CN112063245A

CN112063245A - High-temperature insulating coating for battery and preparation method thereof

Info

Publication number: CN112063245A
Application number: CN202010883522.6A
Authority: CN
Inventors: 刘俊兴; 崔祺; 钱礽淼; 焦露霞
Original assignee: Foiltec Industrial Co ltd
Current assignee: Foiltec Industrial Co ltd
Priority date: 2020-08-28
Filing date: 2020-08-28
Publication date: 2020-12-11

Abstract

The application discloses a high-temperature insulating coating for a battery and a preparation method thereof, which relate to the technical field of lithium ion batteries and comprise a third preparation liquid and a binder; the third preparation liquid comprises a first preparation liquid containing expanded particles and a second preparation liquid containing a graphite component; the graphite component is graphene or graphite; the expanded particles, the graphite component and the binder are as follows by mass percent: expanded particles: 1% -15%; graphite component: 40% -90%; adhesive: 8% -30%; the application is innovative to combine polymer expanded material and graphite alkene and be applied to it in the battery coating to make full use of its characteristic realizes the thermal automatic management and control of battery, and is more sensitive to the reaction of battery internal temperature, has more superior security performance, has compromise the normal electric path under the normal atmospheric temperature state again in addition, does not influence daily normal use.

Description

High-temperature insulating coating for battery and preparation method thereof

Technical Field

The application relates to the technical field of lithium ion batteries, in particular to a high-temperature insulating coating for a battery and a preparation method thereof.

Background

Lithium ion batteries, especially vehicle-mounted batteries, are mainly developed to achieve the maximum energy storage effect and shorten the charging time in a limited space, i.e., to improve the unit energy density and accelerate the charging efficiency.

The improvement of the unit energy density can be divided into two main directions, one of which is a material for seeking a high-voltage platform, and the mode possibly has the problems of overhigh internal resistance, unstable structure and the like; the other direction is to change the proportion of the electroactive substances or adjust the space structure of the battery, the current collector thickness is mainly reduced through the proportion adjustment, but the conductive sectional area is reduced after the current collector is reduced, so that the internal resistance is increased, and in addition, the difficulty of compaction and encryption of the electroactive layer is improved due to the reduction of the mechanical strength. In terms of the spatial structure adjustment direction, the conventional method is to change the shape of the cylindrical battery into a sheet-shaped soft package form, so that the heat cannot be smoothly conducted even though the energy density is increased. The space is adjusted and the thinning is mostly used currently, but the thinning item is slowed down due to the limitations of rolling technology, conductivity, mechanical strength and the like; the appearance of the battery is changed, and the heat dissipation problem occurs due to the overlarge volume of the single battery; coupled with the need for a fast charge, battery heat buildup is a problem that must be faced in a high voltage charging environment.

The existing manufacturers adopt a thermistor (PTC) to perform high-temperature aging control on the battery, so that the overheating of elements is avoided. However, for a bulky vehicle-mounted battery, a general thermistor cannot effectively respond to the heat generation inside the battery at the first time, cannot sense a local heat generation phenomenon inside the battery at the first time, and can respond correspondingly, and a time difference exists in temperature sensing. In addition, the common PTC is divided into two types, the first type is that the internal resistance is gradually increased, the PTC of the type has more obvious heating phenomenon along with the temperature rise due to the self problem of materials, and easily forms a reverse effect on a vehicle-mounted project to accelerate the battery deterioration; the second type is to use a direct phase change material such as BaTiO3, but its initial internal resistance is too high to meet the internal resistance requirement of the battery, if the conductive agent is added to increase its conductivity, its internal current will also move by selecting the path with the lowest resistance according to the cheschiff's law, so its performance will be greatly reduced.

The BMS (battery management system) also partitions the internal resistance increasing element, so that the BMS is used for managing and controlling the battery, and the battery is difficult to manage and control the internal behavior of the battery as the volume of the battery is increased along with the wide application of soft package batteries and hard shell batteries. Therefore, in order to solve the various problems in the prior art, a new approach to improvement and optimization is needed.

