Battery, electrode assembly, and method of manufacturing the same

Abstract

This invention relates to the field of battery technology, specifically to a battery, an electrode assembly, and a method for fabricating the same. The electrode assembly includes a positive electrode and a negative electrode stacked together. Along the length of the electrode assembly, the length of the negative electrode is greater than the length of the positive electrode, forming a coating region between the positive electrode and two adjacent negative electrodes. An insulating layer is coated on the coating region, such that the insulating layer covers the outer edge of the positive electrode and exposes the outer edge of the negative electrode. This electrode assembly avoids the uneven current density caused by traditional thinning methods; it also prevents lithium ions from accumulating and depositing in the gaps during fast charging or later stages of cycling, reducing the probability of lithium deposition on the electrode and extending cycle life.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a battery, an electrode assembly, and a method for preparing the same. Background Technology

[0002] In the coating process of lithium-ion batteries, regardless of whether slot coating or blade coating is used, the minute deformations and vibrations of the mechanical system, as well as the instability of the slurry feeding, inevitably affect the consistency of the electrode thickness. Especially when producing long-distance electrodes, achieving absolute consistency in electrode thickness becomes extremely difficult. Without special processing methods to compensate for this thickness difference, the electrodes are prone to edge bursting during winding, which can disrupt the continuous operation of the battery production line, affecting production efficiency and output.

[0003] With increasing demands on battery cell performance, especially under conditions such as fast charging and late-cycle operation, the inconsistency in electrode thickness has become particularly important. The difference in thickness between the positive and negative electrodes leads to significant differences in the ion transport paths between them, which ultimately results in uneven current density distribution, causing uneven temperature distribution inside the battery cell. Excessive local temperature can also lead to increased internal resistance and lithium plating. Summary of the Invention

[0004] This invention provides an electrode assembly to solve the defect of lithium plating caused by uneven coating thickness in the prior art.

[0005] The present invention also provides a battery.

[0006] The present invention also provides a method for preparing an electrode assembly.

[0007] A first aspect of the present invention provides an electrode assembly, comprising: The positive and negative electrode sheets are stacked together, and along the length direction of the electrode assembly, the length of the negative electrode sheet is greater than the length of the positive electrode sheet, so as to form a coating area between the positive electrode sheet and two adjacent negative electrode sheets. An insulating layer is coated on the coating area such that the insulating layer covers the edge of the positive electrode and exposes the edge of the negative electrode.

[0008] According to one embodiment of the present invention, the width of the insulating layer is adapted to the width of the coating area along the thickness direction of the electrode assembly.

[0009] According to one embodiment of the present invention, along the thickness direction of the electrode assembly, the thickness of the insulating layer is equal to the thickness of the positive electrode film on the positive electrode sheet, and the thickness of the positive electrode film on the positive electrode sheet is equal to the thickness of the negative electrode film on the negative electrode sheet.

[0010] According to one embodiment of the present invention, along the length direction of the electrode assembly, the outer edge of the insulating layer is aligned with the outer edge of the negative electrode sheet; or, Along the length of the electrode assembly, the height of the outer edge of the insulating layer is less than the height of the outer edge of the negative electrode sheet.

[0011] According to one embodiment of the present invention, the insulating layer comprises a coated insulating coating; or, The insulating layer includes insulating tape adhered to the positive electrode sheet.

[0012] According to one embodiment of the present invention, the insulating coating is formed by drying and curing an insulating slurry containing a polymer binder and inorganic insulating particles.

[0013] According to one embodiment of the present invention, the inorganic insulating particles include alumina particles, and the polymer binder includes polyvinylidene fluoride.

[0014] A second aspect of the present invention provides a battery including the electrode assembly as described above.

[0015] A third aspect of the present invention provides a method for preparing an electrode assembly as described above, comprising: The positive electrode and the negative electrode are stacked to form a coating area between the positive electrode and two adjacent negative electrode sheets; The insulating layer is applied to the coating area such that it covers the outer edge of the positive electrode and exposes the outer edge of the negative electrode.

