An echelon internal heating strategy for lithium-ion battery

An echelon internal heating strategy for lithium-ion battery

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Energy Procedia 142 Energy Procedia 00(2017) (2017)3135–3140 000–000 www.elsevier.com/locate/procedia

9th International Conference on Applied Energy, ICAE2017, 21-24 August 2017, Cardiff, UK

An echelon internal heating strategy for lithium-ion battery The 15th International Symposium on District Heating and Cooling

Shanshan GUOa,b, Rui XIONGa,b* , Fengchun SUNa,b,Jiayi CAOa,b,Kan WANGa,b

Assessing the feasibility of using the heat demand-outdoor of National Engineering Engineering Laboratory Laboratory for for Electric Electric Vehicles, Vehicles, School of Mechanical Mechanical Engineering, Engineering, Beijing Beijing Institute Institute of of Technology, Technology, 100081, 100081, China; China; temperature function for Vehicles aSchool long-term district heat demand forecast Beijing in Beijing Co-innovation Co-innovation Center Center for for Electric Electric Vehicles in Beijing, Beijing, Beijing Beijing Institute Institute of of Technology, Technology, Beijing Beijing 100081, 100081, China China

a aNational

Abstract a

bb

I. Andrića,b,c*, A. Pinaa, P. Ferrãoa, J. Fournierb., B. Lacarrièrec, O. Le Correc

IN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal

b An echelon heating strategy toRecherche preheat lithium-ion internally at Daniel, low temperatures alternating current (AC) is Veolia & Innovation,battery 291 Avenue Dreyfous 78520 Limay,with France Systèmes Énergétiques Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 France developed. AncDépartement electro-thermal coupled model iset developed to achieve a good balance between rapid heatNantes, generation rate and less damage to battery lifetime. Using this model the optimal frequency for maximum heat generation rate at a certain ambient conditions is determined and experimentally validated. The optimal time to change the current amplitude during preheating is calculated at a certain temperature by the theoretical formula based on terminal voltage within the allowable range. Experimental Abstract results demonstrate that the heat generation rate at the optimal frequency and variable current amplitude is fast with high efficiency and no voltage overrun. The battery can be heated from -20°C to 10 °C within 905 seconds, and the average District heatingisnetworks are commonly addressed in the literature as one of theverified most effective solutions damage for decreasing the temperature-rise 1.99°C/min. The proposed AC heating strategy is experimentally with no apparent to battery greenhouse emissions the building sector.batteries These systems require high investments which are returned through the heat life and can begas consulted forfrom engineering to preheat in electric vehicles. to the changed climate conditions ©sales. 2017 Due The Authors. Published by Elsevier Ltd. and building renovation policies, heat demand in the future could decrease, © 2017 The Authors. Published by Elsevier Ltd. prolonging the investment return period. Peer-review under responsibility of the scientific committee of the 9th International Conference on Applied Energy. Peer-review under ofassess the scientific committee of thethe 9thheat International on Applied Energy. The main scope ofresponsibility this paper is to the feasibility of using demand – Conference outdoor temperature function for heat demand forecast. Lithium-ion The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 Keywords: battery, low temperature,Alternating current, Echelon heating strategy Keywords: Lithium-ion battery, low temperature,Alternating current, Echelon heating strategy buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. 1. Introduction The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation Lithium-ion batteries with the performance advantages of high energy density, high voltage, little pollution, long scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). cycle life are commonly usedincreased as poweronsources electric vehicles [1].However, batteries (LIBs)toare The value of slope coefficient average in within the range of 3.8% up to 8% lithium-ion per decade, that corresponds the significantly difficult to charge or discharge at subzero temperatures [2-4]. Thus it is necessary to preheat the LIBsand at decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather subzero temperatures. Currently, for heating batteries in for cold environments are internal heating renovation scenarios considered). Onthe themain other methods hand, function intercept increased 7.8-12.7% per decade (depending on the and external heating.The In values the published external heating mainly included liquid or gas heating coupled scenarios). suggestedliteratures, could be used to modify themethods function are parameters for the scenarios considered, and [5, 6], heating plate [7], heating pipe[8-10], Peltier heating and so on[11-13]. improve the accuracy of heat demand estimations.

