Battery output end structure and forming process thereof

Abstract

The invention discloses a battery output end structure and a forming process thereof, and relates to the technical field of batteries. The battery output end structure comprises a negative pole piece and a negative pole column, the negative pole column is an aluminum pole column, and the negative pole piece comprises a current collector and an active material layer; the current collector comprises a body part and a welding part, and the welding part is an aluminum foil; the welding part is electrically connected with the copper area in the body part through the transition area; and the transition area is formed by mixing metal copper and metal aluminum. According to the invention, a copper-aluminum compounding mode is converted from pure physical pressing to copper-aluminum hot rolling compounding, so that the risk caused by cracking of copper-aluminum compounding due to thermal expansion is reduced, the problem of high resistance of a contact interface of the copper-aluminum compounding and the copper-aluminum compounding is solved, and meanwhile, the problem that air, moisture and the like outside the battery possibly enter the contact interface of the copper-aluminum compounding and the copper-aluminum compounding is further solved; the reliability of the output end is improved and the service life of the battery is prolonged while the welding effect of the pole piece and the pole and the welding effect of the pole and the busbar are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and specifically to a battery output terminal structure and its forming process. Background Art

[0002] In a battery, after the positive and negative electrode plates are welded to the battery terminal posts, the current is output from the terminal posts; each battery realizes series or parallel connection between the batteries through a busbar welded to the battery terminal posts to increase the capacity and voltage of the battery pack; since aluminum metal has a lower weight and cost compared to copper metal, it is a commonly used material for the busbar in the battery pack; however, because the negative electrode of the battery is usually a copper terminal post, when the copper terminal post is welded to the aluminum busbar, aluminum explosion will occur due to different melting points, affecting the welding effect. Therefore, the commonly used method now is to design the negative terminal post as a copper-aluminum riveted terminal post, that is, one end of the negative terminal post welded to the negative electrode plate is a copper block, and the end welded to the aluminum busbar is an aluminum block. The copper block and the aluminum block are combined and conduct electricity through a riveting structure.

[0003] Although this kind of riveted terminal post can effectively solve the problem of explosion welding, during the long-term use of the battery, the following problems will occur: 1. The thermal expansion coefficients of copper and aluminum are different. Long-term use and temperature changes will cause inconsistent expansion of the two, and loosening or cracking is likely to occur; 2. The copper-aluminum combination is a purely physical pressing method, with a relatively high interface resistance, and air and moisture may enter the interface during long-term use, resulting in a further increase in the contact resistance. Summary of the Invention

[0004] The purpose of the present invention is to provide a battery output terminal structure and its forming process to solve the problems raised in the prior art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A battery output terminal structure includes a negative electrode plate and a negative terminal post. The negative terminal post is an aluminum terminal post. The negative electrode plate includes a current collector and an active material layer; the current collector includes a body part and a welding part, and the welding part is an aluminum foil; the welding part is electrically connected to the copper area in the body part through a transition area; the transition area is a mixture of metal copper and metal aluminum.

[0006] Further, the body part is a copper foil, a tab is provided on the body part, the welding part is arranged at one end of the tab away from the body part, and the transition area is arranged at the other end of the tab.

[0007] Further, the distance between the transition area and the body part is 1-5 mm.

[0008] Further, the current collector is multi-layered. The body part includes a polymer base film and a copper layer, and the tab is electrically connected to the surface of the copper layer by welding or conductive adhesive;

[0009] The tab is a split tab.

[0010] Further, the tab includes an overlapping portion and an extending portion. The overlapping portion is a copper foil that overlaps with the copper layer in the body portion. The welding portion is provided at one end of the extending portion away from the overlapping portion, and the transition region is provided at the other end of the extending portion.

[0011] Further, the copper layer is provided on the upper surface and / or the lower surface of the polymer base film. The tab is a metal foil.

[0012] The overlapping portion is electrically connected to the overlapping area of the body portion by welding to form a welding area.

[0013] The welding area does not overlap with the transition region.

[0014] Further, the active material layer is provided on the upper surface and / or the lower surface of the body portion.

