Double-layer all-solid-state electrolyte containing polymer blend layer, preparation method of double-layer all-solid-state electrolyte and lithium ion battery

Abstract

The invention belongs to the technical field of lithium ion batteries, and relates to a double-layer all-solid-state electrolyte containing a polymer blend layer, a preparation method of the double-layer all-solid-state electrolyte and a lithium ion battery. The double-layer all-solid-state electrolyte comprises a polymer blend electrolyte layer and a plastic crystal electrolyte layer, the polymer blend electrolyte layer contains a polymer blend, an inorganic ceramic fast ion conductor filler and a lithium salt; and the plastic crystal electrolyte layer contains butanedinitrile and lithium salt. The double-layer all-solid-state electrolyte provided by the invention has higher conductivity and more excellent cycle performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion batteries, and in particular, relates to a double-layer all-solid-state electrolyte containing a polymer blend layer, a method for preparing the double-layer all-solid-state electrolyte, and a lithium ion battery comprising the double-layer all-solid-state electrolyte. Background Art

[0002] Lithium-ion batteries are considered to be a promising energy storage element due to their high energy density and good cycle performance. The disadvantages of the more mature liquid electrolytes today are low lithium ion migration number, flammability, easy leakage, and the inability to use metallic lithium as the negative electrode electrolyte, which limits the further development of lithium-ion batteries. Therefore, researchers have turned their attention to solid electrolytes.

[0003] The advantages of polymer solid electrolytes are low cost, high safety and easy processing, so they have received widespread attention. However, compared with liquid electrolytes, polymer solid electrolytes have low ionic conductivity and are difficult to use on a large scale at this stage.

[0004] The conductivity of inorganic solid electrolytes at room temperature is close to that of liquid electrolytes, but it is difficult to directly contact the positive and negative electrodes, and the mechanical properties are poor. In order to comprehensively improve the performance of lithium-ion batteries, researchers have tried to combine polymer electrolytes and inorganic solid electrolytes to combine the advantages of both. However, the conductivity of the electrolytes obtained by the current composite scheme is still unsatisfactory.

[0005] In the selection of solid polymer electrolyte matrix, although the electrical conductivity of polypropylene carbonate and polyacrylonitrile electrolytes can meet the use requirements of solid electrolytes, the solid electrolyte with polypropylene carbonate as the matrix has too high viscosity and poor mechanical properties, which is not conducive to the subsequent assembly of the battery; while the solid electrolyte with polyacrylonitrile as the matrix is ​​too brittle and accompanied by warping, which also affects the subsequent processing of the battery.

[0006] In addition, solid-state batteries still face some urgent problems before they can be applied on a large scale. For example, compared with liquid electrolytes, polymer solid electrolytes have low ionic conductivity; and during the battery cycle, metal lithium forms dendrites due to uneven deposition, which penetrate the electrolyte and cause short circuits, seriously affecting the battery cycle stability and safety. Summary of the invention

[0007] In view of the above problems existing in the prior art, the object of the present invention is to provide a double-layer all-solid-state electrolyte containing a polymer blend layer, a preparation method thereof, and a lithium-ion battery, wherein the double-layer all-solid-state electrolyte has higher electrical conductivity and better cycle performance.

[0008] The first aspect of the present invention provides a double-layer all-solid-state electrolyte containing a polymer blend layer, wherein the double-layer all-solid-state electrolyte includes a polymer blend electrolyte layer and a plastic crystal electrolyte layer; the polymer blend electrolyte layer contains a polymer blend, an inorganic ceramic fast ion conductor filler and a lithium salt; the plastic crystal electrolyte layer contains succinonitrile and a lithium salt.

[0009] A second aspect of the present invention provides a method for preparing the above-mentioned double-layer all-solid-state electrolyte containing a polymer blend layer, the preparation method comprising the following steps:

[0010] 1) mixing the polymer blend and the lithium salt with an organic solvent to obtain a mixed solution;

[0011] 2) adding the inorganic ceramic fast ion conductor filler into the mixed solution and dispersing it to form a suspension;

[0012] 3) coating the suspension on a mold and drying it to obtain the polymer blend electrolyte layer;

[0013] 4) mixing the succinonitrile and the lithium salt to obtain a mixed solution;

[0014] 5) coating the mixed solution obtained in step 4) on the polymer blend electrolyte layer and drying it to obtain a double-layer all-solid electrolyte.

