CN115842215A - Diaphragm, pole piece, winding type battery cell, battery and power utilization device - Google Patents

Diaphragm, pole piece, winding type battery cell, battery and power utilization device Download PDF

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Publication number
CN115842215A
CN115842215A CN202211321119.XA CN202211321119A CN115842215A CN 115842215 A CN115842215 A CN 115842215A CN 202211321119 A CN202211321119 A CN 202211321119A CN 115842215 A CN115842215 A CN 115842215A
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China
Prior art keywords
pole piece
coating
battery
diaphragm
membrane
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CN202211321119.XA
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Chinese (zh)
Inventor
程兴
伍永彬
牛少军
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Contemporary Amperex Technology Co Ltd
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Contemporary Amperex Technology Co Ltd
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Priority to CN202211321119.XA priority Critical patent/CN115842215A/en
Publication of CN115842215A publication Critical patent/CN115842215A/en
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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Abstract

The application discloses diaphragm, pole piece, coiling formula electric core, battery and power consumption device, the diaphragm includes: the diaphragm has first and second ends opposite in a length direction, the diaphragm decreasing in thickness in a direction from the first end toward the second end. According to the diaphragm of this application, through making the diaphragm from first end to the thickness reduction of second end, can make the clearance of the inner circle of electric core and the clearance of outer lane tend to unanimously, avoid because of the too big or undersize inflation that leads to of clearance is educed lithium, is soaked badly and interface black spot scheduling problem, can also avoid the pole piece because of the risk of great extrusion force fracture short circuit in causing the battery to guarantee the cyclicity performance of battery.

Description

Diaphragm, pole piece, winding type battery cell, battery and power utilization device
Technical Field
The application relates to the technical field of batteries, in particular to a diaphragm, a pole piece, a winding type battery cell, a battery and an electric device.
Background
In a power battery, a conventional lithium ion battery is generally formed by winding or laminating a positive electrode sheet, a separator, and a negative electrode sheet into a cell. For the battery core formed by winding in the related technology, the problems of cycle expansion lithium precipitation, poor infiltration, interface black spot and the like exist, and the cycle performance of the battery core is influenced.
Disclosure of Invention
The present application is directed to solving at least one of the problems in the prior art. Therefore, the first aspect of the present application is to provide a separator, which can make the gap of the inner ring and the gap of the outer ring of the battery cell tend to be consistent, and avoid the problems of expansion lithium precipitation, poor infiltration, black spots on the interface and the like caused by too large or too small gaps.
The second aspect of the present application also provides a pole piece.
The third aspect of the present application further provides a winding type battery cell.
The fourth aspect of the present application also provides a battery.
The fourth aspect of the present application also provides an electric device.
The separator according to the first aspect of the present application is applied to a wound-type electric core, and has a first end and a second end opposite to each other in a length direction, and a thickness of the separator decreases in a direction from the first end toward the second end.
According to the diaphragm of this application, through making the diaphragm from first end to the thickness reduction of second end, can make the clearance of the inner circle of electric core and the clearance of outer lane tend to unanimously, avoid because of the too big or undersize inflation that leads to of clearance is educed lithium, is soaked badly and interface black spot scheduling problem, can also avoid the pole piece because of the risk of great extrusion force fracture short circuit in causing the battery to guarantee the cyclicity performance of battery.
In some embodiments, the diaphragm has a thickness that gradually decreases in a direction from the first end toward the second end.
This embodiment reduces gradually through the thickness that makes the diaphragm from first end to second end, and the change of tightening force when can making the thickness change of diaphragm more match the coiling makes the uniformity of electric core in the clearance of each position better.
In some embodiments, the diaphragm includes a plurality of membrane segments connected in series in a direction from the first end toward the second end, and a thickness of the membrane segment toward the first end is greater than a thickness of the membrane segment toward the second end in adjacent two of the membrane segments.
This embodiment is through dividing the diaphragm into a plurality of membrane sections along length direction, can conveniently control the thickness of diaphragm, simplifies the control procedure of diaphragm thickness, simplifies diaphragm processing, makes things convenient for the shaping of diaphragm, reduces the technology degree of difficulty and manufacturing cost.
In some embodiments, the septum comprises: a film body and a coating provided on at least one side surface of the film body, the coating decreasing in thickness in a direction from the first end toward the second end.
This embodiment is through making the diaphragm include membrane main part and coating to the thickness that makes the coating reduces from first end to second end, like this, can control the thickness of diaphragm through the thickness of control coating, can make things convenient for diaphragm machine-shaping from this, reduces the production degree of difficulty and manufacturing cost.
In some embodiments, the coating comprises a high molecular weight polymer and a binder.
In the embodiment, the coating comprises the high molecular polymer and the binder, so that the coating has high modulus and incompressible performance in winding, thus the gap of the battery core wound on the inner ring can be effectively increased, the friction resistance between the coating and the pole piece can be increased, and the slippage of the pole piece and the diaphragm is reduced, so that the gap consistency of the inner ring and the outer ring of the battery core is better, and the cycle performance of the battery is improved.
In some embodiments, the high molecular polymer comprises at least one of polyvinylidene fluoride, polyvinyl alcohol, polymethacrylic acid, polyvinyl sulfonate, and polyethylene glycol; and/or the binder is at least one of styrene butadiene rubber, sodium alginate, styrene-acrylic latex and polyacrylic acid.
In this embodiment, the high molecular polymer is limited to include at least one of polyvinylidene fluoride, polyvinyl alcohol, polymethacrylic acid, polyvinyl sulfonate and polyethylene glycol, and the binder is at least one of styrene butadiene rubber, sodium alginate, styrene-acrylic latex and polyacrylic acid, so that the high molecular polymer and the binder can be selected according to design requirements, thereby reducing cost.
In some embodiments, the coating has an average thickness of 1 μm to 30 μm at the surface of the film body.
In the embodiment, the average thickness of the coating is 1-30 μm, so that the consistency of the gap between the inner ring and the outer ring of the battery cell is better, and the cycle performance of the battery is improved.
In some embodiments, the coating has an average distributed mass of 0.1g/m over the surface of the film body 2 -2g/m 2 。
The embodiment can control the spraying thickness of the coating by controlling the spraying weight of the coating by limiting the quality of the coating in unit area, is convenient to operate, and can improve the spraying efficiency of the coating on the premise of ensuring the spraying thickness of the coating.
In some embodiments, the mass per unit area of the coating at the first end is greater than the mass per unit area of the coating at the second end.
In this embodiment, the mass per unit area of the coating at the first end is greater than the mass per unit area of the coating at the second end, so that the thickness of the coating at the first end is greater than the thickness of the coating at the second end, thereby improving the gap consistency between the inner ring and the outer ring of the battery cell, controlling the thickness of the coating by controlling the mass of the coating in the unit area, improving the spraying efficiency of the coating, and simplifying the control flow of coating spraying.
In some embodiments, the coating has a decreasing mass per unit area in a direction from the first end toward the second end, and the coating has a gradient of decreasing mass of 10g/m or less 3 。
In the embodiment, the spraying quality of the coating per unit area in the direction from the first end to the second end is gradually reduced, and the mass reduction gradient of the coating is less than or equal to 9g/m 3 Can make the coatingThe thickness change of layer more matches the change of tightening force, improves the clearance uniformity of electric core inner circle and outer lane.
In some embodiments, the total area of the coating is 10% to 90% of the total area of the film body.
In the embodiment, the total area of the coating accounts for 10-90% of the total area of the film main body, so that the weight and the cost can be reduced and the processing efficiency can be improved on the premise of improving the gap consistency of the inner ring and the outer ring of the battery cell and the gap consistency of different axial positions.
