Double-layer all-solid-state electrolyte containing polyalkylene oxide 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 polyalkylene oxide 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 polyalkylene oxide electrolyte layer and a plastic crystal electrolyte layer, the polyalkylene oxide electrolyte layer contains polyalkylene oxide, inorganic ceramic fast ion conductor filler and 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 polyalkylene oxide layer, a preparation method of 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 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

[0006] 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 polyalkylene oxide 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.

[0007] The first aspect of the present invention provides a double-layer all-solid-state electrolyte containing a polyalkylene oxide layer, wherein the double-layer all-solid-state electrolyte comprises a polyalkylene oxide electrolyte layer and a plastic crystal electrolyte layer; the polyalkylene oxide electrolyte layer contains polyalkylene oxide, an inorganic ceramic fast ion conductor filler and a lithium salt; and the plastic crystal electrolyte layer contains succinonitrile and a lithium salt.

[0008] A second aspect of the present invention provides a method for preparing the above-mentioned double-layer all-solid-state electrolyte containing a polyalkylene oxide layer, the preparation method comprising the following steps:

[0009] 1) mixing the polyalkylene oxide and lithium salt with an organic solvent to obtain a mixed solution;

[0010] 2) adding the inorganic ceramic fast ion conductor filler into the mixed solution and dispersing it to form a suspension;

[0011] 3) coating the suspension on a mold and drying it to obtain the polyalkylene oxide electrolyte layer;

[0012] 4) mixing the succinonitrile and the lithium salt to obtain a mixed solution;

[0013] 5) coating the mixed solution obtained in step 4) on the polyalkylene oxide electrolyte layer and drying it to obtain a double-layer all-solid electrolyte.

[0014] 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 polyalkylene oxide layer.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. The plastic crystal layer in 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.

[0017] 2. The substrate used for the polyalkylene oxide electrolyte layer of the present invention is polyalkylene oxide, which has good crystallinity and mechanical properties. The polyalkylene oxide electrolyte layer can ensure the electrical conductivity and mechanical properties of the solid electrolyte and has good comprehensive performance.

[0018] 3. Compared with liquid electrolytes or mixed electrolytes, the double-layer all-solid electrolyte containing a polyalkylene oxide layer of the present invention has good safety and is non-flammable.

[0019] 4. The method for preparing a double-layer all-solid electrolyte containing a polyalkylene oxide layer of the present invention is simple and easy to implement, and the raw materials are readily available, which is conducive to promotion.

[0020] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0022] 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

[0023] 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.

[0024] According to the first aspect of the present invention, the present invention provides a double-layer all-solid-state electrolyte containing a polyalkylene oxide layer, wherein the double-layer all-solid-state electrolyte comprises a polyalkylene oxide electrolyte layer and a plastic crystal electrolyte layer; the polyalkylene oxide electrolyte layer contains polyalkylene oxide, an inorganic ceramic fast ion conductor filler and a lithium salt; the plastic crystal electrolyte layer contains succinonitrile and a lithium salt.

[0025] In the present invention, the polyalkylene oxide used as the substrate may be polyoxy lower carbon alkane, preferably polyethylene oxide and / or polypropylene oxide. The lower carbon alkane in the present invention refers to an alkane having 2-4 carbon atoms.

[0026] According to the present invention, the inorganic ceramic fast ion conductor filler can be Li 14 Zn(GeO 4 ) 4 、LiAlxZr 2- x(PO 4 ) 3 , Li 7 La 3 Zr 2 O 12 , Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 , Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 and Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 At least one of LiAl x Zr 2-x (PO 4 ) 3 Preferably, the inorganic ceramic fast ion conductor filler is Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 and / or Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3As in conventional use, the inorganic ceramic fast ion conductors can be commercially available or prepared by methods known in the art.

[0027] 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.

[0028] In the polyalkylene oxide electrolyte layer of the present invention, based on the total weight of the polyalkylene oxide electrolyte layer, the content of the polyalkylene oxide 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%.

[0029] 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%.

[0030] When the double-layer all-solid electrolyte containing a polyalkylene oxide layer of the present invention is used in a lithium ion battery, it is usually prepared in a film shape, and its thickness can be set as required. For example, the polyalkylene oxide 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.

[0031] 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 polyalkylene oxide layer, the preparation method comprising the following steps:

[0032] 1) mixing the polyalkylene oxide and lithium salt with an organic solvent to obtain a mixed solution;

[0033] 2) adding the inorganic ceramic fast ion conductor filler into the mixed solution and dispersing it to form a suspension;

[0034] 3) coating the suspension on a mold and drying it to obtain the polyalkylene oxide electrolyte layer;

[0035] 4) mixing the succinonitrile and the lithium salt to obtain a mixed solution;

[0036] 5) coating the mixed solution obtained in step 4) on the polyalkylene oxide electrolyte layer and drying it to obtain a double-layer all-solid electrolyte.

[0037] 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.

