Phase change heat insulation barrier plate, preparation method and application thereof, and soft package battery module

Abstract

The invention belongs to the technical field of battery safety, and particularly relates to a phase change heat insulation baffle, a preparation method and application thereof, and a soft package battery module. The invention provides a phase-change heat-insulation barrier plate. The phase-change heat-insulation barrier plate comprises a phase-change heat-insulation material and a packaging film for packaging the phase-change heat-insulation material, the phase-change thermal insulation material comprises a substrate material, and a phase-change material and a flame-retardant material which are adsorbed on the substrate material, the substrate material comprises a silicon dioxide nanofiber felt and a supporting material; the phase-change material comprises one or more of silica sol, alumina sol and a saturated calcium chloride solution, and the flame-retardant material comprises a phosphorus-containing flame retardant. The phase-change thermal insulation material contains the phase-change material and the thermal insulation substrate, has a very high phase-change enthalpy value, plays a good role in blocking heat spreading through thermal insulation of the thermal insulation material and phase-change energy consumption of the phase-change material during thermal runaway, and can delay the heat spreading time or inhibit the heat spreading.

Description

Technical Field

[0001] The present invention belongs to the field of battery safety technology, and specifically relates to a phase-change heat-insulating barrier plate, a preparation method and application thereof, and a soft-pack battery module. Background Art

[0002] As the development of electric vehicles accelerates, the safety of their power battery systems has also attracted increasing attention. The core of electric vehicle safety accidents is thermal runaway of power batteries, which is initially caused by thermal runaway of a single battery cell and releases a large amount of heat in a short period of time. This heat will be transferred to adjacent batteries, causing their temperature to rise and further runaway, and even cause the thermal runaway of the entire battery module or the entire battery pack to spread. Thermal runaway is often accompanied by smoke, fire or explosion, which is extremely dangerous. Therefore, in order to ensure the safety of passengers' lives and property, it is of great significance to suppress or delay the spread of power battery heat.

[0003] Lithium-ion batteries can be divided into lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, ternary and other systems according to the different positive electrode material systems. At present, the new energy vehicles on the market mainly use ternary batteries and lithium iron phosphate batteries. In recent years, with the increasing market share of electric vehicles, the public's requirements for their range are also constantly increasing. As a result, ternary lithium-ion batteries with higher energy density are more favored by the market, especially in high-priced long-range pure electric models. Soft-pack batteries naturally have the advantage of high energy density. The capacity is 50% higher than that of steel-shell batteries of the same specifications and sizes, and 20-30% higher than that of aluminum-shell batteries, and have good application prospects. However, compared with square-shell batteries, ternary soft-pack batteries are more prone to thermal runaway, and their thermal runaway spread has the characteristics of large fire, short time, and difficult early warning.

[0004] At present, battery and new energy vehicle companies mainly delay the spread of heat in battery modules by applying thermal insulation materials between battery cells. Thermal insulation materials include ceramic fibers, ceramic silicone materials, aerogels, etc., which have been widely used to suppress or delay thermal runaway of battery cells in modules. When the battery is in thermal runaway, the above materials rely on their own thermal insulation properties to delay heat transfer from the heat released by the runaway battery, thereby providing passengers with valuable time to escape. However, from the principle of heat conservation, the energy generated by the thermal runaway battery cell is only limited to the battery module. The thermal insulation material delays its transfer time, but eventually it will cause thermal runaway of other battery cells over time, causing heat spread in the battery pack. The current thermal insulation materials are used to deal with the severe thermal runaway of soft-pack batteries, and the protection effect is not good. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a phase change thermal insulation barrier plate and its preparation method and application, and a soft pack battery module. The phase change thermal insulation barrier plate of the present invention has a very high phase change enthalpy value and can play a good barrier role against heat spread during thermal runaway.

