Composite ceramic separator for energy storage lithium battery and lithium battery thereof

Abstract

The utility model discloses a kind of composite ceramic diaphragm for energy storage lithium battery, including first bonding glue layer, first composite microporous base film, alumina particle layer, second composite microporous base film, second bonding glue layer are sequentially laminated.The alumina particle layer is filled between two base films, increase the bonding strength of ceramic powder and base film, effectively avoid the shedding of ceramic powder particle;Porous gap improves battery liquid retention effect;The bonding glue layer of polymer particle enhances the air permeability and high-temperature resistance protection effect of diaphragm.Moreover, base film of different thickness is matched with ceramic layer of different thickness, and other characteristics of diaphragm can also be improved, including air permeability, porosity, puncture strength, mechanical strength and other properties.The energy storage lithium battery obtained by the composite ceramic diaphragm of multilayer structure is greatly improved in cycle and safety performance.

Description

Technical Field

[0001] This utility model belongs to the field of battery separator technology, specifically relating to a composite ceramic separator for energy storage lithium batteries and the lithium battery thereof. Background Technology

[0002] Lithium-ion batteries are mainly composed of positive electrode plates, negative electrode plates, separators, electrolytes, and casings. Among these, the separator is one of the key internal components. The performance of the separator determines the battery's interface structure and internal resistance, directly affecting its capacity, cycle life, and safety performance. A high-performance separator plays a crucial role in improving the overall performance of the battery. The main function of the separator is to separate the positive and negative electrodes, preventing direct contact and short circuits, while allowing the smooth passage of electrolyte ions. The separator material is non-conductive, and its physicochemical properties have a significant impact on battery performance. Different types of batteries use different separators.

[0003] Ceramic separators have been widely used in the lithium battery field due to their excellent performance, especially in high-end products such as power batteries and energy storage batteries, where their high safety and long cycle life have been recognized by the market. Different ceramic separator structures and the composition of their ceramic layers play a crucial role in battery performance. Currently common ceramic separators mainly consist of an inorganic ceramic material layered on one or both sides of a traditional base membrane, used in lithium battery production.

[0004] However, this type of ceramic separator has a problem: the ceramic powder is on the outer surface of the base membrane. During the lithium battery production process, the ceramic particles on the outer surface of the base membrane may fall off due to weak adhesion, electrolyte immersion, or multiple battery cycles. The ceramic particles dissolve in the electrolyte and move around, affecting the movement of lithium ions during battery charging and discharging, which can easily lead to other battery safety and cycle performance issues.

[0005] As a type of high-capacity, low-power battery, energy storage lithium batteries have higher requirements for safety and cycle performance, making it necessary to improve the problem of separator coating peeling. Summary of the Invention

[0006] To address the problems of existing ceramic separators being prone to powder shedding and coating peeling, this invention provides a composite ceramic separator for energy storage lithium batteries and the lithium battery thereof.

[0007] The present invention achieves the aforementioned technical effect through the following technical solution.

[0008] In a first aspect, the present invention provides a composite ceramic separator for energy storage lithium batteries, the composite ceramic separator comprising a first adhesive layer, a first composite microporous base membrane, an alumina particle layer, a second composite microporous base membrane, and a second adhesive layer stacked sequentially.

[0009] Furthermore, the first adhesive layer comprises PVDF polymer particles with an average particle size of 0.1~0.3μm, and the thickness of the first adhesive layer is 0.2~0.8μm. This enhances the thermal stability and air permeability of the membrane.

[0010] Furthermore, the first composite microporous base membrane is a PP / PE / PP three-layer composite microporous membrane, and the thickness of the first composite microporous base membrane is 6~20μm. This can enhance the thermal stability, mechanical strength, and air permeability of the membrane.

[0011] Furthermore, the average particle size of the alumina particles in the alumina particle layer is 0.3~0.5μm, and the thickness of the alumina particle layer is 2.2~4μm. This not only enhances the mechanical strength of the separator, but also, due to the smaller particle size and more uniform and dense alumina particles, effectively blocks lithium dendrite penetration, reduces thermal shrinkage, and improves the battery's resistance to short circuits and thermal runaway.

[0012] Furthermore, the material and thickness of the second composite microporous base membrane are the same as those of the first composite microporous base membrane.

[0013] Furthermore, the material and thickness of the second adhesive layer are the same as those of the first adhesive layer.