[0016] According to an embodiment of the present invention, the step of coating the insulating layer in the coating area includes: The insulating paste is applied to the edge of the positive electrode and then dried and cured.

[0017] According to the electrode assembly provided in the first aspect of the present invention, by filling the gaps with an insulating layer and adapting the length of the negative electrode to cover the thinned area, there are no gaps after the positive and negative electrodes are stacked. The transport path length of lithium ions between the positive and negative electrodes is consistent, avoiding excessively high local current density and reducing the problem of increased internal resistance of the electrode from the root, thereby improving the charging and discharging efficiency of the cell. It also prevents lithium ions from lingering in the gap area, significantly reducing the probability of lithium plating on the electrode surface. Simultaneously, the insulating layer covers the edge of the positive electrode, preventing poor lithium ion transport caused by thinning at the positive electrode edge, further reducing the risk of lithium plating and significantly extending the cycle life of the cell. Compared with the traditional overall insulation design, this electrode assembly eliminates gaps while ensuring the effective active area of ​​the negative electrode, ensuring that the cell capacity performance is not affected. It also ensures uniform heat generation and transfer in the positive and negative electrode reaction areas, without local high-temperature points. At the same time, the presence of the insulating layer reduces abnormal reaction heating at the positive electrode edge, further optimizing the cell temperature distribution and reducing the safety risks of cell bulging and fire caused by local high temperatures.

[0018] According to the battery provided in the second aspect of the present invention, the gapless design of the electrode assembly ensures uniform lithium-ion transport, reduces local internal resistance differences, and improves the battery's rate performance. Especially under fast charging conditions, it enables stable high-current charging and discharging, shortening charging time. It also reduces damage to internal battery components caused by lithium plating and localized high temperatures, delays the degradation of the positive electrode material and the pulverization of the negative electrode material, allowing the battery to maintain a high capacity after long-term cycling and extending its service life. The uniform temperature distribution and stable insulation performance reduce the risks of separator thermal shrinkage and electrolyte decomposition caused by localized high temperatures, lowering safety hazards such as battery fires and bulging, and improving safety in use.

[0019] According to the electrode assembly preparation method provided in the third aspect of the present invention, the steps of lamination, coating, and drying all use conventional equipment in lithium-ion battery production lines, without the need for additional specialized equipment. Only some process parameters need to be adjusted, reducing equipment investment costs for industrial applications. Furthermore, visual positioning and dimensional inspection can ensure precise coating area formation and proper insulation layer coating, resulting in no significant performance differences in mass-produced electrode assemblies, improving batch stability of the cells and reducing defect rates. Lamination and insulation layer coating can be seamlessly integrated, reducing electrode transfer and waiting time. Compared to traditional thinning processes, the overall production cycle is shortened, increasing production line capacity. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic front view of the positive electrode sheet provided by the present invention.

[0022] Figure 2 This is a schematic side view of the positive electrode sheet provided by the present invention.

[0023] Figure 3 This is a schematic front view of the negative electrode sheet provided by the present invention.

[0024] Figure 4 This is a schematic view of the first electrode assembly provided by the present invention.

[0025] Figure 5 This is a schematic view of the second electrode assembly provided by the present invention.

[0026] Figure 6 This is a schematic flowchart of the preparation method of the electrode assembly provided by the present invention.

[0027] Figure label: 100. Positive electrode sheet; 102. Negative electrode sheet; 104. Coated area; 106. Insulating layer; 108. Positive electrode film layer; 110. Negative electrode film layer. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] like Figures 1 to 5 As shown, a first aspect of the present invention provides an electrode assembly, comprising: The positive electrode 100 and negative electrode 102 are stacked together. Along the length direction of the electrode assembly, the length of the negative electrode 102 is greater than the length of the positive electrode 100, so as to form a coating area 104 between the positive electrode 100 and two adjacent negative electrode 102. An insulating layer 106 is coated on the coating area 104 so that the insulating layer 106 covers the outer edge of the positive electrode 100 and exposes the outer edge of the negative electrode 102.