[0006] The present invention provides a phase-change thermal insulation barrier plate, comprising a phase-change thermal insulation material and a packaging film that packages the phase-change thermal insulation material;

[0007] The phase change thermal insulation material comprises a base material, and a phase change material and a flame retardant material adsorbed on the base material;

[0008] The substrate material includes silica nanofiber felt and a supporting material;

[0009] The phase change material includes one or more of silica sol, aluminum sol and saturated calcium chloride solution; and the flame retardant material includes a phosphorus-containing flame retardant.

[0010] Preferably, the mass fraction of the phase change material in the phase change thermal insulation material is 70-95%.

[0011] Preferably, the phosphorus-containing flame retardant includes triethyl phosphate and / or triphenyl phosphate.

[0012] Preferably, the average fiber diameter of the silica nanofiber felt is 200-10000 nm, and the density is 140-160 mg / cm 3 .

[0013] The present invention also provides a method for preparing the phase change thermal insulation barrier plate described in the above technical solution, comprising the following steps:

[0014] The silica sol and the polyethylene oxide solution are mixed, and the obtained dispersion is spun and calcined to obtain a silica nanofiber felt;

[0015] inserting a support material into the silica nanofiber felt to obtain a base material;

[0016] After coating the flame retardant material on the surface of the base material, the base material is immersed in the phase change material to obtain a phase change thermal insulation material;

[0017] The phase-change thermal insulation material is packaged to obtain the phase-change thermal insulation barrier plate.

[0018] Preferably, the silica sol is obtained by a mixed reaction of polyethyl silicate, oxalic acid, ethanol and water, and the mass ratio of the polyethyl silicate, oxalic acid, ethanol and water is 20-100:0.3:10:10-100.

[0019] Preferably, the spinning conditions include: the dispersion liquid and air flow rates are 4-8 mL / h and 6-15 m / s, respectively.

[0020] Preferably, the calcination temperature is 500-700° C. and the calcination time is 25-40 min.

[0021] The present invention also provides the use of the phase-change thermal insulation barrier plate described in the above technical solution or the phase-change thermal insulation barrier plate obtained by the above preparation method in the heat spread protection of soft-pack battery modules.

[0022] The present invention also provides a soft-pack battery module, comprising a liquid cooling plate, and a battery cell assembly abutting against the liquid cooling plate;

[0023] The battery cell assembly includes a plurality of battery cells, and adjacent battery cells are separated by a barrier plate; the barrier plate is the phase-change thermal insulation barrier plate described in the above technical solution or the phase-change thermal insulation barrier plate obtained by the above preparation method.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention provides a phase-change thermal insulation barrier plate, comprising a phase-change thermal insulation material and an encapsulation film encapsulating the phase-change thermal insulation material; the phase-change thermal insulation material comprises a base material, and a phase-change material and a flame-retardant material adsorbed on the base material; the base material comprises a silica nanofiber felt and a supporting material; the phase-change material comprises one or more of silica sol, aluminum sol and saturated calcium chloride solution; the flame-retardant material comprises a phosphorus-containing flame retardant. The phase-change thermal insulation material of the present invention contains a phase-change material and a thermal insulation base, and has a very high phase-change enthalpy value (1800-2200 J / g). In the event of thermal runaway, the heat insulation of the thermal insulation material and the phase change of the phase-change material consume energy, which has a good barrier effect on heat spread, and can delay the heat spread time or inhibit heat spread.

[0026] At present, placing heat-insulating materials between battery cells to prevent heat spread has the problem that the overall energy density of the battery pack and the thermal runaway protection effect cannot be achieved at the same time. The composite protective material of the present invention has a very high phase change enthalpy value and a small mass. When used in a battery pack, the thickness can be as low as 1 mm, and the overall energy of the battery will not be significantly reduced. Moreover, placing heat-insulating materials between batteries will affect the heat dissipation of the battery under normal conditions, which is not conducive to thermal management. The battery packs currently on the market will be equipped with a complex thermal management system (setting a spoiler structure-air cooling, there will be a heat-conducting medium between the battery cells, and the additional structure will cause the mass percentage of the battery inside the battery pack to decrease, thereby reducing the energy density. If you consider adding a heat-insulating sheet between the batteries, such as an aerogel board, it will also take up space and reduce the energy density), reducing the energy density of the battery pack. The phase change thermal insulation material of the present invention has good thermal conductivity at room temperature, which is beneficial to the thermal management of the battery pack.

