WO2022237378A1 - Self-heating battery and preparation method therefor - Google Patents

Abstract

The present invention relates to a self-heating battery and a preparation method therefor. The self-heating battery comprises a shell, a sealing cover, an inner core and a graphene heating film, wherein the inner core and the graphene heating film are placed in a sealing cavity, which is formed by the shell and the sealing cover fitting with each other; and the graphene heating film wraps the inner core, and the graphene heating film generates heat after being electrified, so as to heat the inner core. Heating is performed from inside a battery shell, such that the distance between a heating body and a heated body is shortened. Heat transfer can be performed in a plurality of ways (e.g. radiation, heat conduction and convection), and the heat transfer is sufficient. Therefore, an active material of a battery is quickly heated, and the battery can be quickly charged or discharged while being heated, without needing to be preheated.

Description

A kind of self-heating battery and its preparation method technical field

The invention relates to the field of power batteries, in particular to a self-heating battery and a preparation method thereof.

Background technique

Under the general environment of advocating environmental protection and energy saving, new energy vehicles are developing rapidly, electric vehicles, as the main force of new energy vehicles, have developed rapidly, and the power battery and battery cell industry has also developed rapidly. With the wide application of power batteries, their low-temperature performance defects are gradually emerging. In a low temperature environment, most batteries, especially the commonly used lithium-ion batteries, have the problems of battery capacity attenuation, discharge rate decrease, and driving mileage shrinkage. In some lithium-ion batteries, even because the ambient temperature is too low, lithium ions precipitate into lithium metal crystals, forming lithium dendrites to pierce the diaphragm, causing internal short circuits in the battery, leading to spontaneous combustion or explosion accidents. Therefore, in a low temperature environment, the power battery needs to be pre-heated before use or charging, and even during use, it needs to be heated and controlled to maintain the performance of the power battery.

At present, the heating methods used for the battery are all external heating of the battery, that is, heating the battery outside the battery casing, or heating the battery pack outside the battery pack, or a combination of the above two heating methods. The above-mentioned battery is called an externally heated battery. The disadvantages of the external heating battery and its external heating method are that the heating space range is large, the heat radiation and heat convection heat conduction paths are blocked by the battery casing and the battery pack casing, the effective use of heat is low, and the energy consumption is high; the battery active materials that really need to be heated The temperature of the substance rises slowly, the heating inside and between the batteries is uneven, and the improvement of the low-temperature performance of the power battery is affected. Moreover, because of the long heating path and many uncontrollable factors, battery thermal management is difficult.

Contents of the invention

In order to overcome the deficiencies of the prior art, the present invention provides a self-heating battery adopting an internal heating method.

The first aspect of the present invention provides a self-heating battery, comprising:

Shell, cover, inner core and graphene heating membrane, wherein,

The inner core and the graphene heating film are placed in the sealed cavity formed by the cooperation of the outer shell and the cover, and

The graphene heating film wraps the inner core, and the graphene heating film generates heat for heating the inner core after being energized.

In some embodiments of the present invention, the graphene heating film includes a substrate, a graphene heating material, a conductive tape, a first power supply line and a second power supply line, and the graphene heating material is coated on the substrate Above, the conductive strip is printed on the substrate and is in contact with the graphene heating material, and both the first power supply line and the second power supply line are connected to the conductive strip.

In some embodiments of the present invention, the graphene heating film further includes a graphene heating material covered on the substrate, a conductive strip, and an encapsulation material for the first power supply line and the second power supply line.

In some embodiments of the invention, the inner core of the self-heating battery is a rolled inner core.

In some embodiments of the present invention, the roll-shaped inner core includes a positive electrode material, a separator, a negative electrode material, and a separator that are sequentially stacked and wound into a spiral shape, and the gap between the shell, the positive electrode material, the separator, and the negative electrode material is forming a first electrolyte tank for injecting electrolyte;

The cover is provided with a first wire hole and a second wire hole, which are respectively used for the first power supply line and the second power supply line to pass through the cover and extend to the outside of the cover. A raised positive electrode is provided on the upper surface of the cover;

The positive electrode material is connected to the positive electrode ear, and the positive electrode ear is welded to the metal piece connected to the positive electrode; the negative electrode material is connected to the negative electrode ear, and the negative electrode ear is welded to the negative electrode.

