Sandwich type embedded composite liquid cooling plate and method suitable for 314ah large capacity lithium iron phosphate energy storage cell

Abstract

The application discloses a sandwich embedded composite liquid cooling plate and method suitable for 314Ah large-capacity lithium iron phosphate energy storage cell, the liquid cooling plate is an integrated sandwich structure, which is composed of two metal heat-conducting shell layers and an intermediate functional layer, a plurality of parallel microchannels are arranged in the intermediate functional layer, and the gaps between the channels are filled with aerogel thermal insulation materials, so that active liquid cooling heat dissipation and passive thermal insulation blocking are integrated. The application adopts the parallel microchannel layout, cooperates with the ethylene glycol aqueous solution cooling fluid, and can significantly reduce the flow channel pressure drop and improve the heat exchange uniformity at a low flow rate, and effectively blocks the cell thermal runaway propagation. The application highly integrates the liquid cooling and thermal insulation functions, has an ultrathin and compact structure, greatly improves the volume energy density of the energy storage system, reduces the circulating energy consumption, solves the problems of the traditional scheme, such as large thickness, high pressure drop, uneven heat exchange, insufficient thermal runaway blocking capacity and the like, and is suitable for the thermal management and thermal safety protection of large-capacity energy storage power station battery modules.

Description

Technical Field

[0001] This invention belongs to the field of battery thermal safety, specifically relating to a sandwich-type embedded composite liquid cooling plate suitable for 314Ah large-capacity lithium iron phosphate energy storage cells, a battery thermal management system including the liquid cooling plate, and a thermal runaway suppression method based on the structure. It is mainly applied to the thermal management and thermal runaway propagation blocking of battery modules in large-scale energy storage power stations and containerized energy storage systems. Background Technology

[0002] Against the backdrop of the rapid development of the energy storage industry, 314Ah high-capacity lithium iron phosphate batteries have become the mainstream cell specification for large-scale energy storage power stations due to their high energy density, long cycle life, and high safety. As cell capacity increases and system integration continues to improve, the risk of battery thermal runaway increases significantly. Thermal runaway of a single cell can easily trigger a chain reaction of thermal propagation at the module and battery cluster levels, causing serious safety accidents such as fires and explosions.

[0003] Current energy storage battery thermal management and thermal runaway suppression technologies have the following shortcomings: 1. Passive insulation solutions are too thick, with conventional aerogel insulation components reaching 2-3mm in thickness, significantly occupying module space and reducing system volumetric energy density; 2. Traditional liquid cooling plates often use serpentine flow channels, resulting in long flow paths, large pressure drops, and poor heat exchange uniformity. Under thermal runaway conditions, the flow velocity needs to be significantly increased to suppress propagation, leading to a significant increase in system pump consumption; 3. The liquid cooling, insulation, and support structures are layered and stacked, resulting in a large overall thickness, complex assembly, and structural redundancy, further compressing the space for cell placement; 4. The selection of cooling fluids is unreasonable, with some high-ignition-point fluids having excessively high viscosity, leading to excessively high flow resistance, insufficient heat exchange efficiency, and poor adaptability to low-temperature environments.

[0004] The aforementioned problems make it difficult for existing technologies to simultaneously meet the requirements of ultra-thin integration, low resistance and high efficiency, and low flow rate to prevent thermal runaway, thus failing to meet the thermal safety protection needs of 314Ah high-capacity energy storage cells. Therefore, developing a composite liquid cooling plate that integrates liquid cooling and thermal insulation, has a compact structure, low energy consumption, and high reliability, as well as a method for suppressing thermal runaway, has become a pressing technical challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a sandwich-type embedded composite liquid cooling plate and method suitable for 314Ah high-capacity lithium iron phosphate energy storage cells. It integrates active liquid cooling heat dissipation and passive aerogel insulation into one unit, achieving efficient heat exchange and blocking thermal runaway propagation in an ultra-thin structure, thereby improving the system's energy density and operational safety.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A sandwich-type embedded composite liquid cooling plate suitable for 314Ah high-capacity lithium iron phosphate energy storage cells, featuring a sandwich layered structure integrating liquid cooling and thermal insulation, including: Two layers of thermally conductive metal outer shell; An intermediate functional layer located between two layers of thermally conductive metal outer shell; The intermediate functional layer contains multiple microchannels arranged in parallel, and the gaps between adjacent microchannels are filled with aerogel insulation material. When the composite liquid cooling plate is embedded between two adjacent lithium iron phosphate energy storage cells, the metal thermally conductive outer shell layer is in direct contact with the cooling fluid on the cell surface and in the microchannels, forming an integrated composite structure with thermal conduction, heat exchange and thermal insulation coupling.

