Solid electrolyte membrane and preparation method and application thereof

Abstract

The invention discloses a solid electrolyte membrane which comprises a compact layer and a pore structure layer, the compact layer is located on the surface of at least one side of the pore structure layer, and the compact layer is obtained by performing laser melting on the pore structure layer. The laser enables surface protrusions of the pore structure layer to be melted and filled into surface pores of the pore structure layer, the compact layer formed through laser melting has a smooth surface and can make close contact with an electrode, and the interface resistance is reduced; the compact layer also has good mechanical strength and is beneficial to preventing electrolyte membrane breakage caused by local stress, so that the short-circuit risk of the all-solid-state battery is reduced; the pore structure layer can provide an ion transmission path through continuous through holes, the ion transmission path is shortened, and the ion conductivity is improved.

Description

Technical Field

[0001] The present application relates to the field of battery material technology, and in particular to a solid electrolyte membrane and a preparation method and application thereof. Background Art

[0002] Solid-state battery technology uses a glass compound made of lithium and sodium as a conductive material, and uses solid-state electrolytes to replace the electrolyte of previous lithium batteries. Compared with traditional liquid batteries, solid-state batteries exhibit higher safety under high temperature and mechanical stress; compared with liquid electrolytes with the same lithium content, solid-state electrolytes are lighter, allowing the battery anode material to use high-gram capacity materials, which can greatly improve the energy density of the battery; in terms of cycling, the interface between the solid-state electrolyte and the electrode material is more stable, which can reduce the occurrence of side reactions and thus extend the service life of the battery; the operating temperature range of solid-state batteries is wider, and the solid-state electrolyte is not easy to freeze or evaporate, allowing the battery to work normally under more extreme temperature conditions.

[0003] Although solid-state batteries have significant advantages in terms of safety, energy density and cycle life, the current research and development of solid-state batteries still faces difficulties. The solid electrolyte needs to be kinetically and / or thermodynamically stable to lithium metal and cathode materials, and at the same time be able to withstand the mechanical stress caused by the volume change of the active material. Granular solid-state batteries have a very thick solid electrolyte layer, which will significantly reduce the energy density of the solid-state battery; a thin electrolyte layer can be obtained by coating and drying the electrolyte slurry, but pinholes will appear when the slurry is dried and shrinks. Since all-solid-state batteries cannot control the random formation of lithium dendrites during the charge / discharge cycle, lithium dendrites will grow through the above pinholes, further causing battery short circuit failure and thermal runaway. In order to solve the above problems, there is an urgent need for a solid electrolyte membrane with high mechanical strength, high energy density and simple preparation process. Summary of the Invention

[0004] In response to the above-mentioned problems in the prior art, the present application provides a solid electrolyte membrane and a preparation method and application thereof. The specific technical solutions are as follows: On the one hand, the present application provides a solid electrolyte membrane, comprising a dense layer and a porous structure layer, wherein the dense layer is located on the surface of at least one side of the porous structure layer, and the dense layer is obtained by laser melting the porous structure layer, wherein the laser melts the surface protrusions of the porous structure layer and fills them into the surface pores of the porous structure layer.

[0005] In a possible implementation manner, the dense layer satisfies at least one of the following characteristics: The thickness of the dense layer is 0.05-5 μm; The porosity of the dense layer is 0-2%; The number of micropores in the dense layer is 0-1 pcs / m 2 .

[0006] In a possible implementation manner, the porous structure layer satisfies at least one of the following characteristics: The porosity of the porous structure layer is 5-20%; The number of micropores in the porous structure layer is 10-100 pcs / m 2 .

[0007] In a possible implementation manner, the ratio of the thickness of the dense layer to the thickness of the solid electrolyte membrane is 1%-10%.

[0008] In a possible embodiment, the ionic conductivity of the solid electrolyte membrane is 10 -6 -10 -2 S / cm.

[0009] In a possible embodiment, the material of the solid electrolyte membrane includes at least one of a halide-based solid electrolyte, a sulfide-based solid electrolyte, an argyrodite-type solid electrolyte, a lithium lanthanum zirconium-based solid electrolyte, and a NASICON-type oxide-based solid electrolyte.

[0010] On the other hand, the present application also provides a method for preparing a solid electrolyte membrane, comprising: providing an electrolyte slurry; Applying the electrolyte slurry and drying it to obtain a solid electrolyte matrix with a porous structure; Laser melting treatment is performed on at least one side of the surface of the solid electrolyte matrix to form a solid electrolyte membrane including a porous structure layer and a dense layer, wherein the dense layer is located on at least one side of the surface of the porous structure layer.

[0011] In a possible implementation manner, the preparation method further comprises: selecting an irradiation area of ​​the laser based on the surface morphology of the solid electrolyte matrix; focusing and homogenizing the laser beam to determine the defocus amount of the laser; The ablation threshold of the solid electrolyte matrix is ​​measured to determine the output energy of the laser.

