A blend polymer all-solid-state electrolyte containing nano-powder rubber, a preparation method thereof, and a lithium ion battery

Abstract

The application belongs to the field of batteries and relates to a blended polymer full solid-state electrolyte containing nano-powder rubber, a preparation method of the blended polymer full solid-state electrolyte and a lithium ion battery. The full solid-state electrolyte comprises a polymer blend, a lithium salt and nano-powder rubber; the polymer blend comprises polyacrylonitrile and polypropylene carbonate; the weight content of the polymer blend is 25-70%, the weight content of the lithium salt is 20-50% and the weight content of the nano-powder rubber is 3-35% based on the total weight of the full solid-state electrolyte. The full solid-state electrolyte has higher conductivity and better cycle performance.

Description

Technical Field

[0001] This invention belongs to the field of batteries, specifically relating to an all-solid-state electrolyte composed of a blend of polypropylene carbonate containing nanoparticle rubber and polyacrylonitrile, a method for preparing the all-solid-state electrolyte, and a lithium-ion battery. Background Technology

[0002] As the applications of lithium-ion batteries become increasingly widespread, research on them is also deepening. The main components of a lithium-ion battery include the positive electrode, negative electrode, and electrolyte. The electrolyte, as a crucial part of the battery, is closely related to its performance. Currently, commercially available lithium-ion battery electrolytes are all liquids, which have poor safety and their energy density is close to the theoretical limit, limiting future development potential. Therefore, researchers are increasingly turning their attention to solid-state 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] Regarding the selection of solid polymer electrolyte matrix, although the conductivity of both polypropylene carbonate and polyacrylonitrile electrolytes can meet the requirements for solid electrolyte use, solid electrolytes with polypropylene carbonate matrix have excessively high viscosity and poor mechanical properties, which is not conducive to subsequent battery assembly; while solid electrolytes with polyacrylonitrile matrix are too brittle and accompanied by warping, which also affects the subsequent battery processing.

[0005] Furthermore, solid-state batteries still face some pressing issues before achieving large-scale application. For example, polymer solid-state electrolytes have lower ionic conductivity compared to liquid electrolytes; and during battery cycling, uneven deposition of lithium metal can generate dendrites that penetrate the electrolyte, leading to short circuits and severely affecting battery cycle stability and safety. Summary of the Invention

[0006] The purpose of this invention is to provide an all-solid-state electrolyte composed of a blend of nanoparticle rubber, its preparation method, and a lithium-ion battery thereof. This all-solid-state electrolyte exhibits higher conductivity and better cycle performance.

[0007] A first aspect of the present invention provides a blended polymer all-solid electrolyte containing nanoparticle rubber, the all-solid electrolyte comprising a polymer blend, a lithium salt, and nanoparticle rubber; the polymer blend comprising polyacrylonitrile and polypropylene carbonate; based on the total weight of the all-solid electrolyte, the weight content of the polymer blend is 25-70%, the weight content of the lithium salt is 20-50%, and the weight content of the nanoparticle rubber is 3%-35%.

[0008] A second aspect of the present invention provides a method for preparing the above-mentioned blended polymer all-solid-state electrolyte, comprising the following steps:

[0009] 1) Mix the components of the all-solid electrolyte with an organic solvent to obtain a mixed solution;

[0010] 2) The solution is dried under vacuum to obtain the all-solid electrolyte.

[0011] 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 aforementioned blended polymer all-solid-state electrolyte.

[0012] The present invention has the following advantages:

[0013] 1. The nanopowder 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 transport channel in the electrolyte. In addition, the nanopowder rubber has both elastic and rigid characteristics, which also takes into account many requirements such as mechanical properties and ion transport between electrodes. The particle size of the nanopowder rubber is beneficial to reducing the porosity of the solid electrolyte and promoting the improvement of the cycle performance of solid batteries.

[0014] 2. The all-solid electrolyte polymer matrix of the present invention is a blend of polypropylene carbonate and polyacrylonitrile. The two polymers have good compatibility, and the obtained differential scanning calorimetry curve has only one glass transition temperature peak. Such good compatibility can improve the conductivity of the electrolyte and is also beneficial to the cycle performance of the battery.