[0007] Further optimization involves using an aluminum alloy outer shell, a composite liquid cooling plate with a total thickness of 1 mm, a metal thermally conductive outer shell with a thickness of 0.1 mm, and an intermediate functional layer with a thickness of 0.8 mm.

[0008] Further optimization involves the microchannels being parallel rectangular channels with a parallel topology layout, where the cooling fluid is split at the inlet and converges at the outlet.

[0009] Further optimization involves having 12, 13, or 14 microchannels, with each microchannel having a width of 6.5 to 7.5 mm; the aerogel occupies 85% to 92% of the total space of the intermediate functional layer.

[0010] Further optimization involves 13 microchannels, each with a width of 7mm; when the cooling fluid flows at a velocity of 0.03m / s within the microchannels, the fluid pressure drop within the microchannels is ≤40Pa.

[0011] A battery thermal management system, characterized in that it includes the above-mentioned sandwich-type embedded composite liquid cooling plate and a cooling circulation unit connected to a microchannel; the cooling circulation unit uses an aqueous ethylene glycol solution as the cooling fluid. The system is applied to battery modules or battery packs, with composite liquid cooling plates arranged between adjacent cells within the battery module / pack. The composite liquid cooling plates can be arranged on one or both sides of a single cell.

[0012] Further optimization is achieved by using an ethylene glycol aqueous solution with a concentration of 40% to 60%, a freezing point of -36.8°C, a viscosity of 0.00339 Pa•s, and a flow rate of 0.03 to 0.04 m / s within the microchannel.

[0013] A method for suppressing thermal runaway in a 314Ah high-capacity lithium iron phosphate energy storage cell, employing the aforementioned composite liquid cooling plate, includes: The composite liquid cooling plate is embedded between adjacent cells, so that the metal thermally conductive outer shell layer is in close contact with the cell surface; Cooling fluid is introduced into the microchannel and the flow rate is controlled to be no less than the critical choke flow rate; By combining the forced convection heat transfer of parallel microchannels with the thermal insulation of aerogel gaps, the propagation of thermal runaway between battery cells is blocked.

[0014] Further optimization revealed that when 13 microchannels were connected in parallel, the critical occlusion velocity was 0.03 m / s; when 7 microchannels were connected in parallel, the critical occlusion velocity was 0.05 m / s.

[0015] Further optimization resulted in a decrease in peak temperature of thermally runaway cells by more than 22°C at critical blocking flow rates, while the peak temperature of adjacent cells was controlled below 95°C.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1) Strong thermal runaway prevention capability: This invention can completely block the propagation of thermal runaway in a 314Ah battery cell even at extremely low coolant flow rates. Its unique sandwich structure tightly integrates a highly thermally conductive metal shell, microchannel liquid cooling technology, and high-performance thermal insulation materials, forming a synergistic defense mechanism: the metal shell ensures that heat is quickly captured and directed to the coolant channels; the thermal insulation material in the middle effectively blocks the radiation and transfer of heat between batteries; and the parallel microchannel design can remove heat from the source of thermal runaway in a timely manner with minimal energy consumption. This allows the system to respond quickly and terminate the chain reaction even under conditions of extremely high energy density and the greatest risk of thermal runaway.

[0017] 2. Significantly Optimized Space Occupancy and System Energy Consumption: This invention highly integrates the previously separate liquid cooling and thermal insulation functions, significantly reducing the overall thickness and achieving an ultra-thin integrated structure. This greatly reduces system volume and the space occupied by the battery, significantly improving the overall energy density of the battery pack. Simultaneously, the carefully designed flow channel topology greatly reduces fluid flow resistance, resulting in an order-of-magnitude reduction in the energy required to drive coolant circulation. This not only improves the overall energy efficiency of the system but also reduces operating costs and the burden on related components (such as the cooling circulation pump).

