Index
(full-text links to be added soon)
G.S.Popkirov, E. Barsoukov, "In situ impedance measurements
during oxidation and reduction of conducting polymers:
significance of capacitive currents",
J. Electroanal. Chem. 383 (1995) 155
Abstract:
An attempt has been made to model mathematically the
capacitive component of the current obtained in cyclic voltammograms of
polymer-coated electrodes. The capacitance data used were obtained by means
of electrochemical impedance spectroscopy (EIS) measurements performed
in situ during the potential sweeps. It was shown that the capacitive current
flowing during the oxidation and reduction processes strongly depends on
both the low frequency capacitance of the polymer and its changes during
the sweep.
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G.S. Popkirov, E. Barsoukov and R.N. Schindler "Electrochemical
impedance spectroscopy of twin working electrodes bridged
with
conducting polymer layer", Electrochim. Acta 40 (1995)
1857
Abstract:
A new technique is described for electrochemical impedance
spectroscopic (EIS) investigations in the plane of a polymer layer coating
an electrode without crossing the interface polymer-electrolyte. For this
purpose a twin-working electrode configuration was constructed, that consists
of two practically identical electrodes with a gap of a few micrometers
width between them. This gap was bridged by a polymer layer of polybithiophene.
Its behavior was studied during electrochemical deposition on the twin
electrode and during transition from insulating to conducting state upon
oxidation. It is shown that for lower frequencies the impedance spectra
obtained depend predominantly on the polymer conductivity and are not determined
by the macroscopic external polymer/electrolyte interface. Contribution
of capacitive ac currents that cross microscopic internal polymer-electrolyte
interfaces in the deep pores of the polymer become considerable only in
the higher frequency range.
_____________________________________________________________________________________
G.S. Popkirov, E. Barsoukov and R.N. Schindler
"Investigation of conducting polymer electrodes
by impedance spectroscopy under galvanostatic conditions"
J. Electroanal. Chem., 425 (1997) 209-216
Abstract:
Electrochemical impedance spectroscopy was used to investigate
the electrochemical polymerization of bithiophene under galvanostatic conditions.
The impedance spectra obtained on layers with different thicknesses were
analyzed by a fitting procedure, based on theoretical models known from
the literature. It was shown that the model of Ho at al. (C. Ho, I.D. Raistrick
and R.A. Huggings, J.Electrochem. Soc., 127 (1950) 343) can be applied
successfully in studying the impedance spectra of relatively thin polybithiophene
layers, deposited at low current density. The model of Paash at al. (G.
Paasche, K. Micka and P. Gersodorf, Electrochim. Acta, 38 (1993) 2653)
in a simplified form is better suited to describe the spectra of thicker,
supposedly porous polymer layers, obtained at higher current density. It
was suggested that the deposition of polymer film onto a metal electrode
follows a 3D growth mechanism during the first stages of polymerization,
and pseudo-2D growth form polymerization at charges higher than 15 to 20
mC/cm-2. Important parameters of the polymer film, such as the apparent
diffusion coefficient, apparent diffusion length, ionic and polymer layer
thickness were estimated.
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Jong Hyun Kim, Jong Hun Kim, Evgenij Barsoukov, Chul Oh
Yoon, and Hosull Lee
“Li NMR Study of Li Intercalated Carbons Prepared by
Electrochemical Method”, Mol.Chyst.Liq.Cryst. 310 (1998) 297
Abstract:
Li solid-state nuclear magnetic resonance (NMR) is employed
to investigate the mechanism of electrochemical lithium-intercalation in
various carbon materials. Multiple resonance line shapes observed in fully
lithiated carbons indicate that several intercalant sites exist under distinct
spin-interaction environment, and they are substantially dependent upon
physical nature of host structure. The temperature dependence of resonance
spectra in disordered carbons prepared at relatively low carbonization
temperature considerably differs from that observed in lithiated carbons
with graphite structure.