[0012] In a possible implementation manner, the laser satisfies at least one of the following characteristics: The scanning speed of the laser is 1-100 mm / s; The output energy of the laser is 1-400 J / mm 2 ; The defocus of the laser is 0.001-0.1 mm; The scanning path of the laser is a unidirectional path scanning.

[0013] On the other hand, the present application also provides a solid-state battery, comprising the solid-state electrolyte membrane as described above.

[0014] Based on the above technical solution, this application has the following beneficial effects: The present application provides a solid electrolyte membrane, comprising a dense layer and a porous structure layer. The dense layer is obtained by laser melting the porous structure layer. The laser can melt the surface protrusions of the porous structure layer and fill them into the surface pores of the porous structure layer. The surface laser melting does not affect the porous structure layer of the solid electrolyte membrane; the dense layer can be in close contact with the electrode to reduce the interface resistance, and the dense layer has good mechanical strength, which is beneficial to prevent the electrolyte membrane from rupture due to local stress, thereby reducing the short circuit risk of the all-solid-state battery; the porous structure layer can provide an ion transmission path through continuous through holes, shorten the ion transmission path, and improve the ionic conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0016] Figure 1 : A schematic diagram of the principle of laser processing provided in an embodiment of the present application; Figure 2 : A schematic structural diagram of a solid-state battery provided in an embodiment of the present application; Figure 3 : A surface SEM image of a solid electrolyte matrix provided in Example 1 of the present application; Figure 4 : AFM image of a surface of a solid electrolyte matrix provided in Example 1 of the present application; Figure 5 : A surface SEM image of a dense layer of a solid electrolyte membrane provided in Example 1 of the present application; Figure 6 : AFM image of the surface of a dense layer of a solid electrolyte membrane provided in Example 1 of the present application; Figure 7 : An image of a solid electrolyte membrane during laser processing provided in Example 1 of the present application. DETAILED DESCRIPTION

[0017] The following is a clear and complete description of the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of this application.

[0018] For the following defined terms, these definitions shall apply unless a different definition is given in the claims or elsewhere in this specification. All numerical values, whether or not explicitly indicated, are defined herein as being modified by the term "about". The term "about" generally refers to a numerical range that one of ordinary skill in the art would consider equivalent to the stated value to produce substantially the same properties, functions, results, etc. A numerical range indicated by a lower value and an upper value is defined to include all numerical values ​​included in the numerical range and all subranges included in the numerical range.

[0019] It should be noted that the terms "first," "second," and the like in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions.

[0020] The present application provides a solid electrolyte membrane, comprising a dense layer and a porous structure layer, wherein the dense layer is located on the surface of at least one side of the porous structure layer, and the dense layer is obtained by laser melting the porous structure layer, wherein the laser causes the surface protrusions of the porous structure layer to melt and fill the surface pores of the porous structure layer. In this way, the dense layer formed by surface laser melting can not affect the high-conductivity phase structure inside the electrolyte membrane, and the high heating rate and high cooling rate characteristics of the laser are utilized to quickly melt the solid electrolyte in the shallow layer, so that it flows and fills the pores, forming a dense layer with a smooth surface, and the dense layer can be in close contact with the electrode, thereby reducing the interface resistance; the dense layer also has good mechanical strength, which is conducive to preventing the electrolyte membrane from rupturing due to local stress, thereby reducing the short circuit risk of the all-solid-state battery; the porous structure layer can provide an ion transmission path through continuous through holes, shorten the ion transmission path, and improve the ionic conductivity.

[0021] In some embodiments, the dense layer can be a fine-grained fused layer. This layer, with a fine-grained structure, is obtained by laser melting and solidifying the surface particles of the porous structure layer. By regulating the grain size and grain boundary characteristics, the grains in the fine-grained fused layer can be tightly bonded, which helps improve the mechanical strength and interfacial stability of the solid electrolyte membrane.

[0022] In a specific embodiment, doping ions are introduced into the dense layer to improve the overall performance of the dense layer; for example, Ta is doped into the dense layer. 5+ , used to improve the oxidation resistance of the dense layer; it can be understood that doping ions can be introduced into the dense layer according to actual needs.

[0023] In a specific embodiment, the pore structure layer at least partially has a pore structure; specifically, the pore structure can be interconnected through holes. It can be understood that the pore structure is the pores between the solid electrolyte particles, and the pore structure can be adjusted by adjusting the size of the solid electrolyte particles and / or adjusting the molding pressure of the solid electrolyte membrane; in one example, the pore structure can be nanometer-scale; in another example, the pore structure can be micrometer-scale.

