WO2021022997A1

WO2021022997A1 - Lithium strip and lithium strip coil having same

Info

Publication number: WO2021022997A1
Application number: PCT/CN2020/102999
Authority: WO
Inventors: 谢斌; 龚志杰; 陈仕通
Original assignee: 宁德时代新能源科技股份有限公司
Priority date: 2019-08-02
Filing date: 2020-07-20
Publication date: 2021-02-11
Also published as: CN112310342B; CN112310342A

Abstract

The present application provides a lithium strip and a lithium strip coil having same, and relates to the field of lithium strips for batteries. The lithium strip comprises a calendering start section, and a main section integrally connected to the calendering start section. The width of the calendering start section is smaller than that of the main section. The ratio of the width H of any part of the calendering start section to the width L of the main section is greater than or equal to 90% and less than 100%. The width of the calendering start section of the lithium strip is smaller than that of the main section of the lithium strip, so that the width of the start section of the obtained calendered lithium foil is more consistent with the width of the main section, avoiding the phenomenon that the calendered lithium foil is stick to the roll; the utilization rate of the lithium strip is higher, avoiding waste; and it facilitates reducing the production cost.

Description

Lithium belt and lithium belt coil material containing the lithium belt

Cross references to related applications

This application claims the priority of the Chinese patent application 201910712661.X filed on August 02, 2019, entitled "A lithium belt and a lithium belt coil containing the lithium belt". The entire content of this application is incorporated by reference. Into this article.

Technical field

This application relates to the field of lithium belts for batteries, in particular to a lithium belt and a lithium belt coil containing the lithium belt.

Background technique

With the popularization of new energy vehicles, everyone's requirements for new energy vehicle batteries are becoming more and more stringent. For example, batteries must have high energy density, long cycle and stable performance, as well as fast charging capabilities.

At present, technologies such as pre-lithiation can be used to improve the cycle performance of the battery and increase its energy density. One of the pre-lithiation methods is to use the lithium foil formed by rolling the lithium belt and the negative electrode. During the calendering process of the lithium ribbon, due to the softness of the lithium ribbon, the initial rolling position of the lithium ribbon is not balanced under the action of tension and pressure. At this time, due to the imbalance of tension and pressure, the result will be obtained from the calendering of the lithium ribbon. The width consistency of lithium foil is poor, causing sticking roller problems. At the same time, due to the inconsistency of the width of the lithium foil obtained after calendering the lithium tape, it needs to be further trimmed before it can be used after calendering, thereby causing waste of raw materials and increasing process steps.

Summary of the invention

The first aspect of the present application provides a lithium belt, comprising: a calendering start section, and a main body section integrally connected with the calendering start section, the width of the calendering start section is smaller than the width of the main body section; The ratio of the width H at any place of the calendering starting section to the width L of the main body section is greater than or equal to 90% and less than 100%.

The inventor of the present application found that due to the softness of the lithium belt, the middle part of the lithium belt will become narrower under the action of tension during the calendering time, while the initial section of the calendering does not reach a force balance due to its own tension and calendering pressure. , Its width is wider than that of the lithium belt under balanced force. In the lithium belt provided by the present application, the width of the starting section of the calendering section is smaller than the width of the main section, and the ratio of the width H at any place of the starting section of the rolling to the width L of the main section is set to be greater than or equal to 90% and less than 100 %, can effectively balance the width difference between the initial section and the middle section of the rolling, so that the width of the lithium foil after the rolling of the lithium belt maintains a higher consistency. Compared with the existing lithium belt with the same size, the lithium belt of the present application has a high consistency in the width after calendering, and the tape length when the width of the lithium foil reaches a stable after calendering is shorter, which avoids calendering during the calendering process. The phenomenon of lithium foil sticking to the roller, the utilization rate of the lithium belt is higher, the phenomenon of waste is avoided, and the production cost is reduced.

In any of the foregoing embodiments, the ratio of the width H at any position of the calendering start section to the width L of the main section is 94% to 98%.

In any of the foregoing embodiments, the length of the calendering start section is 50 mm to 400 mm.

In any of the foregoing embodiments, the length of the initial section of calendering is 150 mm to 200 mm.

In any of the foregoing embodiments, the width of the calendering start section gradually decreases from the main body section to the calendering start section.

