Solid-state battery

Abstract

The utility model relates to the technical field of batteries, and provides a solid-state battery which comprises at least one battery cell unit, the battery cell unit comprises a positive pole piece and a negative pole piece, and the battery cell unit further comprises a solid-state electrolyte layer arranged between the positive pole piece and the negative pole piece, the negative pole piece comprises a negative current collector and a negative active material layer arranged on the negative current collector, the negative current collector comprises a metal layer and an anti-corrosion layer, and the metal layer is a copper foil layer. According to the copper foil current collector, the corrosion of sulfide or halide solid electrolyte to the copper foil current collector is reduced or prevented by arranging the anti-corrosion layer at the metal layer, and feasibility is provided for application of the copper foil in sulfide-based and halide-based solid batteries.

Description

TECHNICAL FIELD

[0001] The utility model relates to lithium battery technical field, especially a kind of solid-state battery. BACKGROUND

[0002] Currently commercialized lithium ion battery is mainly liquid battery using organic electrolyte, however, due to the characteristics of traditional liquid electrolyte, such as easy volatilization, easy leakage, easy combustion, etc., there are serious safety hazards in the use of lithium battery. Compared with traditional liquid lithium ion battery, all-solid-state lithium ion battery uses solid-state electrolyte with good thermal stability and safety, and gradually becomes the development direction of next-generation commercialized lithium ion battery.

[0003] Among them, sulfide solid-state electrolyte and halide solid-state electrolyte have been widely concerned due to their high energy density, high safety and long cycle life. However, the commonly used copper foil current collector is easily corroded by sulfide solid-state electrolyte and halide solid-state electrolyte, which will cause the premature failure of solid-state battery, so it cannot be directly applied in sulfide-based solid-state battery and halide-based solid-state battery.

[0004] Therefore, the market urgently needs a technical solution to solve the above problems. UTILITY MODEL CONTENT

[0005] In order to solve the problem that copper foil cannot be directly applied in sulfide-based solid-state battery and halide-based solid-state battery, the utility model provides a solid-state battery, which is treated by corrosion prevention at the copper foil current collector to reduce or prevent the corrosion of sulfide electrolyte and halide solid-state electrolyte on the copper foil current collector, and provides the feasibility of the application of copper foil in sulfide-based solid-state battery and halide-based solid-state battery.

[0006] The technical scheme of the utility model is implemented as follows:

[0007] A solid-state battery comprises at least one cell unit, the cell unit comprises a positive electrode sheet and a negative electrode sheet, and the cell unit further comprises a solid-state electrolyte layer arranged between the positive electrode sheet and the negative electrode sheet;

[0008] The negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer arranged on the negative electrode current collector;

[0009] The negative electrode current collector comprises a metal layer and a corrosion-resistant layer;

[0010] The metal layer is a copper foil layer;

[0011] The corrosion-resistant layer is arranged on one side surface of the metal layer close to the negative electrode active material layer along the thickness direction of the metal layer.

[0012] Preferably, the anticorrosion layer is further arranged on a side surface of the metal layer away from the negative active material layer in a thickness direction of the metal layer, and the anticorrosion layer covers the metal layer.

[0013] Preferably, the solid-state electrolyte layer comprises any one or a laminate of both of a sulfide solid-state electrolyte layer and a halide solid-state electrolyte layer.

[0014] Preferably, the positive electrode tab comprises a positive current collector and a positive active material layer, and the positive active material layer is arranged between the positive current collector and the solid-state electrolyte layer.

[0015] Preferably, in a thickness direction of the positive current collector, a projected area of the positive current collector is S1, and a projected area of the positive active material layer is S2, wherein S1=S2.

[0016] Preferably, in a thickness direction of the negative current collector, a projected area of the negative current collector is S3, and a projected area of the negative active material layer is S4, wherein S3>=S4.

[0017] Preferably, a thickness of the metal layer is 1-30 microns, and a thickness of the anticorrosion layer is 1-20 microns.

[0018] Preferably, the positive electrode tab, the negative electrode tab and the solid-state electrolyte layer are all in a rectangular sheet structure.

[0019] Preferably, the cell unit is arranged in a sequence of the positive electrode tab, the solid-state electrolyte layer and the negative electrode tab.

[0020] Preferably, the solid-state battery further comprises a shell, and the cell unit is arranged in the shell.

