Battery and preparation method

Abstract

The invention relates to a battery and a preparation method in the technical field of lithium batteries, the battery comprises at least two stacked battery cell units, each battery cell unit comprises two negative pole pieces and a positive pole piece arranged between the two negative pole pieces, each negative pole piece comprises a negative pole composite current collector, and each positive pole piece comprises a positive pole composite current collector and a negative pole composite current collector. The negative electrode composite current collector comprises an elastic base material and a metal layer, one side of the elastic base material is provided with the metal layer, and the other side of the elastic base material is stacked with the elastic base material in the other cell unit. The current collector in the negative pole piece is arranged to be the negative current collector compounded by the elastic base material and the metal layer, and through the arrangement of the battery cell units including the negative electrode, the positive electrode and the negative electrode, when the battery is assembled, the elastic base material in the negative pole piece of the battery cell unit can be used as a buffer layer; the problem that the volume of the battery is easy to change in the use process is solved, and the preparation process is simpler and more convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a battery and a preparation method thereof. Background Art

[0002] With the development and progress of science and technology, lithium-ion batteries are increasingly used in power, energy storage, 3C and other fields, and the market requirements for the energy density of lithium-ion batteries are getting higher and higher.

[0003] Normally, lithium-ion batteries use pure metal foil as the current collector of the negative electrode. The thinner the current collector material is, the more the energy density of the battery will increase. However, due to other issues such as safety, the current collector material cannot be further thinned after reaching a certain threshold, which also results in the energy density of the lithium battery being unable to continue to increase. During the charging and discharging process of the battery, the volume of the battery will change, which will also have an adverse effect on the battery life and performance. In the prior art, it is often necessary to set a buffer layer between the two battery cells to solve this problem, which increases the complexity of the battery preparation process.

[0004] Therefore, the market is in urgent need of a technical solution to solve the above problems. Summary of the invention

[0005] In order to solve the above technical problems, the present invention discloses a battery and a preparation method, which uses a composite negative electrode current collector, including an elastic substrate and a metal layer, wherein the elastic substrate can be used as a buffer layer to reduce the impact of the volume change of the battery. At the same time, the preparation steps are completed when the negative electrode current collector is prepared, rather than adding a buffer layer after the traditional positive and negative electrode lamination. The present invention is more convenient to prepare, and the positive electrode uses a composite positive electrode current collector, taking into account the energy density of the battery. The technical solution of the present invention is implemented as follows:

[0006] A first aspect of the present invention discloses a battery, the battery comprising at least two stacked battery cells;

[0007] The battery cell unit comprises two negative electrode sheets and a positive electrode sheet arranged between the two negative electrode sheets;

[0008] The negative electrode plate includes a negative electrode composite current collector;

[0009] The negative electrode composite current collector comprises an elastic substrate and a metal layer;

[0010] Wherein, a metal layer is arranged on one side of the elastic substrate, and the other side of the elastic substrate is stacked with an elastic substrate in another battery cell unit.

[0011] The negative electrode pole piece of the present invention adopts a composite current collector structure, and the negative electrode metal layer is only arranged on one side of the elastic substrate, and the side of the elastic substrate away from the negative electrode metal layer is hot-pressed and fixed with the elastic substrates of other battery cells. In addition, the elastic substrate itself is also used as a buffer layer, which can not only effectively alleviate the influence of battery expansion on battery performance but also prevent the negative electrode metal layer from breaking. At the same time, there is no need to add an additional buffer layer after the negative electrode pole piece is prepared, and the preparation process is simpler. The present invention adopts a negative electrode pole piece, a positive electrode pole piece, and a negative electrode pole piece stacked in sequence as a battery cell unit. Negative electrode pole pieces are arranged on both sides of each battery cell unit, and the outermost side of the negative electrode pole piece is an elastic substrate. A battery with any number of battery cell units can be assembled as needed.

[0012] In a specific application, the material of the elastic substrate can be selected from one or more of PET / PP / PI, and the metal layer can be selected from copper foil. The above is only an example and not a limitation.

[0013] Copper foil is a commonly used current collector material for negative electrodes because of its good electrical and thermal conductivity, which can effectively improve the energy density and charge and discharge efficiency of batteries.

[0014] Methods for disposing the copper foil on the elastic substrate include, but are not limited to, physical vapor deposition, electroplating, or chemical plating.