Disclosure of Invention

The application aims to provide a high-temperature insulating coating for a battery and a preparation method thereof.

In a first aspect, the present application provides a high-temperature insulating coating for a battery, comprising a third liquid formulation and a binder; the third preparation liquid comprises a first preparation liquid containing expanded particles and a second preparation liquid containing a graphite component; the graphite component is graphene or graphite;

the expanded particles, the graphite component and the binder are as follows by mass percent:

expanded particles: 1% -15%;

graphite component: 40% -90%;

adhesive: 8 to 30 percent.

Preferably, the expanded particles include an inner layer made of volatile hydrocarbon, and an outer coating layer wrapping the outer portion of the inner layer.

Preferably, the outer cladding layer is one of PAA (polyacrylic acid), PVDF (polyvinylidene fluoride), SBR (styrene butadiene rubber), PU (polyurethane), PS (polystyrene), and PVA (polyvinyl alcohol).

Preferably, the particle size of the graphite or graphene is 6-15 μm.

Preferably, the binder is one of PAA (polyacrylic acid), SBR (styrene butadiene rubber), PU (polyurethane).

Preferably, the first liquid preparation further comprises a particle dispersant.

Preferably, the second preparation liquid further comprises a graphite dispersing agent.

Preferably, the second preparation liquid further comprises a conductive agent.

In a second aspect, the present application provides a method for preparing a high temperature insulating coating according to any one of the above, comprising the steps of:

(1) mixing the components in the first prepared solution with an organic solvent or water according to a ratio, and stirring to obtain a prepared solution A; mixing the components in the second preparation solution with an organic solvent or water in proportion, and grinding the mixture in a nano grinder to obtain a preparation solution B;

(2) mixing the prepared solution A and the prepared solution B, and stirring to obtain a prepared solution C;

(3) and mixing the preparation solution C and the binder in proportion to obtain the coating.

Preferably, the grinding time of the second preparation liquid is 4-12 hours.

Compared with the prior art, the beneficial effect of this application lies in: according to the method, the solid polymer particles coated with the solvent or capable of subliming are added in the graphene coating, so that the expanded particles do not expand under a normal temperature state, and electric paths are formed among graphene molecules to generate a conductive effect; when a certain temperature is reached, the volatile hydrocarbon gas makes the whole expansion particles expand, so that graphene molecules are extruded, gaps are formed among the graphene molecules, the electric conductivity is reduced, the internal resistance is increased, and the effects of high resistance and even insulation are achieved, so that the automatic management and control of the heat of the battery are realized; in addition, when the temperature is gradually reduced, the expanded particles can be shrunk again, so that an electric path is formed between the graphene again, and the repeated application of the coating provided by the application is realized; the application is innovative to combine polymer expanded material and graphite alkene and be applied to it in the battery coating to make full use of its characteristic realizes the thermal automatic management and control of battery, and is more sensitive to the reaction of battery inside temperature, has more superior security performance, has compromise the normal electric path under the normal atmospheric temperature state again in addition, does not influence daily normal use.

Drawings

FIG. 1 is a flow chart of a method of making the present application;

FIG. 2 is a graph of the amount of surface internal resistance change with temperature for expanded particle EM504 at different addition levels;

FIG. 3 is a graph of the amount of surface internal resistance as a function of temperature for expanded particle EHM302 at various addition levels;

fig. 4 is a graph showing the amount of change in surface internal resistance with temperature of the expanded particle EML101 at different addition amounts;

FIG. 5 is a graph showing the amount of change in surface internal resistance of different expanded particles with temperature

FIG. 6 is a graph of the amount of surface internal resistance as a function of temperature for different conductive agent/graphite ratios;

FIG. 7 is a graph of the amount of surface internal resistance as a function of temperature for different graphite compositions at grinding times;

FIG. 8 is a graph showing the amount of surface internal resistance change with temperature for different amounts of addition of a particle dispersant;

Detailed Description

The technical scheme of the application is further described in detail by combining specific examples and comparative examples. The specific materials, amounts, data, and other conditions and details given in the examples and comparative examples are to be construed as illustrative of the present application and the scope of the present application is not limited by the examples. All simple modifications, equivalent changes and modifications made in accordance with the spirit of the present application fall within the scope of the claims of the present application.

