Lithium battery and method for manufacturing the same

Abstract

The application provides a lithium battery and a preparation method thereof. The preparation method of the lithium battery comprises the following steps: firstly, coating active materials on the first active material coating sublayer coating area, the second active material coating sublayer coating area and the second bonding layer to form the first active material coating sublayer, the second active material coating sublayer and the second active material coating layer; secondly, forming the heat dissipation glue layer on the positive plate by coating the heat dissipation glue solution on the heat dissipation air foil area and forming the heat dissipation glue layer after solidification; finally, stacking the negative plate, the diaphragm and the positive plate in sequence and performing the lamination operation to obtain the battery cell, so that when the temperature in the battery cell rises during use, the heat in the battery cell can be conducted out of the external through the heat dissipation glue layer, the temperature in the battery cell can be greatly reduced, and the heat dissipation performance of the lithium battery is effectively improved, and the cycle performance of the lithium battery is effectively optimized.

Description

Technical Field

[0001] This invention relates to the field of batteries, and in particular to a lithium battery and its preparation method. Background Technology

[0002] Lithium-ion batteries have been widely used in portable consumer electronics, power tools, and medical electronics due to their advantages such as high energy density, high power density, long cycle life, no memory effect, low self-discharge rate, wide operating temperature range, safety, reliability, and environmental friendliness. However, with the increasing market demand for lithium-ion batteries, the performance requirements are also becoming more stringent. During charging and discharging, lithium-ion batteries generate a large amount of heat, causing the battery temperature to rise and leading to a deterioration in cycle performance. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a lithium battery with better heat dissipation performance and better battery cycle performance, as well as a method for preparing the same.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A method for preparing a lithium battery includes the following steps:

[0006] Preparation of negative electrode sheet;

[0007] Preparation of positive electrode sheet;

[0008] The negative electrode, the separator, and the positive electrode are sequentially stacked and a stacking operation is performed to obtain a battery cell;

[0009] The specific operations for preparing the positive electrode sheet include the following steps:

[0010] The aluminum foil base strip is divided into multiple positive electrode regions;

[0011] A first adhesive layer and a second adhesive layer are provided on both sides of each positive electrode region;

[0012] The first adhesive layer is divided into a positive electrode tab welding empty foil area, a first active material coating sub-layer coating area, a heat dissipation empty foil area, and a second active material coating sub-layer coating area, which are distributed in sequence.

[0013] An active material is coated on the coating area of ​​the first active material coating sublayer, the coating area of ​​the second active material coating sublayer, and the second adhesive layer to form the first active material coating sublayer, the second active material coating sublayer, and the second active material coating layer.

[0014] The heat dissipation adhesive is applied to the heat dissipation foil area, and a heat dissipation adhesive layer is formed after curing;

[0015] The aluminum foil substrate is die-cut to obtain multiple positive electrode sheets.

[0016] In one embodiment, the thermal adhesive comprises the following components in parts by weight:

[0017]

[0018] In one embodiment, the delay agent is OH 1-etyny1-1-cyclohexanol.

[0019] In one embodiment, the adhesive is polyvinylidene fluoride.

[0020] In one embodiment, the first thermally conductive flame retardant is aluminum oxide;

[0021] The second thermally conductive flame retardant is aluminum hydroxide.

[0022] In one embodiment, after the thermal adhesive is applied to the thermally insulating foil area and a thermal adhesive layer is formed after curing, and after the aluminum foil substrate is die-cut to obtain the positive electrode sheet, the preparation of the positive electrode sheet further includes the following steps:

[0023] The aluminum foil base strip is subjected to a rolling operation.

[0024] In one embodiment, the specific operation of preparing the negative electrode sheet includes the following steps:

[0025] Divide the copper foil baseband into multiple negative electrode regions;

[0026] The coating process is performed on multiple negative electrode regions;

[0027] The coated copper foil substrate is then subjected to a roller-rolling operation.

[0028] The copper foil substrate after passing through the roller is die-cut to obtain multiple negative electrode sheets.

[0029] In one embodiment, after sequentially stacking the negative electrode, the separator, and the positive electrode to obtain a battery cell, the following step is further included:

[0030] The battery cell is then soldered with electrode tabs.

[0031] In one embodiment, after the electrode tab bonding operation on the battery cell, the following steps are further included:

[0032] The battery cell is processed to obtain a finished lithium battery.

[0033] A lithium battery is prepared using the lithium battery preparation method described in any of the above embodiments.

