Sulfide all-solid-state battery based on mixed multi-layer electrolyte and preparation method

Abstract

The invention discloses a sulfide all-solid-state battery based on mixed multi-layer electrolyte, a preparation method and an all-solid-state lithium metal battery, the sulfide all-solid-state battery comprises a positive electrode material and a solid-state electrolyte, the solid-state electrolyte comprises a sulfide-based composite electrolyte, and the positive electrode material comprises lithium cobalt oxide, high nickel (such as NCM523, NCM622 and NCM811) and sulfide; the sulfide-based composite electrolyte material is prepared by mixing different sulfide solid electrolytes. According to the sulfide all-solid-state battery based on the mixed multilayer electrolyte and the preparation method disclosed by the invention, the problem of poor stability of a lithium metal negative electrode and a sulfide interface is relieved, meanwhile, the annular lithium metal negative electrode promotes uniform deposition of lithium, and the cycling stability of the all-solid-state lithium metal battery is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of lithium metal solid-state batteries, and in particular to a sulfide all-solid-state battery based on a mixed multilayer electrolyte and a preparation method thereof. Background Art

[0002] All-solid-state lithium metal batteries offer higher energy density and safety than liquid batteries and are considered a key area of next-generation battery technology. The key to this development lies in the use of solid-state electrolytes in place of liquid electrolytes, combined with a lithium metal anode, to achieve higher energy density. Solid-state electrolytes include oxides, polymers, sulfides, and halides. Sulfide electrolytes, however, are favored by researchers due to their exceptionally high ionic conductivity and excellent mechanical properties.

[0003] Lithium metal anode (LMA) is the key factor to achieve high energy density of all-solid-state lithium metal batteries, and its theoretical specific capacity can reach about 3860mAh g -1 , and has a low redox potential (-3.04V vs. standard hydrogen electrode). However, lithium metal anodes still face many challenges in practical applications, such as interfacial side reactions and lithium dendrite growth. These problems greatly limit the cycle stability and safety of all-solid-state batteries. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the technical problem to be solved by the present invention is the problem of lithium dendrites between the anode and the solid sulfide electrolyte penetrating the electrolyte, causing all-solid-state battery failure. The present invention provides a sulfide all-solid-state battery based on a hybrid multilayer electrolyte and a preparation method, which alleviates the problem of poor interface stability between the lithium metal anode and the sulfide. At the same time, the ring-shaped lithium metal anode promotes uniform lithium deposition, significantly improving the cycle stability of the all-solid-state lithium metal battery.

[0005] To achieve the above objectives, the present invention provides a sulfide all-solid-state battery based on a hybrid multilayer electrolyte, comprising a positive electrode, a composite solid electrolyte layer and a negative electrode;

[0006] Among them, the positive electrode, composite solid electrolyte layer and negative electrode are stacked in sequence and pressure is applied.

[0007] Furthermore, the positive electrode is configured to be a mixture of a positive electrode material and a sulfide electrolyte in a certain proportion, and the positive electrode material includes lithium cobalt oxide and high nickel.

[0008] Furthermore, the negative electrode is a ring-shaped lithium metal negative electrode.

[0009] Furthermore, the composite solid electrolyte layer is configured to be composed of a sulfide electrolyte and Li x PS5Cl 1-x(LPSC) are mixed and ground to obtain a composite sulfide solid electrolyte; wherein the sulfide electrolyte includes Li 10 GeP2S 12 (LGPS) or Li 10 SnP2S 12 (LiSnPS).

[0010] Furthermore, 90 mg of LPSC solid electrolyte powder was weighed and flattened, and then 10 mg of the composite solid electrolyte was weighed and evenly sprinkled on top of the LPSC electrolyte. 15 MPa was applied to the powder to obtain a sulfide solid electrolyte layer.

[0011] Furthermore, the positive electrode and the pressed sheet sulfide solid electrolyte are stacked and pressure is applied, and then a metal lithium negative electrode is attached to the other side and finally a certain pressure is applied to make a sulfide all-solid-state battery based on a mixed multilayer electrolyte.

[0012] Furthermore, the composite sulfide electrolyte layer is adjacent to the positive electrode layer.

[0013] Furthermore, the sulfide electrolyte particle size is 3-6 μm.

[0014] Furthermore, the annular lithium metal negative electrode is configured as a ring with an outer diameter of 7 mm and an inner diameter of 5 mm.

