CN221226302U

CN221226302U - Battery cell, electrode assembly, battery, electricity utilization device and energy storage device

Info

Publication number: CN221226302U
Application number: CN202420742416.XU
Authority: CN
Inventors: 王细辉; 许文竹
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2024-04-11
Filing date: 2024-04-11
Publication date: 2024-06-25
Anticipated expiration: 2034-04-11

Abstract

The application discloses a battery monomer, an electrode assembly, a battery, an electricity utilization device and an energy storage device, wherein the battery monomer comprises a shell and a storage space; an electrode assembly disposed in the receiving space, the electrode assembly including: the positive pole piece and the negative pole piece are mutually laminated and wound to form a winding structure, the winding structure comprises a bending area, and a separator is arranged between the positive pole piece and the negative pole piece; the positive pole piece comprises a plurality of positive pole bending parts positioned in the bending area, and the negative pole piece comprises a plurality of negative pole bending parts positioned in the bending area; at least a part of at least one negative electrode bending part is formed into a wavy structure, and the wavy structure is formed by bending a negative electrode plate into a wavy shape. According to the application, the occurrence of lithium precipitation can be reduced, so that the risk of thermal runaway is reduced.

Description

Battery cell, electrode assembly, battery, electricity utilization device and energy storage device

Technical Field

The application relates to the technical field of batteries, in particular to a battery cell, an electrode assembly, a battery, an electric device and an energy storage device.

Background

New energy batteries are increasingly used in life and industry, for example, new energy automobiles having a battery mounted therein have been widely used, and in addition, batteries are increasingly used in the field of energy storage and the like.

In a new energy vehicle that carries a battery, the battery may be used to fully or partially power. In the energy storage field, the battery may be mounted in an energy storage case or directly on the user side. In addition to improving the performance of batteries, the problem of thermal runaway of batteries is also a non-negligible problem in the development of battery technology. Therefore, how to reduce the thermal runaway risk of the battery is a technical problem to be solved in the battery technology.

Disclosure of utility model

In order to solve the technical problems, the application provides a battery cell, an electrode assembly, a battery, an electricity utilization device and an energy storage device, which can reduce the risk of thermal runaway of the battery.

The application is realized by the following technical scheme.

A first aspect of the present application provides a battery cell comprising: a housing having an accommodation space; an electrode assembly in the receiving space, the electrode assembly comprising: the positive pole piece and the negative pole piece are mutually laminated and wound to form a winding structure, the winding structure comprises a bending area, and a separator is arranged between the positive pole piece and the negative pole piece in a clamping way; the positive pole piece comprises a plurality of positive pole bending parts positioned in the bending area, and the negative pole piece comprises a plurality of negative pole bending parts positioned in the bending area; at least a part of at least one of the negative electrode bending parts is formed into a wavy structure, and the wavy structure is formed by bending the negative electrode plate into a wavy shape.

The negative electrode bending part positioned in the bending area is set to be of a wavy structure, so that the surface area of the negative electrode bending part is increased, the surface area of the negative electrode active material layer is increased, and therefore more lithium intercalation sites can be provided for the positive electrode active material of the adjacent positive electrode bending part to be intercalated into the negative electrode active material layer, lithium precipitation is reduced, the thermal runaway risk of the battery is further reduced, and the performance and the cycle life of the battery are improved.

In some embodiments, the undulating structure comprises a plurality of continuous wave segments.

The continuous wave-shaped section further increases the surface area of the anode active material layer of the anode bending part, thereby further reducing occurrence of lithium precipitation and reducing risk of thermal runaway.

In some embodiments, the wave segments have a crest and a trough, in one wave segment, the wave segment comprises a first face and a second face, the first face and the second face being connected at the crest along the winding direction, in a plurality of wave segments, the second face of one wave segment being connected with the first face of an adjacent wave segment at the trough; the first face and the second face extend along the winding axis direction.

The first surface and the second surface of the waveform section extend along the winding shaft direction, and the negative electrode bending part is convenient to process and easy to mold.

In some embodiments, in one of the waveform segments, the shortest distance from the peak portion to the trough portion of the waveform segment is L1, wherein L1 ranges from 0.5um to less than 50um; and/or the shortest distance between the peaks of two adjacent waveform segments is L2, wherein the range of L2 is more than or equal to 0.5mm and less than 500mm.

L1 can increase the surface area of the negative electrode active material layer of the negative electrode bending part in a proper range, and can limit the distance between the negative electrode bending part and the adjacent positive electrode bending part in a proper range, so that the risk that the positive electrode active material of the positive electrode bending part is difficult to be embedded into the negative electrode bending part due to overlarge distance between the trough position of the waveform section and the positive electrode bending part is reduced or avoided, and the occurrence of lithium precipitation is reduced, and the thermal runaway risk of the battery is further reduced.

L2 is in suitable range, can increase the negative electrode active material layer's of negative electrode kink surface area, can make the positive electrode active material of positive electrode kink smoothly imbed in the negative electrode active material layer of negative electrode kink again to reduce and deposit lithium and take place, and then reduce battery thermal runaway risk.

In some embodiments, the relief structure is configured as a continuous sinusoidal waveform, as viewed along the winding axis.

