Self-repairing polymer electrolyte, preparation method and application thereof, and polymer lithium battery

Abstract

The invention discloses a self-repairing polymer electrolyte, a preparation method and application thereof, and a polymer lithium battery, the self-repairing polymer electrolyte comprises the following preparation raw materials by mass: 50-100 parts of polysiloxane diacrylate, 1-10 parts of disulfide diacrylate, 10-40 parts of a cross-linking agent, 60-120 parts of a plasticizer, 60-120 parts of a lithium salt, and 1-10 parts of a photoinitiator. According to the self-repairing polymer electrolyte disclosed by the invention, a thiol-ene click reaction can be carried out between carbon-carbon double bonds in polysiloxane diacrylate and disulfide diacrylate and sulfydryl of the cross-linking agent, so that a dynamic disulfide bond and hydrogen bond network structure is endowed to the self-repairing polymer electrolyte; and the dynamic disulfide bond and the hydrogen bond can enable the electrolyte membrane to realize self-healing at room temperature without external stimulation.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and more specifically, to a self-repairing polymer electrolyte, a preparation method and application thereof, and a polymer lithium battery. Background Art

[0002] Traditional lithium-ion batteries face safety challenges in practical applications due to the use of liquid electrolytes. Solid-state electrolytes can solve this challenge and have attracted more and more attention. However, traditional lithium batteries are difficult to use in flexible devices and large-scale equipment due to their poor flexibility and low energy density. Therefore, researchers have extensively studied polymer lithium batteries with high energy density, flexibility and manufacturability to meet consumer demand for large-scale equipment. As a key component of lithium-ion batteries, solid-state electrolyte membranes will definitely be affected by external forces during assembly and use, causing certain damage to the solid-state electrolyte membrane, thereby affecting the service life and safety of lithium-ion batteries. Therefore, it is a technical problem that urgently needs to be solved in this field. Summary of the invention

[0003] In view of this, the present invention provides a self-healing polymer electrolyte to solve the problem in the prior art that the solid electrolyte membrane may be affected by external forces during assembly and use, causing certain damage to the electrolyte membrane and affecting the service life and safety of the battery.

[0004] In a first aspect, the present application provides a self-healing polymer electrolyte, which is composed of the following preparation raw materials, in parts by mass, 50 to 100 parts of polysiloxane diacrylate, 1 to 10 parts of disulfide diacrylate, 10 to 40 parts of a cross-linking agent, 60 to 120 parts of a plasticizer, 60 to 120 parts of a lithium salt and 1 to 10 parts of a photoinitiator.

[0005] Optionally, the preparation method is composed of the following raw materials, in parts by mass: 55 to 90 parts of the polysiloxane diacrylate, 2 to 8 parts of the disulfide diacrylate, 10 to 30 parts of the cross-linking agent, 70 to 100 parts of the plasticizer, 70 to 100 parts of the lithium salt and 1 to 8 parts of the photoinitiator.

[0006] Optionally, the raw materials for synthesizing the polysiloxane diacrylate include polydimethylsiloxane, isocyanoethyl methacrylate and an organic solvent.

[0007] Optionally, the mass ratio of the polydimethylsiloxane, isocyanoethyl methacrylate and the organic solvent is in the range of (8-20):(3-10):(40-80).

[0008] Optionally, the polydimethylsiloxane is aminopropyl-terminated polydimethylsiloxane, and its molecular weight ranges from 800 to 10000 g / mol.

[0009] Optionally, the plasticizer includes one or more of succinonitrile, sebaconitrile, N,N-dimethyltrifluoroacetamide, and N-methylacetamide.

[0010] In a second aspect, the present application provides a method for preparing a self-healing polymer electrolyte, comprising the following steps:

[0011] Firstly, the lithium salt and the plasticizer are heated and stirred, then the polysiloxane diacrylate, the disulfide diacrylate and the crosslinking agent are mixed, and finally the photoinitiator is mixed to obtain a precursor solution;

[0012] The precursor solution is cured by ultraviolet light to obtain a self-healing polymer electrolyte.

[0013] Optionally, the preparation method of the polysiloxane diacrylate comprises the following steps:

[0014] In a nitrogen atmosphere, polydimethylsiloxane, isocyanoethyl methacrylate and an organic solvent are mixed to obtain the polysiloxane diacrylate.

[0015] In a third aspect, the present application also provides an application of the above-mentioned self-healing polymer electrolyte in a polymer lithium battery.

[0016] In a fourth aspect, the present application also provides a polymer lithium battery, a positive electrode, a negative electrode and an electrolyte between the positive and negative electrodes, wherein the electrolyte is the above-mentioned self-healing polymer electrolyte.

[0017] Compared with the prior art, the self-healing polymer electrolyte, preparation method and application thereof, and polymer lithium battery provided by the present invention achieve at least the following beneficial effects:

[0018] The present invention provides a self-healing polymer electrolyte, a preparation method and application thereof, and a polymer lithium battery. The self-healing polymer electrolyte is composed of the following raw materials by mass: 50 to 100 parts of polysiloxane diacrylate, 1 to 10 parts of disulfide diacrylate, 10 to 40 parts of a cross-linking agent, 60 to 120 parts of a plasticizer, 60 to 120 parts of a lithium salt, and 1 to 10 parts of a photoinitiator. The above scheme is adopted to utilize the thiol-ene click reaction between the carbon-carbon double bonds in polysiloxane diacrylate and disulfide diacrylate and the thiol group of the cross-linking agent to give the self-healing polymer electrolyte a dynamic disulfide bond and hydrogen bond network structure, and the dynamic disulfide bond and hydrogen bond can enable the electrolyte membrane to achieve self-healing at room temperature without external stimulation. According to the description of Example 4, the ionic conductivity of the self-healing polymer electrolyte described in the present invention reaches 4.75×10 -4 S cm -1; The polymer lithium battery (such as lithium iron phosphate battery) assembled using the self-healing polymer electrolyte as the electrolyte has a discharge capacity of 150mAh g after 100 cycles at a rate of 0.5C. -1 .

[0019] Of course, any product implementing the present invention does not necessarily need to achieve all of the technical effects described above at the same time.

[0020] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0022] Figure 1 It is a flow chart of the preparation method of the self-healing polymer electrolyte provided by the present invention;

[0023] Figure 2 The infrared spectra of octa(3-mercaptopropyl)-POSS (POSS-SH), diphenyl disulfide bis(2-methylacrylamide) and polysiloxane diacrylate in the self-healing gel polymer electrolyte obtained in Example 4;

[0024] Figure 3 This is a graph showing the change in ionic conductivity of the self-healing polymer electrolyte prepared in Example 4 as a function of temperature;

[0025] Figure 4 The self-repairing process of the self-repairing gel polymer electrolyte membrane prepared in Example 4 at room temperature;

[0026] Figure 5 This is a cycle test diagram of a button cell assembled with the self-healing polymer electrolyte prepared in Example 4 as the electrolyte at room temperature at a rate of 0.5C;

[0027] Figure 6 The Li / / Li symmetric button cell assembled with the self-healing polymer electrolyte prepared in Example 4 was tested at 0.1 mA cm -2 Cyclic stability curves at different current densities. DETAILED DESCRIPTION

[0028] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0029] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0030] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0031] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0032] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0033] The present embodiment provides a self-healing polymer electrolyte, which is composed of the following preparation raw materials, by weight, 50 to 100 parts of polysiloxane diacrylate, 1 to 10 parts of disulfide diacrylate, 10 to 40 parts of a cross-linking agent, 60 to 120 parts of a plasticizer, 60 to 120 parts of a lithium salt and 1 to 10 parts of a photoinitiator.