[0015] A third aspect of the present invention provides a lithium ion battery, comprising a positive electrode, a negative electrode and an electrolyte, wherein the electrolyte is the above-mentioned double-layer all-solid electrolyte containing a polymer blend layer.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. The plastic crystal layer of the present invention can inhibit the formation of lithium negative electrode dendrites, increase the contact area, reduce the interface impedance, and improve the stability of the battery cycle. Moreover, it has both solid and liquid characteristics and also takes into account the requirements of mechanical properties. The self-diffusion of succinonitrile in the plastic crystal layer and the rotation of its molecules or ions can promote the movement of lithium ions, and a higher ionic conductivity can be obtained.

[0018] 2. The polymer blend electrolyte layer of the present invention ensures the electrical conductivity and mechanical properties of the solid electrolyte. The polymer blend layer is made of a blend of polypropylene carbonate and polyacrylonitrile. The two polymers have good compatibility. The obtained blend has both the rigidity of polyacrylonitrile and the flexibility of polypropylene carbonate, and has good comprehensive performance, which is conducive to the rapid transmission of lithium ions, thereby improving the electrical conductivity of the electrolyte.

[0019] 3. Compared with liquid electrolytes or mixed electrolytes, the double-layer all-solid electrolyte containing a polymer blend layer of the present invention has good safety and is non-flammable.

[0020] 4. The method for preparing a double-layer all-solid-state electrolyte containing a polymer blend layer of the present invention is simple and easy to implement, and the raw materials are readily available, which is conducive to promotion.

[0021] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0023] Figure 1 It is a schematic diagram comparing the conductivity of the electrolytes prepared in Examples 1-2, 5-6 and Comparative Examples 1-4 at 25°C. DETAILED DESCRIPTION

[0024] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0025] According to the first aspect of the present invention, the present invention provides a double-layer all-solid-state electrolyte containing a polymer blend layer, wherein the double-layer all-solid-state electrolyte includes a polymer blend electrolyte layer and a plastic crystal electrolyte layer; the polymer blend electrolyte layer contains a polymer blend, an inorganic ceramic fast ion conductor filler and a lithium salt; the plastic crystal electrolyte layer contains succinonitrile and a lithium salt.

[0026] In the present invention, the polymer blend is composed of polyacrylonitrile and polypropylene carbonate, and the weight ratio of polyacrylonitrile to polypropylene carbonate can be 0.25-9:1, preferably 1-9:1, and more preferably 1.5-4:1. For example, it can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 and other ratios within the above range. By controlling the weight ratio of the polyacrylonitrile to the polypropylene carbonate within the preferred range, higher conductivity can be obtained.

[0027] According to the present invention, the inorganic ceramic fast ion conductor filler can be Li 14 Zn(GeO4)4、LiAl x Zr 2-x (PO4)3, Li7La3Zr2O 12 , Li 6.4 Ln3Z 1.4 Ta 0.6 O 12 , Li 1.4 Al 0.4 Ti 1.6 (PO4)3 and Li 1.5 Al 0.5 Ge 1.5At least one of (PO4)3, LiAl x Zr 2-x (PO4)3, 0.1≤x≤0.5. Preferably, the inorganic ceramic fast ion conductor filler is Li 6.4 Ln3Z 1.4 Ta 0.6 O 12 and / or Li 1.5 Al 0.5 Ge 1.5 (PO4)3. As in conventional use, the inorganic ceramic fast ion conductors are all commercially available or can be prepared by methods known in the art.

[0028] The lithium salt used in the present invention may be any lithium salt conventionally used in the art, including but not limited to at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium tetrafluorophosphate, lithium difluorophosphate, lithium bis(oxalatoborate) and lithium difluorooxalatoborate. Preferably, lithium hexafluorophosphate and / or lithium bis(trifluoromethanesulfonyl)imide are used.

[0029] In the polymer blend electrolyte layer of the present invention, based on the total weight of the polymer blend electrolyte layer, the content of the polymer blend can be 35-90wt%, preferably 40-80wt%, and more preferably 50-70wt%; the content of the inorganic ceramic fast ion conductor filler can be 0.5-50wt%, preferably 2-40wt%, and more preferably 5-20wt%; the content of the lithium salt can be 9-50wt%, preferably 18-50wt%, and more preferably 25-40wt%.

[0030] In the plastic crystal electrolyte layer of the present invention, based on the total weight of the plastic crystal electrolyte layer, the content of succinonitrile can be 40-80wt%, preferably 50-75wt%, and more preferably 55-75wt%; the content of the lithium salt can be 20-60wt%, preferably 25-50wt%, and more preferably 25-45wt%.

[0031] When the double-layer all-solid electrolyte containing a polymer blend layer of the present invention is used in a lithium-ion battery, it is usually prepared into a film, and its thickness can be set as required. For example, the polymer blend electrolyte layer is in a film shape, and the thickness of the film can be 60-200 μm; the plastic crystal electrolyte layer is in a film shape, and the thickness of the film can be 60-200 μm; the thickness of the double-layer all-solid electrolyte is the total thickness of the two electrolyte layers, which can be 120-400 μm.

