Post on 10-Mar-2018
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1680 East West Road, POST 109, Honolulu, HI 96822
Ph: (808) 956-2349 Fax: (808) 956-2336
Battery History and Anatomy
Matthieu Dubarry
Matthieu.Dubarry@gmail.com
Electricity was not used before less than 400 years ago
No practical use until the mid to late 1800s.
250000 light bulbs at the Chicago World Columbia Exposition (1893)
Bridge illumination over the Seine river in Paris, France (1900)
How old do you think the first battery is compare to electrification?
Centuries before? Just before? Right after? Well after?
Answer: -1000 BCE : The Baghdad Battery
A brief history of electrochemical systems
More details: Mythbusters episode 29
1749: Benjamin Franklin’s capacitors
Panels of glass coated with metal on each surface.
Used as static electricity generators.
Linking them together in a "battery" gave a stronger discharge.
Battery original meaning: "group of two or more similar objects functioning together", as in an artillery battery.
A brief history of electrochemical systems
1791: Luigi Galvani
Luigi Galvani, an Italian physicist, discovered a hint that paved the way to the idea of the battery. Galvani was dissecting a frog attached to a brass hook with an iron scalpel, and as he touched the frog’s leg, the leg twitched. The physicist believed that this was due to “animal electricity” wherein the energy that sparked the movement came from the leg itself.
A brief history of electrochemical systems
1800: “Modern” batteries, Alessandro Volta
Alessandro Volta believing this phenomenon was caused by two differentmetals joined together by a moist intermediary.
He verified this hypothesis through experiment, and published in 1791.
In 1800, Volta invented the first true battery, which came to be known as thevoltaic pile : pairs of copper and zinc discs piled on top of each other,separated by a layer of cloth or cardboard soaked in brine (i.e., theelectrolyte).
A brief history of electrochemical systems
https://www.youtube.com/watch?v=5DnaxcUKuhQ
Theory of electrodynamics
From Volta’s discovery, study of electrical current became possible:
1820, Ampère’s law of interaction between electrical currents;
1827, Ohm’s law of proportionality between voltage and current;
1831, Joule’s law of the thermal effect of electrical current;
1831, Faraday’s law of electromagnetic induction, and many others.
These achievements led to the development of the theory of electrodynamics and practice of electrical engineering and, as a result, to the appearance of a revolutionary new power source: the electromagnetic generator invented in 1866 by Werner von Siemens, which soon surpassed their predecessors both in electrical and economic parameters.
A brief history of electrochemical systems
1839: William Robert Grove invented the fuel cell
He called it gas voltaic battery, produced electrical energy by combining hydrogen and oxygen.
In showing that steam could be disassociated into oxygen and hydrogen, and the process reversed, he was the first person to demonstrate the thermal dissociation of molecules into their constituent atoms
A brief history of electrochemical systems
1859: Gaston Planté invented the lead acid battery
First rechargeable system
His early model consisted of a spiral roll of two sheets of pure lead separated by a linen cloth, immersed in a glass jar of sulfuric acid solution
A brief history of electrochemical systems
A brief history of electrochemical systems
1866: Georges Leclanché, forerunner of the modern dry cell battery.
It comprised a conducting solution (electrolyte) of ammonium chloride with a negative terminal of zinc and a positive terminal of manganese dioxide.
These “dry” Leclanché batteries proved to be very simple with regard to manufacture and reliable in usage. As early as 1868, more than twenty thousands of such cells were being manufactured.
A brief history of electrochemical systems
20th century: new technologies and ubiquity:
1949: Alkaline dry cells (market 1959)
1949: Hajek imagined the Lithium batteries
1957: Invention of lithium batteries by Herbert & Ulam
1966: Supercapacitors were invented in Cleveland.
Late 1960s: Nickel Metal Hydride cells
1970s: Li-ion batteries (Whittingham) & Flow batteries
1990: Commercialization of Ni-MH batteries
1991: Commercialization of Li-ion batteries (SONY)
Early 1900s to 1920s: The (hopefully 1st) golden age of electric vehicles
1884: Invented by Thomas Parker (UK)
1895: First auto race in America , won by an EV.
1896: First car dealer – sells only EVs.
1898: NYC blizzard, only EVs were capable of transport on the roads.
