Separator and battery comprising the same

Abstract

The utility model relates to the technical field of diaphragm, concretely provides a diaphragm and the battery including the diaphragm, the diaphragm of the utility model includes: the base film layer, the lithium supplement layer and the adhesive layer that are sequentially stacked from bottom to top, still be provided with the rubber coating layer on the upper surface of base film layer, the rubber coating layer is located respectively lithium supplement layer and the left and right sides of adhesive layer, and the thickness of rubber coating layer is greater than or equal to the overall thickness of lithium supplement layer and adhesive layer. Diaphragm passes through the lithium supplement layer of intermediate area, releases lithium ion in the circulation process, when lithium supplement agent circulates and consumes, forms ion channel, and this channel can significantly improve the ion transmission power of electrode intermediate area, makes the lithium ion of this area advance rate of promotion, and the adhesive layer forms the protective structure with lithium supplement layer through intermolecular force, reduces the lithium supplement agent drop rate. When the thickness of rubber coating layer is greater than the overall thickness of lithium supplement layer and adhesive layer, the potential distribution of balanced edge area is reduced, and the irreversible lithium precipitation amount of pole piece edge is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of diaphragm, concretely provides a diaphragm and the battery including the diaphragm. BACKGROUND

[0002] With the wide application of lithium ion battery in electric vehicles, energy storage system and other fields, the main factors of cycle attenuation and capacity attenuation of lithium ion battery at present are active lithium loss in the cycle process and irreversible lithium precipitation at the edge of the pole piece.

[0003] Irreversible lithium precipitation at the edge of the pole piece is mainly due to the non-uniform potential at the edge of the pole piece, which leads to faster deintercalation of lithium ions at the edge of the pole piece, and further causes abnormal deposition of lithium ions and growth of lithium dendrites, forming irreversible lithium precipitation at the edge of the pole piece.

[0004] In order to improve the active lithium loss in the cycle process, researchers add lithium compounds such as lithium nickelate, lithium ferrite or lithium oxalate to the positive electrode, add metal lithium to the negative electrode, and coat lithium supplement additives on the diaphragm as a lithium source to supplement the loss of active lithium in the cycle process. However, on the one hand, the lithium supplement agent is easy to fall off after the coating reaction on the diaphragm, which leads to poor lithium supplement effect and cannot supplement the loss of active lithium caused by irreversible lithium precipitation at the head and tail of the pole piece. On the other hand, it cannot effectively inhibit the irreversible lithium precipitation at the head and tail of the pole piece, resulting in continuous loss of active lithium.

[0005] Correspondingly, there is a need in the art for a new diaphragm to solve the problem that the lithium supplement agent is easy to fall off after coating on the existing diaphragm, resulting in poor lithium supplement effect and unable to effectively improve the loss of active lithium caused by irreversible lithium precipitation at the head and tail of the pole piece. UTILITY MODEL CONTENTS

[0006] The utility model aims at solving the above technical problem, i.e. solving the problem that the lithium supplement agent is easy to fall off after coating on the existing diaphragm, resulting in poor lithium supplement effect and unable to effectively improve the loss of active lithium caused by irreversible lithium precipitation at the head and tail of the pole piece.

[0007] In a first aspect, the utility model provides a diaphragm, which comprises:

[0008] The base film layer, the lithium supplement layer and the adhesive layer are sequentially stacked from bottom to top; the upper surface of the base film layer is further provided with a glue coating layer, the glue coating layer is located on the left and right sides of the lithium supplement layer and the adhesive layer respectively, and the thickness of the glue coating layer is greater than or equal to the overall thickness of the lithium supplement layer and the adhesive layer.

[0009] In the optional technical solution of the above diaphragm, a gap is formed between the edge of the glue coating layer and the edge of the base film layer on at least one side of the left and right sides, and the base film layer protrudes from the side edge of the glue coating layer.