[0032] According to a second aspect of the present invention, the present invention provides a method for preparing the above-mentioned double-layer all-solid-state electrolyte containing a polymer blend layer, the preparation method comprising the following steps:

[0033] 1) mixing the polymer blend and the lithium salt with an organic solvent to obtain a mixed solution;

[0034] 2) adding the inorganic ceramic fast ion conductor filler into the mixed solution and dispersing it to form a suspension;

[0035] 3) coating the suspension on a mold and drying it to obtain the polymer blend electrolyte layer;

[0036] 4) mixing the succinonitrile and the lithium salt to obtain a mixed solution;

[0037] 5) coating the mixed solution obtained in step 4) on the polymer blend electrolyte layer and drying it to obtain a double-layer all-solid electrolyte.

[0038] In step 1) of the present invention, the organic solvent may be at least one of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile and acetone, preferably acetonitrile and / or N,N-dimethylformamide, and more preferably acetonitrile.

[0039] The mass concentration of the solute in the mixed solution in step 1) can be 10-40%.

[0040] In the present invention, the amount of polymer blend (polyacrylonitrile and polypropylene carbonate), lithium salt, and inorganic ceramic fast ion conductor filler used in preparing the polymer blend electrolyte layer is determined according to the content of each component in the polymer blend electrolyte layer, and the loss during the preparation process is ignored. Similarly, the amount of succinonitrile and lithium salt used in preparing the plastic crystal electrolyte layer is also determined according to their content in the plastic crystal electrolyte layer.

[0041] According to the present invention, in step 1), mixing is carried out under stirring conditions, the polymer blend and the lithium salt are mixed with the organic solvent, and stirred sufficiently to completely dissolve the polymer blend and the lithium salt to obtain a mixed solution; the mixing conditions preferably include: stirring at 40-75° C. for 5-12 hours.

[0042] In step 2) of the present invention, dispersion is carried out by combining ultrasonic dispersion and stirring. The ultrasonic dispersion can adopt conventional process conditions and equipment in the art. The dispersion conditions may include: first ultrasonic dispersion for 5-25 minutes, and then stirring at 40-85°C for 5-20 hours.

[0043] According to the present invention, the suspension in step 3) is coated on the mold by solution casting to form a liquid film, and the liquid film is dried to form a polymer blend electrolyte layer, and the drying can be vacuum drying, and the vacuum drying temperature can be 25-80° C., and the time can be 12-48 hours. The mold can be a mold of various materials commonly used in the art, such as a polytetrafluoroethylene mold.

[0044] In step 4) of the present invention, the mixing conditions may include: stirring at 60-100° C. for 4-8 hours.

[0045] According to the present invention, the mixed solution in step 5) is coated on the polymer blend electrolyte layer by solution casting to form a liquid film, and the liquid film is dried to form a plastic crystal electrolyte layer. The drying can be vacuum drying, the vacuum drying temperature can be 25-80°C, and the time can be 12-48 hours.

[0046] According to the third aspect of the present invention, the present invention further provides a lithium ion battery, the lithium ion battery comprising a positive electrode, a negative electrode and an electrolyte, wherein the electrolyte is the above-mentioned double-layer all-solid electrolyte containing a polymer blend layer.

[0047] The positive electrode and negative electrode of the lithium-ion battery in the present invention can be made of various conventional positive and negative electrode materials, and the present invention has no special limitation on this.

[0048] The present invention will be further described below in conjunction with embodiments, but the scope of the present invention is not limited to these embodiments.

[0049] In the following examples and comparative examples, the raw materials and data acquisition methods used are as follows:

[0050] Polyacrylonitrile was purchased from PetroChina Ningxia Petrochemical Company.

[0051] Polypropylene carbonate: purchased from EmpowerMateria, Japan.

[0052] Lithium bis(trifluoromethanesulfonate)imide: purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0053] Lithium bis(fluorosulfonyl)imide: purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0054] Li 1.5 Al 0.5 Ge 1.5 (PO4)3: purchased from Hefei Kejing Material Technology Co., Ltd.

[0055] Li 6.4 Ln3Z 1.4 Ta 0.6 O 12 : Purchased from Hefei Kejing Material Technology Co., Ltd.

[0056] Li7La3Zr2O 12 : Purchased from Hefei Kejing Material Technology Co., Ltd.

[0057] Li 1.4 Al 0.4 Ti 1.6 (PO4)3: purchased from Hefei Kejing Material Technology Co., Ltd.