[0034] Compared with the prior art, the present invention has at least the following advantages:

[0035] The lithium battery manufacturing method of this application comprises a first adhesive layer in a single positive electrode area with sequentially distributed positive electrode tab welding empty foil area, a first active material coating sub-layer coating area, a heat dissipation empty foil area, and a second active material coating sub-layer coating area. First, active material is coated onto the first active material coating sub-layer coating area, the second active material coating sub-layer coating area, and the second adhesive layer to form the first active material coating sub-layer, the second active material coating sub-layer, and the second active material coating layer. Next, a heat dissipation adhesive is applied to the heat dissipation empty foil area and, after curing, forms a heat dissipation adhesive layer, thereby forming a heat dissipation adhesive layer on the positive electrode. Finally, the negative electrode, separator, and positive electrode are sequentially stacked and laminated to obtain a battery cell. This means that when the internal temperature of the battery cell rises during use, the heat can be conducted to the outside through the heat dissipation adhesive layer, significantly reducing the internal temperature of the battery and effectively improving the heat dissipation performance of the lithium battery, thereby effectively optimizing the cycle performance of the lithium battery. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart of a method for preparing a lithium battery in one embodiment;

[0038] Figure 2 for Figure 1 The flowchart shows some steps of the lithium battery manufacturing method.

[0039] Figure 3 The thermal image of Comparative Example 1 after thermal imaging processing.

[0040] Figure 4 This is a thermal image of Example 1 after thermal imaging processing;

[0041] Figure 5 The graphs show the cyclic test results for Comparative Examples 1-2 and Examples 1-2;

[0042] Figure 6 This is a schematic diagram showing the results of the acupuncture test performed on Comparative Example 1.

[0043] Figure 7 This is a schematic diagram showing the results of the acupuncture test in Example 1;

[0044] Figure 8 This is a schematic diagram of the lithium battery structure in another embodiment;

[0045] Figure 9 for Figure 8 A schematic diagram of a partial structure of a lithium battery is shown.

[0046] Figure 10 for Figure 8 The diagram shows a partial structural schematic of a lithium battery. Detailed Implementation

[0047] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0048] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0050] The lithium battery preparation method provided in this application includes the following steps: preparing a negative electrode sheet; preparing a positive electrode sheet; sequentially stacking the negative electrode sheet, separator, and positive electrode sheet to obtain a battery cell; wherein, the specific operation of preparing the positive electrode sheet includes the following steps: dividing an aluminum foil base strip into multiple positive electrode sheet regions; providing a first adhesive layer and a second adhesive layer on both sides of each positive electrode sheet region; dividing the first adhesive layer into sequentially distributed positive electrode tab welding empty foil regions, first active material coating sub-layer coating regions, heat dissipation empty foil regions, and second active material coating sub-layer coating regions; coating active material on the first active material coating sub-layer coating regions, the second active material coating sub-layer coating regions, and the second adhesive layer to form a first active material coating sub-layer, a second active material coating sub-layer, and a second active material coating layer; coating a heat dissipation adhesive onto the heat dissipation empty foil regions, and forming a heat dissipation adhesive layer after curing; and performing a die-cutting operation on the aluminum foil base strip to obtain multiple positive electrode sheets.

[0051] The aforementioned method for manufacturing a lithium battery involves sequentially distributing a positive electrode tab welding foil area, a first active material coating sub-layer coating area, a heat dissipation foil area, and a second active material coating sub-layer coating area in the first adhesive layer of a single positive electrode area. First, active material is coated onto the first active material coating sub-layer coating area, the second active material coating sub-layer coating area, and the second adhesive layer to form the first active material coating sub-layer, the second active material coating sub-layer, and the second active material coating layer. Next, a heat dissipation adhesive is applied to the heat dissipation foil area and cured to form a heat dissipation adhesive layer, thus forming a heat dissipation adhesive layer on the positive electrode. Finally, the negative electrode, separator, and positive electrode are sequentially stacked and laminated to obtain the battery cell. This means that when the internal temperature of the battery cell rises during use, the heat can be conducted to the outside through the heat dissipation adhesive layer, significantly reducing the internal temperature of the battery and effectively improving its heat dissipation performance, thereby effectively optimizing its cycle performance.

[0052] Please see Figure 1 and Figure 2 To better understand the lithium battery preparation method of this application, the following further explanation is provided:

[0053] One embodiment of the method for preparing a lithium battery includes the following steps:

[0054] S100 is used to prepare the negative electrode.

[0055] In this embodiment, a negative electrode is prepared, which is one of the essential components for the conductivity of the lithium battery during use, to ensure that the lithium battery can be used normally.

[0056] S200 is used to prepare the positive electrode.

[0057] In this embodiment, a positive electrode is prepared, which is one of the essential components for the conductivity of the lithium battery during use, to ensure that the lithium battery can be used normally.

[0058] S300, the negative electrode, the separator and the positive electrode are sequentially stacked and stacked to obtain a battery cell.

[0059] In this embodiment, the negative electrode, separator and positive electrode are first stacked sequentially to form an electrode module, and then the electrode module is stacked by a stacking machine to form a battery cell.