[0030] According to the electrode assembly provided in the first aspect of the present invention, the insulating layer 106 fills the gaps and the negative electrode 102 is adapted to cover the thinned area, resulting in no gaps after the positive and negative electrodes are stacked. The transmission path length of lithium ions between the positive and negative electrodes is consistent, avoiding excessively high local current density and reducing the problem of increased internal resistance of the electrode from the root, thereby improving the charging and discharging efficiency of the cell. It also prevents lithium ions from lingering in the gap area, significantly reducing the probability of lithium plating on the electrode surface. Simultaneously, the insulating layer 106 covers the edge of the positive electrode, preventing poor lithium ion transmission caused by thinning at the positive electrode edge, further reducing the risk of lithium plating and significantly extending the cycle life of the cell. Compared with the traditional overall insulation design, this electrode assembly eliminates gaps while ensuring the effective active area of ​​the negative electrode 102, ensuring that the cell capacity performance is not affected. It also ensures uniform heat generation and transfer in the positive and negative electrode reaction areas, without local high-temperature points. At the same time, the presence of the insulating layer 106 reduces abnormal reaction heating at the positive electrode edge, further optimizing the cell temperature distribution and reducing safety risks such as cell bulging and fire caused by local high temperatures.

[0031] Please continue reading Figures 1 to 5 The electrode assembly provided in the first aspect of the present invention addresses the problem that thinning zones easily form at the edges of the electrode sheets during the coating process of lithium-ion batteries, leading to lithium plating caused by gaps between the positive and negative electrodes. By setting the edge insulation covering of the positive electrode sheet 100 and adjusting the length of the negative electrode sheet 102, the gaps are eliminated and the electrochemical reaction is ensured to proceed normally.

[0032] Specifically, the positive electrode 100 includes a positive current collector and a positive electrode film 108. The positive current collector is made of a highly conductive metal foil, and a continuous positive electrode film 108 is formed on its surface through a coating process. Due to factors such as slight deformation of the mechanical system and unstable slurry feeding during the coating process, a thinning area will form at the edge of the positive electrode film 108. If this area is not treated, it will form a gap when stacked with the negative electrode 102.

[0033] The negative electrode 102 includes a negative current collector and a negative electrode film 110. The negative current collector is made of highly conductive metal foil, and a continuous negative electrode film 110 is formed on its surface through a coating process. Along the length of the electrode assembly, the overall length of the negative electrode 102 is designed to be greater than the overall length of the positive electrode 100. Specifically, the length of the negative electrode 102 extending beyond the two ends of the positive electrode 100 just covers the thinning area at the edge of the positive electrode film 108, without exceeding the range required for the subsequent coating of the insulating layer 106.

[0034] When the positive electrode 100 and negative electrode 102 are alternately stacked in the order of negative electrode 102, positive electrode 100, and negative electrode 102, two adjacent negative electrode 102 are located on both sides of the positive electrode 100. Because the negative electrode 102 is longer, an annular coating area 104 is naturally formed around the edge of the positive electrode 100 between the edge of the positive electrode 100 and the two adjacent negative electrode 102. The width of this area is determined by the width of the thinning area of ​​the positive electrode film layer 108 and the length of the negative electrode 102 beyond the positive electrode 100, and it is only distributed at the edge of the positive electrode 100, without covering the effective active areas of the positive and negative electrode 102.

[0035] The insulating layer 106 is coated on the above-mentioned annular coating area 104. During the coating process, two core requirements must be met: First, the insulating layer 106 completely covers the edge of the positive electrode 100, including the thinning area of ​​the positive electrode film 108, to ensure that the gap formed by the thinning area is completely filled; Second, the insulating layer 106 does not cover the edge of the negative electrode 102, so that the edge of the negative electrode 102 remains exposed to avoid affecting the lithium-ion intercalation function of the negative electrode 102.

[0036] According to one embodiment of the present invention, the width of the insulating layer 106 is adapted to the width of the coating area 104 along the thickness direction of the electrode assembly.