[0015] Furthermore, the thickness of the annular lithium metal negative electrode is set to 200 μm. In a preferred embodiment of the present invention, a method for preparing a sulfide all-solid-state battery based on a mixed multilayer electrolyte comprises the following steps:

[0016] First, materials are obtained to prepare a composite sulfide solid electrolyte, and the composite sulfide solid electrolyte is pressed into a sheet to obtain a composite sulfide solid electrolyte layer;

[0017] Then lithium cobalt oxide, high nickel and sulfide are mixed and ground in a certain proportion to make a positive electrode;

[0018] Then, lithium is made into lithium sheets, which are cut into rings to make a ring-shaped lithium metal negative electrode;

[0019] After stacking the positive electrode and the pressed sheet sulfide solid electrolyte and applying pressure, the metal lithium negative electrode is attached to the other side and finally a certain pressure is applied to make a sulfide all-solid-state battery based on a mixed multilayer electrolyte.

[0020] Furthermore, first obtain the material to prepare the composite sulfide solid electrolyte, and apply pressure to the composite sulfide solid electrolyte to form a sheet, specifically including: 10 GeP2S 12 Electrolyte or Li 10 SnP2S 12Electrolyte and Li x PS5Cl 1-x Mix and grind to obtain mixed powder;

[0021] The mixed electrolyte powder CEL and LPSC electrolyte are pressed into tablets according to a certain ratio and pressure to obtain a composite sulfide solid electrolyte.

[0022] Furthermore, the grinding time is 10-30 min.

[0023] Technical Effects

[0024] The composite solid electrolyte material provided by the present invention inhibits lithium dendrites. This is because the composite electrolyte includes a mixture of two electrolytes, LGPS and LPSC, wherein the LGPS electrolyte itself can react with lithium metal to form a Li-Ge alloy. As the LGPS electrolyte decomposes, the battery interface impedance is further increased, gradually leading to battery failure. At the same time, the LPSC electrolyte easily induces the generation of lithium dendrites, which eventually penetrate the electrolyte and connect the positive and negative electrodes, thereby causing battery failure. The composite electrolyte is located on the composite positive electrode side and is not connected to the lithium metal. When the dendrite gradually grows with electrochemistry and encounters the LPSC and LGPS composite electrolyte layer, the lithium dendrite reacts with the LGPS, blocking the growth of the lithium dendrite. The composite solid electrolyte material in a sulfide all-solid-state battery based on a mixed multilayer electrolyte provided by the present invention can also slow down interfacial side reactions, alleviate the problem of poor interfacial stability between the lithium metal negative electrode and the sulfide, and significantly improve the interfacial stability between the lithium metal negative electrode and the solid sulfide electrolyte, thereby improving the electrochemical performance of the all-solid-state lithium battery. At the same time, the annular lithium metal negative electrode promotes uniform lithium deposition, significantly improving the cycle stability of the all-solid-state lithium metal battery.

[0025] The present invention provides new ideas for the design and optimization of solid electrolyte materials, is applicable to electric vehicles, portable electronic devices and other fields, and has broad commercial prospects.

[0026] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is an NMR spectrum of a composite sulfide solid electrolyte material according to a preferred embodiment of the present invention;

[0028] Figure 2 This is a comparison chart of the charge and discharge cycles of a sulfide all-solid-state battery based on a mixed multilayer electrolyte according to a preferred embodiment of the present invention and an all-solid-state lithium battery provided in a comparative example at a current density of 1.2 mA;

[0029] Figure 3 The voltage-specific capacity curves of a sulfide all-solid-state battery based on a mixed multilayer electrolyte at a current density of 1.2 mA at the 1st, 5th, 100th, and 500th cycles are shown in FIG.

[0030] Figure 4 It is a schematic diagram of the structure of the sulfide solid-state battery of the present invention.

[0031] Figure 5 This is a comparative example of the present invention. At a current density of 1.2 mA, the voltage-specific capacity curves for the 1st, 5th, 100th and 500th cycles. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] In the following description, specific details, such as certain internal procedures and techniques, are provided for purposes of illustration and not limitation to facilitate a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

[0034] like Figure 4 As shown, the present invention provides a sulfide all-solid-state battery based on a mixed multilayer electrolyte, comprising a positive electrode, a composite solid electrolyte layer and a negative electrode;

[0035] The positive electrode, composite solid electrolyte layer, and negative electrode are stacked in sequence and pressurized. The composite solid electrolyte layer consists of two layers: the first is a 10mg layer of LPSC and LGPS mixed in a 1:1 ratio, and the second is a 90mg layer of LPSC.

