Battery cell and battery

Abstract

The utility model discloses a battery cell. The battery cell comprises a pole piece, a diaphragm and a conductive piece, the pole piece comprises a positive pole piece and a negative pole piece, and the diaphragm is positioned between the positive pole piece and the negative pole piece; the pole piece comprises a pole piece main body and lug parts, the lug parts protrude out of the pole piece main body, the lug parts are stacked in the thickness direction of the battery cell to form a lug group, and the conductive piece is fixedly connected with the lug group. According to the technical scheme of the utility model, the lug parts are stacked along the thickness direction of the battery cell to form the lug group, and then the conductive piece is arranged at the lug group so as to press the lug group and make close contact with the lug group; according to the lithium ion battery, effective concentration of electric energy can be promoted, meanwhile, the conductive piece is installed at the position of the tab set, effective connection between the lug parts of the tab set can be achieved, stable connection between the lug parts of the tab set can be achieved through the installation mode, current between the lug parts can be evenly distributed in the charging and discharging process, and the overall performance and reliability are enhanced. In addition, the utility model also discloses a battery.

Description

Technical Field

[0001] The utility model relates to the field of batteries, in particular to a battery core and a battery. Background Art

[0002] Laminated and multi-electrode batteries are high energy density battery structures with broad application prospects. The application of composite current collectors in laminated and multi-electrode batteries will increase the safety performance and energy density of the battery. However, the electrical conductivity of the metal layer in the composite current collector has always been a key factor restricting its performance.

[0003] At present, some methods have been proposed to solve the problem of electrical conductivity of the metal layer in the composite current collector. For example, welding metal foil to cover the edge of the composite current collector to collect current, welding metal foil is prone to problems such as loose welding or perforation, affecting the reliability and performance of the battery, while this will increase manufacturing costs and reduce manufacturing efficiency. Utility Model Content

[0004] The main purpose of the utility model is to provide a battery core, aiming to solve the problem of unreliable electrical conduction of the metal layer of the composite current collector by welding metal foil at the edge of the composite current collector.

[0005] In order to achieve the above object, the utility model provides a battery cell, which comprises:

[0006] A pole piece, a diaphragm and a conductive member, wherein the pole piece comprises a positive pole piece and a negative pole piece, and the diaphragm is located between the positive pole piece and the negative pole piece; the pole piece comprises a pole piece body and a lug portion, the lug portion protrudes from the pole piece body, the lug portions are stacked along the thickness direction of the battery cell to form a pole lug group, and the conductive member is fixedly connected to the pole lug group.

[0007] In some embodiments, the positive electrode sheet and the negative electrode sheet both include a composite current collector, and the composite current collector includes an insulating layer and two conductive layers respectively disposed on opposite sides of the insulating layer;

[0008] Two active material layers, each of which is disposed on a side of the conductive layer facing away from the insulating layer, and the composite current collector comprises an embedded portion disposed between the two active material layers and the convex ear portion extending outside the two active material layers.

[0009] In some embodiments, the positive electrode sheets and the negative electrode sheets are alternately stacked in plurality, and the separator is disposed between each of the positive electrode sheets and the negative electrode sheets;

[0010] Wherein, the lug portions of each of the positive electrode sheet and the negative electrode sheet are stacked along the thickness direction of the battery cell to form the lug group.

[0011] In some embodiments, the lugs of each of the positive electrode sheet and the negative electrode sheet are staggered and distributed in sequence along the length direction of the battery cell.

[0012] In some embodiments, the conductive member is disposed outside the lug portion of at least the two positive electrode plates, and the inner side wall of the conductive sleeve is in contact with the conductive layer of each lug portion respectively.

[0013] In some embodiments, the conductive member is a conductive sleeve, which is disposed outside the lug portion, and an inner side wall of the conductive sleeve is respectively in contact with the two conductive layers of each lug portion.

[0014] In some embodiments, the inner side wall of the conductive sleeve has at least two convex grooves disposed at intervals; each of the convex grooves is in contact with the two conductive layers of each of the lug portions.

[0015] In some embodiments, each convex pattern is an annular convex pattern disposed on the inner side wall of the conductive sleeve along the circumference of the conductive sleeve.

[0016] In some embodiments, the inner side wall of the conductive sleeve is provided with at least two circles of annular convex patterns arranged at intervals, and each circle of the annular convex patterns is in contact with the two conductive layers of each of the lug portions.