[0037] In one embodiment of the present invention, the width of the insulating layer 106 is perfectly matched with the width of the coating area 104 along the thickness direction of the electrode assembly. Specifically, the width of the coating area 104 is determined by the width of the thinning region at the edge of the positive electrode 100 and the length of the negative electrode 102 extending beyond the positive electrode 100. The width of the insulating layer 106 is completely consistent with the width of the coating area 104, allowing only minor processing errors caused by equipment precision.

[0038] During production, the width of the coating area 104 is measured in real time using an online visual inspection system, and the coating parameters of the insulating layer 106 are adjusted synchronously to ensure that the insulating layer 106 completely covers the coating area 104, without any missed or over-coating. For mass-produced electrode assemblies, the widths of the coating area 104 and the insulating layer 106 can be pre-fixed through mold design to achieve width matching for all assemblies in the batch.

[0039] The width adaptation ensures that the insulating layer 106 completely covers the coating area 104, thoroughly filling the gaps formed by the thinning of the positive electrode edge, leaving no area that might create voids, and further guaranteeing the tightness of the positive and negative electrodes. The width of the insulating layer 106 does not exceed the coating area 104, and will not cover the effective active area of ​​the negative electrode sheet 102, ensuring that the negative electrode film layer 110 can fully participate in the electrochemical reaction and avoiding cell capacity loss due to obstruction by the insulating layer 106. There is no need to repeatedly adjust the coating width of the insulating layer 106, reducing manual calibration time, adapting to automated coating production lines, increasing the manufacturing cycle speed of electrode components, and reducing labor costs.

[0040] According to one embodiment of the present invention, along the thickness direction of the electrode assembly, the thickness of the insulating layer 106 is equal to the thickness of the positive electrode film 108 on the positive electrode 100, and the thickness of the positive electrode film 108 on the positive electrode 100 is equal to the thickness of the negative electrode film 110 on the negative electrode 102.

[0041] In one embodiment of the present invention, during the preparation of the positive electrode sheet 100, the thickness of the positive electrode film layer 108 formed on the surface of the positive electrode current collector is kept uniform by adjusting the parameters of the coating equipment, so as to ensure that there is no significant difference in the thickness of the positive electrode film layer 108 of the same batch of positive electrode sheets 100.

[0042] Similarly, when the negative electrode sheet 102 is prepared, the thickness of the positive electrode film layer 108 is used as a reference. By adjusting the parameters of the negative electrode coating equipment, the thickness of the negative electrode film layer 110 formed on the surface of the negative electrode current collector is made to be completely consistent with the thickness of the positive electrode film layer 108, so as to achieve precise matching of the thickness of the positive and negative electrode film layers 110.

[0043] When coating the insulating layer 106, its thickness should be controlled to be the same as that of the positive electrode film layer 108. If it is a coating-formed insulating coating, the coating thickness should be ensured to be consistent with that of the positive electrode film layer 108 by adjusting the nozzle height and slurry viscosity of the coating equipment; if it is an insulating tape, the tape specification with the same thickness as that of the positive electrode film layer 108 should be selected to ensure that there is no thickness deviation after pasting.

[0044] The insulating layer 106, the positive electrode film layer 108, and the negative electrode film layer 110 have the same thickness, ensuring that all contact surfaces of the stacked electrode assembly are flat, without local protrusions or depressions. This avoids interlayer compression or loosening caused by height differences, enhances the overall structural stability of the assembly, and reduces mechanical deformation during charging and discharging. The flat interlayer structure allows the electrolyte to be evenly distributed on the surface of each film layer, ensuring that the migration path length of lithium ions between the positive and negative electrodes is consistent. This avoids differences in reaction rates caused by local electrolyte enrichment or deficiency, ensuring that the electrochemical reaction proceeds uniformly on the electrode surface, and improving the capacity consistency and rate performance of the cell.