[0034] The above-mentioned self-healing polymer electrolyte can be a self-healing three-dimensional cross-linked network gel polymer electrolyte (self-healing 3D cross-linked network gel polymer electrolyte), which is an electrolyte material with self-healing ability and a three-dimensional cross-linked network structure, so that when the self-healing polymer electrolyte is damaged or broken, it can automatically repair the damage, thereby restoring its original function and performance. At the same time, the three-dimensional cross-linked network structure not only has higher mechanical strength and stability, but also provides more channels and paths for the transmission of lithium ions, which helps to improve the transmission efficiency of lithium ions.

[0035] Usually the ionic conductivity of pure polymers is less than 10-4S / cm -2 The introduction of plasticizer is beneficial to improving the ionic conductivity of the electrolyte membrane and improving the compatibility of the interface. The plasticizer can form hydrogen bonds with the polysiloxane in the polysiloxane diacrylate, thereby increasing the thermal stability of the network polymer. The network polymer is formed by the reaction between the thiol group and the double bond of the polysiloxane diacrylate, disulfide diacrylate, and the crosslinking agent, wherein the NH in the network polymer can form hydrogen bonds with the NH in the plasticizer.

[0036] In a certain proportion, the network polymer formed by polysiloxane diacrylate and crosslinking agent exhibits the best mechanical strength, and the plasticizer and lithium salt are beneficial to improving the ionic conductivity of the electrolyte membrane. According to the corresponding proportion, an electrolyte membrane with good mechanical strength and high ionic conductivity can be obtained.

[0037] In this embodiment, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0038] The above-mentioned polysiloxane diacrylate is a functional polymer, and the specific groups in its molecular structure can interact with lithium ions, thereby promoting the transmission of lithium ions in the self-healing polymer electrolyte, and can reduce the glass transition temperature of the self-healing polymer electrolyte, so that the self-healing polymer electrolyte can still maintain good flexibility and processability at lower temperatures.

[0039] Preferably, the raw materials for synthesizing the polysiloxane diacrylate include polydimethylsiloxane, isocyanoethyl methacrylate and an organic solvent, and the polydimethylsiloxane may be aminopropyl-terminated polydimethylsiloxane.

[0040] Specifically, polysiloxane elastomers themselves have good self-healing properties, thanks to the dynamic cross-linking network in their molecular structure. By introducing components such as aminopropyl-terminated polydimethylsiloxane, the dynamic cross-linking network can be further regulated and optimized, thereby giving the self-healing polymer electrolyte a stronger self-healing ability. When cracks or damage appear in the self-healing polymer electrolyte during use, this self-healing property can quickly restore its integrity and function and extend its service life; the addition of methacrylate isocyanate and organic solvents can enable the material to maintain high strength and self-healing properties while also having better plasticity and easy processing characteristics.

[0041] It should be noted that the polydimethylsiloxane has a relatively low glass transition temperature, which is beneficial to improving the ionic conductivity at room temperature.

[0042] The preparation method of the polysiloxane diacrylate comprises the following steps:

[0043] In a nitrogen atmosphere, aminopropyl-terminated polydimethylsiloxane, isocyanoethyl methacrylate and an organic solvent are mixed and reacted to obtain polysiloxane diacrylate.

[0044] In this embodiment, there is no special limitation on the mixing of aminopropyl-terminated polydimethylsiloxane, isocyanoethyl methacrylate and organic solvent. The mixing may be carried out by a process well known to those skilled in the art and ensuring that aminopropyl-terminated polydimethylsiloxane and isocyanoethyl methacrylate can be fully dissolved in the organic solvent.

[0045] In the present invention, the reaction temperature may range from 15 to 60° C., more preferably from 20 to 50° C.; the reaction time may range from 15 to 30 h, more preferably from 20 to 25 h.

[0046] Furthermore, the temperature range of the above reaction is 20-40°C.

[0047] In the present invention, the reaction is preferably carried out under stirring conditions. The present invention does not have any particular limitation on the stirring conditions, and conditions familiar to those skilled in the art may be used.

[0048] Optionally, the mass ratio of polydimethylsiloxane, isocyanoethyl methacrylate and organic solvent is in the range of (8-20):(3-10):(40-80) to ensure that the molar ratio of polydimethylsiloxane and isocyanoethyl methacrylate satisfies 2:1, which is conducive to the reaction between polydimethylsiloxane and isocyanoethyl methacrylate.

[0049] The polysiloxane diacrylate comprises, by weight, 2 to 5 parts of polydimethylsiloxane, 4 to 13 parts of isocyanoethyl methacrylate, and 10 to 20 parts of an organic solvent.

[0050] In an optional embodiment, the polydimethylsiloxane is aminopropyl-terminated polydimethylsiloxane, and its molecular weight ranges from 800 to 10000 g / mol.

[0051] Furthermore, the aminopropyl-terminated polydimethylsiloxane may have a concentration of 1000 to 2500 g / mol.

[0052] In this embodiment, the organic solvent includes one or more of benzene, dichloromethane, methanol, ethanol, acetone, acetonitrile and N,N-dimethylformamide; when the above-mentioned organic solvent is two or more of the above-mentioned specific selections, this embodiment has no special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0053] The above-mentioned disulfide diacrylate is used to contain dynamic disulfide bonds and hydrogen bonds, which can enable the self-healing polymer electrolyte to achieve self-healing at room temperature. Specifically, a dynamic disulfide bond (-SS-) is introduced into the self-healing polymer electrolyte. The disulfide bond has a unique dynamic rearrangement characteristic and can break and recombine under certain conditions, thereby giving the self-healing polymer electrolyte the ability to self-heal; at the same time, hydrogen bonds are introduced. Hydrogen bonds, as a strong intermolecular force, can enhance the interaction between polymer chain segments and improve the mechanical strength and stability of the electrolyte membrane. In the self-healing process, hydrogen bonds also play an important role. They can assist the breaking and rearrangement of dynamic disulfide bonds and promote the healing of damaged areas. Disulfide diacrylate provides the self-healing network gel polymer electrolyte with the ability to achieve self-healing at room temperature by introducing dynamic disulfide bonds and hydrogen bonds.

[0054] The disulfide diacrylate includes disulfide dimethacrylate and / or bis(4-vinylphenyl) disulfide. Preferably, the disulfide diacrylate is disulfide dimethacrylate.

