Functionalized clay-based membrane and polymer composite electrolyte as well as preparation method and application thereof

Abstract

The invention belongs to the field of solid electrolytes, and particularly relates to a functionalized clay-based membrane and polymer composite electrolyte and a preparation method and application thereof.The functionalized clay-based membrane and polymer composite electrolyte is of a sandwich structure and comprises a functionalized clay-based membrane and polymer layers compounded on the two surfaces of the functionalized clay-based membrane, the functionalized clay-based membrane is a material layer formed by stacking functionalized clay, the functionalized clay is a material obtained by intercalating clay with alkali metal ions in advance and then modifying the clay with a modifier; the modifier comprises at least one of a formula A # imgabs 0 # and a formula B # imgabs 1 #. The clay-based membrane-polymer three-layer sandwich composite electrolyte provided by the invention is further matched with the combination of a clay dual modification mechanism, so that the synergism can be accidentally realized, the conductivity and the ion mobility of the composite solid electrolyte are improved, the electrochemical performance of the composite solid electrolyte is improved, and the mechanical performance and the thermal stability of the composite solid electrolyte are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the field of battery materials, and particularly relates to the technical field of solid electrolytes. Background Art

[0002] In recent years, secondary battery technology has achieved great success in the fields of mobile communication and electronics, and has emerged in the fields of electric transportation, military, aerospace, power grid, etc. In solid-state lithium / sodium / potassium metal batteries, solid electrolytes are used to replace organic electrolytes. At the same time, the solid electrolytes have high mechanical strength, which can effectively inhibit the growth of dendrites, thus greatly improving the safety performance of the batteries. Compared with traditional batteries, they have higher theoretical specific capacity and lower standard electrode potential (compared with the standard hydrogen potential), and are expected to break through the technical bottlenecks of traditional batteries.

[0003] Interface stability has an important impact on the electrochemical performance of solid-state batteries. Generally, solid inorganic electrolytes have higher ionic conductivity than polymer electrolytes, but their contact with the electrode interface is completely rigid; while polymer solid electrolytes have low ionic conductivity, but have relatively good flexibility, which can improve their interface performance to a certain extent. However, polymer solid electrolytes are limited by the intrinsic strength of the system and it is difficult to achieve the preparation of ultra-thin films and large-scale production.

[0004] In traditional organic-inorganic composite solid electrolytes, adding trace inorganic fillers to the polymer matrix can break the regularity of polymer chains and improve ionic conductivity by adjusting the composition ratio, but the improvement of the mechanical properties of the electrolyte membrane is not ideal, and it is still difficult to solve the above problems. Clay minerals are widely distributed on the earth and have advantages such as low cost, high mechanical properties, and good flame retardancy. In addition, clay has a large specific surface area and rich functional groups, and can design and construct fast ion transport channels through the synergistic effect of polymers and clay fillers to meet the requirements of high ionic conductivity. Therefore, using clay as the base film is an advanced battery construction strategy to achieve excellent electrochemical performance and maintain long-term cycle stability of the battery.

[0005] The prior art also discloses some technical solutions of clay-based solid electrolytes. For example, the Chinese patent document with the publication number CN113964380A discloses a self-healing polymer electrolyte that can be in-situ thermally polymerized. The polymer electrolyte is prepared by an in-situ thermal polymerization method from lithium bis(trifluoromethanesulfonyl)imide, a polymer containing self-healing chemical bonds, an initiator, a plasticizer, and an inorganic additive; the inorganic additive is vermiculite or garnet-type oxide electrolyte. In addition, the Korean patent document with the publication number KR102583474A1 discloses a polymer-clay nanocomposite electrolyte for secondary batteries and a secondary battery including the same, wherein the polymer-clay nanocomposite electrolyte for secondary batteries includes: a semi-interpenetrating polymer network including a crosslinked polymer and a non-crosslinked polymer; exfoliated clay minerals dispersed in the semi-interpenetrating polymer network; and an electrolyte containing a lithium salt or a sodium salt.

[0006] In summary, the clay-based solid electrolytes in the prior art mainly directly incorporate the clay component into the polymer matrix. The electrolyte of this technology has a large thickness, and the clay component is buried by the polymer, so its electrochemical performance cannot be fully exerted. In addition, the batch quality stability of the existing process needs to be further improved. Summary of the Invention

[0007] Aiming at the problems existing in the existing clay solid electrolytes, the first object of the present invention is to provide a functionalized clay-based film@polymer composite electrolyte, aiming to provide a composite electrolyte with a brand-new physical and chemical structure.

[0008] The second object of the present invention is to provide a preparation method and application of the functionalized clay-based film@polymer composite electrolyte.

[0009] The third object of the present invention is to provide an application including the functionalized clay-based film@polymer composite electrolyte.

