All-solid-state sulfide electrolyte layer, method for producing the same, and solid-state lithium ion battery

Abstract

This application discloses an all-solid-state sulfide electrolyte layer, its preparation method, and a solid-state lithium-ion battery. In this application, the all-solid-state sulfide electrolyte layer includes a porous framework layer and an electrolyte filling the pores of the porous framework layer; the porous framework layer is obtained by creating pores in the sulfide electrolyte material; the sulfide electrolyte material is Li6PS5Cl or Li 10 SnPS 12 Li6PS5Br or Li 10 GeP2S 12 The electrolyte is selected from Li6PS5Cl and Li 10 SnPS 12 Li6PS5Br and Li 10 GeP2S 12 In at least one of the following methods, the present application alleviates the mismatch between electrolyte particles during the dry preparation of the electrolyte layer by casting a sulfide skeleton layer with a sulfide electrolyte, reduces the porosity of the electrolyte particles, makes the connection between electrolyte particles tighter, and improves the conductivity of the electrolyte layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of secondary batteries, in particular to a full solid sulfide electrolyte layer, a preparation method thereof and a solid-state lithium ion battery. BACKGROUND

[0002] With the rapid development and progress of society, energy shortage and environmental pollution problems are becoming increasingly serious, and people's demand for clean energy is becoming increasingly important. As the mainstream energy supply device of new energy vehicles, the energy density and safety performance of lithium ion batteries are of great concern. The existing commercial lithium ion batteries are mostly liquid batteries, and the energy density of liquid batteries has reached a bottleneck. It is difficult to improve in terms of high energy density, and safety accidents of lithium ion batteries have occurred frequently in recent years. The theoretical energy storage density limit of solid-state batteries is 2-10 times that of liquid lithium ion batteries, and solid-state batteries use solid-state electrolytes, have low heat generation and better safety performance. Therefore, the development of solid-state batteries has become the focus of attention at the moment.

[0003] In the prior art, solid-state batteries mostly use sulfide solid-state electrolytes such as Li3.25Ge0.25P0.75S4, Li10GeP2S12(LGPS) and Li9.54Si1.74P1.44S11.7Cl0.3(LSiPSCl) materials as electrolyte layers, and the preparation method is mostly dry mixing method. The inventors found through research that the sulfide electrolyte layer prepared by the dry mixing method has a high porosity, and lithium ions cannot be transmitted in the pores, resulting in low conductivity and loss of electrochemical performance. Therefore, the sulfide electrolyte material needs to be further improved in the art to improve the conductivity of the electrolyte material. SUMMARY

[0004] The purpose of the present application is to provide a full solid sulfide electrolyte layer, so that the conductivity of the electrolyte material is improved.

[0005] Another purpose of the present application is to provide a preparation method of a full solid sulfide electrolyte layer.

[0006] Another purpose of the present application is to provide a solid-state lithium ion battery comprising the full solid sulfide electrolyte layer described above.

[0007] Another purpose of the present application is to provide a method for improving the conductivity of a solid-state sulfide electrolyte layer.

[0008] To solve the above technical problems, the first aspect of the present application provides a full solid sulfide electrolyte layer, the full solid sulfide electrolyte layer comprising a porous framework layer, and an electrolyte filled in the pores of the porous framework layer.

[0009] The porous framework layer is obtained by pore-forming a sulfide electrolyte material.

[0010] In some preferred embodiments, the sulfide electrolyte material is Li6PS5Cl, Li 10 SnPS 12 , Li6PS5Br or Li 10 GeP2S 12 .

[0011] In some preferred embodiments, the electrolyte is selected from at least one of Li6PS5Cl, Li 10 SnPS 12 , Li6PS5Br and Li 10 GeP2S 12 .

[0012] In some preferred embodiments, the porosity of the porous framework layer is 65 to 80%.

[0013] In some preferred embodiments, the mass ratio of the porous framework layer to the electrolyte is 1:(1.5-4.5).

[0014] In some preferred embodiments, the sulfide electrolyte material is Li6PS5Br, and the electrolyte is Li6PS5Br.

[0015] In some preferred embodiments, the sulfide electrolyte material is Li6PS5Cl, and the electrolyte is Li6PS5Br.

[0016] In some preferred embodiments, the thickness of the all-solid-state sulfide electrolyte layer is 45-55 μm, for example, 50 μm.