All percentages, parts, ratios, etc. herein are by weight unless otherwise indicated.

The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

When an amount or other value is expressed as a range, preferred range, or upper limit of a preferred value and a lower limit of a preferred value, it is to be understood that this is to be construed as a specific recitation of any range where any pair of range upper or lower limits are combined, regardless of whether ranges are specifically disclosed.

The application discloses a high-temperature insulating coating for a battery, which comprises a third liquid preparation and a binder;

specifically, the third prepared liquid comprises a first prepared liquid and a second prepared liquid;

further, the first preparation liquid comprises swelling particles; the second preparation liquid comprises a graphite component, wherein the graphite component is graphene or graphite;

specifically, the expanded particles, the graphite component and the binder are as follows by mass percent:

expanded particles: 1% -15%;

graphite component: 40% -90%;

adhesive: 8 to 30 percent.

Specifically, the expanded particles comprise an inner layer made of volatile hydrocarbon and an outer coating layer wrapping the outer part of the inner layer;

further, the volatile hydrocarbon is volatile alkane, ketone, lipid, alcohol, etc.

Specifically, the outer cladding layer is one of PAA (polyacrylic acid), PVDF (polyvinylidene fluoride), SBR (styrene butadiene rubber), PU (polyurethane), PS (polystyrene), and PVA (polyvinyl alcohol).

Specifically, the particle size of the graphite or graphene is 6-15 μm.

Specifically, the binder is one of PAA (polyacrylic acid), SBR (styrene butadiene rubber), and PU (polyurethane).

In order to further optimize the service performance of the high-temperature insulating coating provided by the application, the application provides the following scheme:

specifically, the first preparation liquid also comprises a particle dispersing agent; the second preparation liquid also comprises a graphite dispersing agent and a conductive agent;

further, the conductive agent is a conductive additive such as carbon black, acetylene black and the like.

In the scheme, the particle dispersing agent is added into the first preparation liquid, so that the expanded particle texture is more uniform, and the homogeneous state can be kept in the processing process or the using process; the graphite dispersing agent is added into the second preparation liquid, so that the graphite can be uniformly dispersed, the influence on the processing and using processes due to the fact that the graphite is mixed into a whole is avoided, and meanwhile, the conductive performance of the coating is improved by adding the conductive agent.

Specifically, the application also provides a preparation method of the high-temperature insulating coating, which comprises the following steps:

Further, the organic solvent may be esters, including ethyl acetate, butyl acetate, etc.; can be an alkane, including methane, ethane, propane, butane, pentane, and the like; can be alcohols, including methanol, ethanol, isopropanol, n-butanol, etc.

The properties of the insulating coating provided by the present application will be further shown in the following specific examples.

The expanded particles adopted in the present application are purchased from hydrops chemical industry co, and the models are EML101, EHM302, and EM504, respectively, and the above expanded particles are used in the following experiments; the ingredients added in the following examples are all commercially available.

