Batteries: fin du maillon faible? Batterien: Nicht mehr das

Transcription

Technik und Informatik / Wissens- und Technologietransfer
Batteries: fin du maillon faible?
Batterien: Nicht mehr das schwächste Glied?
Batteries: No longer the weak link in the chain?
Electric Drive System Research Activities at
Bern University of Applied Sciences
Engineering and Information Technology
Andrea Vezzini, Switzerland
D sc. techn.
Dr.
t h ETHZ
August 2008
About the Speaker
Dr. Andrea Vezzini
• Professor for Industrial
Electronics since 1996 at
Bern University of Applied
Sciences (BFH TI)
• Chairman of the Board of
drivetek ag since 2002
• 2003 Visiting Guest
Professor at General Motors
Advanced Technology
C t in
Center
i Torrance
T
(7
Months)
• 2007 Distinguished Visiting
Scientist at CSIRO, Australia
(5 Months)
1
BFH Engineering and
Information Technology
•
Part of Bern University of
Applied
pp
Sciences
6 Divisions with a total of
1’300 students, second
biggest in Switzerland
External Turnover with
aR&D 2007: approx. 10
Mio. CHF (+ 2.5 Mio. CHF
internal)
Strategic Programs in Fuel
Cell Development,
Automotive Systems and
Renewable Energy
Over 10 Innovation prices
since 1993
•
•
•
•
Content

What is required?
What is possible?
p
What do we (BFH) do?
What will be?
“The outcome of any serious research can only be to make two questions grow where only one
grew before.
before ”
Thorstein Veblen
US economist & social philosopher (1857 ‐ 1929)
2
Analyst's Consensus on Growth
• In the last 10 years car numbers raised
from 700 to 800 millions.
• By 2020, analysts predict 1.1 billion
vehicles (an increase of 300 million).
Parked end
end‐to‐end,
to end enough to circle
the earth 125 times.
• Assuming a stable growth of the world
economy, numbers of 2 – 3 billions
vehicles are possible (ca. 300 vehicles /
1‘000 inhabitants)
• Even at a worldwide fleet consumption
of 2–3 l/100km: no reduction in
consumption or CO2 emissions is
possible.
possible
• Energy diversity and new technology
solutions are required in the future.
Reducing dependency on petroleum is
imperative.
Sources:
Steven E. Schulz: “Power Electronics for Electric and
Hybrid Vehicles”, APEC 2008 / Hybrid.com
Urs Muntwyler, IEA Chairman, BFH Energievorträge
2008
Lightweight EVs make a lot of sense
• Most transportation needs could be covered by
electric vehicles and charging stations
• Vehicle Mass reduction offers a great potential for
energy consumption reduction
Sources:
• ARE/BFS: Mikrozensus Studie Mobilität
• Bernhard Gerster: Mobilität ohne Erdöl – Schrecken oder Vision, BFH
Energiezukunft, Vorlesungsreihe 2008
3
BFH Vehicle Performance Simulation
Wheel torque vs. Vehicle Speed; m=720kg, different Acceleration Profile, Power and Grade
1400
Acceleration 0.. 400m for vehicle weight = 720kg on a 0% grade
0-100km/[email protected] 0%
1200
13
16
80
1000
14
15
70
14
15
16
17
20
26
50
19
18
60
22
24
Wheel Power [kW]
[email protected] 0%
14
26
17
19
20
90
13
Wheel Torque [Nm]
22
24
18
15
100
15
16
40
16
17
18
20
24
22
20
18
19
20
20
22
26
10
18
19
400
24
26
600
800
40-80km/h@5sec 8%
64kW
60kW
80-120km/h@8sec 0%
Superposition
56kW
52kW
48kW
44kW
800
40kW
36kW
600
30%
32kW
28kW
20%
24kW
20kW
400
17
19
30
68kW
10%
200
6%
22
3%
24
1000
1200
1400
Wheel Torque [Nm]
1600
24
2000
1800
Size: Compact Passenger Car (e.g. Citroën C4, Peugeot 207)
•Frontal Area: 2.6m2
•Air drag coefficient cw: 0.3
•Cw*A= 0.78
•Rolling resistance coefficient cr: 0.012
•Wheel Radius: 0.3m
•Mass: 1050 kg
•Goals:
• 0‐100km/h: 10…13s
• 0‐50km/h: < 5s
• Ppeak: 45kW…75kW
0
0%
0
200
400
600
800
1000
Speed / Base Speed [rpm]
1200
1400
drive train requirements
Based on the limits from the different requirements,
the possible motor specs (base speed and nominal
torque are plotted. The red line is the combined
curve all the motor specs, which will fulfill all the
requirements.