[0015] 3. Compared with liquid electrolytes or mixed electrolytes, the all-solid electrolyte of the present invention has good safety and is not flammable.

[0016] 4. The preparation method of the all-solid electrolyte of the present invention is simple and easy to implement, the raw materials are readily available, and it is conducive to promotion.

[0017] 5. The system of the present invention preferably contains plastic crystals. The self-diffusion of plastic crystals and the rotation of their molecules or ions can promote the movement of lithium ions, resulting in high ionic conductivity. Moreover, it has both solid and liquid characteristics, and also takes into account many requirements such as mechanical properties and ion transport between electrodes, so that the resulting all-solid electrolyte has a tensile strength of more than 20 MPa.

[0018] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0019] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0020] Figure 1The image shows the DSC analysis curve of the all-solid electrolyte obtained in Example 1.

[0021] Figure 2 The image shows the DSC analysis curve of the all-solid electrolyte obtained in Example 9. Detailed Implementation

[0022] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0023] This invention provides a blended polymer all-solid electrolyte containing nanoparticle rubber. The all-solid electrolyte comprises a polymer blend, a lithium salt, and nanoparticle rubber. The polymer blend comprises polyacrylonitrile and polypropylene carbonate. Based on the total weight of the all-solid electrolyte, the weight content of the polymer blend is 25-70%, the weight content of the lithium salt is 20-50%, and the weight content of the nanoparticle rubber is 3-35%.

[0024] According to a preferred embodiment of the present invention, the all-solid electrolyte is composed of a polymer blend, a lithium salt, and nanopowder rubber. Based on the total weight of the all-solid electrolyte, the weight content of the polymer blend is 40-65%, preferably 50-60%; the weight content of the lithium salt is 25-40%, preferably 27-38%; and the weight content of the nanopowder rubber is 5-25%, preferably 8-15%.

[0025] According to a preferred embodiment of the present invention, the polymer component of the all-solid electrolyte is composed of polyacrylonitrile and polypropylene carbonate, and the differential scanning calorimetry curve of the all-solid electrolyte has only one glass transition temperature peak in the range of 5.8℃-91.5℃.

[0026] According to a more preferred embodiment of the present invention, the all-solid electrolyte further includes plastic crystals, and the weight content of the plastic crystals is 3-35%, preferably 5-25%, and more preferably 6-15%, based on the total weight of the all-solid electrolyte.

[0027] Specifically, the all-solid electrolyte is composed of a polymer blend, a lithium salt, a plastic crystal, and nano-powder rubber. Based on the total weight of the all-solid electrolyte, the weight content of the polymer blend is 35-55%, preferably 40-52%; the weight content of the lithium salt is 25-40%, preferably 27-37%; and the weight content of the nano-powder rubber is 5-25%, preferably 6-15%.

[0028] According to the present invention, preferably, the plastic crystal is one or more of succinate, Li2SO4 and α-Na2SO4, more preferably succinate.

[0029] According to a specific embodiment of the present invention, when the all-solid electrolyte includes plastic crystals, the polymer component of the all-solid electrolyte is composed of polyacrylonitrile and polypropylene carbonate, and the differential scanning calorimetry curve of the all-solid electrolyte has only one glass transition temperature peak in the range of 1.3℃ to 86.1℃.

[0030] According to a preferred embodiment of the present invention, the weight ratio of the polyacrylonitrile to the polypropylene carbonate is 0.25-15:1, preferably 1-12:1, and more preferably 3-10:1. For example, it can be 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, and other ratios within the above ranges. Controlling the weight ratio of the polyacrylonitrile to the polypropylene carbonate within the preferred range can achieve higher conductivity and better battery performance.

[0031] According to a preferred embodiment of the present invention, the nanopowder rubber is one or more of nitrile rubber, carboxylated nitrile rubber, styrene-butadiene rubber, carboxylated styrene-butadiene rubber, and butyl acrylate rubber, preferably nitrile rubber and / or carboxylated nitrile rubber.