In some embodiments of the present invention, a safety valve is provided in the middle of the cover to release the pressure of the gas generated by the abnormally high temperature of the battery to avoid explosion.

In some embodiments of the present invention, the end of the shell near the opening is provided with a shell neck slot, and the shell neck slot forms a collar inwardly for supporting the cover.

In some embodiments of the present invention, the negative electrode material is 0.5-1.5 mm wider than the positive electrode material; the negative electrode material is 5-10 mm longer than the positive electrode material to prevent lithium precipitation.

In some embodiments of the present invention, the separator must completely separate the positive electrode material from the negative electrode material. The width of the separator is usually 0.5-1.0 mm wider than that of the negative electrode material, and the length of the separator is usually 1-2.0 mm longer than that of the negative electrode material. The positive electrode material and the negative electrode material are contacted and short-circuited.

In some embodiments of the present invention, the length dimension of the graphene heating film is 3-10mm smaller than the perimeter dimension of the roll-shaped inner core, so as to prevent the overlapping of conductive bands and leakage short circuit; the width dimension of the graphene heating film is smaller than that of the roll-shaped inner core. The height dimension is 0.5-2.0mm smaller, which is convenient for fixing the graphene heating film.

In some embodiments of the invention, the inner core is a sheet-like inner core.

In some embodiments of the present invention, the sheet-shaped inner core includes sequentially stacked separators, positive electrode materials, separators, and negative electrode materials, and the gap between the positive electrode material, separator, negative electrode material, and casing forms the second electrolyte groove, the upper part of the sheet-shaped inner core is provided with an electrode cover, and the electrode cover is provided with a laminated positive electrode and a laminated negative electrode, the head end of the positive electrode material is connected to the laminated positive electrode, and the end of the negative electrode material Connected to the laminated negative electrode, the positive electrode material and the negative electrode material are connected in series in sequence;

The cover is provided with a third wire hole, a fourth wire hole and a liquid injection hole, and the third wire hole and the fourth wire hole are respectively used for the first power supply line and the second power supply line to pass through the cover and extend to Outside the cover, the liquid injection hole is used to inject electrolyte into the housing.

The present invention also provides a method for preparing a self-heating battery comprising a roll-shaped inner core, comprising:

The positive electrode material, the separator, the negative electrode material and the separator are superimposed in sequence, wound, edge-sealed, and a roll-shaped inner core is obtained;

The graphene heating film is wrapped around the roll-shaped inner core, and the graphene heating film is fixed to obtain the graphene roll-shaped inner core;

Place the graphene roll-shaped inner core in the shell, and carry out short-circuit inspection after spot welding the negative electrode;

Bake the shell with the graphene roll-shaped inner core, and then inject electrolyte into the shell;

Lead the first power supply line and the second power supply line through the first line hole and the second line hole on the cover, and then spot weld the positive electrode;

Insulate and seal the first wire hole and the second wire hole, and seal the gland to make a semi-finished product of the self-heating battery;

Clean and dry the semi-finished self-heating battery, and check the alignment of the semi-finished self-heating battery;

Qualified self-heating battery semi-finished products are subjected to casing coding, formation, storage aging, OCV (Open Circuit Voltage, open circuit voltage) test and capacity classification to obtain self-heating battery products.

In some embodiments of the present invention, the preparation method of the self-heating battery including the roll-shaped inner core further includes: performing a full appearance inspection on the finished self-heating battery, spraying grade codes, grade scanning, packaging, and warehousing.

In some embodiments of the present invention, the positive electrode material of the roll-shaped inner core is prepared as follows:

S111, homogenizing the positive electrode material containing the positive electrode active material, and then coating it on the positive electrode substrate;

S112, cutting the positive electrode substrate coated with the positive electrode material into positive electrode strips after rolling;

S113, baking the positive electrode strip, and welding tabs to the baked positive electrode strip;

S114, coating a protective glue on the connecting portion of the tab and the positive electrode strip to obtain the positive electrode material.

In some embodiments of the present invention, the negative electrode material of the roll-shaped inner core is prepared as follows:

S121, homogenizing the negative electrode material containing the negative electrode active material, and then coating it on the negative electrode substrate;

S122, cutting the negative electrode substrate coated with the negative electrode material into negative electrode strips after rolling;

S123, baking the negative electrode strip, and welding tabs to the baked negative electrode strip;

S124, coating a protective glue on the connecting part of the tab and the negative electrode strip to obtain the negative electrode material.

