A solid electrolyte membrane, its preparation method and application

Abstract

The present invention provides a solid electrolyte membrane, a preparation method and an application thereof. The raw materials for preparing the solid electrolyte membrane include the following components in percentage by weight: 0.05-20% of a lithiated polymer, 40-99.9% of an inorganic solid electrolyte, and 0.05-59.95% of a fibrillatable polymer. In the present invention, a coated structure is formed by using the lithiated polymer and the inorganic solid electrolyte, and the inorganic solid electrolyte is coated in the lithiated polymer, avoiding the direct contact between the inorganic solid electrolyte and the positive and negative electrode materials, and effectively improving the electrochemical stability problem of the solid electrolyte material and the positive and negative electrode materials; at the same time, during the film-forming process, the adhesion ability between the polymer layer on the surface of the inorganic solid electrolyte and the polymer fibers is much higher than the adhesion ability between the inorganic solid electrolyte and the polymer fibers, increasing the dry film-forming property and being beneficial to improving the mechanical properties of the film.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and relates to a solid electrolyte membrane, a preparation method thereof, and an application thereof. Background Art

[0002] As an important part of current clean energy, lithium-ion batteries have been widely used in various 3C products and electric vehicles, which is an effective way to reduce the dependence on petrochemical energy. As people's requirements for the performance of lithium-ion batteries are getting higher and higher, it is urgent to improve their energy density and solve the safety problems of traditional liquid lithium-ion batteries, such as flammability and even explosion. Therefore, the research on developing all-solid-state lithium-ion batteries by using solid electrolytes to replace liquid electrolytes has naturally become a global hot topic.

[0003] The solid electrolyte membrane is a key component of all-solid-state lithium-ion batteries, which has the functions of isolating the positive and negative electrodes and providing a lithium-ion transmission channel. Therefore, developing a solid electrolyte membrane with excellent performance and reducing its production cost is one of the main research goals of future all-solid-state lithium-ion batteries.

[0004] Currently, most of the existing composite solid electrolyte membranes are composed of polymers and lithium salts. Although the addition of lithium salts can improve the ionic conductivity of the electrolyte, the addition of lithium salts will cause the polymer to become amorphous, reduce the melting point of the polymer, and also affect the working temperature range and mechanical properties of the electrolyte. There are also some composite electrolyte membranes that use polymers and lithium salts as the main body, and add a small amount of inorganic additives such as oxide / sulfide solid electrolytes to increase the amorphous region of the polymer to improve the performance, but still cannot solve the problem of poor mechanical properties. At the same time, most of the above methods use wet processes, and the wet processes are generally more complex, requiring a lot of time and effort to screen solvents, and the process control is difficult and the cost is high. CN111916633A discloses a dry process for preparing an electrolyte membrane, in which a fibrillatable polymer is sheared at a high speed to make it fibrillate under the shearing force, and then hot-pressed into a film to form a polymer network with rich pores, and the solid electrolyte is dispersed and bonded therein to obtain the electrolyte membrane. Although this invention can indeed solve some problems faced by wet film formation by means of dry film formation, it fails to solve problems such as the electrochemical stability between the electrolyte membrane and the positive and negative electrode materials. For example, the instability between metallic lithium and the electrolyte results in low interfacial charge transfer kinetics, and some sulfides even easily cause the generation of lithium dendrites. At the same time, the mechanical properties of the electrolyte membrane obtained by this method are poor. Generally, a method of increasing the polymer content is adopted to improve the mechanical properties of the electrolyte membrane, and the electrolyte membrane with a high polymer content has disadvantages such as poor ionic conductivity and low electrochemical window.

[0005] Therefore, there is an urgent need to develop a solid electrolyte membrane with excellent electrochemical stability and mechanical properties. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a solid electrolyte membrane, a preparation method thereof, and an application thereof. The solid electrolyte membrane of the present invention effectively improves the electrochemical stability problem between the solid electrolyte material and the positive and negative electrode materials, and has good mechanical properties.

[0007] To achieve the purpose of this invention, the following technical solutions are adopted:

[0008] On the one hand, the present invention provides a solid electrolyte membrane, and the preparation raw materials of the solid electrolyte membrane include the following components in weight percentages:

[0009] Lithiated polymer: 0.05 - 20%

[0010] Inorganic solid electrolyte: 40 - 99.9%

[0011] Fibrable polymer: 0.05 - 59.95%.

[0012] In the present invention, the solid electrolyte membrane is obtained by coating the inorganic solid electrolyte with the lithiated polymer and then mixing it with the fibrable polymer to form a film.

