All-tab roll core applying composite current collector, preparation method of all-tab roll core and all-tab battery

Abstract

The invention discloses a full-tab roll core applying a composite current collector, a preparation method of the full-tab roll core and a full-tab battery, the preparation method comprises the following steps: S1, preparing a positive pole piece and a negative pole piece, the positive pole piece comprises a positive composite current collector and a positive active material layer, and the negative pole piece comprises a negative composite current collector and a negative active material layer; at least one side of the positive pole composite current collector is provided with a positive pole blank area which is not coated with a positive pole active material, the negative pole piece comprises a negative pole composite current collector and a negative pole active material layer, and at least one side of the negative pole composite current collector is provided with a negative pole blank area which is not coated with a negative pole active material; s2, stacking and winding the positive pole piece, the diaphragm and the negative pole piece into a winding core; and S3, coating at least one side of the two sides in the central axis direction of the roll core with a conductive adhesive, so that the conductive layers of the positive electrode composite current collector and / or the negative electrode composite current collector are conducted. The metal films on the two sides of the composite current collector can be conducted without externally connecting traditional foils, and the problem that the energy density is reduced due to the fact that the weight of the battery is increased is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a full-tab winding core using a composite current collector, a preparation method thereof, and a full-tab battery. Background Art

[0002] Taking Tesla's 4680 large cylindrical full-ear battery as an example, the full-ear battery has the advantages of high energy density, high safety and low impedance, so it quickly attracted the attention of the industry. Full-ear batteries are usually cylindrical batteries. Their manufacturing process usually involves cross-cutting the blank areas of the current collector on both sides of the positive and negative pole pieces that are not coated with active materials, cutting the blank areas into multiple small pieces, and then stacking and winding the positive pole pieces, diaphragms, and negative pole pieces to form a winding core, and then pressing and overlapping the blank areas of the positive and negative pole pieces to form a full-ear structure (usually called a flattening process), and then sequentially encapsulating, shelling, current collector plate welding, lid closing, peripheral welding, helium inspection, and chemical composition. The purpose of cutting the blank area into multiple small pieces is to facilitate flattening. In some full-ear batteries, the blank area will not be cut to save steps.

[0003] With the vigorous development of the new energy industry, the market has also put forward higher requirements for the safety and energy density of lithium-ion batteries. Based on this, composite current collectors with better performance have emerged in the industry. The composite current collector generally uses a polymer base film as the middle layer, and a metal film is arranged on both sides of the polymer base film to form a sandwich-like structure. However, since the middle layer of the composite current collector is an insulating polymer base film, when multiple composite current collector tabs are welded, the metal films on both sides cannot be directly connected. At present, one of the existing ways to make the metal films on both sides of the composite current collector conductive is the transfer welding technology. The specific steps include: placing a layer of traditional metal foil on both sides of the thickness direction of the composite current collector, and then welding the composite current collector and the traditional metal foil together by ultrasonic welding, so that the metal films on both sides of the composite current collector are conductive. However, the transfer welding technology is applied to full-tab batteries, the process is complicated, the cost is high, and the weight and space occupied by the traditional metal foil will increase the overall weight of the battery, resulting in a decrease in the battery energy density. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings, the purpose of the present invention is to provide a full-tab roll core using a composite current collector, a preparation method thereof, and a full-tab battery, which can achieve conduction of the metal films on both sides of the composite current collector without the need for external traditional foil materials, thereby avoiding the problem of decreased energy density due to increased battery weight.

[0005] In order to achieve the above object, one of the technical solutions adopted by the present invention is: a method for preparing a full-electrode tab core using a composite current collector, comprising the following steps: S1. Prepare a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode composite current collector and a positive electrode active material layer arranged on at least one side of the positive electrode composite current collector in the thickness direction, and at least one side of the positive electrode composite current collector in the width direction is provided with a positive electrode blank area not coated with a positive electrode active material; the negative electrode sheet comprises a negative electrode composite current collector and a negative electrode active material layer arranged on at least one side of the negative electrode composite current collector in the thickness direction, and at least one side of the negative electrode composite current collector in the width direction is provided with a negative electrode blank area not coated with a negative electrode active material; the positive electrode composite current collector and the negative electrode composite current collector both comprise a base film and a conductive layer arranged on both sides of the base film; S2, stacking the positive electrode sheet, the separator, and the negative electrode sheet and winding them into a winding core; along the central axis direction of the winding core, the positive electrode blank area and the negative electrode blank area are respectively located on both sides of the winding core; S3. Coating a conductive adhesive on at least one of the two sides of the winding core in the direction of the central axis to make the conductive layers on both sides of the positive electrode composite current collector conductive and / or the conductive layers on both sides of the negative electrode composite current collector conductive.