[0017] In a second aspect, the present application provides a method for preparing an all-solid-state sulfide electrolyte layer, the method comprising the steps of:

[0018] porous framework layer is obtained by porosifying a sulfide electrolyte material;

[0019] an electrolyte solution is cast on the porous framework layer, followed by vacuum drying, high-temperature treatment and flat-plate hot-pressing treatment, to obtain the all-solid-state sulfide electrolyte layer;

[0020] In some preferred embodiments, the sulfide electrolyte material is Li6PS5Cl, Li 10 SnPS 12 , Li6PS5Br or Li 10 GeP2S 12 .

[0021] In some preferred embodiments, the electrolyte is selected from at least one of Li6PS5Cl, Li 10 SnPS 12 , Li6PS5Br and Li 10GeP2S 12 at least one of the group consisting of

[0022] In some preferred embodiments, the preparation of the porous framework layer comprises the steps of:

[0023] coating the sulfide electrolyte slurry containing the pore-forming agent on the current collector, sequentially rolling and vacuum drying to solidify the sulfide electrolyte slurry, and separating the sulfide electrolyte slurry from the current collector to obtain the porous framework layer.

[0024] In some preferred embodiments, the mass ratio of the sulfide electrolyte material to the pore-forming agent in the sulfide electrolyte slurry containing the pore-forming agent is 3:1 to 1:3.

[0025] In some preferred embodiments, the preparation of the sulfide electrolyte slurry containing the pore-forming agent comprises the steps of:

[0026] mixing the sulfide electrolyte material and the pore-forming agent and stirring to obtain the sulfide electrolyte slurry containing the pore-forming agent.

[0027] In some preferred embodiments, the instrument used for stirring is a Thinky defoaming stirrer.

[0028] In order to make the prepared porous framework layer have uniform size pores, in some preferred embodiments, the stirring program comprises a first stirring stage and a second stirring stage, the rotation speed Rev1 of the first stirring stage is higher than the rotation speed Rev2 of the second stirring stage. In some more preferred embodiments, the first stirring stage lasts t1 minutes at a rotation speed of Rev1, and the second stirring stage lasts t2 minutes at a rotation speed of Rev2.

[0029] wherein Rev1 is 1800-2200 rmp, t1 is 9-11 minutes,

[0030] Rev2 is 400-600 rmp, and t1 is 4-6 minutes.

[0031] In some preferred embodiments, the electrolyte and ethanol are mixed to obtain the electrolyte solution, and the solid content of the electrolyte solution is 40-60%, for example, 50%.

[0032] In some preferred embodiments, the high-temperature treatment is carried out in a muffle furnace.

[0033] In some preferred embodiments, the temperature of the high-temperature treatment is 500-600°C, for example, 550°C.

[0034] In some preferred embodiments, the pressure of the flat plate hot pressing treatment is 5-10 Mpa.

[0035] The hot-pressing treatment time of the flat plate is 100-150 minutes; for example, 120 minutes.

[0036] The hot-pressing treatment temperature of the flat plate is 70-80℃; for example, 75℃.

[0037] The third aspect of the present application provides a solid-state lithium ion battery, which comprises the all-solid-state sulfide electrolyte layer of the first aspect of the present application.

[0038] The fourth aspect of the present application provides a method for improving the conductivity of a solid-state sulfide electrolyte layer, which comprises the following steps:

[0039] The sulfide electrolyte layer is configured in a manner that the electrolyte is filled in a porous framework layer;

[0040] The porous framework layer is obtained by pore-forming on a sulfide electrolyte material;

[0041] The sulfide electrolyte material is Li6PS5Cl, Li 10 SnPS 12 , Li6PS5Br or Li 10 GeP2S 12 ; and

[0042] The electrolyte is selected from at least one of Li6PS5Cl, Li 10 SnPS 12 , Li6PS5Br and Li 10 GeP2S 12 .

[0043] The present application has at least the following advantages over the prior art:

[0044] (1) The all-solid-state sulfide electrolyte layer provided by the present application is configured in a manner that the sulfide electrolyte is cast in a sulfide framework layer, which alleviates the incompatibility between electrolyte particles in the process of dry preparation of the electrolyte layer, reduces the pores in the electrolyte particles, makes the connection between electrolyte particles more compact, and improves the conductivity of the electrolyte layer.

[0045] (2) In the preferred embodiment of the present application, the all-solid-state sulfide electrolyte layer uses a material with high grain boundary conductivity as the framework Li6PS5Cl, and casts a material with high bulk phase conductivity Li6PS5Br, which form a coordination, thereby improving the conductivity of the electrolyte layer.

