Polyalkylene oxide all-solid-state electrolyte containing nano powder rubber, preparation method of polyalkylene oxide all-solid-state electrolyte and lithium ion battery

Abstract

The invention belongs to the field of lithium ion batteries, and relates to a polyalkylene oxide all-solid-state electrolyte containing nano powder rubber, a preparation method of the polyalkylene oxide all-solid-state electrolyte and a lithium ion battery. The all-solid-state electrolyte comprises polyalkylene oxide, lithium salt, plastic crystals and nano powder rubber, on the basis of the total weight of the all-solid-state electrolyte, the content of the polyalkylene oxide is 25-60 wt%, the content of the lithium salt is 20-50 wt%, the content of the plastic crystal is 3-35 wt%, and the content of the nano powder rubber is 3-35 wt%. The all-solid-state electrolyte provided by the invention has higher conductivity and better cycle performance.

Description

Technical Field

[0001] The present invention belongs to the field of lithium ion batteries, and in particular, relates to a polyalkylene oxide all-solid electrolyte containing nano-powder rubber, a preparation method of the all-solid electrolyte, and a lithium ion battery. Background Art

[0002] As the application of lithium-ion batteries becomes more and more extensive, people are studying them more and more deeply. The main components of lithium-ion batteries include positive electrodes, negative electrodes and electrolytes. As an important part of the battery, the electrolyte is closely related to the performance of the battery. The electrolytes of commercial lithium-ion batteries are all liquid, with poor safety and energy density close to the theoretical limit. There is limited room for future development, so researchers have turned their attention to solid electrolytes.

[0003] Solid polymer electrolytes have many advantages such as low cost, high safety, and good integration, and are considered to be the development direction of the next generation of electrolytes.

[0004] 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

[0005] In view of the above situation, the purpose of the present invention is to provide a polyalkylene oxide all-solid electrolyte containing nano-powder rubber and a preparation method thereof and a lithium ion battery. The all-solid electrolyte has higher conductivity and better cycle performance.

[0006] The first aspect of the present invention provides a polyalkylene oxide all-solid electrolyte containing nano-powder rubber, the all-solid electrolyte comprising polyalkylene oxide, lithium salt, plastic crystals and nano-powder rubber; based on the total weight of the all-solid electrolyte, the content of the polyalkylene oxide is 25-60wt%, the content of the lithium salt is 20-50wt%, the content of the plastic crystals is 3-35wt%, and the content of the nano-powder rubber is 3-35wt%.

[0007] The second aspect of the present invention provides a method for preparing the above-mentioned polyalkylene oxide all-solid electrolyte containing nano-powder rubber, the preparation method comprising the following steps:

[0008] 1) mixing polyalkylene oxide, lithium salt, plastic crystal and nano-powder rubber with an organic solvent to obtain a mixed solution;

[0009] 2) The mixed solution is coated on a mold and vacuum dried to obtain an all-solid electrolyte.

[0010] A third aspect of the present invention provides a lithium ion battery, which includes a positive electrode, a negative electrode and an electrolyte, wherein the electrolyte is the above-mentioned polyalkylene oxide all-solid electrolyte containing nano-powder rubber.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] 1. The nano-powder rubber in the system of the present invention has swelling properties in organic solvents, which is beneficial to the movement and diffusion of lithium salts in the system and provides another lithium ion transmission channel in the electrolyte. In addition, the nano-powder rubber has the dual characteristics of elasticity and rigidity and also takes into account many requirements such as mechanical properties and ion transmission between electrodes. The particle size of the nano-powder rubber is conducive to reducing the porosity of the solid electrolyte and promoting the improvement of the cycle performance of the solid-state battery.

[0013] 2. The self-diffusion of the plastic crystals and the rotation of its molecules or ions in the present invention can promote the movement of lithium ions, thereby obtaining a higher ionic conductivity. Moreover, it has the dual characteristics of solid and liquid states and also takes into account many requirements such as mechanical properties and ion transmission between electrodes.

