A laminated battery and a method of manufacturing the same

Abstract

The present application relates to the technical field of battery, in particular to a laminated battery, comprising a shell and an electrode assembly contained in the shell, the electrode assembly comprising a plurality of first pole pieces and two second pole pieces stacked along the thickness direction, the second pole piece comprising a current collector, an active material layer and a functional layer, the functional layer being arranged at the edge region of the surface of the current collector. The setting of the functional layer alleviates the warping of the pole piece due to the inconsistent extension tension of the two sides of the single-sided sheet during the rolling process, and since the functional layer is arranged at the edge region of the surface of the current collector, the thickness of the edge of the pole piece is larger, and when heat pressing is performed, the edge of the pole piece is subjected to greater pressure, the warping of the pole piece can be flattened through the step of heat pressing, and the edge is not prone to lithium precipitation. In addition, the present application also discloses a preparation method of the above-mentioned laminated battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a laminated battery and a preparation method thereof. BACKGROUND

[0002] The laminated battery is widely used because it can avoid corner lithium precipitation and has high energy density. However, there is a demand for further improving the energy density of the laminated battery. In order to improve the energy density of the laminated battery, the outermost pole piece of the laminated battery cell is usually set as a single-sided pole piece. The structure of the single-sided pole piece is that one side of the current collector is coated with active material, and the other side of the current collector is not coated with active material, thereby reducing the amount of material not participating in the reaction, thereby effectively increasing the content of active material participating in the reaction per unit volume or unit mass of the battery, which directly improves the energy density of the battery.

[0003] However, since one side of the single-sided pole piece has active material and the other side does not have active material, the extension tension on both sides of the single-sided pole piece is inconsistent during the rolling process of the single-sided pole piece, which is prone to warping. Further, after the single-sided pole piece is warped, it is difficult to process during lamination. Moreover, when using active materials with a large expansion coefficient, the single-sided pole piece is prone to weak adhesion due to expansion, which may further cause edge lithium precipitation.

[0004] Therefore, there is an urgent need to invent a laminated battery and a preparation method thereof to solve the above technical problems. SUMMARY

[0005] One of the purposes of the present application is to provide a laminated battery that can improve the energy density of the battery and reduce edge lithium precipitation of the battery.

[0006] To solve the above technical problems, the present application adopts the following technical solutions:

[0007] The present application provides a laminated battery, which comprises a shell and an electrode assembly contained in the shell. The electrode assembly comprises a plurality of first pole pieces and two second pole pieces stacked along the thickness direction, wherein all the first pole pieces are arranged between the two second pole pieces. The second pole piece comprises a current collector, an active material layer and a functional layer, and the active material layer and the functional layer are arranged on both sides of the current collector in the thickness direction, respectively. The functional layer is arranged on the side away from the first pole piece, and the functional layer is arranged in the edge region of the surface of the current collector.

[0008] Specifically, the material of the functional layer is one or more of ceramic material, elastic material, active material and resin material.

[0009] Specifically, the thickness of the functional layer is between 0.5 and 1.5 times the thickness of the active material layer.

[0010] Specifically, the functional layer is provided with a chamfer.

[0011] Specifically, the thickness of the functional layer is 0.1-0.5 mm.

[0012] Specifically, the outer boundary of the edge region coincides with the surface boundary of the current collector, the distance from the inner boundary of the edge region to the surface boundary of the current collector is 0.1-10 mm, and the functional layer covers the edge region.

[0013] Specifically, when the second tab is a negative tab, the width of the edge region is greater than the width of the overhang region.

[0014] Specifically, the thickness of the functional layer gradually increases from the inner boundary of the edge region to the inside of the functional layer.

[0015] The application has the beneficial effects that: the application reduces the difference in tension between the two surfaces of the current collector during rolling by providing a functional layer, alleviates the warping of the tab during rolling due to the inconsistent tension on both sides of the single-sided sheet, and because the functional layer is provided in the edge region of the surface of the current collector, the thickness of the edge of the tab is greater, the edge of the tab receives greater pressure during hot pressing formation, the warping of the tab can be flattened through the step of hot pressing formation, and because the edge of the tab receives greater pressure, the bonding strength of the active material is higher, and the active material at the edge of the tab is not easily damaged by the expansion of the active material, resulting in lithium precipitation.