[0027] The present invention also provides a soft-pack battery module, including a liquid cooling plate, and a battery cell assembly abutting the liquid cooling plate; the battery cell assembly includes a plurality of battery cells, and adjacent battery cells are separated by a barrier plate; the barrier plate is the phase change insulation barrier plate described in the above technical solution. The soft-pack battery module of the present invention has a triple effect on thermal runaway protection, including: the phase change material absorbs a large amount of heat when a phase change occurs at high temperature, the liquid cooling device transfers a large amount of heat, and the base material in the phase change insulation material blocks the transfer of heat between battery cells. The power battery thermal runaway blocking strategy of the present invention integrates the triple effects of heat absorption, heat insulation and heat dissipation, which can effectively block the thermal runaway of the ternary soft-pack battery module. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. 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 creative work.

[0029] Figure 1 It is a schematic diagram of the test model in the test case;

[0030] Figure 2 The temperature rise diagram of the front and back surfaces of each battery cell of the battery pack of Example 2;

[0031] Figure 3 This is a diagram of the thermal runaway blocking strategy for power batteries based on the triple effects of fusion heat absorption, heat insulation and heat dissipation according to the present invention. DETAILED DESCRIPTION

[0032] The present invention provides a phase-change thermal insulation barrier plate, comprising a phase-change thermal insulation material and a packaging film that packages the phase-change thermal insulation material;

[0033] The phase change thermal insulation material comprises a base material, and a phase change material and a flame retardant material adsorbed on the base material;

[0034] The substrate material includes silica nanofiber felt and a supporting material;

[0035] The phase change material includes one or more of silica sol, aluminum sol and saturated calcium chloride solution, and the flame retardant material includes a phosphorus-containing flame retardant.

[0036] In the present invention, unless otherwise specified, the materials and equipment used are commercially available products in the art.

[0037] In the present invention, the mass fraction of the phase change material in the phase change thermal insulation material is preferably 70-95%, more preferably 78%.

[0038] In the present invention, the mass fraction of silicon dioxide particles in the silica sol is preferably 0.1-3%, more preferably 1.5%; after water evaporates from the silica sol under thermal runaway conditions, silicon oxide aerogel is formed to further play a heat insulation role.

[0039] In the present invention, the phosphorus-containing flame retardant preferably includes triethyl phosphate (TEP) and / or triphenyl phosphate (TPP).

[0040] In the present invention, the average fiber diameter of the silica nanofiber felt is preferably 200 to 10000 nm, more preferably 400 to 450 nm, specifically 450 nm, and the density is preferably 140 to 160 mg / cm 3 , specifically 150.5 mg / cm 3 .

[0041] In the present invention, the thickness of the silica nanofiber felt is preferably 1 to 3 mm, specifically 1.5 mm.

[0042] In the present invention, the supporting material preferably comprises an aluminum film or a copper film, the supporting material is preferably inserted into the silica nanofiber felt, and the thickness of the supporting material is preferably 0.05 to 0.2 mm.

[0043] In the present invention, the packaging film is preferably an aluminum-plastic film, and the thickness of the aluminum-plastic film is preferably 0.1 mm. The packaging film is used to package the base material and the phase change material and the flame retardant material adsorbed on the base material.

[0044] In the present invention, the mass fraction of the supporting material in the phase change thermal insulation barrier plate is preferably 1-2%, the mass fraction of the silica nanofiber felt is preferably 10-18%, more preferably 12%, the mass fraction of the phase change material is preferably 60-83%, more preferably 70%, the mass fraction of the flame retardant material is preferably 1-10%, more preferably 6%, and the mass fraction of the encapsulation film is preferably 5-10%.

