Lithium supplementing device

Abstract

Disclosed is a lithium supplementing device. The lithium supplementing device comprises: a pole piece conveying mechanism configured to convey a pole piece; a lithium band conveying mechanism configured to convey a lithium band; a calendering mechanism, comprising a first calendering roller and a second calendering roller, with a gap capable of accommodating a lithium band being provided between the first calendering roller and the second calendering roller; a transfer roller is located between the second calendering roller and the pole piece and abuts the pole piece, and an auxiliary film is sleeved between the second calendering roller and the transfer roller; when a lithium band is located in the gap, two sides of the lithium band respectively abut the first calendering roller and the auxiliary film; the calendering mechanism is configured for calendering a lithium band through the gap to form a lithium foil, and for adhering same to an auxiliary film, and the transfer roller is configured for attaching to a pole piece the lithium foil adhered to the auxiliary film.

Description

TECHNICAL FIELD

[0002] The present application relates to the technology field of production and manufacturing of lithium batteries, in particular relates to a lithium supplementing device.BACKGROUND

[0003] Due to the advantages of high energy density, long cycle life, and no memory effect, lithium-ion batteries are widely used in fields such as consumer electronics and new energy vehicles, etc. However, during the first charging and discharging process of the electrode material in lithium-ion batteries, the formation of a solid electrolyte film results in lithium loss, which limits the energy density of lithium-ion batteries. This is particularly evident in silicon-based negative electrode material systems, and the active lithium loss caused by side reactions during the cycling process would shorten the cyclic life.

[0004] In order to solve this problem, related arts use a lithium supplementing device to supplement lithium for the electrode sheet, so as to improve the energy density and cyclic life of lithium-ion batteries. The lithium supplementing device has the following two forms:

[0005] In the first form, the lithium supplementing device adopts the form of separate calendering and one-time film covering. The lithium supplementing device comprises an electrode sheet conveying mechanism, a lithium band conveying mechanism, an auxiliary film conveying mechanism, and a transfer mechanism. The electrode sheet conveying mechanism is configured to convey an electrode sheet, the lithium band conveying mechanism is configured to convey a lithium band, and the auxiliary film conveying mechanism is configured to convey an auxiliary film. The two sides of the lithium band can abut against the auxiliary film and the transfer mechanism respectively, so that the calendered lithium band is bonded to the surface of the transfer mechanism, the transfer mechanism then transfers the lithium band onto the electrode sheet, thereby realizing the process of supplementing lithium for the electrode sheet. Since both sides of the lithium band can abut against the auxiliary film and the transfermechanism respectively, the auxiliary film provides support for the lithium band. During the lithium supplementing process, the auxiliary film only covers the surface of the lithium band for one time. For an electrode sheet that requires lithium supplementing on both sides thereof, an auxiliary film with twice as much the area of the electrode sheet needs to be consumed, and the auxiliary film cannot be reused, resulting in high costs for lithium supplementing.

[0006] In the second form, the lithium supplementing device adopts the form of integrated calendering without using an auxiliary film. The transfer mechanism of the lithium supplementing device not only plays a transfer role, but also plays a calendering role. For the calendering process, the transfer mechanism needs to have a relatively small size to calender a relatively thick lithium band into a relatively thin lithium foil; and for the transfer process, the transfer mechanism needs to have a relatively large size to reduce the elongation effect for the electrode sheet, so there is a problem that it is difficult for the transfer mechanism to balancing between the requirements of the calendaring process and the transfer process.SUMMARY

[0007] The present application provides a lithium supplementing device that cansimultaneously meet the functional requirements of calendering and transfer, achieve the circulation of auxiliary film, and save production costs.

[0008] A lithium supplementing device comprises:

[0009] an electrode sheet conveying mechanism, configured to convey an electrode sheet;

[0010] a lithium band conveying mechanism, configured to convey a lithium band;

[0011] a calendering mechanism, comprising a first calendering roller and a secondcalendering roller, wherein a gap for accommodating the lithium band is formed between the first calendering roller and the second calendering roller;

[0012] a transfer roller, located between the second calendering roller and the electrode sheet and arranged to abut against the electrode sheet, wherein an auxiliary film is wound between the second calendering roller and the transfer roller,

[0013] when the lithium band is received in the gap, two sides of the lithium band arearranged to abut against the first calendering roller and the auxiliary film respectively, thecalendering mechanism is configured to calender the lithium band through the gap to form a lithium foil and attach the lithium foil to the auxiliary film, and the transfer roller is configured to adhere the lithium foil, which has been attached to the auxiliary film, onto the electrode sheet.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a structural schematic diagram of a lithium supplementing device provided in an embodiment of the present application;

[0015] Figure 2 is a structural schematic diagram of the surface of a transfer roller in a lithium supplementing device provided in an embodiment of the present application;

[0016] Figure 3 is a structural schematic diagram of the surface of the transfer roller in another lithium supplementing device provided in an embodiment of the present application.