[0018] 3. Excellent thermal uniformity and flow stability. The parallel microchannel design fundamentally ensures the uniformity of coolant distribution, eliminating stagnant zones or high-speed scouring zones common in traditional serpentine flow channels. Combined with optimized coolant characteristics, the system achieves stable and controllable flow throughout the entire flow field, effectively avoiding efficiency losses or potential risks caused by fluid disturbances, eddies, and other instabilities. This not only improves the efficiency of thermal management but also ensures the safe and reliable operation of the entire thermal management system.

[0019] 4. Wide environmental adaptability and process feasibility. This invention uses an aqueous ethylene glycol solution to balance low-temperature antifreeze and low flow resistance, making it suitable for both frigid and high-temperature environments, thus solving the freezing or high-temperature failure problems that traditional solutions may face. The design takes into account both ease of manufacturing and economy, with a highly regular and modular structure, facilitating mass production and assembly. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the geometric structure of the composite liquid cooling plate and the battery pack model. Figure 2 Thermal runaway propagation curves under different mesh accuracies; Figure 3 Mesh generation for the thermal management model of the composite liquid-cooled plate; Figure 4 The thermal runaway propagation curves for a 13-channel parallel microchannel system are shown. Figure 5 The thermal runaway propagation curve is shown in the traditional serpentine flow channel diagram. Figure 6 Temperature cloud map of thermal runaway for a 13-channel parallel microchannel system; Figure 7 This is a thermal runaway temperature contour map of a serpentine flow channel. Figure 8 For the coolant flow velocity distribution in different flow channels; Figure 9 Pressure cloud diagrams for different flow channels; Figure 10 This is a cloud map showing the highest temperature distribution of the liquid cooling plate. Figure 11 This is a schematic diagram of a 7-channel parallel liquid cooling plate structure; Figure 12 The thermal runaway propagation curves for a 7-channel parallel microchannel system are shown. Figure 13 The flow velocity distribution is for 7 parallel microchannels; Figure 14 Pressure cloud map of 7 parallel microchannels; Figure 15 The thermal runaway propagation curve is shown for a 50% ethylene glycol aqueous solution. Figure 16 The thermal runaway propagation curve of the coolant used in the synthesis of MIDEL7131 ester; Figure 17 Cloud maps showing the velocity distribution of 13 parallel channels for different coolants; Figure 18 Pressure distribution cloud map for 13 parallel channels corresponding to different coolants. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can better understand the present invention.

[0022] In this embodiment, a sandwich-type embedded composite liquid cooling plate design method suitable for 314Ah high-capacity lithium iron phosphate energy storage cells is provided as a means of thermal management and thermal runaway propagation prevention for 314Ah high-capacity lithium iron phosphate battery modules and battery packs. Its 1mm thickness design, aluminum plate encapsulation, and sandwich structure composed of microchannel layers and aerogel embedding allow for coupled thermal management from both barrier and heat dissipation perspectives. The parallel microchannel design and coolant optimization further ensure efficient cooling and low energy consumption of the composite liquid cooling plate. Overall, it offers higher safety performance, improved energy efficiency, and space savings.

[0023] To achieve the above objectives, in a first aspect, embodiments of this application establish a battery pack model based on liquid cooling-thermal insulation composite thermal management. Figure 1 This is a geometric schematic diagram of a composite liquid cooling plate. Figure 1 Image (a) is a schematic diagram of the thermal management battery pack model. The cross-section of the liquid cooling plate is shown below. Figure 1 As shown in (b), the total thickness of the composite liquid cooling plate is set to 1 mm. The red parts on both sides are 0.1 mm thick aluminum plates, and the blue part in the middle is a 0.8 mm thick liquid cooling microchannel filled with aerogel. The aluminum plates with excellent thermal conductivity are in direct contact with the battery and the flowing coolant, which can transfer the heat of the battery to the liquid cooling microchannel in a timely manner. The flowing coolant then transfers the absorbed heat to the outside of the battery pack in a timely manner. Figure 1 (c) in the middle shows Figure 1 (b) A geometrical planar diagram of the aerogel and flow channels in the sandwich structure. The flow channels are designed as parallel microchannels. The dark blue area in the figure represents a rectangular liquid-cooled microchannel with a width of 7 mm, and the light blue area represents the aerogel material used to delay heat transfer between adjacent batteries. Figure 1 The middle (d) shows another serpentine liquid cooling channel design, used for comparative testing.