[0045] The present invention also provides a method for preparing the phase change thermal insulation barrier plate described in the above technical solution, comprising the following steps:

[0046] The silica sol and the polyethylene oxide solution are mixed, and the obtained dispersion is spun and calcined to obtain a silica nanofiber felt;

[0047] inserting a support material into the silica nanofiber felt to obtain a base material;

[0048] After coating the flame retardant material on the surface of the base material, the base material is immersed in the phase change material to obtain a phase change thermal insulation material;

[0049] The phase-change thermal insulation material is packaged to obtain the phase-change thermal insulation barrier plate.

[0050] In the present invention, the silica sol is obtained by mixing polyethyl silicate, oxalic acid, ethanol and water.

[0051] In the present invention, the mass ratio of polyethyl silicate, oxalic acid, ethanol and water is preferably 20-100:0.3:10:10-100, more preferably 50:0.3:10:10; the mixing reaction time is preferably 6 hours. The mixing reaction includes: hydrolysis of polyethyl silicate to generate ethyl orthosilicate, and preparation of silica sol using oxalic acid as a catalyst.

[0052] After obtaining the silica sol, the present invention mixes the silica sol with a polyethylene oxide solution, spins the obtained dispersion, and calcines it to obtain a silica nanofiber felt.

[0053] In the present invention, the concentration of polyethylene oxide (PEO) in the polyethylene oxide solution is preferably 0.1 g / mL; the weight average molecular weight (Mw) of polyethylene oxide in the polyethylene oxide solution is preferably 40,000; the polyethylene oxide solution is preferably obtained by mixing polyethylene oxide and water, and the mixing time is preferably 4 hours. The PEO is used for dispersion and flocculation, has high viscosity at low concentrations, and has a flocculation effect on polymers.

[0054] In the present invention, the silica sol and the polyethylene oxide solution are preferably mixed for 2 hours.

[0055] In the present invention, the spinning is preferably solution air spinning (SBS), and the spinning conditions include: the flow rate of the dispersion is preferably 4-8 mL / h, more preferably 6 mL / h, and the flow rate of the air is preferably 6-15 m / s, more preferably 10 m / s. The function of the air is to take away the solvent vapor volatilized from the stock solution thin flow through the hot air flow, so that the stock solution thin flow is solidified while gradually removing the solvent, and elongated and thinned under the action of the winding tension, thereby forming a primary fiber.

[0056] In the present invention, the calcination temperature is preferably 500-700° C., more preferably 600° C., and the calcination time is preferably 25-40 min, more preferably 30 min.

[0057] After obtaining the silica nanofiber felt, the present invention inserts a supporting material into the silica nanofiber felt to obtain a base material; after coating the surface of the base material with a flame retardant material, the base material is immersed in a phase change material to obtain the phase change thermal insulation barrier plate.

[0058] The present invention has no special requirements for the method of inserting the support material into the silica nanofiber mat, and the method commonly used by those skilled in the art can be used.

[0059] In the present invention, when the flame retardant material is preferably triphenyl phosphate (TPP), the triphenyl phosphate is preferably pre-melted before coating, and the pre-melting temperature is preferably 55°C.

[0060] In the present invention, the immersion is preferably performed until the base material absorbs the phase change material solution, and the time is several seconds to several tens of seconds.

[0061] After obtaining the phase-change thermal insulation material, the present invention packages the phase-change thermal insulation material to obtain the phase-change thermal insulation barrier plate.

[0062] In the present invention, the packaging preferably adopts aluminum-plastic film.

[0063] In the present invention, the thickness of the phase-change thermal insulation barrier plate in a free state is preferably 2 mm.

[0064] The present invention also provides the use of the phase change heat insulation barrier plate described in the above technical solution in the heat spread protection of soft-pack battery modules.

