A composite biomimetic runner liquid cooling plate for battery thermal management

Abstract

The application discloses a composite bionic flow channel liquid cooling plate for battery thermal management, and relates to the technical field of battery thermal management.The composite bionic flow channel is designed in the interior of the liquid cooling plate main body, which is coupled by fishbone-shaped shunt structures arranged along the main flow direction of the cooling liquid and honeycomb-shaped temperature equalizing structures filled between the branches of the fishbone-shaped shunt structures.The fishbone-shaped shunt structures undertake the functions of fluid distribution and low-pressure drop transportation, the honeycomb-shaped temperature equalizing structures are filled between the fishbone branches, and the density of the honeycomb is designed in a gradient that gradually increases along the flow direction, so that the liquid cooling plate main body realizes high heat dissipation efficiency, temperature balance and low resistance along the main flow direction of the cooling liquid, thereby decoupling the fishbone-shaped shunt structures and the honeycomb-shaped temperature equalizing structures in function and coupling them in space, solving the contradiction between "low pressure drop" and "high temperature balance", and achieving perfect combination of high heat dissipation efficiency, excellent temperature balance and low pressure drop energy consumption at the physical mechanism level.

Description

Technical Field

[0001] This invention relates to the field of battery thermal management technology, and in particular to a composite biomimetic flow channel liquid cooling plate for battery thermal management. Background Technology

[0002] As a core component of new energy vehicles, lithium-ion batteries continuously generate heat during operation. In particular, battery modules formed by connecting multiple individual cells in series and parallel have extremely high heat dissipation power. If the heat cannot be dissipated effectively and in a timely manner, the internal temperature of the battery will continue to rise, causing a decline in battery performance, accelerating battery life degradation, and excessive heat accumulation may even trigger thermal runaway, seriously endangering vehicle safety. In fact, the optimal operating temperature range for batteries is 25–40 ℃, and the internal temperature difference needs to be controlled within 5 ℃. To ensure that the battery can operate safely, for a long life, and stably, a battery thermal management system (BTMS) is needed to dissipate heat from the battery, reduce the maximum temperature, reduce the internal temperature difference, and reduce the system's voltage drop (pump work).

[0003] Liquid cooling has become the mainstream solution for battery thermal management due to its high heat exchange efficiency and stable performance. As the core component of the liquid cooling system, the design of the internal flow channel structure of the liquid cooling plate directly determines the heat dissipation capacity, temperature uniformity, and energy consumption level (manifested as inlet and outlet pressure drop) of the entire system. In order to improve the overall performance of the liquid cooling plate, researchers have conducted extensive research on the flow channel structure, which can be mainly divided into two categories: conventional flow channel structure optimization and biomimetic flow channel structure optimization. Conventional flow channel structure optimization, such as direct flow channel, parallel flow channel, and serpentine flow channel, is relatively simple. The coolant continuously absorbs heat from the battery during the flow in a single direction, causing its own temperature to rise continuously along the flow path. This makes the heat exchange effect of the liquid cooling plate strong near the inlet area, but the heat exchange capacity is significantly weakened in the outlet area, thus forming a large temperature gradient on the battery surface along the flow direction. It is difficult to meet the stringent requirements of high-power batteries for temperature uniformity. Therefore, biomimetic flow channel structures are often used at present.

[0004] Bionic flow channel structures are proposed by researchers inspired by the efficient mass and heat transfer networks in nature, such as fishbone, leaf vein, tree, and honeycomb structures. However, the design concept of such single bionic flow channel structures often focuses on optimizing a certain performance index. For example, although fishbone flow channels can achieve low-resistance flow distribution, their fluid distribution network may lead to uneven flow at the end of each branch channel, thus limiting the temperature uniformity effect. While honeycomb and other mesh flow channels have good temperature uniformity, their dense and multi-intersecting structure inevitably introduces huge local flow resistance, resulting in a significant increase in system pump power consumption. Moreover, fluid is prone to forming flow dead zones in complex networks, which weakens local heat exchange efficiency. It can be seen that there is an inherent contradiction between "low pressure drop" and "high temperature uniformity" in the current single bionic structure. This usually results in a significant temperature difference near the inlet and outlet of the flow channel, and the temperature distribution on the battery surface is also uneven. As a result, it is difficult to achieve high heat dissipation efficiency, excellent temperature uniformity, and low pressure drop energy consumption at the same time, and ultimately it is difficult to achieve efficient heat dissipation of batteries in new energy vehicles. Summary of the Invention