[0015] A battery output terminal structure device includes an outer box body and a battery output terminal structure arranged in the box body. The placement direction of the battery is such that the direction in which the negative electrode post extends is opposite to the direction of the gravity.

[0016] A forming process for a battery output terminal structure includes the following steps:

[0017] S1: Take a copper plate, perform surface heat treatment, and then pour semi-solid aluminum that has undergone crystallization treatment. After solidification, an aluminum layer is formed. Roll in the thickness direction to form a composite copper-aluminum sheet.

[0018] Cut the composite copper-aluminum sheet into strips to form composite strips. Stand the composite strips upright and perform secondary rolling. Repeat the secondary rolling 3 - 5 times to form a copper region - a transition region - an aluminum region, and obtain a copper-aluminum spliced foil.

[0019] S2: Coat the copper region of the copper-aluminum spliced foil obtained in S1 with an active material and dry it to form an active material layer (7), and obtain a semi-finished negative electrode sheet.

[0020] Die-cut the obtained semi-finished negative electrode sheet to form tabs and obtain a negative electrode sheet.

[0021] S3: Stack or wind the negative electrode sheet obtained in S2 with a separator and a positive electrode sheet to obtain an electric core. Weld the aluminum region to the negative electrode post to form a battery output terminal structure.

[0022] Then install it in a housing, inject electrolyte, and seal it to obtain a battery.

[0023] Further, in step S1, the composite copper-aluminum sheet is formed by alternately laminating multiple layers of copper plates and multiple layers of aluminum layers.

[0024] The upper surface, lower surface, and both side surfaces in the length direction of the outermost layer of the composite copper-aluminum sheet are all aluminum.

[0025] Further, in step S2, before die-cutting, slitting is performed in the middle of the aluminum area to obtain a plurality of semi-finished negative electrode sheets with the width direction of the current collector being aluminum-copper-aluminum.

[0026] Further, the area coated with the active material in S2 does not exceed the copper area.

[0027] In the above technical implementation manners, the copper area formed in the process corresponds to the main body part of the current collector or the overlapping part of the split tab, and the aluminum area corresponds to the welding part of the current collector or the split tab.

[0028] When the main body part is a copper foil, the copper area formed in the aforementioned process corresponds to the main body part of the current collector, and the aluminum area corresponds to the welding part of the current collector.

[0029] When the current collector is multilayered, the copper area formed in the aforementioned process corresponds to the overlapping part of the split tab, and the aluminum area corresponds to the welding part of the split tab.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. The present invention transfers the copper-aluminum composite structure at the negative electrode output end of the battery from the outside of the battery to the inside of the battery, and converts the copper-aluminum composite method from pure physical pressing to copper-aluminum hot rolling composite, reducing the risk of cracking problems caused by thermal expansion in copper-aluminum composite, solving the problem of large contact interface resistance between the two, and further solving the problems that air, moisture, etc. in the outside of the battery may enter the contact interface between the two. While ensuring the welding effect between the electrode sheet and the pole column, and between the pole column and the bus bar, the reliability of the output end is improved, and the service life of the battery is extended.

[0032] In this solution, the rolling forming of the transition area of the current collector is carried out. In the thickness direction, the two are rolled into a composite copper-aluminum sheet by a rolling mill, then cut into strips, and then the strips are placed vertically and subjected to secondary hot rolling. The secondary rolling can be repeated for multiple hot rolling passes, and a copper-aluminum splicing foil with an aluminum-copper transition connection can be obtained. After multiple hot rolling passes at the connection between the two, the copper-aluminum metal lattice structures are interlaced with each other. The connection strength of the splicing foil obtained in this way is reliable, the fusion effect at the copper-aluminum splicing is good, and the interface resistance at the splicing is low, which can meet the over-current requirements in the battery.

[0033] 2. The tab of the current collector is obtained by die-cutting the foil. During die-cutting, the transition area and aluminum outside the tab area are all cut off, and the main body area is all copper. Only the negative electrode active material is coated on the main body area. Because aluminum will undergo an alloying reaction with lithium metal, if there is aluminum in the main body area, during the lithium insertion process at the negative electrode of the battery during charging, aluminum and lithium form an alloy, resulting in a significant volume expansion, which may damage the battery structure and seriously affect the performance and service life of the battery.