[0045] According to one embodiment of the present invention, along the length direction of the electrode assembly, the outer edge of the insulating layer 106 is aligned with the outer edge of the negative electrode 102; or, Along the length of the electrode assembly, the height of the outer edge of the insulating layer 106 is less than the height of the outer edge of the negative electrode 102.

[0046] like Figure 4 As shown, in one embodiment of the present invention, along the length direction of the electrode assembly, the outer edge of the insulating layer 106 is completely aligned with the outer edge of the negative electrode 102. Specifically, when the insulating layer 106 is coated, its outer edge is in the same vertical plane as the outer edge of the negative electrode 102, without any protruding or recessed step structure.

[0047] To achieve edge alignment, during the positive electrode 100 fabrication stage, positioning marks are pre-set on the positive current collector to ensure the precise coating position of the insulating layer 106; during the negative electrode 102 fabrication stage, the length of the negative electrode 102 is calibrated using a laser positioning system to ensure that the length of the negative electrode 102 exceeding that of the positive electrode 100 exactly matches the width of the insulating layer 106; during the lamination stage, the edge position is confirmed a second time using a visual recognition device to control the alignment error to a very small range.

[0048] Aligned edges ensure a smooth outer contour of the electrode assembly, allowing the separator to adhere tightly to the assembly surface. This prevents localized wrinkles in the separator caused by steps, ensuring effective isolation between the positive and negative electrodes and reducing the risk of separator damage. The smooth edge contour also allows the electrolyte to more evenly wet the positive and negative electrode films, preventing localized enrichment or loss of electrolyte due to steps. This ensures that the electrochemical reaction occurs uniformly on the electrode surface, improving the cell's rate performance. The stepless structure reduces localized stress concentration in the electrode assembly during charging and discharging, preventing assembly deformation and cell bulging caused by stress, and improving the structural stability of the cell during long-term use.

[0049] Or, such as Figure 5 As shown, along the length of the electrode assembly, the height of the outer edge of the insulating layer 106 is less than the height of the outer edge of the negative electrode 102.

[0050] Along the length of the electrode assembly, the outer edge of the insulating layer 106 is not flush with the outer edge of the negative electrode 102, forming a stepped structure where the edge of the insulating layer 106 is lower than the edge of the negative electrode 102. Specifically, the coating (or pasting) width of the insulating layer 106 is less than the length of the negative electrode 102 extending beyond the positive electrode 100, maintaining a certain distance between the outer edge of the insulating layer 106 and the outer edge of the negative electrode 102. The height difference between the edge of the insulating layer 106 and the edge of the negative electrode 102 is controlled to ensure that this height difference does not affect the normal adhesion of the separator and does not create new gaps.

[0051] The stepped structure provides space for the expansion of the electrode plates during the charging and discharging process, preventing deformation or detachment of the insulation layer 106 and the edge of the negative electrode 102 due to mutual compression during expansion, thus improving the structural stability of the electrode assembly during cycling. The recessed design of the insulation layer 106 creates a protruding protection at the edge of the negative electrode 102. Even if the separator experiences minor damage in the edge area, the edge of the negative electrode 102 can preferentially contact the separator, reducing the risk of short circuits caused by direct contact between the positive and negative electrodes.

[0052] According to one embodiment of the present invention, the insulating layer 106 comprises a coated insulating coating; or, The insulating layer 106 includes insulating tape adhered to the positive electrode 100.

[0053] In one embodiment of the present invention, the insulating layer 106 is provided in at least two different specific implementations: Method 1: Insulating coating formed by coating The polymer binder and inorganic insulating particles are mixed in a certain proportion, and a solvent is added and stirred to form a uniform insulating slurry. The insulating slurry is precisely coated onto the coating area 104 at the edge of the positive electrode 100 using a coating equipment. The coating thickness is consistent with the normal thickness of the positive electrode film layer 108. After coating, the positive electrode 100 is sent to a drying equipment and the solvent is removed by hot air drying, so that the slurry is cured to form a tightly adhered insulating coating. There are no gaps between the coating and the positive electrode 100 and the negative electrode 102.

