All-solid-state battery with multilayer solid electrolyte

Abstract

The utility model relates to an all-solid-state battery with multiple layers of solid electrolyte. The all-solid-state battery sequentially comprises a positive electrode, a first solid electrolyte layer, a second solid electrolyte layer and a negative electrode, the first solid electrolyte layer comprises sulfide solid electrolyte or halide solid electrolyte; the second solid electrolyte layer comprises a composite solid electrolyte, and the composite solid electrolyte comprises an oxide solid electrolyte and a polymer solid electrolyte. According to the all-solid-state battery, all the solid electrolytes are matched, so that the interface between the electrode and the solid electrolytes can be stabilized, the compatibility of the interface can be improved, the rate capability can be improved, the internal resistance can be reduced, and the cycle performance can be improved, and all the performances of the all-solid-state battery can be greatly improved.

Description

Technical Field

[0001] This utility model relates to the field of solid-state batteries, and more particularly to an all-solid-state battery with a multilayer solid electrolyte. Background Technology

[0002] Lithium-ion batteries have been widely used due to their many advantages, such as high voltage and high capacity, as well as long cycle life, high open-circuit voltage, and absence of memory effect. However, traditional liquid lithium-ion batteries contain a large amount of organic electrolyte, which has disadvantages such as volatility, flammability, and explosiveness, posing significant safety hazards. Therefore, developing all-solid-state batteries by replacing liquid electrolytes is the fundamental way to solve battery safety issues. Compared to liquid electrolyte batteries, all-solid-state batteries have greater potential for improvement in energy density, wider operating temperature range, and extended lifespan. Solid-state electrolyte batteries also feature compact structure, adjustable scale, and greater design flexibility.

[0003] Compared to liquid batteries, all-solid-state batteries use polymer, oxide, sulfide, and halide systems as solid electrolytes, and separate the positive and negative electrodes in the form of thin films, thereby replacing the role of the separator. Each of these solid electrolytes has its own advantages and disadvantages. Appropriately combining multiple solid electrolytes to obtain high-performance solid-state batteries is a feasible technical route. Utility Model Content

[0004] Problems to be solved by utility models

[0005] The purpose of this invention is to provide an all-solid-state battery with a multilayer solid electrolyte, aiming to solve the problems of high impedance and poor interfacial contact in existing all-solid-state batteries. This invention combines existing solid electrolyte materials, utilizing the advantages of polymer / oxide / sulfide / halide solid electrolyte materials to compensate for their shortcomings. It designs a practical and high-performance all-solid-state battery through a multilayer solid electrolyte composite and the matching of various solid electrolytes.

[0006] Solution for solving the problem

[0007] To achieve the above objectives, the present invention may adopt the following technical solutions.

[0008] This invention provides an all-solid-state battery with multiple layers of solid electrolyte, comprising, in sequence: a positive electrode, a first solid electrolyte layer, a second solid electrolyte layer, and a negative electrode;

[0009] The first solid electrolyte layer includes a sulfide solid electrolyte or a halide solid electrolyte;

[0010] The second solid electrolyte layer includes a composite solid electrolyte, which includes an oxide solid electrolyte and a polymer solid electrolyte.

[0011] In one specific embodiment, the composite solid electrolyte further includes a lithium salt.

[0012] In one specific embodiment, the first solid electrolyte layer further includes a binder and an optional conductive agent.

[0013] In one specific embodiment, a third solid electrolyte layer is further included between the positive electrode and the first solid electrolyte layer, the third solid electrolyte layer comprising a halide solid electrolyte or a composite solid electrolyte.

[0014] In one specific embodiment, the all-solid-state battery sequentially includes: a positive electrode, a third solid electrolyte layer optionally including a composite solid electrolyte, a first solid electrolyte layer containing a halide solid electrolyte, a second solid electrolyte layer, and a negative electrode.

[0015] In one specific embodiment, the all-solid-state battery sequentially comprises: a positive electrode, a third solid electrolyte layer containing a halide solid electrolyte or a composite solid electrolyte, a first solid electrolyte layer containing a sulfide solid electrolyte, a second solid electrolyte layer, and a negative electrode.

[0016] In one specific embodiment, the thickness of the second solid electrolyte layer and the third solid electrolyte layer is 1-10 μm.

[0017] In one specific embodiment, the thickness of the first solid electrolyte layer is 10-50 μm.

[0018] In one specific embodiment, the positive electrode contains a halide solid electrolyte and / or an oxide solid electrolyte, preferably a halide solid electrolyte.