The wave structure is sinusoidal wave, each wave section presents regular structure, machining efficiency is high, and crest portion is the arcwall face, reduces the emergence of puncture separator in winding structure coiling process and the compaction process to reduce battery thermal runaway risk.

In some embodiments, the winding structure includes a flat region, the bending regions are respectively disposed at two ends of the flat region along the winding direction of the winding structure, and the undulating structure is disposed at the negative electrode bending portion of each bending region.

The surface area of the anode active material layer at the anode bending part of each bending region is increased, so that the occurrence of lithium precipitation in each bending region is reduced, the battery is comprehensively protected, and the thermal runaway risk of the battery is reduced.

In some embodiments, among the plurality of anode bending parts, at least the anode bending part at the innermost side is provided with the undulating structure.

The probability of lithium precipitation of the innermost negative electrode bending part is high, and the undulation structure is arranged on the innermost negative electrode bending part, so that the probability of lithium precipitation of the innermost negative electrode bending part position can be reduced, and the thermal runaway risk of the battery is reduced.

A second aspect of the present application provides an electrode assembly comprising: the positive pole piece and the negative pole piece are mutually laminated and wound to form a winding structure, the winding structure comprises a bending area, and a separator is arranged between the positive pole piece and the negative pole piece in a clamping way; the positive pole piece comprises a plurality of positive pole bending parts positioned in the bending area, and the negative pole piece comprises a plurality of negative pole bending parts positioned in the bending area; at least a part of at least one of the negative electrode bending parts is formed into a wavy structure, and the wavy structure is formed by bending the negative electrode plate into a wavy shape.

In some embodiments, the undulating structure is configured as a continuous sinusoidal waveform as viewed along a winding axis of the winding structure.

In some embodiments, the relief structure is provided at least at an innermost one of the plurality of negative electrode bending portions, wherein the innermost one is closer to a winding axis of the winding structure than the outermost one.

A third aspect of the present application provides a battery comprising: at least one battery cell as described in the first aspect.

A fourth aspect of the present application provides an electrical device comprising a battery cell as described in the first aspect or a battery as described in the third aspect, the battery being capable of providing electrical energy to the electrical device.

A fifth aspect of the application provides an energy storage device comprising a battery cell as described in the first aspect or a battery as described in the third aspect, the battery being capable of storing electrical energy and of providing electrical energy.

The utility model has the following effects:

according to the embodiment of the application, occurrence of lithium precipitation can be reduced, so that the risk of thermal runaway is reduced.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the accompanying drawings. In the drawings:

FIG. 1 is a schematic illustration of a vehicle according to some embodiments of the present application;

fig. 2 is an exploded perspective view of a battery pack according to some embodiments of the present application;

Fig. 3 is an exploded perspective view of a battery cell according to some embodiments of the present application;

fig. 4 is a perspective view of an electrode assembly according to some embodiments of the present application;

FIG. 5 is a schematic cross-sectional view of an electrode assembly according to some embodiments of the present application;

FIG. 6 is an enlarged partial schematic view of an electrode assembly according to some embodiments of the present application;

Fig. 7 is a schematic structural diagram of a negative electrode bending portion in an unfolded state according to some embodiments of the present application.

Reference numerals illustrate:

1000-vehicle; 100-battery pack; 200-a controller; 300-motor;

1-a battery cell; 2-a box body; 3-a bottom shell; 4-a cover;

10-an electrode assembly; 11-a positive pole piece; 111-positive electrode bending part; 12-a negative electrode piece; 121-a negative electrode bending part; 1211-waveform segments; 1211 a-peak portions; 1211 b-trough portions; 1211 c-a first side; 1211 d-second side; 13-spacers; 10A-inflection region; 10B-plateau;

20-a housing; 21-a housing; 22-end caps; 23-electrode terminals; 24-a pressure release mechanism;

An O-winding shaft; z-winding axis direction; x-stacking direction; y-length direction; c-winding direction; d-thickness direction.

Detailed Description

Embodiments of the technical scheme of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present application, and thus are merely examples, and are not intended to limit the scope of the present application.

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 "comprising" and "having" and any variations thereof in the description of the application and in the description of the drawings above are intended to cover non-exclusive inclusions.

In the description of embodiments of the present application, the technical terms "first," "second," "third," "fourth," "fifth," etc. are used merely to distinguish between different objects, and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, a particular order or a major-minor relationship. In the description of the embodiments of the present application, the meaning of "plurality" is two or more unless explicitly defined otherwise.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases 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. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

In the description of the embodiments of the present application, the term "and/or" is merely an association relationship describing an association object, and indicates that three relationships may exist, for example, a and/or B may indicate: a exists alone, A and B exist together, and B exists alone. In this context, the character "/" generally indicates that the associated object is an "or" relationship.

In the description of the embodiments of the present application, the orientation or positional relationship indicated by the technical terms "length", "width", "thickness", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "circumferential", etc. are orientation or positional relationship based on the drawings, and are merely for convenience of describing the embodiments of the present application and for simplifying the description, and are not intended to indicate or imply that the apparatus or element in question must have a specific orientation, be constructed, operated, or used 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 explicitly specified and limited otherwise, the terms "mounted," "connected," "secured" and the like should be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; or may be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to specific circumstances.