[0060] The specific operations for preparing the positive electrode sheet include the following steps:

[0061] S201 divides the aluminum foil baseband into multiple positive electrode regions.

[0062] In this embodiment, since the aluminum foil base strip is relatively long, it is first divided into multiple positive electrode areas to facilitate the rapid progress of subsequent processes, thereby effectively improving the production efficiency of lithium batteries.

[0063] S202, a first adhesive layer and a second adhesive layer are provided on both sides of each of the positive electrode regions.

[0064] In this embodiment, the first adhesive layer and the second adhesive layer are located on both sides of a single positive electrode area, which facilitates precise positioning in subsequent processes and thus effectively improves the production efficiency of lithium batteries.

[0065] S203, the first adhesive layer is divided into sequentially distributed positive electrode tab welding empty foil area, first active material coating sub-layer coating area, heat dissipation empty foil area and second active material coating sub-layer coating area.

[0066] In this embodiment, the first adhesive layer is divided into a positive electrode tab welding empty foil area, a first active material coating sub-layer coating area, a heat dissipation empty foil area, and a second active material coating sub-layer coating area, which enables precise positioning of subsequent processes to improve the production efficiency of lithium batteries.

[0067] S204, apply active materials to the coating areas of the first active material coating sublayer, the second active material coating sublayer, and the second adhesive layer to form the first active material coating sublayer, the second active material coating sublayer, and the second active material coating layer.

[0068] In this embodiment, the active material is one of the main factors that enables the positive electrode to conduct electricity, allowing electrons to become more active on the positive electrode to improve the performance of the lithium battery.

[0069] S205, the heat dissipation adhesive is applied to the heat dissipation foil area, and a heat dissipation adhesive layer is formed after curing.

[0070] In this embodiment, without affecting the performance of the lithium battery, a heat dissipation foil area is provided in the first adhesive layer. Since the overall temperature inside the lithium battery cell will rise during use, and high temperature has a certain impact on the activity of the active material and may even reduce the activity of the active material, thus causing the cycle performance of the lithium battery to decline, a heat dissipation foil area is provided in the first adhesive layer and a heat dissipation adhesive is applied to the heat dissipation foil area to form a heat dissipation adhesive layer. This allows the internal heat of the cell to be conducted away through the heat dissipation adhesive layer during use, effectively reducing the internal temperature of the cell and preventing the activity of the active material from being affected by excessive temperature. This effectively optimizes the cycle performance of the lithium battery and also improves the heat dissipation performance of the lithium battery.

[0071] S206, the aluminum foil base strip is die-cut to obtain a plurality of positive electrode sheets.

[0072] In this embodiment, a die-cutting machine is used to perform die-cutting operations on multiple positive electrode areas of the aluminum foil base strip, so that multiple aluminum foil base strips are cut into multiple positive electrode sheets, realizing the mass production of positive electrode sheets, improving the production efficiency of a single positive electrode sheet, and thus effectively improving the production efficiency of lithium batteries.

[0073] In one embodiment, the thermal adhesive comprises the following components in parts by weight:

[0074]

[0075]

[0076] In this embodiment, the delay agent in the thermal adhesive reduces the release rate of each component in the thermal adhesive system, ensuring the durability of the thermal adhesive's heat dissipation effect. This, in turn, ensures the durability of the thermal adhesive's heat dissipation effect when applied to the positive electrode, thereby effectively extending the lifespan of the positive electrode sheet. ViMe2SiO(Me2SiO)nSiMe2Vi and Me3SiO(Me2SiO)m(MeHSiO)nSiMe3 are both crosslinking agents, capable of generating chemical bonds between linear molecules in the thermal adhesive system, causing the linear molecules to interlink and form a network structure. This results in a high molecular structure strength in the thermal adhesive system. Furthermore, the addition of a binder further enhances the bonding force of each molecule in the thermal adhesive system. The network structure also allows the first and second thermally conductive flame retardants to be more evenly dispersed in the system, enabling the thermal adhesive to effectively improve the heat dissipation uniformity of the thermal adhesive coating area of ​​the positive electrode sheet when applied to the positive electrode sheet.

[0077] In one embodiment, the delay agent is OH 1-etyny1-1-cyclohexanol. It should be noted that OH 1-etyny1-1-cyclohexanol is 1-ethynyl-1-cyclohexanol, an alcohol-based delay agent that can reduce the release rate of each component in the thermal adhesive system, thereby effectively improving the durability of the thermal adhesive's heat dissipation effect.

[0078] In one embodiment, the adhesive is polyvinylidene fluoride (PVDF). It should be noted that PVDF is a copolymer that combines the characteristics of both fluoropolymers and general-purpose resins, namely, good adhesion, serving as an interfacial bond in the system, and also possessing high-temperature resistance, resulting in good structural stability of the thermal adhesive system and good stability of the thermal adhesive layer when applied to lithium batteries.