In any of the foregoing embodiments, there is at least one obtuse angle at the start angle α of the rolling start section;

Optionally, the shape of the initial section of the calendering is a trapezoid; optionally, the trapezoid is an isosceles trapezoid, and the lower base of the trapezoid is integrally connected with the main body section.

In any of the foregoing embodiments, the cross-sectional shape of the rolling start section is selected from rectangular, trapezoidal, and wedge-shaped hexagons.

In any of the above embodiments, the cross-sectional shape is rectangular.

In any of the foregoing embodiments, the cross-sectional shape is a trapezoid, and the minimum angle θ _{1 of} the trapezoid is greater than or equal to 80° and less than 90°.

In any of the foregoing embodiments, the cross-sectional shape is a wedge-shaped hexagon, and the angle θ ₂ formed by the wedge-shaped hexagon along the thickness direction of the lithium belt is greater than or equal to 80° and less than 180°.

In any of the foregoing embodiments, the width of the main body section is 60 mm to 350 mm.

In any of the foregoing embodiments, the thickness of the main body section is 100 mm to 4000 mm.

In any of the foregoing embodiments, the tensile strength of the lithium belt is 0.9 MPa to 3.0 MPa.

In any of the foregoing embodiments, the tensile strength of the lithium belt is 0.9 MPa to 1.5 MPa.

In any of the foregoing embodiments, the elongation at break of the lithium belt is ≥10%.

In any of the foregoing embodiments, the elongation at break of the lithium belt is ≥25%.

A second aspect of the present application provides a lithium belt coil, which includes a reel and the lithium belt according to the first aspect of the present application wound on the reel.

In any of the foregoing embodiments, the reel and the lithium belt are connected by a base material section, one end of the base material section is connected to the reel, and the other end of the base material section is connected to the main body section;

Optionally, the material of the base material segment includes one of a metal strip, a polymer material strip, or a composite material film.

In any of the foregoing embodiments, the width of the substrate segment is less than or equal to the width of the roll.

In any of the above embodiments, the width of the reel is 40 mm wider than the width of the lithium belt.

In any of the foregoing embodiments, the difference between the width of the base material section and the width of the main body section is M, and the ratio of M to the width of the main body section ranges from -5% to +5%.

In any of the foregoing embodiments, the length of the base material section is 0.4 m to 1.2 m; optionally, the length of the base material section is 1 m to 1.2 m.

Description of the drawings

In order to more clearly illustrate the specific embodiments of this application or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the specific embodiments or the description of the prior art. Obviously, the appendix in the following description The drawings are some embodiments of the application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

FIG. 1 is a schematic diagram of the structure of a lithium belt in an embodiment of the application;

FIG. 2 shows that the width of the rolled lithium foil formed by calendering a lithium belt in an embodiment of the application reaches a stable tape length, and the width of the rolled lithium foil formed by a lithium tape with a uniform width in the prior art reaches a stable tape length length;

3 is a schematic diagram of a trapezoidal cross-sectional shape in an embodiment of the application;

4 is a schematic diagram of a wedge-shaped hexagon in the cross-sectional shape in an embodiment of the application;

FIG. 5 is a schematic diagram of the structure of the coil in an embodiment of the application.

Among them, 100-lithium belt; 110-starting section of calendering; 120-main section; 200-reel; 300-base material section; 400-bonding part.

detailed description

The implementation of the present application will be described in further detail below in conjunction with the drawings and embodiments. The detailed description and drawings of the following embodiments are used to exemplarily illustrate the principles of the application, but cannot be used to limit the scope of the application, that is, the application is not limited to the described embodiments.

In the description of this application, it should be noted that, unless otherwise specified, "plurality" means two or more; the terms "upper", "lower", "left", "right", "inner", and " The orientation or positional relationship indicated by “outside” is only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a reference to the present application. Application restrictions. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable range of error. "Parallel" is not strictly parallel, but within the allowable range of error.

The orientation words appearing in the following description are all directions shown in the figure, and do not limit the specific structure of the application. In the description of this application, it should be noted that the terms "installation", "connection", and "connection" should be understood in a broad sense unless otherwise clearly specified and limited. For example, they may be fixed connections or alternatively. Disassembly connection, or integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above-mentioned terms in this application can be understood according to the specific circumstances.

For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and any upper limit may be combined with any other upper limit to form an unspecified range. In addition, although not explicitly stated, every point or single value between the end points of the range is included in the range. Therefore, each point or single numerical value can be used as its own lower limit or upper limit in combination with any other point or single numerical value or in combination with other lower or upper limits to form an unspecified range.