[0006] The beneficial effects of the preparation method of the present invention are: 1. The positive electrode blank area and the negative electrode blank area are respectively set in the width direction of the positive electrode composite current collector and the negative electrode composite current collector through step S1, which makes it possible to directly use the positive electrode blank area and the negative electrode blank area as the pole ear; through step S2, winding into a winding core, so that the positive electrode blank area and the negative electrode blank area can be respectively located on both sides of the central axis of the winding core; and then through step S3, a conductive glue is coated on at least one side of the central axis direction of the winding core, so that the conductive layer and the positive electrode blank area / negative electrode blank area on the same side of the winding core along the central axis direction can be mutually conductive due to the effect of the conductive glue, and then the positive electrode blank area or the negative electrode blank area coated with the conductive glue can be directly used as the pole ear, thereby avoiding the increase of the battery weight caused by the external pole ear and ensuring the energy density of the battery.

[0007] 2. In step S3, the conductive glue is coated in a simple manner, which can ensure that the conductive glue is in more comprehensive contact with the composite current collector and has lower resistance, thereby improving the rate performance of the battery; some existing solutions use punching to achieve the conduction of the metal films on both sides of the composite current collector. Compared with the punching method, the coating method can effectively avoid the stress concentration problem caused by punching, avoid the positive electrode sheet or the negative electrode sheet from breaking during the production and winding process, and the process is simpler. In addition, the coating of the conductive glue can further enhance the flexibility and mechanical properties of the tab area, reduce the safety risks caused by tab breakage, and improve the safety of the battery.

[0008] 3. The composite current collector causes the temperature of the full-tab battery to rise during use due to the polymer base film in the middle. The setting of the conductive glue can improve thermal management, conduct the heat generated in the tab area more effectively, and reduce the overheating problem of the battery during high-rate charging and discharging.

[0009] Further, in step S3, after the conductive adhesive is applied, a post-application treatment is required, and the post-application treatment includes sequentially preheating and drying, heating and drying, and cooling and drying the core after the conductive adhesive is applied, so that the conductive adhesive is solidified on the core. The core is dried at different temperatures by preheating and drying, heating and drying, and cooling and drying, so that the conductive adhesive can be completely solidified on the core, so as to improve the bonding strength between the conductive adhesive and the core.

[0010] Specifically, the preheating and drying temperature is 50-80° C., the heating and drying temperature is 70-90° C., and the cooling and drying temperature is 30-50° C. The conductive adhesive on both sides of the core is initially solidified by preheating and drying, and further solidified by heating and drying, and finally cooled and dried to cool and completely solidify the conductive adhesive.

[0011] Furthermore, in step S1, the widths of the positive electrode blank area and the negative electrode blank area are both 3-80 mm.

[0012] Furthermore, after step S3, a short circuit test is performed on the core to detect whether there is a short circuit between the positive and negative electrodes of the core. During the test, a voltage of 50-300V is applied to the core through a safety instrument, and then the leakage current of the core is detected to be within the specified range to determine whether there is a short circuit between the positive and negative electrodes of the core. It should be noted that if the core is tested to have a short circuit, the short-circuited core will be directly scrapped.

[0013] Furthermore, the conductive adhesive includes a conductive metal and a binder, wherein the conductive metal includes at least one of gold, silver, copper, and aluminum, and the binder includes at least one of polyvinyl alcohol, polytetrafluoroethylene, sodium carboxymethyl cellulose, polyvinylidene fluoride, and styrene-butadiene rubber. Furthermore, the fineness of the conductive adhesive is 10-100 μm, the viscosity is 7000-15000 mPa·s, and the solid content is 40-70%. By adjusting the fineness, viscosity, and solid content of the conductive adhesive, the bonding effect between the conductive adhesive and the metal film layer on both sides of the composite current collector can be further increased.

