Battery based on temperature memory alloy self-driven heat pipe-phase change material

Abstract

The invention relates to the technical field of battery thermal management, in particular to a battery based on a temperature memory alloy self-driven heat pipe-phase change material, and mainly solves the technical problems that a continuous heat production working condition is easy to saturate, peak heat dissipation and low-temperature heat preservation cannot be considered, and driving depends on external energy consumption in an existing battery thermal management technology. The battery comprises an insulating box body, a battery module, a phase change material and a self-dispersing heat dissipation assembly, the self-dispersing heat dissipation assembly comprises a supporting piece and a heat pipe, and the supporting piece is made of a memory alloy material. The battery is driven by heat generated by the battery, direct conversion of heat energy-mechanical energy-heat management efficiency can be realized, and the energy utilization efficiency is greatly improved; meanwhile, components such as a pump and a fan of a traditional active heat management system are omitted, the structure is simplified, the whole life cycle cost and the maintenance requirement are reduced, the system adapts to application scenes such as vehicle-mounted application scenes and energy storage application scenes with strict requirements for reliability and economical efficiency, and the heat safety and energy efficiency bottlenecks of a high-magnification fast-charging battery are effectively broken through.

Description

Technical Field

[0001] This invention relates to the field of battery thermal management technology, and in particular to a battery based on a temperature memory alloy self-driven heat pipe-phase change material. Background Technology

[0002] With the global energy structure shifting towards renewable energy, electric vehicles and large-scale energy storage systems are experiencing explosive growth. Lithium-ion batteries, as the core power source, are seeing continuous improvements in energy density and charging speed, especially future-oriented solid-state ternary lithium batteries, which are expected to achieve even higher energy density and greater charging power (≥3C). However, high-power fast charging generates enormous instantaneous heat flow. If this heat cannot be dissipated in time, it will cause a sharp rise in battery temperature, leading to serious safety accidents such as performance degradation, thermal runaway, and even explosion.

[0003] Traditional battery thermal management technologies (such as air cooling and liquid cooling) suffer from drawbacks such as slow response and high energy consumption, especially in handling transient peak heat loads. Phase change materials (PCMs), with their latent heat storage properties, can passively absorb heat generated by the battery, effectively mitigating temperature peaks, and have attracted widespread attention in the field of thermal management. However, pure PCMs have the following inherent technical defects: First, pure PCMs have low thermal conductivity, and heat easily accumulates inside the material, easily reaching phase change saturation under continuous heat generation conditions, thus losing their temperature control capabilities; second, after the phase change of the PCM completes the heat absorption phase change, without active driving force, it is difficult to dissipate heat quickly and return to its initial solid state, failing to meet the thermal management requirements under cyclic operating conditions. In addition, while the heat insulation properties of PCMs help maintain the battery operating temperature in low-temperature environments, their heat insulation properties hinder heat dissipation during the battery heat generation phase; and traditional active thermal management systems consume a large amount of electrical energy for battery preheating under low-temperature charging conditions, and cannot cut off heat dissipation channels as needed, resulting in wasted heat generated by the battery itself and reducing the system's effective energy efficiency.

[0004] Therefore, developing an intelligent thermal management system that can adapt to changes in operating conditions, balance peak heat dissipation and low-temperature insulation, and requires no external energy consumption has become the key to breaking through the bottlenecks of battery thermal safety and energy efficiency. Summary of the Invention

[0005] To overcome the technical shortcomings of existing battery thermal management technologies, such as easy saturation under continuous heat generation conditions, inability to balance peak heat dissipation and low-temperature insulation, and reliance on external energy consumption, this invention provides a battery based on a temperature memory alloy self-driven heat pipe-phase change material.

[0006] This invention provides a battery based on a temperature memory alloy self-driven heat pipe-phase change material, comprising:

[0007] Insulating box;

[0008] The battery module includes multiple vertically arranged battery bars, which are evenly distributed within the insulating box and have gaps between adjacent battery bars.

[0009] Phase change material, which is filled between adjacent battery bars and between the battery bars and the insulating box;

[0010] The self-driven heat dissipation assembly has multiple sets located between adjacent battery bars. The self-driven heat dissipation assembly includes a support member and a heat pipe connected above the support member and arranged vertically. The support member is connected to the bottom of the insulating box and is made of shape memory alloy (SMA). The support member extends along the length direction as the battery bar generates heat to push the heat pipe outward towards the phase change material, and contracts along the length direction as the temperature decreases to drive the heat pipe back inward towards the phase change material.