[0055] The above-mentioned disulfide dimethacrylate is composed of disulfide, isocyanoethyl methacrylate and an organic solvent. The preparation method of the disulfide dimethacrylate comprises the following steps:

[0056] In a nitrogen atmosphere, disulfide, isocyanoethyl methacrylate and an organic solvent are mixed and reacted to obtain disulfide dimethacrylate.

[0057] The nitrogen atmosphere was achieved by bubbling with nitrogen.

[0058] The above-mentioned disulfide includes one or more of 4,4-diaminodiphenyl disulfide and bis(2-diaminoethyl) disulfide; when the disulfide is two or more of the above-mentioned specific selections, this embodiment has no special restrictions on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. In this embodiment, the organic solvent includes one or more of benzene, methanol, ethanol, acetone, dichloromethane, acetonitrile and N,N-dimethylformamide; when the organic solvent is two or more of the above-mentioned specific selections, the present invention has no special restrictions on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.

[0059] The mass ratio of the above disulfide, methacrylate isocyanoethyl ester and organic solvent can be (2-9): (6-12): (8-15). The introduction of disulfide as a chain extender can significantly improve the mechanical strength of the polymer. Within the above ratio range, the synergistic effect of disulfide, methacrylate isocyanoethyl ester and organic solvent enables the self-healing polymer electrolyte to achieve optimal mechanical properties, thereby enhancing the durability and safety of the battery, and can also optimize the self-healing ability of the electrolyte, extend the service life of the battery, and help to optimize the ion conductivity in the electrolyte.

[0060] The above-mentioned disulfide dimethacrylate comprises, by weight, 0.5 to 2.25 parts of disulfide, 1.5 to 3 parts of isocyanoethyl methacrylate and 2 to 3.75 parts of an organic solvent.

[0061] The present invention has no special limitation on the mixing, and the mixing may be carried out by a process well known to those skilled in the art and ensure that the disulfide and isocyanoethyl methacrylate can be fully dissolved in the organic solvent.

[0062] In this embodiment, the reaction temperature of the disulfide, methacrylate isocyanoethyl ester and organic solvent is in the range of 20 to 80° C., further 30 to 60° C., and the reaction time can be in the range of 10 to 30 hours, further 15 to 25 hours. In this embodiment, the reaction is carried out under stirring conditions, and there is no particular limitation on the stirring conditions in this embodiment, and conditions familiar to those skilled in the art can be used.

[0063] The reaction temperature of the disulfide, isocyanoethyl methacrylate and the organic solvent is further in the range of 40 to 50°C.

[0064] The crosslinking agent generates a self-healing crosslinked network polymer through a thiol-ene click reaction between the carbon-carbon double bonds of disulfide diacrylate and polysiloxane diacrylate and the thiol group of the crosslinking agent, thereby providing the self-healing polymer electrolyte with excellent mechanical properties and self-healing ability.

[0065] Specifically, the cross-linking agent produces chemical bonds, connecting linear molecules to each other to form a network structure. This network structure can significantly improve the strength and elasticity of polymer materials. In the self-healing polymer electrolyte, by introducing a cross-linking agent, stable cross-linking points can be formed between the self-healing polymer electrolyte molecules, thereby enhancing the mechanical strength and toughness of the self-healing polymer electrolyte. When the self-healing polymer electrolyte is damaged, this cross-linking structure can maintain the integrity of the self-healing polymer electrolyte and prevent the damage from further spreading. At the same time, due to the presence of the cross-linking agent, the self-healing mechanism in the self-healing polymer electrolyte is activated, and the damaged part is repaired through a specific chemical reaction, thereby restoring the original performance of the self-healing polymer electrolyte.

[0066] The cross-linking agent includes one or more of tetrakis(3-mercaptopropionic acid)pentaerythritol ester, hexa(3-mercaptopropionic acid)dipentaerythritol ester and octa(3-mercaptopropyl)-POSS; when the cross-linking agent is two or more of the above specific selections, this embodiment does not have any special restrictions on the ratio of the above specific substances, and they can be mixed in any ratio.

[0067] The raw materials for synthesizing octa(3-mercaptopropyl)-POSS include (3-mercaptopropyl)trimethoxysilane, concentrated hydrochloric acid and an organic solvent.

[0068] The preparation method of the above-mentioned eight (3-mercaptopropyl)-POSS comprises the following steps:

[0069] (3-Mercaptopropyl)trimethoxysilane and concentrated hydrochloric acid are added to an organic solvent, heated and stirred to react, and a white precipitate is produced. Afterwards, the prepared crude product is washed three times with an organic solvent, and then the resulting viscous solution is dissolved in an organic solvent, and then washed three times with brine, and finally dried and concentrated to obtain a white viscous liquid octa(3-mercaptopropyl)-POSS (POSS-SH).

[0070] In this embodiment, the organic solvent includes one or more of dichloromethane, methanol, benzene, ethanol, acetone, acetonitrile and N,N-dimethylformamide; when the organic solvent is two or more of the above specific selections, the present invention has no special limitation on the ratio of the above specific substances, and they can be mixed in any ratio.

[0071] In this embodiment, the mass ratio of the above-mentioned (3-mercaptopropyl)trimethoxysilane, concentrated hydrochloric acid and organic solvent is in the range of (1-5): (2-8): (30-70). The use of the above-mentioned ratio range helps to achieve the self-healing performance of the self-healing polymer electrolyte and optimize its mechanical strength and ionic conductivity.

[0072] The crosslinking agent comprises, by weight, 0.25 to 1.25 parts of (3-mercaptopropyl)trimethoxysilane, 0.5 to 4 parts of concentrated hydrochloric acid and 7.5 to 17.5 parts of an organic solvent.

[0073] The present invention has no special limitation on mixing, and the mixing may be carried out by a process well known to those skilled in the art and ensuring that (3-mercaptopropyl)trimethoxysilane and concentrated hydrochloric acid can be fully dissolved in the organic solvent.

[0074] In this embodiment, the reaction temperature range of (3-mercaptopropyl)trimethoxysilane, concentrated hydrochloric acid and organic solvent can be 50-200°C. Optionally, the reaction temperature range of (3-mercaptopropyl)trimethoxysilane, concentrated hydrochloric acid and organic solvent is 70-100°C; the reaction time is preferably 15-40h, more preferably 20-30h.

[0075] Furthermore, the reaction temperature of (3-mercaptopropyl)trimethoxysilane, concentrated hydrochloric acid and organic solvent may be in the range of 75 to 95°C.

[0076] In the present invention, the reaction is preferably carried out under stirring conditions. The present invention does not have any particular limitation on the stirring conditions, and conditions familiar to those skilled in the art may be used.

[0077] The plasticizer can accelerate the transmission of lithium ions, increase the conductivity of the self-healing polymer electrolyte at room temperature, improve the interface compatibility, and reduce the interface impedance, thereby improving the cycle performance and rate performance of the polymer lithium battery.