[0065] The present invention also provides a soft-pack battery module, comprising a liquid cooling plate, and a battery cell assembly abutting against the liquid cooling plate;

[0066] The battery cell assembly includes a plurality of battery cells, and adjacent battery cells are separated by a barrier plate; the barrier plate is the phase-change thermal insulation barrier plate described in the above technical solution or the phase-change thermal insulation barrier plate obtained by the above preparation method.

[0067] In the present invention, a flow channel is provided in the liquid cooling plate, and the flow channel is filled with cooling liquid.

[0068] In the present invention, the battery cell assembly preferably further includes a mica plate, the mica plate is on both sides of the plurality of battery cells, and the mica plate is used to isolate the contact between the battery cells and the fixture.

[0069] The structural schematic diagram of the soft pack battery module of the present invention is as follows Figure 1 As shown (excluding the heating plate). The battery module of the present invention can effectively block the heat spread of the large-capacity ternary soft-pack battery cell, and has a small number of parts and high space utilization of the battery module.

[0070] In order to further illustrate the present invention, the phase change thermal insulation barrier plate and its preparation method and application, and the soft-pack battery module provided by the present invention are described in detail below in combination with the accompanying drawings and embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0071] Example 1

[0072] 1. Preparation of silica nanofiber felt

[0073] First, 50g of polyethyl silicate, 0.3g of oxalic acid, 10g of ethanol and 10g of deionized water were mixed for 6h to obtain a uniform and transparent silica sol. Then, 3g of polyethylene oxide (Mw=40000) and 30g of deionized water were mixed for 4h to obtain a polyethylene oxide (PEO) solution. The PEO solution was then added to the silica sol and further mixed for 2h. Next, the obtained dispersion was transferred to a feed tank and sent to the spinneret of the SBS (solution air spinning) equipment through a gear pump. At the same time, a commercial air compressor was used to provide a continuous air supply to the annular air path around the spinneret. The liquid and gas flow rates of a single needle were set to 6mL / h and 10m / s, respectively. After the spinneret system was stabilized, the roller belt collection system began to continuously collect nanofibers. Next, the obtained precursor mat segments were calcined in an air atmosphere at 600℃ for 30min to produce a silica nanofiber felt with a thickness of about 1.5mm.

[0074] The prepared silica nanofiber mat has an average fiber diameter of 450 nm and a density of 150.5 mg / cm 3 .

[0075] Unless otherwise stated, all subsequent structural and performance studies use a density of 150.5 mg / cm 3 The silica nanofiber felt was prepared.

[0076] 2. Preparation of phase change insulation layer

[0077] An aluminum film (1 g) with a thickness of 0.2 mm was inserted into a silica nanofiber felt (6 g) with a thickness of 1.5 mm, and 3 g of triphenyl phosphate (TPP) was pre-melted at 55°C and evenly applied on the silica nanofiber felt inserted into the aluminum film; then it was immersed in 35 g of silica sol (silicon dioxide mass fraction 1.5%); and it was packaged with 5 g of aluminum-plastic film (thickness 0.113 mm) to obtain a heat spread protection plate (310 mm×100 mm×2 mm, 50 g).

[0078] 3. Selection and location of liquid cooling plate

[0079] The installation position of the liquid cooling plate is at the bottom of the battery pack, located on the side of the battery cell. The battery module and the liquid cooling plate are fixed with a fixing device, such as Figure 1 shown.

[0080] It uses an embedded tube liquid cooling plate, 400mm*330mm*20mm, the water channel diameter is 10mm, and the flow rate is set to 0.

[0081] Example 2

[0082] The difference from Example 1 is that the flow rate of the coolant in the liquid cooling plate is set to 0.1 L / s, and the battery cell is in full contact with the phase change insulation layer and the cold plate.