Drive Cycle Results: ZH‐Pendler Cycle Simulations
Energy for 38 km Pendler Cycle
12
Energy [% of total] for 38 km Pendler Cycle
3.5
10
1000
3
Energy[% of T
Total]
45kW - Peak Pow er
25
2.5
500
2
Torque for a=0 @ 0%
0
6
4
1.5
2
-500
1
0
0
20
40
60
80
Speed[km/h]
0.5
-1000
100000
<
100
120
140
STOP
100 km
0
20
40
60
80
Speed[km/h]
100
120
Relational
Operator
0
140
1/s
s
Integrator
distance [m]
U_batt
Battery
and
BattMan
v(t) [m/s]
M_wheel
W_batt _J
Stop Simulation
v_veh
W_batt _end
To Workspace 4
Torque on
the Wheels [Nm ]
Speed: Pendler Cycle
x 10
Mechanical Power: Pendler Cycle
4
Acceleration: Pendler Cycle
1/1000
5
85 /3.6
4
120
to kW
v_const.
P_mot_out
100
80
60
A c c e l e r a t io n [ m / s 2 ]
M e c h a n ic a l P o w e r [ W ]
2
1
0
1
2
speed
sign
City-Cycle
v _ref
Mwheel
v
Pwheel
Mwheel
drive resistance
0.6
0.8 1 1.2
distance [m]
1.4
1.6
1.8
2
4
x 10
M_m ot
P_el
P_el
M_mot
speed controller
(driver model )
0
W_el_tot
Mwheel
w_mot
Mechanics
w_mot
Electronics
and Motor
w_mot
Energy
Counter
Wmot_Wh
W_mot _end
To Workspace1
3.6
-4
0.4
To Workspace5
M_mot
1
to km/h
-4
0.2
P_el 1
Pmot_out
v _ist
-3
-3
0
v
-2
-2
20
3
-1
-1
40
0
P_el
4
3
S p e e d [k m /h ]
Torque[Nm]
23kW - Cont Pow er
8
0
0.2
0.4
0.6
0.8
1 1.2
distance [m]
1.4
1.6
1.8
2
4
x 10
-5
0
0.2
0.4
0.6
0.8
1 1.2
distance [m]
1.4
1.6
1.8
2
4
x 10
v
P_mech
To Workspace
M_mot
To Workspace2
w_mot
To Workspace3
8
4
Used Electric Energy on 100km and resulting battery weight
• Most pure electric car
projects assume an
autonomy of 150 to
200km. This requires a
battery between 15 and
20kWhr
• Recent research activities
show that this would
result in a battery weight
up to 200kg
• Recently car
manufacturers propose
plug‐in hybrids to fulfill
daily travel distance up to
40km purely electric and
to assure longer distances
with an IC engine
Mmax = 1020Nm
NEFZ
Pendler ZH
City ZH
12.86 kWh
13.38 kWh
9.15 kWh
13.17 kWh
13.69 kWh
9.45 kWh
(75kW)
Mmax = 1100Nm
(45kW)
Sources:
• Status and Prospects for Zero
Emissions Vehicle Technology,
Report of the ARB Independent
Expert Panel 2007, p. 29
High Power / Medium Energy Battery Data
Useable charge and life cycles
Source: Plug‐In Hybrid Electric Vehicle Energy Storage System Design
T. Markel and A. Simpson, 2006
• For lightweight PHEV the required peak power might
make the use of higher power batteries necessary
• Longer pure electric driving makes larger discharge
necessary thus reducing the lifecycles
necessary,
• Cycle energy efficiency is important if plugged in for
overall system efficiency
Source: Status and Prospects for Zero Emissions Vehicle
Technology, Report of the ARB Independent Expert Panel 2007 , p. 33
5
Plug‐in Hybrid
NEFZ
Pendler ZH
• Lightweight Plugin‐Hybrid
High-Energy
High-Power
High-Energy
High-Power
High-Energy
High-Power
47.2 (69.5)kg
71.0 (106)kg
49.3 (72.6)kg
74.2 (111)kg
33.5 (49.5)kg
50.5 (75.5)kg
51kW
160kW
53kW
168kW
36kW
114kW
6.6 kWh
• 40 km Range (Battery
only)
City ZH
6.9 kWh
4.7 kWh
• 80% Battery Discharge
• Resulting Weight and Power
output on cell level
• Values in Bracket show
System weight and power
output
• Prius PHEV Demonstrator
requires higher battery weight
due to higher total car weight
• Increasing
I
i specific
ifi Energy
E
would actally keep battery
system weight below 100kg
Source:
• Status and Prospects for Zero Emissions
Vehicle Technology, Report of the ARB
Independent Expert Panel 2007 , p. 162
Plugin‐Hybrids?