[0017] In the drawings:

[0018] 100. auxiliary film;

[0019] 1. electrode sheet conveying mechanism; 2. lithium band conveying mechanism; 3. support roller; 4. calendering mechanism; 5. release agent coating mechanism; 6. cleaning mechanism; 7. transfer roller;

[0020] 11. electrode sheet discharge roller; 12. electrode sheet receiving roller;

[0021] 41. first calendaring roller; 42. second calendaring roller;

[0022] 71. protrusion.DETAILED DESCRIPTION

[0023] The technical solution of the embodiments of the present application will be described hereinafter in conjunction with the drawings. The described embodiments are only a part of the embodiments of the present application.

[0024] In the description of the present application, it needs to be noted that, unless expressly specified and defined otherwise, the terms such as "connection", "connected", and "fixed" should be understood in a broad sense, for example, it may be fixedly connected, detachably connected or integrally connected; it may be mechanically connected or electrically connected; it may be connected directly or connected indirectly through an intermediate medium, or it may be internal communication between two elements or interaction relationship between two elements. For a person skilled in the art, specific meanings of the above terms in the present application should be understood according to the circumstances thereof.

[0025] In the present application, it needs to be noted that, unless expressly specified and defined otherwise, the first feature being "above" or "below" the second feature may comprise direct contact between the first and second features, it may also comprise that the first and second features are not directly in contact with each other but rather contact through another feature between them. Moreover, the first feature being "above", "on", and "over" the second feature comprises the first feature being directly above or diagonally above the second feature, or simply indicates that the horizontal height of the first feature is higher than that of the secondfeature. The first feature being "below", "beneath", and "under" the second feature comprises the first feature being directly below and diagonally below the second feature, or simply indicates that the horizontal height of the first feature is lower than that of the second feature.

[0026] The technical solution of the present application is explained below in conjunction with the drawings and specific embodiments.

[0027] The present embodiment provides a lithium supplementing device configured to supplement lithium for an electrode sheet. As shown in Figure 1, the lithium supplementing device comprises an electrode sheet conveying mechanism 1, a lithium band conveying mechanism 2, a calendering mechanism 4 and a transfer roller 7. The electrode sheet conveying mechanism 1 is configured to convey an electrode sheet, the lithium band conveying mechanism 2 is configured to convey a lithium band, the calendering mechanism 4 is configured to calendar the lithium band, wherein an auxiliary film 100 is wound between the calendering mechanism 4 and the transfer roller 7. The lithium band can be calendered into a lithium foil and attached to the surface of the auxiliary film 100, which provides support and transfer function for the lithium band. The transfer roller 7 is located between the calendering mechanism 4 and the electrode sheet and abuts against the electrode sheet. The transfer roller 7 has a function of intermediate transfer, and the lithium foil is caused to be adhered to the electrode sheet by means of the transfer roller 7.

[0028] The electrode sheet conveying mechanism 1 comprises an electrode sheet discharge roller 11 and an electrode sheet receiving roller 12. The electrode sheet is respectively wound around the electrode sheet discharge roller 11 and the electrode sheet receiving roller 12. The electrode sheet discharge roller 11 is configured to discharge the electrode sheet, and the electrode sheet receiving roller 12 is configured to receive the electrode sheet for which the lithium supplementing has been completed. At least one of the electrode sheet discharge roller 11 and the electrode sheet receiving roller 12 can rotate to drive the movement of the electrode sheet, thereby realizing the transportation process of the electrode sheet. The lithium band conveying mechanism 2 comprises a lithium band discharge roller, wherein the lithium band is wrapped around the exterior of the lithium band discharge roller. The lithium band discharge roller is configured to discharge the lithium band, and the lithium band discharge roller can rotate to drive the movement of the lithium band, thereby realizing the transportation process of the lithium band.

[0029] If the auxiliary film 100 covers the surface of the lithium band for only one time during the lithium supplementing process, for an electrode sheet that requires lithium supplementing on both sides thereof, an auxiliary film 100 with twice as much the area of the electrode sheet needs to be consumed, and the auxiliary film 100 cannot be reused, resulting in high costs for lithium supplementing. Meanwhile, if the calendering mechanism 4 and the transfer roller 7 are used for calendering, the transfer roller 7 has the problem of being unable to balance between the requirements of the calendering process and the transfer process.

