Absorber phase change material coated separator for batteries
By embedding solid unencapsulated heat-absorbing phase change material particles on the porous substrate and ceramic coating of the lithium-ion battery separator, the problem of lithium-ion batteries in the prior art is difficult to prevent thermal runaway under high temperature conditions, and thermal shutdown and lithium-ion transmission cut-off at lower temperatures are achieved, and the safety and performance stability of the battery are improved.
Patent Information
- Application Number
- CN202411367465.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-10-05
- Filing Date
- 2024-09-29
- Publication Date
- 2025-04-15
AI Technical Summary
The existing lithium-ion battery separators are difficult to effectively prevent thermal runaway under high temperature conditions, and cannot quickly cut off lithium ion transmission during thermal runaway to prevent further electrochemical reactions.
Porous substrates and ceramic coatings are used as the basis structures, and solid unencapsulated heat-absorbing phase change material particles are embedded in their surfaces or ceramic coatings. These phase-change material particles melt when they reach the phase transition temperature, filling the pores of the porous substrate, increasing resistance and blocking lithium ion transmission, thereby achieving thermal shutdown.
Through this technical means, lithium-ion batteries can achieve thermal shutdown at lower temperatures to prevent thermal runaway, while not affecting the mechanical properties of the porous membrane, improving the safety and performance stability of the battery.
Smart Images
Figure CN119833888A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to phase change material coatings for separators in lithium ion batteries. Background Art
[0002] Lithium-ion batteries have been used for energy storage in portable electronic devices, large-scale smart grids and electric vehicles. Lithium-ion batteries consist of three main functional components, namely, an anode or negative electrode, a cathode or positive electrode and an electrolyte. Typically, a separator is placed between the negative electrode and the positive electrode to prevent physical contact and thus electrical short circuiting of the two electrodes, while absorbing the electrolyte and allowing ions to be transported between the electrodes. Typically, the separator does not directly participate in any chemical reaction in the battery, but plays a role in determining battery performance (including cycle life, energy density and power density) by affecting the kinetics of the battery cell. During operation, the separator should be chemically stable, mechanically stable and electrochemically stable in the highly reactive environment inside the battery. Summary of the invention
[0003] According to one embodiment, a battery component is provided, the battery component comprising a separator. The separator comprises a porous substrate, a ceramic coating on a surface of the porous substrate, and solid unencapsulated endothermic phase change material particles on or in the ceramic coating. The solid unencapsulated endothermic phase change material is configured to melt and fill the pores in the surface of the porous substrate when a phase transition temperature is reached.
[0004] In an alternative embodiment, a battery cell is provided, the battery cell comprising a positive electrode and a negative electrode, a separator disposed between the electrodes, and an electrolyte impregnating the separator and contacting the electrodes. The separator comprises a porous substrate, a ceramic coating on opposite sides of the porous substrate, and solid unencapsulated endothermic phase change material particles on or in the ceramic coating. The solid unencapsulated endothermic phase change material particles are configured to melt, fill the pores on the side of the porous substrate, and hinder ion transport between the electrodes when a phase transition temperature is reached.
[0005] In yet another embodiment, a battery cell is provided, the battery cell comprising a positive electrode and a negative electrode, a separator disposed between the electrodes, and an electrolyte impregnating the separator and contacting the electrodes. The separator comprises a porous substrate and solid unencapsulated endothermic phase change material particles. The solid unencapsulated endothermic phase change material particles are configured to melt, fill the pores of the porous substrate, and hinder ion transport between the electrodes when a phase transition temperature is reached. BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Figure 1A is a schematic diagram of a separator according to an embodiment.
[0007] Figure 1B is a schematic diagram of a separator according to another embodiment.
[0008] Figure 2A is a schematic diagram of a baffle according to an alternative embodiment.
[0009] Figure 2B is a schematic diagram of a separator according to yet another embodiment.
[0010] Figure 3 yes Figure 1B Schematic diagram of a separator after the phase change material has undergone a phase change.
