Battery thermal management system based on electrocaloric effect and application thereof
Through the battery thermal management system based on the electric card effect, the solid-state phase change process and partition control technology driven by electric field is solved, and efficient temperature equalization and battery performance improvement are achieved.
Patent Information
- Application Number
- CN202510667261.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-22
- Publication Date
- 2025-08-26
AI Technical Summary
The volume and weight specifications of the existing battery thermal management system are not ideal enough to meet the local thermal management needs of integrated circuit chips, and there are uneven heat dissipation leading to degradation of battery performance and safety hazards.
Using a battery thermal management system based on the electric card effect, the graphene coating electrode and the modified double-layer polymer layer are used to achieve refrigeration and heating through a solid-state phase change process driven by an electric field, and the temperature equalization is performed in combination with partition control technology. The system includes a battery module and an electric card module.
It realizes efficient thermal management capabilities, is small in size and light in weight, and can quickly respond to battery temperature changes, reduce temperature differences, and improve battery performance and safety.
Smart Images
Figure CN120545512A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of battery thermal management, and more particularly to a battery thermal management system based on the electrocaloric effect and its application. Background Art
[0002] Batteries generate a large amount of heat during operation, which accumulates over time in a relatively small space. The dense stacking of cells within the battery pack makes heat dissipation in the central area more difficult, exacerbating temperature inconsistencies between cells. This reduces the battery's charge and discharge efficiency, affecting its power output; in severe cases, it can even lead to thermal runaway, impacting the system's safety and lifespan. Battery temperature significantly impacts its performance, lifespan, and safety. At low temperatures, lithium-ion batteries experience increased internal resistance and reduced capacity. In extreme cases, this can lead to electrolyte freezing and the inability to discharge. This significantly impacts the low-temperature performance of the battery system, resulting in reduced power output.
[0003] Battery thermal management is a key function in a battery management system (BMS). It aims to keep the battery pack operating within a suitable temperature range, thereby maintaining optimal operating conditions. Battery thermal management primarily includes cooling, heating, and temperature equalization. Cooling and heating primarily adjust for the potential impact of ambient temperature on the battery. Temperature equalization minimizes temperature variations within the battery pack, preventing rapid degradation caused by overheating of a single cell.
[0004] Existing battery thermal management systems mostly rely on compressor technology, which has the defects of being large in size and heavy in weight, and cannot meet the local thermal management requirements of integrated circuit chips. Summary of the Invention
[0005] The present invention provides a battery thermal management system based on the electrocaloric effect and its application, which are used to solve the problem that the volume and weight specifications of the battery thermal management system in the prior art are not ideal.
[0006] In the first aspect, the present invention provides a battery thermal management system based on the electrocaloric effect, comprising: a battery module and an electrocaloric module; wherein the electrocaloric module is installed on the outside of the battery module; the electrocaloric module comprises, from bottom to top, a first insulating layer, a first polymer layer, a heat transfer layer, a second polymer layer, and a second insulating layer; the first insulating layer and the second insulating layer are both graphene coating electrodes, and the outer surface of the graphene coating electrode has an insulating layer and the inner surface has a dielectric layer; the first polymer layer and the second polymer layer both include a PDMS (polydimethylsiloxane) frame and a modified double-layer polymer stack, and one side of the modified double-layer polymer stack is arranged at the upper end of the PDMS frame, and the other side is arranged at the lower end of the PDMS frame.
[0007] As a possible implementation manner, the modified double-layer polymer stack of the first polymer layer and the modified double-layer polymer stack of the second polymer layer are arranged in an axisymmetric form, and the axis of symmetry is the heat transfer layer.
[0008] As a possible implementation manner, the insulating layer is made of polyimide.
[0009] As a possible implementation manner, the insulating layer on the outer surface of the first insulating layer and the second insulating layer has a thickness of 30 to 40 μm.
[0010] As a possible implementation, the heat transfer layer is a graphene electrode coated with a PET (polyethylene terephthalate) layer on the outside.
[0011] As a possible implementation, the thickness of the PET layer is 45 to 55 μm.
[0012] As a possible implementation, the thickness of the electric card module is 1.2 to 1.5 mm.
[0013] As a possible implementation manner, the bendable radius of the electric card module is ≥5 mm.
[0014] In a second aspect, the present invention provides an application of a battery thermal management system based on the electrocaloric effect as described in any possible implementation of the first aspect in a power battery system of an electric vehicle.
[0015] In a third aspect, the present invention provides an application of a battery thermal management system based on the electrocaloric effect as described in any possible implementation of the first aspect in a high-density battery pack for a drone.
[0016] As a possible implementation method, the battery thermal management system based on the electrocaloric effect described in any possible implementation method of the first aspect can also be applied to other temperature-sensitive battery application scenarios, such as portable electronic devices, base station backup power supplies, aerospace highly integrated energy systems, etc.