[0054] The coated insulating coating is suitable for large-scale continuous production and can be integrated with existing positive electrode coating processes.

[0055] Method 2: Applying insulating tape Insulating tape with resistance to electrolyte corrosion and insulation properties is selected. After the positive electrode 100 is prepared, the insulating tape is directly pasted onto the coating area 104 at the edge of the positive electrode 100. During the pasting process, it is ensured that the tape completely covers the thinned area of ​​the positive electrode film 108 and that the outer edge is aligned with the edge of the negative electrode 102. The thickness of the tape is adapted to the normal thickness of the positive electrode film 108. After pasting, it is tightly adhered to the positive electrode 100 and the negative electrode 102 without bubbles or wrinkles.

[0056] The applied insulating tape is suitable for small-batch trial production or special specification electrode assemblies, without the need to adjust the coating equipment, thus meeting diverse production needs.

[0057] Both types of insulation layer 106 can block the direct electrical connection between the positive electrode edge and the negative electrode, avoiding leakage caused by the thinning of the positive electrode edge, ensuring the stability of the internal circuit of the electrode assembly, and not affecting the charging and discharging performance of the battery cell. Coating and bonding require no complex processes; on-site operators can master them with simple training, reducing the defect rate caused by process errors and lowering production management costs.

[0058] According to one embodiment of the present invention, the insulating coating is formed by drying and curing an insulating slurry containing a polymer binder and inorganic insulating particles; the inorganic insulating particles include alumina particles, and the polymer binder includes polyvinylidene fluoride.

[0059] In one embodiment of the present invention, the insulating coating is formed by drying and curing an insulating slurry. The insulating slurry comprises a polymer binder and inorganic insulating particles, wherein the inorganic insulating particles are alumina particles and the polymer binder is polyvinylidene fluoride (PVDF). During the preparation of the insulating slurry, PVDF powder and alumina particles are mixed in a preset ratio, a carbonate solvent is added, and the mixture is stirred using a high-speed stirring device until it is uniformly dispersed, forming a slurry without particle agglomeration. During coating, the slurry is uniformly coated onto the edge of the positive electrode 100 using a precision coating device, controlling the coating thickness to be consistent with the positive electrode film 108. During the drying and curing stage, a gradient heating method is used to remove the solvent, avoiding coating cracking caused by rapid drying, ultimately forming a dense insulating coating. This material combination possesses excellent resistance to electrolyte corrosion and insulation, and the adhesive strength of PVDF ensures that the coating is tightly bonded to the positive electrode 100 and the negative electrode 102, making it less prone to peeling off over long-term use.

[0060] Alumina particles possess excellent insulation properties, while polyvinylidene fluoride (PVDF) exhibits strong resistance to electrolyte corrosion. The combination of these two materials ensures that the insulating coating maintains stable insulation performance even after prolonged immersion in the electrolyte, preventing leakage between the positive and negative electrodes. The high adhesion of PVDF ensures a tight bond between the insulating coating and the positive electrode film 108, the positive current collector, and the negative electrode sheet 102. During electrode assembly stacking, winding, and cell charging and discharging, the coating is less prone to peeling or cracking, extending the lifespan of the electrode assembly. Neither alumina particles nor PVDF chemically reacts with the electrolyte or the positive and negative electrode active materials of the lithium-ion battery, preventing the generation of harmful substances that contaminate the electrolyte or consume lithium ions, thus ensuring stable cell capacity, voltage, and other performance characteristics.

[0061] A second aspect of the present invention provides a battery comprising the electrode assembly as described above.

[0062] According to the battery provided in the second aspect of the present invention, the gapless design of the electrode assembly ensures uniform lithium-ion transport, reduces local internal resistance differences, and improves the battery's rate performance. Especially under fast charging conditions, it enables stable high-current charging and discharging, shortening charging time. It also reduces damage to internal battery components caused by lithium plating and localized high temperatures, delays the degradation of the positive electrode material and the pulverization of the negative electrode material, allowing the battery to maintain a high capacity after long-term cycling and extending its service life. The uniform temperature distribution and stable insulation performance reduce the risks of separator thermal shrinkage and electrolyte decomposition caused by localized high temperatures, lowering safety hazards such as battery fires and bulging, and improving safety in use.