[0014] Further, step S1 includes slurry treatment, coating treatment, rolling treatment, and slitting treatment, wherein the slurry treatment includes preparing positive electrode active materials and negative electrode active materials respectively, the coating treatment includes coating the positive electrode active materials and the negative electrode active materials on the positive electrode composite collector and the negative electrode composite collector respectively and drying them, the rolling treatment includes rolling the positive electrode composite collector and the negative electrode composite collector after the coating treatment to a set thickness; the slitting treatment includes slitting the positive electrode composite collector and the negative electrode composite collector after the rolling treatment to a set width to obtain positive electrode sheets and negative electrode sheets.

[0015] Furthermore, during the homogenization treatment, the active material in the positive electrode active material includes at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide, and nickel cobalt lithium manganese oxide, and the positive electrode active material has a fineness of 10-100 μm, a viscosity of 3000-15000 mPa·s, and a solid content of 40-75%.

[0016] Furthermore, during the homogenization treatment, the active material in the negative electrode active material includes at least one of silicon-based materials, carbon microspheres, hard carbon, soft carbon and lithium metal, the fineness of the negative electrode active material is 10-100 μm, the viscosity is 2000-10000 mPa·s, and the solid content is 40-60%.

[0017] The second technical solution adopted by the present invention is: a full-ear winding core using a composite current collector, which is prepared by any of the preparation methods described above.

[0018] The beneficial effects of the full-tab winding core of the present invention are: dividing the positive electrode blank area / negative electrode blank area on the composite current collector, and coating the positive electrode blank area / negative electrode blank area with conductive glue, so that the conductive layers on the same side of the composite current collector can be mutually conductive, thereby providing the possibility of directly using the composite current collector as the tab; and directly using the composite current collector as the tab does not require welding an external aluminum foil as a transfer tab, which can simplify the process while avoiding the problem of reduced energy density of the battery cell.

[0019] The third technical solution adopted by the present invention is: a full-tab battery, including the full-tab core described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of stacking the positive electrode sheet, the separator, and the negative electrode sheet according to an embodiment of the present invention; Figure 2 A schematic structural diagram of a winding core according to an embodiment of the present invention; Figure 3 It is a schematic diagram of the structure of the winding core tab after being flattened according to an embodiment of the present invention.

[0021] In the figure: 1-positive electrode composite current collector; 2-positive electrode active material layer; 3-positive electrode blank area; 4-negative electrode composite current collector; 5-negative electrode active material layer; 6-negative electrode blank area; 7-diaphragm; 8-winding core; 9-ear. DETAILED DESCRIPTION The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0022] Example See attached Figure 1-3 As shown, a method for preparing a full-electrode tab core using a composite current collector of the present invention comprises the following steps: S1. Prepare a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode composite current collector 1 and a positive electrode active material layer 2 arranged on at least one side of the positive electrode composite current collector 1 in a thickness direction, and a positive electrode blank area 3 not coated with a positive electrode active material is arranged on at least one side of the positive electrode composite current collector 1 in a width direction, and the negative electrode sheet comprises a negative electrode composite current collector 4 and a negative electrode active material layer 5 arranged on at least one side of the negative electrode composite current collector 4 in a thickness direction, and a negative electrode blank area 6 not coated with a negative electrode active material is arranged on at least one side of the negative electrode composite current collector 4 in a width direction; both the positive electrode composite current collector 1 and the negative electrode composite current collector 2 comprise a base film and a conductive layer arranged on both sides of the base film; S2, stacking the positive electrode sheet, the separator 7, and the negative electrode sheet and winding them into a winding core 8; along the central axis direction of the winding core, the positive electrode blank area 3 and the negative electrode blank area 6 are respectively located on both sides of the winding core 8; S3. Coating a conductive adhesive on at least one of the two sides of the winding core in the direction of the central axis to make the conductive layers on both sides of the positive composite current collector 1 conductive and / or the conductive layers on both sides of the negative composite current collector 4 conductive.

