Battery cell spacing heating pad and preparation method thereof

Abstract

The invention provides a battery cell spacing heating pad and a preparation method thereof. The battery cell spacing heating pad comprises a first flexible layer, a pore adjusting layer, a transition layer and a second flexible layer which are sequentially stacked, the pore adjusting layer comprises a first pore adjusting area, a second pore adjusting area and a third pore adjusting area which are sequentially arranged in the direction perpendicular to the stacking direction. The porosity of the second pore adjusting area is different from the porosity of the first pore adjusting area and the porosity of the third pore adjusting area. By designing the structure of the battery cell spacing heating pad and arranging the pore adjusting layer with the gradient pore structure, the problems that a traditional thermal insulation material is easy to crack under the thermal expansion pressure of the battery cell, the heat conductivity coefficient is unstable and the like can be effectively solved, and meanwhile, the battery cell spacing heating pad has excellent compression resilience performance and long-term use reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of battery thermal management, and particularly relates to a heat insulation pad, and more particularly to an inter-cell thermal pad and a preparation method thereof. Background Art

[0002] With the rapid development of new energy vehicles and energy storage technologies, the problem of battery thermal safety has become increasingly prominent. Most traditional inter-cell thermal materials are of rigid structures and are prone to cracking under the thermal expansion pressure of the cells, resulting in a decline in heat insulation performance.

[0003] CN116345022A discloses a preparation method of an inter-cell thermal pad and a heat insulation pad. The preparation method includes: cutting aerogel, cutting PET film, mixing silicone rubber, slicing silicone rubber, forming silicone rubber, cutting an inner frame, assembling, pressing, trimming, and pasting double-sided tape. The inter-cell thermal pad provided by this patent can only play a role in heat insulation and cannot solve the problem of compression deformation, and thus cannot meet the requirements of long-term stable use.

[0004] CN117691260A discloses a heat insulation pad, which includes a first heat insulation part and a second heat insulation part; the first heat insulation part is located in the central area of the heat insulation pad, and the second heat insulation part surrounds the periphery of the first heat insulation part and is located in the edge area of the heat insulation pad. By restricting the thermal conductivity coefficient of the first heat insulation part to be less than that of the second heat insulation part, and the thickness H1 of the first heat insulation part ≤ the thickness H2 of the second heat insulation part, the difference in heat insulation performance caused by cell expansion is balanced, the extrusion force received by the first heat insulation part is relieved, and the deformation degree of the first heat insulation part is reduced.

[0005] CN110061158A discloses a sealing, buffering and heat insulation pad for a power battery, which includes a heat insulation pad main body. The heat insulation pad main body includes a heat insulation core and a rubber frame; a reserved heat insulation core accommodating hole is provided at the central position of the rubber frame; a heat insulation core is placed in the heat insulation core accommodating hole; a packaging film is respectively and adhesively provided on the left and right side surfaces of the heat insulation pad main body.

[0006] In the prior art, more attention is paid to the heat insulation effect of the heat insulation pad, and less improvement is made to the buffering effect, and the requirements of low thermal conductivity coefficient and dynamic stress release cannot be met simultaneously. In addition, the problem that traditional materials are prone to permanent deformation under long-term compression, affecting the service life of the battery pack, cannot be solved either.

[0007] Therefore, it is of great significance to develop an inter-cell thermal pad and a preparation method thereof that can dynamically regulate pores, have a stable thermal conductivity coefficient, and have long-term use reliability. Summary of the Invention

[0008] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a cell spacer thermal pad and a preparation method thereof. By designing the structure of the cell spacer thermal pad and setting a pore adjustment layer with a gradient pore structure, the present invention can effectively solve problems such as the traditional thermal insulation material being prone to cracking under the thermal expansion pressure of the cell and the thermal conductivity coefficient being unstable, and at the same time has excellent compression and rebound performance and long-term use reliability.

