Battery cell hot-pressing shaping method, battery monomer and battery cell hot-pressing shaping device

Abstract

The invention belongs to the technical field of lithium battery manufacturing, and particularly relates to a battery cell hot-pressing shaping method, a battery monomer and a battery cell hot-pressing shaping device. The battery cell hot-pressing shaping method comprises the following steps: electrically connecting two positive electrode tabs and / or two negative electrode tabs of a bare battery cell structure to a heating power supply, so as to electrify and heat the bare battery cell structure; and clamping and shaping the heated bare cell structure to fix the shape contour of the bare cell structure. The invention aims to solve the problems that the energy utilization rate is low and the heating time is long when a naked battery cell structure is indirectly heated through a hot pressing plate, and the diaphragm is easy to close due to the fact that the surface temperature of the hot pressing plate abutting against the naked battery cell structure is high and the time of the hot pressing plate abutting against the surface of the naked battery cell structure is long.

Description

Technical Field

[0001] The present application belongs to the technical field of lithium battery manufacturing, and in particular relates to a method for hot pressing and shaping a battery cell, a battery cell, and a hot pressing and shaping device for a battery cell. Background Art

[0002] The wound cell includes a bare cell structure, which is a component in which the positive electrode sheet, the negative electrode sheet and the separator are stacked in a predetermined order and wound. After the wound bare cell structure is cut, the bare cell structure is fluffy, and the positive electrode sheet and the negative electrode sheet are easy to slip and difficult to assemble. Therefore, the wound bare cell structure usually needs to be hot-pressed or cold-pressed to shape the bare cell structure into a fixed shape.

[0003] At present, the application rate of hot pressing shaping process in the industry is higher than that of cold pressing shaping process. The hot pressing device of the battery cell in the related technology includes two sets of hot pressing components arranged oppositely, and the hot pressing surfaces of the two sets of hot pressing components are arranged oppositely. The hot pressing components include hot pressing plates, and a number of heating tubes are connected to the sides of the hot pressing plates. The hot pressing plates are heated by the heating tubes. When the two sets of hot pressing plates move towards each other to clamp the bare battery cell structure, the hot pressing plates heated by the heating tubes complete the hot pressing process for the bare battery cell structure.

[0004] In summary, the battery cell hot pressing device of the related technology heats the bare battery cell structure indirectly through the hot pressing plate, which has low energy utilization and long heating time. In addition, the surface temperature of the hot pressing plate abutting against the bare battery cell structure is high, and the hot pressing plate abuts against the surface of the bare battery cell structure for a long time, which can easily lead to diaphragm closure. Summary of the invention

[0005] The purpose of the present application is to provide a battery cell hot pressing and shaping method, a battery cell and a battery cell hot pressing and shaping device, aiming to solve the problem of indirect heating of the bare battery cell structure by a hot pressing plate, low energy utilization rate, long heating time, high surface temperature of the hot pressing plate abutting the bare battery cell structure, and long time of the hot pressing plate abutting the surface of the bare battery cell structure, which easily leads to diaphragm closure.

[0006] To achieve the above purpose, the technical solution adopted in the present application is: a method for hot pressing and shaping a battery cell, which is used to hot press and shape a bare battery cell structure, and the method for hot pressing and shaping a battery cell comprises the following steps:

[0007] Electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs of the bare cell structure to a heating power source to electrically heat the bare cell structure;

[0008] The heated bare cell structure is clamped and pressed to fix the shape of the bare cell structure.

[0009] The battery cell hot pressing shaping method provided in the embodiment of the present application heats the bare battery cell structure by directly energizing the pole piece in the bare battery cell structure so that the pole piece generates ohmic heat through overcurrent to heat the bare battery cell structure. The inner and outer rings of the bare battery cell structure can be quickly and synchronously heated, with short heating time, uniform heating, good heating temperature distribution consistency, and significantly improved energy utilization. In addition, the time that the pressing plate abuts against the surface of the bare battery cell structure is shorter, thereby reducing the probability of the surface diaphragm of the bare battery cell structure having a closed diaphragm, thereby improving the product quality of the lithium battery.

[0010] In some embodiments of the present application, before performing the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs of the bare cell structure to a heating power source to electrically heat the bare cell structure", the steps of: stacking and composite-molding the positive electrode sheet, the separator and the negative electrode sheet into a cell material roll, and winding the cell material roll to form a bare cell structure are performed. Rapidly winding to form a fluffy bare cell structure completes the preparation work for hot pressing and improves work efficiency.

[0011] In some embodiments of the present application, during the process of performing the step of "electrically connecting two of the positive pole tabs and / or two of the negative pole tabs of the bare cell structure to a heating power source": the two positive pole tabs are the two positive pole tabs that are farthest apart when the bare cell structure is unfolded into a cell material roll; and / or, the two negative pole tabs are the two negative pole tabs that are farthest apart when the bare cell structure is unfolded into a cell material roll. In this way, the ohmic resistance that can generate ohmic heat when the positive and / or negative electrode sheets are overcurrented is the largest, so that the heat generation efficiency of the positive and / or negative electrode sheets to generate ohmic heat when the positive and / or negative electrode sheets are overcurrented is the highest, and the energy utilization rate is high.

[0012] In some embodiments of the present application, before executing the step of "winding the battery core material to form a bare battery core structure", two positive pole tabs and / or two negative pole tabs that need to be connected to the heating power supply are die-cut to reserve the pole tab electrical connection ends. Since the pole tab electrical connection ends are extended in length based on the length of the pole tabs, when the pole tab electrical connection ends are electrically connected to the positive and negative poles of the heating power supply, they will not be interfered by the other pole tabs, thereby completing the electrical connection more conveniently and quickly.

[0013] In some embodiments of the present application, when performing the step of "die-cutting two positive pole tabs and / or two negative pole tabs that need to be connected to a heating power source to reserve the pole tab power connection ends", each positive pole tab and each negative pole tab are die-cut so that the contour shapes of each positive pole tab and each negative pole tab after die-cutting are consistent. Positive pole tabs and negative pole tabs with consistent shapes can be easily sorted separately, thereby improving the efficiency of sorting the pole tabs.

[0014] In some embodiments of the present application, during the process of performing the step of "winding the battery core material to form a bare battery core structure": the positive pole ears are aligned with each other, and there is a gap between the surfaces of two adjacent positive pole ears; and the negative pole ears are aligned with each other, and there is a gap between the surfaces of two adjacent negative pole ears. The alignment of the positive pole ears and the alignment of the negative pole ears are conducive to quickly completing the electrical connection of each positive pole ear to the positive electrode collector of the battery cell in the subsequent assembly process, and to quickly completing the electrical connection of each negative pole ear to the negative electrode collector of the battery cell, thereby improving the assembly efficiency. In addition, there is a gap between the surfaces of two adjacent positive pole ears and between the surfaces of two adjacent negative pole ears, that is, the two adjacent positive pole ears and the two adjacent negative pole ears are insulated from each other. In this way, when the two positive electrode tabs and / or the two negative electrode tabs are electrically connected to the positive pole and the negative pole of the heating power supply and current flows, the current will inevitably flow through the conductor between the two tabs, so that the positive electrode sheet and / or the negative electrode sheet generates ohmic heat to efficiently heat the entire bare battery cell structure.

[0015] In some embodiments of the present application, after the step of "clamping and shaping the heated bare cell structure" is completed, the electrical end of the tab is cut. Cutting off the electrical end of the tab makes the lengths of all positive tabs completely consistent, and the lengths of all negative tabs completely consistent, which is conducive to quickly completing the electrical connection of each positive tab to the current collector of the positive electrode of the battery cell, and quickly completing the electrical connection of each negative tab to the current collector of the negative electrode of the battery cell, thereby improving assembly efficiency.