[0010] In the above-mentioned optional technical solutions for the diaphragm, gaps are formed between the edges of the adhesive layer on both the left and right sides and the edges of the base film layer.

[0011] In the above-mentioned optional technical solutions for the separator, the coating thickness L3 of the lithium replenishment layer is in the range of 3μm to 6μm.

[0012] In the above-mentioned optional technical solutions for the diaphragm, the difference between the coating thickness L2 of the adhesive layer, the coating thickness L3 of the lithium replenishment layer, and the coating thickness L4 of the bonding layer does not exceed 2 μm.

[0013] In the above-mentioned optional technical solutions for the diaphragm, the difference between the coating thickness L2 of the adhesive layer, the coating thickness L3 of the lithium replenishment layer, and the coating thickness L4 of the bonding layer is in the range of 1 μm to 2 μm.

[0014] In the above-mentioned optional technical solutions for the diaphragm, the coating thickness L2 of the adhesive layer is in the range of 7μm to 9μm.

[0015] In the above-mentioned optional technical solutions for the diaphragm, the coating thickness L2 of the adhesive layer is in the range of 7 μm to 9 μm; and / or, the coating thickness L4 of the bonding layer is in the range of 1 μm to 2 μm.

[0016] In the above-mentioned optional technical solutions for the diaphragm, the gap width W2 formed between the edge of the adhesive layer and the edge of the base film layer is in the range of 1 mm to 2 mm; and / or, the coating width W3 of the adhesive layer is in the range of 10 mm to 15 mm.

[0017] In the above-mentioned optional technical solutions for the diaphragm, the adhesive layer is an oil-based adhesive layer; and / or, the coating layer is a ceramic coating.

[0018] In a second aspect, the present invention also provides a battery, the battery comprising the separator described in any one of the above technical solutions.

[0019] Those skilled in the art will understand that the diaphragm of this invention comprises: a base film layer, a lithium replenishment layer, and an adhesive layer stacked sequentially from bottom to top;

[0020] An adhesive layer is also provided on the upper surface of the base film layer. The adhesive layer is located on the left and right sides of the lithium replenishment layer and the adhesive layer, respectively. The thickness of the adhesive layer is greater than or equal to the overall thickness of the lithium replenishment layer and the adhesive layer.

[0021] With the above technical solution, the separator releases lithium ions during cycling through the lithium replenishment layer in the middle region. As the lithium replenishment agent is gradually consumed during cycling, ion diffusion channels are formed. This channel structure can significantly improve the ion transport dynamics in the middle region of the electrode, increasing the lithium ion forward migration rate in this region and effectively alleviating the local polarization problem. On the other hand, the adhesive layer on the outer layer of the lithium replenishment layer forms a protective structure with the lithium replenishment layer through intermolecular forces, reducing the lithium replenishment agent shedding rate and thus avoiding the negative impact of lithium replenishment compound shedding on the cell's cycling performance. In addition, when the thickness of the adhesive layer on the outer ring of the separator is greater than the overall thickness of the lithium replenishment layer and the adhesive layer, a mechanical pressure compensation region is formed at the beginning and end of the electrode through the thickness difference design. This region forms a tight adhesive interface with the edge of the electrode, which can not only balance the potential distribution in the edge region, but also suppress abnormal lithium ion deposition at the edge through physical constraint, reducing the amount of irreversible lithium plating at the electrode edge. Combined with the continuous lithium source replenishment of the middle lithium replenishment layer, the cell cycling can be effectively improved, solving the dual problems of poor lithium replenishment effect and irreversible lithium plating at the beginning and end of the electrode in the existing technology. Attached Figure Description

[0022] The preferred embodiments of this utility model are described below with reference to the accompanying drawings, in which:

[0023] Figure 1 This is a cross-sectional schematic diagram of the diaphragm of this utility model;

[0024] Figure 2 This is a top view of the diaphragm of this utility model.