[0016] The second object of the application is to provide a preparation method of the laminated battery, which is used for preparing the laminated battery, and comprises the following steps:

[0017] S1, preparing an active material slurry and a functional material;

[0018] S2, coating the active material slurry on both surfaces of the current collector to form a first tab;

[0019] S3, coating the active material slurry on one surface of the current collector, and connecting the functional material to the other surface of the current collector by one of coating, spraying and bonding to form a second tab;

[0020] S4, laminating the first tab, the second tab and the separator, wherein all the first tabs are located between two second tabs, and the laminated assembly is packaged to obtain a packaged battery cell;

[0021] S5, injecting the packaged battery cell into an electrolyte and performing hot pressing formation, two-seal degassing and capacity sorting to obtain a finished battery cell.

[0022] Specifically, when the functional material is connected to the current collector by coating, the step S3 is specifically that the functional material is coated on the edge area of the surface of the current collector and rolled to form a functional layer with edge coating structure; and / or when the functional material is connected to the current collector by spraying, the step S3 is specifically that the functional material is sprayed on the edge area of the surface of the current collector and rolled to form a functional layer with edge coating structure; and / or when the functional material is connected to the current collector by bonding, the step S3 is specifically that the functional material is bonded on the edge area of the surface of the current collector and rolled to form a functional layer with edge coating structure.

[0023] Specifically, when the functional material is connected to the current collector by coating, the step S3 is specifically that the functional material is coated on the edge area of the surface of the current collector and rolled to form a functional layer with edge coating structure; and / or when the functional material is connected to the current collector by spraying, the step S3 is specifically that the functional material is sprayed on the edge area of the surface of the current collector and rolled to form a functional layer with edge coating structure; and / or when the functional material is connected to the current collector by bonding, the step S3 is specifically that the functional material is bonded on the edge area of the surface of the current collector and rolled to form a functional layer with edge coating structure. BRIEF DESCRIPTION OF DRAWINGS

[0024] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0025] Figure 1 FIG. 1 is a schematic view of a structure of a laminated battery according to the present application;

[0026] Figure 2 FIG. 2 is a top view of a second pole piece according to the present application;

[0027] Figure 3 FIG. 3 is a schematic view of another structure of a laminated battery according to the present application.

[0028] In the drawings: 1 - first pole piece; 2 - second pole piece; 21 - functional layer; 211 - chamfer; 22 - active material layer; 23 - current collector; 3 - separator; 100 - electrode assembly. DETAILED DESCRIPTION

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application.

[0030] The present invention will be further described in detail below with reference to the accompanying drawings, but this is not intended to limit the scope of the invention.

[0031] The applicant has discovered that in order to improve the energy density of existing stacked batteries, the electrodes on both sides of the stacked battery are set as single-sided electrodes. A single-sided electrode is an electrode with active material on one side of the current collector and no active material on the other side. The energy density of the battery is improved by removing the coating of the non-reactive active material on one side.

[0032] However, in practical applications, it has been found that the removal of the active material coating on the current collector side causes uneven stress on the single-sided sheet during rolling, resulting in inconsistent stretching tension on both sides and making it prone to warping. To make the electrode sheet more evenly stressed and reduce warping, a new coating needs to be applied to the side of the current collector where the active material coating has been removed to reduce the impact of stretching tension, or the thickness of the current collector needs to be increased to enhance its strength and reduce the impact of stretching tension. However, both of these methods will reduce the energy density of the battery, which is inconsistent with the original intention of setting up a single-sided sheet.

[0033] The applicant has improved the energy density of the battery by optimizing the coating structure to reduce stretching tension and retaining only the parts of the coating that are prone to warping, thereby reducing the volume occupied by the coating.

[0034] Example 1

[0035] The first aspect of the invention, as Figures 1-2 As shown, a stacked battery is provided, including a housing and an electrode assembly 100 housed in the housing. The electrode assembly 100 includes a plurality of first electrodes 1 and two second electrodes 2 stacked along the thickness direction. The first electrodes 1 and the second electrodes 2 together form the electrode assembly 100 for electrochemical reactions, wherein all the first electrodes 1 are disposed between the two second electrodes 2. The first electrodes 1 are disposed in the middle of the electrode assembly 100, while the two second electrodes 2 are respectively disposed on the outermost sides of the electrode assembly 100.

[0036] The second tab 2 includes a current collector 23, an active material layer 22, and a functional layer 21, the active material layer 22 and the functional layer 21 are respectively arranged on both sides of the current collector 23 in the thickness direction, and the functional layer 21 is arranged on the side away from the first tab 1, and the functional layer 21 is arranged in the edge area of the surface of the current collector 23.