In the description of the embodiments of the present application, unless explicitly specified and limited otherwise, the term "contact" is to be understood in a broad sense as either direct contact or contact across an intermediate layer, as either contact with substantially no interaction force between the two in contact or contact with interaction force between the two in contact.

In the embodiment of the application, the battery cell can be a secondary battery cell, and the secondary battery cell refers to a battery cell which can activate the active material in a charging mode to continue to use after the battery cell discharges.

The battery cell may be a lithium ion battery cell, a sodium lithium ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium sulfur battery cell, a magnesium ion battery cell, a nickel hydrogen battery cell, a nickel cadmium battery cell, a lead storage battery cell, etc., which is not limited by the embodiment of the application.

The battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge of the battery cell, active ions (e.g., lithium ions) are inserted and extracted back and forth between the positive electrode and the negative electrode. The separator is arranged between the positive electrode and the negative electrode, can play a role in preventing the positive electrode and the negative electrode from being short-circuited, and can enable active ions to pass through.

In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

As an example, the positive electrode current collector has two surfaces opposing in its own thickness direction, and the positive electrode active material is provided on either or both of the two surfaces opposing the positive electrode current collector.

As an example, the positive electrode current collector may employ a metal foil or a composite current collector. For example, as the metal foil, silver-surface-treated aluminum or stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, titanium, or the like can be used. The composite current collector may include a polymeric material base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (e.g., a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery cell positive electrode active material may be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of the lithium-containing phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO ₄ (which may also be referred to simply as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO ₄), a composite of lithium manganese phosphate and carbon, lithium manganese phosphate, and a composite of lithium manganese phosphate and carbon.

In some embodiments, the positive electrode may be a metal foam. The foam metal can be foam nickel, foam copper, foam aluminum, foam alloy, foam carbon or the like. When the metal foam is used as the positive electrode, the surface of the metal foam may not be provided with the positive electrode active material, but may be provided with the positive electrode active material. As an example, a lithium source material, which is lithium metal and/or a lithium-rich material, potassium metal or sodium metal, may also be filled and/or deposited within the foam metal.

In some embodiments, the negative electrode may be a negative electrode tab, which may include a negative electrode current collector.

As an example, the negative electrode current collector may employ a metal foil, a foam metal, or a composite current collector. For example, as the metal foil, silver-surface-treated aluminum or stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, titanium, or the like can be used. The composite current collector may include a polymeric material base layer and a metal layer. The foam metal can be foam nickel, foam copper, foam aluminum, foam alloy, foam carbon or the like. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (e.g., a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). In some embodiments, the material of the positive electrode current collector may be aluminum and the material of the negative electrode current collector may be copper.

In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

In some embodiments, the separator is a separator film. The type of the separator is not particularly limited, and any known porous separator having good chemical stability and mechanical stability can be used.

As an example, the main material of the separator may be at least one selected from glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic.

In some embodiments, the separator is a solid state electrolyte. The solid electrolyte is arranged between the anode and the cathode and plays roles in transmitting ions and isolating the anode and the cathode.

In some embodiments, the battery cell further includes an electrolyte that serves to conduct ions between the positive and negative electrodes. The application is not particularly limited in the kind of electrolyte, and may be selected according to the need. The electrolyte may be liquid, gel or solid.

In some embodiments, the electrode assembly is a rolled structure. The positive plate and the negative plate are wound into a winding structure.

As an example, a plurality of positive electrode sheets and negative electrode sheets may be provided, respectively, and a plurality of positive electrode sheets and a plurality of negative electrode sheets may be alternately stacked.

As an example, the separator may be provided in plurality, respectively between any adjacent positive electrode sheet or negative electrode sheet.

As an example, the separator may be continuously provided, being provided between any adjacent positive electrode sheet or negative electrode sheet by winding.

In some embodiments, the electrode assembly may be cylindrical in shape, flat, etc.

In some embodiments, the electrode assembly is provided with tabs that can conduct current away from the electrode assembly. The tab includes a positive tab and a negative tab.

In some embodiments, the battery cell may include a housing. The case is used to encapsulate the electrode assembly, the electrolyte, and the like. The shell can be a steel shell, an aluminum shell, a plastic shell (such as polypropylene), a composite metal shell (such as a copper-aluminum composite shell), an aluminum-plastic film or the like.

As an example, the battery cell may be a cylindrical battery cell, a pouch battery cell, or other shaped battery cell, and the prismatic battery cell includes a square case battery cell, a blade-shaped battery cell, a polygonal-prismatic battery cell, such as a hexagonal-prismatic battery cell, etc., and the present application is not particularly limited.

In some embodiments, the housing includes an end cap and a case, the case being provided with an opening, the end cap closing the opening to form a closed space for accommodating the electrode assembly, electrolyte, and the like. The housing may be provided with one or more openings. One or more end caps may also be provided.

In some embodiments, at least one electrode terminal is provided on the housing, the electrode terminal being electrically connected to the tab. The electrode terminal may be directly connected to the tab, or may be indirectly connected to the tab through the adapter member. The electrode terminal may be provided on the terminal cover or may be provided on the case.

In some embodiments, a pressure relief mechanism is provided on the housing. The pressure release mechanism is used for releasing the internal pressure of the battery monomer.

