Battery cell lithium supplementing device and lithium supplementing battery

Abstract

The utility model relates to the technical field of battery production and processing, in particular to a battery cell lithium supplementing device and a lithium supplementing battery. The lithium supplementing structure is provided with a lithium supplementing area used for supplementing lithium for the battery cell and a conductive area connected with a battery shell, the lithium supplementing area is arranged on the insulating film, and the conductive area extends out of the insulating film; the packaging structure covers the lithium supplementing area, and the lithium supplementing area is packaged by the packaging structure and the insulating film together; wherein the packaging structure is a polyvinylidene fluoride (PVDF) film (PVDF film). According to the lithium supplementing device for the battery cell, continuous lithium supplementing for the battery cell is realized, and the condition of subsequent insufficiency existing in one-time lithium supplementing is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of battery production and processing, and more specifically, to a lithium supplementing device for battery cells and a lithium-supplemented battery. Background Art

[0002] In recent years, with the rapid development of new energy vehicles, higher requirements have been continuously put forward for various performances of lithium-ion batteries, among which the improvement of battery energy density is the most urgent.

[0003] In the existing lithium-ion battery system, on the one hand, the energy density can be improved by optimizing the battery structure; on the other hand, the battery energy density can be greatly improved by iterating the cathode and anode materials. In addition, the lithium supplementing technology for lithium-ion batteries is also an important means to improve the battery energy density.

[0004] The lithium supplementing technology is a technology aimed at improving the energy density of lithium-ion batteries and extending the battery life. It is mainly used to compensate for the irreversible loss of lithium during the first charge-discharge cycle of the battery. During the first charging process of the lithium-ion battery, lithium ions move from the positive electrode to the negative electrode, forming a protective layer called the solid electrolyte interface (SEI) film on the surface of the negative electrode. This process permanently consumes a part of lithium ions, reducing the initial capacity and energy density of the battery. In addition, there are also processes such as the inactivation of negative electrode material particles due to shedding and the irreversible deposition of lithium metal, all of which will consume active lithium and reduce the capacity and energy density of the battery.

[0005] The basic principle of the lithium supplementing technology is to pre-add extra lithium during the battery manufacturing process to compensate for the lithium loss caused by the formation of the SEI film and other irreversible reactions. In this way, when the battery is first charged, although the SEI film will still be formed, the actual capacity of the battery will not decrease significantly like that of the non-lithium-supplemented battery, thereby improving the overall energy density of the battery and the coulombic efficiency (ICE) of the first cycle.

[0006] The Chinese utility model patent with the publication number of CN218568926U discloses a lithium battery preform and a lithium-ion battery. By arranging a second encapsulation structure and a lithium supplementing structure outside the battery cell structure, in this way, before the first charge-discharge of the battery, the negative electrode can be pre-lithiated by means of electrochemical pre-lithiation, that is, the connecting piece connecting the negative electrode tab and the lithium supplementing structure conducts a discharging process, thereby supplementing lithium to the negative electrode of the battery cell structure to improve the first coulombic efficiency of the battery and thus improve the reversible capacity of the battery; after the lithium supplementing is completed, the second encapsulation structure is removed from the first encapsulation structure, thereby removing the lithium supplementing structure from the battery cell structure. In this way, the additional weight of the lithium-ion battery can be avoided, which is more conducive to the improvement of the energy density and can also reduce the battery safety risk.

[0007] However, although the lithium battery preforms mentioned above can achieve lithium replenishment, there are still some defects, such as the speed and period of lithium replenishment cannot be controlled. Utility Model Content

[0008] The main purpose of the utility model is to provide a battery cell lithium replenishing device and a lithium replenishing battery, aiming to solve the technical problems mentioned in the background technology.

[0009] In order to solve the above technical problems, the utility model, on the one hand, proposes a battery cell lithium replenishing device, comprising:

[0010] Insulating film;

[0011] The lithium replenishment structure comprises a lithium replenishment area for replenishing lithium for the battery cell and a conductive area connected to the battery housing, wherein the lithium replenishment area is arranged on the insulating film and the conductive area extends out of the insulating film;

[0012] and a packaging structure, which covers the lithium replenishment area and packages the lithium replenishment area together with the insulating film;

[0013] Among them, the packaging structure is a polyvinylidene fluoride film (PVDF film).

[0014] In the above technical solution, further, the lithium supplement structure includes:

[0015] A lithium supplement layer is disposed on the insulating film;

[0016] and a conductive sheet covering the lithium replenishing layer, with at least one end thereof extending out of the insulating film;

[0017] The lithium replenishment layer and part of the conductive sheet on the insulating film together form a lithium replenishment area, and part of the conductive sheet extending out of the insulating film forms a conductive area.