[0037] By arranging the functional layer 21 in the edge area of the surface of the current collector 23, the difference in elongation tension on both sides of the current collector 23 during rolling is smaller, the warping of the second tab 2 during rolling is reduced, and because the functional layer 21 is arranged in the edge area of the surface of the current collector 23 corresponding to the position of the second tab 2 that is warped, the thickness of the position where the functional layer 21 is arranged is larger during the heat pressing process, and the pressure during heat pressing is larger, so that the position of the second tab 2 that is warped can be flattened during the heat pressing process.

[0038] The existing battery starts to increase the use of silicon material in order to improve the energy density, and the use of silicon material makes the expansion of the battery larger, and the expansion force is transmitted from the inside to the outside during the expansion process of the battery. The second tab 2 is arranged on both sides of the electrode assembly 100 in the thickness direction, and is arranged on the outermost position in the thickness direction, and in the horizontal direction perpendicular to the thickness direction, the edge position of the second tab 2 is the outermost position. When the battery expands, the expansion force expands from the inside to the outside to the outermost position, and the active material in the outermost position is prone to adhesion failure, the structure of the active material layer 22 is damaged, and even the active material falls off. Therefore, the edge of the second tab 2 is prone to edge lithium precipitation, especially when it is arranged as a single-sided tab, it cannot provide sufficient support for the active material layer 22, and the edge lithium precipitation becomes more serious. By arranging the functional layer 21 in the edge position of the second tab 2, the pressure on the active material layer 22 in the edge position of the second tab 2 during the heat pressing process is larger, the adhesion effect of the active material in the edge position is better, and the strength is higher, which prevents the structure of the active material from being damaged when it is subjected to the expansion force, thereby causing lithium precipitation.

[0039] Embodiment 2

[0040] The difference between this embodiment and embodiment 1 is that the material of the functional layer 21 in this embodiment is one or more of ceramic material, elastic material, active material, and resin material. When the elastic material is used, it is equivalent to providing a elastic pressure device for the stacked battery, which has little loss to the overall thickness of the stacked battery and improves the energy density of the battery. For the ceramic material, because of the high specific heat capacity, it can play a role in heat dissipation, reduce temperature rise, improve the thermal stability of the battery cell, and improve the safety performance of the battery.

[0041] Preferably, the thickness of the functional layer 21 is between 0.5 and 1.5 times the thickness of the active material layer 22, and the thickness of the functional layer 21 and the thickness of the active material layer 22 have a close relationship. When the thickness of the functional layer 21 is too small, the active material layer 22 is prone to lithium precipitation during hot pressing due to insufficient pressure. When the thickness of the functional layer 21 is too large, lithium ions cannot be timely embedded in the active material layer 22 due to excessive pressure on the active material layer 22, causing lithium precipitation.

[0042] Preferably, the functional layer 21 is provided with a chamfer 211, which can reduce stress concentration when the functional layer 21 is used to press the active material, preventing the active material from being affected.

[0043] Preferably, the thickness of the functional layer 21 is 0.1-0.5mm. Within this thickness range, the pressure provided by the functional layer 21 is appropriate and the deformation of the pole piece is not too large.

[0044] Preferably, the outer boundary of the edge region coincides with the surface boundary of the current collector 23, and the distance from the inner boundary of the edge region to the surface boundary of the current collector 23 is 0.1-10mm. The functional layer 21 covers the edge region. The range of the edge region of the functional layer 21 is within the above range, which can satisfy the pressure effect of the functional layer 21 on the active material layer 22, and will not be too wide to cause the energy density of the battery to decrease. Within the above width range, the thickness of the functional layer 21 will decrease when pressed, and will not excessively affect the thickness of the battery.

[0045] Preferably, when the second pole piece 2 is a negative pole piece, the width of the edge region is greater than the width of the overhang region. When the CB value of the battery is too small, the CB value is the ratio of the positive anode capacity to the negative cathode capacity. Due to the capacity imbalance, the negative pole is prone to edge lithium precipitation. Therefore, the width of the negative pole piece is generally greater than that of the positive pole piece to ensure the capacity balance of the positive and negative poles. The area of the negative pole piece that exceeds the width of the positive pole piece is the overhang region. The overhang region may cause lithium precipitation due to the accumulation of lithium ions after multiple cycles. The present application sets the width of the edge region coated by the functional layer 21 to be greater than the width of the overhang region, so that the edge region covers the overhang region, providing pressure to the negative active material of the overhang region to improve compaction and prevent excessive accumulation of lithium ions in the overhang region, thereby preventing lithium precipitation.