1900: NYC's huge pollution problem – horses. 2.5 million pounds of manure, 60,000 gallons of urine daily on the streets; 15,000 dead horses removed from the streets each year. All US cars produced: 33% steam cars, 33% EV, and 33% gasoline cars.
A brief history of electric vehicles
1990s: Revival of interest for EVs
Push from the California Air Resources Board for lower emissions vehicles
Chrysler, Toyota, and a group of GM dealers sued CARB in Federal court, leading to the eventual neutering of CARB's ZEV Mandate.
A brief history of electric vehicles
http://www.whokilledtheelectriccar.com/
2010s: New generation of EVs
The world's two best selling all-electric cars of all-time are the Nissan Leaf with 200,000 global sales, and the Tesla Model S, with 100,000 units, both, by December 2015
A brief history of electric vehicles
A look into the future…
A brief history of electrochemical systems
Air batteries
Li-sulfur batteries For storage: different opportunities
Summarized timeline:
A brief history of electrochemical systems
http://www.upsbatterycenter.com/blog/history-batteries-timeline/https://en.wikipedia.org/http://batteryuniversity.com/learn/article/when_was_the_battery_inventedhttp://www.upsbatterycenter.com/blog/history-batteries-timeline/http://www.electricauto.org/?page=evhistory
Sources:
Principles
Reactions in batteries are chemical reactions between an oxidizer and a reducer.
In reactions of this type, the reducer being oxidized releases electrons while the oxidizer being reduced accepts electrons.
In the simple case a battery (cell) consists of two electrodes made of different materials immersed in an electrolyte. The oxidizer is present on one electrode, the reducer on the other.
Battery AnatomyEl
ectr
od
e 1
Elec
tro
de
2
Electrolyte
e- ions
e- ions
When these electrodes are placed into the common electrolyte, an open circuit voltage (OCV) develops between them. When they are additionally connected by an electronically conducting external circuit, the OCV causes electrons to flow through it from the negative to the positive electrode.This current is the result of reactions occurring at the surfaces of the electrodes immersed into the electrolyte.
Activity table
Battery Anatomy - Half cell potentials
More extensive one:http://en.wikipedia.org/wiki/Standard_electrode_potential_(data_page)
The more positive the half-cell EMF, the greater the tendency of the reductant to donate electrons, and the smaller thetendency of the oxidant to accept electrons.
A species in the leftmost column can act as an oxidizing agent to any species below it in the reductant column.
Oxidants such as Cl2 that are above H2O will tend to decompose water.
Classification
By their principles of functioning, batteries can be classified as follows:
1. Primary (single-discharge) batteries.
A primary battery contains a finite quantity of the reactants participating in the reaction; once this quantity is consumed (on completion of discharge), a primary battery cannot be used again (“throw-away batteries”).
Battery Anatomy
Classification
By their principles of functioning, batteries can be classified as follows:
2. Secondary (or rechargeable) batteries.
On the completion of discharge, a storage battery can be recharged by forcing an electric current through it in the opposite direction; this will regenerate the original reactants from the reaction (or discharge) products.
Battery Anatomy
Classification
By their principles of functioning, batteries can be classified as follows:
3. Fuel cells.
In the fuel-cell mode of operation, reactants are continuously fed into the cell (or battery) while reaction products are continuously removed.
Hence, fuel cells can deliver current continuously for a considerable length of time, which largely depends on external reactant storage.
Battery Anatomy
Classification
By their principles of functioning, batteries can be classified as follows:
2.5 Flow batteries
Electrolyte tanks. Can be changed or recharged
Battery Anatomy
Classification
By their principles of functioning, batteries can be classified as follows:
4. Supercapacitors.
Electrochemical capacitors uses the double-layer effect to store electric energy. This double-layer has no conventional solid dielectric which separates the charges.
Battery Anatomy
Different chemistries: different properties, price, efficiency and lifetime
Battery Anatomy
Different chemistries: different properties, price, efficiency and lifetime
Battery Anatomy
Source: KEMA Market Evaluation for Energy Storage in the United States
Modern battery dates back to the 1800s
Invented by Alessandro Volta
Opened the gate to electrification
Lot different chemistries invented since the 1800s
Provide different voltages, performances, lifetime…
Choice depends on application
Li-ion batteries, Lead Acid batteries, Ni-MH, Fuel cells…
Battery History and Anatomy – Take home message
Any questions?
