Structural battery and preparation method thereof

Abstract

The invention relates to a structural battery and a preparation method thereof, and belongs to the technical field of secondary batteries. The structural battery comprises a shell and a plurality of battery bodies, wherein the battery bodies are accommodated in the shell; the material of the shell comprises a fiber composite material; the battery bodies are connected in series and / or in parallel, each battery body comprises a positive pole piece, a solid electrolyte layer and a negative pole piece which are stacked, and the solid electrolyte layer is arranged between the positive pole piece and the negative pole piece; by utilizing the characteristic of high energy density of the solid-state battery cell and the characteristics of high mechanical property, easy forming and the like of the fiber composite material, the solid-state battery cell is coated by adopting the fiber composite material as the shell, so that the structural battery can give consideration to both energy density and mechanical strength.

Description

Technical Field

[0001] The present application relates to the field of secondary batteries, and in particular to a structural battery and a method for preparing the same. Background Art

[0002] Lithium-ion batteries are widely used in electric vehicles, electric aircraft and other electrification fields due to their excellent performance. However, the energy density of the most advanced batteries is still unsatisfactory, which limits the further expansion of the driving range. At present, the battery packs of new energy vehicles use liquid batteries such as ternary lithium-ion batteries and lithium iron phosphate lithium-ion batteries. They are composed of electrodes and diaphragms filled with liquid electrolytes and sealed in bags or metal shells. They cannot meet the mechanical requirements, so new designs are needed to enhance the mechanical properties. Generally, in order to enhance the strength of the battery pack, it is necessary to consider longitudinal and transverse beam design, modules and other solutions in the battery pack to enhance the strength and safety of the entire pack, but this will further reduce the energy density of the battery. Summary of the invention

[0003] The present application provides a structural battery and a preparation method thereof, which take into account both the energy density and mechanical strength of the battery.

[0004] In the first aspect, the present application provides a structural battery, which includes a shell and a plurality of battery bodies, wherein the battery bodies are accommodated in the shell; the material of the shell includes a fiber composite material; the battery bodies are connected in series and / or in parallel with each other, and the battery bodies include a stacked positive electrode sheet, a solid electrolyte layer and a negative electrode sheet, and the solid electrolyte layer is arranged between the positive electrode sheet and the negative electrode sheet.

[0005] As an optional implementation manner, the fiber composite material includes fiber material and resin.

[0006] As an optional embodiment, the fiber material includes at least one of glass fiber and carbon fiber; and / or

[0007] The resin includes at least one of phenolic resin, urea-formaldehyde resin, polyamide resin, epoxy resin, polyester resin, polyurethane and thermoplastic resin.

[0008] As an optional implementation, the thickness of the shell is 5 mm to 10 mm.

[0009] As an optional embodiment, the shell includes a shell frame and a cover plate, the positive electrode plate, the solid electrolyte layer and the negative electrode plate are accommodated in the shell frame, and the cover plate is covered on at least one end surface of the shell frame; the material of the shell frame includes glass fiber; the material of the cover plate includes carbon fiber.

[0010] As an optional implementation, the positive electrode plate includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is attached to the positive electrode current collector, and the positive electrode current collector includes a metal foil or a composite current collector.

[0011] As an optional implementation, the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is attached to the negative electrode current collector, and the negative electrode current collector includes a metal foil or a composite current collector.

[0012] As an optional implementation, the positive electrode active material of the positive electrode active material layer has a core-shell structure, the core of the positive electrode active material is the active material body, and the shell layer of the positive electrode active material includes a coated solid electrolyte.

[0013] As an optional implementation, the negative electrode active material of the negative electrode active material layer includes a silicon-carbon material.

[0014] As an optional implementation, components of the solid electrolyte layer include: oxide electrolyte and polymer electrolyte.

[0015] In a second aspect, the present application provides a method for preparing the structural battery provided in the first aspect, the method comprising:

[0016] A plurality of battery bodies are obtained, wherein the battery bodies are connected in series and / or in parallel with each other, and the battery bodies include a positive electrode sheet, a solid electrolyte layer and a negative electrode sheet which are stacked, and the solid electrolyte layer is arranged between the positive electrode sheet and the negative electrode sheet;

[0017] Obtaining a fiber composite material prepreg;

[0018] The fiber composite material prepreg is attached between the plurality of battery bodies and on the surfaces of the plurality of battery bodies, and the fiber composite material prepreg is solidified into a shell to obtain a structural battery.

[0019] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0020] The structural battery provided in the embodiment of the present application utilizes the high energy density characteristics of solid-state battery cells and the high mechanical properties and easy molding characteristics of fiber composite materials. By using fiber composite materials as a shell to cover the solid-state battery cells, the structural battery can take into account both energy density and mechanical strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0023] Figure 1 A schematic diagram of the structure of a battery provided in an embodiment of the present application;

[0024] Figure 2 for Figure 1 Sectional view at AA in the middle;

[0025] Figure 3 A process diagram of the method provided in an embodiment of the present application.

