Lithium Metal Solid-State Battery Carbon Fiber Multi-Grid Box and Its Forming Method and Application

Abstract

The present invention discloses a carbon fiber multi-grid box body for a lithium metal solid-state battery, a forming method thereof, and an application. The forming method of the carbon fiber multi-grid box body for a multi-module lithium metal solid-state battery includes: (1) laying a first prepreg on the surface of the cavity of a female mold; (2) providing a split mold, laying a second prepreg on five surfaces of the split mold, then pressing it tightly into the cavity with the first prepreg laid, and making the surface of the split mold without the second prepreg laid face away from the bottom of the cavity, and pasting a buffer layer on the side surface of the split mold that does not directly contact the female mold; (3) repeating step (2) more than once to form a multi-grid structure; (4) curing the first prepreg, the second prepreg, and the buffer layer to form a multi-grid box body with multiple grid units. The technological process of the present invention is simple, and the obtained multi-grid box body has high structural strength and stiffness, and can effectively bear the pressure generated during the expansion and deformation of the lithium metal solid-state battery.

Description

Technical Field

[0001] The present invention particularly relates to a carbon fiber multi-grid box body for a lithium metal solid-state battery, a forming method thereof, and an application thereof, belonging to the technical field of battery boxes. Background Art

[0002] During the charging and discharging process of a lithium metal solid-state battery, its volume will have a relatively significant expansion and contraction phenomenon, and the expansion and contraction phenomenon of a module formed by stacking multiple lithium metal batteries is even more obvious. Therefore, in a solid-state battery box containing multiple modules, a layer with a buffer material needs to be used between each module to give sufficient deformation allowance to the lithium metal solid-state battery. The carbon fiber battery box has high structural strength and stiffness, and can effectively bear the pressure generated during the expansion and deformation of the lithium metal solid-state battery. Summary of the Invention

[0003] The main object of the present invention is to provide a carbon fiber multi-grid box body for a lithium metal solid-state battery, a forming method thereof, and an application thereof, so as to overcome the deficiencies in the prior art.

[0004] To achieve the foregoing invention object, the technical solutions adopted by the present invention include:

[0005] A first aspect of an embodiment of the present invention provides a forming method for a carbon fiber multi-grid box body of a multi-module lithium metal solid-state battery, which includes:

[0006] (1) Laying a first prepreg on the surface of the cavity of a female mold, wherein the cavity of the female mold is a cuboid structure;

[0007] (2) Providing a split mold, the split mold being a cuboid structure, laying a second prepreg on five surfaces of the split mold, and then pressing it tightly into the cavity covered with the first prepreg, and making the surface of the split mold without the second prepreg face away from the bottom of the cavity, and, attaching a buffer layer to the side surface of the split mold that does not directly contact the female mold;

[0008] (3) Repeating step (2) more than once to form a preform with a multi-grid structure;

[0009] (4) Curing the preform to form a multi-grid box body with multiple grid units, the first prepreg forms the outer shell of the multi-grid box body after curing, the second prepreg and the buffer layer form partitions after curing, and the multiple grid units are separated by the partitions, and the partitions include a surface layer formed by the second prepreg and a buffer layer sandwiched between the surface layers.

[0010] A second aspect of an embodiment of the present invention provides a carbon fiber multi-grid box body of a multi-module lithium metal solid-state battery obtained by the forming method of the carbon fiber multi-grid box body of the multi-module lithium metal solid-state battery.

[0011] In the third aspect of the embodiments of the present invention, a lithium metal solid-state battery assembly includes: the multi-module lithium metal solid-state battery carbon fiber multi-grid box body, and a lithium metal solid-state battery module. A plurality of lithium metal solid-state batteries included in the lithium metal solid-state battery module are respectively arranged in a plurality of grid units of the multi-module lithium metal solid-state battery carbon fiber multi-grid box body.

[0012] Compared with the prior art, the advantages of the present invention include: the forming method of the multi-module lithium metal solid-state battery carbon fiber multi-grid box body provided by the embodiments of the present invention has a simple process flow. The obtained multi-grid box body has high structural strength and stiffness, and can effectively bear the pressure generated during the expansion and deformation of the lithium metal solid-state battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic structural diagram of a female mold provided in a typical embodiment of the present invention;

[0014] Figure 2 is a schematic configuration diagram of a split mold and a buffer layer in a typical embodiment of the present invention;

[0015] Figure 3 is a schematic structural diagram after the configuration of all split molds and the female mold in a typical embodiment of the present invention;

[0016] Figure 4 is a schematic structural diagram of a multi-module lithium metal solid-state battery carbon fiber multi-grid box body obtained in a typical embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] In view of the deficiencies in the prior art, the inventors of this case have proposed the technical solution of the present invention through long-term research and a large number of practices. The following will further explain the technical solution, its implementation process, principles, etc.