[0010] The functionalized clay-based film@polymer composite electrolyte has a sandwich structure, which includes a functionalized clay-based film and polymer layers compounded on its two surfaces (front and back). The functionalized clay-based film is a material layer formed by stacking functionalized clay, wherein the functionalized clay is a material obtained by pre-intercalating clay with alkali metal ions and then modifying and modifying it with a modifier;

[0011] The modifier includes at least one of Formula A and Formula B;

[0012]

[0013] The R 1 is an alkyl group of C 1 ~C 6 ; the R 2is a substituted alkyl group with substituents; the substituents include at least one of amino group, substituted amino group, epoxy group, mercapto group, acryloyloxy group, vinyl group, isocyanate group;

[0014] wherein n is an integer from 2 to 6, and M is H, Na, K or NH 4 ;

[0015] The clay is vermiculite and / or sepiolite.

[0016] The present invention provides a three-layer sandwich composite electrolyte of clay-based membrane-polymer. Further combined with the type of the clay material and the dual modification mechanism, synergism can be unexpectedly achieved, improving the conductivity and ion mobility of the composite solid electrolyte, improving its electrochemical performance, and significantly enhancing its mechanical performance and thermal stability. In addition, this composite electrolyte based on clay as the base membrane can solve the problems of relatively thick electrolyte membrane and unsatisfactory high-rate performance existing in polymer electrolytes, and further reduce the production cost of the electrolyte.

[0017] Preferably, the thickness of the functionalized clay-based membrane is 30 - 60 μm, and further can be 40 - 50 μm.

[0018] Preferably, the functionalized clay in the functionalized clay-based membrane is obtained by alkali metal ion intercalation and subsequent modification of Formula A and Formula B. In the present invention, the clay in the base membrane contains clay modified by the combination of Formula A and Formula B, which can further strengthen the process synergy and contribute to further improving its conductivity and transference number.

[0019] Preferably, the functionalized clay-based membrane includes a first base membrane and a second base membrane composite on the surface; wherein, the functionalized clay in the first base membrane is obtained by alkali metal ion intercalation and modification of Formula A, and the functionalized clay in the second base membrane is obtained by alkali metal ion intercalation and modification of Formula B. In the present invention, the composite base membrane formed by using the special modified clay can further strengthen the process synergy and contribute to further improving its conductivity and transference number.

[0020] In the present invention, the polymer in the polymer layer can be a polymer known in the field of solid electrolytes, for example, it can be a polyethylene oxide-based polymer.

[0021] In the present invention, the polymer layer can be obtained by in-situ polymerization of polymerization monomers on the functionalized clay-based membrane.

[0022] There is no particular requirement for the type of the polymer. For example, it can be a polyethylene oxide-based polymer.

[0023] In the present invention, the thickness of the functionalized clay-based membrane@polymer composite electrolyte can be 90 - 120 μm.

[0024] The present invention also provides a method for preparing the functionalized clay-based film @ polymer composite electrolyte, and the steps include:

[0025] Step 1: Preparation of the functionalized clay-based film

[0026] Step 1A: First modification

[0027] Place the clay in a first modification solution containing alkali metal ions for intercalation modification to obtain first-modified clay;

[0028] Step 1B: Second modification

[0029] Place the first-modified clay in a second modification solution containing a modifier for second-stage modification to obtain the functionalized clay;

[0030] Step 1C: Preparation of the base film

[0031] Form the functionalized clay into a functionalized clay-based film;

[0032] Step 2: Preparation of the composite electrolyte

[0033] Compound a polymer on the functionalized clay-based film to obtain the functionalized clay-based film @ polymer composite electrolyte.

[0034] Aiming at problems such as the difficulty in reducing the thickness of the polymer film in the traditional photoinitiator system, poor mechanical strength, and the difficulty in fully exerting the electrochemical performance, the present invention innovatively pre-treats the clay with the first modification, then performs the second modification, further combines the two-stage modification, further forms a clay-based film layer, and then compounds a polymer on its surface, so as to be able to prepare the double-layer composite electrolyte with excellent electronic and ionic conductivities and excellent electrochemical performance. In addition, the method of the present invention is simple to operate and easy to implement, has high process stability and battery performance repeatability, and is easy to scale up production.

[0035] In the present invention, the alkali metal ions include at least one of lithium, sodium, and potassium ions.

[0036] Preferably, in the first modification solution, the concentration of the alkali metal ions is below 3M, and further can be 0.3 - 0.6M.

[0037] Preferably, the solid-liquid ratio in the intercalation modification stage is 0.1 - 2 g / ml; further can be 0.5 - 0.6 g / ml.

[0038] Preferably, the temperature in the intercalation modification stage is 15 - 180 °C, and further can be 35 - 55 °C;

[0039] Preferably, the time for intercalation modification is 1 to 72 h, and further preferably 15 to 20 h.

[0040] In the present invention, after intercalation modification, subsequent modification treatment of Formula 1 is carried out, so that synergy can be achieved, and the conductivity and transference number of the obtained material can be improved.