[0025] List of reference numerals in the attached diagram:

[0026] 1. Base film layer; 2. Lithium replenishment layer; 3. Adhesive layer; 4. Coating layer. Detailed Implementation

[0027] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0028] It should be noted that in the description of this utility model, the terms "upper," "lower," "left," "right," etc., indicating directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. This is merely for ease of description and does not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this utility model. In this utility model, the upper and lower directions are based on the base film layer being placed below and parallel to the ground. "Up" refers to the side closer to the upper surface in the direction from the lower surface to the upper surface of the base film layer, and "lower" refers to the side closer to the lower surface. "Left" and "right" refer to the sides closer to the left and right sides of the base film layer, respectively. The "upper" and "lower" directions are defined as the thickness direction of the diaphragm, and "left" and "right" are defined as the width direction of the diaphragm.

[0029] Reference Figure 1 To address the problem that lithium replenishment agents on existing separators are prone to detachment, resulting in poor lithium replenishment effects, and that the loss of active lithium caused by irreversible lithium deposition at the electrode ends cannot be effectively improved, this invention provides a separator.

[0030] The separator comprises a base film layer 1, a lithium replenishment layer 2, and an adhesive layer 3, stacked sequentially from bottom to top. A coating layer 4 is also disposed on the upper surface of the base film layer 1, with the coating layer 4 positioned on the left and right sides of both the lithium replenishment layer 2 and the adhesive layer 3. The thickness of the coating layer 4 is greater than the overall thickness of the lithium replenishment layer 2 and the adhesive layer 3. In other words, the lithium replenishment layer 2 and the adhesive layer 3 are sequentially arranged in the middle of the upper surface of the base film layer 1; the lithium replenishment layer 2 is closer to the upper surface of the base film layer 1, while the adhesive layer 3 is located on the side of the lithium replenishment layer 2 furthest from the base film layer 1; the two coating layers 4 are respectively positioned on the left and right sides of the lithium replenishment layer 2 and the adhesive layer 3.

[0031] On the one hand, the separator releases lithium ions during cycling through the lithium replenishment layer 2 in the middle region. As the lithium replenishment agent is gradually consumed during cycling, ion diffusion channels are formed. This channel structure can significantly improve the ion transport dynamics in the middle region of the electrode, increasing the lithium ion forward migration rate in this region and effectively alleviating the local polarization problem. On the other hand, the adhesive layer 3 on the outer layer of the lithium replenishment layer 2 forms a protective structure with the lithium replenishment layer 2 through intermolecular forces, reducing the lithium replenishment agent shedding rate and thus avoiding the negative impact of lithium replenishment compound shedding on the cell's cycling performance. In addition, the thickness of the adhesive layer 4 on the outer ring of the separator is greater than the overall thickness of the lithium replenishment layer 2 and the adhesive layer 3. This thickness difference design forms a mechanical pressure compensation region at the beginning and end of the electrode. This region forms a tight adhesive interface with the edge of the electrode, which not only balances the potential distribution in the edge region but also inhibits abnormal lithium ion deposition at the edge through physical constraints, reducing the amount of irreversible lithium plating at the electrode edge. Combined with the continuous lithium source replenishment of the middle lithium replenishment layer, this can effectively improve the cell's cycling performance and solve the dual problems of poor lithium replenishment effect and irreversible lithium plating at the beginning and end of the electrode in the existing technology.