[0019] In one specific embodiment, the positive electrode includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, vanadium oxide, NaFePO4, NaMnO2, Na2FeSiO4, Na2S, Na3V2(PO4)3, and Na2FeSiO4; the negative electrode is selected from at least one of lithium metal, graphite, amorphous carbon, lithium titanate, hard carbon, Na2S, Na2S5, SnO2, Sb2O3, and SnSb.

[0020] In one specific embodiment, the halide solid electrolyte is selected from Li2ZrCl6, Li3InCl6 and their derivatives.

[0021] In one specific embodiment, the oxide solid electrolyte is selected from one or more of lithium lanthanum zirconium oxide, lithium titanium aluminum phosphate, lithium lanthanum titanate, and their derivatives; the polymer solid electrolyte is selected from one or more of polyethylene oxide, polyvinylidene fluoride, poly(vinylidene fluoride-co-hexafluoropropylene), and their derivatives.

[0022] The sulfide solid electrolyte is selected from Li 10 GeP2S 12 One or more of Li6PS5Cl and its derivatives.

[0023] Effects of the utility model

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The all-solid-state battery with multilayer solid electrolyte provided by this utility model ensures that the solid-state battery has high ionic conductivity by making the solid electrolyte layer between the positive electrode and the negative electrode a halide solid electrolyte layer or a sulfide solid electrolyte layer.

[0026] (2) By having a composite solid electrolyte on the surface of the negative electrode, side reactions between halide or sulfide solid electrolytes and metallic lithium can be prevented.

[0027] (3) When the second solid electrolyte layer is a sulfide solid electrolyte layer, a halide solid electrolyte layer or a composite solid electrolyte layer is made on the surface of the positive electrode to avoid direct contact between the sulfide and the positive electrode, thereby solving the problem that the sulfide solid electrolyte is not resistant to high voltage of the positive electrode.

[0028] (4) By combining the solid electrolytes as described above, the interface between the electrode and the solid electrolyte can be stabilized and the interface compatibility can be improved. In addition, the rate performance can be improved, the internal resistance can be reduced and the cycle performance can be improved, thereby greatly improving all the performance of the all-solid-state battery. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of a composite solid electrolyte provided in one embodiment of the present invention.

[0030] Figure 2 A schematic diagram of the structure of a composite solid electrolyte provided for another embodiment of this utility model.

[0031] Figure 3 The graph shows the results of rate performance testing of the pouch cells in the examples and comparative examples.

[0032] Figure 4 The graph shows the results of cycle performance testing of the pouch cells in the embodiments and comparative examples.

[0033] Explanation of reference numerals in the attached figures: 1-positive electrode, 2-first solid electrolyte layer, 3-negative electrode, 4-second solid electrolyte layer, 5-third solid electrolyte layer. Detailed Implementation

[0034] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the present utility model. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0035] In one embodiment of this utility model, an all-solid-state battery with multiple layers of solid electrolyte is provided, which sequentially includes: a positive electrode, a first solid electrolyte layer, a second solid electrolyte layer and a negative electrode; the first solid electrolyte layer includes a sulfide solid electrolyte or a halide solid electrolyte; the second solid electrolyte layer includes a composite solid electrolyte, which includes an oxide solid electrolyte and a polymer solid electrolyte.

[0036] In some specific embodiments, a third solid electrolyte layer is further included between the positive electrode and the first solid electrolyte layer, the third solid electrolyte layer including a halide solid electrolyte or a composite solid electrolyte.

[0037] In some specific implementations, such as Figure 1 As shown, the all-solid-state battery sequentially includes: a positive electrode 1, a first solid electrolyte layer 2 containing a halide solid electrolyte, a second solid electrolyte layer 4 containing a composite solid electrolyte, and a negative electrode 3. Since the halide solid electrolyte in the first solid electrolyte layer 2 can directly contact the positive electrode 1, a third solid electrolyte layer 5 may or may not be present on the positive electrode 1 side. Figure 1 The illustration shows an embodiment without the third solid electrolyte layer 5. In some specific embodiments, when the third solid electrolyte layer 5 is present, it may include a composite solid electrolyte. The composite solid electrolyte includes oxide solid electrolytes and polymer solid electrolytes.

