Composite power battery thermal management device based on double-layer phase change material and liquid cooling plate

Abstract

The invention discloses a power battery thermal management device based on compounding of a double-layer phase change material and a liquid cooling plate, the device comprises a battery box body (1), batteries (2), the liquid cooling plate (3), a micro-channel (4), a first layer of phase change material (5) and a second layer of phase change material (6), the batteries (3) are sequentially arranged in the middle of the battery box body (1) along the thickness direction; the first layer of phase change material (5) and the second layer of phase change material (6) are filled between the battery (2) and the liquid cooling plate (3), and the heat conductivity coefficient of the second layer of phase change material (6) close to the battery is smaller than that of the first layer of phase change material (5) close to the liquid cooling plate. Through two layers of phase change materials with different heat conductivity coefficients, the low-heat-conductivity-coefficient phase change material absorbs heat by virtue of phase change latent heat to serve as a heat transfer buffer area to improve the temperature uniformity of the battery pack, and the high-heat-conductivity-coefficient phase change material strengthens heat transfer to reduce the highest temperature of the battery pack and improve the efficiency and the stability of battery heat management.

Description

Technical Field

[0001] The present invention relates to the technical field of battery thermal management in an energy storage system, and in particular to a composite power battery thermal management device based on a double-layer phase change material and a liquid cooling plate. Background Art

[0002] The rapid expansion of the new energy vehicle industry has made the performance and safety of power batteries, which are its heart, the focus. During the charging and discharging process, the battery will release a lot of heat energy. If it cannot be effectively managed, it will damage the battery performance and shorten the service life, and may even cause safety accidents. Therefore, battery thermal management technology has become the key to industry research. At present, thermal management technologies mainly include air cooling, liquid cooling, thermoelectric cooling, heat pipe technology, and the use of phase change materials. In particular, liquid cooling has been widely adopted in the market due to its excellent cooling effect. Liquid cooling cools the battery by absorbing and discharging heat through circulating liquid, but there are problems such as uneven cooling and high energy consumption. Phase change material thermal management uses the characteristics of materials absorbing or releasing a lot of heat during phase change, which helps to stabilize the battery temperature and reduce the impact of temperature fluctuations, but its thermal conductivity is poor and the volume expands when absorbing heat. In order to combine the advantages of both, researchers began to study liquid cooling and phase change material composite thermal management technology. Although this technology has potential, it is still under research and faces many challenges, such as composite material preparation, system structure design, cooling strategy, etc.

[0003] Liquid cooling and phase change material cooling each have the advantages required for battery thermal management, but they also have limitations. Combining the two is a promising research direction. In existing composite thermal management systems, phase change materials are usually filled in the battery gap, and liquid cooling is directly in contact with the battery side. This system can improve temperature uniformity and reduce the maximum temperature, but the temperature of the coolant still rises rapidly, making it difficult to achieve ideal temperature uniformity. In addition, the contact area between liquid cooling and phase change material is limited, which may cause the liquid phase rate of the phase change material to rise rapidly. For example, the Chinese patent with publication number CN220189776U discloses a battery temperature control device coupled with a two-stage phase change material and a liquid, which includes alternately stacked square batteries and two-stage phase change material plates, a liquid cooling plate, and ribs placed around the battery pack and cross-placed with the battery pack; the two-stage phase change material plate is divided into two layers, which are filled with metal phase change material and organic phase change material respectively; but in this structure, the role of the two-stage phase change material plate is not obvious, and there is no explanation of the advantages of the two-stage phase change material compared with the single use of organic phase change material or the single use of metal phase change material. Under this structure, the battery is in contact with the liquid cooling plate and the phase change material plate at the same time, and the two cooling methods cool the battery at the same time. The temperature control device using a single phase change material with good thermal conductivity may have better heat dissipation performance, and gallium is corrosive to metals and can form alloys with multiple metals at a lower temperature. In addition, a two-stage phase change material plate is required between every two batteries. If the number of batteries is large enough, its structure is too complicated.