[0030] In order to solve this problem, the calendering mechanism 4 comprises a first calendering roller 41 and a second calendering roller 42, wherein a gap for accommodating and calendering the lithium band is formed between the first calendering roller 41 and the second calendering roller 42. The lithium band conveying mechanism 2 can discharge the lithium band into the gap between the first calendering roller 41 and the second calendering roller 42. If the thickness of the lithium band is greater than 1mm, the lithium band is a thick lithium band. The gap between the first calendering roller 41 and the second calendering roller 42 is relatively small. Under the joint action of the first calendering roller 41 and the second calendering roller 42, the lithium band can be calendered into a lithium foil with a thickness between 2pm-10pm, so as to complete the process of calendering a thick lithium band into an ultra-thin lithium foil.

[0031] During this process, an auxiliary film 100 is wound between the second calendering roller 42 and the transfer roller 7. The second calendering roller 42 not only achieves the calendering effect, but also supplies the auxiliary film 100. The two sides of the lithium band can respectively abut against the first calendering roller 41 and the auxiliary film 100, the auxiliary film 100 provides support and transfer function for the lithium band. The lithium band can be calendered into a lithium foil and attached to the auxiliary film 100, and the lithium foil is caused to be adhered to the electrode sheet by means of the transfer roller 7, which has a function of transferring the lithium foil. At the same time, the electrode conveying mechanism 1 is configured to transport the electrode sheet. By setting the transfer roller 7 to be located between the second calendering roller 42 and the electrode sheet and abutting against the electrode sheet, the lithium foil that has been attached to the surface of the auxiliary film 100 becomes adhered to the electrode sheet under the action of pressure, thus completing the lithium supplementing process for the electrode sheet.

[0032] The lithium supplementing device provided in the present embodiment, under the joint action of the transfer roller 7 and the second calendering roller 42, enables the auxiliary film 100 to form a closed loop structure, thereby achieving the recycling of the auxiliary film 100. As compared to the one-time use of the auxiliary film 100 in related arts, the reuse rate of the auxiliary film 100 is high, and production costs are saved by introducing the auxiliary film 100 that can be recycled in a closed-loop manner. By setting a gap between the first calendering roller 41 and the second calendering roller 42 that can accommodate and calender the lithium band, the calendering process is completed. The auxiliary film 100 causes the lithium foil to be adhered onto the electrode sheet by means of the transfer roller 7, thereby completing thelithium foil transfer bonding process. By adding the auxiliary film 100, the calendering process and the transfer process are separated from each other, so that the functional requirements of both calendering and transfer can be simultaneously met, and a good balance is achieved therebetween.

[0033] The diameter of the first calendering roller 41 and the diameter of the second calendering roller 42 are both d, and the diameter of the transfer roller 7 is D, wherein d<D. In the present embodiment, 100mm ≤ d ≤ 200mm, 200mm ≤ D ≤ 500mm. By setting the two calendering rollers with smaller diameters and using the two calendering rollers with smaller diameters in the calendering process, a relatively thick lithium band can be calendered in to a relatively thin lithium foil, thus realizing the preparation of an ultra-thin metal lithium foil. By setting the diameter size of the transfer roller 7 to be larger, the transfer roller 7 with a large diameter is used in the transfer process to prevent the elongation of the electrode sheet from being caused during the transfer process of the lithium foil, so as to achieve the goal of reducing the elongation effect for the electrode sheet.

[0034] The linear speed v1 of the first calendering roller 41 is less than or equal to the linear speed v2 of the second calendering roller 42, and in this embodiment, 0.4 ≤ v1 / v2 ≤ 1. By setting the linear speed v1 of the first calendering roller 41 to be less than or equal to the linear speed v2 of the second calendering roller 42, there is a linear speed difference between the two calendering rollers to ensure the calendering effect for the lithium foil.

[0035] Since the auxiliary film 100 has a supporting effect on the thinning and lengthening of the lithium foil during the calendering process of the lithium band, when the lithium foil needs to be adhered to the electrode sheet, it is necessary for the lithium foil to be able to separate from the auxiliary film 100. If the lithium foil and the auxiliary film 100 cannot be separated, the auxiliary film 100 is prone to deviation along with the movement of the lithium band, thereby adversely affecting the transfer of the lithium foil by the transfer roller 7.