[0015] In actual operation, any one of the above methods or a combination of two or more can be selected to achieve the bonding of the copper foil and the elastic substrate, and the present invention does not impose any limitation on this.

[0016] Preferably, the negative electrode composite current collector further comprises an anti-corrosion layer, and the anti-corrosion layer is arranged on a side of the metal layer away from the elastic substrate layer.

[0017] Copper foil is a commonly used negative electrode current collector. When it is used in a solid electrolyte system, especially a sulfide solid electrolyte system or a halide solid electrolyte system, the copper foil will be corroded, further leading to premature failure of the battery. At the same time, PET, a commonly used material for elastic substrates, has poor corrosion resistance. Therefore, providing an anti-corrosion layer at the metal layer can solve the above problems and enable the negative electrode plate to have both energy density and safety performance.

[0018] In a specific application, the anti-corrosion layer can be selected from one or more of nickel foil, chromium foil, and stainless steel foil. The above is only an example and not a limitation.

[0019] Preferably, the negative electrode plate further comprises a negative electrode active material layer, and the negative electrode active material layer is arranged on a side of the anti-corrosion layer away from the metal layer.

[0020] Preferably, the negative electrode active material layer includes a negative electrode active material, a conductive agent and a binder.

[0021] In specific applications, the negative electrode active material can be selected to include any one of artificial graphite, natural graphite, microcrystalline graphite, soft carbon and hard carbon, or a combination of at least two of them. The above are common negative electrode active materials in the art, which are only examples and not limitations.

[0022] In specific applications, the conductive agent includes any one or a combination of at least two of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene or carbon nanofibers. The above are all common conductive agents in the art, which are only examples and not limitations.

[0023] In specific applications, the binder includes any one of polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyvinyl chloride, polystyrene, polyoxymethylene, polycarbonate, polyamide, acrylic plastics, other polyolefins and their copolymers, polysulfone, polyphenylene ether or carboxymethyl cellulose, or a combination of at least two of them. The above are all common binders in the art and are only examples and not limitations.

[0024] In some preferred applications, the binder is polytetrafluoroethylene or polyvinyl chloride.

[0025] Preferably, the positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer arranged on both sides of the positive electrode current collector.

[0026] Preferably, the positive electrode current collector is a positive electrode composite current collector, comprising a positive electrode substrate layer and positive electrode metal layers arranged on both sides of the positive electrode substrate layer.

[0027] The positive electrode adopts a composite current collector, which can reduce the mass of the current collector per unit area, realize the lightweight of the lithium battery, and is beneficial to improve the energy density of the battery. At the same time, the positive electrode substrate layer can also use an elastic substrate, which can further reduce the volume change of the battery during use and the impact of the volume change.

[0028] Preferably, the positive electrode active material layer includes a positive electrode active material, a conductive agent and a binder.

[0029] In specific applications, the positive electrode active material can be selected to include any one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, lithium iron manganese phosphate, lithium vanadium phosphate, lithium vanadium phosphate, lithium iron phosphate, lithium titanate or lithium-rich manganese, or a combination of at least two of them. The above are all common positive electrode active materials in the art, which are only examples and not limitations.

[0030] Preferably, a solid electrolyte layer is further provided between the positive electrode active material layer and the negative electrode active material layer.

[0031] In specific applications, the solid electrolyte can be any one of halide solid electrolytes or any one of sulfide solid electrolytes, or any combination of at least one halide solid electrolyte and at least one sulfide solid electrolyte. The present invention does not impose any restrictions on this.

[0032] In specific applications, the halide solid electrolyte can be selected from: Li2CdC l4 , Li2MgC l4 , Li2Cd I4 , Li2ZnI4, Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x (where 0 < x < 1) of at least one.

[0033] In specific applications, the sulfide solid electrolyte can be selected from: Li2S-P2S5, Li2S-P2S5-MS x (where M is Si, Ge, and Sn and 0 ≤ x ≤ 2), Li 3.4 Si 0.4 P 0.6 S4, Li 10 GeP2S 11.7 O 0.3 , Li 9.6 P3S 12 , Li7P3S 11 , Li9P3S9O3, Li 10.35 Si 1.35 P 1.65 S 12 , Li 9.81 Sn 0.81 P 2.19 S 12 , Li 10 (Si 0.5 Ge 0.5 )P2S 12 , Li(Ge 0.5 Sn 0.5 )P2S 12 , Li(Si 0.5 Sn 0.5 )PsS 12 , Li 10 GeP2S 12 (LGPS), Li6PS5X (where X is Cl, Br, or I), Li7P2S8I, Li 10.35 Ge 1.35 P 1.65 S 12 , Li 3.25 Ge 0.25 P 0.75 S4, Li10 SnP2S 12 , Li 10 SiP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 C l0.3 , (1-x) P2S 5-x At least one of Li2S (wherein 0.5≤x≤0.7).