In some embodiments of the present invention, the graphene heating film of roll-shaped inner core is prepared as follows:

S131, homogenizing the graphene electrothermal material, and then coating it on the substrate;

S132, printing silver paste conductive tape on the substrate coated with graphene electrothermal material to obtain a semi-finished heating film;

S133, slicing the semi-finished heating film;

S134, welding the first power supply line and the second power supply line to the sliced semi-finished heating film.

In some embodiments of the present invention, the preparation method of the graphene heating film also includes:

S135, covering the packaging material with the semi-finished heating film after welding the first power supply line and the second power supply line, performing insulation and anti-corrosion packaging, and obtaining a graphene heating film.

The present invention also provides a method for preparing a self-heating battery comprising a flaky inner core, comprising:

The separator, the positive electrode material, the separator and the negative electrode material are stacked in sequence, and flat-pressed to obtain the pretreated product;

Weld the lugs of the pretreated products, seal the edges, and apply glue to obtain the flaky inner core;

The graphene heating film is wrapped around the flaky inner core, and the graphene heating film is fixed to obtain the graphene flaky inner core;

Putting the graphene flake inner core into the shell;

Leading the first power supply line and the second power supply line through the third line hole and the fourth line hole on the cover;

Insulate and seal the third wire hole and the fourth wire hole, and seal the gland to obtain an intermediate product;

Inject the electrolyte into the intermediate product through the liquid injection hole;

Preheating and pumping to seal the liquid injection hole to produce a self-heating battery semi-finished product;

The self-heating battery semi-finished product is formed, volumetric and OCV tested, and the self-heating battery product is obtained.

In some embodiments of the present invention, the preparation method of the self-heating battery including the sheet-shaped inner core further includes: performing a full appearance inspection, packaging, and storage of the finished self-heating battery.

In some embodiments of the present invention, the positive electrode material of the sheet-shaped inner core is prepared as follows:

S211, homogenizing the positive electrode material containing the positive electrode active material, and then coating it on the positive electrode substrate;

S212, cutting the positive electrode substrate coated with the positive electrode material into positive electrode strips;

S213, performing continuous rolling on the positive electrode belt;

S214 , die-cutting the rolled positive electrode strip, welding the tabs, and coating a protective glue on the connection between the tabs and the positive electrode strip to obtain a positive electrode material.

In some embodiments of the present invention, the negative electrode material of the sheet-shaped inner core is prepared as follows:

S221, homogenizing the negative electrode material containing the negative electrode active material, and then coating it on the negative electrode substrate;

S222, cutting the negative electrode substrate coated with the negative electrode material into negative electrode strips;

S223, performing continuous rolling on the negative electrode belt;

S224 , die-cutting the rolled negative electrode strip, welding the tabs, and coating a protective glue on the connection between the tabs and the negative electrode strip to obtain the negative electrode material.

In some embodiments of the present invention, the graphene heating film of sheet-like inner core is prepared as follows:

S231, homogenizing the graphene electrothermal material, and then coating it on the substrate;

S232, printing silver paste conductive tape on the substrate coated with graphene electrothermal material to obtain a semi-finished heating film;

S233, slicing the semi-finished heating film;

S234, welding the first power supply line and the second power supply line to the sliced semi-finished heating film.

In some embodiments of the present invention, the preparation method of graphene heating film also includes:

S235, covering the packaging material with the semi-finished heating film after welding the first power supply line and the second power supply line, and performing insulation and anti-corrosion packaging to obtain a graphene heating film.

The technical solution of the present invention has the following advantages:

1. Heating is carried out inside the battery casing. The distance between the heating body and the heating body is short, and heat transfer can be carried out in various ways (such as radiation, heat conduction, convection) and the heat transfer is sufficient. Therefore, the battery active material, such as the electrolyte, heats up quickly. It can quickly charge or discharge while heating without preheating, which is conducive to quickly increasing the capacity and discharge rate of the power battery, thereby fundamentally improving the low-temperature performance of the power battery and further improving the vehicle performance of the electric vehicle.

2. Because the heating is carried out inside the battery shell, the heating space is small, the heating efficiency is high, and the heating energy consumption is low, which can greatly reduce non-power energy consumption, which is conducive to maintaining the optimal temperature required by the power battery for a long time.

