A cylindrical lithium-ion battery with thermal management function

Abstract

The present invention relates to the field of thermal management technology for lithium-ion batteries, and in particular to a cylindrical lithium-ion battery with thermal management function. The battery mainly includes a shell, a battery cell, a thermally conductive insulating column, a thermally conductive insulating sealing block, a phase change material, and a heating wire. The battery cell is wrapped by the shell. The shell is a hollow structure, and the thermally conductive insulating column is located in the center. The thermally conductive insulating column is connected to the shell through the thermally conductive insulating sealing blocks at both ends. Phase change material is filled between the shell and the thermally conductive insulating column. The heating wire is wound around the surface of the thermally conductive insulating column. The battery provided by the patent of the present invention can effectively reduce the maximum temperature of the battery and improve temperature uniformity during high-rate charge and discharge by using phase change material in combination with thermally conductive insulating sealing blocks and thermally conductive insulating columns; at low temperatures below zero degrees, the battery cell can quickly reach a safe charge and discharge temperature by short-term electrical heating of the heating wire, and can be maintained for a period of time by relying on the heat preservation effect of the phase change material.

Description

Technical Field

[0001] The patent of this invention relates to the field of thermal management technology of lithium-ion batteries, and specifically to a cylindrical lithium-ion battery with thermal management function. Background Art

[0002] Lithium-ion batteries are currently widely used in various fields due to their excellent charge and discharge performance. Cylindrical lithium-ion batteries are one of the battery types of choice for automotive power batteries. Temperature significantly impacts battery performance and safety, making battery thermal management particularly important. Currently, the main methods for battery thermal management include air cooling, liquid cooling, phase change material cooling, and heat pipe cooling. Liquid cooling systems are widely used in vehicles. For example, Tesla vehicles utilize cooling channels on the outside of cylindrical batteries, with coolant flowing inside. However, these systems present significant challenges, including leakage risk and high energy consumption. In addition to dissipating heat from the batteries to prevent overheating, liquid cooling systems can also heat the coolant and transfer heat to the batteries to restore them to operating temperature when ambient temperatures drop, though this typically takes a long time, and once heating ceases, the battery temperature quickly drops again. Phase change materials, due to their latent heat, can absorb or release significant amounts of heat during melting or solidification. The primary advantage of phase-change materials for battery thermal management is that they can effectively absorb the heat generated by the battery by melting, without consuming additional energy. Choosing the right phase-change temperature for the phase-change material can prevent overheating and maintain a relatively constant temperature. The melted phase-change material stores heat, which it then slowly releases to insulate the battery. However, most current battery designs utilize phase-change materials solely for heat dissipation, lacking a battery structure that fully utilizes both of these advantages to achieve both heat dissipation and heating. Summary of the Invention

[0003] The purpose of the present invention is to provide a cylindrical lithium-ion battery with thermal management function. The structure is ingenious and fully utilizes the advantage of phase change materials that can absorb or release a large amount of heat when melting or solidifying, which can achieve both good heat dissipation effect and effective heating function.

[0004] The cylindrical lithium-ion battery with thermal management function of the present invention comprises a shell, a battery core, a thermally conductive insulating column, a thermally conductive insulating sealing block, a phase change material, and a heating wire;

[0005] The battery core is wrapped by a shell, which has a circular column structure. The thermally conductive insulating column is located in the hollow area in the center of the circular column structure; and the two ends of the hollow area are sealed by thermally conductive insulating sealing blocks. The thermally conductive insulating column is connected to the shell through the thermally conductive insulating sealing blocks at both ends; phase change material is filled between the shell and the thermally conductive insulating column, and the heating wire is wound around the surface of the thermally conductive insulating column.

[0006] As a preferred solution of the present invention, the thermally conductive insulating column and the thermally conductive insulating sealing block, as well as the thermally conductive insulating sealing block and the housing, are tightly matched to achieve the function of encapsulating the phase change material.