[0046] It should be understood that, within the scope of the present application, the above technical features of the present application and the technical features specifically described in the following (such as the examples) can be combined with each other to form new or preferred technical solutions. Due to the limited space, they are not listed one by one here. DETAILED DESCRIPTION

[0047] The existing sulfide electrolyte material commonly uses lithium phosphorus sulfide chloride and the like as a sulfide electrolyte, and is prepared into an electrolyte layer by a dry mixing method. Although lithium phosphorus sulfide chloride is a material with relatively high conductivity, it still cannot meet the needs of use. In order to further improve the conductivity of the material, the inventors found through research that one of the reasons for causing the conductivity of the lithium phosphorus sulfide chloride electrolyte layer to be low is that it has a large pore inside, and the pores make lithium ions unable to be transmitted. Therefore, the inventors innovatively developed a full solid-state sulfide electrolyte layer, and used a method of pouring and filling electrolyte in a porous framework layer to enhance the cooperation between particles, reduce pores, and greatly enhance the conductivity of the material.

[0048] Full solid-state sulfide electrolyte layer

[0049] In the present application, the full solid-state sulfide electrolyte layer comprises a porous framework layer and an electrolyte filled in the pores of the porous framework layer.

[0050] The porous framework layer is obtained by pore-forming of a sulfide electrolyte material. The pore-forming method can be any method commonly used to obtain a porous material, such as a template method, an etching method, and the like. In a preferred embodiment of the present application, the template method is used to pore-form the sulfide electrolyte material.

[0051] The sulfide electrolyte material constituting the porous framework layer can be any sulfide electrolyte material commonly used in the field of solid-state batteries. In a preferred embodiment of the present application, the sulfide electrolyte material is Li6PS5Cl, Li 10 SnPS 12 , Li6PS5Br or Li 10 GeP2S 12 .

[0052] The electrolyte filled in the pores of the porous framework layer is also any sulfide electrolyte material or a combination of a plurality of sulfide electrolyte materials commonly used in the field of solid-state batteries. The material used for the electrolyte can be the same as or different from that of the porous framework layer. In a preferred embodiment of the present application, the electrolyte is selected from at least one of Li6PS5Cl, Li 10 SnPS 12 , Li6PS5Br and Li 10 GeP2S 12 .

[0053] In some preferred embodiments of the present application, the sulfide electrolyte material is Li6PS5Br, and the electrolyte is Li6PS5Br. In some more preferred embodiments of the present application, the sulfide electrolyte material is Li6PS5Cl, and the electrolyte is Li6PS5Br. The use of Li6PS5Cl, which has a higher grain boundary conductivity, as the framework, and Li6PS5Br, which has a high bulk phase conductivity, as the filler, synergistically improves the conductivity of the electrolyte layer.

[0054] The mass of the porous framework layer and the electrolyte filled in the pores thereof in the all-solid-state sulfide electrolyte layer is not limited, as long as the amount of the electrolyte is sufficient to fill the porous framework layer. However, the mass ratio of the two affects the conductivity of the all-solid-state sulfide electrolyte layer. In a preferred embodiment of the present application, the mass ratio of the porous framework layer to the electrolyte is 1:(1.5-4.5).

[0055] It is understandable that the mass of the electrolyte in the pores varies with the size and morphology of the pores, and therefore, the porosity of the porous framework layer affects the filling amount and filling effect of the electrolyte. In a preferred embodiment of the present application, the porosity of the porous framework layer is 65-80%.

[0056] In the present application, the size and thickness of the all-solid-state sulfide electrolyte layer are not limited, and can be determined according to the conventional methods in the art. In a preferred embodiment of the present application, the thickness of the all-solid-state sulfide electrolyte layer is 45-55 μm, for example, 50 μm.

[0057] Method for preparing the all-solid-state sulfide electrolyte layer

[0058] In an embodiment of the present application, a method for preparing the all-solid-state sulfide electrolyte layer is also provided, which comprises the steps of:

[0059] porous framework layer is obtained by porosifying the sulfide electrolyte material;

[0060] The electrolyte solution is poured on the porous framework layer, and the solvent in the electrolyte solution is removed.

[0061] The types of the sulfide electrolyte material and the electrolyte in the electrolyte solution are as described above. In a preferred embodiment of the present application, the sulfide electrolyte material is Li6PS5Cl, Li 10 SnPS 12 , Li6PS5Br or Li 10 GeP2S 12 ; and the electrolyte is selected from Li6PS5Cl, Li 10 SnPS 12 , Li6PS5Br and Li 10GeP2S 12 at least one of the group consisting of Li, Na, K, Rb, Cs, and Fr.