Electricity and the waterfall analogy
Water only spontaneously flows one way in a waterfall.
Likewise electrons only spontaneously flow one way in a redox reaction
From higher to lower potential energy.
Battery Anatomy
Electricity and the waterfall analogy
The Voltage is the driving force, the Current is the flow of electric charge
The Resistance is the opposition to the passage
Battery Anatomy
Height (voltage)
Kahiwa falls Akaka falls Rainbow falls
Flow (current)
Resistance (opposition)
660 m 129 m 31 m
small medium large
negligible negligiblemedium(6 tiers)
1680 East West Road, POST 109, Honolulu, HI 96822
Ph: (808) 956-2349 Fax: (808) 956-2336
Lithium battery specifics
Matthieu Dubarry
Matthieu.Dubarry@gmail.com
First specificity: the voltage
Lithium battery specifics
Eo (V)
H2O/O2
H+/H2 0
1.23
–
+Fuel cell, 1.23V
PbSO4/Pb -0.36 –
PbO2/PbSO4 1.68 +Lead Acid, 2.1V
Ni-MH, 1.2V
MH/M
NiO(OH)/Ni(OH)2
~- 0.6
0.6
–
+
Li+/Li
Fe3+/Fe2+
-3
0.77
–
+Lithium, 3.77V
From their chemistry Lithium batteries have2x or 3x more energy than other technologies
Li batteries should not work because there is no stable electrolyte
The KEY of Li batteries is: « it works ONLY because stable SEI forms and prevents further electrolyte degradation »
Lithium battery specifics
« SEI » Solid ElectrolyteInterphase
2 V
olt m
ax
Electrolyte Stability window
SEI
SEI
Aqueous electrolyte
Non-Aqueous electrolyte
Lithium dendrites
However, irregularities at the SEI may lead to uneven lithium deposition upon charge, with dendrite formation that grows to short the cell.
In extreme cases, these uncontrolled events give rise to overheating effects with associated thermal runaway and explosions.
Lithium battery specifics
https://www.youtube.com/watch?v=zwLUD41f15U https://www.youtube.com/watch?v=uyO-XE-Q9ZQ
Proposed solution to the dendrite problem:
(1) a careful choice of the electrolyte system to assure optimized, smooth
lithium deposition
Demonstrated as early as the early 1980s but expensive and harsh chemicals
(2) Another popular route for assuring safe lithium cycling was to switch from liquid, reacting solutions to solid, inert electrolytes.
To prevent serious ohmic polarization, need high lithium conductivity at RT.
Not many materials fulfill this condition.Solid state polymer electrolyte (PEO): working at T>70°C
Was commercialized in the late 90’s
Successful demonstration project but abandoned.
Recently reconsidered by Bolloré/Blue Solutions for the blue car
Lithium battery specifics
Blue Solutions Lithium metal polymer cell
Lithium battery specifics
https://www.blue-solutions.com/en/
Proposed solution to the dendrite problem:
(1) a careful choice of the electrolyte system to assure optimized, smooth
lithium deposition
Demonstrated as early as the early 1980s but expensive and harsh chemicals
(2) Another popular route for assuring safe lithium cycling was to switch from liquid, reacting solutions to solid, inert electrolytes.
To prevent serious ohmic polarization, need high lithium conductivity at RT.
Not many materials fulfill this condition.Solid state polymer electrolyte (PEO): working at T>70°C
Was commercialized in the late 90’s
Successful demonstration project but abandoned.
Recently reconsidered by Bolloré for the blue car
(3) Replacement of the lithium metal with a less aggressive anode material
Use an intercalation anode: Li-ion cells, the “rocking chair battery”
Use of alloys
Lithium battery specifics
Non intercalation batteries
Lithium battery specifics
Lithium battery specifics
Intercalation Reaction Electrodes
++
++
+
+
++
Intercalation reactionIons are intercalated in the crystal structure of the electrode Diffusion of ions in the electrode intercalation material.
surface reaction
++
e-
+
+ e-
e-
e-
e-
e-
e-
e-
e-
e-
e-
+
Lithium battery specifics
Insertion Reaction Electrodes
Examples: V2O5
X. Rocquefelte, Ph.D thesis
Lithium battery specifics
Insertion Reaction Electrodes
Examples: Graphite
Positive electrodes
Nearly all use transition metals
A transition metal is one of the 38 chemical elements from periods 4 to 7 (rows) and
groups 3 to 12 (columns) in the Periodic Table of the Elements.