[0058] N,N-Dimethylformamide: purchased from Beijing Inokai Technology Co., Ltd.

[0059] N,N-Dimethylacetamide: purchased from Beijing Inokai Technology Co., Ltd.

[0060] Acetonitrile: purchased from Beijing Bailingwei Technology Co., Ltd.

[0061] Acetone: purchased from Beijing Inokai Technology Co., Ltd.

[0062] Succinonitrile: purchased from Beijing Inokai Technology Co., Ltd.

[0063] 1. Ionic conductivity: The room temperature (25° C.) conductivity of the all-solid electrolyte membranes prepared in the embodiments and comparative examples was tested using electrochemical impedance spectroscopy.

[0064] 2. Cycle performance: A solid-state battery was prepared by assembling a lithium iron phosphate positive electrode, a lithium metal negative electrode and a solid electrolyte prepared in the embodiment or the comparative example, and then a cycle performance test was performed at a charge and discharge rate of 0.5C.

[0065] Example 1

[0066] 2.4 g polyacrylonitrile, 0.6 g polypropylene carbonate, 20 g N,N-dimethylformamide, and 2.1 g lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a uniform solution. 0.3 g Li 1.5 Al 0.5 Ge 1.5 (PO4)3 is added to the above solution, ultrasonically dispersed for 10 minutes, stirred at 70°C for 12 hours to obtain a suspension, and the suspension is cast on a polytetrafluoroethylene mold and dried in a vacuum oven at 50°C for 24 hours to obtain a polymer blend solid electrolyte layer. The polymer blend solid electrolyte layer is in the form of a film with a thickness of 70μm. 2g of succinonitrile and 1.25g of lithium bis(trifluoromethanesulfonate imide) are stirred at 80°C for 6 hours to obtain a uniform mixed solution. The mixed solution is cast on the polymer blend solid electrolyte layer and dried in a vacuum oven at 50°C for 24 hours to obtain a plastic crystalline solid electrolyte layer. The plastic crystalline solid electrolyte layer is in the form of a film with a thickness of 60μm. The thickness of the double-layer all-solid-state electrolyte membrane is 130μm, and its performance results are as follows. Figure 1 And as shown in Table 1.

[0067] Example 2

[0068] 4.5 g of polyacrylonitrile, 0.5 g of polypropylene carbonate, 35 g of acetonitrile, and 3 g of lithium bis(trifluoromethanesulfonate)imide were added to a 250 mL flask and stirred at 50 °C for 10 h to obtain a uniform solution. 6.4 Ln3Z 1.4 Ta 0.6 O 12 Add to the above solution, ultrasonically disperse for 20 minutes, stir at 80°C for 16 hours to obtain a suspension, cast the suspension on a polytetrafluoroethylene mold, and dry in a vacuum oven at 80°C for 24 hours to obtain a polymer blend solid electrolyte layer. The polymer blend solid electrolyte layer is in a film-like shape with a thickness of 100 μm. Stir 2.5 g of succinonitrile and 1.5 g of lithium bis(trifluoromethanesulfonate imide) at 90°C for 5 hours to obtain a uniform mixed solution, cast the mixed solution on the polymer blend solid electrolyte layer, and dry in a vacuum oven at 50°C for 24 hours to obtain a plastic crystalline solid electrolyte layer. The plastic crystalline solid electrolyte layer is in a film-like shape with a thickness of 80 μm. The thickness of the double-layer all-solid-state electrolyte membrane is 180 μm, and its performance results are as follows. Figure 1 And as shown in Table 1.

[0069] Example 3

[0070] 1.6 g polyacrylonitrile, 0.4 g polypropylene carbonate, 15 g N,N-dimethylacetamide, and 1 g lithium bis(fluorosulfonyl)imide were added to a 100 mL flask and stirred at 40 °C for 6 h to obtain a uniform solution. 0.3 g Li 1.5 Al 0.5 Ge 1.5 (PO4)3 was added to the above solution, ultrasonically dispersed for 10 minutes, stirred at 50°C for 8 hours to obtain a suspension, which was cast on a polytetrafluoroethylene mold and dried in a vacuum oven at 70°C for 24 hours to obtain a polymer blend solid electrolyte layer, which was in the form of a film with a thickness of 140 μm. 1.5 g of succinonitrile and 0.75 g of lithium bis(trifluoromethanesulfonate imide) were stirred at 85°C for 5 hours to obtain a uniform mixed solution, which was cast on the polymer blend solid electrolyte layer and dried in a vacuum oven at 50°C for 24 hours to obtain a plastic crystal solid electrolyte layer, which was in the form of a film with a thickness of 100 μm. The thickness of the double-layer all-solid electrolyte membrane was 240 μm, and its performance results are shown in Table 1.