© 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific of The 15th International Symposium on District Heating and ** Corresponding author. Tel.: fax: +86-010-6891-4070. Corresponding author. Tel.: +86-010-6891-4070; +86-010-6891-4070; fax:Committee +86-010-6891-4070. Cooling. E-mail address: [email protected] Keywords: Heat demand; Forecast; Climate change 1876-6102 © 1876-6102 © 2017 2017 The The Authors. Authors. Published Published by by Elsevier Elsevier Ltd. Ltd. Peer-review Peer-review under under responsibility responsibility of of the the scientific scientific committee committee of of the the 9th 9th International International Conference Conference on on Applied Applied Energy. Energy.

1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling.

1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 9th International Conference on Applied Energy . 10.1016/j.egypro.2017.12.456

Shanshan Guo et al. / Energy Procedia 142 (2017) 3135–3140 Author name / Energy Procedia 00 (2017) 000–000

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It is relatively safe, easy to implement, however, the energy loss is relatively large, heating generation rate is slow, the battery temperature increase unevenly. Compared with external heating, internal heating is a heating strategy that heat generation from battery itself [14]. Many researches have been studied on internal heating methods. Wang [15, 16] invented a self-heating battery, that a piece of nickel-chip is installed in the battery and can heat itself rapidly from -20 ℃ or -30 ℃ to 0 ℃ within 20s or 30s, respectively. However, it changed the battery structure, cannot use the existing battery in engineering applications. Other internal heating strategy is the sinusoidal alternating current (SAC) heating strategy, which is verified that the battery has no damage after dozens of heating cycles, is recommended as a good way for internal heating[1, 3, 17-18]. Experimental verification displayed that the larger current amplitude the quicker heat generation rate [19, 20]. Whereas, the battery may be damaged irreversibly by the high current amplitude, for which may lead to the safe voltage range is exceeded and the battery is overcharging. So the voltage should be considered and kept in a reasonable range when selecting the current amplitude [21]. However, several studies neglect the polarization voltage [3, 17,18]. The proper current amplitude which ensures the terminal voltage within the safe range at low temperatures remains unanswered. In this work, an echelon heating strategy for lithium-ion battery is proposed, the optimal current amplitude for the maximum heat temperature-rise at a certain temperature is determined, which is changed with elevated temperature to keep voltage within the safe range. The experiment results show that the battery can be heated from -20°C to 10 °C within 905 seconds, and the average temperature-rise is 1.99°C/min. In addition, forty cycles of heating experiments have been carried out which reveal that no reduction of battery life. 2. Mathematical model For 18650 batteries, the heat generation rate between internal and surface is quite consistent according to Ref.[1]. Therefore, the battery is considered as a lump and the heat generation rate can be refined by: T . . (1) mc  Q Q p

t

n

(2)

.

 Qn hS (T Tamb )

Where m is the mass of the battery, C p is the specific heat capacity, T is the battery temperature, t is the time, Q is the heat generation rate, Qn is the heat loss to the outside of the battery, which conclude: heat flux and heat radiation. Ordinarily, heat radiation is ignored. Where h is the equivalent heat transfer coefficient, S is the battery surface area, Tamb is the ambient temperature. The heat generated from the real part of impedance is only taken into account according to Ref.[1,17] . The heat generation rate during the SAC heating can be governed as: . I (3) Q  ( )2 R Q

2

Where, I is the input amplitude of the alternating current. R is the real part of the overall impedance. Combined with the electro-thermal coupled model[30], R can be expressed as: RD (T) (4)  R (T) R (T)  Q

Q

Q

ohm

1  w 2 RD2 (T)C2D

Where R is ohmic resistance, is Relectrochemical polarization resistance.C Dis the electric double-layer capacitance. According to the Arrhenius equation, the R can be described as: E (5) R (T) A  exp( a ) ohm

D

D

D

T

Where Ea is the activation energy, and A is a pre-exponential constant. Overcharge should be prevented and the amplitude of the excitation current should be monitored at the optimal range during the AC heating process. The



Shanshan Guo et al. / Energy Procedia 142 (2017) 3135–3140 Author name / Energy Procedia 00 (2017) 000–000

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permitted AC current amplitude should be determined according to the model. The resistance is obtained by equation (4), according to law of ohm, the terminal voltage U t at k moment [3] can be given as: (6)

Ut ,k UOCV ,k 1  U D,k 1  Rohm  iL,k 1 1  U D,k 1 exp(

t



) U D,k  (1  exp(

U t , UOCV ,k  [exp( k 1

Where t is the time,

U OCV is

open-circuit voltage,

The permitted AC current amplitude

The

iL,k 1

iL,k 1 can

iL,k 1 is

t



t



(7)