According to the pole piece of the second aspect of the application, the pole piece is applied to the winding type battery cell, a plurality of protrusions are formed on the surface of the pole piece, and the height of the protrusions is reduced in the direction from one end of the pole piece in the length direction to the other end of the pole piece.
According to the pole piece, the height of the bulge on the pole piece is reduced from one end of the length direction to the other end of the pole piece, so that the gap of the inner ring of the battery cell and the gap of the outer ring tend to be consistent, the problems of lithium precipitation due to expansion caused by overlarge or undersize gaps, poor infiltration, interface black spots and the like are avoided, the risk of short circuit in the battery caused by breakage of the pole piece due to large extrusion force can be avoided, and the cycle performance of the battery is ensured.
In some embodiments, the height of the projection gradually decreases in a direction from one end of the pole piece in the length direction toward the other end.
This embodiment is through making bellied height reduce gradually from the one end of pole piece to the other end, and the change of tightening force when can making bellied altitude variation match the coiling more makes the uniformity in the clearance of electric core in each position better.
In some embodiments, said pole piece comprises a plurality of subsections connected in sequence in a direction from said one end to another end, and in two adjacent subsections, the height of said projection of said subsection towards said one end is greater than the height of said projection of said subsection towards said another end.
According to the pole piece, the pole piece is divided into the plurality of subsections along the length direction, the height of the protrusions on the pole piece can be conveniently controlled in a segmented mode, the processing of the protrusions is simplified, and the process difficulty and the production cost are reduced.
In some embodiments, the height of the protrusions is less than or equal to 5mm, and/or the maximum size of the protrusions on the surface of the pole piece is less than or equal to 10mm, and/or the density of the protrusions is less than or equal to 100ea/cm 2 。
In the embodiment, the height of the protrusions is not more than 5mm, the maximum width of the protrusions on the surface of the pole piece is not more than 10mm, and the density of the protrusions is not more than 100ea/cm 2 The structure of the salient can be optimized on the premise of improving the rigidity of the pole piece and avoiding the wrinkles of the pole piece, and the processing and the manufacturing are convenient.
The winding type battery cell comprises a pole piece and a diaphragm, wherein the pole piece comprises a positive pole piece and a negative pole piece, the diaphragm is arranged between the positive pole piece and the negative pole piece, the diaphragm is the diaphragm of the first aspect of the application, and/or at least one of the positive pole piece and the negative pole piece is the pole piece of the second aspect of the application.
According to the winding type battery cell, by arranging the diaphragm of the first aspect embodiment and/or the pole piece of the second aspect embodiment, the gap of the inner ring of the battery cell and the gap of the outer ring tend to be consistent, the problems of expansion lithium precipitation and poor infiltration caused by the undersize gap of the inner ring of the battery cell are effectively avoided, the pole piece can be prevented from bearing larger extrusion force caused by the undersize gap when the pole piece expands, and the risk of short circuit in the battery caused by the breakage of the pole piece is avoided; the problems of poor infiltration, interface black spots and the like caused by overlarge outer ring clearance of the battery core can be avoided, the cycle performance of the battery is ensured, the safety performance of the battery is improved, and the service life of the battery is prolonged.
The battery according to the fourth aspect of the present application includes the winding type battery cell according to the third aspect of the present application.
According to the battery of the application, the winding type battery cell of the third aspect is arranged, so that the overall performance of the battery is improved.
The electric device according to the fifth aspect of the present application includes the battery according to the fourth aspect of the present application for supplying electric energy.
According to the electric device of the present application, the battery of the fourth aspect is provided, thereby improving the overall performance of the electric device.
Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.
Drawings
Fig. 1 is an exploded view of a battery according to an embodiment of the present application; a schematic diagram of (a);
FIG. 2 is a schematic view of a diaphragm according to a first embodiment of the present application;
FIG. 3 is a schematic illustration of a pole piece according to an embodiment of the present application;
fig. 4 is a diagram illustrating the relationship between the number of winding turns and the gap of the battery according to the first embodiment of the present application;
FIG. 5 is a schematic view of a septum according to example two of the present application;
fig. 6 is a diagram illustrating the relationship between the number of winding turns and the gap of the battery according to the second embodiment of the present application.
Reference numerals:
100. a battery;
10. a housing; 20. an end cap; 30. an electric core;
31. a diaphragm; 31a, a first end; 31b, a second end; 311. a film body; 312. coating;
32. pole pieces; 321. and (4) protruding.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are merely used to more clearly illustrate the technical solutions of the present application, and therefore are only examples, and the protection scope of the present application is not limited thereby.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "including" and "having," and any variations thereof, in the description and claims of this application and the description of the above figures are intended to cover non-exclusive inclusions.
In the description of the embodiments of the present application, the technical terms "first", "second", and the like are used only for distinguishing different objects, and are not to be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary-secondary relationship of the technical features indicated. In the description of the embodiments of the present application, "a plurality" means two or more unless specifically defined otherwise.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.
In the description of the embodiments of the present application, the term "and/or" is only one kind of association relationship describing an associated object, and means that three relationships may exist, for example, a and/or B, and may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.
In the description of the embodiments of the present application, the term "plurality" refers to two or more (including two), and similarly, "plural sets" refers to two or more (including two), and "plural pieces" refers to two or more (including two).
In the description of the embodiments of the present application, the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like, indicate orientations and positional relationships that are based on the orientations and positional relationships shown in the drawings, and are used for convenience in describing the embodiments of the present application and for simplification of the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus, should not be construed as limiting the embodiments of the present application.
In the description of the embodiments of the present application, unless otherwise explicitly stated or limited, the terms "mounted," "connected," "fixed," and the like are used in a broad sense, and for example, may be fixedly connected, detachably connected, or integrated; mechanical connection or electrical connection is also possible; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the embodiments of the present application can be understood by those of ordinary skill in the art according to specific situations.
At present, the application of the power battery is more and more extensive from the development of market situation. The power battery is not only applied to energy storage power supply systems such as hydraulic power, firepower, wind power and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric automobiles and the like, and a plurality of fields such as military equipment and aerospace. With the continuous expansion of the application field of the power battery, the market demand is also continuously expanding.
The applicant has noted that, for a winding type battery, the battery is generally formed by winding a positive plate, a diaphragm and a negative plate into a cell, however, as the number of winding turns of the cell increases, the plate and the diaphragm are continuously tightened under continuous tension, and slippage occurs. At the moment, for the inner ring of the battery core, the bulges generated on the pole pieces by the embossing rollers are easily compressed and deformed, so that the gap between the pole pieces of the inner ring is reduced, the infiltration of electrolyte on the pole pieces is influenced, the ion transmission path is changed, and the problem of expansion lithium precipitation of the battery in the charging and discharging circulation process is caused. Meanwhile, the pole piece can expand outwards in the charging and discharging cycle process, and the pole piece can bear large extrusion force for a long time due to too small gap, so that the risk of short circuit in the power generation battery caused by pole piece fracture is easily caused. For the outer ring of the battery core, due to insufficient tension, the gap between the pole pieces is too large, and the problems of poor pole piece infiltration, interface black spots and the like can be caused.
In order to solve the problem of inconsistent gaps between the inner ring and the outer ring of the battery, the applicant researches and discovers that a larger gap can be reserved for the inner ring battery cell in design, and a smaller gap can be reserved for the outer ring battery cell, so that the gaps between the inner ring and the outer ring are consistent under the tension action of the pole piece and the diaphragm along with the increase of the number of winding turns.