[0034] 3. In a battery, an insulating separator is also interposed between the battery electrode plates. The insulating separator has good electrolyte wettability. And to avoid short circuit at the edges of the positive and negative electrodes, usually the edge of the insulating separator protrudes beyond the edge of the electrode plate, i.e., overhang design. Therefore, there needs to be a certain distance between the copper-aluminum transition region and the body region to prevent the copper-aluminum transition region from contacting the insulating separator and causing the transition region to be contaminated with the electrolyte. Since copper and aluminum have different electrode potentials in the electrochemical series, when the two metals come into contact and are in an electrolyte environment, a micro galvanic cell will be formed. In this galvanic cell, the metal with a lower electrode potential (aluminum) will dissolve as the anode. Therefore, to ensure the effective life of the battery, it is necessary to avoid the transition region between the two metals being in the electrolyte environment.

[0035] 4. The current collector can also be a multi-layer current collector. The multi-layer current collector can improve the battery energy density and reduce the battery cost due to the introduction of the polymer.

[0036] 5. Since the multi-layer current collector is non-conductive in the thickness direction due to the introduction of the polymer, it is necessary to export the current through the split tab welded on the copper layer surface. The split tab is made of copper-aluminum transition foil. The copper region is welded to the copper layer, and the aluminum region is welded to the aluminum pole. The copper-aluminum transition region cannot be welded to the copper layer to avoid the explosion welding problem due to the different melting points of copper and aluminum.

[0037] 6. Ensure that the battery is in the upright state in the battery pack or battery module, rather than inverted or flat, which can prevent the electrolyte from infiltrating into the splicing part of the copper-aluminum spliced tab and avoid the formation of micro batteries.

[0038] 7. By preparing a copper-aluminum spliced foil with copper and aluminum alternating multiple times in the width direction, it is possible to simultaneously coat the negative electrode active material layer on multiple electrode plates and dry them, and then multiple negative electrode plates can be obtained after slitting, greatly improving the battery manufacturing efficiency and reducing the process cost. Description of the Drawings

[0039] Figure 1 It is a schematic structural diagram of a battery output terminal structure in Embodiment 4 of the present invention;

[0040] Figure 2 It is a schematic rolling process diagram in Embodiment 1 of the present invention;

[0041] Figure 3 It is a schematic slitting process diagram in Embodiment 1 of the present invention;

[0042] Figure 4 It is a schematic structural diagram of the copper-aluminum spliced foil in Embodiment 1 of the present invention;

[0043] Figure 5 It is a schematic structural diagram of the negative electrode plate semi-finished product in Embodiment 1 of the present invention;

[0044] Figure 6 It is a schematic structural diagram of the negative electrode sheet in Embodiment 1 of the present invention;

[0045] Figure 7 It is a schematic structural diagram of the battery output terminal in Embodiment 1 of the present invention;

[0046] Figure 8 It is a schematic rolling process diagram in Embodiment 5 of the present invention;

[0047] Figure 9 It is a schematic strip cutting process diagram in Embodiment 5 of the present invention;

[0048] Figure 10 It is a schematic structural diagram of multiple copper-aluminum spliced foils in Embodiment 5 of the present invention;

[0049] Figure 11 It is a schematic structural diagram of multiple copper-aluminum spliced foils after coating with the active material layer in Embodiment 5 of the present invention;

[0050] Figure 12 It is a schematic slitting process diagram in Embodiment 5 of the present invention;

[0051] Figure 13 It is a schematic structural diagram of the semi-finished negative electrode sheet in Embodiment 5 of the present invention;

[0052] Figure 14 It is a schematic structural diagram of the negative electrode sheet in Embodiment 5 of the present invention.

