A three-dimensional sandwich separator structure for a battery with hierarchical liquid retention ability

Abstract

The present invention discloses a three-dimensional sandwich diaphragm structure of a battery with a hierarchical liquid retention ability, which includes a front surface layer base film (11) and a rear surface layer base film (12) that are spaced apart front and back; in the cavity between the front surface layer base film (11) and the rear surface layer base film (12), a plurality of horizontally distributed liquid storage interlayers (2) are arranged at intervals from top to bottom; the liquid storage interlayers (2) are used to divide the cavity between the front surface layer base film (11) and the rear surface layer base film (12) into a plurality of independent liquid storage channels; each liquid storage interlayer (2) includes a plurality of interlayer monomers (4) connected together in sequence; the interlayer monomer is a groove structure with an upward opening; at the connection between any two adjacent interlayer monomers, an intercommunication hole (3) vertically penetrating up and down is opened. The structure of the present invention is scientifically designed, and the hierarchical storage of the electrolyte at different height levels can be controllably realized, thereby preventing battery safety and electrical performance problems caused by the lack of electrolyte.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a three-dimensional sandwich diaphragm structure of a battery with a hierarchical liquid retention ability. Background Art

[0002] As the main force in the development of current green energy, the electrical performance and safety of batteries are the key concerns of people. And as a main component of the battery, the diaphragm plays a crucial role in the battery.

[0003] Currently, the arrangement method of batteries in a battery pack (PACK) is mainly vertical placement. In this placement method, due to the gravity effect, part of the electrolyte will inevitably accumulate at the bottom of the battery. And when the electrolyte needs to be activated, it often takes a certain amount of time to transfer the electrolyte at the bottom to the upper part. Therefore, a concentration difference will be generated, seriously affecting the rate performance of the battery. At the same time, when the battery electrode group is wound, due to different tensions, the tension at some positions increases, and the amount of electrolyte in the corresponding part will decrease, resulting in lithium deposition or dead zones due to lack of electrolyte during the charge and discharge process, seriously affecting the safety performance of the battery.

[0004] Therefore, in view of the above problems, there is an urgent need to develop corresponding technical solutions currently. Summary of the Invention

[0005] The purpose of the present invention is to provide a three-dimensional sandwich diaphragm structure of a battery with a hierarchical liquid retention ability in view of the technical defects existing in the prior art.

[0006] To this end, the present invention provides a three-dimensional sandwich diaphragm structure of a battery with a hierarchical liquid retention ability, including a front surface layer base film and a rear surface layer base film that are distributed at intervals front and back;

[0007] In the cavity between the front surface layer base film and the rear surface layer base film, a plurality of horizontally distributed liquid storage interlayers are sequentially arranged at intervals from top to bottom;

[0008] The liquid storage interlayer is used to divide the cavity between the front surface layer base film and the rear surface layer base film into a plurality of independent liquid storage channels;

[0009] Each liquid storage interlayer includes a plurality of interlayer monomers connected together in sequence;

[0010] The interlayer monomer is a groove structure with an upward opening;

[0011] At the connection between any two adjacent interlayer monomers, an intercommunication hole vertically penetrating up and down is opened.

[0012] Among them, a plurality of liquid storage interlayers are equally spaced in the cavity between the front surface layer base film and the rear surface layer base film.

[0013] Among them, the interlayer monomer has a V-shaped or concave-shaped structure with an upward opening.

[0014] Among them, the thickness of the front surface layer base film and the rear surface layer base film is 2-50 μm.

[0015] Among them, the specific preparation process of the battery three-dimensional interlayer diaphragm structure is as follows:

[0016] First, on the surface of the rear surface layer base film, multiple liquid storage interlayers are formed by die injection molding method and the preliminary composite of the rear surface layer base film is obtained. Among them, an intercommunication hole 3 is left between two interlayer monomers;

[0017] Subsequently, the front surface layer base film is covered on the front side surface of the liquid storage interlayer, and the thermal temperature is controlled at 50-120 °C to bond the preliminary composite body with the front surface layer base film, and finally the battery three-dimensional interlayer diaphragm structure is formed.

[0018] As can be seen from the technical solutions provided by the present invention above, compared with the prior art, the present invention provides a battery three-dimensional interlayer diaphragm structure with a hierarchical liquid retention ability. Its structural design is scientific, and the electrolyte can be controllably stored at different height levels, thereby preventing battery safety and electrical performance problems caused by the lack of electrolyte, and having great significance in production practice.