[0023] Through step S1, the positive electrode blank area 3 and the negative electrode blank area 6 are respectively set in the width direction of the positive electrode composite current collector 1 and the negative electrode composite current collector 4, which makes it possible to directly use the positive electrode blank area 3 and the negative electrode blank area 6 as the pole ear; through step S2, winding into a winding core 8, so that the positive electrode blank area 3 and the negative electrode blank area 6 can be located on both sides of the central axis of the winding core 8 respectively; and then through step S3, a conductive glue is coated on at least one side of the central axis direction of the winding core 8, so that the conductive layer, the positive electrode blank area 3 / the negative electrode blank area 6 on the same side of the winding core 8 along the central axis direction can be mutually conductive due to the effect of the conductive glue, and then the positive electrode blank area 3 or the negative electrode blank area 6 coated with the conductive glue can be directly used as the pole ear, avoiding the increase of the battery weight caused by the external pole ear, and ensuring the energy density of the battery. Specifically, step S1 includes the following steps: S11. Homogenization treatment: prepare positive electrode active materials and negative electrode active materials respectively; wherein, the active material in the positive electrode active material includes at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide, and nickel cobalt manganese oxide, the fineness of the positive electrode active material is 10-100 μm, the viscosity is 3000-15000 mPa·s, and the solid content is 40-75%; the active material in the negative electrode active material includes at least one of silicon-based materials, carbon microspheres, hard carbon, soft carbon and lithium metal, the fineness of the negative electrode active material is 10-100 μm, the viscosity is 2000-10000 mPa·s, and the solid content is 40-60%.

[0024] It can be understood that the fineness of the positive electrode active material includes but is not limited to 10μm, 20μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm; the viscosity of the positive electrode active material includes but is not limited to: 3000mPa·s, 5000mPa·s, 7000mPa·s, 9000mPa·s, 11000mPa·s, 13000mPa·s, 15000mPa·s; the solid content of the positive electrode active material includes but is not limited to: 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%; the fineness of the negative electrode active material includes but is not limited to 10μm, 20μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm; the viscosity of the negative electrode active material includes but is not limited to: 2000mPa·s, 4000mPa·s s, 6000mPa·s, 8000mPa·s, 10000mPa·s; the solid content of the negative electrode active material includes but is not limited to: 40%, 45%, 50%, 55%, 60%.

[0025] S12, coating treatment: coating the positive electrode active material and the negative electrode active material on the positive electrode composite current collector 1 and the negative electrode composite current collector 4 respectively and drying them, so as to form a positive electrode active material layer 2 and a negative electrode active material layer 5 on the positive electrode composite current collector 1 and the negative electrode composite current collector 4 respectively; when coating the positive electrode active material, coating the positive electrode active material on both sides of the positive electrode composite current collector 1 along the thickness direction in a continuous coating manner, and forming a positive electrode blank area 3 not coated with the positive electrode active material in the edge area of ​​the positive electrode composite current collector 1 along the width direction; when coating the negative electrode active material, coating the negative electrode active material on both sides of the negative electrode composite current collector 4 along the thickness direction in a continuous coating manner, and forming a negative electrode blank area 6 not coated with the negative electrode active material in the edge area of ​​the negative electrode composite current collector 4 along the width direction; S13, rolling treatment: using a rolling device to roll the positive electrode composite current collector 1 and the negative electrode composite current collector 4 to a set thickness.

[0026] S14, cutting process: the positive electrode composite current collector 1 and the negative electrode composite current collector 4 after the rolling process are cut into set widths by physical cutting or laser cutting, so as to obtain the required positive electrode sheets and negative electrode sheets.

[0027] The tab is a carrier for energy transfer between the battery and the outside world, and the positive electrode active material and the negative electrode active material are used to store or release lithium ions. In step S1, the composite current collector is used as a carrier of the positive electrode active material and the negative electrode active material, which can reduce the weight of the battery while ensuring the energy density of the battery; the positive electrode active material and the negative electrode active material are transferred to the corresponding composite current collector through coating treatment to realize the production of the positive and negative electrodes of the battery, and a blank area is reserved in the edge area of ​​the composite current collector, so that the blank area (positive electrode blank area or negative electrode blank area) can be directly made into a tab in the future.

