KR20010037119A - Lithium polymer battery for electric vehicle or hybrid electric vehicle - Google Patents

Abstract

PURPOSE: A lithium polymer battery for an electric car or a hybrid electric car is provided to overcome deterioration of life cycle and performance of battery module and battery pack due to temperature deviation inside a unit cell by forming air flow for cooling the unit cell due to a plastic spacer inserted between the unit cells, thereby effectively controlling heat, and simplify overall structure of the battery, thereby increasing energy density by removing a structure which is added by internal pressure, etc. CONSTITUTION: The lithium polymer battery comprises a plastic case (50) having a structure through which external air can pass freely, spacers (70) which are inserted between a plurality of polymer unit cells having a few Ah and distanced each other, and an upper cover (80) on which negative and positive output terminals (81,82) are prominently formed, wherein the negative and positive output terminals (81,82) generate power by connecting the spacers (70) with the polymer unit cells (60) for producing high capacity and high voltage.

Description

Lithium polymer battery for electric vehicle / hybrid electric vehicle {Lithium polymer battery for electric vehicle or hybrid electric vehicle}

The present invention relates to a battery for an electric vehicle or a hybrid electric vehicle, and more specifically, a case (Case) by arranging a plurality of lithium polymer unit cells made of a thin aluminum sheet in a plastic case configured to allow the outside air to pass through smoothly A battery having a high capacity (50 Ah to 150 Ah) and a high voltage (10 V to 20 V) is configured to facilitate mounting on a vehicle.

In particular, the present invention provides a spacer between the unit cells to minimize the heat dissipation of the unit cell and the temperature deviation between the unit cells by the air flowing from the outside to reduce the performance due to temperature variation and the performance deviation between the unit cells The present invention relates to constructing a high capacity or high voltage battery of a lithium polymer battery with a unit cell for use in a system such as an electric vehicle or a hybrid electric vehicle requiring a high capacity and a high voltage to overcome the life and performance deterioration.

As is well known, the electric vehicle is a vehicle that can fundamentally solve the environmental problem among the problems with the vehicle equipped with the internal combustion engine which is the mainstream is characterized by no emissions.

That is, as described above, the electric vehicle is not obtained by the combustion action of the fuel as in the conventional art, but by the electric power provided from the charged battery, so that the exhaust gas generated when the internal combustion engine is operated is generated. It is not.

Therefore, the battery for providing the power required for driving the vehicle in the electric vehicle is essential, and the performance of the battery is the key to have sufficient mileage and power performance, such as gasoline vehicles.

The driving distance of an electric vehicle is determined by the total energy of a battery mounted in the vehicle, and the total energy is determined by the capacity and voltage of the mounted battery. In the case of a vehicle, the battery mounting space is limited, and since the battery usually occupies 30% to 40% of the vehicle weight, electrical energy per unit volume and electrical energy per unit weight become an important factor in an electric vehicle battery. In general, a lead battery has a short driving distance within 50 miles at 30 Wh / kg, and a Ni-MH battery having an energy density of 70 to 80 Wh / kg has a driving distance of about 100 miles. Therefore, in order to increase the mileage, development of an electric vehicle with a high energy density Li-based secondary battery is underway. Li-based secondary battery is divided into Li-ion battery having a liquid electrolyte, and a polymer battery having a solid electrolyte. Currently, Li-ion batteries are Sony and Nissan of Japan. Is currently mounted on vehicles. Li-polymer battery that operates at room temperature is currently used for cellular phones of 1Ah class, energy density is 130 ~ 140Wh / kg, about twice that of Ni-MH battery, and is currently developed for 5Ah class notebooks. It is becoming. Since the energy density is about twice that of Ni-MH, it is expected that the driving distance of 200 miles is expected when applied to the vehicle, which is an energy storage means that can solve the mileage problem. Therefore, in order to be used as a power source for electric vehicles, development of high capacity batteries with increased capacities to 50 to 150 Ah is required. In addition, for cellular phones and laptops, a low voltage of 3.6V to 7.2V is required, but for vehicles, a high voltage of 300V or more is required. Should be designed.