[0062] As a method for removing solvent from the electrolyte solution, vacuum drying, high-temperature treatment, and flat-plate hot-pressing treatment can be used. In a preferred embodiment of the present application, the electrolyte solution is cast on the porous framework layer, and then vacuum drying, high-temperature treatment, and flat-plate hot-pressing treatment are performed, thereby obtaining the all-solid-state sulfide electrolyte layer.

[0063] In some preferred embodiments, the high-temperature treatment is performed in a muffle furnace.

[0064] In some preferred embodiments, the high-temperature treatment is performed at a temperature of 500 to 600°C; for example, at 550°C.

[0065] In some preferred embodiments, the flat-plate hot-pressing treatment is performed at a pressure of 5 to 10 MPa.

[0066] The flat-plate hot-pressing treatment is performed for a time of 100 to 150 minutes; for example, for 120 minutes.

[0067] The flat-plate hot-pressing treatment is performed at a temperature of 70 to 80°C; for example, at 75°C.

[0068] Preparation of the porous framework layer

[0069] The porous framework layer described above is preferably prepared by a method comprising the steps of:

[0070] A sulfide electrolyte slurry containing a pore-forming agent is coated on a current collector, and then roll-pressed and vacuum-dried until the sulfide electrolyte slurry is solidified, and the sulfide electrolyte slurry is separated from the current collector, thereby obtaining the porous framework layer.

[0071] The type of pore-forming agent affects the morphology of the pores. In a preferred embodiment of the present application, selenium disulfide is used as the pore-forming agent, and the size and morphology of the pores of the obtained porous framework layer are more uniform, and the conductivity of the obtained all-solid-state sulfide electrolyte layer is higher.

[0072] To obtain a porous framework layer having pores of uniform size, the mass ratio of the sulfide electrolyte material to the pore-forming agent in the sulfide electrolyte slurry containing a pore-forming agent is preferably 3: 1 to 1:3, preferably 2: 1 to 1: 1, for example, 1.5 to 1.

[0073] The sulfide electrolyte containing a pore-forming agent can be obtained by adding a pore-forming agent to a sulfide electrolyte slurry by a conventional method. In some preferred embodiments of the present application, the preparation of the sulfide electrolyte slurry containing a pore-forming agent comprises the steps of:

[0074] The sulfide electrolyte material and the pore-forming agent are mixed, and stirring is performed using a Thinky debubbling stirrer, to thereby obtain the sulfide electrolyte slurry containing the pore-forming agent.

[0075] In order to make the prepared porous framework layer have pores of uniform size, in some preferred embodiments, the stirring procedure includes a first stirring stage and a second stirring stage, the rotation speed Rev1 of the first stirring stage being higher than the rotation speed Rev2 of the second stirring stage. In some more preferred embodiments, the first stirring stage is performed at the rotation speed Rev1 for t1 minutes, and the second stirring stage is performed at the rotation speed Rev2 for t2 minutes.

[0076] wherein Rev1 is 1800-2200 rpm, t1 is 9-11 minutes,

[0077] Rev2 is 400-600 rpm, and t1 is 4-6 minutes.

[0078] Preparation of electrolyte solution

[0079] The electrolyte and the solvent are mixed, to thereby obtain the electrolyte solution. The solvent is preferably ethanol. In some preferred embodiments of the present application, the solid content of the electrolyte solution is 40-60%, for example 50%. When the amount of electrolyte exceeds the upper limit of the amount of electrolyte that can be dissolved in the solvent, part of the electrolyte cannot be dissolved in the solvent, i.e. exists in the form of a solid to form a slurry, and the solid content can be used to indicate the proportion of the mass of the part of the electrolyte that is not dissolved in the solvent to the total mass.

[0080] Solid-state lithium ion battery

[0081] In the present application, the solid-state lithium ion battery is not specially limited in the other components thereof except the electrolyte layer, and the components are prepared according to the methods commonly used in the art.

[0082] In one embodiment of the present application, the solid-state lithium ion battery comprises:

[0083] a positive electrode;

[0084] a negative electrode;

[0085] a full-solid sulfide electrolyte layer between the positive electrode and the negative electrode.