[0083] Test Example 1

[0084] The battery packs prepared in Example 1 and Example 2 were subjected to thermal runaway blocking tests, and ceramic fiber aerogel and glass fiber aerogel of the same thickness on the market were used as comparative samples. Figure 1 The thermal runaway blocking test results are shown in Table 1:

[0085] Table 1 Thermal runaway blocking test results

[0086]

[0087]

[0088] Figure 2 The temperature rise diagram of the front and back surfaces of each battery cell in the battery pack of Example 2, in which 1a, 1b, 2a, 2b, 3a, 3b, 4a, and 4b respectively represent Figure 1 The two sides of the battery cell from left to right in the model. The results show that the temperature rise curves of 1a and 1b are the temperature rise curves of the first battery that experiences thermal runaway. The temperature rise is fast, and the maximum temperature reaches over 500°C. Due to the effects of the phase change heat-absorbing material and the liquid cooling plate, the temperature drops quickly, and the subsequent battery cell temperature is low, and thermal runaway does not occur, indicating that the thermal insulation sheet has strong thermal insulation and thermal conductivity effects, and the module has a good cooling effect, indicating that the thermal runaway strategy is effective.

[0089] The present invention is based on a power battery thermal runaway blocking strategy that combines the triple effects of heat absorption, heat insulation and heat dissipation (such as Figure 3 As shown), it can effectively block the thermal runaway of the ternary soft-pack battery module.

[0090] Although the above-mentioned embodiments have made a detailed description of the present invention, they are only some embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on the embodiments of the present invention without creative work, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A phase change thermal insulation barrier plate, characterized in that: It includes a phase-change thermal insulation material and a packaging film that encapsulates the phase-change thermal insulation material; The phase change thermal insulation material comprises a base material, and a phase change material and a flame retardant material adsorbed on the base material; The substrate material includes silica nanofiber felt and a supporting material; The phase change material includes one or more of silica sol, aluminum sol and saturated calcium chloride solution; and the flame retardant material includes a phosphorus-containing flame retardant.

2. The phase change thermal insulation barrier plate according to claim 1, characterized in that: The mass fraction of the phase change material in the phase change thermal insulation material is 70-95%.

3. The phase change thermal insulation barrier plate according to claim 1, characterized in that: The phosphorus-containing flame retardant includes triethyl phosphate and / or triphenyl phosphate.

4. The phase change thermal insulation barrier plate according to claim 1, characterized in that: The average fiber diameter of the silica nanofiber felt is 200-10000 nm, and the density is 140-160 mg / cm 3 .

5. The method for preparing the phase-change thermal insulation barrier plate according to any one of claims 1 to 4, characterized in that: The following steps are involved: The silica sol and the polyethylene oxide solution are mixed, and the obtained dispersion is spun and calcined to obtain a silica nanofiber felt; inserting a support material into the silica nanofiber felt to obtain a base material; After coating the flame retardant material on the surface of the base material, the base material is immersed in the phase change material to obtain a phase change thermal insulation material; The phase-change thermal insulation material is packaged to obtain the phase-change thermal insulation barrier plate.

6. The preparation method according to claim 5, characterized in that: The silica sol is obtained by mixing polyethyl silicate, oxalic acid, ethanol and water, and the mass ratio of the polyethyl silicate, oxalic acid, ethanol and water is 20-100:0.3:10:10-100.

7. The preparation method according to claim 5, characterized in that: The spinning conditions include: the dispersion liquid and air flow rates are 4-8 mL / h and 6-15 m / s respectively.

8. The preparation method according to claim 5, characterized in that: The calcination temperature is 500-700° C. and the calcination time is 25-40 minutes.

9. Use of the phase-change thermal insulation barrier plate according to any one of claims 1 to 4 or the phase-change thermal insulation barrier plate obtained by the preparation method according to any one of claims 5 to 8 in heat spread protection of soft-pack battery modules.

10. A soft pack battery module, characterized in that: It includes a liquid cooling plate and a battery cell assembly abutting against the liquid cooling plate; The battery cell assembly includes a plurality of battery cells, and adjacent battery cells are separated by a barrier plate; the barrier plate is the phase-change thermal insulation barrier plate described in any one of claims 1 to 4 or the phase-change thermal insulation barrier plate obtained by the preparation method described in any one of claims 5 to 8.

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