純電動(dòng)汽車鋰離子電池（Pure electric vehiclelithium ion battery）

1、純電動(dòng)汽車 3 鋰離子電池（Pure electric vehicle 3 lithium ion battery）This article by Jesus speechless contributionPpt documents may experience poor browsing on the WAP side. It is recommended that you first select TXT, or download the source file to the local view.The second chapter is pure electric vehicle (b

2、attery electric car) Battery car) Battery Electric Vehicles (BEV)L pure electric vehicles - lithium-ion batteries, pure electric vehicles - lithium-ion batteriesWorking principle diagram of lithium ion batteryWhen discharging, the lithium is dropped from the carbon material back to the oxide positiv

3、e electrode, and the positive electrode is in a lithium rich state. When charging the lithium ions from the cathode lattice extrusion, through organic electrolyte lithium ion conduction after migration into carbon negative material cathode, anode in lithium rich state, anode in lithium poor state, a

4、nd the electronic charge compensation from outside circuit is supplied to the carbon anode, guarantee the electric He Pingheng negative; load balance;Li ion battery performanceCompared with the traditional chemical power system, it has the following advantages: 1. High specific energy. The lithium i

5、on battery specific energy can reach 200Wh/Kg and 300Wh/L, is about the traditional zinc manganese, lead acid 200Wh/Kg and 300Wh/L, which is about 6 times of the traditional zinc manganese, lead acid and nickel cadmium battery 6 and nickel cadmium batteries; 2, wide range of working temperature. Ava

6、ilable in -200, C-+750, C rings, wide operating temperature range. Can work at ambient temperature; work under ambient temperature; 3. Good storage performance. The lithium primary battery usually stores 53 and has good storage performance. A lithium battery can be stored for 510 years, two times th

7、e self discharge of lithium battery is generally less than 15% (10 years, two lithium battery self discharge is generally less than 15% (one year), about conventional lead-acid, nickel cadmium battery, is about 1/10; conventional lead-acid, nickel cadmium batteries 1/10;Li ion battery performance4,

8、the high voltage of 3.6 volts (generally above 3 volts) and high voltage, 3.6 volts is generally above 3 volts) electric steady voltage; voltage stability; 5, small self discharge, long cycle life;, small self discharge, long cycle life, no memory effect; 6. At present, as an application trend, lith

9、ium-ion power battery is more and more used in electric vehicles. The application of Chinas lithium ion batteries in electric vehicles have been included in the national high technology research and development program (863 plan has been included in the national high technology research and developm

10、ent program (863 Program) and the national fifteen plan.Composition of lithium ion batteriesLithium ion battery is a lithium ion concentration cell, the positive and negative electrodes composed of two different kinds of lithium ion intercalation compound, commonly used anode lithium compounds Li ca

11、thode generally use lithium compounds LiXCoO2, LiXNiO2 or LiMn2O4, using a carbon anode lithium intercalation compound Li negative pole lithium intercalation compounds with carbon LiXC6, electrolyte LiPF LiPF6 and LiAsF6 organic electrolyte solution, with Li ten in organic solution, with Li negative

12、 electrode trips between intercalation and deintercalation of charging and discharging process of battery formation. When charging, the Li ten positive electrode is removed and embedded, and the electrolyte is embedded in the negative electrode, the negative electrode is in the lithium rich state, t

13、he positive electrode is in a lithium poor state, and the discharge is just the opposite.A mathematical model for Li ion batteriesThe basis of modeling of Li ion battery is how to determine the electromotive force and internal resistance characteristic function of lithium-ion battery. The determinat

14、ion of these characteristic functions is based on the results of the variation relation of the charge state value SOC (State, of, Capacity) of the battery, Capacity).Charging characteristicsCharge state of Li ion batteryThe two basic characteristics of Li ion battery: two basic characteristics of Li