[0004] Therefore, how to maintain the temperature uniformity of the battery module while reducing the maximum temperature of the battery module is a research hotspot in this field. Summary of the invention

[0005] The purpose of the present invention is to provide a power battery thermal management device based on a double-layer phase change material and a liquid cooling plate composite, which can effectively improve the efficiency and stability of battery thermal management, while maintaining the temperature uniformity of the battery module while reducing the maximum temperature of the battery module.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A power battery thermal management device based on a double-layer phase change material and a liquid cooling plate, the device comprising a battery case, a battery, a liquid cooling plate, a microchannel, a first layer of phase change material, and a second layer of phase change material. The batteries are arranged in sequence along the thickness direction and placed in the middle of the battery case. The first layer of phase change material and the second layer of phase change material are filled between the battery and the liquid cooling plate. The thermal conductivity of the second layer of phase change material close to the battery is smaller than the thermal conductivity of the first layer of phase change material close to the liquid cooling plate.

[0008] The present invention sets two layers of phase change material with different thermal conductivity coefficients: the first layer of phase change material close to the liquid cooling plate has a high thermal conductivity coefficient, which can improve the temperature heat transfer efficiency, thereby enhancing heat transfer and reducing the maximum temperature of the battery pack; the second layer of phase change material close to the battery has a low thermal conductivity coefficient and serves as a heat conduction buffer zone, which mainly relies on the latent heat of phase change to absorb heat, and serves as a heat transfer buffer zone to improve the temperature uniformity of the battery pack; thereby helping to improve the efficiency and stability of battery thermal management. Compared with the use of composite phase change material coupled with a liquid cooling plate, the former will form a thin layer of only traditional phase change material, which slows down the speed of heat transfer to the coolant, reduces the temperature difference between the coolant inlet and outlet, and improves the temperature uniformity of the battery pack to a certain extent.

[0009] Preferably, the first layer of phase change material includes a single phase change material, the second layer of phase change material is a composite phase change material including a single phase change material and a thermal conductive material, and the single phase change material in the first layer of phase change material and the second layer of phase change material are the same.

[0010] Preferably, the material of the single phase change material is selected from paraffin or calcium chloride hexahydrate. In the present invention, the second layer of phase change material close to the battery is a single traditional phase change material with low thermal conductivity: such as paraffin (thermal conductivity is generally 0.1-0.5W / (m K)) and calcium chloride hexahydrate (thermal conductivity is generally 0.8-1.2W / (m K)). The first layer of phase change material close to the liquid cooling plate is a composite phase change material with high thermal conductivity: such as paraffin and calcium chloride hexahydrate with added expanded graphite (thermal conductivity varies according to the content of expanded graphite, generally greater than 3W / (m K)).

[0011] Preferably, the organic phase change materials are all located in the hollow aluminum plate, so as to solve the leakage problem caused by the volume expansion of the phase change material after melting and the problem of mixing of two different phase change materials.

[0012] The thickness of the second phase change material layer is less than that of the first phase change material layer. Preferably, the thickness of the second phase change material layer is 1 / 7 to 1 / 2 of the thickness of the first phase change material layer.

[0013] Preferably, the thickness of the first layer of phase change material is 4-7 mm; the thickness of the second layer of phase change material is 1-3 mm.

[0014] It can be understood that the first layer of phase change material and the second layer of phase change material are separated by the aluminum baffle in the battery case so that they are in their respective areas and not in direct contact, thereby preventing the phase change materials from leaking and mixing with each other after melting.

[0015] Preferably, the liquid cooling plate and the baffle containing the battery box are made of aluminum.

[0016] Preferably, a microchannel is provided in the liquid cooling plate, and the microchannel is connected to the cooling liquid inlet main pipeline and the cooling liquid outlet main pipeline through the battery box respectively, and the flow direction of the cooling liquid in the microchannel is upward in and downward out.

[0017] Preferably, the flow channel is in a Z-shape, a U-shape or a J-shape.

[0018] Furthermore, the battery box has holes at the inlet and outlet positions corresponding to the liquid cooling plate flow channel, so that the liquid cooling plate can pass through the wall of the battery box and be connected to the cooling liquid inlet main pipeline and the cooling liquid outlet main pipeline.

[0019] Preferably, the battery is a square battery, and the two layers of phase change material are located on the side of the battery with a larger thermal conductivity.

[0020] The geometric dimensions of the liquid cooling plate channel and the geometric dimensions of the phase change material layer of the battery thermal management device provided by the present invention can be adjusted accordingly according to different working scenarios.