[0041] In the present invention, in the modifier, the R 1 can be methyl or ethyl. The R 2 can be a substituted alkyl group, wherein the substituted amino group can be an amino group or a substituted amino group, and the substituted amino group is preferably at least one of phenylamino, alkylamino, etc. Research in the present invention shows that under a more preferred modifier, it can be further combined with the process synergistically, which helps to further improve the conductivity and transference number of the obtained composite material.

[0042] In the present invention, Formula A includes compounds having the following structure;

[0043]

[0044] The R 3 is a carbon chain of C1 - C4, and the R 4 is at least one of H, an alkyl group of C1 - C4, a phenyl group, and a substituted phenyl group. The substituted phenyl group is, for example, a substituted phenyl group with at least one substituent such as an alkyl group, an alkoxy group, a nitro group, a halogen, a trifluoromethyl group, etc.

[0045] Research in the present invention shows that when using Formula A2 as the modifier, especially when the R 4 is a group such as an alkyl group, a phenyl group, a substituted phenyl group, etc., it can further cooperate with the overall process, and is expected to further synergistically improve the conductivity and transference number of the obtained sandwich material.

[0046] Preferably, the modifier includes Formula A (especially Formula A2) and Formula B; more preferably, the weight ratio of Formula A to Formula B is 0.5 - 2:1. Research in the present invention also shows that Formula A (especially Formula A2) and Formula B as modifiers can be combined with other operations and parameters, and unexpectedly better process synergy can be obtained, which can improve the conductivity of the electrolyte and the ion migration effect.

[0047] Preferably, the weight of the modifier is 0.5 - 5% of the weight of the clay; preferably 1 - 2%.

[0048] In the present invention, the functionalized clay is dispersed in an aqueous solution, and then filtered, and the functionalized clay is stacked to form the functionalized clay-based membrane.

[0049] In a preferred embodiment of the present invention, clay can be subjected to alkali metal intercalation treatment, and then placed in a modification solution containing Formula A and Formula B for synergistic improvement, and then a base film is formed to obtain a preferred functionalized base film.

[0050] In another preferred embodiment of the present invention, the clay modified by alkali metal intercalation can be pre-modified with Formula A, and then a first base film is formed. Subsequently, a second base film is formed on the first base film using the clay modified by alkali metal intercalation and Formula B to obtain the functionalized base film.

[0051] In the present invention, thanks to the modification such as the combined modification of Formula A and Formula B, especially the combined control of the modification and structure of the special composite base film, further synergy can be achieved to improve the conductivity and transference number.

[0052] Preferably, the aqueous solution is water or a mixed solution of water and an organic solvent.

[0053] In the present invention, a polymer solution is directly compounded on the functionalized clay base film and then dried to form the polymer layer; or a precursor solution of the polymer is compounded on the polymer base film and then in-situ polymerized to form the polymer layer.

[0054] In the present invention, the compounding method includes at least one of coating, spraying, and knife coating.

[0055] In an alternative embodiment of the present invention, the precursor solution of the polymer contains a polyethylene oxide-based polymer monomer, a small molecule plasticizer, an electrolyte salt, a multi-arm crosslinking agent, and a photoinitiator.

[0056] In the present invention, the polyethylene oxide-based polymer monomer is selected from one or more of methoxypolyethylene glycol acrylate, polyethylene glycol diacrylate, methoxypolyethylene glycol methacrylate, polyethylene glycol methacrylate, polyethylene glycol dimethacrylate, and methoxypolyethylene glycol styrene. The content of the polymer monomer in the precursor solution is 0.1-50 wt%, and further can be 20-30 wt%.

[0057] In the present invention, the small molecule plasticizer is selected from one or more of fluorinated ethylene carbonate, 1,3-dioxolane, ethylene glycol dimethyl ether, ethylene carbonate, diethyl carbonate, dimethyl carbonate, propylene carbonate, ethyl methyl carbonate, and trifluoroacetate. The content of the plasticizer in the precursor solution is 1-60 wt%, and further can be 40-50 wt%.

[0058] In the present invention, the multi-arm crosslinking agent is selected from one or more of ethoxylated glycerol triacrylate, ethoxylated bisphenol A diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethoxylated pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, pentaerythritol glycidyl ether, trimethylolpropane triglycidyl ether, glycerol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether. The content of the multi-arm crosslinking agent in the precursor solution is 0.1 to 10 wt%, and further can be 2 to 3 wt%.

[0059] In the present invention, the photoinitiator is selected from one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, benzophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-4'-(methylthio)-2-morpholinopropiophenone. The content of the photoinitiator in the precursor solution is 0.01 to 5 wt%, and further can be 0.2 to 0.3 wt%.