[0018] In any of the above technical solutions, further, there are multiple lithium replenishing layers, which are distributed in an array on the insulating film.

[0019] In any of the above technical solutions, further, a plurality of holes are provided on the conductive sheet;

[0020] The holes and the lithium supplement layers are staggered.

[0021] In any of the above technical solutions, further, the size of the portion of the conductive sheet located on the insulating film is smaller than the size of the PVDF film.

[0022] In any of the above technical solutions, further, the thickness of the PVDF membrane is 0.1 mm-0.3 mm.

[0023] In any of the above technical solutions, further, the conductive area can be bent, and a protective adhesive layer is provided at the bending portion.

[0024] In any of the above technical solutions, further, the lithium compensation area is arranged on the covering surface of the insulating film corresponding to the bottom surface of the battery cell.

[0025] In any of the above technical solutions, further, the size of the PVDF film is smaller than the size of the covering surface of the insulating film corresponding to the bottom surface of the battery cell.

[0026] On the other hand, a lithium compensation battery is also proposed, including: a housing, and a battery cell arranged in the housing; wherein, it further includes: the battery cell lithium compensation device described above;

[0027] Wherein, the insulating film is coated on the battery cell, and the conductive area is connected to the housing.

[0028] Beneficial effects: Compared with the prior art, a lithium compensation area is arranged on the insulating film, and the lithium compensation area is encapsulated by the PVDF film. After the battery is injected with electrolyte, that is, when the PVDF film is immersed in the electrolyte, after a period of time (about 200 charge-discharge cycles), the PVDF film will swell in the electrolyte. During this process, the electrolyte penetrates into the PVDF film, enabling the lithium ions in the lithium compensation area to slowly and stably pass through the PVDF film to compensate the lithium of the battery cell. By continuously releasing lithium ions from the lithium compensation area, continuous lithium compensation of the battery cell is achieved, avoiding the subsequent deficiencies existing in one-time lithium compensation. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0030] Figure 1 It is a schematic structural diagram of the present invention;

[0031] Figure 2 It is a schematic structural diagram of the conductive sheet of the present invention.

[0032] The description of the reference numerals is as follows:

[0033] 100, insulating film; 101, crease; 200, lithium compensation structure; 210, lithium compensation layer; 220, conductive sheet; 221, hole; 222, protective adhesive layer; 300, PVDF film. Detailed Embodiments

[0034] Next, exemplary embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. It should be understood that the present application is not limited by the exemplary embodiments described herein. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] It should be noted that, as shown in the present application and the claims, unless the context clearly indicates an exception, words such as "a", "an", "one" and / or "the" are not specifically singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0036] If there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, then such directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the drawings). If this specific posture changes, then the directional indications will also change accordingly.

[0037] In the present invention, unless otherwise clearly defined and limited, terms such as "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the communication inside two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, then such descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and / or" appearing throughout the text includes three parallel scenarios. Taking "A and / or B" as an example, it includes scenario A, scenario B, or the scenario where both A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0039] The following is a detailed description of a lithium supplementation device for battery cells and a lithium-supplemented battery according to the present application through the following embodiments.

[0040] Embodiment 1:

[0041] As Figure 1 shown, in this embodiment, a lithium supplementation device for battery cells includes: an insulating film 100; a lithium supplementation structure 200, which has a lithium supplementation area for supplementing lithium to the battery cells and a conductive area connected to the battery housing. The lithium supplementation area is disposed on the insulating film 100, and the conductive area extends out of the insulating film 100; and a packaging structure that covers the lithium supplementation area and jointly packages the lithium supplementation area with the insulating film 100;

[0042] Among them, the packaging structure is a PVDF film 300.

[0043] Among them, the lithium supplementation structure 200 includes: a lithium supplementation layer 210 disposed on the insulating film 100; and a conductive sheet 220 covering the lithium supplementation layer 210, and at least one end of the conductive sheet 220 extends out of the insulating film 100;

[0044] Among them, the lithium supplementation layer 210 and a part of the conductive sheet 220 located on the insulating film 100 jointly form the lithium supplementation area, and the part of the conductive sheet 220 extending out of the insulating film 100 forms the conductive area.

[0045] Among them, the size of the part of the conductive sheet 220 located on the insulating film 100 is smaller than the size of the PVDF film 300.

[0046] It should be noted that the size of the conductive sheet 220 forming the lithium supplementation area, that is, the part of the conductive sheet 220 located on the insulating film 100, is smaller than the size of the PVDF film 300, so as to ensure that the conductive sheet 220 and the battery cells do not come into direct contact, thus avoiding safety problems.

[0047] It should be noted that the present application uses the PVDF film 300 to package the lithium supplementation area because the PVDF film is a common substance in the preparation process of battery electrodes, thereby avoiding the introduction of new impurities.