In embodiments of the present application, the battery may be a battery module that includes one or more battery cells to provide a single physical module of higher voltage and capacity. When a plurality of battery cells are provided, the plurality of battery cells are connected in series, in parallel or in series-parallel through the converging component. The plurality of battery cells are arranged and fixed to form a battery module.

In some embodiments, the battery may be a battery pack including a case and at least one battery cell housed in the case.

In some embodiments, the tank may be part of the chassis structure of the vehicle. For example, a portion of the tank may become at least a portion of the floor of the vehicle, or a portion of the tank may become at least a portion of the cross member and the side member of the vehicle.

The present application will be described in detail below.

At present, new energy batteries are increasingly widely applied to life and industry. The new energy 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 a plurality of fields such as aerospace. With the continuous expansion of the application field of the power battery, the market demand of the power battery is also continuously expanding.

In addition to improving the performance of batteries, the problem of thermal runaway of batteries is also a non-negligible problem in the development of battery technology. Therefore, how to reduce the thermal runaway risk of the battery is a technical problem to be solved in the battery technology.

It has been found that during the charging process of a lithium ion battery, the phenomenon of lithium precipitation may lead to the risk of thermal runaway of the battery. For example, when the lithium intercalation site of the anode active material layer of the anode tab is less than the amount of lithium ions that can be provided by the cathode active material layer of its adjacent anode tab, a lithium precipitation phenomenon easily occurs. The lithium separation phenomenon not only reduces the performance of the lithium ion battery and shortens the cycle life greatly, but also limits the quick charge capacity of the lithium ion battery. In addition, when the lithium ion battery generates a lithium precipitation phenomenon, the precipitated lithium metal is very active and can react with electrolyte at a lower temperature, so that the battery generates heat, and the thermal runaway risk exists. When lithium is seriously separated, lithium dendrites can be formed on the surface of the negative electrode plate by the separated lithium ions, and the lithium dendrites easily puncture the separator, so that adjacent positive electrode plates and negative electrode plates are short-circuited, and the risk of thermal runaway exists.

Further research shows that in the battery with the winding structure, the electrode assembly is easy to generate a lithium precipitation phenomenon in a bending region, and the lithium precipitation phenomenon is caused because, in the bending region, the lithium intercalation position of the negative electrode active material layer of the negative electrode plate is less than the quantity of lithium ions which can be provided by the positive electrode active material layer of the positive electrode plate adjacent to the negative electrode plate and positioned outside the negative electrode plate, so that the lithium precipitation phenomenon is caused, and further, the thermal runaway risk exists.

In this regard, the present application provides a battery cell including a housing having an accommodating space; an electrode assembly disposed in the receiving space, the electrode assembly including: the positive pole piece and the negative pole piece are mutually overlapped and wound to form a winding structure, and the winding structure comprises a bending area; the positive pole piece comprises a plurality of positive pole bending parts positioned in the bending area, and the negative pole piece comprises a plurality of negative pole bending parts positioned in the bending area; at least a part of at least one negative electrode bending part is formed into a wavy structure, and the wavy structure is formed by bending a negative electrode plate into a wavy shape.

The negative pole piece that is located the bending zone is bent into the relief structure of relief form, and this relief structure can increase negative pole kink surface area, can provide more inserts lithium position to reduce the lithium emergence of separating out, and then reduce the thermal runaway risk.

The application also provides an electric device comprising the battery, and the battery can reduce occurrence of lithium precipitation and reduce thermal runaway risk of the battery, so that the reliability of the electric device can be improved.

The battery provided by the embodiment of the application can be used for, but is not limited to, an energy storage power supply system, a vehicle, a ship or an aircraft and other electric devices.

The battery provided by the embodiment of the application can be used as a battery pack in groups. The battery pack can also be used in, but not limited to, energy storage power systems, vehicles, boats or aircraft, and other electrical devices. The use of a battery pack can provide a higher total energy.

The embodiment of the application provides an electric device comprising the battery or the battery pack for providing electric energy, wherein the electric device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, a battery car, an electric automobile, a ship, a spacecraft and the like. Among them, the electric toy may include fixed or mobile electric toys, such as game machines, electric car toys, electric ship toys, electric plane toys, and the like, and the spacecraft may include planes, rockets, space planes, and spacecraft, and the like.

In the following embodiments, for convenience of explanation, the electric device according to an embodiment of the present application will be described by taking the vehicle 1000 as an example. The following description refers to the accompanying drawings.

Fig. 1 is a schematic structural diagram of a vehicle 1000 according to some embodiments of the present application. The vehicle 1000 may be a fuel oil vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or a range-extended vehicle. As shown in fig. 1, the battery pack 100 is provided inside the vehicle 1000, and the battery pack 100 may be provided at the bottom or the head or the tail of the vehicle 1000. The battery pack 100 may be used for power supply of the vehicle 1000, for example, the battery pack 100 may serve as an operating power source of the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, the controller 200 being configured to control the battery pack 100 to power the motor 300, for example, for operating power requirements during start-up, navigation, and travel of the vehicle 1000.

In some embodiments of the present application, the battery pack 100 may not only serve as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, instead of or in part instead of fuel oil or natural gas, to provide driving power for the vehicle 1000.

Referring to fig. 2, the battery pack 100 includes a case 2 and at least one battery cell 1, the case 2 including a bottom case 3 and a cover 4, the cover 4 covering over the bottom case 3, such that an accommodating space of the battery cell 1 is formed between the bottom case 3 and the cover 4.