Unlike alkali metals (column 1) and alkali earth metals (column 2), the transition metals can form ions with a wide variety of degrees of oxidation.
It is this property which is exploited in batteries.
In practice only some of first row are useable because of the existence of high degree of oxidation: Ti, V, Mn, Fe, Co and Ni.
Sc is too rare, Cr is toxic, Cu has a too low potential and zinc not a high enough degree of ox.
Lithium battery specifics
Lithium battery specifics
Insertion Reaction Electrodes
Examples: V2O5
X. Rocquefelte, Ph.D thesis
Lithium battery specifics
2.8
3
3.2
3.4
3.6
3.8
4
4.2
0 0.05 0.1 0.15 0.2 0.25 0.3
Vo
lta
ge (
V)
Discharged Capacity (Ah)
Li-ion
Lead acid
Present and future development regarding Li-ion batteries
Improvement of the intrinsic performances (energy, power)
Lithium battery specifics
Thermal runaway
"thermal runaway" describes a process which is accelerated by increased temperature, in turn releasing energy that further increases temperature. In chemistry (and chemical engineering), this risk is associated with strongly exothermic reactions that are accelerated by temperature rise.
Apply for electrolyte
Decomposition of electrolyte salts and interactions between the salts and solvent start at as low as 70oC. Significant decomposition occurs at higher temperatures.
Lithium battery specifics
Lithium battery specifics
Lithium resources
https://www.youtube.com/watch?v=7wAH7bdXE6ghttp://vimeo.com/18145602
Lithium resources
An 18650 cell, which is used almost universally in portable computers,
contains 0.8 g of lithium for a capacity of 2.7 Ah. At $6/kg, the cost
Lithium Resources attributable to lithium is less than $0.005.
For an average-sized electric vehicle, the mass of lithium needed to createa battery pack is around 3 kg. At $6/kg, the cost of the lithium works out atless than $20, a very small part of the final cost of the battery pack
Lithium battery specifics
Lithium battery specifics
Any questions?
Electrode architecture
Lithium battery specifics
Mixing the Active material (poor conductivity) with
Electron-conductive agent (CB powder) e- conductivity
Liquid electrolyte within the porosity Li+ conductivity
Polymeric binder B Cohesion and Adhesion
CB/Binder network
AM
Li+
Liq
uid
ele
ctr
oly
te
e-
e-
e-
Cu
rr
en
t c
oll
ec
tor
Li+
Li+
Positive electrodes
Lithium battery specifics
The first commercial prototypes appeared in the late 1970s,
Exxon Company using a TiS2 cathode and Moli Energy Battery group using a MoS2, both with liquid organic electrolytes.
However, some operational faults, including fire incidents, led to the rapid conclusion that there were some problems that prevented safe, extended operation of these first lithium batteries.
It was soon realized that the problems were associated with the anode; due to its very high reactivity, lithium metal reacts readily with the electrolyte: formation of a passivation layer on its surface.
Lithium battery specifics
An Exxon LiTiS2 rechargeable lithium battery exhibited at the Chicago electric vehicle (EV) show in 1977. This cell used a tetramethylboride salt in dioxolane solvent electrolyte and each cell had a capacity of 45 Wh. It had pressure relieve valves, to ensure no pressure buildup.
1680 East West Road, POST 109, Honolulu, HI 96822
Ph: (808) 956-2349 Fax: (808) 956-2336
Lithium-ion battery testing and degradation analysis
Matthieu Dubarry
Matthieu.Dubarry@gmail.com
50
Introduction
Path dependence of the degradation
What is the problem?
Different paths will lead to different degradation and different evolution of OCV vs. SOC curves.
51
Introduction
Path dependence of the degradation
What is the problem?
?
Possible to handle individual paths
52
Introduction
Path dependence of the degradation
What is the problem?
?