[0063] Specifically, the battery includes electrode components, a separator, tabs, and a packaging structure. The electrode components are the core reaction components of the battery. The positive electrode 100 is connected to the external positive electrode of the battery via a positive tab, and the negative electrode 102 is connected to the external negative electrode of the battery via a negative tab. The separator is sandwiched between the positive electrode 100 and the negative electrode 102, achieving ion conduction and electronic isolation. The packaging structure uses an aluminum-plastic film or a metal shell to completely encapsulate the electrode components, separator, and tabs. Before packaging, electrolyte is injected into the battery, fully wetting the positive electrode film layer 108, the negative electrode film layer 110, and the separator, forming a chargeable and dischargeable electrochemical system. The gapless design of the electrode components ensures that all layers inside the battery are tightly bonded, and the electrolyte is evenly distributed without localized dry or over-accumulated areas, ensuring stable battery operation.

[0064] like Figure 6 As shown, a third aspect of the present invention provides a method for preparing an electrode assembly as described above, comprising: Step 10: The positive electrode 100 and the negative electrode 102 are stacked to form a coating area 104 between the positive electrode 100 and two adjacent negative electrode 102. Step 20: Apply an insulating layer 106 to the coating area 104 so that the insulating layer 106 covers the outer edge of the positive electrode 100 and exposes the outer edge of the negative electrode 102.

[0065] According to the electrode assembly preparation method provided in the third aspect of the present invention, the steps of lamination, coating, and drying all use conventional equipment in lithium-ion battery production lines, without the need for additional specialized equipment. Only some process parameters need to be adjusted, reducing equipment investment costs for industrial applications. Furthermore, visual positioning and dimensional inspection can ensure precise formation of the coating area 104 and proper coating of the insulating layer 106, resulting in no significant performance differences in mass-produced electrode assemblies, improving batch stability of the cells, and reducing defect rates. The lamination and coating of the insulating layer 106 can be seamlessly connected, reducing electrode transfer and waiting time. Compared to traditional thinning processes, the overall production cycle is shortened, increasing production line capacity.

[0066] Please continue reading Figure 6In step 10, firstly, a positive electrode 100 and a negative electrode 102 are prepared respectively: the positive electrode 100 forms a positive electrode film layer 108 on the surface of the positive current collector through a coating process, and the negative electrode 102 forms a negative electrode film layer 110 on the surface of the negative current collector through a coating process, ensuring that the length of the negative electrode 102 is greater than the length of the positive electrode 100. Subsequently, the positive electrode 100 and the negative electrode 102 are alternately stacked, with two adjacent negative electrode 102 located on both sides of the positive electrode 100. Because the negative electrode 102 is longer, a coating area 104 is naturally formed between the edge of the positive electrode 100 and the two adjacent negative electrode 102. The stacking position is calibrated by a visual positioning device to ensure that the coating area 104 uniformly surrounds the edge of the positive electrode 100.

[0067] In step 20, the form of the insulating layer 106 is selected according to production requirements: if an insulating coating is selected, the insulating slurry is applied to the coating area 104 using a coating equipment, and then sent to a drying equipment for hot air drying to solidify the slurry and form an insulating coating; if insulating tape is selected, the tape is directly pasted onto the coating area 104, ensuring that the tape adheres tightly without air bubbles. After coating is completed, the position and size of the insulating layer 106 are confirmed using a dimensional inspection device to ensure that it covers the edge of the positive electrode 100 but does not cover the edge of the negative electrode 102, ultimately forming a complete electrode assembly.

[0068] According to an embodiment of the present invention, the step of coating an insulating layer 106 in the coating area 104 includes: The insulating paste is applied to the edge of the positive electrode 100 and then dried and cured.