[0026] Figure numerals: 1 - shell; 11 - shell frame; 12 - cover plate; 2 - battery body. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0028] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0029] The current batteries still have a lot of room for improvement in mechanical properties and energy density. To this end, this application intends to provide a structural battery. The inventor believes that: in terms of mechanical properties, structural batteries need to have high strength in multiple directions, and other strategies such as binders and solid electrolytes should be adopted. At the same time, from an electrochemical point of view, in addition to energy density, structural batteries usually also need to meet cycle life and reasonable power density. In addition, safety is one of the primary requirements for all batteries, and it is even more critical for structural batteries because their working environment is much more harsh. Therefore, it is possible to consider the use of non-flammable liquid electrolytes, solid electrolytes, thermally stable diaphragms and adhesives, as well as strong and light external protection. Therefore, to realize structural batteries, several key points must be met: mechanical properties, electrochemical properties, safety and cost.

[0030] Fiber composite materials have high mechanical properties and are easy to form, and solid-state batteries have high energy density and are easy to integrate. Solid-state batteries and fiber composite prepregs are molded into one to prepare an integrated composite structural battery. At the same time, according to actual conditions, the capacity requirements of the structural battery and the arrangement of the structural battery in the battery pack can be considered, and the capacity and voltage of the structural battery monomer can be confirmed in combination with the design indicators of the solid-state battery system, and the series-parallel design of the solid-state battery cells inside the structural battery can be carried out.

[0031] Figure 1 and Figure 2 A schematic diagram of the structure of a battery provided in an embodiment of the present application, such as Figure 1 and Figure 2 As shown, an embodiment of the present application provides a structural battery, which includes a shell and a plurality of battery bodies, wherein the battery bodies are accommodated in the shell; the material of the shell includes a fiber composite material; the battery bodies are connected in series and / or in parallel with each other, and the battery bodies include a stacked positive electrode sheet, a solid electrolyte layer and a negative electrode sheet, and the solid electrolyte layer is arranged between the positive electrode sheet and the negative electrode sheet.

[0032] Solid-state batteries and composite materials such as carbon fiber can be assembled in layers. By utilizing the high energy density of solid-state battery cells and the high mechanical properties and easy forming of fiber composite materials, the strength of the battery pack can be optimized from the box directly to the battery cells, and an integrated structural battery can be constructed. This allows the structural battery to have both energy density and mechanical strength, thereby improving the endurance of the entire vehicle, increasing production efficiency, making the structure stronger, and even improving the handling of the entire vehicle.

[0033] In some embodiments, the fiber composite material includes a fiber material and a resin. Further, the fiber material includes at least one of glass fiber and carbon fiber; the resin includes at least one of phenolic resin, urea-formaldehyde resin, polyamide resin, epoxy resin, polyester resin, polyurethane and thermoplastic resin. Epoxy resin has excellent properties such as bonding strength, corrosion resistance and heat resistance. Polyester resin has good toughness and impact resistance, and is often used to manufacture composite materials requiring higher impact performance; phenolic resin has excellent heat resistance and corrosion resistance, and is often used to manufacture composite materials requiring high temperature and corrosion resistance; thermoplastic resin has good processability and formability, and is often used to manufacture composite materials requiring high precision and complex shapes.

[0034] In some embodiments, the thickness of the shell is 5 mm to 10 mm. Exemplarily, the thickness of the shell can be 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc., and can also be any value within the range of 5 mm to 10 mm.

[0035] Glass fiber has good toughness, plays the role of insulation, flame retardant and breathable stress control, carbon fiber has higher strength, and taking advantage of the difference in properties between glass fiber and carbon fiber, in some embodiments, the shell includes a shell frame and a cover plate, the battery body is accommodated in the shell frame, and the cover plate is covered on at least one end face of the shell frame; the material of the shell frame includes glass fiber; the material of the cover plate includes carbon fiber. Glass fiber has good toughness, plays the role of insulation, flame retardant and breathable stress control, and is applied to the battery body to achieve insulation effect. High-strength carbon fiber constitutes a composite material and is applied to the upper and lower structural cover plates to increase the strength of the structural battery. Specifically, the thickness of the cover plate is 3mm to 6mm, the thickness of the shell frame is 0.5mm to 1mm, and the cover plate and the battery body closest to it are spaced 1mm to 2mm apart to achieve better insulation.