[0013] In the present invention, a coating structure is formed by using the lithiated polymer and the inorganic solid electrolyte, and the inorganic solid electrolyte is coated in the lithiated polymer, avoiding the direct contact between the inorganic solid electrolyte and the positive and negative electrode materials, and effectively improving the electrochemical stability problem between the solid electrolyte material and the positive and negative electrode materials; at the same time, during the film-forming process, the adhesion ability between the polymer layer on the surface of the inorganic solid electrolyte and the polymer fibers is much higher than the adhesion ability between the inorganic solid electrolyte and the polymer fibers, increasing the dry film-forming property and being beneficial to improving the mechanical properties of the film.

[0014] In the present invention, the weight percentage of the lithiated polymer in the preparation raw materials of the solid electrolyte membrane can be 0.05%, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 28%, 30%, 35%, 38% or 40%. If the weight percentage of the lithiated polymer is less than 0.05%, too little polymer electrolyte will affect the coating effect of the polymer on the inorganic solid electrolyte. If its weight percentage is greater than 40%, excessive coating of a large amount of polymer solid electrolyte will occur, resulting in the formation of a film between the polymer solid electrolyte and the inorganic solid electrolyte, and it will be unable to form a film with the fibrable polymer again, and at the same time, it will also affect the working temperature range of the battery.

[0015] In the present invention, the weight percentage of the inorganic solid electrolyte in the raw materials for preparing the solid electrolyte membrane can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 63%, 65%, 68%, 70%, 73%, 75%, 78%, 80%, 85%, 88%, 90%, 93%, 95%, 99%, etc. If the weight percentage of the inorganic solid electrolyte is less than 20%, the ionic conductivity of the composite solid electrolyte membrane will be affected.

[0016] In the present invention, the weight percentage of the fibrillatable polymer in the raw materials for preparing the solid electrolyte membrane can be 0.05%, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 28%, 30%, 35%, 38%, 40%, 50%, 55%, 60%, 65%, 70%, 75%, 79%, etc. If the weight percentage of the fibrillatable polymer is less than 0.05%, the fibrillatable polymer will not be able to adhere the inorganic solid electrolyte, thus affecting the mechanical properties of the composite solid electrolyte membrane. If its weight percentage is greater than 79.95%, the mechanical properties of the composite solid electrolyte membrane will increase significantly, but its ionic conductivity will be severely affected.

[0017] Preferably, the lithiated polymer is at least one of the following lithiated compounds: polyphenylene sulfide (PPS), polysulfide or polythiocarbamide, preferably polyphenylene sulfide.

[0018] Preferably, the inorganic solid electrolyte includes at least one of an oxide solid electrolyte and a sulfide solid electrolyte.

[0019] Preferably, the oxide solid electrolyte includes at least one of a garnet-type solid electrolyte, a NASICON-type solid electrolyte or a perovskite-type solid electrolyte.

[0020] Preferably, the garnet-type solid electrolyte is a cation-doped cubic phase Li7La3Zr2O 12 (LLZO), and its chemical formula can be respectively expressed as Li 7-3x-y+z A x La3Zr 2-y B y O 12+z / 2 or Li 7-3x-2k+z A x La3Zr 2-k C k O 12+z / 2 , where A is a trivalent metal element, B is a pentavalent metal element, C is a hexavalent metal element, 0 ≤ x ≤ 0.4, 0 ≤ y ≤ 1, 0 ≤ k ≤ 0.7, 0 ≤ z ≤ 1.4, A is Al and / or Ga, B is Ta and / or Nb, C is W and / or Te.

[0021] Preferably, the NASICON type solid electrolyte is Li 1+x Al x Ti 2-x (PO4)3(LATP) or Li 1+y Al y Ge 2-y (PO4)3(LAGP), 0.2≤x≤0.6, 0.2≤y≤0.6.

[0022] Preferably, the perovskite solid electrolyte is Li3xLa 2 / 3-x TiO3(LLTO), 0.04<x<0.17.

[0023] Preferably, the sulfide solid electrolyte includes at least one of a binary Li2S-P2S5 system sulfide solid electrolyte, a thio-LISICON type sulfide solid electrolyte or an argyrodite type sulfide solid electrolyte.

[0024] Preferably, the chemical formula of the Li2S-P2S5 system sulfide and the argyrodite-type sulfide can be expressed as xLi2S·(100-xz)A y S n ·zB,0 <x<100,y为0、1或2,n为2y或2y+1,0≤z<100-x,A为B 3+ , P 3+ , P 5+ 、Si 4+ Or Ge 4+ , B is LiCl, LiBr, LiI, P2O5, GeS2, Li3PO4, Li4SiO4 or P2S3.