[0069] In one embodiment of the present invention, the coating step of the insulating coating is refined, specifically: The polymer binder and inorganic insulating particles are mixed in a certain proportion, and a solvent is added. The mixture is stirred until it is homogeneous through a high-speed disperser to form an insulating slurry with no particle agglomeration and moderate viscosity. The temperature is controlled during the stirring process to prevent the solvent from evaporating too quickly.

[0070] The stacked positive electrode 100 and negative electrode 102 are fixed on the worktable of the coating equipment. The position and range of the coating area 104 are determined by the visual positioning device. The coating equipment is started and the insulating slurry is precisely coated onto the coating area 104 through the nozzle. During the coating process, the nozzle moving speed and the amount of slurry dispensed are controlled to ensure that the coating thickness is uniform and consistent with the normal thickness of the positive electrode film layer 108, without any missed coating or accumulation.

[0071] The components coated with the slurry are sent into a drying oven and dried using a gradient heating method: first, most of the solvent is removed at a lower temperature, and then the temperature is gradually increased to remove the residual solvent, so as to avoid cracking of the coating due to rapid drying; after drying, the components are naturally cooled to room temperature to allow the insulating coating to be fully cured and tightly bonded to the positive electrode 100 and the negative electrode 102.

[0072] Gradient drying prevents coating cracking, ensuring a dense, non-porous insulating coating that prevents insulation failure during long-term use and guarantees the insulation stability of the electrode assembly. Through nozzle control and visual positioning, the insulating slurry precisely covers the coating area 104, resulting in high consistency in coating size and position during mass production, reducing manual adjustment time and improving production efficiency. The drying and curing process enhances the adhesion between the insulating coating and the positive electrode 100, preventing the coating from easily detaching during subsequent cell assembly and charging / discharging processes, thus extending the lifespan of the electrode assembly.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrode assembly, characterized in that, include: The positive and negative electrode sheets are stacked together, and along the length direction of the electrode assembly, the length of the negative electrode sheet is greater than the length of the positive electrode sheet, so as to form a coating area between the positive electrode sheet and two adjacent negative electrode sheets. An insulating layer is coated on the coating area such that the insulating layer covers the outer edge of the positive electrode and exposes the outer edge of the negative electrode.

2. The electrode assembly according to claim 1, characterized in that, Along the thickness direction of the electrode assembly, the width of the insulating layer is adapted to the width of the coating area.

3. The electrode assembly according to claim 1, characterized in that, Along the thickness direction of the electrode assembly, the thickness of the insulating layer is equal to the thickness of the positive electrode film on the positive electrode sheet, and the thickness of the positive electrode film on the positive electrode sheet is equal to the thickness of the negative electrode film on the negative electrode sheet.

4. The electrode assembly according to claim 1, characterized in that, Along the length of the electrode assembly, the outer edge of the insulating layer is aligned with the outer edge of the negative electrode sheet; or, Along the length of the electrode assembly, the height of the outer edge of the insulating layer is less than the height of the outer edge of the negative electrode sheet.

5. The electrode assembly according to any one of claims 1 to 4, characterized in that, The insulating layer includes a coated insulating layer; or, The insulating layer includes insulating tape adhered to the positive electrode sheet.

6. The electrode assembly according to claim 5, characterized in that, The insulating coating is formed by drying and curing an insulating slurry containing polymer binders and inorganic insulating particles.

7. The electrode assembly according to claim 6, characterized in that, The inorganic insulating particles include alumina particles, and the polymer binder includes polyvinylidene fluoride.

8. A battery, characterized in that, Includes the electrode assembly as described in any one of claims 1 to 7.

9. A method for preparing an electrode assembly as described in any one of claims 1 to 7, characterized in that, include: The positive electrode and the negative electrode are stacked to form a coating area between the positive electrode and two adjacent negative electrode sheets; The insulating layer is applied to the coating area such that it covers the outer edge of the positive electrode and exposes the outer edge of the negative electrode.

10. The preparation method according to claim 9, characterized in that, The step of coating the insulating layer in the coating area includes: The insulating paste is applied to the edge of the positive electrode and then dried and cured.

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