[0021] In the technical scheme of the utility model, the anticorrosion layer is arranged on the surface of the copper foil layer and is not corroded by the sulfide solid-state electrolyte and the halide solid-state electrolyte, so that the copper foil is not corroded by the sulfide solid-state electrolyte and the halide solid-state electrolyte, the cycle performance of the solid-state battery of the sulfide electrolyte system and the halide solid-state electrolyte system is improved, and the copper foil can be applied to the solid-state battery of the sulfide solid-state electrolyte system and the halide solid-state electrolyte system as a current collector. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or the prior art, the drawings needed to be used in the embodiment or the prior art description will be briefly introduced below, and obviously, the drawings in the following description are only one embodiment of the utility model, and other drawings can be obtained by those skilled in the art without creative labor.

[0023] Wherein the same parts are denoted by the same reference numerals. It should be noted that the words "front", "back", "left", "right", "up" and "down" used in the following description refer to the directions in the drawings, and the words "bottom" and "top", "inner" and "outer" refer to the directions towards or away from the geometric center of a particular component, respectively.

[0024] Figure 1 Structure diagram of the battery cell unit in the embodiment 1 of the present application;

[0025] Figure 2 Structure diagram of the battery cell unit in the embodiment 2 of the present application.

[0026] In the above drawings, each figure number mark represents:

[0027] 1, positive electrode current collector, 2, positive electrode active material layer, 3, solid electrolyte layer, 4, negative electrode active material layer, 5, corrosion protection layer, 6, metal layer. DETAILED DESCRIPTION

[0028] The technical solutions of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0029] Unless otherwise defined, all technical and scientific terms used in the present application have the same meanings as those commonly understood by those skilled in the art to which the present application belongs; the terms used in the specific embodiments are only for the purpose of describing the specific embodiments, not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0030] In the description of the specific embodiments of the present application, 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 application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified.

[0031] The phrase "embodiment" in the present utility model means that the specific features, structures or properties described in combination with the embodiments can be included in at least one embodiment of the present utility model. The appearance of this 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 not mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present utility model can be combined with other embodiments.

[0032] In the description of the embodiments of the present utility model, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A existing alone, A and B existing together, and B existing alone. In addition, the character " / " in the present utility model generally represents that the front and rear associated objects are in an "or" relationship.

[0033] Throughout the present utility model, numerical values represent approximate measurements or limits of a range to encompass minor deviations from the given values as well as embodiments having about the mentioned values and embodiments having the mentioned exact values. Except for the working examples provided at the end of the specific embodiments, all numerical values of parameters (e.g., amounts or conditions) in the specification (including the appended claims) should be understood in all cases as being modified by the term "about", whether or not the term "about" actually appears before the numerical value. "About" indicates that some minor inaccuracy exists in the stated numerical value (is close to the exact value of the stated value to some extent; is approximately or reasonably close to the stated value; is almost). If the inaccuracy provided by "about" is not otherwise understood in the art in this ordinary meaning, "about" as used in the present utility model at least indicates the variation that can be produced by ordinary methods of measuring and using such parameters. For example, "about" can 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%.

[0034] In addition, the disclosure of a range includes all values and further partitioned range disclosures within the entire range, including the endpoints and subranges given for these ranges.

[0035] Copper foil is a commonly used current collector in lithium batteries, however, when it is applied to sulfide solid electrolyte and halide solid electrolyte systems, it will be corroded, the interface impedance of the corroded copper foil current collector will increase rapidly, and then the cycle performance of the battery will decrease.

[0036] To solve the above problems, the utility model discloses a kind of solid-state battery, the solid-state battery includes at least one battery cell unit, the battery cell unit includes positive pole sheet and negative pole sheet, the battery cell unit further includes the solid-state electrolyte layer being arranged between the positive pole sheet and the negative pole sheet, the negative pole sheet includes negative pole current collector and the negative pole active material layer being arranged on the negative pole current collector, wherein, the negative pole current collector includes metal layer and anticorrosion layer, the metal layer is copper foil layer, the anticorrosion layer is along the thickness direction of metal layer, and is arranged on the side surface of the metal layer close to the negative pole active material layer.