[0017] The utility model further provides a battery, comprising a shell and the aforementioned battery core, wherein the battery core is arranged in the shell.

[0018] In the technical solution of the utility model, the lug parts are stacked along the thickness direction of the battery cell to form a lug group, and then the conductive member is installed at the lug group to compress the lug group and make close contact with it; in this way, the stacking of the lug parts and the formation of the lug group can promote the effective concentration of electric energy. At the same time, the conductive member is installed at the lug group to achieve effective connection between the lug parts of the lug group. This installation method can not only achieve stable connection between the lug parts of the lug group, but also evenly distribute the current between the lug parts during charging and discharging, thereby enhancing the overall performance and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of a battery cell in one embodiment of the utility model;

[0020] Figure 2 This is a schematic diagram of the structure of a battery cell in one embodiment of the utility model;

[0021] Figure 3 This is a schematic structural diagram of a conductive member in another embodiment of the utility model;

[0022] Figure 4 It is a structural schematic diagram of a conductive member in another embodiment of the utility model.

[0023] Description of Figure Numbers:

[0024] 100, pole piece; 102, positive pole piece; 106a, convex ear portion; 106, composite current collector; 108, insulating layer; 110, conductive layer; 112, active material layer; 114, embedded portion; 104, negative pole piece; 200, diaphragm; 300, conductive member; 300a, convex pattern.

[0025] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the scheme in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0028] It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0029] In addition, the descriptions of "first", "second", etc. in the present utility model are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0030] Reference Figure 1 , Figure 1 It is a schematic diagram of the structure of a battery cell in one embodiment of the utility model.

[0031] The battery cell proposed in the embodiment of the utility model includes pole pieces, a diaphragm 200 and a conductive member 300, the pole pieces include a positive pole piece 102 and a negative pole piece 104, the diaphragm 200 is located between the positive pole piece 102 and the negative pole piece 104; the pole piece includes a pole piece body and a lug portion 106a, the lug portion 106a is protruding from the pole piece body, the lug portion 106a is stacked along the thickness direction of the battery cell to form a pole lug group, and the conductive member 300 is fixedly connected to the pole lug group.

[0032] In this embodiment, the pole piece can use aluminum foil as the positive electrode current collector and copper foil as the negative electrode current collector. Aluminum foil and copper foil have excellent electrical conductivity and corrosion resistance, which can effectively improve the conductivity and service life of the battery. The positive electrode material generally uses lithium nickel cobalt manganese oxide (NCM) or lithium iron phosphate (LFP), and the negative electrode material uses graphite or silicon carbon composite material. These materials have high energy density and stable electrochemical properties, which help to improve the overall performance of the battery.

[0033] The separator 200 can be made of polypropylene (PP) or polyethylene (PE) microporous membrane, which has good mechanical strength and chemical stability, can effectively isolate the positive and negative electrodes, prevent short circuits, and has good electrolyte wettability to ensure smooth passage of ions. The conductive member 300 is made of high-purity copper or aluminum to ensure good electrical and thermal conductivity.

[0034] The conductive member 300 is mainly used to realize the electrical connection between the lugs 106a. Its material can generally be copper (Cu), which is a commonly used conductive material with good electrical conductivity and mechanical strength. The copper conductive layer 110104 is usually tightly combined with the polymer macromolecular layer to ensure the effective conduction of current. Of course, in other embodiments, aluminum, silver or other alloys, such as copper-aluminum alloy, can also be selected to balance conductivity, cost and mechanical properties.

[0035] That is, the material selection of the conductive member 300 can be determined according to the specific design requirements, cost and performance requirements of the battery. The trade-off between different materials depends on the application scenario and priority of the battery.

[0036] The battery cell of this embodiment mainly adopts the laminated battery cell, and its manufacturing process mainly involves pressing the diaphragm 200 material between the pole pieces. The pole pieces are then cut into the required shape and size. Subsequently, the lamination process is entered, in which a special device (such as a lamination machine) is used to alternately stack the positive pole piece 102, the diaphragm 200 and the negative pole piece 104. The lug portion 106a is reserved during the lamination process. After stacking, the battery chip is placed in the housing and sealed and the electrolyte is injected. In the process of connecting multiple battery cells, the conductive member 300 can be sleeved on these reserved lug portions 106a, and then some auxiliary means can be used to enhance the connection between the conductive member and the lug portion, for example:

[0037] 1. Use conductive adhesive bonding. Conductive adhesive can connect the conductive parts to the tab group without high temperature. This method is suitable for sensitive components because it will not cause thermal damage to other parts of the battery.