[0024] To ensure the realism of the simulation, the battery pack thermal runaway propagation model uses a fluid-structure interaction (FSI) model that couples liquid cooling with solid-state heat transfer. The computation time and accuracy of three mesh generation methods (conventional, refined, and even finer) are compared, and the results are shown in Table 1. Figure 2 , 3 As shown. Among them Figure 2 Simulate the corresponding battery thermal runaway propagation curves under different mesh qualities; Figure 3 To refine the mesh results of the composite liquid-cooled plate thermal management battery pack model, the following steps were taken: Figure 3 (a) shows the mesh generation result of the 13-microchannel composite liquid-cooled plate thermal management battery pack model arranged in parallel. Figure 3 (b) shows the mesh generation result of the 13 microchannel composite liquid cooling plate arranged in parallel. Figure 3(c) shows the mesh generation result of the composite liquid-cooled plate thermal management battery pack model corresponding to the serpentine flow channel. Figure 3 In the middle (d), the mesh generation result of the composite liquid cooling plate corresponding to the serpentine flow channel is shown. Finally, a refined mesh generation with higher accuracy and shorter time is adopted.

[0025] Table 1. Calculation results for different mesh qualities in the thermal management model.

[0026] Secondly, a multi-branch parallel layout is adopted to replace the traditional serpentine flow channel, which allows the cooling fluid to be diverted to 13 independent microchannels at the inlet, shortening the fluid path and improving heat exchange efficiency; the channel geometry parameters are adapted to the battery gap size to ensure that the two sides of the flow channel are in close contact with the battery surface.

[0027] like Figure 4 As shown in Table 2, for the composite liquid-cooled plate thermal management battery pack model with 13 microchannels arranged in parallel, when the inlet flow velocity of the coolant is ≥0.03m / s, the flow channel can completely interrupt the thermal runaway propagation of the battery pack. The peak temperature of the first thermal runaway battery (battery 1) drops to ≤461.85℃, and the temperature of the adjacent batteries (batteries 2 and 3) stabilizes below 95℃. Figure 4 In the figure, (a), (b), (c), and (d) represent the thermal runaway propagation curves of the parallel 13-microchannel composite liquid-cooled plate thermal management battery pack with inlet flow velocities of 0.01, 0.02, 0.03, and 0.04 m / s, respectively.

[0028] Under the same operating conditions, for the composite liquid-cooled plate thermal management battery pack model corresponding to the serpentine flow channel, a flow velocity ≥0.05m / s is required to achieve the same interruption effect, and the peak temperature of the thermal runaway battery is about 10℃ higher. Figure 5 Compare with the data in Table 3. Figure 5 In the figure, (a), (b), (c), and (d) represent the thermal runaway propagation curves of the serpentine flow channel composite liquid-cooled plate thermal management battery pack with inlet flow velocities of 0.03, 0.04, 0.05, and 0.06 m / s, respectively.

[0029] Table 2 Peak temperatures and arrival times of thermal runaway propagation in parallel microchannels at different flow rates

[0030] Table 3 Peak temperatures and arrival times of thermal runaway propagation in serpentine channels at different flow velocities

[0031] Secondly, such as Figure 6 , 7 As shown in the figure, the thermal runaway propagation temperature cloud map also demonstrates that the heat dissipation capacity of the parallel microchannel is significantly better than that of the serpentine flow channel. Figure 6Temperature cloud maps of thermal runaway propagation for a parallel 13-microchannel composite liquid-cooled plate thermal management battery pack with inlet flow velocities of 0.2 and 0.3 m / s. Figure 7 The temperature cloud map shows the thermal runaway propagation of the serpentine flow channel composite liquid-cooled plate thermal management battery pack with inlet flow velocities of 0.4 and 0.5 m / s.