[0053] In the figure, 1. Extension part, 2. Negative electrode column, 3. Transition area, 4. Welding part, 5. Overlapping part, 6. Welding area, 7. Active material layer, 8. Copper layer, 9. Body part, 10. Polymer base film. Detailed implementation manners

[0054] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0055] In the following detailed implementation manners,

[0056] The separator is a polypropylene microporous membrane with a pore size range of 30 μm, sourced from Haining Delv New Materials Technology Co., Ltd.;

[0057] The copper-aluminum composite material, with a thickness of 20 μm, a width of 200 mm, and a length of 80 mm, is sourced from Tianjin Hongsheng Metal Materials Co., Ltd.;

[0058] The specifications of the copper plate are: thickness 50 mm, width 400 mm, length 120 mm, sourced from Shandong Wanjia Copper Industry Co., Ltd.;

[0059] The polymer base film is PET (polyethylene terephthalate), with a thickness of 6 μm, sourced from Toray Advanced Materials Korea Co., Ltd.;

[0060] Both the positive electrode post and the negative electrode post are aluminum electrode posts;

[0061] The positive electrode sheet has a positive electrode active material layer provided on both sides of the aluminum foil surface, and its components are: 92 parts of lithium iron phosphate, 3 parts of carbon nanotubes, 2 parts of Super P (conductive carbon black), and 3 parts of PVDF (polyvinylidene fluoride);

[0062] The electrolyte is a mixture of LiPF6 (lithium hexafluorophosphate) and an EC / DEC composite solution, the electrolyte concentration is 1 M, and the volume ratio of EC (ethylene carbonate) to DEC (diethyl carbonate) is 1:1;

[0063] When the body part is a copper foil, the copper area formed in the process corresponds to the body part of the current collector, and the aluminum area corresponds to the welding part where the current collector is welded to the aluminum electrode post;

[0064] When the current collector is a composite current collector, the copper area formed in the process corresponds to the overlapping part of the split tab and the composite current collector, and the aluminum area corresponds to the welding part where the split tab is welded to the aluminum electrode post.

[0065] Example 1: When the body part is a copper foil, a forming process for a battery output terminal structure includes the following steps:

[0066] (1) Preparation of semi-solid aluminum:

[0067] Under the protection of a nitrogen atmosphere, melt metallic aluminum, stir for 30 s to obtain liquid aluminum, let the liquid aluminum stand for 30 min, and then perform semi-solid isothermal heat treatment. After the treatment is completed, quench to obtain semi-solid aluminum; the process conditions for the semi-solid isothermal heat treatment are: temperature 555 °C, holding time 10 minutes;

[0068] (2) Preparation of the battery:

[0069] S1: Take a copper plate, perform surface heat treatment, and then pour semi-solid aluminum that has undergone crystallization treatment. After solidification, an aluminum layer is formed. Roll in the thickness direction to form a composite copper-aluminum sheet. Cut the composite copper-aluminum sheet into strips to form composite strips. Stand the composite strips upright and perform secondary rolling. Repeat the secondary rolling 3 times to form a copper zone - transition zone - aluminum zone, obtaining a copper-aluminum spliced foil. S2: Coat the copper zone of the copper-aluminum spliced foil obtained in S1 with an active material and dry it to form an active material layer 7, obtaining a semi-finished negative electrode sheet. Partially die-cut the area without the active material covering of the obtained semi-finished negative electrode sheet to form tabs, obtaining a negative electrode sheet. S3: Stack the negative electrode sheet obtained in S2 with a separator and a positive electrode sheet to obtain an electric core. Weld the aluminum zone to a negative electrode post (aluminum), and weld the tab of the positive electrode sheet to a positive electrode post (aluminum) to form a battery output terminal structure. Then, place it in a housing, inject electrolyte, and seal it to obtain a battery. In S1, the pouring thickness of the semi-solid aluminum is 4 mm. The process conditions for rolling in S1 are: temperature 250 °C, time 2.5 h. In S2, the thickness of the negative electrode active material layer is 0.5 mm. In S1, the composite copper-aluminum sheet is prepared from 1 layer of copper plate and 1 layer of aluminum layer. In S2, the area coated with the active material does not exceed the copper zone.

[0070] Example 2: When the body part is a copper foil, a forming process for a battery output terminal structure includes the following steps:

[0071] (1) Preparation of semi-solid aluminum:

[0072] Under the protection of a nitrogen atmosphere, melt metallic aluminum, stir for 40 s to obtain liquid aluminum. Let the liquid aluminum stand for 40 min, and then perform semi-solid isothermal heat treatment. After the treatment is completed, quench to obtain semi-solid aluminum. The process conditions for the semi-solid isothermal heat treatment are: temperature 570 °C, holding time 25 minutes.

