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 solid-state battery also comprises a solid-state electrolyte layer arranged between the positive pole piece and the negative pole piece, the negative pole piece comprises a composite negative pole current collector and a negative pole active material layer arranged on the composite negative pole current collector, the composite negative pole current collector comprises a base material and a metal layer, and the negative pole piece further comprises an anti-corrosion layer. By adopting the sandwich structure, the effects of reducing the thickness of the composite negative electrode current collector and improving the energy density of the battery are realized, and the corrosion-resistant layer is arranged at the metal layer to prevent the sulfide solid electrolyte and the halide solid electrolyte from corroding the metal layer, so that the cycle performance of the battery is further improved.

Description

TECHNICAL FIELD

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

[0002] With the development and progress of science and technology, lithium ion battery is increasingly widely used in power, energy storage, 3C and other fields, and the market requires higher and higher energy density of lithium ion battery, among them, sulfide-based solid-state battery and halide-based solid-state battery attract widespread attention in lithium battery industry due to its high energy density, high safety and long cycle life.

[0003] Copper foil is lithium battery negative electrode current collector material, the thinner the copper foil, the more the energy density of battery improves, but the continuous thinning of copper foil also correspondingly brings the problem of safety, at the same time, copper foil as current collector is easily corroded by sulfide solid-state electrolyte and halide solid-state electrolyte, which will cause solid-state battery to fail prematurely, 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 above problems, the utility model provides a kind of solid-state battery, adopts " sandwich " structure to improve the energy density of battery, at the same time, by corrosion-proof treatment on the surface of copper foil, it can prevent copper foil from being corroded by sulfide solid-state electrolyte and halide solid-state electrolyte, effectively prolong the service life of copper foil, further improve the cycle performance of battery. The technical scheme of the utility model is implemented as follows:

[0006] A kind of solid-state battery, comprising at least one battery cell unit, the battery cell unit includes positive electrode sheet and negative electrode sheet, the battery cell unit further includes solid-state electrolyte layer arranged between the positive electrode sheet and the negative electrode sheet;

[0007] The negative electrode sheet includes composite negative electrode current collector and negative electrode active material layer arranged on the composite negative electrode current collector;

[0008] The composite negative electrode current collector includes substrate and metal layer;

[0009] The metal layer is copper foil layer, arranged on both sides of the substrate along the thickness direction of the substrate;

[0010] The negative electrode sheet further includes corrosion-resistant layer;

[0011] The corrosion-resistant layer is arranged between the composite negative electrode current collector and the negative electrode active material layer.

[0012] Preferably, the anticorrosion layer is further arranged on a side of the composite negative current collector away from the negative active material layer along a thickness direction of the composite negative current collector.

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

[0014] Preferably, the substrate is in a sheet shape and rectangular, and has a thickness of 0.5-5 microns.

[0015] 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.

[0016] Preferably, the metal layer has a thickness of 1-30 microns, and the anticorrosion layer has a thickness of 1-20 microns.

[0017] Preferably, the composite negative current collector has a thickness of 10-50 microns.

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

[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] The negative current collector in a "sandwich" structure has higher safety and energy density than a simple copper foil as a current collector, and the composite current collector with a substrate arranged in the middle and copper foils arranged on both sides has higher safety and energy density, and the anticorrosion layer arranged on the copper foils can prevent the copper foils from being corroded by sulfide solid-state electrolytes and halide solid-state electrolytes, effectively prolongs the service life of the copper foils, and further improves the cycle performance of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or prior art description will be briefly introduced below, and obviously, the drawings in the following description are only one embodiment of the present application, and those skilled in the art can obtain other drawings according to these drawings 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.

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

[0025] Figure 2 Structure diagram of the negative electrode sheet in the embodiment of the present application.

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

[0027] 1. Anti-corrosion layer;

[0028] 2. Metal layer;

[0029] 3. Base material;

[0030] 4. Negative active material layer;

[0031] 5. Positive current collector;

[0032] 6. Positive active material layer;

[0033] 7. Solid-state electrolyte layer. DETAILED DESCRIPTION

[0034] 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 protection of the present application.

[0035] 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.

[0036] In the description of the specific embodiments of the utility model, the technical terms "first", "second" and the like 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 utility model, the meaning of "a plurality of" is more than two, unless otherwise explicitly specified.

[0037] In the utility model, the "embodiment" means that the specific features, structures or characteristics described in combination with the embodiment can be included in at least one embodiment of the utility model. The phrase appears at 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 utility model can be combined with other embodiments.