[0007] As a preferred solution of the present invention, the heat-conducting insulating column is located at the central axis of the circular column structure, and its two ends are respectively connected to two heat-conducting insulating sealing blocks located at two ends of the battery.

[0008] As a preferred solution of the present invention, the thermally conductive insulating column and the thermally conductive insulating sealing block are made of a thermally conductive insulating material with a thermal conductivity exceeding 3W / (m·K).

[0009] As a preferred solution of the present invention, the phase change material is a solid-liquid organic phase change material, and a space is left as needed during packaging.

[0010] As a preferred embodiment of the present invention, the phase change temperature of the phase change material is selected in the range of 30-45°C, preferably around 35°C.

[0011] As a preferred embodiment of the present invention, the heating wire is wound around the surface of the heat-conducting insulating column, and its two ends are led out from the heat-conducting insulating sealing block on the end face of the battery for connection to electricity. The lead-out part is sealed, and the lead-out part of the heating wire is wrapped with an insulating layer. More preferably, the two ends of the heating wire can be led out from the same end.

[0012] Beneficial effects of the present invention: The cylindrical lithium-ion battery with thermal management function provided by the present invention has an ingenious structural design. When the battery is charged and discharged at a high rate, a good thermal conductivity effect is ensured by the thermally conductive insulating sealing block and the thermally conductive insulating column. The phase change material is used to absorb heat and melt, consume the heat generated by the battery, effectively reduce the maximum temperature of the battery, and at the same time improve the temperature uniformity of the battery; at low temperatures below zero degrees, the battery core can be quickly brought to a safe charging and discharging temperature by short-term electric heating of the heating wire. The reason why a large heating power can be used is that the phase change material melts and absorbs heat as a buffer layer, so that the battery temperature will not be too high, and after the heating is stopped, the melted phase change material is used to release heat during the solidification process to further heat and keep the battery warm, which can maintain the battery core at a safe charging and discharging temperature for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic structural diagram of a cylindrical lithium-ion battery with thermal management function provided by an embodiment of the present invention (cut apart for ease of display).

[0014] Figure 2 The calculation results of the simulation of the embodiment of the present invention (labeled as the new battery on the figure) to demonstrate its effect, specifically the change in the maximum temperature of the battery cell at a 4C rate. The calculation results of the traditional battery are also plotted on the figure for easy comparison.

[0015] Figure 3 The calculation results of the simulation of the embodiment of the present invention (labeled as the new battery on the figure) to demonstrate its effect, specifically the change in temperature uniformity of the battery cell at a 4C rate, using the maximum temperature difference within the battery cell as the measurement indicator. The calculation results of the traditional battery are also plotted on the figure for easy comparison.

[0016] Figure 4 The calculation results of the simulation to reflect the effect of the embodiment of the present invention are specifically the case of heating the battery in a low temperature environment, and the change of the maximum and minimum temperatures in the battery cell over time are obtained.

[0017] Marking instructions: 1-shell, 2-battery core, 3-thermal insulating column, 4-thermal insulating sealing block, 5-phase change material, 6-heating wire. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0019] like Figure 1 Figure 1 shows a cylindrical lithium-ion battery with thermal management functionality, comprising a housing 1, a battery cell 2, a thermally conductive insulating column 3, a thermally conductive insulating sealing block 4, a phase change material 5, and a heating wire 6. The housing 1 is an annular cylindrical structure. The central region of the annular cylindrical structure is a cylindrical hollow area; both ends of the hollow area are sealed by thermally conductive insulating sealing blocks 4. The thermally conductive insulating column 3 is located in the hollow area and is connected to the housing 1 via the thermally conductive insulating sealing blocks 4 at both ends.

[0020] The battery core 2 is wrapped by a shell 1 , a phase change material 5 is filled between the shell 1 and the thermally conductive insulating column 3 , and the heating wire 6 is wound around the surface of the thermally conductive insulating column 3 .

[0021] The cylindrical casing 1 consists of two annular end surfaces at the top and bottom, and two inner and outer cylindrical surfaces. The area enclosed by these four surfaces encloses the battery cell 2; that is, the battery cell 2 is enclosed by the casing 1. The inner cylindrical surface of the casing 1 separates the battery cell 1 from the phase change material 5, allowing for heat transfer.