_____________________________________________________________________________________
Evgenij Barsoukov, Jong Hyun Kim, Jong Hun Kim, Chul Oh
Yoon, and Hosull Lee
“Effect of Low-Temperature Conditions on Passive Layer
Growth on Li Intercalation Materials: In sity Impedance Study”, J.Electrochem.Soc.
145/8 (1998) 2711.
Abstract:
Electrochemical impedance spectroscopy has been applied
to investigate the formation of insulating layers at the surfaces of microscopic
particles of mesocarbon microbeads (MCMB), graphite and hard carbon during
the first Li-intercalation into these materials at ambient temperature
as well as at -20 oC. Investigations were carried out in a 3-electrode
sandwich cell, designed for impedance measurements in the frequency range
64kHz-5mHz. The impedance spectra, obtained in the potential range 1.5
and 0.02 V during the first charge, were analyzed by complex non-linear
least square fits. A new model, taking into account the porous structure
of the intercalation material, electrochemical processes at the interface,
as well as spherical diffusion of Li ions toward the centers of the particles,
has been used for this analysis. First intercalation at -20oC results in
formation of an insulating layer, which is about 90 times thinner than
in the room temperature case, as concluded from the analysis of experimental
results. The irreversible capacity loss, which is 1.3 times larger at -20
oC than at room temperature, is ascribed to the formation of a porous precipitate
of electrolyte decomposition products on the particle surface. Additional
reduction at room temperature results in irreversible capacity loss of
26% from the initial value, and formation of a composite layer, including
low-temperature and room-temperature deposited components.
_____________________________________________________________________________________
Evgenij Barsoukov, Jong Hyun Kim, Chul Oh Yoon, and Hosull
Lee
“Kinetics of lithium intercalation into carbon anodes:
in sity impedance investigation of thickness and potential dependence”,
Solid State Ionics, 116 (1999) 249.
Abstract:
Electrochemical impedance spectroscopy (EIS) in 3-electrode
sandwich configuration was applied to investigate the kinetics of Li intercalation
into mesocarbon-microbeads (MCMB) based anodes. A new frequency domain
model, considering porous macroscopic structure of the active material
and spherical diffusion inside the particles, has been applied to analyze
the potential and thickness dependence of impedance spectra. Values of
several kinetics-relevant parameters like specific conductivity of the
layer of intercalation material (2.6 10-4 S cm-1), chemical diffusion coefficient
of Li-ions in MCMB (2.2 10-9 cm2 sec), charge transfer resistance (184
? cm2), are obtained from the analysis. Applicability of proposed model
to prediction of time-domain charge curves has been tested using numerical
inversion of Laplace transformation (NILT). The time domain modeling lead
to conclusion, that phase nucleation at the boundaries between Li-rich
and Li-poor phases coexistent during intercalation is the rate-limiting
step at initial stage of the impulse-discharge.
_____________________________________________________________________________________
Chul Oh Yoon, Hyun Kyung Sung, Jong Hun Kim, Evgenij Barsoukov, Jong Hyun Kim, Hosull Lee, “The effect of low-temperature conditions on the electrochemical polymerization of polypyrrole films with high density, high electrical conductivity and high stability”, Synthetic metals, 99 (1999) 201.
Abstract:
High-quality polypyrrole-hexafluorophosphate (PPy-PF6)
films with high density (~1.4 g/cm3), high conductivity (>300 S/cm for
unstretched film) and high electrochemical stability are obtained reproducibly
by galvanostatic polymerization at low-temperature conditions. The optimal
polymerization current density of Jp=0.02-0.05 mA/cm2 was obtained at the
polymerization temperature of Tp=-40oC. The surface morphology of the film
sensitively varies depending upon the properties of electrode and its surface
conditions. The transport measurements characterize the high-density PPy-PF6
film as a disordered metal close to the boundary of disorder induced metal-insulator
(M-I) transition. The X-ray diffraction measurements suggest that partially
crystalline structure of PPy-PF6 film is related to the transport properties.