[0086] As the positive electrode, a positive electrode active material is included, and the positive electrode active material can be used, non-limitingly, for example, a transition metal-containing lithium oxide (LiCoO2, LiNiO2, LiNi0.8Co0.15Al0.05O2, LiNi0.33Co0.33Mn0.33O2, LiMn2O4) or a sulfur-containing compound (TiS2, MoS2).

[0087] As the positive electrode, a positive electrode active material is included, and as the positive electrode active material, for example, non-limiting examples include lithium metal, lithium alloy (Li-In, Li-Si, LiAl), or graphite.

[0088] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the present application will be further described below with reference to specific examples. It should be understood that these examples are only used to illustrate but not to limit the scope of the present application. The experimental methods in the following examples, if no specific conditions are indicated, are generally carried out according to the conventional conditions or the conditions recommended by the manufacturers. Unless otherwise specified, percentages and parts are weight percentages and weight parts. The experimental materials and reagents used in the following examples, if no specific instructions are given, can be obtained from the market.

[0089] Unless otherwise indicated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should be noted that the terms used herein are only for the purpose of describing the specific embodiments and are not intended to limit the exemplary embodiments of the present application.

[0090] In the present application, the preparation of the all-solid-state sulfide electrolyte layer is carried out in an argon glove box with water ≤ 0.1 ppm, oxygen ≤ 0.1 ppm, and carbon dioxide ≤ 0.1 ppm. Before the experimental operation, all materials are first dehydrated to ensure that the water content of the materials is ≤ 10 ppm.

[0091] Example 1. Preparation of Li6PS5Br skeleton pouring Li6PS5Br solution all-solid-state sulfide electrolyte layer

[0092] Step 1, preparation of lithium phosphorus sulfur bromide sulfide electrolyte skeleton

[0093] Mix 7 g of lithium phosphorus sulfur bromide (Li6PS5Br) electrolyte material with a mass fraction of 50% and 5 g of selenium disulfide with a mass fraction of 50%, use dimethyl carbonate as the solvent, the solid content is about 50-60%, use a Thinky defoaming stirrer to stir at 2000 rpm for 10 min, and then stir at 500 rpm for 5 min; uniformly coat the mixed sulfide electrolyte slurry on an aluminum foil with a coating gap of 100 microns, and vacuum dry the coated material at room temperature; roll the previously prepared sulfide electrolyte layer to a thickness of about 50 microns; then vacuum dry at 150°C, in this process SeS2 is completely volatilized, the electrolyte layer has a uniform pore structure three-dimensional structure, and the porosity of the lithium phosphorus sulfur bromide sulfide electrolyte layer is calculated by weighing.

[0094] Step 2, pouring electrolyte solution into lithium phosphorus sulfur bromide sulfide electrolyte skeleton

[0095] Li6PS5Br 6.5g mass is dissolved in an ethanol solution to form a Li6PS5Br ethanol solution with a solid content of about 50%; the Li6PS5Br ethanol solution is cast on the electrolyte layer according to the pore volume, so that the Li6PS5Br ethanol solution penetrates into the electrolyte layer.

[0096] Step 3, preparation of the all-solid-state sulfide electrolyte layer

[0097] The electrolyte layer on which the Li6PS5Br ethanol solution is cast is further vacuum dried at 150°C for 12 hours to ensure that the ethanol in the electrolyte layer has been completely removed; the electrolyte layer is clamped with a clamp and placed in a muffle furnace in an argon environment for sintering at 550°C, and the muffle furnace is naturally cooled to room temperature after sintering; the electrolyte layer is taken out and sealed, and the sealed aluminum plastic film is taken out of the glove box for flat plate hot pressing treatment, with a flat plate hot pressing pressure of 5-10 MPa, a time of 120 min, and a temperature of 75°C, and the flat plate hot pressing machine is taken out after completion.

[0098] To explore the effects of different sulfide framework materials and cast electrolyte solutions on the performance of the obtained all-solid-state sulfide electrolyte layer, different all-solid-state sulfide electrolyte layers are prepared in Examples 2 to 4 of the present application by changing the combination of the sulfide framework layer and the electrolyte solution, and the preparation method is substantially the same as that of Example 1, except that the electrolyte framework material and the cast electrolyte solution are different. See Table 1 for details.