[0034] The second aspect of the present invention discloses a method for preparing a battery, the method comprising the following steps:

[0035] S1, preparing a negative electrode sheet;

[0036] S1.1, selecting an elastic material and preparing an elastic substrate;

[0037] S1.2, disposing a negative electrode metal layer on one side of the elastic substrate to prepare a negative electrode composite current collector;

[0038] S1.3, disposing a negative electrode active material on the negative electrode composite current collector to prepare a negative electrode sheet;

[0039] S2, preparing a positive electrode sheet;

[0040] S3, preparing a battery cell unit;

[0041] The negative electrode sheet, the solid electrolyte layer, the positive electrode sheet, the solid electrolyte layer, and the negative electrode sheet are stacked in sequence and hot pressed to form a battery cell unit;

[0042] S4, preparing the battery;

[0043] At least two battery cell units are stacked, and the elastic substrate on the negative electrode sheet of one battery cell unit is stacked and hot-pressed with the elastic substrate on the negative electrode sheet of another battery cell unit to prepare a battery.

[0044] Usually, the preparation process of a battery is to first prepare the positive and negative electrode sheets to form a battery cell, and then add a buffer layer to alleviate the volume change of the battery. The preparation process of the battery in the present invention is to composite the elastic substrate and the negative electrode metal layer into a negative electrode composite current collector, wherein the elastic substrate can be used as a buffer layer. Unlike the conventional method of setting a buffer layer between two battery cell units, the elastic substrate used as a buffer layer in the present application is integrally formed when the negative electrode is prepared, which simplifies the production process of lithium-ion batteries containing buffer layers. In the present invention, different numbers of battery cell units can be selected according to actual needs to be stacked to prepare batteries with different energies, and when preparing the battery, there is no need to consider the alignment of conventional positive and negative electrode alternating laminations when adding a buffer layer.

[0045] Preferably, the step S1.2 further includes providing an anti-corrosion layer on a side of the metal layer away from the elastic substrate.

[0046] Preferably, S2 includes S2.1, selecting an elastic material to prepare an elastic substrate;

[0047] S2.2, disposing a positive electrode metal layer on both sides of the elastic substrate to prepare a positive electrode composite current collector;

[0048] S2.3, disposing a positive electrode active material on the positive electrode composite current collector to prepare a positive electrode sheet.

[0049] The negative electrode plate of the present invention adopts a composite current collector structure, the negative electrode metal layer is only arranged on one side of the elastic substrate, and the side of the elastic substrate away from the negative electrode metal layer is hot-pressed and fixed with the elastic substrates of other battery cells. The elastic substrate can be used as a buffer layer, which can not only effectively alleviate the impact of battery expansion on battery performance but also prevent the negative electrode metal layer from breaking. At the same time, there is no need to add an additional buffer layer after the negative electrode plate is prepared, and the preparation process is simpler.

[0050] The positive electrode plate of the present invention adopts a composite current collector, which can reduce the mass of the current collector per unit area, realize the lightweight of the lithium battery, and is conducive to improving the energy density of the battery. At the same time, the positive electrode substrate layer can also use an elastic substrate, which can further reduce the volume change of the battery during use and the impact of the volume change;

[0051] The present invention adopts a structure in which negative electrode sheets, positive electrode sheets and negative electrode sheets are stacked in sequence as a battery cell unit. Negative electrode sheets are arranged on both sides of each battery cell unit and the outermost side of the negative electrode sheets is an elastic substrate. A battery with any number of battery cell units can be assembled as needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present invention 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, the drawings described below are only one embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0053] The same parts are denoted by the same reference numerals. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the drawings, and the words "bottom" and "top", "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0054] Figure 1 It is a schematic structural diagram of an embodiment of the present invention;

[0055] Figure 2 for Figure 1 A schematic diagram of the structure of a battery cell unit in the embodiment shown;

[0056] Figure 3 Schematic diagram of the hot pressing process of the first battery cell unit and the second battery cell unit in an embodiment of the present invention.