In general, since a single unit cell capable of charging and discharging electricity has a low voltage and capacity, a high voltage and high capacity are required by using a unit cell to meet the voltage and capacity required by a vehicle. Battery systems that use aqueous solutions as electrolytes, such as lead-acid batteries and alkaline batteries such as Ni-Cd or Ni-MH, have pressure resistance due to gas generation by water decomposition, and the thickness of the case decreases the energy per unit volume. When using a steel (stainless steel) material can be less than 0.5mm in thickness, but there is a problem that the energy per unit weight is reduced due to the high density of 7.8g / cc. Therefore, in order to achieve high capacity without sacrificing energy density, it is necessary to increase the capacity of the unit cell itself, and in this case, there is a problem in that the inner pole plate of the pole plates constituting the unit cell has a poor thermal problem.

FIG. 1 illustrates a battery module 100 having 11 Ni-MH unit cells connected in series to facilitate mounting and handling. The battery module 100 withstands the internal pressure of a plurality of unit cells 110 arranged in a row. It is designed to have an end plate (End plate; 120) and a stainless steel band (stainlesssteel band; 130) to support it.

In addition, as shown in FIG. 2, the unit cell 110 includes a cathode plate 112 and an anode plate 113 formed of MH and Ni (OH) ₂ . The lid assembly 116 is connected to the lid assembly 116 by welding or bolting, and then embedded in a can 111 to be welded, and the center of the lid assembly 116 is inside the can 111. Vent structure 117 is provided to discharge when the gas exceeds the dangerous level. Since Ni-MH cells use an aqueous solution of electrolyte, the gas is theoretically generated and the operating pressure is usually about 50 to 70 psig. Therefore, the can should be designed to withstand such pressure resistance characteristics. Achieving high capacity minimizes the sacrifice of energy density, but there is a weak point in the thermal properties of the plate located in the middle of the plate group.

Current electric vehicles require energy of about 15 to 60 kWh, and in this case, the electric capacity and voltage of the battery are 50 to 150 Ah and 300 to 400 V, respectively, so that a high capacity and a high voltage of the unit cell are required to satisfy this. In the case of lead batteries or Ni-MH batteries that are capable of high capacity of unit cells, in order to fabricate 50 to 150 Ah unit cells and to high voltage, 240 to 260 unit cells 110 must be connected in series. Therefore, for easy handling and connection, 10 ~ 11 unit cells are connected by serial power to form a module (Module; 100), and then 24 to 27 units are connected in series to pack 15 ~ 60kWh. Will be configured. Likewise, the Li-polymer battery also needs a high voltage and a high capacity as described above in order to be used in an electric vehicle, and there is a problem in that a battery configuration for increasing the capacity and voltage of the high-capacity battery must be solved. Unlike Li-ion batteries using liquid electrolytes, the high capacity of Li-polymer batteries using electrolytes having a solid phase and a liquid intermediate form a problem of extracting ions for injection of electrolytes, and the thermally located electrode plate at the center of high capacity. Due to various technical problems such as problems, a 5Ah grade with a thickness of about 4 to 6 mm is currently being developed. The case of high capacity Ni-MH battery has the disadvantage that the weight ratio is 20% by using relatively heavy stainless steel, whereas the Li-polymer battery is made of light aluminum sheet so that the weight fraction of the case is less than 5%. It has an advantage in the storage of sugar energy.

In addition, since the voltage of the battery system used in the electric vehicle is composed of a high voltage of 300V or more, thermal management of hundreds of individual unit cells greatly influences the battery life and characteristics, and thus, effective thermal management is required. In the case of Ni-MH batteries, the pack is composed of 23 to 27 battery modules 100. In this case, there is a temperature deviation between the modules and a temperature deviation between the unit cells 110 in the module, resulting in a performance difference between the batteries in the pack. There is a problem of degrading the life and performance of the battery pack.

In the case of a hybrid electric vehicle, the required voltage is similar to that of an electric vehicle, but there is a difference in capacity between a series and a parallel type. In the case of a series type, a high capacity similar to that of an electric vehicle is required, but in the case of a power-assisted type parallel type, a small capacity battery of 5 to 20 Ah is required, and thermal management is particularly important in this case.

Accordingly, the present invention has been made in view of the above problems, using a small-capacity Li-polymer battery to efficiently flow the air between a high capacity, high voltage battery configuration method and unit cells for electric vehicles and hybrid electric vehicles An object of the present invention is to construct a battery pack capable of overcoming deterioration of the lifespan and performance of a battery module and a battery pack due to temperature variations in a unit cell by means of spacers inserted therein.

1 is a perspective view showing a typical Ni-HM battery module for an electric vehicle

FIG. 2 is a partial cutaway perspective view of the Ni-HM unit cell shown in FIG. 1; FIG.

