Ultracapacitors Microelectronics High-Voltage Capacitors 26 April 2007 Energy Storage Technology, Markets and Applications, Ultracapacitor’s in Combination with Lithium-ion Dr. John M. Miller Maxwell Technologies, Inc IEEE Rock River Valley, IL, Section
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Ultracapacitors Microelectronics High-Voltage Capacitors 26 April 2007
Energy Storage Technology, Markets and Applications,
Ultracapacitors are becoming widely accepted in the energy storage industry in both standalone and in combination with batteries. Standalone applications, once niche, are now rapidly expanding as the technical and economic benefits of this power dense component become more widely understood. Combination examples continue toproliferate, primarily in battery electric and hybrid electric commercial transportation segments such as transit buses and trains. The ultracapacitor offers a fast energy buffer to advanced chemistry energy reservoirs such as nickel metal hydride and lithium batteries and offer an opportunity for truly energy optimized battery systems. Thispresentation will discuss trends in energy storage systems, advanced chemistry batteries such as nickel-hydrogen and lithium-ion and why such components would benefit from working in combination with carbon capacitors.
• A single household with one vehicle consumes the equivalent of 5,000 kg of gasoline/year.• = 216 GJ of energy/household/year • 100M households consume 21.6 EJ
• U.S. energy supply breakdown (in Quad ~=EJ)• Coal…………22.6 • Gas….………23.1 • Oil……………40.6 • Nuclear……….8.2• Hydro…………2.7• Alternative……3.6
• Rising global awareness that we need more carbon free energy sources:• No viable non-carbon alternative can meet the energy demands of
1010 people in the near future, 2050.• Globally, 6.3B people, 12.8 TW (U.S. @ 25% =3.3 TW) now 28
TW in 2050• The right people are working on this, but have not been heard.
• Climate change is now positively linked to anthropogenic activities with very high confidence.• Net effect of human activity since 1750 has been one of warming.
• Hydrogen economy is a myth, will never happen! Yes, for niche applications.• Electricity from fuel cell costs 4x grid delivered electricity• It would take 400 Gen IV nuclear plants to equal hybridizing trans.
• Electricity is the energy carrier of the future.
What is an Ultracapacitor?• Invented in U.S. by Robert A. Rightmire of SOHIO
company.• U.S. Patent 3,288,641 “ELECTRICAL ENERGY STORAGE APPARATUS:
This invention relates generally to the utilization of an electrostatic field across the interphase boundary between an electron conductor and an ion conductor to promote the storage of energy by ionic adsorption at the interphase boundary.”Nov. 29, 1966
• Electrochemical storage batteries and capacitors have been in existence for over 200 years (Baghdad battery BC), Volta “pile” 1800, to Ben Franklin 1848 who coined the term “battery”.
• Battery stores energy in chemical bonds that follow reduction-oxidation (REDOX) reactions. Mass transfer is involved.
• Capacitors store energy in electrostatic fields between ions in solution and a material. No mass transfer involved – hence no electrochemcial wearout.
Source: Joel Schindall, “Concept and Status of Nano-sculpted Capacitor Battery,” Presented at 16th Annual Seminar on Double Layer Capacitors and Hybrid Energy Storage Devices December 4-6, Deerfield Beach, Florida
Ultracapacitor Material and Electrode• On cost of ultracapacitors is dominated
by carbon.• Raw material – coconut shells =>
• Carbon is the cost driver • Resin based – high purity, high mat’l costs• Natural product based – (coconut, wood,
coal, peat, etc.) lower cost, higher impurities
Grind
Activated carbon powderActivated carbon powder
Activation
Electrodefabrication
CoatingRolling/Kneading/Pasting
Source: Prof. Katsuhiko Naoi, Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology,Recent Advances in Capacitors and Hybrid Power Sources in Japan, presented to DOE Basic Energy Sciences Wkshp, 3-4 March 2007
• Pore sizes must be controlled to provide access for both ion species. AC
Conducting agents( KB, AB )
Al
Adsorped ions(anions, cations)
Solvents
Micro pores( < 2 nm)
Meso pores(2 ~ 50 nm )
Macro pores( > 50 nm )
CC
binder( PTFE )
Electrode for EDLC
Inset from: Prof. Katsuhiko Naoi, Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology,Recent Advances in Capacitors and Hybrid Power Sources in Japan,presented to DOE Basic Energy Sciences Wkshp, 3-4 March 2007
The Compact Layer• Evolution of electrochemical capacitor modeling theory:
• Helmholtz
• Gouy-Chapman
• Stern’s model
Helmholtz model:ε~78 for organic electrolyted~ 0.2nm for solvent moleculeC 340 uF/cm2, is 10x experimentC is not voltage dependent.
