Battery module for delaying internal heat diffusion and preparation method and application thereof
阅读说明：本技术 一种延缓内部热扩散的电池模组及其制备方法和应用 (Battery module for delaying internal heat diffusion and preparation method and application thereof ) 是由 王雪涛 李�学 马华 李文文 于 2021-08-20 设计创作，主要内容包括：本发明涉及一种延缓内部热扩散的电池模组及其制备方法和应用。所述电池模组包括2个或2个以上电芯,所述电芯表面分别独立地设置有隔热包覆层；所述电池模组的制备方法包括：将隔热包覆层的原料混合制备成浆料；将所述浆料涂覆于电芯表面,得到被包覆的电芯；将被包覆的2个或2个以上电芯进行堆叠得到电芯组；将所述电芯组装进箱体,得到所述电池模组。本发明所述电池模组中,将隔热包覆层设置在每支电芯之间,可以有效地延缓热量扩散至相邻电芯,延缓模组热失控的时间；隔热包覆层中使用的胶类成分,起到粘结作用,可以取代电芯粘结的双面胶,有效节约模组的空间。(The invention relates to a battery module for delaying internal heat diffusion and a preparation method and application thereof. The battery module comprises 2 or more than 2 battery cells, and the surfaces of the battery cells are respectively and independently provided with a heat insulation coating layer; the preparation method of the battery module comprises the following steps: mixing the raw materials of the heat-insulating coating layer to prepare slurry; coating the slurry on the surface of the battery cell to obtain a coated battery cell; stacking the coated 2 or more than 2 electric cores to obtain an electric core group; and assembling the battery cell into a box body to obtain the battery module. In the battery module, the heat insulation coating layer is arranged between every two battery cores, so that heat can be effectively delayed from being diffused to the adjacent battery cores, and the time of thermal runaway of the module is delayed; the glue component used in the heat insulation coating layer plays a role in bonding, can replace double-sided adhesive tape bonded by the battery core, and effectively saves the space of the module.)
1. The utility model provides a delay battery module of inside thermal diffusion which characterized in that, battery module includes 2 or more than 2 electric cores, the electric core surface is provided with thermal-insulated coating respectively independently.
2. The battery module according to claim 1, wherein the heat insulating coating layer is a non-foamed coating layer or a foamed coating layer;
preferably, the raw materials of the non-foaming coating layer comprise a refractory material, a binder and a solvent;
preferably, the raw materials of the foaming coating layer comprise a foaming agent, a flame retardant and an emulsifier;
preferably, the raw materials of the non-foaming coating layer comprise 100 parts of a refractory material, 10-50 parts of an adhesive and 100-400 parts of a solvent in parts by weight;
preferably, the raw materials of the foaming coating layer comprise 100 parts by weight of foaming agent, 10-40 parts by weight of flame retardant and 3-8 parts by weight of emulsifier.
3. The battery module according to claim 2, wherein the refractory material comprises any one of boehmite, alumina, magnesia, silica, or titania, or a combination of at least two thereof;
preferably, the adhesive comprises any one of PVDF, SBR, CMC or polyacrylate or a combination of at least two thereof;
preferably, the solvent comprises any one of N-methyl pyrrolidone, deionized water, methyl ethyl ketone or isopropanol or a combination of at least two thereof;
preferably, the foaming agent comprises any one of acrylate, polyurethane, polyester polyol or isocyanate or a combination of at least two of the same;
preferably, the flame retardant comprises any one of or a combination of at least two of dimethyl allyl phosphate, melamine or ammonium polyphosphate;
preferably, the emulsifier comprises sodium lauryl sulfate and/or isomeric tridecanol polyoxyethylene ether.
4. The battery module according to any one of claims 1 to 3, wherein the heat insulating coating layer has a thickness of 1 to 100 μm, preferably 2 to 40 μm.
5. The battery module according to any one of claims 1 to 4, wherein the thermal insulation coating layer covers the surface of the battery cell completely or partially;
preferably, the area of the partial coverage is 50-80% of the stacking contact area of the battery cell.
