Progress and Problem of Battery System for Traction Use

Transcription

1 Progress and Problem of Battery System for Traction Use Jianbo Zhang Dept. of Automotive Engineering Tsinghua University State Key Laboratory for Automotive Safety and Energy Sept. 30-Oct. 2, 2013 Messe Stuttgart, Germany

2 Outline 1. China s progress in xevs and LIB 2. Thermal issues in traction battery system 3. Our work on thermal properties of largeformat battery 4. Future work

3 A Dream Come True or a Nightmare Just Beginning China became the largest car producer and market in the world in 2009, reaching annual sales of 19 millions in 2012, with 40 millions being projected for Sales(10k) 中国 CHN 美国 US 日本 JPN Year

4 Foreign Dependence of Oil Approaches 60% Domestic/imported Oil(10k Ton) 国产原油 Domestic 进口原油 Imported 对外依存度 Foreign dependence 47% 44% 41% 41% 35% 29% 29% 20% 5% 60% 56% 56% 55% 51% 49% 50% Year 40% 30% 20% 10% 0% Foreign dependence 4

5 Congestion and Smog

6 Dual Strategy to Sustainable Development

7 Focus on E-Mobility

8 Ambitious Goals: 5 Million EVs till 2020 Global EV Outlook (IEA, April 2013) --Understanding the EV Landscape to

9 Sales and Stocks in 2012 Global EV Outlook (IEA, April 2013) --Understanding the EV Landscape to

10 EV-related Standards: China vs. International Type China(68 ) ISO(11) IEC(9) BEV Vehicle HEV FCV Electric Motor Infrastructure Key compon ents Traction Battery Motor and control Charging device and station

11 Cell Size and Configuration (QC/T ) 长度 长度 直径 高度 宽度 高度 宽度 高度 LIB Nominal Maximum size ( mm ) Capacity No. voltage (Ah) Length (V) Width Height (diameter)

12 ISO16898: Configuration and Sizes for Traction Battery 11 of the 87 specifications came from China Table 1 / cylindrical cells Application Shape Type D / W Di / T H h p p source year scale V R B 26 n.a. 65 n.a. n.a. n.a. CN 2010 medium Table 2 / prismatic cells V P A CN 2010 large V P A CN 2008 large V P A CN 2010 V P A 179.5± ± ± ±0.2 CN V P A ±0.2 20±0.2 16±0.2 CN 2009 large V P A 135.0± ± ± ±0.2(negative) ±0.2(positive) 12.5 CN 2010 large V P A 99.5± ± ± ± W/2 10~15 CN 2008 large V P B CN 2011 large Table 3, pouch cells V F A 343±3 18.5± ±2 245±2 80±2 9±0.2 CN 2008 large V F A CN 2008 large

13 SCI Paper on LIB: Year Total number of paper Top 5 countries Percent of the top CHN 731 US 472 JPN 282 KOR 270 FRA % CHN 742 US 418 JPN 254 KOR 252 FRA % CHN 990 US 590 JPN 304 KOR 295 FRA % CHN 991 US 694 KOR 364 JPN 337 FRA % CHN 1284 US 906 KOR 344 JPN 321 GER % 何向明, 田光宇, 张剑波, 从 SCI 收录论文数量统计看锂离子电池研究动态, 锂电世界,2012,2:

14 Major Battery Manufacturers in China

15 Major Battery Material Manufacturers in China

16 Performance of LIB Comparable with World Leading Companies World Domestic 1800W/kg Power type LIB World Domestic 120Wh/kg Energy type LIB