[0025] Preferably, the chemical formula of the thio-LISICON type sulfide solid electrolyte is Li 4-x A 1-y B y S4 or Li 10+ z K l+z P 2-z S 12 , A is selected from one of Si and Ge, B is selected from one of Al, P, Zn, and Ga, 0≤x≤2, 0≤y≤1, K is selected from one or at least two of the third, fourth, or fifth main group elements, 0≤z≤1.

[0026] Preferably, the fiberizable polymer includes at least one of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), polyacrylic acid (PAA), polyimide (PI) or styrene-butadiene rubber (SBR), but is not limited to the substances listed above. Other fiberizable polymers can also be used in the present invention, and polytetrafluoroethylene is most preferred.

[0027] Preferably, the solid electrolyte membrane has a thickness of 15 μm-100 μm, for example, 15 μm, 30 μm, 50 μm, 70 μm, 80 μm, 90 μm, 95 μm or 100 μm.

[0028] In a second aspect, the present invention provides a method for preparing the solid electrolyte membrane as described above, the preparation method comprising the following steps:

[0029] (1) grinding and mixing the lithiated polymer and the inorganic solid electrolyte so that the lithiated polymer coats the inorganic solid electrolyte to obtain a composite solid electrolyte powder;

[0030] (2) shearing and mixing the fiberizable polymer and the composite solid electrolyte powder to obtain a mixture;

[0031] (3) The mixed material of step (2) is subjected to hot pressing to obtain the solid electrolyte membrane.

[0032] Preferably, the lithiated polymer in step (1) is obtained by thoroughly mixing the polymer with a lithium salt.

[0033] Preferably, the rotation speed of the grinding and mixing in step (1) is 50rpm-300rpm (for example, 50rpm, 60rpm, 80rpm, 100rpm, 130rpm, 150rpm, 200rpm, 250rpm or 300rpm), and the time is 5min-30min (for example, 5min, 8min, 10min, 15min, 18min, 20min, 25min, 28min or 30min).

[0034] Preferably, the rotation speed of the shear mixing in step (2) is 1000rpm-30000rpm (for example, 1000rpm, 3000rpm, 5000rpm, 8000rpm, 10000rpm, 13000rpm, 15000rpm, 18000rpm, 20000rpm, 25000rpm, 28000rpm or 30000rpm), and the time is 0.5min-60min (for example, 1min, 5min, 8min, 10min, 20min, 30min, 40min, 50min or 60min).

[0035] In the present invention, the equipment used for the grinding and mixing in step (1) includes one of a high-speed mixer, a jet mill, a high-speed disperser, and a ball mill, but is not limited to the equipment listed above. Other equipment that can achieve the coating effect can also be used in the present invention. Most preferably, it is a high-speed mixer.

[0036] The equipment for the shearing and mixing in step (2) can be a high-speed disperser, a jet mill, a ball mill, etc.

[0037] In the present invention, grinding and mixing and shearing and mixing are different processes. The grinding and mixing has a small rotation speed and low energy. Shearing and mixing refers to high-speed shearing, with a fast speed and high energy. Grinding is to coat the polymer on the surface of the inorganic solid electrolyte, while using high-speed shearing will damage the structure of the polymer and is not conducive to the coating process; shearing is to fibrillate the fibrillatable polymer, and a low speed will result in a poor fibrillation effect or no fibrillation at all.

[0038] Preferably, the hot pressing treatment in step (3) is hot roll pressing.

[0039] Preferably, the temperature of the hot pressing treatment in step (3) is 20°C - 250°C (such as 20°C, 25°C, 30°C, 40°C, 50°C, 70°C, 90°C, 100°C, 130°C, 150°C, 180°C, 200°C, 220°C, 240°C, etc.), preferably 70°C - 140°C.

[0040] In the preparation method of the solid electrolyte membrane of the present invention, the polymer solid electrolyte and the inorganic solid electrolyte are simply dry-mixed and mechanically ground. By utilizing the ductility of the polymer solid electrolyte, the polymer solid electrolyte is coated on the surface of the inorganic solid electrolyte material, and then high-speed shearing and mixing with the fibrillatable polymer is carried out, and hot pressing is performed to form a film. Due to the introduction of the polymer solid electrolyte layer on the surface of the inorganic solid electrolyte in the preparation method of the present invention, the inorganic solid electrolyte is wrapped, avoiding the direct contact between the inorganic solid electrolyte and the positive and negative electrode materials, and effectively improving the electrochemical stability problem between the solid electrolyte material and the positive and negative electrode materials; at the same time, during the film-forming process, the adhesion ability between the polymer layer on the surface of the inorganic solid electrolyte and the polymer fiber is much higher than the adhesion ability between the inorganic solid electrolyte and the polymer fiber, increasing the dry film-forming property and being beneficial to improving the mechanical properties of the film; and no solvent is used during the preparation process, the preparation process is simple, and the cost is low.

