A multilayer all-solid-state battery and a preparation method and application thereof

Abstract

The application provides a multilayer full solid-state battery and a preparation method and application thereof. The multilayer full solid-state battery comprises, in sequence, a positive electrode current collector, a first positive electrode layer, a second positive electrode layer, a first electrolyte layer, a second electrolyte layer, a second negative electrode layer, a first negative electrode layer and a negative electrode current collector; the first positive electrode layer, the second positive electrode layer and the first electrolyte layer independently comprise a positive electrode side electrolyte material; the first negative electrode layer, the second negative electrode layer and the second electrolyte layer independently comprise a negative electrode side electrolyte material; the first positive electrode layer and the second positive electrode layer are different in composition, and the first negative electrode layer and the second negative electrode layer are different in composition. The multilayer full solid-state battery improves the compatibility of the battery, improves the ion transmission of the electrode layer and the electrolyte layer, and improves the performance of the full solid-state battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries and relates to a multi-layer all-solid-state battery and a preparation method and application thereof. Background Art

[0002] Lithium-ion batteries have become the preferred choice for consumer electronics and new energy vehicle power batteries due to their high energy density, long cycle life, and lack of memory effect. However, the use of flammable organic solvents as electrolytes in lithium-ion batteries presents significant safety risks. With the widespread adoption of new energy vehicles, the number of spontaneous combustion incidents in these vehicles has also increased rapidly. Developing solid-state electrolytes to replace existing electrolytes and fundamentally avoiding the use of flammable organic solvents is an important approach to improving the safety of lithium-ion batteries and achieving intrinsic safety.

[0003] For example, CN 114744199A discloses an all-solid-state battery and its preparation method. The provided all-solid-state battery comprises, in order, a composite lithium anode layer, an electrolyte layer, and a composite cathode layer. The lithium anode is surface-modified with Li3N, which not only improves the interfacial stability between the metallic lithium anode and the ceramic electrolyte but also guides the uniform deposition and stripping of metallic lithium during charge and discharge, inhibiting the formation of lithium dendrites.

[0004] However, existing problems such as complex all-solid-state battery preparation processes, poor compatibility between positive and negative electrodes of solid electrolytes, and poor electron and ion transport kinetics within electrodes are still bottlenecks restricting the development and application of all-solid-state batteries.

[0005] Based on the above research, it is necessary to provide a multi-layer all-solid-state battery, which has good compatibility between the positive and negative electrodes, improves the ion transmission between the electrode and the electrolyte layer, and enhances the rate performance of the all-solid-state battery. Summary of the Invention

[0006] The purpose of the present invention is to provide a multi-layer all-solid-state battery and its preparation method and application. The multi-layer all-solid-state battery improves the electrode kinetics and the compatibility of the positive and negative electrode electrolytes by designing a multi-layer structure differentiated electrode, improves the ion transmission between the electrode and the electrolyte layer, and improves the rate performance of the all-solid-state battery.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a multilayer all-solid-state battery, comprising a positive electrode current collector, a first positive electrode layer, a second positive electrode layer, a first electrolyte layer, a second electrolyte layer, a second negative electrode layer, a first negative electrode layer, and a negative electrode current collector stacked in sequence;

[0009] The first positive electrode layer, the second positive electrode layer and the first electrolyte layer each independently include a positive electrode side electrolyte material, and the first negative electrode layer, the second negative electrode layer and the second electrolyte layer each independently include a negative electrode side electrolyte material;

[0010] The first positive electrode layer and the second positive electrode layer have different compositions, and the first negative electrode layer and the second negative electrode layer have different compositions.

[0011] The present invention designs a multi-layer structure differentiated electrode, adopts multi-layer positive electrode layers, negative electrode layers and electrolyte layers with different compositions, and adds solid electrolyte materials to both the positive electrode layer and the negative electrode layer. However, the solid electrolyte materials added to the positive electrode layer and the negative electrode layer are different. At the same time, in order to improve the internal compatibility of the battery, the electrolyte material added to the positive electrode layer is the same as the electrolyte material in the first electrolyte layer, and the electrolyte material added to the negative electrode layer is the same as the electrolyte material in the second electrolyte layer. This solves the compatibility problem of all-solid-state batteries, improves the ion transmission between the electrodes and the electrolyte layer, and improves the rate performance of the all-solid-state battery.