15、 ion battery: 1, the battery capacity and the discharge current, discharge current increases, the current effective capacity that can release the less, this property referred to as less capacity characteristics, working voltage and the discharge 2, the battery capacity characteristics referred to as

16、 the depth, the greater the depth of discharge current and the discharge voltage of the battery, the work decreased more,This property is referred to as the voltage drop, which is referred to as the voltage characteristicThe battery energy model is based on an equivalent circuit diagram of the batte

17、ry,The characteristics of battery capacity will directly affect the effective range of electric vehicles, and its voltage characteristics will directly affect the dynamic performance of electric vehicles, both interdependence, mutual influence, constitute the battery discharge characteristics (2.7v-

18、4.2v). The mutual influence constitutes the discharge characteristics of the battery (2.7v-4.2v).Discharge characteristicsThe experiment found that lithium ion battery end voltage 2.7V in the discharge conditions, the discharge current is polarized 2.7V cell polarization conditions, the discharge cu

19、rrent is the battery increases, the discharge capacity of the battery is small, but the relationship between the depth of discharge voltage of the battery and the battery is basically unchanged state. In the case of large current discharge (greater than 2C), the discharge curve of the battery is lar

20、ger than 2C. The discharge curve of the battery shows the phenomenon that the voltage decreases first and then rises.ExampleAt 25 degrees Celsius, the battery is charged to constant voltage at constant flow of 4.2 V and then to 4.2 V, then the constant voltage charge is applied. When the charging cu

21、rrent is less than 10% of the constant current charge, the charge is stopped,ExampleFrom figure 1A shows that from figure 1A shows that the single battery charging curve is divided into two parts to charge constant current charging and constant voltage charging and constant voltage charging, the two

22、 part, with the increase of the charge current, battery constant current charging capacity to reduce the proportion of single battery constant constant current charging capacity to reduce the proportion of pressure charging capacity, the increase in the proportion of pressure charging capacity; the

23、increase in the proportion; with charge rate increase, improve, single battery voltage constant current charging process of the rising rate of speed, speed up the rate of charging platform also increased. When the charging rate of 7 C, basically can not see the characteristics of LiMn2O4, charging f

24、lat C basically can not see the LiMn, which is mainly due to the high rate of battery charging electrochemical polarization caused by the increase.ExampleFrom figure 1b shows: the discharge curves of 1B single cell in different magnification visible: the similar shapes, and close to the initial disc

25、harge voltage at the end of the rapid decline, the mid small changes in discharge voltage, showing a discharge platform. The 1 C discharge platform for the single cell is maintained at 3.85 units. The 1 C discharge platform of the single cell remains at about 3.85 V;. With the increase of discharge

26、rate, the discharge platform of the battery will decrease and the capacity will be reduced. When the discharge rate is increased to 6 C, the capacity decreases. When the discharge rate is increased to 6 C, the discharge platform is reduced to about 3.57 V, the discharge capacity is 1 C, and the capa

27、city is 91%. Continue to increase the discharge rate to 12 C, discharge%. Continue to increase the discharge rate to the discharge platform to maintain at 3.31, the platform remained at about 3.31 V, discharge capacity close to 1 C capacity, discharge capacity close to 1, C capacity of 62%. %.Availa

28、ble capacityBattery capacityT - battery discharge time; battery discharge time; N - Peukert constant; for different battery values are not Peukert constant; for different battery values are different.Utilization coefficient of a batteryCharge state of batteryBattery state of charge K abbreviated SOC

29、, also available% battery state of charge K abbreviated SOC, can also be used to measure the percentage of.Mathematical model of internal resistance of lithium batteryExpressed as a function of the battery charge state value:The calculation of the battery terminal voltage is as follows: the calculat

30、ion of the battery terminal voltage is as follows:Disadvantages: disadvantages:(1) lithium ion cathode for lithium ion batteries when charging the dissolution of too much (1) lithium ion cathode for lithium ion batteries when charging the dissolution of too much back to the original state of the bat