[0016] In some embodiments of the present application, during the step of "clamping and pressing the heated bare cell structure", the bare cell structure is clamped and pressed by clamping and pressing from top to bottom. At this time, the first pressing plate and the second pressing plate used for clamping and pressing are arranged vertically opposite to each other, and the fluffy bare cell structure can be directly transferred and placed on the first pressing plate, which can simplify the transfer process of the bare cell structure, save the transfer time, and improve the work efficiency.

[0017] In some embodiments of the present application, when performing the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs to a heating power source to electrically heat the bare cell structure", the heating time is 5s-10s. According to Ohm's law, ohmic heat Q = I 2 *R*t, achieving efficient heating of the bare cell structure, and the heating time is 5s-10s to heat the bare cell structure to the appropriate hot pressing temperature.

[0018] In some embodiments of the present application, when performing the step of "clamping and pressing the heated bare cell structure to fix the shape and contour of the bare cell structure", the time for clamping and pressing the bare cell structure is 5s-10s. The time for clamping and pressing the bare cell structure should not be too long. By selecting a suitable pressure to clamp the bare cell structure for 5s-10s, a bare cell structure with a fixed shape and contour can be obtained, thereby reducing the situation where the diaphragm is closed due to too long clamping time.

[0019] In some embodiments of the present application, when performing the step of "clamping and pressing the heated bare cell structure to fix the shape and contour of the bare cell structure", the surface pressure of the clamping and pressing bare cell structure is greater than or equal to 5MPa. The pressure of clamping and pressing the bare cell structure should not be too large. By selecting a suitable pressure of 5MPa to clamp the bare cell structure, a bare cell structure with a fixed shape and contour can be obtained, thereby reducing the situation of diaphragm closure caused by excessive pressure.

[0020] In some embodiments of the present application, the interval time between the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs to a heating power source for electrical heating" and the step of "clamping and shaping the heated bare cell structure to fix the shape profile of the bare cell structure" is 0-10s. The heated bare cell structure is left to stand so that the overall temperature of the bare cell structure reaches the ideal temperature value for performing step S50. Since the temperature of the bare cell structure 40 is appropriate when performing step S50, the probability of diaphragm closure caused by the high temperature of the bare cell structure is effectively reduced, and the product quality of the hot-pressed bare cell structure is effectively improved.

[0021] According to another aspect of the present application, a battery cell is provided, wherein the battery cell comprises a bare battery cell structure that is hot-pressed and shaped using the battery cell hot-pressing shaping method as described above.

[0022] According to another aspect of the present application, a battery cell hot pressing and shaping device is provided. Among them, the battery cell hot pressing and shaping device includes a shaping station, and the shaping station is provided with a driving mechanism, a first pressing plate, a second pressing plate and a heating power supply. The first pressing plate and the second pressing plate are arranged opposite to each other to clamp the bare battery cell structure, and the driving mechanism is connected to the first pressing plate and / or the driving mechanism is connected to the second pressing plate. The heating power supply is used to energize and heat the bare battery cell structure. At this time, the first pressing plate and the second pressing plate used for clamping and shaping are arranged opposite to each other up and down, and the bare battery cell structure in a fluffy state can be directly transferred and placed on the first pressing plate, which can simplify the transfer process of conveying the bare battery cell structure, save conveying time, and improve work efficiency. By adopting a method of directly energizing the pole piece in the bare battery cell structure so that the pole piece overcurrent generates ohmic heat to heat the bare battery cell structure, the inner circle and the outer circle of the bare battery cell structure can be quickly and synchronously heated, the heating time is short, the heating is uniform, the heating temperature distribution is consistent, and the energy utilization rate is significantly improved. In addition, the time that the pressing plate abuts against the surface of the bare cell structure is shorter, thereby reducing the probability of diaphragm closure occurring on the surface diaphragm of the bare cell structure and improving the product quality of the lithium battery.

[0023] In some embodiments of the present application, the battery cell hot pressing shaping device further includes a winding station, which is located upstream of the shaping station and is used to wind the battery cell material to form a bare battery cell structure. The bare battery cell structure is quickly wound to form a fluffy state, which completes the preparation work for hot pressing and improves work efficiency.

[0024] In some embodiments of the present application, the battery cell hot pressing and shaping device further includes a composite molding station and a die-cutting station, the die-cutting station is located upstream of the winding station, the composite molding station is located upstream of the die-cutting station, the composite molding station is used to laminate and compositely mold the positive electrode sheet, the diaphragm and the negative electrode sheet into a battery cell material roll, and the die-cutting station is used to die-cut the positive electrode tab and / or the negative electrode tab on the battery cell material roll, and die-cut to obtain the tab electrical connection end for electrical connection with the heating power supply. Since the length of the tab electrical connection end is extended on the basis of the length of the tab, the tab electrical connection end will not be interfered with by the other tabs when electrically connected to the positive and negative electrodes of the heating power supply, thereby completing the electrical connection more conveniently and quickly.

[0025] In some embodiments of the present application, the shaping station is further provided with a cutting mechanism, and after the first pressing plate and the second pressing plate clamp the bare cell structure, the cutting mechanism is used to cut the end of the pole tab for connecting to electricity. Cutting off the end of the pole tab for connecting to electricity makes the lengths of all positive pole tabs completely consistent, and the lengths of all negative pole tabs completely consistent, which is conducive to quickly completing the electrical connection of each positive pole tab to the current collector of the positive electrode of the battery cell, and quickly completing the electrical connection of each negative pole tab to the current collector of the negative electrode of the battery cell, thereby improving assembly efficiency.

[0026] The embodiments of the present application have the following beneficial effects:

[0027] By directly energizing the pole piece in the bare cell structure so that the pole piece overcurrent generates ohmic heat to heat the bare cell structure, the inner and outer rings of the bare cell structure can be quickly and synchronously heated, with short heating time, uniform heating, good heating temperature distribution consistency, and significantly improved energy utilization. In addition, the time that the pressure plate abuts the surface of the bare cell structure is shorter, thereby reducing the probability of diaphragm closure in the surface diaphragm of the bare cell structure and improving the product quality of lithium batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 A schematic diagram of the process of the hot pressing and shaping method of a battery cell according to an embodiment of the present application;

[0030] Figure 2 It is a schematic structural diagram of a bare cell structure, a first pressing plate, a second pressing plate and a heating power supply in a cell hot pressing shaping method according to an embodiment of the present application;

[0031] Figure 3 for Figure 2 A cross-sectional view of

[0032] Figure 4 A schematic diagram of a bare cell structure to be hot-pressed and shaped in a method for hot-pressing and shaping a cell according to an embodiment of the present application;

[0033] Figure 5 A schematic diagram of the structure of a negative electrode sheet used in a bare cell structure to be hot-pressed and shaped in the hot-pressing and shaping method of a cell in an embodiment of the present application;

[0034] Figure 6 A schematic diagram of the structure of a positive electrode sheet used in a bare cell structure to be hot-pressed and shaped in the hot-pressing and shaping method of a cell in an embodiment of the present application;

[0035] Figure 7 for Figure 5 A schematic diagram of the structure of a negative electrode tab connected to the power end;

[0036] Figure 8 It is a schematic diagram of the arrangement of the composite molding station, die cutting station, winding station and shaping station of the battery cell hot pressing shaping device according to an embodiment of the present application;

[0037] Fig. 9 This is a schematic diagram of the exploded structure of a battery cell according to an embodiment of the present application.