[0012] Preferably, the thickness ratio of the first positive electrode layer to the second positive electrode layer, and the thickness ratio of the first negative electrode layer to the second negative electrode layer are independently (1-3):1, for example, they can be 1:1, 2:1 or 3:1, but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0013] Since the electrode layers of the present invention play different roles in improving the battery's compaction density, capacity, dynamic performance, cycle performance and other aspects of performance, the thicknesses of different electrode layers preferably adopt the above ratio.

[0014] Preferably, the thickness ratio of the first electrolyte layer to the second electrolyte layer is (0.5-2):1, for example, it can be 0.5:1, 1:1, 1.5:1 or 2:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] The first electrolyte layer and the second electrolyte layer of the present invention play a role in improving compatibility, and the thickness ratio of the first electrolyte layer and the second electrolyte layer is preferably within the above range.

[0016] Preferably, the thickness of the first electrolyte layer is 7-15 μm, for example, it can be 7 μm, 9 μm, 12 μm or 15 μm, and the thickness of the second electrolyte layer is 7-15 μm, for example, it can be 7 μm, 9 μm, 12 μm or 15 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, the content of the positive electrode side electrolyte material in the second positive electrode layer is higher than the content of the positive electrode side electrolyte material in the first positive electrode layer.

[0018] In the second positive electrode layer close to the first electrolyte layer, the electrolyte material content is greater than that of the first positive electrode layer, which can improve the ion transport capacity of the electrode and improve the rate performance of the electrode.

[0019] Preferably, the positive electrode side electrolyte material content in the second positive electrode layer is 5-25wt%, for example, it can be 10wt%, 15wt%, 20wt% or 25wt%, but is not limited to the listed values, and other unlisted values within the value range are also applicable.

[0020] Preferably, the positive electrode side electrolyte material content in the first positive electrode layer is 1-12wt%, for example, it can be 3wt%, 5wt%, 7wt%, 9wt% or 11wt%, but is not limited to the listed values, and other unlisted values within the value range are also applicable.

[0021] The electrolyte material used in the present application is all inorganic solid-state electrolyte material.

[0022] Preferably, the positive electrode side electrolyte material includes halide electrolyte and / or sulfide electrolyte.

[0023] Preferably, the halide electrolyte used in the positive electrode side electrolyte material is preferably Li3MB6, M is any one or a combination of at least two of Y, Zr, In, Sc, Ta or La, B is selected from any one or a combination of at least two of Cl, Br or I, and the sulfide electrolyte used in the positive electrode side electrolyte material includes Li 10 GeP2S 12 and the same structure of element doped material.

[0024] Preferably, the positive electrode active material content in the second positive electrode layer is less than that in the first positive electrode layer.

[0025] The positive electrode active material content in the second positive electrode layer of the present application is less than that in the first positive electrode layer, which ensures the content of electrolyte material therein; the negative side is the same.

[0026] Preferably, the positive electrode active material in the second positive electrode layer includes single crystal material or secondary particle material of nickel-cobalt-manganese lithium ternary positive electrode material and / or nickel-cobalt-manganese-aluminum quaternary positive electrode material (single crystal material is selected for long cycle life battery, secondary particle material is selected for high power battery).

[0027] Preferably, the positive electrode active material content in the second positive electrode layer is 70-90wt%, for example, it can be 70wt%, 80wt% or 90wt%, but is not limited to the listed values, and other unlisted values within the value range are also applicable.

[0028] Preferably, the positive electrode active material in the first positive electrode layer includes any one or a combination of at least two of a lithium cobalt manganese oxide ternary positive electrode material, a nickel cobalt manganese aluminum quaternary positive electrode material or a lithium-rich manganese-based positive electrode material, with a content of 85-95wt%, for example, it can be 87wt%, 90wt%, 92wt% or 95wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, the morphology of the positive electrode active material in the first positive electrode layer includes single crystal particles and secondary particles, which is a composite material of single crystal particles and secondary particles of any one or a combination of at least two of lithium cobalt manganese oxide ternary positive electrode materials, nickel cobalt manganese aluminum quaternary positive electrode materials or lithium-rich manganese-based positive electrode materials.

[0030] The first and second electrode layers of the present invention use different active materials and formulations. The first electrode layer close to the current collector side uses an electrode active material with low cost, high compaction density and high capacity, and the second electrode layer close to the electrolyte layer uses an electrode active material with good kinetics and long cycle life, so as to achieve a comprehensive improvement in the compatibility of battery cost, life and power performance.

[0031] Preferably, the binder content in the second positive electrode layer is less than the binder content in the first positive electrode layer.