[0079] In one embodiment, the first thermally conductive flame retardant is aluminum oxide; the second thermally conductive flame retardant is aluminum hydroxide. It should be noted that both aluminum hydroxide and aluminum oxide not only provide flame retardancy but also contribute to heat conduction in the system. By forming a network structure within the system and dispersing aluminum hydroxide and aluminum oxide within this network structure, the thermally conductive flame retardants in the thermal adhesive system are uniformly dispersed. This results in a more uniform heat dissipation performance of the thermal adhesive layer after curing when applied to the positive electrode, effectively improving the heat dissipation performance of the positive electrode and consequently, the heat dissipation performance of the lithium battery.

[0080] In one embodiment, after the thermal adhesive is applied to the thermally insulating foil area and a thermal adhesive layer is formed after curing, and after the aluminum foil substrate is die-cut to obtain the positive electrode sheet, the preparation of the positive electrode sheet further includes the following steps:

[0081] The aluminum foil base strip is subjected to a rolling operation.

[0082] In this embodiment, the aluminum foil base strip is pressed by a roller press, which improves the flatness of both sides of the aluminum foil base strip, that is, effectively improves the flatness of the coating layer and the heat dissipation adhesive layer, thereby ensuring the pass rate of the positive electrode sheet, and thus effectively ensuring the product pass rate of the lithium battery.

[0083] In one embodiment, the specific operation of preparing the negative electrode sheet includes the following steps:

[0084] First, the copper foil substrate is divided into multiple negative electrode areas.

[0085] In this embodiment, since the second aluminum foil base strip is relatively long, it is first divided into multiple negative electrode areas to facilitate the rapid progress of subsequent processes, thereby effectively improving the production efficiency of lithium batteries.

[0086] Next, a coating process is performed on multiple negative electrode regions.

[0087] In this embodiment, before coating multiple negative electrode areas, the two sides of the negative electrode area are first divided into a third adhesive layer and a fourth adhesive layer. The third adhesive layer has a negative electrode tab welding foil area and a third active material coating area, and the fourth adhesive layer has a fourth active material coating area. Then, active material is coated onto the third and fourth active material coating areas. The active material is one of the main factors enabling the negative electrode to conduct electricity, allowing electrons to become more active on the negative electrode, thereby improving the performance of the lithium battery.

[0088] Next, the coated copper foil substrate is subjected to a roller-rolling operation.

[0089] In this embodiment, the second aluminum foil base strip is pressed by a roller press, which improves the flatness of both sides of the second aluminum foil base strip, that is, effectively improves the flatness of the coating layer, thereby ensuring the pass rate of the negative electrode sheet, and thus effectively ensuring the product pass rate of the lithium battery.

[0090] Finally, the copper foil substrate after passing through the roller is die-cut to obtain multiple negative electrode sheets.

[0091] In this embodiment, a die-cutting machine is used to perform die-cutting operations on multiple negative electrode areas of the second aluminum foil base strip, so that multiple second aluminum foil base strips are cut into multiple negative electrode sheets, realizing the mass production of negative electrode sheets, improving the production efficiency of a single negative electrode sheet, and thus effectively improving the production efficiency of lithium batteries.

[0092] In one embodiment, after sequentially stacking the negative electrode, the separator, and the positive electrode to obtain a battery cell, the following step is further included:

[0093] The battery cell is then soldered with electrode tabs.

[0094] In this embodiment, the positive tab and negative tab are welded to the empty foil area for welding the positive tab and the empty foil area for welding the negative tab of the battery cell, respectively. The positive and negative tabs are connecting conductors inside and outside the battery, serving as conductive conductors during charging and discharging to ensure the normal operation of the lithium battery.

[0095] In one embodiment, after the electrode tab bonding operation on the battery cell, the following steps are further included:

[0096] The battery cell is processed to obtain a finished lithium battery.

[0097] In this embodiment, the specific steps for processing the battery cell to obtain the finished lithium battery are as follows:

[0098] First, the battery cell with the soldered tabs is encased in an aluminum-plastic film sleeve. This sleeve is a key material for lithium battery cell encapsulation; it's a high-strength, high-barrier multilayer composite material composed of various plastics, aluminum foil, and adhesives. Furthermore, the aluminum-plastic film sleeve possesses excellent barrier properties, electrolyte stability, cold-stamping formability, puncture resistance, and insulation. The aluminum-plastic film sleeve effectively prevents leakage of current and electrolyte from the lithium battery, ensuring a high product yield.