[0038] Among them, the reference numerals in the figure are:

[0039] 10. positive electrode sheet; 11. positive electrode tab; 12. first gap;

[0040] 20. Negative electrode sheet; 21. Negative electrode tab; 22. Negative electrode tab electrical connection end; 23. Second gap;

[0041] 30. diaphragm; 31. first diaphragm; 32. second diaphragm;

[0042] 40. Bare battery cell structure;

[0043] 50. Heating power supply; 51. Positive electrode of power supply; 52. Negative electrode of power supply;

[0044] 61. first pressing plate; 62. second pressing plate;

[0045] 71. Composite molding station; 72. Die cutting station; 73. Winding station; 74. Shaping station;

[0046] 100, battery cell; 101, end cover; 102, electrode terminal; 103, housing; 104, current collector; 105, liquid capsule. DETAILED DESCRIPTION

[0047] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0048] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0049] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the feature. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0050] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0051] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0052] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0053] At present, from the perspective of market development, the application of power batteries, especially lithium batteries, is becoming more and more extensive. Lithium batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as police equipment, military equipment and aerospace and other fields. With the continuous expansion of the application field of lithium batteries, its market demand is also constantly expanding.

[0054] The preparation of lithium batteries requires the process of electrode compounding, winding, shaping, etc. to prepare lithium battery cells, and then assemble the battery cells into lithium batteries. The shaping process of lithium battery preparation is to shape the bare cell structure that is wound but fluffy to fix the shape of the bare cell structure, thereby solving the problem that the positive and negative electrodes in the fluffy bare cell structure are easy to slip and difficult to assemble.

[0055] The composite process refers to the process of rolling and composite the positive electrode sheet, separator and negative electrode sheet into a cell material roll for winding a bare cell structure.

[0056] The winding process refers to winding the composite formed battery cell material roll to form a bare battery cell structure semi-finished product. At this time, the bare battery cell structure semi-finished product formed by winding is in a fluffy state, the shape contour of the bare battery cell structure is not fixed, and the positive and negative electrodes in the bare battery cell structure are easy to slip and difficult to assemble.

[0057] The shaping process refers to the use of hot pressing or cold pressing technology to clamp and press the fluffy bare cell structure to fix the shape contour of the bare cell structure, thereby solving the problem that the positive and negative electrodes in the fluffy bare cell structure are easy to slip and difficult to assemble, which is beneficial to improving the assembly accuracy and efficiency of the subsequent assembly to form battery cells.

[0058] In the related art, the shaping process usually adopts hot pressing shaping process or cold pressing shaping process, among which the application rate of hot pressing shaping process in the industry is higher than that of cold pressing shaping process. At present, the hot pressing shaping process is generally: heating the fluffy bare cell structure through a preheating tunnel furnace, and then transferring the heated bare cell structure to a pressing plate for clamping and shaping; or, heating the pressing plate to a high temperature, transferring heat to the fluffy bare cell structure through the pressing plate to heat the bare cell structure, and then applying pressure on the pressing plate to clamp the heated bare cell structure to achieve hot pressing shaping.

[0059] However, whether the fluffy bare cell structure is heated by a preheating tunnel furnace or by a high-temperature pressing plate, the heating time is relatively long, the energy utilization rate is low, and the temperature distribution of the inner and outer circles of the bare cell structure is uneven. Moreover, when the fluffy bare cell structure is heated by a high-temperature pressing plate and hot-pressed, the surface temperature of the hot pressing plate abutting against the surface of the bare cell structure is high, and the hot pressing plate abuts against the surface of the bare cell structure for a long time, which can easily cause the surface diaphragm of the bare cell structure to have diaphragm closure, thereby affecting the wetting effect of the electrolyte on the electrode and affecting the product quality of the lithium battery.

[0060] Diaphragm closed-cell means that a diaphragm is used to insulate the positive electrode and the negative electrode. The diaphragm has micropores that allow the electrolyte to pass through, so that the electrolyte can infiltrate the positive and negative electrode sheets, so that the positive and negative electrode sheets and the electrolyte can undergo normal electrochemical reactions to generate electricity. Therefore, it is necessary to ensure that the diaphragm's micropores cannot be closed. If the diaphragm's micropores are closed, especially if part or all of the micropores of the outer ring diaphragm of the bare cell structure are closed, it will seriously affect the quality of the bare cell structure product. As the name suggests, diaphragm closed-cell means that the diaphragm's micropores are closed and the electrolyte cannot pass through, which is an undesirable phenomenon that affects product quality.

[0061] Based on the above considerations, in order to solve the problems in the current technology that the heating time of the bare cell structure is long, the energy utilization rate is low, the temperature distribution of the inner and outer rings of the bare cell structure is uneven, and it is easy to cause the diaphragm to be closed, the embodiment of the present application designs a cell hot pressing and shaping method for hot pressing and shaping the bare cell structure so that the shape contour of the bare cell structure in a fluffy state is fixed. The cell hot pressing and shaping method provided in the embodiment of the present application achieves rapid heating of the bare cell structure by directly energizing the pole piece in the bare cell structure so that the pole piece overcurrent generates ohmic heat to heat the bare cell structure. In addition, the ohmic heat generated by the overcurrent of the pole piece can quickly and synchronously heat the inner and outer rings of the bare cell structure, with a short heating time, uniform heating, good consistency of heating temperature distribution, and significantly improved energy utilization. In this way, during clamping and shaping, the clamping time of the pressing plate on the bare cell structure can be shortened compared to the clamping time of the current technology, that is, the time that the pressing plate abuts against the surface of the bare cell structure is shorter, thereby reducing the probability of diaphragm closure occurring in the surface diaphragm of the bare cell structure and improving the product quality of the lithium battery.

[0062] In addition, the embodiments of the present application also provide a battery cell hot pressing and shaping device for implementing the battery cell hot pressing and shaping method designed in the embodiments of the present application.

[0063] The battery cell hot pressing shaping method and the corresponding battery cell hot pressing shaping device designed in the embodiment of the present application are suitable for the preparation and production of wound lithium batteries, wherein the wound lithium batteries include but are not limited to wound square lithium batteries and wound cylindrical lithium batteries. In addition, the bare battery cell structure hot-pressed by the battery cell hot pressing shaping method disclosed in the embodiment of the present application is used to prepare and produce battery cells, and the battery cells are used to prepare and produce lithium batteries. The prepared lithium batteries can be used for but not limited to mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, for example, game consoles, electric car toys, electric ship toys and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles and spacecraft, etc.

[0064] According to some embodiments of the present application, see Figure 1 and Figure 2 As shown, the cell hot pressing shaping method includes the following core steps S40 and S50:

[0065] Step S40: electrically connect two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 of the bare cell structure 40 to the heating power source 50 to electrically heat the bare cell structure 40. It can be that only the positive electrode tab 11 is electrically connected to the heating power source 50, so that the positive electrode sheet 10 generates ohmic heat when the positive electrode sheet 10 is overcurrent. Since the positive electrode sheet 10, the diaphragm 30 and the negative electrode sheet 20 are close to each other in the bare cell structure 40, the ohmic heat generated by the positive electrode sheet 10 can quickly transfer heat to the diaphragm 30 and the negative electrode sheet 20, so that the bare cell structure 40 is quickly and evenly heated as a whole, and the energy utilization rate is high. Alternatively, only the negative electrode tab 21 is electrically connected to the heating power source 50, so that the negative electrode sheet 20 generates ohmic heat when the negative electrode sheet 20 is overcurrented. Since the positive electrode sheet 10, the diaphragm 30 and the negative electrode sheet 20 are close to each other in the bare cell structure 40, the ohmic heat generated by the negative electrode sheet 20 can quickly transfer heat to the diaphragm 30 and the positive electrode sheet 10, so that the bare cell structure 40 as a whole is quickly and evenly heated, and the energy utilization rate is high. Alternatively, both the positive electrode tab 11 and the negative electrode tab 21 are electrically connected to the heating power source 50, so that both the positive electrode sheet 10 and the negative electrode sheet 20 generate ohmic heat when the current is overcurrented, so that the bare cell structure 40 as a whole is quickly and evenly heated, the heating efficiency is higher, the energy utilization rate is relatively higher, and the heating uniformity is better.

[0066] Step S50: clamp and press the heated bare cell structure 40 to fix the shape of the bare cell structure 40. In some embodiments of the present application, the clamping and pressing obtains a wound square bare cell structure 40, and then the square bare cell structure 40 is assembled into a square lithium battery.