[0038] 2. Fix the conductive parts to the tab assembly by bolts, screws or other mechanical fasteners. This method is simple and reliable.

[0039] These methods can provide a connection strength similar to welding, while avoiding the problems that welding may cause, such as weak welding or perforation, etc. Finally, a current collecting tab is connected to the conductive member 300 for connecting to an external circuit to form a loop.

[0040] Through the above steps, the conductive member 300 forms a stable and efficient electrical connection with the reserved lug portion 106a, which is crucial to the overall performance and reliability of the battery cell. This connection method not only improves the manufacturing efficiency of the battery cell, but also ensures the stability and safety of the battery cell during long-term use.

[0041] In the battery cell of this embodiment, during operation, the positive electrode sheet 102 and the negative electrode sheet 104 undergo electrochemical reactions through lithium ions in the electrolyte. The current is conducted from the main body of the positive electrode sheet 102 through the lug portion 106a to the tab group, and the tab group collects and transmits the current through the conductive member 300. The positive and negative electrodes are effectively isolated by the separator 200 to prevent short circuits, while allowing lithium ions to pass through during the charge and discharge process.

[0042] During the charging process, lithium ions move from the positive electrode to the negative electrode through the electrolyte and the separator 200, and are embedded in the negative electrode material. At the same time, electrons reach the negative electrode through the external circuit to achieve energy storage. During the discharge process, lithium ions escape from the negative electrode, pass through the separator 200 and move back to the positive electrode. At the same time, electrons flow back to the positive electrode through the external circuit to release electrical energy. The conductive member 300 connects the tab group to ensure efficient conduction and distribution of current in the battery cell, reducing energy loss in current transmission.

[0043] In the technical solution of the utility model, the lug portions 106a are stacked along the thickness direction of the battery cell to form a lug group, and then the conductive member 300 is installed at the lug group to compress the lug group and make close contact with it; in this way, the stacking of the lug portions 106a and the formation of the lug group can promote the effective concentration of electric energy. At the same time, the conductive member 300 is installed at the lug group to achieve effective connection between the lug portions 106a of the lug group. This installation method can not only achieve stable connection between the lug portions 106a of the lug group, but also evenly distribute the current between the lug portions 106a during charging and discharging, thereby enhancing the overall performance and reliability.

[0044] In addition, the equal distribution of electric energy can reduce the internal resistance of the battery cell. Due to the reduction of internal resistance, the charging and discharging efficiency of the battery can be significantly improved. This means that the battery can charge and release energy faster, improving the power density and service life of the battery. In addition, the reduction in resistance also reduces the heat generated during the charging and discharging process, improving the safety performance of the battery. These improvements combined have significantly enhanced the performance, efficiency and safety of the battery cell proposed in the utility model.

[0045] See also Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the structure of a battery cell in an embodiment of the utility model. Figure 2 It is a schematic diagram of the structure of a battery cell in one embodiment of the utility model.

[0046] In this embodiment, the positive electrode sheet 102 and the negative electrode sheet 104 both include a composite current collector 106, and the composite current collector 106 includes an insulating layer 108 and two conductive layers 110 respectively disposed on opposite sides of the insulating layer 108;

[0047] Two active material layers 112 are provided, each active material layer 112 is provided on a side of a conductive layer 110 facing away from the insulating layer 108 , and the composite current collector 106 has an embedded portion 114 provided between the two active material layers 112 and a protruding ear portion 106 a extending outside the two active material layers 112 .

[0048] In this embodiment, the composite current collector 106 is used as a substrate to provide a coating basis for the conductive layer 110, wherein the composite current collector 106 can be formed by combining a metal layer and a polymer material layer. This structure is similar to a "sandwich", wherein the metal layer is usually copper or aluminum, and the polymer material layer can be PET (polyethylene terephthalate), PP (polypropylene) or PI (polyimide), etc.

[0049] The process of forming the metal layer and the polymer material layer mainly includes the following steps:

[0050] First, select a suitable polymer material as the base film, common ones include PET (polyethylene terephthalate), PP (polypropylene) or PI (polyimide) and the like.