Example 1

Preparing raw materials of each component according to the following proportion:

(1) 1% of expanded particles, 0.1% of particle dispersant, 80% of graphite component, 6% of conductive agent, 2.9% of graphite dispersant and 10% of binder;

(2) 5% of expanded particles, 1% of particle dispersant, 60% of graphite component, 7% of conductive agent, 7% of graphite dispersant and 20% of binder;

(3) 10% of expanded particles, 2% of particle dispersing agent, 40% of graphite component, 8% of conductive agent, 10% of graphite dispersing agent and 30% of binder;

the expanded particles adopt EM 504;

the specific operation steps are as follows:

(1) mixing the expanded particles with a particle dispersant and stirring the mixture in an organic solvent to obtain a preparation liquid A; mixing a graphite component, a graphite dispersant and a conductive agent in an organic solvent, and putting the mixture into a nano grinder for grinding for 8 hours to obtain a preparation liquid B;

(3) mixing the preparation solution C and the binder in proportion to obtain a coating;

the coating obtained according to the three compositions of the embodiment is subjected to a subsequent test to obtain the amount of change of the internal resistance of the surface of the expanded particle EM504 with temperature under different addition amounts, which is shown in fig. 2.

Example 2

Referring to the mixture ratio in example 1, the expanded particle EM504 was replaced with the EHM302, and the specific operation method in example 1 was used to obtain the amount of change of the internal resistance of the surface with temperature at different addition amounts of the expanded particle EHM302, as shown in fig. 3.

Example 3

Referring to the mixture ratio in example 1, the expanded particle EM504 was replaced with the EML101, and referring to the specific operation method in example 1, the change of the internal resistance of the surface with temperature was obtained for different added amounts of the expanded particle EML101, specifically referring to fig. 4.

Example 4

Referring to the compounding ratio of the expanded particles of example 1 when the added amount is 5%, the surface internal resistances of different expanded particles, specifically, the expanded particles EM504, EHM302, and EML101, were compared with the temperature variation, and refer to fig. 5.

In addition, the addition amount of the dispersant is compared according to different particles, and the specific result is shown in fig. 8.

Example 5

(1) 5% of expanded particles, 1% of particle dispersant, 60% of graphite component, 0.6% of conductive agent, 13.4% of graphite dispersant and 20% of binder;

(2) 5% of expanded particles, 1% of particle dispersant, 60% of graphite component, 3% of conductive agent, 11% of graphite dispersant and 20% of binder;

(3) 5% of expanded particles, 1% of particle dispersant, 60% of graphite component, 6% of conductive agent, 8% of graphite dispersant and 20% of binder;

(4) 5% of expanded particles, 1% of particle dispersant, 60% of graphite component, 12% of conductive agent, 2% of graphite dispersant and 20% of binder;

the expanded particles adopt EHM 101;

the specific preparation method is as in example 1;

in this embodiment, the ratio between the conductive agent and the graphite is changed, and the effect between different conductive agent/graphite ratios is tested, and please refer to fig. 6 for a specific result;

example 6

5% of expanded particles, 1% of particle dispersant, 60% of graphite component, 3% of conductive agent, 11% of graphite dispersant and 20% of binder;

the expanded particles adopt EHM 101;

the specific preparation method is as in example 1;

in the present embodiment, the performance of the graphite component is tested at different grinding times, the grinding times are respectively tested at 4 hours, 6 hours and 12 hours, and the specific result is shown in fig. 7;

in particular, in combination with the above embodiments, and with reference to FIGS. 1-7, it can be seen that:

referring to fig. 1 to 3, when the addition amount of the expanded particles is changed, the resistance value increases more rapidly when the temperature reaches a designated temperature by 1% and 5%, and the resistance value increases more slowly when the addition amount of the expanded particles is 10%;

referring to fig. 5, when the same amount of different types of expanded particles are added, the three different types of expanded particles exhibit different critical temperatures, wherein EML101 reacts most rapidly, its resistance value starts to increase at about 110 ℃ and rapidly increases to over 200 ohms with temperature, while EHM302 starts to increase at about 130 ℃ and also rapidly increases its internal resistance value with temperature, and thus it can be seen that it has a sensitive response to temperature;

aiming at the phenomenon, operators can be matched with different expansion particles according to the requirements in the actual production process, so that the high-temperature insulating coating with different temperature critical values can be obtained, the application range of the high-temperature insulating coating provided by the application is greatly improved by the characteristics, and the high-temperature insulating coating is more flexible in actual use.