[0005] This invention provides a composite biomimetic flow channel liquid cooling plate for battery thermal management, which can solve the problems existing in the prior art.

[0006] This invention provides a composite biomimetic flow channel liquid cooling plate for battery thermal management, including a liquid cooling plate body disposed on one side of the battery, wherein a composite biomimetic flow channel is formed inside the liquid cooling plate body; The composite biomimetic flow channel is composed of a fishbone-shaped flow distribution structure arranged along the mainstream direction of the coolant and a honeycomb-shaped temperature equalization structure filled between each branch of the fishbone-shaped flow distribution structure. The fishbone-shaped flow distribution structure includes multi-level branch channels formed by gradually branching along the main flow direction of the coolant. The topological configuration of the multi-level branch channels follows the fractal law of biomimetic fish bones and is used to guide and distribute the coolant along the main flow direction to various areas within the liquid cooling plate body. The honeycomb-shaped temperature equalization structure is composed of multiple interconnected honeycomb units. In each flow division region along the mainstream direction of the coolant in the fishbone-shaped flow division structure, the number of honeycomb units contained in the honeycomb-shaped temperature equalization structure is increased by one level or a preset increment, so that the honeycomb units along the mainstream direction of the coolant in the composite biomimetic flow channel are gradually denser, which is used to perform step-by-step heat exchange of the coolant along the mainstream direction to maintain the temperature equalization of the liquid cooling plate body.

[0007] Preferably, the honeycomb cells within the honeycomb-shaped temperature-equalizing structure are hexagonal.

[0008] Preferably, the diameters of the composite biomimetic flow channels are equal; The diameter of the composite bionic flow channel can also be set as a variable diameter flow channel, wherein the diameter of the honeycomb unit flow channel near the inlet end of the composite bionic flow channel is larger than the diameter of the honeycomb unit flow channel near the outlet end of the composite bionic flow channel, or the diameter of the honeycomb unit flow channel within the same flow channel branch has a gradually changing structure.

[0009] Preferably, the inner wall surface of the composite biomimetic flow channel is a smooth surface or a rough surface to enhance heat exchange.

[0010] Preferably, the cross-sectional shape of the composite biomimetic flow channel is rectangular, trapezoidal, semi-circular, or triangular.

[0011] Preferably, the number of flow stages, the width and the height of the composite bionic flow channel can be adjusted to adapt to the heat dissipation of battery modules with different power ratings.

[0012] Preferably, the branch channels of the fishbone-shaped flow distribution structure are coupled to the honeycomb cells in the honeycomb-shaped temperature equalization structure through transition rounded corners to reduce the local flow resistance loss of the coolant at the coupling connection.

[0013] Preferably, a thermally conductive interface material layer is provided on the side of the liquid cooling plate body that contacts the battery. The thermally conductive interface material layer is a thermally conductive silicone grease material layer, a thermally conductive pad material layer, a thermally conductive adhesive material layer, or a phase change thermally conductive material layer, which is used to reduce the contact thermal resistance between the liquid cooling plate body and the battery and enhance heat exchange.

[0014] Preferably, the cooling medium of the coolant is an ethylene glycol solution, deionized water, or a fluoride coolant.

[0015] Preferably, the main body of the liquid cooling plate is made of aluminum, copper, or alloy.