[0032] In one possible implementation, a gap of a predetermined width is formed between the edges of the adhesive layer 4 on both the left and right sides and the edges of the base film layer 1. That is, the base film layer 1 is wider than the overall width of the lithium replenishment layer 2, the adhesive layer 3, and the adhesive layer 4, and the base film layer 1 protrudes beyond the side edge of the adhesive layer 4. This gap is the distance by which the base film layer 1 protrudes beyond the side edge of the adhesive layer 4. The purpose of setting this gap is to control the width difference between the electrode and the separator in the width direction. By limiting the coating boundary of the adhesive layer 4, it is possible to effectively avoid the slurry overflow and loss caused by the adhesive layer being applied too wide during the coating process, and at the same time, to prevent the problem of excessive coating thickness in the edge area. When the coating range of the adhesive layer 4 exceeds the edge of the base film layer 1, excess slurry will accumulate at the edge to form an excessively thick coating, which not only wastes materials, but may also lead to a decrease in the bonding accuracy between the electrode and the separator due to abnormal edge thickness during subsequent electrode assembly, and may even cause local electric field concentration to aggravate edge lithium deposition. By reserving a gap, the boundary of the adhesive layer 4 can be strictly limited within the effective area of ​​the base film layer 1, so that the edge of the separator and the electrode form the best width difference. This ensures the alignment accuracy during electrode assembly and optimizes the potential distribution at the edge of the electrode through the thickness difference design of the adhesive layer 4, thereby achieving the dual technical effects of accurate lithium replenishment coating and edge lithium plating suppression.

[0033] As one possible implementation, the coating thickness L2 of the adhesive layer 4 is in the range of 7 μm to 9 μm. Controlling the thickness of the adhesive layer 4 within this range ensures that the thickness on the left and right sides of the separator is thicker than that at the center. During hot pressing, due to the uneven pressure distribution on both sides, the adhesion on the sides of the separator is stronger than in the middle, which helps to balance the potential distribution on both sides and improve lithium plating. For example, L2 can be any value among 7 μm, 7.5 μm, 8 μm, 8.5 μm, and 9 μm.

[0034] To avoid a coating layer thickness L2 less than 7μm, which would result in a thicker middle layer compared to the sides, causing concentrated pressure at the middle interface during hot pressing and stronger adhesion, thus exacerbating the potential unevenness caused by insufficient adhesion on both sides and failing to effectively improve lithium plating on both sides. Conversely, to avoid a coating layer thickness L2 greater than 9μm, which would lead to excessive thickness on both sides, causing a decrease in adhesion strength in the middle region due to excessive gaps during hot pressing, resulting in voids at the interface between the electrode and the separator, ineffective adhesion, concentrated electric field in the middle region, and increased lithium plating in the middle.

[0035] As one possible implementation, the coating thickness L3 of the lithium replenishment layer 2 is in the range of 3 μm to 6 μm. Controlling the coating thickness of the lithium replenishment layer 2 within the range of 3 μm to 6 μm can effectively increase the amount of active lithium replenished during cycling and extend the cycle life. For example, L3 can be any value among 3 μm, 4 μm, 4.6 μm, 5 μm, 5.5 μm, and 6 μm.

[0036] To avoid situations where L3 is less than 3μm, the insufficient thickness of the lithium replenishment layer 2 would result in a low lithium replenishment amount, thus failing to effectively improve cycle life. Conversely, to avoid situations where L3 is greater than 6μm, the excessive thickness of the lithium replenishment layer 2 would prevent rapid lithium ion insertion / extraction, hindering the rapid insertion / extraction of internal active lithium and affecting the lithium replenishment life.

[0037] As one possible implementation, the coating thickness L4 of the adhesive layer 3 is in the range of 1 μm to 2 μm. Controlling the coating thickness L4 of the adhesive layer 3 within the range of 1 μm to 2 μm allows for rapid migration of lithium ions in the lithium replenishment layer 2 without affecting the lithium replenishment utilization rate, and also effectively improves cycle life. For example, L4 can be any value among 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, and 2 μm.

[0038] To avoid L4 being less than 1 μm, as an excessively thin adhesive layer 3 would result in poor adhesion, leading to the detachment of the lithium replenishment layer 2 and affecting cycle performance. Conversely, to avoid L4 being greater than 2 μm, as an excessively thick adhesive layer 3 would affect the thickness in the middle, making it significantly thicker than the sides, thus failing to effectively improve lithium plating on both sides. Furthermore, an excessively thick adhesive layer 3 would increase the lithium-ion migration path, reducing the lithium intercalation rate and failing to effectively improve cycle life.