[0032] The lithium salt used in this invention can be a conventional choice in the art, including but not limited to one or more of lithium bis(trifluoromethanesulfonate)imide, lithium hexafluorophosphate, lithium bis(fluorosulfonate)imide, lithium perchlorate, lithium tetrafluorophosphate, lithium difluorophosphate, lithium bis(oxalate)borate, and lithium di(oxalate)borate; preferably lithium hexafluorophosphate and / or lithium bis(trifluoromethanesulfonate)imide.

[0033] When used in lithium-ion batteries, the all-solid electrolyte is usually prepared as a film, the thickness of which can be set as needed, for example, 50-300 μm, preferably 60-200 μm.

[0034] This invention also provides a method for preparing the above-mentioned blended polymer all-solid-state electrolyte, comprising the following steps:

[0035] 1) Mix the components of the all-solid electrolyte with an organic solvent to obtain a mixed solution;

[0036] 2) The mixed solution is vacuum dried to obtain the all-solid electrolyte.

[0037] To prepare the film-like all-solid electrolyte, step 2) may include:

[0038] 2-1) The mixed solution is coated onto a carrier to form a liquid film; the coating can be performed using various methods conventional in the art, such as solution casting.

[0039] 2-2) The liquid film is vacuum dried to obtain the all-solid electrolyte.

[0040] According to a preferred embodiment of the present invention, in step 1), the mass concentration of the solute in the mixed solution is 10-40%.

[0041] According to a preferred embodiment of the present invention, in step 1), the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile and acetone, preferably acetonitrile and / or N,N-dimethylformamide.

[0042] According to a preferred embodiment of the present invention, in step 1), the mixing is carried out under stirring conditions. Step 1) includes: mixing each component of the all-solid electrolyte with an organic solvent, and stirring thoroughly to completely dissolve the polymer blend and lithium salt to obtain a mixed solution; the stirring is preferably carried out at 35-75°C.

[0043] According to a preferred embodiment of the present invention, in step 2), the vacuum drying temperature is 30-90°C and the time is 12-48 hours.

[0044] This invention also provides a lithium-ion battery, comprising a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte is the all-solid-state electrolyte described above. The positive and negative electrodes of the lithium-ion battery can be made of various conventional positive and negative electrode materials, and this invention does not impose any particular limitation on them.

[0045] The present invention will be further described below with reference to the embodiments, but the scope of the present invention is not limited to these embodiments.

[0046] Example 1

[0047] 1.92 g of polyacrylonitrile, 0.48 g of polypropylene carbonate, 0.6 g of nitrile rubber, 10 g of N,N-dimethylformamide, and 1.8 g of lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a homogeneous solution. The solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte was in the form of a film with a thickness of 70 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 61.7 °C.

[0048] Example 2

[0049] 3.6 g of polyacrylonitrile, 0.4 g of polypropylene carbonate, 1 g of carboxylated nitrile rubber, 18 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 homogeneous mixed solution. The mixed solution was cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 80 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte is in the form of a film with a thickness of 90 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 85.7 °C.

[0050] Example 3

[0051] 1.28 g of polyacrylonitrile, 0.32 g of polypropylene carbonate, 0.4 g of nitrile rubber, 6 g of N,N-dimethylacetamide, and 1.0 g of lithium difluorosulfonylimide were added to a 100 mL flask and stirred at 40 °C for 6 h to obtain a homogeneous mixed solution. The mixed solution was cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 70 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte is in the form of a film with a thickness of 90 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 59.8 °C.

[0052] Example 4

[0053] 2.56 g of polyacrylonitrile, 0.64 g of polypropylene carbonate, 0.8 g of carboxylated nitrile rubber, 16 g of acetone, and 1.6 g of lithium difluorosulfonyl imide were added to a 250 mL flask and stirred at 70 °C for 7 h to obtain a homogeneous mixed solution. This solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 80 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte is in the form of a film with a thickness of 190 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 65.6 °C.