[0016] This invention provides a composite biomimetic flow channel liquid cooling plate for battery thermal management, which has the following advantages compared with the prior art: This invention utilizes a composite biomimetic flow channel designed within the main body of a liquid-cooled plate. This channel is composed of a fishbone-shaped flow distribution structure positioned along the main flow direction of the coolant and a honeycomb-shaped heat equalization structure filling the spaces between the branches of the fishbone-shaped flow distribution structure. The fishbone-shaped flow distribution structure acts as a "macroscopic transport skeleton," using an optimized fractal topology to rapidly and uniformly distribute the coolant along a low-resistance path to various areas of the liquid-cooled plate, fulfilling the functions of fluid distribution and low-pressure-drop transport. The honeycomb-shaped heat equalization structure acts as a "microscopic heat exchange network," filling the spaces between the fishbone branches. Its gradient design, with progressively increasing honeycomb density along the flow direction, results in a lower honeycomb density at the inlet section, effectively avoiding unnecessary resistance introduction. At the outlet section, as the heat exchange capacity naturally decreases, the honeycomb density increases accordingly to provide stronger heat exchange compensation. At this point, the fluid is close to the outlet, and its flow path is almost exhausted. The impact of the additional resistance introduced by the increased density on the total pressure drop of the system is minimized. This topology design, which distributes the heat on demand step by step, enables the liquid cooling plate body to achieve high heat dissipation efficiency, temperature uniformity, and low resistance along the mainstream direction of the coolant. Thus, the entire composite biomimetic flow channel decouples the fishbone-shaped flow distribution structure and the honeycomb-shaped heat equalization structure in function and couples them in space, solving the contradiction between "low pressure drop" and "high temperature uniformity". This achieves a perfect balance of high heat dissipation efficiency, excellent temperature uniformity, and low pressure drop energy consumption at the physical mechanism level. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall architecture of the composite biomimetic flow channel provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a battery cooling system provided in an embodiment of the present invention; Figure 3 A schematic diagram of a liquid cooling plate provided in an embodiment of the present invention; Figure 4 This is a comparative schematic diagram of different flow channel structures provided in the embodiments of the present invention; Figure 5 This is a schematic diagram comparing the performance of different flow channel structures provided in the embodiments of the present invention; Figure 6 Temperature cloud maps of battery surfaces with different flow channel structures provided in embodiments of the present invention; Figure 7 Pressure cloud diagrams at the center of different flow channel structures provided for embodiments of the present invention. Detailed Implementation

[0018] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0019] For conventional parallel or serpentine flow channel structures, the coolant continuously absorbs heat during flow, causing its temperature to gradually increase along the flow direction. This results in strong heat dissipation at the battery module inlet area and weaker heat dissipation at the outlet area, creating a significant temperature gradient on the battery surface. This makes it difficult to meet the temperature uniformity requirements of high-power batteries. For single biomimetic flow channels, such as fishbone, leaf vein, and honeycomb shapes, there are certain advantages in improving fluid distribution and enhancing heat transfer. However, different biomimetic structures often focus on improving only one aspect of performance. While honeycomb and other mesh structures have good temperature uniformity, they are often accompanied by large flow resistance, making it difficult to simultaneously meet the requirements of heat dissipation efficiency and low pressure drop.

[0020] To address this, the present invention designs a composite biomimetic flow channel liquid cooling plate that combines efficient flow diversion and temperature uniformity for battery thermal management. This effectively reduces the battery's maximum temperature, temperature difference, and the pressure drop of the entire heat dissipation system. Specifically: I. Composite biomimetic flow channel model.