[0041] On the other hand, the present invention provides a solid-state battery, and the solid-state battery includes the solid electrolyte membrane as described above.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] In the present invention, a coated structure is formed by using a lithiated polymer and an inorganic solid electrolyte, with the inorganic solid electrolyte coated in the lithiated polymer, avoiding direct contact between the inorganic solid electrolyte and the positive and negative electrode materials, effectively improving the electrochemical stability problem between the solid electrolyte material and the positive and negative electrode materials; meanwhile, during the film-forming process, the adhesion ability between the polymer layer on the surface of the inorganic solid electrolyte and the polymer fibers is much higher than that between the inorganic solid electrolyte and the polymer fibers, increasing the dry film-forming property and being beneficial to improving the mechanical properties of the film. The solid electrolyte membrane of the present invention used in a solid-state battery enables it to have excellent mechanical properties (tensile strength above 15 MPa) and cycling performance (number of cycles above 280 at 60 °C). The preparation method of the present invention uses no solvents, has a simple preparation process, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a flowchart for the preparation of the solid electrolyte membrane of the present invention.

[0045] Figure 2 It is a scanning electron microscope image of LATP (Li 1.3 Al 0.3 Ti 1.7 (PO4)3) coated with lithiated PPS. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0047] Example 1

[0048] In this example, a solid electrolyte membrane was prepared. The raw materials for preparing the solid electrolyte membrane included the following components in weight percentages: 1 wt% of lithiated PPS, 98.8 wt% of LPSC (Li5.4PS4.4Cl1.6), and 0.2 wt% of PTFE.

[0049] Among them, the lithiated PPS was obtained by fully mixing 33 wt% of the lithium salt LiTFSI and 67 wt% of PPS to obtain lithiated PPS.

[0050] The specific preparation process is as Figure 1 shown and includes the following steps:

[0051] S1. Weigh the raw materials according to the following ratio: 1 wt% of lithiated PPS, 98.8 wt% of LPSC (Li 5.4 PS 4.4 Cl 1.6 ) and 0.2 wt% of PTFE;

[0052] S2. Premix the lithiated PPS powder with the LPSC powder, and then put the premix into a high-speed mixer and mix at 300 r / min for 30 min to obtain a composite solid electrolyte powder.

[0053] S3. Place the PTFE powder and the composite solid electrolyte powder in proportion in a high-speed disperser and mix at 2500 r / min for 10 min to obtain a mixture.

[0054] S4. For the mixture described in step S3, in a roll press, the heating temperature of the roll press is 80 °C and the rotation speed is 6 rpm, and roll the powder material into a composite solid electrolyte membrane.

[0055] Example 2

[0056] In this example, a solid electrolyte membrane was prepared. The preparation raw materials of the solid electrolyte membrane included the following components in weight percentages: 4 wt% of lithiated PPS, 95 wt% of Li7P3S 11 and 1 wt% of PTFE.

[0057] Among them, the lithiated PPS was obtained by fully mixing 33 wt% of the lithium salt LiTFSI and 67 wt% of PPS to obtain lithiated PPS.

[0058] The specific preparation process included the following steps:

[0059] S1. Weigh the raw materials according to the following ratio: 4 wt% of lithiated PPS, 95 wt% of LPS (Li7P3S 11 ) and 1 wt% of PTFE;

[0060] S2. Premix the lithiated PPS powder with the LPS powder, and then put the premix into a medium-speed mixer and mix at 250 r / min for 30 min to obtain a composite solid electrolyte powder.

[0061] S3. Place the PTFE powder and the composite solid electrolyte powder in proportion in a high-speed disperser and stir at 10000 r / min for 20 min to obtain a mixture.

[0062] S4. For the mixture described in step S3, in a roll press, the heating temperature of the roll press is 100 °C and the rotation speed is 10 rpm, and roll the powder material into a composite solid electrolyte membrane.

[0063] Example 3

[0064] In this example, a solid electrolyte membrane was prepared. The preparation raw materials of the solid electrolyte membrane included the following components in weight percentages: 5 wt% of lithiated PPS, 90 wt% of LATP (Li 1.3 Al 0.3 Ti1.7 (PO4)3) and 5 wt% PTFE.