17 Challenge: Thermal Runaways of EV Date Accident Cause June 7, 2008 Prius PHEV, US Caused by improper bolted joints June, 2008 Jan. 7, 2010 April 11, 2011 Honda HEV fire, Japan EV buses fire, Urumqi, China Zotye EV taxi fire, Hangzhou, China Caused by overheated LiFePO4 batteries LFP batteries malfunctioned and catch fire, ignited the bus Wangxiang, 16Ah LFP batteries, Electrolyte leaked for at least two modules, Short circuit, self-ignition. June 3-6, 2011 GM Volt fire, US Caused by crash test weeks ago July 18, 2011 May 26, 2012 EV bus fire, Shanghai, China BYD E6, Shenzhen, China(3 killed in the accident) Caused by overheated LFP batteries Battery were squeezed due to the collision, short circuit led to electric arc between the high voltage wires and the car body, igniting the car Thermal runaway caused fire and explosion of lithium ion battery, Journal of Power Sources 208 (2012)

18 Challenge: Life and Low T Performance Life for the battery system << Life for the cell < Life for the vehicle 20 Cities-1000 Vehicles Program 18

19 Outline 1. China s progress in xevs and LIB 2. Thermal issues in traction battery system 3. Our work on thermal properties of largeformat battery 4. Future work

20 Charging and Discharging Capability at Different T 温温温放电 0 温温温放电 -10 温温温放电 -20 温温温放电 -30 温温温放电 -40 温温温放电 A 恒恒放电电电 / V 充电电电 / V 充电 10 充电 0 充电 -10 充电 -20 充电 -30 充电 -40 充电 放电放放 / Ah 充电放放 / Ah 20

21 Battery Power vs. T At low temperatures the performance is reduced for both energy and power. However, the power depends much stronger on the temperature than the energy. Operation at high temperatures is not recommended to avoid overheating of the battery and to reduce the aging. Best performance of Li-Ion cells is reached in a very narrow temperature band. VOLTEC Battery System for Electric Vehicle with Extended Range SAE International,

22 Cell Variability vs. T 放电电电 / V 号电号 2号电号 3号电号 4号电号 放电电电 / V 号电号 2号电号 3号电号 4号电号 放电放放 / Ah 放电放放 / Ah 1C discharge at 20 1C discharge at

23 Cell Life vs. T Temperatures above 35 C to 40 C should be avoided or at least reduced to a short time only. Ln(Degradation rate) Life High T: Electrolyte and solvent decomposition Ahrenius-Law = Low T: Li plating T 60 C 10 C 1/T

24 Cell Safety vs. T Processes leading to thermal runaway 动力锂离子电池的安全性控制策略及其试验验证, 汽车安全与节能学报, 李建军, 王莉, 高剑, 何向明, 田光宇, 张剑波 24

25 LIB for Electronic Device vs LIB for Traction Use Charge Capacity (Ah Ah) Energy Capacity (Wh Wh) Number of cells in package (-) Working conditions Life (Year Year) Cost of battery relative to the product (-) Electronic Device ~1 ~1 <10 Around room temperature 1-2 ~1% Traction Use ~ ~50 C, Shock, vibration 8-10 Second life (4R) Range, safety Uniformity Reliability Durability ~1/4-1/3 Costperformance ratio

26 Multi-scale and Multi-physics Uniform, heat generation rate, reaction, amount of heat, fundamental Positive active material Negative active material Separator Electrolyte Material Thermal stability Endothermic/Exothermic reactions Thermal compatibility Thermal resistance of separator Effect of T on the transport parameters Method TG-MS Newly made or used Electrode layer Thermal stability of SEI Thermal properties and the influence of components, structure DSC 100 mah (Uniform) Coin cell Effect of T on performance, life, safety Heat generation rate Distribution, heat conduction/removal, T, application 20~40 Ah Single cell Thermal properties and its dependence on cell configuration, size, structure Local hot spot, heat transfer path Equivalent thermal properties Thermal model Thermal-electrical electrical coupling Optimization kwh thermal management Package EVs Thermal environ Requirement on the T Drive cycle range and variation Climate BTMS(PCM, air, liquid, Vehicle thermal heating, insulation) management for OCV(SOC,T) Thermal screening Suppression of thermal runaway PCM Coupling between thermal, mechanical, electrical, fluid Infrared thermograph Embedded T.C. Flow visualization Surface heat transfer rate, IBC ARC Matlab, COMSOL ANSYS, Star-CD