In the description herein, it should be noted that, unless otherwise specified, "above" and "below" include the number, and "several" in "one or more" means two or more.

The foregoing summary of the invention is not intended to describe each disclosed embodiment or every implementation in this application. The following description more specifically exemplifies exemplary embodiments. In many places throughout the application, guidance is provided through a series of examples, which can be used in various combinations. In each instance, the enumeration serves only as a representative group and should not be interpreted as an exhaustive list.

In the first aspect of the present application, the present application provides a lithium belt. Referring to FIG. 1, the lithium belt 100 includes a calendering start section 110 and a main body section 120 integrally connected with the calendering start section 110. The main body section 120 faces the calendering starting section 110, the width of the calendering starting section 110 is smaller than the width of the main body section 120, the width H of any place of the calendering starting section 110 is equal to the width of the main body section 120 The ratio of L is greater than or equal to 90% and less than 100%, for example, it can be 90%, 92%, 94%, 96%, 98%, 99%, etc., preferably 94% to 98%.

Because the lithium belt is relatively soft, the middle part of the lithium belt will be narrowed under the action of tension during the calendering time, and the initial section of the calendering does not reach the force balance under its own tension and pressure, the width of the initial section of the calendering It is wider than the lithium belt under force balance. In the lithium belt provided by the present application, the width of the starting section of the calendering section is smaller than the width of the main section, and the ratio of the width H at any place of the starting section of the rolling to the width L of the main section is set to be greater than or equal to 90% and less than 100 %, can effectively balance the width difference between the initial section and the middle section of the rolling, so that the width of the lithium foil after the rolling of the lithium belt maintains a higher consistency. Compared with the existing lithium belts of the same size, the lithium belt of the present application, after a lot of experimental research by the inventor, found that the lithium belt is set as a lithium belt with a special starting end and the calendering start section and main section of the lithium belt The width ratio is set within a certain range, and the width consistency after calendering is high, and the length of the tape when the width of the lithium foil becomes stable after calendering is shorter. For the above content, please refer to Figure 2 for details; the lithium tape of this application To avoid the phenomenon that the rolled lithium foil sticks to the roller during the rolling process, the utilization rate of the lithium belt is higher, and the phenomenon of waste is avoided, which is beneficial to reduce the production cost.

It is understandable that the structure of the specific rolling start section is not limited in this application, as long as it can meet the requirements of this application. For example, a lithium belt that meets the above conditions can be obtained by shearing the starting section of the rolling with uniform width.

Optionally, the length of the initial section of calendering is 50 mm to 400 mm, preferably 150 mm to 200 mm. For example, the length of the starting section of the calendering can be 50mm, 80mm, 100mm, 150mm, 200mm, 250mm, 300mm, 350mm or 400mm. The length of the starting section of the calendering will affect the consistency of the calendering tape. When the length of the starting section of the calendering is set within the above range, the width of the starting section of the lithium belt after calendering is more uniform, and the width of the starting section of the calendering The consistency with the width of the main section is better. Compared with the above-mentioned length range, when the length of the initial section of calendering is too short, although the consistency of the lithium foil after calendering is improved, the width of the initial section will be wider after calendering. The width consistency is relatively poor, but the width consistency of the obtained calendered lithium foil is better than the effect of calendering the lithium belt with the same width in the prior art; when the length of the initiation section of calendering is too long, partial initiation will occur after calendering The width of the section is smaller than the width of the main section, and the width consistency of the obtained rolled lithium foil is relatively poor, but the obtained rolled lithium foil has a better width consistency than the effect of calendering the lithium belt with the same width in the prior art, and the lithium belt Too long the starting section of the calendering will increase the difficulty of the process. Therefore, controlling the length of the starting section of the lithium ribbon calendering within a reasonable range helps to better improve the final calendering effect of the lithium ribbon.

Optionally, from the main body section to the calendering start section, the width of the calendering start section gradually decreases.

Although this application does not specify the shape of the starting section of the lithium belt, considering the difficulty of the process and the final effect, the structure is designed to be gradually reduced, which can prevent the width of the starting section of the rolling during the rolling process. There was a jump change. Although it is possible to improve the consistency of the lithium foil after the rolling of the lithium belt as long as the width of the starting section of the rolling is smaller than the width of the main section, if the starting section of the rolling is not designed to have a gradually reduced structure, the process of rolling the lithium tape into a lithium foil In this case, the width of the lithium foil changes leaps and bounds with the width of the lithium belt, and the effect is not ideal. However, the structure is designed to be gradually reduced, which is easier to achieve from the perspective of the production process.