[0018] The first aspect of the embodiments of the present invention provides a forming method of a multi-module lithium metal solid-state battery carbon fiber multi-grid box body, which includes:

[0019] (1) Laying a first prepreg on the cavity surface of the female mold, and the cavity of the female mold is a cuboid structure;

[0020] (2) Providing a split mold, the split mold is a cuboid structure, laying a second prepreg on five surfaces of the split mold, then tightly pressing it into the cavity paved with the first prepreg, and making the surface of the split mold without the second prepreg face away from the bottom of the cavity. In addition, a buffer layer is attached to the side surface of the split mold that does not directly contact the female mold;

[0021] (3) Repeat step (2) more than once to form a preform with a multi-grid structure;

[0022] (4) Cure the preform to form a multi-grid box body with multiple grid units. After curing, the first prepreg forms the outer shell of the multi-grid box body, and the second prepreg and the buffer layer cure to form partitions. The multiple grid units are separated by the partitions. The partitions include a surface layer formed by the second prepreg and a buffer layer sandwiched between the surface layers.

[0023] Further, both the first prepreg and the second prepreg are carbon fiber prepregs.

[0024] Further, the fiber volume content in the carbon fiber prepreg is 50%-70%, preferably 60%-65%.

[0025] Further, the higher the fiber volume content in the carbon fiber prepreg, the higher the tensile strength, compressive strength, and stiffness of the composite material are usually. However, too high a fiber volume content (such as >70%) may lead to uneven resin distribution, reduce the interlayer bonding force, and cause delamination or brittle fracture. At the same time, if the fiber volume content is higher and the resin content is lower, it may lead to insufficient resin fluidity, making it difficult to fully infiltrate the fibers and form pores or resin-starved areas. For example, when FVC > 65%, high pressure needs to be applied through an autoclave process to ensure uniform resin distribution. Moreover, when the resin content is too low, the tackiness of the prepreg will be reduced, affecting the conformability during layup, especially prone to warping or delamination in complex curved surface molds.

[0026] Further, the resin matrix contained in the carbon fiber prepreg includes at least one of epoxy resin, phenolic resin, and polyimide.

[0027] Further, the number of plies of the first prepreg is 13. Among them, the carbon fiber directions in the two surface layers on both sides are the 0° direction and the 90° direction, the carbon fiber direction in the middle layer is the unidirectional 90° direction, and the carbon fiber directions in the remaining layers are the unidirectional 0° direction. It can be understood that in the thirteen layers of the first prepreg, the carbon fiber directions in the first layer and the tenth layer are the 0° direction and the 90° direction, the carbon fiber direction in the seventh layer is the unidirectional 90° direction, and the carbon fiber directions in the remaining layers are the unidirectional 0° direction. The carbon fibers in the first prepreg located in the two surface layers on both sides are vertically crossed to form a woven layer.

[0028] Further, the number of layers of the second prepreg is 8. Among them, the carbon fiber directions in the two surface layers are the 0° direction and the 90° direction, the carbon fiber direction in the middle layer is the unidirectional 90° direction, and the carbon fiber directions in the remaining layers are the unidirectional 0° direction. It can be understood that in the eight-layer second prepreg, the carbon fiber directions in the first layer and the eighth layer are the 0° direction and the 90° direction, the carbon fiber directions in the fourth layer and the fifth layer are the unidirectional 90° direction, and the carbon fiber directions in the remaining layers are the unidirectional 0° direction. The carbon fibers in the second prepreg located in the two surface layers are vertically crossed to form a woven layer.

[0029] Further, the buffer layer is mainly composed of an elastic material.

[0030] Further, the elastic material includes at least one of silica gel, polyurethane elastomer, and rubber to form a foam, or the elastic material is PMI foam.

[0031] Further, the thickness ratio of the surface layer to the buffer layer in the partition is 1:3.

[0032] Further, the thickness of each surface layer is 1 mm, and the thickness of the buffer layer is 3 mm.