[0048] Among them, the lithium supplementation structure 200 is disposed on the bottom surface of the battery cell, that is, the lithium supplementation area is disposed on the covering surface of the insulating film 100 corresponding to the bottom surface of the battery cell.

[0049] Among them, the size of the PVDF film 300 is smaller than the size of the covering surface of the insulating film 100 corresponding to the bottom surface of the battery cell.

[0050] It should be noted that the lithium supplementation layer 210 in the present application is a lithium supplementing agent, and the selection of the lithium supplementing agent can refer to the conventional selection in the art, and the present application does not make specific limitations.

[0051] At present, some existing structures for replenishing lithium in battery cells all use a pre-embedded method to directly replenish lithium in the battery cells. Due to structural limitations, lithium replenishment is one-time and cannot be replenished continuously. For this reason, the present application sets a lithium replenishment area on the insulating film, and encapsulates the lithium replenishment area through a PVDF film 300. The PVDF film 300 is a polyvinylidene fluoride film, which is a polymer material with multiple excellent properties. After the battery is injected with electrolyte, that is, when the PVDF film 300 is immersed in the electrolyte, after a period of time (about 200 charge and discharge cycles), the PVDF film will swell in the electrolyte. In this process, the electrolyte penetrates into the PVDF film 300, so that the lithium ions in the lithium replenishment area can slowly and stably pass through the PVDF film 300 to replenish the lithium in the battery cell. The lithium ions are released for a long time by the lithium replenishment area, thereby achieving continuous lithium replenishment of the battery cell and avoiding the subsequent shortage of one-time lithium replenishment.

[0052] The thickness of the PVDF film 300 is 0.1 mm-0.3 mm.

[0053] It should be noted that the swelling rate of the PVDF film 300 is closely related to its thickness. This feature allows us to accurately control the lithium replenishment period and lithium replenishment speed of the lithium replenishment device by adjusting the thickness of the PVDF film 300. According to specific needs, the thickness of the PVDF film 300 can be set to 0.1mm-0.3mm to achieve the best lithium replenishment effect. This precise control capability not only improves the performance stability of the battery cell, but also extends its service life.

[0054] It should be noted that after swelling, the thickness of the PVDF membrane 300 increases. The enlarged PVDF membrane 300 can fill the space of the battery cell in the height direction, thereby preventing the battery cell from shaking in its shell to a certain extent.

[0055] There are a plurality of lithium replenishing layers 210 , which are distributed on the insulating film 100 in an array.

[0056] It should be noted that the lithium replenishing layer 210 is actually a lithium replenishing point. The lithium replenishing agent can be sprayed on the insulating film 100 by spraying. In order to achieve continuous replenishment of lithium ions, the lithium replenishing points are sprayed on the insulating film 100 in an array.

[0057] Embodiment 2:

[0058] This embodiment is a further improvement made on the basis of the first embodiment.

[0059] like Figure 1 As shown, in this embodiment, the conductive area can be bent, and a protective adhesive layer 222 is disposed at the bending portion.

[0060] Since the conductive area needs to be in contact with the shell to achieve the purpose of conduction, the conductive area is bendable and can be accommodated by the shell by bending. Then, in order to avoid breakage after bending or wear of the battery cell at the bent part, a protective rubber layer 222 is provided to play a buffering role.

[0061] Embodiment three:

[0062] This embodiment is a further improvement made on the basis of any of the above embodiments.

[0063] like Figure 1 As shown, in this embodiment, the insulating film 100 is further provided with a fold 101 to enable the insulating film 100 to be bent.

[0064] In order to control the space occupied by the entire lithium replenishing device when assembled on the battery cell, a fold 101 is provided. The fold 101 is in the shape of an H. The lithium replenishing area is located at a position corresponding to the bottom surface of the battery cell. After bending, the insulating film 100 is U-shaped. This design can well ensure the stability of the lithium replenishing device installed on the battery cell and prevent it from falling off.

[0065] Embodiment 4:

[0066] This embodiment is a further improvement made on the basis of any of the above embodiments.

[0067] like Figure 1 and Figure 2 As shown, in this embodiment, the conductive sheet 220 may be a strip-shaped sheet structure, which is directly laid on the insulating film 100 and covers the lithium replenishing layer 210 .

[0068] In order to reduce the cost, the structure of the conductive sheet 220 can be improved. For example, a plurality of holes 221 in an array can be provided on the conductive sheet 220. The holes 221 on the conductive sheet 220 are staggered with the lithium replenishing layer 210, so that the lithium replenishing layer 210 is exactly located at the metal position of the conductive sheet 220, thereby ensuring that the lithium replenishing layer 210 can be connected to the battery shell. In this way, not only the weight of the conductive sheet 220 can be reduced, but also the production cost of the conductive sheet 220 can be saved.