[0028] Furthermore, in step S1, the area of ​​the positive electrode composite current collector 1 coated with the positive electrode active material is larger than the area of ​​the positive electrode blank area 3 not coated with the positive electrode active material, and the area of ​​the negative electrode composite current collector 4 coated with the negative electrode active material is larger than the area of ​​the negative electrode blank area 6 not coated with the negative electrode active material. And the widths of the positive electrode blank area 3 and the negative electrode blank area 6 are both 3 to 80 mm. The area of ​​the positive electrode composite current collector 1 coated with the positive electrode active material is limited to be larger than the area of ​​the positive electrode blank area 3, and the area of ​​the negative electrode composite current collector 4 coated with the negative electrode active material is limited to be larger than the area of ​​the negative electrode blank area 6, so that after the conductive glue is coated on the positive electrode blank area 3 and the negative electrode blank area 6, the weight of the winding core 8 will not increase significantly, so as to minimize the impact on the battery energy density caused by the coating of the conductive glue.

[0029] In some embodiments, in step S2, when stacking the positive electrode sheet, the separator 7, and the negative electrode sheet, the positive electrode sheet and the negative electrode sheet are arranged alternately along the winding direction perpendicular to the winding core, so that the positive electrode sheet on one side protrudes from the negative electrode sheet, and the negative electrode sheet on the other side protrudes from the positive electrode sheet. This arrangement is to enable the positive electrode blank area 3 on the side where the positive electrode sheet protrudes from the negative electrode sheet to form a positive electrode ear that is conductive with the positive electrode sheet, and the negative electrode blank area 6 on the side where the negative electrode sheet protrudes from the positive electrode sheet to form a negative electrode ear that is conductive with the negative electrode sheet.

[0030] In addition, the size of the separator 7 along the winding direction of the winding core 8 should be larger than the size of the positive electrode sheet and the negative electrode sheet along the winding direction of the winding core. The size of the separator 7 along the central axis of the winding core 8 should be smaller than the size of the positive electrode sheet and the negative electrode sheet along the central axis of the winding core, and larger than the size of the positive active material layer 2 and the negative active material layer 5 along the central axis of the winding core 8. This arrangement enables the separator 7 to completely cover the positive active material layer 2 and the negative active material layer 5, ensuring the separation of the positive active material and the negative active material.

[0031] In some embodiments, step S3 includes the following steps: S31. Prepare conductive glue: The conductive glue includes conductive metal and binder. The conductive metal includes at least one of gold, silver, copper and aluminum. The binder includes at least one of polyvinyl alcohol, polytetrafluoroethylene, sodium carboxymethyl cellulose, polyvinylidene fluoride and styrene-butadiene rubber. The conductive metal and the binder are fully stirred to obtain the conductive glue. Furthermore, the fineness of the conductive glue is 10-100 μm, the viscosity is 7000-15000 mPa·s, and the solid content is 40-70%. By adjusting the fineness, viscosity and solid content of the conductive glue, the bonding effect between the conductive glue and the metal film layer on both sides of the composite current collector can be further increased.

[0032] It can be understood that the fineness of the conductive adhesive includes but is not limited to 10μm, 20μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, and 100μm; the viscosity of the conductive adhesive includes but is not limited to: 7000mPa·s, 9000mPa·s, 11000mPa·s, 13000mPa·s, and 15000mPa·s; the solid content of the conductive adhesive includes but is not limited to: 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75%.

[0033] S32, apply conductive glue; transfer the prepared conductive glue to a storage tank and keep the conductive glue circulating by pumping to avoid precipitation of the conductive glue in the storage tank; transfer the conductive glue in the storage tank to the glue roller by quantitative suction, and evenly disperse the conductive glue on the glue roller by a disc scraper, and control the thickness of the conductive glue on the glue roller to be 1 to 3 times the thickness of the positive electrode (or negative electrode); transport the core to the glue application position of the glue roller in a vertical or horizontal direction, so that one side of the core can face the glue application surface of the glue roller; drive the glue roller to rotate back and forth through the carrier plate, so that the conductive glue on the glue roller can be applied to the end of the core. on the surface; since the core is wound, therefore, when the glue roller coats the conductive glue along the end surface of the core, the glue roller can squeeze onto the end surface of the core, so that the conductive glue can penetrate into the positive blank area / negative blank area along the winding gap, so that the end surface of the positive blank area / negative blank area (that is, the side of the core facing the glue roller) and both sides of the positive blank area / negative blank area can be coated with the conductive glue, so as to realize the conduction of the conductive layer on both sides of the positive blank area / negative blank area through the conductive glue, so as to form a positive electrode ear or a negative electrode ear; when the glue coating is completed on one end surface of the core, the core is flipped 180° to coat the other end surface of the core with glue.

