Liquid-cooled phase-change metal battery support system

Abstract

The application discloses a liquid cooling-phase change material-metal support collaborative thermal management system which can be connected with fire extinguishing medium, comprising a shell, array-arranged cylindrical lithium ion batteries, a phase change material, a metal support and multiple medium flow channels. The metal support comprises a transverse partition plate and a longitudinal heat conduction rib to limit the migration of the molten phase change material and establish a continuous heat conduction path. The medium flow channels are arranged between adjacent batteries in parallel to the battery axial direction and are provided with medium inlets capable of selectively receiving water or fire extinguishing medium. Under normal working conditions, water is connected to the medium flow channels for circulating cooling; when it is determined that the battery abnormally heats, there is a risk of thermal runaway or spontaneous combustion, the water is stopped or reduced and the fire extinguishing medium is connected instead, so as to perform emergency cooling on the abnormal battery, delay the development of thermal runaway and reduce the risk of heat spread.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery thermal management and safety protection technology, specifically to a battery thermal management and fire prevention system that utilizes water cooling, phase change materials and metal supports for synergistic heat dissipation. Background Technology

[0002] Lithium-ion batteries generate a significant amount of heat during high-rate charging and discharging. Excessive battery temperature or uneven temperature distribution within the battery pack can accelerate performance degradation and increase the risk of thermal runaway. Battery thermal management systems typically need to control the maximum battery temperature within a reasonable range while minimizing the temperature difference between individual battery cells.

[0003] Existing phase change material (PCM) cooling structures can passively absorb heat using latent heat, but PCMs have low thermal conductivity and tend to migrate upwards under buoyancy after melting, leading to heat accumulation at the top and uneven distribution of PCM capacity. While adding metal heat-conducting components can shorten the heat conduction path, heat can still accumulate within the PCM under sustained high heat flux conditions. Conventional water-cooling systems are typically only used for temperature control during normal charge and discharge operations. When the battery experiences abnormal temperature rise, thermal runaway, or spontaneous combustion, it is difficult to switch to a dedicated fire extinguishing medium for emergency response in a timely manner. Therefore, a composite thermal management structure with a compact structure, continuous heat conduction path, and both daily temperature control and spontaneous combustion protection is needed. Summary of the Invention I. Technical problems to be solved

[0004] The present invention aims to solve the problems of limited thermal conductivity of phase change materials, easy axial migration of molten phase change materials, insufficient continuous heat dissipation under high-rate conditions, and difficulty in timely introduction of fire extinguishing medium in the event of battery thermal runaway or spontaneous combustion in existing liquid cooling structures. II. Technical Solution

[0005] To address the aforementioned problems, this invention provides a liquid-cooled phase change material-metal support synergistic thermal management system capable of transmitting fire extinguishing media. The system includes a housing, multiple parallel and arrayed cylindrical lithium-ion batteries, a phase change material filling and covering the batteries, a metal support in thermal contact with the batteries, and multiple media flow channels disposed between the batteries.

[0006] The metal support includes transverse partitions and multiple longitudinal thermally conductive ribs. The transverse partitions divide the space containing the phase change material into an upper and lower phase change zone, limiting the overall migration of the molten phase change material between the two zones. The longitudinal thermally conductive ribs establish a continuous heat conduction path between the battery, the transverse partitions, and the media flow channels. The media flow channels are arranged parallel to the battery axis and pass through the transverse partitions, used for selectively delivering water or extinguishing media.

[0007] Preferably, the system includes 16 18650 lithium-ion batteries arranged in 4 rows and 4 columns; 9 medium flow channels are arranged in 3 rows and 3 columns in the gaps between adjacent batteries. The metal support is made of aluminum or aluminum alloy, and the phase change material is a paraffin-based phase change material with a melting point of 304 K; the cooling medium under normal operating conditions is water.