In the battery pack 100, the plurality of battery cells 1 may be connected in series, parallel or a series-parallel connection between the plurality of battery cells 1, and the series-parallel connection refers to that the plurality of battery cells 1 are connected in series or parallel. The plurality of battery cells 1 can be directly connected in series or in parallel or in series-parallel, and then the whole body formed by the plurality of battery cells 1 is placed in the accommodating space formed by the bottom shell 3 and the cover body 4; of course, the battery pack 100 may also be a battery module form formed by connecting a plurality of battery cells 1 in series or parallel or series-parallel connection, and then connecting a plurality of battery modules in series or parallel or series-parallel connection to form a whole, and the battery modules are accommodated in an accommodating space formed by the bottom shell 3 and the cover body 4. The battery pack 100 may further include other structures, for example, the battery pack 100 may further include a bus member for making electrical connection between the plurality of battery cells 1.

Some embodiments of the present application are described in detail below with reference to fig. 3 to 7.

The embodiment of the application provides a battery monomer 1, a shell 20, a battery module and a battery module, wherein the shell is provided with an accommodating space; an electrode assembly 10 disposed in the receiving space, the electrode assembly 10 including: the positive pole piece 11 and the negative pole piece 12 are mutually laminated and wound to form a winding structure, a separator 13 is arranged between the positive pole piece 11 and the negative pole piece 12, and the winding structure comprises a bending area 10A; the positive electrode pole piece 11 comprises a plurality of positive electrode bending parts 111 positioned in the bending region 10A, and the negative electrode pole piece 12 comprises a plurality of negative electrode bending parts 121 positioned in the bending region 10A; at least a part of at least one anode bending portion 121 is formed in a wavy structure (shown in fig. 6 and 7), and the wavy structure is formed by bending the anode tab 12 into a wavy shape.

Referring to fig. 3, the case 20 may include a case 21 and an end cap 22, the case 21 being provided with an opening, the end cap 22 closing the opening to form a closed space for accommodating at least one electrode assembly 10 and electrolyte, etc. The housing 21 may be provided with one or more openings. One or more end caps 22 may also be provided. In some embodiments, the end cap 22 may be provided with an electrode terminal 23, and the electrode terminal 23 is used to electrically connect with the tab of the electrode assembly 10. In some embodiments, a pressure relief mechanism 24, such as a pressure relief valve, may also be provided on the end cap 22 for venting the internal pressure of the battery.

The positive electrode tab 11 includes a positive electrode current collector and a positive electrode active material layer coated on a surface of the positive electrode current collector. The material of the positive electrode current collector may be aluminum (aluminum foil), the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material may be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate, or the like. The positive electrode tab may be led out at one end of the positive electrode current collector.

The negative electrode tab 12 includes a negative electrode current collector and a negative electrode active material layer coated on a surface of the negative electrode current collector. The material of the anode current collector may be copper (copper foil), the anode active material layer includes an anode active material, and the anode active material may be carbon (e.g., graphite carbon) or silicon, or the like. A negative electrode tab may be led out at one end of the negative electrode current collector.

In order to ensure that the high current is not fused, the number of the positive electrode lugs is multiple, the positive electrode lugs are folded together, the number of the negative electrode lugs is multiple, and the negative electrode lugs are folded together.

The positive electrode tab 11 and the negative electrode tab 12 are stacked on each other and form a winding structure around a winding axis O (shown in fig. 4). The extending direction of the winding axis O (also referred to as the winding axis direction Z), the stacking direction X of the winding structure, and the longitudinal direction Y of the winding structure are perpendicular to each other. The winding structure has an inner side and an outer side, wherein the inner side is closer to the winding axis O than the outer side. The positive electrode sheet 11 and the negative electrode sheet 12 stacked on each other gradually thicken from the inside to the outside during winding around the winding axis O. It will be appreciated that the winding axis O is not a real component of the winding structure, being a virtual axis; the winding shaft O is a winding needle structure existing on a winding apparatus during the manufacturing process of the battery cell 1. The winding axis O is introduced for a more clear description of the embodiments of the present application.

A separator 13 is interposed between each adjacent positive electrode tab 11 and negative electrode tab 12, the separator 13 being used to separate the positive electrode tab 11 from the negative electrode tab 12, so as to reduce the risk of short circuits between the positive electrode tab 11 and the negative electrode tab 12. The material of the separator 13 may be PP (polypropylene) or PE (polyethylene).

The positive electrode tab 11, the negative electrode tab 12, and the separator 13 may each have a band-like structure. The positive electrode sheet 11, the separator 13, the negative electrode sheet 12, and the separator 13 may be laminated in this order, and then wound around the winding axis O from inside to outside for two or more turns to form a winding structure. Fig. 5 shows that the winding direction C is clockwise. Of course, the winding direction C may be counterclockwise.

The winding structure includes a bending region 10A, and the bending region 10A may be a region where the bending structure having an arc shape is located on the positive electrode tab 11 and the negative electrode tab 12, which is an example of the bending region.