[0036] In some embodiments, the positive electrode plate includes a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer is attached to the positive electrode current collector, and the positive electrode current collector includes a metal foil or a composite current collector; the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer is attached to the negative electrode current collector, and the negative electrode current collector includes a metal foil or a composite current collector. Generally, the positive electrode current collector can be made of aluminum foil, and the negative electrode current collector can be made of copper foil. By using metal foil or a composite current collector as the positive electrode current collector and the negative electrode current collector in combination with the solid electrolyte layer, the battery can have better electrical performance.

[0037] In some embodiments, the positive active material of the positive active material layer has a core-shell structure, the core of the positive active material is the active material body, and the shell layer of the positive active material includes a coated solid electrolyte; the negative active material of the negative active material layer includes a silicon-carbon material. The active material body can be selected from a ternary material, such as NCM; the coated solid electrolyte can be selected from lithium aluminum titanium phosphate (LATP).

[0038] In some embodiments, components of the solid electrolyte layer include: an oxide electrolyte and a polymer electrolyte.

[0039] Figure 3 A process diagram of the method provided in the embodiment of the present application, such as Figure 3 As shown, based on a general inventive concept, an embodiment of the present application also provides a method for preparing the structural battery provided above.

[0040] The method is used to prepare the above-mentioned structural battery. The specific content of the structural battery can refer to the above-mentioned embodiment. Since the method adopts part or all of the technical solutions of the above-mentioned embodiment, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be repeated here one by one.

[0041] In some embodiments, the method comprises:

[0042] S1. Obtain a plurality of battery bodies, each of which is connected in series and / or in parallel, wherein the battery body comprises a stacked positive electrode sheet, a solid electrolyte layer and a negative electrode sheet, wherein the solid electrolyte layer is disposed between the positive electrode sheet and the negative electrode sheet;

[0043] S2. Obtaining a fiber composite material prepreg;

[0044] S3. Attaching the fiber composite material prepreg between and on the surfaces of the plurality of battery bodies, and solidifying the fiber composite material prepreg into a shell to obtain a structural battery.

[0045] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0046] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present specification, the terms "including", "comprising", etc. refer to "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of the associated objects, indicating that there may be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "plural" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc, or abc, where a, b and c can be single or multiple.

[0047] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A structural battery, characterized in that: The structural battery includes a shell and multiple battery bodies, and the battery bodies are accommodated in the shell; the material of the shell includes a fiber composite material; the battery bodies are connected in series and / or in parallel with each other, and the battery bodies include stacked positive electrode sheets, solid electrolyte layers and negative electrode sheets, and the solid electrolyte layers are arranged between the positive electrode sheets and the negative electrode sheets.

2. The structural battery according to claim 1, characterized in that: The fiber composite material comprises a fiber material and a resin.

3. The structural battery according to claim 2, characterized in that: The fiber material comprises at least one of glass fiber and carbon fiber; and / or The resin includes at least one of phenolic resin, urea-formaldehyde resin, polyamide resin, epoxy resin, polyester resin, polyurethane and thermoplastic resin.

4. The structural battery according to claim 1, characterized in that: The thickness of the shell is 5 mm to 10 mm.

5. The structural battery according to claim 1, characterized in that: The shell includes a shell frame and a cover plate, the positive electrode plate, the solid electrolyte layer and the negative electrode plate are accommodated in the shell frame, and the cover plate is covered on at least one end surface of the shell frame; the material of the shell frame includes glass fiber; the material of the cover plate includes carbon fiber.

6. The structural battery according to claim 1, characterized in that: The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The positive electrode active material layer is attached to the positive electrode current collector. The positive electrode current collector includes a metal foil or a composite current collector.

7. The structural battery according to claim 6, characterized in that: The positive electrode active material of the positive electrode active material layer has a core-shell structure, the core of the positive electrode active material is the active material body, and the shell layer of the positive electrode active material includes a coated solid electrolyte.

8. The structural battery according to claim 1, characterized in that: The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode active material layer is attached to the negative electrode current collector. The negative electrode current collector includes a metal foil or a composite current collector.

9. The structural battery according to claim 8, characterized in that: The negative electrode active material of the negative electrode active material layer includes a silicon-carbon material.

10. A method for preparing a structural battery according to any one of claims 1 to 9, characterized in that: The method comprises: A plurality of battery bodies are obtained, wherein the battery bodies are connected in series and / or in parallel with each other, and the battery bodies include a positive electrode sheet, a solid electrolyte layer and a negative electrode sheet which are stacked, and the solid electrolyte layer is arranged between the positive electrode sheet and the negative electrode sheet; Obtaining a fiber composite material prepreg; The fiber composite material prepreg is attached between the plurality of battery bodies and on the surfaces of the plurality of battery bodies, and the fiber composite material prepreg is solidified into a shell to obtain a structural battery.

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