[0060] In the present invention, the electrolyte salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium difluoro(oxalato)phosphate, lithium difluorophosphate, sodium bis(trifluoromethanesulfonyl)imide, sodium hexafluorophosphate, sodium perchlorate, sodium tetrafluoroborate, sodium bis(oxalato)borate, sodium difluoro(oxalato)phosphate, sodium difluorophosphate, potassium bis(fluorosulfonyl)imide, potassium fluoroborate, potassium hexafluorophosphate, potassium perchlorate. The concentration of the electrolyte salt is 0.1 to 5 mol / L. In the present invention, in the precursor solution, the balance is the electrolyte salt.

[0061] The present invention also provides an application of the functionalized clay-based film@polymer composite electrolyte, using it as a barrier layer for preparing solid or semi-solid secondary batteries.

[0062] Preferably, it is disposed between the positive electrode and the negative electrode.

[0063] Preferably, it is compounded on the positive electrode to form a composite positive electrode, and / or it is compounded on the negative electrode to form a composite negative electrode.

[0064] Preferably, the solid or semi-solid secondary battery is a lithium-ion battery and / or a sodium-ion battery.

[0065] The present invention also provides a solid or semi-solid secondary battery, which includes the functionalized clay-based film@polymer composite electrolyte, or is prepared by the functionalized clay-based film@polymer composite electrolyte.

[0066] For the solid or semi-solid secondary battery described in the present invention, except for the composite solid electrolyte described in the present invention, other components and structures can be known.

[0067] Advantageous Effects

[0068] The present invention provides a modified clay-polymer bilayer composite electrolyte. Based on the combined modification method of the modified clay and the combined control of the sandwich structure, synergy can be achieved, the effective film thickness of the electrolyte can be significantly reduced. In addition, the ionic and electronic conduction capabilities of the composite electrolyte can be enhanced, and its electrochemical performance can be improved.

[0069] The research of the present invention shows that using sepiolite as the clay and the formula A2 and / or formula B as the modifier can further achieve the adaptability synergy of the structure and chemical properties of the components, further improve the ionic and electronic conduction capabilities of the composite electrolyte, and improve its electrochemical performance. Description of the Drawings

[0070] Figure 1 Optical photograph of the functionalized clay-based film obtained in Example 1.

[0071] Figure 2 Impedance comparison diagram of the modified clay-based film composite electrolyte M-CPE obtained in Example 1, the unmodified clay-based film composite electrolyte UM-CPE, and the solid electrolyte SPE without added clay.

[0072] Figure 3 Linear sweep voltammetry comparison diagram of the modified clay-based film composite electrolyte M-CPE obtained in Example 1, the unmodified clay-based film composite electrolyte UM-CPE, and the solid electrolyte SPE without added clay.

[0073] Figure 4 Results of the lithium ion transference number of the solid electrolyte SPE without added clay, namely the potentiostatic current-time curve and the impedance changes before and after.

[0074] Figure 5 Results of the lithium ion transference number of the unmodified clay-based film composite electrolyte UM-CPE, namely the potentiostatic current-time curve and the impedance changes before and after.

[0075] Figure 6 Results of the lithium ion transference number of the modified clay-based film composite electrolyte M-CPE obtained in Example 1, namely the potentiostatic current-time curve and the impedance changes before and after. Detailed Embodiments

[0076] The following examples are intended to further illustrate the content of the present invention in detail, rather than limiting the scope of protection of the claims of the present invention.

[0077] The preparation method of an enumerable functionalized clay-based membrane in the present invention is as follows:

[0078] (1) Disperse the said nano-clay in an aqueous solution of metal salt A, and perform an ion exchange reaction by stirring at a high temperature to obtain the nano-clay after the corresponding salt cation exchange;

[0079] (2) Disperse the nano-clay after the corresponding salt cation exchange in a functionalizing reagent, and perform functionalized grafting by stirring at a high temperature to obtain the corresponding functionalized nano-clay;

[0080] (3) Disperse the corresponding functionalized nano-clay in deionized water, perform vacuum filtration, and dry at a high temperature to obtain an independent functionalized clay-based membrane.

[0081] An optional preparation method of a composite solid electrolyte in the present invention may have the following steps:

[0082] (1) Prepare a precursor solution of a polymer solid electrolyte, where the precursor solution contains a polyethylene oxide-based polymer monomer, a small molecule plasticizer, an electrolyte salt, a multi-arm crosslinking agent, and a photoinitiator;

[0083] (2) Attach the electrolyte precursor solution to the functionalized clay-based membrane by methods such as soaking, spraying, and scraping, and then cure it by ultraviolet light irradiation to obtain a composite solid electrolyte.

[0084] Preferably, the stirring time of the precursor solution prepared in a certain proportion is 0.1 - 24 h.

[0085] Preferably, the soaking time of the inorganic clay-based membrane is 0.1 - 3 h, the wavelength of the ultraviolet light irradiation is 254 - 365 nm, and the ultraviolet light irradiation time is 0.1 - 100 min.

[0086] In the present invention, the application of the composite solid electrolyte with a clay as the base membrane prepared by any one of the said preparation methods in a lithium metal, sodium metal, or potassium metal battery.