[0014] 3. The substrate used for the solid electrolyte of the present invention is polyalkylene oxide, which has good crystallinity and mechanical properties.

[0015] 4. Compared with liquid electrolytes or mixed electrolytes, the all-solid electrolyte of the present invention is safer and non-flammable.

[0016] 5. The preparation method of the all-solid electrolyte of the present invention is simple and easy, and the raw materials are easily available, which is conducive to promotion.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0019] Figure 1 It is a schematic diagram comparing the conductivity of the electrolytes prepared in Examples 1, 6-7 and Comparative Examples 1-2 at 25°C. DETAILED DESCRIPTION

[0020] 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.

[0021] The invention provides a polyalkylene oxide all-solid electrolyte containing nanometer powder rubber. The all-solid electrolyte comprises polyalkylene oxide, lithium salt, plastic crystal and nanometer powder rubber. Based on the total weight of the all-solid electrolyte, the content of the polyalkylene oxide is 25-60wt%, the content of the lithium salt is 20-50wt%, the content of the plastic crystal is 3-35wt%, and the content of the nanometer powder rubber is 3-35wt%.

[0022] Preferably, the all-solid-state electrolyte is composed of polyalkylene oxide, lithium salt, plastic crystal and nano-powder rubber. Based on the total weight of the all-solid-state electrolyte, the content of polyalkylene oxide is 35-55wt%, preferably 40-50wt%; the content of lithium salt is 25-40wt%, preferably 27-37wt%; the content of plastic crystal is 5-25wt%, preferably 8-15wt%; the content of nano-powder rubber is 5-25wt%, preferably 8-15wt%.

[0023] According to the present invention, the polyalkylene oxide may be a polyoxy lower alkane, preferably polyethylene oxide and / or polypropylene oxide. The lower alkane in the present invention is an alkane having 2 to 4 carbon atoms.

[0024] The lithium salt used in the present invention can be a lithium salt conventionally used in the art, and the lithium salt includes but is not limited to one or more 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.

[0025] According to the present invention, the plastic crystal may be at least one of succinonitrile, Li2SO4 and α-Na2SO4, preferably succinonitrile.

[0026] The present invention, nano powder rubber can use the conventional nano powder rubber used in the prior art, for example, the nano powder rubber can be at least one of nano nitrile rubber, nano carboxyl nitrile rubber, nano styrene butadiene rubber, nano carboxyl styrene butadiene rubber and nano butyl acrylate rubber, preferably nano nitrile rubber and / or nano carboxyl nitrile rubber. The particle diameter of the nano powder rubber can be a conventional particle diameter, such as 20-500nm, preferably 20-200nm.

[0027] When used in lithium-ion batteries, the all-solid electrolyte is usually prepared in a film shape, and its thickness can be set as required, for example, 60-200 μm.

[0028] According to a second aspect of the present invention, the present invention provides a method for preparing the above-mentioned polyalkylene oxide all-solid electrolyte containing nano-powder rubber, the preparation method comprising the following steps:

[0029] 1) mixing polyalkylene oxide, lithium salt, plastic crystal and nano-powder rubber with an organic solvent to obtain a mixed solution;

[0030] 2) The mixed solution is coated on a mold and vacuum dried to obtain an all-solid electrolyte.

[0031] 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 N,N-dimethylformamide.

[0032] According to the present invention, in step 1), the mass concentration of the solute in the mixed solution is 10-40%.

[0033] In the present invention, the amounts of polyalkylene oxide, lithium salt, plastic crystal and nano-powder rubber used in preparing the polyalkylene oxide all-solid electrolyte are determined according to the content of each component in the polyalkylene oxide all-solid electrolyte, and the loss during the preparation process is ignored.

[0034] In step 1) of the present invention, the mixing is carried out under stirring conditions, and the components of the all-solid electrolyte are mixed with the organic solvent, and the polyalkylene oxide and the lithium salt are fully stirred to completely dissolve to obtain a mixed solution. The mixing conditions may include: stirring at 40-75° C. for 5-12 hours.