3 is an exploded perspective view showing a large capacity polymer battery for an electric vehicle according to Embodiment 1 of the present invention;

4 is a perspective view partially showing an arrangement of the polymer unit cell shown in FIG.

Figure 5 is an exploded perspective view showing a 11.4V 80 ~ 100 Ah class large capacity battery module for an electric vehicle according to a second embodiment of the present invention

Explanation of symbols on the main parts of the drawings

1: large capacity polymer battery 2: polymer battery module

10, 50: plastic case 11: space part

20, 60: polymer unit cell 21: aluminum foil case

25, 65: Terminal 26, 66: Both terminals

30, 70: plastic spacer 40, 80: plastic top cover

41, 81: Sound output terminal 42, 82: Positive output terminal

43, 83: negative connection bar 54, 84: positive connection bar

The present invention for achieving the above object has a thermal problem and other problems when the high capacity Li-polymer battery in the same way as the Ni-MH battery, but compared to the Ni-MH battery that the case occupies 20% of the total weight, 50 ~ 150Ah class battery by inserting a lot of pole plates in one case like Ni-MH battery at the time of high capacity by taking advantage of the use of aluminum case which is light within 5% of the case and has excellent heat dissipation efficiency. In order to achieve high capacity of 50 ~ 150Ah class by using current 5Ah battery in consideration of thermal characteristics instead of making a large weight fraction of the case, and to simplify the installation and handling on electric and hybrid electric vehicles It is to provide a modularization plan.

In order to solve the thermal problem caused by high capacity and high capacity, to obtain the desired capacity and voltage in the plastic casing with perforated holes on both sides, the front and the top and bottom so that outside air flows. Insert the required unit cells in a row to enable parallel or / and series connection, and then insert the plastic spacers to allow air to flow between the unit cells, and then weld or bolt the Yin-Yang output terminals to the injection-molded plastic cover. It is to provide a module of a lithium polymer battery for an electric vehicle or a hybrid electric vehicle configured by connecting the terminals of the unit battery.

Hereinafter, an embodiment of the present invention will be described in more detail with reference to the accompanying drawings.

<Example 1>

3 shows a 3.8V, 80-100Ah class high capacity lithium polymer battery 1 using a 4-6Ah class small capacity Li polymer battery. The high capacity polymer battery 1 includes a plastic case forming an outer body, a plurality of polymer unit cells 20, a plastic spacer 30, and a plastic top cover 40. It is a structure capable of high capacity without sacrificing energy density while solving the problem of high capacity by inserting a pole plate in a case.

In other words, the inside of the case 10 has a width corresponding to the width of the polymer unit electrons 20, and both sides or upper and lower surfaces of the front and rear sides of the polymer unit electron 20 are supplied so that external air can be supplied. It is made of a structure that can support and maintain the shape. The polymer unit cell 20 in the high capacity battery 1 is a 3.8 V to 4.6 Ah class positive electrode plate 22 having a negative terminal 25 and a positive electrode plate having both terminals 26, as shown in FIG. 4. The electrode plate group composed of the 23 and the polymer electrolyte membrane 24 is inserted into the aluminum foil case 21 to seal the negative terminals 25 and both terminals 26 in a protruding structure.

In addition, the polymer unit cell 20 has a thickness t of 4 to 6 mm, a width w of 100 to 150 mm, a height L of 100 to 150 mm, and a plurality of spaces 11 of the plastic case 10. Are arranged left and right as shown in the drawing. At this time, each of the negative terminal 25 and both terminals 26 are located in the same direction. For example, if all the negative terminals 25 are located at the rear, all the terminals 26 are located at the front.

In addition, in order to facilitate the heat dissipation of the unit cell 20 by the smooth flow of outside air, both side surfaces and the front and rear surfaces of the case 10 are formed with through holes 10b and 10b, and the upper and lower surfaces are connected to yin and yang. A distribution hole 40a is formed between the bars 43 and 44 in a through structure.

The plastic spacers 30 are inserted between the polymer unit cells 20 to form a flow of cooling air between the polymer unit cells 20 to form a gap G of 1 mm. In addition, the spacer 30 is positioned on the upper side and the lower side to maintain the vertical alignment relationship stably, the size of the spacer is equal to the width (w) of the polymer unit cell 20 to enable the air flow in the front and rear direction. In addition, it is possible to arrange a plurality of smaller than the width to enable the flow of air in the front and rear direction and the vertical direction.