[0021] Inspired by the excellent heat dissipation performance of biomimetic fishbone and biomimetic honeycomb flow channels, this invention proposes a composite biomimetic flow channel structure with multi-level bifurcation along the flow direction, integrating the features of both types of biomimetic systems, to improve the efficiency of liquid cooling systems, reduce battery temperature accumulation, and improve the uniformity of temperature distribution in individual cells. The composite biomimetic flow channel is as follows: Figure 1 As shown; this structure increases the actual heat exchange contact area between the battery and the flow channel, and adjusts the internal configuration of the flow channel to make the distribution of coolant in each flow channel more balanced, thus enhancing the overall heat exchange capacity. During the flow heat exchange process, the coolant continuously absorbs heat, and its temperature rises along the flow path, gradually decreasing its ability to absorb heat. Conventional flow channels usually exhibit significant temperature differences near the inlet and outlet, and the temperature distribution on the battery surface is more prone to unevenness; for example... Figure 1 As shown, the fluid enters through the right inlet, and the number of honeycomb channels increases progressively in the flow direction. Each time a flow split is completed, the number of honeycomb channels increases by one, and the fluid finally exits through the right outlet; the liquid cooling system is as follows. Figure 2 As shown, the entire model consists of a single battery cell and two liquid cooling plates arranged on both sides of it. The coolant in both liquid cooling plates enters from the right side and flows out from the left side; the structure diagram of the cooling plates is shown below. Figure 3As shown, the dark area represents the fluid structure, and the light area represents the solid cold plate structure. The structural parameters are shown in Table 1.

[0022] Table 1 Model structural parameters II. Numerical calculation of heat dissipation characteristics of composite biomimetic flow channel.

[0023] To compare the differences between the composite biomimetic flow channel proposed in this invention and traditional flow channels, this invention uses Ansys Fluent software to calculate the heat dissipation characteristics of different flow channels on a lithium-ion battery at a 2 C discharge rate. The governing equations are calculated using a pressure-based solver, the velocity-pressure coupling uses the SIMPLE algorithm, the pressure equation uses a second-order scheme, and the momentum and energy equations use a second-order upwind scheme. The convergence criterion is set as follows: the continuity residual is less than 10. -4 The residual of the energy equation is less than 10. -7 The residuals of all other governing equations were controlled within 10. -4 Within; at the same time, the highest temperature of the battery is monitored in real time, and when it tends to be stable, the calculation results are considered to have converged; the following simplifications are made in the numerical simulation: (1) the coolant flows stably, is single-phase and is an incompressible fluid; (2) gravity and contact thermal resistance are ignored; (3) the physical properties of the fluid and solid do not change with temperature; (4) the wall of the cooling plate is thermally insulated and has no slip wall; (5) the cooling plate is a homogeneous isotropic material and the battery is a homogeneous anisotropic material; (6) the cooling medium is a 50% volume fraction ethylene glycol solution and the liquid cooling plate is made of aluminum.

[0024] (1) Governing equations.

[0025] The coolant in the liquid cooling plate is a 50% ethylene glycol solution, and its mass, momentum, and energy conservation equations are as follows: .

[0026] .

[0027] .

[0028] in: ρ l The density of the coolant is expressed in kg·m³. -3 ; Let be the velocity vector of the coolant, in m·s -1 ; P The static pressure of the coolant is expressed in Pa. μ Where is the dynamic viscosity of the coolant, Pa·s; c p,l The specific heat capacity of the coolant, J·kg -1 ·K -1 ;T l The temperature of the coolant, in K; λ l The thermal conductivity of the coolant is expressed in W·m. -1 ·K -1 .

[0029] The energy conservation equation for a liquid-cooled plate is: .

[0030] in: ρ p The density of the liquid cooling plate is expressed in kg·m³. -3 ; c p,p The specific heat capacity of the liquid cooling plate is J·kg. -1 ·K -1 ; T p The temperature of the liquid cooling plate, in K; λ p The thermal conductivity of the liquid cooling plate is expressed in W·m. -1 ·K -1 .

[0031] (2) Boundary conditions.

[0032] The battery pack discharge rate is 2 C. The effect of contact thermal resistance between the liquid cooling plate and the battery is not considered in the calculation. The ambient temperature is set to 30℃, and the initial temperatures of the battery, liquid cooling plate, and inlet coolant are all uniformly set to 30℃. The inlet boundary of the cold plate adopts a velocity inlet condition, the flow state is set to laminar flow, the outlet boundary is a pressure outlet, the initial gauge pressure is 0 Pa, the fluid satisfies the no-slip condition at the flow channel wall, the contact wall between the battery and the cold plate is set as a coupled heat transfer boundary, and the thermal radiation effect is ignored. Transient calculation is used with a time step of 1 s and a time step number of 1800 to simulate and analyze the temperature rise of the battery within 1800 s.