[0071] Example 4

[0072] 3.2 g polyacrylonitrile, 0.8 g polypropylene carbonate, 30 g acetone, and 1.6 g lithium bis(fluorosulfonyl)imide were added to a 250 mL flask and stirred at 70 °C for 7 h to obtain a uniform solution. 6.4 Ln3Z 1.4 Ta 0.6 O 12 Add to the above solution, ultrasonically disperse for 20 minutes, stir at 70°C for 12 hours to obtain a suspension, cast the suspension on a polytetrafluoroethylene mold, and dry in a vacuum oven at 80°C for 24 hours to obtain a polymer blend solid electrolyte layer, which is in the form of a film with a thickness of 160 μm. Stir 2g of succinonitrile and 0.8g of lithium bis(trifluoromethanesulfonate imide) at 95°C for 4.5 hours to obtain a uniform mixed solution, cast the mixed solution on the polymer blend solid electrolyte layer, and dry in a vacuum oven at 50°C for 24 hours to obtain a plastic crystal solid electrolyte layer, which is in the form of a film with a thickness of 120 μm. The thickness of the double-layer all-solid electrolyte membrane is 280 μm, and its performance results are shown in Table 1.

[0073] Example 5

[0074] 4.5 g polyacrylonitrile, 0.5 g polypropylene carbonate, 35 g acetonitrile, and 3 g lithium bis(trifluoromethanesulfonate)imide were added into a 250 mL flask and stirred at 50 °C for 10 h to obtain a uniform solution. 12 Add to the above solution, ultrasonically disperse for 20 minutes, stir at 80°C for 16 hours to obtain a suspension, cast the suspension on a polytetrafluoroethylene mold, and dry in a vacuum oven at 80°C for 24 hours to obtain a polymer blend solid electrolyte layer. The polymer blend solid electrolyte layer is in a film-like shape with a thickness of 100 μm. Stir 2.5 g of succinonitrile and 1.5 g of lithium bis(trifluoromethanesulfonate imide) at 90°C for 5 hours to obtain a uniform mixed solution, cast the mixed solution on the polymer blend solid electrolyte layer, and dry in a vacuum oven at 50°C for 24 hours to obtain a plastic crystalline solid electrolyte layer. The plastic crystalline solid electrolyte layer is in a film-like shape with a thickness of 80 μm. The thickness of the double-layer all-solid-state electrolyte membrane is 180 μm, and its performance results are as follows. Figure 1 And as shown in Table 1.

[0075] Example 6

[0076] 4.5 g of polyacrylonitrile, 0.5 g of polypropylene carbonate, 35 g of acetonitrile, and 3 g of lithium bis(trifluoromethanesulfonate)imide were added to a 250 mL flask and stirred at 50 °C for 10 h to obtain a uniform solution. 1.4 Al 0.4 Ti 1.6(PO4)3 is added to the above solution, ultrasonically dispersed for 20 minutes, stirred at 80°C for 16 hours to obtain a suspension, and the suspension is cast on a polytetrafluoroethylene mold and dried in a vacuum oven at 80°C for 24 hours to obtain a polymer blend solid electrolyte layer. The polymer blend solid electrolyte layer is in the form of a film with a thickness of 100μm. 2.5g of succinonitrile and 1.5g of lithium bis(trifluoromethanesulfonate imide) are stirred at 90°C for 5 hours to obtain a uniform mixed solution. The mixed solution is cast on the polymer blend solid electrolyte layer and dried in a vacuum oven at 50°C for 24 hours to obtain a plastic crystalline solid electrolyte layer. The plastic crystalline solid electrolyte layer is in the form of a film with a thickness of 80μm. The thickness of the double-layer all-solid-state electrolyte membrane is 180μm, and its performance results are as follows. Figure 1 And as shown in Table 1.

[0077] Example 7

[0078] 1.0 g of polyacrylonitrile, 4.0 g of polypropylene carbonate, 35 g of acetonitrile, and 3 g of lithium bis(trifluoromethanesulfonate)imide were added to a 250 mL flask and stirred at 50 °C for 10 h to obtain a uniform solution. 1.5 Al 0.5 Ge 1.5 (PO4)3 was added to the above solution, ultrasonically dispersed for 20 minutes, stirred at 80°C for 16 hours to obtain a suspension, which was cast on a polytetrafluoroethylene mold and dried in a vacuum oven at 80°C for 24 hours to obtain a polymer blend solid electrolyte layer, which was in the form of a film with a thickness of 190 μm. 3.5 g of succinonitrile and 2.1 g of lithium bis(trifluoromethanesulfonate imide) were stirred at 80°C for 5 hours to obtain a uniform mixed solution, which was cast on a polymer blend all-solid electrolyte layer, and dried in a vacuum oven at 50°C for 24 hours to obtain a plastic crystalline solid electrolyte layer, which was in the form of a film with a thickness of 150 μm. The thickness of the double-layer all-solid electrolyte membrane was 340 μm, and its performance results are shown in Table 1.