[0039] As one possible implementation, the difference between L2, L3, and L4 is in the range of 1 μm to 2 μm. By controlling the thickness difference between the separator edge and the middle within the range of 1 μm to 2 μm, the separator forms an ideal thickness gradient distribution during hot pressing. The increased mechanical pressure generated by the increased thickness in the edge region significantly enhances the adhesion strength with the electrode, effectively suppressing edge lithium plating; simultaneously, the moderate thickness in the middle region ensures a tight fit between the separator and the electrode, avoiding lithium plating problems caused by poor contact in the middle region. For example, the difference between L2, L3, and L4 can be any value among 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, and 2 μm.

[0040] To avoid situations where L2-L3-L4 is less than 1μm, resulting in poor adhesion at the edges due to insufficient thickness difference in the edge region, thus failing to effectively improve lithium plating on both sides, it is also necessary to avoid situations where L2-L3-L4 is greater than 2μm, resulting in a relatively thin thickness in the middle region, leading to gaps between the separator and the electrode, which exacerbates lithium plating in the middle.

[0041] As one possible implementation method, refer to Figure 2 The gap width W2 between the edge of the adhesive layer 4 and the edge of the base film layer 1 is in the range of 1mm to 2mm. Controlling the gap width W2 between the edge of the adhesive layer 4 and the edge of the base film layer 1 within this range effectively prevents the slurry from overflowing to the outside of the base film layer 1 during the coating process by limiting the coating boundary of the adhesive layer 4, thus preventing excessive coating thickness due to slurry accumulation at the edges. It also precisely matches the width difference between the separator and the electrode, ensuring ideal coverage between the separator edge and the electrode, and guaranteeing the adhesion strength in the edge area. For example, W2 can be any value among 1mm, 1.2mm, 1.5mm, 1.8mm, and 2mm.

[0042] This design avoids situations where W2 is less than 1mm, causing the coating boundary of the adhesive layer 4 to lose its buffer space, resulting in slurry overflowing to both sides of the base film during coating. This leads to inaccurate control of the edge thickness, wasting slurry and causing localized stress concentration during electrode assembly due to excessive edge thickness. Conversely, a design where W2 is greater than 2mm results in an excessive width difference between the separator edge and the electrode, leading to poor adhesion of the separator at the electrode edge, affecting the adhesion of the outermost edge, causing edge lithium plating, and worsening cycle life.

[0043] As one possible implementation, the coating width W3 of the adhesive layer 4 is in the range of 10mm to 15mm. Controlling the coating width W3 of the adhesive layer 4 to 10mm to 15mm effectively covers the thinned area on the edge side of the electrode, increasing the adhesion area between the edge side and the separator, significantly improving adhesion, effectively balancing the edge potential distribution, and suppressing lithium plating. For example, W3 can be any value among 10mm, 10.5mm, 11mm, 11.5mm, 12mm, 12.5mm, 13mm, 13.5mm, 14mm, 14.5mm, and 15mm.

[0044] This design avoids situations where W3 is less than 10mm, resulting in insufficient coverage of the thinned areas at the electrode edges by the adhesive layer 4, poor adhesion in the uncovered areas on both sides, and increased lithium deposition. It also avoids situations where W3 is greater than 15mm, resulting in a reduction in the effective coating area in the center of the lithium replenishment layer 2, which in turn reduces the overall lithium replenishment and lowers cycle life.

[0045] L1 is the thickness of the base film 1, and W1 is the width of the base film 1. Therefore, the coating widths of the lithium replenishment layer 2 and the adhesive layer 3 are equal, and the coating width W4 = W1 - 2 * W2 - 2 * W3.