[0032] Preferably, the binder content in the second positive electrode layer is 0.5-2wt%, for example, it can be 0.5wt%, 1wt%, 1.5wt% or 2wt%, and the binder content in the first positive electrode layer is 1-3wt%, for example, it can be 1.5wt%, 2wt%, 2.5wt% or 3wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] Preferably, the content of the conductive agent in the second positive electrode layer is less than that in the first positive electrode layer.

[0034] Preferably, the conductive agent content in the second positive electrode layer is 0-1wt%, for example, it can be 0wt%, 0.1wt%, 0.5wt% or 1wt%, and the conductive agent content in the first positive electrode layer is 0.5-3wt%, for example, it can be 1wt%, 2wt% or 3wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0035] Preferably, the content of the negative electrode side electrolyte material in the second negative electrode layer is higher than the content of the negative electrode side electrolyte material in the first negative electrode layer.

[0036] Preferably, the negative electrode side electrolyte material content in the second negative electrode layer is 2-30wt%, for example, it can be 5wt%, 10wt%, 20wt% or 30wt%, and the negative electrode side electrolyte material content in the first negative electrode layer is 0-25wt%, but does not include 0wt%, for example, it can be 5wt%, 10wt%, 20wt% or 25wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] Preferably, the negative electrode side electrolyte material includes a sulfide electrolyte.

[0038] The negative electrode electrolyte material of the present invention is selected from Li (6-x) PS (5-x) X (1+x) (X=Cl, Br, I, 0≤x≤0.6, for example, it can be 0, 0.4 or 0.6), xLi2S·(1-x)P2S5 (0.2≤x≤0.8, for example, it can be 0.2, 0.3 or 0.5) sulfide electrolyte or Li3PS4, any one or a combination of at least two.

[0039] Preferably, the content of the negative electrode active material in the second negative electrode layer is less than that in the first negative electrode layer.

[0040] Preferably, the negative electrode active material in the second negative electrode layer includes any one of high-power artificial graphite, long cycle life artificial graphite, soft carbon or hard carbon, or a combination of at least two of them, with a content of 60-90wt%, for example, 70wt%, 80wt% or 90wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] Preferably, the negative electrode active material in the first negative electrode layer includes any one or a combination of at least two of artificial graphite, natural graphite, silicon oxide material or silicon carbon material, with a content of 70-95wt%, for example, it can be 80wt%, 85wt%, 90wt% or 95wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] Preferably, the binder content in the second negative electrode layer is 0.5-2wt%, for example, it can be 0.5wt%, 1wt%, 1.5wt% or 2wt%, the binder content in the first negative electrode layer is 1-3wt%, for example, it can be 1.5wt%, 2wt%, 2.5wt% or 3wt%, and the binder content in the second negative electrode layer is less than the binder content in the first negative electrode layer.

[0043] Preferably, the conductive agent content in the second negative electrode layer is 0-1wt%, for example, it can be 0wt%, 0.1wt%, 0.5wt% or 1wt%, and the conductive agent content in the first negative electrode layer is 0.5-3wt%, for example, it can be 1wt%, 2wt% or 3wt%, and the conductive agent content in the second negative electrode layer is less than the conductive agent content in the first negative electrode layer.

[0044] Preferably, the first electrolyte layer and the second electrolyte layer each independently further comprise a binder in an amount of 0.5-5 wt%, for example, 1 wt%, 3 wt% or 5 wt%, but not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0045] Preferably, the content of the positive electrode side electrolyte material in the first electrolyte layer and the content of the negative electrode side electrolyte material in the second electrolyte layer are independently 95-99.5wt%, for example, they can be 96wt%, 98wt%, 99wt% or 99.5wt%, but are not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] The binders used in the first positive electrode layer, the second positive electrode layer, the first electrolyte layer, the second electrolyte layer, the first negative electrode layer and the second negative electrode layer of the present invention independently include any one of polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), styrene-butadiene rubber (SBR), nitrile rubber (NBR) or hydrogenated nitrile rubber (HNBR) or a combination of at least two thereof, and the conductive agents independently include any one of SP (conductive carbon black), CNT (carbon nanotube) or VGCF (vapor-grown carbon fiber) or a combination of at least two thereof.

[0047] In a second aspect, the present invention provides a method for preparing a multilayer all-solid-state battery as described in the first aspect, the preparation method comprising the following steps:

[0048] (1) coating a first positive electrode layer mixed material, a second positive electrode layer mixed material, and a first electrolyte layer mixed material on the surface of a positive electrode current collector to obtain a positive electrode;

[0049] (2) coating a first negative electrode layer mixed material, a second negative electrode layer mixed material, and a second electrolyte layer mixed material on the surface of the negative electrode current collector to obtain a negative electrode;

[0050] (3) assembling the positive electrode of step (1) and the negative electrode stack of step (2) to obtain the multilayer all-solid-state battery;

[0051] Steps (1) and (2) are performed in no particular order.

