Don Siegel Mechanical Engineering Department University of Michigan
Outline 1. Energy storage: rationale for transportation and state of the art 2. Challenges 3. Tools: In situ diagnostics and predictive computational modeling 4. Batteries of the future
Well-to-Wheels (WTW) Analyses Reveals the amount of X [X = energy, CO 2, gasoline, $$, etc.] consumed in operating a vehicle, including production of fuel. 3 Source: Argonne National Labs
Emissions and Petroleum Use Vehicle electrification can lower GHG emissions and reduce petroleum use. 4 Source: Argonne National Labs
EVs: Then 1909 Baker EV: 60-100 mi range 1970s GM Electrovette EV: ~ 60 mi range http://www.wired.com/autopia/2010/03/jay-leno-1909- baker-electric 5
EVs: Now 2011 Nissan Leaf EV 24 kwh 2013 Ford Focus EV 23 kwh 6
Battery Chemistries vs. Time 5x improvement 130 years (Moore s Law: 3.8 x 1022) Baghdad battery 200 BC to 220 AD Voltaic pile 1800, Alessandro Volta Nature 451, 652 (2008).
Li-ion Batteries 101 Discharge Charge 8
Comparing Performance: Ragone Plot Annu. Rev. Chem. Biomol. Eng. 2010. 1:299 320
Killacycle 0-60 mph in less than 1 s 500+ HP http://youtu.be/3drpazci9m0
Challenges
Low Energy Density = Range Anxiety The driving range of battery electric vehicles is far below that of gasoline vehicles 12 Nature Materials 11, p12 (2012)
The cost model allows us to develop perspective regarding the relat contribution of various material and processing costs, for various s Cost Current cost of Li-ion batteries: $700-1000/kWh. U.S. DOE Cost target: $150/kWh Materials account for 60-70% of the final PHEV battery pack cost, with the cathode Materials account for 60-70% of active material contributing 15-30% the cost for a PHEV battery pack, with the cathode material contributing 15-30% Capex 6.9% Maintenance 2.9% Utility 2.1% Labor 12.3% BOP Materials 11.3% Illustrative Example Capital 5.5% Other Cell Materials 19.7% Anode Active Material 7.5% Cathode Active Material 23.4% Separator Material 8.5% Fraction of Process Process Formation and Aging 1 Anode Coating/Drying 1 Cathode Coating/Drying 1 Winding Cathode Mixing Anode Pressing Cathode Pressing BOP Tesla Packaging Roadster 53 kwh stored energy All Others 6801 18650-sized Li-ion cells *Value depends on cell design ~$50,000(?) for battery system Cell formation and aging, anode coating and drying, and winding much as 70% of the total proc Source: TIAX LLC, 2011 DOE Vehicle Technologies Merit Review
n, impurities, etc.). Furthermore, most available 2.2. Changes at the electrode/electrolyte inter ata concentrates on complete cells without the atf certain effects to either anode or cathode. In view Changes at the electrode/electrolyte interfac Degradation: Anode/electrolyte interface itations, this part of the study can summarise and to reactions of the anode with the electrolyt ly the dominant A viable ageing EV battery mechanisms must last of graphite for 10-15 years ered and bywithstand many researchers 1000+ of to cycles be the major so ing of/at the anode [15]. It is well known tha 14 J. Power Sources 147 (2005) 269 281
Safety A Setback for Electric Cars By BILL VLASIC and NICK BUNKLEY Published: November 28, 2011 DETROIT Even as they pour money into developing a range of electric vehicles, automakers have acknowledged that widespread sales of battery-powered models are years away. Now a federal investigation into the Chevrolet Volt could make the pitch for the electric cars that much tougher. General Motors said on Monday that it would offer free loaner cars to Volt owners worried about the safety of their vehicles, a move that underscored the fragile reputation of automobiles powered primarily by batteries and the growing consternation set off by the federal action. The National Highway Traffic Safety Administration on Friday opened a formal defect investigation into the Volt after two batteries caught fire as part of testing by regulators.