Optionally, there is at least one obtuse angle at the start angle α of the rolling start section.

It should be noted that the starting angle α refers to the angle between the edge and the edge at the free end of the calendering starting section. For details, refer to FIG. 1. There is at least one obtuse angle at the starting end angle α of the rolling starting section, which is to ensure that the width of the starting end of the rolling starting section is minimized, so as to ensure that the lithium ribbon can better improve the width uniformity of the lithium foil during the rolling process.

Optionally, the shape of the calendering initial section is, for example, a trapezoid, preferably an isosceles trapezoid, and the lower base of the trapezoid is integrally connected with the main body section.

By setting it into a trapezoid, especially an isosceles trapezoid, the structure is simple, easy to realize, and easy to process and manufacture, and because of its symmetry, the isosceles trapezoid makes the lithium belt more uniform during the calendering process, which can improve the calendering The smoothness of the calendering width dimension of the initial section in the calendering process, considering the difficulty of processing and the final effect, when the calendering initial section of the lithium belt is set as an isosceles trapezoid, the consistency of the lithium foil after the lithium belt is better . It is worth noting that the lower bottom side of the trapezoid is integrally connected with the main body section, and the lower bottom side of the trapezoid is the width of the side of the calendering starting section close to the main body section that first reaches the width of the main body section. As a limit, the integral connection of the rolling start section and the main section can better ensure the consistency of the lithium foil after the lithium belt is rolled.

Optionally, the cross-sectional shape of the calendering initial section may be, for example, a rectangle, a trapezoid, or a wedge-shaped hexagon.

The shape of the section affects the consistency of the lithium belt during the rolling process, and the cross-sectional shape of the initial section of the rolling can characterize the flatness of the initial section of the rolling in the thickness direction of the lithium belt to a certain extent. In the ideal state, the cross-section is rectangular, which is convenient for the operator to more accurately control the ratio of the width of the starting section to the width of the main section. However, in the actual production process, due to the limitation of equipment technology, the rolling is usually It is difficult for the section of the initial section to be rectangular, so the section of the initial section of rolling will also appear trapezoidal or wedge-shaped hexagon.

In some embodiments of the application, the cross-sectional shape is rectangular. When the section is rectangular, it indicates that the cross-section of the starting section of the lithium belt with a special starting end in the thickness direction of the lithium belt is relatively flat. The operator does not need to consider the thickness direction when designing the width of the starting section of the lithium belt. For the impact of the unevenness, it is only necessary to design such that the ratio of the width of the starting section of the lithium belt to the width of the main section of the lithium belt is greater than or equal to 90% and less than 100%.

In other embodiments of the present application, the cross-sectional shape is trapezoidal, the trapezoid is equal to the minimum angle θ ₁ greater than 80 ° less than 90 °, θ ₁ as shown in FIG. The angle of θ ₁ will affect the consistency of the lithium ribbon rolling. If the angle of θ ₁ is controlled within an appropriate range, the flatness of the section can be limited to a certain range, which can effectively ensure the consistency of the lithium ribbon rolling. The limitation of the specific value of the angle is based on the conclusion drawn by the inventor through a large number of experimental studies.

In still other embodiments of the present application, the cross-sectional shape is a wedge-shaped hexagon, and the angle θ ₂ formed along the thickness direction of the lithium ribbon formed by the six-shaped wedge is greater than or equal to 80° and less than 180°, as shown in FIG. 4, θ ₂ is the angle between two adjacent sides of the wedge-shaped hexagon in the thickness direction. Wherein, the reason for the angle limitation of the wedge-shaped hexagon is the same as the above, and will not be repeated here.

In this application, the width and thickness of the main section of the lithium belt are not specifically limited, and the width of the starting section of the calendering can be limited according to the width of the main section.