[0054] Example 5

[0055] 2.8 g of polyacrylonitrile, 0.7 g of polypropylene carbonate, 1.5 g of styrene-butadiene rubber, 18 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 homogeneous mixed solution. This solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 80 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte was in the form of a film with a thickness of 90 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 41.5 °C.

[0056] Example 6

[0057] 3.2 g of polyacrylonitrile, 0.8 g of polypropylene carbonate, 1 g of carboxylated styrene-butadiene rubber, 18 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 homogeneous mixed solution. This solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 80 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte was in the form of a film with a thickness of 130 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 47.8 °C.

[0058] Example 7

[0059] 2.4 g of polyacrylonitrile, 0.6 g of polypropylene carbonate, 2 g of butyl acrylate rubber, 18 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 homogeneous mixed solution. This solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 80 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte was in the form of a film with a thickness of 150 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 31.9 °C.

[0060] Example 8

[0061] 0.48 g of polyacrylonitrile, 1.92 g of polypropylene carbonate, 0.6 g of nitrile rubber, 10 g of N,N-dimethylformamide, and 1.8 g of lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a homogeneous solution. This solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 50 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte was in the form of a film with a thickness of 100 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 24.6 °C.

[0062] Comparative Example 1

[0063] 2.4 g of polyacrylonitrile, 0.6 g of nitrile rubber, 10 g of N,N-dimethylformamide, and 1.8 g of lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a homogeneous solution. The solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 24 h to obtain a polyacrylonitrile all-solid-state electrolyte. This all-solid-state electrolyte is in the form of a film with a thickness of 70 μm.

[0064] Comparative Example 2

[0065] 2.4 g of polypropylene carbonate, 0.6 g of nitrile rubber, 10 g of N,N-dimethylformamide, and 1.8 g of lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a homogeneous solution. This solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 24 h to obtain the polypropylene carbonate all-solid electrolyte. This all-solid electrolyte does not form a film and cannot be used in all-solid electrolyte applications.

[0066] Comparative Example 3

[0067] 2.4 g of polyacrylonitrile, 0.6 g of polypropylene carbonate, 10 g of N,N-dimethylformamide, and 1.8 g of lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a homogeneous solution. The solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid electrolyte. This all-solid electrolyte is in the form of a film with a thickness of 70 μm.

[0068] Comparative Example 4

[0069] 2.4 g of polyacrylonitrile, 0.6 g of polyethylene oxide, 0.6 g of carboxylated nitrile rubber, 10 g of N,N-dimethylformamide, and 2.1 g of lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a homogeneous mixed solution. The mixed solution was cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 24 h to obtain a polyacrylonitrile-polyethylene oxide all-solid-state electrolyte. This all-solid-state electrolyte is in the form of a film with a thickness of 70 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte revealed two glass transition temperature peaks at -34.3 °C and 64.5 °C.

[0070] Comparative Example 5

[0071] 2.4 g of polypropylene carbonate, 0.6 g of polyethylene oxide, 0.6 g of carboxylated acrylonitrile rubber, 10 g of N,N-dimethylformamide, and 2.1 g of lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a homogeneous solution. This solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 24 h to obtain a polypropylene carbonate-polyethylene oxide all-solid-state electrolyte. This all-solid-state electrolyte does not form a film and cannot be used in all-solid-state electrolyte applications.

[0072] Test Example 1

[0073] DSC analysis was performed on the polymer blend electrolytes prepared in Examples 1-8 and Comparative Example 4. Specifically, the temperature was increased from -50°C to 150°C at a rate of 10°C / min, held at that temperature for 1 minute, then decreased from 150°C to -50°C at a rate of 10°C / min, held at that temperature for 1 minute, and then increased from -50°C to 150°C at a rate of 10°C / min. The DSC curve obtained after the second heating was used as the DSC analysis curve. The DSC analysis curve of the all-solid-state electrolyte obtained in Example 1 is shown below. Figure 1 As shown.