[0079] Comparative Example 1

[0080] 2.4 g polyacrylonitrile, 0.6 g polypropylene carbonate, 20 g N,N-dimethylformamide, and 2.1 g lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a uniform solution. 0.3 g Li 1.5 Al 0.5 Ge 1.5(PO4)3 was added to the above solution, ultrasonically dispersed for 10 minutes, stirred at 70°C for 12 hours to obtain a suspension, which was cast on a polytetrafluoroethylene mold and dried in a vacuum oven at 50°C for 24 hours to obtain a polymer blend all-solid electrolyte layer. The polymer blend all-solid electrolyte layer was in the form of a film with a thickness of 70 μm. Its performance results are shown in FIG. Figure 1 And as shown in Table 1.

[0081] Comparative Example 2

[0082] 4.5 g of polyacrylonitrile, 0.5 g of polypropylene carbonate, 35 g of acetonitrile, and 3 g of lithium bis(trifluoromethanesulfonate)imide were added to a 250 mL flask and stirred at 50 °C for 10 h to obtain a uniform solution. 6.4 Ln3Z 1.4 Ta 0.6 O 12 Add to the above solution, ultrasonically disperse for 20 minutes, stir at 80°C for 16 hours to obtain a suspension, cast the suspension on a polytetrafluoroethylene mold, and dry in a vacuum oven at 80°C for 24 hours to obtain a polymer blend all-solid electrolyte layer. The polymer blend all-solid electrolyte layer is in the form of a film with a thickness of 100 μm. Its performance results are as follows Figure 1 And as shown in Table 1.

[0083] Comparative Example 3

[0084] 2.4 g polyacrylonitrile, 0.6 g polypropylene carbonate, 2 g succinonitrile, 20 g N,N-dimethylformamide, and 2.1 g lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a uniform mixed solution. 1.5 Al 0.5 Ge 1.5 (PO4)3 was added to the above solution, ultrasonically dispersed for 10 minutes, stirred at 70°C for 12 hours to obtain a suspension, which was cast on a polytetrafluoroethylene mold and dried in a vacuum oven at 50°C for 24 hours to obtain a polymer blend all-solid electrolyte layer. The polymer blend all-solid electrolyte layer was in the form of a film with a thickness of 70 μm. Its performance results are shown in FIG. Figure 1 And as shown in Table 1.

[0085] Comparative Example 4

[0086] 4.5 g of polyacrylonitrile, 0.5 g of polypropylene carbonate, 2.5 g of succinonitrile, 35 g of acetonitrile, and 3 g of lithium bis(trifluoromethanesulfonate)imide were added to a 250 mL flask and stirred at 50 °C for 10 h to obtain a uniform mixed solution. 6.4 Ln3Z 1.4 Ta 0.6 O 12Add to the above solution, ultrasonically disperse for 20 minutes, stir at 80°C for 16 hours to obtain a suspension, cast the suspension on a polytetrafluoroethylene mold, and dry in a vacuum oven at 80°C for 24 hours to obtain a polymer blend all-solid electrolyte layer. The polymer blend all-solid electrolyte layer is in the form of a film with a thickness of 100 μm. Its performance results are as follows Figure 1 And as shown in Table 1.

[0087] Comparative Example 5

[0088] 0.6 g polyacrylonitrile, 2.4 g polypropylene carbonate, 2 g succinonitrile, 20 g N,N-dimethylformamide, and 2.1 g lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a uniform mixed solution. 1.5 Al 0.5 Ge 1.5 (PO4)3 was added to the above solution, ultrasonically dispersed for 10 minutes, stirred at 70°C for 12 hours to obtain a suspension, which was cast on a polytetrafluoroethylene mold and dried in a vacuum oven at 50°C for 24 hours to obtain a polymer blend all-solid electrolyte layer. The polymer blend all-solid electrolyte layer was in the form of a film with a thickness of 70 μm, and its mechanical properties were too low to be tested for electrochemical properties.