[0099] Secondly, a top-side sealing integrated machine is used to heat seal the top and sides of the aluminum-plastic film sleeve. Both top sealing and side sealing are to ensure the airtightness of the aluminum-plastic film sleeve, avoid affecting the subsequent processes, and thus ensure the production qualification rate of lithium batteries.

[0100] Secondly, an electrolyte injection operation is performed on the heat-sealed aluminum-plastic film sleeve. This involves injecting electrolyte into the aluminum-plastic film sleeve through its bottom, immersing the battery cell in the electrolyte. Then, the bottom of the aluminum-plastic film sleeve is sealed to ensure its airtightness and thus guarantee the stable chemical reaction within the sleeve.

[0101] Secondly, the aluminum-plastic film sleeve after liquid injection is subjected to a formation operation, that is, the positive and negative electrode materials inside the battery cell are activated by charging and discharging.

[0102] Secondly, high-temperature aging of the formed aluminum-plastic film sleeve can promote side reactions within the sleeve and also screen out substandard sleeves, thus effectively ensuring the production qualification rate of lithium batteries.

[0103] Secondly, the aluminum-plastic film sleeve after high-temperature aging is vented by puncturing it to create an vent hole, allowing the gas generated by the reaction to escape from the aluminum-plastic film sleeve, and then sealing the vent hole.

[0104] Finally, the aluminum-plastic film sleeve after degassing is trimmed and folded to obtain the finished lithium battery, which is the excess side of the aluminum-plastic film sleeve. The side is then folded up to complete the preparation of the lithium battery.

[0105] The following are some specific embodiments. It should be noted that the following embodiments do not exhaust all possible situations, and the materials used in the following embodiments are commercially available unless otherwise specified.

[0106] Example 1

[0107] The copper foil substrate is divided into multiple negative electrode areas, and coating is applied to each negative electrode area. The coated copper foil substrate is then passed through a roller, and finally die-cut to obtain multiple negative electrode sheets, thus preparing ViMe2SiO (Me2SiO). n The mass fraction of SiMe2Vi is 20%, and the mass fraction of Me3SiO (Me2SiO) is also present.m (MeHSiO) n A heat-dissipating adhesive is prepared by comprising 15% SiMe3, 0.01% OH-1-etyny1-1-cyclohexanol, 1% polyvinylidene fluoride, 15% alumina, and 20% aluminum hydroxide. An aluminum foil substrate is divided into multiple positive electrode regions. A first adhesive layer and a second adhesive layer are applied to both sides of each positive electrode region. The first adhesive layer is further divided into sequentially distributed regions: a positive electrode tab welding empty foil region, a first active material coating sub-layer coating region, a heat-dissipating empty foil region, and a second active material coating sub-layer coating region. Active material is applied to the first active material coating sub-layer region, the second active material coating sub-layer region, and the second adhesive layer to form the first active material coating sub-layer, the second active material coating sub-layer, and the second active material coating layer. The heat-dissipating adhesive is applied to the heat-dissipating empty foil region, and a heat-dissipating adhesive layer is formed after curing. The coated aluminum foil substrate is then subjected to a rolling operation, followed by die-cutting to obtain multiple positive electrode sheets. The negative electrode, separator, and positive electrode are sequentially stacked and stacked to obtain a battery cell. The battery cell is then welded with tabs, and the battery cell after the tabs are welded is processed to obtain a lithium battery with a capacity of 6000mAh.

[0108] Example 2

[0109] The copper foil substrate is divided into multiple negative electrode areas, and coating is applied to each negative electrode area. The coated copper foil substrate is then passed through a roller, and finally die-cut to obtain multiple negative electrode sheets, thus preparing ViMe2SiO (Me2SiO). n The mass fraction of SiMe2Vi is 50%, and that of Me3SiO (Me2SiO) is also present. m (MeHSiO) nA heat-dissipating adhesive is prepared by comprising 3% SiMe3, 0.1% OH-1-etyny1-1-cyclohexanol, 5% polyvinylidene fluoride, 40% alumina, and 10% aluminum hydroxide. An aluminum foil substrate is divided into multiple positive electrode regions. A first adhesive layer and a second adhesive layer are applied to both sides of each positive electrode region. The first adhesive layer is further divided into sequentially distributed regions: a positive electrode tab welding empty foil region, a first active material coating sub-layer region, a heat-dissipating empty foil region, and a second active material coating sub-layer region. Active material is applied to the first active material coating sub-layer region, the second active material coating sub-layer region, and the second adhesive layer to form the first active material coating sub-layer, the second active material coating sub-layer, and the second active material coating layer. The heat-dissipating adhesive is applied to the heat-dissipating empty foil region, and a heat-dissipating adhesive layer is formed after curing. The coated aluminum foil substrate is then subjected to a rolling operation, followed by die-cutting to obtain multiple positive electrode sheets. The negative electrode, separator, and positive electrode are sequentially stacked and stacked to obtain a battery cell. The battery cell is then welded with tabs, and the battery cell after the tabs are welded is processed to obtain a lithium battery with a capacity of 6000mAh.