The uniaxial stretching induces an increase of the conductivity up to ~930
S/cm in a direction parallel to stretching as well as the anisotropy of
conductivity. The comparative studies of thermogravimetric analysis (TGA),
cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS)
for PPy-PF6 films prepared at room-temperature and low-temperature conditions
show that the latter exhibit better thermal stability as well as electrochemical
stability under long oxidative polarization.
_____________________________________________________________________________________
Evgenij Barsoukov, Jong Hyun Kim, Chul Oh Yoon, and Hosull Lee, “Universal battery parameterization to yield a non-linear equivalent circuit valid for battery simulation at arbitrary load”, J.Power Sources, 83 1/2 (1999) 61
Abstract:
A method of numerical representation for electrical storage
cells based on measurement of wide frequency range impedance spectra at
a number of different states of charge and measurement of the depth-of-discharge
dependence of equilibrium voltage are developed. Applicability of this
method to batteries with various chemistries and sizes are established
by comparing numerical prediction to experiment. The model represents all
tested batteries with accuracy (less than 1% in average deviation) in processes
ranging from time constants of 1 ms to 10 h and from current densities
of C/10 to 3C. The method includes the fitting of impedance spectra to
physically relevant static linear transmission-line model and the use of
parameters determined at different discharge levels to create a non-linear
dynamic model. Formalization of the model as a non-linear equivalent circuit
enables its direct application as a part of any electric device in digital
circuit simulators like SPICE.
_____________________________________________________________________________________
Evgenij Barsoukov, Jong Hyun Kim, Dong Hwan Kim, Chul Oh Yoon, and Hosull Lee, “Parametric analysis using impedance spectroscopy: relationship between material properties and battery performance”, Journal of New Materials for Electrochemical Systems, 3, (2000) 303-310.
Abstract:
The possibility of prediction of battery material performance
based on parameterization of impedance spectra measured at different states
of charge in boundaries of non-linear equivalent circuit model (numerical
image) is demonstrated. An impedance parameterization procedure developed
in this laboratory was used to obtain all kinetically relevant parameters
of LiCoO2 based composite Li-ion battery cathode materials. The accuracy
of performance prediction was tested by comparing voltage profiles, calculated
on basis of numerical image, at discharge rates ranging from 1/10C to 3C
with experimental data. Model parameters were used to compare the relative
influence from different kinetic steps on discharge behavior of composite
electrode. Predicted thickness dependence of electrode impedance was compared
with experimental impedance spectra measured on samples with active material
thickness from 20 to 60 ?m. The change of relative contributions of kinetic
parameters with thickness has been investigated.
_____________________________________________________________________________________
Evgenij Barsoukov, Jee Hwan Jang, and Hosull Lee
"Measurement of Li-ion batteries thermal impedance spectrum
using heat-pulse response analysis", J. Power Sources, 109 (2002) 313
Abstract:
A novel characterization of thermal properties of battery
has been introduced by defining its frequency-dependent thermal impedance
function. Thermal impedance function can be approximated as a thermal impedance
spectrum by analyzing experimental temperature transient which is related
to the thermal impedance function through Laplace transformation.
In order to obtain temperature transient, a process has
been devised to generate external heat pulse with heating wire and to measure
the response of battery. This process is used to study several commercial
Li-ion batteries of cylindrical type. The thermal impedance measurements
have been performed using potentionstat/galvanostate controlled digital
signal processor, which is more commonly available than flow-meter usually
applied for thermal property measurements.
Thermal impedance spectra obtained for the batteries
produced by different manufactures are found to differ considerably. Comparison
of spectra at different states of charge indicates independence of thermal
impedance on charging state of battery. It is shown that thermal
impedance spectrum can be used to obtain simultaneously thermal capacity
and thermal conductivity of battery by non-linear complex least-square
fit of the spectrum to thermal-impedance model.
_____________________________________________________________________________________
Evgenij Barsoukov, Jee Hwan Jang, and Hosull Lee
"Eectrochemical impedance spectrometer based on carrier
function Laplace-transform", J. Electroanal. Chemistry, 536/1, (2002),
109
Abstract:
A novel impedance spectrometer has been developed to
obtain good quality spectrum for electrochemical cell or device in the
minimum time required by Nyquist theorem for the lowest frequency in spectrum.