Source: EPRI: Environmental Assessment of Plug‐In Hybrid Electric Vehicles
Volume 1: Nationwide Greenhouse Gas Emissions, 2007, p.7
• Annual and cumulative GHG emissions are reduced
significantly across each of the nine scenario
combinations.
• Annual GHG emissions reductions were significant
in every scenario combination of the study, reaching
a maximum reduction of 612 million metric tons in
2050 (High PHEV fleet penetration, Low electric
sector CO2 intensity case).
12
6
A winning combination for the future: PV+EV/PHEV!
source: PHOTON
Range achieved by the energy produced on 1 ha land
(the bar of the plug‐in‐hybrid vehicle is 7 times longer than shown here)
Î The PHEV (consumption 16 kWh/100 km) using solar energy produced by a PV installation on 1 ha drives 150 times
further than a car (consumption 6,5 l/ 100 km fuel equivalent) using bio‐ethanol extracted from grain produced on
one ha.
Workshop IEA Transportation IA Paris 2008
What is required?
Conclusions
•
•
•
•
•
The need for mobility is still growing, especially in emerging
countries like India and China. The findingg of new oil reserves on
the other hand is decreasing
A typical mobility profile ask for small daily trip distances, but
drivers like to be able to cover larger distances from time to time
Reduction in total curb weight and drive train power have the
biggest potential for energy consumption saving
Batteries for EV with a reasonable weight and price still limit the
distance to 100 ‐200km even for lightweight vehicles
Pl i hybrids
Plug‐in
h b id will
ill require
i b
battery
tt
packs
k with
ith a weight
i ht below
b l 80k
80kg
and bring the biggest overall benefit in energy reduction.
7
Chemistry Comparison
Some of the main electrochemical
technologies used today in
automotive applications include:
• Lead‐acid batteries: these have a
very low specific energy and
short cycle life.
• Nickel‐Cadmium: contain
cadmium and have a specific
energy close to that of lead‐acid.
• Nickel Metal Hydrid: Better
specific energy, but still too low.
Cycling capability is not good
enough, requiring cycling at low
DODs.
DODs
• Sodium battery (Zebra): need to
be kept at high temperature and
therefore need to be plugged in
when not in use.
• Lithium‐ion batteries: variety of
chemistries, some potentially
suitable for automotive
applications, but not all!
Source: Leclanché SA
Lithium Based Technologies
LiNiPO4
The anode of a
conventional Li‐ion
cell is made from
carbon the cathode is
carbon,
a metal oxide, and the
electrolyte is a lithium
salt in an organic
solvent.
The Voltage of the cell
depends on the
difference on the
reduction scale.
Material
Average Voltage
Gravimetric Capacity
LiCoO2
3.7 V
140 mAh/g
LiMnO2
4.0 V
100 mAh/g
LiFePO4
3.3 V
170 mAh/g
Li2FePO4F
3.6 V
115 mAh/g
LiFePO4
• Today safety is achieved through the
use of cathode that show greater
thermal stability, such as the olivine
group.
• The most used is of course the Iron
Phosphate cathode, but the
replacement of Fe by other metals
allows for higher Wh/kg values (up to
50%)
• The challenge today is finding a stable
electrolyte for these high voltage
electrodes.
8
Lithium Based Technologies
The anode of a conventional Li‐ion cell is made from carbon, the cathode is a metal oxide, and
the electrolyte is a lithium salt in an organic solvent.
However, organic solvents are easily decomposed on anodes during charging, thus preventing
battery activation. Nevertheless, when appropriate organic solvents are used for electrolytes, the
electrolytes are decomposed and form a solid electrolyte interphase (SEI) at first charge that is
electrically insulating and high Li‐ion conducting.