[0021] Specifically, the power battery thermal management device based on a double-layer phase change material and a liquid cooling plate provided by the present invention includes two liquid cooling plates in direct contact with a high thermal conductivity layer, multiple batteries are closely arranged in the thickness direction, and phase change materials are filled between the batteries and the liquid cooling plates. The internal structure of the square battery is mostly a stacking of collector-electrode-diaphragm-electrode-collector along the thickness direction of the battery, so the thermal conductivity of the battery along the thickness direction is small, and the battery, phase change material and liquid cooling plate are arranged accordingly. Therefore, the arrangement of batteries, phase change materials and liquid cooling plates used in the battery thermal management device provided by the present invention takes into account the anisotropy of battery thermal conductivity, forming a simple structure that is conducive to heat dissipation and reduces the volume occupied.

[0022] The battery thermal management device provided by the present invention has a higher heat transfer efficiency than a liquid cooling plate using a single traditional phase change material. The heat of the latter may be accumulated in a thin layer of phase change material close to the battery and cannot be transferred out, and the maximum temperature of the battery cannot be effectively controlled.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The power battery thermal management device based on the composite of double-layer phase change material and liquid cooling plate provided by the present invention improves the disadvantage of low thermal conductivity of traditional phase change material by compounding the liquid cooling plate with two layers of phase change material with different thermal conductivity; by contacting the phase change material with high thermal conductivity (first layer of phase change material) with the liquid cooling plate to improve the heat transfer efficiency of the phase change material and the liquid cooling plate in this area, in the thin layer area of ​​low thermal conductivity phase change material (second layer of phase change material) close to the battery pack, the heat conduction is slow, and most of the heat is absorbed in the form of latent heat of the phase change material, avoiding the rapid transfer of heat to the coolant and causing the temperature difference between the coolant inlet and outlet to rise rapidly, and improving the temperature uniformity of the battery module to a certain extent; at the same time, the flow rate of the coolant can be adjusted according to the different working conditions of the battery to dissipate heat from the battery module more effectively. Therefore, the device provided by the present invention can effectively improve the efficiency and stability of battery thermal management. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of a power battery thermal management device based on a double-layer phase change material and a liquid cooling plate composite provided by the present invention;

[0026] Figure 2 It is a top view of a power battery thermal management device based on a double-layer phase change material and a liquid cooling plate provided by the present invention;

[0027] Figure 3 It is a schematic diagram of the overall structure explosion of a power battery thermal management device based on a double-layer phase change material and a liquid cooling plate provided by the present invention;

[0028] Figure 4 It is a schematic diagram of the maximum temperature of a battery module in a power battery thermal management device composited with a double-layer phase change material and a liquid cooling plate provided in Example 1 and a single phase change material after 3C discharge;

[0029] Figure 5 It is a schematic diagram of the maximum temperature difference of the battery module in the power battery thermal management device of the double-layer phase change material and the liquid cooling plate composite provided in Example 1 and the battery module using a single phase change material after 3C discharge;

[0030] Figure 6 It is a schematic diagram of the battery module in the power battery thermal management device of the double-layer phase change material and the liquid cooling plate composite provided in Example 1 and the phase change material liquid fraction after 3C discharge using a single phase change material;

[0031] Among them: 1. battery box, 2. battery, 3. liquid cooling plate, 4. microchannel, 5. first layer of phase change material, 6. second layer of phase change material. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0033] like Figure 1-Figure 3 As shown, the present invention provides a power battery thermal management device based on a double-layer phase change material and a liquid cooling plate, comprising:

[0034] Batteries 2, which are arranged in sequence along the thickness direction and are placed between the second layer of phase change material 6;

[0035] The first layer of phase change material 5 and the second layer of phase change material 5 are located between the liquid cooling plate 3 and the second layer of phase change material 6 .

[0036] A second layer of phase change material 6, the second layer of phase change material 6 covers the battery 2 on both sides of the battery 2;

[0037] A liquid cooling plate 3, the liquid cooling plate 3 is in direct contact with the first layer of phase change material 5, and is used to improve the heat transfer efficiency and ensure that the phase change material will not be completely melted;

[0038] The cooling liquid inlet and cooling liquid outlet of the microchannel 4 of the liquid cooling plate 3 extend outwards and are connected to the cooling liquid main channel;

[0039] The battery box 1 wraps the battery 2, the first layer of phase change material 5, the second layer of phase change material 6 and the liquid cooling plate 3 therein, and the aluminum baffle in the battery box 1 separates the first layer of phase change material 5 from the second layer of phase change material 6.