[0037] In practical application, the negative pole active material includes one or more combinations of artificial graphite, natural graphite, microcrystalline graphite, soft carbon, hard carbon, pure silicon, silicon carbon and silicon oxygen. The above is only an example, not limited.

[0038] In practical application, the anticorrosion layer material can select one or more combinations of stainless steel, nickel, chromium and nickel-chromium. The anticorrosion layer can be arranged on the surface of the metal layer in the form of deposition, including but not limited to electroplating deposition, physical vapor deposition, chemical deposition, magnetron sputtering deposition, etc. It can also be arranged in the form of adhesive. The above is only an example, not limited.

[0039] In some embodiments, the anticorrosion layer is also arranged on the side surface of the metal layer away from the negative pole active material layer along the thickness direction of the metal layer, and the anticorrosion layer covers the metal layer.

[0040] In some embodiments, the solid-state electrolyte layer includes any one or both of a sulfide solid-state electrolyte layer and a halide solid-state electrolyte layer.

[0041] In practical application, the solid-state electrolyte layer can be only a single-layer sulfide solid-state electrolyte layer, which can also contain other solid-state electrolytes. The solid-state electrolyte layer can also be only a single-layer halide solid-state electrolyte layer, which can also contain other solid-state electrolytes. The solid-state electrolyte layer can also be a laminated body including a sulfide solid-state electrolyte layer and a halide solid-state electrolyte layer, which can contain other solid-state electrolytes. The above is only an example, not limited.

[0042] In practical applications, the sulfide solid electrolyte in the sulfide solid electrolyte layer can be specifically selected from Li2S-P2S5, Li2S-P2S5-LiX, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-2Z m S n , Li2S-GeS2, Li2S-SiS2-Li3PO4, and Li2S-SiS2-Li p MO q wherein X is a halogen element, m, n, p, and q are positive numbers, Z is Ge, Zn, or Ga, and M is P, Si, Ge, B, Al, Ga, or In. The above are only examples and are not limiting.

[0043] In practical applications, the halide solid electrolyte in the halide solid electrolyte layer can be specifically selected from Li2ZrCl6, Li2CdCl6, Li2MgCl6, Li2CdI4, Li2ZnI4, Li3OCl, LiI, Li5ZnI4, Li3OCl l4 , Li2MgC l4 , Li2Cd I4 , Li2ZnI4, Li3OCl 1-x Br x wherein 0 < x < 1. The above are only examples and are not limiting.

[0044] The utility model discloses a copper foil surface as metal layer can be protected from the corrosion of sulfide solid electrolyte or halide solid electrolyte through the setting anticorrosive layer, guarantee the cycle performance of battery.

[0045] In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer is arranged between the positive electrode current collector and the solid electrolyte layer.

[0046] The positive electrode active material layer can be arranged only between the positive electrode current collector and the solid electrolyte layer, or can be arranged on both sides of the positive electrode current collector.

[0047] In practical applications, the positive electrode active material of the positive electrode active material layer can be selected to include any one or a combination of at least two of lithium cobaltate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminate, lithium manganate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxyphosphate, lithium iron phosphate, lithium titanate, or a lithium-rich manganese-based material. The above are all common positive electrode active materials in the art and are merely examples and are not limiting.

[0048] In practical applications, the positive electrode active material layer and the negative electrode active material layer can further independently include a binder, which includes any one or a combination of at least two of polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyvinyl chloride, polystyrene, polyformaldehyde, polycarbonate, polyamide, acrylic plastic, other polyolefins and copolymers thereof, polysulfone, polyphenyl ether, or carboxymethyl cellulose, preferably polytetrafluoroethylene or polyvinyl chloride. The above are all common binders in the art and are merely examples and are not limiting.

[0049] In practical applications, the positive electrode active material layer and the negative electrode active material layer can further independently include a conductive agent, which 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 and are merely examples and are not limiting.

[0050] In some embodiments, in the thickness direction of the positive electrode current collector, the projected area of the positive electrode current collector is S1 and the projected area of the positive electrode active material layer is S2, where S1 = S2.

[0051] In some embodiments, in the thickness direction of the negative electrode current collector, the projected area of the negative electrode current collector is S3 and the projected area of the negative electrode active material layer is S4, where S3 ≥ S4.