Referring to fig. 6, the ratio between the conductive agent and the graphite is changed, and as can be seen from fig. 6, when the ratio between the conductive agent and the graphite reaches 20%, the resistance value does not change significantly with the increase of temperature, and when the ratio between the conductive agent and the graphite is 1% and 5%, the resistance value can be adjusted sensitively according to the temperature.

Referring to fig. 7, the grinding time of the graphite component was changed while maintaining other variables, and it can be seen from fig. 7 that the comparative example in which the grinding time was 4 hours had an unstable resistance value change during the temperature rise and was in a wavy state, and the resistance value change was more stable than that in the grinding for 12 hours as the grinding time increased to 6 hours.

Referring to fig. 8, the addition amount of the particle dispersant is changed, and as can be seen from fig. 8, when the addition amount of the particle dispersant is 2%, the gradient of the internal resistance value along with the temperature rise is steeper than that of the other two groups, which indicates that the internal resistance value can reach a proper resistance value in a shorter time to realize the circuit isolation.

The technical core of the invention is that the graphite component and the expansion particles are organically combined into a whole in an innovative way, and the graphite component and the expansion particles are applied to the automatic temperature control of the battery; because the coating mode is adopted, the sensitivity of the coating to the temperature is excellent, and the self property of chemical substances is utilized to form a temperature control mechanism, so that the temperature control mechanism is quicker than the temperature control mechanism through various sensors and software;

as can be seen from a plurality of groups of drawings, the proportion among different components is one of the core invention points of the application, the effects of different proportions among different components are different, and the application obtains the optimal proportion through a plurality of groups of compounding experiments; meanwhile, the grinding time of the preparation B also has an influence on the final properties of the coating, and the influence relationship is not as simple as the grinding time is better, and a large amount of experiments are still required for testing so as to obtain the optimal grinding time.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. It will be readily apparent to those skilled in the art that various modifications can be made to the embodiments, and thus, several simple deductions or substitutions made without departing from the spirit and scope of the present invention should be considered as falling within the protection scope of the present invention.

Claims

1. A high-temperature insulating paint for batteries is characterized in that: comprises a third liquid preparation and a bonding agent; the third preparation liquid comprises a first preparation liquid containing expanded particles and a second preparation liquid containing a graphite component; the graphite component is graphene or graphite;

expanded particles: 1% -15%;

graphite component: 40% -90%;

adhesive: 8 to 30 percent.

2. A high temperature insulating coating according to claim 1, characterized in that: the expanded particles include an inner layer made of volatile hydrocarbon, and an outer cladding layer wrapping the outer portion of the inner layer.

3. A high temperature insulating coating according to claim 2, characterized in that: the outer cladding layer is one of PAA (polyacrylic acid), PVDF (polyvinylidene fluoride), SBR (styrene butadiene rubber), PU (polyurethane), PS (polystyrene) and PVA (polyvinyl alcohol).

4. A high temperature insulating coating according to claim 3, characterized in that: the particle size of the graphite or graphene is 6-15 μm.

5. A high temperature insulating coating according to claim 3, characterized in that: the binder is one of PAA (polyacrylic acid), SBR (styrene butadiene rubber) and PU (polyurethane).

6. A high temperature insulating coating according to claim 3, characterized in that: the first liquid preparation also comprises a particle dispersing agent.

7. A high temperature insulating coating according to claim 3, characterized in that: the second preparation liquid also comprises a graphite dispersing agent.

8. A high temperature insulating coating according to claim 3, characterized in that: the second preparation liquid also comprises a conductive agent.

9. A method for preparing a high temperature insulating coating according to any one of claims 1 to 8, characterized in that: the method comprises the following steps:

10. The method of claim 9, wherein: the grinding time of the second preparation liquid is 4-12 hours.