[0024] In a specific embodiment, the dense layer is located on the surface of one side of the porous structure layer. The dense layer can improve the mechanical strength of the solid electrolyte membrane and resist surface stress. The porous structure layer can improve the toughness of the solid electrolyte membrane and prevent the solid electrolyte membrane from breaking as a whole. The dense layer can also block the penetration of lithium dendrites, reduce the risk of short circuit, and reduce the side reactions at the interface between the electrode and the electrolyte, thereby improving the cycle life of the solid-state battery.

[0025] In one specific embodiment, the solid electrolyte membrane has a dense layer on each of the two opposing surfaces of the porous structure layer, forming a "sandwich structure" of dense layer, porous structure layer, and dense layer. This structure separates the positive and negative electrodes of the solid-state battery, preventing bidirectional dendrite penetration from the positive and negative electrodes. Furthermore, the dense layer blocks heat conduction between the electrodes and the electrolyte, dissipating thermal stress and preventing short circuits caused by cracking of the electrolyte membrane.

[0026] In a possible embodiment, the thickness of the dense layer is 0.05-5 μm; it is understandable that the thickness of the dense layer can be any value between 0.05-5 μm; for example, the thickness of the dense layer can be 0.05 μm, 0.1 μm, 1 μm, 2 μm, 4 μm, 5 μm, etc. In this way, by controlling the thickness of the dense layer within the above range, the dense layer can effectively block the growth of lithium dendrites and withstand the puncture force of lithium dendrites, thereby improving the mechanical properties of the solid electrolyte membrane. If the thickness of the dense layer is too large, it will affect the pore structure inside the solid electrolyte membrane, resulting in a decrease in ionic conductivity. Preferably, the thickness of the dense layer is 2-3 μm.

[0027] In a possible embodiment, the porosity of the dense layer is 0-2%. It is understood that the porosity of the dense layer can be any value within the range of 0-2%. For example, the porosity of the dense layer can be 0, 0.5%, 1%, 1.5%, 2%, etc. In this way, the dense layer has a low porosity, which can evenly transfer heat and resist localized stress, thereby effectively improving the structural stability of the dense layer. Preferably, the porosity of the dense layer is 0-0.5%.

[0028] In a possible embodiment, the number of micropores in the dense layer is 0-1 pcs / m 2 It can be understood that the number of micropores in the dense layer can be 0-1 pcs / m 2 For example, the number of micropores in the dense layer can be 0, 0.1 pcs / m 2 , 0.5pcs / m 2 , 0.7pcs / m 2 , 0.9pcs / m 2 , 1pcs / m 2 The number of micropores per unit area can be used to characterize the degree of density. A smaller number of micropores indicates that the dense layer has a good dense structure, which is beneficial to improving the structural stability and mechanical strength of the dense layer, thereby effectively preventing short circuits in solid-state batteries.

[0029] In a possible embodiment, the porosity of the porous structure layer is 5-20%. It is understood that the porosity of the porous structure layer can be any value within the range of 5-20%. For example, the porosity of the porous structure layer can be 5%, 10%, 12%, 15%, 20%, etc. Thus, if the porosity is too high, the ion transmission path will be dispersed, while if the porosity is too low, the ion transmission path will be too concentrated. Controlling the porosity of the porous structure layer within the above range can provide sufficient channels for ion transmission and reduce the resistance during ion transmission, thereby reducing local overcharge or overdischarge.

[0030] In some embodiments, the porosity gradually increases from the dense layer to the porous structure layer; in one example, the porosity gradient from the dense layer to the porous structure layer increases, which enables ions to choose different paths according to their positions during transmission, ensuring rapid exchange of ions at the electrode interface, and providing more transmission paths by the porous structure layer; and the gradient-increasing porosity can guide the ions to be evenly distributed in the thickness direction of the solid electrolyte membrane, reducing the accumulation or loss of ions inside the solid electrolyte membrane.

[0031] In a possible embodiment, the number of micropores in the porous structure layer is 10-100 pcs / m 2 It can be understood that the number of micropores in the porous structure layer can be 10-100 pcs / m 2For example, the number of micropores in the porous structure layer can be 10 pcs / m 2 , 20pcs / m 2 , 50pcs / m 2 , 80pcs / m 2 , 100pcs / m 2 Thus, compared with the dense layer, the porous structure layer has more micropores per unit area, which can provide an effective ion transmission channel and improve the ion conductivity of the solid electrolyte membrane. Preferably, the number of micropores in the porous structure layer is 40-60 pcs / m 2 .