[0034] S33, post-gluing treatment: After the conductive glue is coated on both sides of the core 8, the core 8 is preheated and dried, heated and dried, and cooled and dried in sequence to allow the conductive glue to completely solidify on the two end faces of the core. Among them, the temperature of preheating and drying is 50~80℃, the temperature of heating and drying is 70~90℃, and the temperature of cooling and drying is 30~50℃. The glue on both sides of the core can be initially solidified by preheating and drying, and then the glue is further condensed by heating and drying, and finally the glue is cooled and completely solidified by cooling and drying. The core is dried at different temperatures by preheating and drying, heating and drying, and cooling and drying, so that the conductive glue can be completely solidified on the core to improve the bonding strength between the conductive glue and the core.

[0035] In some embodiments, after step S3, a short-circuit test is also performed on the core to detect whether the positive and negative poles of the core are short-circuited. During the test, a voltage of 50-300V is applied to the core through a safety instrument, and then the leakage current of the core is detected to be kept within the specified range to determine whether the positive and negative poles of the core are short-circuited. If the core is tested to have a short circuit, the short-circuited core is directly scrapped; if the core is not tested to have a short circuit, the tab is flattened.

[0036] For details, see the attached Figure 3 As shown, the tab flattening process includes: within the critical stress value range that the positive composite current collector 1 and the negative composite current collector 4 can withstand, the positive tab and the negative tab are flattened to form a full tab structure with a gap that meets the welding requirements, wherein the flattening accuracy is controlled within ±0.05mm, and the flatness of the rear end surface after flattening is controlled within ±0.15mm.

[0037] Preferably, the tab 9 is cut before the tab flattening process is performed, so as to prevent the tab from bulging due to stress concentration after the tab is flattened.

[0038] The present invention also provides a method for preparing a battery using a composite current collector, comprising preparing the above-mentioned full-tab core into a battery. Specifically, the battery preparation method comprises the following steps: 1. Prepare a full-electrode lug core: including preparing the composite current collector into positive and negative electrode sheets respectively, stacking the positive electrode sheet, the separator 7, and the negative electrode sheet and winding them into a core 8, coating the two sides of the core 8 perpendicular to its winding direction with conductive glue, performing a short-circuit test on the core 8, and flattening the lugs of the core; it should be noted that the preparation of the full-electrode lug core can refer to the preparation method of the full-electrode lug core mentioned above, which will not be repeated here; 2. Rubber coating: Wrap the positive and negative pole ears at both ends of the flattened winding core with insulating tape to prevent the ears from contacting the metal shell and causing a short circuit; 3. Shelling: Push the coated core into the battery shell through the pushing device, and make the positive and negative pole ears flattened at both ends of the core face the openings at both ends of the battery shell respectively; stack the positive electrode sheet, diaphragm, and negative electrode sheet and wind them into a core; 4. Collector plate welding process: Weld the positive collector plate and the negative collector plate to the flattened end surfaces of the positive and negative pole ears respectively; 5. Covering treatment: Cover plates are respectively placed on the open ends of the battery shell, and the cover plates are connected to the corresponding positive electrode collector plate or negative electrode collector plate by bending, extrusion and riveting; then the cover plates are tightly combined with the battery shell and pre-spot welded to shape; 6. Peripheral welding: perform peripheral sealing welding on the battery after the cover is closed; 7. Helium inspection: Use helium inspection equipment to test the air tightness of the battery after peripheral welding. If the air tightness is qualified, it will enter the next process. If the air tightness is unqualified, it will be reworked or scrapped. 8. Divide the battery into capacities and test the OCV data; 9. Clean the assembled batteries, conduct a full appearance inspection on the batteries, and then pack them for shipment.