Infinite possible combinations : Impossible to predictNeed to diagnose on board on a case by case basis
53
Battery degradation is extremely sensitive to usage and chemistry.
Introduction
Path dependence of the degradation
Ca
pa
city
Time
Path A
Path BPath D
Path C
54
Active
elements
StructureMorphology Architecture
Loading,
SeparatorCasing
Voltage
Theoretical CapacityRate capabilityCycle life
Ohmic resistance
Nominal capacity
Cell specificcapacity
Intrinsic Electrode processing
Cell manufacturingΔ Rate capability
Δ ResistanceΔ Capacity
Δ Weight
Δ PERFORMANCE
55Introduction
Path dependence of the degradation
Need to characterize cells variability
To compare cells and protocols
To insure safety of battery packs
Can be fully addressed with 3 attributes:
Capacity : Amount of active material
Resistance : Ohmic resistance
Rate capability: Faradic resistance
Laboratory testing
Cell to cell variations
Dubarry, Vuillaume, Liaw, Int. J. Energy Res., 34 (2010) 216–231.
Dubarry, Vuillaume, Liaw, J. Power Sources 186 (2009) 500-507.
56
Laboratory testing
Good practices
57
Formation cycles
1 – Ensure formation is completed(stable capacity & voltage response)
2 – Assess cell-to-cell variations1 cycle @ C/21 cycle @ C/5
Duty Cycle
1 – Must be representative of real usage
End Of Life
Laboratory testing
Good practices
58
Formation cycles
1 – Assess cell performance2 – Allow electrochemical analysis
At least:1 cycle @ C/25 Thermodynamic assessment1 cycle @ C/1 Kinetic assessment
End Of Life
Duty Cycle
ReferencePerformanceTest
MonthlyReferencePerformanceTest
Useful diagnosis is a complex balance
Battery Diagnosis
A complex balance
59
Accuracy of diagnosis Diagnosis resources
LOW
HIGH LOW
HIGH
Useful diagnosis is a complex balance
Academics
60
Accuracy of diagnosis Diagnosis resources
LOW
HIGH LOW
HIGH
Post mortem analysisHalf cell analysis,…XRD, EXAFS, XANES,…First principle modeling,…
Expensive & complexExperimentsHeavy computing
Battery Diagnosis
A complex balance
Lithium ion battery degradation mechanisms
Introduction
Why derivative methods?
J. Groot, State of Health Estimation of Li-ion batteries cycle life test methods
61
Useful diagnosis is a complex balance
Industry
62
Accuracy of diagnosis Diagnosis resources
LOW
HIGH LOW
HIGH
Voltage & capacity monitoring
Simple characterizationLook up tablesLimited computing
Battery Diagnosis
A complex balance
Classic Industry outputs
63
Q
t t
R
Limited to no knowledge of degradation mechanisms
Battery Diagnosis
A complex balance
0
0.5
1
1.5
2
0 200 400 600 800 1000
2C agingC/25C/5C/2C/12C5C
Ca
pacity (
Ah)
Cycle #
Use testing to address key parameters
Battery Diagnosis
A complex balance
64
Cycle life
Ohmic resistance
VoltageCapacity
Rate capability
10
100
10 100
-20oC
-5oC
10oC
25oC
40oC
60oC
Sp
ecific
en
erg
y (
Wh
.kg
-1)
Specific power (W.kg-1
)
200
400
Voltage vs. capacity Capacity vs. cycle #
Specific P & E vs. TRohmic vs. T
2.5
3
3.5
4
0 0.5 1 1.5 2
C/25
C/5
C/2
C/1
2C
5C
Voltage (
V)
Capacity (Ah)
Conventional battery testing only assess cell performance metricsNot performing diagnostics for battery management
Useful diagnosis is a complex balance
Derivative methods can offer an happy balance
65
Accuracy of diagnosis Diagnosis resources
LOW
HIGH LOW
HIGH
Look up tablesMedium computing
Battery Diagnosis
A complex balance
Lithium ion battery degradation mechanisms
J. Groot, State of Health Estimation of Li-ion batteries cycle life test methods
Change in lithium
inventory
Change in active
material
Change in ohmic and
faradic resistances
Useful categorization for diagnostics
Thermodynamics
Kinetics
66Battery Diagnosis
A complex balance
Useful diagnosis is a complex balance
Derivative methods can offer an happy balance
67
Accuracy of diagnosis Diagnosis resources
LOW
HIGH LOW
HIGH
Quantification ofdegradation modes
Look up tablesMedium computing
Battery Diagnosis
A complex balance
Adapt to industry requirements:
Use of available sensors: voltage, current and temperature.