[0032] In a possible embodiment, the ratio of the thickness of the dense layer to the thickness of the solid electrolyte membrane is 1%-10%. It is understood that the ratio of the thickness of the dense layer to the thickness of the solid electrolyte membrane can be any value between 1%-10%. For example, the ratio of the thickness of the dense layer to the thickness of the solid electrolyte membrane can be 1%, 3%, 5%, 8%, 10%, etc. In this way, the thickness of the dense layer can be adjusted according to the thickness of the solid electrolyte membrane, and the ratio of the thickness of the dense layer to the solid electrolyte membrane can be controlled within the above range. In this way, the dense layer is located at the shallow surface of the solid electrolyte membrane in the thickness direction, does not affect the pore structure inside the solid electrolyte membrane, and maintains good ionic conductivity while improving mechanical strength. Preferably, the ratio of the thickness of the dense layer to the thickness of the solid electrolyte membrane is 2%-5%.

[0033] In a possible embodiment, the ionic conductivity of the solid electrolyte membrane is 10 -6 -10 -2 S / cm; It can be understood that the ionic conductivity of the solid electrolyte membrane can be 10 -6 -10 -2 S / cm; for example, the ionic conductivity of the solid electrolyte membrane can be 10 -6 S / cm, 10 -5 S / cm, 10 -4 S / cm, 10 -3 S / cm, 10 -2 S / cm, etc. Preferably, the ionic conductivity of the solid electrolyte membrane is 10 -3 -10 -2 S / cm. In this way, the solid electrolyte membrane has a high ionic conductivity, which can ensure that ions migrate quickly and stably between the positive and negative electrodes during the battery's charge and discharge process, which helps to avoid dendrite growth inside the battery and improve the battery's energy density.

[0034] In some embodiments, the material of the solid electrolyte membrane includes at least one of a halide-based solid electrolyte, a sulfide-based solid electrolyte, an argyrodite-type solid electrolyte, a lithium lanthanum zirconium-based solid electrolyte, and a NASICON-type oxide-based solid electrolyte, and can have good ionic conductivity, and the structure of the solid electrolyte membrane can be applicable to a variety of solid electrolyte materials.

[0035] Specifically, the halide-based solid electrolyte may be at least one of Li2ZrCl6, LiNbOCl4, LiTaOCl4, Li3YCl6, and Li3InCl6. Specifically, the sulfide-based solid electrolyte may be Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-LiCl, Li2S-P2S5-LiBr, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are positive numbers, and Z is one of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li x MO y (wherein x and y are positive numbers, and M is at least one of P, Si, Ge, B, Al, Ga, and In); specifically, the argyrodite-type solid electrolyte can be Li 10 GeP2S 12 Specifically, the lithium lanthanum zirconium oxide solid electrolyte can be Li 5+x La3Zr x M 2-x O 12 , wherein M is one of Ta, Nb, Hf, Al, Si, Ga, Ge, Sc, Ti, V, Y and Sn, and x=0-0.6.

[0036] The following describes a method for preparing a solid electrolyte membrane provided by an embodiment of the present application. The order of steps listed in the embodiment is only one of many possible execution orders and does not represent the only execution order. The preparation method includes: S10: Providing electrolyte slurry; In some embodiments, the electrolyte slurry includes a solid electrolyte, a binder, and a solvent. Specifically, the mass ratio of the solid electrolyte to the binder in the electrolyte slurry is 18-20:1. It is understood that the mass ratio of the solid electrolyte to the binder in the electrolyte slurry can be any value between 18-20:1. For example, the mass ratio of the solid electrolyte to the binder in the electrolyte slurry can be 18:1, 19:1, 20:1, etc. By controlling the mass ratio of the solid electrolyte to the binder within the above range, the solid electrolyte particles can be connected by the binder, forming a solid electrolyte membrane with a stable structure.

[0037] Specifically, the material of the solid electrolyte membrane includes at least one of a halide-based solid electrolyte, a sulfide-based solid electrolyte, an argyrodite-type solid electrolyte, a lithium lanthanum zirconium-based solid electrolyte, and a NASICON-type oxide-based solid electrolyte.

[0038] Specifically, the binder includes at least one of ethyl cellulose, poly(1,4-butylene adipate), polyethylene glycol, polyacrylic acid, and polyacrylonitrile, which can effectively increase the adhesion between electrolyte particles, fix the internal structure of the solid electrolyte membrane, and prevent the solid electrolyte membrane from cracking or breaking; and has good chemical stability, and can still enable the solid electrolyte membrane to maintain its intact structure after long-term use.

[0039] S20: applying the electrolyte slurry and drying it to obtain a solid electrolyte matrix with a porous structure; In some embodiments, the thickness of the solid electrolyte matrix is ​​1-500 μm. It is understood that the thickness of the solid electrolyte matrix can be any value between 1-500 μm. For example, the thickness of the solid electrolyte matrix can be 1 μm, 5 μm, 100 μm, 200 μm, 500 μm, etc. Preferably, the thickness of the solid electrolyte matrix is ​​10-60 μm, and the thickness of the solid electrolyte matrix can be adjusted according to the actual thickness of the solid electrolyte membrane.

