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Homogeneity of lithium analysis in lithium-ion batteries - A study on half-cells, full-cells and parallel connected cells of the Tesla Model S 85

Authors:

Abstract

In this work, the inhomogeneous distribution of lithium on the electrodes of lithium-ion batteries is assessed by analyzing the voltage response in half-cells, full-cells, and parallel connected cells. A set of experiments has been conducted ranging from differential voltage analysis to voltage relaxation measurements and electrochemical impedance spectroscopy. This submission summarizes the former stated experiments, derives and explains the theory of homogeneity of lithium distribution
Chair for Electrochemical Energy Conversion
and Storage Systems
Battery Ageing • Battery Models • Battery Diagnostics • Battery Pack Design • Electromobility • Stationary Energy Storage • Energy System Analysis
Homogeneity of lithium analysis in lithium-ion batteries
A study on half-cells, full-cells
and parallel connected cells of the Tesla Model S 85
Friedrich Emanuel Hust, Dirk Uwe Sauer
01.02.2019 50 55 %
SOC
|
Chair for Electrochemical Energy Conversion and Storage Systems
Motivation
Current distribution
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer2
444
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Objective of this talk
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer3
Influence of distribution of lithium inside of high energy-cells during
Pulse-excitation
Electrochecmical impedance spectroscopy
Slow-transients in parallel connection
1
2
3
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Chair for Electrochemical Energy Conversion and Storage Systems
Structure of the talk
1. Definition of homogeneity of lithium distribution
Experimental results on half-cells
Experimental results on full-cells
Implication on parallel connected cells
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer4
Particle Particle
1
2
3
4
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Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Homogeneity of lithium distribution:
Is a metric for the distribution of lithium on the
electrode
A homogenous distribution is well defined:
Every particle of an electrode has the same
lithium concentration
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer5
Particle Particle
Homogeneity of lithium distribution on the anode
Graphite anode
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Homogeneity of lithium distribution on the anode
Graphite anode
Homogeneity of lithium distribution:
Is a metric for the distribution of lithium on the
electrode
A homogenous distribution is well defined:
Every particle of an electrode has the same
lithium concentration
An inhomogeneous distribution is not well defined.
It might be:
Discrete
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer6
Particle Particle
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Homogeneity of lithium distribution on the anode
Graphite anode
Homogeneity of lithium distribution:
Is a metric for the distribution of lithium on the
electrode
A homogenous distribution is well defined:
Every particle of an electrode has the same
lithium concentration
An inhomogeneous distribution is not well defined.
It might be:
Discrete
A continuous distribution
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer7
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Homogeneity of lithium distribution on the anode
Graphite anode
Homogeneity of lithium distribution:
Is a metric for the distribution of lithium on the
electrode
A homogenous distribution is well defined:
Every particle of an electrode has the same
lithium concentration
An inhomogeneous distribution is not well defined.
It might be:
Discrete
A continuous distribution
It is not possible to differentiate the homogeneity of
lithium distribution via OCV-measurement
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer8
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Homogeneity of lithium distribution on the anode
Graphite anode
Homogeneity of lithium distribution:
Is a metric for the distribution of lithium on the
electrode
A homogenous distribution is well defined:
Every particle of an electrode has the same
lithium concentration
An inhomogeneous distribution is not well defined.
It might be:
Discrete
A continuous distribution
It is not possible to differentiate the homogeneity of
lithium distribution via OCV-measurement
However, when charging or discharging, the shape
of the distribution will change and this can be
measured via the voltage
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer9
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Objective of this talk
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer10
Influence of distribution of lithium inside of high energy-cells during
Pulse-excitation
Electrochecmical impedance spectroscopy
Slow-transients in parallel connection
1
2
3
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Relaxation behavior
Graphite anode
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer11
shoulder
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Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer12
lithiation
Half-cell measurement
Graphite anode
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer13
lithiation
Half-cell measurement
Graphite anode
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer14
stage
2L - 2
stage 2
stage
2 -1
stage
2L - 2
stage 2
V 40 mV
stage 2
transition
Half-cell measurement
Graphite anode
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust15
stage
2L - 2
stage 2
stage
2 -1
stage
2L - 2
stage 2
Half-cell measurement
Graphite anode
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust16
stage
2L - 2
stage 2
stage
2 -1
stage
2L - 2
stage 2
         