3. Since the graphene heating film has a temperature-limited heating characteristic, it can heat the battery with a limited temperature. Even if the battery management system fails, the power battery will not overheat due to heating, and the heating safety is good.

4. The structure is simple, which can greatly reduce the non-battery weight of the battery pack, and is conducive to improving the mass energy density of the battery pack.

Description of drawings

FIG. 1 is a schematic structural diagram of a self-heating battery provided in Example 2 of the present invention;

Fig. 2 is a schematic diagram of the housing in Embodiment 2 of the present invention;

Fig. 3 is the graphene heating film structure schematic diagram that the embodiment of the present invention provides;

Fig. 4 is a layered schematic diagram of a roll-shaped inner core in Example 2 of the present invention;

Fig. 5 is a schematic diagram of packaging of a wound cylindrical self-heating battery provided in Example 2 of the present invention;

Fig. 6 is a schematic diagram of the packaging of the laminated square self-heating battery provided by Embodiment 3 of the present invention;

Fig. 7 is a schematic structural view of the sheet-shaped inner core in Example 3 of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Example 1

A self-heating battery, including a shell, an inner core and a cover, the shell and the cover cooperate to form a sealed cavity for placing the inner core, the self-heating battery also includes a graphene heating film wrapping the inner core, the graphene After the heating film is energized, it generates heat for heating the inner core.

In the present invention, the inner core of the self-heating battery may include a positive electrode material, a negative electrode material, and a separator. Electrolyte can exist in the gap between the positive electrode material, the negative electrode material and the separator in the inner core of the self-heating battery. After the graphene heating film is energized, it generates heat to heat the electrolyte in the inner core.

In this embodiment, as shown in FIG. 3 , the graphene heating film includes a substrate, a first power supply line 111 , a second power supply line 112 , a conductive strip 113 and a graphene heating material 114 . A graphene heating material 114 is coated on the substrate, and a conductive strip 113 is printed on the substrate, and the conductive strip 113 is in contact with the graphene heating material 114 . Both the first power supply line 111 and the second power supply line 112 are connected to the conductive strip 113 .

In the present invention, printing the conductive strip on the substrate can be understood as printing the conductive strip directly on the substrate, that is, there is no other material between the conductive strip and the substrate, and the two are in direct contact, or the conductive strip is indirectly printed on the substrate. It is printed on the substrate, that is, the conductive strip is printed on the graphene heating material.

In the present invention, the contact between the conductive tape and the graphene heating material may be line contact or surface contact.

In the present invention, flexible support materials such as PET and PVC films can be used as the base material.

In the present invention, the graphene heating material may include water-based graphene oxide materials, carbon nanotubes, purified water, water-based modified resins, defoamers, and the like. Of course, it can be understood that other graphene heating materials known in the art can also be used to form the self-heating battery provided by the present invention.

In this embodiment, the graphene heating film further includes a graphene heating material covered on the base material, a conductive tape, and packaging materials for the first power supply line and the second power supply line, which are insulated and anti-corrosion packaged. When the graphene heating film wraps the inner core, the encapsulation material faces and is close to the inner core.

In the present invention, the encapsulation material can be the same as or different from the material of the base material, and the covering method can be film sticking or spraying.

The self-heating battery provided by the present invention, when it is charged, the first power supply line and the second power supply line can be connected to the charging front-end 220V or 380V alternating current, so that the graphene heating film generates heat. When the electric battery is discharged, the first power supply line and the second power supply line can be respectively connected to the overall positive pole and negative pole of the vehicle system power supply, battery pack, and battery pack, so that the graphene heating film can generate heat.

In this embodiment, the inner core of the self-heating battery may be a rolled inner core or a sheet inner core. A wound cylindrical self-heating battery can be fabricated using a rolled core. A laminated prismatic self-heating battery can be prepared using a sheet-like inner core.

The wound cylindrical self-heating battery and the laminated prismatic self-heating battery will be described in more detail below.