6. The battery module according to any one of claims 1 to 5, wherein the heat insulating coating layer is coated in a manner including uniform coating or stripe coating.
7. A method for manufacturing a battery module according to any one of claims 1 to 6, comprising the steps of:
(1) mixing the raw materials of the heat-insulating coating layer to prepare slurry;
(2) coating the slurry obtained in the step (1) on the surface of the battery cell to obtain a coated battery cell;
(3) stacking 2 or more than 2 coated electric cores in the step (2) to obtain an electric core group;
(4) and (4) assembling the battery cell in the step (3) into a box body to obtain the battery module.
8. The method according to claim 7, wherein the mixing in step (1) is carried out by stirring;
preferably, the stirring speed is 800-2000 rpm;
preferably, the solid content of the slurry in the step (1) is 10-70%, and more preferably 20-50%
Preferably, the fineness of the slurry in the step (1) is less than or equal to 5 mu m.
9. The manufacturing method according to claim 7 or 8, wherein the type of the battery cell of the step (2) comprises any one of a soft pack, a square shape or a cylindrical shape;
preferably, the coating in step (2) comprises any one or a combination of at least two of spraying, dipping and printing;
preferably, the stacking manner of the step (3) is series connection and/or parallel connection;
preferably, the stack in the step (3) is pressurized and kept stand, and the pressure intensity of the pressurization is 0.1-1.0 MPa, and more preferably 0.3-0.6 MPa;
preferably, the stack in the step (3) is pressurized and kept stand, and the temperature for keeping stand is 20-85 ℃.
10. Use of a battery module according to any of claims 1 to 6 in the field of power batteries.
Technical Field
The invention relates to the technical field of batteries, in particular to a battery module and a preparation method and application thereof, and particularly relates to a battery module for delaying internal heat diffusion and a preparation method and application thereof.
Background
In recent years, with the rapid development of electric vehicles, the market demand for power batteries has been rapidly increased. Electric automobile driving system comprises the module, and the inside electric core of module is closely piled together, and the clearance is less between electric core and the electric core, about general 100 mu m, when a battery cell takes place the thermal runaway in the module, the heat spreads to adjacent battery cell very fast, leads to adjacent battery cell temperature to rise, and adjacent battery cell also takes place the thermal runaway along with it when the temperature rises to the certain degree, from this initiation chain reaction to lead to whole module out of control to cause serious consequence. Therefore, under the condition that a single battery core is out of control, the thermal diffusion speed is reduced as much as possible, the thermal control time of the whole module is prolonged, and more escape time is strived for users.
The mode that has delayed module heat diffusion uses the mica sheet, the aerogel, material such as thermal-insulated cotton plays thermal-insulated buffering's effect, but the addition of this kind of material can occupy certain module space, consequently most module design can increase one deck thermal insulation material every 2 ~ 6 electric cores, this effect variation that just leads to delaying heat diffusion, if every electric core increases this material of one deck in order to prevent heat diffusion to adjacent electric core, will lead to the effective space sharply reducing of module, thereby reduce the energy density of module by a wide margin.
At present, the reports on delaying the internal heat diffusion of the battery can be found, and mainly include that a heat insulating material or a flame retardant material is arranged between the batteries, and a heat insulating material or a flame retardant material is arranged between the battery cores.
CN213212223U discloses a compatible heat dissipation and battery module who restraines thermal runaway transmission, it sets up the fin between adjacent electric core subassembly, fin one side spraying insulating coating, opposite side spraying insulating coating and flame retardant coating can keep apart through thermal-insulated flame retardant coating between the adjacent electric core, when an electric core takes place the thermal runaway, can not transmit between the adjacent electric core, avoids the whole thermal runaway conduction of electric core module. The radiating fins are arranged between the adjacent electric core components, and have certain thickness and occupy module space; the heat insulation layer is only isolated by a fireproof mica coating layer, the function is single, and the heat insulation performance cannot play the best effect.