[0011] Furthermore, the battery rod is a cylindrical lithium-ion battery.

[0012] Furthermore, the phase change material is paraffin.

[0013] Furthermore, the support member is a spring.

[0014] Furthermore, it also includes a heat sink located outside the insulating box and fixed relative to the insulating box, the heat sink being located directly above the heat pipe, and the top of the heat pipe contacting the heat sink when the heat pipe is pushed outward by the support member towards the phase change material.

[0015] Furthermore, the heat sink is an aluminum finned heat sink.

[0016] The technical solution provided by this invention has the following advantages compared with the prior art:

[0017] 1) The battery provided by this invention innovatively constructs a collaborative thermal management system of "PCM latent heat shaving + SMA self-driven heat pipe diversion". It not only uses PCM to solve the problem of sudden increase in heat over time, but also uses SMA as an intelligent thermal switch to automatically wake up the heat pipe heat dissipation path at high temperature, overcoming the key defects of low thermal conductivity and difficulty in recovery after heat dissipation of pure PCM. At the same time, it cuts off the heat dissipation channel at low temperature, reduces the energy consumption of battery preheating, and achieves a dynamic balance between efficient heat dissipation and heat preservation, which greatly improves the system's thermal safety margin and adaptability to continuous high power conditions.

[0018] 2) The battery provided by this invention is driven by heat generated by the battery. It does not require external sensors, controllers, pumps or fans. The temperature deformation of the SMA is directly converted into the mechanical action of heat pipe displacement, realizing the direct and efficient conversion of "thermal energy → mechanical energy → thermal management efficiency", which essentially improves energy utilization efficiency. At the same time, it eliminates complex circuits and continuous power consumption, simplifies the system structure, and conforms to the high-efficiency and energy-saving concept of renewable energy application.

[0019] 3) The battery provided by this invention proposes a dynamic collaborative operation strategy of "latent heat storage - on-demand heat dissipation". The PCM is responsible for suppressing the heat peak in the time dimension, and the heat pipe controlled by SMA is responsible for heat migration and diversion in the spatial dimension. The two work together dynamically to achieve automatic adjustment of thermal management under all working conditions without manual intervention, and adapt to complex working conditions such as high-rate fast charging and low-temperature operation.

[0020] 4) The battery provided by this invention eliminates components such as pumps, fans, and complex flow channels compared to traditional air-cooled / liquid-cooled systems, and has no continuous energy consumption; compared to enhanced PCM with added thermally conductive fillers, it can dynamically improve heat dissipation capacity without the cost and weight increase brought by high thermal conductivity networks; the system has no complex moving and circuit components, has a simple structure, extremely high theoretical reliability and service life, and low maintenance cost throughout the entire life cycle, making it particularly suitable for vehicle-mounted and energy storage applications with stringent requirements for reliability and economy. Attached Figure Description

[0021] Figure 1 A schematic diagram showing the battery at low temperature in an embodiment of the present invention;

[0022] Figure 2 A schematic diagram showing the battery in a high-temperature state according to an embodiment of the present invention;

[0023] Figure 3 A schematic diagram illustrating the battery in a transitional state in an embodiment of the present invention;

[0024] Figure 4 This is a temperature-time comparison curve showing the SMA in full contact and non-contact states in an embodiment of the present invention.

[0025] In the picture:

[0026] 1. Insulating housing; 2. Battery module; 3. Phase change material; 4. Self-driving heat dissipation assembly; 41. Support component; 42. Heat pipe. Detailed Implementation

[0027] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0029] The following is combined Figures 1 to 4 Specific embodiments of the present invention will be described in detail below.

[0030] This embodiment provides a battery based on a temperature memory alloy self-driven heat pipe-phase change material, including an insulating housing 1, a battery module 2, a phase change material 3, and a self-driven heat dissipation component 4.

[0031] The insulating box 1 is used to provide installation space for other components.

[0032] Specifically, the material of the insulating box 1 is not limited. For example, a PC / ABS alloy formed from polycarbonate (PC) and acrylonitrile-butadiene-styrene copolymer (ABS) can be used, which can combine the high temperature resistance and high rigidity of PC with the impact resistance and easy processing of ABS, and has excellent insulation performance; polypropylene (PP) can also be used, which has excellent chemical corrosion resistance, insulation and low temperature resistance, and low density and moderate cost.