[0011] Figure 4 is a cross-sectional view of a battery device including an exemplary separator. DETAILED DESCRIPTION
[0012] Embodiments are described herein. However, it should be understood that the disclosed embodiments are merely examples and that other embodiments may take various and alternative forms. The drawings are not necessarily drawn to scale. Some features may be enlarged or minimized to show details of particular components. Therefore, the specific structural details and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art.
[0013] The various features shown and described with reference to any one of the accompanying drawings may be combined with features shown in one or more other drawings to produce embodiments not explicitly shown or described. The combinations of features shown provide representative embodiments for typical applications. However, for specific applications or implementations, various combinations and modifications of features consistent with the teachings of the present disclosure may be desired.
[0014] Lithium-ion batteries include electrodes, electrolytes, and separators. The separator physically separates the positive and negative electrodes to prevent internal short circuits. The separator may include a polyolefin-based porous membrane. The typical thickness of a polyolefin-based porous membrane is between 5 μm and 30 μm.
[0015] The separator may also provide a function known as shutdown to prevent thermal runaway. Thermal runaway is a self-reinforcing increase in temperature within a battery cell that results in a chemical reaction that produces heat. This can occur when a battery is subjected to conditions that cause it to overheat, including overcharging, short circuiting, or exposure to high temperatures. Thermal runaway can cause the electrolyte to decompose and release gases and / or degrade internal components.
[0016] When the battery cell temperature approaches the melting point of the separator (commonly referred to as the shutdown temperature), the separator pores close and block the migration of lithium ions between the electrodes, thus preventing further electrochemical operation, which in turn prevents the battery cell temperature from increasing and thermal runaway.
[0017] Conventional separators can be produced by blending high-density polyethylene ("HDPE") and ultra-high molecular weight polyethylene ("UHMWPE") to obtain mechanical strength and thermal stability. The use of UHMWPE increases the shutdown temperature, typically above 140°C, due to the increased molecular weight and high crystallinity. A lower shutdown temperature (about 130°C or less) can speed up the shutdown speed. Using separators made of resins with lower crystallinity and melting points can reduce the shutdown temperature by lowering the melting point of the separator. However, this may affect the mechanical strength of the porous membrane.
[0018] Phase change materials ("PCMs") are materials that release or absorb energy upon and during a phase transition, which can be used to provide useful heating or cooling properties. Typically, the transition begins from one of the first two fundamental states of matter, solid and liquid. PCMs can be applied to battery separators to further control the shutdown temperature of the battery cells.
[0019] According to an embodiment of the present disclosure, a heat absorbing or endothermic PCM is coated on a porous separator membrane. The PCM may have a melting point of about 130°C or less. Upon heating caused by a short circuit, overcharging, or other excessive heat generating events, the PCM approaches its phase transition temperature. Upon phase change, the PCM endothermically absorbs heat and melts, thereby transitioning from a solid to a liquid or high viscosity state. The liquid or high viscosity state of the PCM enables the material to fill and close the separator pores. The liquid or high viscosity material filling the pores increases the resistance of the separator and may ultimately cause a thermal shutdown by cutting off lithium ion transport.
[0020] Thus, the PCM coating can serve two functions: as an additional and more efficient than melting of the porous membrane by permitting the cell to shut down at lower temperatures without affecting the mechanical properties of the porous membrane; and as an endothermic heat absorber, thus cooling hot spots and affecting thermal management within the battery cell.
[0021] In one example, the PCM may be coated on a single side of the separator. In another example, the PCM may be coated on both sides of the separator. The PCM may include hydrocarbons such as polyolefins, paraffins, or combinations thereof. The PCM may include polymers such as polyolefins, fluoropolymers, polyethylene oxides, acrylic resins, or combinations thereof. The PCM may also include ionic liquids. The PCM may be selected from a single or a combination of these materials. Depending on the material selected, the melting point of the PCM is in the range of about 90°C to 150°C, and preferably between about 110°C and 130°C. The PCM particles may have a D50 of about 0.1 μm to 2 μm. The PCM coating may have a thickness of about 0.5 μm to 10 μm.