Optionally, the width of the main body section is 60 mm to 350 mm, for example, the width of the main body section may be 60 mm, 100 mm, 150 mm, 200 mm, 250 mm, 300 mm, 350 mm, or the like. The choice of the width of the main section has a certain impact on the final running consistency. When the ratio of the width H at any place of the calendering start section 110 to the width L of the main section 120 is determined as the preferred range, when the width of the main section is larger, the rolling Later, there will be a phenomenon that the width of the initial section is narrow, and the width consistency of the obtained calendered lithium foil is relatively poor, but the obtained calendered lithium foil has a better width consistency than the effect of calendering the lithium belt with the same width in the prior art ; When the main section is narrow, the width of the initial section will be wider after calendering, and the width consistency of the obtained calendered lithium foil is relatively poor, but the obtained calendered lithium foil has better width consistency than the prior art of calendering The effect of a lithium belt with uniform width.

Optionally, the thickness of the main body section may be, for example, 100 mm to 4000 mm. For example, the thickness of the main body section may be 100 mm, 500 mm, 1000 mm, 1500 mm, 2000 mm, 2500 mm, 3000 mm, 3500 mm, or 4000 mm.

Optionally, the tensile strength of the lithium belt is 0.9MPa to 3.0MPa, for example, it may be 0.9MPa, 1MPa, 1.2MPa, 1.4MPa, 1.6MPa, 1.8MPa, 2MPa, 2.2MPa, 2.4MPa, 2.6MPa, 2.8MPa or 3MPa etc. Therefore, it can not only ensure that the lithium belt will not be broken during the rolling process, but also can effectively prevent the excessive tensile strength from hindering the rolling of the lithium belt. After many experiments, the inventor found that selecting lithium belts with different tensile strengths is very important for the setting of the width H of the starting section of the rolling. The inventors of the present application use lithium belts with different tensile strengths to finally The ratio of H to L that needs to be set is obtained. In some optional embodiments of the present application, the tensile strength of the lithium belt is 0.9 MPa to 1.5 MPa.

Optionally, the elongation at break of the lithium belt is ≥10%, for example, the elongation at break of the lithium belt may be 10%, 20%, 30%, or 40%. Therefore, during the calendering process, there will be no fracture of the lithium ribbon. In the process of calendering the lithium ribbon, not only the consistency of the calendered lithium foil and the lithium foil need to be considered, but also the fracture derivation rate of the lithium ribbon needs to be controlled, otherwise the lithium ribbon Fracture occurs during the calendering process. If the lithium ribbon is fractured, the tension and force will be unbalanced again in the next part of the lithium ribbon where the lithium ribbon is broken during the calendering process, which will cause the lithium foil to fail after the lithium ribbon is calendered. Even problem. Therefore, it should be noted that in order to ensure better consistency of the lithium foil after the lithium belt is rolled, it is necessary to appropriately control the elongation at break of the lithium belt. Optionally, the elongation at break of the lithium belt is ≥25%.

In the second aspect of the present application, the present application provides a lithium tape coil. With reference to FIG. 5, the lithium tape coil includes: a reel 200 and the coil of the first aspect of the application wound on the reel 200 Lithium belt 100.

Since the lithium belt coil of the present application includes the lithium belt of the present application, the lithium belt coil of the present application has all the advantages of the lithium belt of the present application, and will not be repeated here.

Optionally, referring to FIG. 5, the reel 200 and the lithium belt 100 are connected through a substrate section 300, wherein one end of the substrate section 300 is connected to the reel 200, and the substrate section 300 The other end is connected to the main body section 110.

Generally, during the unwinding process of the lithium strip coil, the end of the lithium strip connected to the reel and the calender need to maintain a certain tension, so the end section of the lithium strip cannot be fully utilized, and the length of the coil The total length of the material is relatively large, so it will cause serious waste and increase production and processing costs. In this application, by providing the base material section, the function of the end section of the lithium belt can be effectively replaced, so that the entire lithium belt can be fully utilized.

Optionally, the material of the substrate section includes one of a metal strip, a polymer material strip or a composite material film, wherein the metal strip includes but is not limited to copper foil, aluminum foil, steel strip or One of the titanium belts; the polymer material belts include but are not limited to polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyimide (PI) One of; the composite film material includes but is not limited to one of glass fiber polymer, release film, release paper or release paper. As a result, the substrate section has a wide range of materials, lower prices, and better strength; and the above-mentioned materials are not easy to absorb water, do not contain strong polar groups (carboxyl, hydroxyl, amine, cyano, carbonyl, etc.), and have good performance.