[0065] Among them, the lithiated PPS is obtained by fully mixing 33 wt% of the lithium salt LiTFSI and 67 wt% of PPS.

[0066] The specific preparation process includes the following steps:

[0067] S1. Weigh the raw materials according to the following ratio: 5 wt% of lithiated PPS, 90 wt% of LATP (Li 1.3 Al 0.3 Ti 1.7 (PO4)3) and 5 wt% PTFE;

[0068] S2. Premix the lithiated PPS powder and the LATP powder, and then put the premix into a planetary ball mill and mill it at 200 r / min for 30 min to obtain the composite solid electrolyte powder.

[0069] S3. Place the PTFE powder and the composite solid electrolyte powder in a high-speed disperser according to the ratio and stir it at 15000 r / min for 25 min to obtain the mixture.

[0070] S4. Roll the mixture described in step S3 in a roll press. The heating temperature of the roll press is 120 °C and the rotation speed is 8 rpm to roll the powder into a composite solid electrolyte membrane.

[0071] The composite solid electrolyte powder prepared in step S2 of this example was characterized by using Hitachi scanning electron microscope S4800. As Figure 2 shown, it can be seen that the lithiated PPS has completed a good coating on the LATP solid electrolyte particles of about 1 μm.

[0072] Example 4

[0073] In this example, a solid electrolyte membrane was prepared. The raw materials for preparing the solid electrolyte membrane include the following components by weight percentage: 20 wt% of lithiated polysulfide, 70 wt% of LLTO (Li 0.5 La 0.5 TiO3) and 10 wt% PTFE.

[0074] Among them, the lithiated polysulfide is obtained by fully mixing 33 wt% of the lithium salt LiTFSI and 67 wt% of polysulfide.

[0075] The specific preparation process includes the following steps:

[0076] S1. Weigh the raw materials according to the following ratio: 20 wt% of lithiated polysulfide, 70 wt% of LLTO (Li0.5 La 0.5 (LaTiO3) and 10 wt% PTFE;

[0077] S2. Premix the lithiated polysulfide powder and the LLTO powder, and then put the premix into a high-speed mixer and mix at 300 r / min for 20 min to obtain a composite solid electrolyte powder;

[0078] S3. Place the PTFE powder and the composite solid electrolyte powder in a high-speed disperser according to the ratio and ball mill at 1000 r / min for 30 min to obtain a mixture;

[0079] S4. Perform the mixture obtained in step S3 in a roll press. The heating temperature of the roll press is 125 °C and the rotation speed is 10 rpm to roll the powder into a composite solid electrolyte membrane.

[0080] Example 5

[0081] In this example, a solid electrolyte membrane was prepared. The raw materials for preparing the solid electrolyte membrane included the following components in weight percentages: 0.05 wt% lithiated PPS, 40 wt% LGPS (Li 10 GeP2S 12 ) and 59.95 wt% PTFE.

[0082] Among them, the lithiated PPS was obtained by fully mixing 33 wt% lithium salt LiTFSI and 67 wt% PPS to obtain lithiated PPS.

[0083] The specific preparation process included the following steps:

[0084] S1. Weigh the raw materials according to the following ratio: 0.05 wt% lithiated PPS, 40 wt% LGPS (Li 10 GeP2S 12 ) and 59.95 wt% PTFE;

[0085] S2. Premix the lithiated PPS powder and the LGPS powder, and then put the premix into a high-speed mixer and mix at 300 r / min for 20 min to obtain a composite solid electrolyte powder;

[0086] S3. Place the PTFE powder and the composite solid electrolyte powder in a high-speed disperser according to the ratio and stir at 12000 r / min for 15 min to obtain a mixture;

[0087] S4. Perform the mixture obtained in step S3 in a roll press. The heating temperature of the roll press is 135 °C and the rotation speed is 4 rpm to roll the powder into a composite solid electrolyte membrane.

[0088] Example 6

[0089] In this embodiment, a solid electrolyte membrane was prepared. The raw materials for preparing the solid electrolyte membrane included the following components in weight percentages: 20 wt% of lithiated PPS, 40 wt% of LGPS (Li 10 GeP2S 12 ) and 40 wt% of polyvinylidene fluoride (PVDF).

[0090] Among them, the lithiated PPS was obtained by fully mixing 33 wt% of the lithium salt LiTFSI and 67 wt% of PPS to obtain lithiated PPS.