[0087] In the following examples, the selected negative electrode is a lithium metal, and the specific performance test method includes the following steps:

[0088] (1) Impedance test: Assemble the prepared composite solid electrolyte membrane between two steel sheets in a glove box to form a CR2025 type coin cell. Use the alternating current impedance technique (EIS) in a Gamry electrochemical workstation to test the battery.

[0089] (2) Electrochemical stability window test: Assemble the prepared composite solid electrolyte membrane between a steel sheet and a commercial lithium sheet in a glove box to form a CR2025 type coin cell. Use linear sweep voltammetry (LSV) in a Gamry electrochemical workstation to test the battery.

[0090] (3) Ion transference number test: In the glove box, the prepared composite solid electrolyte membrane was sandwiched between two commercial lithium foils to assemble a CR2025 coin cell. The battery was tested using the alternating current impedance technique (EIS) and potentiostatic polarization in a Gamry electrochemical workstation to obtain the change in the constant potential current and the change in impedance before and after the battery test.

[0091] In the present invention, the ion transference number refers to the ion transference number in a lithium-ion battery.

[0092] Example 1

[0093] An integrated composite electrolyte based on a functionalized clay-based membrane, where the nano-clay mineral is sepiolite and the functionalizing reagent is modifier 1 The polymer monomer is methoxypolyethylene glycol acrylate, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide, the plasticizer is fluoroethylene carbonate, the crosslinking agent is trimethylolpropane triacrylate, and the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0094] Step 1: The preparation method of the functionalized clay-based membrane includes the following steps:

[0095] (1.1) Take 0.05 g of sepiolite, add 0.5 mol / L lithium chloride solution (liquid-solid ratio is 0.5 - 0.6 g / mL) to a beaker, stir at 40 °C for the first-stage modification for 16 h, and ultrasonication was carried out for the first 30 min before the treatment;

[0096] (1.2) Add 1 wt% of modifier 1 based on the weight of the clay to the clay solution, stir at 40 °C for the second-stage modification for 16 h;

[0097] (1.3) Vacuum filtration, drying at 50 °C for 12 h to obtain a clay-based membrane (thickness is 50 μm).

[0098] Step 2: The preparation method of the composite solid electrolyte includes the following steps:

[0099] (2.1) Prepare the precursor solution: The polymer monomer is methoxypolyethylene glycol acrylate (0.5 g, its content in the precursor solution is 22.4 wt%), the lithium salt is lithium bis(trifluoromethanesulfonyl)imide (0.673 g, EO:Li + = 4:1), the plasticizer is fluoroethylene carbonate (1 g, its content in the precursor solution is 44.9 wt%), the crosslinking agent is trimethylolpropane triacrylate (0.05 g, its content in the precursor solution is 2.2 wt%), and the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone (0.005 g, its content in the precursor solution is 0.2 wt%).

[0100] Stir at room temperature for 4 h;

[0101] (2.2) Coat the precursor solution on one side of the sepiolite-based membrane, transfer it to a 365 nm ultraviolet lamp for ultraviolet photopolymerization for 3 min, and then perform the same operation on the other side to obtain the modified material with the sandwich structure (total thickness of 100 μm).

[0102] The room temperature ionic conductivity of the composite solid electrolyte (M-CPE) prepared in Example 1 is 7.7×10 -4 S cm -1 , the electrochemical window is 4.99 V, and the transference number is 0.38.

[0103] Example 2

[0104] Compared with Example 1, the difference is only that the composition of the clay is changed, and other operations and parameters are the same as those in Example 1. The experimental results are as follows:

[0105] Group A: The clay is vermiculite. Other operations and parameters are the same as those in Example 1. The results are: the ionic conductivity is 5.8×10 -4 Scm -1 , the electrochemical window is 4.76 V, and the transference number is 0.22.

[0106] Control Group A: The clay is kaolin. Other operations and parameters are the same as those in Example 1. The results are: the ionic conductivity is 3.1×10 -4 S cm -1 , the electrochemical window is 4.68 V, and the transference number is 0.21.

[0107] Control Group B: The clay is attapulgite. Other operations and parameters are the same as those in Example 1; the materials and preparation conditions of this case are not compatible, the material preparation fails, and the impedance is large.

[0108] Control Group C: The clay is mullite. Other operations and parameters are the same as those in Example 1; the materials and preparation conditions of this case are not compatible, the material preparation fails, and the impedance is large.

[0109] It can be seen from Examples 1 and 2 that in the process of the present invention, sepiolite is used as the clay, and through the two-stage modification process of the present invention, the special physical and chemical characteristics and surface characteristics of sepiolite can be unexpectedly utilized, better adaptability and synergy can be obtained, and better conductivity and ion mobility can be exhibited.