[0073] (2) Preparation of the battery:

[0074] S1: Take a copper plate, conduct surface heat treatment, and then pour semi-solid aluminum that has undergone crystallization treatment. After solidification, an aluminum layer is formed. Roll in the thickness direction to form a composite copper-aluminum sheet. Cut the composite copper-aluminum sheet into strips to form composite long strips. Stand the composite long strips upright and conduct secondary rolling. Repeat the secondary rolling 4 times to form a copper zone - transition zone - aluminum zone, obtaining a copper-aluminum spliced foil. S2: Coat the copper zone of the copper-aluminum spliced foil obtained in S1 with an active material and dry it to form an active material layer 7, obtaining a semi-finished negative electrode sheet. Partially die-cut the area without the active material covering of the obtained semi-finished negative electrode sheet to form tabs, obtaining a negative electrode sheet. S3: Stack the negative electrode sheet obtained in S2 with a separator and a positive electrode sheet to obtain an electric core. Weld the aluminum zone to the negative electrode post (aluminum), and weld the tab of the positive electrode sheet to the positive electrode post (aluminum) to form a battery output terminal structure. Then, install it in a housing, inject electrolyte, and seal it to obtain a battery. In S1, the pouring thickness of the semi-solid aluminum is 6 mm. In S1, the process conditions for rolling are: temperature 350 °C, time 3.5 h. In S2, the thickness of the negative electrode active material layer is 1.0 mm. In S1, the composite copper-aluminum sheet is prepared from 1 layer of copper plate and 1 layer of aluminum layer. In S2, the area coated with the active material does not exceed the copper zone.

[0075] Example 3: When the main body part is a copper foil, a forming process for a battery output terminal structure includes the following steps:

[0076] (1) Preparation of semi-solid aluminum:

[0077] Under the protection of a nitrogen atmosphere, melt metallic aluminum, stir for 50 s to obtain liquid aluminum, let the liquid aluminum stand for 45 min, and then conduct semi-solid isothermal heat treatment. After the treatment is completed, quench to obtain semi-solid aluminum. The process conditions for the semi-solid isothermal heat treatment are: temperature 585 °C, holding time 40 minutes.

[0078] (2) Preparation of the battery:

[0079] S1: Take a copper plate, conduct surface heat treatment, and then pour semi-solid aluminum that has undergone crystallization treatment. After solidification, an aluminum layer is formed. Roll in the thickness direction to form a composite copper-aluminum sheet. Cut the composite copper-aluminum sheet into strips to form composite long strips. Stand the composite long strips upright and conduct secondary rolling. Repeat the secondary rolling 5 times to form a copper zone - transition zone - aluminum zone, obtaining a copper-aluminum spliced foil. S2: Coat the copper zone of the copper-aluminum spliced foil obtained in S1 with an active material and dry it to form an active material layer 7, obtaining a semi-finished negative electrode sheet. Partially die-cut the area without the active material covering of the obtained semi-finished negative electrode sheet to form tabs, obtaining a negative electrode sheet. S3: Stack the negative electrode sheet obtained in S2 with a separator and a positive electrode sheet to obtain an electrode core. Weld the aluminum zone to the negative electrode terminal (aluminum), and weld the tab of the positive electrode sheet to the positive electrode terminal (aluminum) to form a battery output terminal structure. Then place it in a housing, inject electrolyte, and seal it to obtain a battery. In S1, the pouring thickness of the semi-solid aluminum is 8 mm. In S1, the process conditions for rolling are: temperature 450 °C, time 4.5 h. In S2, the thickness of the negative electrode active material layer is 1.5 mm. In S1, the composite copper-aluminum sheet is prepared from 1 layer of copper plate and 1 layer of aluminum layer. In S2, the area coated with the active material does not exceed the copper zone.