Voltage carries thermodynamic information
Study evolution of voltage response
How can we extract degradation information?
How can we put it in equation for a model?
Use derivative method (enhance changes): IC
Link every feature to corresponding
reactions in the PE and the NE
Follow peak evolution to deduce the origin
-2
-1.5
-1
-0.5
0
3 3.2 3.4 3.6 3.8 4 4.2
Cycle 10Cycle 250Cycle 500
Incre
me
nta
l cap
acity (
Ah
V-1
)
Voltage (V)
2.6
2.8
3
3.2
3.4
3.6
3.8
4
4.2
0 0.5 1 1.5 2
Cycle 10Cycle 250Cycle 500
Incre
men
tal cap
acity (
Ah V
-1)
Voltage (V)
68Battery Diagnosis
A complex balance
Capacity (Ah)
Voltage (
V)
ΔQ/ ΔV
Experimentally: possible by coupling 2 techniques:
Battery Diagnosis
A complex balance
0
10
20
30
40
50
60
70
0 200 400 600 800 1000
C/25C/5C/2C/12C
Cap
acity lo
ss (
%)
Cycle #
Loss of lithium inventory
Loss of active
material
Kinetic limitations
Resistance increase
-2
-1.5
-1
-0.5
0
3 3.2 3.4 3.6 3.8 4 4.2
Cycle 10Cycle 250Cycle 500
Incre
men
tal cap
acity (
Ah
/V)
Voltage (V)
0
10
20
30
40
50
0 200 400 600 800 1000
C/25C/5C/1C2C
EO
D S
OC
(%
)
Cycle #
SOH tracking +
SOC tracking
M. Dubarry et al. J. Power Sources 196 (2011) 10336
M. Dubarry et al. J. Power Sources, 196(7), (2011) 3420
M. Dubarry et al. J. Power Sources 194 (2009) 551
Rest cell voltagesevolution
Incremental capacitycurves evolution
Change in lithium
inventory
Change in active
material
Change in ohmic and
faradic resistances
2C aging at RT
69
1.2
1.4
1.6
1.8
2
2.2
2.4
0 500 1000 1500 2000
DST/4C
4C/4C
y = 2.2446 - 0.0001232x R= 0.9978
y = 2.3051 - 9.9021e-5x R= 0.99331
Cap
acity (
Ah
)
Cycle #
Battery Diagnosis
A complex balance
-40
-35
-30
-25
-20
-15
-10
-5
0
3.1 3.15 3.2 3.25 3.3 3.35 3.4 3.45 3.5
IC (
Ah
/V)
Voltage (V)
-40
-35
-30
-25
-20
-15
-10
-5
0
3.1 3.15 3.2 3.25 3.3 3.35 3.4 3.45 3.5
IC (
Ah
/V)
Voltage (V)
-40
-35
-30
-25
-20
-15
-10
-5
0
3.1 3.15 3.2 3.25 3.3 3.35 3.4 3.45 3.5
IC (
Ah
/V)
Voltage (V)
We studyvoltagevariations
To understandthe degradationfrom a materialstand point
We then use that knowledgeto predict what willhappen to the cell
?Conventional approach
Our approach
0
5
10
15
20
25
30
35
40
0 500 1000 1500 2000
Deg
rad
ation
%
Cycle number
LAMNE: loss of negative electrode material
LLI: Loss of lithium inventory
Peak indexation: The clepsydra analogy
Use individual electrode response
Understanding the degradation mechanisms
Understanding the IC signature
Peak
Beginning of discharge
Middle of discharge
End of discharge
-3
-2.5
-2
-1.5
-1
-0.5
0
3.2 3.4 3.6 3.8 4 4.2
Incre
men
tal cap
acity (
V-1
)
Voltage (V)