[0069] Embodiment five:

[0070] This embodiment is a further improvement made on the basis of any of the above embodiments.

[0071] In this embodiment, the insulating film 100 is a Mylar film. The Mylar film is a polyester film made of polyester fiber and has extremely high insulation properties. It can effectively isolate the battery cells and the casing in the battery to prevent direct charge conduction, thereby avoiding the occurrence of short circuit accidents.

[0072] Embodiment six:

[0073] This embodiment proposes a lithium supplement battery, which is a further improvement made on the basis of any of the above embodiments.

[0074] In this embodiment, the lithium replenishing battery comprises: a shell, and a battery cell arranged in the shell; wherein, it also comprises: the battery cell lithium replenishing device mentioned above;

[0075] The insulating film 100 is coated on the battery core, and the conductive area is connected to the outer shell.

[0076] Specifically, the preparation process of the battery cell lithium replenishment device provided in the present application can be described as follows: take out the Mylar film and place it on the workbench, and then spray the lithium replenishing agent in an array on the coating surface of the Mylar film corresponding to the bottom surface of the battery cell to form a lithium replenishing layer 210, and then place the conductive sheet 220, so that the holes 221 on the conductive sheet 220 are staggered with the lithium replenishing layer 210, and the protective glue layer 222 on the conductive sheet 220 is located at the edge of the Mylar film, and then cover the PVDF film 300 on the conductive sheet 220, and heat press the PVDF film 300, the Mylar film and the conductive sheet 220 together by hot pressing to form a sealed space, and the lithium replenishment device is completed. Next, bend the Mylar film around so that it covers the battery cell, and cover the PVDF film 300 on the bottom of the battery cell, then bend the conductive sheet 220, and then assemble the battery shell so that the conductive area on the conductive sheet 220 is in contact with the battery shell. Therefore, the lithium replenisher will be gradually released during the long cycle. Since the lithium replenishment point is located at the bottom of the battery cell, it can reach the inside of the battery cell along the winding or folding gap of the battery cell during the cycle, thereby replenishing the active lithium lost by the battery cell due to the long cycle, playing the role of lithium replenishment. Subsequent tests show that the long cycle performance of the battery using the battery cell lithium replenishment device of this application is better.

[0077] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A lithium supplement device for an electric cell, characterized in that, include: Insulating film (100); A lithium replenishment structure (200), the lithium replenishment structure (200) comprising a lithium replenishment area for replenishing lithium for a battery cell and a conductive area connected to a battery housing, the lithium replenishment area being arranged on the insulating film (100), and the conductive area extending out of the insulating film (100); and a packaging structure, which covers the lithium replenishment area and, together with the insulating film (100), packages the lithium replenishment area; Wherein, the packaging structure is a PVDF film (300).

2. The lithium supplement device for the battery cell according to claim 1, wherein, The lithium supplement structure (200) comprises: A lithium supplement layer (210) is disposed on the insulating film (100); and a conductive sheet (220), covering the lithium replenishing layer (210), with at least one end thereof extending out of the insulating film (100); The lithium replenishment layer (210) located on the insulating film (100) and part of the conductive sheet (220) together form the lithium replenishment area, and the part of the conductive sheet (220) extending out of the insulating film (100) forms the conductive area.

3. The lithium supplement device for the battery cell according to claim 2, characterized in that, The lithium supplement layer (210) has a plurality of layers and is distributed in an array on the insulating film (100).

4. The lithium supplement device for the battery cell according to claim 3, wherein The conductive sheet (220) is provided with a plurality of holes (221); Wherein, each of the holes (221) and each of the lithium replenishing layers (210) are arranged in a staggered manner.

5. The lithium supplementation device for the battery cell according to claim 2, wherein The size of the portion of the conductive sheet (220) located on the insulating film (100) is smaller than the size of the PVDF film (300).

6. The lithium supplement device for the battery cell according to claim 1, wherein, The thickness of the PVDF film (300) is 0.1 mm-0.3 mm.

7. The lithium supplement device for battery cells according to claim 1, wherein, The conductive area can be bent, and a protective adhesive layer (222) is provided at the bent portion.

8. The lithium supplement device for the battery cell according to claim 1, wherein, The lithium replenishment area is arranged on a coating surface of the insulating film (100) corresponding to the bottom surface of the battery cell.

9. The lithium supplement device for the battery cell according to claim 8, wherein, The size of the PVDF film (300) is smaller than the size of the covering surface of the insulating film (100) corresponding to the bottom surface of the battery cell.

10. A lithium battery supplement, comprising: A housing, and a battery cell disposed in the housing; characterized in that it also comprises: a battery cell lithium replenishing device according to any one of claims 1 to 9; The insulating film (100) is coated on the battery core, and the conductive area is connected to the outer shell.

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