[0036] The positive electrode is made of positive electrode materials, including lithium cobalt oxide, high nickel composite materials (such as NCM523, NCM622, NCM811), and sulfide electrolyte. The positive electrode active material and sulfide are mixed and ground in a mass ratio of 7:3.

[0037] The negative electrode is a ring-shaped lithium metal negative electrode.

[0038] The positive electrode material is made by mixing the positive electrode material and the sulfide electrolyte in a ratio of 7:3.

[0039] The composite solid electrolyte layer is configured to be composed of a sulfide electrolyte Li 10 GeP2S12 (LGPS) or Li 10 SnP2S 12 (LiSnPS) and Li x PS5Cl 1-x (LPSC) are mixed and ground to obtain a composite sulfide solid electrolyte. x PS5Cl 1-x The x of (LPSC) is set to 5<x<7. 10 GeP2S 12 (LGPS) or Li 10 SnP2S 12 (LiSnPS) electrolyte and Li x PS5Cl 1-x The mass ratio of (LPSC) is 1:(1-3).

[0040] The above sulfide electrolyte (Li 10 GeP2S 12 (LGPS) or Li 10 SnP2S 12 (LiSnPS) and Li x PS5Cl 1-x (LPSC)) particle size is 3-6μm.

[0041] The structure of the solid-state battery is that the positive electrode, composite solid electrolyte layer and negative electrode are arranged vertically in sequence. The composite solid electrolyte layer includes the first layer of 10 mg of LPSC and LGPS mixed in a ratio of 1:1, and the second layer is 90 mg of LPSC layers pressed in sequence.

[0042] In a preferred embodiment of the present invention, a method for preparing a sulfide all-solid-state battery based on a mixed multilayer electrolyte comprises the following steps:

[0043] Step 100: first obtain materials to prepare composite sulfide solid electrolyte, apply pressure to the composite sulfide solid electrolyte to form a sheet; specifically, Li 10 GeP2S 12 or Li 10 SnP2S 12 With Li x PS5Cl 1-x Mix and grind to obtain mixed powder; wherein the grinding time is 10-30 minutes.

[0044] The mixed electrolyte powder CEL and LPSC electrolyte are pressed into tablets according to a certain ratio and pressure to obtain a composite sulfide solid electrolyte; wherein the mass ratio of CEL to LPSC is 1:9; and the pressure is 100 MPa.

[0045] Step 200: The lithium cobalt oxide composite material and the sulfide are mixed and ground in a certain proportion to form a positive electrode; the pressure during the production of the positive electrode is set to 300 MPa;

[0046] Step 300 , lithium is then used to make lithium sheets, which are cut into rings to make a ring-shaped lithium metal negative electrode. Specifically, 200 μm of lithium is punched out using a 7 mm punch to obtain a 7 mm diameter circular sheet.

[0047] A 5 mm diameter circle was punched out in the middle of the 7 mm diameter wafer using a 5 mm d puncher to obtain a lithium metal ring; the thickness of the annular lithium metal negative electrode was set to 200 μm.

[0048] In step 400 , a positive electrode, a sheet-like composite sulfide solid electrolyte, and a ring-shaped lithium metal negative electrode are stacked in sequence and pressure is applied to form a sulfide all-solid-state battery based on a mixed multilayer electrolyte. The pressure at this time is set to 10 MPa.

[0049] Example 1

[0050] This embodiment provides a method for preparing a composite sulfide solid electrolyte, which specifically includes:

[0051] 0.5 g of LGPS and 0.5 g of LPSC were mixed and ground for 10 min to obtain a composite sulfide solid electrolyte.

[0052] Figure 1 An NMR spectrum of a composite sulfide solid electrolyte material is provided for one embodiment of the present invention, such as Figure 1 As shown, the composite material provided in this embodiment still maintains the structures of the two electrolytes themselves, and no obvious chemical reaction or phase separation occurs in the mixture.

[0053] 90mg of LPSC was placed in a mold and flattened using the mold. 10mg of composite sulfide solid electrolyte was weighed and poured on the positive electrode side. Then, a pressure of 100Mpa was applied to form it into a sheet to obtain a composite sulfide solid electrolyte layer. The lithium cobalt oxide composite material and sulfide Li x PS5Cl 1-x (LPSC) is mixed and ground in a mass ratio of 7:3, and 10 mg is weighed as a mixed positive electrode, added to the upper side of the composite electrolyte, and a pressure of 300 MPa is applied in the mold to connect the positive electrode and the composite solid electrolyte layer together; finally, a lithium sheet with a diameter of 7 mm is cut, and a lithium sheet with a diameter of 5 mm is cut off at its center, and a ring-shaped lithium metal negative electrode with an outer diameter of 7 mm and an inner diameter of 5 mm is formed, and a pressure of 10 MPa is applied to form an all-solid-state lithium metal battery. Figure 2 As shown, the red line is the long cycle diagram of 1.2mA charge and discharge of the sulfide all-solid-state battery. Figure 3As shown, the voltage-specific capacity curves of the above embodiment at the current density of 1.2 mA at the 1st, 5th, 100th and 500th cycles show that the capacity retention rate is good.