[0008] The medium flow channel has a medium inlet and a medium outlet. The medium inlet can selectively receive water or extinguishing medium. Under normal operating conditions, water is circulated through the medium inlet for cooling. If abnormal temperature rise, thermal runaway risk, or spontaneous combustion of the battery is detected, the water flow is stopped or reduced, and extinguishing medium is introduced instead. The selection and replacement of the medium can be done manually or by external supply equipment. The extinguishing medium can be a water-based extinguishing agent, inert gas, carbon dioxide, or other extinguishing media suitable for lithium-ion batteries. III. Beneficial Effects

[0009] Metal supports shorten the heat transfer path from the battery to the phase change material and the medium flow channel, thereby improving the effective utilization of the phase change material.

[0010] The transverse partitions separate the phase change material into layers, restricting the overall upward movement of the molten phase change material and improving the axial temperature uniformity of the battery pack;

[0011] Water continuously removes heat from the phase change material and the metal support, delaying the phase change material from reaching a fully molten state, thereby improving the continuous heat dissipation capacity under high-rate operating conditions.

[0012] The combination of liquid cooling, phase change heat absorption, and metal thermal conductivity can achieve a good balance between temperature control performance and pumping power consumption.

[0013] The same set of media flow channels can be used for the delivery of fire extinguishing media under normal water cooling and abnormal operating conditions, without changing the channel structure inside the battery module. It can provide emergency cooling for abnormal batteries, delay the development of thermal runaway, and reduce the risk of thermal spread to adjacent batteries. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the thermal management system structure according to an embodiment of the present invention;

[0015] Figure 2 This is a top view of the thermal management system according to an embodiment of the present invention;

[0016] Figure 3 for Figure 1 The diagram shows a cross-sectional view of the thermal management system along the battery axis.

[0017] Figure 4The diagram shows the simulation results of the PCM-only model (Case 1), the PCM-metal support model (Case 2), and the present invention—the PCM-metal support model combined with liquid cooling (Case 3)—at different discharge rates. Figure Labels

[0018] The numbers in the diagram are: 1-Battery module; 10-Cylindrical lithium-ion battery; 20-Phase change material; 21-Upper phase change region; 22-Lower phase change region; 30-Metal support; 31-Transverse partition plate; 32-Vertical thermal rib; 40-Medium flow channel; 41-Medium inlet; 42-Medium outlet; 50-Shell. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings. It should be understood that the embodiments described are for explaining the present invention, and not for limiting the scope of protection of the present invention. In this specification, "upper," "lower," and "axial" all refer to the orientation shown in the accompanying drawings. Example 1: Composite Thermal Management Structure

[0020] like Figures 1 to 3 As shown, battery module 1 is housed within housing 50. Sixteen cylindrical lithium-ion batteries 10, all 18650 lithium-ion batteries, are arranged in a 4x4 grid, with their axes parallel to each other. The outer dimensions of housing 50 are 91 mm × 91 mm × 65 mm; the diameter of each cylindrical lithium-ion battery 10 is 18 mm, its height is 65 mm, and the minimum spacing between adjacent batteries is 3 mm. Phase change material 20 fills the space within housing 50 excluding the batteries, metal support 30, and medium flow channel 40, and contacts the outer wall of each battery.

[0021] The metal support 30 is made of aluminum alloy and includes a transverse partition 31 located in the center of the battery axis and multiple longitudinal thermally conductive ribs 32 extending along the battery axis. The transverse partition 31 is 1 mm thick and separates the phase change material 20 into an upper phase change region 21 and a lower phase change region 22. The longitudinal thermally conductive ribs 32 are disposed between adjacent cells and connected to the transverse partition 31, allowing the heat generated by the battery to diffuse along the longitudinal thermally conductive ribs 32 and the transverse partition 31. This layered structure also restricts the overall upward migration of the molten phase change material under buoyancy.

[0022] Nine medium flow channels 40 are arranged in 3 rows and 3 columns in the gaps between the 4 rows and 4 columns of the battery array. Each medium flow channel 40 is parallel to the battery axis and passes through the transverse partition plate 31. The inner diameter of the medium flow channel 40 is 4 mm, with a medium inlet 41 at the upper end and a medium outlet 42 at the lower end. Under normal operating conditions, water enters from the medium inlet 41 and flows downward along the same axis.