In view of the above, in order to achieve the problem of keeping the gap of the battery cell consistent under the tension of the battery cell during the winding process, the applicant has conducted intensive research and has designed a separator and a pole piece, wherein the thickness of the separator is reduced in the direction from the first end to the second end in the length direction, for example, the thickness of the separator is reduced in a stepwise manner or gradually from the first end to the second end. By making the projections of the pole piece surface decrease in height in the direction from one end toward the other end in the length direction of the pole piece, for example, the height of the projections decreases stepwise or gradually from one end to the other end of the pole piece.
When the diaphragm is adopted to wind the battery core of the battery, the diaphragm can be gradually wound to the second end from the first end of the diaphragm along the length direction, so that the initial winding gap of the inner ring of the formed battery core is larger as the thickness of the diaphragm at the first end is larger than that of the second end, but the pole piece and the diaphragm can be continuously tightened up under the action of continuous tension as the winding continues, and therefore, when the final winding is completed, the gap of the inner ring of the battery core can be reduced compared with the initial winding gap. Therefore, the gap of the inner ring and the gap of the outer ring of the finally wound battery cell tend to be consistent, so that the problems of expansion lithium precipitation, poor infiltration, black spots on the section and the like caused by overlarge or undersize gaps can be effectively avoided, and the cycle performance of the battery is ensured.
When adopting this kind of pole piece to carry out the electric core of battery and coiling, can follow the one end of pole piece and coil to the other end along length direction gradually, like this, because the height of arch in the one end of pole piece is greater than the height at the pole piece other end, the initial coiling clearance of the inner circle of the electric core that consequently forms is bigger, nevertheless along with going on of coiling, under the effect of continuous tension, pole piece and diaphragm can constantly tighten up, consequently, when final coiling was accomplished, the clearance of electric core inner circle can be compared in initial coiling clearance and reduce. Therefore, the gap of the inner ring and the gap of the outer ring of the finally wound battery cell tend to be consistent, so that the problems of expansion lithium precipitation, poor infiltration, black spots on the section and the like caused by overlarge or undersize gaps can be effectively avoided, and the cycle performance of the battery is ensured.
The diaphragm and the pole piece disclosed by the embodiment of the application can be used for an electric device using a battery as a power supply or various energy storage systems using the battery as an energy storage element. The powered device may be, but is not limited to, a cell phone, tablet, laptop, electronic toy, electric tool, battery car, electric car, ship, spacecraft, and the like. The electric toy may include a stationary or mobile electric toy, such as a game machine, an electric car toy, an electric ship toy, an electric airplane toy, and the like, and the spacecraft may include an airplane, a rocket, a space shuttle, a spacecraft, and the like.
For example, when the electric device is a vehicle, the vehicle may be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile may be a pure electric automobile, a hybrid electric automobile, or an extended range automobile, etc. The interior of the vehicle is provided with a battery, which may be provided at the bottom or at the head or tail of the vehicle. The battery may be used for power supply of the vehicle, for example, the battery may serve as an operation power source of the vehicle. The vehicle may also include a controller and a motor, the controller being used to control the battery to power the motor, for example, for start-up, navigation, and operational power requirements while traveling of the vehicle.
In some embodiments of the present application, the battery may not only serve as an operating power source for the vehicle, but also as a driving power source for the vehicle, instead of or in part instead of fuel or natural gas, to provide driving power for the vehicle.
In this application, a battery refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in the present application may include a battery module or a battery pack, etc. Some batteries may include a case for enclosing one or more battery cells or a plurality of battery modules. The box can avoid liquid or other foreign matters to influence the charging or discharging of battery monomer. Of course, some batteries may not include the case and may be disposed directly in the battery compartment of the powered device.
Referring to fig. 1, fig. 1 is an exploded view of a battery 100 according to some embodiments of the present application. As shown in fig. 1, the battery 100 of the present embodiment may include a casing, a battery cell 30, and an electrolyte, where the casing is configured to accommodate the battery cell 30 and the electrolyte.
The housing comprises a shell 10 and two end covers 20, wherein the shell 10 is in a cylindrical shape with two open ends, and the two end covers 20 cover the two open ends of the shell 10. The housing 10 and the end cap 20 may be separate components, and an opening may be provided in the housing 10 to form the internal environment of the battery 100 by covering the opening with the end cap 20. Without limitation, the end cap 20 and the housing 10 may be integrated, and specifically, the end cap 20 and the housing 10 may form a common connecting surface before other components are inserted into the housing, and when it is required to enclose the inside of the housing 10, the end cap 20 covers the housing 10. The housing 10 may be of various shapes and sizes, such as cylindrical, hexagonal, etc. Specifically, the shape of the casing 10 may be determined according to the specific shape and size of the battery cell 30. The material of the housing 10 may be various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which is not limited in this embodiment.
The end cap 20 refers to a member that covers an opening of the case 10 to insulate the internal environment of the battery 100 from the external environment. Without limitation, the shape of the end cap 20 may be adapted to the shape of the housing 10 to fit the housing 10. Alternatively, the end cap 20 may be made of a material (e.g., aluminum alloy) having certain hardness and strength, so that the end cap 20 is not easily deformed when being impacted, and thus the battery 100 may have higher structural strength and improved safety. The material of the end cap 20 may be various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which is not limited in the embodiments of the present invention. In some embodiments, insulation may also be provided on the inside of the end cap 20, which may be used to isolate the electrical connections within the housing 10 from the end cap 20 to reduce the risk of shorting. Illustratively, the insulator may be plastic, rubber, or the like.
The casing of the battery 100 may be provided with a terminal, etc. connected to the tab, as an electrical connection portion of the battery 100, for outputting or inputting electrical energy of the battery 100. Further, the case of the battery 100 may be provided with a pressure release mechanism for releasing the internal pressure when the internal pressure or temperature of the battery 100 reaches a threshold value. When the internal pressure of the battery monomer is too large (for example, thermal runaway), the pressure relief part is used for releasing substances (for example, gas, liquid, particulate matters and the like) in the battery monomer so as to reduce the internal pressure of the battery monomer and avoid dangerous accidents such as explosion of the battery monomer caused by the too fast pressurization in the battery monomer. For example, the relief portion may be an explosion-proof valve, an explosion-proof plate, or the like.
The battery cell 30 is composed of a positive electrode plate 32, a negative electrode plate 32 and a diaphragm 31. The battery operates primarily by virtue of metal ions moving between the positive and negative pole pieces 32, 32. The positive pole piece 32 comprises a positive pole current collector and a positive pole active substance layer, wherein the positive pole active substance layer is coated on the surface of the positive pole current collector, the positive pole current collector which is not coated with the positive pole active substance layer protrudes out of the positive pole current collector which is coated with the positive pole active substance layer, and the positive pole current collector which is not coated with the positive pole active substance layer is used as a positive pole lug. Taking a lithium ion battery as an example, the material of the positive electrode current collector may be aluminum, and the positive electrode active material may be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate, or the like.
The negative pole piece 32 includes negative pole mass flow body and negative pole active substance layer, and the surface of negative pole mass flow body is scribbled to the negative pole active substance layer, and the negative pole mass flow body protrusion in the negative pole mass flow body of having scribbled the negative pole active substance layer of not scribbling the negative pole active substance layer, and the negative pole mass flow body of not scribbling the negative pole active substance layer is as negative pole utmost point ear. The material of the negative electrode collector may be copper, and the negative electrode active material may be carbon, silicon, or the like. In order to ensure that the fuse is not fused when a large current is passed, the number of the positive electrode tabs is multiple and the positive electrode tabs are stacked together, and the number of the negative electrode tabs is multiple and the negative electrode tabs are stacked together.
The material of the diaphragm 31 may be PP (polypropylene) or PE (polyethylene). The battery core 30 of the embodiment of the present application is of a winding structure.