[0032] In terms of flow velocity, the serpentine flow channel has a much lower flow velocity compared to the parallel flow channel, such as... Figure 8 As shown, where, Figure 8 (a) shows the coolant velocity distribution of the composite liquid cooling plate corresponding to the parallel arrangement of 13 microchannels. Figure 8 (b) shows the coolant velocity distribution of the serpentine flow channel composite liquid cooling plate. Figure 8 (c) is Figure 8 (a) A magnified view of the outlet of the central channel. However, overall, the parallel microchannels improve the uniformity of coolant distribution across the entire liquid cooling plate, and due to the shorter flow path, more heat exchange cycles can occur in the same amount of time. Furthermore, the maximum pressure drop of the parallel microchannels is approximately 118 Pa (flow velocity 0.03 m / s), and the energy consumption is only 13.1% of the maximum pressure drop of the serpentine channel (900 Pa), while avoiding the mechanical stress risks caused by high pressure, such as... Figure 9 As shown, the coverage area of ​​the low-temperature zone at the entrance has been increased by 30%, and the maximum temperature of the high-temperature zone is controlled below 219℃ (e.g., Figure 10 As shown), it improves thermal uniformity. The dual liquid cooling plate collaborative design after the module is assembled, such as the liquid cooling plates being arranged simultaneously on both sides of battery 2, enables it to reduce the peak temperature by 29.7°C under thermal runaway conditions (compared to the state without liquid cooling plates).

[0033] in Figure 9 (a) shows the coolant pressure cloud diagram of the composite liquid cooling plate corresponding to the parallel arrangement of 13 microchannels. Figure 9 Image (b) shows the coolant pressure cloud diagram of the serpentine flow channel composite liquid cooling plate. Figure 10 (a) shows the temperature distribution cloud map of the composite liquid-cooled plate corresponding to a parallel arrangement of 13 microchannels. Figure 9 (b) is a temperature distribution cloud map of the serpentine flow channel composite liquid cooling plate.

[0034] Thirdly, for the composite liquid-cooled plate thermal management battery pack model corresponding to the parallel arrangement of microchannels, this application adopts 13 parallel microchannels, compared with the 7-channel scheme (such as...). Figure 11As shown in Table 4, the critical flow velocity for thermal runaway suppression decreased from 0.05 m / s to 0.03 m / s, a 40% reduction, resulting in lower energy consumption. Under the same flow velocity increment, the heat dissipation capacity increased by 50%. For example, at 0.03 → 0.04 m / s, the temperature drop for the 7-channel battery was only 1.5℃, while the 13-channel battery under the same conditions saw a 22℃ temperature drop. The 13-channel layout reduced the aerogel filling amount in the liquid cooling plate gaps by 27%, but by increasing the channel density, the heat exchange area increased by 46%, and the forced convection heat transfer coefficient increased by 35%. This offset the adverse effects of the thinned insulation layer, resulting in an overall enhanced thermal runaway suppression effect. Figure 12 As shown, thermal runaway can be interrupted at 0.03 m / s for channel 13, while it requires 0.05 m / s for channel 7. Figure 12 In the figure, (a), (b), (c), and (d) represent the thermal runaway propagation curves of the parallel 7-channel composite liquid-cooled plate thermal management battery pack with inlet flow velocities of 0.03, 0.04, 0.05, and 0.06 m / s, respectively.

[0035] Table 4. Peak temperatures and arrival times of thermal runaway propagation in 7 parallel channels at different flow rates

[0036] Compared to the 7-channel design, the 13-channel design effectively suppresses eddies and surge pressure drops. The velocity difference in the 13-channel design is controlled at 0.005–0.514 m / s, while that in the 7-channel design ranges from 0.005–0.854 m / s. Figure 13 As shown, the high velocity difference leads to a 120% increase in vortex kinetic energy; the pressure drop is reduced to 38 Pa (channel 13), a 45% reduction compared to channel 7 (70 Pa), as... Figure 14 As shown, this avoids the risk of local pressure drop to zero in the fluid convergence area.

[0037] Fourthly, this application addresses the shortcomings of existing liquid cooling system cooling fluids (such as deionized water and synthetic esters) in terms of low-temperature adaptability, heat dissipation efficiency, and flow characteristics by proposing a synergistic technical solution of 50% ethylene glycol aqueous solution + 13-channel liquid cooling plate.

[0038] The selected 50% ethylene glycol aqueous solution meets the following physical properties as shown in Table 5: thermal conductivity ≥ 0.384 W / (m·K); freezing point ≤ -36.8℃ (solving the low-temperature freezing problem); viscosity ≤ 0.00339 Pa•s (low flow resistance).

[0039] At the same time, high-viscosity synthetic esters (such as MIDEL7131) were excluded because although they have a high flash point (316℃), their viscosity (0.0276Pa•s) causes a pressure drop exceeding 3000Pa (e.g. Figure 18 As shown in the figure, it is 10.3 times that of the ethylene glycol solution.