[0023] Phase change material 20 is RT31 paraffin-based phase change material, with a density of 825 kg / m³, a thermal conductivity of 0.2 W / (m·K), a specific heat capacity of 2000 J / (kg·K), a latent heat of phase change of 240800 J / kg, and a melting point of 304 K. Both the initial system temperature and the medium inlet temperature can be set to 298.15 K. Example 2: Operation Mode

[0024] During normal charging and discharging of the battery pack, part of the heat generated by the cylindrical lithium-ion battery 10 is directly transferred to the phase change material 20 and absorbed through the latent heat of phase change. The other part is diffused through the metal support 30 to a wider area of ​​the phase change material 20 and the medium flow channel 40. Cooling water enters the medium flow channel 40 from the medium inlet 41, flows downward along the battery axis, and is discharged from the medium outlet 42, thus forming a heat transfer path that combines metal heat conduction, phase change heat absorption, and forced liquid convection.

[0025] During normal cooling, the inlet flow rate of water is preferably between 0.02 m / s and 0.10 m / s. Within this range, water cooling can significantly reduce the maximum temperature and maximum temperature difference of the battery pack, while keeping the pumping power consumption at a relatively controllable level.

[0026] When it is determined that the cylindrical lithium-ion battery 10 has experienced abnormal temperature rise, poses a risk of thermal runaway, or spontaneously combusts, the flow of water from the medium inlet 41 is stopped or reduced, and instead, a fire extinguishing medium is introduced into the medium flow channel 40. The fire extinguishing medium flows along the medium flow channel 40, absorbing the heat from the abnormal battery through the channel walls, metal support 30, and phase change material 20, and carrying away the absorbed heat from the medium outlet 42. This provides emergency cooling for the abnormal battery, delays the development of thermal runaway, and reduces the risk of thermal spread to adjacent batteries. Example 3: Numerical Verification

[0027] To verify the structural effectiveness, three structures were compared under the same initial temperature and boundary conditions: a structure with only phase change material, a structure with both phase change material and metal support, and the liquid-cooled phase change material-metal support composite structure of the present invention. Numerical simulations were performed using 3C, 4C, and 5C discharge rates.

[0028] Compared to structures containing only phase change materials, the addition of a metal support resulted in a reduction in the maximum battery pack temperature by 0.16 K, 0.32 K, and 0.21 K under 3C, 4C, and 5C discharge conditions, respectively, and a reduction in the maximum temperature difference by 0.32 K, 1.04 K, and 3.12 K, respectively. These results indicate that the metal support and layered structure significantly improve temperature uniformity under medium-to-high rate operating conditions.

[0029] After adding a medium flow channel to the structure of phase change material and metal support, the maximum temperature of the battery pack was further reduced by 0.68 K, 1.00 K and 1.20 K under 3C, 4C and 5C discharge conditions, respectively, and the maximum temperature difference was further reduced by 0.35 K, 0.57 K and 0.69 K, respectively; the final liquid phase fraction of the phase change material was reduced by 0.14, 0.11 and 0.12, respectively, indicating that water removed some heat and delayed the melting of the phase change material.

[0030] Under 5C discharge conditions, when all nine dielectric flow channels adopt a downward, unidirectional flow direction, the highest temperature of the battery pack is 314.34 K, and the maximum temperature difference is 5.08 K. Changing the flow direction of some channels would weaken the cooling effect in critical high-temperature areas. Therefore, it is preferable that all dielectric flow channels adopt a consistent axial flow direction.

[0031] When the water flow rate increases from 0 to 0.20 m / s, the highest temperature of the battery pack decreases from 315.96 K to 313.61 K, and the maximum temperature difference decreases from 5.91 K to 4.58 K; however, the pumping power consumption increases to 1.47 W at 0.20 m / s. Considering both the benefits of temperature control and energy consumption, 0.02 m / s to 0.10 m / s is the preferred inlet flow rate range.