31、tery discharge when the lithium ion can not be filled to the positive terminal of the channel. The battery charge is not enough to cause permanent damage. In this way, we must take measures to limit the charging voltage to control the dissolution of lithium ions;The way to control the voltage of lit

32、hium ion dissolution; (2) lithium ion battery discharge on the end point, the internal material will be sent (2) lithium ion battery discharge on the end point, the internal material will change, that lithium ion graphite layer on negative electrode in all off, next time when charging the graphite c

33、athode layer no lithium ion can ensure smooth loop, so to take measures to control the discharge voltage; (3) if you short-circuit the battery or excessive discharge current (3) if you short-circuit the battery or excessive discharge electric current will cause the internal temperature of the batter

34、y is too high and the energy consumption, it will shorten the discharge time, so to carry out overcurrent protection.Pay attention to the following three aspects: pay attention to the following three aspects:1. lithium ion battery has great resistance, can not achieve the 1. lithium ion battery has

35、great resistance fast charge, unable to realize the fast charging or discharging, high rate charge or discharge will cause the battery temperature exceeds the allowable range, cause safety problems. Therefore, we must strictly limit the lithium ion battery charge discharge rate, strictly control the

36、 operation temperature of lithium ion battery; pool working temperature; 2. battery into the constant voltage charging stage, to strictly control the battery into the battery 2. constant voltage charging stage, to strictly control the battery charging voltage, charging to prevent overvoltage or unde

37、rvoltage charging; the charging voltage, charging to prevent overvoltage or undervoltage charging; 3. discharge process, to prevent the battery depth of discharge. When the electric 3. discharge process, to prevent the battery from deep discharge. When the terminal voltage of the battery is lower th

38、an the discharge terminal voltage of the battery, the discharge work of the battery should be stopped immediately.UltracapacitorAs the electric car frequently starts and stops, the discharge process of the battery is greatly changed. In normal driving, the average power draw from the battery of elec

39、tric vehicle is quite low, and the peak power of the acceleration and climbing the peak power ratio is quite high, a high performance of the electric vehicle and the average power of up to 16:1. The ratio of peak power of electric vehicles with high performance and average power up to 16:1. For the

40、acceleration and climbing when the energy consumption accounted for 2/3 of the total energy consumption in the existing consumption for the acceleration and climbing when energy accounted for 2/3 of the total energy consumption in the battery, the existing technical conditions, the battery must be i

41、n energy and power and the ratio between power and cycle life balance is difficult to do, a set of energy systems while pursuing high specific energy, high specific power and long life. In order to solve the electric vehicle mileage and speed up the contradiction between the climbing performance, yo

42、u can consider using two sets of energy system, which offer the best mileage from the main energy, and the auxiliary energy in the acceleration and climbing to provide auxiliary power short. The energy of the auxiliary energy system can be taken directly from an autonomous energy source, or renewabl

43、e kinetic energy can be recovered during braking or downhill of an electric vehicle. The use of ultracapacitor as an auxiliary energy source has attracted wide attention.Super capacitor featuresIn the near future, the very low specific energy of supercapacitors makes it impossible to use it solely a

44、s an energy source for electric vehicles, but the use of ultracapacitor as an auxiliary energy source has significant advantages. The best combination used in electric vehicles is the battery and ultracapacitor hybrid energy system, which allows the ev to separate the specific energy and specific po

45、wer requirements of the battery. The battery design can focus on comparing energy and cycle life considerations without having to consider the specific power issues much. Because of the load balancing effect of the super capacitor, the discharge current of the battery is reduced, so that the useful

46、energy and the service life of the battery can be remarkably improved. And, compared with batteries, supercapacitors can absorb the regenerative kinetic energy produced by electric cars quickly and efficiently. Due to the load balancing and energy recovery of the super capacitor, the vehicle mileage has been greatly improved. But the system should be integrated, optimized and matched with batteries, super capacitors, motors and pow