CN107978723A discloses a heat insulation cotton, a preparation method thereof and a battery module using the same, wherein the heat insulation cotton is applied between single batteries in the battery module, the heat insulation cotton comprises a heat insulation material and a flame retardant material, the two materials are mixed and added into a solvent, a proper amount of binder is added and stirred to obtain a mixed slurry, and the obtained mixed slurry is pressed and molded to obtain the heat insulation cotton. The heat insulation cotton is applied between the single batteries and is not applicable between the battery cores.
CN112310539A discloses a battery core module of battery core expend with heat and contract with cold displacement dynamic compensation thermal-insulated function in electric automobile power battery package and its preparation method, it is equipped with silica aerogel or hybridized silica aerogel felt cladding heat insulating sheet between the electric core, because expend with heat and contract with cold the effect and make electric core equipment stress even, guarantee that the operating temperature scope of lithium cell is in reasonable temperature interval. The safety of the aerogel felt is difficult to guarantee, and hidden dangers are brought to the safety and reliability of the electric automobile; because the material of its coating reaches 0.1 ~ 1.5mm including thickness such as silica gel fire prevention cloth, the thermal insulation material thickness of making is big, has occupied the space of module.
How to effectively delay battery module thermal diffusion, can also practice thrift battery module inner space simultaneously, be an important research direction in the battery module field.
Disclosure of Invention
In view of the problems in the prior art, the invention provides a module for delaying the internal thermal diffusion of a battery and a preparation method and application thereof, wherein each battery cell of the battery module is coated with a heat-insulating coating layer, so that the heat diffusion to an adjacent battery cell can be effectively delayed, the thermal diffusion speed is delayed, and the thermal diffusion performance of the module is improved; the thickness of thermal-insulated coating is steerable, and the coating can be controlled between 1 ~ 100 mu m as required to thermal-insulated coating has the adhesion, can replace the double faced adhesive tape, bonds electric core together, effectively practices thrift battery module's space, and battery module has higher energy density simultaneously.
In order to achieve the technical effect, the invention adopts the following technical scheme:
one objective of the present invention is to provide a battery module for delaying internal thermal diffusion, where the battery module includes 2 or more than 2 battery cells, and the surfaces of the battery cells are respectively and independently provided with a thermal insulation coating layer. The number of the battery cells may be 2, 3, 4, 5, 10, 50, or 100, but is not limited to the enumerated values, and other unrecited values in the range of the enumerated values are also applicable.
According to the invention, each electric core in the battery module is coated with the heat insulation coating layer, so that when one electric core is abnormally out of control due to heat, each electric core is coated with the coating layer, heat can be effectively delayed from being diffused to the adjacent electric core, the time of the adjacent electric core out of control is delayed, and the time of the battery module out of control is finally delayed.
According to the invention, the thickness of the heat-insulating coating layer is controllable, the heat-insulating coating layer has adhesiveness, double faced adhesive tapes can be replaced, the battery cores are bonded together, the module space can be effectively saved, the thickness of the heat-insulating coating layer can be controlled to be 1-100 mu m, and the thickness of a module formed by 24pcs battery cores can be saved by 0-2.254 mm.
As a preferable technical scheme of the invention, the heat insulation coating layer of the battery cell is a non-foaming coating layer or a foaming coating layer.
Preferably, the raw materials of the non-foaming coating layer comprise a refractory material, a binder and a solvent.
Preferably, the raw materials of the foaming coating layer comprise a foaming agent, a flame retardant and an emulsifier.
Preferably, the raw material of the non-foamed coating layer comprises, by weight, 100 parts of a refractory material, 10 to 50 parts of an adhesive, wherein the adhesive may be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, or the like, but is not limited to the enumerated values, and other non-enumerated values within the range of the enumerated values are also applicable, and 100 to 400 parts of a solvent, wherein the solvent may be 100 parts, 150 parts, 200 parts, 250 parts, 300 parts, 350 parts, or 400 parts, but is not limited to the enumerated values, and other non-enumerated values within the range of the enumerated values are also applicable.
Preferably, the raw material of the foaming coating layer comprises 100 parts by weight of foaming agent and 10-40 parts by weight of flame retardant, wherein the parts by weight of the flame retardant can be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts or 40 parts, and the like, but is not limited to the enumerated values, and other non-enumerated values in the numerical range are also applicable. 3-8 parts of emulsifier, wherein the parts by weight of the emulsifier can be 3 parts, 4 parts, 5 parts, 6 parts, 7 parts or 8 parts, and other numerical values in the numerical range are also applicable.
