, ordered aggregates.

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Experimental and theoretical investigation of lithium-ion conductivity in Li2LaNbTiO7

Dalton Transactions ◽

10.1039/c9dt03547h ◽

2019 ◽

Vol 48 (46) ◽

pp. 17281-17290 ◽

Cited By ~ 1

Author(s):

Selorm Joy Fanah ◽

Ming Yu ◽

Farshid Ramezanipour

Keyword(s):

Density Functional Theory ◽

Electrochemical Impedance Spectroscopy ◽

Impedance Spectroscopy ◽

Density Functional ◽

Electrochemical Impedance ◽

Lithium Ion ◽

Ion Conductivity ◽

Functional Theory ◽

Li Ion ◽

Lithium Ion Conductivity

Li-ion conductivity in Li2LaNbTiO7 and its Li-deficient analogue has been investigated. Neutron diffraction, electrochemical impedance spectroscopy, and density functional theory have been utilized to study these Ruddlesden-Popper oxides.

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Thermal Issues in Lithium-Ion Batteries

Materials, Nondestructive Evaluation, and Pressure Vessels and Piping ◽

10.1115/imece2006-15106 ◽

2006 ◽

Cited By ~ 1

Author(s):

S. R. Alavi-Soltani ◽

T. S. Ravigururajan ◽

Mary Rezac

Keyword(s):

Lithium Ion Batteries ◽

Thermal Management ◽

Review Paper ◽

Electrochemical Impedance ◽

Lithium Ion ◽

Chemical Characteristics ◽

Li Ion Batteries ◽

Thermal Management System ◽

System Method ◽

Li Ion

This paper reviews various studies carried out on thermal issues in lithium-ion batteries. Although thermal behavior of Li-ion batteries plays an important role in performance, life cycle and safety of these batteries, it has not been studied as intensely as chemical characteristics of these batteries. In this review paper, studies concerning thermal issues on Li-ion batteries are classified based on their methodologies and the battery components being investigated. The methodologies include mathematical thermal modeling, calorimetry, electrochemical impedance spectroscopy and thermal management system method. The battery components that have been studied include anode, cathode, electrolyte and the whole cell.

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Preferential lattice expansion of polypropylene in a trilayer polypropylene/polyethylene/polypropylene microporous separator in Li-ion batteries

Scientific Reports ◽

10.1038/s41598-021-81644-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Wen-Dung Hsu ◽

Po-Wei Yang ◽

Hung-Yuan Chen ◽

Po-Hsien Wu ◽

Pin-Chin Wu ◽

...

Keyword(s):

Current Density ◽

Density Functional ◽

Electrochemical Impedance ◽

Lithium Ion ◽

Density Functional Theory Calculations ◽

Lattice Expansion ◽

X Ray Diffraction ◽

Charging Current ◽

Separator Material ◽

Li Ion

AbstractThe abnormal lattice expansion of commercial polypropylene (PP)/polyethylene (PE)/polypropylene (PP) separator in lithium-ion battery under different charging current densities was observed by in-situ X-ray diffraction. Significant lattice changes of both PP and PE were found during the low current density charging. The capacity fading and the resistance value of the cell measured at 0.025 C (5th retention, 92%) is unexpectedly larger than that at 1.0 C (5th retention, 97.3%) from the electrochemical impedance spectroscopic data. High-resolution scanning electron microscopy is employed to witness the pore changes of the trilayered membrane. Density functional theory calculations were used to investigate the mechanism responsible for the irregular results. The calculations revealed that the insertion of Li-ion and EC molecule into PP or PE are thermodynamically favourable process which might explain the anomalous significant lattice expansion during the low current density charging. Therefore, designing a new separator material with a more compact crystalline structure or surface modification to reduce the Li insertion during the battery operation is desirable.

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Ni-Rich Layered Oxide with Preferred Orientation (110) Plane as a Stable Cathode Material for High-Energy Lithium-Ion Batteries

Nanomaterials ◽

10.3390/nano10122495 ◽

2020 ◽

Vol 10 (12) ◽

pp. 2495

Author(s):

Fangkun Li ◽

Zhengbo Liu ◽

Jiadong Shen ◽

Xijun Xu ◽

Liyan Zeng ◽

...

Keyword(s):

Transition Metal Oxides ◽

Electrochemical Impedance ◽

Voltage Drop ◽

Lithium Ion ◽

High Energy ◽

Preferred Orientation ◽

Voltage Drops ◽

Diffusion Dynamics ◽

Li Ion ◽

Co Precipitation

The cathode, a crucial constituent part of Li-ion batteries, determines the output voltage and integral energy density of batteries to a great extent. Among them, Ni-rich LiNixCoyMnzO2 (x + y + z = 1, x ≥ 0.6) layered transition metal oxides possess a higher capacity and lower cost as compared to LiCoO2, which have stimulated widespread interests. However, the wide application of Ni-rich cathodes is seriously hampered by their poor diffusion dynamics and severe voltage drops. To moderate these problems, a nanobrick Ni-rich layered LiNi0.6Co0.2Mn0.2O2 cathode with a preferred orientation (110) facet was designed and successfully synthesized via a modified co-precipitation route. The galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) analysis of LiNi0.6Co0.2Mn0.2O2 reveal its superior kinetic performance endowing outstanding rate performance and long-term cycle stability, especially the voltage drop being as small as 67.7 mV at a current density of 0.5 C for 200 cycles. Due to its unique architecture, dramatically shortened ion/electron diffusion distance, and more unimpeded Li-ion transmission pathways, the current nanostructured LiNi0.6Co0.2Mn0.2O2 cathode enhances the Li-ion diffusion dynamics and suppresses the voltage drop, thus resulting in superior electrochemical performance.

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