The new method based on a simple instrumental design resolves the known
problems of existing methods such as long measurement time and fairly complicated
design of frequency response analyzer (FRA), as well as poor quality of
obtained spectrum for pulse-response analysis based systems.
The spectrometer applies a simple excitation such as
current pulse, instantly connected resistance, or current interrupt, followed
by measurement of response such as voltage or current against time. The
response is fitted to an analytical function (carrier function), and the
values of parameters obtained in the fit are applied to the expression
of analytical Laplace transformation of this function. The carrier function
is selected so that it approximates well the transient response of most
electrochemical systems. An analytical expression of impedance function
is obtained by dividing the Laplace transform of the carrier function by
the the Laplace transform of excitation signal. The frequency dependent
impedance spectrum is obtained by evaluating this analytical expression
at required frequencies.
_____________________________________________________________________________________
E. Barsoukov?, D.H. Kim, H.S. Lee and H. Lee (1); Marina
Yakovleva, Yuan Gao and John F. Engel (2),
“Comparison of kinetic properties of LiCoO2 and LiTi0.05Mg0.05Ni0.7Co0.2O2
by impedance spectroscopy”, Solid State Ionics, submitted (2002)
(1) Kumho Chemical Laboratories, Korea Kumho Petrochemical
Company
57-1 Hwaam Yuseong, Daejeon 305-348, Rep. of Korea
(2) FMC Corporation
Abstract
New material based on LiNiO2 with some nickel atoms substituted
for other metals has become increasingly popular as cathode materials for
Li-ion battery due to higher capacity of LiNiO2 compared to traditionally
used LiCoO2 and improved material stability and safety due to substitutes.
However, rate capability of new materials was not extensively researched.
Purpose of this investigation was to characterize by impedance spectroscopy
all major kinetic steps of Li-intercalation into conventional LiCoO2 and
substitution stabilized material LiTi0.05Mg0.05Ni0.7Co0.2O2 samples, provided
by FMC Corporation. Very wide frequency range of impedance measurements
(to 200 ?Hz) with acceptable duration was made possible by using Kumho
Chemical Laboratories one-shot FFT-impedance spectrometer. Availability
of such low frequency data allowed confident estimation of diffusion and
phase-change kinetic parameters. Results were analyzed in terms of transmission-line
model considering composite structure of electrode. Effects of particle
size and mechanism of samples degradation with cycling were also investigated.
_____________________________________________________________________________________
"Method and apparatus for measuring battery capacity by
impedance spectrum measurement" Kumho Petrochemical, by C.O.Yoon, E.Barsoukov,
J.H.Kim, Korean Patent No. 264515 (00/6/1), Japan Patent No. 3162346
(01/3/23), US Patent No. 6208147 (01/3/27)
United States Patent 6,208,147
Yoon , et al. March 27, 2001
Method of and apparatus for measuring battery capacity
by impedance spectrum analysis
Abstract
Provided with a method of measuring battery capacity
by impedance spectrum analysis, which is to measure a characteristic impedance
spectrum of primary and secondary batteries and determine the battery capacity
the method including the steps of: (1) measuring the characteristic impedance
spectrum of a battery in a predetermined frequency region; (2) determining
a parameter from the measured impedance spectrum; (3) monitoring in advance
the correlation between the determined parameter and the battery capacity
measured by a real-time discharge technique; and (4) determining the battery
capacity from the characteristic impedance spectrum of a battery having
an unknown capacity based on the monitored correlation.