As a preferred embodiment of the present invention, the refractory material comprises any one or a combination of at least two of boehmite, alumina, magnesia, silica or titania, typical but non-limiting examples of which are: boehmite and alumina in combination, boehmite and alumina and titania in combination, magnesia and silica in combination, silica and boehmite in combination, and the like.
Preferably, the adhesive comprises any one of PVDF, SBR, CMC or polyacrylate or a combination of at least two of these, typical but non-limiting examples being: PVDF and SBR combinations, PVDF and CMC combinations, CMC and polyacrylate combinations, and the like.
Preferably, the solvent comprises any one of N-methyl pyrrolidone, deionized water, methyl ethyl ketone, or isopropanol, or a combination of at least two of these, typical but non-limiting examples being: combinations of N-methyl pyrrolidone and deionized water, combinations of N-methyl pyrrolidone and methyl ethyl ketone, N-methyl pyrrolidone, combinations of deionized water and methyl ethyl ketone, or combinations of N-methyl pyrrolidone, deionized water and isopropyl alcohol, and the like.
Preferably, the blowing agent comprises any one of, or a combination of at least two of, acrylates, polyurethanes, polyester polyols or isocyanates, typical but non-limiting examples of which are: combinations of acrylates and polyurethanes, combinations of acrylates and polyester polyols, combinations of acrylates and isocyanates or combinations of acrylates and polyurethanes and isocyanates, and the like.
Preferably, the flame retardant comprises any one of, or a combination of at least two of, dimethyl allyl phosphate, melamine or ammonium polyphosphate, typical but non-limiting examples of which are: a combination of dimethyl propyl phosphate and melamine, a combination of dimethyl propyl phosphate and ammonium polyphosphate, a combination of melamine and ammonium polyphosphate or a combination of dimethyl propyl phosphate and melamine and ammonium polyphosphate.
Preferably, the emulsifier comprises sodium lauryl sulfate and/or isomeric tridecanol polyoxyethylene ether.
In a preferred embodiment of the present invention, the heat insulating coating layer has a thickness of 1 to 100 μm, wherein the heat insulating coating layer may have a thickness of 2 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, or 95 μm, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned value range are also applicable, and preferably 2 to 40 μm.
The thickness of the heat-insulating coating layer adopted in the invention is small, and the thickness of the heat-insulating coating layer can be controlled to be 1-100 mu m according to the requirement, so that the space of the module is effectively saved. Can practice thrift 0 ~ 2.254mm to the module thickness that 24pcs electricity core constitutes.
As a preferred technical solution of the present invention, the heat insulating coating layer covers the surface of the battery cell completely or partially.
Preferably, the area of the partial coverage is 50 to 80% of the stacking contact area of the battery cell, wherein the area may be 50%, 55%, 60%, 65%, 70%, 75%, or 80%, etc., but is not limited to the recited values, and other values not recited in the range of the values are also applicable. The partial covering portion is an arbitrary portion of the unit surface.
As a preferable technical solution of the present invention, the coating manner of the heat-insulating coating layer includes uniform coating or stripe coating. The shape of the coating is determined according to the design requirements, and can be a round coating, a square coating, a zebra coating or the like.
It is another object of the present invention to provide a method for manufacturing a battery module according to the first aspect, the method comprising the steps of:
(1) mixing the raw materials of the heat-insulating coating layer to prepare slurry;
(2) coating the slurry obtained in the step (1) on the surface of the battery cell to obtain a coated battery cell;
(3) stacking 2 or more than 2 coated electric cores in the step (2) to obtain an electric core group;
(4) and (4) assembling the battery cell in the step (3) into a box body to obtain the battery module.
In a preferred embodiment of the present invention, the mixing in step (1) is stirring.