[0038] In other specific implementations, such as Figure 2As shown, the all-solid-state battery sequentially includes: a positive electrode 1, a third solid electrolyte layer 5 containing a halide solid electrolyte or a composite solid electrolyte, a first solid electrolyte layer 2 containing a sulfide solid electrolyte, a second solid electrolyte layer 4 containing a composite solid electrolyte, and a negative electrode 3. In this embodiment, the third solid electrolyte layer 5 on the positive electrode 1 side can prevent the sulfide solid electrolyte in the first solid electrolyte layer 2 from directly contacting the positive electrode, thus solving the problem that the sulfide solid electrolyte is not resistant to high voltage at the positive electrode.

[0039] In this invention, the combination of the positive electrode and the third solid electrolyte layer can be called the positive electrode composite layer, and the combination of the negative electrode and the second solid electrolyte layer can be called the negative electrode composite layer.

[0040] In this invention, the first solid electrolyte layer comprises a halide solid electrolyte or a sulfide solid electrolyte, thereby ensuring that the solid-state battery has high ionic conductivity. Preferably, it comprises a sulfide solid electrolyte. Sulfide solid electrolytes have the advantages of ultra-high ionic conductivity, high interface flexibility, and high voltage resistance. Halide solid electrolytes also have the advantages of high voltage resistance, high ionic conductivity, and flexible interface, but their ionic conductivity is lower than that of sulfide solid electrolytes. Therefore, the first solid electrolyte layer more preferably comprises a sulfide solid electrolyte.

[0041] The second solid electrolyte layer on the negative electrode side comprises a composite solid electrolyte, which includes an oxide solid electrolyte and a polymer solid electrolyte. The composite solid electrolyte possesses advantages such as high stability, high interfacial flexibility, and resistance to lithium metal reduction, preventing side reactions between the halide or sulfide solid electrolyte and metallic lithium. Furthermore, based on the excellent flexibility and processing properties of polymers, good interfacial contact and ionic conductivity between the halide or sulfide solid electrolyte and the negative electrode can be achieved. Therefore, using the composite solid electrolyte layer of this invention, high ionic conductivity at room temperature, along with good interfacial contact and electrochemical stability, enables the fabrication of high-performance all-solid-state batteries.

[0042] In some specific embodiments, as described above, the first solid electrolyte layer contains a sulfide solid electrolyte, in which case a third solid electrolyte layer is required. The third solid electrolyte layer contains a halide solid electrolyte or a composite solid electrolyte, preferably a halide solid electrolyte. Halide electrolytes have the advantages of high ionic conductivity, high interfacial flexibility, and high voltage resistance. Composite solid electrolytes have the advantages of high voltage resistance, high ionic conductivity, and a flexible interface, but their ionic conductivity and interfacial flexibility are inferior to those of halide solid electrolytes; therefore, the presence of a halide solid electrolyte is more preferred. It should be noted that when the first solid electrolyte layer contains a composite solid electrolyte, this composite solid electrolyte may be the same as or different from the composite solid electrolyte in the second solid electrolyte layer.

[0043] In this invention, by combining the various solid electrolytes as described above, the interface between the electrode and the solid electrolyte can be stabilized and the interface compatibility can be improved. At the same time, the rate performance can be improved, the internal resistance can be reduced, and the cycle performance can be improved, thereby greatly improving all the performance of the all-solid-state battery.

[0044] In some specific embodiments, the aforementioned sulfide solid electrolyte can be selected from Li 10 GeP2S 12 One or more of (LGPS), Li6PS5Cl(LPSC)-based sulfides and their derivatives. The above-mentioned halide electrolytes may be selected from one or more of Li2ZrCl6, Li3InCl6-based halides and their derivatives.

[0045] The oxide solid electrolyte in the aforementioned composite solid electrolyte can be selected from one or more oxides and their derivatives, such as lithium lanthanum zirconium oxide (LLZO), lithium titanium aluminum phosphate (LATP), and lithium lanthanum titanate (LLTO). The polymer solid electrolyte in the aforementioned composite solid electrolyte can be selected from one or more polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), and their derivatives.

[0046] In some embodiments, the first solid electrolyte layer further includes a binder and optionally a conductive agent. When the first solid electrolyte layer contains a halide solid electrolyte, the first solid electrolyte layer may include a conductive agent; when the first solid electrolyte layer contains a sulfide solid electrolyte, the first solid electrolyte layer does not include a conductive agent. In some embodiments, the composite solid electrolyte also includes a lithium salt.