[0009] To achieve the object of the present invention, the following technical solutions are adopted:

[0010] In the first aspect, the present invention provides a cell spacer thermal pad, which includes a first flexible layer, a pore adjustment layer, a transition layer, and a second flexible layer stacked in sequence;

[0011] The pore adjustment layer includes a first pore adjustment area, a second pore adjustment area, and a third pore adjustment area arranged in sequence perpendicular to the stacking direction;

[0012] The porosity of the second pore adjustment area is different from that of the first pore adjustment area and the third pore adjustment area.

[0013] By setting a cell spacer thermal pad with a multi-layer composite structure, the present invention effectively solves problems such as the traditional thermal insulation material being prone to cracking under the thermal expansion pressure of the cell and the thermal conductivity coefficient being unstable. At the same time, by setting a pore adjustment layer with a gradient pore structure, it has excellent compression and rebound performance and long-term use reliability. The overall structure of the cell spacer thermal pad provided by the present invention is simple, easy to produce on a large scale, and applicable to various battery types.

[0014] Through reasonable gradient structure design of the pore adjustment layer, the pore structure can reversibly change within the pressure range below 5 MPa, and the compression and rebound rate is ≥95%, realizing the "breathing" function of the cell spacer thermal pad and effectively relieving the thermal expansion pressure of the cell.

[0015] Preferably, the porosity of the first pore adjustment area and the third pore adjustment area is independently 40%-50%.

[0016] Preferably, the porosity of the second pore adjustment area is 60%-70%.

[0017] Preferably, the pore adjustment layer is a polyurethane foam layer.

[0018] Preferably, the materials of the first flexible layer and the second flexible layer independently include flexible mica rolls.

[0019] Preferably, the material of the transition layer includes silica glass fiber cloth.

[0020] Preferably, the foaming density of the polyurethane foam layer is 80 kg / m 3-120 kg / m 3 .

[0021] Preferably, the polyurethane foam layer further comprises uniformly distributed microencapsulated silicone oxygenate repair agent.

[0022] Preferably, the polyurethane foam layer further comprises a flame retardant.

[0023] Preferably, the surfaces of the first flexible layer and the second flexible layer are each independently treated by plasma activation.

[0024] Preferably, the surface of the transition layer is coated with a nano-silica reinforcing coating.

[0025] Preferably, after the plasma activation treatment, the interfacial bonding strength of the first flexible layer and the second flexible layer is each independently ≥ 5 MPa.

[0026] Preferably, the thickness of the cell spacer thermal pad is 1.5 mm - 6 mm.

[0027] Preferably, the thicknesses of the first flexible layer and the second flexible layer are each independently 0.1 mm - 0.4 mm.

[0028] Preferably, the thickness of the pore adjustment layer is 1.25 mm - 5 mm.

[0029] Preferably, the thickness of the transition layer is 0.05 mm - 0.2 mm.

[0030] In a second aspect, the present invention provides a method for preparing the cell spacer thermal pad as described in the first aspect, the preparation method comprising:

[0031] Mix polyol, isocyanate, foaming agent, and catalyst to obtain a mixed stock solution; sequentially lay the second flexible layer and the transition layer in a mold; pour in the mixed stock solution, form a first pore adjustment region at a first foaming and molding temperature, a second porosity region at a second foaming and molding temperature, and a third porosity region at a third foaming and molding temperature to form a pore adjustment layer; then lay the first flexible layer; cure, cool, and demold to obtain the cell spacer thermal pad.

[0032] Preferably, the temperature of the first foaming and molding and the temperature of the third foaming and molding are each independently 60 °C - 70 °C.

[0033] Preferably, the temperature of the second foaming and molding is 80 °C - 90 °C.

[0034] Preferably, the curing temperature is 110 °C - 130 °C.

[0035] Preferably, the curing time is 1 h - 5 h.

[0036] Preferably, the mixed stock solution further includes a microencapsulated silicone oxygen repair agent.

[0037] Preferably, the mixed stock solution further includes a flame retardant.