[0017] This invention provides a battery thermal management system based on the electrocaloric effect. Among these technologies, electrocaloric effect cooling (magnetic caloric (MC), electric caloric (EC), spring caloric (eC), and compression caloric (BC)) utilizes the latent heat change during a solid-state phase transition to achieve cooling. This solid-state phase transition can be induced by magnetic fields, electric fields, uniaxial stress, and isostatic pressure. Electric-field-driven electrocaloric cooling eliminates the need for environmentally hazardous refrigerants and offers low energy consumption, a compact size, and light weight, making it a highly efficient solid-state cooling technology with great development potential.
[0018] It has efficient thermal management capabilities, excellent weight and volume specifications and excellent aging resistance. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0020] Figure 1 A schematic structural diagram of a battery thermal management system based on the electrocaloric effect provided in an embodiment of the present invention.
[0021] Figure 2 This is a schematic diagram of the hot and cold cycle principle of the electrocaloric effect electrocaloric element provided by an embodiment of the present invention.
[0022] Figure 3 Schematic diagram of thermal transport of electric card components provided by an embodiment of the present invention. DETAILED DESCRIPTION
[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0024] In order to solve the problem that the volume and weight specifications of the battery thermal management system in the prior art are not ideal, this embodiment provides a battery thermal management system based on the electrocaloric effect and its application.
[0025] Figure 2 and Figure 3The four stages of heat transfer in an electrocaloric element loaded with electrocaloric material in a Brayton cycle are exemplified, along with a schematic diagram of the heat transfer of the electrocaloric element. Specifically, the temperature of the polar material is regulated by inducing dipole flipping through an electric field, and the heat absorption and release behavior generated during the voltage change is utilized to achieve cooling through heat transfer. When the ferroelectric is in stage 1 (stage 1), the externally applied electric field is 0 (E=0), and the electric dipoles inside the ferroelectric material are randomly arranged. When transitioning from stage 1 to stage 2 (stage 2), the external electric field begins to be applied (E>0), and the dipoles in the ferroelectric material inside the module begin to align along the direction of the electric field. At this point, the electrocaloric element heats up rapidly under adiabatic conditions, and the entropy value remains unchanged. Then, during the process from stage 2 to stage 3 (stage 3), the electric field remains unchanged, the electrocaloric module contacts the hot end, and releases heat to the hot end, at which point the temperature and entropy value of the electrocaloric material decrease simultaneously. Then, during the transition from stage 3 to stage 4, the electric field is removed, and the ferroelectric material dipoles within the module return to a disordered state. At this point, they are in an adiabatic state, with no heat exchange with the outside world. Therefore, the entropy remains constant, and the temperature of the electrocaloric element decreases. Finally, during the transition from stage 4 to stage 1, the electrocaloric module contacts the cold end and absorbs heat from the cold end. At this point, the temperature and entropy of the element itself increase simultaneously, and the system returns to its initial state. The amount of electrocaloric cooling capacity depends in part on the change in polarization intensity during the dipole flip, so larger electrocaloric temperature changes (ΔT) are more likely to occur in highly polar ferroelectric dielectrics.
[0026] The technical solution of the present invention will be further described below with reference to specific embodiments.
[0027] Example 1
[0028] This embodiment provides a structure of a battery thermal management system based on the electrocaloric effect.
[0029] The battery module uses a ternary lithium battery module (rated voltage 400V, capacity 100Ah); the thickness of the electric card module is controlled at 1.2~1.5mm, and the bending radius can be ≥5mm, which can adapt to battery modules of different shapes.
[0030] The electric card module adopts a five-layer composite design, from top to bottom:
[0031] ① The first insulating layer: a graphene coating electrode (square resistance ≤ 5Ω / sq), a 35μm thick polyimide insulating layer (breakdown voltage ≥ 20kV / mm) coated on the outside, and a 5μm thick Al2O3 dielectric layer (relative dielectric constant εr = 9.8) deposited on the inside; it serves the dual functions of conductive path and electrical isolation.
[0032] ② First polymer layer: The PDMS frame adopts a honeycomb microstructure (pore diameter 200μm, wall thickness 50μm) with a filling rate of 75%. The lower layer of the modified double-layer polymer stack uses PVDF-TrFE-CFE ferroelectric polymer (Curie temperature 65°C, electrocaloric temperature change ΔT = 12K@50MV / m), and the upper layer uses BNN / PDMS composite material (thermal conductivity 1.8W / m·K, a 15-fold increase). The function is to achieve heat absorption and release through the electrocaloric effect.
[0033] ③ Heat transfer layer: graphene electrode (thickness 20μm, thermal conductivity 1500W / m·K), coated with a 50μm thick PET layer on the outside (surface roughness Ra≤0.1μm); its function is to provide rapid heat conduction and mechanical protection.
[0034] ④ The second polymer layer: The structure is completely symmetrical with the first polymer layer, forming a "thermal bridge" structure; the stacking direction of the double polymer layer is opposite to that of the first polymer layer, realizing cooperative heat transfer driven by the electric field
[0035] ⑤ Second insulation layer: designed the same as the first insulation layer to form a complete electrical shielding structure.