____________________________________________________________________________________________________________________________________
Inventors: Yoon; Chul Oh (Taejeon, KR); Barsukov;
Yevgen (Taejeon, KR); Kim; Jong Hyun (Seoul, KR)
Assignee: Korea Kumho Petrochenical Co., Ltd. (Chongno-ku)
Appl. No.: 260438
Filed: March 2, 1999
"Method of and apparatus for measuring battery capacity using voltage response signal based on pulse current", Kumho Petrochemical, by C.O.Yoon, E.Barsoukov, J.H.Kim, Korean Patent No. 262465 (00/5/2), Japan Patent No. 19234A2 (00/1/21), US Patent No. 6118275 (00/9/12), PCT Application No. 66340A1 (99/12/23, 7 countries including EU, Canada, Israel and Taiwan)
United States Patent 6,118,275
Yoon , et al. September 12, 2000
Method and apparatus for measuring battery capacity using
voltage response signal based on pulse current
Abstract
A method of measuring battery capacity using a voltage
response signal based on a pulse current, where the method includes the
steps of: measuring a voltage response signal based on a pulse current
signal applied to a primary or secondary battery; performing an approximation
of the measured voltage response signal to an equivalent circuit model
composed of resistors, capacitors and transmission lines to determine the
model parameters; and determining the unknown battery capacity from the
voltage response characteristics based on a correlation between the measured
capacity and the model parameters, which correlation is previously determined
by a real-time discharge method, thereby takes a shorter time than a real-time
discharge method and delivering efficiency and reliability in determining
model parameters of an equivalent circuit which are in close correlation
with the charge/discharge condition of the battery.
____________________________________________________________________________________________________________________________________
Inventors: Yoon; Chul Oh (Taejeon, KR); Barsukov;
Yevgen (Taejeon, KR); Kim; Jong Hyun (Seoul, KR)
Assignee: Korea Kumho Petrochemical Co., Ltd. (Seoul,
KR)
Appl. No.: 216181
Filed: December 18, 1998
"Battery parameterization system" Kumho Petrochemical,
by C.O.Yoon, E.Barsoukov, J.H.Kim, Korean Patent Application No. 98-49700
(98/11/19), Japan Patent No. 3190313 (01/5/18),US Patent No. 6160382 (00/12/12),
PCT Application No. 31557A1 (00/6/2, 16 countries including EU, Canada,
Israel and Taiwan)
United States Patent 6,160,382
Yoon , et al. December 12, 2000
Method and apparatus for determining Characteristic parameters
of a charge storage device
Abstract
A method and an apparatus for determining characteristic
parameters of a charge storage device based on a wide frequency range of
impedance measurement and a non-linear equivalent circuit model by which
the parameters of the non-linear equivalent circuit model indicative of
the characteristics of various charge storage devices such as a primary
battery, secondary battery, capacitor, supercapacitor and fuel cell are
determined, the method comprising the steps of: (1) measuring voltage and
current characteristics in a process of charging/discharging of the charge
storage device by applying a voltage/current at a predetermined discharge
rate; (2) measuring impedance spectra at a predetermined range of frequency
by measuring the current and voltage from both terminals of the charge
storage device or from an electrical load directly connected to the charge
storage device at a plurality of states of charge within the entire charge/discharge
interval; and (3) obtaining the parameters of the non-linear equivalent
circuit of the charge storage device from the charge or discharge characteristics
measured in step (1) and the characteristic impedance spectrum in the predetermined
range of frequency measured in step (2).
____________________________________________________________________________________________________________________________________
Inventors: Yoon; Chul Oh (Taejeon, KR); Barsukov;
Yevgen (Taejeon, KR); Kim; Jong Hyun (Seoul, KR)
Assignee: Korea Kumbho Petrochemical Co., Ltd.