Diagnostics and Modeling
In-Situ TEM Nano Electrochemistry Si nanowires LiCoO 2 Al rod Si wafer Au ILE - Potentiostat + STM Tip Sample First working in-situ Li-ion cell inside a TEM Enables real time observations of electrochemistry process at atomic length scales Open cell using an ionic liquid electrolyte in the high vacuum of a TEM Huang et al., Science 330, 1515 (2010); Phys. Rev. Lett. 106, 248302 (2011)
Time scale molecules [7, 8] and to study crack formations and propagation Kinetic Monte Carlo (KMC) to model electrochemical reactions [9] and to study Multi-Scale the interfacial chemical Modeling reactions of Batteries phase field modeling (see, for example, Refs [10 13]) to study the mesoscopic transport of ionic species and to understand the various resistances at the Years Minutes Milliseconds Microseconds Nanoseconds Femtoseconds Battery Pack and Full Vehicle Full Cell Secondary Particle Crack Formation ( poly-crystal level ) Primary Particles (single crystal level ) Initial formation of defects (atomic level ) Increasing Computational Complexity Accelerated molecular dynamics Electronic structure Molecular dynamics Phase field Kinetic Monte Carlo Systems-level Simulations Micro-Macroscopic Simulations Increasing Model Complexity 10-15 10-12 10-9 10-6 10-3 1 Length scale (m) Figure 25.1 Multiscale and multiphysics models for batteries and electrochemical systems. Handbook of Battery Materials, 2 nd Ed.
Virtual High-Throughput Screening MRS Bulletin 35, 698, (2010).
Batteries of the Future
Li-air batteries exhibit high specific energies Specific energy densities of various electrochemical systems 300-400% vs. Li-ion 30-60% vs. Li-ion J. Phys. Chem. Lett. 1, 2193 (2010). 21 Li-air projected cost: $100/kWh - Johnson Controls presentation, Battery Congress 4/11/11 JES 159, 2193, R1 (2012).
Li-Air Cell 22 2Li + + O 2(g) + 2e Li 2 O 2 U o = 2.96 V 2Li + + ½ O 2(g) + 2e Li 2 O U o =
Nature Materials 11, p12 (2012) Challenges: Li-Air Battery
Electrolyte How Do Li-Air Catalysts Work? Catalysts lower overpotentials for both the discharge and charging Co 3 O 4 nanopillars Catalyst Li + Li + Li + O 2 Li + O 2 O 2 e - e - Porous carbon support Li 2 O 2 Energy Environ. Sci., 2011, 4, 4727 4734
Conclusion Efficient electrical energy storage is key to achieving viable electric vehicles Development of batteries with high capacity, long life, and low cost remains a challenge New experimental techniques are providing insight into battery performance limitations; computational methods are guiding the discovery of new chemistries Batteries with theoretical specific energies 10x today s cells are known, yet will likely need a decade of research to advance beyond the laboratory. djsiege@umich.edu
Appendix
27 Petroleum Use in the United States Transportation accounts for 2/3 of U.S. oil consumption Most oil consumption arises from light duty vehicles
U.S. Greenhouse Gas Emissions by Sector The transportation sector leads all U.S. end-use sectors in CO 2 emissions (33%) EIA data 28 Emissions parallel total vehicle miles traveled Number of vehicles worldwide is estimated to triple during 2000-2050
DOE Targets
Challenges: Li-Sulfur Battery Nature Materials 11, p12 (2012)
Monitoring & Controls Robust control strategies are needed to monitor battery health Tesla Battery Failures Make Bricking a Buzzword By BRADLEY BERMAN March 2, 2012 An uproar recently ignited on automotive blogs over a post about a Tesla Roadster whose battery needed replacement after its owner parked the car, low on charge and unplugged, for more than two months. The battery, which had fully discharged, could not be revived. While controversy has swirled around the incident with bloggers arguing about an owner s responsibility to keep the battery charged and the motivation in making the details public Tesla has confirmed basic facts about the situation. The crux of the matter was Tesla s denial of warranty coverage because the owner had not plugged in the car while it was parked, as specified in the owner s manual and other materials. A replacement battery from Tesla s Los Angeles service center was offered at around $40,000, according to a letter to the owner from Tesla s vice president for service, J. Joost de Vries.