[0033] Specifically, the shape of the insulating box 1 is not limited. For example... Figure 1 As shown, the insulating box 1 in this embodiment is a cuboid shape without a lid. In other embodiments, the insulating box 1 can also be designed as a cylinder, a triangular prism, or an irregular shape, and can also be equipped with a lid. However, it should be noted that when the insulating box 1 is equipped with a lid, a clearance hole should be opened on the lid corresponding to the self-driven heat dissipation assembly 4 to ensure that the heat pipe 42 of the self-driven heat dissipation assembly 4 can extend and retract freely.

[0034] The battery module 2 includes multiple vertically arranged battery bars, which are evenly distributed within the insulating box 1 with gaps between adjacent battery bars.

[0035] Specifically, there are no restrictions on the type, quantity, or arrangement of the battery bars. For example... Figure 1 As shown, the battery rod in this embodiment is an 18650 cylindrical lithium-ion battery with six cells arranged in two rows of three cells each. The three cells in the same row are connected in series and the cells in different rows are connected in parallel. The six cells are closely arranged in the insulating box 1, and the aforementioned gap is formed by utilizing the structural characteristics of the cylinder itself.

[0036] It should be noted that the gap between adjacent battery bars is used to fill phase heat material on the one hand, and to install the self-driving heat dissipation component 4 on the other hand.

[0037] It should be noted that since battery module 2 is an existing structure, it has not been explained in detail above. However, the necessary structure of battery module 2 should be taken into account in the actual design, such as the selection of the positive and negative terminals of the battery.

[0038] The phase change material 3 is filled between adjacent battery bars and between the battery bars and the insulating box 1.

[0039] Specifically, the type of phase change material 3 is not limited. For example, in this embodiment, the phase change material 3 is paraffin wax, and the phase change temperature of paraffin wax is selected according to requirements.

[0040] It is easy to understand that phase change material 3, as the main heat storage medium, uses its huge latent heat of phase change to absorb most of the peak heat load in a short period of time.

[0041] The self-driven heat dissipation assembly 4 is provided in multiple sets and located between adjacent battery bars. The self-driven heat dissipation assembly 4 includes a support member 41 and a heat pipe 42 connected above the support member 41 and arranged vertically. The support member 41 is connected to the bottom of the insulating box 1 and is made of shape memory alloy material. The support member 41 extends along the length direction as the battery bar generates heat and rises in temperature to push the heat pipe 42 outward to the outside of the phase change material 3. As the temperature decreases, it contracts along the length direction to drive the heat pipe 42 to retract inward to the inside of the phase change material 3.

[0042] Specifically, the structure of the support member 41 is not limited. For example... Figure 2 As shown, the support member 41 in this embodiment is a spring.

[0043] Specifically, the connection method between the support member 41 and the insulating box 1 is not limited. For example, the bottom end of the support member 41 can be welded to the bottom of the insulating box 1; or the bottom end of the support member 41 can be fixed to the bottom of the insulating box 1 with screws.

[0044] Specifically, the type of shape memory alloy material is not limited. In this embodiment, the shape memory alloy material is Ni-Ti based.

[0045] It should be noted that the phase change temperature of the shape memory alloy material is 3℃-5℃ higher than the upper limit of the phase change material 3. This ensures that if the temperature of the phase change material 3 continues to rise after it has fully absorbed heat, the support component 41 will activate, thus preventing premature heat dissipation.

[0046] It should be noted that the lower part of heat pipe 42 is the evaporation section and the upper part is the condensation section. When heat pipe 42 retracts at low temperatures, its condensation section can be completely placed inside the phase change material 3, or it can partially extend outside the phase change material 3. However, when it extends at high temperatures, the portion of the condensation section outside the phase change material 3 is increased to improve heat dissipation. For example... Figure 1 and Figure 2 As shown, in this embodiment, when the heat pipe 42 retracts at low temperature, part of the condensing section still extends outward from the phase change material 3, while when it extends outward at high temperature, the condensing section extends completely outward from the phase change material 3.

[0047] To improve the heat dissipation effect of heat pipe 42, this embodiment also adds a heat dissipation component fixed to the outside of the insulating box 1. The heat dissipation component is located directly above heat pipe 42, and when heat pipe 42 is pushed outward by support member 41 towards the outside of phase change material 3, the top of heat pipe 42 contacts heat dissipation component.