Preferably, the stirring rate is 800 to 2000rpm, wherein the rate may be 800rpm, 900rpm, 1000rpm, 1100rpm, 1200rpm, 1300rpm, 1400rpm, 1500rpm, 1600rpm, 1700rpm, 1800rpm, 1900rpm, 2000rpm, etc., but is not limited to the enumerated values, and other non-enumerated values within the range are also applicable.
Preferably, the solid content of the slurry in the step (1) is 10 to 70%, wherein the solid content may be 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc., but is not limited to the recited values, and other values not recited in the range of the values are also applicable, and more preferably 20 to 50%.
Preferably, the fineness of the slurry in the step (1) is less than or equal to 5 μm, wherein the fineness of the slurry can be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm, but is not limited to the enumerated values, and other unrecited values in the numerical range are also applicable.
As a preferred technical solution of the present invention, the type of the battery cell in step (2) includes any one of a soft bag, a square shape and a cylindrical shape, and the battery cell may also be a crescent shape, a pentagon shape and the like.
Preferably, the slurry coating manner in step (2) includes any one or a combination of at least two of spraying, dipping and printing.
Preferably, the cells in the step (3) are stacked in series and/or parallel.
Preferably, the pressure of the pressurization in the step (3) is 0.1 to 1.0Mpa, and the pressure of the pressurization may be 0.1Mpa, 0.2Mpa, 0.3Mpa, 0.4Mpa, 0.5Mpa, 0.6Mpa, 0.7Mpa, 0.8Mpa, 0.9Mpa, or 1.0Mpa, but is not limited to the enumerated values, and other values not enumerated within the numerical range are also applicable, and more preferably 0.3 to 0.6 Mpa.
Preferably, the temperature of the standing in the step (3) is 20 to 85 ℃, and the temperature may be 20 ℃, 25 ℃, 30 ℃, 35 ℃, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃ or 85 ℃, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.
The battery cell is put into the box body to form a finished product module through procedures of tab welding and the like, and the operation is conventional operation in the field and is not specially limited.
The invention also provides an application of the battery module as described in the first aspect, and the battery module is applied to the field of power batteries.
Compared with the prior art, the invention has at least the following beneficial effects:
(1) the heat insulation coating layer provided by the invention is arranged on each battery cell, so that heat can be effectively delayed from being diffused to the adjacent battery cells, the heat diffusion speed is delayed, the heat diffusion performance of the module is improved, and the thermal runaway interval of the two adjacent battery cells can be prolonged to 32 s.
(2) The thickness of the heat-insulating coating layer provided by the invention is controllable, and the heat-insulating coating layer has adhesion property, can replace double-sided adhesive tape, and can be used for bonding the battery cells together, the thickness of the heat-insulating coating layer can be controlled to be 1-100 mu m, and the thickness of a module formed by 24pcs battery cells can be saved by 0-2.254 mm.
(3) The heat-insulating coating layer provided by the invention has a good heat-insulating effect, and simultaneously enables the module to have higher module energy density, and the energy density can be improved by about 2%.
Drawings
Fig. 1 is a schematic diagram of uniform cell coating layers in examples 1, 3 to 8, 10 to 11 and comparative examples 1 to 2 of the present invention.
Fig. 2 is a schematic diagram of cell stack structures in examples 1 to 11 of the present invention and comparative example 1.
Fig. 3 is a schematic diagram of a strip-shaped battery cell cladding layer in embodiments 2 and 9 of the present invention.
Fig. 4 is a schematic diagram of cell taping in comparative examples 2-3.
Fig. 5 is a schematic diagram of a cell stack structure in comparative example 2.
FIG. 6 is a schematic diagram of the tests in examples 1 to 11 and comparative examples 1 to 2.