[0057] In the above drawings, the figure numbers represent:

[0058] 1. Negative electrode elastic substrate;

[0059] 2. Negative metal layer;

[0060] 3. Negative electrode anti-corrosion layer;

[0061] 4. Negative electrode active material layer;

[0062] 5. Solid electrolyte layer;

[0063] 6. Positive electrode active material layer;

[0064] 7. Positive electrode composite current collector;

[0065] 8. The first battery cell unit,

[0066] 9. A second battery cell unit;

[0067] 10.Battery. DETAILED DESCRIPTION

[0068] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0069] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by technicians in the technical field to which the present invention belongs; the terms used in the specific implementation methods are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" in the specification and claims of the present invention and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0070] In the description of the specific implementation methods of the present invention, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0071] Reference to "embodiments" in the present invention means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present invention may be combined with other embodiments.

[0072] In the description of the embodiments of the present invention, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects before and after are in an "or" relationship.

[0073] Throughout the present invention, numerical values ​​represent approximate measures or limits of ranges to cover minor deviations from given values ​​as well as embodiments with about the values ​​mentioned and embodiments with the exact values ​​mentioned. Except for the working examples provided at the end of the detailed description, all numerical values ​​of parameters (e.g., amounts or conditions) in this specification (including the appended claims) should be understood to be modified by the term "about" in all cases, regardless of whether "about" actually appears before the numerical value. "About" indicates that the stated numerical value allows some minor imprecision (close to the exact value of the value to some extent; approximately or reasonably close to the value; almost). If the imprecision provided by "about" is not otherwise understood in this ordinary sense in the art, "about" as used in the present invention at least indicates the variation that can be produced by the ordinary methods of measuring and using such parameters. For example, "about" may include a variation of less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in some aspects, optionally less than or equal to 0.1%.

[0074] Additionally, disclosure of ranges includes disclosure of all values ​​within the entire range and further divided ranges, including endpoints and sub-ranges given for such ranges.

[0075] The embodiments of the present invention will be described in more detail below by way of examples. It should be noted that the embodiments of the present invention are not limited to these examples.

[0076] Example

[0077] This embodiment discloses a Figure 1 The battery 10 shown includes a first battery cell unit 8 and a second battery cell unit 9 which are stacked.

[0078] The structures of the first battery cell unit 8 and the second battery cell unit 9 are completely the same. Taking the first battery cell unit 8 as an example, the structure of the first battery cell unit 8 is as follows: Figure 3 As shown, it includes two negative electrode sheets and a positive electrode sheet arranged between the two negative electrode sheets; a solid electrolyte layer 5 is arranged between the positive electrode sheet and the negative electrode sheet; the negative electrode sheet includes a negative electrode composite current collector and a negative electrode active material layer 4 arranged on one side of the negative electrode composite current collector; the negative electrode composite current collector includes a negative electrode elastic substrate 1 and a negative electrode metal layer 2 arranged on one side of the negative electrode elastic substrate 1; a negative electrode anti-corrosion layer 3 is arranged on the side of the negative electrode metal layer 2 away from the negative electrode elastic substrate 1. The positive electrode sheet includes a positive electrode composite current collector 7 and a positive electrode active material layer 6 arranged on both sides of the positive electrode composite current collector 7.

[0079] In this embodiment, the first battery cell unit 8 and the second battery cell unit 9 are stacked, wherein the elastic substrate on the negative electrode plate of the first battery cell unit 8 and the elastic substrate on the negative electrode plate of the second battery cell unit 9 are stacked and hot-pressed to prepare a battery.

[0080] Hot pressing process Figure 2 shown.

[0081] The specific preparation process of this embodiment is as follows:

[0082] S1, preparing a negative electrode sheet;

[0083] S1.1, select an elastic material to prepare a negative electrode elastic substrate; in this embodiment, the elastic material is PET.

[0084] S1.2, a negative electrode metal layer is arranged on one side of the negative electrode elastic substrate, and then an anti-corrosion layer is arranged on the side of the negative electrode metal layer away from the elastic substrate to prepare a negative electrode composite current collector.

[0085] In this embodiment, the negative electrode metal layer is copper foil. In this embodiment, the copper foil is plated on one side of the negative electrode elastic substrate using a magnetron sputtering process.

[0086] In this embodiment, the anti-corrosion layer is a chromium layer. In this embodiment, the chromium layer is plated on the side of the copper foil away from the negative electrode elastic substrate by a magnetron sputtering process.

