Increasing Battery Potential: Electrochemical Controls Scott Moura Assistant Professor | eCAL Director University of California, Berkeley Satadru Dey, Hector Perez, Saehong Park, Dong Zhang UGBA 193B | UC Berkeley Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 1
eCAL Battery Controls Team @ UC Berkeley Current Researchers Prof. Scott Moura | Dr. Satadru Dey | Dr. Hector Perez | Saehong Park | Dong Zhang Supporting Researchers Prof. Xiaosong Hu | Defne Gun | Changfu Zou | Zach Gima | Preet Gill Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 2
A Golden Era Keyword Search: Battery Systems and Control 3500 3000 No. of Publications 2500 2000 1500 1000 500 0 1985 1990 1995 2000 2005 2010 2015 Year Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 3
Cost Parity with ICEs is Reachable! Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 4
Future Battery R&D Study by U.S. Dept. of Energy Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 5
U.S. Dept of Energy Battery R&D Budget Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 6
Pathways to Future Batteries Two Solutions Design better batteries Make current batteries better (materials science & chemistry) (estimation and control) Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 7
Outline BACKGROUND & BATTERY ELECTROCHEMISTRY FUNDAMENTALS 1 ESTIMATION AND CONTROL PROBLEM STATEMENTS 2 ELECTROCHEMICAL MODEL 3 STATE ESTIMATION 4 CONSTRAINED OPTIMAL CONTROL 5 SUMMARY AND OPPORTUNITIES 6 Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 8
History Luigi Galvani, 1737-1798, Experiments on frog legs Physicist, Bologna, Italy “Animal electricity” Dubbed “galvanism” First foray into electrophysiology Alessandro Volta, 1745-1827 Voltaic Pile Monument to Volta in Como Physicist, Como, Italy Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 9
Comparison of Lithium Ion (Cathode) Chemistries Lithium Manganese Oxide Lithium Cobalt Oxide Lithium Nickel Manganese (LiMn 2 O 4 ) (LiCO 2 ) Cobalt Oxide (LiNiMnCoO 2 ) Lithium Nickel Cobalt Lithium Titanate Lithium Iron Phosphate Aluminum Oxide (LiNiCoAlO 2 ) (Li4Ti 5 O 12 ) (LiFePO 4 ) Source: http://batteryuniversity.com/learn/article/types_of_lithium_ion Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 10
Energy Density Source: Katherine Harry & Nitash Balsara, UC Berkeley Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 11
Outline BACKGROUND & BATTERY ELECTROCHEMISTRY FUNDAMENTALS 1 ESTIMATION AND CONTROL PROBLEM STATEMENTS 2 ELECTROCHEMICAL MODEL 3 STATE ESTIMATION 4 CONSTRAINED OPTIMAL CONTROL 5 SUMMARY AND OPPORTUNITIES 6 Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 12
Battery Models Equivalent Circuit Model (a) OCV-R Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 13
Battery Models Equivalent Circuit Model (a) OCV-R (b) OCV-R-RC (c) Impedance Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 13
Battery Models Equivalent Circuit Model Electrochemical Model (a) OCV-R - - sep sep + + 0 L 0 L L 0 x (b) OCV-R-RC Cathode Anode Separator c s - ( r ) c s + ( r ) e - Li + e - c ss - c ss + (c) Impedance r r c e ( x ) Li x C 6 Li 1-x MO 2 Electrolyte Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 13
Safely Operate Batteries at their Physical Limits Electrochemical model-based limits of operation ECM-based limits of operation ECM-based limits of operation Terminal Voltage Overpotential Surface concentration Cell Current Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 14
What are we protecting against? Electrolyte Oxidation Cobalt Oxide Electrolyte Stability Potential (E) vs. Li Electrode “Breathing” (Stress/Cracking) Electrolyte Reduction (Kinetically limited) Graphite Lithium Plating (Dendrites) Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 15
Operational Limits Electrolyte Oxidation Cobalt Oxide Electrolyte Stability Potential (E) vs. Li Electrode “Breathing” (Stress/Cracking) Electrolyte Reduction (Kinetically limited) Graphite Lithium Plating (Dendrites) Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 16