A separator 31 according to an embodiment of the first aspect of the present application will be described below with reference to fig. 2, where the separator 31 of this embodiment is applied to a wound battery cell 30, and the separator 31 is sandwiched between a positive electrode sheet 32 and a negative electrode sheet 32 of the wound battery cell 30.
As shown in fig. 2, the diaphragm 31 has a first end 31a and a second end 31b opposite in the longitudinal direction of the diaphragm 31, and the thickness of the diaphragm 31 decreases in a direction from the first end 31a toward the second end 31b (e.g., in a left-to-right direction shown in fig. 2).
The length direction of the separator 31 is the winding direction of the battery cell 30 of the battery 100, that is, when the pole piece 32 and the separator 31 are wound, the winding is started from the first end 31a along the length direction of the separator 31 and is gradually wound to the second end 31b. After the winding, the first end 31a of the separator 31 is the inner end of the separator 31, and the second end 31b of the separator 31 is the outer end of the separator 31. Here, the inner and outer sides are the ends of the battery 100 formed by winding, the ends located radially inward being the inner ends, and the ends located radially outward being the outer ends.
The reduced thickness of the septum 31 may cause the thickness of the septum 31 at the first end 31a to be greater than the thickness of the septum 31 at the second end 31b. With respect to the adjacent two-part diaphragms 31, the thickness of the first part of the diaphragm 31 toward the first end 31a of the diaphragm 31 is greater than the thickness of the second part of the diaphragm 31 toward the second end 31b of the diaphragm 31 in the longitudinal direction of the diaphragm 31. For example, the thickness of the diaphragm 31 may gradually decrease in a direction from the first end 31a toward the second end 31b. As another example, the thickness of the diaphragm 31 decreases stepwise in a direction from the first end 31a toward the second end 31b.
When the separator 31 of the present embodiment is applied to a winding-type battery cell 30, when the pole piece 32 and the separator 31 in the battery cell 30 are wound, the stacked pole piece 32 and separator 31 may be gradually wound from the first end 31a to the second end 31b of the separator 31 along the length direction, so that the initial winding gap of the inner ring of the battery cell 30 is larger because the thickness of the separator 31 at the first end 31a is larger than that at the second end 31b, but as the winding continues, the pole piece 32 and the separator 31 are continuously tightened under the action of continuous tension, and therefore, when the final winding is completed, the gap of the inner ring of the battery cell 30 is smaller than the initial winding gap. Therefore, the gap of the inner ring of the finally wound battery cell 30 and the gap of the outer ring tend to be consistent, so that the problems of expansion lithium precipitation and poor infiltration caused by the excessively small gap of the inner ring of the battery cell 30 can be effectively avoided, the phenomenon that the pole piece 32 bears large extrusion force caused by the excessively small gap when the pole piece 32 expands can also be avoided, and the risk of short circuit in the battery caused by the breakage of the pole piece 32 is avoided; the problems of poor infiltration, interface black spots and the like caused by overlarge outer ring clearance of the battery core 30 can be avoided, and the cycle performance of the battery is ensured.
According to the separator 31 of the embodiment of the application, the thickness of the separator 31 from the first end 31a to the second end 31b is reduced, so that the gap of the inner ring of the battery cell 30 and the gap of the outer ring tend to be consistent, the problems of expansion lithium precipitation, poor infiltration, interface black spots and the like caused by overlarge or undersize gaps are avoided, and the risk of short circuit in the battery caused by fracture of the pole piece 32 due to large extrusion force can be avoided, so that the cycle performance of the battery is ensured.
In addition, when the diaphragm is applied to a battery, the consistency of the gaps between the inner ring and the outer ring can be effectively improved on the basis that the structure of the embossing roller of the pole piece is not adjusted.
It should be noted that, when the separator 31 of the present embodiment is applied to the battery core 30 of the battery 100, the separator 31 may form a gap of 1 μm to 100 μm for the wound battery core 30. For example, the gap of the separator 31 for the wound battery cell 30 may be 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, or 90 μm. And, when the protrusions 321 are disposed on the pole piece 32 of the battery cell, the protrusions 321 of the pole piece 32 may form a gap of 1 μm to 50 μm for the battery cell 30 after winding. For example, the gap formed by the protrusion 321 on the pole piece 32 for the wound battery cell 30 may be 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, or 50 μm. In this case, the gap formed between the pole piece 32 having the protrusion 321 and the battery cell 30 formed by the separator 32 of the present embodiment may be 2 μm to 150 μm.
According to some embodiments of the present application, the thickness of the diaphragm 31 may gradually decrease in a direction from the first end 31a toward the second end 31b.
The thickness of the diaphragm 31 may decrease linearly or non-linearly in a direction from the first end 31a to the second end 31b. Therein, it is understood that the decreasing function of the thickness of diaphragm 31 may be determined based on the different tightening forces experienced by pole piece 32 and diaphragm 31 at different locations during winding.
Since the tightening force applied to the pole piece 32 and the separator 31 is different at different positions under the action of continuous tension as the number of winding layers increases during the winding of the pole piece 32 and the separator 31, the tightening force is larger at positions closer to the winding center and smaller at positions farther from the winding center, that is, the tightening force is gradually reduced in the direction from the inside to the outside. Therefore, by gradually decreasing the thickness of the separator 31 from the first end 31a to the second end 31b, the thickness variation of the separator 31 can be made to more match the variation of the tightening force, and further more match the reduction of the gap due to the tightening force, so that the uniformity of the gap at each position of the winding-molded battery cell 30 can be made to be better.
In the present embodiment, by gradually decreasing the thickness of the separator 31 from the first end 31a to the second end 31b, the thickness variation of the separator 31 can be more matched with the variation of the tightening force during winding, so that the gap uniformity of the battery cell 30 at each position is better.
According to some embodiments of the present application, the diaphragm 31 includes a plurality of film segments connected in series in a direction from the first end 31a toward the second end 31b, and in adjacent two film segments, a thickness of the film segment toward the first end 31a is greater than a thickness of the film segment toward the second end 31b.
The diaphragm 31 may comprise two, three, four, five or six and more membrane segments in the direction from the first end 31a towards the second end 31b. In the direction from the first end 31a to the second end 31b, the plurality of film segments are respectively a first film segment, a second film segment, \8230, and an Nth film segment, wherein the thickness of the first film segment is d1, the thickness of the second film segment is d2, the thickness of the Nth film segment is dN, and the thicknesses of the plurality of film segments satisfy the relation: d1 > d2 > d3 > \8230; > dN.
This embodiment is through dividing diaphragm 31 into a plurality of membrane sections along length direction, can conveniently control the thickness of diaphragm 31, simplifies the control procedure of diaphragm 31 thickness, simplifies diaphragm 31 processing, makes things convenient for diaphragm 31's shaping, reduces the technology degree of difficulty and manufacturing cost.
According to some embodiments of the present application, the diaphragm 31 may include: the film body 311 and the coating layer 312 provided on at least one side surface of the film body 311 are such that the thickness of the coating layer 312 decreases in a direction from the first end 31a toward the second end 31b.
The diaphragm 31 may include a film main body 311 and a coating layer 312, the film main body 311 being a sheet-shaped thin film. Alternatively, the thickness of the film main body 311 may be the same at any position in the direction from the first end 31a to the second end 31b.
The coating 312 is provided on the film main body 311, and the coating 312 may be provided on one side surface of the film main body 311 in the thickness direction, or the coating 312 may be provided on both side surfaces of the film main body 311 in the thickness direction. The thickness of the coating 312 may gradually decrease in a direction from the first end 31a to the second end 31b, or the coating 312 may be divided into a plurality of sections along the length of the diaphragm 31, and the thickness of the coating 312 may be uniform in each section, while the thicknesses of the coatings 312 in two adjacent sections are different.