[0051] Then, a double copper / aluminum conductive layer 110104 can be deposited on the upper and lower surfaces of the base film by vacuum coating and other processes. This step is the key to forming the composite current collector 106, which allows the metal layer to be closely combined with the polymer material layer.

[0052] Finally, on the thin metal layer formed by vacuum coating, electroplating is used to further thicken the metal layer to achieve the required mechanical strength and electrical conductivity. This process can combine the advantages of the metal layer and the polymer material layer, maintaining the conductivity and mechanical strength of the metal while utilizing the lightweight and safety of the polymer material.

[0053] The composite current collector formed by this combination is lightweight, which helps to increase the energy density of the battery. At the same time, the polymer material layer can melt at high temperatures to form a short circuit, blocking the flow of current, thereby cutting off the short-circuit current when a short circuit occurs inside the battery, effectively preventing thermal runaway of the battery.

[0054] At the same time, since the amount of metal used is reduced, the manufacturing cost of the composite current collector 106 is lower than that of the traditional metal current collector.

[0055] Active material layer 112, in this embodiment, the function of active material layer 112 is to store and release lithium ions, thereby realizing the charge and discharge function of the battery. Common active material materials include lithium manganese oxide, lithium cobalt oxide, and nickel cobalt manganese oxide. These materials can embed and de-embed lithium ions in their structures, and this process is the basis for the operation of lithium batteries. The benefits of using these materials include high energy density, stable discharge voltage, and long cycle life.

[0056] In this embodiment, a part of the composite current collector 106 is used as the embedded part 114, which is used as the basis for coating the active material layer 112, and the other part extends out of the two active material layers 112 to serve as the convex ear part 106a; in this way, after the positive electrode sheets 102 and the negative electrode sheets 104 are alternately stacked, the convex ear part 106a also presents a stacked image. The difference is that the convex ear parts 106a of multiple positive electrode sheets 102 can be stacked, and then the convex ear parts 106a of the negative electrode sheets 104 protrude and stack, respectively forming their own pole ear groups, which not only provides a basis for the installation of the conductive member 300, but also facilitates the efficient collection of electric energy.

[0057] Continue reading Figure 2 In this embodiment, a plurality of positive electrode sheets 102 and negative electrode sheets 104 are alternately stacked, and a separator 200 is disposed between each positive electrode sheet 102 and each negative electrode sheet 104;

[0058] The lug portions 106 a of each positive electrode sheet 102 and negative electrode sheet 104 are stacked along the thickness direction of the battery cell to form a lug group.

[0059] In this embodiment, the lugs 106a of each positive electrode sheet 102 and negative electrode sheet 104 are stacked along the thickness direction of the battery cell to form respective lug groups. In this way, the lug group of the positive electrode sheet 102 can be independent of the lug group of the negative electrode sheet 104, thereby providing a basis for the subsequent installation of the conductive member 300. This stacking method can be achieved by an automated stacking machine, which can accurately place each electrode sheet and ensure that the lugs 106a are correctly arranged.

[0060] In this embodiment, the lug portion 106a of each positive electrode sheet 102 and negative electrode sheet 104 is stacked along the thickness direction of the battery cell to form independent lug groups, which helps to enhance the convergence of electric energy. At the same time, when combined with the conductive member 300, the current can be evenly distributed to reduce internal resistance.

[0061] Continue reading Figure 2 In this embodiment, the lugs 106 a of each positive electrode sheet 102 and negative electrode sheet 104 are staggered and distributed in sequence along the length direction of the battery cell.

[0062] In this embodiment, in order to enable the conductive member 300 to effectively contact the lug portion 106a, the lug portions 106a of each positive electrode sheet 102 and negative electrode sheet 104 are staggered in sequence along the length direction of the battery cell. The staggered lug portions 106a enable the surface of each lug portion 106a to fully contact the conductive member 300, thereby achieving uniform distribution of current inside the battery cell, avoiding local overheating and current concentration, and thus improving the overall performance and safety of the battery.

[0063] In this embodiment, the staggered lugs 106a can ensure that the surface of each lug 106a is in contact with the conductive member 300, which is conducive to improving the conduction efficiency of electric energy, thereby improving the charging and discharging efficiency and output power of the battery. At the same time, the staggered lug 106a design not only facilitates the installation of the conductive member 300, but also helps to efficiently gather electric energy and improve the overall battery performance.