[0046] As Figure 3As shown, preferably, the thickness of the functional layer 21 gradually increases from the inner boundary of the edge region to the inside of the functional layer 21, and by such arrangement, when the functional layer 21 is pressed against the active material, a transition is provided between the active material at the pressed position and the active material at the non-pressed position, preventing the connection position between the active material at the pressed position and the active material at the non-pressed position from being damaged due to the sudden change in compaction, and further preventing the active material layer 22 from being damaged due to the different expansion speeds of the active material caused by the different binding speeds of lithium ions in the battery, and further preventing lithium precipitation.

[0047] Embodiment 3

[0048] In a second aspect, the present application provides a preparation method of the laminated battery, for preparing the laminated battery as described above, comprising:

[0049] S1, preparing an active material slurry and a functional material;

[0050] S2, coating the active material slurry on both sides of the current collector 23 to form the first electrode sheet 1;

[0051] S3, coating the active material slurry on one side of the current collector 23, and connecting the functional material to the other side of the current collector 23 by one of coating, spraying and bonding to form the second electrode sheet 2;

[0052] S4, laminating the first electrode sheet 1, the second electrode sheet 2 and the separator 3, wherein all the first electrode sheets 1 are located between two second electrode sheets 2, and packaging to obtain a packaged battery cell;

[0053] S5, injecting the packaged battery cell into an electrolyte and performing steps such as hot pressing, formation, double-sealing degassing and capacity sorting to obtain a finished battery cell.

[0054] Preferably, when the functional material is connected to the current collector by coating, step S3 specifically comprises fully coating the functional material on the surface of the current collector 23 and rolling, and then removing the functional material in the middle of the current collector 23 to form a functional layer 21 with an edge coating structure; and / or when the functional material is connected to the current collector by spraying, step S3 specifically comprises fully spraying the functional material on the surface of the current collector 23 and rolling, and then removing the functional material in the middle of the current collector 23 to form a functional layer 21 with an edge coating structure; and / or when the functional material is connected to the current collector by bonding, step S3 specifically comprises fully bonding the functional material on the surface of the current collector 23 and rolling, and then removing the functional material in the middle of the current collector 23 to form a functional layer 21 with an edge coating structure.

[0055] In order to form the functional layer 21 with a thickness difference, the functional material in the middle of the current collector 23 is removed, and the position with the functional material has a larger thickness. When the battery is subjected to thermal compression formation, the entire surface of the electrode tab is simultaneously pressed down, and the position provided with the functional layer 21 can provide a larger pressure due to the larger thickness.

[0056] The selection of the functional material includes but is not limited to ceramic slurry, low-viscosity residual slurry, volatile organic slurry, or active material slurry. When the active material slurry is used, the first electrode tab 1 can be processed to obtain the second electrode tab 2 to save the production steps and improve the production efficiency. The removal area of the functional material has certain limitations, and the coating material needs to be at least reserved at the four corners and the edge position. At the same time, the boundary of the removal area needs to be a smooth boundary, such as an ellipse or a chamfered rectangle. The removal methods include but are not limited to one or more of the following methods: using a dust-free paper or a dust-free cloth to dip alcohol or other solvents for wiping, laser ablation, heating and volatilization, or tearing.

[0057] The functional layer 21 with an edge coating structure is obtained by removing the slurry in the middle of the current collector 23. The feature of this technology is that it has the advantage of uniform compaction. Since both sides of the current collector 23 are fully coated during rolling, the stress on the current collector 23 is uniform. During rolling, the compaction of the functional layer 21 and the active material layer 22 can be ensured to be uniform. Since the compaction is uniform, a higher compaction density can be achieved, the rolling thickness of the second electrode tab 2 can be guaranteed, the particle compaction effect is consistent with that of the first electrode tab 1, and the loss of thickness and energy density caused by over-compaction of the second electrode tab 2 is avoided. At the same time, since the stress on both sides of the current collector 23 is uniform during rolling, the stress concentration is small, the foil is not easy to wrinkle, the material area is not easy to fall off, and a thinner current collector 23 can be selected for the current collector 23, thereby improving the energy density of the battery.