Today research is concentrating on new anode materials like Titanate (Li4Ti5O12) applied using
nanotechnology naon‐Titanate (Altairnano / nanosafe).
18
Basic characteristics of most common materials
Cathode materials
LiMnO2
Anode materials
Pros
Cons
Pros
Cons
High Power
Lower energy
Price
Mediumly safe
Fading at high °T
Rate limited at low
temperatures
Synthetic graphite
Good energy density
Low cost per kg
LiFePO4
High Power
Lower energy
Good safety
Lower voltage
Natural graphite
Low cost
Good at high °TT
Most proven
H d carbon
Hard
b
Low cost
Purification required
High rate capability
Rate limited at low
temperatures
Lower capacity
Sloping voltage
Higher costs
Thermally unstable
Higher irresversible capacity
moisture sensitive
No SEI
Low voltage
LiNiCoAlO2
Impedance rise at high
SOC
Li4Ti5O12
Low capacity density
Long life
Higher costs
9
Relative performance of various Lithium Chemistries
10
21
Titanate cell characteristics
Second generation Lithium Polymer
Titanate cells from LLi have several key
differentiating factors:
• extended temperature range: ‐40°C to
85°C
• very high cycle life: more than 8000
full cycles
• very low self‐discharge rate: less than
2% per month
• maximum safety due to lower nominal
voltage
• custom design
• high pressure resistivity: up to 600 bar
• high acceleration resistivity: 5000 g
Matrix of different cell configurations
Source: AABC 2008
11
23
Lithium‐sulfur and lithium‐air batteries
Lithium – Sulfur battery technology:
Whereas the lithium‐ion active material couple yields about 500 Wh/kg ideally, the lithium‐
sulfur active material couple is yielding 2500 Wh/kg. The practical amount that can be
extracted from that is approximately 500 to 550 Wh/kg, well over 2 times that of state of the
art lithium‐ion cells. In principle these cells will exceed all existing rechargeable chemistries in
all performance categories.
But the technology is still several years away, and there are still a lot of unanswered questions.
Lithium – air battery technology:
These batteries use lithium metal and air electrodes in a non‐aqueous electrolyte. Very similar
in there conception to zinc‐air batteries, they should reach a theoretical specific capacity of
5200 Wh/kg, resulting in an estimated practical specific capacity of 1700 Wh/kg.
Considerable work still needs to be done on this chemistry to obtain working cells, and many
limitations, such as rate capability, self discharge … will most probably not be overcome. These
systems could possibly be used in hybrid battery packs with lithium‐ion.
Safety of Lithium‐ion cells
• The cathode materials start
decomposing at temperatures around
200°C and upwards. As seen on the
previous graphs, NCA is the most
reactive, followed by Cobalt oxide and
Manganese spinel. The olivines show
the greatest stability.
• The anode also releases heat and
participates in the start of thermal
runaways. The previous graphs show
that this participation increases with the
amount of graphite present. Therefore
the graphite anode is also very critical in
large cells.
• On the other hand the titanate anode is
much less reactive,, due to the absence
of SEI. It also acts as an oxygen
absorber within the cell (oxygen that
can come from the cathode
decomposition), further stabilising the
system.
• For safety of large lithium ion cells, all
aspects of the cell design need to be
considered.
Source: Leclanché SA
Differential scanning calorimetry (DSC)
of fully charged electrodes
Source: ZSW, lithium mobile power 2007
Source: Argonne National Laboratories
12
Recycling
Toxco, US (Tesla Motors):
• Residual electrical energy is removed from
larger, more reactive batteries. If necessary
the batteries then begin Toxco’s patented
cryogenic
y g
p
process and are cooled to ‐325°F.
Lithium, although normally explosively
reactive at room temperature, is rendered
relatively inert at this temperature. The
batteries are then safely sheared/shredded
and the materials are separated. Metals
from the batteries are collected and sold.
The lithium components are separated and
converted to lithium carbonate for resale.
Hazardous electrolytes are neutralized to
form stable compounds
p
and residual p
plastic
casings and miscellaneous components are
recovered for appropriate recycling or
scrapping. If the batteries contain cobalt this
is also recovered for reuse.
BATREC, Switzerland
• http://www.batrec.ch
Lithium: Will there be enough?