[0052] The present invention utilizes integrated three-layer coating technology to realize the integrated molding and manufacturing of the multi-layer structure of all-solid-state batteries, greatly simplifying the production process of all-solid-state batteries and facilitating the mass production of all-solid-state batteries. It utilizes the mutual diffusion during the coating process of the electrolyte layer and the electrode layer to improve the ion transmission between the electrode and the electrolyte layer, thereby enhancing the rate performance of the all-solid-state battery.

[0053] The solvent used in the preparation of the mixed material by the preparation method of the present invention is selected from any one of NMP (N-methylpyrrolidone), toluene, xylene, trimethylbenzene, n-pentane, n-hexane, n-heptane or n-octane, or a combination of at least two thereof.

[0054] In a third aspect, the present invention provides an electronic device comprising the multi-layer all-solid-state battery as described in the first aspect.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The present invention improves electrode kinetics by designing a differentiated electrode formula with a multi-layer structure, uses electrolyte materials that match the electrolyte layer in the electrode layer, and the electrolyte material added to the positive electrode layer is the same as the electrolyte material in the first electrolyte layer, and the electrolyte material added to the negative electrode layer is the same as the electrolyte material in the second electrolyte layer, thereby achieving compatibility of the electrolyte materials; at the same time, the present invention utilizes an integrated three-layer coating technology, on the one hand, to achieve integrated molding and manufacturing of the multi-layer structure of the all-solid-state battery, greatly simplifying the production process of the all-solid-state battery and facilitating the mass production of the all-solid-state battery; on the other hand, by utilizing the mutual diffusion during the coating process of the electrolyte layer and the electrode layer, the ion transmission between the electrode and the electrolyte layer is improved, thereby improving the rate performance of the all-solid-state battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a schematic structural diagram of the multi-layer all-solid-state battery according to Example 1 of the present invention;

[0058] 1-positive electrode current collector, 2-first positive electrode layer, 3-second positive electrode layer, 4-first electrolyte layer, 5-second electrolyte layer, 6-second negative electrode layer, 7-first negative electrode layer, 8-negative electrode current collector. DETAILED DESCRIPTION

[0059] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0060] Example 1

[0061] This embodiment provides a Figure 1The multilayer all-solid-state battery shown includes a positive electrode current collector 1, a first positive electrode layer 2, a second positive electrode layer 3, a first electrolyte layer 4, a second electrolyte layer 5, a second negative electrode layer 6, a first negative electrode layer 7 and a negative electrode current collector 8 stacked in sequence, wherein the first positive electrode layer 2, the second positive electrode layer 3 and the first electrolyte layer 4 include the same positive electrode side electrolyte material, and the first negative electrode layer 7, the second negative electrode layer 6 and the second electrolyte layer 5 include a negative electrode side electrolyte material;

[0062] The first positive electrode layer 2 includes 90 wt% NCM811, 0.5 wt% SP, 0.25 wt% CNT, 7 wt% Li3YCl6 and 2.25 wt% PVDF, with a thickness of 70 μm;

[0063] The second positive electrode layer 3 includes 86.5 wt% NCM811, 0.2 wt% SP, 0.1 wt% CNT, 12 wt% Li3YCl6 and 1.2 wt% PVDF, with a thickness of 30 μm. The thickness ratio of the first positive electrode layer 2 to the second positive electrode layer 3 is 2.33:1;

[0064] The first electrolyte layer 4 comprises 99 wt% of Li3YCl6 and 1 wt% of PVDF, and has a thickness of 10 μm;

[0065] The first negative electrode layer 7 comprises 85 wt% of artificial graphite, 1 wt% of SP, 12 wt% of Li3PS4 and 2 wt% of NBR, and has a thickness of 80 μm;

[0066] The second negative electrode layer 6 includes 81.5 wt% of artificial graphite, 0.5 wt% of SP, 17 wt% of Li3PS4 and 1 wt% of NBR, and has a thickness of 35 μm. The thickness ratio of the first negative electrode layer 7 to the second negative electrode layer 6 is 2.29:1.