[0019] In addition, the battery three-dimensional interlayer diaphragm structure with a hierarchical liquid retention ability provided by the present invention has high flexibility. It can flexibly design the channel size, distribution position and density according to the difference in the coating amount at different positions of the electrode sheet, so as to controllably distribute the electrolyte directionally. None of the current diaphragms have this structure and function. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of a battery three-dimensional interlayer diaphragm structure with a hierarchical liquid retention ability provided by the present invention;

[0021] Figure 2 It is a three-dimensional exploded structural schematic diagram of a battery three-dimensional interlayer diaphragm structure with a hierarchical liquid retention ability provided by the present invention;

[0022] Figure 3 It is a schematic structural diagram of an interlayer monomer with a V-shaped structure in a battery three-dimensional interlayer diaphragm structure with a hierarchical liquid retention ability provided by the present invention;

[0023] Figure 4 It is a schematic diagram of the microscopic morphology of an interlayer monomer with a V-shaped structure in a battery three-dimensional interlayer diaphragm structure with a hierarchical liquid retention ability provided by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] To enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] Referring to Figures 1 to 4 , the present invention provides a three-dimensional sandwich separator structure for a battery with a hierarchical liquid retention ability, which includes a front surface layer base film 11 and a rear surface layer base film 12 that are spaced apart front and back;

[0026] In the cavity between the front surface layer base film 11 and the rear surface layer base film 12, a plurality of horizontally distributed liquid storage interlayers 2 are sequentially arranged at intervals from top to bottom;

[0027] The liquid storage interlayer 2 is used to divide the cavity between the front surface layer base film 11 and the rear surface layer base film 12 into a plurality of independent liquid storage channels (i.e., channels and cavities for storing electrolyte at multiple levels);

[0028] Each liquid storage interlayer 2 includes a plurality of interlayer monomers 4 connected together in sequence;

[0029] The interlayer monomer 4 is a groove structure with an upward opening (sealed at the bottom);

[0030] At the connection between any two adjacent interlayer monomers 4, an intercommunication hole 3 that penetrates vertically up and down is opened.

[0031] In the present invention, specifically, a plurality of liquid storage interlayers 2 are equally spaced in the cavity between the front surface layer base film 11 and the rear surface layer base film 12.

[0032] In the present invention, specifically, the interlayer monomer 4 is preferably a V-shaped or concave-shaped structure with an upward opening, but is not limited to this shape.

[0033] In the present invention, specifically, the liquid storage interlayer 2 is located in the middle of the two base film planes (i.e., the front surface layer base film 11 and the rear surface layer base film 12) and is combined together through a gluing effect.

[0034] In the present invention, specifically, the thickness of the front surface layer base film 11 and the rear surface layer base film 12 is 2-50 μm.

[0035] In the present invention, specifically, the depth and width of the pore channels connecting the intercommunication holes 3 in the liquid storage interlayer 2 can be flexibly designed according to the injection volume, and all size ranges are included within the scope of protection of this patent.

[0036] It should be noted that for the present invention, after the electrolyte is injected, it will be hierarchically retained in the multi-level liquid storage channels in different height directions of the separator structure of the battery cell. And there are certain intercommunication holes between the multiple layers of channels, but it does not affect the long-term storage of the electrolyte in the channels.

[0037] In the present invention, specifically, the materials of the front surface layer base film 11 and the rear surface layer base film 12 can be polyolefin materials, which can be prepared by existing dry or wet methods and can adopt the battery separator base films with mature existing technologies.

[0038] In the present invention, specifically, the liquid storage interlayer 2 located between the front surface layer base film 11 and the rear surface layer base film 12 is a three-dimensional structure made of PVDF (polyvinylidene fluoride) glue (but not limited to PVDF-based substances, and all materials that can meet the requirements for making the designed structure are within the protection scope). The size of the PVDF raw material powder is nanoscale, and the non-crystalline region retention range is 10-40%. Dissolve 20%-67% by weight of nanoscale PVDF powder in NMP (N-methylpyrrolidone) or DMF (dimethylformamide) or the BS-12 emulsion of alkyl betaine. Heat at a temperature above 30°C and stir for 30 minutes to fully dissolve the nanoscale PVDF until the viscosity of the glue solution is 2000-7000 / cp.