[0110] Comparative Example 1

[0111] The copper foil substrate is divided into multiple negative electrode areas, and coating is applied to these areas. The coated copper foil substrate is then rolled and die-cut to obtain multiple negative electrode sheets. Similarly, the aluminum foil substrate is divided into multiple positive electrode areas, and coating is applied to these areas. The coated aluminum foil substrate is then rolled and die-cut to obtain multiple positive electrode sheets. The negative electrode sheets, separator, and positive electrode sheets are sequentially stacked to obtain a battery cell. Electrode tabs are then welded onto the battery cell, and the cell is further processed to obtain a 6000mAh lithium battery.

[0112] Comparative Example 2

[0113] The copper foil substrate is divided into multiple negative electrode areas, and coating is applied to these areas. The coated copper foil substrate is then rolled and die-cut to obtain multiple negative electrode sheets. Similarly, the aluminum foil substrate is divided into multiple positive electrode areas, and coating is applied to these areas. The coated aluminum foil substrate is then rolled and die-cut to obtain multiple positive electrode sheets. The negative electrode sheets, separator, and positive electrode sheets are sequentially stacked to obtain a battery cell. Electrode tabs are then welded onto the battery cell, and the cell is further processed to obtain a 6000mAh lithium battery.

[0114] Comparative Example 1 and Example 1 were subjected to triple-rate high-current discharge at 23±2℃, and the lithium batteries were thermally imaged to obtain... Figure 3 and Figure 4 and to Figure 3 and Figure 4 Temperature measurements were taken at points 1-9, and the results are shown in Table 1.

[0115] Figure 3 The thermal image of Comparative Example 1 after thermal imaging processing.

[0116] Figure 4 This is a thermal image of Example 1 after thermal imaging processing;

[0117] Table 1: Figure 3 and Figure 4 Temperature measurements were taken at points 1-9.

[0118]

[0119]

[0120] Examples 1-2 and Comparative Examples 1-2 were subjected to 1C charge-discharge cycle tests at 23±2℃, and the results are shown in Tables 2 and 3. Figure 3 .

[0121] Table 2: Comparative Examples 1-2 were subjected to 1C charge-discharge cycle tests at 23±2℃. The capacity measurement results and capacity retention rates are shown in Table 2.

[0122]

[0123] Table 3: Capacity measurement results and capacity retention rate of 1C charge-discharge cycle tests conducted at 23±2℃ in Examples 1-2.

[0124]

[0125] The cyclic test result curves of Examples 1-2 and Comparative Examples 1-2 under 1C charge-discharge cycle testing at 23±2℃ were obtained using the measurement data in Tables 2 and 3. Figure 5 .

[0126] The two lithium batteries of Example 1 and Comparative Example 1 were subjected to nail penetration tests.

[0127] Test method:

[0128] 1) The battery is charged to 4.2V at 25℃±5℃ using a constant current and constant voltage of 0.5C, with a cutoff current of 0.02C.

[0129] 2) After the battery is fully charged, let it stand for 1 to 4 hours in an environment of 25℃±5℃.

[0130] 3) Use A high-temperature resistant steel needle is inserted into the battery at a speed of 10-40 mm / s from a direction perpendicular to the battery, penetrating the largest surface of the battery. The steel needle remains inside the battery for 20 seconds.

[0131] Acceptance criteria: The battery should not catch fire or explode.

[0132] Test results: such as Figure 6 and Figure 7 As shown, Figure 6 This is a schematic diagram showing the results of the acupuncture test in Comparative Example 1. Figure 7 This is a schematic diagram of the results of the acupuncture test in Example 1.

[0133] From Table 1, Figure 3 and Figure 4 It can be seen that:

[0134] Compared to the lithium battery in Comparative Example 1 without thermal adhesive, the temperature of the same area of ​​the lithium battery cell in Example 1 of this application with thermal adhesive is significantly lower, and the temperature at each point is more uniform, that is, the lithium battery of this application has better heat dissipation performance.

[0135] From Table 2, Table 3 and Figure 5 It can be seen that:

[0136] Compared to the lithium batteries in Comparative Examples 1-2 that were not coated with thermal adhesive, the lithium batteries in Examples 1-2 of this application coated with thermal adhesive have better cycle performance.

[0137] Depend on Figure 6 and Figure 7 It can be seen that:

[0138] Compared to the lithium battery in Comparative Example 1 without thermal adhesive, the lithium battery in Example 1 of this application with thermal adhesive has better heat dissipation and safety performance.