[0067] The second electrolyte layer 5 comprises 99 wt% of Li3PS4 and 1 wt% of NBR, and has a thickness of 10 μm. The thickness of the first electrolyte layer 4 and the second electrolyte layer 5 is 1:1;

[0068] The method for preparing the multi-layer all-solid-state battery comprises the following steps:

[0069] (1) Add the components of the first positive electrode layer 2, the second positive electrode layer 3, and the first electrolyte layer 4 to NMP according to the formula amount and disperse them in sequence. Then, use a three-layer coating die head to coat them on the aluminum foil current collector surface in a coating machine and dry them to obtain a positive electrode;

[0070] (2) According to the formula, the components of the first negative electrode layer 7, the second negative electrode layer 6, and the second electrolyte layer 5 are sequentially added to the p-xylene solvent and uniformly dispersed. Then, they are sequentially coated on the surface of the copper foil current collector using a three-layer coating die on a coating machine and dried to obtain a negative electrode;

[0071] (3) The positive electrode described in step (1) and the negative electrode described in step (2) are die-cut to a set size, stacked in sequence, and then isostatically pressed to form a 1Ah soft-pack battery.

[0072] Example 2

[0073] This embodiment provides a multi-layer all-solid-state battery, the multi-layer all-solid-state battery comprising a positive electrode current collector, a first positive electrode layer, a second positive electrode layer, a first electrolyte layer, a second electrolyte layer, a second negative electrode layer, a first negative electrode layer, and a negative electrode current collector stacked in sequence, wherein the first positive electrode layer, the second positive electrode layer, and the first electrolyte layer comprise the same positive electrode side electrolyte material, and the first negative electrode layer, the second negative electrode layer, and the second electrolyte layer comprise a negative electrode side electrolyte material;

[0074] The first positive electrode layer includes 95wt% NCM811, 0.3wt% SP, 0.3wt% CNT, 1.4wt% Li3YCl6 and 3wt% PVDF, with a thickness of 30μm;

[0075] The second positive electrode layer includes 92 wt% NCM811, 0.25 wt% SP, 0.25 wt% CNT, 5.5 wt% Li3YCl6 and 2 wt% PVDF, with a thickness of 30 μm, and a thickness ratio of the first positive electrode layer to the second positive electrode layer is 1:1;

[0076] The first electrolyte layer comprises 95 wt% of Li3YCl6 and 5 wt% of PVDF and has a thickness of 10 μm;

[0077] The first negative electrode layer comprises 95 wt% of artificial graphite, 0.5 wt% of SP, 1.5 wt% of Li3PS4 and 3 wt% of NBR, and has a thickness of 35 μm;

[0078] The second negative electrode layer includes 93 wt% of artificial graphite, 0.25 wt% of SP, 4.75 wt% of Li3PS4 and 2 wt% of NBR, has a thickness of 35 μm, and the thickness ratio of the first negative electrode layer to the second negative electrode layer is 1:1;

[0079] The second electrolyte layer comprises 95 wt% of Li3PS4 and 5 wt% of NBR, has a thickness of 20 μm, and the thickness of the first electrolyte layer and the second electrolyte layer is 0.5:1;

[0080] The preparation method of the multi-layer all-solid-state battery comprises the following steps:

[0081] (1) According to the formula amount, respectively, the components of the first positive electrode layer, the second positive electrode layer and the first electrolyte layer are added to NMP for dispersion, and a three-layer coating die is used to coat the aluminum foil current collector surface in sequence on a coating machine and dried to obtain a positive electrode;

[0082] (2) According to the formula amount, respectively, the components of the first negative electrode layer, the second negative electrode layer and the second electrolyte layer are added to p-xylene solvent for dispersion, and a three-layer coating die is used to coat the copper foil current collector surface in sequence on a coating machine and dried to obtain a negative electrode;

[0083] (3) The positive electrode of step (1) and the negative electrode of step (2) are cut to a certain size and stacked in sequence to form a 1Ah soft package battery by isostatic pressing.