[0087] S1.3, disposing a negative electrode active material on the negative electrode composite current collector to prepare a negative electrode sheet;

[0088] S2, preparing a positive electrode sheet;

[0089] S2.1, selecting an elastic material to prepare a positive electrode elastic substrate; in this embodiment, the positive electrode elastic substrate is prepared using the same material as the negative electrode elastic substrate.

[0090] S2.2, coating metal aluminum foil on both sides of the elastic substrate of the positive electrode by magnetron sputtering process to prepare a positive electrode composite current collector;

[0091] S2.3, disposing a positive electrode active material on the positive electrode composite current collector to prepare a positive electrode sheet.

[0092] S3, preparing a first battery cell unit and a second battery cell unit;

[0093] Stacking the negative electrode sheet, the solid electrolyte layer, the positive electrode sheet, the solid electrolyte layer, and the negative electrode sheet in sequence, and hot pressing to form a first battery cell unit;

[0094] The preparation process of the second battery cell unit is completely consistent with the preparation process of the first battery cell unit.

[0095] In this embodiment, the solid electrolyte is a sulfide solid electrolyte layer.

[0096] One side of the active material layer on the negative electrode sheet and the positive electrode sheet is arranged toward the sulfide solid electrolyte layer.

[0097] S4, preparing the battery;

[0098] The first battery cell unit and the second battery cell unit prepared by S3 are stacked, and the elastic substrate on the negative electrode plate of the first battery cell unit and the elastic substrate on the negative electrode plate of the second battery cell unit are stacked and hot-pressed to prepare a battery.

[0099] It should be noted that this embodiment only uses two battery cell units for exemplary description. In fact, in the technical solution included in the present invention, the number of battery cell units can be more as needed.

[0100] It should be pointed out that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A battery, characterized in that: comprising at least two stacked battery cell units; The battery cell unit comprises two negative electrode sheets and a positive electrode sheet arranged between the two negative electrode sheets; The negative electrode plate includes a negative electrode composite current collector; The negative electrode composite current collector comprises an elastic substrate and a metal layer; Wherein, a metal layer is arranged on one side of the elastic substrate, and the other side of the elastic substrate is stacked with an elastic substrate in another battery cell unit.

2. The battery according to claim 1, characterized in that The negative electrode composite current collector further includes an anti-corrosion layer, and the anti-corrosion layer is arranged on a side of the metal layer away from the elastic substrate layer.

3. The battery according to claim 2, characterized in that The negative electrode plate further includes a negative electrode active material layer, and the negative electrode active material layer is arranged on a side of the anti-corrosion layer away from the metal layer.

4. The battery according to claim 3, characterized in that The negative electrode active material layer includes a negative electrode active material, a conductive agent and a binder.

5. The battery according to claim 1, characterized in that The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer arranged on both sides of the positive electrode current collector.

6. The battery according to claim 5, characterized in that The positive electrode current collector is a positive electrode composite current collector, which includes a positive electrode substrate layer and positive electrode metal layers arranged on both sides of the positive electrode substrate layer.

7. The battery according to claim 5, characterized in that The positive electrode active material layer includes a positive electrode active material, a conductive agent and a binder.

8. The battery according to claim 5, characterized in that A solid electrolyte layer is further disposed between the positive electrode active material layer and the negative electrode active material layer.

9. A method for preparing a battery, characterized in that: The steps include: S1, preparing a negative electrode sheet; S1.1, selecting an elastic material and preparing an elastic substrate; S1.2, disposing a metal layer on one side of the elastic substrate to prepare a negative electrode composite current collector; S1.3, disposing a negative electrode active material on the negative electrode composite current collector to prepare a negative electrode sheet; S2, preparing a positive electrode sheet; S3, preparing a battery cell unit; The negative electrode sheet, the solid electrolyte layer, the positive electrode sheet, the solid electrolyte layer, and the negative electrode sheet are stacked in sequence and hot pressed to form a battery cell unit; S4, preparing the battery; At least two battery cell units are stacked, and the elastic substrate on the negative electrode sheet of one battery cell unit is stacked and hot-pressed with the elastic substrate on the negative electrode sheet of another battery cell unit to prepare a battery.

10. The method according to claim 9, characterized in that In the above S1.2, an anti-corrosion layer is further provided on a side of the metal layer away from the elastic substrate.

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