[0091] The specific preparation process included the following steps:

[0092] S1. Weigh the raw materials according to the following ratio: 20 wt% of lithiated PPS, 40 wt% of Li3PS4, and 40 wt% of PVDF;

[0093] S2. Premix the lithiated PPS powder and the LGPS powder, and then put the premix into a high-speed mixer and mix at 300 r / min for 20 min to obtain a composite solid electrolyte powder;

[0094] S3. Place the PVDF powder and the composite solid electrolyte powder in a high-speed disperser according to the ratio and stir at 12,000 r / min for 15 min to obtain a mixed material;

[0095] S4. Roll the mixed material obtained in step S3 in a roll press. The heating temperature of the roll press is 135 °C and the rotation speed is 4 rpm to roll the powder into a composite solid electrolyte membrane.

[0096] Example 7

[0097] In this embodiment, a solid electrolyte membrane was prepared. The raw materials for preparing the solid electrolyte membrane included the following components in weight percentages: 40 wt% of lithiated PPS, 59.95 wt% of LATP (Li 1.4 Al 0.4 Ti 1.6 (PO4)3) and 0.05 wt% of PTFE.

[0098] Among them, the lithiated PPS was obtained by fully mixing 33 wt% of the lithium salt LiTFSI and 67 wt% of PPS to obtain lithiated PPS. The specific preparation process included the following steps:

[0099] S1. Weigh the raw materials according to the following ratio: 20 wt% of lithiated PPS, 79.95 wt% of LATP (Li 1.4 Al 0.4 Ti 1.6 (PO4)3) and 0.05 wt% of PTFE;

[0100] S2. Premix the lithiated PPS powder and LATP powder, and then put the premix into a planetary ball mill. Mill at 200 r / min for 30 min to obtain a composite solid electrolyte powder.

[0101] S3. Place the PTFE powder and the composite solid electrolyte powder in a high-speed disperser in proportion. Stir at 25,000 r / min for 30 min to obtain a mixture.

[0102] S4. Subject the mixture obtained in step S3 to a roll press. The heating temperature of the roll press is 130 °C and the rotation speed is 10 rpm to roll the powder into a composite solid electrolyte membrane.

[0103] Example 8

[0104] In this example, a solid electrolyte membrane was prepared. The raw materials for preparing the solid electrolyte membrane included the following components in weight percentages: 0.05 wt% of lithiated PPS, 99.9 wt% of LLZTO (Li 6.5 La3Zr 1.5 Ta 0.5 O 12 ) and 0.05 wt% of PTFE.

[0105] Among them, the lithiated PPS was obtained by fully mixing 33 wt% of the lithium salt LiTFSI and 67 wt% of PPS. The specific preparation process included the following steps:

[0106] S1. Weigh the raw materials according to the following ratio: 0.05 wt% of lithiated PPS, 99.9 wt% of LLZTO (Li 6.5 La3Zr 1.5 Ta 0.5 O 12 ) and 0.05 wt% of PTFE;

[0107] S2. Premix the lithiated PPS powder and LLZTO powder, and then put the premix into a planetary ball mill. Mill at 100 r / min for 10 min to obtain a composite solid electrolyte powder.

[0108] S3. Place the PTFE powder and the composite solid electrolyte powder in a high-speed disperser in proportion. Stir at 21,000 r / min for 30 min to obtain a mixture.

[0109] S4. Subject the mixture obtained in step S3 to a roll press. The heating temperature of the roll press is 125 °C and the rotation speed is 5 rpm to roll the powder into a composite solid electrolyte membrane.

[0110] Comparative Example 1

[0111] This comparative example prepared a composite solid electrolyte, which was different from that in Example 1 in that: in this comparative example, the inorganic solid electrolyte LPSC in Example 1 was not coated with polyphenylene sulfide polymer electrolyte, and other operations were the same as those in Example 1.

[0112] Comparative Example 2

[0113] This comparative example prepared a composite solid electrolyte, which was different from that in Example 1 in that: the lithiated PPS was replaced with an equal amount of unlithiated PPS.

[0114] Comparative Example 3

[0115] This comparative example prepared a composite solid electrolyte, which was different from that in Example 1 in that: 0.2 wt% PTFE was replaced with an equal amount of lithiated PPS, and the treatment of S3 was not carried out. The composite solid electrolyte powder was directly put into a roll press. The heating temperature of the roll press was 80 °C, and the rotation speed was 6 rpm. The powder was roll-pressed into a composite solid electrolyte membrane.