[0052] If the negative electrode does not have a place to accept lithium ions, lithium ions will be precipitated on the surface of the negative electrode to form lithium dendrites, which will pierce the separator and cause internal short circuit of the battery, leading to thermal runaway. Therefore, in order to avoid such situations, the orthographic projection area of the negative electrode current collector is greater than or at least equal to the orthographic projection area of the negative electrode active material layer.

[0053] In some embodiments, the thickness of the metal layer is 1 μm-30 μm and the thickness of the corrosion-resistant layer is 1 μm-20 μm.

[0054] In practical applications, the thickness of the metal layer can be specifically selected from 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, etc. 26μm, 27μm, 28μm, 29μm, 30μm; in practical applications, the specific thickness of the anti-corrosion layer can be selected as 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm. The above values ​​are for illustrative purposes only and are not limitations.

[0055] Limiting the thickness of the metal layer and the anti-corrosion layer to the above-mentioned range not only allows us to take advantage of the high conductivity, abundant resources, low cost and easy availability of copper foil, as well as its good ductility, but also ensures the anti-corrosion effect of the anti-corrosion layer, thus guaranteeing that the cycle performance of the lithium battery is not affected.

[0056] In some embodiments, the positive electrode, the negative electrode, and the solid electrolyte layer are all rectangular sheet structures.

[0057] In some embodiments, the battery cell unit is formed by stacking the positive electrode, the solid electrolyte layer, and the negative electrode in sequence.

[0058] In some embodiments, the solid-state battery further includes a housing, within which the battery cell is disposed.

[0059] The embodiments of this utility model will be described in more detail below through examples. It should be noted that the embodiments of this utility model are not limited to these examples.

[0060] Example 1

[0061] In one specific embodiment, a solid-state battery includes several such... Figure 1 The battery cell unit shown is as follows. Each battery cell unit includes a positive current collector 1, a positive active material layer 2, a solid electrolyte layer 3, a negative active material layer 4, two anti-corrosion layers 5, and a metal layer 6. The two anti-corrosion layers 5 are respectively attached to the upper and lower surfaces of the metal layer 6 to form the negative current collector. The positive current collector 1, the positive active material layer 2, the solid electrolyte layer 3, the negative active material layer 4, and the negative current collector are stacked sequentially.

[0062] In this embodiment, along the thickness direction of the positive current collector 1, the projected area of ​​the positive current collector 1 is S1, and the projected area of ​​the positive active material layer 2 is S2. Along the thickness direction of the negative current collector, the projected area of ​​the negative current collector is S3, and the projected area of ​​the negative active material layer 4 is S4. In this embodiment, S1 = S2, and S3 = S4.

[0063] In this embodiment, the solid electrolyte layer 3 is a sulfide solid electrolyte layer, the metal layer 6 is a copper foil layer, and the anti-corrosion layer 5 is a chromium layer.

[0064] The above-mentioned cell units are stacked together to prepare a lithium-ion solid-state battery.

[0065] In this embodiment, the solid electrolyte layer 3 is prepared by: placing the sulfide electrolyte Li7PS6 and the binder into a small mixer for dry mixing to obtain a mixture, and then rolling the mixture multiple times on a roller press to obtain the solid electrolyte layer 3.

[0066] Example 2

[0067] In one specific embodiment, a solid-state battery includes several such... Figure 2 The battery cell unit shown is as follows. Each battery cell unit includes a positive current collector 1, a positive active material layer 2, a solid electrolyte layer 3, a negative active material layer 4, two anti-corrosion layers 5, and a metal layer 6. The two anti-corrosion layers 5 are respectively attached to the upper and lower surfaces of the metal layer 6 to form the negative current collector. The positive current collector 1, the positive active material layer 2, the solid electrolyte layer 3, the negative active material layer 4, and the negative current collector are stacked sequentially.

[0068] In this embodiment, along the thickness direction of the positive current collector 1, the projected area of ​​the positive current collector 1 is S1, and the projected area of ​​the positive active material layer 2 is S2. Along the thickness direction of the negative current collector, the projected area of ​​the negative current collector is S3, and the projected area of ​​the negative active material layer 4 is S4. In this embodiment, S1 = S2, and S3 > S4.

[0069] In this embodiment, the solid electrolyte layer 3 is a halide solid electrolyte layer, the metal layer 6 is a copper foil layer, and the anti-corrosion layer 5 is a nickel layer.