(Seoul, KR)
Appl. No.: 358264
Filed: July 21, 1999
"Laplace transform impedance spectrometer" Kumho Petrochemical, by C.O.Yoon, E.Barsoukov, J.H.Kim, Korean Patent Application No. 8460 (99/3/13), Japan Patent No. 3069346 (00/5/19), US Patent Application No. 746452 (99/12/30), PCT Application (15 countries including EU, Canada, Israel and Taiwan) in process
Abstract
This disclosure describes a method of measuring impedance based on carrier function Laplace transform. The measurement includes detecting a response signal from a device under test to which signal excitation such as pulse, interrupt or constant load is applied. Resulting data is fitted to a carrier function, selected so as to be capable to provide a good fit and for which an analytical Laplace transform is known, in order to obtain parameters of such function providing best fit. Obtained parameters are further substituted into analytical expression of Laplace transform of carrier function which is used to calculate a frequency dependent impedance function in the Laplace domain. The resulting impedance function is used for calculating the impedance spectrum in a frequency domain and for calculating the measurement error of the frequency domain impedance spectrum using the standard deviations of the parameters, obtained during fitting of time-domain data.
____________________________________________________________________________________________________________________________________
"Method to obtain performance characteristics of electrochemical power source by multidimensional correlation of parameters obtained by measurement", Kumho Petrochemical, by H.K.Sung, E.Barsoukov, J.H.Jang, Korean Patent Application in process, US Patent Application in process
Abstract
A method of obtaining performance characteristic such
as but not restricted to state of charge, state of health, manufacturing
quality (grade), cycling life etc. of electrochemical power sources such
as primary battery, secondary battery or fuel-cell by multidimensional
(also known as multi-variant) correlation between the desired performance
characteristic and 2 or more parameters obtained from test measurements
performed on the multiple entities of power source having different values
of the performance characteristic to be obtained. Test measurement which
results are used to obtain parameters employed by this method has to be
of shorter time duration or less destructive then the direct measurement
of desired performance characteristic, such as but not restricted to impedance
measurement.
Method includes: (a) performing test measurements
on multiple power sources of same design but with different values of desired
performance characteristic; (b) performing direct measurement of the desired
performance characteristic on all electrochemical power sources for which
test a) was performed; (c) obtaining 2 or more parameters p1,p2...pN for
each of tested power sources by analysis of the results of test measurement
performed in a); (d) performing multi-dimensional correlation between the
desired performance characteristic and parameters obtained in c) using
suitable means such as but not restricted to localized multi-variant
regression to obtain set of regression parameters k1,k2...kN which define
multidimensional functional or algorithmic dependence in form V=f(p1,p2...pN,
k1,k2...kN) where V is the desired performance characteristic and p1,p2...pN
are parameters obtained in c); (e) Performing same test measurement as
in (a) on power source with unknown performance charachteristic; (g) obtaining
from test measurement results set of 2 or more parameters u1,u2...uN using
same method as in c); (h) substituting the obtained in (g) parameters u1,u2...uN
into multidimensional functional or algorithmic dependence obtained in
(d) and calculating the desired performance characteristic V1=f(u1,u2...uN,k1,k2...kN);
____________________________________________________________________________________________________________________________________
"Method for grouping quality of batteries to build optimal packs using pattern matching technology of impedance spectrum", Kumho Petrochemical, by H.K.Sung, E.Barsoukov, J.H.Jang, Korean Patent Application in process, US Patent Application in process
Abstract
Method to assign single cells of power sources to several
groups in order to improve performance of cell-packs made of cells residing
in one group as compared to packs made of randomly selected batteries using
parameters obtained by equivalent circuit analysis of impedance spectrum
as criterion of grouping. .
Method includes: (a) Performing impedance spectra
measurement measurements on statistically representative number of power
sources of same design but with different values of performance. Impedance
spectra are measured at several frequencies in frequency range sufficient
to obtain parameters of chosen equivalent circuit used for analyzing the
spectrum.; (b) finding resistive and capacitate parameters of an equivalent
circuit by fitting the measured impedance spectra to known impedance function
of the equivalent circuit. Equivalent circuit is chosen so that it allows
best possible extrapolation of experimental data to 0 frequency; (c) Using
one or several of obtained parameters to calculate approximation of the
total resistance (real part of impedance at zero frequency, or DC resistance).
(d) Assigning all batteries intended for making battery packs to several
groups distinguished by similarity of the value of total resistance
obtained in step d. Selection of group ranges is optimized based on known
distribution of the total resistance value of the cells.