[0048] It is easy to understand that the heat sink has good thermal conductivity. When the condensation section of the heat pipe 42 comes into contact with the heat sink, it will quickly transfer heat to the heat sink to accelerate the heat dissipation rate.

[0049] Specifically, the type and installation method of the heat sink are not limited. For example, in this embodiment, the heat sink is an aluminum finned heat sink, which is fixed to the outside of the insulating box 1 by a bracket. This part of the structure is not shown in the figure. When the heat pipe 42 retracts at low temperature, an air gap is maintained between its condensing section and the aluminum finned heat sink, or it is isolated by a low thermal conductivity material, resulting in a large thermal resistance. When the SMA is triggered and the heat pipe 42 extends at high temperature, its condensing section is tightly pressed against the bottom of the aluminum finned heat sink, the contact thermal resistance is drastically reduced, and the heat dissipation capacity is greatly improved.

[0050] The working principle of a battery based on a temperature memory alloy self-driven heat pipe and phase change material in this embodiment is as follows:

[0051] At low temperatures, such as Figure 1 As shown, the paraffin is in a solidified state, the spring is in a low-temperature martensitic state and retracted, the condensation section of heat pipe 42 is separated from the aluminum finned heat sink, and the system is kept warm.

[0052] During the heat generation and temperature rise of the battery, paraffin wax first absorbs heat, effectively suppressing the battery temperature rise; this is the first layer of passive safety protection. The paraffin wax gradually melts upon absorbing heat. When the paraffin wax has completely melted while the battery is still generating heat, the temperature of the paraffin wax continues to rise. Figure 3 As shown, at this time, the spring undergoes an austenitic phase transformation due to heat and begins to gradually expand and elongate, driving the heat pipe 42 to move upward, so that the condensation section of the heat pipe 42 is gradually exposed to the outside of the phase change material 3.

[0053] At high temperatures, such as Figure 2 As shown, when the spring is extended to its maximum length, the condensing section of the heat pipe 42 contacts the aluminum finned heat sink to enhance heat dissipation; this is the second layer of active safety protection.

[0054] As heat dissipation is enhanced, the temperature of the paraffin gradually decreases. When the temperature drops to the phase transition temperature of the spring, as... Figure 3 As shown, the spring begins to retract, the condensing section of heat pipe 42 detaches from the aluminum finned radiator and gradually retracts into the lower phase change material 3, and the system returns to a high-insulation state; when the temperature drops to the melting point of paraffin, the paraffin gradually solidifies, eventually switching to... Figure 1 The low temperature state is shown.

[0055] The design parameters of the battery in this embodiment will be described below.

[0056] 1) Heat load estimation:

[0057] Using six 18650 batteries, each with a nominal capacity of 1500mAh and a voltage of 3.7V, and simulating 2C charging (i.e., 3000mA current at twice the capacity rate), considering that heat generated by the battery's internal resistance is the main source, the total heat generation power can be approximately estimated using equation (1):

[0058] ----(1)

[0059] in, For heat load, The charging current is 3A at 2C. The internal resistance of a single battery cell was measured to be 77 mΩ. Given 6 batteries, the total heat load is calculated to be approximately 4W. This value serves as the basis for PCM usage and heat dissipation design.

[0060] 2) PCM dosage calculation:

[0061] The PCM needs to absorb most of the heat generated during the fast charging cycle to maintain the temperature within the phase change plateau. The required mass can be calculated using equation (2):

[0062] ---(2)

[0063] in, For the required quality of PCM, The heat load is 4W. The latent heat of phase transition of paraffin is 200 kJ / kg. The specific heat capacity of paraffin is 2 kJ / kg·K. The fast charging duration is 1200s. Calculations show that 0.02kg of paraffin wax can absorb most of the heat during a single charge. The actual design allows for a safety margin of 0.03kg.

[0064] 3) SMA Selection and Drive Capability Calculation:

[0065] The SMA (Surface Mount Mass Regulator) needs to provide sufficient force to overcome unevenness of the contact surface and mechanical friction, ensuring a sufficiently low interface thermal resistance between the heat pipe and the aluminum finned heatsink. Selection should be based on the performance curves provided by the supplier, ensuring that its restoring force at the target temperature is greater than the sum of the required clamping force and the return spring force. Furthermore, materials with good thermal conductivity, such as thermal grease, can be used to fill the gap between the heat pipe and the aluminum heatsink to enhance thermal conductivity during connection.