))  i L,k 1R D

) U D ,k  (1  exp(

t



))  i L,k 1R D ]  Rohm  iL,k 1

(8)

the AC current amplitude at k+1 moment.

be consolidated as: iL,k 1 

changed with the temperature can be given as:

iL,k 1 (T) 

And according to the Voltage design limit:

U OCV  exp( (1  exp(

U OCV (T)  exp( (1  exp(

t



t



t



t



imin,k 1 (T) 

U OCV (T)  exp( (1  exp(

t



U OCV (T)  exp( (1  exp(

t



t



(9)

)) R D  Rohm

)  U D ,k  U t,max

(10)

)) R D (T)  Rohm (T)

U t ,min  U t  U t ,max

imax,k 1 (T) 

)  U D ,k  U t ,k 1

)  U D ,k  U t,max

(11) (12)

)) R D (T)  Rohm (T)

t



)  U D ,k  U t,min

(13)

)) R D (T)  Rohm (T)

Where i is the max current amplitude limit, imin,k 1 is the min current amplitude limit. Fundamentally, battery voltage limit is a complex non-linear control process during battery AC charge/discharge process. In order to and the imin,k 1 , and iterative simplify the thermal model in the paper, the input current should be the smaller of the i calculation method is adopted according to the above formulas. max,k 1

max,k 1

3. Experiments The tested battery in this study was a commercial 18650 cell with NCM cathode material and its specifications are shown in Table 1. The test equipment and measured devices used in this study are also shown in Figure2. The test battery is calibrated to 50% SOC for the EIS measurement and the following AC heating tests. An Autolab PP241 impedance analyzer measures the EIS. The experiments are implemented over the frequency ranging from 104 k Hz to 0.2 Hz, under a sinusoidal excitation of 5 mV amplitude. The thermal chamber controls and monitors the temperature of the test battery at every 5℃ from -20℃ to 5℃. The battery was soaked at each set temperature before EIS tests for more than 4 hours to make sure temperature equilibration. The ambient temperature is set and fixed at -20℃.The test battery with 50%SOC (state of charge) was soaked in the chamber at -20℃ for more than four hours. The temperature of the battery is measured by three T-type thermocouples. Then it is preheated with various frequencies and amplitudes from -20℃ by kikusui bipolar supply, generates sinusoidal alternating current.

Shanshan Guo et al. / Energy Procedia 142 (2017) 3135–3140 Author name / Energy Procedia 00 (2017) 000–000

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To investigate the effect of the frequencies on the heat generation rate, the AC heating test with various frequencies such as 5Hz, 10Hz, 20Hz, 30Hz, 50Hz are developed at 1.5A in order to make sure no overcharge. Then the current amplitudes are changed from 3A to 15A with a constant frequency 10Hz to analyze the impact of current amplitudes on the temperature rise rate. Table1.Specifications of the tested battery Battery type

Cylindrical 18650 lithium-ion battery

Cathode material

LiMnNiCoO2

Anode material

Graphite

Nominal capacity/ voltage

3000mAh/3.7V

Charge /discharge voltage

4.2V/3.0V

Battery length/ diameter

65mm/18mm

Battery mass

Table 2.Capacity fading of the echelon heating strategy

Times 0 10 20 30 40

46.0g

Charge capacity(Ah) 3.068 3.066 2.972 3.052 3.041

Discharge capacity(Ah) 3.061 3.056 2.974 3.051 3.045

1.72Jg-1K-1

Specific heat capacity

To speed up the rate of temperature rise, shorten the heating time, simultaneously, with no possible damage to the battery such as over-voltage, under-voltage, hot abuse and so on, the current amplitude and frequencies are determined carefully. The frequency is fixed at 10Hz. The concrete implementation method of the current amplitude is: The current amplitude changes at the temperature increased by 1 degree centigrade until reach the maximum current amplitude. This heating strategy is repeated for 40 times to verify its impact on the battery life. RD

Rohm

CD + +

+

U OCV

UD

-

Ut AC

-

-

Fig.1. Electro-thermal coupled model

Fig.2. Test equipment and measured devices

4. Results and discussion 4.1

EIS results at different temperatures

Figure 3 shows that the EIS of this battery enlarges in both the real and the imaginary parts with the decrease of the temperature. The impedance increases drastically with the decrease of temperature, implying that the parameters of the equivalent electrical circuit are highly temperature-sensitive. The equivalent electrical circuit model parameters at different temperatures are fitted using the EIS data. 4.2

Heating with different frequencies at 1.5A and different current amplitudes at 10Hz

The frequencies effects on heating time are demonstrated in Figures 4, which show the temperature evolution in various AC signal frequencies, the lower the frequency, the faster temperature rise. The temperature differences primarily result from the variation of impedance. The alternating current heating test with different current amplitudes such as 3A/6A/15A at 10 Hz are tested respectively and shown in figure5. The results show that when the current amplitude of the AC heating is very small at 3A, there is no obviously temperature rise.