[0036] In order to solve this problem, the total friction force between the auxiliary film 100 and the second calendering roller 42 and between the auxiliary film 100 and the transfer roller 7 is greater than the friction force between the auxiliary film 100 and the lithium band. That is to say, the sum of the friction force between the auxiliary film 100 and the second calendering roller 42 and the friction force between the auxiliary film 100 and the transfer roller 7 is greater than the friction force between the auxiliary film 100 and the lithium band. The auxiliary film 100 is made of polyester (PET) fiber film, polypropylene (PP) film, polyethylene (PE) film, or a stainless-steel foil. The outer surface of the auxiliary film 100 is smoothed, and the inner surface of the auxiliary film 100 is roughened, so that the total friction force between the inner surface of the auxiliary film 100 and the second calendering roller 42 and between the inner surface of the auxiliary film 100 and the transfer roller 7 is greater than the resistance force acted on the calendering mechanism 4 and the transfer roller 7 when calendering the lithium band, thereby realizing synchronous running of the auxiliary film 100 together with the second calendering roller 42 and the transfer roller 7 to prevent deviation of the auxiliary film 100, and thus ensuring the lithium supplementing effect of the transfer roller 7 on the electrode sheet.

[0037] In order to achieve the extension and calendering of the lithium band and to attach the calendered lithium foil to the auxiliary film 100, before calendering the lithium band, a release agent such as polymethyl siloxane and polyether is coated on surfaces of both sides of the lithium band. By adjusting the type and coating amount of the release agent, the release force on the side of the auxiliary film is greater than that on the side of the first calendering roller 41, so that the lithium foil can be fully attached to the outer surface of the auxiliary film 100, thereby ensuring the calendering effect for the lithium band while ensuring the separation of the lithium foil from the first calendering roller 41.

[0038] The release agent has a conductive agent or a lithium salt or a mixture of conductive agent and lithium salt added therein, so that the release agent has ionic, electronic, or mixed conductivity, thereby reducing the impact of the release agent on the diffusion of lithium ions.

[0039] In order to improve the calendering effect for the metal lithium foil, the lithium supplementing device also comprises a release agent coating mechanism 5, which is located between the lithium band conveying mechanism 2 and the first calendering roller 41 and is configured to apply the release agent onto the lithium band, playing a role in supplementally coating the release agent on the lithium band. The coating method can be any one of spray coating, extrusion coating, and transfer coating.

[0040] The lithium supplementing device further comprises a support roller 3, wherein the auxiliary film 100 is wound on outer surfaces of the support roller 3, the second calendering roller 42, and the transfer roller 7 respectively. Under the synergistic action of the support roller 3, the second calendering roller 42, and the transfer roller 7, the auxiliary film 100 can form a closed loop structure, thereby achieving the recycling of the auxiliary film 100. As compared to the one-time use of the auxiliary film 100 in related arts, the reuse rate of the auxiliary film 100 is high, and production costs are saved by introducing the auxiliary film 100 that can be recycled in a closed-loop manner.

[0041] The position of the support roller 3 is adjustable, and the tension of the auxiliary film 100 is controlled by controlling the position of the support roller 3.

[0042] The auxiliary film 100 is detachably connected to the support roller 3 and the second calendering roller 42. By setting the auxiliary film 100 as a detachable structure, the auxiliary film 100 can be regularly replaced according to the external surface release force and damage degree during usage, so as to ensure that the auxiliary film 100 has a good auxiliary support effect on the lithium band at all times.

[0043] In order to improve the electrolyte wetting effect of the electrode sheet, the lithium supplementing method can also be lithium supplementing in a striped manner. To achieve lithium supplementing in a striped manner, as shown in Figures 1 to 3, protrusions 71 are arranged on the outer wall of the transfer roller 7. By arranging the protrusions 71, the protrusions 71 reduce the contact area and increase the pressure. Under the action of the increased pressure, the part of the lithium foil corresponding to the position of the protrusions 71 can be better transferred onto the electrode sheet.

[0044] The protrusions 71 can be arranged along the circumferential direction of the transfer roller 7 (as shown in Figure 2), and the number of protrusions 71 may be multiple. An extending direction of each of the protrusions 71 is parallel to an axial direction of the transfer roller 7 and the protrusions 71 are distributed in parallel to be spaced apart in the circumferential direction of the transfer roller 7, thereby forming a transverse striped structure.

[0045] The protrusions 71 can be arranged along the axial direction of the transfer roller 7 (as shown in Figure 3), and the number of protrusions 71 may be multiple. An extending direction of each of the protrusions 71 is perpendicular to an axial direction of the transfer roller 7 and the protrusions 71 are distributed in parallel to be spaced apart in the axial direction of the transfer roller 7, thereby forming a vertical striped structure. The striped structure is utilized to improve the uniformity of lithium foil transfer.