[0039] In the present invention, specifically, the specific preparation process of the three-dimensional sandwich diaphragm structure of the battery is as follows: First, according to the setting, on the surface of the polyolefin-based rear surface layer base film 12, a continuous sandwich body (i.e., multiple liquid storage interlayers 2) and the rear surface layer base film 12 are preliminarily compounded by means of die casting (existing). A preliminary composite body is obtained. Among them, there are tiny gaps (intercommunicating holes 3) between the two V-shaped sandwich monomers 4 to ensure that when the electrolyte is injected, the electrolyte can be transferred between the multiple liquid storage channels. Subsequently, the front surface layer base film 11 is covered on the front side surface of the liquid storage interlayer 2, and the heat temperature is controlled at 50-120°C to bond the preliminary composite body with the front surface layer base film 11, and finally, the three-dimensional sandwich diaphragm structure of the battery is formed.

[0040] It should be noted that for the liquid storage interlayer 2, the colloid used is not limited to PVDF glue, and the scope includes any material that can form this shape. The method protection is not limited to the above method and should include any method for preparing this sandwich structure.

[0041] It should be noted that both the front surface layer base film 11 and the rear surface layer base film 12 are planar layers, forming a two-layer planar structure. The intermediate liquid storage interlayer is a three-dimensional V-shaped channel. The base film planar layer and the liquid storage interlayer can be controllably assembled into a three-dimensional interlayer structure. This three-dimensional structure can realize controllable grading of storing the electro-hydraulic in different interlayer channels by regulating the size of the interlayer structure and the interlayer density, matching the demand for electrolyte at different positions of the electrode plate, improving the liquid retention capacity of the separator, accelerating the reaction rate of ions in the electrolyte, and enhancing the rate performance of the battery. At the same time, this structure also avoids the uneven distribution of electrolyte in the electrode group caused by uneven tension, solves the lithium plating phenomenon caused thereby, and improves the safety performance of the battery. In addition, through the multi-level and designable pore channel distribution of the present invention, the effect of controllable grading distribution of the electrolyte can be realized according to the different coating amounts at different positions of the electrode plate. Currently, no separator material has this structure.

[0042] In order to more clearly illustrate the technical solution of the present invention, the following will be described in conjunction with specific embodiments.

[0043] See Figures 1 to 4 As shown, a three-dimensional interlayer separator structure of a battery with a grading liquid retention ability according to the present invention includes a surface layer and an interlayer body (i.e., the front surface layer base film 11, the rear surface layer base film 12, and the liquid storage interlayer). The liquid storage interlayer 2 is in a V shape and can store electro-hydraulic in the tunnel.

[0044] The front surface layer base film 11 and the rear surface layer base film 12 are made of polyolefin and are prepared by dry stretching; the intermediate liquid storage interlayer is a three-dimensional structure of PVDF glue, the particle size of its PVDF raw material powder is nanoscale, and the non-crystalline region retention range is 22%. The nanoscale PVDF is dissolved in NMP or an aqueous solvent, the heating temperature is 50 °C, and the stirring time is 60 min to fully dissolve the nanoscale PVDF until the viscosity of the glue solution reaches 5600 cp. According to the setting, on the height direction surface (i.e., the front side) of the rear surface layer base film 12, through the die injection molding method, a preliminary composite of the multi-level interlayer body and the rear surface layer base film is formed, with a small gap left between every two V shapes to ensure the transfer between multiple layers when injecting electrolyte. Subsequently, the front surface layer base film is covered on the front surface of the interlayer, and the thermal temperature is controlled at 60 °C to bond the preliminary composite body with the front surface layer base film to form the three-dimensional interlayer structure.

[0045] For the present invention, according to the difference in the distribution of the coating amount of the electrode plate, it is designed that the pore channel level is slightly sparse and the electrolyte retention is slightly less on the upper side in the height direction of the battery cell. Similarly, the pore channels are dense on the lower side and can store more electrolyte.

[0046] Compared with the prior art, the three-dimensional interlayer separator structure of a battery with a grading liquid retention ability provided by the present invention has the following beneficial effects:

[0047] 1. The three-dimensional sandwich separator structure of the battery of the present invention can avoid the drawbacks of the concentration gradient distribution of the electrolyte caused by the vertical placement of the battery. Its unique liquid retention structure can enable the lithium ions in the electrolyte to start quickly, improving the electrical performance of the battery.