[0066] 4) After SMA is triggered, the heat pipe needs to quickly dissipate heat from the PCM. The thermal resistance network of the heat pipe needs to be calculated, including the evaporation section thermal resistance, internal working fluid transfer thermal resistance, condensation section thermal resistance, and contact thermal resistance. The purpose of SMA is to significantly reduce the final contact thermal resistance. By selecting a suitable heat pipe model, ensure its maximum heat transfer capacity is far greater than the system heat load (4W) to guarantee unobstructed heat dissipation. Sufficient safety margins and real-time monitoring measures must be included in the design.

[0067] The performance of the battery in this embodiment will be verified through experiments below.

[0068] 1) Simulated heat source: The 18650 battery pack was subjected to 2C (i.e. 3A) constant current discharge using a discharge load tester;

[0069] 2) Control variables: Manually adjust the contact between the condenser section of heat pipe 42 and the aluminum finned heat sink, and set two states: "no contact" and "SMA simulated full contact" to simulate the working conditions of SMA not being triggered and fully triggered.

[0070] 3) Data Acquisition: A multi-channel temperature monitoring instrument is used to record the temperature of the battery surface, PCM, and insulating housing 1 in real time, recording the temperature-time curves of the entire heating and low-power natural cooling process, such as... Figure 4 As shown, compared with the control group without heat pipe 42 to enhance heat dissipation, the battery surface temperature decreased by about 3°C ​​and the time of the temperature peak was delayed by 5 minutes, indicating that the paraffin fully absorbed the heat load of the battery in a short period of time and the heat pipe 42 dissipated the heat in time.

[0071] 4) Test Results and Analysis:

[0072] First, PCM exhibits a significant peak-shaving effect: during testing, the temperature rise rate of batteries and systems with added PCM slowed down considerably, and a relatively flat temperature plateau appeared, the duration of which was basically consistent with the theoretically calculated PCM phase transition endothermic time. This confirms the effectiveness of PCM as the first line of thermal safety barrier.

[0073] Second, the necessity of SMA-driven "enhanced heat dissipation": In the simulated "non-contact" state, the system temperature continued to rise slowly in the later stages of the temperature plateau, indicating that the PCM phase transition was approaching saturation. In the simulated "SMA full contact" state, the temperature curve showed a clear inflection point after the plateau period, and the temperature rapidly stabilized or even decreased. This indicates that after the efficient heat dissipation channel was established, the system successfully switched from "heat storage as the main function" to "heat dissipation as the main function," avoiding thermal saturation and verifying the crucial role of the second safety barrier.

[0074] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.

Claims

1. A battery based on a temperature memory alloy self-driven heat pipe-phase change material, characterized in that, include: Insulating box (1); The battery module (2) includes multiple vertically arranged battery bars, which are evenly distributed inside the insulating box (1) with gaps between adjacent battery bars. Phase change material (3) is filled between adjacent battery bars and between the battery bars and the insulating box (1); The self-driven heat dissipation assembly (4) is provided in multiple sets and located between adjacent battery bars. The self-driven heat dissipation assembly (4) includes a support member (41) and a heat pipe (42) connected above the support member (41) and arranged vertically. The support member (41) is connected to the bottom of the insulating box (1) and is made of shape memory alloy material. The support member (41) extends along the length direction as the battery bars generate heat and rises in temperature to push the heat pipe (42) outward to the phase change material (3) and contracts along the length direction as the temperature decreases to drive the heat pipe (42) to retract inward to the phase change material (3).

2. A battery based on a temperature memory alloy self-driven heat pipe-phase change material according to claim 1, characterized in that, The battery rod is a cylindrical lithium-ion battery.

3. A battery based on a temperature memory alloy self-driven heat pipe-phase change material according to claim 1, characterized in that, The phase change material (3) is paraffin.

4. A battery based on a temperature memory alloy self-driven heat pipe-phase change material according to claim 1, characterized in that, The support member (41) is a spring.

5. A battery based on a temperature memory alloy self-driven heat pipe-phase change material according to any one of claims 1 to 4, characterized in that, It also includes a heat sink located outside the insulating box (1) and fixed relative to the insulating box (1), the heat sink being located directly above the heat pipe (42), and the top of the heat pipe (42) contacting the heat sink when the heat pipe (42) is pushed outward by the support member (41) towards the phase change material (3).

6. A battery based on a temperature memory alloy self-driven heat pipe-phase change material according to claim 5, characterized in that, The heat sink is an aluminum finned heat sink.

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