[0116] Comparative Example 4

[0117] The comparative example prepared a composite solid electrolyte, which was different from that in Example 1 in that: the preparation raw materials of the solid electrolyte membrane included the following components in weight percentages: 50 wt% lithiated polysulfide, 15 wt% LPSC (Li 5.4 PS 4.4 Cl 1.6 ) and 35 wt% PTFE.

[0118] Comparative Example 5

[0119] The comparative example prepared a composite solid electrolyte, which was different from that in Example 1 in that: the preparation raw materials of the solid electrolyte membrane included the following components in weight percentages: 1 wt% lithiated PPS, 9 wt% LPSC (Li 5.4 PS 4.4 Cl 1.6 ) and 90 wt% PTFE.

[0120] Comparative Example 6

[0121] This comparative example prepared a composite solid electrolyte, which was different from that in Example 1 in that: in this comparative example, alumina (Al2O3) was used as the inorganic filler instead of the inorganic solid electrolyte, and other operations were the same as those in Example 1.

[0122] Comparative Example 7

[0123] The difference between this comparative example and Example 1 was only that the rotation speed during mixing in step S2 was 600 rpm, and the rest was the same as that in Example 1.

[0124] Comparative Example 8

[0125] The difference between this comparative example and Example 1 is only that the rotation speed during mixing in Step S3 is 500 rpm, and the rest is the same as in Example 1.

[0126] Application Example 1

[0127] This application example prepared a solid-state battery, which used the composite solid electrolyte prepared in Example 1. The specific steps are as follows:

[0128] S1. Prepare the positive electrode film. In a room-temperature environment, weigh the ternary positive electrode material, the solid electrolyte film of Example 1, the conductive agent conductive carbon black (SP), and PTFE powder in a mass ratio of 70:30:2:1, place them in a high-speed disperser, stir at 10,000 rpm, and after stirring for 10 min, place the mixed material in a roll press. The heating temperature of the roll press is 160 °C, and the rotation speed is 5 rpm to obtain the positive electrode film;

[0129] S2. Prepare the negative electrode film. Use metallic lithium as the negative electrode;

[0130] S3. Assemble the solid-state battery. Place the positive electrode film prepared in Step S1 into a mold, sequentially stack the composite solid electrolyte film prepared in Example 1 and the negative electrode film in Step S2, and then cold press at 80 °C and 140 MPa to obtain the solid-state battery SSB-01.

[0131] Application Examples 2-8 and Comparative Application Examples 1-8

[0132] This application example prepared a solid-state battery. The difference between this application example and Application Example 1 is that: in this application example, the solid electrolyte films prepared in Examples 2-8 and Comparative Examples 1-8 were respectively used to replace the solid electrolyte film of Example 1 used in Application Example 1, and the solid electrolyte used in the positive electrode film was also correspondingly replaced with the solid electrolyte in the corresponding example. Other operations were the same as in Application Example 2, and the solid-state batteries SSB-02 to SSB-16 were correspondingly prepared.

[0133] Detection Example

[0134] This detection example tested the performance of each of the solid-state batteries SSB-01 to SSB-16 prepared in the above application examples, mainly including mechanical properties and cycling performance. The specific test methods are as follows:

[0135] The test method for mechanical properties is as follows: Use a universal mechanical property testing machine to test the tensile strength of the solid electrolyte film. Use a test mold to prepare the solid electrolyte film into a dumbbell-shaped spline, and calculate the maximum force when it is stretched to failure on the testing machine at a speed of 10 mm / min.

[0136] The test method for the cycling performance is as follows: The test is carried out using a prototype battery mold at a test temperature of 60°C. First, a constant current charge is performed at a current of 0.1C until 4.3V, then a constant voltage charge is carried out until the current is cut off at 0.05C. After that, it is left standing for 20 minutes, and then discharged at a current of 0.2C until 2.7V, and left standing for 20 minutes to complete one cycle. Such charge-discharge cycles are repeated for the test.

[0137] The mechanical properties and electrochemical properties of the solid-state batteries SSB-01 to SSB-16 are tested using the above method, and the obtained results are shown in Table 1.

[0138] Table 1

[0139]

[0140]

[0141] From the performance test results of each solid-state battery in Table 1, it can be seen that compared with the solid-state battery SSB-06 using the solid electrolyte of Comparative Example 1, the composite solid electrolytes of Examples 1 to 8 used in solid-state batteries SSB-01 to SSB-05 have excellent mechanical properties (tensile strength above 15 MPa) and cycling performance (cycle number at 60°C above 280 cycles), indicating that the composite solid electrolyte membranes prepared in Examples 1 to 8 have excellent mechanical properties and electrochemical stability.