[0040] Specifically, as an implementation method, the present invention provides a power battery thermal management device based on a double-layer phase change material and a liquid cooling plate, comprising:

[0041] Battery box 1, battery 2, liquid cooling plate 3, microchannel 4, first layer of phase change material 5 and second layer of phase change material 6. The battery 2 is arranged in sequence in the thickness direction and placed in the middle position. The liquid cooling plate 3 is arranged on both sides of the battery 2 with a gap. The first layer of phase change material 5 and the second layer of phase change material 6 are filled between the battery 2 and the liquid cooling plate 3. The microchannel 4 of the liquid cooling plate 3 extends outward through the wall of the battery box 1 at the position of the coolant inlet and the coolant outlet, and is connected to the coolant inlet main pipeline and the coolant outlet main pipeline. The coolant passes from the coolant inlet main pipeline through the Z-shaped microchannel 4 to the coolant outlet main pipeline.

[0042] The liquid cooling plate 3 and the hollow plate with two layers of phase change material are made of aluminum material, the battery box 1 is made of aluminum or stainless steel material, and the portion of the liquid cooling plate 3 passing through the battery box 1 is sealed by welding.

[0043] The coolant flows in the microchannel 4 in a direction of upward inflow and downward outflow; the height of the battery box 1 is greater than the height of the battery 2 .

[0044] Example 1

[0045] like Figure 3 As shown, the battery 2, the liquid cooling plate 3, the first layer of phase change material 5 and the second layer of phase change material 6 are arranged symmetrically.

[0046] The battery case of this embodiment is made of aluminum material to reduce weight. The thickness of the battery case 1 is 2 mm, the thickness of the baffle separating the two layers of phase change material in the case is 0.5 mm, the thickness of the liquid cooling plate 3 is 4 mm, the thickness of the first layer of phase change material 5 is 5 mm, and the thickness of the second layer of phase change material 6 is 1 mm. The first layer of phase change material 5 is calcium chloride hexahydrate with a melting temperature of 30°C, and the second layer of phase change material 6 is a composite phase change material formed by expanded graphite and calcium chloride hexahydrate.

[0047] Figure 4 A schematic diagram of the maximum temperature of the battery module after 3C discharge in the power battery thermal management device based on a double-layer phase change material and a liquid cooling plate composite provided in this embodiment, wherein in the abscissa, control group 1 represents a single phase change material calcium chloride hexahydrate with low thermal conductivity for both layers of phase change material, and control group 2 represents a single composite phase change material (composed of calcium chloride hexahydrate and expanded graphite) with high thermal conductivity for both layers of phase change material; Figure 4 It can be seen that the maximum battery temperature of the device provided in this embodiment is lower than the maximum battery temperature of the control group 1. Although the maximum battery temperature is higher than the maximum battery temperature of the control group 2, it is still within the ideal operating temperature range.

[0048] Figure 5 Schematic diagram of the maximum temperature difference of the battery module after 3C discharge in the power battery thermal management device based on the double-layer phase change material and the liquid cooling plate provided in this embodiment; Figure 5 It can be seen that the temperature difference of the battery module using the high thermal conductivity single-layer phase change material of the control group 2 has exceeded the ideal operating temperature difference (5°C).

[0049] Figure 6 It is the liquid fraction of the phase change material of the battery module after 3C discharge in the power battery thermal management device based on the double-layer phase change material and the liquid cooling plate provided in this embodiment. The liquid fraction in the device provided in this embodiment is between the two control groups.

[0050] Example 2-3

[0051] The power battery thermal management device based on a double-layer phase change material and a liquid cooling plate provided in Examples 2-3 can refer to Example 1, except that the thickness of the first layer of phase change material 5 is 4 mm and 6 mm respectively.

[0052] Embodiment 4-5

[0053] The power battery thermal management device based on a double-layer phase change material and a liquid cooling plate provided in Examples 4-5 can refer to Example 1, except that the thickness of the second layer of phase change material 6 is 1.5 mm and 2 mm respectively.

[0054] Example 6

[0055] The power battery thermal management device based on a double-layer phase change material and a liquid cooling plate provided in this embodiment can refer to Example 1, except that the first layer of phase change material 5 is paraffin with a melting point of 35°C, and the second layer of phase change material 6 is a phase change material composite of expanded graphite and paraffin.