[0078] Specifically, the introduction of plasticizers can reduce the crystallinity of polymers, increase the amorphous region of polymers, and make the conduction path of lithium ions smoother. At the same time, plasticizers can also promote the movement of polymer segments, making it easier for lithium ions to migrate in polymers, thereby increasing the transmission speed of lithium ions. At the same time, they can also increase the number of free ions in self-healing polymer electrolytes and improve the mobility of ions, thereby improving the conductivity of self-healing polymer electrolytes at room temperature. In addition, plasticizers can also improve the interface contact between self-healing polymer electrolytes and electrode materials. It can form a more uniform interface layer between the self-healing polymer electrolyte and the electrode, reducing the resistance and impedance at the interface, thereby improving the performance and cycle stability of polymer lithium batteries.

[0079] The plasticizer includes one or more of succinonitrile, sebaconitrile, N,N-dimethyltrifluoroacetamide and N-methylacetamide.

[0080] The above-mentioned lithium salt is used to reduce the glass transition temperature of the polymer electrolyte and provide lithium ions. The lithium salt includes LiPF 6 、LiClO 4 , LiTFSI, LiFSI, LiBOB, LiNO 3 and one or more of LiDFOB; when the lithium salt is two or more of the above specific selections, the present invention has no special limitation on the ratio of the above specific substances, and they can be mixed in any ratio.

[0081] The photoinitiator includes one or more of 1-hydroxycyclohexyl phenyl ketone, 4-methyl benzophenone and 2,2-dimethoxy-2-phenylacetophenone; when the photoinitiator is two or more of the above specific selections, the present invention has no special restrictions on the ratio of the above specific substances, and they can be mixed in any ratio. Through the initiation of 2,2-dimethoxy-2-phenylacetophenone, the thiol and the olefin undergo a click reaction.

[0082] Compared with the prior art, the self-healing polymer electrolyte provided in this embodiment achieves at least the following beneficial effects:

[0083] The self-healing polymer electrolyte provided in this embodiment is composed of the following raw materials, measured by mass, 50-100 parts of polysiloxane diacrylate, 1-10 parts of disulfide diacrylate, 10-40 parts of cross-linking agent, 60-120 parts of plasticizer, 60-120 parts of lithium salt and 1-10 parts of photoinitiator. The above scheme is adopted to utilize the thiol-ene click reaction between the carbon-carbon double bonds in polysiloxane diacrylate and disulfide diacrylate and the thiol group of the cross-linking agent, thereby giving the self-healing polymer electrolyte a dynamic disulfide bond and hydrogen bond network structure. The dynamic disulfide bond and hydrogen bond can enable the electrolyte membrane to achieve self-healing at room temperature without external stimulation, thereby improving the service life and safety of the polymer lithium battery. According to the description of Example 4, the ionic conductivity of the self-healing polymer electrolyte of the present invention reaches 4.75×10 -4 S cm -1 ; The polymer lithium battery (such as lithium iron phosphate battery) assembled using the self-healing polymer electrolyte as the electrolyte has a discharge capacity of 150mAh g after 100 cycles at a rate of 0.5C. -1 .

[0084] Optionally, the following raw materials are used for preparation, in parts by mass: 55-90 parts of polysiloxane diacrylate, 2-8 parts of disulfide diacrylate, 10-30 parts of crosslinking agent, 70-100 parts of plasticizer, 70-100 parts of lithium salt and 1-8 parts of photoinitiator. With the above scheme, the self-healing polymer electrolyte not only has good toughness to resist external stress, but also has good ionic conductivity to ensure the efficient operation of polymer lithium battery.

[0085] Furthermore, the self-healing polymer electrolyte is composed of the following raw materials, by weight: 60-70 parts of polysiloxane diacrylate, 2-5 parts of disulfide diacrylate, 12-20 parts of crosslinking agent, 80-90 parts of plasticizer, 80-90 parts of lithium salt and 1.5-4 parts of photoinitiator. With the above scheme, the self-healing polymer electrolyte not only has good toughness to resist external stress, but also has higher ionic conductivity to ensure the efficient operation of the polymer lithium battery.

[0086] See also Figure 1 As shown, Figure 1 : is a flow chart of a method for preparing a self-healing polymer electrolyte provided by the present invention; this embodiment provides a method for preparing a self-healing polymer electrolyte, comprising the following steps:

[0087] Step 100, firstly heating and stirring the lithium salt and the plasticizer, then mixing the polysiloxane diacrylate, the disulfide diacrylate and the crosslinking agent, and finally mixing with the photoinitiator to obtain a precursor solution;

[0088] Step 102: UV-curing the precursor solution to obtain a self-healing polymer electrolyte.

[0089] Specifically, in the above step 100, in a glove box, the lithium salt and the plasticizer are first heated and stirred to form a eutectic solvent, and then polysiloxane diacrylate, disulfide diacrylate and a crosslinking agent are added and mixed; finally, the precursor solution is obtained by mixing with a photoinitiator;

[0090] In the above step 102, the precursor solution is cured by ultraviolet (UV) to obtain a method for preparing a self-healing polymer electrolyte. The above ultraviolet (UV) curing can promote the occurrence of a thiol-ene click reaction.

[0091] The inventors have found that if the temperature of heating and stirring the lithium salt and the plasticizer is too low, the plasticizer and the lithium salt cannot be completely dissolved, and if the temperature of heating and stirring the lithium salt and the plasticizer is too high, the lithium salt may be decomposed and the plasticizer may be volatilized, causing the solvent to deteriorate. Therefore, in this embodiment, the heating time range of the lithium salt and the plasticizer during heating and stirring can be 0.5-2h, and the temperature range can be 40-100°C, which can not only achieve complete dissolution of the plasticizer and the lithium salt, but also avoid decomposition of the lithium salt and volatilization of the plasticizer, thereby preventing the solvent from deteriorating.

[0092] In this embodiment, the lithium salt, plasticizer, polysiloxane diacrylate, disulfide diacrylate and crosslinking agent are mixed under stirring; the stirring time range can be 10 to 40 hours. This embodiment does not have any special limitation on the stirring speed. The speed familiar to those skilled in the art is adopted and the lithium salt, plasticizer, polysiloxane diacrylate, disulfide diacrylate and crosslinking agent are fully dissolved in the organic solvent under the above stirring time.

[0093] In this embodiment, the reaction is carried out with the photoinitiator under stirring; the stirring time range can be 2 to 5 hours. This embodiment does not have any special limitation on the stirring speed. A speed familiar to those skilled in the art can be used to ensure that the photoinitiator is fully dissolved in the organic solvent under the above stirring time.

[0094] After the precursor solution is obtained in the above step 102, in this embodiment, the precursor solution is UV-cured under an argon atmosphere to obtain a self-healing gel polymer electrolyte.

[0095] It should be noted that lithium salts and plasticizers are usually solid at room temperature, which is not conducive to dissolution and dispersion.