Operational Limits Electrolyte Oxidation Cobalt Oxide Electrolyte Stability Potential (E) vs. Li Electrode “Breathing” (Stress/Cracking) Electrolyte Reduction (Kinetically limited) Graphite Lithium Plating (Dendrites) Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 16
Operational Limits Electrolyte Oxidation Cobalt Oxide Electrolyte Stability Potential (E) vs. Li Electrode “Breathing” (Stress/Cracking) Electrolyte Reduction (Kinetically limited) Graphite Lithium Plating (Dendrites) Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 16
Operational Limits Electrolyte Oxidation Cobalt Oxide Electrolyte Stability Potential (E) vs. Li Electrode “Breathing” (Stress/Cracking) Electrolyte Reduction (Kinetically limited) Graphite Lithium Plating (Dendrites) Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 16
Operational Limits Electrolyte Oxidation Cobalt Oxide Electrolyte Stability Potential (E) vs. Li Electrode “Breathing” (Stress/Cracking) Electrolyte Reduction (Kinetically limited) Graphite Lithium Plating (Dendrites) Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 16
Removing the blinders What we are protecting against What we currently monitor Electrolyte oxidation Temperature Inside every cell / reduction Groups of cells Voltage Lithium Plating (Dendrites) Current Electrode stress/cracking Internal cell defects Thermal runaway Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 17
ElectroChemical Controller (ECC) Measurements I r ( t ) V ( t ), T ( t ) I ( t ) EChem-based Battery Cell Controller + Innovations _ EChem-based Estimated ^ ^ x ( t ), θ ( t ) State/Param States & Params ^ ^ Estimator V ( t ), T ( t ) ElectroChemical Controller (ECC) Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 18
ElectroChemical Controller (ECC) The State Estimation Problem Measurements I r ( t ) I ( t ) V ( t ), T ( t ) EChem-based Battery Cell Controller + Innovations _ EChem-based Estimated ^ ^ x ( t ), θ ( t ) States & Params State/Param ^ ^ V ( t ), T ( t ) Estimator ElectroChemical Controller (ECC) The State (a.k.a. SOC) Estimation Problem Given measurements of current I ( t ) , voltage V ( t ) , and temperature T ( t ) , estimate the electrochemical states of interest. Exs: bulk solid phase Li concentration (state-of-charge) surface solid phase Li concentration (state-of-power) Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 19
ElectroChemical Controller (ECC) The Parameter Estimation Problem Measurements I r ( t ) V ( t ), T ( t ) I ( t ) EChem-based Battery Cell Controller + Innovations _ EChem-based Estimated ^ ^ x ( t ), θ ( t ) States & Params State/Param ^ ^ V ( t ), T ( t ) Estimator ElectroChemical Controller (ECC) The Parameter (a.k.a. SOH) Estimation Problem Given measurements of current I ( t ) , voltage V ( t ) , and temperature T ( t ) , estimate uncertain parameters related to SOH. Exs: cyclable lithium (capacity fade) volume fraction (capacity fade) solid-electrolyte interface resistance (power fade) Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 20
ElectroChemical Controller (ECC) The Constrained Control Problem Measurements I r ( t ) V ( t ), T ( t ) I ( t ) EChem-based Battery Cell Controller + Innovations _ EChem-based Estimated ^ ^ x ( t ), θ ( t ) States & Params State/Param ^ ^ Estimator V ( t ), T ( t ) ElectroChemical Controller (ECC) The Constrained Control Problem Given measurements of current I ( t ) , voltage V ( t ) , and temperature T ( t ) , control current such that critical electrochemical variables are maintained within safe operating constraints. Exs: saturation/depletion of solid phase and electrolyte phase side-reaction overpotentials internal temperature Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 21
Outline BACKGROUND & BATTERY ELECTROCHEMISTRY FUNDAMENTALS 1 ESTIMATION AND CONTROL PROBLEM STATEMENTS 2 ELECTROCHEMICAL MODEL 3 STATE ESTIMATION 4 CONSTRAINED OPTIMAL CONTROL 5 SUMMARY AND OPPORTUNITIES 6 Scott Moura | UC Berkeley Battery Controls October 23, 2016 | Slide 22
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