[0074] BET specific surface area test: After the test sample was degassed in vacuum at 80℃ for 12h, the nitrogen adsorption-desorption isotherm was measured at liquid nitrogen temperature of 77K, and the Brunauer-Emmett-Teller-(BET) specific surface area was calculated.

[0075] The room temperature (25°C) ionic conductivity of the all-solid-state electrolyte composite membranes prepared in Examples 1-8 and Comparative Examples 1-5 was tested based on electrochemical impedance spectroscopy, and the results are as follows: Figure 2 As shown in Table 1.

[0076] A solid-state battery was prepared by assembling a lithium iron phosphate cathode, a lithium metal anode, and the solid electrolyte used, and then its cycle performance was tested at a charge-discharge rate of 0.5C.

[0077] Table 1

[0078]

[0079]

[0080] As can be seen from Table 1, because the nanopowder rubber reduces the specific surface area of ​​the solid electrolyte membrane, it provides better conditions for limiting the growth of lithium-ion dendrites, and the number of cycles with nanopowder rubber is greater. Under the same conditions, compared with the all-solid electrolyte composed of other blend systems, the all-solid electrolyte obtained by the polyacrylonitrile-polypropylene carbonate blend system of this invention has a higher room temperature conductivity.

[0081] Furthermore, the all-solid electrolyte of the present invention also has significant advantages compared with all-solid electrolytes based on a single polymer system: the room temperature conductivity of polyacrylonitrile solid electrolyte is worse than that of blended solid electrolyte, and polyacrylonitrile solid electrolyte is too brittle, which is not conducive to the subsequent use of the electrolyte; polypropylene carbonate solid electrolyte cannot form a film after being blended with plastic crystals, and therefore cannot be used in solid-state batteries.

[0082] Example 9

[0083] 4 g of polyacrylonitrile, 1 g of polypropylene carbonate, 0.85 g of succinic anionyl nitrile, 0.85 g of nitrile rubber, 33 g of N,N-dimethylformamide, and 3.48 g of lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a homogeneous solution. This solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte was in the form of a film with a thickness of 70 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 58.5 °C.

[0084] Example 10

[0085] 3.6 g of polyacrylonitrile, 0.4 g of polypropylene carbonate, 0.65 g of succinic anionyl nitrile, 0.65 g of carboxylated nitrile rubber, 20 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 homogeneous mixed solution. The mixed solution was cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 80 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte is in the form of a film with a thickness of 90 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 81.6 °C.

[0086] Example 11

[0087] 4 g of polyacrylonitrile, 1 g of polypropylene carbonate, 0.8 g of succinic anionyl nitrile, 0.8 g of nitrile rubber, 32 g of N,N-dimethylacetamide, and 3.25 g of lithium difluorosulfonyl imide were added to a 100 mL flask and stirred at 40 °C for 6 h to obtain a homogeneous mixed solution. The mixed solution was cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 70 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte is in the form of a film with a thickness of 90 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 56.6 °C.

[0088] Example 12

[0089] 2.56 g of polyacrylonitrile, 0.64 g of polypropylene carbonate, 0.5 g of succinic anionyl nitrile, 0.5 g of carboxylated nitrile rubber, 16 g of acetone, and 1.6 g of lithium difluorosulfonyl imide were added to a 250 mL flask and stirred at 70 °C for 7 h to obtain a homogeneous mixed solution. The mixed solution was cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 80 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte is in the form of a film with a thickness of 190 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve only had a glass transition temperature peak at 63.0 °C.

[0090] Example 13

[0091] 2.8 g of polyacrylonitrile, 0.7 g of polypropylene carbonate, 0.55 g of succinic anionyl nitrile, 0.55 g of styrene-butadiene rubber, 20 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 homogeneous mixed solution. The mixed solution was cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 80 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte is in the form of a film with a thickness of 90 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 37.3 °C.

[0092] Example 14

[0093] 3.2 g of polyacrylonitrile, 0.8 g of polypropylene carbonate, 0.6 g of Li₂SO₄, 0.6 g of carboxylated styrene-butadiene rubber, 18 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 homogeneous mixed solution. This solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 80 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte was in the form of a film with a thickness of 130 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 44.1 °C.