In the present embodiment, the diaphragm 31 includes the film main body 311 and the coating layer 312, and the thickness of the coating layer 312 is reduced from the first end 31a to the second end 31b, so that the thickness of the diaphragm 31 can be controlled by controlling the thickness of the coating layer 312, thereby facilitating the processing and forming of the diaphragm 31 and reducing the production difficulty and the manufacturing cost.
In one embodiment of the present application, the coating 312 may include a high molecular polymer and a binder.
The coating 312 may be composed of at least a high molecular polymer and a binder. The high molecular polymer can make the coating 312 have high modulus and incompressibility, so as to ensure that sufficient gaps exist between the pole pieces 32 of the winding-formed battery cell 30; the adhesive is mainly used for adhering and fixing the coating 312 on the film main body 311, and the coating 312 with the adhesive can increase the frictional resistance between the diaphragm 31 and the pole piece 32, so that the slippage between the pole piece 32 and the diaphragm 31 is reduced, and the gap consistency of the winding-formed battery core 30 is better.
When the coating 312 is disposed on the film main body 311, the high molecular polymer and the binder may be dispersed by a solvent, and then the mixture may be sprayed on the film main body 311, and finally the coating 312 adhered to the surface of the film main body 311 may be obtained by drying.
Alternatively, when the high molecular polymer is dispersed using a solvent, the mass of the solvent may be 5% to 90% of the total mass of the high molecular polymer and the binder. For example, the mass of the solvent may be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50%, 60%, 70%, 80%, 90%, or the like of the total mass of the high molecular polymer and the binder. The mass ratio of the solvent to the high molecular polymer and the binder can be determined according to the type and properties of the high molecular polymer and the binder and the spraying process of the coating 312, so as to improve the spraying efficiency of the coating 312, the forming efficiency of the coating 312 and the quality of the coating 312.
In the embodiment, the coating 312 includes the high molecular polymer and the binder, so that the coating 312 has high modulus and incompressible performance during winding, and thus, the gap of the battery core 30 wound around the inner ring can be effectively increased, the friction resistance between the coating 312 and the pole piece 32 can be increased, and the slippage between the pole piece 32 and the diaphragm 31 can be reduced, so that the gap consistency between the inner ring and the outer ring of the battery core 30 is better, and the cycle performance of the battery 100 is improved.
In one example of the present application, the high molecular polymer may include at least one of polyvinylidene fluoride, polyvinyl alcohol, polymethacrylic acid, polyvinylsulfonate, and polyethylene glycol; and/or the binder is at least one of styrene-butadiene rubber, sodium alginate, styrene-acrylic latex and polyacrylic acid.
Specifically, the high molecular polymer may include one of polyvinylidene fluoride, polyvinyl alcohol, polymethacrylic acid, polyvinyl sulfonate and polyethylene glycol, and the high molecular polymer may also include any two, three or more of polyvinylidene fluoride, polyvinyl alcohol, polymethacrylic acid, polyvinyl sulfonate and polyethylene glycol. The composition of the high molecular weight polymer may be selected based on the modulus requirements and compressibility requirements for the coating 312.
The adhesive can be one of styrene butadiene rubber, sodium alginate, styrene-acrylic latex and polyacrylic acid, the adhesive can also comprise any two or three of styrene butadiene rubber, sodium alginate, styrene-acrylic latex and polyacrylic acid, and the adhesive can also comprise styrene butadiene rubber, sodium alginate, styrene-acrylic latex and polyacrylic acid. The matching binder may be selected based on the adhesion performance requirements for the coating 312 and the characteristics of the high molecular weight polymer.
In this embodiment, the high molecular polymer is limited to include at least one of polyvinylidene fluoride, polyvinyl alcohol, polymethacrylic acid, polyvinyl sulfonate and polyethylene glycol, and the binder is at least one of styrene-butadiene rubber, sodium alginate, styrene-acrylic latex and polyacrylic acid, so that the high molecular polymer and the binder can be selected according to design requirements, and the cost is reduced.
In one embodiment of the present application, the average thickness of the coating 312 on the surface of the film body 311 may be 1 μm to 30 μm.
I.e., the average sprayed thickness of the coating 312 may be in the range of 1 μm to 30 μm, with the thickness of the coating 312 at the first end 31a being greater than the thickness of the coating 312 at the second end 31b. For example, the thickness of the coating 312 can be 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, 11 μm, 13 μm, 15 μm, 17 μm, 19 μm, 21 μm, 23 μm, 25 μm, 27 μm, 29 μm, 30 μm, or the like. Alternatively, the thickness of the coating 312 at the first end 31a may be 10 μm to 30 μm, and the thickness of the coating 312 at the second end 31b may be 1 μm to 20 μm.
In the embodiment, the average thickness of the coating 312 is 1 μm to 30 μm, so that the gap between the inner ring and the outer ring of the battery cell 30 is more consistent, and the cycle performance of the battery 100 is improved.
In one embodiment of the present application, the average distribution mass of the coating 312 on the surface of the film body 311 may be 0.1g/m 2 -2g/m 2 。
For example, the average distributed mass per unit area of the coating 312May be 0.1g/m 2 、0.2g/m 2 、0.3g/m 2 、0.4g/m 2 、0.5g/m 2 、0.6g/m 2 、0.7g/m 2 、0.8g/m 2 、0.9g/m 2 、1g/m 2 、1.1g/m 2 、1.2g/m 2 、1.41g/m 2 、1.6g/m 2 、1.8g/m 2 Or 2g/m 2 。
Since the thickness dimension of the coating 312 is small, the spraying thickness of the coating 312 is controlled by directly measuring the thickness of the coating 312, the operability is poor, and the processing efficiency is low.
The embodiment can control the spraying thickness of the coating 312 by controlling the spraying weight of the coating 312 by limiting the mass of the coating 312 in a unit area, is convenient to operate, and can improve the spraying efficiency of the coating 312 on the premise of ensuring the spraying thickness of the coating 312.
In one embodiment of the present application, the mass per unit area of the coating 312 at the first end 31a is greater than the mass per unit area of the coating 312 at the second end 31b.
The mass per unit area of the coating 312 is a at the location of the first end 31a of the diaphragm 31, the mass of the large inner face of the coating 312 is B at the location of the second end 31B of the diaphragm 31, and a and B satisfy: a is greater than B. Alternatively, the mass A of the coating 312 per unit area of the first end 31a may be 0.8g/m 2 -2g/m 2 The mass B of the coating 312 per unit area of the second end 31B may be 0.1g/m 2 -1.2g/m 2 And A > B.
In this embodiment, the mass per unit area of the coating 312 at the first end 31a is greater than the mass per unit area of the coating 312 at the second end 31b, so that the thickness of the coating 312 at the first end 31a is greater than the thickness of the coating 312 at the second end 31b, thereby improving the uniformity of the gap between the inner ring and the outer ring of the battery cell 30, and the mass per unit area of the coating 312 is controlled to control the thickness of the coating 312, thereby improving the spraying efficiency of the coating 312 and simplifying the control flow of the spraying of the coating 312.
In one embodiment of the present application, the coating 312 is applied per unit area in a direction from the first end 31a toward the second end 31bThe mass is gradually reduced, and the mass reduction gradient of the coating 312 is less than or equal to 10g/m 3 。
The sprayed amount of the coating 312 per unit area may decrease linearly or non-linearly in a direction from the first end 31a to the second end 31b. It is to be understood, among other things, that a decreasing function of the sprayed amount of coating 312 per unit area may be determined based on the different tightening forces experienced by pole piece 32 and diaphragm 31 at different locations during winding. Through making the spraying volume of coating 312 in the unit area reduce from first end 31a to second end 31b gradually, can make the thickness change of coating 312 match the change of tightening force more, and then match the clearance more and because of the decrement that the tightening force arouses to can make the electric core 30 of winding formation better in the uniformity in the clearance of each position.