[0038] In the description of the embodiments of the 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 alone, A and B together, and B alone. In addition, the character " / " in the utility model generally represents that the front and rear associated objects are in an "or" relationship.

[0039] Throughout the utility model, numerical values represent approximate measurements or limits of a range to encompass minor deviations from the given values and embodiments with approximately mentioned values and embodiments with mentioned exact values. In addition to the working examples provided at the end of the specific embodiments, all numerical values of the parameters (e.g. quantities or conditions) in the specification (including the appended claims) should be understood in all cases to be modified by the term "about", regardless of whether "about" is actually present before the numerical value. "About" indicates that some minor inaccuracy exists in the stated numerical value (to some extent close to the exact value of the value stated; approximately or reasonably close to the value stated; almost). If the inaccuracy provided by "about" is not otherwise understood in the art in this ordinary meaning, "about" as used in the 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%.

[0040] In addition, the disclosure of the range includes all values within the entire range and the disclosure of the further divided range, including the endpoints and subranges given for these ranges.

[0041] Copper foil is a commonly used negative current collector material for lithium batteries. The thinner the copper foil, the higher the energy density of the battery. However, the continuous thinning of the copper foil also brings safety problems. In addition, the copper current collector is easily corroded by sulfide solid electrolyte and halide solid electrolyte, which can cause the premature failure of the solid-state battery and cannot be directly applied to sulfide-based solid-state batteries and halide-based solid-state batteries.

[0042] To solve the above problems, the utility model discloses a kind of solid-state batteries, and the solid-state battery includes at least one battery cell unit, and the battery cell unit includes positive pole piece and negative pole piece, and the battery cell unit further includes solid electrolyte layer arranged between the positive pole piece and the negative pole piece, and the negative pole piece includes composite negative current collector and negative active material layer arranged on the composite negative current collector, and the composite negative current collector includes substrate and metal layer, and the metal layer is copper foil layer, and is arranged on both sides of the substrate along the thickness direction of the substrate, and the negative pole piece further includes corrosion-resistant layer, and the corrosion-resistant layer is arranged between the composite negative current collector and the negative active material layer.

[0043] In practical application, the negative 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 are only examples and are not limited.

[0044] In practical application, the corrosion-resistant layer material can be selected from one or more combinations of stainless steel, nickel, chromium and nickel-chromium. The corrosion-resistant layer can be deposited on the surface of the metal layer in a manner such as, but not limited to, electroplating deposition, physical vapor deposition, chemical deposition, magnetron sputtering deposition, etc. It can also be glued.

[0045] In some embodiments, the corrosion-resistant layer is also arranged on the side of the composite negative current collector away from the negative active material layer along the thickness direction of the composite negative current collector.

[0046] In some embodiments, the solid electrolyte layer includes any one or both of a sulfide solid electrolyte layer and a halide solid electrolyte layer.

[0047] 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.

[0048] In practical applications, the halide solid electrolyte in the halide solid electrolyte layer can be specifically selected from Li2ZrCl6, Li2CdCl l4 , Li2MgCl l4 , Li2Cd I4 , Li2ZnI4, Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x , wherein 0 < x < 1. The above are only examples and are not limiting.

[0049] The utility model discloses a current collector of " sandwich " structure, compared with the pure use copper foil layer as the current collector, adopt the composite current collector of the middle setting base material, two sides set copper foil layer, have higher security and energy density, and the copper foil layer is provided with the anticorrosive layer, can prevent the copper foil from being corroded by sulfide solid electrolyte and halide solid electrolyte, effectively prolongs the service life of copper foil, further enhances the cycle performance of battery, makes copper foil be used in sulfide-based solid-state battery and halide-based solid-state battery.

[0050] In some embodiments, the substrate is a sheet-shaped rectangle, and the thickness is 0.5 μm-5 μm.

[0051] In practical applications, the thickness of the substrate can be selected as 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5 μm, 2.6 μm, 2.7 μm, 2.8 μm, 2.9 μm, 3 μm, 3.1 μm, 3.2 μm, 3.3 μm, 3.4 μm, 3.5 μm, 3.6 μm, 3.7 μm, 3.8 μm, 3.9 μm, 4 μm, 4.1 μm, 4.2 μm, 4.3 μm, 4.4 μm, 4.5 μm, 4.6 μm, 4.7 μm, 4.8 μm, 4.9 μm, 5 μm. The above values are only examples and are not limiting.