[0033] (3) Evaluation index of heat dissipation performance.

[0034] The Reynolds number is used to distinguish whether a fluid flow is laminar or turbulent, and can be described as follows: .

[0035] .

[0036] in: D h The hydraulic diameter of the channel cross-section, in meters (m). A inlet Let m be the cross-sectional area of ​​the channel entrance. 2 ; C inletLet be the perimeter of the passage entrance, in meters (m). a The length of the channel cross-section, in meters (m). b The width of the channel cross-section, in meters (m). v The flow rate of the coolant is expressed in m / s. -1 .

[0037] Battery temperature difference is defined as: .

[0038] in: T b,max The highest temperature of the battery, in °C; T b,min The lowest temperature of the battery, in °C; Δ T The temperature difference of the battery is expressed in °C.

[0039] The inlet and outlet pressure drop of a liquid cooling plate is defined as follows: .

[0040] in: P in The average inlet pressure of the liquid cooling plate is given in Pa. P out Δ is the average outlet pressure of the liquid cooling plate, Pa; P The pressure drop at the inlet and outlet of the liquid cooling plate is expressed in Pa.

[0041] III. Performance Comparison of Liquid Cooling Plates with Different Flow Channel Structures

[0042] To compare the performance of cold plates with different flow channel structures, this invention compares the performance of traditional direct-flow channels, fishbone channels, and newly designed composite biomimetic channels in terms of maximum battery temperature, temperature difference, and inlet / outlet voltage drop. Diagrams of the different flow channel structures are shown below. Figure 4 As shown, (a) is a fishbone flow channel; (b) is a direct current channel; and (c) is a composite biomimetic flow channel (this invention). The width and height of the flow channel are both set to 2 mm, and the battery discharge rate is 2 C. The study and analysis are conducted at 0.10 m·s. -1 0.15 m·s -1 0.20 m·s -1 0.25 m·s -1 and 0.30 m·s -1 Three flow channel structures at five speeds and the highest battery temperature T max Battery temperature difference Δ T and the pressure drop Δ at the inlet and outlet of the cold plate P The changing pattern.

[0043] Performance comparison of different structures, such as Figure 5 As shown, Figure 5 (a) The effect of different flow channel structures on the highest battery temperature at different inlet velocities.T max Due to the influence of the inlet velocity, the maximum temperature of the battery gradually decreases with increasing inlet velocity in the fishbone flow channel, direct flow channel, and composite biomimetic flow channel liquid cooling plates. T max The decreasing trend of the inlet velocity is becoming smaller and smaller, indicating that the effect of the inlet velocity on the reduction of the maximum temperature is limited; under the condition of constant inlet flow velocity, the composite biomimetic flow channel liquid cooling plate... T max The lowest temperature is reached, and the greater the speed, the greater the difference in the maximum temperature among the three flow channel structures. Figure 5 (b) The effect of different flow channel structures on battery temperature difference Δ at different inlet velocities. T Due to the influence of the inlet velocity, the temperature difference of the battery gradually decreases with the increase of the inlet velocity in the fishbone flow channel, direct flow channel, and composite biomimetic flow channel cold plates; under the condition of constant inlet flow velocity, the Δ of the composite biomimetic flow channel liquid cooling plate... T The lower the temperature, the greater the speed, the greater the temperature difference between the three flow channel structures, and the better the temperature uniformity of the composite bionic flow channel cold plate. Figure 5 (c) The effect of different flow channel structures on the inlet and outlet pressure difference Δ at different inlet velocities. P Due to the influence of the inlet and outlet pressure drops of the three flow channel structures, the pressure drops gradually increase with the increase of the inlet velocity; the composite bionic flow channel cold plate has the lowest pressure drop under different inlet flow velocities, and the difference with the direct flow channel cold plate is very small.