[0038] Preferably, the preparation method further includes performing plasma activation treatment on the first flexible layer and / or the second flexible layer.

[0039] Preferably, the preparation method further includes spraying a nano-silica enhanced coating on the surface of the transition layer.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) By providing a multi-layer composite structure of the cell spacer thermal pad, the present invention effectively solves the problems of traditional thermal insulation materials being prone to cracking and unstable thermal conductivity under the thermal expansion pressure of the cell. By adopting the interface strengthening technology, the bonding strength and durability of the multi-layer composite structure are significantly improved. The thermal conductivity of the cell spacer thermal pad prepared by the present invention @25°C ≤ 0.20 W / (m·K), and the long-term use temperature range is -40°C to 150°C, with excellent long-term use reliability.

[0042] (2) By reasonably designing the gradient structure of the pore adjustment layer, the pore structure can reversibly change within the pressure range below 5 MPa, and the compression and rebound rate ≥ 95%, realizing the "breathing" function of the cell spacer thermal pad, effectively relieving the thermal expansion pressure of the cell, and having excellent compression and rebound performance.

[0043] (3) The overall structure of the cell spacer thermal pad provided by the present invention is simple, easy to scale up production, and applicable to various battery types. Description of the Drawings

[0044] Figure 1 is a schematic structural diagram of the cell spacer thermal pad provided by the present invention.

[0045] Figure 2 is a schematic diagram of the change of the pore adjustment layer before compression, during compression, and after compression and rebound of the cell spacer thermal pad provided by the present invention.

[0046] Wherein, 1 - the first flexible layer; 2 - the pore adjustment layer; 21 - the first pore adjustment area; 22 - the second pore adjustment area; 23 - the third pore adjustment area; 3 - the transition layer; 4 - the second flexible layer. Detailed Embodiments

[0047] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs; the terms used herein are for the purpose of describing specific embodiments only and are not intended to limit this application; the terms "comprising" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusion.

[0049] In the description of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality of" means two or more, unless otherwise specifically defined.

[0050] In a specific embodiment, the present invention provides a cell spacer thermal pad, as Figure 1 shown, the cell spacer thermal pad includes a first flexible layer 1, a pore adjustment layer 2, a transition layer 3, and a second flexible layer 4 that are sequentially stacked; the pore adjustment layer 2 includes a first pore adjustment area 21, a second pore adjustment area 22, and a third pore adjustment area 23 that are sequentially arranged perpendicular to the stacking direction; the porosity of the second pore adjustment area 22 is different from the porosities of the first pore adjustment area 21 and the third pore adjustment area 23.

[0051] By providing a cell spacer thermal pad with a multi-layer composite structure, the present invention effectively solves problems such as the traditional heat insulation material being easily broken under the thermal expansion pressure of the cell and the thermal conductivity coefficient being unstable. At the same time, by providing a pore adjustment layer with a gradient pore structure, it has excellent compression and rebound performance and long-term use reliability. The overall structure of the cell spacer thermal pad provided by the present invention is simple, easy to scale up production, and applicable to various battery types.

[0052] By reasonably designing the gradient structure of the pore adjustment layer 2, the pore structure can reversibly change within the pressure range below 5 MPa, and the compression and rebound rate is ≥95%, realizing the "breathing" function of the cell spacer thermal pad and effectively relieving the thermal expansion pressure of the cell.

[0053] In some embodiments, the porosity of the first pore adjustment area 21 and the third pore adjustment area 23 is independently 40%-50%, for example, it can be 40%, 42%, 44%, 46%, 48% or 50%, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0054] In some embodiments, the porosity of the second pore adjustment area 22 is 60%-70%, for example, it can be 60%, 62%, 64%, 66%, 68% or 70%, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0055] In some embodiments, the pore adjustment layer 2 is a polyurethane foam layer.

[0056] In some embodiments, the materials of the first flexible layer 1 and the second flexible layer 4 independently include flexible mica rolls.

[0057] In some embodiments, the material of the transition layer 3 includes silica glass fiber cloth.