Half-cell measurement
Graphite anode
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer17
Half-cell measurement
Graphite anode          
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer18
fast
particle
slow
particle
Hypothesis:
Anode as a cause of homogenization
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer19
Hypothesis:
Anode as a cause of homogenization
fast
particle
slow
particle
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer20
Hypothesis:
Anode as a cause of homogenization fast particle
slow particle
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer21
Hypothesis:
Anode as a cause of homogenization fast particle
slow particle
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer22
Hypothesis:
Anode as a cause of homogenization fast particle
slow particle
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
When charging the shape of the distribution will
change
Redistribution of lithium via potential
homogeneity of lithium distribution increases
Lithium distribution will peak before stage 2
Short-circuit graphite-graphite battery
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer23
Instable
Homogeneity of lithium distribution on the anode
Graphite anode
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Objective of this talk
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer24
Influence of distribution of lithium inside of high energy-cells during
Pulse-excitation
Electrochecmical impedance spectroscopy
Slow-transients in parallel connection
1
2
3
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Full-cell
Experimental protocol
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer25
Relaxation
measurement Electrochemical
Impedance
Spectroscopy
5%  1 kHz 1 mHz
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer26
1. Cathode is influencing lower
SOC
2. Anode is influencing higher
SOC
Full-cell
Electrochemical Impedance Spectroscopy
Non-invasive investigation of predominant processes in the impedance spectra of high energy lithium-ion batteries with Nickel-Cobalt-Aluminum cathodes
Pouyan Shafiei Sabet, Gereon Stahl, Dirk Uwe Sauer, Journal of Power Sources, 2018
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer27
1. Cathode is influencing lower
SOC
2. Anode is influencing higher
SOC
3. At 50 % SOC we reach
minimal Imag(Z) for low
frequency
Expected behahavior:
Imaginary part is strongly
.related to differential capacity
 ~ Imag (Z)
C is large
Full-cell
Electrochemical Impedance Spectroscopy
Non-invasive investigation of predominant processes in the impedance spectra of high energy lithium-ion batteries with Nickel-Cobalt-Aluminum cathodes
Pouyan Shafiei Sabet, Gereon Stahl, Dirk Uwe Sauer, Journal of Power Sources, 2018
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer28
Full-cell measurement
Relaxation measurement
Homogeneity of lithium distribution has a strong impact on the impedance
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Objective of this talk
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer29
Influence of distribution of lithium inside of high energy-cells during
Pulse-excitation
Electrochecmical impedance spectroscopy
Slow-transients in parallel connection
1
2
3
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
27 cells with a total capacity of around 84 Ah
Capacity check (10 A charging)
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer30
Parallel cells
Measurement device
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Parallel cells
Current redistribution
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer31
50 55 % SOC
Current converges as a mean of homogenization
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Parallel cells
Current redistribution
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer32
|
Lehrstuhl für Elektrochemische Energiewandlung und Speichersystemtechnik
Summary
01.02.2019 Friedrich Emanuel Hust, Dirk Uwe Sauer33
The distribution of lithium is influencing
the relaxation after pulse-excitation,
causing a redistribution via potential
difference
the impedance, causing a smaller
impedance in a homogenious state
the distribution of currents in parallel connected cells
1
50 55 %
SOC
2
3
Thank you
for your attention
Contact
Chair for Electrochemical Energy Conversion
and Storage Systems
Univ.-Prof. Dr. rer. nat. Dirk Uwe Sauer
RWTH Aachen University
Jaegerstrasse 17/19
52066 Aachen
GERMANY
www.isea.rwth-aachen.de
We thank
34
Tel.: +49 241 80-96927
fhu@isea.rwth-aachen.de
batteries@isea.rwth-aachen.de
Friedrich Emanuel Hust, Dirk Uwe Sauer
Chair for Electrochemical Energy Conversion
and Storage Systems
Battery Ageing • Battery Models • Battery Diagnostics • Battery Pack Design • Electromobility • Stationary Energy Storage • Energy System Analysis
Homogeneity of lithium analysis in lithium-ion batteries
A study on half-cells, full-cells
and parallel connected cells of the Tesla Model S 85
Friedrich Emanuel Hust, Dirk Uwe Sauer
01.02.2019 50 55 %
SOC
Chair for Electrochemical Energy Conversion
and Storage Systems
Battery Ageing • Battery Models • Battery Diagnostics • Battery Pack Design • Electromobility • Stationary Energy Storage • Energy System Analysis
Homogeneity of lithium analysis in lithium-ion batteries
A study on half-cells, full-cells
and parallel connected cells of the Tesla Model S 85
Friedrich Emanuel Hust, Dirk Uwe Sauer
01.02.2019 50 55 %
SOC
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