[0032] The above parameters can be adjusted according to battery specifications, heating power, phase change material properties, allowable pumping power consumption, and fire extinguishing medium characteristics. As long as a laterally separated phase change zone, a metal support in thermal contact with the battery, and a medium flow channel located in the battery gap are used, and the supply of fire extinguishing medium can be switched between normal water cooling and abnormal operating conditions, it can fall under the technical concept of this invention.

Claims

1. A liquid-cooled phase change metal support battery thermal management system, comprising a housing, multiple cylindrical lithium-ion batteries, a phase change material, a metal support, and multiple medium flow channels, characterized in that: Multiple cylindrical lithium-ion batteries are arranged in an array; the phase change material is filled in the housing and covers the cylindrical lithium-ion batteries; the metal support is in thermally conductive contact with the cylindrical lithium-ion batteries and includes a transverse partition plate that divides the phase change material into an upper phase change region and a lower phase change region, and multiple longitudinal thermally conductive ribs connected to the transverse partition plate. Multiple media flow channels are arranged parallel to the axial direction of the cylindrical lithium-ion battery between adjacent cylindrical lithium-ion batteries and penetrate the transverse partition plate; The medium flow channel is provided with a medium inlet and a medium outlet. The medium inlet can selectively receive water or fire extinguishing medium to cool the cylindrical lithium-ion battery under normal operating conditions, and to provide emergency cooling by introducing fire extinguishing medium when the cylindrical lithium-ion battery experiences abnormal temperature rise, thermal runaway risk, or spontaneous combustion.

2. The battery thermal management system according to claim 1, characterized in that: The cylindrical lithium-ion battery consists of 16 18650 lithium-ion batteries arranged in 4 rows and 4 columns; the medium flow channel consists of 9 channels arranged in 3 rows and 3 columns between adjacent cylindrical lithium-ion batteries, and the inner diameter of each medium flow channel is 4 mm.

3. The battery thermal management system according to claim 1, characterized in that: The metal support is made of aluminum or aluminum alloy, the transverse partition is located in the axial middle of the cylindrical lithium-ion battery and has a thickness of 1 mm; the phase change material is a paraffin-based phase change material with a melting point of 304 K and a latent heat of phase change of 240800 J / kg.

4. The battery thermal management system according to claim 1, characterized in that: Under normal operating conditions, the inlet temperature of the water flowing into the medium flow channel is 298.15 K, the inlet flow velocity is 0.02 m / s to 0.10 m / s, and the water is in a laminar flow state within the medium flow channel.

5. The battery thermal management system according to claim 1, characterized in that: Under normal operating conditions, water enters the medium flow channel from the medium inlet and flows out from the medium outlet. When the cylindrical lithium-ion battery experiences abnormal temperature rise, poses a risk of thermal runaway, or spontaneous combustion, the water flow is stopped or reduced, and fire extinguishing medium is introduced into the medium flow channel instead, in order to reduce the temperature of the abnormal battery and suppress the development and spread of thermal runaway.

6. The battery thermal management system according to claim 1, characterized in that: The extinguishing medium includes at least one of water-based extinguishing agents, inert gases, carbon dioxide, or perfluorohexanone.

7. The battery thermal management system according to claim 2, characterized in that: The outer dimensions of the casing are 91 mm × 91 mm × 65 mm, the diameter of the cylindrical lithium-ion battery is 18 mm, the height is 65 mm, and the minimum distance between adjacent cylindrical lithium-ion batteries is 3 mm.

8. A battery thermal management and fire prevention method, characterized in that, include: Under normal operating conditions, water is introduced into multiple medium flow channels to remove the heat generated by the cylindrical lithium-ion battery through heat conduction by the metal support, heat absorption by the phase change material, and forced convection of the water. When it is determined that the cylindrical lithium-ion battery has abnormally heated up, has a risk of thermal runaway, or has spontaneously combusted, the water supply to the medium flow channels is stopped or reduced, and fire extinguishing medium is introduced into the medium flow channels instead to provide emergency cooling for the abnormal battery and suppress the development and spread of thermal runaway.

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