[0080] Example 4: Taking Example 1 as a comparison, when the current collector is a composite current collector, a forming process for a battery output terminal structure includes the following steps:

[0081] (1) Preparation of semi-solid aluminum:

[0082] Under the protection of a nitrogen atmosphere, melt metallic aluminum, stir for 30 s to obtain liquid aluminum, let the liquid aluminum stand for 30 min, and then conduct semi-solid isothermal heat treatment. After the treatment is completed, quench to obtain semi-solid aluminum. The process conditions for the semi-solid isothermal heat treatment are: temperature 555 °C, holding time 10 minutes.

[0083] (2) Preparation of the battery:

[0084] S1: Take a copper plate, conduct surface heat treatment, and then pour semi-solid aluminum that has undergone crystallization treatment. After solidification, an aluminum layer is formed. Roll in the thickness direction to form a composite copper-aluminum sheet. Cut the composite copper-aluminum sheet into strips to form composite long strips. Stand the composite long strips vertically and conduct secondary rolling. Repeat the secondary rolling 3 times to form a copper zone - transition zone - aluminum zone, obtaining a copper-aluminum spliced foil. After cutting, obtain a copper-aluminum spliced tab; S2: Select a PET polymer base film, and deposit a copper seed layer with a thickness of 20 nm on each side surface through a magnetron sputtering process. Then, thicken it to a copper layer with a thickness of 1 μm on each side through electroplating to obtain a composite copper current collector; S3: Coat an active material on some areas of the surface of the composite copper current collector obtained in S2, and dry it to form an active material layer 7, obtaining a semi-finished negative electrode sheet. Weld the copper layer in the non-active material covered area of the obtained semi-finished negative electrode sheet to the copper zone of the copper-aluminum spliced foil in S1 through an ultrasonic welding process. Then, die-cut the non-active material covered area and the copper zone to form tabs, obtaining a negative electrode sheet; S4: Stack the negative electrode sheet obtained in S3 with a separator and a positive electrode sheet to obtain an electric core. Weld the aluminum zone to a negative electrode post (aluminum), and weld the tab of the positive electrode sheet to a positive electrode post (aluminum) to form a battery output terminal structure. Then, install it in a housing, inject electrolyte, and seal it to obtain a battery; In S1, the pouring thickness of the semi-solid aluminum is 4 mm; In S1, the process conditions for rolling are: temperature 250 °C, time 2.5 h; In S2, the thickness of the negative electrode active material layer is 0.5 mm; In S1, the composite copper-aluminum sheet is prepared from 1 layer of copper plate and 1 layer of aluminum layer; In S2, the process conditions for magnetron sputtering are: deposition rate 500 nm / min; In S3, the process conditions for ultrasonic welding are: time 1.2 s, pressure 0.5 MPa, amplitude 40 μm.

[0085] Example 5: Taking Example 1 as a comparison, when the current collector is obtained by multiple cuts, a forming process for a battery output terminal structure includes the following steps:

[0086] (1) Preparation of semi-solid aluminum:

[0087] Under the protection of a nitrogen atmosphere, melt metallic aluminum, stir for 30 s to obtain liquid aluminum. Let the liquid aluminum stand for 30 min, and then conduct semi-solid isothermal heat treatment. After the treatment is completed, quench to obtain semi-solid aluminum. The process conditions for the semi-solid isothermal heat treatment are: temperature 555 °C, holding time 10 minutes;

[0088] (2) Preparation of the battery:

[0089] S1: Take a copper plate, conduct surface heat treatment, and then pour semi-solid aluminum that has undergone crystallization treatment on one side of the copper plate. After solidification, an aluminum layer is formed. Roll in the thickness direction to form a first composite copper-aluminum sheet;

[0090] S2: Cast semi-solid aluminum that has undergone crystallization treatment on the other side of the copper plate, cover the surface of the semi-solid aluminum with another copper plate, and roll it in the thickness direction after the semi-solid aluminum solidifies to form a second copper-aluminum composite plate;

[0091] S3: Repeat step S2 once. On the outer side of the top copper plate, then pour semi-solid aluminum that has undergone crystallization treatment, and form an aluminum layer after solidification; roll it in the thickness direction to form a third copper-aluminum composite plate;