27 Coupling between Modeling and Experiment Configuring a high voltage battery, for the Volt, was more than just attaching multiple cells together to form a parallel/series string. Math studies, Finite Element, DFMEA, and multiple other disciplines allowed virtual components, to drive hardware requirements. Worst case scenarios, and predictions for end of life behavior, drove material selections and packaging directions. Thermal model of battery next to hot exhaust pipe in charge sustaining operation VOLTEC Battery System for Electric Vehicle with Extended Range SAE International,

28 Outline 1. China s progress in xevs and LIB 2. Thermal issues in traction battery system 3. Our work on thermal properties of largeformat battery 4. Future work

29 Framework Thermalelectrochemical model deeq qg = IT + I( Eeq E) dt Heat generation model and estimation methods Simulation Thermal Issues Thermal parameters Measuring T for Validation 29

30 Reversible Heat Generation Rate Q rev. du = IT dt Potentiometric method Calorimetric method U T P = q discharge q 2IT charge 2013/9/24 30/28

31 Irreversible Heat Generation Rate V-I characteristic method ( ) ( ) / Q = I U V = R = U V I ir rev. 2 Qir rev. IR V-OCV method Intermittent current method EIS method Four approaches to measure R 2013/9/24 31

32 Irreversible Heat Generation Rate Energy method (estimating the Irrev. heat directly, not through R) Charge: Echa = Ebat + Erev,cha + Eirrev,cha Discharge: Ebat = Edischa + Erev,discha + Eirrev,discha Irrev. heat: ( ) E = E - E / 2 irrev cha discha 2013/9/24 32

33 Difficulties in Estimating Heat Generation Rate of Large-Format LIBs Temperature rise during charging/discharging Time delay Temperature/ o C Ah 2C dch o C Time/min 2013/9/24 33

34 Journal of Power Sources, submitted,zhang et al. Work1: Compare/validate methods to estimate the heat generation rate 2013/9/24 34

35 Validation of temperature rising rate using estimated heat generation rate dt/dt (K min -1 ) R VI of pouch cell R EM of pouch cell Measurement Calculation with R VI of pouch cell Calculation with R EM of pouch cell Calculation with R IC of 25Ah cell Calculation with R EM of 25Ah cell dt/dt (K min -1 ) R EM of pouch cell R VI of pouch cell Measurement calculation with R VI of pouch cell calculation with R EM of pouch cell calculation with R IC of 25Ah cell calculation with R EM of 25Ah cell R IC of 25Ah cell R EM of 25Ah cell SOC (-) R IC of 25Ah cell R EM of 25Ah cell SOC (-) A comparison between calculated and experimental temperature rising rate of 25Ah cell during discharging at 1C. A comparison between calculated and experimental temperature rising rate of 25Ah cell during charging at 1C. 2013/9/24 35

36 Validation of temperature rise using estimated heat generation rate T ( ) R VI of pouch cell R EM of pouch cell R IC of 25Ah cell R EM of 25Ah cell Measurement Calculation with R VI of pouch cell Calculation with R EM of pouch cell Calculation with R IC of 25Ah cell Calculation with R EM of 25Ah cell T ( ) measurement calculation with R VI of pouch cell calculation with R EM of pouch cell calculation with R IC of 25Ah cell calculation with R EM of 25Ah cell R EM of pouch cell R VI of pouch cell R IC of 25Ah cell R EM of 25Ah cell SOC (-) SOC (-) A comparison between calculated and experimental cell temperature of 25Ah cell during charging (left)/discharging (right) at 1C. 2013/9/24 36

37 Journal of Power Sources, submitted,zhang et al. Work 2: Estimate thermal parameters Challenges Thermal conductivity Soak of electrolyte Al-plastic film Anisotropy Specific heat capacity Negative Core Non-uniform temperature distribution of large-format batteries Requirement Equivalent, In-situ, Anisotropy Battery Negative Positive Positive Core structure Separator 37