[0084] Example 3

[0085] The embodiment provides a multi-layer all-solid-state battery, which comprises a positive electrode current collector, a first positive electrode layer, a second positive electrode layer, a first electrolyte layer, a second electrolyte layer, a second negative electrode layer, a first negative electrode layer and a negative electrode current collector which are sequentially stacked, wherein the first positive electrode layer, the second positive electrode layer and the first electrolyte layer comprise the same positive electrode side electrolyte material, and the first negative electrode layer, the second negative electrode layer and the second electrolyte layer comprise the negative electrode side electrolyte material;

[0086] The first positive electrode layer comprises 85wt% of NCM811, 1wt% of SP, 1wt% of CNT, 12wt% of Li3YCl6 and 1wt% of PVDF, and the thickness is 90μm;

[0087] The second positive electrode layer comprises 74wt% of NCM811, 0.25wt% of SP, 0.25wt% of CNT, 25wt% of Li3YC l6 and 0.5wt% of PVDF, and the thickness is 30μm, and the thickness ratio of the first positive electrode layer to the second positive electrode layer is 3:1;

[0088] The first electrolyte layer comprises 99wt% of Li3YCl6 and 1wt% of PVDF, and the thickness is 20μm;

[0089] The first negative electrode layer comprises 71wt% of artificial graphite, 3wt% of SP, 25wt% of Li3PS4 and 1wt% of NBR, and the thickness is 105μm;

[0090] The second negative electrode layer includes 68 wt% artificial graphite, 1 wt% SP, 30 wt% Li3PS4 and 1 wt% NBR, has a thickness of 35 μm, and the thickness ratio of the first negative electrode layer to the second negative electrode layer is 3:1;

[0091] The second electrolyte layer comprises 99 wt% of Li3PS4 and 1 wt% of NBR, has a thickness of 10 μm, and the thickness of the first electrolyte layer and the second electrolyte layer is 2:1;

[0092] The method for preparing the multi-layer all-solid-state battery comprises the following steps:

[0093] (1) Add the components of the first positive electrode layer, the second positive electrode layer, and the first electrolyte layer to NMP according to the formula amount and disperse them in sequence, and use a three-layer coating die head to coat them on the aluminum foil current collector surface on a coating machine and dry them to obtain a positive electrode;

[0094] (2) adding the components of the first negative electrode layer, the second negative electrode layer, and the second electrolyte layer to a p-xylene solvent in order according to the formula amount and dispersing them uniformly, and then coating them in order on the surface of the copper foil current collector using a three-layer coating die on a coating machine and drying them to obtain a negative electrode;

[0095] (3) The positive electrode described in step (1) and the negative electrode described in step (2) are die-cut to a set size, stacked in sequence, and then isostatically pressed to form a 1Ah soft-pack battery.

[0096] Example 4

[0097] This embodiment provides a multi-layer all-solid-state battery, which is the same as Example 1 except that the first positive electrode layer includes 86.5wt% NCM811, 0.2wt% SP, 0.1wt% CNT, 12wt% Li3YCl6 and 1.2wt% PVDF, and the second positive electrode layer includes 90wt% NCM811, 0.5wt% SP, 0.25wt% CNT, 7wt% Li3YCl6 and 2.25wt% PVDF.

[0098] Example 5

[0099] This embodiment provides a multi-layer all-solid-state battery, which is the same as Example 1 except that the first negative electrode layer includes 81.5wt% artificial graphite, 0.5wt% SP, 17wt% Li3PS4 and 1wt% NBR, and the second negative electrode layer includes 85wt% artificial graphite, 1wt% SP, 12wt% Li3PS4 and 2wt% NBR.

[0100] Comparative Example 1

[0101] This comparative example provides a multi-layer all-solid-state battery, the multi-layer all-solid-state battery comprising a positive electrode current collector, a positive electrode layer, an electrolyte layer, a negative electrode layer and a negative electrode current collector stacked in sequence;

[0102] The positive electrode layer includes 90wt% NCM811, 0.5wt% SP, 0.25wt% CNT, 7wt% Li3YCl6 and 2.25wt% NBR, with a thickness of 95μm;

[0103] The negative electrode layer includes 85 wt% of artificial graphite, 1 wt% of SP, 12 wt% of Li3PS4 and 2 wt% of NBR, and has a thickness of 105 μm;

[0104] The electrolyte layer comprises 99 wt% of Li3PS4 and 1 wt% of PTFE, and has a thickness of 20 μm;

[0105] The preparation method of the all-solid-state battery comprises the following steps:

[0106] According to the formula, the components of the positive electrode layer, the negative electrode layer and the electrolyte layer are uniformly dispersed in a toluene solution to form a uniform mixed material, which is then coated on the surface of aluminum foil, copper foil and PET film in sequence and dried to form the positive electrode, negative electrode and electrolyte membranes;

[0107] The above positive electrode, electrolyte membrane and negative electrode are cut into the designed size, stacked and packaged in soft packs, and then isostatically pressed to form a 1Ah soft pack battery.