[0058] Embodiment 4

[0059] Different from embodiment 2, when the functional material is connected to the current collector by coating, step S3 is specifically that the functional material is coated on the edge area of the surface of the current collector 23 and is rolled to form the functional layer 21 with an edge coating structure; and / or when the functional material is connected to the current collector by spraying, step S3 is specifically that the functional material is sprayed on the edge area of the surface of the current collector 23 and is rolled to form the functional layer 21 with an edge coating structure; and / or when the functional material is connected to the current collector by adhesion, step S3 is specifically that the functional material is adhered on the edge area of the surface of the current collector 23 and is rolled to form the functional layer 21 with an edge coating structure.

[0060] The functional material is coated on the edge area of the surface of the current collector 23, including but not limited to local coating, local sticking, local spraying, local printing, etc., to form a functional layer 21 with an edge coating structure at the edge and corner positions of the pole piece. The selection of the functional material can be rigid or elastic material.

[0061] This way can save coating material in the early stage and reduce cost. Since the functional material is removed once, the coating material can be saved. The selection of the functional material is flexible, such as elastic material, which is equivalent to giving the battery a elastic pressure device, and the loss of the overall thickness of the battery is small, so that the stress range of the four corners is increased. For ceramic materials, due to high specific heat capacity, heat can be exported, temperature rise can be reduced, battery thermal stability can be improved, and battery safety performance can be improved. For the pasted coating, the operation is simple and the process cost is low.

[0062] Embodiment 5

[0063] Step 1: Stir the required main material, conductive agent and binder in a certain proportion to form a uniform and dispersed active material slurry and ceramic slurry;

[0064] Step 2: The specific operation is to uniformly coat the active material slurry obtained in step 1 on one side of the current collector 23 to obtain a single-sided pole piece with a single-sided active material layer 22, and the thickness of the active material layer 22 is 0.2 mm;

[0065] Step 3: The specific operation is to uniformly coat the active material slurry obtained in step 1 on the other side of the single-sided pole piece obtained in step 2, and roll to a certain thickness to obtain a first pole piece 1 with a double-sided active material layer 22;

[0066] Step 4: The specific operation is to uniformly spray the ceramic slurry on the other side of the single-sided pole piece obtained in step 2, and roll to a certain thickness to form a double-sided pole piece with an active material layer 22 and a ceramic coating, and the thickness of the ceramic coating is 0.2 mm;

[0067] Step 5: The specific operation is to cut the first pole piece 1 and the double-sided pole piece obtained in steps 3 and 4 to the required size;

[0068] Step 6: The specific operation is to remove the middle part of the ceramic coating of the double-sided pole piece obtained in step 5 by tearing off the adhesive tape, and only the edge and corner coating is retained to obtain a second pole piece 2;

[0069] Step 7: The specific operation is to assemble, fold, heat press and top seal weld the second pole piece 2 obtained in step 6, the first pole piece 1 obtained in step 5, the separator 3 and the other polarity pole piece to obtain a packaged battery;

[0070] The specific operation of step 8 is to obtain the finished battery cell through the steps of liquid injection, aging, thermal compression formation, two-seal degassing, capacity sorting, etc. of the packaged battery cell obtained in step 7.

[0071] Example 6

[0072] Different from example 5: the thickness of the ceramic coating is 0.3mm.

[0073] Example 7

[0074] Different from example 5: the thickness of the ceramic coating is 0.1mm.

[0075] Example 8

[0076] Different from example 5: the specific operation of step 4 is to uniformly spray the active material slurry on the other side of the single-sided electrode sheet obtained in step 2, roll to a certain thickness, form a double-sided electrode sheet, and the thickness of the active material slurry is 0.2mm.

[0077] The specific operation of step 6 is to remove the middle part of the active material layer 22 of the double-sided electrode sheet obtained in step 5 by laser ablation removal method, only the edge and corner coating materials are reserved, and the second electrode sheet 2 is obtained.

[0078] Example 9

[0079] Different from example 5: the specific operation of step 4 is to paste the PE film on the other side of the single-sided electrode sheet obtained in step 2, roll to a certain thickness, form a double-sided electrode sheet, and the thickness of the PE film is 0.2mm.

[0080] The specific operation of step 6 is to remove the middle part of the PE film of the double-sided electrode sheet obtained in step 5 by mechanical scraping, only the edge and corner PE film is reserved, and the second electrode sheet 2 is obtained.