Optionally, the width of the substrate section is less than or equal to the width of the reel. The width of the reel is generally 40mm wider than the width of the lithium belt. When the difference between the width of the reel and the width of the lithium belt exceeds 40mm, the length of the reel will increase and the equipment will be overrun. The width of the roller causes unnecessary waste, and the wider the width, the higher the requirement for tension consistency; the difference between the width of the base material section and the width of the main section of the lithium belt is M, the ratio of M to the width of the main section of the lithium belt The preferred range is -5% to +5%.

Optionally, the length of the substrate section is greater than 0.4m, for example, the length of the substrate section may be 0.4m, 0.6m, 0.8m, 1m, 1.2m, 1.4m, 1.6m, 1.8m, 2m or 2.2m Wait. Therefore, it is beneficial to make full use of the lithium belt. Compared with the above-mentioned length range, when the width of the base material section is too short, a part of the lithium belt near the reel of the main body section cannot be fully utilized, resulting in waste of the lithium belt. In some preferred embodiments of the present application, the length of the substrate section is 1 m to 1.2 m.

Optionally, referring to FIG. 5, the roll 200 and the base material section 300 and the lithium belt 100 and the base material section 300 are all connected by an adhesive member 400. In this way, the adhesive member can firmly connect the lithium tape, the base material segment and/or the reel.

Optionally, the adhesive force of the adhesive is greater than 60N. Therefore, it will not be broken during unwinding. When the tensile strength of the adhesive is too small, it is easy to be broken during the unwinding process.

Optionally, the material of the bonding element includes yellow glue, green glue, blue glue, plastic tape, insulating tape, and the like. The adhesive is not easy to absorb water, does not contain strong polar groups, such as carboxyl, hydroxyl, amino, cyano, carbonyl, etc., which can effectively prevent the oxidation of the lithium belt.

The application will be further explained by specific examples below. However, it should be understood that these examples are only used for more detailed description, and should not be understood as limiting the application in any form.

Preparation of lithium belts in Examples 1-16 and Comparative Examples 1-2:

The lithium belts in Examples 1-16 and Comparative Example 2 were obtained by cutting with a cutter according to the parameters in Table 1, where:

The shape of the end face of the initial section of rolling described in Examples 1-11 and Comparative Example 2 is obtained by single-pole shearing in the thickness direction of the lithium ribbon, and the shearing time is 0S～1S, and the shape of the end face of the initial section of rolling is rectangular. 12-13 is obtained by single-pole shearing in the thickness direction of the lithium ribbon, and the shearing time is> 1S, and the end surface shape of the initial section of the calendering is trapezoidal;

Examples 14-16 are obtained by double-knife shearing (such as scissors) in the thickness direction of the lithium ribbon, and the shearing time is> 1S, and the end surface shape of the starting section of the calendering is obtained as a wedge-shaped hexagon;

The lithium belt in Comparative Example 1 was not sheared;

Examples 1-16 and Comparative Example 2 are respectively a kind of lithium belt coils, and the structure of which is shown in FIG. 5. The properties of the lithium strip coils in Examples 1-16 and Comparative Example 2 are listed in Table 1.

Comparative Example 1 is also a lithium ribbon coil. The difference between the structure and the structure with reference to FIG. 5 is that the lithium ribbon in Comparative Example 1 is not sheared and has no rolling start section.

Each parameter and performance test in Examples 1-16 and Comparative Examples 1-2

Lithium belt width and base material section width: Use millimeter size soft ruler to test the width of lithium belt.

Lithium belt thickness: Use a micrometer or a micrometer to test the thickness of the lithium belt.

The width of the calendered lithium foil reaches a stable tape length: When the calendered width of the lithium tape is consistent with the stable width, test the tape length with a meter ruler.

In the lithium strip coils of Examples 1-16 and Comparative Examples 1-2, the width of the main section of the lithium belt, the ratio of the width H of the starting section of the rolling to the width L of the main section, the length of the starting section of the rolling, and the rolling The specific values of the shape of the initial section, the cross-sectional shape of the initial section of the calendering and the minimum angle of the section shape of the initial section of the calendering are shown in Table 1.

Table 1

In the lithium tape coils of Examples 1-16 and Comparative Examples 1-2, the width of the rolled lithium foil obtained by rolling reaches a stable tape length (marked as B), as shown in Table 1.