[0096] In this embodiment, lithium salt and plasticizer are heated and stirred at a certain ratio to form a deep eutectic solvent, which is liquid at room temperature. Then, polysiloxane diacrylate, disulfide diacrylate and crosslinking agent are added, so that each component can be evenly dispersed, which is conducive to forming a uniform phase. Finally, a photoinitiator is added to prevent these components from reacting during the stirring process.

[0097] Compared with the prior art, the method for preparing the self-healing polymer electrolyte provided in this embodiment achieves at least the following beneficial effects:

[0098] In the preparation method of the self-healing polymer electrolyte provided in this embodiment, the lithium salt and the plasticizer are first heated and stirred, and then the polysiloxane diacrylate, the disulfide diacrylate and the cross-linking agent are mixed, and finally mixed with a photoinitiator to obtain a precursor solution; the precursor solution is ultraviolet-cured to obtain a self-healing polymer electrolyte. According to this scheme, the lithium salt and the plasticizer are first heated and stirred to form a eutectic solvent. The eutectic solvent has excellent ion transport properties, is cheap, environmentally friendly and electrochemically stable, which not only accelerates the transmission of lithium ions, but also has a stable electrochemical window. The in-situ preparation strategy not only improves the ionic conductivity of the self-healing polymer electrolyte at room temperature, but also improves the interface compatibility, reduces the interface impedance, and improves the cycle performance and rate performance of the polymer lithium battery. The preparation process has the advantages of simple operation, mild conditions and low cost.

[0099] In order to prevent the unnecessary reaction of organic components caused by too long stirring time, the photoinitiator is added at the last stage of the stirring process.

[0100] In this embodiment, the UV curing wavelength range may be 100 to 380 nm, further 300 to 380 nm; the irradiation intensity range may be 10 to 200 mW / cm -2 , further 100-200 mW cm -2 ; The time range can be 0.5 to 20 minutes, further 0.5 to 10 minutes.

[0101] The above self-repairing polymer electrolyte can be used in polymer lithium batteries, such as the application of self-repairing three-dimensional network cross-linked network gel polymer electrolyte in polymer lithium batteries.

[0102] Based on the same inventive concept, this embodiment provides a polymer lithium battery, including a positive electrode, a negative electrode, and an electrolyte between the positive electrode and the negative electrode, wherein the electrolyte is the above-mentioned self-healing polymer electrolyte.

[0103] Specifically, the polymer lithium battery may be a gel polymer lithium battery. This embodiment has no special requirements for the positive electrode and the negative electrode, and the positive electrode and the negative electrode for lithium electrodes well known to those skilled in the art may be used.

[0104] In this embodiment, the positive electrode includes a positive electrode active material, a current collector, a conductive agent and a binder, wherein the mass ratio of the positive electrode active material, the conductive agent and the binder can be 8:1:1. The mass ratio of the positive electrode active material, the conductive agent and the binder can be adjusted according to actual conditions, and this embodiment does not make specific limitations on this.

[0105] The positive electrode active material includes one or more of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate and lithium iron manganese phosphate; the current collector may be copper foil or aluminum foil; the conductive agent includes one or more of ketjen black, acetylene black and carbon nanotubes; the binder includes one or more of polyurethane, tetrafluoroethylene and polyvinylidene fluoride. In this embodiment, the negative electrode may be metallic lithium. This embodiment has no special requirements for the assembly method of the gel polymer lithium battery, and an assembly method familiar to those skilled in the art may be used.

[0106] The polymer lithium battery provided by the present invention uses a self-repairing gel polymer electrolyte as an electrolyte and has excellent rate performance.

[0107] The self-healing gel polymer electrolyte prepared in the above Example 1 was used as an electrolyte to assemble a button cell.

[0108] The positive electrode active material may be lithium iron phosphate, the current collector may be aluminum foil, the conductive agent may be acetylene black, the binder may be polytetrafluoroethylene; and the negative electrode may be metallic lithium.

[0109] The mass of polysiloxane diacrylate is M1, the mass of disulfide diacrylate is M2, the mass of crosslinker is M3, the mass of plasticizer is M4, the mass of lithium salt is M5, and the mass of photoinitiator is M6, wherein (M1: M2: M3: M4: M5: M6) × 100% = 67: 2.8: 14: 84: 84: 2. In the following embodiments, the mass fractions of polysiloxane diacrylate, disulfide diacrylate, crosslinker, plasticizer, lithium salt and photoinitiator are all set to 0.01 g per portion.

[0110] Example 1

[0111] The self-healing polymer electrolyte in this embodiment is composed of the following raw materials, by weight: 50 parts of polysiloxane diacrylate, 1 part of disulfide diacrylate, 10 parts of a cross-linking agent, 60 parts of a plasticizer, 60 parts of a lithium salt and 1 part of a photoinitiator.

[0112] The preparation method of the self-healing polymer electrolyte is as follows:

[0113] (1) Dissolve 2.5 g of 4,4-diaminodiphenyl disulfide in acetone, bubble for 30 min under nitrogen, add 2.9 mL of methyl methacrylate isocyanoethyl ester, and stir at room temperature for 20 h to obtain diphenyl disulfide bis(2-methylacrylamide);

[0114] (2) First, 2.9 mL of ethyl isocyanate methacrylate was added to 40 mL of anhydrous acetone, and the mixture was bubbled under nitrogen for 15 min. Then, 10 g of aminopropyl-terminated polydimethylsiloxane was added, and nitrogen was continued to be bubbled for 15 min. The mixture was stirred at room temperature for 24 h, and then rotary evaporated to obtain an oily liquid polysiloxane diacrylate;

[0115] (3) 15 mL (3-mercaptopropyl) trimethoxysilane and 30 mL concentrated hydrochloric acid were added to 300 mL methanol, heated and stirred at 90° C. for 24 h to produce a white precipitate. Afterwards, the prepared crude product was washed three times with ice methanol, and then the obtained viscous solution was dissolved in dichloromethane, and then washed three times with brine, and finally dried and concentrated to obtain a white viscous liquid POSS-SH;

[0116] (4) In a glove box, 60 parts of lithium salt and 60 parts of N-methylacetamide (NMAc) were added to a 5 mL vial and stirred at 50 °C for 3 h to obtain a eutectic solvent. Then, 50 parts of polysiloxane diacrylate, 1 part of diphenyl disulfide bis(2-methylacrylamide), 10 parts of POSS-SH and 16.8 parts of eutectic solvent were added to a 10 mL vial, stirred evenly and 1 part of photoinitiator was added; finally, stirred at room temperature for 24 h, the stirred solution was evenly coated on a lithium sheet with a diameter of 16 mm, and irradiated with UV (365 nm) light for 5 min in an argon atmosphere to obtain a self-healing polymer electrolyte with a thickness of 100 μm. In addition, the electrolyte membrane prepared by irradiating light for 5 min between two glass plates was subjected to other electrochemical tests.