[0094] Example 15

[0095] 2.4 g of polyacrylonitrile, 0.6 g of polypropylene carbonate, 0.3 g of succinic anionyl nitrile, 0.3 g of butyl acrylate rubber, 18 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 homogeneous mixed solution. The mixed solution was cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 80 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte is in the form of a film with a thickness of 150 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 28.2 °C.

[0096] Example 16

[0097] 0.48 g of polyacrylonitrile, 1.92 g of polypropylene carbonate, 0.85 g of succinic anionyl nitrile, 0.85 g of nitrile butadiene rubber, 10 g of N,N-dimethylformamide, and 1.8 g of lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a homogeneous mixed solution. The mixed solution was cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 50 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid-state electrolyte. This all-solid-state electrolyte is in the form of a film with a thickness of 100 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte showed that the DSC curve exhibited only a glass transition temperature peak at 21.9 °C.

[0098] Comparative Example 6

[0099] 5 g of polyacrylonitrile, 0.85 g of succinic anionyl nitrile, 0.85 g of nitrile rubber, 33 g of N,N-dimethylformamide, and 3.48 g of lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a homogeneous mixed solution. The mixed solution was cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 24 h to obtain a polyacrylonitrile all-solid electrolyte. This all-solid electrolyte is in the form of a film with a thickness of 70 μm.

[0100] Comparative Example 7

[0101] 5g of polypropylene carbonate, 0.85g of succinic anhydride, 0.85g of nitrile butadiene rubber, 33g of N,N-dimethylformamide, and 3.48g of lithium bis(trifluoromethanesulfonate)imide were added to a 100mL flask and stirred at 40℃ for 8 hours to obtain a homogeneous solution. This solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 60℃ for 24 hours to obtain a polypropylene carbonate all-solid electrolyte. This all-solid electrolyte does not form a film and cannot be used in all-solid electrolyte applications.

[0102] Comparative Example 8

[0103] 4 g of polyacrylonitrile, 1 g of polypropylene carbonate, 30 g of N,N-dimethylformamide, and 3.48 g of lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a homogeneous solution. The solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid electrolyte. This all-solid electrolyte is in the form of a film with a thickness of 70 μm.

[0104] Comparative Example 9

[0105] 4 g of polyacrylonitrile, 1 g of polypropylene carbonate, 1.7 g of succinic anionyl nitrile, 33 g of N,N-dimethylformamide, and 3.48 g of lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a homogeneous mixed solution. The mixed solution was cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 24 h to obtain a polyacrylonitrile-polypropylene carbonate all-solid electrolyte. This all-solid electrolyte is in the form of a film with a thickness of 70 μm.

[0106] Comparative Example 10

[0107] 4 g of polyacrylonitrile, 1 g of polyethylene oxide, 0.85 g of succinic anionyl nitrile, 0.85 g of nitrile butadiene rubber, 33 g of N,N-dimethylformamide, and 3.48 g of lithium bis(trifluoromethanesulfonate)imide were added to a 100 mL flask and stirred at 40 °C for 8 h to obtain a homogeneous mixed solution. The mixed solution was cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 60 °C for 24 h to obtain a polyacrylonitrile-polyethylene oxide all-solid-state electrolyte. This all-solid-state electrolyte is in the form of a film with a thickness of 70 μm. Differential scanning calorimetry (DSC) analysis of the all-solid-state electrolyte revealed two glass transition temperature peaks at -37.9 °C and 60.7 °C.

[0108] Comparative Example 11

[0109] 4g of polypropylene carbonate, 1g of polyethylene oxide, 0.85g of succinic anhydride, 0.85g of nitrile butadiene rubber, 33g of N,N-dimethylformamide, and 3.48g of lithium bis(trifluoromethanesulfonate)imide were added to a 100mL flask and stirred at 40℃ for 8 hours to obtain a homogeneous solution. This solution was then cast onto a polytetrafluoroethylene mold and dried in a vacuum oven at 60℃ for 24 hours to obtain a polypropylene carbonate-polyethylene oxide all-solid-state electrolyte. This all-solid-state electrolyte does not form a film and cannot be used in all-solid-state electrolyte applications.