Plastic upper cover 40 is made of a structure that is covered on the upper portion of the plastic case 10, the lower surface is formed a structure for connecting the polymer unit cell 20 in parallel. That is, the Pb-Sn alloy surface-treated copper negative connection bar 43 and the positive connection bar 44 connecting each of the negative terminals 25 in a row and connecting the both terminals 26 in a line have a plastic upper cover ( The sound output terminal 41 and the positive output terminal 42 which are connected to each other by welding and connected to the negative connection bar 43 and the positive connection bar 44 at both ends of the upper surface of the cover 40, respectively. It protrudes upward at positions opposite to each other.

Therefore, according to the first embodiment of the present invention configured as described above, due to the characteristics of the polymer battery without the internal gas generation, vents such as cans and gas discharge, which are made thick to withstand pressure like conventional Ni-MH cells (Vent) No structure needed.

Accordingly, in the present invention, the unit cell 20 is made of an aluminum foil case 10 having a simple structure, so that the energy density per weight of the high capacity battery corresponds to about 2 times 70 to 80 Wh / kg of the conventional Ni-MH battery. Can be increased to 130 ~ 140Wh / kg.

In addition, the present invention can solve the problem of deterioration of the characteristics due to the non-uniformity of the electrolyte solution and the non-uniform thermal characteristics of the electrode plate located in the middle of the unit cell when the capacity of the room temperature type lithium polymer unit battery to 30mm or more It is unique to the polymer battery which can solve the above problems without achieving high capacity by using a method such as Ni-MH because there is no gas generation and the ratio of the case to the weight of the battery is particularly small. By using the characteristics of the electric car was possible to employ.

In addition, according to the present invention, the air flow for cooling is uniformly formed by the plastic spacers 30 sandwiched between the polymer unit cells 20, so that effective thermal management is achieved, thereby reducing the temperature variation in the unit cells 20. .

<Example 2>

FIG. 5 is a view showing a 11.4V 80 to 100Ah class polymer battery module 2 for an electric vehicle according to Embodiment 2 of the present invention, wherein the polymer battery module 2 is formed of plastic to form an outer body as in the above-described embodiment. The case 50 includes a plurality of polymer unit cells 60, a plastic spacer 70, and a plastic upper cover 80.

However, in order to be able to output 11.4V, each group (1c) (2c) (3c) is separated into three groups (1c) (2c) (3c) of a high capacity battery constructed in a similar manner to FIG. Made of structure. At this time, the unit cells 60 in each of the groups (1c) (2c) (3c) are the yin and yang terminals (65, 66) in the same direction to be connected in parallel so as to output 3.8V as in the above-described embodiment Yin and Yang terminals 65 and 66 between the groups 1c, 2c, and 3c are positioned in opposite directions so that they can be connected in series, and the yin and yang connecting bars 83 and 84 of the upper cover 80 are positioned. ) Is formed in a structure that can be connected in series with the group located next to.

Accordingly, the polymer battery module 2 according to the second embodiment of the present invention is capable of outputting 11.4 V as each group (1c) (2c) (3c) of 3.8V is connected in series, and other configurations And the operation is the same as in Example 1 described above.

In the drawings, reference numerals 50a, 50b, and 80a denote distribution holes formed in the front, rear, upper, and lower surfaces of the plastic case 50 for air flow. The polymer unit cell 60 is the same as the negative electrode plate 22, the positive electrode plate 23, the polymer electrolyte membrane 24, and the aluminum foil case 21 constituting the polymer unit cell 20 in the first embodiment. Consists of the configuration.

<Example 3>

In the case of the structure to be used in the power assist type hybrid electric vehicle, since the capacity is 5 to 20 Ah class, in the module configuration method of Example 2, the number of unit cells for high capacity is reduced by only 5 to 20 Ah class. The remaining space is connected to a series of 5 ~ 20Ah battery in series to form a high voltage of 20 ~ 70V, the size of the negative electrode connection bar on the upper cover is only the basic configuration method is the same as in the second embodiment.