[0033] Further, the curing treatment includes: encapsulating the preform obtained in step (3) with a vacuum bag and placing it in an autoclave, maintaining it at a temperature of 80 °C and a pressure of 3 MPa for 30 min. Then, raise the temperature to 125 °C, increase the pressure to 5 MPa, and maintain it for 90 min. Finally, lower the temperature to 50 °C and release the pressure to atmospheric pressure to complete the curing.

[0034] Further, the forming method of the multi-module lithium metal solid-state battery carbon fiber multi-grid box body further includes: demolding after the curing treatment and performing surface treatment on the obtained multi-grid box body to remove excess wool and burrs, and machining the required positioning holes.

[0035] The second aspect of the embodiments of the present invention provides a multi-module lithium metal solid-state battery carbon fiber multi-grid box body manufactured by the forming method of the multi-module lithium metal solid-state battery carbon fiber multi-grid box body.

[0036] Further, the overall warpage of the multi-module lithium metal solid-state battery carbon fiber multi-grid box body is within 2 mm.

[0037] The third aspect of the embodiments of the present invention provides a lithium metal solid-state battery assembly, which includes: the multi-module lithium metal solid-state battery carbon fiber multi-grid box body, and a lithium metal solid-state battery module. The multiple lithium metal solid-state batteries included in the lithium metal solid-state battery module are respectively arranged in multiple grid units of the multi-module lithium metal solid-state battery carbon fiber multi-grid box body.

[0038] Furthermore, during the charge and discharge cycles of the lithium metal solid-state battery module, the deformation amount of the lithium metal solid-state battery module in the thickness direction does not exceed 10% of the total thickness of the battery cell.

[0039] The technical solution, its implementation process, principle, etc. will be further explained below in conjunction with the accompanying drawings and specific implementation cases.

[0040] In a relatively typical implementation case, a forming method for a carbon fiber multi-grid box body of a multi-module lithium metal solid-state battery includes the following steps:

[0041] 1) Lay a plurality of layers of prepreg as the shell in a large rectangular female mold.

[0042] Provide a rectangular female mold as shown in Figure 1 The rectangular female mold has a cavity with an open top. The cavity is of a rectangular structure. Lay thirteen layers of first prepreg on the surface of the cavity of the female mold. The first prepreg is a carbon fiber prepreg with a fiber volume content of 50%-70%, preferably 60%-65%. Among the thirteen layers of first prepreg, the carbon fiber directions in the first layer and the tenth layer are 0° and 90° directions, the carbon fiber direction in the seventh layer is a unidirectional 90° direction, and the carbon fiber directions in the remaining layers are unidirectional 0° directions.

[0043] (2) Provide a split mold. The split mold is of a rectangular structure. A demolding handle is provided on one surface of the split mold. Lay eight layers of second prepreg on the five surfaces of the split mold except the surface with the demolding handle. The second prepreg is a carbon fiber prepreg with a fiber volume content of 50%-70%, preferably 60%-65%. Among the eight layers of second prepreg, the carbon fiber directions in the first layer and the eighth layer are 0° and 90° directions, the carbon fiber directions in the fourth layer and the fifth layer are unidirectional 90° directions, and the carbon fiber directions in the remaining layers are unidirectional 0° directions;

[0044] Then press it tightly into the cavity paved with the first prepreg, and make the surface of the split mold without the second prepreg facing up away from the bottom of the cavity. In addition, attach a buffer layer to the side surface of the split mold that does not directly contact the female mold. The buffer layer is a PMI foam with a thickness of 3 mm, as shown in Figure 2 the figure.

[0045] (3) Repeat step (2) five times until the last split mold is placed in the cavity to form a preform with a multi-grid structure, as shown in Figure 3 the figure.

[0046] (4) The preform obtained in step (3) is encapsulated with a vacuum bag and placed in an autoclave for curing. The curing process includes: setting the temperature in the autoclave to 80 °C, the pressure to 3 MPa, and maintaining for 30 min. Then, the temperature in the autoclave is raised to 125 °C, the pressure is increased to 5 MPa, and maintained for 90 min. Finally, the temperature in the autoclave is lowered to 50 °C, and the pressure is released to atmospheric pressure, thus completing the curing, and a multi-grid box body with multiple grid units having a stable structure and sufficient deformation allowance can be obtained, as Figure 4 shown. Among them, the first prepreg forms the outer shell of the multi-grid box body after curing, the second prepreg and the buffer layer form partitions after curing, and the multiple grid units are separated by the partitions. The partitions include a surface layer formed by the second prepreg and a buffer layer sandwiched between the surface layers.