In the bending region 10A, the positive electrode sheet 11 includes a plurality of positive electrode bending portions 111, and the negative electrode sheet 12 includes a plurality of negative electrode bending portions 121, the positive electrode bending portions 111 and the negative electrode bending portions 121 being alternately distributed from the inside to the outside, wherein the inside is closer to the winding axis O than the outside. As a specific example, the innermost positive electrode bent portion 111 is located outside the innermost negative electrode bent portion 121. The positive electrode bending portion 111 and the negative electrode bending portion 121 may have a substantially circular arc shape.

At least one negative electrode bending portion 121 of the plurality of negative electrode bending portions 121 in the bending region 10A has a wavy structure (shown in fig. 6 and 7), and the wavy structure is formed by bending the negative electrode tab 12 into a wavy shape.

In the bending region 10A, the relief structure is bent by the negative electrode tab 12 (negative electrode bending portion 121) to form a relief surface having a height uneven along its own thickness direction D (shown in fig. 7), and the thickness of each position of the relief surface is substantially uniform with the thickness of the negative electrode tab 12 where the relief structure is not provided. Thereby, the surface area of the anode bending part 121 can be increased without substantially changing the thickness of the anode bending part 121.

In the bending region 10A, the plurality of negative electrode bending portions 121 may have a partially undulating structure in the negative electrode bending portions 121, or may have an undulating structure in all the negative electrode bending portions 121.

In the bending region 10A, each negative electrode bending portion 121 may have a wavy structure in all regions or may have a wavy structure in some regions.

As a specific example, referring to fig. 6, all of the plurality of anode bent portions 121 and all areas of the respective anode bent portions 121 constitute a relief structure.

The negative electrode bending part 121 positioned in the bending region 10A is provided with a wavy structure, so that the surface area of the negative electrode bending part 121 is increased, and the surface area of the negative electrode active material layer is increased, therefore, more lithium intercalation sites can be provided for the positive electrode active material of the adjacent positive electrode bending part 111 to be intercalated into the negative electrode active material layer, thereby reducing occurrence of lithium precipitation, further reducing the thermal runaway risk of the battery, and simultaneously being beneficial to improving the performance and the cycle life of the battery.

In some embodiments, referring to fig. 5 and 6, the winding structure further includes a flat region 10B, bending regions 10A are respectively disposed at both ends of the flat region 10B along the winding direction C, and a relief structure is disposed at the negative electrode bending portion 121 of each bending region 10A.

The flat region 10B may be, for example, a region where the positive electrode tab 11 and the negative electrode tab 12 have a flat structure. Bending regions 10A are provided at both ends of the flat region 10B so that the electrode assembly 10 is constructed in a flat shape that can be easily put into a square-case battery.

The surface area of the anode active material layer at the anode bending part 121 of each bending region 10A is increased, so that the occurrence of lithium precipitation in each bending region 10A is reduced, the battery is comprehensively protected, and the thermal runaway risk of the battery is reduced.

In some embodiments, the undulating structure comprises a plurality of continuous wave segments 1211.

Each waveform segment 1211 has a peak portion 1211a and a trough portion 1211b, and each waveform segment 1211 includes a first face 1211c and a second face 1211d.

A wave segment 1211 may be a convex segment or a concave segment. For example, the convex section between two vertical dashed lines is exemplarily shown in fig. 7 as one wave section 1211.

Referring to fig. 7, as an example, in one waveform segment 1211, the first face 1211C and the second face 1211d are connected at the crest portion 1211a along the winding direction C, and in a plurality of waveform segments 1211, the second face 1211d of one waveform segment 1211 is connected with the first face 1211C of an adjacent waveform segment at the trough portion 1211 b. Of course, in one waveform segment 1211, the first surface 1211C and the second surface 1211d may be connected at the trough portion 1211b along the winding direction C, and in a plurality of waveform segments 1211, the second surface 1211d of one waveform segment 1211 is connected with the first surface 1211C of an adjacent waveform segment at the crest portion 1211 a.

The continuous wave-shaped segment 1211 further increases the surface area of the anode active material layer of the anode bent portion 121, thereby further reducing occurrence of lithium precipitation and reducing the risk of thermal runaway.

In some embodiments, the first face 1211c and the second face 1211d extend along the winding axis direction Z.

The first face 1211c and the second face 1211d of the wavy segment 1211 may extend along the winding axis direction Z to be flush with both edges of the negative electrode tab 12. The negative electrode bending portion 121 may be integrally bent to form a plurality of continuous wave segments 1211.

The first surface 1211c and the second surface 1211d of the wavy segment 1211 extend along the winding axis direction Z, and the negative electrode bending portion 121 is easy to process and mold.

In some embodiments, referring to fig. 7, the shortest distance from the peak 1211a to the trough 1211b of each waveform segment 1211 is L1, wherein L1 ranges from 0.5um to less than 50um.

Fig. 7 is a schematic diagram of the folded state of one anode folded portion 121 in fig. 6 when the anode folded portion 121 is unfolded (flattened), and the folded state of the anode folded portion 121 maintains the undulating structure in the folded state, but the anode folded portion 121 is unfolded entirely. The shortest distance L1 from the peak portion 1211a to the trough portion 1211b of each waveform segment 1211 is a distance between the peak portion 1211a and the trough portion 1211b along the thickness direction D of the anode bending portion 121 itself. The value of L1 may be, for example, 0.5um, 1um, 5um, 10um, 15um, 20um, 25um, 30um, 35um, 40um, 45um, etc.