[0014] Furthermore, the total thickness of the composite ceramic separator is 16~40μm. The thickness of energy storage lithium battery separators is usually quite thick, depending on the specific application scenario. While ensuring good overall performance such as thermal stability, mechanical strength, air permeability, and no loss of electrolytes, the thickness can be reduced as much as possible.

[0015] Secondly, this utility model provides a lithium battery, which includes a positive electrode, a negative electrode, an electrolyte, and a separator as described in the first aspect.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] To improve the safety and cycle performance of lithium batteries, this invention designs a composite ceramic separator. An alumina particle layer is filled between two base membrane layers, effectively preventing the shedding of ceramic powder particles. Furthermore, because the ceramic powder is deposited and adhered within the base membranes on both sides, the bonding strength between the ceramic powder and the base membrane is increased. The ceramic powder, affected by electrolyte immersion and cycling, is constrained and will not move around due to the influence of current, reducing the occurrence of material shedding due to weak adhesion between ceramic powder particles, thus improving battery cycle performance.

[0018] This invention improves the battery's electrolyte retention by filling the spaces between the composite microporous base membranes with a layer of alumina particles. This increased porosity enhances the battery's electrolyte retention and mitigates the decline in cycle performance caused by electrolyte depletion. Simultaneously, the polymer particle adhesive layer on the outer surface of the composite microporous base membrane not only enhances the membrane's permeability but also provides some protection against membrane shrinkage under high-temperature conditions. Furthermore, combining base membranes of varying thicknesses with ceramic layers of different thicknesses can further improve other membrane properties, including permeability, porosity, puncture strength, and mechanical strength.

[0019] The energy storage lithium battery obtained by the multi-layer composite ceramic separator of this invention may have an increase in internal resistance, but under low-rate (0.1~0.5c) discharge conditions, it has little impact on the battery discharge capacity and the battery discharge efficiency will not decrease, but the cycle performance and safety performance of the battery are greatly improved. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only schematic diagrams of some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the composite ceramic separator used in energy storage lithium batteries according to this utility model.

[0022] In the figure: 1-first adhesive layer, 2-first composite microporous base membrane, 3-alumina particle layer, 4-second composite microporous base membrane, 5-second adhesive layer. Detailed Implementation

[0023] To make the technical problems, technical solutions, and beneficial effects solved by this utility model clearer, the various embodiments of this utility model are described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments described herein are only some, not all, of the embodiments of this utility model, and are merely used to explain this utility model and are not intended to limit it. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model. The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined and referenced with each other without contradiction.

[0024] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein.

[0025] In the description of this application, it should be understood that the terms "thickness", "width", "height", "upper", "lower", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0026] In the description of this application, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or the first and second features being in contact through another feature between them.

[0027] In a first aspect, the present invention provides a composite ceramic separator for energy storage lithium batteries, the composite ceramic separator comprising a first adhesive layer 1, a first composite microporous base membrane 2, an alumina particle layer 3, a second composite microporous base membrane 4, and a second adhesive layer 5 stacked sequentially.

[0028] In one specific implementation, the first adhesive layer 1 comprises PVDF polymer particles with an average particle size of 0.1~0.3μm, and specifically, the thickness of the first adhesive layer 1 is 0.2~0.8μm. The adhesive layer achieves bonding between the electrode and the separator after hot pressing. If the polymer particle size is too small, it may clog pores over a large area, affecting the separator's permeability; if the particle size is too large, it may cause adhesive detachment. When the average particle size of the polymer particles is 0.1~0.3μm, it not only enhances the separator's thermal shrinkage performance and permeability but also prevents adhesive detachment, while simultaneously improving the wettability of the electrolyte on the separator.

[0029] In one specific implementation scheme, the first composite microporous base membrane 2 is a PP / PE / PP three-layer composite microporous membrane with a thickness of 6~20μm. The composite microporous base membrane is composed of three layers of polypropylene (PP), polyethylene (PE), and polypropylene (PP). This composite structure combines the advantages of PP / PE materials, enhancing the thermal stability and mechanical strength of the separator. The micropores on the base membrane enhance air permeability, further improving the safety and reliability of the battery.

[0030] In one specific implementation, the average particle size of the alumina particles in the alumina particle layer 3 is 0.3~0.5μm, and the thickness of the alumina particle layer 3 is 2.2~4μm. Smaller particle sizes of alumina, due to their more uniform and denser structure, effectively block lithium dendrite penetration, reduce thermal shrinkage, and improve the battery's resistance to short circuits and thermal runaway. However, when the particle size is less than 0.3μm, the van der Waals forces between particles are significantly enhanced, easily leading to agglomeration into "pseudo-large particles," which in turn damages the uniformity of the alumina particle layer. When the average particle size of the alumina is 0.3~0.5μm, the overall performance is better. The thickness of the alumina particle layer should also not be too thick; a thickness of 2.2~4μm provides the best overall performance.