[0099] Example 2. Preparation of an all-solid-state sulfide electrolyte layer of a Li6PS5Cl framework cast with a Li6PS5Br solution

[0100] Step 1, preparation of a lithium phosphorus sulfide chloride electrolyte framework

[0101] 7g of lithium phosphorus sulfide chloride (Li6PS5Cl) electrolyte material with a mass fraction of 50% and 5g of selenium disulfide with a mass fraction of 50% are mixed, dimethyl carbonate is used as a solvent, the solid content is about 50-60%, a Thinky defoaming stirrer is used for stirring at 2000rmp for 10min, and then at 500rmp for 5min; the mixed sulfide electrolyte slurry is uniformly coated on an aluminum foil with a coating gap of 100 microns, and the coated material is vacuum dried at room temperature; the previously prepared sulfide electrolyte layer is rolled to a thickness of about 50 microns; then vacuum dried at 150°C, during which SeS2 is completely volatilized, and a three-dimensional structure with a uniform pore structure is formed in the electrolyte layer, and the porosity of the lithium phosphorus sulfide chloride electrolyte layer is calculated by weighing.

[0102] Step 2, casting of the electrolyte solution on the lithium phosphorus sulfide chloride electrolyte framework

[0103] Li6PS5Br 6.5 g is dissolved in ethanol solution to form Li6PS5Br ethanol solution with a solid content of about 50%; the Li6PS5Br ethanol solution is cast on the electrolyte layer according to the pore volume, so that the Li6PS5Br ethanol solution penetrates into the electrolyte layer.

[0104] Step 3, preparation of the full solid sulfide electrolyte layer

[0105] The electrolyte layer on which the Li6PS5Br ethanol solution is cast is further vacuum dried at 150°C for 12 hours to ensure that the ethanol in the electrolyte layer has been completely removed; the above electrolyte layer is clamped with a clamp and placed in a muffle furnace in an argon environment for sintering at 550°C, and the muffle furnace is naturally cooled to room temperature after sintering; the electrolyte layer is taken out and sealed, and the sealed aluminum plastic film is taken out of the glove box for flat plate hot pressing treatment, with a flat plate hot pressing pressure of 5-10 MPa, a time of 120 min, and a temperature of 75°C, and the full solid sulfide electrolyte layer is obtained after being taken out of the flat plate hot pressing machine.

[0106] Example 3. Preparation of Li6PS5Cl framework cast Li6PS5Cl solution full solid sulfide electrolyte layer

[0107] Step 1, preparation of Li6PS5Cl sulfide electrolyte framework

[0108] Li6PS5Cl electrolyte material 7 g with a mass fraction of 50% and selenium disulfide 5 g with a mass fraction of 50% are mixed, dimethyl carbonate is used as a solvent, the solid content is about 50-60%, a Thinky defoaming stirrer is used for stirring at 2000 rpm for 10 min, and then defoaming stirring is performed at 500 rpm for 5 min; the mixed sulfide electrolyte slurry is uniformly coated on an aluminum foil with a coating gap of 100 microns, and the coated material is vacuum dried at room temperature; the previously prepared sulfide electrolyte layer is rolled to a thickness of about 50 microns; then vacuum drying is performed at 150°C, during which SeS2 is completely volatilized, and a three-dimensional structure with a uniform pore structure is formed in the electrolyte layer, and the porosity of the Li6PS5Cl sulfide electrolyte layer is calculated by weighing.

[0109] Step 2, casting of electrolyte solution on lithium phosphorus sulfide chloride sulfide electrolyte framework

[0110] Li6PS5Cl 6.5 g is dissolved in ethanol solution to form Li6PS5Cl ethanol solution with a solid content of about 50%; the Li6PS5Cl ethanol solution is cast on the electrolyte layer according to the pore volume, so that the Li6PS5Cl ethanol solution penetrates into the electrolyte layer.

[0111] Step 3, preparation of the full solid sulfide electrolyte layer

[0112] The electrolyte layer with Li6PS5Cl ethanol solution is dried at 150°C under vacuum for 12 hours to ensure that the ethanol in the electrolyte layer is completely removed; the electrolyte layer is clamped with a clamp and placed in a muffle furnace in an argon environment for sintering at 550°C, and the muffle furnace is naturally cooled to room temperature after sintering; the electrolyte layer is taken out and sealed, and the sealed aluminum plastic film is taken out of the glove box for flat plate hot pressing treatment, the flat plate hot pressing pressure is 5-10 MPa, the time is 120 min, and the temperature is 75°C, and the flat plate hot pressing machine is taken out after completion.