[0067] "Positive electrode sheet 10 overcurrent" and "negative electrode sheet 20 overcurrent" mean that: the positive electrode sheet 10 and the negative electrode sheet 20 themselves have ohmic resistance, and the positive electrode sheet 10 and the negative electrode sheet 20 can be used as resistive heating devices. A loop is formed by electrically connecting the positive electrode sheet 10 to the positive power supply 51 and the negative power supply 52 of the heating power supply 50, and another loop is formed by electrically connecting the negative electrode sheet 20 to the positive power supply 51 and the negative power supply 52 of the heating power supply 50. When the loop is closed, current passes through the positive electrode sheet 10 and the negative electrode sheet 20, and the positive electrode sheet 10 and the negative electrode sheet 20 generate ohmic heat.

[0068] Ohmic heat: According to Ohm's law, when current passes through a conductor, due to the certain resistance of the conductor, the current will generate heat in the conductor. In addition, ohmic heat, that is, the heat generated in the conductor, is proportional to the resistance of the conductor, the strength of the current passing through, and the time of the current passing through. The calculation formula is expressed as: Q = I 2*R*t, where Q represents the heat generated (in joules), I represents the intensity of the current passing through (in amperes), R represents the resistance of the conductor (in ohms), and t represents the time the current passes through (in seconds).

[0069] In some embodiments of the present application, see Figure 1 As shown, before executing step S40, that is, before executing "electrically connecting two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 of the bare battery cell structure 40 to the heating power source 50", it is necessary to complete the preparation work, that is, it is necessary to complete step S10 and step S30. Specifically, the positive electrode sheet 10, the separator 30 and the negative electrode sheet 20 are stacked and composite-formed into a battery cell material roll, that is, step S10 in the battery cell hot pressing shaping method is completed: the positive electrode sheet 10, the separator 30 and the negative electrode sheet 20 are composite-formed into a battery cell material roll. Among them, in the composite-formed battery cell material roll, Figure 3 As shown, the diaphragm 30 includes a first diaphragm 31 and a second diaphragm 32, and the first diaphragm 31, the positive electrode sheet 10, the second diaphragm 32 and the negative electrode sheet 20 are sequentially stacked and compositely roll-formed into a battery core material roll. In addition, the positive electrode sheet 10 has a plurality of positive electrode tabs 11, and two adjacent positive electrode tabs 11 are arranged at intervals, and the negative electrode sheet 20 has a plurality of negative electrode tabs 21, and two adjacent negative electrode tabs 21 are arranged at intervals. The plurality of positive electrode tabs 11 and the plurality of negative electrode tabs 21 extend out of the edge of the diaphragm 30. And execute and complete step S30: wind the battery core material roll to form a bare battery core structure 40. After executing and completing step S30, the battery core material roll is wound and formed into a semi-finished product of the bare battery core structure 40, and the semi-finished product of the bare battery core structure 40 is the bare battery core structure 40 in a fluffy state.

[0070] Alternatively, the bare cell structure 40 in a fluffy state is a purchased cell raw material, and then step S40 and step S50 can be directly performed on the bare cell structure 40 in a fluffy state without performing any preparation work on the purchased bare cell structure 40 .

[0071] In preparation, see Figure 5 and Figure 6 As shown, the preparation work includes but is not limited to: die-cutting each positive electrode tab 11 and each negative electrode tab 21, so that the contour shapes of each positive electrode tab 11 and each negative electrode tab 21 after die-cutting are consistent. That is to say, after executing step S10 "positive electrode sheet 10, separator 30 and negative electrode sheet 20 are compositely formed into a battery core material roll", the positive electrode tab 11 of the compositely formed positive electrode sheet 10 and the negative electrode tab 21 of the negative electrode sheet 20 will be die-cut to obtain the positive electrode tab 11 and the negative electrode tab 21 of the predetermined shape. In addition, the positive electrode tab 11 and the negative electrode tab 21 with the same shape can be easily sorted separately, which improves the work efficiency of sorting the tabs.

[0072] Furthermore, in some embodiments of the present application, before executing step S30, that is, before executing "winding the battery core material to form a bare battery core structure 40", it is also necessary to execute and complete step S20: die-cut the two positive pole tabs 11 and / or the two negative pole tabs 21 that need to be connected to the heating power source 50 to reserve the pole tab electrical connection ends. When only the positive pole tabs 11 are electrically connected to the heating power source 50, only the two positive pole tabs 11 on the positive electrode sheet 10 that need to be used to electrically connect to the heating power source 50 are die-cut to reserve the positive pole tab electrical connection ends, and the remaining positive pole tabs 11 do not need to reserve the positive pole tab electrical connection ends (that is, these positive pole tabs 11 are directly die-cut to form the final shape of the positive pole tabs 11 of the bare battery core structure 40). When only the negative pole tabs 21 are electrically connected to the heating power source 50, only the two negative pole tabs 21 on the negative electrode sheet 20 that need to be used to electrically connect to the heating power source 50 are die-cut to reserve the negative pole tab electrical connection ends 22, such as Figure 5 As shown, the remaining negative pole tabs 21 do not need to reserve the negative pole tab electrical connection end 22 (that is, these negative pole tabs 21 can be directly die-cut to form the final shape of the negative pole tab 21 of the bare battery core structure 40). When the positive pole tabs 11 and the negative pole tabs 21 are both electrically connected to the heating power source 50, the two positive pole tabs 11 that need to be electrically connected to the heating power source 50 are die-cut to reserve the positive pole tab electrical connection end, and the two negative pole tabs 21 that need to be electrically connected to the heating power source 50 are die-cut to reserve the negative pole tab electrical connection end 22, and the remaining positive pole tabs 11 and negative pole tabs 21 are directly die-cut to form the final shapes of the positive pole tabs 11 and negative pole tabs 21 of the bare battery core structure 40.

[0073] By die-cutting to reserve the end of the pole ear for electrical connection, when the positive pole ear 11 and / or the negative pole ear 21 are electrically connected to the heating power source 50, since the length of the pole ear end is extended on the basis of the length of the pole ear, the pole ear end for electrical connection with the positive power source 51 and the negative power source 52 of the heating power source 50 will not be interfered by the other pole ears, so that the electrical connection can be completed more conveniently and quickly, as shown in FIG. Figure 2 shown.

[0074] See also Figure 1 , Figure 2 , Figure 4 and Figure 5As shown, in some embodiments of the present application, during the process of performing step S40, that is, during the process of performing "electrically connecting two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 to the heating power source 50": when only the positive electrode tabs 11 are electrically connected to the heating power source 50, the two positive electrode tabs 11 are the two positive electrode tabs 11 that are farthest apart when the bare battery core structure 40 is unfolded into a battery core material roll; when only the negative electrode tabs 21 are electrically connected to the heating power source 50, the two positive electrode tabs 11 are the two positive electrode tabs 11 that are farthest apart when the bare battery core structure 40 is unfolded into a battery core material roll; 0, the two negative pole tabs 21 are the two negative pole tabs 21 that are farthest apart when the bare cell structure 40 is unfolded into a cell material roll; or, when both the positive pole tab 11 and the negative pole tab 21 are electrically connected to the heating power source 50, the two positive pole tabs 11 are the two positive pole tabs 11 that are farthest apart when the bare cell structure 40 is unfolded into a cell material roll, and the two negative pole tabs 21 are the two negative pole tabs 21 that are farthest apart when the bare cell structure 40 is unfolded into a cell material roll. In this way, in the process of heating the bare cell structure 40 using ohmic heat, the energy utilization rate can be effectively improved.