[0022] The separator may include a ceramic coating. The ceramic coating may affect the thermal stability, mechanical stability, and electrolyte wettability of the separator. The ceramic particles may include alumina, boehmite, silica, or a combination thereof. The average ceramic particle size may be between about 0.1 μm and 2 μm and preferably between 0.2 μm and 1 μm.
[0023] In one example, the PCM is coated on the surface of the ceramic coating. The PCM may be coated on one side or opposite sides of the separator. In another example, the PCM may be embedded in the ceramic coating. The PCM may be embedded in one side or opposite sides of the separator.
[0024] Binder materials can be used to hold ceramic particles, PCM particles, or both together and to the porous membrane. Binder materials can include acrylic resins, carboxymethyl cellulose, methyl cellulose, styrene-butadiene rubber, polyvinyl alcohol, polyvinyl pyrrolidone, fluoropolymers, polyurethanes, polyacrylamides, curable monomers, or combinations thereof.
[0025] Figure 1A An exemplary separator 10 according to an embodiment is schematically depicted. The separator 10 includes a porous substrate 12, a ceramic coating 14 on a surface of the porous substrate 12, and solid unencapsulated heat absorbing PCM particles 16 on the ceramic coating 14. The ceramic coating 14 may include ceramic particles having a D50 of about 0.1 μm to 2 μm, the ceramic particles including alumina, boehmite, silica, or a combination thereof. The PCM particles 16 may be hydrocarbons including polyolefins, paraffin waxes, or a combination thereof. The PCM particles 16 may also be polymers including polyolefins, fluoropolymers, polyethylene oxides, acrylic resins, or a combination thereof. The PCM particles 16 may also be ionic liquids.
[0026] exist Figure 1B In the variation depicted in , the separator 10 may include solid unencapsulated heat absorbing PCM particles 16 on the ceramic coating 14 on the opposite side of the porous substrate 12. In either variation, the PCM particles 16 may have a D50 of about 0.1 μm to 2 μm and a phase transition temperature or melting point in the range of about 90° C. to 150° C., but preferably in the range of 110° C. to 130° C. The PCM particles 16 may form a layer on the ceramic coating 14 having a thickness of about 0.5 μm to 10 μm.
[0027] Figure 2AAn exemplary separator 20 according to another embodiment is schematically depicted. The separator 20 includes a porous substrate 22, a ceramic coating 24 on a surface of the porous substrate 22, and solid unencapsulated heat absorbing PCM particles 26 embedded in the ceramic coating 24. The ceramic coating 24 may include ceramic particles having a D50 of about 0.1 μm to 2 μm, the ceramic particles including alumina, boehmite, silica, or a combination thereof. The PCM particles 26 may be hydrocarbons including polyolefins, paraffin waxes, or a combination thereof. The PCM particles 26 may also be polymers including polyolefins, fluoropolymers, polyethylene oxides, acrylic resins, or a combination thereof. The PCM particles 26 may also be ionic liquids.
[0028] exist Figure 2B In the variation depicted in , separator 20 may include solid unencapsulated heat absorbing PCM particles 26 embedded in a ceramic coating 24 on opposite sides of a porous substrate 22. In either variation, the PCM particles 26 may have a D50 of about 0.1 μm to 2 μm and a phase transition temperature or melting point of about 90°C to 150°C, but preferably in the range of 110°C to 130°C.
[0029] Figure 3 An exemplary separator 30 is schematically depicted after reaching the phase transition temperature of the PCM according to an embodiment. The separator 30 includes a porous substrate 32, a ceramic coating 34 on the surface of the porous substrate 32, and solid unencapsulated heat absorbing PCM particles 36 on the ceramic coating 34. The PCM particles 36 absorb heat and transform from a solid to a liquid or high viscosity state when the phase transition temperature is reached, subsequently filling the pores in the surface of the porous substrate 32, increasing the electrical resistance on the separator 30, and hindering or preventing ion transport across the separator 30.