[0038] The mass concentration of the solute in the mixed solution in step 1) can be 10-40%.

[0039] In the present invention, the amount of polyalkylene oxide, lithium salt, and inorganic ceramic fast ion conductor filler used in preparing the polyalkylene oxide electrolyte layer is determined according to the content of each component in the polyalkylene oxide 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.

[0040] According to the present invention, in step 1), mixing is carried out under stirring conditions, the polyalkylene oxide and the lithium salt are mixed with the organic solvent, and stirred sufficiently to completely dissolve the polyalkylene oxide and the lithium salt to obtain a mixed solution; the mixing conditions preferably include: stirring at 40-75° C. for 5-12 hours.

[0041] 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.

[0042] According to the present invention, the suspension in step 3) is coated on a mold by solution casting to form a liquid film, and the liquid film is dried to form a polyalkylene oxide 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 conventionally used in the prior art, such as a polytetrafluoroethylene mold.

[0043] In step 4) of the present invention, the mixing conditions may include: stirring at 60-100° C. for 4-8 hours.

[0044] According to the present invention, the mixed solution in step 5) is coated on the polyalkylene oxide electrolyte layer by solution casting to form a liquid film, and the liquid film is dried to form a plastic crystalline 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.

[0045] 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 polyalkylene oxide layer.

[0046] 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.

[0047] 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.

[0048] In the following examples and comparative examples, the raw materials and data acquisition methods used are as follows:

[0049] Polyethylene oxide: purchased from Beijing Inokai Technology Co., Ltd.

[0050] Polypropylene oxide: purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0051] Lithium bis(trifluoromethanesulfonate)imide: purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

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

[0053] Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 : Purchased from Hefei Kejing Material Technology Co., Ltd.

[0054] Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 : Purchased from Hefei Kejing Material Technology Co., Ltd.

[0055] Li 7 La 3 Zr 2 O 12 : Purchased from Hefei Kejing Material Technology Co., Ltd.

[0056] Li 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3 : Purchased from Hefei Kejing Material Technology Co., Ltd.

[0057] N,N-Dimethylformamide: purchased from Beijing Inokai Technology Co., Ltd.

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

[0059] Acetonitrile: purchased from Beijing Bailingwei Technology Co., Ltd.

[0060] Acetone: purchased from Beijing Inokai Technology Co., Ltd.

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

[0062] 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.

[0063] 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 comparative example, and then a cycle performance test was performed at a charge and discharge rate of 0.5C.

[0064] Example 1

[0065] 3 g polyethylene oxide, 20 g acetonitrile, 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. 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 Add to the above solution, ultrasonically disperse for 10 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 50°C for 24 hours to obtain a polyethylene oxide solid electrolyte layer. The polyethylene oxide solid electrolyte layer is in a film-like shape with a thickness of 70μm. Stir 2g of succinonitrile and 1.25g of lithium bis(trifluoromethanesulfonate imide) at 80°C for 6 hours to obtain a uniform mixed solution, cast the mixed solution on the polyethylene oxide 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 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.

[0066] Example 2

[0067] 5 g polyethylene oxide, 35 g N,N-dimethylformamide, 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 La 3 Zr 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 polyethylene oxide solid electrolyte layer. The polyethylene oxide 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 polyethylene oxide 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.

[0068] Example 3

[0069] 2 g polyethylene oxide, 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. 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 Add to the above solution, ultrasonically disperse for 10 minutes, stir at 50°C for 8 hours to obtain a suspension, cast the suspension on a polytetrafluoroethylene mold, and dry in a vacuum oven at 70°C for 24 hours to obtain a polyethylene oxide solid electrolyte layer, which is in the form of a film with a thickness of 140 μm. Stir 1.5 g of succinonitrile and 0.75 g of lithium bis(trifluoromethanesulfonate imide) at 85°C for 5 hours to obtain a uniform mixed solution, cast the mixed solution on the polyethylene oxide 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 100 μm. The thickness of the double-layer all-solid electrolyte membrane is 240 μm, and its performance results are shown in Table 1.

[0070] Example 4

[0071] 4 g polyethylene oxide, 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 La 3 Zr 1.4 Ta 0.6 O 12Add 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 polyethylene oxide 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 polyethylene oxide 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.

[0072] Example 5

[0073] 5 g polyethylene oxide, 35 g N,N-dimethylformamide, 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. 7 La 3 Zr 2 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 polyethylene oxide solid electrolyte layer. The polyethylene oxide 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 polyethylene oxide 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.

[0074] Example 6

[0075] 5 g polyethylene oxide, 35 g N,N-dimethylformamide, 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. 1.4 Al 0.4 Ti 1.6 (PO 4 ) 3Add 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 polyethylene oxide solid electrolyte layer. The polyethylene oxide 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 polyethylene oxide 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.