[0075] When the two positive pole tabs 11 electrically connected to the heating power source 50 are selected as the two positive pole tabs 11 that are farthest apart when the bare cell structure 40 is unfolded into a cell material roll, the ohmic resistance that can generate ohmic heat when the positive electrode sheet 10 is overcurrent is the largest, the heating efficiency of the positive electrode sheet 10 generating ohmic heat when the overcurrent is the highest, and the energy utilization rate is high. Similarly, when the two negative pole tabs 21 electrically connected to the heating power source 50 are selected as the two negative pole tabs 21 that are farthest apart when the bare cell structure 40 is unfolded into a cell material roll, the ohmic resistance that can generate ohmic heat when the negative electrode sheet 20 is overcurrent is the largest, the heating efficiency of the negative electrode sheet 20 generating ohmic heat when the overcurrent is the highest, and the energy utilization rate is high.

[0076] In addition, in some embodiments of the present application, the two positive pole tabs 11 and / or the two negative pole tabs 21 electrically connected to the heating power source 50 may not be the two positive pole tabs 11 and / or the two negative pole tabs 21 that are farthest apart when the bare cell structure 40 is unfolded into a cell material roll. For example, when the bare cell structure 40 is unfolded into a cell material roll, the cell material roll is divided into equal parts, and then any positive pole tab 11 and / or negative pole tab 21 is selected from a section of the cell material roll divided into equal parts. For example, the equal parts are divided into two equal parts. At this time, the two positive pole tabs 11 and / or the two negative pole tabs 21 electrically connected to the heating power source 50 can be selected as the positive pole tabs 11 and / or the negative pole tabs 21 that are in a relatively central position on any section of the equal-portion cell material roll. For another example, the equal parts are divided into three equal parts, and the positive pole tabs 11 and / or the negative pole tabs 21 that are close to the equal-divided positions of the adjacent two equal-portion cell material rolls can be selected. For example, if the equal portion is divided into four equal portions, the positive electrode tab 11 and / or the negative electrode tab 21 in the relatively central position on any equal portion of the battery core material roll can be selected. In such a manner of selecting two positive electrode tabs 11 and / or negative electrode tabs 21 electrically connected to the heating power source 50, ohmic heat is generated by overcurrent of the positive electrode sheet 10 and / or the negative electrode sheet 20 to heat the bare battery core structure 40, which can not only realize efficient heating of the bare battery core structure 40, but also make the bare battery core structure 40 be heated uniformly and consistently, and effectively improve energy utilization.

[0077] In some embodiments of the present application, see Figure 2 and Figure 4 As shown, during the process of executing step S30, that is, during the process of “winding the battery core material to form a bare battery core structure 40”: the positive electrode tabs 11 are aligned with each other, and there is a gap between the surfaces of two adjacent positive electrode tabs 11, that is, a first gap 12 is formed between the surfaces of two adjacent positive electrode tabs 11, as shown in FIG. Figure 4 and, so that each negative electrode tab 21 is aligned with each other, there is a gap between the surfaces of two adjacent negative electrode tabs 21, that is, a second gap 23 is formed between the surfaces of two adjacent negative electrode tabs 21, as shown Figure 4As shown. In the bare cell structure 40, each positive electrode tab 11 is aligned with each other and each negative electrode tab 21 is aligned with each other. In the subsequent assembly process, it is beneficial to quickly complete the electrical connection of each positive electrode tab 11 to the current collector 104 of the positive electrode of the battery cell 100, and it is beneficial to quickly complete the electrical connection of each negative electrode tab 21 to the current collector 104 of the negative electrode of the battery cell 100, thereby improving the assembly efficiency. The semi-finished product of the bare cell structure 40 formed by winding, that is, the bare cell structure 40 in a fluffy state, has a first gap 12 between the surfaces of two adjacent positive electrode tabs 11 thereon, that is, the two adjacent positive electrode tabs 11 are insulated from each other. In this way, when two of the positive electrode tabs 11 are electrically connected to the positive power supply 51 and the negative power supply 52 of the heating power supply 50 and current is passed through, the current must flow through the conductor between the two positive electrode tabs 11, so that the positive electrode sheet 10 generates ohmic heat to heat the entire bare cell structure 40. Similarly, there is a second gap 23 between the surfaces of two adjacent negative electrode tabs 21 on the fluffy bare cell structure 40, that is, the two adjacent negative electrode tabs 21 are insulated from each other. In this way, when two of the negative electrode tabs 21 are electrically connected to the positive power supply 51 and the negative power supply 52 of the heating power supply 50 and current is passed, the current will inevitably flow through the conductor between the two negative electrode tabs 21, so that the negative electrode sheet 20 generates ohmic heat to heat the entire bare cell structure 40.

[0078] In addition, in some embodiments of the present application, in the bare cell structure 40 formed by winding, each positive electrode tab 11 may be misaligned, and / or each negative electrode tab 21 may also be misaligned. In the subsequent assembly process, each positive electrode tab 11 and each negative electrode tab 21 need to be classified, and then each classified positive electrode tab 11 is electrically connected to the positive electrode current collector 104 of the battery cell 100, and each classified negative electrode tab 21 is electrically connected to the negative electrode current collector 104 of the battery cell 100, and ensure that the positive electrode current collector 104 and the negative electrode current collector 104 are insulated from each other.

[0079] See also Figure 1 As shown, in some embodiments of the present application, after executing step S50, that is, after executing "clamping and shaping the heated bare cell structure 40", the shape contour of the bare cell structure 40 has been fixed, and then step S60 is executed: the electrical connection ends of the tabs are cut, that is, the two positive pole tabs are cut, and / or the two negative pole tabs are cut 22. In this way, the lengths of all positive pole tabs 11 are completely consistent, and / or the lengths of all negative pole tabs 21 are completely consistent. In this way, it is beneficial to quickly complete the electrical connection of each positive pole tab 11 to the current collector 104 of the positive electrode of the battery cell 100, and quickly complete the electrical connection of each negative pole tab 21 to the current collector 104 of the negative electrode of the battery cell 100, thereby improving assembly efficiency.

[0080] The die-cut reserved negative electrode tab connection end 22 is used as an example for explanation, and the die-cut reserved positive electrode tab connection end can refer to the negative electrode tab connection end 22. Figure 7 As shown, the negative electrode tab 21 is in a gradually narrowing trapezoidal shape from the negative electrode sheet 20 to the free end. In the final shape of the negative electrode tab 21, the width of the free end of the negative electrode tab 21 is D, that is, the width of the starting end of the negative electrode tab electrical end 22 is D, and the length of the negative electrode tab electrical end 22 is H. In addition, a circular through hole is provided on the negative electrode tab electrical end 22 to facilitate electrical connection to the negative power supply 52 of the heating power supply 50, and the diameter of the circular through hole is d. In some specific embodiments of the present application, the outer dimensions of the negative electrode tab electrical end 22 are: D is 20 mm, H is 30 mm, and d is 6 mm.

[0081] In other embodiments of the present application, after the "clamping and shaping of the heated bare cell structure 40" is completed, the two positive pole tabs and / or the two negative pole tabs may be retained. When each positive pole tab 11 is electrically connected to the positive current collector 104 of the battery cell 100, the two positive pole tabs and the ends thereof are bent and covered with the ends of the remaining positive pole tabs 11, and then all the positive pole tabs 11 are electrically connected as a whole to the positive current collector 104 of the battery cell 100. Similarly, when each negative pole tab 21 is electrically connected to the negative current collector 104 of the battery cell 100, the two negative pole tabs and the ends thereof are bent and covered with the ends of the remaining negative pole tabs 21, and then all the negative pole tabs 21 are electrically connected as a whole to the negative current collector 104 of the battery cell 100.