[0040] Table 5. Thermophysical properties of the synthesized ester from 50% ethylene glycol aqueous solution and MIDEL7131

[0041] Based on the 13-channel liquid cooling plate structure, a 50% ethylene glycol aqueous solution is required to interrupt thermal runaway at a speed of 0.08 m / s, as shown in Table 6. Figure 15 As shown, the peak temperature of unsuppressed thermal runaway in battery 2 at the critical flow rate is 384.13℃, which is much lower than the temperature of deionized water as a coolant at the critical flow rate (450.88℃). The thermal conductivity of the 50% ethylene glycol solution is 40% lower than that of deionized water, but the 13-channel design increases the heat exchange area by 46%, and the overall heat dissipation still suppresses the spread of thermal runaway; the peak temperature of battery 2 drops to 93.65℃ (0.08 m / s, Table 6), and the safety margin meets the national standard requirements (<120℃). MIDEL7131, on the other hand, requires 0.11 m / s to interrupt thermal runaway, as shown in Table 7. Figure 16 As shown, the flow rate decreased by 27% under the same operating conditions. Figure 15 In the figure, (a), (b), (c), and (d) represent the thermal runaway propagation curves of the 50% ethylene glycol aqueous solution and the 13-channel liquid-cooled plate thermal management battery pack at inlet flow velocities of 0.06, 0.07, 0.08, and 0.09 m / s, respectively. Figure 16 In the figure, (a), (b), (c), and (d) represent the thermal runaway propagation curves of the MIDEL7131 and 13-channel liquid-cooled plate thermal management battery packs at inlet flow velocities of 0.09, 0.10, 0.11, and 0.12 m / s, respectively.

[0042] Table 6. Peak temperatures and arrival times of thermal runaway propagation in 50% ethylene glycol aqueous solution.

[0043] Table 7 Peak temperatures and arrival times of thermal runaway propagation in MIDEL7131

[0044] Regarding the issue of eliminating eddy current effects, the viscosity increases after adding ethylene glycol. With a 50% ethylene glycol aqueous solution and an average inlet velocity of 0.08 m / s, the local maximum flow velocity at the liquid inlet and outlet of the liquid-cooled plate is 0.125 m / s (e.g., ...). Figure 17 As shown in the figure, the overall velocity difference between the liquid inlet and outlet is small, resulting in good flow uniformity. It is also worth noting that, as mentioned earlier... Figure 8(a) When deionized water is used as the cooling fluid, an extremely high-velocity vortex region forms in the lower left corner of the outlet. However, after adding 50% ethylene glycol, even though the coolant flow rate increases, the vortex region does not increase but disappears. This is because the addition of ethylene glycol increases the viscosity of the coolant, leading to increased internal friction during flow. This reduces the velocity gradient, increasing the uniformity of fluid flow and decreasing or even eliminating the vortex intensity. Figure 17 As shown, Figure 17 In the middle (a), the velocity distribution cloud map is the flow channel corresponding to the 50% ethylene glycol aqueous solution and the 13 parallel flow channel liquid cooling plate. Figure 17 (b) shows the flow velocity distribution cloud map corresponding to the MIDEL 7131 synthetic ester and the 13 parallel flow channel liquid cooling plate. When the average inlet velocity of the MIDEL 7131 synthetic ester is 0.11 m / s, the local maximum flow velocity at the liquid inlet and outlet of the liquid cooling plate is 0.172 m / s. Due to its high viscosity, no extremely high-velocity vortex region was observed. However, because its viscosity is much higher than that of other coolants, the boundary layer thickness increases, which in turn leads to a further increase in the local velocity in the middle of the inlet and outlet flow channels. Therefore, the velocity difference between the local maximum velocity and the average velocity is greater than that of a 50% ethylene glycol aqueous solution.

[0045] Figure 18 The figures show pressure distribution contour maps of liquid-cooled plates at the critical flow velocity for thermal runaway isolation, using (a) a 50% ethylene glycol aqueous solution and (b) MIDEL 7131 synthetic ester as the cooling fluid, respectively. The results show that the maximum pressure at the inlet of the 50% ethylene glycol aqueous solution is approximately 300 Pa, the minimum pressure at the outlet is approximately 10 Pa, and the overall pressure drop is approximately 290 Pa. When MIDEL 7131 synthetic ester is used as the cooling fluid, the pressure in the liquid-cooled plate increases significantly, exceeding 3000 Pa at the coolant inlet, and the overall pressure drop is also approximately 3000 Pa, far exceeding the pressure drop of deionized water and the 50% ethylene glycol aqueous solution. Aside from a very small portion of the pressure drop due to increased flow velocity, the vast majority is due to increased internal friction as viscosity increases, leading to greater pressure loss. Since the viscosity of MIDEL 7131 synthetic ester is much higher than the other two cooling fluids, the pressure loss during flow is also significantly greater.