[0092] S4: Cut the third copper-aluminum composite plate into strips to form composite strips; place the composite strips vertically and perform secondary rolling, repeat the secondary rolling 3 times to form an aluminum zone - transition zone - copper zone - transition zone - aluminum zone - transition zone - copper zone - transition zone - aluminum zone - transition zone - copper zone - transition zone - aluminum zone, and obtain multiple copper-aluminum spliced foils; S5: Coat active material in the copper zones of the multiple copper-aluminum spliced foils obtained in S4, dry it to form an active material layer 7; perform slitting in the middle of the aluminum zones of the multiple copper-aluminum spliced foils to obtain multiple semi-finished negative electrode sheets with the width direction of the current collector being aluminum - copper - aluminum; perform partial die-cutting on the non-active material covered area of the obtained semi-finished negative electrode sheets to form tabs and obtain negative electrode sheets; S6: Stack the negative electrode sheets obtained in S5 with the separator and the positive electrode sheet to obtain an electric core; weld the aluminum zone to the negative electrode post (aluminum), and weld the tab of the positive electrode sheet to the positive electrode post (aluminum) to form a battery output terminal structure; then install it in a housing, inject electrolyte, and seal it to obtain a battery; in S1, the casting thickness of the semi-solid aluminum is 4 mm; in S2, the thickness of the negative electrode active material layer is 0.5 mm; in S4, the third copper-aluminum composite plate is prepared from 3 layers of copper plates and 4 layers of aluminum layers; in S2, the area coated with the active material does not exceed the copper zone; the process conditions for rolling are: temperature 250 °C, time 2.5 h.

[0093] Comparative Example 1: Taking Example 1 as a comparison, replace the copper-aluminum spliced foil prepared in S1 with a commercially available copper-aluminum composite material, and keep the other conditions unchanged.

[0094] Comparative Example 2: Taking Example 5 as a comparison, replace the copper-aluminum spliced foil prepared in S1 with a commercially available copper-aluminum composite material, and keep the other conditions unchanged.

[0095] Comparative Example 3: Taking Example 1 as a comparison, replace the copper-aluminum spliced foil prepared in S1 with a commercially available copper foil, and replace the battery negative electrode post with a copper-aluminum riveted electrode post, and keep the other conditions unchanged.

[0096] Experiment: Take the copper-aluminum composite plates obtained in Examples 1 - 5 and Comparative Examples 1 - 3, make specimens with a length of 50 mm and a width of 15 mm, place them on an electronic universal testing machine for a tensile test with a tensile rate of 50 mm / min, and the test results are as follows in the table;

[0097] Table 1 Mechanical property test results of copper-aluminum composite plates

[0098] Tensile strength of composite copper-aluminum sheet / MPa Example 1 50 Example 2 53 Example 3 56 Example 4 59 Example 5 55 Comparative Example 1 48 Comparative Example 2 49 Comparative Example 3 62

[0099] Take the batteries obtained in Examples 1 - 5 and Comparative Examples 1 - 3, and refer to the national standard GB18287 - 2000 to conduct charge - discharge cycle performance tests on them; the results are as follows in the table;

[0100] Table 2 Test Results of Battery Performance

[0101]

[0102] From the test results of the mechanical properties of the composite copper - aluminum sheet, it can be seen that the copper - aluminum splicing foil prepared by the present invention has better mechanical strength compared with the commercially available copper - aluminum composite material, and the method of copper - aluminum compounding is changed from pure physical pressing to copper - aluminum hot - rolling compounding, reducing the risk of cracking caused by thermal expansion during copper - aluminum compounding;

[0103] From the test results of battery performance, it can be seen that compared with Example 1 and Example 5, the interfacial resistance of Comparative Example 1, Comparative Example 2, and Comparative Example 3 is larger. This is because after changing the copper - aluminum compounding method from pure physical pressing to copper - aluminum hot - rolling compounding, the mechanical strength of the copper - aluminum splicing foil is improved, the cracking caused by thermal expansion is reduced, and the problem of large interfacial resistance at the contact interface between the two is solved. Moreover, the copper - aluminum riveted pole in Comparative Example 3 has a relatively large resistance and a poor cycle life, so the battery performance drops significantly; compared with Example 1 and Example 5, the difference between the first - cycle discharge specific capacity and the capacity after 500 cycles of Comparative Example 1, Comparative Example 2, and Comparative Example 3 is large, indicating that the introduction of the polymer base film in the multi - layer current collector can improve the battery energy density; in summary, the battery prepared by the present invention has better chemical properties and cycle stability, has high application prospects, can reduce the process cost, and has good economic benefits.