[0076] Example 7

[0077] 5 g of polypropylene oxide, 35 g of N,N-dimethylformamide, 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 (PO 4 ) 3 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 oxide solid electrolyte layer. The polypropylene oxide all-solid electrolyte is in the form of a film with a thickness of 190 μm. Stir 3.5 g of succinonitrile and 2.1 g of lithium bis(trifluoromethanesulfonate imide) at 80°C for 5 hours to obtain a uniform mixed solution, cast the mixed solution on the polyethylene oxide solid electrolyte layer, and dry in a vacuum oven at 50°C for 24 hours to obtain a plastic crystal solid electrolyte layer. The plastic crystal solid electrolyte layer is in the form of a film with a thickness of 150 μm. The thickness of the double-layer all-solid electrolyte membrane is 340 μm, and its performance results are shown in Table 1.

[0078] Comparative Example 1

[0079] 3 g polyethylene oxide, 20 g acetonitrile, 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. 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3Add to the above solution, ultrasonically disperse for 10 minutes, stir at 70℃ for 12 hours to obtain a suspension, cast the suspension on a polytetrafluoroethylene mold, and dry in a vacuum oven at 50℃ for 24 hours to obtain a polyethylene oxide all-solid electrolyte. The polyethylene oxide all-solid electrolyte is in the form of a film with a thickness of 70μm. Its performance results are as follows Figure 1 And as shown in Table 1.

[0080] Comparative Example 2

[0081] 5 g polyethylene oxide, 35 g N,N-dimethylformamide, 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 La 3 Zr 1.4 Ta 0.6 O 12 Add to the above solution, ultrasonically disperse for 20 minutes, stir at 80℃ for 16 hours to obtain a suspension, cast the suspension on a polytetrafluoroethylene mold, and dry in a vacuum oven at 80℃ for 24 hours to obtain a polyethylene oxide all-solid electrolyte. The polyethylene oxide all-solid electrolyte is in the form of a film with a thickness of 100μm. Its performance results are as follows Figure 1 And as shown in Table 1.

[0082] Comparative Example 3

[0083] 3 g polyethylene oxide, 0.75 g succinonitrile, 20 g acetonitrile, 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. .5 Al 0.5 Ge 1.5 (PO 4 ) 3 Add to the above solution, ultrasonically disperse for 10 minutes, stir at 70℃ for 12 hours to obtain a suspension, cast the suspension on a polytetrafluoroethylene mold, and dry in a vacuum oven at 50℃ for 24 hours to obtain a polyethylene oxide all-solid electrolyte. The polyethylene oxide all-solid electrolyte is in the form of a film with a thickness of 70μm. Its performance results are as follows Figure 1 And as shown in Table 1.

[0084] Comparative Example 4

[0085] 5 g polyethylene oxide, 1.25 g succinonitrile, 35 g N,N-dimethylformamide, 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 mixed solution. 6.4 La 3 Zr 1.4 Ta 0.6 O12 Add to the above solution, ultrasonically disperse for 20 minutes, stir at 80℃ for 16 hours to obtain a suspension, cast the suspension on a polytetrafluoroethylene mold, and dry in a vacuum oven at 80℃ for 24 hours to obtain a polyethylene oxide all-solid electrolyte. The polyethylene oxide all-solid electrolyte is in the form of a film with a thickness of 100μm. Its performance results are as follows Figure 1 And as shown in Table 1.

[0086] Comparative Example 5

[0087] 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.

[0088] Table 1

[0089]

[0090]

[0091] From Table 1 and Figure 1 It can be seen that compared with single-layer polyalkylene oxide 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 conduct electrochemical performance tests; and the conductivity and cycle performance of single-layer polyalkylene oxide solid electrolytes containing plastic crystals are also inferior to those of double-layer solid electrolytes.

[0092] 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.

[0093] 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 polyalkylene oxide layer, characterized in that: The double-layer all-solid electrolyte comprises a polyalkylene oxide electrolyte layer and a plastic crystal electrolyte layer; the polyalkylene oxide electrolyte layer contains polyalkylene oxide, inorganic ceramic fast ion conductor filler and lithium salt; the plastic crystal electrolyte layer contains succinonitrile and lithium salt.

2. The double-layer all-solid electrolyte containing a polyalkylene oxide layer according to claim 1, wherein The polyalkylene oxide is a polyoxy lower alkane, preferably polyethylene oxide and / or polypropylene oxide.

3. The double-layer all-solid electrolyte containing a polyalkylene oxide 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 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 1.5 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 Ln3Z 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 polyalkylene oxide 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 polyalkylene oxide layer according to any one of claims 1 to 4, wherein In the polyalkylene oxide electrolyte layer, based on the total weight of the polyalkylene oxide electrolyte layer, the content of the polyalkylene oxide 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 polyalkylene oxide 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 polyalkylene oxide layer according to claim 1, wherein The polyalkylene oxide 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 polyalkylene oxide layer according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: 1) mixing the polyalkylene oxide and 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 polyalkylene oxide 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 polyalkylene oxide 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 polyalkylene oxide 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 polyalkylene oxide layer as claimed in any one of claims 1 to 7.

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