The mass reduction gradient of the coating 312 is: the spray mass per unit area of the coating 312 decreases per unit length in a direction from the first end 31a to the second end 31b. For example, the coating 312 may have a mass decreasing gradient of 9g/m in a direction from the first end 31a toward the second end 31b 3 、8g/m 3 、7g/m 3 、6g/m 3 、5g/m 3 、4g/m 3 、3g/m 3 、2g/m 3 、1g/m 3 、0.8g/m 3 、0.7g/m 3 、0.6g/m 3 、0.5g/m 3 、0.4g/m 3 、0.3g/m 3 、0.2g/m 3 Or 0.1g/m 3 . The gradient of mass reduction of the coating 312 can be controlled according to the degree of change in the tightening force, so that the gap of the wound battery cell 30 is more consistent at each position.
In the present embodiment, the spraying quality per unit area of the coating 312 in the direction from the first end 31a to the second end 31b is gradually reduced, and the gradient of the mass reduction of the coating 312 is set to 9g/m or less 3 The thickness change of the coating 312 can be more matched with the change of the tightening force, and the consistency of the gap between the inner ring and the outer ring of the battery cell 30 is improved.
In one example of the present application, the total area of the coating 312 may be 10% -90% of the total area of the film body 311.
I.e. the coating 312 may cover 10-90% of the area of the membrane body 311. For example, the total sprayed area of the coating 312 can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the total area of the film body 311.
The larger the spraying area of the coating 312 is, the more the friction force between the diaphragm 31 and the pole piece 32 can be further increased, the slippage between the diaphragm 31 and the pole piece 32 during winding is reduced or prevented, the consistency of the gaps between the inner ring and the outer ring of the battery cell 30 is further improved, the consistency of the gaps at different axial positions of the motor assembly is also ensured, and the cycle performance and the service life of the battery 100 are improved.
When the spraying area of the coating 312 is smaller, the using amount of the coating 312 can be reduced, the cost is reduced, the spraying time is shortened, and the processing efficiency is improved.
In this embodiment, the total area of the coating 312 accounts for 10% to 90% of the total area of the film main body 311, so that the weight and the cost can be reduced and the processing efficiency can be improved on the premise of improving the gap consistency between the inner ring and the outer ring of the battery cell 30 and the gap consistency at different axial positions.
A pole piece 32 according to an embodiment of the second aspect of the present application is described below with reference to fig. 3, where the pole piece 32 of this embodiment is applied to a winding type battery cell 30.
As shown in fig. 3, a plurality of projections 321 are formed on the surface of the pole piece 32, and the height of the projections 321 decreases in a direction from one end of the pole piece 32 in the longitudinal direction toward the other end (for example, a direction from left to right as shown in fig. 3).
The length direction of the pole piece 32 is the winding direction of the battery core 30 of the battery 100, that is, when the pole piece 32 and the diaphragm 31 are wound, the winding is started from one end along the length direction of the pole piece 32 and is gradually wound to the other end of the pole piece 32. After winding, one end of the pole piece 32 is the inner end of the pole piece 32, and the other end of the pole piece 32 is the outer end of the pole piece 32. Here, the inner and outer sides are the ends of the battery 100 formed by winding, the ends located radially inward being the inner ends, and the ends located radially outward being the outer ends.
The protrusions 321 are formed on at least one side surface of the pole piece 32 in the thickness direction, and the protrusions 321 are arranged on the pole piece 32, so that the rigidity of the pole piece 32 can be increased, the pole piece 32 is not prone to wrinkle, the soaking effect of electrolyte on the pole piece 32 is ensured, and the cycle performance of the battery 100 is improved.
The height of the projection 321 decreases in a direction from one end of the pole piece 32 toward the other end. Wherein the height of the protrusion 321 is reduced such that the height of the protrusion 321 at one end of the pole piece 32 is greater than the height of the protrusion 321 at the other end of the pole piece 32. For two adjacent portions of the pole piece 32, the height of the protrusion 321 on the first portion of the pole piece 32 towards one end of the pole piece 32 is greater than the height of the protrusion 321 on the second portion of the pole piece 32 towards the other end of the pole piece 32 in the length direction of the pole piece 32. For example, the height of the projection 321 may gradually decrease in a direction from one end toward the other end of the pole piece 32. As another example, the height of the protrusion 321 may decrease in a stepwise manner in a direction from one end of the pole piece 32 toward the other end.
When the pole piece 32 of the present embodiment is applied to the winding-type battery cell 30, when the pole piece 32 and the diaphragm 31 in the battery cell 30 are wound, the stacked pole piece 32 and the diaphragm 31 may be gradually wound from one end of the pole piece 32 to the other end along the length direction, so that, since the height of the protrusion 321 at one end of the pole piece 32 is greater than the height of the protrusion 321 at the other end of the pole piece 32, the initial winding gap of the inner ring of the battery cell 30 formed is larger, but as the winding continues, the pole piece 32 and the diaphragm 31 are continuously tightened under the action of continuous tension, and therefore, when the final winding is completed, the gap of the inner ring of the battery cell 30 is reduced compared with the initial winding gap. Therefore, the gap of the inner ring of the finally wound battery cell 30 and the gap of the outer ring tend to be consistent, so that the problems of expansion lithium precipitation and poor infiltration caused by the excessively small gap of the inner ring of the battery cell 30 can be effectively avoided, the phenomenon that the pole piece 32 bears large extrusion force caused by the excessively small gap when the pole piece 32 expands can also be avoided, and the risk of short circuit in the battery caused by the breakage of the pole piece 32 is avoided; the problems of poor infiltration, interface black spots and the like caused by overlarge outer ring clearance of the battery core 30 can be avoided, and the cycle performance of the battery is ensured.
According to the pole piece 32 of the embodiment of the application, the height of the protrusion 321 on the pole piece 32 is reduced from one end to the other end in the length direction, so that the gap of the inner ring of the battery cell 30 and the gap of the outer ring tend to be consistent, the problems of expansion lithium precipitation, poor infiltration, interface black spots and the like caused by overlarge or undersize gaps are avoided, the risk of short circuit in the battery caused by fracture of the pole piece 32 due to large extrusion force can be avoided, and the cycle performance of the battery is ensured.
According to some embodiments of the present application, the height of the protrusion 321 gradually decreases in a direction from one end of the pole piece 32 in the length direction toward the other end.
The height of the protrusion 321 may decrease linearly or non-linearly in a direction from one end to the other end of the pole piece 32 in the length direction. It will be appreciated, among other things, that the decreasing function of the height of projection 321 may be determined by the different tightening forces to which pole piece 32 and diaphragm 31 are subjected at different locations during winding.
Since the tightening force applied to the pole piece 32 and the separator 31 is different at different positions under the action of continuous tension as the number of winding layers increases during the winding of the pole piece 32 and the separator 31, the tightening force is larger at positions closer to the winding center and smaller at positions farther from the winding center, that is, the tightening force is gradually reduced in the direction from the inside to the outside. Therefore, by gradually reducing the height of the protrusion 321 on the pole piece 32 from one end to the other end of the pole piece 32, the height change of the protrusion 321 can be more matched with the change of the tightening force, and further the reduction of the gap caused by the tightening force can be more matched, so that the consistency of the gap of the winding-formed battery cell 30 at each position can be better.
In this embodiment, the height of the protrusion 321 is gradually reduced from one end of the pole piece 32 to the other end, so that the height change of the protrusion 321 can be more matched with the change of the tightening force during winding, and the consistency of the gap of the battery cell 30 at each position is better.