[0046] Due to the inevitable residual residues between every two adjacent protrusions 71 during the transfer process, as shown in Figure 1, the lithium supplementing device further comprises a cleaning mechanism 6, which is configured to clean residues on the auxiliary film 100 to prevent residual metal lithium residues from sticking to the electrode sheet and adversely affecting the flatness of the electrode sheet surface. The cleaning mechanism 6 comprises a scraper and a suction nozzle, wherein the scraper is configured to separate the residues from the auxiliary film 100, and the suction nozzle is configured to suck the residues thereinto.

[0047] The above mechanism can be configured to supplement lithium for one side of the electrode sheet. If the electrode sheet needs lithium supplementing on both sides thereof, the numbers of the lithium band conveying mechanism 2, the support roller 3, the first calendering roller 41, the second calendering roller 42, the transfer roller 7, the release agent coating mechanism 5, and the cleaning mechanism 6 are all two, and they are symmetrically arranged on both sides of the electrode sheet, which is equivalent to two systems simultaneously supplementing lithium on both sides of the electrode sheet, with good synchronization and high production efficiency.

[0048] In the description of the present application, it needs to be understood that orientational or locational relationships indicated by terms such as "up", "down", "right" are based on orientational or locational relationships shown in the drawings, and are only used to facilitate description and simplify description, but are not used to indicate or imply that the apparatuses or elements referred to must have a specific orientation or must be constructed and operated in a specific orientation, and therefore, cannot be understood as a limitation to the present application. In addition, the terms such as "first" and "second" are only used for distinguish one element from another element in description, without any special meaning.

[0049] In the description of the present specification, the description of reference terms "one embodiment", "example", etc. means that the features, structures, materials, or features described in this embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example.

Claims

1. A lithium supplementing device, characterized in comprising: an electrode sheet conveying mechanism (1), configured to convey an electrode sheet; a lithium band conveying mechanism (2), configured to convey a lithium band; a calendering mechanism (4), comprising a first calendering roller (41) and a second calendering roller (42), wherein a gap for accommodating the lithium band is formed between the first calendering roller (41) and the second calendering roller (42); a transfer roller (7), located between the second calendering roller (42) and the electrode sheet and arranged to abut against the electrode sheet, wherein an auxiliary film (100) is wound between the second calendering roller (42) and the transfer roller (7), when the lithium band is received in the gap, two sides of the lithium band are arranged to abut against the first calendering roller (41) and the auxiliary film (100) respectively, the calendering mechanism (4) is configured to calender the lithium band through the gap to form a lithium foil and attach the lithium foil to the auxiliary film (100), and the transfer roller (7) is configured to adhere the lithium foil, which has been attached to the auxiliary film (100), onto the electrode sheet.

2. The lithium supplementing device according to claim 1, characterized in that, a diameter of the first calendering roller (41) and a diameter of the second calendering roller (42) are both d, and a diameter of the transfer roller (7) is D, wherein d is less than D.

3. The lithium supplementing device according to claim 1, characterized in that, a linear speed of the first calendering roller (41) is less than or equal to a linear speed of the second calendering roller (42).

4. The lithium supplementing device according to claim 1, characterized in further comprising: a release agent coating mechanism (5), which is located between the lithium band conveying mechanism (2) and the first calendering roller (41) and is configured to apply a release agent onto the lithium band.

5. The lithium supplementing device according to claim 4, characterized in that, the release agent has a conductive agent or a lithium salt or a mixture of conductive agent and lithium salt added therein.

6. The lithium supplementing device according to claim 1, characterized in that, a total friction force between the auxiliary film (100) and the second calendering roller (42) and between the auxiliary film (100) and the transfer roller (7) is greater than a friction force between the auxiliary film (100) and the lithium band.

7. The lithium supplementing device according to claim 1, characterized in further comprising: a support roller (3), wherein the auxiliary film (100) is wound on outer surfaces of the support roller (3), the second calendering roller (42), and the transfer roller (7) respectively.

8. The lithium supplementing device according to claim 1, characterized in that, an outer wall of the transfer roller (7) is provided with a protrusion (71).

9. The lithium supplementing device according to claim 8, characterized in that, multiple protrusions (71) are provided, wherein an extending direction of each of the protrusions (71) is perpendicular to an axial direction of the transfer roller (7) and the protrusions (71) are distributed in parallel to be spaced apart in the axial direction of the transfer roller (7), or wherein an extending direction of each of the protrusions (71) is parallel to the axial direction of the transfer roller (7) and the protrusions (71) are distributed in parallel to be spaced apart in the circumferential direction of the transfer roller (7).

10. The lithium supplementing device according to claim 8, characterized in further comprising: a cleaning mechanism (6) configured to clean residues on the auxiliary film (100).