[0044] At an inlet velocity of 0.1 m·s -1 Temperature cloud maps of battery surfaces with different flow channel structures are shown below. Figure 6 As shown in the figure, the composite biomimetic flow channel results in the lowest maximum battery temperature and the best temperature uniformity. The highest battery temperature occurs near the outlet. This is because the coolant flows in from the right and out from the left. During the flow, the coolant temperature gradually increases due to heat exchange, and its flow heat exchange capacity gradually weakens. The unique design of the composite biomimetic flow channel, which gradually stages along the flow direction, improves its temperature uniformity. At an inlet velocity of 0.1 m / s... -1 Pressure cloud diagrams at the center of different flow channel structures are shown below. Figure 7 As shown, the inlet and outlet pressures of the fishbone flow channel cold plate are the highest, while the inlet and outlet pressure drops of the composite bionic flow channel cold plate are the lowest, and the difference between them and the direct flow channel cold plate is very small. The highest pressure of the flow channel occurs at the inlet of the flow channel, and the lowest pressure occurs at the outlet of the flow channel. The pressure of the fluid gradually decreases during the flow process.

[0045] This invention combines biomimetic fishbone flow channels with biomimetic honeycomb flow channels to design a composite biomimetic flow channel liquid cooling plate for battery thermal management, which combines efficient flow distribution and temperature uniformity. This improves battery temperature uniformity while reducing the battery's maximum temperature and system voltage drop. The flow channel's number of stages (N), width (D), and height (H) can be adjusted according to the requirements of the battery thermal management system to meet specific battery operating environments. The flow channel surface can be smooth or rough, and fins can be added to further enhance heat transfer. This composite biomimetic flow channel cooling plate can be used in conjunction with traditional heat dissipation methods (such as phase change materials and heat pipes) to further improve the performance of the battery thermal management system. This composite biomimetic flow channel cooling plate is suitable not only for single batteries but can also be applied to the thermal management of battery modules through multiple parallel connections. The cooling medium is not limited to ethylene glycol but can also be other cooling media such as fluorides and deionized water. The liquid cooling plate material is not limited to aluminum but can also be other materials such as pure copper and alloys with high thermal conductivity.

[0046] The biomimetic honeycomb flow channel in this invention is hexagonal; other alternatives include triangles, rectangles, and other polygons. The flow channels in this invention have equal diameters; alternatives include variable diameter flow channels, such as a larger diameter near the inlet and a smaller diameter near the outlet, or a gradually changing diameter structure for a single flow channel branch. In this invention, the coolant is a 50% ethylene glycol solution, and the liquid cooling plate is made of aluminum; alternatives include replacing the coolant with other working fluids, such as fluorides or deionized water; and changing the material of the cooling plate, such as using copper or alloys.

[0047] The composite biomimetic flow channel of this invention possesses both the efficient transport capacity of a fishbone-type flow divider and the large-area heat exchange capacity of a honeycomb network. The overall convective heat transfer coefficient of the coolant within the flow channel is significantly improved. Compared with a direct-flow channel and a single fishbone flow channel, under the same inlet flow rate and pump power conditions, the composite biomimetic flow channel can more quickly and fully remove the heat generated by the battery, thereby effectively suppressing the rise in the battery's maximum temperature. It can better cope with instantaneous thermal shocks under high-rate discharge or extreme operating conditions, significantly reducing the risk of thermal runaway induced by local overheating, and fundamentally ensuring the operational safety of the battery system.

[0048] The gradient honeycomb structure of this invention provides a finer heat exchange network in the outlet region, increasing the effective heat exchange area and enhancing fluid turbulence and mixing. This effectively compensates for the naturally decaying heat exchange capacity in this region. This compensation mechanism makes the heat exchange intensity of the liquid cooling plate more uniform along the entire flow direction, eliminating the unavoidable phenomenon of "inlet undercooling and outlet overheating" in conventional flow channels. At the same time, the low-resistance guiding characteristics of the fishbone-shaped flow distribution structure undertake the main function of fluid transport, while the gradient distribution of honeycomb density avoids the resistance penalty caused by the high-density network throughout the entire process. It also eliminates the local high-speed jet and eddy current losses caused by uneven fluid distribution in traditional parallel flow channels, making the flow field distribution more uniform and stable.