[0110] Test Example 2

[0111] DSC analysis was performed on the polymer blend electrolytes prepared in Examples 9-16 and Comparative Example 10. Specifically, the temperature was increased from -50°C to 150°C at a rate of 10°C / min, held at that temperature for 1 minute, then decreased from 150°C to -50°C at a rate of 10°C / min, held at that temperature for 1 minute, and then increased from -50°C to 150°C at a rate of 10°C / min. The DSC curve obtained after the second heating was used as the DSC analysis curve. The DSC analysis curve of the all-solid-state electrolyte obtained in Example 9 is shown below. Figure 2 As shown.

[0112] BET specific surface area test: After the test sample was degassed in vacuum at 80℃ for 12h, the nitrogen adsorption-desorption isotherm was measured at liquid nitrogen temperature of 77K, and the Brunauer-Emmett-Teller-(BET) specific surface area was calculated.

[0113] The room temperature (25°C) ionic conductivity of the all-solid electrolyte composite membranes prepared in Examples 9-16 and Comparative Examples 6-11 was tested based on electrochemical impedance spectroscopy, and the results are shown in Table 2.

[0114] Solid-state batteries were prepared by assembling a lithium iron phosphate cathode, a lithium metal anode, and the solid electrolytes prepared in Examples 9-16 and Comparative Examples 6-11, and then cycle performance was tested at a charge-discharge rate of 0.5C.

[0115] Table 2

[0116]

[0117]

[0118] As can be seen from Table 2, in addition to the advantages of the aforementioned nanopowder rubber and polymer blends, the plastic crystals have higher diffusion rate and stronger plasticity, providing better conditions for the dissolution and conduction of lithium ions. The all-solid electrolytes prepared in Examples 9-16 with added plastic crystals have higher room temperature conductivity and lower specific surface area under the same polymer system, resulting in more battery cycle times.

[0119] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0120] The endpoints and any values ​​of the ranges disclosed herein 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 the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A blend polymer all-solid-state electrolyte containing nano-powdered rubber, characterized in that, The all-solid electrolyte comprises a polymer blend, a lithium salt, and nanoparticle rubber; the polymer blend is composed of polyacrylonitrile and polypropylene carbonate; based on the total weight of the all-solid electrolyte, the weight content of the polymer blend is 25-70%, the weight content of the lithium salt is 20-50%, and the weight content of the nanoparticle rubber is 3-35%. The weight ratio of the polyacrylonitrile to the polypropylene carbonate is 0.25-15:1; The nanopowder rubber is one or more of nitrile rubber, carboxylated nitrile rubber, styrene-butadiene rubber, carboxylated styrene-butadiene rubber, and butyl acrylate rubber.

2. The all-solid-state electrolyte of the blended polymer according to claim 1, wherein, Based on the total weight of the all-solid electrolyte, the polymer blend has a weight content of 40-65%; the lithium salt has a weight content of 25-40%; and the nanopowder rubber has a weight content of 5-25%.

3. The blended polymer all-solid-state electrolyte according to claim 2, wherein, Based on the total weight of the all-solid electrolyte, the polymer blend has a weight content of 50-60%, the lithium salt has a weight content of 27-38%, and the nanopowder rubber has a weight content of 8-15%.

4. The all-solid-state electrolyte of the blended polymer according to claim 1, wherein, The differential scanning calorimetry (DSC) curve of the all-solid electrolyte shows only one glass transition temperature peak in the range of 5.8℃ to 91.5℃.

5. The all-solid-state electrolyte of the blended polymer according to claim 1, wherein, The all-solid electrolyte also includes plastic crystals, and the weight content of the plastic crystals is 3-35% based on the total weight of the all-solid electrolyte.

6. The blended polymer all-solid-state electrolyte according to claim 5, wherein, Based on the total weight of the all-solid electrolyte, the weight content of the plastic crystal is 5-25%.