[0064] See also Figure 3 , Figure 3 FIG. 1 is a schematic structural diagram of a conductive member 300 in another embodiment of the present invention.

[0065] In this embodiment, the conductive member 300 is disposed outside the lug portions 106 a of at least two positive electrode sheets 102 , and the inner sidewall of the conductive sleeve is in contact with the conductive layer 110 of each lug portion 106 a .

[0066] In this embodiment, the conductive member 300 may be a strip-shaped conductive sheet, and its shape is varied, mainly designed according to the shape change of the lug portion 106a. For example, it may be circular, rectangular or any other shape suitable for a specific application. They are usually made of conductive materials, such as metal or conductive plastic, and can be customized as needed to adapt to different lug portions 106a and conductive layers 110. The stable connection between the conductive sheet and the lug portion 106a can be achieved by using conductive adhesives, which can be used to replace welding, providing more design flexibility and a simplified assembly process.

[0067] During use, the current path of the conductive sheet is determined by its internal structure. The current flows from one conductive layer 110 to the conductive sheet and then distributes to another conductive layer 110. This path design ensures uniform distribution and effective transmission of the current.

[0068] In this embodiment, the use of the conductive member 300 can improve the reliability and durability of the circuit. They can provide stable current transmission, reduce connection points, and thus reduce the failure rate. In addition, the use of the conductive member 300 can simplify the assembly process and reduce manufacturing costs.

[0069] Furthermore, in order to enhance the transmission efficiency, the contact area between the conductive member 300 and the lug portion 106a can be increased. Specifically, in this embodiment, the conductive member 300 is a conductive sleeve, which is disposed outside the lug portion 106a, and the inner side wall of the conductive sleeve is respectively in contact with the two conductive layers 110 of each lug portion 106a.

[0070] In this embodiment, the inner wall of the conductive sleeve is fully in contact with the conductive layer 110 on the two opposite sides of the lug portion 106a, thereby increasing the contact area and reducing the contact resistance; a larger contact area means a more stable physical connection, ensuring uniform distribution of current inside the battery, helping to prevent local overheating and increasing the service life of the battery.

[0071] At the same time, the design of the conductive sleeve simplifies the assembly process, making battery production more efficient and reducing manufacturing costs.

[0072] Continue reading Figure 3 In order to increase the transmission efficiency and stability in this embodiment, the connection between the conductive sleeve and the lug portion 106a can be enhanced. In this embodiment, the inner side wall of the conductive sleeve has at least two spaced-apart convex grooves 300a, and each convex groove 300a is in contact with the two conductive layers 110 of each lug portion 106a.

[0073] In this embodiment, at least two convex grooves 300a are arranged at intervals on the inner side wall of the conductive sleeve to enhance the connection between the conductive sleeve and the lug portion 106a; the convex grooves 300a can be formed in one piece with the conductive sleeve. Of course, in other embodiments, fillers can be added between the inner side wall of the conductive sleeve and the lug portion 106a to increase the contact area. By increasing the contact area, not only the connection stability is enhanced, but also the current conduction area is increased, which is beneficial to the transmission of current.

[0074] In this embodiment, the presence of the convex pattern 300a increases the mechanical interlocking between the conductive sleeve and the lug portion 106a, thereby improving the stability of the connection. This physical interlocking ensures that the connection will not easily loosen even under vibration or mechanical stress. At the same time, the convex pattern 300a improves the electrical contact performance by increasing the contact area between the conductive sleeve and the conductive layer 110. This helps to reduce the contact resistance, thereby improving the efficiency of current transmission.

[0075] See also Figure 4 , Figure 4 FIG. 1 is a schematic structural diagram of a conductive member 300 in another embodiment of the present invention.

[0076] Furthermore, each convex pattern 300a can be an annular convex pattern 300a disposed around the inner side wall of the conductive sleeve along the circumference of the conductive sleeve. The annular convex pattern 300a can form a larger contact area with the conductive layer 110 of the lug portion 106a, thereby providing a more stable current transmission path. It can also better grasp the lug portion 106a, increase the stability of the mechanical connection, and reduce the possibility of loose connection due to vibration or other external forces. At the same time, the annular convex pattern 300a helps to evenly distribute the current between the conductive layers 110, reduce the risk of local overheating and current concentration, and improve the overall battery performance and safety.