[0052] In practical applications, the substrate is made of a polymer material, which includes at least one of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyimide, polyamide, polyethylene glycol, polyamide-imide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyvinyl acetate, polytetrafluoroethylene, poly methylene naphthalene, polyvinylidene fluoride, polyethylene naphthalate, polypropylene carbonate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-co-trifluorochloroethylene), silicone, vinylon, polypropylene, polyethylene, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester, polysulfone and derivatives thereof, sodium carboxymethyl cellulose, styrene butadiene rubber, fluorinated rubber, polyvinyl alcohol, and polyvinylidene fluoride. The above are only examples and are not limiting.

[0053] The mass of the polymer material of the same volume is lighter than that of the metal. By using the polymer material as the substrate, the specific gravity of the composite negative electrode current collector can be reduced without increasing the total thickness of the composite negative electrode current collector, so that the energy density of the battery is improved.

[0054] In some embodiments, the positive electrode tab includes a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer is disposed between the positive electrode current collector and the solid electrolyte layer.

[0055] In practical applications, the material of the positive electrode active material layer can be selected from any one or a combination of at least two of lithium cobaltate, lithium nickel cobalt manganese acid, lithium nickel cobalt aluminum acid, lithium manganese acid, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxide phosphate, lithium iron phosphate, lithium titanate, or lithium-rich manganese-based material. The above are all common positive electrode active materials in the art and are only examples and are not limiting.

[0056] In practical applications, the positive active material layer and the negative active material layer can each independently further 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, polyphenylene ether, or carboxymethyl cellulose, preferably polytetrafluoroethylene or polyvinyl chloride. The above are all common binders in the art, which are only examples and are not limited.

[0057] In practical applications, the positive active material layer and the negative active material layer can each independently further 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, which are only examples and are not limited.

[0058] 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.

[0059] In practical applications, the thickness of the copper foil can be specifically selected from 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm; and the thickness of the corrosion-resistant layer can be specifically selected from 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm. The above values are only examples and are not limited.

[0060] Limiting the thickness of the metal layer and the corrosion-resistant layer within the above range not only can take advantage of the high electrical conductivity, abundant resources, low cost, and good ductility of copper foil, but also can take into account the corrosion-resistant effect of the corrosion-resistant layer, and ensure that the cycle performance of the lithium battery is not affected.

[0061] In some embodiments, the thickness of the composite negative electrode current collector is 10 μm-50 μm.

[0062] In practical applications, the thickness of the composite negative electrode current collector can be selected as 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm, 50 μm. The above values are only examples and are not limited.

[0063] Limiting the thickness of the composite negative electrode current collector within the above range can balance the battery volume and capacity problems and ensure the capacity of the battery.

[0064] In some embodiments, the positive electrode tab, the negative electrode tab, and the solid-state electrolyte layer are all in a rectangular sheet structure.

[0065] In some embodiments, the cell unit is arranged in sequence with the positive electrode tab, the solid-state electrolyte layer, and the negative electrode tab.

[0066] In some embodiments, the solid-state battery further comprises a shell, and the cell unit is arranged in the shell.

[0067] The embodiments of the present application will be described in more detail by the following examples. It should be noted that the embodiments of the present application are not limited to these examples.

[0068] Example 1

[0069] In a specific embodiment 1, a solid-state battery comprises a plurality of cell units as shown in Figure 1 , each cell unit comprising a negative electrode tab, a positive electrode tab, and a solid-state electrolyte layer 7 arranged between the positive electrode tab and the negative electrode tab as shown in Figure 2 . In this embodiment, the solid-state electrolyte layer 7 is a sulfide solid-state electrolyte, the negative electrode tab comprises a composite negative electrode current collector and a negative active material layer 4 arranged on the composite negative electrode current collector, and the composite negative electrode current collector comprises a substrate 3 and a metal layer 2. The metal layer 2 is a copper foil layer arranged on both sides of the substrate 3 along the thickness direction of the substrate 3. The negative electrode tab further comprises a corrosion-resistant layer 1, which is a stainless steel layer arranged between the composite negative electrode current collector and the negative active material layer 4. The corrosion-resistant layer 1 is also arranged on the side of the composite negative electrode current collector away from the negative active material layer 4 along the thickness direction of the composite negative electrode current collector. The positive electrode tab comprises a positive electrode current collector 5 and a positive active material layer 6 arranged between the positive electrode current collector 5 and the solid-state electrolyte layer 7.