In the figure: 1-electric core; 2-double sided adhesive tape; 3-mica sheets; 31-heat insulating coating layer; 41-uniform coating layer; 51-strip-shaped coating layers; 61-heating plate; 62-a module housing; 63-temperature sensing line.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
Example 1
The battery module is prepared by the following steps:
(1) stirring and dispersing 100 parts of nano silicon dioxide, 30 parts of SBR and 200 parts of N-methyl pyrrolidone at 1400rpm to prepare slurry, wherein the solid content of the slurry is 40%, and the fineness of the slurry is 3 microns;
(2) uniformly coating the slurry on two surfaces of a battery cell (as shown in figure 1) by a coating layer with the thickness of 10 μm in a spraying manner;
(3) stacking the coated 4 battery cells together according to a series connection mode, wherein the stacking structure is shown in fig. 2, applying pressure of 800kgf to two ends of the stacked battery cells, placing the battery cells in a heat preservation box at 40 ℃, and standing for a period of time to obtain a battery cell group;
(4) and assembling the gel into a module according to a module assembling process after the gel is solidified.
Example 2
The battery module is prepared by the following steps:
(1) 100 parts of Al2O3The powder, 35 parts of PVDF and 200 parts of methyl ethyl ketone are stirred at 2000rpm to prepare slurry, the solid content of the solution is 10%, and the fineness is 2 mu m;
(2) printing the slurry into strips on one surface of each cell in a printing mode, wherein the thickness of each strip-shaped coating (shown in figure 3) is 2 microns;
(3) the 4 electric cores to be coated are stacked together in a parallel connection mode, the stacking structure is shown in figure 2, and the pole lugs are well insulated and protected. Applying 1200kgf pressure to the two ends of the stacked battery cell, placing the battery cell in a heat preservation box at 50 ℃, and bonding the battery cell together by glue in the coating layer;
(4) and (4) installing the bonded battery core and the copper bar into the box body, and forming a finished product module after the procedures of welding lugs and the like.
Example 3
The battery module is prepared by the following steps:
(1) 100 portions of nano Al2O3Stirring with 10 parts of SBR and 250 parts of deionized water at 1100rpm to prepare water-based slurry, wherein the solid content of the slurry is 25%, and the fineness of the slurry is 5 microns;
(2) uniformly coating the surface of the battery cell with a layer of slurry (shown in figure 1) in a dip-coating mode, wherein the thickness is 4 mu m, protecting the lug from being coated, and spraying a high-temperature adhesive with the thickness of 10 mu m on the surface of the coated layer after the coated layer is dried;
(3) stacking the coated 4 cells together in a series connection mode, wherein the stacking structure is as shown in fig. 2, applying pressure of 600kgf to two ends of the stacked cells, placing the cells in a 60 ℃ incubator, and standing for a period of time;
(4) and assembling the gel into a module according to a module assembling process after the gel is solidified.
Example 4
The battery module is prepared by the following steps:
(1) preparing a water-based foaming flame-retardant coating: adding 100 parts of aqueous polyurethane emulsion, 20 parts of allyl dimethyl phosphate and 4 parts of lauryl sodium sulfate into a reaction kettle with a stirring device, adding 20 parts of allyl dimethyl phosphate and 4 parts of lauryl sodium sulfate again, and uniformly stirring at 800 rpm;
(2) uniformly coating the uniformly stirred emulsion on one surface of the battery cell in a spraying manner (as shown in figure 1), wherein the thickness of the emulsion is 100 micrometers;
(3) stacking the coated 8 cells together in a series connection mode, wherein the stacking structure is as shown in fig. 2, and placing 400kgf of pressure applied to two ends of the stacked cells in a 20 ℃ incubator and standing for a period of time;
(4) and assembling the gel into a module according to a module assembling process after the gel is solidified.
Example 5
The battery module is prepared by the following steps:
(1) preparing a water-based foaming flame-retardant coating: adding 80 parts of polyester polyol, 40 parts of olefin melamine and 4 parts of tridecanol polyoxyethylene ether into a reaction kettle with a stirring device, adding 40 parts of melamine and 4 parts of isomeric tridecanol polyoxyethylene ether at one time, and uniformly stirring at 1700 rpm;
(2) uniformly coating the uniformly stirred emulsion on one surface of a battery cell in a spraying manner (as shown in figure 1), wherein the thickness of the emulsion is 20 microns;
(3) stacking the coated 4 cells together in parallel, wherein the stacking structure is as shown in fig. 2, and placing the stacked cells in a 30 ℃ incubator under 1000kgf pressure applied to the two ends of the cells, and standing for a period of time;
(4) and assembling the gel into a module according to a module assembling process after the gel is solidified.