[0113] Example 4. Li 10 SnPS 12 Preparation of Li6PS5Br solution full solid-state sulfide electrolyte layer

[0114] Step 1, Li 10 SnPS 12 Preparation of sulfide electrolyte skeleton

[0115] The mass fraction of Li 10 SnPS 12 (LSnPS) electrolyte material 7g, mass fraction of selenium disulfide 5g, dimethyl carbonate as solvent, solid content about 50-60%, using Thinky defoaming stirrer 2000rmp stirring 10min, then 500rmp defoaming stirring 5min; the mixed sulfide electrolyte slurry is uniformly coated on the aluminum foil, the coating gap is 100 microns, and the material is dried at room temperature after coating; the previously prepared sulfide electrolyte layer is rolled to a thickness of about 50 microns; then vacuum dried at 150°C, in this process SeS2 completely volatilizes, the electrolyte layer forms a three-dimensional structure with uniform pore structure inside, by weighing, the mass of Li 10 SnPS 12 Pore rate of sulfide electrolyte layer.

[0116] Step 2, Li 10 SnPS 12 Sulfide electrolyte skeleton pouring electrolyte solution

[0117] Li6PS5Br 6.5g is dissolved in ethanol solution to form Li6PS5Br ethanol solution, and the solid content is about 50%; according to the pore volume, Li6PS5Br ethanol solution is poured into the electrolyte layer, so that the Li6PS5Br ethanol solution penetrates into the electrolyte layer.

[0118] Step 3, preparation of full solid-state sulfide electrolyte layer

[0119] The electrolyte layer with the cast Li6PS5Br ethanol solution is vacuum dried at 150℃ for 12 hours to ensure that the ethanol in the electrolyte layer is completely removed; the electrolyte layer is clamped with a clamp and placed in a muffle furnace in an argon environment for sintering at 550℃, and the muffle furnace is naturally cooled to room temperature after sintering; the electrolyte layer is taken out and sealed, and the sealed aluminum plastic film is taken out of the glove box for flat plate hot pressing treatment, with a flat plate hot pressing pressure of 5-10 MPa, a time of 120 min, and a temperature of 75℃, and the flat plate hot pressing machine is taken out after completion to obtain the full solid-state sulfide electrolyte layer.

[0120] Table 1

[0121]

[0122]

[0123] To explore the influence of different proportions of sulfide skeleton layer and cast electrolyte solution on the performance of the obtained full solid-state sulfide electrolyte layer, different full solid-state sulfide electrolyte layers were prepared in Examples 5 to 7 of the present application by changing the mass ratio of the sulfide skeleton layer and the electrolyte solution, and the preparation method was substantially the same as that of Example 2, except that the mass ratio of the electrolyte skeleton material and the cast electrolyte solution was different. See Table 2 for details.

[0124] Table 2

[0125] No. Sulfide skeleton material mass: electrolyte solution solute and solid mass Porosity Example 2 3.5:6.5 72.4％ Example 5 3.0:7.0 75.3％ Example 6 2.5:7.5 77.7％ Example 7 2.0:8.0 80.1％

[0126] Comparative Example 1, preparation of a full solid-state sulfide electrolyte layer by dry mixing method

[0127] The raw materials including 7g of lithium phosphorus sulfur chloride (Li6PS5Cl) electrolyte material with a mass fraction of 50% and 5g of lithium phosphorus sulfur bromide (Li6PS5Br) electrolyte material with a mass fraction of 50% and 5g of pore-forming agent selenium disulfide were vacuum dried at a drying temperature of 50-100℃ for 6-20h; under an inert atmosphere, the dried raw materials were weighed according to the metering ratio, mixed and ground to obtain a mixed powder; the mixed powder was transferred to a high-pressure reaction kettle, and after adding a solvent, the reaction kettle was sealed and placed in a muffle furnace for heat treatment; after cooling, acetone was added to precipitate the solids, the powder was filtered out, washed with ethanol, and vacuum dried to obtain a preliminary material; the preliminary material was heat treated under an inert atmosphere to obtain a final product; the heat treatment temperature was 200-500℃, and the holding time was 1-3h.

[0128] Test Example, performance test of full solid-state sulfide electrolyte layer

[0129] The full solid-state sulfide electrolyte layers prepared in the above examples were tested for room temperature ionic conductivity, direct current polarization electronic conductivity and electrolyte layer electrochemical window according to the steps described below, and the results are recorded in Table 3.

[0130]

Room temperature ionic conductivity test

[0131] The prepared composite all-solid sulfide electrolyte layer was punched in a glove box, and a mold cell was used for conductivity test. The test conditions were: diameter 10 mm, test pressure 50 Mpa, at room temperature 23±2℃, the test was conducted using Bio-logic MTZ-35 impedance analyzer, frequency 3.5MHz-0.1Hz.

