Transcript heat_ppt
RND Center for Hybrid Energy Sources Electro-Thermal Analysis of Lithium Ion Batteries: Experimental and Numerical study Gad A. Pinhasi The Israeli Fuel Cell and Batteries Center (IFCBC) Conference 26 January 2011, Tel Aviv University 1 Outline • The Objective • The Project • Background – Internal Resistance – Heat Generation • The Study • Experimental Setup – Calorimeter • Models – Lumped heat model – CFC model • Results – Cell – Battery – Pack 4 • Conclusions • Summery 2 The Objective • Thermal Analysis and Design of a Large Battery Pack. • To evaluate the heat generation and temperature field under various electrical loads and design specifications. – Safety: Thermal Runaway – Max. Temperature restriction: – “Passive cooling” solutions 3 The Project • Evaluation of Heat Generation: – Source term – Experimentally • Calculation of the Temperature Field – Numerically • Cell, Battery, Packs : 4, 92 4 Cell, Battery and Packs Type Cell Battery Pack 4 ICR18650 Samsung MR-2791 YT-600 24 cells 4 bat 91(+1) bat 4S×6P 4P 7S×13P Voltage: [V] 3.7 16.8 16.8 Capacity: [Ahr] 2.6 14.4 57.6 Discharge currents [A] 0.2, 0.4, 1 3, 4, 8 32 Pack 92 5 Introduction • Evaluation of Heat Generation – Experimentally • Calculation of the temperature field – Numerically • Model Approaches • Thermal characterization • Battery Internal 6 Model Approaches • Fundamental models • physical foundations principles – Transport Phenomena • Phenomenological models • Equivalent circuit models 7 Thermal characterization • The heat produced due to: • Joule heat of the electrical resistance • Polarization heat • Reaction heat qgen qJ qp qr VOC qgen iVOC V iT T – initially exothermic during discharge – reversible 8 Battery Internal Resistance • The cell voltage under load is : – Open circuit voltage – Internal Ohmic resistance – “Concentration polarization” – “Charge transfer polarization” V VOC diff ch,tr iRi • Methods for Determining the Internal Resistance – – – – Ohm’s Law Joule’s Law AC Resistance Electrochemical Impedance Spectroscopy (EIS) 9 Internal Resistance Dependence • Temperature – Decreasing with Temperature • State of Charge (SoC) • State of Health (SoH) Yurkovich et al. (2009) 10 Internal Resistance and Heat Generation • Joule heat of the electrical resistance • Open circuit voltage V0 V Rel i 12 40 0.6 20 Temperature-Water El. Potential 0.5 8 0.4 El. Resistance:R0=0.176 W Heat Electric Resistance 6 0.3 4 0.2 2 0.1 0 0 0 20 40 60 80 Time [min] 100 120 140 36 34 Temperature [C] 10 Electric Resistance [W] Heat [W] 38 New Battery Discharge Current: 8 A Water: 1.2 liter 19 18 Initial voltage 32 17 Start Load 16 30 15 28 14 26 13 24 22 12 20 11 18 10 0 20 40 60 80 Time [min] 100 120 140 11 Electric Potential [Volt] q R 2 i The Study: Experimental and Numerical Temperature-oil 6 Temperature-battery Temperature-room 100 5 80 4 3 40 2 Temperature [C] 40 60 19 El. Potential Potential [Volt] Temperature [C] 45 20 Battery 4 Discharge Current: 8 A oil: 2 kg 18 Initial voltage 17 16 Start Load 35 15 30 14 13 25 20 1 Temperature Potential 12 20 11 0 0 0 20 40 60 Time (min) 80 100 120 15 0 20 40 60 80 Time [min] 100 12 120 10 Electric Potential [Volt] 50 120 Experimental Setup Dewar: Calorimeter FLUKE: Data Acquisition Liquid Bath Cell/ Battery/ Pack Charge/ Load Charge Load Silicone Fluid Dow Corning DC-200/100 cSt Temperature Data logger 13 Calorimeter: • Batch / Continuous Flow (SHC) Calorimeter dT C p w Tw.out Tw.in Ws qgen mCp i i m dt i Tw,in Tw,out Toil,in 14 Numerical Study: Tools • Computational Fluid Dynamics (CFD) • Partial differential equations (PDEs) solvers: – Fluid Mechanics – Heat Transfer – Mass Transfer • (Diffusion) • Chemical reactions • COMSOL Multiphysics – Batteries & Fuel Cells Module • ANSYS – CFX – FLUENT 15 The Lumped Model • Cells mCp1 dT1 V1q AU 12 T1 T2 • Heat Transfer Mechanisms dt • Battery Medium mCp2 dT2 AU 12T1 T2 AU 23T2 T3 dt • Pack Medium mCp3 dT3 AU 23T2 T3 AU 3 T3 T T T1 Cell T3 T q 24 2 q”’ U3 U23 U12 ” Battery ’ 91 dt 16 Results • Cell – Temperature history – Heat Generation and SOC • Battery • The Pack • Electrical resistance – Open-circuit voltage – Heat Generation 17 Samsung 18650 • ICR18650-26C 2600m Li-ion 3.7v Battery • Brand :Samsung • Nominal voltage : 3.7V • Capacity: 2.6Ahr • Size 18mm x 65.0mm • Weight : 48g/pcs • Made in JAPAN 18 Cell Heat Generation and SOC 2.6A 1A 4 4 12 3.5 3 9 2 6 1.5 1 3 Heat Electric Power 9 2.5 Heat [W] 2.5 Electric Power [W] 3 Heat Electric Power 2 6 1.5 1 3 0.5 0.5 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 1-SOC 0.7 0.8 0.9 1 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 1-SOC 0.7 0.8 0.9 1 19 Electric Power [W] 3.5 Heat [W] 12 Pack 4 • YT-600 • 4 Batteries 2791 • 4P • Voltage: 16.8 Volts • Capacity :57.6Ahr 20 70 20 65 19 18 55 17 Initial voltage 50 16 Start Load 45 15 40 14 35 13 30 12 25 11 20 20 40 60 Time [min] 80 100 300 Heat Electric Power 250 Heat [W] 120 600 zeros 400 150 300 100 200 50 100 0 0 0 20 40 60 Time [min] 80 100 120 • Current: 32A • Temperature • Electrical voltage 500 200 Pack 4 – Battery inside – Battery Gap – Surrounding water 10 0 Electric Power [W] Temperature [C] 60 Package 4 Discharge Current: 32A oil: Electric Potential [Volt] Temperature-oil battery Temperature-oil pack Temperature-water tank El. Potential • Electrical Power • Heat Power 21 Pack 4: Simulation • Experiment vs. Simulation • Medium Effect: – air/oil 22 Experiment vs. Simulation 60 Package 4 Discharge Current: 32A oil: 55 Temperature [C] 50 Points: Battery inside Battery Gap Experiment 45 Simulation 40 35 Temperature-oil battery Temperature-oil pack 30 Temperature-water tank Temperature-oil battery-calculated 25 0.6W/cell Temperature-oil pack-calculated 20 0 20 40 60 Time [min] 80 100 120 23 Experiment vs. Simple model 60 Package 4 Discharge Current: 32A oil: 55 Temperature [C] 50 45 40 35 Points: Battery inside Battery Gap Temperature-oil battery Temperature-oil pack 30 Temperature-water tank Temperature-oil battery-calculated 25 Temperature-oil pack-calculated 20 0 20 40 60 Time [min] 80 100 120 Temperature [C] 80 TCell TBat TPack 60 0.6W/cell 40 20 100 0 20 40 60 time [min] 80 100 120 24 Pack 4: Medium Effect :32A 100min Tmax :51ºC Oil • Tmax :96ºC Air • 25 Summary • The heat generation and temperature field for battery packs were evaluated theoretically and experimentally • Internal resistance of a cell was determined by current step methods and thermal loss methods. • Future Work: – Heat generation Correlation – Dynamic models – Fundamental models 26 People • Dr. Gad Pinhasi – Department of Chemical Engineering and Biotechnology • Dr. Alon Kuperman – Department of Electrical Engineering • Neria Roth – (M.Sc. Student) Experimental Study • Itshak Shtainbach – (M.Sc. Student) Numerical Study 27 Acknowledgment The research is supported by the ISRAEL Ministry of Defense : MAFAT 29 30 Conferences Roth, N., Shtainbach, T., Kuperman, A. and Pinhasi, G.A., "Electro-thermal Analysis of Lithium Ion Batteries: Experimental and Numerical study”, 1. The 31st Israeli Conference on Mechanical Engineering - ICME 2010 , Dan Panorama Hotel, TelAviv 2-3 June 2010. 2. The 47th annual meeting of the IIChE, 2010. The Israeli Fuel Cell and Batteries Center (IFCBC) Conference, 2011 31 32