[0036] Example 2
[0037] This embodiment provides a working efficiency test experiment of the battery thermal management system based on the electrocaloric effect prepared in Example 1.
[0038] 1. Cooling mode (battery high temperature scenario: when the battery module temperature exceeds 40°C)
[0039] Electric field application: a pulsed electric field of 30 MV / m (pulse width 10 ms) was applied between the first insulating layer and the second insulating layer;
[0040] The electrocaloric effect is activated: the PVDF-TrFE-CFE in the first and second polymer layers undergoes polarization reversal, causing a 5.2°C temperature increase. Heat is rapidly transferred to the outside through the heat transfer layer.
[0041] Electric field removal: The temperature of the polymer layer drops, absorbing heat from the battery module (heat absorption power density can reach 250W / m 2 );
[0042] Cycle control: The electric field frequency is controlled by PWM (typical value 5Hz) to maintain the battery temperature at 30±2℃.
[0043] 2. Heating mode (battery low temperature scenario: when the battery module temperature is below 0°C)
[0044] Reverse electric field application: Apply a reverse electric field (25MV / m) to activate the electrocaloric heating effect;
[0045] Directed heat transfer: The polymer layer temperature rises by 7.8°C; the heat is transferred to the battery module through the heat transfer layer.
[0046] Low-temperature startup optimization: The battery can be heated from 0°C to 25°C in just 8 minutes at -20°C (heating efficiency is 40% higher than traditional PTC heating).
[0047] 3. Temperature balance function
[0048] By using zoning control technology, differentiated electric field strengths are applied to the electric card modules in different areas of the battery module (for example, the electric field strength in the edge area is 15% higher than that in the center area), which can reduce the temperature difference within the module from ±8°C in the traditional system to within ±2°C.
[0049] Example 3
[0050] This embodiment provides a performance test experiment of the battery thermal management system based on the electrocaloric effect prepared in Example 1.
[0051] The battery thermal management system based on the electrocaloric effect prepared in Example 1 was tested for its working performance. The results showed that its cooling capacity could reach 350W / m at 25°C. 2 The system's temperature response speed, from 45°C to 35°C, is ≤15 seconds. Its system cost-effectiveness ratio (COP) is 4.2, significantly better than a conventional compressor (COP of 2.8). Clearly, this system demonstrates highly effective thermal management capabilities.
[0052] The physical properties of the battery thermal management system based on the electrocaloric effect prepared in Example 1 were measured, and the results showed that its volume was reduced by 60% and its weight was reduced by 45% compared with the traditional liquid cooling system (taking a typical 100kWh battery pack as an example, the weight was reduced by 28kg).
[0053] The battery thermal management system based on the electrocaloric effect prepared in Example 1 was subjected to a material aging test. 6 The performance degradation after electric field cycling is less than 5%; moreover, it has an all-solid-state structure, with no risk of leakage, and the maintenance cycle can be extended to more than 10 years.
[0054] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.
[0055] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.
Claims
1. A battery thermal management system based on electrocaloric effect, characterized in that: include: Battery module (1) and electric card module (2); Wherein, the electric card module (2) is installed outside the battery module (1); The electric card module (2) comprises, from bottom to top, a first insulating layer (201), a first polymer layer (202), a heat transfer layer (203), a second polymer layer (204), and a second insulating layer (205); The first insulating layer (201) and the second insulating layer (205) are both graphene coating electrodes, and the outer surface of the graphene coating electrode has an insulating layer and the inner surface has a dielectric layer; The first polymer layer (202) and the second polymer layer (204) both include a PDMS frame and a modified double-layer polymer stack, wherein one side of the modified double-layer polymer stack is arranged at the upper end of the PDMS frame and the other side is arranged at the lower end of the PDMS frame.
2. The system according to claim 1, wherein: The modified double-layer polymer stack of the first polymer layer (202) and the modified double-layer polymer stack of the second polymer layer (204) are arranged in an axisymmetric form, with the axis of symmetry being the heat transfer layer (203).
3. The system according to claim 1, wherein: The insulating layer is made of polyimide.
4. The system according to claim 1, wherein: The insulating layer on the outer surface of the first insulating layer (201) and the second insulating layer (205) has a thickness of 30 to 40 μm.
5. The system according to claim 1, wherein: The heat transfer layer (203) is a graphene electrode coated with a PET layer on the outside.
6. The system according to claim 5, characterized in that The thickness of the PET layer is 45-55 μm.
7. The system according to claim 1, wherein: The thickness of the electric card module (2) is 1.2 to 1.5 mm.
8. The system according to claim 1, wherein: The bendable radius of the electric card module (2) is ≥5mm.
9. Application of the battery thermal management system based on the electrocaloric effect according to any one of claims 1 to 8 in an electric vehicle power battery system.
10. Application of the battery thermal management system based on the electrocaloric effect according to any one of claims 1 to 8 in a high-density battery pack for an unmanned aerial vehicle.