[0110] Example 3

[0111] Compared with Example 1, the difference is only that the composition of the modifier is changed, and other operations and parameters are the same as those in Example 1. The experimental results are as follows:

[0112] Group A: The modifier is (Modifier 2);

[0113] Group B: The modifier is (Modifier 3);

[0114] Group C: The modifier is (Modifier 4);

[0115] Group D: The modifier is (Modifier 1) and (Modifier 4) with a weight ratio of 1:1.

[0116] Test according to the method of Example 1, and the results are as follows:

[0117] Group A: The room-temperature ionic conductivity of the prepared composite solid electrolyte is 4.2×10 -4 S cm -1 , the electrochemical window is 4.7 V, and the transference number is 0.24.

[0118] Group B: The room-temperature ionic conductivity of the prepared composite solid electrolyte is 4.3×10 -4 S cm -1 , the electrochemical window is 4.7 V, and the transference number is 0.23.

[0119] Group C: The room-temperature ionic conductivity of the prepared composite solid electrolyte is 5.3×10 -4 S cm -1 , the electrochemical window is 4.8 V, and the transference number is 0.28.

[0120] Group D: The room-temperature ionic conductivity of the prepared composite solid electrolyte is 8.5×10 -4 S cm -1 , the electrochemical window is 5.02 V, and the transference number is 0.40.

[0121] It can be seen from Examples 1 and 3 that by using the preferred Formula A2 and Formula B modifiers of the present invention, especially the Formula A modifier with R2 being a substituted amino group, in combination with the modification process of the present invention, it can further cooperate synergistically with the physicochemical characteristics of clay, which helps to further optimize the conductivity and ion mobility of the prepared materials.

[0122] Example 4

[0123] Compared with Example 1, the difference is only that the conditions of the treatment process are changed, specifically:

[0124] Step 1: The preparation method of the functionalized clay-based membrane includes the following steps:

[0125] (1.1) Take 0.05 g of sepiolite, add 0.4 mol / L sodium chloride solution (liquid-solid ratio is 0.5 - 0.6 g / mL) to the beaker, stir at 50 °C for the first-stage modification treatment for 20 h. Among them, ultrasonic treatment was also carried out 30 min before the treatment;

[0126] (1.2) Add 2 wt% of modifier 1 based on the weight of the clay to the clay solution, stir at 50 °C for the second-stage modification for 18 h;

[0127] (1.3) Vacuum filtration, dry at 50 °C for 12 h to obtain a clay-based membrane (thickness is 55 μm).

[0128] Step 2: The preparation method of the composite solid electrolyte includes the following steps:

[0129] (2.1) Prepare the precursor solution: The polymer monomer is methoxypolyethylene glycol acrylate (accounting for 28.5 wt% of the precursor solution), the plasticizer is fluoroethylene carbonate (accounting for 42.8 wt% of the precursor solution), the crosslinking agent is trimethylolpropane triacrylate (accounting for 2.9 wt% of the precursor solution), the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone (accounting for 0.3 wt% of the precursor solution), and the balance is lithium salt lithium bis(trifluoromethanesulfonyl)imide (EO:Li + = 4:1). Stir at room temperature for 3 h;

[0130] (2.2) Scrap the precursor solution on one side of the sepiolite-based membrane, transfer it to a 365 nm ultraviolet lamp for ultraviolet photopolymerization, with a light irradiation time of 2 min, and then perform the same operation on the other side to obtain the modified material with a sandwich structure (total thickness is 100 μm).

[0131] The room-temperature ionic conductivity of the composite solid electrolyte prepared in Example 4 is 7.6×10 -4 S cm -1 , the electrochemical window is 4.90 V, and the transference number is 0.36.

[0132] Example 5

[0133] Compared with Example 1, the difference is only that the first-stage filtration is carried out in advance using the second-stage modification system of Example 1 (the modification solution system in step 1.2 of Example 1) to form the first base membrane (the thickness is half of the clay-based membrane in step 1.3 of Example 1), and then the second-stage modification system of Example 3C (the modification solution system in step 1.2 of Example 3C) is used for the second-stage filtration to form the second base membrane layer on the first base membrane to obtain a composite base membrane (the thickness of the composite base membrane is the same as that of the base membrane in Example 1), and then subsequent treatments are carried out, and other operations and parameters are the same as those in Example 1.

[0134] The room-temperature ionic conductivity of the prepared composite solid electrolyte is 8.8×10 -4 S cm -1 , the electrochemical window is 5.05 V, and the transference number is 0.42.

[0135] It can be seen from Example 1, Example 3C, and Example 5 that by adopting the said composite modification and cooperating with the said double-layer base film process, the conductivity, chemical window, and transference number can be further enhanced.

[0136] Comparative Example 1

[0137] Compared with Example 1, the difference is only that the treatment in Step 1 is not carried out, and the said precursor solution is directly used for polymerization to form a solid electrolyte (marked as SPE).

[0138] Tested according to the method of Example 1, the results are as follows: the room-temperature ionic conductivity is 3.3×10 -4 S cm -1 , the electrochemical window is 4.67 V, and the transference number is 0.28.