[0040] S30: performing laser melting treatment on the surface of at least one side of the solid electrolyte matrix to form a solid electrolyte membrane including a porous structure layer and a dense layer, wherein the dense layer is located on the surface of at least one side of the porous structure layer.

[0041] In some embodiments, step S30 further includes: S31: Selecting a laser irradiation area based on the surface morphology of the solid electrolyte matrix; Specifically, the surface morphology of the solid electrolyte matrix can be observed by scanning electron microscopy, and the portion with obvious protrusions can be selected as the laser irradiation area; illustratively, the portion with larger pore diameter on the surface of the solid electrolyte matrix can also be selected as the laser irradiation area.

[0042] S32: focusing and homogenizing the laser beam to determine the defocus amount of the laser; Specifically, a focusing lens can be used to focus the laser beam, thereby reducing the diameter of the laser and increasing the energy density of the laser beam, thereby achieving higher power at the focal point. Specifically, a beam shaper can be used to homogenize the laser beam to avoid local overheating or uneven processing.

[0043] The defocus amount refers to the distance between the focus of the laser beam and the actual processing surface. In a specific embodiment, the defocus amount of the laser can be determined according to the morphology of the protrusions on the surface of the solid electrolyte matrix, so that the size of the laser spot is larger than the size of the protrusions.

[0044] S33: Determine the ablation threshold of the solid electrolyte matrix and determine the output energy of the laser.

[0045] The ablation threshold of a solid electrolyte matrix refers to the minimum energy required for the solid electrolyte matrix to begin undergoing physical or chemical changes under laser irradiation. Specifically, the ablation threshold of a solid electrolyte matrix can be measured through microscopic observation, in-situ scattered light detection, spectral analysis, and thermal effect analysis. The laser output energy is greater than or equal to the ablation threshold of the solid electrolyte, allowing the laser to change the surface morphology of the solid electrolyte matrix. In this way, through the thermal effect between the laser and the solid electrolyte material, under the conditions of laser treatment, the shallow surface layer of the solid electrolyte material can be melted and then solidified to form a dense layer.

[0046] Figure 1 Schematic diagram of laser processing principle, refer to Figure 1 The laser irradiates the protrusions on the surface of the solid electrolyte matrix, melting the protrusions and forming a molten pool on the surface of the solid electrolyte matrix. The molten material in the molten pool flows to the surrounding recessed areas under the action of capillary force. After the molten material cools, a smooth surface is formed. The melting depth at this time is only zero to several microns.

[0047] In some embodiments, the laser used for the laser melting process may be at least one of a Nd:YAG laser, a CO2 laser, and an ArF laser. In a possible implementation, the scanning path of the laser is a unidirectional path scanning.

[0048] In a specific embodiment, the laser scanning speed is 1-100 mm / s; it is understood that the laser scanning speed can be any point value in the range of 1-100 mm / s; for example, the laser scanning speed can be 1 mm / s, 10 mm / s, 50 mm / s, 80 mm / s, 100 mm / s, etc. If the laser scanning speed is too slow, the surface of the solid electrolyte matrix will be excessively melted, the dense layer will be too large, and the overall conductivity of the solid electrolyte membrane will be too low; if the laser scanning speed is too fast, the laser melting will be insufficient, and an effective dense layer cannot be formed. It is understood that the laser scanning speed can be adjusted according to the material of the solid electrolyte.

[0049] In a specific embodiment, the output energy of the laser is 1-400 J / mm 2 ; It can be understood that the output energy of the laser can be 1-400J / mm 2 For example, the output energy of the laser can be 1J / mm 2 , 100J / mm 2 , 150J / mm 2 , 300J / mm 2 , 400J / mm 2 If the laser energy is too low, it will lead to incomplete melting and the formation of a smooth surface will not be achieved; if the laser energy is too high, it will damage the solid electrolyte matrix structure. It can be understood that the laser output energy can be adjusted according to the surface morphology of the solid electrolyte.

[0050] In a specific embodiment, the laser defocus is 0.001-0.1 mm. It is understood that the laser defocus can be any value within the range of 0.001-0.1 mm. For example, the laser defocus can be 0.001 mm, 0.005 mm, 0.01 mm, 0.05 mm, 0.1 mm, etc. If the laser defocus is too high, the layered structure of the electrolyte matrix may be dislocated over a large area, and the laser may not be able to treat the entire surface.

[0051] The preparation method provided in the present application is simple to operate and has low cost. It can be operated in a narrow space and a protective atmosphere. By utilizing the high heating rate and high cooling rate characteristics of the laser, it can quickly melt the solid electrolyte in the shallow layer, allowing it to flow and fill the pores, and does not affect the pore structure layer inside the solid electrolyte membrane, so that the solid electrolyte membrane maintains a high ionic conductivity; by forming a dense layer with high density, it is beneficial to improve the mechanical strength of the solid electrolyte membrane and significantly reduce the short circuit risk of the all-solid-state battery.