[0049] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A composite biomimetic flow channel liquid cooling plate for battery thermal management, characterized in that, include: A liquid cooling plate body is disposed on one side of the battery, and a composite biomimetic flow channel is opened inside the liquid cooling plate body; The composite biomimetic flow channel is composed of a fishbone-shaped flow distribution structure arranged along the main flow direction of the coolant and a honeycomb-shaped temperature equalization structure filled between each branch of the fishbone-shaped flow distribution structure. The fishbone-shaped flow distribution structure includes multi-level branch channels formed by gradually branching along the main flow direction of the coolant. The topological configuration of the multi-level branch channels follows the fractal law of biomimetic fish bones and is used to guide and distribute the coolant along the main flow direction to various areas within the liquid cooling plate body. The honeycomb-shaped temperature equalization structure is composed of multiple interconnected honeycomb units. In each flow division region along the mainstream direction of the coolant in the fishbone-shaped flow division structure, the number of honeycomb units contained in the honeycomb-shaped temperature equalization structure is increased by one level or a preset increment, so that the honeycomb units along the mainstream direction of the coolant in the composite biomimetic flow channel are gradually denser, which is used to perform step-by-step heat exchange of the coolant along the mainstream direction to maintain the temperature equalization of the liquid cooling plate body.

2. The composite biomimetic flow channel liquid cooling plate for battery thermal management according to claim 1, characterized in that, The honeycomb-shaped isothermal structure contains hexagonal honeycomb cells.

3. The composite biomimetic flow channel liquid cooling plate for battery thermal management according to claim 1, characterized in that, The composite biomimetic flow channels have equal flow channel diameters; The diameter of the composite bionic flow channel can also be set as a variable diameter flow channel, wherein the diameter of the honeycomb unit flow channel near the inlet end of the composite bionic flow channel is larger than the diameter of the honeycomb unit flow channel near the outlet end of the composite bionic flow channel, or the diameter of the honeycomb unit flow channel within the same flow channel branch has a gradually changing structure.

4. The composite biomimetic flow channel liquid cooling plate for battery thermal management according to claim 1, characterized in that, The inner wall of the composite biomimetic flow channel is either smooth or rough, which is used to enhance heat exchange.

5. A composite biomimetic flow channel liquid cooling plate for battery thermal management according to claim 1, characterized in that, The cross-sectional shape of the composite biomimetic flow channel is rectangular, trapezoidal, semi-circular, or triangular.

6. A composite biomimetic flow channel liquid cooling plate for battery thermal management according to claim 1, characterized in that, The number of flow stages, the width, and the height of the composite biomimetic flow channel can be adjusted to adapt to the heat dissipation of battery modules with different power ratings.

7. A composite biomimetic flow channel liquid cooling plate for battery thermal management according to claim 1, characterized in that, The fishbone-shaped flow distribution structure and the honeycomb cells in the honeycomb-shaped heat dissipation structure are coupled together by transition rounded corners to reduce the local flow resistance loss of the coolant at the coupling connection.

8. A composite biomimetic flow channel liquid cooling plate for battery thermal management according to claim 1, characterized in that, A thermal interface material layer is provided on the side of the liquid cooling plate body that contacts the battery. The thermal interface material layer is made of thermally conductive silicone grease, thermally conductive pad, thermally conductive adhesive, or phase change thermally conductive material, and is used to reduce the contact thermal resistance between the liquid cooling plate body and the battery and enhance heat exchange.

9. A composite biomimetic flow channel liquid cooling plate for battery thermal management according to claim 1, characterized in that, The working fluid of the coolant is ethylene glycol solution, deionized water, or fluoride coolant.

10. A composite biomimetic flow channel liquid cooling plate for battery thermal management according to claim 1, characterized in that, The main body of the liquid cooling plate is made of aluminum liquid cooling plate, copper liquid cooling plate or alloy liquid cooling plate.

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