[0056] In summary, the power battery thermal management device provided by the present invention has a simple structure. The heat generated by the battery is first absorbed by the second layer of phase change material 6 in the form of latent heat. The heat conduction in this area is slow, and the lack of direct contact with the liquid cooling plate 3 can reduce the temperature difference between the liquid inlet and outlet in the liquid cooling plate 3, thereby improving the temperature uniformity of the battery pack. In the area of ​​the first layer of phase change material 5, the phase change material in this area is a composite of high thermal conductivity material and traditional phase change material, with good thermal conductivity. The heat transfer efficiency between the liquid cooling plate 3 and the phase change material is enhanced, and the liquid cooling takes away the heat in the phase change material, making it difficult for the phase change material to melt completely. The entire heat dissipation device effectively improves the heat dissipation efficiency of the battery and extends the service life of the battery.

[0057] Although the methods disclosed in the embodiments of the present application are as above, the contents described are only implementation methods adopted for ease of understanding. Any ordinary technician in the field should understand that any modifications and changes can be made in the form and details of implementation without departing from the spirit and scope disclosed by the present invention. However, the scope of patent protection of the present invention shall still be based on the scope defined by the attached claims.

Claims

1. A power battery thermal management device based on a double-layer phase change material and a liquid cooling plate, characterized in that: The device comprises a battery box (1), a battery (2), a liquid cooling plate (3), a microchannel (4), a first layer of phase change material (5), and a second layer of phase change material (6); the battery (3) is arranged in sequence along the thickness direction and placed in the middle of the battery box (1); the first layer of phase change material (5) and the second layer of phase change material (6) are filled between the battery (2) and the liquid cooling plate (3); and the thermal conductivity of the second layer of phase change material (6) close to the battery is smaller than the thermal conductivity of the first layer of phase change material (5) close to the liquid cooling plate.

2. The power battery thermal management device based on a double-layer phase change material and a liquid cooling plate composite according to claim 1, characterized in that: The first layer of phase change material (5) comprises a single phase change material, the second layer of phase change material (6) is a composite phase change material comprising a single phase change material and a thermal conductive material, and the single phase change material in the first layer of phase change material (5) and the second layer of phase change material (6) is the same.

3. The power battery thermal management device based on a double-layer phase change material and a liquid cooling plate composite according to claim 2 is characterized in that: The material of the liquid cooling plate (3) is aluminum; the material of the single phase change material is selected from paraffin or calcium chloride hexahydrate, and the material of the heat conductive material is selected from expanded graphite or hexagonal boron nitride.

4. The power battery thermal management device based on a double-layer phase change material and a liquid cooling plate composite according to claim 1, characterized in that: The thickness of the second layer of phase change material (6) is smaller than the thickness of the first layer of phase change material (5).

5. The power battery thermal management device based on a double-layer phase change material and a liquid cooling plate composite according to claim 4 is characterized in that: The thickness of the first layer of phase change material (5) is 4 to 7 mm; the thickness of the second layer of phase change material (6) is 1 to 3 mm.

6. The power battery thermal management device based on double-layer phase change material according to claim 1, characterized in that: The liquid cooling plate (3) is provided with a microchannel (4), and the flow direction of the cooling liquid in the microchannel (4) is upward in and downward out.

7. The power battery thermal management device based on a double-layer phase change material and a liquid cooling plate composite according to claim 6, characterized in that: The microchannel (4) is in a Z-shape, a U-shape or a J-shape.

8. The power battery thermal management device based on a double-layer phase change material and a liquid cooling plate composite according to claim 6, characterized in that: The inlet and outlet positions of the microchannel (4) are consistent with the vacant positions of the battery box (1).

9. The power battery thermal management device based on a double-layer phase change material and a liquid cooling plate composite according to claim 1, characterized in that: The battery (2) is a square battery, and the first layer of phase change material (5) and the second layer of phase change material (6) are located on the side of the battery (2) with a larger thermal conductivity.

10. The power battery thermal management device based on a double-layer phase change material and a liquid cooling plate composite according to claim 1, characterized in that: The height of the battery box (1) is greater than the heights of the first layer of phase change material (5), the second layer of phase change material (6) and the battery (2).

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