Example 2

Referring to Fig. 1-Fig. 5, a wound cylindrical self-heating battery is provided on the basis of Embodiment 1, including a casing 100, a rolled battery 120 and a cover 130, which also includes graphite wrapped around the rolled inner core 120 ene heating film 110; the roll-shaped inner core 120 includes a positive electrode material 121, a separator 122 and a negative electrode material 123, and the positive electrode material 121, separator 122, negative electrode material 123 and separator 122 are stacked in sequence and wound into a spiral shape. The roll-shaped inner core 120 is placed in the casing 100, the casing 100 is connected to the cover 130, and the gap between the casing 100, the positive electrode material 121, the diaphragm 122 and the negative electrode material 123 forms a first electrolyte tank 124 for Inject electrolyte.

In this embodiment, the cover 130 is provided with a first wire hole 131 and a second wire hole 134 for the first power supply line 111 and the second power supply line 112 to pass through the cover 130 and extend to the cover 130 respectively. Outside the cover 130 , a safety valve 132 is provided in the middle of the cover 130 , and a protruding positive electrode 133 is provided on the upper surface of the cover 130 .

In this embodiment, the positive electrode material 121 is connected to the positive electrode ear, and the positive electrode ear is welded to the metal piece connected to the positive electrode 133; the negative electrode material 123 is connected to the negative electrode ear, and the negative electrode ear is formed by the bottom of the casing. The negative electrode 102 is welded.

In this embodiment, the shell 100 is provided with a shell neck slot 101 at the end near its opening, and the shell neck slot 101 forms a collar inwardly for supporting the cover 130 . When sealing the housing with the cover, the upper surface of the collar contacts the sealing ring of the cover 130 and forms a seal by pressing.

In this embodiment, the negative electrode material 123 may be 0.5-1.5 mm wider than the positive electrode material 121; the negative electrode material 123 may be 5-10 mm longer than the positive electrode material 121 to prevent lithium precipitation.

In this embodiment, all separators are 0.5-1.0 mm wider than the negative electrode material and 1-2.0 mm longer than the negative electrode material.

In the present invention, the positive electrode material 121 and the negative electrode material 123 can be made into a substantially rectangular pole strip, and the rolled core 120 is formed by winding along the length direction of the positive electrode material 121 and the negative electrode material 123 . Therefore, the length of the positive electrode material 121 and the negative electrode material 123 can be understood as the size of a side substantially parallel to the winding direction of the roll-shaped inner core 120, and the width of the positive electrode material 121 and the negative electrode material 123 can be understood as being perpendicular to the roll-shaped inner core 120. The size of one side of the winding direction.

In this embodiment, the length of the graphene heating film 110 is 3 to 10 mm shorter than the circumference of the roll-shaped inner core 120, preventing the overlapping of conductive bands and leakage short circuit; The size is 0.5~2.0mm smaller, which is convenient for fixing the graphene heating film.

In the present invention, the graphene heating film 110 can be substantially rectangular, and when the graphene heating film 110 wraps the roll-shaped inner core 120, the length of the graphene heating film 110 is along the circumference of the roll-shaped inner core 120, and the graphene heating The width of the film 110 is along the height of the rolled core 120 .

In the present invention, the graphene heating film 110 can be fixed on the roll-shaped inner core 120 by adhesive tape.

The present invention also provides a method for preparing a wound cylindrical self-heating battery, which includes: stacking the positive electrode material 121, the separator 122, the negative electrode material 123 and the separator 122 in sequence, winding and sealing the edges to obtain a rolled inner core 120;

The graphene heating film 110 is wrapped around the roll-shaped inner core 120, and the graphene heating film 110 is fixed to obtain a graphene roll-shaped inner core;

Put the graphene roll-shaped inner core into the shell 100, and conduct a short-circuit inspection after spot welding the negative electrode 102;

Bake the shell 100 with the graphene rolled inner core, and then inject electrolyte into the shell 100;

Lead the first power supply line 111 and the second power supply line 112 through the first line hole 131 and the second line hole 134 on the cover 130, and then spot weld the positive electrode 133;

Insulating and sealing the first wire hole 131 and the second wire hole 134, and sealing them with a gland to obtain a semi-finished product of the self-heating battery;

Clean and dry the semi-finished self-heating battery, and check the alignment of the semi-finished self-heating battery;

Carry out casing coding, formation, storage aging, OCV test and capacity separation on qualified self-heating battery semi-finished products to obtain self-heating battery products;

Perform a full appearance inspection of the finished self-heating battery, spray grade code, grade scan, pack, and put into storage.