[0046] In one possible implementation, the lithium replenishment layer 2 comprises a lithium replenishment compound, a polymer substrate, and a small amount of adhesive. The lithium replenishment compound accounts for 70 wt% (weight percentage) of the lithium replenishment layer. The lithium replenishment compound may be at least one of lithium oxide, lithium hydride, lithium alloy, lithium nitride, and lithium organometallic compound. The polymer substrate may be at least one of polyvinylidene fluoride, polyethylene oxide, polypropylene, polyethylene, and vinylidene fluoride-hexafluoropropylene copolymer.

[0047] As one possible implementation, adhesive layer 3 is an oil-based adhesive layer. An oil-based adhesive layer refers to an adhesive layer prepared using an organic solvent as a dispersion medium or solvent system in the prior art, and is a concept relative to "water-based adhesive layers" (using water as a dispersion medium).

[0048] The adhesive layer 3 specifically comprises 70-85 wt% organic solvent and 15-30 wt% adhesive. The organic solvent is at least one of NMP (N-methylpyrrolidone), acetone, and DEC (diethyl carbonate), and the adhesive is at least one of polyvinylidene fluoride, polyethylene, and polypropylene.

[0049] In one possible implementation, the adhesive layer 4 is a ceramic coating. The ceramic coating comprises ceramic particles and an adhesive. The ceramic particles include at least one of alumina, boehmite, calcium oxide, magnesium oxide, iron oxide, silicon nitride, silicon carbide, or titanium dioxide. The adhesive includes at least one of PVDF (polyvinylidene fluoride), PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene), PEO (polyethylene oxide), PAN (polyacrylonitrile), PMMA (polymethyl methacrylate), PVB (polyvinyl butyral), PDA (polydopamine), and polystyrene-acrylate.

[0050] It should also be noted that although this application describes the specific components of the lithium replenishment layer 2, the adhesive layer 4, and the bonding layer 3, it is not intended to limit their specific chemical composition and ratio. Those skilled in the art can reasonably adjust and optimize the types of materials, additives, and ratio parameters of each layer based on the battery system requirements, production process conditions, and performance optimization goals, and all of these adjustments fall within the protection scope of this utility model.

[0051] As described in the first paragraph of this section, the above embodiments are merely used to illustrate the principle of this utility model and are not intended to limit the scope of protection of this utility model. Without departing from the principle of this utility model, those skilled in the art can adjust the above structure so that this utility model can be applied to more specific application scenarios.

[0052] For example, in one possible implementation, a gap is formed between the edge of the adhesive layer 4 and the edge of the base film layer 1 on only one side of the left and right sides. That is, a gap can be formed between the edge of the adhesive layer 4 on the left side and the edge of the base film layer 1; or, a gap can be formed between the edge of the adhesive layer 4 on the right side and the edge of the base film layer 1. Furthermore, when gaps are formed on both sides simultaneously, the widths of the gaps on both sides can be equal or unequal. These can be set according to actual needs, and none of them deviate from the principle of this utility model. Therefore, they all fall within the protection scope of this utility model.

[0053] For example, in an alternative embodiment, the thickness of the adhesive layer 4 is equal to the overall thickness of the lithium replenishment layer 2 and the adhesive layer 3. These do not deviate from the principle of this utility model and therefore fall within the protection scope of this utility model.

[0054] For example, in an alternative embodiment, the coating thickness L3 of the lithium replenishment layer 2 is less than 3 μm or greater than 6 μm. These do not deviate from the principle of this utility model and therefore fall within the protection scope of this utility model.

[0055] For example, in an alternative embodiment, the coating thickness L2 of the adhesive layer 4 is less than 7 μm or greater than 9 μm. These do not deviate from the principle of this utility model and therefore fall within the protection scope of this utility model.