[0117] The lithium salt includes LiTSFI:LiNO3:LiDFOB, wherein the mass ratio of LiTSFI:LiNO3:LiDFOB may be 90wt%:5wt%:5wt%.

[0118] Example 2

[0119] The self-healing polymer electrolyte in this embodiment is composed of the following raw materials, by weight: 100 parts of polysiloxane diacrylate, 10 parts of disulfide diacrylate, 40 parts of a cross-linking agent, 120 parts of a plasticizer, 120 parts of a lithium salt and 10 parts of a photoinitiator.

[0120] The preparation method of the self-healing polymer electrolyte is as follows:

[0121] (1) Dissolve 2.5 g of 4,4-diaminodiphenyl disulfide in acetone, bubble for 30 min under nitrogen, add 2.9 mL of methyl methacrylate isocyanoethyl ester, and stir at room temperature for 20 h to obtain diphenyl disulfide bis(2-methylacrylamide);

[0122] (2) First, 2.9 mL of ethyl isocyanate methacrylate was added to 80 mL of anhydrous acetone, and the mixture was bubbled under nitrogen for 15 min. Then, 10 g of aminopropyl-terminated polydimethylsiloxane was added, and nitrogen was continued to be bubbled for 15 min. The mixture was stirred at room temperature for 24 h, and then rotary evaporated to obtain an oily liquid polysiloxane diacrylate;

[0123] (3) 15 mL (3-mercaptopropyl) trimethoxysilane and 30 mL concentrated hydrochloric acid were added to 500 mL methanol, heated and stirred at 90° C. for 24 h to produce a white precipitate. Afterwards, the prepared crude product was washed three times with ice methanol, and then the obtained viscous solution was dissolved in dichloromethane, and then washed three times with brine, and finally dried and concentrated to obtain a white viscous liquid POSS-SH;

[0124] (4) In a glove box, 120 parts of lithium salt and 120 parts of N-methylacetamide (NMAc) were added to a 5 mL vial and stirred at 50 °C for 3 h to obtain a eutectic solvent. Then, 100 parts of polysiloxane diacrylate, 10 parts of diphenyl disulfide bis(2-methylacrylamide), 40 parts of POSS-SH and 16.8 parts of eutectic solvent were added to a 10 mL vial, stirred evenly and then 10 parts of photoinitiator were added; finally, stirred at room temperature for 24 h, the stirred solution was evenly coated on a lithium sheet with a diameter of 16 mm, and irradiated with UV (365 nm) light for 5 min in an argon atmosphere to obtain a self-healing polymer electrolyte with a thickness of 100 μm. In addition, the electrolyte membrane prepared by light irradiation for 5 min between two glass plates was subjected to other electrochemical tests.

[0125] The components and mass ratio of the lithium salt in Example 2 are the same as those in Example 1.

[0126] Example 3

[0127] The self-healing polymer electrolyte in this embodiment is composed of the following raw materials, by weight: 75 parts of polysiloxane diacrylate, 5.5 parts of disulfide diacrylate, 25 parts of a crosslinking agent, 90 parts of a plasticizer, 90 parts of a lithium salt and 5.5 parts of a photoinitiator.

[0128] The preparation method of the self-healing polymer electrolyte is as follows:

[0129] (1) Dissolve 2.5 g of 4,4-diaminodiphenyl disulfide in acetone, bubble for 30 min under nitrogen, add 2.9 mL of methyl methacrylate isocyanoethyl ester, and stir at room temperature for 20 h to obtain diphenyl disulfide bis(2-methylacrylamide);

[0130] (2) First, 2.9 mL of ethyl isocyanate methacrylate was added to 50 mL of anhydrous acetone, and the mixture was bubbled under nitrogen for 15 min. Then, 10 g of aminopropyl-terminated polydimethylsiloxane was added, and nitrogen was continued to be bubbled for 15 min. The mixture was stirred at room temperature for 24 h, and then rotary evaporated to obtain an oily liquid polysiloxane diacrylate;

[0131] (3) 15 mL (3-mercaptopropyl) trimethoxysilane and 30 mL concentrated hydrochloric acid were added to 500 mL methanol, heated and stirred at 90° C. for 24 h to produce a white precipitate. Afterwards, the prepared crude product was washed three times with ice methanol, and then the obtained viscous solution was dissolved in dichloromethane, and then washed three times with brine, and finally dried and concentrated to obtain a white viscous liquid POSS-SH;

[0132] (4) In a glove box, 90 parts of lithium salt and 90 parts of N-methylacetamide (NMAc) were added to a 5 mL vial and stirred at 50 °C for 3 h to obtain a eutectic solvent. Then, 75 parts of polysiloxane diacrylate, 5.5 parts of diphenyl disulfide bis(2-methylacrylamide), 25 parts of POSS-SH and 16.8 parts of eutectic solvent were added to a 10 mL vial, stirred evenly and then 5.5 parts of photoinitiator were added; finally, stirred at room temperature for 24 h, the stirred solution was evenly coated on a lithium sheet with a diameter of 16 mm, and irradiated with UV (365 nm) light for 5 min in an argon atmosphere to obtain a self-healing polymer electrolyte with a thickness of 100 μm. In addition, the electrolyte membrane prepared by irradiating light for 5 min between two glass plates was subjected to other electrochemical tests.

[0133] The components and mass ratio of the lithium salt in Example 3 are the same as those in Example 1.

[0134] Example 4

[0135] 2.5 g of 4,4-diaminodiphenyl disulfide was dissolved in acetone, and 2.9 mL of methyl methacrylate isocyanoethyl ester was added after bubbling under nitrogen for 30 min, and stirred at room temperature for 20 h to obtain diphenyl disulfide bis(2-methylacrylamide);

[0136] First, add 2.9 mL of ethyl isocyanate methacrylate into 50 mL of anhydrous acetone and bubble nitrogen for 15 minutes. Then, add 10 g of aminopropyl-terminated polydimethylsiloxane and continue to bubble nitrogen for 15 minutes. Stir at room temperature for 24 hours and then rotary evaporate to obtain oily liquid polysiloxane diacrylate.

[0137] 15 mL (3-mercaptopropyl) trimethoxysilane and 30 mL concentrated hydrochloric acid were added to 360 mL methanol, heated and stirred at 90°C for 24 h to produce a white precipitate. After that, the prepared crude product was washed three times with ice methanol, and then the obtained viscous solution was dissolved in dichloromethane, then washed three times with brine, and finally dried and concentrated to obtain a white viscous liquid POSS-SH.

[0138] In a glove box, 84 parts of lithium salt and 84 parts of NMAc were added to a 5 mL vial, and stirred at 50 ° C for 3 hours to obtain a eutectic solvent. Then 67 parts of polysiloxane diacrylate, 2.8 parts of diphenyl disulfide bis (2-methyl acrylamide) and 14 parts of POSS-SH and 168 parts (such as 1.68g) of eutectic solvent were added to a 10 mL vial, and 2.8 parts of photoinitiator were added after stirring evenly. Finally, it was stirred at room temperature for 24 hours, and the stirred solution was evenly coated on a lithium sheet with a diameter of 16 mm, and irradiated with UV (365nm) light for 5 minutes under an argon atmosphere to obtain an in-situ self-healing polymer electrolyte with a thickness of 100 μm. In addition, the electrolyte membrane prepared by light irradiation for 5 minutes between two glass plates was subjected to other electrochemical tests.