The present invention also provides a preparation method for the positive electrode material 121 of the wound cylindrical self-heating battery, which includes the following steps:

S111, homogenizing the positive electrode material containing the positive electrode active material, and then coating it on the positive electrode substrate;

S112, cutting the positive electrode substrate coated with the positive electrode material into positive electrode strips after rolling;

S113, baking the positive electrode strip, and welding tabs to the baked positive electrode strip;

S114 , coating a protective glue on the connecting portion of the tab and the positive electrode strip to obtain the positive electrode material 121 .

In the present invention, materials such as aluminum foil can be used as the positive electrode substrate, and the positive electrode substrate can be used as a positive electrode current collector.

The present invention also provides a preparation method for the negative electrode material 123 of the wound cylindrical self-heating battery, which includes the following steps:

S121, homogenizing the negative electrode material containing the negative electrode active material, and then coating it on the negative electrode substrate;

S122, cutting the negative electrode substrate coated with the negative electrode material into negative electrode strips after rolling;

S123, baking the negative electrode strip, and welding tabs to the baked negative electrode strip;

S124 , coating a protective glue on the connecting portion of the tab and the negative electrode belt to obtain the negative electrode material 123 .

In the present invention, copper foil and the like can be used as the negative electrode substrate, and the negative electrode substrate can be used as a negative electrode current collector.

The present invention also provides a preparation method of the graphene heating film 110 of the wound cylindrical self-heating battery, which comprises the following steps:

S131, homogenizing the graphene electrothermal material, and then coating it on the substrate;

S132, printing silver paste conductive tape on the base material coated with graphene electrothermal material to obtain a semi-finished heating film;

S133, slicing the semi-finished heating film;

S134, welding the power supply line to the sliced semi-finished product heating film;

S135, covering the semi-finished heating film after welding the power supply line with packaging material, performing insulation and anti-corrosion packaging, and obtaining the graphene heating film 110.

Example 3

Referring to Fig. 6 and Fig. 7, a laminated square self-heating battery is provided on the basis of Embodiment 1: it includes a casing 200, a sheet-shaped inner core 220 and a cover 230, which also includes a wrapping sheet-shaped inner core 220. Graphene heating film 110, the sheet-like inner core 220 includes diaphragm 222, positive electrode material 221, diaphragm 222, negative electrode material 223 stacked in sequence, the gap between the diaphragm 222, positive electrode material 221, diaphragm 222 and negative electrode material 223 A second electrolyte tank 224 is formed, an electrode cover 225 is arranged on the top of the sheet-shaped inner core 220, and a laminated positive electrode 231 and a laminated negative electrode 232 are arranged on the electrode cover, and the head end of the positive electrode material 221 is connected to the laminated positive electrode 231 , the end of the negative electrode material 223 is connected to the laminated negative electrode 232 , the positive electrode material 221 and the negative electrode material 223 are connected in series in sequence, the sheet-shaped inner core 220 is placed in the casing 200 , and the casing 200 is connected to the cover 230 .

In this embodiment, the positive electrode material 221, the diaphragm 222, and the negative electrode material 223 are sheet-shaped, and are stacked together in the order described above. Sheet separator 222, laminated negative electrode material 223.

In this embodiment, the cover 230 is provided with a third wire hole 234 and a fourth wire hole 235 for the first power supply wire 111 and the second power supply wire 112 to pass through the cover 230 and extend to the outer cover. 230 , the cover 230 is provided with a liquid injection hole 233 .

The present invention also provides a method for preparing a laminated square self-heating battery, which includes: sequentially stacking the separator 222, the positive electrode material 221, the separator 222 and the negative electrode material 223, and performing flat pressing to obtain a pretreated product;

Weld the lugs of the pretreated product, seal the edge, and apply glue to obtain the flaky inner core 220;

The graphene heating film 110 is wrapped around the flaky inner core 220, and the graphene heating film 110 is fixed to obtain a graphene flaky inner core;

Putting the graphene flake inner core into the shell 200;

Lead the first power supply line 111 and the second power supply line 112 through the third line hole 234 and the fourth line hole 235 on the cover 230;

Insulating and sealing the third line hole 234 and the fourth line hole 235, and sealing them with a gland to obtain an intermediate product;

Inject the electrolyte into the intermediate product through the liquid injection hole 233;

Preheating and pumping to seal the liquid injection hole to produce a self-heating battery semi-finished product;

Carry out formation, volumetric and OCV tests on semi-finished products of self-heating batteries to produce finished products of self-heating batteries;

Complete appearance inspection, packaging, and storage of the finished self-heating battery.