[0054] Example 2

[0055] The preparation method of the all-solid-state lithium metal battery provided in this embodiment can refer to Example 1, except that 0.3 g of LGPS and 0.7 g of LPSC are weighed and mixed and ground for 10 minutes to obtain a composite sulfide solid electrolyte.

[0056] Example 3

[0057] The preparation method of the all-solid-state lithium metal battery provided in this embodiment can refer to Example 1, except that 0.2 g of LGPS and 0.8 g of LPSC are weighed and mixed and ground for 10 minutes to obtain a composite sulfide solid electrolyte.

[0058] Example 4

[0059] The preparation method of the all-solid-state lithium metal battery provided in this embodiment can refer to Example 1, except that 0.7 g of LGPS and 0.3 g of LPSC are weighed and mixed and ground for 10 minutes to obtain a composite sulfide solid electrolyte.

[0060] Example 5

[0061] The preparation method of the all-solid-state lithium metal battery provided in this embodiment can refer to Example 1, except that 0.8 g LSnPS and 0.2 g LPSC are weighed and mixed and ground for 10 minutes to obtain a composite sulfide solid electrolyte.

[0062] Example 6

[0063] The preparation method of the all-solid-state lithium metal battery provided in this embodiment can refer to Example 1, except that 80 mg of LPSC is placed in a mold, flattened using the mold, and 20 mg of a composite sulfide solid electrolyte is weighed and poured on the positive electrode side. Subsequently, a pressure of 100 MPa is applied to form it into a sheet to obtain a composite sulfide solid electrolyte layer.

[0064] Example 7

[0065] The preparation method of the all-solid-state lithium metal battery provided in this embodiment can refer to Example 1, except that a pressure of 15 MPa is applied at the end to form the solid-state lithium metal battery.

[0066] Example 8

[0067] The preparation method of the all-solid-state lithium metal battery provided in this embodiment can refer to Example 1, except that 0.5 g of LGPS and 0.5 g of LPSC are weighed and mixed and ground for 30 minutes.

[0068] Comparative Example 1

[0069] The preparation method of the all-solid-state lithium battery provided in this comparative example can refer to Example 1, except that a sulfide solid electrolyte LPSC is used as the electrolyte layer. Figure 2 As shown, the blue line is the long cycle diagram of 1.2mA charge and discharge of the sulfide all-solid-state battery. Figure 5 For the above comparative example, at a current density of 1.2 mA, the voltage-specific capacity curves at the 1st, 5th, 100th, and 500th cycles clearly show that the battery specific capacity declines significantly as the charge and discharge proceed.

[0070] Comparative Example 2

[0071] The preparation method of the all-solid-state lithium battery provided in this comparative example can refer to Example 1, except that 90 mg of LPSC is placed in a mold, flattened using the mold, and 10 mg of LGPS sulfide solid electrolyte is weighed and poured on the positive electrode side, and then a pressure of 100 MPa is applied to form it into a sheet to obtain an electrolyte layer.

[0072] Comparative Example 3

[0073] The preparation method of the all-solid-state lithium battery provided in this comparative example can refer to Example 1, except that 20 mg of LPSC is placed in a mold, flattened with the mold, and 60 mg of LGPS sulfide solid electrolyte is weighed and poured on top, flattened with a mold, and finally 20 mg of LPSC is weighed and poured on top of LGPS, flattened with a mold, and then a pressure of 100 MPa is applied to make it into a sheet to obtain an electrolyte layer.

[0074] Comparative Example 4

[0075] The preparation method of the all-solid-state lithium battery provided in this comparative example can refer to Example 1, except that a 7mm lithium metal negative electrode is cut.

[0076] Table 1 lists and illustrates the preparation methods of the composite sulfide electrolyte materials provided in Examples 1-8 to make the differences between the composite sulfide electrolyte materials provided in Examples 1-8 more intuitive.