[0035] According to the present invention, in step 2), the vacuum drying temperature is 25-80° C. and the time is 12-48 hours.

[0036] In the present invention, the mixed solution is coated on a mold to form a liquid film, and the liquid film is vacuum dried to obtain a fully solid electrolyte. The coating can be performed by various conventional methods in the art, such as solution casting. The mold can be a mold of various materials conventionally used in the art, such as a polytetrafluoroethylene mold.

[0037] 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, the electrolyte being the above-mentioned polyalkylene oxide all-solid electrolyte containing nano-powder rubber.

[0038] In the present invention, the positive electrode and the negative electrode of the lithium-ion battery can be various conventional positive and negative electrode materials, and the present invention has no special limitation on this.

[0039] 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.

[0040] In the following examples and comparative examples, the relevant raw materials and data are obtained as follows:

[0041] Polyethylene oxide: Empower Materia Co., Ltd., Japan.

[0042] Polypropylene oxide: Empower Materia Co., Ltd., Japan.

[0043] Nano-nitrile rubber: prepared according to patent document CN1152082C.

[0044] Nano carboxyl nitrile rubber: prepared with reference to patent document CN1152082C.

[0045] Nano-styrene-butadiene rubber: prepared according to patent document CN1152082C.

[0046] Nano carboxyl styrene butadiene rubber: prepared with reference to patent document CN1152082C.

[0047] Nano butyl acrylate rubber: prepared according to patent document CN1152082C.

[0048] Lithium bis(trifluoromethanesulfonate): Shanghai MacLean Biochemical Technology Co., Ltd.

[0049] Lithium bis(fluorosulfonyl)imide: Shanghai MacLean Biochemical Technology Co., Ltd.

[0050] Succinonitrile: Beijing Inokai Technology Co., Ltd.

[0051] Li2SO4: Beijing Inokai Technology Co., Ltd.

[0052] N,N-Dimethylformamide: Beijing Inokai Technology Co., Ltd.

[0053] N,N-Dimethylacetamide: Beijing Inokai Technology Co., Ltd.

[0054] Acetonitrile: Beijing Bailingwei Technology Co., Ltd.

[0055] Acetone: Beijing Inokai Technology Co., Ltd.

[0056] 1. BET specific surface area test: After the test sample was vacuum degassed at 80°C for 12 h, the nitrogen adsorption-desorption isotherm was measured at a liquid nitrogen temperature of 77 K, and the Brunauer-Emmett-Teller-(BET) specific surface area was calculated.

[0057] 2. Conductivity test: The room temperature (25° C.) conductivity of the all-solid electrolytes prepared in each embodiment and comparative example was tested using electrochemical impedance spectroscopy.

[0058] 3. Cycle performance test: 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.

[0059] Example 1

[0060] 5g of polyethylene oxide, 0.85g of succinonitrile, 0.85g of nano-nitrile rubber, 33g of N,N-dimethylformamide, and 3.48g of lithium bis(trifluoromethanesulfonate)imide were added to a 100mL flask, stirred at 40°C for 8h to obtain a uniform mixed solution, and the mixed solution was cast on a polytetrafluoroethylene mold and dried in a vacuum oven at 60°C for 24h to obtain a polyethylene oxide all-solid electrolyte. The all-solid electrolyte is in the form of a film with a thickness of 70μm. Its performance parameters are shown in Tables 1 and Figure 1 shown.

[0061] Example 2

[0062] 4g of polyethylene oxide, 0.65g of succinonitrile, 0.65g of nano-carboxylated nitrile rubber, 20g of acetonitrile, and 3g of lithium bis(trifluoromethanesulfonate)imide were added to a 250mL flask, stirred at 50°C for 10h to obtain a uniform mixed solution, cast the mixed solution on a polytetrafluoroethylene mold, and dried in a vacuum oven at 80°C for 24h to obtain a polyethylene oxide all-solid electrolyte. The all-solid electrolyte is in the form of a film with a thickness of 90μm, and its performance parameters are shown in Table 1.