[0046] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A sandwich-type embedded composite liquid cooling plate suitable for 314Ah high-capacity lithium iron phosphate energy storage cells, characterized in that, A sandwich-like layered structure integrating liquid cooling and thermal insulation, comprising: Two layers of thermally conductive metal outer shell; An intermediate functional layer located between two layers of thermally conductive metal outer shell; The intermediate functional layer contains multiple microchannels arranged in parallel, and the gaps between adjacent microchannels are filled with aerogel insulation material. When the composite liquid cooling plate is embedded between two adjacent lithium iron phosphate energy storage cells, the metal thermally conductive outer shell layer is in direct contact with the cooling fluid on the cell surface and in the microchannels, forming an integrated composite structure with thermal conduction, heat exchange and thermal insulation coupling.

2. The sandwich-type embedded composite liquid cooling plate for 314Ah high-capacity lithium iron phosphate energy storage cells according to claim 1, characterized in that, The metal outer shell is made of aluminum alloy, the total thickness of the composite liquid cooling plate is 1mm, the thickness of the metal thermally conductive outer shell is 0.1mm, and the thickness of the intermediate functional layer is 0.8mm.

3. The sandwich-type embedded composite liquid cooling plate for 314Ah high-capacity lithium iron phosphate energy storage cells according to claim 1, characterized in that, The microchannels are parallel rectangular channels with a parallel topology layout, where the cooling fluid is split at the inlet and converges at the outlet.

4. The sandwich-type embedded composite liquid cooling plate for 314Ah high-capacity lithium iron phosphate energy storage cells according to claim 3, characterized in that, The number of microchannels is 12, 13, or 14, and the width of a single microchannel is 6.5 to 7.5 mm; the volume of the aerogel occupies 85% to 92% of the total space of the intermediate functional layer.

5. The sandwich-type embedded composite liquid cooling plate for 314Ah high-capacity lithium iron phosphate energy storage cells according to claim 4, characterized in that, The number of microchannels is 13, and the width of each microchannel is 7mm; when the flow velocity of the cooling fluid in the microchannel is 0.03m / s, the pressure drop of the fluid in the microchannel is ≤40Pa.

6. A battery thermal management system, characterized in that, The invention includes a sandwich-type embedded composite liquid cooling plate as described in any one of claims 1 to 5, and a cooling circulation unit connected to a microchannel; the cooling circulation unit uses an aqueous ethylene glycol solution as the cooling fluid. The system is applied to battery modules or battery packs, with composite liquid cooling plates arranged between adjacent cells within the battery module / pack. The composite liquid cooling plates can be arranged on one or both sides of a single cell.

7. The battery thermal management system according to claim 6, characterized in that, The ethylene glycol aqueous solution has a concentration of 40% to 60%, a freezing point of -36.8°C, a viscosity of 0.00339 Pa•s, and a flow rate of 0.03 to 0.04 m / s in the microchannel.

8. A method for suppressing thermal runaway in a 314Ah high-capacity lithium iron phosphate energy storage cell, characterized in that, The composite liquid cooling plate according to any one of claims 1 to 5 comprises: The composite liquid cooling plate is embedded between adjacent cells, so that the metal thermally conductive outer shell layer is in close contact with the cell surface; Cooling fluid is introduced into the microchannel and the flow rate is controlled to be no less than the critical choke flow rate; By combining the forced convection heat transfer of parallel microchannels with the thermal insulation of aerogel gaps, the propagation of thermal runaway between battery cells is blocked.

9. The method according to claim 8, characterized in that, When there are 13 microchannels connected in parallel, the critical occlusion velocity is 0.03 m / s; when there are 7 microchannels connected in parallel, the critical occlusion velocity is 0.05 m / s.

10. The method according to claim 8, characterized in that, At the critical blocking flow rate, the peak temperature of the thermal runaway cell drops by more than 22°C, and the peak temperature of adjacent cells is controlled below 95°C.

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