[0058] Preferably, the foaming density of the polyurethane foam layer is 80 kg / m 3 -120 kg / m 3 , for example, it can be 80 kg / m 3 , 85 kg / m 3 , 90 kg / m 3 , 95 kg / m 3 , 100 kg / m 3 , 105 kg / m 3 , 110 kg / m 3 , 115 kg / m 3 or 120 kg / m 3 , including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0059] In some embodiments, the polyurethane foam layer further includes uniformly distributed microencapsulated siloxane repair agent.

[0060] By introducing uniformly distributed microencapsulated siloxane repair agent into the polyurethane foam layer, the present invention integrates a self-repairing function in the cell spacer thermal pad, prolongs the service life of the cell spacer thermal pad, and reduces the maintenance cost.

[0061] In some embodiments, the composition of the microencapsulated siloxane repair agent includes a polymer wall (such as PU-FA, PMMA) and a siloxane core (such as epoxy polyorganosiloxane, vinyl silicone oil).

[0062] In some embodiments, the particle size of the microencapsulated siloxane repair agent is 10 μm - 50 μm, for example, it can be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0063] In some embodiments, in the polyurethane foam layer, the mass ratio of the microencapsulated silicone oxygen repair agent is 3%-5%, for example, it can be 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8% or 5%, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0064] In some embodiments, the polyurethane foam layer further includes a flame retardant.

[0065] In the present invention, the type and addition amount of the flame retardant are not particularly limited, as long as the UL94 V0 flame retardant grade can be satisfied. Exemplarily, the type of the flame retardant can be aluminum hydroxide, and the addition amount can be 20-40%.

[0066] In some embodiments, the surfaces of the first flexible layer and the second flexible layer are each independently subjected to plasma activation treatment.

[0067] In the present invention, by performing plasma activation treatment on the surface of the first flexible layer and / or the second flexible layer, the interface strengthening between the multi-layer composite structures of the battery cell spacer thermal pad is realized, and the bonding strength and durability of the multi-layer composite structure are significantly improved.

[0068] After the plasma activation treatment, the first flexible layer 1 and the pore regulation layer 2 can be chemically bonded to form a transition interface layer, and the bonding strength of the transition interface layer is ≥5 MPa, for example, it can be 5 MPa, 5.2 MPa, 5.4 MPa, 5.6 MPa, 5.8 MPa or 6 MPa, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable. Through reasonable gradient structure design of the pore regulation layer, the pore structure can reversibly change within the pressure range of ≤5 MPa, as Figure 2 shown, when the pore regulation layer is subjected to pressure, it can be adaptively compressed to relieve the expansion pressure of the battery cell. When the pressure is removed, the compression rebound rate of the pore regulation layer is ≥95%, realizing the "breathing" function of the battery cell spacer thermal pad and effectively relieving the thermal expansion pressure of the battery cell.

[0069] In some embodiments, after the plasma activation treatment, the interface bonding strength of the first flexible layer and / or the second flexible layer is each independently ≥5 MPa, for example, it can be 5 MPa, 5.2 MPa, 5.4 MPa, 5.6 MPa, 5.8 MPa or 6 MPa, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0070] In some embodiments, the surface of the transition layer is coated with a nano-silica reinforcing coating.

[0071] In some embodiments, the thickness of the nano-silica reinforced coating is 10 nm - 50 nm, for example, it can be 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm or 50 nm, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0072] In some embodiments, the thickness of the cell spacer thermal pad is 1.5 mm - 6 mm, for example, it can be 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm or 6 mm, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0073] In some embodiments, the thicknesses of the first flexible layer and the second flexible layer are each independently 0.1 mm - 0.4 mm, for example, it can be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm or 0.4 mm, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0074] In some embodiments, the thickness of the pore adjustment layer is 1.25 mm - 5 mm, for example, it can be 1.25 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0075] In some embodiments, the thickness of the transition layer is 0.05 mm - 0.2 mm, for example, it can be 0.05 mm, 0.07 mm, 0.09 mm, 0.10 mm, 0.12 mm, 0.14 mm, 0.16 mm, 0.18 mm or 0.2 mm, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0076] In another specific embodiment, the present invention provides a method for preparing the cell spacer thermal pad as described in the foregoing specific embodiment, and the preparation method includes:

[0077] Mix polyol, isocyanate, foaming agent, and catalyst to obtain a mixed stock solution; sequentially lay the second flexible layer and the transition layer in a mold; pour in the mixed stock solution, form a first pore adjustment zone at a first foaming and molding temperature, a second porosity zone at a second foaming and molding temperature, and a third porosity zone at a third foaming and molding temperature to form the pore adjustment layer; then lay the first flexible layer; cure, cool and demold to obtain the cell spacer thermal pad.

[0078] In the present invention, the selection and proportion of raw materials for preparing the mixed stock solution can be reasonably selected according to the raw materials for preparing polyurethane foaming materials in the prior art, and the present invention does not make special limitations. Among them, polyol refers to an alcohol containing three or more hydroxyl groups in the molecule, isocyanate refers to an organic compound containing the R-N=C=O functional group in the molecular formula, the blowing agent can be any one or a combination of at least two of hydrofluorocarbons, cyclopentane, isopentane, water or liquid CO2, and the catalyst can be any one or a combination of at least two of triethylenediamine, bis(dimethylaminoethyl) ether, triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N-ethylmorpholine or stannous octoate.

[0079] In some embodiments, the temperature of the first foaming and molding and the temperature of the third foaming and molding are each independently 60°C - 70°C. For example, they can be 60°C, 62°C, 64°C, 66°C, 68°C or 70°C, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0080] In some embodiments, the temperature of the second foaming and molding is 80°C - 90°C. For example, it can be 80°C, 82°C, 84°C, 86°C, 88°C or 90°C, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0081] In some embodiments, the temperature of the curing is 110°C - 130°C. For example, it can be 110°C, 112°C, 114°C, 116°C, 118°C, 120°C, 122°C, 124°C, 126°C, 128°C or 130°C, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0082] In some embodiments, the time of the curing is 1h - 5h. For example, it can be 1h, 2h, 3h, 4h or 5h, including but not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0083] In some embodiments, the mixed stock solution further includes a microencapsulated silicone oxygen repair agent.

[0084] In some embodiments, the mixed stock solution further includes a flame retardant.

[0085] In some embodiments, the preparation method further includes performing plasma activation treatment on the first flexible layer and / or the second flexible layer.

[0086] In some embodiments, the power of the plasma activation treatment is 100W - 300W. For example, it can be 100W, 150W, 200W, 250W, or 300W, including but not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0087] In some embodiments, the time of the plasma activation treatment is 30s - 60s. For example, it can be 30s, 35s, 40s, 45s, 50s, 55s, or 60s, including but not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0088] In some embodiments, the preparation method further includes spraying a nano - silica reinforcing coating on the surface of the transition layer.

[0089] Example 1

[0090] This example provides a cell spacer thermal pad. The cell spacer thermal pad includes a first flexible layer, a pore - adjusting layer, a transition layer, and a second flexible layer that are sequentially stacked, with thicknesses of 0.3mm, 3mm, 0.1mm, and 0.4mm respectively. The materials of the first flexible layer and the second flexible layer are mica rolls after surface plasma activation treatment, and the interfacial bonding strengths are 5.2MPa and 5MPa respectively. The pore - adjusting layer is a polyurethane foam layer containing 4.2wt% of encapsulated siloxane repair agent with a particle size of 32μm (consisting of a PMMA polymer capsule wall and an epoxy - based polysiloxane capsule core) and 20% of aluminum hydroxide flame retardant, and the foaming density is 100kg / m 3 ³. Among them, the porosities of the first pore - adjusting region, the second pore - adjusting region, and the third pore - adjusting region are 46%, 68%, and 46% respectively. The material of the transition layer is a silica - glass fiber cloth with a 33nm nano - silica reinforcing coating on its surface.