[0047] Furthermore, the first solid electrolyte layer may contain a binder at a weight of 0.1-3% by weight relative to the total weight of the first solid electrolyte layer. If a conductive agent is included, the content of the conductive agent may be 0.1-3% by weight relative to the total weight of the first solid electrolyte layer. The aforementioned composite solid electrolyte may contain a lithium salt at a weight of 0.1-10% by weight relative to the total weight of the composite solid electrolyte.

[0048] By incorporating conductive agents and lithium salts into different solid electrolyte layers between the positive and negative electrodes (conductive agents are added to the electrolyte layer on the positive electrode side, and lithium salts are added to the composite solid electrolyte), the conduction of electrons and ions can be enhanced. Specifically, the conductive agent provides an electron transport channel for the first solid electrolyte layer, thereby improving the electronic conductivity of the electrode and further enhancing the electrochemical performance of the all-solid-state battery.

[0049] In this invention, the conductive agent can be selected from one or more of graphene, carbon nanotubes, conductive carbon black SP, and conductive graphite KS-6. The binder can be selected from one or more of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium carboxymethyl cellulose, styrene-butadiene rubber, styrene-butadiene-styrene copolymer, and polyacrylic acid. The lithium salt in the composite solid electrolyte layer can be selected from one or more of LiPF6, LiBF4, LiTFSI, LiFSI, lithium borate complexes, and lithium phosphate complexes.

[0050] In some specific embodiments, the positive electrode can be a lithium battery positive electrode, a sodium battery positive electrode, etc. The active material particles in the positive electrode can be selected from at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, vanadium oxide, NaFePO4, NaMnO2, Na2FeSiO4, Na2S, Na3V2(PO4)3, and Na2FeSiO4. The positive electrode may also contain an oxide solid electrolyte or a halide solid electrolyte, preferably a halide solid electrolyte.

[0051] In some specific embodiments, the negative electrode can be a lithium-ion battery negative electrode, a sodium-ion battery negative electrode, etc. The active material particles in the negative electrode can be selected from at least one of lithium metal, graphite, amorphous carbon, lithium titanate, hard carbon, Na2S, Na2S5, SnO2, Sb2O3, and SnSb. Using the aforementioned negative electrode active material, a complete charge-discharge system can be formed with the positive electrode and the composite solid electrolyte layer, exhibiting excellent electrochemical performance.

[0052] In this invention, the third solid electrolyte layer can be formed on the surface of the positive electrode by wet coating or dry pressing. The second solid electrolyte layer can be formed on the surface of the negative electrode by wet coating or dry pressing. The first solid electrolyte layer can be formed on the surface of the second solid electrolyte layer by wet coating or dry pressing.

[0053] Furthermore, the thickness of the second and third solid electrolyte layers can both be 1-10 μm, for example, 1 μm, 2 μm, 5 μm, 8 μm, 10 μm, etc. The thickness of the first solid electrolyte layer can be 10-50 μm, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, etc.

[0054] The all-solid-state battery of this invention has a solid electrolyte layer on the surface of both the positive and negative electrodes. This layer can stabilize the interface between the electrode and the halide or sulfide solid electrolyte, improve the interface compatibility, thereby improving rate performance, reducing internal resistance, and improving cycle performance. All the performance characteristics of the all-solid-state battery are greatly improved.

[0055] Furthermore, by combining the positive electrode composite layer, the negative electrode composite layer, and the second solid electrolyte layer (which serves as a solid electrolyte membrane) to form a battery cell, a composite electrolyte all-solid-state battery cell is created. The advantages of this all-solid-state battery cell design include: suitability for lithium-ion and sodium-ion battery systems; tight bonding between the positive electrode, negative electrode, and solid electrolyte layer; and high ionic conductivity and low electronic conductivity, resulting in significant improvements in all aspects of the all-solid-state battery's performance.

[0056] Example

[0057] The embodiments of this utility model will be described in detail below with reference to the examples. However, those skilled in the art will understand that the following examples are only for illustrating this utility model and should not be regarded as limiting the scope of this utility model. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0058] The positive electrode material NCM811, the halide solid electrolyte Li3InCl6, the conductive agent carbon black SP, and the binder polyvinylidene fluoride PVDF were homogenized in N-methylpyrrolidone (NMP) in a weight ratio of 79:1:10:10, coated, dried, and then rolled and cut to form the positive electrode.

[0059] Using Li-Cu composite lithium foil as the negative electrode, the oxide solid electrolyte LLZO and polymer solid electrolyte PVDF with a mass ratio of 1:4 were stirred evenly in the solvent DMF, coated onto the surface of the composite lithium foil, and dried to form a composite solid electrolyte film with a thickness of 5μm, which was then cut into a negative electrode composite layer.