Example 6
The coating thickness of the slurry on the surface of the cell was changed to 120 μm, and the rest was the same as in example 1.
Example 7
The thickness of the coating of the slurry on the surface of the cell was changed to 85 μm, and the rest was the same as in example 1.
Example 8
The thickness of the coating of the slurry on the surface of the cell was changed to 50 μm, and the rest was the same as in example 1.
Example 9
The coating method of the slurry on the surface of the battery cell is changed from uniform coating to strip coating (as shown in fig. 3), and the rest is the same as that of the example 1.
Example 10
The slurry was changed to 5% solids, the rest being the same as in example 1.
Example 11
The slurry was changed to 80% solids, the rest being the same as in example 1.
Comparative example 1
The coated cells were stacked in spaced order with one uncoated cell in between, and the rest was the same as in example 1.
Comparative example 2
The heat insulation coating layer is not arranged, the battery cells are bonded by double faced adhesive tape (as shown in fig. 4), and one mica sheet is arranged every four battery cells for stacking, wherein the stacking mode is as shown in fig. 5.
The battery cells used in examples 1 to 11 and comparative examples 1 to 2 were ternary materials as positive electrode active materials, graphite as negative electrode active materials, electrolyte, separator, and aluminum plastic film, and the capacity of the battery was 60 Ah.
The thermal diffusion performance and the energy density of the battery modules provided in examples 1 to 11 and comparative examples 1 to 2 were measured, and the results are shown in table 1.
According to the testing method of the thermal diffusivity performance, a planar heating device is added between the 2 nd cell and the 3 rd cell according to the graph shown in fig. 6, then the modules are assembled, the assembled modules are fully charged to 4.25V at 1C under the normal temperature condition, the heating device is started until the temperature reaches 300 ℃, and the time from the thermal runaway of the first cell to the thermal runaway of the last cell and the maximum temperature of the modules are recorded.
The energy density is calculated by the method of module capacity platform voltage/module volume
TABLE 1
Maximum temperature/DEG C of the module
Interval time/s
Energy Density/Wh/L
Example 1
537
9
527.62
Example 2
560
4
528.44
Example 3
549
7
527.89
Example 4
418
25
524.01
Example 5
529
11
527.62
Example 6
386
32
523.11
Example 7
442
23
524.68
Example 8
499
16
526.26
Example 9
540
9
527.62
Example 10
547
8
527.62
Example 11
503
13
527.62
Comparative example 1
554
6
528.07
Comparative example 2
580
3
524.01
Through the result, the time from the thermal runaway of the first branch battery cell to the complete thermal runaway of the module after the thermal insulation coating layer is added is increased, which shows that the performance of delaying the internal thermal diffusion of the module is obviously improved after the preparation method is implemented. Among them, it can be seen from examples 1 and 6 to 8 that the performance of retarding the heat diffusion is further improved as the thickness of the heat-insulating clad layer is increased, but the energy density of the module is slightly decreased. It can be seen from examples 1 and 10 to 11 that the increase in the solid content improves the heat diffusion retarding performance at the same thickness of the heat insulating coating layer. It can be seen from examples 1 and 9 that the improvement effect of the thermal diffusion retarding property and the energy density of the stripe coating and the whole coating are similar. The performance of retarding the thermal diffusion and the improvement effect of the energy density are similar in example 2 and example 3. In the embodiment 4 and the embodiment 5, the foaming flame-retardant coating is adopted, when the temperature of the battery core is increased, the substances in the coating can desorb part of heat and form bubbles, so that the heat transfer can be effectively isolated, and the effect of delaying heat diffusion is achieved. As can be seen from comparative example 1 and example 1, the thermal diffusion retardation performance of the coated cells stacked in spaced order is slightly reduced compared to the case where each cell was coated. Comparative example 2 is prior art, and it can be seen that the performance of the module for delaying internal heat diffusion and the energy density have certain differences compared with example 1, so the use of the heat-insulating coating layer has great significance for delaying heat diffusion and improving energy density.
The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, additions of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
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