[0082] See also Figure 3 As shown, in some embodiments of the present application, during the execution of step S50, that is, during the execution of "clamping and pressing the heated bare cell structure 40", the bare cell structure 40 is clamped and pressed by means of upper and lower clamping. That is to say, at this time, the first pressing plate 61 and the second pressing plate 62 used for clamping and pressing are arranged vertically opposite to each other. After completing "step S30: winding the cell material to form a bare cell structure 40", the fluffy bare cell structure 40 can be directly transferred and placed on the first pressing plate 61, as shown in FIG. Figure 3As shown. Then execute "Step S40: electrically connect two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 to the heating power source 50 for electrical heating". The first pressing plate 61 and the second pressing plate 62 are arranged vertically opposite to each other. When clamping, only the first pressing plate 61 can move upward toward the second pressing plate 62, or only the second pressing plate 62 can move downward toward the first pressing plate 61, or the first pressing plate 61 and the second pressing plate 62 can move toward each other at the same time, so as to clamp and shape the bare battery cell structure 40 in a fluffy state after heating. In addition, the first pressing plate 61 can be used as a bearing component for bearing the bare battery cell structure 40 in a fluffy state, which can simplify the transfer process of conveying the bare battery cell structure 40, save conveying time, and improve work efficiency.

[0083] In some embodiments of the present application, when executing step S40, that is, when executing "electrically connecting two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 to the heating power source 50 for electrical heating", the heating time is 5s-10s to fully heat the entire bare cell structure 40. And, when executing step S50, that is, when executing "clamping and shaping the heated bare cell structure 40 to fix the shape profile of the bare cell structure 40", the time for clamping the bare cell structure 40 is 5s-10s, so that the shape profile of the bare cell structure 40 is clamped and fixed. Among them, in some embodiments of the present application, when executing step S50, that is, when executing "clamping and shaping the heated bare cell structure 40 to fix the shape contour of the bare cell structure 40", the surface pressure of clamping the bare cell structure 40 is greater than or equal to 5MPa, and the bare cell structure 40 in a fluffy state is clamped and shaped with sufficient pressure so that the bare cell structure 40 is clamped to form a shape contour of a predetermined size.

[0084] In some specific embodiments of the present application, the heating power supply 50 outputs a current I of 70A-100A to the positive electrode sheet 10 and / or the negative electrode sheet 20, for example, 85A, and the current carrying time of the positive electrode sheet 10 and / or the negative electrode sheet 20 is 10s (i.e., the heating time is 10s), thereby heating the bare cell structure 40 in a fluffy state to about 90°C. At this time, the temperature difference between the inner ring and the outer ring of the bare cell structure 40 in a fluffy state is about 2°C, and the bare cell structure 40 is uniformly heated as a whole, and the heating consistency is good. In addition, the surface pressure of 5MPa is used between the first pressing plate 61 and the second pressing plate 62 to clamp and shape the bare cell structure 40 in a fluffy state, and the clamping and shaping time is 7s. In this way, there is no undesirable phenomenon of the pole piece opening (especially the inner ring pole piece opening) or the diaphragm closed hole in the bare cell structure 40 after hot pressing and shaping, which improves the product yield of the bare cell structure 40.

[0085] Pole piece opening means: when the fluffy bare cell structure 40 is clamped by the first pressure plate 61 and the second pressure plate 62, the bare cell structure 40 is subjected to uneven pressure, which causes the inner and outer ring pole pieces to deform inconsistently during the clamping process. The edge areas of the pole pieces will bend outwards to present an open shape, especially the edge areas of the inner ring pole pieces will bend outwards to present an open shape. This is called pole piece opening, which is an undesirable phenomenon that affects product quality.

[0086] In some embodiments of the present application, between executing step S40 and executing step S50, that is, between executing "electrically connecting two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 to the heating power source 50 to electrically heat the bare cell structure 40" and executing "clamping and shaping the heated bare cell structure 40 to fix the shape profile of the bare cell structure 40", the interval time between the two steps is 0-10s. Since when executing step S40, the temperature of heating different bare cell structures 40 is not always the ideal temperature value for executing step S50, the overall temperature of some bare cell structures 40 is sometimes slightly higher than the ideal temperature value for executing step S50. At this time, the heated bare cell structure 40 is left to stand, so that the overall temperature of the bare cell structure 40 reaches the ideal temperature value for executing step S50. This can effectively improve the product quality of the bare cell structure 40 with a fixed shape contour obtained by the clamping and shaping in step S50. Since the temperature of the bare cell structure 40 is appropriate when executing step S50, the probability of diaphragm closure caused by the high temperature of the bare cell structure 40 is effectively reduced, and the product quality of the bare cell structure 40 formed by hot pressing is effectively improved.

[0087] In a specific embodiment of the present application, the battery cell hot pressing shaping method provided by the design includes the following steps in sequence:

[0088] Step S10: The positive electrode sheet 10, the separator 30 and the negative electrode sheet 20 are composite-formed into a battery core roll;

[0089] Step S20: Die-cut two positive electrode tabs 11 and / or two negative electrode tabs 21 that need to be connected to the heating power source 50 to reserve the tab power connection ends;

[0090] Step S30: Winding the battery core material to form a bare battery core structure 40;

[0091] Step S40: electrically connecting two of the positive electrode tabs 11 and / or two of the negative electrode tabs 21 of the bare cell structure 40 to the heating power source 50 to electrically heat the bare cell structure 40;

[0092] Step S50: clamping and shaping the heated bare cell structure 40 to fix the shape of the bare cell structure 40;

[0093] Step S60: cutting the electrical connection end of the tab.

[0094] Among them, during the execution of the specific embodiment of the present application, step S40 is to heat the entire bare cell structure 40 by passing current through the negative electrode sheet 20 to generate ohmic heat. Therefore, when executing step S20, only the two negative electrode tabs 21 of the negative electrode sheet 20 electrically connected to the heating power supply 50 are die-cut to reserve the negative electrode tab electrical connection end 22, and the two negative electrode tabs 21 electrically connected to the positive power supply 51 and the negative power supply 52 of the heating power supply 50 are the two negative electrode tabs 21 farthest apart when the bare cell structure 40 is unfolded into a cell material roll. When executing step S40, the heating power supply 50 outputs a current I of 85A to the negative electrode sheet 20, and the current carrying time of the negative electrode sheet 20 is 10s (that is, the heating time is 10s), thereby heating the fluffy bare cell structure 40 to about 90°C. Furthermore, when executing step S50, the first pressing plate 61 and the second pressing plate 62 are clamped and pressed to shape the fluffy bare cell structure 40 with a surface pressure of 5 MPa, and the clamping and pressing time is 7 seconds.

[0095] According to another aspect of the embodiment of the present application, a battery core hot pressing shaping device is designed and provided, see Figure 8 As shown, Figure 8 Of the two ellipsis symbols shown in FIG. 1 , one indicates that the station and equipment in the previous process are omitted, and the other indicates that the station and equipment in the subsequent process are omitted. The battery cell hot pressing shaping device designed in the embodiment of the present application includes a shaping station 74. Figure 2 and Figure 3 As shown, the shaping station 74 is provided with a driving mechanism (not shown), a first pressing plate 61, a second pressing plate 62 and a heating power source 50. Specifically, the first pressing plate 61 and the second pressing plate 62 are arranged opposite to each other to clamp the bare cell structure 40, the driving mechanism is drivingly connected to the first pressing plate 61 and / or the driving mechanism is drivingly connected to the second pressing plate 62, and the heating power source 50 is used to electrically heat the bare cell structure 40.

[0096] In some embodiments of the present application, the first pressing plate 61 and the second pressing plate 62 are arranged vertically opposite to each other, and the first pressing plate 61 is used to place the bare cell structure 40, and the fluffy bare cell structure 40 can be directly transferred and placed on the first pressing plate 61. In other words, using the first pressing plate 61 as a bearing component for bearing the fluffy bare cell structure 40 can simplify the transfer process of conveying the bare cell structure 40, save conveying time, and improve work efficiency.

[0097] In some embodiments of the present application, the driving mechanism may be only drivingly connected to the first pressing plate 61 , that is, the driving mechanism drives the first pressing plate 61 to move toward the second pressing plate 62 , and at this time, the second pressing plate 62 is fixedly arranged.