[0139] Comparative Example 2

[0140] Compared with Example 1, the difference is only that the two-stage modification treatments in Step 1.1 and Step 1.2 are cancelled, and sepiolite is directly formed into a clay-based film. Other operations and parameters are the same as those in Example 1, and the prepared solid electrolyte is marked as UM-CPE.

[0141] Tested according to the method of Example 1, the results are as follows: the room-temperature ionic conductivity is 2.2×10 -4 S cm -1 , the electrochemical window is 4.82 V, and the transference number is 0.20.

[0142] Comparative Example 3

[0143] Compared with Example 1, the difference is only that the clay-based film is not formed (Step 1.3 is omitted), that is, the modified clay is not pre-formed into a base film, but the two-stage modified clay is directly mixed with the precursor solution and polymerized by light together.

[0144] The room-temperature ionic conductivity is 4.2×10 -4 S cm -1 , the electrochemical window is 4.71 V, and the transference number is 0.28.

[0145] Comparative Example 4

[0146] Compared with Example 1, the difference is only that in the process of clay modification, the first-stage modification is not carried out.

[0147] The room temperature ionic conductivity is 3.6×10 -4 S cm -1 , the electrochemical window is 4.75 V, and the transference number is 0.30.

[0148] Comparative Example 5

[0149] Compared with Example 1, the only difference is that in the process of clay modification, the second-stage modification is not carried out.

[0150] The room temperature ionic conductivity is 4.1×10 -4 S cm -1 , the electrochemical window is 4.80 V, and the transference number is 0.19.

[0151] Comparative Example 6

[0152] Compared with Example 1, the only difference is that the clay is first subjected to the second-stage modification and then the first-stage modification.

[0153] The room temperature ionic conductivity is 3.9×10 -4 S cm -1 , the electrochemical window is 4.81 V, and the transference number is 0.28.

Claims

1. Functionalized clay-based membrane@polymer composite electrolyte, characterized in that: It has a sandwich structure, which includes a functionalized clay-based membrane and a polymer layer composited on its two surfaces, wherein the functionalized clay-based membrane is a material layer formed by stacking functionalized clay, wherein the functionalized clay is a material that is pre-intercalated with alkali metal ions and then modified with a modifier; The modifier comprises at least one of formula A and formula B; The R1 is a C1-C6 alkyl group; the R2 is a substituted alkyl group with a substituent; the substituent includes at least one of an amino group, a substituted amino group, an epoxy group, a mercapto group, an acryloxy group, a vinyl group, and an isocyanate group; Said n is an integer of 2 to 6, and M is H, Na, K or NH4; The clay is vermiculite and / or sepiolite.

2. The functionalized clay-based membrane@polymer composite electrolyte according to claim 1, characterized in that: The clay is nanoclay, preferably including at least one of montmorillonite, kaolin, lithophore, attapulgite, mullite, bentonite, vermiculite, sepiolite and halloysite; Preferably, the thickness of the functionalized clay-based membrane is 30 to 60 μm; Preferably, the functionalized clay in the functionalized clay-based membrane is obtained by alkali metal ion intercalation and subsequent modification of formula A and formula B; Preferably, the functionalized clay base film comprises a first base film and a second base film composited on the surface; wherein the functionalized clay in the first base film is obtained by alkali metal ion intercalation and modification of formula A, and the functionalized clay in the second base film is obtained by alkali metal ion intercalation and modification of formula B; Preferably, the polymer layer is obtained by in-situ polymerization of polymer monomers on the functionalized clay-based membrane; Preferably, the polymer is a polyethylene oxide polymer; Preferably, the thickness of the functionalized clay-based membrane@polymer composite electrolyte may be 90 to 120 μm.

3. A method for preparing a functionalized clay-based membrane@polymer composite electrolyte according to any one of claims 1 to 2, characterized in that the steps include: Step 1: Functionalized clay-based membrane preparation Step 1A: First modification Placing clay in a first modification solution containing alkali metal ions to perform intercalation modification to obtain a first modified clay; Step 1B: Second Modification placing the first modified clay in a second modifying solution containing the modifier to perform a second modification to obtain the functionalized clay; Step 1C: Basement membrane preparation Forming the functionalized clay into a functionalized clay-based membrane; Step 2: Composite electrolyte preparation A polymer is compounded on the functionalized clay-based membrane to obtain the functionalized clay-based membrane@polymer composite electrolyte.

4. The method for preparing the functionalized clay-based membrane@polymer composite electrolyte according to claim 3, characterized in that: The alkali metal ions include at least one of lithium, sodium and potassium; Preferably, in the first modified solution, the concentration of alkali metal ions is below 3M; Preferably, the solid-to-liquid ratio in the intercalation modification stage is 0.1 to 2 g / ml; Preferably, the temperature in the intercalation modification stage is 15 to 180°C; Preferably, the intercalation modification time is 1 to 72 hours.