[0039] The full-tab winding core and battery prepared by the present invention have blank areas (positive electrode blank areas or negative electrode blank areas) separated on the composite current collector, and the blank areas are coated with conductive glue, so that the conductive layers on both sides of the composite current collector can be mutually conductive, thereby providing the possibility of directly using the composite current collector as the tabs; and the conductive glue can be completely solidified on the blank areas on both sides of the winding core through post-coating treatment, so that positive electrode tabs and negative electrode tabs can be formed on both sides of the winding core respectively, and there is no need to weld external aluminum foil as transfer tabs, which simplifies the tab preparation process and avoids the problem of reduced energy density of the battery cell due to external aluminum foil. The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a full-electrode tab core using a composite current collector, characterized in that: The steps include: S1. Prepare a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet comprises a positive electrode composite current collector and a positive electrode active material layer arranged on at least one side of the positive electrode composite current collector in the thickness direction, and at least one side of the positive electrode composite current collector in the width direction is provided with a positive electrode blank area not coated with a positive electrode active material; the negative electrode sheet comprises a negative electrode composite current collector and a negative electrode active material layer arranged on at least one side of the negative electrode composite current collector in the thickness direction, and at least one side of the negative electrode composite current collector in the width direction is provided with a negative electrode blank area not coated with a negative electrode active material; the positive electrode composite current collector and the negative electrode composite current collector both comprise a base film and a conductive layer arranged on both sides of the base film; S2, stacking the positive electrode sheet, the separator, and the negative electrode sheet and winding them into a winding core; along the central axis direction of the winding core, the positive electrode blank area and the negative electrode blank area are respectively located on both sides of the winding core; S3. Coating a conductive adhesive on at least one of the two sides of the winding core in the direction of the central axis to make the conductive layers on both sides of the positive electrode composite current collector conductive and / or the conductive layers on both sides of the negative electrode composite current collector conductive.

2. The preparation method according to claim 1, characterized in that: In step S3, after the conductive adhesive is applied, post-adhesion treatment is required, and the post-adhesion treatment includes preheating and drying, heating and drying, and cooling and drying the core after the conductive adhesive is applied in sequence, so that the conductive adhesive is solidified on the core; the preheating and drying temperature is 50~80℃, the heating and drying temperature is 70~90℃, and the cooling and drying temperature is 30~50℃.

3. The preparation method according to claim 1, characterized in that: In step S1, the widths of the positive electrode blank area and the negative electrode blank area are both 3-80 mm.

4. The preparation method according to claim 1, characterized in that: After step S3, a short circuit test is performed on the winding core to detect whether there is a short circuit between the positive electrode sheet and the negative electrode sheet of the winding core.

5. The preparation method according to claim 1, characterized in that: The conductive adhesive comprises a conductive metal and a binder, wherein the conductive metal comprises at least one of gold, silver, copper and aluminum, and the binder comprises at least one of polyvinyl alcohol, polytetrafluoroethylene, sodium carboxymethyl cellulose, polyvinylidene fluoride and styrene-butadiene rubber.

6. The preparation method according to claim 1, characterized in that: Step S1 includes slurry treatment, coating treatment, rolling treatment, and slitting treatment, wherein the slurry treatment includes preparing positive electrode active materials and negative electrode active materials respectively, the coating treatment includes coating the positive electrode active materials and negative electrode active materials on the positive electrode composite current collector and the negative electrode composite current collector respectively and drying them, the rolling treatment includes rolling the positive electrode composite current collector and the negative electrode composite current collector after the coating treatment to a set thickness; the slitting treatment includes slitting the positive electrode composite current collector and the negative electrode composite current collector after the rolling treatment to a set width to obtain positive electrode sheets and negative electrode sheets.

7. The preparation method according to claim 6, characterized in that: During the homogenization treatment, the active material in the positive electrode active material includes at least one of lithium cobalt oxide, lithium iron phosphate, lithium manganese oxide, and nickel cobalt lithium manganese oxide. The fineness of the positive electrode active material is 10-100 μm, the viscosity is 3000-15000 mPa·s, and the solid content is 40-75%.

8. The preparation method according to claim 6, characterized in that: During the homogenization treatment, the active material in the negative electrode active material includes at least one of silicon-based materials, carbon microspheres, hard carbon, soft carbon and lithium metal, and the negative electrode active material has a fineness of 10-100 μm, a viscosity of 2000-10000 mPa·s, and a solid content of 40-60%.

9. A full-electrode tab core using a composite current collector, characterized in that: The method is prepared by any one of claims 1 to 8.

10. A full-tab battery, characterized in that: It comprises the full-tab winding core as described in claim 9.

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