[0048] 2. The three-dimensional sandwich separator structure of the battery of the present invention can avoid lithium deposition caused by the lack of electrolyte in some areas through the effective infiltration of the electrolyte, greatly reducing the safety risk of the battery.

[0049] 3. The three-dimensional sandwich separator structure of the battery of the present invention can retain the electrolyte in different regions of the battery height in segments. By controllably customizing the position, depth, and density of the hierarchical channels, the matching of the coating amount of the electrode sheet and the amount of electrolyte can be achieved, avoiding the waste of the electrolyte and the safety problems caused by the lack of electrolyte.

[0050] 4. In the three-dimensional sandwich separator structure of the battery of the present invention, the nano-scale PVDF particles used in the sandwich structure can effectively retain the electrolyte. At the same time, this sandwich structure can reduce the risk of diaphragm shrinkage caused by temperature rise to a certain extent, and can also play a buffering role in directly piercing the diaphragm by foreign objects during the process, avoiding the safety problems brought thereby.

[0051] 5. Since the three-dimensional sandwich separator structure of the battery of the present invention retains the electrolyte in the directionally distributed height direction of the separator, compared with other structures, it can accelerate the infiltration of the electrode sheet, reduce the standing time during the production process, and improve the production efficiency.

[0052] 6. The three-dimensional sandwich separator structure of the battery of the present invention has strong designability.

[0053] In summary, compared with the prior art, the three-dimensional sandwich separator structure of the battery with a hierarchical liquid retention ability provided by the present invention has a scientific structure design, can controllably realize the hierarchical storage of the electrolyte at different height levels, thereby preventing the battery safety and electrical performance problems caused by the lack of electrolyte, and has great significance in production practice.

[0054] In addition, the three-dimensional sandwich separator structure of the battery with a hierarchical liquid retention ability provided by the present invention has high flexibility. It can flexibly design the channel size, distribution position, and density according to the difference in the coating amount at different positions of the electrode sheet, so as to controllably and directionally distribute the electrolyte. None of the current separators have this structure and function.

[0055] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A three-dimensional sandwich diaphragm structure of a battery with hierarchical liquid retention ability, characterized in that, it includes a front surface layer base film (11) and a rear surface layer base film (12) that are spaced apart front and rear; in the cavity between the front surface layer base film (11) and the rear surface layer base film (12), a plurality of horizontally distributed liquid storage interlayers (2) are sequentially arranged at intervals from top to bottom; the liquid storage interlayers (2) are used to divide the cavity between the front surface layer base film (11) and the rear surface layer base film (12) into a plurality of independent liquid storage channels; each liquid storage interlayer (2) includes a plurality of interlayer monomers (4) connected together in sequence; the interlayer monomer (4) is a groove structure with an upward opening; at the connection between any two adjacent interlayer monomers (4), an intercommunication hole (3) vertically penetrating up and down is opened; a plurality of liquid storage interlayers (2) are equally spaced in the cavity between the front surface layer base film (11) and the rear surface layer base film (12); the interlayer monomer (4) is a V-shaped or concave-shaped structure with an upward opening.

2. The three-dimensional sandwich diaphragm structure of a battery with hierarchical liquid retention ability according to claim 1, characterized in that, the thickness of the front surface layer base film (11) and the rear surface layer base film (12) is 2 to 50 μm.

3. The three-dimensional sandwich diaphragm structure of a battery with hierarchical liquid retention ability according to any one of claims 1 to 2, characterized in that, the specific preparation process of the three-dimensional sandwich diaphragm structure of the battery is as follows: First, on the surface of the rear surface layer base film (12), a plurality of liquid storage interlayers (2) and the rear surface layer base film (12) are preliminarily compounded by die injection molding to obtain a preliminary composite body, wherein an intercommunication hole (3) is left between two interlayer monomers (4); subsequently, the front surface layer base film (11) is covered on the front side surface of the liquid storage interlayer (2), and the thermal temperature is controlled at 50 to 120 °C to bond the preliminary composite body with the front surface layer base film (11), and finally the three-dimensional sandwich diaphragm structure of the battery is formed.

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