[0022] The interior of a traditional cylindrical lithium-ion battery cell is mainly wound with a positive electrode separator and a negative electrode layered structure. The hollow structure shell 1 of the cylindrical lithium-ion battery with thermal management function provided by the embodiment of the present invention can still meet the requirements of the layered winding process, so this structure is feasible in production. However, the traditional ear structure is eliminated, which will not be suitable for some traditional embedded battery compartment usage scenarios. However, for the power battery field that the present invention focuses on, normal series and parallel connection can still be achieved by reasonably designing the current collector in the battery and leading it out and then wiring it as needed. Since the focus of the present invention is on the thermal management structure in the hollow structure shell 1 rather than the battery cell 2 itself, some specific structures inside and attached to the battery cell 2 are not described here and are not drawn in the accompanying drawings.

[0023] The thermally conductive insulating column 3, the thermally conductive insulating sealing block 4, and the housing 1 work closely together to encapsulate the phase change material 5. The housing 1 can be made of steel, similar to traditional cylindrical lithium-ion batteries. The thermally conductive insulating column 3 and the thermally conductive insulating sealing block 4 are constructed from insulating materials with high thermal conductivity, such as a silicone ceramic composite material with a thermal conductivity of up to 6 W / (m·K), to achieve good thermal conductivity while ensuring electrical safety. The phase change material 5 can be a solid-liquid organic phase change material with a phase transition temperature of approximately 35°C, which exhibits excellent insulation properties. Since its volume changes slightly when it absorbs heat and melts, it should not be completely filled during packaging; a gap should be left as needed. The heating wire 6 can be made of a commonly used iron-chromium-aluminum alloy and wrapped around the surface of the thermally conductive insulating column 3. Its two ends can be extended from one end of the battery, such as the upper end, to facilitate connection to the battery for heating. The extension of the heating wire 6 does not affect the seal with the phase change material 5. After extension, it must be wrapped with an insulating layer to ensure electrical safety.

[0024] When the battery is charged and discharged at a high rate, the present invention ensures a better thermal conductivity through the thermally conductive insulating sealing block 4 and the thermally conductive insulating column 3, and utilizes the phase change material 5 to absorb heat and melt, consume the heat generated by the battery, effectively reduce the maximum temperature of the battery, and at the same time improve the temperature uniformity of the battery. In order to demonstrate its effect, numerical simulation calculations were carried out. The battery prototype is a traditional 26650 lithium iron phosphate cylindrical lithium-ion battery (with a diameter of 26mm and a height of 65mm), and it is also used as a comparison object; the cylindrical lithium-ion battery with thermal management function provided by the present invention is modified on the basis of the traditional 26650 lithium iron phosphate cylindrical lithium-ion battery to ensure that the capacity remains unchanged. In this embodiment, the radius of the thermally conductive insulating column 3 is set to 1mm, and the radial thickness of the phase change material 5 is set to 2mm. The initial ambient temperature is set to 30°C, and the battery surface is in natural convection heat exchange conditions. The heat generation of battery charging and discharging at the same rate is similar, Figure 2The graph shows the change of the maximum temperature in the battery cell 2 at a 4C rate. The calculation results of the traditional battery are also plotted on the graph for comparison. Generally, it is not desirable for the temperature of a lithium battery to exceed 45°C. It can be seen that the cylindrical lithium-ion battery with thermal management function provided by the present invention has good heat dissipation performance without the need for additional energy consumption, while the maximum temperature of the traditional battery exceeds 46°C. Figure 3 The temperature uniformity change of the single battery is shown. The vertical axis is the maximum temperature difference in the battery cell 2, that is, the difference between the highest temperature and the lowest temperature. Compared with the traditional battery cell, the maximum temperature difference is as high as about 5°C. Thanks to the melting and heat absorption effect of the phase change material 5, the temperature uniformity of the cylindrical lithium-ion battery with thermal management function provided by the present invention is also improved.