[0063] Example 3

[0064] 5g polyethylene oxide, 0.8g succinonitrile, 0.8g nano-nitrile rubber, 32g N,N-dimethylacetamide, and 3.25g lithium bis(fluorosulfonyl)imide were added to a 100mL flask, stirred at 40°C for 6h to obtain a uniform mixed solution, cast the mixed solution on a polytetrafluoroethylene mold, and dried in a vacuum oven at 70°C for 24h to obtain a polyethylene oxide all-solid electrolyte. The all-solid electrolyte is in a film shape with a thickness of 90μm, and its performance parameters are shown in Table 1.

[0065] Example 4

[0066] 3.2g polyethylene oxide, 0.5g succinonitrile, 0.5g nano-carboxylated nitrile rubber, 16g acetone, and 1.6g lithium bis(fluorosulfonyl)imide were added to a 250mL flask, stirred at 70°C for 7h to obtain a uniform mixed solution, cast the mixed solution on a polytetrafluoroethylene mold, and dried in a vacuum oven at 80°C for 24h to obtain a polyethylene oxide all-solid electrolyte. The all-solid electrolyte is in the form of a film with a thickness of 190μm, and its performance parameters are shown in Table 1.

[0067] Example 5

[0068] 3.5g polyethylene oxide, 0.55g succinonitrile, 0.55g nano-styrene butadiene rubber, 20g acetonitrile, and 3g lithium bis(trifluoromethanesulfonate)imide were added to a 250mL flask, stirred at 50°C for 10h to obtain a uniform mixed solution, cast the mixed solution on a polytetrafluoroethylene mold, and dried in a vacuum oven at 80°C for 24h to obtain a polyethylene oxide all-solid electrolyte. The all-solid electrolyte is in a film shape with a thickness of 90μm, and its performance parameters are shown in Table 1.

[0069] Example 6

[0070] 4g polyethylene oxide, 0.6g Li2SO4, 0.6g nano carboxyl styrene butadiene rubber, 18g acetonitrile, and 3g lithium bis(trifluoromethanesulfonate)imide were added to a 250mL flask and stirred at 50°C for 10h to obtain a uniform mixed solution. The mixed solution was cast on a polytetrafluoroethylene mold and dried in a vacuum oven at 80°C for 24h to obtain a polyethylene oxide all-solid electrolyte. The all-solid electrolyte is in the form of a film with a thickness of 130μm. Its performance parameters are shown in Tables 1 and Figure 1 shown.

[0071] Example 7

[0072] 3g polypropylene oxide, 0.3g succinonitrile, 0.3g nano-butyl acrylate rubber, 18g acetonitrile, and 3g lithium bis(trifluoromethanesulfonate)imide were added to a 250mL flask and stirred at 50°C for 10h to obtain a uniform mixed solution. The mixed solution was cast on a polytetrafluoroethylene mold and dried in a vacuum oven at 80°C for 24h to obtain a polypropylene oxide all-solid electrolyte. The all-solid electrolyte is in the form of a film with a thickness of 150μm. Its performance parameters are shown in Tables 1 and Figure 1 shown.

[0073] Comparative Example 1

[0074] 5g polyethylene oxide, 0.85g nano-nitrile rubber, 33g N,N-dimethylformamide, and 3.48g lithium bis(trifluoromethanesulfonate)imide were added to a 100mL flask and stirred at 40°C for 8h to obtain a uniform mixed solution. The mixed solution was cast on a polytetrafluoroethylene mold and dried in a vacuum oven at 60°C for 24h to obtain a polyethylene oxide all-solid electrolyte. The all-solid electrolyte is in the form of a film with a thickness of 70μm. Its performance parameters are shown in Tables 1 and Figure 1 shown.