Shanshan Guo et al. / Energy Procedia 142 (2017) 3135–3140 Author name / Energy Procedia 00 (2017) 000–000

3139 5

As the current increases, the temperature has a very significant increase. Within 1058s, the battery is heated separately by different current 3A, 6A, 15A at 10Hz from -18°C to -14.1°C,-8°C,-15°C. Contrary to figure 2 and 3, the temperature rise of the battery is more sensitive to current than frequency because the relationship between Q and I is squared according to Equation (3), which can lead to a dramatic heat generation rate inside the battery with the increased current. So it is more advisable to use the optimal current than frequency to heat the cell rapidly. 5Hz 10Hz 20Hz 30Hz 40Hz

-16.0

0.5 0.45

0.3

-17.0

T(℃)

0.35

Z'/mΩ

-16.5

0℃ 5℃ -5℃ -10℃ -15℃ -20℃

0.4

0.25 0.2

-17.5 -18.0 -18.5

0.15 -19.0

0.1

-19.5

0.05 0 0

0.2

0.4

0.6

Z/mΩ

0.8

1

1.2

Fig.3. EIS results at different temperatures

4.3

0

100

200

300

400

500

Time (s)

1.4

Fig.4. Heating with different frequencies at 1.5A

The echelon heating strategy of variable currents and effect on battery health

The echelon heating strategy to internally preheat lithium-ion battery at low temperatures with variable alternating currents is adopted and implemented. One typical experimental and simulated results of temperature rise using echelon heating strategy at 10 Hz frequency are shown in Figure 6. 3A 6A 15A

20

285

15 280

10

0

270

T/K

T(℃)

Simulation Experiment

275

5

-5

265

-10 260

-15 -20

255

0

200

400

600

800

1000

1200

time (s)

Fig.5.Temperature rise of AC heating at different current amplitudes.

250

0

100

200

300

400

500

600

700

800

900

1000

Time(s)

Fig.6. Experimental and simulated results of echelon heating strategy.

It can be clearly observed that at the beginning the cell temperature increases slowly because of the small current amplitude, then at about -15 ℃,as the increased current amplitude, the temperature increases apparently. Figure 6 shows that the battery can be heated from −20 ℃ to 10 ℃within 905 s. Overall, the proposed strategy affords an easier method to heat the battery rapidly and uniformly. Although the parameters that may shorten battery life are taken into consideration before heating, the experiment of life degradation also needs to be developed. To investigate whether this method has impact on the battery health, the capacity calibration is carried out after 40 times heating process at 30 ℃. By comparing the capacity calibration of the AC heating before and after 40 times, shown in Table 2, all the value are almost the same, implying that there is no obvious capacity deterioration. 5. Conclusion In this study, an echelon heating strategy using alternating current to preheat the lithium-ion batteries at low temperature was carried out. The reliability and validity of the echelon heating method are verified by the mathematical model and experiments. Be aimed to achieve a short heating time, high heating efficiency, the current amplitude, which should not be constant, is calculated accurately and gradually increased according to the transient

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Shanshan Guo et al. / Energy Procedia 142 (2017) 3135–3140 Author name / Energy Procedia 00 (2017) 000–000