[0070] The above-mentioned cell units are stacked together to prepare a lithium-ion solid-state battery.

[0071] In this embodiment, the solid electrolyte layer 3 is prepared by: placing the halide electrolyte Li2ZrCl6 and the binder into a small mixer for dry mixing to obtain a mixture, and then rolling the mixture multiple times on a roller press to obtain the solid electrolyte layer 3.

[0072] Control group 1

[0073] The difference from example 1 is that the negative electrode plate in control group 1 does not include an anti-corrosion layer, and other structures and the preparation method of the sulfide solid electrolyte are exactly the same as those in example 1.

[0074] Control group 2

[0075] The difference from example 2 is that the negative electrode plate in control group 2 does not include an anti-corrosion layer, and other structures and the preparation method of the halide solid electrolyte are exactly the same as those in example 2.

[0076] After the batteries are prepared, a total of four groups of samples are taken, including example 1, example 2, control group 1 and control group 2, and the number of samples in each group is 10.

[0077] The corrosion resistance of each group of samples is tested respectively.

[0078] The test process is as follows:

[0079] The samples are charged and discharged at a rate of 1C for 500 cycles, and then the negative electrode plates in each battery are taken out, the negative electrode active material is washed off, and the corrosion of the negative electrode current collector is observed. The test results are shown in the following table:

[0080] Group Positive electrode Negative electrode Electrolyte Corrosion condition Example 1 Aluminum foil Copper foil + chromium layer Li7PS6 No Example 2 Aluminum foil Copper foil + nickel layer Li2ZrCl6 No Control 1 Aluminum foil Copper foil Li7PS6 Corrosion occurred in negative electrode Control 2 Aluminum foil Copper foil Li2ZrCl6 Corrosion occurred in negative electrode

[0081] According to the above experiment, it can be known that the anti-corrosion layer coated on the surface of the copper foil can effectively prevent the corrosion of the sulfide solid electrolyte and the halide solid electrolyte.

[0082] It should be noted that the above only describes the preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1.A solid-state battery, comprising at least one cell unit, the cell unit comprising a positive electrode sheet and a negative electrode sheet, characterized in that, the cell unit further comprises a solid-state electrolyte layer arranged between the positive electrode sheet and the negative electrode sheet; the negative electrode sheet comprises a negative electrode current collector and a negative electrode active material layer arranged on the negative electrode current collector; wherein the negative electrode current collector comprises a metal layer and an anti-corrosion layer; the metal layer is a copper foil layer; the anti-corrosion layer is arranged on one side surface of the metal layer close to the negative electrode active material layer along the thickness direction of the metal layer; the anti-corrosion layer is also arranged on the other side surface of the metal layer away from the negative electrode active material layer along the thickness direction of the metal layer, and the anti-corrosion layer covers the metal layer; the solid-state electrolyte layer comprises any one or a laminated body of both of a sulfide solid-state electrolyte layer and a halide solid-state electrolyte layer; the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer, the positive electrode active material layer being arranged between the positive electrode current collector and the solid-state electrolyte layer; the projected area of the positive electrode current collector in the thickness direction of the positive electrode current collector is S1, and the projected area of the positive electrode active material layer is S2, wherein S1=S2; the projected area of the negative electrode current collector in the thickness direction of the negative electrode current collector is S3, and the projected area of the negative electrode active material layer is S4, wherein S3≧S4; the thickness of the metal layer is 1-30 μm, and the thickness of the anti-corrosion layer is 1-20 μm; the positive electrode sheet, the negative electrode sheet and the solid-state electrolyte layer are all in a rectangular sheet shape; the cell unit is arranged in a sequence of the positive electrode sheet, the solid-state electrolyte layer and the negative electrode sheet; the solid-state battery further comprises a shell, and the cell unit is arranged in the shell. ​ ​ ​ ​ ​ 2. The solid-state battery of claim 1, wherein, ​ 3. The solid-state battery of claim 1, wherein, ​ 4. The solid-state battery of claim 1, wherein, ​ 5. The solid-state battery of claim 4, wherein, ​ 6. The solid-state battery of claim 1, wherein, ​ 7. The solid-state battery of claim 1, wherein, ​ 8. The solid-state battery of claim 1, wherein, ​ 9. The solid-state battery of claim 1, wherein, ​ 10. The solid-state battery of claim 1, wherein, ​

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