[0091] The preparation method of the cell spacer thermal pad includes:

[0092] (1) Prepare a mixed stock solution: Mix 100 parts of polyoxypropylene glycol, 50 parts of diphenylmethane diisocyanate, 5 parts of isopentane, 0.5 parts of triethylenediamine, 8.7 parts of micro - encapsulated siloxane repair agent, and 41 parts of aluminum hydroxide to obtain a mixed stock solution.

[0093] (2) Use a plasma treatment device to activate the surfaces of the mica rolls of the first flexible layer and the second flexible layer. The treatment power is 200W and the time is 45s; spray a nano - silica reinforcing coating on the surface of the silica - glass fiber cloth, and the coating thickness is 30nm.

[0094] (3) Molding: Lay the second flexible layer and silica glass fiber cloth in the mold in sequence, pour in the mixed stock solution, and lay the first flexible layer after foam molding. Cure at 120 °C for 2 hours, demold after cooling to obtain the battery cell spacer thermal pad.

[0095] Example 2

[0096] This example provides a battery cell spacer thermal pad, which includes a first flexible layer, a pore adjusting layer, a transition layer, and a second flexible layer with thicknesses of 0.2 mm, 1.02 mm, 0.05 mm, and 0.1 mm respectively, which are stacked in sequence. The materials of the first flexible layer and the second flexible layer are mica rolls after plasma activation treatment on the surface, and the interfacial bonding strengths are 5.1 MPa and 5.2 MPa respectively. The pore adjusting layer is a polyurethane foam layer containing 3 wt% of encapsulated silicone oxide repair agent with a particle size of 10 μm (composed of a PU-FA polymer capsule wall and a vinyl silicone oil core) and 20% of aluminum hydroxide flame retardant, and the foam density is 80 kg / m 3 ³. Among them, the porosity of the first pore adjusting area, the second pore adjusting area, and the third pore adjusting area are 40%, 60%, and 42% respectively. The material of the transition layer is silica glass fiber cloth with a 10 nm nano-silica enhanced coating on the surface.

[0097] The preparation method of the battery cell spacer thermal pad includes:

[0098] (1) Prepare the mixed stock solution: Mix 100 parts of polyoxypropylene ether glycol, 50 parts of diphenylmethane diisocyanate, 5 parts of isopentane, 0.5 parts of triethylenediamine, 6 parts of microencapsulated silicone oxide repair agent, and 40.5 parts of aluminum hydroxide to obtain the mixed stock solution.

[0099] (2) Use a plasma treatment device to activate the surfaces of the mica rolls of the first flexible layer and the second flexible layer, with a treatment power of 210 W and a time of 43 s; spray a nano-silica enhanced coating on the surface of the silica glass fiber cloth, with a coating thickness of 10 nm.

[0100] (3) Molding: Lay the second flexible layer and silica glass fiber cloth in the mold in sequence, pour in the mixed stock solution, and lay the first flexible layer after foam molding. Cure at 110 °C for 5 hours, demold after cooling to obtain the battery cell spacer thermal pad.

[0101] Example 3

[0102] This embodiment provides a cell spacer thermal pad. The cell spacer thermal pad includes a first flexible layer, a pore adjustment layer, a transition layer, and a second flexible layer that are sequentially stacked, with thicknesses of 0.4 mm, 5 mm, 0.35 mm, and 0.2 mm respectively. The materials of the first flexible layer and the second flexible layer are both mica rolls with surfaces treated by plasma activation, and the interfacial bonding strengths are 5 MPa and 5.3 MPa respectively. The pore adjustment layer is a polyurethane foam layer containing 5 wt% of encapsulated siloxane repair agent with a particle size of 50 μm and 20% of aluminum hydroxide flame retardant, and the foaming density is 120 kg / m 3 ³, and the porosities of the first pore adjustment area, the second pore adjustment area, and the third pore adjustment area are 50%, 70%, and 48% respectively. The material of the transition layer is a silica glass fiber cloth with a 50-nm-thick nano-silica reinforcement coating on its surface.