[0052] On the other hand, the present application also provides a solid-state battery, comprising the solid-state electrolyte membrane as described above, or a solid-state electrolyte membrane prepared by the above-mentioned method for preparing the solid-state electrolyte membrane.

[0053] Specifically, the solid-state battery includes a positive electrode layer 4, a solid electrolyte membrane layer 3 and a negative electrode layer 5. Figure 2 Among them, the solid electrolyte membrane layer 3 includes multiple dense layers 1 and a porous structure layer 2. The multiple dense layers 1 are respectively located between the porous structure layer 2 and the positive electrode layer 4, and between the porous structure layer 2 and the negative electrode layer 5. The dense layer 1 can be used to block dendrite growth, avoid rupture of the solid electrolyte membrane, and thus avoid short circuit of the solid-state battery.

[0054] The following describes specific embodiments of the present application in conjunction with the above-mentioned solid electrolyte membrane, its preparation method, and application. The following examples describe the technical solutions of the present application in more detail. These examples are for illustrative purposes only, as various modifications and variations within the scope of the disclosure of this application are obvious to those skilled in the art. The reagents and materials used in the examples can be obtained commercially or synthesized according to conventional methods and can be used directly without further processing. The instruments and devices used in the examples are all commercially available.

[0055] Example 1 This embodiment provides a solid electrolyte membrane and a method for preparing the same, which are prepared by the following steps: 1. The solid electrolyte Li2S-P2S5-LiCl and the SBR binder were mixed and dispersed in a xylene solvent in a mass ratio of 95:5 to obtain an electrolyte slurry; 2. The electrolyte slurry is coated on the surface of the aluminum foil and dried. The dried electrolyte dry film is subjected to isostatic pressing at a pressure of 600 MPa for 5 minutes to obtain a solid electrolyte matrix; 3. Laser melting treatment is performed on the surface of one side of the solid electrolyte matrix using a Nd:YAG laser with an output energy of 1J / mm 2 , moving in a direction perpendicular to the laser beam, the laser scanning speed is 20 mm / s, the laser defocus is 0.001 mm, forming a solid electrolyte membrane including a porous structure layer and a dense layer.

[0056] Example 2 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the laser used is a CO2 laser.

[0057] Example 3 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the laser used is an ArF laser.

[0058] Example 4 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the scanning speed of the laser is 1 mm / s.

[0059] Example 5 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the scanning speed of the laser is 1 dm / s.

[0060] Example 6 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the output energy of the laser is 400 J / mm 2 .

[0061] Example 7 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the defocusing amount of the laser is 0.1 mm.

[0062] Example 8 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2ZrCl6.

[0063] Example 9 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is LiNbOCl4.

[0064] Example 10 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is LiNbOCl4.

[0065] Example 11 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li3YCl6.

[0066] Example 12 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li3InCl6.

[0067] Example 13 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-P2S5.

[0068] Example 14 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-P2S5-LiI.

[0069] Example 15 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-P2S5-LiBr.

[0070] Example 16 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-P2S5-Li2O.

[0071] Example 17 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-P2S5-Li2O-LiI.

[0072] Example 18 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-SiS2.

[0073] Example 19 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-SiS2-LiI.

[0074] Example 20 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-SiS2-LiBr.

[0075] Example 21 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-SiS2-LiCl.

[0076] Example 22 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-SiS2-B2S3-LiI.

[0077] Example 23 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-SiS2-P2S5-LiI.

[0078] Example 24 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-B2S3.

[0079] Example 25 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-P2S5-Z m S n , where m and n are positive numbers and Z is Ge.

[0080] Example 26 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-GeS2.

[0081] Example 27 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-SiS2-Li3PO4.

[0082] Example 28 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li2S-SiS2-Li x MO y , where x and y are positive numbers and M is P.

[0083] Example 29 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is Li 10 GeP2S 12 .

[0084] Example 30 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is lithium lanthanum zirconium oxide solid electrolyte Li 5+x La3Zr x M 2-x O 12 , where M is Ta and x=0.2.

[0085] Example 31 The similarities between this embodiment and embodiment 1 are not repeated here. The difference between this embodiment and embodiment 1 is that the material of the solid electrolyte is a NASICON structure oxide electrolyte.

[0086] Comparative Example 1 The similarities between this comparative example and Example 1 are not repeated here. The difference between this comparative example and Example 1 is that the laser used is an InGaN semiconductor laser.

[0087] Comparative Example 2 The similarities between this comparative example and Example 1 are not repeated here, and the difference between this comparative example and Example 1 is that: The scanning speed of the laser is 0.1 mm / s.

[0088] Comparative Example 3 The similarities between this comparative example and Example 1 are not repeated here. The difference between this comparative example and Example 1 is that the scanning speed of the laser is 2 dm / s.