[0108] Comparative Example 2

[0109] This comparative example provides an all-solid-state battery, which is the same as Example 1 except that the first positive electrode layer of equal thickness is replaced by a second positive electrode layer, the first negative electrode layer of equal thickness is replaced by a second negative electrode layer, and the first electrolyte layer of equal thickness is replaced by a second electrolyte layer.

[0110] Comparative Example 3

[0111] This comparative example provides an all-solid-state battery, which is the same as Example 1 except that the mass of Li3YCl6 in the first electrolyte layer is replaced by Li3PS4, and the mass of Li3PS4 in the second electrolyte layer is replaced by Li3YCl6.

[0112] The all-solid-state batteries provided in the above embodiments and comparative examples were subjected to electrochemical performance tests, and the first efficiency test was: 0.2C discharge capacity divided by 0.05C first charge capacity;

[0113] 1C capacity retention rate: 1C rate discharge capacity divided by 0.2C rate discharge capacity;

[0114] Room temperature cycle life: the number of cycles of 0.5C charge and discharge until the capacity retention rate reaches 80%.

[0115] The test results are shown in Table 1:

[0116] Table 1

[0117]

[0118] From Table 1 we can see that:

[0119] It can be seen from Example 1 and Comparative Examples 1-2 that the present invention can improve battery performance through a multi-layer design. The positive electrode layer of Comparative Example 1 is only the first positive electrode layer, the negative electrode layer is only the first negative electrode layer, and the electrolyte layer is only the second electrolyte layer. The positive electrode layer of Comparative Example 2 is only the second positive electrode layer, the negative electrode layer is only the second negative electrode layer, and the electrolyte layer is only the first electrolyte layer. The performance of the obtained all-solid-state batteries is not as good as that of Example 1; It can be seen from Example 1 and Comparative Example 3 that the electrolyte materials in the first electrolyte layer and the second electrolyte layer of the present invention must be matched with the positive electrode side and the negative electrode side, otherwise the internal compatibility of the battery will be reduced, thereby reducing the performance of the all-solid-state battery; It can be seen from Example 1 and Examples 4-5 that the different layers of the present invention are located in different positions and have different compositions. If the compositions of the first positive electrode layer and the second positive electrode layer are interchanged, or the compositions of the first negative electrode layer and the second negative electrode layer are interchanged, it will also affect the performance of the battery.

[0120] In summary, the present invention provides a multi-layer all-solid-state battery and its preparation method and application. The multi-layer all-solid-state battery improves the electrode kinetics and the compatibility of the positive and negative electrode electrolytes by designing a multi-layer structure differentiated electrode, improves the ion transmission between the electrode and the electrolyte layer, and improves the rate performance of the all-solid-state battery.

[0121] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A multi-layer all-solid-state battery, characterized in that: The multilayer all-solid-state battery comprises a positive electrode current collector, a first positive electrode layer, a second positive electrode layer, a first electrolyte layer, a second electrolyte layer, a second negative electrode layer, a first negative electrode layer and a negative electrode current collector stacked in sequence; The thickness of the first electrolyte layer is 7-15 μm; the thickness of the second electrolyte layer is 7-15 μm; The first positive electrode layer, the second positive electrode layer and the first electrolyte layer each independently include a positive electrode side electrolyte material, and the first negative electrode layer, the second negative electrode layer and the second electrolyte layer each independently include a negative electrode side electrolyte material; The positive electrode side electrolyte material is Li3MB6, where M in Li3MB6 is any one of Y, Zr, In, Sc, Ta or La or a combination of at least two thereof, and B in Li3MB6 is any one of Cl, Br or I or a combination of at least two thereof; The negative electrode side electrolyte material includes Li (6-x) PS (5-x) X (1+x) , Li3PS4 or xLi2S·(1-x)P2S5 or a combination of at least two thereof, wherein Li (6-x) PS (5-x) X (1+x) X is any one of Cl, Br or I or a combination of at least two, Li (6-x) PS (5-x) X (1+x) x in xLi2S·(1-x)P2S5 satisfies 0≤x≤0.6, and x in xLi2S·(1-x)P2S5 satisfies 0.2≤x≤0.8; The positive electrode side electrolyte material content in the second positive electrode layer is higher than the positive electrode side electrolyte material content in the first positive electrode layer; the negative electrode side electrolyte material content in the second negative electrode layer is higher than the negative electrode side electrolyte material content in the first negative electrode layer; The thickness ratio of the first positive electrode layer to the second positive electrode layer, and the thickness ratio of the first negative electrode layer to the second negative electrode layer are independently (1-3):1; The first positive electrode layer and the second positive electrode layer have different compositions, and the first negative electrode layer and the second negative electrode layer have different compositions; the contents of the positive electrode active material, the binder, and the conductive agent in the second positive electrode layer are respectively less than the contents of the positive electrode active material, the binder, and the conductive agent in the first positive electrode layer; and the contents of the negative electrode active material, the binder, and the conductive agent in the second negative electrode layer are respectively less than the contents of the negative electrode active material, the binder, and the conductive agent in the first negative electrode layer; The multi-layer all-solid-state battery is prepared using an integrated three-layer coating technology.