[0031] As a specific implementation scheme, the material and thickness of the second composite microporous base membrane 4 are the same as those of the first composite microporous base membrane 2.

[0032] In one specific implementation, the material and thickness of the second adhesive layer 5 are the same as those of the first adhesive layer 1.

[0033] As one specific implementation, the total thickness of the composite ceramic separator is 16~40μm. The thickness of lithium-ion battery separators for energy storage is typically quite thick, with the actual thickness depending on the specific application scenario. The thickness can be reduced as much as possible while ensuring good overall performance in terms of thermal stability, mechanical strength, air permeability, and non-saline content.

[0034] Secondly, this utility model provides a lithium battery, which includes a positive electrode, a negative electrode, an electrolyte, and a separator as described in the first aspect.

[0035] Example 1

[0036] like Figure 1 As shown, a composite ceramic separator for energy storage lithium batteries includes a first adhesive layer 1, a first composite microporous base membrane 2, an alumina particle layer 3, a second composite microporous base membrane 4, and a second adhesive layer 5, stacked sequentially. The first adhesive layer 1 comprises PVDF polymer particles with an average particle size of 0.2 μm and a thickness of 0.5 μm. The first composite microporous base membrane 2 is a PP / PE / PP three-layer composite microporous membrane with a thickness of 10 μm. The alumina particle layer 3 contains alumina particles with an average particle size of 0.4 μm and a thickness of 3 μm. The second composite microporous base membrane 4 has the same material and thickness as the first composite microporous base membrane 2. The second adhesive layer 5 has the same material and thickness as the first adhesive layer 1. The total thickness of the composite ceramic separator is 24 μm.

[0037] In industrial production, the process of coating a base film with a single-sided or double-sided ceramic coating (alumina particle layer) is very mature, and the coating equipment is also well-developed. By improving existing coating equipment, adding a diaphragm unwinding device and a drive roller, the coating process of a double-layer composite microporous base film with an alumina particle layer can be achieved. Applying an adhesive layer to the outer side of the double-layer composite microporous base film can also be done using existing equipment. The composite ceramic diaphragm is then bonded and laminated according to the structure designed in this invention, and after baking, it is wound up to obtain a multi-layer composite ceramic diaphragm.

[0038] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the substance and scope of the present invention. Various modifications made by those skilled in the art to the above embodiments after reading this specification are all within the scope of protection of the present invention.

Claims

1. A composite ceramic separator for energy storage lithium batteries, characterized in that, The composite ceramic diaphragm comprises a first adhesive layer (1), a first composite microporous base membrane (2), an alumina particle layer (3), a second composite microporous base membrane (4), and a second adhesive layer (5) stacked sequentially.

2. The composite ceramic separator for energy storage lithium batteries according to claim 1, characterized in that, The first adhesive layer (1) comprises PVDF polymer particles with an average particle size of 0.1~0.3μm and a thickness of 0.2~0.8μm.

3. The composite ceramic separator for energy storage lithium batteries according to claim 1, characterized in that, The first composite microporous base membrane (2) is a PP / PE / PP three-layer composite microporous membrane, and the thickness of the first composite microporous base membrane (2) is 6~20μm.

4. The composite ceramic separator for energy storage lithium batteries according to claim 1, characterized in that, The alumina particles in the alumina particle layer (3) have an average particle size of 0.3~0.5μm and a thickness of 2.2~4μm.

5. The composite ceramic separator for energy storage lithium batteries according to claim 1, characterized in that, The material and thickness of the second composite microporous base membrane (4) are the same as those of the first composite microporous base membrane (2).

6. The composite ceramic separator for energy storage lithium batteries according to claim 1, characterized in that, The material and thickness of the second adhesive layer (5) are the same as those of the first adhesive layer (1).

7. The composite ceramic separator for energy storage lithium batteries according to claim 1, characterized in that, The total thickness of the composite ceramic diaphragm is 16~40μm.

8. A lithium battery, characterized in that, The lithium battery includes a positive electrode, a negative electrode, an electrolyte, and a separator as described in any one of claims 1 to 7.

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