[0089] Comparative Example 6

[0090] 2.5 g of succinonitrile and 1.5 g of lithium bis(trifluoromethanesulfonate)imide were stirred at 90°C for 5 hours to obtain a uniform mixed solution. The mixed solution was cast on a polytetrafluoroethylene mold and dried in a vacuum oven at 50°C for 24 hours to obtain a plastic crystalline solid electrolyte layer. The plastic crystalline solid electrolyte layer was in the form of a film with a thickness of 80 μm. Its mechanical properties were too low to be tested for electrochemical properties.

[0091] Comparative Example 7

[0092] 5.0 g polyacrylonitrile, 35 g acetonitrile, and 3 g lithium bis(trifluoromethanesulfonate)imide were added to a 250 mL flask and stirred at 50 °C for 10 h to obtain a uniform solution. 6.4 Ln3Z 1.4 Ta 0.6 O 12Add to the above solution, ultrasonically disperse for 20 minutes, stir at 80°C for 16 hours to obtain a suspension, cast the suspension on a polytetrafluoroethylene mold, and dry in a vacuum oven at 80°C for 24 hours to obtain a polyacrylonitrile solid electrolyte layer, which is in the form of a film with a thickness of 100μm. Stir 2.5g of succinonitrile and 1.5g of lithium bis(trifluoromethanesulfonate imide) at 90°C for 5 hours to obtain a uniform mixed solution, cast the mixed solution on the polyacrylonitrile solid electrolyte layer, and dry in a vacuum oven at 50°C for 24 hours to obtain a plastic crystalline solid electrolyte layer, which is in the form of a film with a thickness of 80μm. The thickness of the double-layer all-solid electrolyte membrane is 180μm.

[0093] Comparative Example 8

[0094] 5.0 g polypropylene carbonate, 35 g acetonitrile, and 3 g lithium bis(trifluoromethanesulfonate)imide were added to a 250 mL flask and stirred at 50 °C for 10 h to obtain a uniform solution. 6.4 Ln3Z 1.4 Ta 0.6 O 12 Add to the above solution, ultrasonically disperse for 20 minutes, stir at 80°C for 16 hours to obtain a suspension, cast the suspension on a polytetrafluoroethylene mold, and dry in a vacuum oven at 80°C for 24 hours to obtain a polypropylene carbonate solid electrolyte layer, which is in the form of a film with a thickness of 100 μm. Stir 2.5 g of succinonitrile and 1.5 g of lithium bis(trifluoromethanesulfonate imide) at 90°C for 5 hours to obtain a uniform mixed solution, cast the mixed solution on a polypropylene carbonate all-solid electrolyte layer, and dry in a vacuum oven at 50°C for 24 hours. It cannot form a film and cannot be used in solid-state batteries.

[0095] Table 1

[0096] <![CDATA[Ionic conductivity S·cm -1 > Number of cycles Example 1 <![CDATA[1.22×10 -3 ]]> 249 Example 2 <![CDATA[1.15×10 -3 ]]> 236 Example 3 <![CDATA[1.04×10 -3 ]]> 228 Example 4 <![CDATA[9.67×10 -4 ]]> 215 Example 5 <![CDATA[9.23×10 -4 ]]> 204 Example 6 <![CDATA[8.87×10 -4 ]]> 195 Example 7 <![CDATA[8.02×10 -4 ]]> 187 Comparative Example 1 <![CDATA[4.35×10 -4 ]]> 38 Comparative Example 2 <![CDATA[4.16×10 -4 ]]> 30 Comparative Example 3 <![CDATA[5.08×10 -4 ]]> 113 Comparative Example 4 <![CDATA[5.14×10 -4 ]]> 124 Comparative Example 5 / / Comparative Example 6 / / Comparative Example 7 <![CDATA[5.1×10 -4 ]]> 52 Comparative Example 8 / /

[0097] From Table 1 and Figure 1 It can be seen that compared with single-layer polymer blend solid electrolytes, the conductivity and cycle performance of double-layer solid electrolytes are improved, especially the cycle performance is significantly improved; the mechanical properties of single-layer plastic crystal electrolytes are too low to perform electrochemical performance tests; and the single-layer polymer blend solid electrolytes containing plastic crystals have inferior cycle performance to double-layer solid electrolytes and lower conductivity.

[0098] In addition, the present invention also has obvious advantages in comparison with the all-solid-state electrolyte of a single polymer system: the room temperature conductivity of the polyacrylonitrile solid electrolyte is slightly inferior to that of the blended solid electrolyte, and the polyacrylonitrile solid electrolyte is too brittle, which is not conducive to the subsequent use of the electrolyte. After the polypropylene carbonate solid electrolyte is composited with the plastic crystal solid electrolyte layer, it cannot form a film and cannot be used in a solid-state battery. The solid electrolyte mainly composed of polypropylene carbonate polymer cannot form a film after being blended with plastic crystals, and cannot be used in a solid-state battery.