According to some embodiments of the present application, the pole piece 32 comprises a plurality of pole piece 32 segments connected in series in a direction from one end toward the other end, and in two adjacent pole piece 32 segments, the height of the protrusion 321 of the pole piece 32 segment toward one end is greater than the height of the protrusion 321 on the pole piece 32 segment toward the other end.
The pole piece 32 may include two, three, four, five or six and more sub-segments in the direction from one end of the pole piece 32 toward the other end. In the direction from one end of the pole piece 32 to the other end, the plurality of subsections are respectively a first subsection, a second subsection, \ 8230and an Nth subsection, wherein the height of the protrusion 321 on the first subsection is h1, the height of the protrusion 321 on the second subsection is h2, the height of the protrusion 321 on the Nth subsection is hN, and the heights of the protrusions 321 on the plurality of subsections satisfy the relation: h1 & gt h2 & gt h3 & gt 8230; > hN.
In the embodiment, the pole piece 32 is divided into a plurality of subsections along the length direction, so that the height of the protrusion 321 on the pole piece 32 can be conveniently controlled in a segmented manner, the processing of the protrusion 321 is simplified, and the process difficulty and the production cost are reduced.
According to some embodiments of the present application, the height of the protrusions 321 is less than or equal to 5mm, and/or the maximum dimension of the protrusions 321 on the surface of the pole piece 32 is less than or equal to 10mm, and/or the density of the protrusions 321 is less than or equal to 100ea/cm 2 。
For example, the height of the projection 321 may be 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, or 5mm. Wherein, the height of the protrusion 321 at one end of the pole piece 32 is greater than the height of the protrusion 321 at the other end of the pole piece 32. For example, the height of the projection 321 at one end of the pole piece 32 may be 2mm to 5mm; the height of the projection 321 at the other end of the pole piece 32 is not more than 3mm.
The cross-sectional shape of the protrusion 321 may be circular, elliptical, or rectangular. Of course, the cross-sectional shape of the protrusion 321 may be other regular or irregular polygonal shapes. For example, the cross-sectional shape of the protrusion 321 may be circular, and the diameter of the protrusion 321 is 10mm or less. Specifically, the diameter of the protrusion 321 may be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm.
On the surface of the pole piece 32, the density of the arranged projections 321 is not more than 100ea/cm 2 . That is, the number of the protrusions 321 is 100 or less per square centimeter. For example, the density of protrusions 321 may be 1ea/cm 2 、3ea/cm 2 、5ea/cm 2 、7ea/cm 2 、9ea/cm 2 、12ea/cm 2 、15ea/cm 2 、20ea/cm 2 、30ea/cm 2 、40ea/cm 2 、50ea/cm 2 、70ea/cm 2 、90ea/cm 2 Or 95ea/cm 2 。
In the embodiment, the height of the protrusions 321 is not more than 5mm, the maximum width of the protrusions 321 on the surface of the pole piece 32 is not more than 10mm, and the density of the protrusions 321 is not more than 100ea/cm 2 The structure of the projection 321 can be optimized on the premise of improving the rigidity of the pole piece 32 and avoiding the wrinkles of the pole piece 32, and the processing and the manufacturing are convenient.
According to some embodiments of the present application, the areal density of the protrusions 321 may be 10g/m or less 2 。
For example, the areal density of the protrusions 321 may be 1g/m 2 、2g/m 2 、3g/m 2 、4g/m 2 、5g/m 2 、6g/m 2 、7g/m 2 、8g/m 2 Or 9g/m 2 。
The present embodiment is achieved by making the areal density of the projections 321 not more than 10g/m 2 The rigidity of the pole piece 32 can be ensured, the structure of the protrusion 321 is optimized, and the processing and the manufacturing of the pole piece 32 are facilitated.
A wound cell 30 according to an embodiment of the third aspect of the present application is described below with reference to fig. 1.
The wound battery cell 30 according to the embodiment of the present application includes a pole piece 32 and a separator 31, where the pole piece 32 includes a positive pole piece 32 and a negative pole piece 32, and the separator 31 is disposed between the positive pole piece 32 and the negative pole piece 32, where the separator 31 is the separator 31 according to the first aspect of the present application, and/or at least one of the positive pole piece 32 and the negative pole piece 32 is the pole piece 32 according to the second aspect of the present application.
The wound electrical core 30 of the present embodiment includes a pole piece 32 and the separator 31 of the first aspect of the present application, or the wound electrical core 30 of the present embodiment includes the separator 31 and the pole piece 32 of the second aspect of the present application, or the wound electrical core 30 of the present embodiment includes the pole piece 32 of the first aspect of the present application and the pole piece 32 of the second aspect of the present application.
The pole piece 32 includes a positive pole piece 32 and a negative pole piece 32, and only the positive pole piece 32 may be the pole piece 32 of the second aspect embodiment, only the negative pole piece 32 may be the pole piece 32 of the second aspect embodiment, or both the positive pole piece 32 and the negative pole piece 32 may be the pole pieces 32 of the second aspect embodiment.
According to the winding-type battery cell 30 of the embodiment of the application, by arranging the diaphragm 31 of the embodiment of the first aspect and/or arranging the pole piece 32 of the embodiment of the second aspect, the gap of the inner ring of the battery cell 30 and the gap of the outer ring tend to be consistent, the problems of expansion lithium precipitation and poor infiltration caused by the excessively small gap of the inner ring of the battery cell 30 are effectively avoided, the pole piece 32 bears larger extrusion force caused by the excessively small gap when the pole piece 32 expands, and the risk of short circuit in the battery caused by the breakage of the pole piece 32 is avoided; the problems of poor infiltration, interface black spots and the like caused by overlarge outer ring clearance of the battery core 30 can be avoided, the cycle performance of the battery is ensured, the safety performance of the battery is improved, and the service life of the battery is prolonged.
The battery 100 according to the fourth aspect of the present application includes the winding type battery cell 30 according to the above third aspect of the present application.
According to the battery 100 of the embodiment of the present application, by providing the winding type battery cell 30 of the above embodiment, the overall performance of the battery can be improved.
The electric device according to the fifth aspect of the present application includes the battery 100 according to the fourth aspect of the present application, and the battery 100 is used for supplying electric energy.
The powered device may be any of the aforementioned devices or systems that employ battery 100.
According to the power consumption device of the embodiment of the application, the overall performance of the power consumption device can be improved by arranging the battery of the embodiment.
A battery 100 according to two specific embodiments of the present application will be described below with reference to fig. 1 to 4. Referring to fig. 1, the battery 100 includes a casing 10, an end cap 20, and a battery cell 30, where the battery cell 30 is disposed in a receiving cavity formed by the casing 10 and the end cap 20. The battery cell 30 is a winding battery cell, and the battery cell 30 includes a positive electrode tab 32, a negative electrode tab 32, and a separator 31.
In the first embodiment of the present invention, the first,
referring to fig. 3, a protrusion 321 is formed on the negative electrode tab 32, and the protrusion 321 is formed by windingThe embossing roller is processed by a single-sided embossing roller, the height of the bulges 321 is 1mm, the diameter of the bulges 321 is 1mm, and the density of the bulges 321 is 3ea/cm 2 。
Referring to fig. 2, the diaphragm 31 includes a film body 311 and a coating layer 312, the coating layer 312 is provided on one side surface of the film body 311, and the mass of the coating layer 312 per unit area is gradually decreased from the first end 31a to the second end 31b of the diaphragm 31. The coating 312 is made of polyvinylidene fluoride and styrene-butadiene rubber, and the coating 312 is sprayed at the first end 31a of the diaphragm 31 to a weight of 1.0g/m 2 The coating 312 has a spray weight per unit area of 0.1g/m at the second end 31b of the diaphragm 31 2 . The length of the single-layer diaphragm 31 is 5m, and the coating weight of the coating 312 per unit area is 0.18g/m from the first end 31a to the second end 31b 3 The gradient decreases.