In the anode bending part 121, the shortest distance L1 from the crest part 1211a to the trough part 1211b of the waveform segment 1211 is in a proper range, so that the surface area of the anode active material layer of the anode bending part 121 can be increased, and the distance between the anode bending part 121 and the adjacent anode bending part 111 can be limited in a proper range, thereby reducing or avoiding the risk that the anode active material of the anode bending part 111 is difficult to be embedded into the anode bending part 121 due to the overlarge distance between the trough part 1211b of the waveform segment 1211 and the anode bending part 111, and further reducing the occurrence of lithium precipitation and further reducing the thermal runaway risk of the battery.

In some embodiments, the shortest distance between the peak portions 1211a of adjacent two waveform segments 1211 is L2, wherein L2 ranges from 0.5mm or more to less than 500mm.

Referring to fig. 7, in the unfolded state of the negative electrode bending portion 121, the shortest distance between the crest portions 1211a of the adjacent two waveform segments 1211 along the winding direction C (horizontal direction) is L2.

The value of L2 may be 0.5mm、5mm、10mm、20mm、30mm、80mm、100mm、150mm、160mm、170mm、200mm、300mm、310mm、330mm、340mm、350mm、360mm、370mm、400mm、450mm、490mm, for example.

The shortest distance L2 between the crest portions 1211a of the adjacent two waveform segments 1211 is in a proper range, which not only increases the surface area of the anode active material layer of the anode bending portion 121, but also enables the anode active material of the anode bending portion 111 to be smoothly embedded into the anode active material layer of the anode bending portion 121, thereby reducing occurrence of lithium precipitation and further reducing the risk of thermal runaway of the battery.

In some embodiments, the shortest distance L1 from the peak portion 1211a to the trough portion 1211b of each waveform segment 1211 is the same among the plurality of waveform segments 1211, or the waveform segments that differ in the shortest distance L1 are included among the plurality of waveform segments 1211.

The shortest distance L1 from the crest portion 1211a to the trough portion 1211b of each waveform segment 1211 may be identical; or, among the plurality of waveform segments 1211, there may be at least partially different waveform segments of the shortest distance L1 from the peak portion 1211a to the trough portion 1211b of each waveform segment 1211.

In some embodiments, among the plurality of waveform segments 1211, the shortest distance L2 between the peak portions 1211a of the adjacent two waveform segments 1211 is the same, or includes waveform segments in which the shortest distance L2 is different.

Among the plurality of waveform segments 1211, the shortest distance L2 between the peak portions 1211a of the adjacent two waveform segments 1211 may be identical; or, among the plurality of waveform segments 1211, there may be waveform segments in which the shortest distance L2 between the peak portions 1211a of the adjacent two waveform segments 1211 is at least partially different.

The waveform segments 1211 of the same size constitute a regular undulating structure, and the waveform segments 1211 of different sizes constitute an irregular undulating structure, which can increase the surface area of the anode active material layer of the anode bent portion 121 and reduce occurrence of lithium precipitation. The regular undulating structure is beneficial to the production efficiency in batch processing and reduces the cost.

The undulating structure may be partially or entirely regular, or entirely irregular.

In some embodiments, the relief structure is configured as a sinusoidal waveform, as viewed along the winding axis direction Z.

The peak 1211a of the sine wave shape is an arc-shaped surface, which reduces the occurrence of puncturing the separator 13 during the winding process and the compacting process of the winding structure, thereby reducing the risk of thermal runaway of the battery.

Of course, the undulating structure may be configured as a non-sinusoidal waveform, as viewed along the winding axis direction Z, and the non-sinusoidal waveform may be, for example, a square waveform, a triangular waveform, a sawtooth waveform, or the like.

In some embodiments, at least at the innermost negative electrode bending part 121 among the plurality of negative electrode bending parts 121, an undulating structure is provided, wherein the innermost side is closer to the winding axis O of the winding structure than the outermost side.

The probability of lithium precipitation of the innermost negative electrode bending part 121 is high, and the undulation structure is arranged on the innermost negative electrode bending part 121, so that the probability of lithium precipitation of the position of the innermost negative electrode bending part 121 can be reduced, and the thermal runaway risk of the battery can be reduced.

In some embodiments, the positive electrode bending portion 111 is configured as an arc-shaped structure having a flat surface.

The embodiment of the present application also provides an electrode assembly 10 including: the positive pole piece 11 and the negative pole piece 12 are mutually laminated and wound to form a winding structure, a separator 13 is arranged between the positive pole piece 11 and the negative pole piece 12, and the winding structure comprises a bending area 10A; the positive electrode pole piece 11 comprises a plurality of positive electrode bending parts 111 positioned in the bending region 10A, and the negative electrode pole piece 12 comprises a plurality of negative electrode bending parts 121 positioned in the bending region 10A; the positive electrode pole piece 11 comprises a plurality of positive electrode bending parts 111 positioned in the bending region 10A, and the negative electrode pole piece 12 comprises a plurality of negative electrode bending parts 121 positioned in the bending region 10A; at least a part of at least one anode bending portion 121 is configured to have a wavy structure, and the wavy structure is formed by bending the anode tab 12 into a wavy shape.