[0103] The preparation method of the cell spacer thermal pad includes:

[0104] (1) Prepare the mixed stock solution: Mix 100 parts of polyoxypropylene ether glycol, 50 parts of diphenylmethane diisocyanate, 5 parts of isopentane, 0.5 part of triethylenediamine, 10.4 parts of microencapsulated siloxane repair agent, and 41.5 parts of aluminum hydroxide to obtain the mixed stock solution.

[0105] (2) Use a plasma treatment device to activate the surfaces of the mica rolls of the first flexible layer and the second flexible layer, with a treatment power of 205 W and a time of 45 s; spray a nano-silica reinforcement coating on the surface of the silica glass fiber cloth, with a coating thickness of 50 nm.

[0106] (3) Molding: Lay the second flexible layer and the silica glass fiber cloth in sequence in a mold, pour in the mixed stock solution, and lay the first flexible layer after foaming and molding. Cure at 130 °C for 1 hour, cool and demold to obtain the cell spacer thermal pad.

[0107] Example 4

[0108] This embodiment provides a cell spacer thermal pad. Compared with Example 1, except that the mass ratio of the microencapsulated siloxane repair agent is 2%, the rest are the same as in Example 1.

[0109] Example 5

[0110] This embodiment provides a cell spacer thermal pad. Compared with Example 1, except that the mass ratio of the microencapsulated siloxane repair agent is 7%, the rest are the same as in Example 1.

[0111] Example 6

[0112] This embodiment provides a cell spacer thermal pad. Compared with Example 1, except that the foaming density of the polyurethane foam layer is 70 kg / m 3Except for this, the rest are the same as in Example 1.

[0113] Example 7

[0114] This example provides a cell spacer thermal pad. Compared with Example 1, except that the foaming density of the polyurethane foam layer is 130 kg / m 3 Except for this, the rest are the same as in Example 1.

[0115] Comparative Example 1

[0116] This comparative example provides a cell spacer thermal pad. Compared with Example 1, except that the porosity of the polyurethane foam layer is evenly distributed at 68%, the rest are the same as in Example 1.

[0117] Comparative Example 2

[0118] This comparative example provides a cell spacer thermal pad. Compared with Example 1, except that the porosity of the polyurethane foam layer is evenly distributed at 46%, the rest are the same as in Example 1.

[0119] Comparative Example 3

[0120] This comparative example provides a cell spacer thermal pad. Compared with Example 1, except that the surfaces of the first flexible layer and the second flexible layer are not subjected to plasma activation treatment, the rest are the same as in Example 1.

[0121] Comparative Example 4

[0122] This comparative example provides a cell spacer thermal pad. Compared with Example 1, except that it does not have a transition layer, the rest are the same as in Example 1.

[0123] Performance test:

[0124] Using the hot plate method, the thermal conductivity of the cell spacer thermal pads provided in all the above examples and comparative examples at 25°C was tested, and they were compressed under a pressure of 5 MPa for 2 h, and the rebound rate was tested. The test results are shown in Table 1.

[0125] Table 1

[0126]

[0127]

[0128] According to the test results in Table 1, for the cell spacer thermal pads with the composite layer structure defined in the present invention in Examples 1 to 3, the thermal conductivity at 25°C is ≤0.20 W / (m·K), and under a pressure of 5 MPa for 5 h, the rebound rate is greater than 95%.

[0129] According to the test results of Example 1, Comparative Example 1 and Comparative Example 2, if the polyurethane foam layer does not have a gradient pore structure, the cell spacer thermal pad with a composite layered structure cannot meet a 95% rebound rate after being compressed at a pressure of 5 MPa for 2 hours.