5. The method for preparing the functionalized clay-based membrane@polymer composite electrolyte according to claim 3, characterized in that: The formula A includes compounds with the following structures: The R3 is a C1-C4 carbon chain, and the R4 is at least one of H, a C1-C4 alkyl, a phenyl, and a substituted phenyl; Preferably, the modifier comprises formula A and formula B; further preferably, the weight ratio of formula A to formula B is 0.5 to 2:1; Preferably, the weight of the modifier and the clay is 0.5-5%; preferably 1-2%.

6. The method for preparing the functionalized clay-based membrane@polymer composite electrolyte according to claim 3, characterized in that: Dispersing the functionalized clay in an aqueous solution, then filtering, and stacking the functionalized clay to form the functionalized clay-based membrane; Preferably, the aqueous solution is water, or a mixed solution of water-organic solvent.

7. The method for preparing the functionalized clay-based membrane@polymer composite electrolyte according to claim 3, characterized in that: Directly compounding a polymer solution on the functionalized clay-based membrane, followed by drying to form the polymer layer; or compounding a polymer precursor solution on the polymer-based membrane, followed by in-situ polymerization to form the polymer layer; Preferably, the compounding method includes at least one of coating, spraying and scraping.

8. The method for preparing the functionalized clay-based membrane@polymer composite electrolyte according to claim 7, characterized in that: The polymer precursor solution includes a polyoxyethylene polymer monomer, a small molecule plasticizer, an electrolyte salt, a multi-arm cross-linking agent and a photoinitiator; Preferably, the polyethylene oxide polymer monomer is selected from one or more of methoxy polyethylene glycol acrylate, polyethylene glycol diacrylate, methoxy polyethylene glycol methacrylate, polyethylene glycol methacrylate, polyethylene glycol dimethacrylate, and methoxy polyethylene glycol styrene, and the content of the polymer monomer in the precursor solution is 0.1 to 50 wt.%, and can further be 20 to 30 wt.%; Preferably, the small molecule plasticizer is selected from one or more of fluoroethylene carbonate, 1,3-dioxolane, ethylene glycol dimethyl ether, ethylene carbonate, diethyl carbonate, dimethyl carbonate, propylene carbonate, ethyl methyl carbonate, trifluoroacetate, and the content of the plasticizer in the precursor solution is 1 to 60 wt %, and can further be 40 to 50 wt %. Preferably, the electrolyte salt is selected from one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium bis(oxalatoborate), lithium difluorobis(oxalatophosphate), lithium difluorophosphate, sodium bis(trifluoromethanesulfonyl)imide, sodium hexafluorophosphate, sodium perchlorate, sodium tetrafluoroborate, sodium bis(oxalatoborate), sodium difluorobis(oxalatophosphate), sodium difluorophosphate, potassium bis(fluorosulfonyl)imide, potassium fluoroborate, potassium hexafluorophosphate, and potassium perchlorate, and the electrolyte salt concentration is 0.1 to 5 mol / L. Preferably, the multi-arm cross-linking agent is selected from one or more of ethoxylated glycerol triacrylate, ethoxylated bisphenol A diacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethoxylated pentaerythritol tetraacrylate, pentaerythritol tetraacrylate, pentaerythritol glycidyl ether, trimethylolpropane triglycidyl ether, glycerol diglycidyl ether, 1,4-butanediol diglycidyl ether, and 1,6-hexanediol diglycidyl ether, and the content of the multi-arm cross-linking agent in the precursor solution is 0.1-10wt%, and can further be 2-3wt.%; Preferably, the photoinitiator is selected from one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, phenyl di(2,4,6-trimethylbenzoyl)phosphine oxide, benzophenone, 2,2-dimethoxy-2-phenylethanone, 1-hydroxycyclohexyl phenyl ketone, and 2-methyl-4'-(methylthio)-2-morpholinoacetone, and the content of the photoinitiator in the precursor solution is 0.01 to 5 wt%, and can further be 0.2 to 0.3 wt.%.

9. An application of the functionalized clay-based membrane@polymer composite electrolyte according to any one of claims 1 to 2 or the functionalized clay-based membrane@polymer composite electrolyte prepared by the preparation method according to any one of claims 3 to 8, characterized in that: It is used as a barrier layer to prepare solid-state or semi-solid-state secondary batteries; Preferably, it is arranged between the positive electrode and the negative electrode; Preferably, it is compounded on the positive electrode to form a composite positive electrode, and / or, it is compounded on the negative electrode to form a composite negative electrode; Preferably, the solid-state or semi-solid-state secondary battery is a lithium-ion battery and / or a sodium-ion battery.

10. A solid or semi-solid secondary battery, characterized in that: The invention comprises the functionalized clay-based membrane@polymer composite electrolyte described in any one of claims 1 to 2 or the functionalized clay-based membrane@polymer composite electrolyte prepared by the preparation method described in any one of claims 3 to 8, or is prepared by the functionalized clay-based membrane@polymer composite electrolyte.

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