For the specific details of the electrode assembly 10, reference is made to the description of the electrode assembly 10 in the embodiment of the battery cell 1, and no description is given here.

Specific examples of the present application will be described below.

Referring to fig. 4 to 7, an embodiment of the present application provides an electrode assembly 10, which includes a positive electrode tab 11 and a negative electrode tab 12, wherein the positive electrode tab 11 and the negative electrode tab 12 are stacked and wound with each other to form a winding structure, a separator 13 is interposed between the positive electrode tab 11 and the negative electrode tab 12, the winding structure includes a bending region 10A and a flat region 10B, and the bending region 10A is connected to both ends of the flat region 10B; the positive electrode tab 11 includes a plurality of positive electrode bent portions 111 located at each bent region 10A, and the negative electrode tab 12 includes a plurality of negative electrode bent portions 121 located at each bent region 10A; each negative electrode bending portion 121 has a wavy structure, and the wavy structure is formed by bending the negative electrode tab 12 into a wavy shape. The undulating structure includes a plurality of continuous undulating segments 1211 to increase the surface area of the anode active material layer of the anode bend 121, thereby reducing the occurrence of lithium precipitation and thus reducing the risk of thermal runaway.

The waveform segment 1211 has a peak portion 1211a and a trough portion 1211b, and the shortest distance from the peak portion 1211a to the trough portion 1211b is L1, wherein the range of L1 is 0.5um or more and less than 50um. The shortest distance between the crest portions 1211a of the adjacent two waveform segments 1211 is L2, wherein the range of L2 is 0.5mm or more and less than 500mm.

The embodiment of the application also provides a battery, referring to fig. 3, the battery includes: at least one of the above-mentioned battery cells 1. The battery may be a battery module or a battery pack 100.

The embodiment of the application also provides an electric device, which comprises a battery cell or a battery for providing electric energy.

The embodiment of the application also provides an energy storage device, which comprises the battery cell or the battery, wherein the battery can store electric energy and can provide electric energy.

The above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application, and they should be construed as falling within the scope of the present application. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the present application.

Claims

1.A battery cell, comprising:

A housing having an accommodation space;

an electrode assembly disposed in the receiving space, the electrode assembly comprising:

The positive pole piece and the negative pole piece are mutually laminated and wound to form a winding structure, the winding structure comprises a bending area, and a separator is arranged between the positive pole piece and the negative pole piece in a clamping way;

The positive pole piece comprises a plurality of positive pole bending parts positioned in the bending area, and the negative pole piece comprises a plurality of negative pole bending parts positioned in the bending area; at least a part of at least one of the negative electrode bending parts is formed into a wavy structure, and the wavy structure is formed by bending the negative electrode plate into a wavy shape.

2. The battery cell of claim 1, wherein the battery cell comprises a plurality of cells,

The undulating structure comprises a plurality of continuous wave segments.

3. The battery cell of claim 2, wherein the battery cell comprises a plurality of cells,

The wave segments having wave crest portions and wave trough portions, in one of the wave segments, the wave segment comprising a first face and a second face,

The first face and the second face are connected at the wave crest portion along the winding direction of the winding structure, and the second face of one wave section is connected with the first face of the adjacent wave section at the wave trough portion in a plurality of wave sections;

The first face and the second face extend along a winding axis direction of the winding structure.

4. The battery cell of claim 3, wherein the battery cell comprises a plurality of cells,

In one of the waveform segments, the shortest distance from the crest portion to the trough portion of the waveform segment is L1, wherein the range of L1 is 0.5um or more and less than 50um; and/or the number of the groups of groups,

The shortest distance between the peaks of two adjacent waveform segments is L2, wherein the range of L2 is more than or equal to 0.5mm and less than 500mm.

5. The battery cell of claim 2, wherein the battery cell comprises a plurality of cells,

The undulating structure is configured as a continuous sinusoidal waveform as viewed along a winding axis direction of the winding structure.

6. The battery cell of claim 1, wherein the battery cell comprises a plurality of cells,

The winding structure comprises a flat area, bending areas are respectively arranged at two ends of the flat area along the winding direction of the winding structure, and the rolling structure is arranged at the bending parts of the cathodes of the bending areas.

7. The battery cell of claim 1, wherein the battery cell comprises a plurality of cells,

And among the plurality of negative electrode bending parts, at least the innermost negative electrode bending part is provided with the undulating structure.

8. An electrode assembly, comprising:

9. The electrode assembly of claim 8, wherein the electrode assembly comprises,

The undulating structure comprises a plurality of continuous wave segments.

10. The electrode assembly of claim 9, wherein the electrode assembly comprises,

11. The electrode assembly of claim 10 wherein the electrode assembly comprises,

12. The electrode assembly of claim 9, wherein the electrode assembly comprises,

13. The electrode assembly of claim 8, wherein the electrode assembly comprises,

14. The electrode assembly of claim 8, wherein the electrode assembly comprises,

15. A battery, comprising: at least one battery cell according to any one of claims 1 to 7.

16. An electrical device comprising a battery cell according to any one of claims 1-7 or a battery according to claim 15, the battery being capable of providing electrical energy to the electrical device.

17. An energy storage device comprising a cell according to any one of claims 1 to 7 or a battery according to claim 15, said battery being capable of storing electrical energy and providing electrical energy.