[0081] Example 10

[0082] Step 1: The main material, conductive agent and binder required are stirred into uniform and dispersed active material slurry and ceramic slurry according to a certain proportion;

[0083] The specific operation of step 2 is to uniformly coat the active material slurry obtained in step 1 on one side of the current collector 23 to obtain a single-sided electrode sheet with a single-sided active material layer 22, and the thickness of the active material layer 22 is 0.2mm.

[0084] The specific operation of step 3 is to uniformly coat the active material slurry obtained in step 1 on the other side of the single-sided electrode sheet obtained in step 2, roll to a certain thickness, and obtain a first electrode sheet 1 with a double-sided active material layer 22.

[0085] The specific operation of step 4 is to locally coat the ceramic slurry on the other side of the single-sided electrode plate obtained in step 2, roll to a certain thickness, form a second electrode plate 2 with an active material layer 22 and a ceramic coating layer, and the thickness of the ceramic coating layer is 0.2mm;

[0086] The specific operation of step 5 is to cut the first electrode plate 1 and the second electrode plate 2 obtained in steps 3 and 4 to the required size;

[0087] The specific operation of step 6 is to assemble, fold, heat press and top seal weld the second electrode plate 2, the first electrode plate 1 and the separator 3, and the other polarity electrode plate obtained in step 5, to obtain a packaged battery cell;

[0088] The specific operation of step 7 is to obtain a finished battery cell by liquid injection, aging, heat pressing, two-seal degassing, capacity sorting and other steps of the packaged battery cell obtained in step 6.

[0089] Example 11

[0090] Different from example 10, the specific operation of step 4 is to locally coat the elastic slurry on the other side of the single-sided electrode plate obtained in step 2, roll to a certain thickness, form a second electrode plate 2 with an active material layer 22 and an elastic coating layer, and the thickness of the elastic coating layer is 0.2mm.

[0091] Example 12

[0092] Different from example 11, the specific operation of step 4 is to locally coat the active material slurry on the other side of the single-sided electrode plate obtained in step 2, roll to a certain thickness, form a second electrode plate 2, and the thickness of the active material slurry is 0.2mm.

[0093] Comparative example 1

[0094] Different from example 5, the thickness of the ceramic coating layer is 0.02mm.

[0095] Comparative example 2

[0096] Different from example 5, the thickness of the ceramic coating layer is 1mm.

[0097] Comparative example 3

[0098] Step 1: Stir the required main material, conductive agent and binder in a certain proportion to form a uniformly dispersed active material slurry

[0099] The specific operation of step 2 is to uniformly coat the active material slurry obtained in step 1 on one side of the current collector to obtain a single-sided electrode plate with a single-sided active material layer, and the thickness of the active material layer is 0.2mm;

[0100] The specific operation of step 3 is to uniformly coat the active material slurry obtained in step 1 on the other side of the single-sided electrode plate obtained in step 2, roll to a certain thickness, and obtain a first electrode plate with a double-sided active material layer;

[0101] The specific operation of step 4 is to assemble, fold, hot-press, and top-seal weld the single-sided electrode plate obtained in step 1, the first electrode plate obtained in step 1, the separator, and the electrode plate of the other polarity, to obtain a packaged battery cell;

[0102] The specific operation of step 5 is to obtain a finished battery cell by liquid injection, aging, hot-pressing, two-seal degassing, and capacity sorting of the packaged battery cell obtained in step 4.

[0103] Performance test method: after 300 cycles at 3C rate, disassemble the interface, determine the degree of lithium precipitation, and divide the degree of lithium precipitation into no lithium precipitation, slight lithium precipitation, and severe lithium precipitation.

[0104]

[0105]

[0106] As can be seen from the comparison of Examples 4-6 and Comparative Examples 1 and 2, when the thickness of the functional layer is within the range of the present application, the laminated battery of the present application is less likely to precipitate lithium. When the thickness of the functional layer is too small, it cannot provide sufficient pressure during hot-pressing to make the adhesion of the active material at the edge insufficient, and when the thickness of the functional layer is too large, the pressure on the active material is too large, which causes the structure of the active material layer to be destroyed, resulting in lithium precipitation.

[0107] As can be seen from the comparison of Example 4 and Comparative Example 3, the functional layer arrangement of the present application can reduce lithium precipitation at the edge of the single-sided electrode plate.

[0108] As can be seen from the comparison of Example 4 and Examples 8 and 9, when the edge coating structure of the functional layer of the present application is formed, the lithium precipitation of the laminated battery is improved.