[0030] Figure 44 is a cross-sectional view of an exemplary battery device 400. According to an embodiment, the battery device 400 includes a negative electrode 402, a positive electrode 404, and a separator 406. Although not depicted, the battery device 400 includes an electrolyte between and in contact with the negative electrode 402 and the positive electrode 404. The negative electrode 402 is an electrode containing a material undergoing an oxidation reaction in which atoms release electrons during operation, and may include a carbon material such as graphite or lithium metal. The positive electrode 404 is an electrode containing a material undergoing a reduction reaction in which atoms gain electrons during operation, and may include lithium metal oxide. The separator 406 includes a porous substrate 408, a ceramic coating 410 on a surface of the porous substrate 408, and solid unencapsulated heat-absorbing PCM particles 412 on the ceramic coating 410. In an alternative embodiment, the separator 406 may include solid unencapsulated PCM particles on the ceramic coating 410 on the opposite side of the porous substrate 408. In yet another embodiment, the separator 406 may include solid unencapsulated PCM particles embedded in a ceramic coating 410 on one or opposite sides of the porous substrate 408 .
[0031] The PCM particles 412 may have a phase transition temperature or melting point in the range of about 90° C. to 150° C., preferably in the range of 110° C. to 130° C. When the battery device 400 reaches the phase transition temperature, the PCM particles 412 absorb heat and transform from a solid to a liquid or high viscosity state, thereby filling the pores of the porous substrate 408 and increasing the resistance on the separator 406, thus hindering or preventing ion transport from the negative electrode 402 to the positive electrode 404.
[0032] Although exemplary embodiments are described above, these embodiments are not intended to describe all possible forms covered by the claims. The words used in the specification are words of description rather than limitation, and it should be understood that various changes can be made without departing from the spirit and scope of these disclosed materials.
[0033] As previously mentioned, the features of the various embodiments may be combined to form additional embodiments of the present invention that may not be explicitly described or shown. Although various embodiments may have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, it will be appreciated by those of ordinary skill in the art that one or more features or characteristics may be compromised to achieve desired overall system properties, depending on the specific application and implementation. These properties may include, but are not limited to, strength, durability, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, and the like. Therefore, embodiments that are described as being less desirable than other embodiments or prior art implementations with respect to one or more characteristics are within the scope of the present disclosure and may be desirable for a particular application.
[0034] According to the present invention, a battery component is provided, the battery component having: a separator, the separator comprising a porous substrate, a ceramic coating on a surface of the porous substrate, and solid unencapsulated endothermic phase change material particles, the solid unencapsulated endothermic phase change material particles being on or in the ceramic coating and configured to melt and fill the pores in the surface when a phase transition temperature is reached.
[0035] According to an embodiment, the phase change material particles include hydrocarbons.
[0036] According to an embodiment, the hydrocarbon is a polyolefin, a paraffin or a combination thereof.
[0037] According to an embodiment, the phase change material comprises a polymer.
[0038] According to an embodiment, the polymer is a polyolefin, a fluoropolymer, a polyethylene oxide, an acrylic resin or a combination thereof.
[0039] According to an embodiment, the phase change material comprises an ionic liquid.
[0040] According to an embodiment, the solid unencapsulated endothermic phase change material particles on the ceramic coating form a layer having a thickness of about 0.5 μm to 10 μm.
[0041] According to an embodiment, the phase transition temperature is in the range of about 90°C to 150°C.