[0132]

Direct current polarization electronic conductivity test

[0133] In the glove box, at 25℃, using a mold cell, applying 50Mpa pressure, using blocking electrodes (electron conduction, ion blocking) at both ends, clamping the sulfide electrolyte layer in the middle, starting to apply a constant voltage of 0.5V direct current polarization for 3000s, recording the current after direct current for 3000s, electronic resistance = constant voltage / direct current after current, then the electronic conductivity can be calculated through the conductivity test formula.

[0134]

Electrolyte layer electrochemical window test

[0135] At 25℃, in the glove box, assemble Li|sulfide electrolyte layer|SUS button cell, one side is a lithium ion blocking electrode stainless steel sheet; one side is a lithium ion reversible electrode lithium copper composite tape; the middle is a sulfide solid electrolyte layer. The cyclic voltammetry scanning voltage is first scanned from open circuit voltage to-0.5V, and then from-0.5V to 10V, so on, the scanning speed is 0.5mV / s, and the starting oxidation current position of the battery is confirmed.

[0136] Table 3

[0137]

[0138] It can be understood by those skilled in the art that the above-mentioned embodiments are specific examples for implementing the present application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the present application.

Claims

1. An all-solid-state sulfide electrolyte layer, characterized by, The all-solid-state sulfide electrolyte layer comprises a porous framework layer and an electrolyte filled in the pores of the porous framework layer. The porous framework layer is obtained by pore-forming on a sulfide electrolyte material. The sulfide electrolyte material is Li6PS5Cl, Li 10 SnPS 12 , Li6PS5Br or Li 10 GeP2S 12 ; The electrolyte is selected from at least one of Li6PS5CI, Li 10 SnPS 12 , Li6PS5Br and Li 10 GeP2S 12 .

2. The all-solid-state sulfide electrolyte layer according to claim 1, characterized by, The sulfide electrolyte material is Li6PS5Br, and the electrolyte is Li6PS5Br; or The sulfide electrolyte material is Li6PS5Cl, and the electrolyte is Li6PS5Br.

3. The all-solid-state sulfide electrolyte layer according to claim 1, characterized by, The porosity of the porous framework layer is 65-80%.

4. The all-solid-state sulfide electrolyte layer according to claim 1, characterized by, The mass ratio of the porous framework layer to the electrolyte is 1:(1.5-4.5).

5. A method for producing an all-solid-state sulfide electrolyte layer, characterized by, The method comprises the steps of: pore-forming on a sulfide electrolyte material to obtain a porous framework layer; pouring an electrolyte solution on the porous framework layer, and then performing vacuum drying, high-temperature treatment and flat-plate hot-pressing treatment to obtain the all-solid-state sulfide electrolyte layer; wherein the sulfide electrolyte material is Li6PS5Cl, Li 10 SnPS 12 , Li6PS5Br or Li 10 GeP2S 12 ; The electrolyte is selected from at least one of Li6PS5CI, Li 10 SnPS 12 , Li6PS5Br and Li 10 GeP2S 12 .

6. The method of claim 5, wherein, The preparation of the porous framework layer comprises the steps of: coating a sulfide electrolyte slurry containing a pore-forming agent on a current collector, and then performing rolling and vacuum drying until the sulfide electrolyte slurry is solidified, and separating the sulfide electrolyte slurry from the current collector to obtain the porous framework layer.

7. The method of claim 6, wherein, In the sulfide electrolyte slurry containing a pore-forming agent, the mass ratio of the sulfide electrolyte material to the pore-forming agent is 3:1-1:

3.

8. A solid-state lithium-ion battery, characterized by, The solid-state lithium ion battery comprises the all-solid-state sulfide electrolyte layer according to any one of claims 1-4.

9. A method of increasing the electrical conductivity of a solid sulfide electrolyte layer, characterized by, The method comprises the steps of: constructing the sulfide electrolyte layer in a manner that the electrolyte is filled in a porous framework layer; wherein the porous framework layer is obtained by pore-forming on a sulfide electrolyte material. The sulfide electrolyte material is Li6PS5Cl, Li 10 SnPS 12 , Li6PS5Br or Li 10 GeP2S 12 ; and The electrolyte is selected from at least one of Li6PS5CI, Li 10 SnPS 12 , Li6PS5Br and Li 10 GeP2S 12 .

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