[0075] Comparative Example 2

[0076] 5g polyethylene oxide, 0.85g succinonitrile, 33g N,N-dimethylformamide, 3.48g lithium bis(trifluoromethanesulfonate)imide were added to a 100mL flask, stirred at 40°C for 8h to obtain a uniform mixed solution, the mixed solution was cast on a polytetrafluoroethylene mold, and dried in a vacuum oven at 60°C for 24h to obtain a polyethylene oxide all-solid electrolyte. The all-solid electrolyte is in the form of a film with a thickness of 70μm. Its performance parameters are shown in Tables 1 and Figure 1 shown.

[0077] Table 1

[0078]

[0079]

[0080] From Table 1 and Figure 1 It can be seen that the all-solid-state electrolyte of the present invention combines nano-powder rubber and plastic crystals to ensure that the solid-state electrolyte has higher conductivity and better cycle performance. The nano-powder rubber reduces the specific surface area of ​​the solid-state electrolyte membrane, providing better conditions for limiting the growth of lithium ion dendrites. The samples without the addition of plastic crystals have poor conductivity and therefore poor cycle performance. The samples without the addition of powder rubber cannot limit the generation of lithium dendrites and short-circuit.

[0081] 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.

[0082] 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 polyalkylene oxide all-solid electrolyte containing nano-powder rubber, characterized in that: The all-solid electrolyte comprises polyalkylene oxide, lithium salt, plastic crystal and nanometer powder rubber; based on the total weight of the all-solid electrolyte, the content of the polyalkylene oxide is 25-60wt%, the content of the lithium salt is 20-50wt%, the content of the plastic crystal is 3-35wt%, and the content of the nanometer powder rubber is 3-35wt%.

2. The polyalkylene oxide all-solid electrolyte containing nano-powder rubber according to claim 1, wherein: Based on the total weight of the all-solid electrolyte, the content of the polyalkylene oxide is 35-55wt%, preferably 40-50wt%; the content of the lithium salt is 25-40wt%, preferably 27-37wt%; the content of the plastic crystal is 5-25wt%, preferably 8-15wt%; the content of the nano powder rubber is 5-25wt%, preferably 8-15wt%.

3. The polyalkylene oxide all-solid electrolyte containing nano-powder rubber according to claim 1, wherein: The polyalkylene oxide is a polyoxy lower alkane, preferably polyethylene oxide and / or polypropylene oxide.

4. The polyalkylene oxide all-solid electrolyte containing nano-powder rubber 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 polyalkylene oxide all-solid electrolyte containing nano-powder rubber according to claim 1, wherein: The plastic crystal is at least one of succinonitrile, Li2SO4 and α-Na2SO4, preferably succinonitrile.

6. The polyalkylene oxide all-solid electrolyte containing nano-powder rubber according to claim 1, wherein: The nano powder rubber is at least one of nano nitrile rubber, nano carboxylated nitrile rubber, nano styrene butadiene rubber, nano carboxylated styrene butadiene rubber and nano butyl acrylate rubber, preferably nano nitrile rubber and / or nano carboxylated nitrile rubber.

7. The polyalkylene oxide all-solid electrolyte containing nano-powder rubber according to claim 1, wherein: The all-solid electrolyte is in a film shape, and its thickness is 60-200 μm.

8. The method for preparing the polyalkylene oxide all-solid electrolyte containing nano-powder rubber according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: 1) mixing polyalkylene oxide, lithium salt, plastic crystal and nano rubber powder with an organic solvent to obtain a mixed solution; 2) The mixed solution is coated on a mold and vacuum dried to obtain an all-solid electrolyte.

9. The method for preparing the polyalkylene oxide all-solid electrolyte containing nano-powder rubber 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, and more preferably N,N-dimethylformamide; the mass concentration of the solute in the mixed solution is 10-40%; the mixing conditions include: stirring at 40-75° C. for 5-12 hours; In step 2), the vacuum drying temperature is 25-80° C. and the time is 12-48 hours.

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 polyalkylene oxide all-solid electrolyte containing nano-powder rubber as claimed in any one of claims 1 to 7.

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