[0139] Reference Figure 2-Figure 4 As shown, Figure 2 The infrared spectra of octa(3-mercaptopropyl)-POSS (POSS-SH), diphenyl disulfide bis(2-methylacrylamide) and polysiloxane diacrylate in the self-healing gel polymer electrolyte obtained in Example 4 are shown in FIG. -1 Absorption band V S-H Peak and 1620cm -1 Absorption band V C＝C disappears, indicating that polysiloxane diacrylate, diphenyl disulfide bis(2-methylacrylamide) and POSS-SH undergo a thiol-ene click reaction to form a network polymer. Figure 2 MediumWavenumber(cm -1 ) is the unit of wave number, which is a unit of frequency in spectroscopy of atoms, molecules, and nuclei; Figure 3 The ionic conductivity of the self-healing polymer electrolyte prepared in Example 4 varies with temperature. The membrane thickness of the self-healing polymer electrolyte is about 100 μm, and the original ionic conductivity is 4.75×10-4 S / cm at 28°C. -1 ; Figure 4The self-healing process of the self-healing gel polymer electrolyte membrane prepared in Example 4 at room temperature, wherein the membrane thickness of the self-healing polymer electrolyte is about 300 μm. The membrane is cut into two pieces with a scalpel, and the two separated parts are brought into contact. After standing for 6 hours, the gap between the cut membranes disappears, indicating that it has good self-healing properties, and its self-healing ability is attributed to the hydrogen bonds and disulfide bonds in the polymer.

[0140] Figure 5 Cycling test diagram of button cells assembled with the self-healing polymer electrolyte prepared in Example 4 at room temperature at a rate of 0.5C; at a rate of 0.5C, the first cycle discharge capacity of the original self-healing polymer electrolyte battery is 144 mAh g -1 , and maintained 149 mAh g after 100 cycles -1 , the average Coulombic efficiency is 99.8%; Figure 6 The Li / / Li symmetric button cell assembled with the self-healing polymer electrolyte prepared in Example 4 was tested at 0.1 mA cm -2 Cyclic stability curves at current density of 0.1 mA cm using a 16 mm diameter lithium foil. -2 At a current density of 1.5 volts, the symmetrical battery has a one-hour Li+ plating / stripping cycle, with negative and positive voltages representing Li+ plating and Li+ stripping, respectively. After 100 hours of cycling, the positive voltage remains constant at 0.075 V, indicating good interfacial compatibility between the self-healing polymer electrolyte and the negative electrode (such as metallic lithium).

[0141] The components and mass ratio of the lithium salt in Example 4 are the same as those in Example 1.

[0142] Example 5

[0143] The difference between this embodiment 5 and embodiment 3 is that:

[0144] The self-healing polymer electrolyte in this Example 5 is composed of the following raw materials, by weight: 60 parts of polysiloxane diacrylate, 5 parts of disulfide diacrylate, 15 parts of a cross-linking agent, 70 parts of a plasticizer, 70 parts of a lithium salt and 4 parts of a photoinitiator.

[0145] Example 6

[0146] The difference between this embodiment 6 and embodiment 3 is that:

[0147] The self-healing polymer electrolyte in this Example 6 is composed of the following raw materials, by weight: 90 parts of polysiloxane diacrylate, 5 parts of disulfide diacrylate, 30 parts of a crosslinking agent, 85 parts of a plasticizer, 95 parts of a lithium salt and 2 parts of a photoinitiator.

[0148] Example 7

[0149] The difference between this embodiment 7 and embodiment 3 is that:

[0150] The self-healing polymer electrolyte in this Example 7 is composed of the following raw materials, by weight: 70 parts of polysiloxane diacrylate, 4 parts of disulfide diacrylate, 20 parts of a crosslinking agent, 65 parts of a plasticizer, 70 parts of a lithium salt and 6 parts of a photoinitiator.

[0151] Example 8

[0152] The difference between this embodiment 8 and embodiment 1 is that:

[0153] The self-healing polymer electrolyte in this Example 8 is composed of the following raw materials, by weight: 95 parts of polysiloxane diacrylate, 9 parts of disulfide diacrylate, 35 parts of a cross-linking agent, 60 parts of a plasticizer, 60 parts of a lithium salt and 4 parts of a photoinitiator.

[0154] Example 9

[0155] The difference between this embodiment 9 and embodiment 1 is that:

[0156] The self-healing polymer electrolyte in this Example 9 is composed of the following raw materials, by weight: 65 parts of polysiloxane diacrylate, 2 parts of disulfide diacrylate, 20 parts of a crosslinking agent, 120 parts of a plasticizer, 120 parts of a lithium salt and 6 parts of a photoinitiator.

[0157] Example 10

[0158] The difference between this embodiment 10 and embodiment 1 is that:

[0159] The self-healing polymer electrolyte in this embodiment 10 is composed of the following raw materials, by weight: 100 parts of polysiloxane diacrylate, 1 part of disulfide diacrylate, 10 parts of a cross-linking agent, 65 parts of a plasticizer, 80 parts of a lithium salt and 8 parts of a photoinitiator.

[0160] Embodiment 11

[0161] The difference between this embodiment 11 and embodiment 2 is that:

[0162] The self-healing polymer electrolyte in this Example 11 is composed of the following raw materials, in parts by mass, 50 parts of polysiloxane diacrylate, 10 parts of disulfide diacrylate, 10 parts of cross-linking agent, 110 parts of plasticizer, 70 parts of lithium salt and 1 part of photoinitiator.

[0163] The difference between this embodiment 12 and embodiment 3 is that:

[0164] The self-healing polymer electrolyte in this Example 12 is composed of the following raw materials, in parts by mass, 90 parts of polysiloxane diacrylate, 8 parts of disulfide diacrylate, 30 parts of a cross-linking agent, 100 parts of a plasticizer, 100 parts of a lithium salt and 8 parts of a photoinitiator.

[0165] The difference between this embodiment 13 and embodiment 3 is that:

[0166] The self-healing polymer electrolyte in this Example 13 is composed of the following raw materials, by mass, 55 parts of polysiloxane diacrylate, 2 parts of disulfide diacrylate, 10 parts of cross-linking agent, 70 parts of plasticizer, 70 parts of lithium salt and 1 part of photoinitiator.

[0167] The difference between this embodiment 14 and embodiment 3 is that:

[0168] The self-healing polymer electrolyte in this Example 14 is composed of the following raw materials, in parts by mass, 72.5 parts of polysiloxane diacrylate, 5 parts of disulfide diacrylate, 20 parts of cross-linking agent, 85 parts of plasticizer, 85 parts of lithium salt and 4.5 parts of photoinitiator.