[0077]

[0078]

[0079] The all-solid-state lithium batteries provided in Examples 1-8 and Comparative Examples 1-4 were tested at 1C (1C = 170 mAh g -1 ) was used to perform charge and discharge cycle tests. After the cycle was completed, the specific capacity of the lithium cobalt oxide composite material and the capacity retention rate of the battery were calculated. The test results are shown in Figure 2. Figure 3 and as shown in Table 2.

[0080] Table 2 Electrochemical performance test results of all-solid-state lithium batteries provided by Examples 1-8 and Comparative Examples 1-4

[0081] <![CDATA[Specific capacity after 100 cycles (mAh g -1 )]]> Capacity retention rate Example 1 143.03 87.19％ Example 2 135.2 80.46％ Example 3 140.4 85.8％ Example 4 138.4 85.1％ Example 5 136.4 87.2％ Example 6 130.7 84.5 Example 7 137.2 79.1％ Example 8 135.9 75.0％ Comparative Example 1 74.15 64.23％ Comparative Example 2 64.83 56.18％ Comparative Example 3 10.78 11.38％ Comparative Example 4 54.8 41.55％

[0082] According to the above embodiments and comparative examples, it was found that the addition of a composite sulfide solid electrolyte on the positive electrode side greatly improved the cycle stability of the all-solid-state battery, and the self-sacrificial effect of the LGPS electrolyte hindered the penetration of lithium dendrites.

[0083] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A sulfide all-solid-state battery based on a mixed multilayer electrolyte, characterized in that: positive electrode, composite solid electrolyte layer and negative electrode; The positive electrode, the composite solid electrolyte layer and the negative electrode are stacked in sequence and pressure is applied thereto.

2. A sulfide all-solid-state battery based on a mixed multilayer electrolyte according to claim 1, characterized in that: The positive electrode is configured to be made of a positive electrode material, wherein the positive electrode material includes lithium cobalt oxide, high nickel and a sulfide electrolyte.

3. A sulfide all-solid-state battery based on a mixed multilayer electrolyte according to claim 1, characterized in that: The negative electrode is a ring-shaped lithium metal negative electrode.

4. A sulfide all-solid-state battery based on a mixed multilayer electrolyte according to claim 1, characterized in that: The composite solid electrolyte layer is configured to be composed of a sulfide electrolyte and Li x PS5Cl 1-x Mix and grind to obtain the composite sulfide solid electrolyte; the sulfide electrolyte includes Li 10 GeP2S 12 or Li 10 SnP2S 12 .

5. A sulfide all-solid-state battery based on a mixed multilayer electrolyte according to claim 4, characterized in that: The particle size of the sulfide electrolyte is 3-6 μm.

6. A sulfide all-solid-state battery based on a mixed multilayer electrolyte according to claim 3, characterized in that: The annular lithium metal negative electrode is configured as a ring with an outer diameter of 7 mm and an inner diameter of 5 mm.

7. A sulfide all-solid-state battery based on a mixed multilayer electrolyte according to claim 6, characterized in that: The thickness of the annular lithium metal negative electrode is set to 200 μm.

8. The method for preparing a sulfide all-solid-state battery based on a mixed multilayer electrolyte according to any one of claims 1 to 7, characterized in that: The following steps are involved: First, materials are obtained to prepare a composite sulfide solid electrolyte, and the composite sulfide solid electrolyte is pressed into a sheet to obtain a composite sulfide solid electrolyte layer; Then the positive electrode material and sulfide are mixed and ground in a certain proportion to make a positive electrode; Then, lithium is made into lithium sheets, which are cut into rings to make a ring-shaped lithium metal negative electrode; The positive electrode, sheet-like composite sulfide solid electrolyte and ring-shaped lithium metal negative electrode are stacked in sequence and pressure is applied to make a sulfide all-solid-state battery based on a mixed multilayer electrolyte.

9. The method for preparing a sulfide all-solid-state battery based on a mixed multilayer electrolyte according to claim 8, characterized in that: First, obtain the material to prepare the composite sulfide solid electrolyte, and apply pressure to the composite sulfide solid electrolyte to form a sheet, specifically including: 10 GeP2S 12 Electrolyte or Li 10 SnP2S 12 Electrolyte and Li x PS5Cl 1-x Mixing and grinding to obtain a mixed powder; The mixed electrolyte powder CEL and the LPSC electrolyte are pressed into tablets according to a certain ratio and pressure to obtain the composite sulfide solid electrolyte.

10. The method for preparing a sulfide all-solid-state battery based on a mixed multilayer electrolyte according to claim 9, characterized in that: The grinding time is 10-30 min.

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