[0098] In some embodiments of the present application, the driving mechanism may be only drivingly connected to the second pressing plate 62 , that is, the driving mechanism drives the second pressing plate 62 to move toward the first pressing plate 61 , and at this time, the first pressing plate 61 is fixedly arranged.

[0099] In some embodiments of the present application, the driving mechanism is driven and connected to the first pressing plate 61 and the second pressing plate 62, that is, the driving mechanism drives the first pressing plate 61 and the second pressing plate 62 to move toward each other simultaneously to clamp and heat the bare cell structure 40, so that the bare cell structure 40 in a fluffy state is clamped and shaped into a fixed shape contour.

[0100] See also Figure 8 and Figure 3 As shown, the battery cell hot pressing shaping device further includes a winding station 73. The winding station 73 is located upstream of the shaping station 74, and the winding station 73 is used to wind the battery cell material to form a bare battery cell structure 40. At this time, the bare battery cell structure 40 formed by winding is in a fluffy state and is a semi-finished product of the bare battery cell structure 40.

[0101] See also Figures 5 to 8 As shown, the battery cell hot pressing and shaping device also includes a composite molding station 71 and a die-cutting station 72. The composite molding station 71 is located upstream of the die-cutting station 72, and the composite molding station 71 is used to laminate and compositely mold the positive electrode sheet 10, the separator 30 and the negative electrode sheet 20 into a battery cell material roll. The die-cutting station 72 is located upstream of the winding station 73, and the die-cutting station 72 is used to die-cut the positive electrode tab 11 and / or the negative electrode tab 21 on the battery cell material roll, and die-cut to obtain the tab electrical connection end for electrical connection to the heating power supply 50. The tab electrical connection end is reserved by die-cutting. When the positive electrode tab 11 and / or the negative electrode tab 21 are electrically connected to the heating power supply 50, since the length of the tab electrical connection end is extended on the basis of the length of the tab, the tab electrical connection end will not be interfered by the other tabs when it is electrically connected to the positive power supply 51 and the negative power supply 52 of the heating power supply 50, so that the electrical connection can be completed more conveniently and quickly, as shown in FIG. Figure 2 shown.

[0102] In some embodiments of the present application, the shaping station 74 is further provided with a cutting mechanism (not shown). After the first pressing plate 61 and the second pressing plate 62 clamp the bare cell structure 40, the cutting mechanism is used to cut the electrical connection ends of the tabs, that is, to cut off the two positive pole tab electrical connection ends, and / or to cut off the two negative pole tab electrical connection ends 22. In this way, the lengths of all the positive pole tabs 11 are completely consistent, and / or the lengths of all the negative pole tabs 21 are completely consistent. In this way, it is beneficial to quickly complete the electrical connection of each positive pole tab 11 to the current collector 104 of the positive electrode of the battery cell 100, and quickly complete the electrical connection of each negative pole tab 21 to the current collector 104 of the negative electrode of the battery cell 100, thereby improving assembly efficiency.

[0103] In a specific embodiment of the present application, the battery core hot pressing and shaping device provided by the design includes a composite molding station 71, a die cutting station 72, a winding station 73 and a shaping station 74 in sequence. Figure 8 As shown. Among them, the shaping station 74 heats the entire bare cell structure 40 by passing current through the negative electrode sheet 20 to generate ohmic heat. Therefore, in the die-cutting station 72, only the two negative electrode tabs 21 of the negative electrode sheet 20 that are electrically connected to the positive power supply 51 and the negative power supply 52 of the heating power supply 50 are die-cut to reserve the negative electrode tab electrical connection end 22. Moreover, in the shaping station 74, the first pressing plate 61 and the second pressing plate 62 are arranged vertically opposite to each other. At this time, the first pressing plate 61 can be used as a bearing component for bearing the bare cell structure 40 in a fluffy state. Moreover, the driving mechanism is only connected to the second pressing plate 62, so that after the bare cell structure 40 is heated, the second pressing plate 62 is driven to move toward the first pressing plate 61 to clamp and shape the bare cell structure 40 to obtain a bare cell structure 40 with a fixed shape contour.

[0104] According to another aspect of the embodiment of the present application, a battery cell is provided, including a bare cell structure 40 that is hot-pressed and shaped by the hot-pressing and shaping method of the cell as described above, see Fig. 9 shown.

[0105] In some embodiments of the present application, see Fig. 9 As shown, the battery cell 100 includes an end cap 101, a housing 103, a current collector 104, at least one bare cell structure 40, at least one closed liquid capsule 105 and other functional components.

[0106] The end cap 101 refers to a component that covers the opening of the shell 103 to cover and seal the opening of the shell 103. Without limitation, the shape of the end cap 101 can be adapted to the shape of the shell 103 to match the shell 103. Optionally, the end cap 101 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 101 is not easily deformed when squeezed and collided, so that the battery cell 100 can have a higher structural strength and the safety performance can also be improved. Functional components such as electrode terminals 102 can be provided on the end cap 101. The electrode terminal 102 can be used to electrically connect to the bare cell structure 40 for outputting or inputting electrical energy of the battery cell 100. The material of the end cap 101 can also be various, including but not limited to copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0107] The shell 103 is a component used to cooperate with the end cap 101 to form an assembly space for the battery cell 100, wherein the formed assembly space can be used to accommodate the bare cell structure 40, electrolyte and other components. The shell 103 and the end cap 101 can be independent components, and an opening can be set on the shell 103, and the end cap 101 is made to cover the opening at the opening to form an assembly space for the battery cell 100. Specifically, the shape of the shell 103 can be determined according to the specific shape and size of the bare cell structure 40. The material of the shell 103 can be various, including but not limited to copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0108] When the end cap 101 and the shell 103 are made of conductive materials, an insulating layer needs to be provided on the inner wall of the assembly space formed by the end cap 101 and the shell 103 to prevent a short circuit between the end cap 101, the shell 103 and the bare cell structure 40, thereby preventing the battery cell 100 from malfunctioning and being damaged.

[0109] At least one bare cell structure 40 is arranged in the housing 103, and the stacked positive electrode tabs 11 in the bare cell structure 40 are electrically connected through a current collector 104, and the stacked negative electrode tabs 21 are electrically connected through a current collector 104. Then, the current collector 104 electrically connected to the positive electrode tab 11 is electrically connected to the positive electrode terminal 102 provided on the end cap 101, and the current collector 104 electrically connected to the negative electrode tab 21 is electrically connected to the negative electrode terminal 102 provided on the end cap 101.

[0110] At least one closed liquid capsule 105 contains electrolyte. The liquid capsule 105 is arranged in the housing 103 and is at least arranged corresponding to the side wall of the bare battery cell structure 40. At least one weak structure is provided on the liquid capsule 105. When the pressure in the liquid capsule 105 reaches a threshold value, the electrolyte in the liquid capsule 105 breaks through the weak structure and flows out of the liquid capsule 105.

[0111] The liquid capsule 105 is a closed capsule containing electrolyte inside, which can be deformed when squeezed. In order to adapt to the use environment inside the battery and facilitate sealing, the liquid capsule 105 should be formed using a non-conductive packaging material with corrosion resistance and adhesion. For example, a functional composite film or packaging material comprising an external protective layer and an internal sealing layer can be used. The external protective layer is a corrosion-resistant insulating material that can be applied to the electrolyte environment in the battery and adapt to the temperature and pressure environment under the battery use state. For example, the external protective layer can be aluminum, Teflon, acrylic, polypropylene, etc. The internal sealing layer can be, for example, a thermoplastic polyester film or coating that is convenient for packaging by a heat sealing process, such as polypropylene, polyvinyl chloride, polystyrene, acrylic resin, polycarbonate, polytetrafluoroethylene, polyurethane, etc. In some embodiments, an aluminum-plastic film can be used to form a closed liquid capsule 105 by heat sealing.

