HEV, PHEV and EV Batteries ECEN 2060
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HEV, PHEV and EV Batteries
ECEN 2060
Batteries for HEV, PHEV and EVB tt t• Battery types NiMH Li-Ion (many variations)
• Technology Chemistry Electrical characteristics
• Key parameters Energy density [Wh/kg] and [Wh/l], and power density [W/kg] Life: # of charge/discharge cycles as a function of depth of discharge Life: # of charge/discharge cycles as a function of depth of discharge,
i.e. the SOC window (SOCmax SOCmin) Safety Cost [$/kWh]Cost [$/kWh]
• Other topics (not covered here) Construction of battery packs, the need for cell or module balancing
Battery charging from the AC grid (for PHEV or EV)
2ECEN2060
Battery charging from the AC grid (for PHEV or EV)
Reminder: Deep-discharge Lead-Acid batteries for stand-alone PV systems
+
Lead dioxidePbO2
Porous leadPb
Sulfuric acidH2SO4 + H2O 1.685 eV0.356 eV
• Open-circuit cell voltage (Nernst eq): 1.685V + 0.356V + Vt ln(electr.conc/1 mol)• SOC directly determined by acid concentration (6 mol at 100%, 2 mol at 0%)• Capacity [Ah] depends on rate of discharge (Peukert’s law)
Energy efficiency: 75%• Energy efficiency: 75%• Energy density: 30-40 Wh/kg, 60-75 Wh/l• Cost: $(0.1-0.2)/Wh Life cycles (DOD)
HEV requirement: 10-15 years
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Battery cycle life comparison
4ECEN2060
Nickel-Metal Hydride: NiMH
+
Nickel oxyhydroxideNiOOH
Metal alloyMH
MH + OH > M + H2O + e-
0.83 eV NiOOH + H2O + e > Ni(OH)2 + OH
Potassiumhydroxide
KOH + H2O0.52 eV
• Open-circuit cell voltage: 0.83V + 0.52V + Vt ln(electr.conc/1 mol) 1.4 V• SOC directly determined by electrolyte concentration (6 mol at 100%)• Energy efficiency: 65-75%
Energy density: 70 Wh/kg 170 Wh/l• Energy density: 70 Wh/kg, 170 Wh/l• Cost: $(0.5-1)/Wh
5ECEN2060
Example: Prius battery19.6mm(W)×106mm(H)×285mm(L)
NiMH Module6-cell (7.2 V) NiMH modules, 6.5 Ah at C/2
http://www.peve.jp/e/hevjyusi.html
( )46 Wh/kg1.3 kW/kg
Battery pack28 modulesVDC = 201.6 VEbat = 1.3 kWhPack weight: 30 kgSOC = 35%SOCmin = 35%SOCmax = 75%$3K retail replacement cost
6ECEN2060
Lithium-Ion: Li-Ion
+
Lithium cobalt oxide
Carbon compoundgraphite
LiPF6 Li-Ion cell in cell-phone
• Nominal cell voltage: 3.6 V• A separator (e.g. microporous polyethylen membrane) is required• Energy efficiency: 95%• Many chemistry variations• Energy density: 150-200 Wh/kg, 250-500 Wh/l• Cost: currently about $(0.7-1.5)/Wh
7ECEN2060
Lithium-Ion Chemistry
8ECEN2060
A. Pesaran (NREL), “Battery Choices for Different Plug-in HEV Configurations,” Plug-in HEV Forum, July 12, 2006
Comparison of Battery Technologies
Many competing technologies, no clear winners
Battery System Example
+ +nll
Conventional Battery System
A123 Systems (www.a123systems.com)automotive battery pack DC bus
DC-DCconverter
BatteryManagementSystem (BMS) Vbat
_
VDC
_
Electric drivepropulsioncomponents
cells(+protection)
inseries
automotive battery packLiFePO4 cells in series
Control bus Vehiclecontroller
• Battery management system (BMS):Battery management system (BMS): cell balancing
Vehicle Costs (NREL analysis)Projected Retail Powertrain Costs - Midsize Sedans
1) including manufacturer and dealer markups2) all component costs assume projected status
$18 000$663
$663$14,000
$16,000
$18,000charger/plugbatterymotor/invertertransmission
i
$5,117
$8,433
$663
$10,000
$12,000
engine
$1,998
$1 992 $2 004 $2 020
$2,079 $2,407 $2,454
$2,433
$4 000
$6,000
$8,000
$4,005$2,865 $2,919 $3,002
$1,992 $2,004 $2,020
$-
$2,000
$4,000
CV HEV PHEV20 PHEV40CV HEV PHEV20 PHEV40
Vehicle Cost Analysis (NREL)
Cumulative Vehicle plus Energy (Fuel/Elec.) Costs
$60,000
CV
Cumulative Vehicle plus Energy (Fuel/Elec.) Costs
$60,000
CV
Cumulative Vehicle plus Energy (Fuel/Elec.) Costs
$60,000
CV
$40,000
$50,000
$)
CVHEVPHEV20PHEV40
$40,000
$50,000
$)
CVHEVPHEV20PHEV40
$40,000
$50,000
$)
CVHEVPHEV20PHEV40
$30,000
$ ,
lativ
e co
st (2
006
$2 41/ l (2005 )
$30,000
$ ,
lativ
e co
st (2
006
$3 00/ l (t d )
$30,000
$ ,
lativ
e co
st (2
006
A ti $4 00/ l
$10,000
$20,000Cum
u $2.41/gal. (2005 avg)
$10,000
$20,000Cum
u $3.00/gal. (today)
$10,000
$20,000Cum
u Assumption: $4.00/gal.
$-0 5 10 15
Time after purchase (years)
$-0 5 10 15
Time after purchase (years)
$-0 5 10 15
Time after purchase (years)Time after purchase (years)Time after purchase (years)Time after purchase (years)
T. Markel and A. Simpson (NREL), “Cost-Benefit Analysis of Plug-In Hybrid Electric Vehicle Technology,” WEVA 2006
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