[0089] Comparative Example 4 The similarities between this comparative example and Example 1 are not repeated here. The difference between this comparative example and Example 1 is that the output energy of the laser is 1000 J / mm 2 .

[0090] Comparative Example 5 The similarities between this comparative example and Example 1 are not repeated here. The difference between this comparative example and Example 1 is that the output energy of the laser is 0.1 J / mm 2 .

[0091] The performance of the solid electrolyte membranes prepared in the above embodiments and comparative examples was tested, and the test method was as follows: (1) Ionic conductivity test: In an argon atmosphere, the upper and lower surfaces of the solid electrolyte membranes of the above embodiments and comparative examples were respectively connected to a constant potential instrument equipped with a frequency response analyzer, and the ionic conductivity of the solid electrolyte membrane was measured by the electrochemical impedance spectroscopy. The real value of the impedance at the measuring point where the absolute value of the phase of the complex impedance was the smallest was taken as the resistance value of the solid electrolyte membrane to ionic conduction; the conductivity of the solid electrolyte membrane was divided by the conductivity of the solid electrolyte matrix to obtain the conductivity retention rate.

[0092] (2) Scanning electron microscopy observation: The microscopic morphology of the surface of the solid electrolyte membrane was observed by scanning electron microscopy, and the equipment used was a Sigma300-Gemini1 scanning electron microscope.

[0093] (3) Atomic force microscope observation: The microscopic morphology and roughness of the solid electrolyte membrane were observed by atomic force microscope, and the equipment used was Hitachi AFM5500M atomic force microscope.

[0094] (4) All-solid-state battery testing: In an argon atmosphere, the Li6PS5Cl solid electrolyte material and the positive electrode active material LiCoO2 were mixed in an agate mortar at a mass ratio of 3:7 to obtain a positive electrode mixture. The positive electrode mixture, solid electrolyte membrane, and metal Li foil were assembled in an insulating cylinder to obtain a solid electrode. The solid electrode was sealed to obtain an all-solid-state battery. The all-solid-state battery was subjected to electrochemical performance testing at a 3C rate in the voltage range of 2.5-4.2V.

[0095] The following Table 1 statistically records the test data of the above embodiments and comparative examples: Table 1

[0096] Combined with Example 1, reference Figure 3-7 , Figure 3 and Figure 4 The SEM and AFM images of the surface of the solid electrolyte matrix in Example 1 respectively show that the surface of the solid electrolyte matrix is ​​composed of irregularly arranged solid electrolyte particles. There are pores between the particles, and lithium dendrites are easily formed and grown in the pores. When the battery charge and discharge rate is high, it causes a short circuit in the battery. Figure 5 and Figure 6 The surface SEM image and AFM image of the dense layer in Example 1 respectively show that the existence of grain boundaries and pores on the surface of the dense layer cannot be observed at a scale of 1 μm, which proves that laser treatment can eliminate the protrusions on the surface of the solid electrolyte matrix and fill the pores on the surface of the solid electrolyte matrix. Figure 7 This is an image of the solid electrolyte membrane during laser processing. It can be clearly observed that the surface of the solid electrolyte membrane after laser melting is smoother than that of the solid electrolyte matrix without laser melting, proving that a dense layer with a flat and smooth surface can be formed after laser melting.

[0097] Referring to the test results in Table 1, combined with Examples 1-3 and Comparative Example 1, it can be seen that the InGaN semiconductor laser used in Comparative Example 1 has a relatively small power and cannot provide the laser output energy of the Nd:YAG laser, CO2 laser and ArF laser in Examples 1-3, resulting in a smaller thickness of the dense layer in Comparative Example 1, and obvious pores can still be observed, causing the solid-state battery to short-circuit during the charging and discharging process.

[0098] Referring to the test results in Table 1, combined with Examples 1, 4 and 5 and Comparative Examples 2 and 3, it can be seen that the laser scanning speed during the laser treatment of Examples 1, 4 and 5 is 1 mm / s-1 dm / s, and the laser scanning speed of Comparative Example 2 is 0.1 mm / s. There are no obvious pores on the surface of the obtained solid electrolyte membrane, but the ion conductivity retention rate is 6.6%. The ion conductivity retention rates of 94.6%, 95.2% and 97% in Examples 1, 4 and 5 prove that the laser scanning speed is too slow, resulting in an excessively thick dense layer, which in turn affects ion transport and causes a decrease in the overall conductivity of the solid electrolyte membrane; in Comparative Example 3, the laser scanning speed is 2 dm / s, and obvious pores are observed on the surface of the solid electrolyte membrane, proving that the laser speed moves too fast, resulting in the laser being unable to effectively melt the surface protrusions, and thus unable to fill the pores on the surface of the solid electrolyte membrane, and the solid-state battery is prone to short circuits in the unmelted areas.