[0139] In summary, the solution provided in this application can effectively improve the heat dissipation and cycle performance of lithium batteries, while also having good safety performance.

[0140] This application also provides a lithium battery, which is prepared using the lithium battery preparation method described in any of the above embodiments.

[0141] Please see Figures 8 to 10A lithium battery 10 according to one embodiment includes a core 400 and an aluminum-plastic film sleeve 200, the aluminum-plastic film sleeve 200 covering the core 400. The core 400 includes a negative electrode sheet 410, a separator 420, and a positive electrode sheet 430 stacked and wound together. The positive electrode sheet 430 includes an aluminum foil base strip 4310, a first active material coating layer 4320, a second active material coating layer 4330, and a positive electrode tab 4340. A first adhesive layer 4311 and a second adhesive layer 4312 are respectively disposed on both sides of the aluminum foil base strip 4310. The first active material coating layer 4320 and the second active material coating layer 4330 are respectively bonded to both sides of the aluminum foil base strip 4310. The first active material coating layer 4322 includes a first active material coating sublayer 4322 and a second active material coating sublayer 4322. The first adhesive layer 4311 has a positive electrode tab welding empty foil area 43112, a first active material coating sublayer coating area 43114, a heat dissipation empty foil area 43116, and a second active material coating sublayer coating area 43118 respectively. The positive electrode tab 4340 is welded to the positive electrode tab welding empty foil area 43112. The first active material coating sublayer 4322 is coated on the first active material coating sublayer coating area 43114, and the second active material coating sublayer 4324 is coated on the second active material coating sublayer coating area 43118. The positive electrode sheet 430 also includes a heat dissipation adhesive layer 4350, which is bonded to the heat dissipation empty foil area 43116 and also abuts against the separator 420.

[0142] In this embodiment, by providing a positive electrode tab welding empty foil area 43112, a first active material coating sub-layer coating area 43114, a heat dissipation empty foil area 43116, and a second active material coating sub-layer coating area 43118 in the first adhesive layer 4311, and coating the first active material coating sub-layer 4322 on the first active material coating sub-layer coating area 43114, coating the second active material coating sub-layer 4324 on the second active material coating sub-layer coating area 43118, and bonding the heat dissipation adhesive layer 4350 to the heat dissipation empty foil area 43116, and also resisting the separator 420, a heat dissipation adhesive layer 4350 is coated while ensuring the distribution of active material in the positive electrode sheet 430, so that the heat generated inside the core 400 during use of the lithium battery 10 is conducted away through the heat dissipation adhesive layer 4350, resulting in better overall temperature uniformity inside the core 400, which can significantly reduce the temperature of the lithium battery 10, thereby effectively optimizing the cycle performance of the lithium battery 10.

[0143] like Figure 10As shown, in one embodiment, the second adhesive layer 4312 is provided with a second active material coating area 43122. It can be understood that the second adhesive layer 4312 is located on the back side of the first adhesive layer 4311, that is, both sides of the aluminum foil base tape 4310 need to be coated with active material, so the second adhesive layer 4312 is provided with a second active material coating area 43122.

[0144] like Figure 10 As shown, in one embodiment, the second active material coating layer 4330 is coated on the second active material coating area 43122. It can be understood that since both sides of the aluminum foil substrate 4310 need to be coated with active material, the second active material coating layer 4330 is coated on the second active material coating area 43122 to ensure the normal use of the positive electrode 430.

[0145] like Figure 9 As shown, in one embodiment, the thickness of the positive electrode 430 is 40.5 mm.

[0146] like Figure 9 As shown, in one embodiment, the length of the positive electrode 430 is 1437 mm.

[0147] like Figure 9 As shown, in one embodiment, the width of the heat dissipation foil area 43116 is in a 1:10 ratio to the length of the positive electrode sheet 430. It should be noted that this 1:10 ratio of the width of the heat dissipation foil area 43116 to the length of the positive electrode sheet 430 means that the heat dissipation performance of the positive electrode sheet 430 can be improved without affecting its use. This allows heat inside the core 400 to be directly conducted away through the heat dissipation adhesive layer 4350, reducing the internal temperature of the core 400 and effectively improving the heat dissipation performance of the lithium battery 10, thereby effectively optimizing the cycle performance of the lithium battery 10.

[0148] like Figure 9 As shown, in one embodiment, the width of the positive electrode tab welding empty foil area 43112 is in a ratio of 1:10 to the length of the positive electrode sheet 430. It can be understood that the positive electrode tab 4340 serves as the medium for electrical conduction between the positive electrode sheet 430 and the external environment, ensuring the use of the lithium battery 10.

[0149] like Figure 9 As shown, in one embodiment, the width of the first active material coating sublayer coating area 43114 is in a ratio of 2:5 to the length of the positive electrode 430.