Known as the diffuseModel. Works well at low potential, over estimates C for higher potentials.
Improves on Gouy-Chapman by retaining Helmholtz compact layer of adsorbed ions and Gouy-Chapman diffuse layer of point charges, but modifies situation to include physical size to the ions.
Ultracapacitor Example• The model looks simple – but it could be tricky.• Consider:
• Carbon at 75 F/g (i.e., Farads of capacity per gram of carbon)• Total mass of carbon per device = 187g (as example)• Therefore: 75 (F/g)x 187g = 14,025 F (this is a huge number!)
• However:• Each unit consists of a pair of electrodes (1/2 total mass each)• AND 2 each electrode Double Layer Capacitors are in series.
• The Maxwell moment matched equivalent circuit model is used in this work.• Capacitance is SOC dependent: C(U) = Co + kuU• ESR = ESR(T,I) = Relectronic + Rionic
Ultracapacitors: Where to Next?• Fundamental need - understand solvent-salt structure and physical properties.• Performance - create a fundamental understanding of link between device
performance and bulk/interfacial molecular interactions.
• Develop new EDLC materials and architectures that will dramatically boost energy and power.
• Electrode materials with controlled pore size and surface area deposited in ordered geometries with intimate contact to current collectors
Excerpted from: Bruce Dunn, Yury Gogotri, Plenary Closing Session Remarks, DOE Basic Research Needs Workshop on Electrical Energy Storage, Washington, D.C., 4 April 2007
• Very diverse range of markets• Aerospace, industrial, transportation, utility, consumer electronics
• Energy Storage System (ESS) attributes• Regenerative braking and energy recuperation in bus, train, subway, etc. • Cold engine starting aide for standby power, UPS, truck, bus…• Burst power for wind turbine blade pitch systems, shipyard cranes,
material handling trucks, etc. • Bridge power for telecommunications, medical office, etc.• Voltage sag compensators for utility interconnects to restore voltage and to
smooth distribution voltage• Consumer applications in everything from camera’s, car audio, and cell
phones to fast heat coffee makers.• Virtually any application that demands high peak power.
Value today is in transportation, industrial and consumerTarget is the automotive market Hybrid drive trains, board net stabilization, distributed power
Fork lift, cranes
ApplicationMarket
AMR
UPS/Power quality
Telecom
Digital cameras, PDA’s, laptop, mobile phonesConsumer
• Vehicle applications for ultracapacitors are now beginning to emerge as ultracapacitor costs decrease below 1c/F.
• Vehicle PowerNet stabilization example is Alcoa-Maxwell APM• Micro-hybrid energy recuperation again, Alcoa-Maxwell APM• Strong hybrid propulsion and supporting subsystems
100F to 350F “C” and “D” sizeElectric steering, brakes, audioPowerNet stabilization
500F to 1000FBelt ISG, engine cold cranking,Micro hybrid recuperation
1000F to 4000F large cellsCI engine cold startingStrong hybrid energy storage
Challenges for Lithium that Ultracapacitors Benefit
• A value proposition must be made for the combination of ultracapacitors and lithium battery technology:• For a viable business case model, and• For application in mild, strong, and plug-in hybrids
Difficult algorithm for SOC, SOHEase of SOC and SOH monitoringLithium δSOC<50%Very wide SOC windowSensitive to rapid chg/dchgAbuse and rapid discharge tolerantEnergy mgm’t: Cell equalizationEnergy mgm’t: cell over voltageC<100 (at best)High power: C-rates >1000Moderate eff: 95% to 85%High efficiency: 98% to 92%-20oC to +40oC-40oC to +65oCElectrochemical, Faradaic deviceElectrostatic, non-Faradiac
• Comparison of different cathode materials:(Vergleich unterschiedlicher Kathodenmarterialien)
Source: Andreas Jossen, “Lithium Akkumulatoren, -Grundlagen, aktuelle Entwicklungen, Einsatz –”Energiespeicher für Bordnetze und Antriebssysteme, Haus der Technik, Essen 14.02.2007
Lithium Cell Charge/Discharge Mgm’t• Charge and discharge rates must be managed in lithium.