According to the battery 100 of the embodiment of the application, as shown in fig. 4, the gaps of the battery core 30 at each turn position are distributed in the range of 15 μm to 23 μm, and the consistency is good. The battery 100 provided by the embodiment of the application can improve the problem of inconsistent gaps between the inner ring and the outer ring of the battery cell by introducing the gradient diaphragm glue coating layer under the condition that an additional assembling process is not added, solves the problems of lithium precipitation and interface black spot caused by cyclic expansion of the battery cell, and effectively improves the service life and the safety performance of the battery cell.
In the second embodiment, the first embodiment of the method,
referring to fig. 3, the negative electrode tab 32 is formed with protrusions 321, the protrusions 321 are formed by winding a single-sided embossing roller, the height of the protrusions 321 is 1mm, the diameter of the protrusions 321 is 2mm, and the density of the protrusions 321 is 2.5ea/cm 2 。
As shown in FIG. 5, the diaphragm 31 includes a film body 311 and a coating 312, the coating 312 is disposed on both side surfaces of the film body 311, the coating 312 is composed of polyvinylidene fluoride and styrene-butadiene rubber, and the coating 312 is sprayed at a first end 31a of the diaphragm 31 with a weight of 1.2g/m 2 The coating 312 has a spray weight per unit area of 0.2g/m at the second end 31b of the diaphragm 31 2 The length of the single-layer diaphragm 31 is 5m, and the coating weight of the coating 312 per unit area is 0.2g/m from the first end 31a to the second end 31b 3 The gradient decreases.
According to the battery 100 of the embodiment of the application, as shown in fig. 4, the gaps of the battery cells 30 at each turn position are distributed between 18 μm and 24 μm, and the consistency is good.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present disclosure, and the present disclosure should be construed as being covered by the claims and the specification. In particular, the technical features mentioned in the embodiments can be combined in any way as long as there is no structural conflict. The present application is not intended to be limited to the particular embodiments disclosed herein but is to cover all embodiments that may fall within the scope of the appended claims.

Claims (18)

1. A separator (31), characterized in that the separator (31) is applied to a wound cell (30), the separator (31) having a first end (31 a) and a second end (31 b) opposite in the length direction, the thickness of the separator (31) decreasing in the direction from the first end (31 a) towards the second end (31 b).
2. A membrane (31) according to claim 1, wherein the membrane (31) has a thickness that gradually decreases in a direction from the first end (31 a) towards the second end (31 b).
3. Diaphragm (31) according to claim 1, characterised in that said diaphragm (31) comprises a plurality of membrane segments connected in series in a direction from said first end (31 a) towards said second end (31 b), the thickness of said membrane segment towards said first end (31 a) being greater than the thickness of said membrane segment towards said second end (31 b) in two adjacent said membrane segments.
4. A membrane (31) according to any one of claims 1-3, wherein the membrane (31) comprises: a film body (311) and a coating layer (312) provided on at least one side surface of the film body (311), the coating layer (312) decreasing in thickness in a direction from the first end (31 a) toward the second end (31 b).
5. A membrane (31) according to claim 4, wherein the coating (312) comprises a high molecular polymer and a binder.
6. The membrane (31) of claim 5, wherein the high molecular polymer comprises at least one of polyvinylidene fluoride, polyvinyl alcohol, polymethacrylic acid, polyvinyl sulfonate, and polyethylene glycol; and/or
The binder is at least one of styrene butadiene rubber, sodium alginate, styrene-acrylic latex and polyacrylic acid.
7. A membrane (31) according to claim 4, wherein the average thickness of the coating (312) on the surface of the membrane body (311) is 1 μm-30 μm.
8. Membrane (31) according to claim 4, wherein the average distributed mass of the coating (312) on the surface of the membrane body (311) is 0.1g/m 2 -2g/m 2 。
9. A membrane (31) according to claim 4, wherein the mass per unit area of the coating (312) at the first end (31 a) is greater than the mass per unit area of the coating (312) at the second end (31 b).
10. A diaphragm (31) according to claim 9, wherein the mass of the coating (312) per unit area decreases gradually in a direction from the first end (31 a) toward the second end (31 b), and the gradient of the decrease in the mass of the coating (312) is 10g/m or less 3 。
11. A membrane (31) according to claim 4, wherein the total area of the coating (312) is 10-90% of the total area of the membrane body (311).
12. A pole piece (32), characterized in that the pole piece (32) employs a wound electrical core (30), the surface of the pole piece (32) is formed with a plurality of protrusions (321), the height of the protrusions (321) decreases in a direction from one end of the pole piece (32) in the length direction towards the other end.
13. The pole piece (32) of claim 12, wherein the height of the projections (321) gradually decreases in a direction from one end of the pole piece (32) in the length direction toward the other end.
14. The pole piece (32) according to claim 12, characterized in that the pole piece (32) comprises a plurality of subsections connected in sequence in a direction from the one end towards the other end, wherein in two adjacent subsections the height of the projection (321) of the subsection towards the one end is larger than the height of the projection (321) on the subsection towards the other end.
15. Pole piece (32) according to one of the claims 12 to 14, characterized in that the height of the projections (321) is equal to or less than 5mm and/or the maximum dimension of the projections (321) on the surface of the pole piece (32) is equal to or less than 10mm and/or the density of the projections (321) is equal to or less than 100ea/cm 2 。
16. A wound electrical core (30) comprising a pole piece (32) and a separator (31), wherein the pole piece (32) comprises a positive pole piece (32) and a negative pole piece (32), and the separator (31) is disposed between the positive pole piece (32) and the negative pole piece (32), wherein the separator (31) is the separator (31) according to any one of claims 1 to 11, and/or wherein at least one of the positive pole piece (32) and the negative pole piece (32) is the pole piece (32) according to any one of claims 12 to 15.
17. A battery (100) characterized by comprising a wound cell (30) according to claim 16.
18. An electric consumer, characterized in that it comprises a battery (100) according to claim 17, said battery (100) being intended to provide electric energy.
CN202211321119.XA 2022-10-26 2022-10-26 Diaphragm, pole piece, winding type battery cell, battery and power utilization device Pending CN115842215A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015181112A (en) * 2015-04-21 2015-10-15 トヨタ自動車株式会社 Secondary battery, manufacturing method thereof, and method for manufacturing negative electrode sheet used for secondary battery
CN112688029A (en) * 2021-03-15 2021-04-20 江苏厚生新能源科技有限公司 Lithium ion battery multilayer composite diaphragm and preparation method thereof
CN112768623A (en) * 2020-12-31 2021-05-07 Oppo广东移动通信有限公司 Battery and electric core thereof
CN216413207U (en) * 2021-11-04 2022-04-29 宁德时代新能源科技股份有限公司 Diaphragm, electric core assembly, battery monomer, battery and power consumption device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015181112A (en) * 2015-04-21 2015-10-15 トヨタ自動車株式会社 Secondary battery, manufacturing method thereof, and method for manufacturing negative electrode sheet used for secondary battery
CN112768623A (en) * 2020-12-31 2021-05-07 Oppo广东移动通信有限公司 Battery and electric core thereof
CN112688029A (en) * 2021-03-15 2021-04-20 江苏厚生新能源科技有限公司 Lithium ion battery multilayer composite diaphragm and preparation method thereof
CN216413207U (en) * 2021-11-04 2022-04-29 宁德时代新能源科技股份有限公司 Diaphragm, electric core assembly, battery monomer, battery and power consumption device

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