38 Inverse problem formulation Numerical simulation and optimization based on the transient temperature distribution at multi-points Experiment Validate the symmetry hypothesis Measure the temperature of multipoints on the undersurface Simulation Develop heat transfer model Initiate thermal parameters input Compute temperature distribution Optimization Heat insulator Thermography battery Constant temperature heater Adjust the unknown parameters of simulation to fit best with the data from experiment Thermocouple: T(x,t) 38

39 Results and Validation Parameter Optimization Results k r /W m -1 K k z /W m -1 K C p /J g -1 K λ /W m -2 K Cp measured with the ARC is 1.05~1.19 J g -1 K -1 Cp measured with the HFC is 1.03 ± 0.14 J g -1 K -1 39

40 Journal of Power Sources 241 (2013) 536 e 553,Zhe Li et al. Work 3: Measure the spatial and temporal variation of internal temperature Literature review The direct measurement of internal temperature distribution was not found in existing literatures. 2010, Christophe Forgez: LFP,a hole drilled at the center of the cylinder top, and 1 sensor inserted. 2011, Chi-Yuan Lee: spirally-wound prismatic Li-ion, 2 sensors inserted to the axis space of the roll. Ref. 1 Ref. 2 Ref 1: C. Forgez, D.V. Do, G. Friedrich, et al. Thermal modeling of a cylindrical LiFePO4/graphite lithium-ion battery, Journal of Power Sources, 2010, 195(9): Ref 2: C.Y. Lee, S.J. Lee, M.S. Tang, et al. In situ monitoring of temperature inside lithium-ion batteries by flexible micro temperature sensors, Sensors, 2011, (11):

41 Examining temporal and spatial variations of internal temperature in large-format laminated battery with embedded thermocouples Product:25Ah large-format laminated cell with 12 embedded thermocouples A1~A12: Internal B1~B12: Surface

42 Examining temporal and spatial variations of internal temperature in large-format laminated battery with embedded thermocouples Discussion:time evolution max temperature rise Adiabatic Natural convection (NC) Forced convection (FC) Conclusion: (1)The max rise increases with rate. (2)The max rise decreases with increased ventilation.

43 Examining temporal and spatial variations of internal temperature in large-format laminated battery with embedded thermocouples Discussion:spatial variation internal 12 locations(in-plane direction) Conclusion: (1)The temperature variation of internal locations reached 10 C (1.5C, adiabatic) (2)The nonuniformity got stronger when the rate increased. (3)Increasing ventilation depressed the internal variation. The maximum internal variation had been decreased to less than 3 C under forced convection (1.5C). In-plane direction variation (12 internal locations at the moment of the max T reached) Variation of in-plane direction is severe!

44 Examining temporal and spatial variations of internal temperature in large-format laminated battery with embedded thermocouples Discussion:Spatial variation response time of internal and surface locations to external heating T mc p = qc + qg t First-order inertia process Transfer function: qc = ( k T ) 1 r Input Ta,Output T G ( s) = k T n = h( T T a ) 1 +τ ({ Ta}) s The temperature of ambient environment, A1 and B1 The time constants of A1 and B1 on different temperature ranges

45 Outline 1. China s progress in xevs and LIB 2. Thermal issues in traction battery system 3. Our work on thermal properties of largeformat battery 4. Future work

46 Framework Thermalelectrochemical model deeq qg = IT + I( Eeq E) dt Heat generation model and estimation methods Simulation Thermal Issues Thermal parameters Measuring T for Validation 46

47 Standardization of Large-Format LIB Pros and Cons

48 Acknowledgement National 863 Program under the subject number of 2011AA11A230 National Natural Science Foundation of China under the grant number of Independent Research Programs of Tsinghua University under the subject number of 2011Z01004