[0042] According to the present invention, there is provided a battery cell, the battery cell having: a positive electrode and a negative electrode; a separator, the separator being arranged between the electrodes, the separator comprising a porous substrate, a ceramic coating on opposite sides of the porous substrate, and solid unencapsulated endothermic phase change material particles, the solid unencapsulated endothermic phase change material particles being on or in the ceramic coating and being configured to melt when a phase transition temperature is reached, fill the pores on the side and hinder ion transport between the electrodes; and an electrolyte, the electrolyte impregnating the separator and contacting the electrodes.
[0043] According to an embodiment, the phase change material comprises a hydrocarbon.
[0044] According to an embodiment, the hydrocarbon is a polyolefin, a paraffin or a combination thereof.
[0045] According to an embodiment, the phase change material comprises a polymer.
[0046] According to an embodiment, the polymer is a polyolefin, a fluoropolymer, a polyethylene oxide, an acrylic resin or a combination thereof.
[0047] According to an embodiment, the phase change material comprises an ionic liquid.
[0048] According to the present invention, a battery cell is provided, the battery cell having: a positive electrode and a negative electrode; a separator, the separator is arranged between the electrodes, the separator comprises a porous substrate and solid unencapsulated endothermic phase change material particles, the solid unencapsulated endothermic phase change material particles are configured to melt when a phase transition temperature is reached, fill the pores of the porous substrate and hinder ion transport between the electrodes; and an electrolyte, the electrolyte permeates the separator and contacts the electrodes.
[0049] According to an embodiment, the separator further includes a ceramic coating configured to increase permeability and electrolyte wettability.
[0050] According to an embodiment, the ceramic particles include alumina, boehmite, silica, or a combination thereof.
[0051] According to an embodiment, the ceramic particles have a D50 between 0.1 μm and 2 μm.
Claims
1. A battery component, comprising: A separator comprising a porous substrate, a ceramic coating on a surface of the porous substrate, and solid unencapsulated endothermic phase change material particles on or in the ceramic coating and configured to melt and fill the pores in the surface when a phase transition temperature is reached.
2. The separator of claim 1, wherein the phase change material particles comprise hydrocarbons.
3. The separator of claim 2, wherein the hydrocarbon is a polyolefin, a paraffin, or a combination thereof.
4. The separator of claim 1, wherein the phase change material comprises a polymer.
5. The separator of claim 4, wherein the polymer is a polyolefin, a fluoropolymer, polyethylene oxide, an acrylic resin, or a combination thereof.
6. The separator of claim 1, wherein the phase change material comprises an ionic liquid.
7. The separator of claim 1, wherein the solid unencapsulated endothermic phase change material particles on the ceramic coating form a layer having a thickness of about 0.5 μm to 10 μm.
8. The separator of claim 1, wherein the phase transition temperature is in the range of about 90°C to 150°C.
9. A battery cell, comprising: Positive and negative electrodes; a separator disposed between the electrodes, the separator comprising a porous substrate, a ceramic coating on opposite sides of the porous substrate, and solid unencapsulated endothermic phase change material particles on or in the ceramic coating and configured to melt, fill the pores on the sides, and impede ion transport between the electrodes when a phase transition temperature is reached; as well as An electrolyte impregnates the separator and contacts the electrode.
10. The battery cell of claim 9, wherein the phase change material comprises a hydrocarbon.
11. The battery cell of claim 10, wherein the hydrocarbon is a polyolefin, a paraffin, or a combination thereof.
12. The battery cell of claim 9, wherein the phase change material comprises a polymer.
13. The battery cell of claim 12, wherein the polymer is a polyolefin, a fluoropolymer, a polyethylene oxide, an acrylic resin, or a combination thereof.
14. The battery cell of claim 9, wherein the phase change material comprises an ionic liquid.
15. A battery cell, comprising: Positive and negative electrodes; a separator disposed between the electrodes, the separator comprising a porous substrate and solid unencapsulated endothermic phase change material particles, the solid unencapsulated endothermic phase change material particles being configured to melt upon reaching a phase transition temperature, fill pores of the porous substrate, and hinder ion transport between the electrodes; as well as An electrolyte impregnates the separator and contacts the electrode.