The present invention also provides a method for preparing the positive electrode material 221 of the laminated square self-heating battery, which includes the following steps:

S211, homogenizing the positive electrode material containing the positive electrode active material, and then distributing it on the positive electrode substrate;

S212, cutting the positive electrode substrate coated with the positive electrode material into positive electrode strips;

S213, performing continuous rolling on the positive electrode belt;

S214, die-cutting the rolled positive electrode strip, welding the tabs, and applying protective glue to the connection between the tabs and the positive electrode strip to obtain the positive electrode material 221;

The present invention also provides a method for preparing the negative electrode material 223 of the laminated square self-heating battery, which includes the following steps:

S221, homogenizing the negative electrode material containing the negative electrode active material, and then coating the negative electrode coating material mixed with the homogenate on the negative electrode substrate;

S222, cutting the negative electrode substrate coated with the negative electrode material into negative electrode strips;

S223, performing continuous rolling on the negative electrode belt;

S224 , die-cutting the rolled negative electrode strip, welding the tabs, and coating a protective glue on the connection between the tabs and the negative electrode strip to obtain the negative electrode material 223 .

In the present invention, the graphene heating film of the laminated square self-heating battery can be obtained by the same preparation method as the graphene heating film of the wound cylindrical self-heating battery.

The self-heating battery provided by the present invention can realize fast charging or discharging without preheating after being placed at -20°C for a long time, and can achieve a high battery capacity retention rate and charge-discharge rate, thereby fundamentally improving the performance of the power battery. Low temperature performance is also beneficial to simplify battery thermal management and increase the number of battery charge and discharge cycles.

For example, for a battery containing lithium iron phosphate, after adding a graphene heating film to form a self-heating battery provided by the present invention, its initial capacity is 17.020Ah. The battery was placed at -20°C for 16 hours, and then the graphene heating film was heated and charged and discharged. After testing, the battery discharge capacity was 16.777Ah, and the battery capacity retention rate reached 98.5%.

It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a relationship between these entities or operations. There is no such actual relationship or order between them. Furthermore, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article or apparatus comprising a set of elements includes not only those elements, but also includes elements not expressly listed. other elements of or also include elements inherent in such a process, method, article, or device. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (15)

1. A kind of self-heating battery is characterized in that, comprises shell, cover, inner core and graphene heating film, wherein,

   The inner core and the graphene heating film are placed in the sealed cavity formed by the cooperation of the outer shell and the cover, and

   The graphene heating film wraps the inner core, and the graphene heating film generates heat for heating the inner core after being energized.
2. The self-heating battery according to claim 1, characterized in that: the graphene heating film comprises a base material, a graphene heating material, a conductive tape, a first power supply line and a second power supply line, and the graphene heating material is coated with Distributed on the substrate, the conductive strip is printed on the substrate and is in contact with the graphene heating material, and both the first power supply line and the second power supply line are connected to the conductive strip .
3. The self-heating battery according to claim 2, characterized in that: the graphene heating film also includes a graphene heating material covered on the substrate, a conductive tape, a package of the first power supply line and the second power supply line Material.
4. The self-heating battery according to any one of claims 1-3, characterized in that the inner core is a roll-shaped inner core.
5. The self-heating battery according to claim 4, characterized in that: the roll-shaped inner core includes a positive electrode material, a separator, a negative electrode material, and a separator that are stacked in sequence and wound into a vortex;

   The gap between the casing, the positive electrode material, the diaphragm, and the negative electrode material forms a first electrolyte tank;

   The cover is provided with a first wire hole and a second wire hole, which are respectively used for the first power supply line and the second power supply line to pass through the cover and extend to the outside of the cover. A raised positive electrode is provided on the upper surface of the cover;

   The positive electrode material is connected to the positive electrode ear, and the positive electrode ear is welded to the metal piece connected to the positive electrode; the negative electrode material is connected to the negative electrode ear, and the negative electrode ear is welded to the negative electrode.
6. The self-heating battery according to claim 5, wherein a safety valve is arranged in the middle of the cover.
7. The self-heating battery according to any one of claims 4-6, characterized in that: the end of the casing near its opening is provided with a casing neck groove, and the casing neck groove forms a collar inwardly for Hold the cover in place.
8. The self-heating battery according to any one of claims 4-7, characterized in that:

   The negative electrode material is 0.5-1.5 mm wider than the positive electrode material;

   The negative electrode material is 5-10mm longer than the positive electrode material;

   The separator is 0.5-1.0 mm wider than the negative electrode material, and the separator is 1-2.0 mm longer than the negative electrode material.
9. The self-heating battery according to any one of claims 4-8, characterized in that:

   The length of the graphene heating film is 3-10mm shorter than the circumference of the roll-shaped inner core;

   The width of the graphene heating film is 0.5-2.0 mm smaller than the height of the roll-shaped inner core.
10. The self-heating battery according to any one of claims 1-3, characterized in that the inner core is a sheet-shaped inner core.
11. The self-heating battery according to claim 10, characterized in that: the sheet-shaped inner core comprises sequentially stacked separator, positive electrode material, separator and negative electrode material, and the gap between the positive electrode material, separator, negative electrode material, and casing is The gap forms a second electrolyte tank, an electrode cover is provided on the top of the sheet-shaped inner core, a laminated positive electrode and a laminated negative electrode are provided on the electrode cover, and the head end of the positive electrode material is connected to the laminated positive electrode, The end of the negative electrode material is connected to the laminated negative electrode, and the positive electrode material and the negative electrode material are connected in series in sequence;

    The cover is provided with a third wire hole, a fourth wire hole and a liquid injection hole, and the third wire hole and the fourth wire hole are respectively used for the first power supply line and the second power supply line to pass through the cover and extend to The cover is external.
12. The method for preparing a self-heating battery according to any one of claims 5-9, characterized in that it comprises:

    The positive electrode material, the separator, the negative electrode material and the separator are stacked in sequence, wound, and edge-sealed to obtain a roll-shaped inner core;

    The graphene heating film is wrapped around the roll-shaped inner core, and the graphene heating film is fixed to obtain the graphene roll-shaped inner core;

    Place the graphene roll-shaped inner core in the shell, and carry out short-circuit inspection after spot welding the negative electrode;

    Bake the shell with the graphene roll-shaped inner core, and then inject electrolyte into the shell;

    Lead the first power supply line and the second power supply line through the first line hole and the second line hole on the cover, and then spot weld the positive electrode;

    Insulate and seal the first wire hole and the second wire hole, and seal the gland to make a semi-finished product of the self-heating battery;

    Clean and dry the semi-finished self-heating battery, and check the alignment of the semi-finished self-heating battery;

    Qualified self-heating battery semi-finished products are subjected to casing coding, formation, storage aging, OCV testing and capacity separation to obtain finished self-heating batteries.
13. The method for preparing a battery according to claim 11, characterized in that: the separator, the positive electrode material, the separator and the negative electrode material are sequentially stacked and pressed flat to obtain a pretreated product;

    Weld the lugs of the pretreated products, seal the edges, and apply glue to obtain the flaky inner core;

    The graphene heating film is wrapped around the flaky inner core, and the graphene heating film is fixed to obtain the graphene flaky inner core;

    The graphene flake inner core is placed in the shell;

    Leading the first power supply line and the second power supply line through the third line hole and the fourth line hole on the cover;

    Insulate and seal the third wire hole and the fourth wire hole, and seal the gland to obtain an intermediate product;

    Inject the electrolyte into the intermediate product through the liquid injection hole;

    Preheating and pumping to seal the liquid injection hole to produce a self-heating battery semi-finished product;

    The self-heating battery semi-finished product is formed, volumetric and OCV tested, and the self-heating battery product is obtained.
14. The method for preparing a battery according to claim 12 or 13, characterized in that,

    The graphene heating film is prepared by the following method:

    Homogenize the graphene electric heating material, and then coat it on the substrate;

    Print silver paste conductive tape on the substrate coated with graphene electric heating material to obtain semi-finished heating film;

    Slicing the semi-finished heating film;

    The first power supply line and the second power supply line are welded to the sliced semi-finished heating film.
15. The preparation method of battery as claimed in claim 14, is characterized in that, the preparation method of described graphene heating film also comprises:

    The semi-finished heating film after welding the first power supply line and the second power supply line is covered with packaging material.

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