LiMn⅓Ni⅓Co⅓O
2
LiMn2 O
4
Peak Peak
Li+
M. Dubarry et al., J. Power Sources, 196 (2011) 10328.
M. Dubarry, A. Devie and B.Y. Liaw, JEPS In press
Water clock concept: M. Dubarry et al. ECS222/PRIME2012 (2012) abs# 885
IC curves contains information on every component of the cell
The clepsydra analogy enables the indexing of IC curves
NE NE NE
PE PE PE
Vo
lta
ge
Vo
lta
ge
Vo
lta
ge
Li+
71
Clepsydra analogy: Visualize effect of categories of degradation
Understanding the degradation mechanisms
Understanding changes in the IC signature
Initial LAMPELLI Ohmic R increase Faradic R increase
Different degradation categories will have different voltage signaturesDiagnostic possible w/o post-mortem analysesNo need to be an electrochemist
Vo
lta
ge
72
Simple, fast, powerful and accurate diagnosis and prognosis tool
Mechanistic diagnosis and prognosis
Graphical user interface: the ‘alawa toolbox
Stand alone GUI available for license or collaboration
73
Degradation maps: GIC//LFP
Mechanistic diagnosis and prognosis
Degradation simulation examples
74
Mechanistic diagnosis and prognosis
Unique capabilities and benefits
Dubarry, Truchot and Liaw, J.Power Sources, 219 (2012) 204-216
Multi degradation simulationdV/dQ simulation
dQ/dV simulation
Q, P, SOC, RCV calculations
75
Effect of path : from any sources of information
(e.g. laboratory testing, literature, physical modeling,…)
Mechanistic diagnosis and prognosis
Path dependence emulation
If the effect of a path is known, it can be emulated:Prognosis and path dependence emulation
Computation is not intensive.Easy to parameterize. Easy to use.
Complement other modeling approachesReduce complexity: Could be the link between battery material research and BMS
* Dubarry et al. J. Power Sources 196 (2011) 10336
** Kassem et al. J. Power Sources 208 (2012) 296
*** Dubarry et al. J. Electrochem. Soc, 160(2), p. A191 (2013).
RTcycling
Calendaraging
LTexcursion
HTexcursion
Linear LLI +Exponential LAM
*
LLI = f(t,T,SOC) ** LLI+ RDF = f(T) ***
LLI = f(T) ***
Initial LLI thenLinear LLI +
Exponential LAM*
0
20
40
60
80
100
0 200 400 600 800 1000
Cap
acity a
nd
de
gra
datio
n (
%)
Cycle #
Regular RT cycling
LAMNMC
LLIcalendar+LLIaging
LLIcalendar
RT cycling after calendar ageing
76
Battery packsNeeds battery model and state estimator
77
State of Charge (SOC) Estimation
Equivalent of a fuel gauge
for a battery
State estimator
The SOC problem
How is it calculated?
9.5
10
10.5
11
11.5
12
12.5
13
020406080100
Vo
ltag
e (
V)
SOC (%)
Rest Voltage compared lookup table
25
78
9.5
10
10.5
11
11.5
12
12.5
13
020406080100
Cycle 1Cycle 350Cycle 650Cycle 950
Vo
ltag
e (
V)
SOC (%)
State of Charge (SOC) Estimation
State estimator
The SOC problem
What is the problem?
1025
To stay accurate OCV vs. SOC curves needs to be updated according to battery state of health (SOH)
Rest Voltage compared lookup table
79
Academia and industry do not have the same definition for SOC.
For industry, SOC is often defined as “The ratio of the Ampere hours remaining in a battery at a given rate to the rated capacity under the same specified conditions”.
Some people read it as using the nominal capacity instead of “the rated capacity under the same specified conditions”
For academia (and especially electrochemists), SOC is a state function which represents the thermodynamic property of the system.