[0060] 10g of halide solid electrolyte Li3InCl6 and 10g of sulfide solid electrolyte Li6PS5Cl were prepared by dry film preparation and cut into corresponding solid electrolyte films. The thickness of the halide solid electrolyte film and the sulfide solid electrolyte film were both 35μm.

[0061] Then, the positive electrode, halide solid electrolyte membrane, and sulfide solid electrolyte membrane were stacked sequentially and pressed under 400 MPa using an isostatic press to assemble them with the negative electrode composite layer into a pouch cell. Electrochemical performance tests were then conducted by applying a pressure of 10 MPa.

[0062] Comparative Example

[0063] The positive electrode material NCM811, conductive agent carbon black SP, and binder polyvinylidene fluoride PVDF are homogenized in N-methylpyrrolidone (NMP) in a weight ratio of 80:10:10, coated, dried, and then rolled and cut to form the positive electrode.

[0064] Li-Cu composite lithium foil was used as the negative electrode.

[0065] 10g of sulfide solid electrolyte Li6PS5Cl was prepared by dry film preparation and then cut into corresponding solid electrolyte films. The thickness of the sulfide solid electrolyte film was 35μm.

[0066] Then, the positive electrode and the sulfide solid electrolyte membrane were stacked sequentially, pressed under 400 MPa using an isostatic press, and assembled with the negative electrode to form a pouch cell. Electrochemical performance was then tested by applying a pressure of 10 MPa.

[0067] Rate and cycle performance tests were conducted on the pouch cells of the embodiments and comparative examples, and the results are as follows: Figure 3 and Figure 4 As shown.

[0068] pass Figure 3 and Figure 4 The cell performance data shown demonstrates that the all-solid-state battery assembled with a multi-layer composite solid-state electrolyte in the embodiment exhibits significant improvements in both rate performance and cycle performance compared to the all-solid-state battery assembled with a single solid-state electrolyte in the comparative example. Specifically, as... Figure 3 As shown, the all-solid-state battery assembled with a multilayer composite solid-state electrolyte in the embodiment retains 95%, 90%, and 74% of its capacity at 0.5C, 1.0C, and 2.0C rates, respectively, while the all-solid-state battery assembled with a single solid-state electrolyte in the comparative example retains only 90%, 73%, and 51% of its capacity at 0.5C, 1.0C, and 2.0C rates, respectively. Figure 4 As shown, after 100 cycles, the capacity retention rate of the all-solid-state battery assembled with the multilayer composite solid-state electrolyte in the embodiment is 86%, while the capacity retention rate of the all-solid-state battery assembled with the single solid-state electrolyte in the comparative embodiment is only 79%. This proves that the multilayer composite solid-state electrolyte can effectively reduce the cell interface resistance, stabilize the material and interface structure, and thus improve the cell rate performance and cycle performance compared with the single solid-state electrolyte.

[0069] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A full solid-state battery having a multilayer solid electrolyte, characterized by comprises a halide solid electrolyte or a composite solid electrolyte. The second solid electrolyte layer comprises a composite solid electrolyte comprising an oxide solid electrolyte and a polymer solid electrolyte. The all-solid-state battery sequentially comprises: a positive electrode, a third solid electrolyte layer optionally comprising a composite solid electrolyte, a first solid electrolyte layer containing a halide solid electrolyte, a second solid electrolyte layer, and a negative electrode. The all-solid-state battery sequentially comprises: a positive electrode, a third solid electrolyte layer containing a halide solid electrolyte or a composite solid electrolyte, a first solid electrolyte layer containing a sulfide solid electrolyte, a second solid electrolyte layer, and a negative electrode.

2. The all-solid battery according to claim 1, characterized by, The thickness of the second solid electrolyte layer and the third solid electrolyte layer is 1-10 μm.

3. The all-solid battery according to claim 2, characterized by, The thickness of the first solid electrolyte layer is 10-50 μm.

4. The all-solid battery according to claim 2, characterized by, The positive electrode comprises a halide solid electrolyte or an oxide solid electrolyte.

5. The all-solid battery according to any one of claims 2 to 4, characterized by, ​ 6. The all-solid battery according to any one of claims 1 to 4, characterized by, ​ 7. The all-solid battery according to any one of claims 1 to 4, characterized by, ​

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