[0142] In Comparative Example 1, the inorganic solid electrolyte LPSC in Example 1 was not coated with polyphenylene sulfide polymer electrolyte, resulting in a decrease in tensile strength and a decrease in the cycle number at 60°C.

[0143] In Comparative Example 2, the lithiated PPS was replaced with an equal amount of unlithiated PPS, resulting in a decrease in the cycle number at 60°C and affecting the cycling performance.

[0144] In Comparative Example 3, 0.2 wt% PTFE was replaced with an equal amount of lithiated PPS, and the treatment of S3 was not carried out, resulting in a decrease in tensile strength and a decrease in the cycle number at 60°C.

[0145] In Comparative Example 4, due to the too high content of lithiated polysulfide and too low content of inorganic solid electrolyte, the cycle number at 60°C decreased, affecting the cycling performance.

[0146] In Comparative Example 5, due to the too low content of inorganic solid electrolyte and too high content of fibrillable polymer, the cycle number at 60°C decreased, affecting the cycling performance.

[0147] In Comparative Example 6, alumina (Al2O3) was used as the inorganic filler instead of the inorganic solid electrolyte, resulting in a significant decrease in the cycling performance.

[0148] In Comparative Example 7, due to the too high rotation speed during mixing in Step S2, the cycle performance was significantly reduced.

[0149] In Comparative Example 8, due to the too low rotation speed during mixing in Step S3, the tensile strength and cycle performance were significantly reduced.

[0150] The applicant declares that the present invention illustrates the solid electrolyte membrane, its preparation method and application of the present invention through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the raw materials selected for the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A solid electrolyte membrane, characterized in that, The raw materials for preparing the solid electrolyte membrane include the following components in weight percentages: Lithiated polymer: 0.05 - 20% Inorganic solid electrolyte: 40 - 99.9% Fibrillatable polymer: 0.05 - 59.95%; The solid electrolyte membrane is obtained by coating the inorganic solid electrolyte with the lithiated polymer and then mixing it with the fibrillatable polymer to form a film; The lithiated polymer is obtained by mixing a polymer with a lithium salt.

2. The solid electrolyte membrane according to claim 1, wherein The lithiated polymer is at least one of the following lithiated compounds: polyphenylene sulfide, polysulfide, or polysulfur rubber.

3. The solid electrolyte membrane according to claim 2, characterized in that, The lithiated polymer is lithiated polyphenylene sulfide.

4. The solid electrolyte film according to claim 1, wherein The inorganic solid electrolyte includes at least one of an oxide solid electrolyte and a sulfide solid electrolyte.

5. The solid electrolyte film according to claim 4, characterized in that, The oxide solid electrolyte includes at least one of a garnet-type solid electrolyte, a NASICON-type solid electrolyte, or a perovskite-type solid electrolyte.

6. The solid electrolyte membrane according to claim 4, characterized in that, The sulfide solid electrolyte includes at least one of a Li2S-P2S5 system sulfide solid electrolyte, a thio-LISICON type sulfide solid electrolyte, or an argyrodite type sulfide solid electrolyte.

7. The solid electrolyte membrane according to claim 1, characterized in that, The thickness of the solid electrolyte membrane is 15 μm - 100 μm.

8. The method for preparing a solid electrolyte membrane according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: (1) Grind and mix the lithiated polymer with the inorganic solid electrolyte so that the lithiated polymer coats the inorganic solid electrolyte to obtain a composite solid electrolyte powder; (2) Shear-mix the fibrillatable polymer with the composite solid electrolyte powder to obtain a mixture; (3) Perform hot pressing on the mixture described in step (2) to obtain the solid electrolyte membrane.

9. The preparation method according to claim 8, characterized in that, The lithiated polymer in step (1) is obtained by mixing a polymer with a lithium salt.

10. The preparation method according to claim 8, characterized in that, The rotation speed of the grinding and mixing in step (1) is 50 rpm - 300 rpm, and the time is 5 min - 30 min.

11. The preparation method according to claim 8, wherein The rotation speed of the shear mixing in step (2) is 1000 rpm - 30000 rpm, and the time is 0.5 min - 60 min.

12. The preparation method according to claim 8, characterized in that, The hot pressing in step (3) is hot roll pressing.

13. The preparation method according to claim 8, characterized in that, The temperature of the hot pressing in step (3) is 20°C - 250°C.

14. The preparation method according to claim 13, characterized in that, The temperature of the hot pressing in step (3) is 70°C - 140°C.

15. A solid-state battery, characterized in that, The solid-state battery includes the solid electrolyte membrane according to any one of claims 1 - 7.

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