State estimator
The SOC problem
𝑆𝑂𝐶𝑡 =𝑅𝑒𝑚𝑎𝑖𝑛𝑖𝑛𝑔 𝑒𝑥𝑐ℎ𝑎𝑛𝑔𝑒𝑎𝑏𝑙𝑒 𝐿𝑖+ 𝑖𝑜𝑛𝑠
𝑇𝑜𝑡𝑎𝑙 𝑒𝑥𝑐ℎ𝑎𝑛𝑔𝑒𝑎𝑏𝑙𝑒 𝐿𝑖+ 𝑖𝑜𝑛𝑠=
𝑄𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙
𝑄𝑚𝑎𝑥
𝑆𝑂𝐶𝑈 =𝑄𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙
𝑄𝐶
𝑆𝑂𝐶𝑒 =𝑄𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙
𝑄𝑛𝑜𝑚
80
2.8
3.2
3.6
4
0 20 40 60 80 100
C/25
C/5
C/2
C/1
2C
Vo
lta
ge
(V
)
Normalized capacity (%)
Let’s compare them:
State estimator
The SOC problem
SOCt
SOCU definition: SOC scale depends on applied current.Make sense as fuel gauge: miles you can do if you maintain your speedBUT no reference and so no link to thermodynamics.
0100
0100SOCe
𝑆𝑂𝐶𝑈 =𝑄𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙
𝑄𝐶
𝑆𝑂𝐶𝑒 =𝑄𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙
𝑄𝑛𝑜𝑚
𝑆𝑂𝐶𝑡 =𝑄𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙
𝑄𝑚𝑎𝑥
vs. vs.
0100SOCU@C/2
0100SOCU@C/25
0100SOCU@2C
SOCe definition: SOC scale do not depend on applied current.BUT awkward fuel gauge: miles you can do is you start driving at 60mphAnd still no link to thermodynamics.
SOCt definition: link to thermodynamics.BUT awkward fuel gauge:miles you can do if youslow down to really low speed
A common ground need to be met to allow proper communication
X
X
81
Let’s compare them:
State estimator
The SOC problem
SOCU definition: SOC scale depends on applied current.Make sense as fuel gauge: miles you can do if you maintain your speedBUT no reference and so no link to thermodynamics.
𝑆𝑂𝐶𝑈 =𝑄𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙
𝑄𝐶
𝑆𝑂𝐶𝑒 =𝑄𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙
𝑄𝑛𝑜𝑚
𝑆𝑂𝐶𝑡 =𝑄𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙
𝑄𝑚𝑎𝑥
vs. vs.
SOCe definition: SOC scale do not depend on applied current.BUT awkward fuel gauge: miles you can do is you start driving at 60mphAnd still no link to thermodynamics.
SOCt definition: link to thermodynamics.BUT awkward fuel gauge:SOC miles you can do if youslow down to really low speed
X
X𝑆𝑂𝐶𝑈 =
𝑄𝑟𝑒𝑠𝑖𝑑𝑢𝑎𝑙
𝑄𝐶
X
= 1 − 𝐷𝑂𝐷𝑈
The best solution to reduce disconnect would be to use two different metrics:
DOD for fuel gauge applications
SOC for battery state monitoring
DOD 1 – SOC but can be calculated from SOC.
C. Truchot, M. Dubarry and B.Y. Liaw, Applied Energy, 119, 218 (2014).
M. Dubarry, V. Svoboda, R. Hwu, and B.Y. Liaw, J. Power Sources, 174(2), 1121 (2007).
82
New approach using in-situ data and single cell OCV response
E.g. 3S string with T gradient
State estimator
SOC calibration for battery packs
83
0.5
0.6
0.7
0.8
0.9
1
1.1
0 100 200 300 400 500 600
25oC
60oC
3S1P
Cap
acity,
Ah
Cycle #
25°C 60°C 25°C
Easy and quick in-situ battery pack full OCV vs. SOC curve determinationAlso allows accurate imbalance tracking
M. Dubarry, C. truchot, A. Devie, and B.Y. Liaw, Journal of The Electrochemical Society, 162 (6) A877-A884 (2015)
Lithium-ion battery testing and degradation analysis
Any questions?
Formation cycles
End Of Life
Duty Cycle
ReferencePerformanceTest
MonthlyReferencePerformanceTest
-2
-1.5
-1
-0.5
0
3 3.2 3.4 3.6 3.8 4 4.2
Cycle 10Cycle 250Cycle 500
Incre
men
tal cap
acity (
Ah
/V)
Voltage (V)
-2
-1.5
-1
-0.5
0
3 3.2 3.4 3.6 3.8 4 4.2
Cycle 10Cycle 250Cycle 500
Incre
men
tal cap
acity (
Ah
/V)
Voltage (V)