From the data in Table 1, it can be seen that the width of the main section of the lithium belt, the ratio of the width H of the starting section of the calendering section to the width L of the main section, the length of the starting section of the calendering, the shape of the starting section of the rolling The specific values of the cross-sectional shape of the initial section and the minimum angle of the cross-sectional shape of the rolling initial section have a certain effect on the width of the rolled lithium foil to achieve a stable tape length. The best effect can be achieved through the optimized combination of various parameters. In Comparative Example 1-2, when the ratio of the width H of the starting section of the lithium ribbon to the width L of the main section exceeds the range defined in this application, the width of the rolled lithium foil reaches a stable length, which will cause Waste of lithium belt.

Although specific embodiments have been used to illustrate and describe the application, it should be appreciated that many other changes and modifications can be made without departing from the spirit and scope of the application. Therefore, this means that all these changes and modifications that fall within the scope of this application are included in the appended claims.

Claims

A lithium belt, including:

A calendering start section, and a main body section integrally connected with the calendering start section, the width of the calendering start section is smaller than the width of the main body section;

The ratio of the width H at any position of the calendering starting section to the width L of the main section is greater than or equal to 90% and less than 100%.
The lithium belt according to claim 1, wherein the ratio of the width H at any position of the rolling start section to the width L of the main body section is 94% to 98%.
The lithium belt according to claim 1 or 2, wherein the length of the initial section of rolling is 50 mm to 400 mm.
The lithium belt according to any one of claims 1 to 3, wherein the length of the initial section of rolling is 150 mm to 200 mm.
The lithium belt according to any one of claims 1 to 4, wherein the width of the rolling start section gradually decreases from the main body section to the rolling start section.
The lithium belt according to any one of claims 1 to 5, wherein at least one obtuse angle exists at the starting angle α of the rolling starting section;

Optionally, the shape of the initial section of the calendering is a trapezoid; optionally, the trapezoid is an isosceles trapezoid, and the lower base of the trapezoid is integrally connected with the main body section.
The lithium belt according to any one of claims 1 to 6, wherein the cross-sectional shape of the rolling start section is selected from the group consisting of rectangle, trapezoid, and wedge-shaped hexagon.
The lithium belt according to any one of claims 1 to 7, wherein the cross-sectional shape is rectangular.
The lithium belt according to any one of claims 1 to 7, wherein the cross-sectional shape is a trapezoid, and the smallest angle θ 1 of the trapezoid is greater than or equal to 80° and less than 90°.
The lithium belt according to any one of claims 1 to 7, wherein the cross-sectional shape is a wedge-shaped hexagon, and the angle θ 2 formed by the wedge-shaped hexagon along the thickness direction of the lithium belt is greater than or equal to 80° and less than 180° .
The lithium belt according to any one of claims 1 to 10, wherein the width of the main body section is 60 mm to 350 mm.
The lithium belt according to any one of claims 1 to 11, wherein the thickness of the main body section is 100 mm to 4000 mm.
The lithium belt according to any one of claims 1 to 12, wherein the tensile strength of the lithium belt is 0.9 MPa to 3.0 MPa.
The lithium belt according to any one of claims 1 to 13, wherein the tensile strength of the lithium belt is 0.9 MPa to 1.5 MPa.
The lithium belt according to any one of claims 1 to 14, wherein the elongation at break of the lithium belt is ≥10%.
The lithium belt according to any one of claims 1 to 15, wherein the elongation at break of the lithium belt is ≥ 25%.
A lithium belt coil, which comprises a reel and the lithium belt according to any one of claims 1-16 wound on the reel.
The lithium ribbon coil of claim 17, wherein the reel and the lithium ribbon are connected by a base material section, one end of the base material section is connected to the reel, and the other end of the base material section Connect the main body section;

Optionally, the material of the base material segment includes one of a metal strip, a polymer material strip, or a composite material film.
The lithium ribbon coil according to any one of claims 17 or 18, wherein the width of the substrate section is less than or equal to the width of the reel.
The lithium ribbon coil according to any one of claims 17 to 19, wherein the width of the reel is 40 mm wider than the width of the lithium ribbon.
The lithium ribbon coil according to any one of claims 17 to 20, wherein the difference between the width of the base material section and the width of the main body section is M, and the ratio of M to the width of the main body section ranges from -5%～+5%.
The lithium belt coil according to any one of claims 17 to 21, wherein the length of the base material section is 0.4 m to 1.2 m; optionally, the length of the base material section is 1 m to 1.2 m.