[0025] At temperatures below zero, the battery cell 2 can be quickly brought to a safe charge and discharge temperature by short-term electrical heating of the heating wire 6. It is worth noting that the heating wire 6 of the present invention can use a relatively large heating power. The reason why a relatively large heating power can be used is because the phase change material 5 acts as a buffer layer to melt and absorb heat, so that the battery temperature will not be too high. After the heating is stopped, the melted phase change material 5 is used to release heat during the solidification process to further heat and keep the battery warm, which can maintain the battery cell 2 at a safe charge and discharge temperature for a long period of time. In order to demonstrate its effect, numerical simulation calculations were carried out, and the initial ambient temperature was set to -10°C, and the battery surface was in natural convection heat transfer conditions. Generally, compared to discharge, battery charging in a low temperature environment requires a stronger preheating demand, because lithium-ion batteries generally need to be charged above 0°C. The heating power of the heating wire 6 is set to 12W, and the heating time is 120s. Figure 4 The graph shows how the maximum and minimum temperatures within cell 2 of a cylindrical lithium-ion battery with thermal management provided by the present invention change over time. After heating stops for 120 seconds, the melted phase-change material 5 releases heat during solidification, further heating the battery. Therefore, the minimum temperature of cell 2 continues to rise. Although the minimum temperature quickly exceeds 0°C, considering that operating when the maximum temperature difference within the battery cell is too high will affect its performance, safe operation can be resumed after the maximum temperature difference is less than 5°C after 450 seconds. Furthermore, due to the heat preservation function of the phase-change material 5, the battery can remain within the safe operating temperature range for up to 1500 seconds. The heating process of the cylindrical lithium-ion battery with thermal management provided by the present invention is efficient and consumes little energy.

[0026] In addition, the heat dissipation and heating performance of the cylindrical lithium-ion battery with thermal management function provided by the present invention can be further improved by optimizing the size design and material selection of components such as the thermally conductive insulating column 3, the thermally conductive insulating sealing block 4, and the phase change material 5.

[0027] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, various modifications are readily apparent to those skilled in the art. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A cylindrical lithium-ion battery with thermal management function, characterized in that: Mainly includes shell, battery core, thermal insulation column, thermal insulation sealing block, phase change material and heating wire; The battery cell is wrapped by a shell, and the shell is in a circular column structure, and the heat-conducting insulating column is located in the hollow area in the center of the circular column structure; and the two ends of the hollow area are sealed by heat-conducting insulating sealing blocks, and the heat-conducting insulating column is connected to the shell through the heat-conducting insulating sealing blocks at both ends; the shell and the heat-conducting insulating column are filled with phase change material, and the phase change material melts and absorbs heat as a buffer layer, and the phase change temperature selection range of the phase change material is 30-45°C; the heating wire is wound around the surface of the heat-conducting insulating column; the heat-conducting insulating column and the heat-conducting insulating sealing block, as well as the heat-conducting insulating sealing block and the shell are tightly matched to realize the function of encapsulating the phase change material; the heat-conducting insulating column and the heat-conducting insulating sealing block are made of heat-conducting insulating material with a thermal conductivity coefficient exceeding 3W / (m·K); the battery cell and the phase change material are separated by the inner cylindrical surface of the shell; the phase change material is made of solid-liquid organic phase change material, and space is left as needed during packaging; At sub-zero temperatures, the battery core reaches a safe charging and discharging temperature by short-term electrical heating of the heating wire; after heating stops, the melted phase change material releases heat during the solidification process to further heat and keep the battery warm. The thermally conductive insulating column is located at the central axis of the circular column structure, and its two ends are respectively connected to the two thermally conductive insulating sealing blocks located at the two ends of the battery; The heating wire is wound on the surface of the heat-conducting insulating column, and its two ends are led out from the heat-conducting insulating sealing block on the end face of the battery for connecting to electricity. The lead-out part is sealed, and the lead-out part of the heating wire is wrapped with an insulating layer.

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