[0047] Theoretical and actual tests show that when a lithium metal battery cell is encapsulated in the carbon fiber multi-grid box body of this multi-module lithium metal solid-state battery, the number of cycles of the lithium metal battery cell under pressure is significantly better than that under the non-pressure state. Through the optimization of the above box body, the binding force on the lithium metal battery cell is enhanced, and the number of cycles of the battery cell will be correspondingly increased.

[0048] It should be understood that the above embodiments are only used to illustrate the technical concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for forming a multi-module lithium metal solid-state battery carbon fiber multi-grid box, characterized in that: include: (1) Laying a first prepreg on the surface of a cavity of a concave mold, wherein the cavity of the concave mold is a rectangular parallelepiped structure; (2) Providing a split mold, the split mold is a rectangular parallelepiped structure, and the second prepreg is laid on five surfaces of the split mold, and then it is pressed tightly into the mold cavity covered with the first prepreg, and the surface of the split mold not covered with the second prepreg is opposite to the bottom of the mold cavity, and a buffer layer is attached to the side of the split mold that is not in direct contact with the concave mold, the first prepreg and the second prepreg are both carbon fiber prepregs, the fiber volume content of the carbon fiber prepreg is 50%-70%, and the resin matrix contained in the carbon fiber prepreg includes at least one of epoxy resin, phenolic resin, and polyimide; (3) repeating step (2) one or more times to form a preform having a multi-grid structure; (4) The preform is cured to form a multi-grid box having a plurality of grid units, wherein the first prepreg is cured to form an outer shell of the multi-grid box, and the second prepreg and the buffer layer are cured to form a partition, wherein the plurality of grid units are separated by the partition, and the partition comprises a surface layer formed by the second prepreg and a buffer layer sandwiched between the surface layers.

2. The method for forming a multi-module lithium metal solid-state battery carbon fiber multi-grid box according to claim 1, characterized in that: The number of cladding layers of the first prepreg is 13 layers, wherein the directions of the carbon fibers in the surface layers on both sides are 0° and 90°, the direction of the carbon fibers in the middle layer is unidirectional 90°, and the direction of the carbon fibers in the remaining layers is unidirectional 0°; The number of cladding layers of the second prepreg is 8, wherein the directions of the carbon fibers in the surface layers on both sides are 0° and 90°, the direction of the carbon fibers in the middle layer is unidirectional 90°, and the direction of the carbon fibers in the remaining layers is unidirectional 0°; The buffer layer is mainly composed of an elastic material, and the elastic material includes foam formed by at least one of silicone, polyurethane elastomer, and rubber, or the elastic material is PMI foam.

3. The method for forming a multi-module lithium metal solid-state battery carbon fiber multi-grid box according to claim 2, characterized in that: The thickness ratio of the surface layer to the buffer layer in the separator is 1:

3.

4. The method for forming a multi-module lithium metal solid-state battery carbon fiber multi-grid box according to claim 1, characterized in that: The curing treatment comprises: packaging the preform obtained in step (3) with a vacuum bag and placing it in an autoclave, maintaining it at a temperature of 80° C. and a pressure of 3 MPa for 30 minutes, then raising the temperature to 125° C. and the pressure to 5 MPa, and maintaining them for 90 minutes, and finally lowering the temperature to 50° C. and releasing the pressure to normal pressure, thereby completing the curing.

5. The method for forming a multi-module lithium metal solid-state battery carbon fiber multi-grid box according to claim 1, characterized in that: Also includes: After the curing treatment, demoulding is performed and the obtained multi-grid box is subjected to surface treatment.

6. A multi-module lithium metal solid-state battery carbon fiber multi-grid box manufactured by the forming method of a multi-module lithium metal solid-state battery carbon fiber multi-grid box according to any one of claims 1 to 5.

7. The multi-module lithium metal solid-state battery carbon fiber multi-grid box according to claim 6, characterized in that: The overall warping degree of the multi-module lithium metal solid-state battery carbon fiber multi-grid box is within 2 mm.

8. A lithium metal solid-state battery assembly, characterized in that: include: The multi-module lithium metal solid-state battery carbon fiber multi-grid box as described in claim 6 or 7, and the lithium metal solid-state battery module, the lithium metal solid-state battery module comprises a plurality of lithium metal solid-state batteries, and the plurality of lithium metal solid-state batteries are respectively arranged in a plurality of grid units of the multi-module lithium metal solid-state battery carbon fiber multi-grid box.

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