[0104] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above - mentioned exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non - restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

Claims

1. A battery output terminal structure, characterized in that: The invention comprises a negative electrode sheet and a negative electrode column (2), wherein the negative electrode column (2) is an aluminum electrode column, and the negative electrode sheet comprises a current collector and an active material layer (7); the current collector comprises a main body (9) and a welding part (4), and the welding part (4) is an aluminum foil; the welding part (4) is electrically connected to the copper in the main body (9) through a transition zone (3); and the transition zone (3) is a mixture of metal copper and metal aluminum.

2. A battery output terminal structure according to claim 1, characterized in that: The main body (9) is copper foil, a pole ear is arranged on the main body (9), the welding portion (4) is arranged at one end of the pole ear away from the main body (9), and the transition zone (3) is arranged at the other end of the pole ear.

3. A battery output terminal structure according to claim 2, characterized in that: The distance between the transition zone (3) and the main body (9) is 1-5 mm.

4. A battery output terminal structure according to claim 1, characterized in that: The current collector is multi-layered, the main body comprises a polymer base film (10) and a copper layer (8), and the surface of the copper layer (8) is electrically connected to a pole lug by welding or conductive adhesive.

5. A battery output terminal structure according to claim 4, characterized in that: The electrode tab comprises an overlapping portion (5) and an extension portion (1); the overlapping portion (5) is a copper foil and overlaps with a copper layer (8) in a main body portion (9); the welding portion (4) is arranged at one end of the extension portion (1) away from the overlapping portion (5); and the transition zone (3) is arranged at the other end of the extension portion (1).

6. A battery output terminal structure according to claim 5, characterized in that: The copper layer (8) is arranged on the upper surface and / or the lower surface of the polymer base film (10); The overlapping portion (5) is electrically connected to the overlapping area of ​​the main body portion (9) by welding.

7. A battery output terminal structure according to claim 1, characterized in that: The active material layer (7) is arranged on the upper surface and / or the lower surface of the main body (9).

8. A forming process for a battery output terminal structure, characterized in that: The following steps are involved: S1: Take a copper plate, perform surface heat treatment, then pour semi-solid aluminum that has undergone crystallization treatment, and form an aluminum layer after solidification; roll it in the thickness direction to form a composite copper-aluminum plate; The composite copper-aluminum sheet is cut into strips to form composite long strips; the composite long strips are placed upright and subjected to secondary rolling, and the secondary rolling is repeated 3-5 times to form a copper area-transition area-aluminum area to obtain a copper-aluminum spliced ​​foil; S2: coating the copper area of ​​the copper-aluminum spliced ​​foil obtained in S1 with an active material, drying the copper area to form an active material layer (7), and obtaining a negative electrode semi-finished product; Die-cutting the obtained negative electrode sheet semi-finished product to form a tab to obtain a negative electrode sheet; S3: stacking or winding the negative electrode sheet obtained in S2 with the separator and the positive electrode sheet to obtain a battery cell; welding the aluminum area and the negative electrode column to form a battery output terminal structure; Then put it into the shell, inject electrolyte, seal it, and get the battery.

9. The forming process of a battery output terminal structure according to claim 8, characterized in that: In step S1, the composite copper-aluminum plate is formed by alternately stacking multiple layers of copper plates and multiple layers of aluminum; The outermost upper surface, lower surface and both side surfaces in the length direction of the composite copper-aluminum plate are all aluminum; In step S2, before die-cutting, cutting is performed in the middle of the aluminum area to obtain a plurality of negative electrode sheet semi-finished products with the width direction of the current collector being aluminum-copper-aluminum.

10. The forming process of a battery output terminal structure according to claim 8, characterized in that: In step S1, the casting thickness of the semi-solid aluminum is 4-8 mm, and the width of the aluminum layer is smaller than the width of the copper plate; The rolling process conditions are: temperature 250-450° C., time 2.5-4.5 h.

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