[0077] Furthermore, the inner side wall of the conductive sleeve is provided with at least two circles of annular convex patterns 300a arranged at intervals, and each circle of annular convex patterns 300a contacts the two conductive layers 110 of each lug portion 106a. In this embodiment, at least two circles of annular convex patterns 300a can further provide a larger contact area, and the increase in the contact area means that the contact resistance can be further reduced, thereby improving the efficiency of current transmission.

[0078] The utility model also provides a battery, which includes a housing and the pole piece of the above embodiment. Since the battery adopts all the technical solutions of all the above embodiments, it at least has all the technical effects brought by the technical solutions of the above embodiments, which will not be described one by one here. Among them, the battery cell is arranged in the housing.

[0079] In this embodiment, the battery design includes a housing and at least one battery cell of the above-mentioned embodiment, wherein the housing is usually rectangular or cylindrical in shape to adapt to different types of electronic devices, and the battery cell is flattened in shape to increase energy density and adapt to compact space requirements.

[0080] During the assembly process, the battery cell can be placed in the housing by sliding, inserting, etc., wherein the fit between the battery cell and the housing needs to be precisely controlled in size to ensure that the battery cell is stable in the housing and does not move. Of course, in other embodiments, a shock-absorbing material can be provided inside the housing to protect the battery cell from impact and vibration.

[0081] In this embodiment, a solid shell can protect the battery cell from physical damage and prevent the leakage of chemical substances inside the battery. In other words, the shell provides additional structural support and prolongs the service life of the battery. The above is only a partial or preferred embodiment of the utility model. Neither the text nor the drawings can limit the scope of protection of the utility model. All equivalent structural changes made by using the contents of the utility model specification and drawings under the concept of an overall concept of the utility model, or direct / indirect application in other related technical fields are included in the scope of protection of the utility model.

Claims

1. A battery cell, characterized in that: include: It includes pole pieces, diaphragms and conductive parts, the pole pieces include positive pole pieces and negative pole pieces, the diaphragm is located between the positive pole pieces and the negative pole pieces; the pole pieces include pole piece bodies and lugs, the lugs protrude from the pole piece bodies, the lugs are stacked along the thickness direction of the battery cell to form pole lug groups, and the conductive parts are fixedly connected to the pole lug groups.

2. The battery cell according to claim 1, characterized in that: The positive electrode sheet and the negative electrode sheet both include a composite current collector, and the composite current collector includes an insulating layer and two conductive layers respectively arranged on opposite sides of the insulating layer; Two active material layers, each of which is disposed on a side of the conductive layer facing away from the insulating layer, and the composite current collector comprises an embedded portion disposed between the two active material layers and the convex ear portion extending outside the two active material layers.

3. The battery cell according to claim 2, characterized in that: The positive electrode sheets and the negative electrode sheets are alternately stacked in plurality, and the separator is disposed between each of the positive electrode sheets and the negative electrode sheets; Wherein, the lug portions of each of the positive electrode sheet and the negative electrode sheet are stacked along the thickness direction of the battery cell to form the lug group.

4. The battery cell according to claim 3, characterized in that: The lugs of each of the positive pole piece and the negative pole piece are also staggered and distributed in sequence along the length direction of the battery cell.

5. The battery cell according to claim 2 or 4, characterized in that: The conductive member is arranged outside the lug portions of at least the two positive electrode plates, and the inner side wall of the conductive member is in contact with the conductive layer of each lug portion respectively.

6. The battery cell according to claim 5, characterized in that: The conductive member is a conductive sleeve, which is sleeved outside the lug portion, and the inner side wall of the conductive sleeve is respectively in contact with the two conductive layers of each lug portion.

7. The battery cell according to claim 6, characterized in that: The inner side wall of the conductive sleeve has at least two convex grooves arranged at intervals; each of the convex grooves is in contact with the two conductive layers of each lug portion.

8. The battery cell according to claim 7, characterized in that: Each convex pattern is an annular convex pattern arranged on the inner side wall of the conductive sleeve along the circumference of the conductive sleeve.

9. The battery cell according to claim 8, characterized in that: The inner side wall of the conductive sleeve is provided with at least two circles of annular convex patterns arranged at intervals, and each circle of the annular convex patterns is in contact with the two conductive layers of each lug portion.

10. A battery, characterized in that: The invention comprises a shell, and the battery cell according to any one of claims 1 to 9, wherein the battery cell is arranged in the shell.

Images