Sicherheitsmanagement (Safety and security)
Source: Andreas Jossen, “Lithium Akkumulatoren, -Grundlagen, aktuelle Entwicklungen, Einsatz –”Energiespeicher für Bordnetze und Antriebssysteme, Haus der Technik, Essen 14.02.2007
Active circuit protectionPassive circuit protectionPassive cell component
Over chargeUnder chargeShort circuitOver temperature
Source: Tien Duong, “Research Needs: A Transportation Perspective – Applied Problems Can Be Addressed in a Fundamental Way,”Presented to Workshop on Basic Research Needs for Electrical Energy Storage, 2 April 2007, Washington, D.C.
• The fast buffer and power cache branch must match or exceed the efficiency of lithium only:• Much higher matched load power than battery only• Far faster power delivery = low time constant of ultracap• High efficiency at higher power levels from ultracap
Reference: Potential Ultracapacitor Roles for Hybrid Electric Vehicles Supercapacitor Seminar, 12/10/03Matthew Zolot, Tony Markel, Keith Wipke, and Ahmad Pesaran National Renewable Energy Laboratory
• Drive cycle determines peak charge and discharge power
cmx
dmx
dmxmnid
cmxmxic
PPr
RPUUUU
CQU
RPUUUU
=
−+==
=
++==
421
21
421
21
200
0
200
Pdmx
Pcmx
Uc(t)Umx
Uo
Umn
Ultracapacitor Voltage Swing
δSOCchg
δSOCdchg mnmx
mnmx
UrUUrUU
++
=22
0
Set initial state of charge (Uo) of the ultracapto match voltage swing (Pdmx/Pcmx)
Ref: Mark W. Verbrugge, Ping Liu, “Analytic Solutions and Experimental Data for Cyclic Voltammetry and Constant Power Operation of Capacitors Consistent with HEV Applications,” Journal of the Electrochemical Society, 153 (6) A1237-A1245 (200), pgs A1237 – A1245
• Ultracapacitor energy flows controlled via energy management strategy to minimize battery cycling• Dc-dc converter efficiency at 96%• Ultracap efficiency must remain >95%• Converter plus ultracapacitor branch should maintain >92%
• Relative to matched load: 0.4PML for 1s, 0.25PML for 2s, 0.1PML for 8s
Batt
DLC"ultracapacitor"
PowerElectronicConverter
Active Parallel HESSCP Efficiency 3000F UC (0.1, 0.25, 0.4Pml)
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00Time, s
UPS demandsReliability for power back-up’sGraceful power downBackup power in emergency situationsShort term bridge power Short-term power as the transition is made to backup generation power
230 V, 50 HzDC Link 24 V Pb Battery BOOSTCAPTechnology 2*12 V, 7 Ah 10*650 FVolume [l] 2 2Weight [kg] 5 2Backup time 6 min 10 sLifetime [y] 2 10
• Power flows are computed for a selected engine control strategy:• Engine strategy is fixed for both moderate and aggressive drive cycles• Energy management strategy of battery + ultracapacitor
• Battery supports auxiliary electrical loads: base + electric steering + eA/C• Ultracapacitor is the focal point of driveline power flows• Ultracapacitor energy is circulated to maintain battery per EMS strategy
Atkinson cycle I4110 kW with torsion damper
Chain drive of HSD replacedWith gear drive train
Est. 4.05:1 final driveIPM GeneratorMG1 est. 30 kW
• Tesla and Phoenix Motors are pioneering a new wave of electrics.• Roadster @ $92,000 each (381 sold)• 1180 kg (394kg battery)• Tz60 < 4s• MG1 185kW into 2spd transmission• Vwot = 210 kph• Battery: 400 km AER, 3.5h recharg• 200,000km life (5 yrs)