[0099] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0100] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

Claims

1. A double-layer all-solid electrolyte containing a polymer blend layer, characterized in that: The double-layer all-solid electrolyte comprises a polymer blend electrolyte layer and a plastic crystal electrolyte layer; the polymer blend electrolyte layer contains a polymer blend, an inorganic ceramic fast ion conductor filler and a lithium salt; the plastic crystal electrolyte layer contains succinonitrile and a lithium salt.

2. The double-layer all-solid electrolyte containing a polymer blend layer according to claim 1, wherein The polymer blend consists of polyacrylonitrile and polypropylene carbonate, and the weight ratio of polyacrylonitrile to polypropylene carbonate is 0.25-9:1, preferably 1-9:1, and more preferably 1.5-4:

1.

3. The double-layer all-solid electrolyte containing a polymer blend layer according to claim 1, wherein The inorganic ceramic fast ion conductor filler is Li 14 Zn(GeO4)4、LiAl x Zr 2-x (PO4)3, Li7La3Zr2O 12 , Li 6.4 LqCy 1.4 Ta 0.6 O 12 , Li 1.4 Al 0.4 Ti 1.6 (PO4)3 and Li 1.5 Al 0.5 Ge 1.5 At least one of (PO4)3, LiAl x Zr 2-x (PO4)3 0.1≤x≤0.5; the inorganic ceramic fast ion conductor filler is preferably Li 6.4 LqCy 1.4 Ta 0.6 O 12 and / or Li 1.5 Al 0.5 Ge 1.5 (PO4)3.

4. The double-layer all-solid electrolyte containing a polymer blend layer according to claim 1, wherein The lithium salt is at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium tetrafluorophosphate, lithium difluorophosphate, lithium bis(oxalatoborate) and lithium difluorooxalatoborate; preferably lithium hexafluorophosphate and / or lithium bis(trifluoromethanesulfonyl)imide.

5. The double-layer all-solid electrolyte containing a polymer blend layer according to any one of claims 1 to 4, wherein: In the polymer blend electrolyte layer, based on the total weight of the polymer blend electrolyte layer, the content of the polymer blend is 35-90wt%, preferably 40-80wt%, and more preferably 50-70wt%; the content of the inorganic ceramic fast ion conductor filler is 0.5-50wt%, preferably 2-40wt%, and more preferably 5-20wt%; the content of the lithium salt is 9-50wt%, preferably 18-50wt%, and more preferably 25-40wt%.

6. The double-layer all-solid electrolyte containing a polymer blend layer according to any one of claims 1 to 4, wherein: In the plastic crystal electrolyte layer, based on the total weight of the plastic crystal electrolyte layer, the content of succinonitrile is 40-80wt%, preferably 50-75wt%, and more preferably 55-75wt%; the content of the lithium salt is 20-60wt%, preferably 25-50wt%, and more preferably 25-45wt%.

7. The double-layer all-solid electrolyte containing a polymer blend layer according to claim 1, wherein The polymer blend electrolyte layer is in a film shape, and the thickness of the film is 60-200 μm; the plastic crystal electrolyte layer is in a film shape, and the thickness of the film is 60-200 μm.

8. The method for preparing a double-layer all-solid electrolyte containing a polymer blend layer according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: 1) mixing the polymer blend and the lithium salt with an organic solvent to obtain a mixed solution; 2) adding the inorganic ceramic fast ion conductor filler into the mixed solution and dispersing it to form a suspension; 3) coating the suspension on a mold and drying it to obtain the polymer blend electrolyte layer; 4) mixing the succinonitrile and the lithium salt to obtain a mixed solution; 5) coating the mixed solution obtained in step 4) on the polymer blend electrolyte layer and drying it to obtain a double-layer all-solid electrolyte.

9. The method for preparing a double-layer all-solid electrolyte containing a polymer blend layer according to claim 8, wherein: In step 1), the organic solvent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile and acetone, preferably acetonitrile and / or N,N-dimethylformamide, more preferably acetonitrile; the mass concentration of the solute in the mixed solution is 10-40%; The mixing conditions include: stirring at 40-75°C for 5-12h; In step 2), the dispersion conditions include: first ultrasonic dispersion for 5-25 min, then stirring at 40-85° C. for 5-20 h; In step 3) and step 5), the drying is vacuum drying at a temperature of 25-80° C. for 12-48 hours; In step 4), the mixing conditions include: stirring at 60-100° C. for 4-8 h.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises a positive electrode, a negative electrode and an electrolyte, wherein the electrolyte is a double-layer all-solid electrolyte containing a polymer blend layer as described in any one of claims 1 to 7.

Images