temperature with the intermediate temperature by a low performance computer. The proposed echelon heating strategy can heat the test battery from-20°C to 10 °C within 905 seconds, and the temperature distribution of the battery is consistent. The well matched experimental and simulation results reveal that the average temperature-rise rate is fast and reaches 1.99 °C/min. Neither apparent capacity loss nor noticeable charge and discharge fade is found after 40 times owing to the strategy that focus on no overcharge. The proposed heating strategy with preferred determined parameters is demonstrated to have no damage on battery health, can be take into account as a potential method to preheating the EVs in cold weather. Further study will be focus on how to preheat the battery pack using this strategy. It is aimed to rapidly increase temperature without affecting the life of battery pack and verify the applicability and validity of this method. Acknowledgement This work was supported in part by the National Natural Science Foundation of China (Grant No. 51507012), Beijing Municipal Science and Technology Project (Grant No.Z171100000917013) and Joint Funds of the National Natural Science Foundation of China (Grant No. U1564206). The systemic experiments of the lithium- ion batteries were performed at the Advanced Energy Storage and Application (AESA) Group, Beijing Institute of Technology. Reference [1]Zhu, J., et al., An alternating current heating method for lithium‐ion batteries from subzero temperatures. International Journal of Energy Research, 2016. 40(13): p. 1869-1883. [2] Zhiguo LEI, et al., Study on Thermal Characteristics and Thermal Model of Lithium Ion Batteries for Electric Vehicles. New Technology of Electrical Energy, 2015. 34(12): p. 59-54. [3] Ji, Y. and C.Y. Wang, Heating strategies for Li-ion batteries operated from subzero temperatures. Electrochimica Acta, 2013. 107: p. 664-674. [4] Schindler, S., et al., Voltage relaxation and impedance spectroscopy as in-operando methods for the detection of lithium plating on graphitic anodes in commercial lithium-ion cells. Journal of Power Sources, 2016. 304(2): p. 170-180. [5] Yang, L., et al., Energy regulating and fluctuation stabilizing by air source heat pump and battery energy storage system in microgrid. Renewable Energy, 2016. 95: p. 202-212. [6] Wang, T., K.J. Tseng, and J. Zhao, Development of efficient air-cooling strategies for lithium-ion battery module based on empirical heat source model. Applied Thermal Engineering, 2015. 90: p. 521-529. [7] Azzouz, K., et al., HEAT EXCHANGE PLATE FOR THERMAL MANAGEMENT OF A BATTERY PACK. 2016. [8] Kim, Y.J., HEAT PIPE ASSEMBLY HAVING HEATING/COOLING FUNCTIONS, BATTERY MODULE FOR ECO-FRIENDLY VEHICLE USING THE SAME AND METHOD FOR OPERATING BATTERY MODULE. 2015. [9] Park, Y.J., et al., Design optimization of a loop heat pipe to cool a lithium ion battery onboard a military aircraft. Journal of Mechanical Science and Technology, 2010. 24(2): p. 609-618. [10] Greco, A., et al., A theoretical and computational study of lithium-ion battery thermal management for electric vehicles using heat pipes. Journal of Power Sources, 2014. 257(3): p. 344-355. [11] Lu Wancheng, Chen Xianzhang, et al, Car battery thermal management system and its working method. 2009, CN. [12] Zhang, Q., Y. Huo, and Z. Rao, Numerical study on solid–liquid phase change in paraffin as phase change material for battery thermal management. Science Bulletin, 2016. 61(5): p. 391-400. [13] Yang, X.H., S.C. Tan, and J. Liu, Thermal management of Li-ion battery with liquid metal. Energy Conversion & Management, 2016. 117: p. 577-585. [14]Wang, T., et al., Thermal investigation of lithium-ion battery module with different cell arrangement structures and forced air-cooling strategies. Applied Energy, 2014. 134(C): p. 229–238. [15]Wang, C.Y., et al., Lithium-ion battery structure that self-heats at low temperatures. Nature, 2016. 529(7587): p. 515. [16] Zhang, G., et al., Rapid self-heating and internal temperature sensing of lithium-ion batteries at low temperatures. Electrochimica Acta, 2016. 218: p. 149-155. [17] Ruan, H., et al., A rapid low-temperature internal heating strategy with optimal frequency based on constant polarization voltage for lithiumion batteries. Applied Energy, 2016. 177: p. 771-782. [18] Yingying YANG, Study on Low Temperature Performance of Lithium Ion Batteries for Vehicles. Mechatronics, 2016(6): p. 30-35. [19] Hande, A. and T.A. Stuart. AC heating for EV/HEV Batteries. in Power Electronics in Transportation. 2002. [20] Jiang, J., et al., Evaluation of Acceptable Charging Current of Power Li-Ion Batteries Based on Polarization Characteristics. IEEE Transactions on Industrial Electronics, 2014. 61(12): p. 6844-6851. [21] Stuart, T.A. and A. Hande, HEV battery heating using AC currents. Journal of Power Sources, 2004. 129(2): p. 368-378.