[0169] The difference between this embodiment 15 and embodiment 3 is that:

[0170] The self-healing polymer electrolyte in this Example 15 is composed of the following raw materials, in parts by mass, 60 parts of polysiloxane diacrylate, 5 parts of disulfide diacrylate, 12 parts of a cross-linking agent, 90 parts of a plasticizer, 80 parts of a lithium salt and 4 parts of a photoinitiator.

[0171] The difference between this embodiment 16 and embodiment 3 is that:

[0172] The self-healing polymer electrolyte in this Example 16 is composed of the following raw materials, in parts by mass, 70 parts of polysiloxane diacrylate, 2 parts of disulfide diacrylate, 20 parts of cross-linking agent, 80 parts of plasticizer, 90 parts of lithium salt and 1.5 parts of photoinitiator.

[0173] Comparative Example 1

[0174] Dissolve 2.5 g of 4,4-diaminodiphenyl disulfide in acetone, add 2.9 mL of methyl methacrylate isocyanoethyl ester after nitrogen bubbling for 30 min, and stir at room temperature for 20 h to obtain diphenyl disulfide bis(2-methylacrylamide);

[0175] 0.6 g of lithium salt (LiTFSI), 0.08 g of ionic liquid (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl imide salt), 1.25 g of 1000 g / mol polyethylene glycol diacrylate, 0.077 g of diphenyl disulfide bis(2-methylacrylamide), 0.0305 g of pentaerythritol tetrakis(3-mercaptopropionic acid) ester and 0.23 g of 3,6-dioxa-1,8-octanedithiol were dissolved in anhydrous acetonitrile and stirred for 12 h. After stirring evenly, 20 mg of photoinitiator and 10 μL of n-butylamine were added and stirring was continued for 1 h to obtain a uniform precursor solution;

[0176] The homogeneous precursor solution was ultrasonicated for 3 min, and the obtained slurry was scraped onto a 10×20 cm rectangular polytetrafluoroethylene plate, pre-cured in a dryer for 24 h, and then irradiated with ultraviolet light for 1 h (wavelength of 365 nm, light intensity of 150 mW / cm -2 ), and after curing, it was dried in a vacuum oven at 60°C for 4 h, and the film was peeled off to obtain a self-healing network polymer electrolyte.

[0177] Comparative Example 2

[0178] The difference between Comparative Example 2 and Comparative Example 1 is that:

[0179] Dissolve 2.5 g of bis(4-hydroxyphenyl) disulfide in dichloromethane, bubble nitrogen for 30 minutes, heat and stir at 60°C for 30 minutes, add 1 mL of dibutyltin dilaurate and 2.9 mL of methyl methacrylate isocyanoethyl when the temperature drops to 40°C, and stir at 40°C for 20 hours to obtain diphenyl disulfide bis(2-methylacrylate).

[0180] Comparative Example 3

[0181] The difference between Comparative Example 3 and Comparative Example 1 is that:

[0182] 0.31 g of bis(2-hydroxyethyl) disulfide was dissolved in dichloromethane, and nitrogen was bubbled for 30 min, followed by heating and stirring at 60°C for 30 min. When the temperature dropped to 40°C, 0.2 mL of dibutyltin dilaurate and 0.58 mL of methyl methacrylate isocyanoethyl ester were added, and the mixture was stirred at 40°C for 20 h to obtain disulfide bis(2-methylacrylate).

[0183] The polyethylene glycol diacrylate in the above comparative examples 1-3 and the aminopropyl-terminated polydimethylsiloxane in the polysiloxane diacrylate in the present application are two different organic substances. Specifically, the polyethylene glycol diacrylate is an electrolyte based on polyethylene glycol (PEO), which is modified by introducing acrylate groups. The aminopropyl-terminated polydimethylsiloxane in the present embodiment is a siloxane-based electrolyte, which is characterized in that the ends of the polydimethylsiloxane chains are terminated by aminopropyl groups.

[0184] Table 1 below shows the ionic conductivity of the self-healing polymer electrolyte, the first cycle discharge capacity of the polymer lithium battery, the discharge capacity after 100 cycles, and the average Coulombic efficiency at a rate of 0.5C.

[0185] Table 1

[0186]

[0187]

[0188] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A self-healing polymer electrolyte, characterized in that: The preparation method is composed of the following raw materials in parts by mass: 50-100 parts of polysiloxane diacrylate, 1-10 parts of disulfide diacrylate, 10-40 parts of a crosslinking agent, 60-120 parts of a plasticizer, 60-120 parts of a lithium salt and 1-10 parts of a photoinitiator.

2. The self-healing polymer electrolyte according to claim 1, characterized in that: The preparation method is composed of the following raw materials in parts by mass: 55-90 parts of polysiloxane diacrylate, 2-8 parts of disulfide diacrylate, 10-30 parts of crosslinking agent, 70-100 parts of plasticizer, 70-100 parts of lithium salt and 1-8 parts of photoinitiator.

3. The self-healing polymer electrolyte according to claim 1, characterized in that: The raw materials for synthesizing the polysiloxane diacrylate include polydimethylsiloxane, isocyanoethyl methacrylate and an organic solvent.

4. The self-healing polymer electrolyte according to claim 3, characterized in that: The mass ratio of the polydimethylsiloxane, isocyanoethyl methacrylate and the organic solvent is in the range of (8-20):(3-10):(40-80).

5. The self-healing polymer electrolyte according to claim 3, characterized in that: The polydimethylsiloxane is aminopropyl-terminated polydimethylsiloxane, and its molecular weight ranges from 800 to 10000 g / mol.

6. The self-healing polymer electrolyte according to claim 1, characterized in that: The plasticizer includes one or more of succinonitrile, sebaconitrile, N,N-dimethyltrifluoroacetamide, and N-methylacetamide.

7. A method for preparing the self-healing polymer electrolyte according to any one of claims 1 to 6, characterized in that: The following steps are involved: Firstly, the lithium salt and the plasticizer are heated and stirred, then the polysiloxane diacrylate, the disulfide diacrylate and the crosslinking agent are mixed, and finally the photoinitiator is mixed to obtain a precursor solution; The precursor solution is cured by ultraviolet light to obtain a self-healing polymer electrolyte.

8. The method for preparing the self-healing polymer electrolyte according to claim 7, characterized in that: The preparation method of the polysiloxane diacrylate comprises the following steps: In a nitrogen atmosphere, polydimethylsiloxane, isocyanoethyl methacrylate and an organic solvent are mixed to obtain the polysiloxane diacrylate.

9. Use of the self-healing polymer electrolyte according to any one of claims 1 to 6 in a polymer lithium battery.

10. A polymer lithium battery, characterized in that: The positive electrode, the negative electrode and the electrolyte between the positive and negative electrodes, wherein the electrolyte is the self-healing polymer electrolyte according to any one of claims 1 to 6.

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