2. The multi-layer all-solid-state battery according to claim 1, characterized in that The thickness ratio of the first electrolyte layer to the second electrolyte layer is (0.5-2):

1.

3. The multi-layer all-solid-state battery according to claim 1, characterized in that The content of the positive electrode side electrolyte material in the second positive electrode layer is 5-25 wt %.

4. The multi-layer all-solid-state battery according to claim 1, characterized in that The content of the positive electrode side electrolyte material in the first positive electrode layer is 1-12 wt %.

5. The multi-layer all-solid-state battery according to claim 1, characterized in that The positive electrode active material in the second positive electrode layer includes a nickel-cobalt-lithium manganese oxide ternary positive electrode material and / or a nickel-cobalt-manganese-aluminum quaternary positive electrode material, with a content of 70-90 wt%.

6. The multi-layer all-solid-state battery according to claim 1, characterized in that The positive electrode active material in the first positive electrode layer includes any one or a combination of at least two of a lithium cobalt manganese oxide ternary positive electrode material, a nickel cobalt manganese aluminum quaternary positive electrode material, or a lithium-rich manganese-based positive electrode material, with a content of 85-95 wt %.

7. The multi-layer all-solid-state battery according to claim 1, characterized in that The binder content in the second positive electrode layer is 0.5-2 wt %, and the binder content in the first positive electrode layer is 1-3 wt %.

8. The multi-layer all-solid-state battery according to claim 1, characterized in that The content of the conductive agent in the second positive electrode layer is 0-1 wt %, and the content of the conductive agent in the first positive electrode layer is 0.5-3 wt %.

9. The multi-layer all-solid-state battery according to claim 1, characterized in that The content of the negative electrode side electrolyte material in the second negative electrode layer is 2-30 wt %, and the content of the negative electrode side electrolyte material in the first negative electrode layer is 0-25 wt %, but excluding 0 wt %.

10. The multi-layer all-solid-state battery according to claim 1, characterized in that: The negative electrode active material in the second negative electrode layer includes any one of artificial graphite, soft carbon or hard carbon, or a combination of at least two thereof, with a content of 60-90 wt %.

11. The multi-layer all-solid-state battery according to claim 1, characterized in that: The negative electrode active material in the first negative electrode layer includes any one of artificial graphite, natural graphite, silicon-oxygen material or silicon-carbon material, or a combination of at least two thereof, with a content of 70-95 wt %.

12. The multi-layer all-solid-state battery according to claim 1, characterized in that: The binder content in the second negative electrode layer is 0.5-2 wt %, and the binder content in the first negative electrode layer is 1-3 wt %.

13. The multi-layer all-solid-state battery according to claim 1, characterized in that The content of the conductive agent in the second negative electrode layer is 0-1 wt %, and the content of the conductive agent in the first negative electrode layer is 0.5-3 wt %.

14. The multi-layer all-solid-state battery according to claim 1, characterized in that The first electrolyte layer and the second electrolyte layer further independently include a binder.

15. The multi-layer all-solid-state battery according to claim 1, characterized in that The content of the positive electrode side electrolyte material in the first electrolyte layer and the content of the negative electrode side electrolyte material in the second electrolyte layer are independently 95-99.5 wt %.

16. A method for preparing a multilayer all-solid-state battery according to any one of claims 1 to 15, characterized in that: The preparation method comprises the following steps: (1) coating the first positive electrode layer mixed material, the second positive electrode layer mixed material and the first electrolyte layer mixed material on the surface of the positive electrode current collector to obtain a positive electrode; (2) coating the first negative electrode layer mixed material, the second negative electrode layer mixed material and the second electrolyte layer mixed material on the surface of the negative electrode current collector to obtain a negative electrode; (3) Assembling the positive electrode described in step (1) and the negative electrode stack described in step (2) to obtain the multilayer all-solid-state battery; Steps (1) and (2) are performed in no particular order.

17. An electronic device, characterized in that: The electronic device comprises a multi-layer all-solid-state battery as described in any one of claims 1 to 15.

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