[0056] For example, in an alternative embodiment, the coating thickness L4 of the adhesive layer 3 is less than 1 μm or greater than 2 μm. These do not deviate from the principle of this utility model and therefore fall within the protection scope of this utility model.

[0057] For example, in an alternative embodiment, the difference between the coating thickness L2 of the adhesive layer 4, the coating thickness L3 of the lithium replenishment layer 2, and the coating thickness L4 of the adhesive layer 3 is less than 1 μm or greater than 2 μm. These differences do not deviate from the principle of this utility model and therefore fall within the protection scope of this utility model.

[0058] For example, in an alternative embodiment, the gap width W2 formed between the edge of the adhesive layer 4 and the edge of the base film layer 1 is less than 1 mm or greater than 2 mm. These do not deviate from the principle of this utility model and therefore fall within the protection scope of this utility model.

[0059] For example, in an alternative embodiment, the coating width W3 of the adhesive layer 4 is less than 10 mm or greater than 15 mm. These do not deviate from the principle of this utility model and therefore fall within the protection scope of this utility model.

[0060] This invention also provides a battery that employs the separator described in any of the above embodiments. This separator is not only suitable for traditional lithium-ion batteries, but also widely adaptable to other emerging batteries such as sodium-ion batteries, as well as other electrochemical energy storage devices that rely on separators for ion conduction and electrode isolation. Those skilled in the art can define the application targets of the separator according to their needs.

[0061] The technical solution of this utility model has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the protection scope of this utility model is obviously not limited to these specific embodiments. Without departing from the principle of this utility model, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of this utility model.

Claims

1. A diaphragm, characterized in that, The diaphragm includes: The base film layer (1), the lithium replenishment layer (2), and the adhesive layer (3) are stacked sequentially from bottom to top; An adhesive layer (4) is also provided on the upper surface of the base film layer (1). The adhesive layer (4) is located on the left and right sides of the lithium replenishment layer (2) and the adhesive layer (3), respectively. The thickness of the adhesive layer (4) is greater than or equal to the overall thickness of the lithium replenishment layer (2) and the adhesive layer (3).

2. The diaphragm according to claim 1, characterized in that, At least one of the left and right sides, a gap is formed between the edge of the adhesive layer (4) and the edge of the base film layer (1), and the base film layer (1) protrudes from the side edge of the adhesive layer (4).

3. The diaphragm according to claim 2, characterized in that, Gaps are formed between the edges of the adhesive layer (4) on both the left and right sides and the edges of the base film layer (1).

4. The diaphragm according to claim 1, characterized in that, The coating thickness L3 of the lithium replenishment layer (2) is in the range of 3 μm to 6 μm.

5. The diaphragm according to claim 1, characterized in that, The difference between the coating thickness L2 of the adhesive layer (4), the coating thickness L3 of the lithium replenishment layer (2), and the coating thickness L4 of the adhesive layer (3) shall not exceed 2 μm.

6. The diaphragm according to claim 5, characterized in that, The difference between the coating thickness L2 of the adhesive layer (4), the coating thickness L3 of the lithium replenishment layer (2), and the coating thickness L4 of the adhesive layer (3) is in the range of 1 μm to 2 μm.

7. The diaphragm according to claim 1, characterized in that, The coating thickness L2 of the adhesive layer (4) is in the range of 7 μm to 9 μm; and / or, the coating thickness L4 of the adhesive layer (3) is in the range of 1 μm to 2 μm.

8. The diaphragm according to claim 1, characterized in that, The gap width W2 formed between the edge of the adhesive layer (4) and the edge of the base film layer (1) is in the range of 1 mm to 2 mm; and / or, the coating width W3 of the adhesive layer (4) is in the range of 10 mm to 15 mm.

9. The diaphragm according to claim 1, characterized in that, The adhesive layer (3) is an oil-based adhesive layer; and / or the coating layer (4) is a ceramic coating.

10. A battery, characterized in that, The battery comprises the separator according to any one of claims 1-9.

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