7. The all-solid-state electrolyte of the blended polymer according to claim 6, wherein, Based on the total weight of the all-solid electrolyte, the weight content of the plastic crystal is 6-15%.

8. The all-solid-state electrolyte of the blended polymer according to claim 5, wherein, Based on the total weight of the all-solid electrolyte, the polymer blend has a weight content of 35-55%; the lithium salt has a weight content of 25-40%; and the nanopowder rubber has a weight content of 5-25%.

9. The all-solid-state electrolyte of the blended polymer according to claim 8, wherein, Based on the total weight of the all-solid electrolyte, the polymer blend has a weight content of 40-52%, the lithium salt has a weight content of 27-37%, and the nanopowder rubber has a weight content of 6-15%.

10. The all-solid-state electrolyte of the blended polymer according to claim 5, wherein, The plastic crystal is one or more of succinic acid, Li2SO4 and α-Na2SO4.

11. The all-solid-state electrolyte of the blended polymer according to claim 10, wherein, The plastic crystal is succinic acid nitrile.

12. The all-solid-state electrolyte of the blended polymer according to claim 5, wherein, The polymer component of the all-solid electrolyte is composed of polyacrylonitrile and polypropylene carbonate. The differential scanning calorimetry (DSC) curve of the all-solid electrolyte has only one glass transition temperature peak in the range of 1.3℃ to 86.1℃.

13. The all-solid-state electrolyte of the blended polymer according to any one of claims 1-12, wherein, The weight ratio of the polyacrylonitrile to the polypropylene carbonate is 1-12:

1.

14. The all-solid-state electrolyte of the blended polymer according to claim 13, wherein, The weight ratio of the polyacrylonitrile to the polypropylene carbonate is 3-10:

1.

15. The all-solid-state electrolyte of the blended polymer according to any one of claims 1-12, wherein, The nanopowder rubber is nitrile rubber and / or carboxylated nitrile rubber.

16. The all-solid-state electrolyte of the blended polymer according to any one of claims 1-12, wherein, The lithium salt is one or more of lithium bis(trifluoromethanesulfonate)imide, lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium perchlorate, lithium tetrafluorophosphate, lithium difluorophosphate, lithium bis(oxalate)borate, and lithium di(oxalate)borate.

17. The all-solid-state electrolyte of the blended polymer according to claim 16, wherein, The lithium salt is lithium hexafluorophosphate and / or lithium bis(trifluoromethanesulfonate)imide.

18. The all-solid-state electrolyte of the blended polymer according to any one of claims 1-12, wherein, The all-solid electrolyte is in the form of a film with a thickness of 50-300 μm.

19. The all-solid-state electrolyte of the blended polymer according to claim 18, wherein, The all-solid electrolyte is in the form of a film with a thickness of 60-200 μm.

20. A method for preparing the blended polymer all-solid-state electrolyte according to any one of claims 1-19, comprising the following steps: 1) Mix the components of the all-solid electrolyte with an organic solvent to obtain a mixed solution; 2) The mixed solution is vacuum dried to obtain the all-solid electrolyte.

21. The preparation method according to claim 20, wherein, Step 2) includes: 2-1) The mixed solution is coated onto a carrier using a solution casting method to form a liquid film; 2-2) The liquid film is vacuum dried to obtain the all-solid electrolyte.

22. The preparation method according to claim 20 or 21, wherein, In step 1), the mass concentration of the solute in the mixed solution is 10-40%; the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, and acetone; the mixing is carried out under stirring conditions. In step 2), the vacuum drying temperature is 30-90℃ and the time is 12-48 hours.

23. The preparation method according to claim 22, wherein, The organic solvent is acetonitrile and / or N,N-dimethylformamide.

24. The preparation method according to claim 23, wherein, The organic solvent is N,N-dimethylformamide.

25. The preparation method according to claim 22, wherein, The stirring is carried out at 35-75°C.

26. A lithium-ion battery, characterized in that, The lithium-ion battery includes a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte is a blended polymer all-solid-state electrolyte as described in any one of claims 1-19.

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