[0070] The positive electrode sheet, the negative electrode sheet and the solid-state electrolyte layer 7 are laminated to prepare a battery cell unit, and a plurality of battery cell units are sequentially stacked to prepare a solid-state battery.

[0071] In this embodiment, the preparation method of the solid-state electrolyte layer 7 is as follows: the sulfide electrolyte Li7PS6 and the binder are put into a small mixing machine for dry mixing to obtain a mixture, and the mixture is rolled on a roller press multiple times to obtain the solid-state electrolyte layer 7.

[0072] Example 2

[0073] Different from example 1, the corrosion-resistant layer 1 in example 2 is a nickel layer, and the solid-state electrolyte layer 7 is a halide solid-state electrolyte Li2ZrCl6, and other structures and the preparation method of the solid-state electrolyte in example 2 are the same as those in example 1.

[0074] Control group 1

[0075] The difference between example 1 and control group 1 is that the negative electrode sheet in control group 1 does not include a corrosion-resistant layer, and other structures and the preparation method of the sulfide solid-state electrolyte are the same as those in example 1.

[0076] Control group 2

[0077] The difference between example 2 and control group 2 is that the negative electrode sheet in control group 2 does not include a corrosion-resistant layer, and other structures and the preparation method of the halide solid-state electrolyte are the same as those in example 2.

[0078] After the preparation of the battery, a total of four groups of samples, including example 1, example 2, control group 1 and control group 2, are taken, and the number of samples in each group is 10.

[0079] The battery corrosion test of the four groups of samples is carried out respectively, and the test method is as follows:

[0080] The four groups of lithium ion batteries are charged and discharged at 1C rate for 500 cycles, and then the negative electrode sheets in each group of batteries are taken out, the negative electrode active material is washed away, and the corrosion of the negative electrode composite current collector is observed.

[0081] The test results are shown in the table:

[0082] Group Positive electrode Negative electrode Electrolyte Corrosion condition Example 1 Al foil Cu + SUS + substrate Li7PS6 No Example 2 Al foil Cu + Ni + substrate Li2ZrCl6 No Comparative Example 1 Al foil Cu + substrate Li7PS6 Yes Comparative Example 2 Al foil Cu + substrate Li2ZrCl6 Yes

[0083] According to the above experiment, the corrosion of the sulfide solid-state electrolyte and the halide solid-state electrolyte on the copper foil can be effectively prevented by adopting the corrosion-resistant coating on the surface of the copper foil layer.

[0084] It should be pointed out that the above only the preferred embodiments of the present application, and not to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application, should be included within the 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 by, The cell unit further comprises a solid electrolyte layer arranged between the positive electrode tab and the negative electrode tab; The negative electrode tab comprises a composite negative current collector and a negative active material layer arranged on the composite negative current collector; The composite negative current collector comprises a substrate and a metal layer; The metal layer is a copper foil layer arranged on both sides of the substrate along the thickness direction of the substrate; The negative electrode tab further comprises an anticorrosion layer; The anticorrosion layer is arranged between the composite negative current collector and the negative active material layer.

2. The solid-state battery of claim 1, wherein, The anticorrosion layer is also arranged on the side of the composite negative current collector away from the negative active material layer along the thickness direction of the composite negative current collector.

3. The solid-state battery of claim 1, wherein, The solid electrolyte layer comprises a laminated body of any one or both of a sulfide solid electrolyte layer and a halide solid electrolyte layer.

4. The solid-state battery of claim 1, wherein, The substrate is a sheet-shaped rectangle with a thickness of 0.5-5 µm.

5. The solid-state battery of claim 1, wherein, The positive electrode tab comprises a positive current collector and a positive active material layer arranged between the positive current collector and the solid electrolyte layer.

6. The solid-state battery of claim 1, wherein, The thickness of the metal layer is 1-30 µm, and the thickness of the anticorrosion layer is 1-20 µm.

7. The solid-state battery of claim 1, wherein, The thickness of the composite negative current collector is 10-50 µm.

8. The solid-state battery of claim 1, wherein, The positive electrode tab, the negative electrode tab, and the solid electrolyte layer are all in a rectangular sheet-shaped structure.

9. The solid-state battery of claim 1, wherein, The cell unit is arranged in a stacking sequence of the positive electrode tab, the solid electrolyte layer, and the negative electrode tab.

10. The solid-state battery of claim 1, wherein, The solid-state battery further comprises a housing, and the cell unit is arranged in the housing.

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