[0130] According to the test results of Example 1 and Comparative Example 3, if the first flexible layer and the second flexible layer are not subjected to plasma activation treatment, the cell spacer thermal pad with a composite layered structure is prone to delamination, and the interfacial bonding strength between the foam and the first flexible layer and the second flexible layer is lower than 5 MPa.

[0131] According to the test results of Example 1 and Comparative Example 4, if the silica fiberglass cloth transition layer is not provided, the thermal conductivity of the cell spacer thermal pad with a composite layered structure cannot meet ≤0.20 W / (m·K).

[0132] The applicant declares that the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A cell spacer thermal pad, characterized in that, The cell spacer thermal pad includes a first flexible layer, a pore adjustment layer, a transition layer, and a second flexible layer that are sequentially stacked; The pore adjustment layer includes a first pore adjustment zone, a second pore adjustment zone, and a third pore adjustment zone that are sequentially arranged perpendicular to the stacking direction; The porosity of the second pore adjustment zone is different from the porosities of the first pore adjustment zone and the third pore adjustment zone.

2. The cell spacer thermal pad according to claim 1, characterized in that The porosities of the first pore adjustment zone and the third pore adjustment zone are each independently 40%-50%; and / or, the porosity of the second pore adjustment zone is 60%-70%.

3. The cell spacer thermal pad according to claim 1 or 2, characterized in that, The pore adjustment layer is a polyurethane foam layer; and / or, the materials of the first flexible layer and the second flexible layer each independently include flexible mica rolls; and / or, the material of the transition layer includes silica glass fiber cloth.

4. The cell spacer thermal pad according to claim 3, wherein The foaming density of the polyurethane foam layer is 80 kg / m 3 -120 kg / m 3 ; and / or, the polyurethane foam layer further includes uniformly distributed microencapsulated silicone repair agent; and / or, the polyurethane foam layer further includes a flame retardant.

5. The cell spacer thermal pad according to any one of claims 1-4, characterized in that, The surfaces of the first flexible layer and the second flexible layer are each independently treated by plasma activation; and / or, the surface of the transition layer is coated with a nano-silica reinforcement coating.

6. The cell spacer thermal pad according to claim 5, wherein After the plasma activation treatment, the interfacial bonding strength of the first flexible layer and the second flexible layer is each independently ≥5 MPa.

7. The cell spacer thermal pad according to any one of claims 1-6, characterized in that, The thickness of the cell spacer thermal pad is 1.5 mm - 6 mm; and / or, the thicknesses of the first flexible layer and the second flexible layer are each independently 0.1 mm - 0.4 mm; and / or, the thickness of the pore adjustment layer is 1.25 mm - 5 mm; and / or, the thickness of the transition layer is 0.05 mm - 0.2 mm.

8. A method for preparing the cell spacer thermal pad according to any one of claims 1-7, characterized in that, The preparation method includes: Mix polyol, isocyanate, foaming agent, and catalyst to obtain a mixed stock solution; sequentially lay the second flexible layer and the transition layer in a mold; pour in the mixed stock solution, form the first pore adjustment zone at the first foaming and molding temperature, form the second porosity zone at the second foaming and molding temperature, and form the third porosity zone at the third foaming and molding temperature to form the pore adjustment layer; then lay the first flexible layer; cure, cool and demold to obtain the cell spacer thermal pad.

9. The preparation method according to claim 8, wherein, The temperatures of the first foaming and molding and the third foaming and molding are each independently 60°C - 70°C; and / or, the temperature of the second foaming and molding is 80°C - 90°C; and / or, the curing temperature is 110°C - 130°C; and / or, the curing time is 1 h - 5 h.

10. The preparation method according to claim 8 or 9, characterized in that, The mixed stock solution further includes a microencapsulated silicone repair agent; and / or, the mixed stock solution further includes a flame retardant; and / or, the preparation method further includes performing plasma activation treatment on the first flexible layer and / or the second flexible layer; and / or, the preparation method further includes spraying a nano-silica reinforcement coating on the surface of the transition layer.

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