[0150] like Figure 9As shown, in one embodiment, the width of the second active material coating sublayer coating area 43118 is in a 2:5 ratio to the length of the positive electrode sheet 430. It can be understood that the heat dissipation foil area 43116 is disposed between the first active material coating sublayer coating area 43114 and the second active material coating sublayer coating area 43118. Without affecting the normal use of the lithium battery 10, the addition of the heat dissipation foil area 43116 improves the heat dissipation performance of the positive electrode sheet 430, thereby effectively improving the heat dissipation performance of the lithium battery 10 and thus effectively optimizing the cycle performance of the lithium battery 10.

[0151] like Figure 10 As shown, in one embodiment, the width of the second active material coating area 43122 is in a ratio of 9:10 to the length of the positive electrode 430.

[0152] Compared with the prior art, the present invention has at least the following advantages:

[0153] The lithium battery manufacturing method of this application comprises a first adhesive layer in a single positive electrode area with sequentially distributed positive electrode tab welding empty foil area, a first active material coating sub-layer coating area, a heat dissipation empty foil area, and a second active material coating sub-layer coating area. First, active material is coated onto the first active material coating sub-layer coating area, the second active material coating sub-layer coating area, and the second adhesive layer to form the first active material coating sub-layer, the second active material coating sub-layer, and the second active material coating layer. Next, a heat dissipation adhesive is applied to the heat dissipation empty foil area and, after curing, forms a heat dissipation adhesive layer, thereby forming a heat dissipation adhesive layer on the positive electrode. Finally, the negative electrode, separator, and positive electrode are sequentially stacked and laminated to obtain a battery cell. This means that when the internal temperature of the battery cell rises during use, the heat can be conducted to the outside through the heat dissipation adhesive layer, significantly reducing the internal temperature of the battery and effectively improving the heat dissipation performance of the lithium battery, thereby effectively optimizing the cycle performance of the lithium battery.

[0154] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a lithium battery, characterized in that, Includes the following steps: Preparation of negative electrode sheet; Preparation of positive electrode sheet; The negative electrode, the separator, and the positive electrode are sequentially stacked and a stacking operation is performed to obtain a battery cell; The specific operations for preparing the positive electrode sheet include the following steps: The aluminum foil base strip is divided into multiple positive electrode regions; A first adhesive layer and a second adhesive layer are provided on both sides of each positive electrode region; the first adhesive layer and the second adhesive layer are respectively located on both sides of a single positive electrode region; The first adhesive layer is divided into sequentially distributed positive electrode tab welding empty foil area, first active material coating sub-layer coating area, heat dissipation empty foil area and second active material coating sub-layer coating area; wherein, the ratio of the width of the heat dissipation empty foil area to the length of the positive electrode sheet is 1:

10. An active material is coated on the first active material coating sublayer coating area, the second active material coating sublayer coating area, and the second adhesive layer to form a first active material coating sublayer, a second active material coating sublayer, and a second active material coating layer; wherein, the ratio of the width of the first active material coating sublayer coating area to the length of the positive electrode sheet is 2:5, and the ratio of the width of the second active material coating sublayer coating area to the length of the positive electrode sheet is 2:

5. The heat dissipation adhesive is applied to the heat dissipation foil area, and a heat dissipation adhesive layer is formed after curing; The coated aluminum foil substrate is subjected to a rolling operation, and the rolled aluminum foil substrate is then die-cut to obtain multiple positive electrode sheets. The heat-dissipating adhesive comprises the following components in parts by weight: ViMe2SiO(Me2SiO) n SiMe2Vi 20~50 servings; Me3SiO (Me2SiO) m (MeHSiO) n SiMe3 3 to 15 servings; 0.01 to 0.1 parts of delay agent; 1 to 5 parts adhesive; 15 to 40 parts of the first thermally conductive flame retardant; 10 to 20 parts of the second thermally conductive flame retardant; The retarding agent is 1-ethynyl-1-cyclohexanol; The adhesive is polyvinylidene fluoride; The first thermally conductive flame retardant is aluminum oxide; The second thermally conductive flame retardant is aluminum hydroxide; The specific steps for preparing the negative electrode sheet include the following: Divide the copper foil baseband into multiple negative electrode regions; The coating process is performed on multiple negative electrode regions; The coated copper foil substrate is then subjected to a roller-rolling operation. The copper foil substrate after passing through the roller is die-cut to obtain multiple negative electrode sheets; After sequentially stacking the negative electrode, the separator, and the positive electrode to obtain a battery cell, the following steps are also included: The battery cell is then subjected to a tab bonding operation. After the electrode tab bonding operation on the battery cell, the following steps are also included: The battery cell is processed to obtain a finished lithium battery.

2. A lithium battery, characterized in that, The lithium battery is prepared using the method described in claim 1.

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