[1] J. O. Besenhard and M. Winter. Advances in battery technology: Rechargeable magnesium
batteries and novel negative-electrode materials for lithium ion batteries. ChemPhysChem,
3 (2002) 155–159.
13
Battery Cost Today
• Battery Cost evaluation possible
for today technologies based on
high volume production.
Battery Cost in the future
Current data is based on a review of industry data and private correspondence [Miller 2007,
Anderman 2000, Anderman 2005]
Lithium‐Ion BEV cost projections (“Cost” = OEM cost
from battery manufacturer).
“high volume production” is defined as 100K vehicles/year
Source: AABC 2008
14
What is possible?
Conclusions
“ECUV” Electric City Urban Vehicle
Cooperation with Sun Yatsen University, Guanzhao China. Development Goal is a city
commuter car for 4 people and a top speed of 120km/h using advanced Chinese
Lithium Ion batteries
BFH TI: Development of an optimized IPM Motor and the control algorithm. Part of the
cooperation is also consulting work for the system conception as well as help for the
implementation of the electric drive train in China
15
Battery Management Systems
BFH Battery Management Systems
• Monitoring System (BMS) for
Lithium‐Ion and Lithium‐Polymer
batteries in series
• Monitoring of cell voltages,
temperatures and current
• Automatic cell balancing during
charge and discharge cycle
• Hardware overdischarge and
overcharge detection and
protection ( second protection)
• Hardware overcurrent detection
and protection
• Advanced SOC (State of Charge)
and SOH (State of Health)
calculations
• Calculation of internal cell
resistance
• Galvanic isolated CAN interface
providing battery information to
the host system
• PC Software available to display
and log battery data
16
2008 iZip Express
•
•
•
•
•
•
•
•
•
•
Base price: $2,999
Powertrain: 750‐watt DC
neodymium magnet motor;
36‐volt 18Ah lithium‐ion
battery back;
Dolphin Evo‐Drive;
Shimano 44/32/22T crank
and torque sensor;
27‐speed gear train;
on‐board charger
T speed:
Top
d 20‐plus
20 l mph
h
Range: 31‐62 miles per
charge, depending on
power setting
Net weight: 60 pounds
What happens really?
•Hybrid Cars will be introduced in
larger numbers from 2009
•Almost every car manufacturer
announces electric and cars for
2010/11
•Most big car maufactures announce
cooperation agreements with battery
manufacturers
•Forecast sees HEV as standard drive
train technology from 2025
•Plugin‐HEV
•Plugin
HEV will prepare the path for
battery EV‘s
17
Veranstaltungsreihe an der Berner Fachhochschule TI
Energiezukunft Schweiz…
Statt Schlagworte will die Veranstaltungsreihe «Energiezukunft Schweiz» konkrete Lösungsansätze aufzeigen.
Fachleute der Berner Fachhochschule, Departemente Technik und Informatik sowie Schweizerische Hochschule
für Landwirtschaft, und Spezialisten aus führenden Schweizer Unternehmen referieren und diskutieren über:
•
•
•
innovative Technologien in den Bereichen Energie und Verkehr
aktuelle Energieprojekte an der Berner Fachhochschule
Energietechnologie – ein wirtschaftlicher Erfolgsfaktor
Energie und Verkehr: Mobilität ohne Erdöl ‐ Schrecken oder Vision? Die
fossilen Kraftstoffe gehen zur Neige. Womit fahren wir übermorgen? Wie
werden die Autohersteller auf die Herausforderung reagieren?
24. Apr. 2008, Biel/Bienne. [Infos, Referate, Podcasts, Impressionen]
24. Face‐to‐Face‐Meeting: Energiezukunft Schweiz ‐ Wie weiter? Referat
von Dr. Rudolf Rechsteiner "Was kommt nach Öl, Gas und Atom?
Erneuerbare Energien ‐ die no‐Risk‐Strategie." mit folgendem
Podiumsgespräch.
13. Mai 2008, 15.30 ‐ 17.30 Uhr, Quellgasse 21, Biel/Bienne. [mehr]
Alle Referate online als Podcast / Animated Presentation
Neue Veranstaltungsreihe Forschung im Alltag Studienjahr 2008/2009
Thank you very much for your attention
Dr. Andrea Vezzini
Laboratory for Industrial Electronics
Berne University of Applied Sciences
Tf.: +41 32 321 63 72
Fax: +41 32 321 65 72
email: [email protected]
Internet: www.ti.bfh.ch
18

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