[0099] Referring to the test results in Table 1, combined with Examples 1, 6 and Comparative Examples 4, 5, it can be seen that the output energy of the laser during the laser treatment of Examples 1 and 6 is 1 J / mm 2 and 400J / mm 2 , while the laser output energy of Comparative Example 4 is 1000 J / mm 2 The ionic conductivity retention rate of the solid electrolyte membrane was 6.3%, which was significantly lower than the ionic conductivity retention rates of 94.6% and 99.1% in Examples 1 and 6, respectively. This indicates that excessive laser output energy can lead to an excessively thick dense layer, thereby affecting the ion transport in the pore structure inside the solid electrolyte membrane and reducing the overall conductivity of the solid electrolyte membrane. In Comparative Example 5, the laser output energy was 0.1 J / mm 2 , obvious pores were observed on the surface of the solid electrolyte membrane, proving that the laser output energy was too small, resulting in the laser being unable to effectively melt the surface protrusions and unable to fill the pores on the surface of the solid electrolyte membrane, which in turn made the solid-state battery prone to short circuits.

[0100] In combination with Examples 1, 7-31, it can be seen that under the same preparation conditions, by changing the material of the solid electrolyte, a dense layer can be formed on the surface of solid electrolyte membranes of different materials by laser melting, and there are no obvious pores on the surface of the dense layer. The solid electrolyte membrane has good ion conductivity retention. The ion conductivity retention of the solid electrolyte membranes in Examples 1, 7-31 is between 90.8% and 99.7%, and when assembled into solid-state batteries, short circuits occur at a rate of 3C. This proves that the preparation method provided in this application can modify the materials of various solid electrolyte membranes, so that the solid electrolyte membrane has good ion conductivity retention and effectively avoids short circuits.

[0101] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0102] What is described above are only some embodiments of the present application and are not intended to limit the present application. Those skilled in the art should understand that the present application may be subject to various changes and improvements, and any modifications, equivalent substitutions, and improvements made in accordance with the present application shall fall within the scope of protection required by the present application.

Claims

1. A solid electrolyte membrane, characterized in that It includes a dense layer and a porous structure layer, wherein the dense layer is located on the surface of at least one side of the porous structure layer, and the dense layer is obtained by laser melting the porous structure layer, wherein the laser melts the surface protrusions of the porous structure layer and fills them into the surface pores of the porous structure layer.

2. The solid electrolyte membrane according to claim 1, characterized in that The dense layer satisfies at least one of the following characteristics: The thickness of the dense layer is 0.05-5 μm; The porosity of the dense layer is 0-2%; The number of micropores in the dense layer is 0-1 pcs / m 2 .

3. The solid electrolyte membrane according to claim 1, wherein The porous structure layer satisfies at least one of the following characteristics: The porosity of the porous structure layer is 5-20%; The number of micropores in the porous structure layer is 10-100 pcs / m 2 .

4. The solid electrolyte membrane according to any one of claims 1 to 3, characterized in that The ratio of the thickness of the dense layer to the thickness of the solid electrolyte membrane is 1%-10%.

5. The solid electrolyte membrane according to any one of claims 1 to 3, characterized in that The ionic conductivity of the solid electrolyte membrane is 10 -6 -10 -2 S / cm.

6. The solid electrolyte membrane according to any one of claims 1 to 3, characterized in that The material of the solid electrolyte membrane includes at least one of a halide-based solid electrolyte, a sulfide-based solid electrolyte, an argyrodite-type solid electrolyte, a lithium lanthanum zirconium-based solid electrolyte, and a NASICON-type oxide-based solid electrolyte.

7. A method for preparing a solid electrolyte membrane, characterized in that: include: providing an electrolyte slurry; Applying the electrolyte slurry and drying it to obtain a solid electrolyte matrix with a porous structure; Laser melting treatment is performed on at least one side of the surface of the solid electrolyte matrix to form a solid electrolyte membrane including a porous structure layer and a dense layer, wherein the dense layer is located on at least one side of the surface of the porous structure layer.

8. The preparation method according to claim 7, characterized in that The preparation method further comprises: selecting an irradiation area of ​​the laser based on the surface morphology of the solid electrolyte matrix; focusing and homogenizing the laser beam to determine the defocus amount of the laser; The ablation threshold of the solid electrolyte matrix is ​​measured to determine the output energy of the laser.

9. The preparation method according to claim 8, characterized in that The laser meets at least one of the following characteristics: The scanning speed of the laser is 1-100 mm / s; The output energy of the laser is 1-400 J / mm 2 ; The defocus of the laser is 0.001-0.1 mm; The scanning path of the laser is a unidirectional path scanning.

10. A solid-state battery, characterized in that: The invention comprises the solid electrolyte membrane according to any one of claims 1 to 5.

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