[0109] The above description shows and describes several preferred embodiments of the present application, but as previously stated, the present application is not limited to the forms disclosed herein, should not be considered as excluding other embodiments, and can be used in various other combinations, modifications, and environments, and can be modified within the scope of the inventive concept disclosed herein, by the above teachings or related art or knowledge. Any modification and change made by those skilled in the art without departing from the spirit and scope of the present application shall be within the protection scope of the appended claims of the present application.

Claims

1. A stacked battery comprising a housing and an electrode assembly (100) housed in the housing, characterized by: The electrode assembly (100) comprises a plurality of first electrode sheets (1) and two second electrode sheets (2) stacked in the thickness direction, wherein all the first electrode sheets (1) are arranged between the two second electrode sheets (2); The second electrode sheet (2) comprises a current collector (23), an active material layer (22) and a functional layer (21), the active material layer (22) and the functional layer (21) are arranged on both sides of the current collector (23) in the thickness direction, wherein the functional layer (21) is arranged on the side away from the first electrode sheet (1), the functional layer (21) is arranged only in the edge region of the surface of the current collector (23), and the current collector (23) on the side where the functional layer (21) is arranged is only provided with the functional layer (21).

2. The stacked battery of claim 1, wherein: The material of the functional layer (21) is one or more of ceramic material, elastic material, active material and resin material.

3. The stacked battery of claim 1, wherein: The thickness of the functional layer (21) is between 0.5 and 1.5 times the thickness of the active material layer (22).

4. The stacked battery of claim 1, wherein: The functional layer (21) is provided with a chamfer (211).

5. The stacked battery of claim 1, wherein: The thickness of the functional layer (21) is 0.1-0.5mm.

6. The stacked battery of claim 1, wherein: The outer boundary of the edge region coincides with the surface boundary of the current collector (23), the distance from the inner boundary of the edge region to the surface boundary of the current collector (23) is 0.1-10mm, and the functional layer (21) fills the edge region.

7. The stacked battery of claim 1, wherein: The thickness of the functional layer (21) gradually increases from the inner boundary of the edge region to the inside of the functional layer (21).

8. A method for producing a stacked battery, for producing the stacked battery according to any one of claims 1 to 7, characterized by, Comprise: S1, preparing active material slurry and functional material; S2, coating the active material slurry on both sides of the current collector (23) to form the first electrode sheet (1); S3, coating the active material slurry on one side of the current collector (23), and connecting the functional material to the other side of the current collector (23) by one of coating, spraying and bonding to form the second electrode sheet (2); S4, laminating the first electrode sheet (1), the second electrode sheet (2) and the separator (3), wherein all the first electrode sheets (1) are located between the two second electrode sheets (2), and the packaged battery is obtained by packaging; S5, injecting the packaged battery into electrolyte and performing steps such as heat pressing, formation, double-sealing degassing and capacity sorting to obtain the finished battery.

9. The method of claim 8, wherein: When the functional material is connected to the current collector by coating, the step S3 specifically comprises fully coating the functional material on the surface of the current collector (23) and rolling, and then removing the functional material in the middle of the current collector (23) to form a functional layer (21) with an edge coating structure.

10. The method of claim 8, wherein: When the functional material is connected to the current collector by spraying, the step S3 specifically comprises fully spraying the functional material on the surface of the current collector (23) and rolling, and then removing the functional material in the middle of the current collector (23) to form a functional layer (21) with an edge coating structure.

11. The method of claim 8, wherein: When the functional material is connected to the current collector by adhesion, the step S3 is specifically to comprehensively adhere the functional material on the surface of the current collector (23) and roll, and then remove the functional material in the middle of the current collector (23) to form a functional layer (21) with an edge coating structure.

12. The method of claim 8, wherein: When the functional material is connected to the current collector by coating, the step S3 is specifically to coat the functional material on the edge area of the surface of the current collector (23) and roll to form a functional layer (21) with an edge coating structure.

13. The method of claim 8, wherein: When the functional material is connected to the current collector by spraying, the step S3 is specifically to spray the functional material on the edge area of the surface of the current collector (23) and roll to form a functional layer (21) with an edge coating structure.

14. The method of claim 8, wherein: When the functional material is connected to the current collector by adhesion, the step S3 is specifically to adhere the functional material on the edge area of the surface of the current collector (23) and roll to form a functional layer (21) with an edge coating structure.

Images