[0112] The liquid capsule 105 is provided with a weak structure, which has a lower strength than other positions on the liquid capsule 105, so that when the pressure in the liquid capsule 105 reaches a threshold, the electrolyte will break through the weak structure and flow out of the liquid capsule 105 from the rupture of the weak structure.

[0113] “The side wall of the bare cell structure 40” refers to the outer wall of the bare cell structure 40 in the direction parallel to the height direction. The expansion force of the bare cell structure 40 is usually in the direction perpendicular to the height direction, so the bulging direction of the bare cell structure 40 mainly occurs in the large side wall (i.e., the thickness direction) and the corners (i.e., the two ends in the width direction). “The liquid capsule 105 is at least arranged corresponding to the side wall of the bare cell structure 40” means that the liquid capsule 105 is arranged in the shell 103 and at least part of the liquid capsule 105 is in contact with the side wall of the bare cell structure 40.

[0114] As the bare cell structure 40 is used for a longer time, when the side wall swells, an extrusion force is generated on the liquid capsule 105 corresponding to the side wall of the bare cell structure 40. The liquid capsule 105 will be deformed by the extrusion, and become thinner at the position corresponding to the side wall of the bare cell structure 40. The electrolyte in the liquid capsule 105 is relatively gathered in the area with less extrusion force, such as the end area of ​​the liquid capsule 105 along the height direction of the bare cell structure 40 in the figure, and this area is used as a buffer space for the expansion force of the bare cell structure 40. At the same time, the internal pressure of the liquid capsule 105 increases, which has a certain resistance and relief to the expansion force of the side wall of the bare cell structure 40. In this way, the further deterioration of the expansion force of the bare cell structure 40 and the risk of lithium plating caused by squeezing the pole piece can be avoided.

[0115] As the bare cell structure 40 is used for a longer time, the expansion force increases further, and the degree of squeezing the liquid capsule 105 also increases further. When the internal pressure of the liquid capsule 105 increases to a threshold value, the weak structure is broken, and the electrolyte in the liquid capsule 105 flows out of the liquid capsule 105 from the rupture at the location of the weak structure. The electrolyte in the liquid capsule 105 can automatically replenish the electrolyte loss in the shell 103.

[0116] In a specific embodiment of the present application, the battery cell 100 provided by the design includes a liquid capsule 105 and two bare cell structures 40. In the housing 103, the liquid capsule 105 and the two bare cell structures 40 are stacked, and the liquid capsule 105 is located between the two bare cell structures 40.

[0117] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for hot pressing and shaping a battery cell, used for hot pressing and shaping a bare battery cell structure, characterized in that: The battery core hot pressing shaping method comprises the following steps: Electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs of the bare cell structure to a heating power source to electrically heat the bare cell structure; The heated bare cell structure is clamped and pressed to fix the shape of the bare cell structure.

2. The method for hot pressing and shaping a battery cell according to claim 1, characterized in that: Before executing the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs of the bare cell structure to a heating power source to electrically heat the bare cell structure", execute the steps of: stacking and composite-forming the positive electrode sheets, separators and negative electrode sheets into a cell material roll, and winding the cell material roll to form a bare cell structure.

3. The battery core hot pressing shaping method according to claim 1 or 2, characterized in that: During the process of executing the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs of the bare cell structure to a heating power source": two of the positive electrode tabs are the two positive electrode tabs that are farthest apart when the bare cell structure is unfolded into the cell material roll; and / or, two of the negative electrode tabs are the two negative electrode tabs that are farthest apart when the bare cell structure is unfolded into the cell material roll.

4. The battery core hot pressing shaping method according to claim 2 or 3, characterized in that: Before executing the step of "winding the battery core material to form a bare battery core structure", the two positive electrode tabs and / or the two negative electrode tabs that need to be connected to the heating power supply are die-cut to reserve the tab power connection ends.

5. The method for hot pressing and shaping a battery cell according to claim 4, characterized in that: When executing the step of "die-cutting the two positive pole tabs and / or the two negative pole tabs that need to be connected to the heating power supply to reserve the pole tab power connection ends", each of the positive pole tabs and each of the negative pole tabs are die-cut so that the contour shapes of each of the positive pole tabs and each of the negative pole tabs after die-cutting are consistent.

6. The method for hot pressing and shaping a battery cell according to any one of claims 2 to 5, characterized in that: During the process of executing the step of "winding the battery core material to form a bare battery core structure": the positive electrode tabs are aligned with each other, and there is a gap between the surfaces of two adjacent positive electrode tabs; and the negative electrode tabs are aligned with each other, and there is a gap between the surfaces of two adjacent negative electrode tabs.

7. The method for hot pressing and shaping a battery cell according to any one of claims 4 to 5, characterized in that: After completing the step of "clamping and shaping the heated bare cell structure", the electrical connection end of the tab is cut.

8. The method for hot pressing and shaping a battery cell according to any one of claims 1 to 7, characterized in that: During the execution of the step of "clamping and pressing the heated bare cell structure to shape it": the bare cell structure is clamped and pressed by means of upper and lower clamping.

9. The method for hot pressing and shaping a battery cell according to any one of claims 1 to 8, characterized in that: When executing the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs to a heating power source to electrically heat the bare battery cell structure", the heating time is 5s-10s.

10. The battery core hot pressing shaping method according to any one of claims 1 to 9, characterized in that: When executing the step of "clamping and shaping the heated bare cell structure to fix the shape contour of the bare cell structure", the time for clamping and pressing the bare cell structure is 5s-10s.

11. The method for hot pressing and shaping a battery cell according to any one of claims 1 to 10, characterized in that: When executing the step of "clamping and pressing the heated bare cell structure to fix the shape contour of the bare cell structure", the surface pressure of clamping the bare cell structure is greater than or equal to 5 MPa.

12. The battery core hot pressing shaping method according to any one of claims 1 to 11, characterized in that: The interval time between executing the step of "electrically connecting two of the positive electrode tabs and / or two of the negative electrode tabs to a heating power source for electrical heating" and executing the step of "clamping and shaping the heated bare battery cell structure to fix the shape contour of the bare battery cell structure" is 0-10s.

13. A battery cell, characterized in that: It comprises a bare cell structure that is hot-pressed and shaped by the cell hot-pressing and shaping method as described in any one of claims 1 to 12.

14. A battery core hot pressing and shaping device, characterized in that: It includes a shaping station, which is provided with a driving mechanism, a first pressing plate, a second pressing plate and a heating power supply. The first pressing plate and the second pressing plate are arranged opposite to each other to clamp the bare battery cell structure. The driving mechanism is connected to the first pressing plate and / or the driving mechanism is connected to the second pressing plate. The heating power supply is used to electrically heat the bare battery cell structure.

15. The battery core hot pressing and shaping device according to claim 14, characterized in that: The battery cell hot pressing and shaping device also includes a winding station, which is located upstream of the shaping station and is used to wind the battery cell material to form the bare battery cell structure.

16. The battery core hot pressing and shaping device according to claim 15, characterized in that: The battery cell hot pressing and shaping device also includes a composite molding station and a die-cutting station. The die-cutting station is located upstream of the winding station, and the composite molding station is located upstream of the die-cutting station. The composite molding station is used to compositely mold the positive electrode sheet, the diaphragm and the negative electrode sheet into the battery cell material roll in a stacked manner. The die-cutting station is used to die-cut the positive electrode tabs and / or negative electrode tabs on the battery cell material roll, and die-cut to obtain the tab electrical connection ends for electrical connection to the heating power supply.

17. The battery core hot pressing and shaping device according to claim 16, characterized in that: The shaping station is further provided with a cutting mechanism, which is used to cut the electrical connection end of the tab after the first pressing plate and the second pressing plate clamp the bare battery core structure.

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