As described above, the present invention is achieved by arranging the polymer unit cell consisting of an aluminum foil case in parallel in the plastic case of the structure through which the outside air can pass through the air gap is formed by sandwiching the plastic spacer between the unit cells. High-capacity batteries use electrodes arranged in parallel in a single case of 30mm or more like conventional Ni-MH batteries.The nonuniform distribution of electrolytes and thermal problems of electrode plates, which are a problem in high-capacity, make use of the special advantages of polymer batteries. It is possible to easily achieve high capacity batteries while solving high capacity and thermal problems, and to overcome the problems of deterioration of characteristics and life of high capacity batteries such as Ni-MH batteries through effective thermal management of unit cells constituting high capacity batteries. You can do it.

In addition, the present invention is to achieve a high capacity and at the same time the structure of the module having a high voltage by configuring a high capacity battery configuration method as described above to overcome thermal problems and battery life degradation and performance degradation problems caused by temperature variation between unit cells, It has the advantage of easy mounting on electric vehicles and hybrid electric vehicles by facilitating the transport, mounting and handling of the vehicle.

In addition, since the present invention is composed of a polymer battery, each unit cell does not have a breakdown voltage characteristic, so that a vent structure such as Ni-MH can be eliminated, and the thickness and weight of the case can be significantly reduced, and the same pressure resistance as a conventional Ni-MH battery is achieved. There is no need for a steel band to withstand.

Accordingly, the present invention can increase the energy density by simplifying the premise structure constituting the unit cell, the battery module and the battery pack, and thus has an advantage of increasing the driving distance of the vehicle.

While the invention has been shown and described with respect to particular embodiments, those skilled in the art will recognize that various modifications and changes can be made without departing from the spirit and scope of the invention as indicated by the appended claims. Anyone can easily know.

Claims (7)

In constructing a high-capacity battery 10 for supplying power to an electric vehicle or a hybrid electric vehicle and a high-voltage and high-capacity battery module 2 for easy mounting and handling, a plastic having a structure through which external air can flow smoothly Spacers 30 and 70 and polymers sandwiched between the plurality of polymer unit cells 20 and 60 and the unit cells 20 and 60 of a few Ah class in the cases 10 and 50 to form a space therebetween. It characterized in that it comprises a top cover (40) (80) that protrudes the negative output terminal (41) (42) (81) (82) for outputting power by connecting a unit cell to enable high capacity and high voltage High capacity lithium polymer battery and high capacity, high voltage lithium polymer battery module for electric vehicles. The negative electrode plate 22, the positive electrode plate 23, and the polymer electrolyte 24 are covered with the aluminum foil case 21, and the negative terminal (top) of the polymer unit cells 20 and 60 is formed on the polymer unit cells 20 and 60. 25) 65 and a high capacity lithium polymer battery and a high capacity, high voltage lithium polymer battery module for the electric vehicle, characterized in that the structure consisting of protruding both terminals (26) (66). The method of claim 1, wherein the spacers 30 and 70 are less than or equal to 2 mm in a direction enabling air flow in the front and rear directions of the plastic cases 10 and 50 having the polymer unit cells 20 and 60. High capacity lithium polymer battery for electric vehicles and high capacity, high voltage lithium having a bar shape having a thickness, or having a bar shape having a middle cut off thickness of 2 mm or less, which enables air in the front and rear direction and air flow in the vertical direction. Polymer battery module. According to claim 1, wherein the number of the spacers 30, 70 is located between the unit cells is one between each unit cell or between two or three unit cells, or one per four cells A high capacity lithium polymer battery and a high capacity, high voltage lithium polymer battery module for an electric vehicle. According to claim 1, The plastic case 10, 50 is formed in the front and rear and both sides of the distribution holes 10a, 10b, 50a, 50b to facilitate the flow of external air, the cover ( 40 and 80, and the distribution holes (40a, 80a) are formed in the high capacity lithium polymer battery and electric capacity, high voltage of the electric vehicle, characterized in that it has a structure that minimizes the temperature deviation by cooling the unit cell smoothly Lithium Polymer Battery Module. According to claim 1, wherein the case 10, 50, the top cover 40, 80 and the spacer 30, 70 is a high capacity lithium polymer battery and high capacity for an electric vehicle, characterized in that made of a plastic material, High voltage lithium polymer battery module. According to claim 1, wherein the upper cover 40, 80 is parallel to each of the negative terminal 25, 65 and both terminals 26, 66 of the polymer unit cells 20, 60 on the lower surface. Or a connection bar 43, 44, 83, 84 connected in series is connected to the yin and yang output terminals 41, 42, 81, 82 high capacity for an electric vehicle. Lithium polymer battery and high capacity, high voltage lithium polymer battery module.