CN114284639A

CN114284639A - Inorganic/organic composite diaphragm and preparation method thereof

Info

Publication number: CN114284639A
Application number: CN202111583875.5A
Authority: CN
Inventors: 庄志; 吴惠康; 潘星星; 刘倩倩; 鲍晋珍; 程跃
Original assignee: Shanghai Energy New Materials Technology Co Ltd
Current assignee: Jiangxi Tongrui New Energy Technology Development Co ltd
Priority date: 2021-12-23
Filing date: 2021-12-23
Publication date: 2022-04-05
Anticipated expiration: 2041-12-23
Also published as: CN114284639B; WO2023115756A1

Abstract

The present invention provides an inorganic/organic composite separator, comprising: the organic solid electrolyte comprises an organic polymer, and the organic polymer is formed by in-situ polymerization reaction between the inner pores of the inorganic layer and the surface of the inorganic layer.

Description

Inorganic/organic composite diaphragm and preparation method thereof

Technical Field

The invention relates to the technical field related to battery separators, in particular to an ionic conductor/organic solid electrolyte composite separator and a preparation method thereof.

Background

The separator is a basic component of a lithium battery, and mainly has the main function of separating the positive electrode and the negative electrode of the battery, only allowing electrolyte ions to pass through to prevent the two electrodes from contacting and short-circuiting, and the characteristics of the separator have direct influence on the performance of the battery, for example, the performance of the separator can determine the interface structure, the internal resistance and the like of the battery, and further directly influence the capacity, the cycle life, the safety and stability and the like of the battery.

The coated separator containing an inorganic oxide such as alumina is effective in improving the thermal stability and electrolyte-retaining ability of the separator, thereby improving the performance of a lithium battery, but does not substantially contribute to the improvement of electrical conductivity. In addition, a coated separator containing an inorganic solid electrolyte such as Lithium Lanthanum Zirconium Oxide (LLZO) or Lithium Aluminum Titanium Phosphate (LATP) can improve the lithium ion conductivity of the separator, but since the inorganic solid electrolyte is difficult to form a densely packed continuous ion conduction network, the lithium ion conduction capability of the separator is affected, and meanwhile, part of the inorganic solid electrolyte has poor stability to lithium metal, and a stable interface is difficult to form, thereby affecting the battery life.

Disclosure of Invention

In view of the above, the present invention is directed to a composite separator and a method for preparing the same, which uses a membrane containing an inorganic layer as a main body and performs an in-situ polymerization reaction between the inner pores of the inorganic layer and the surface of the inorganic layer to form an organic polymer as an organic solid electrolyte, so as to solve the current problems encountered in the separator.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

Preferably, the inorganic layer has an internal porosity of less than 30%.

Preferably, the inorganic layer comprises one or a combination of inorganic solid electrolyte and inorganic ceramic.

Preferably, the inorganic solid electrolyte comprises a combination of one or more of an oxide solid electrolyte, a sulfide solid electrolyte.

Preferably, the oxide solid electrolyte comprises lithium lanthanum zirconium oxide, lithium titanium aluminum phosphate, garnet-type oxide Li_xLn₃M₂O₁₂Wherein Ln is La or Y, M is Zr, Nb, Sn, Sb, Te, Hf or Ta, and x is 3-7.

Preferably, the sulfide solid electrolyte comprises a combination of one or more of LGPS, LPS, LPSCl, LSnPS, LSiPS, LGSiPS, LAlPS, LGS, LGZS, LSiS, LSAlS.

Preferably, the inorganic solid electrolyte comprises a combination of one or more of garnet-type conductive materials, sulfide-type conductive materials, perovskite-type conductive materials, LiSiON-type conductive materials, LiPON-type conductive materials, Li 3N-type conductive materials.

Preferably, the inorganic ceramic comprises a combination of one or more of alumina, silica, metal oxides, metal nitrides, metal phosphides, metal sulfides, and metal borides.

Preferably, the organic polymer comprises one or more of polyethers, polycarbonates, polyvinylidene fluoride, polyurethanes, polyacrylonitriles, polyimides, polyacrylics, and metal polyacrylates.

Preferably, the organic solid electrolyte further comprises a lithium salt.

Preferably, the organic solid electrolyte further comprises lithium salt and plasticizer.

Preferably, the lithium salt comprises one or more of lithium hexafluorophosphate, lithium dioxalate borate, lithium bistrifluoromethanesulfonimide, lithium bifluorosulfonimide, lithium perchlorate, lithium difluorooxalate borate and lithium tetrafluoroborate.

Preferably, the plasticizer comprises one or more of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, fluoroethylene carbonate, difluoroethylene carbonate, vinyl chloride, 1, 3-dioxolane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, 1, 3-propane sultone, and succinonitrile.

The present invention also provides a method for preparing an inorganic/organic composite separator, which comprises:

providing a base film; forming an inorganic layer on the base film, the inorganic layer having internal pores; filling a precursor in the internal pores of the inorganic layer and distributing on the surface of the inorganic layer; polymerizing the precursor in situ in the internal pores of the inorganic layer and on the surface of the inorganic layer to form an organic polymer, thereby obtaining an organic solid electrolyte filled in the internal pores of the inorganic layer and distributed on the surface of the inorganic layer and including the organic polymer.

Preferably, the in situ polymerization is carried out by standing at room temperature, heating or irradiation with light.

Preferably, the prepolymer comprises one or more of cyclic ether compounds and polyethylene glycol diglycidyl ether.

The invention has the following beneficial effects:

1) according to the invention, the organic polymer is formed in the internal pores of the inorganic layer through in-situ polymerization reaction, so that the pores of the inorganic layer can be effectively filled, and a continuous lithium ion channel is formed, thereby improving the ionic conductivity and stability of the diaphragm and improving the battery performance.

2) The inorganic layer is formed on one surface of the base film, and the organic polymer is formed in the internal pores and the surface of the inorganic layer through in-situ polymerization reaction, so that the organic polymer can form a protective layer on the surface of the inorganic layer on the surface of the base film, and the interface stability of the diaphragm and the anode or the cathode of the battery is further improved to improve the performance of the battery.

3) The invention forms inorganic layers on two surfaces of the base film and forms organic polymers in the inner holes and surfaces of the inorganic layers through in-situ polymerization reaction, so that the organic polymers can form protective layers on the surfaces of the inorganic layers on the two surfaces of the base film, and further the interface stability of the diaphragm and the battery anode and cathode is improved to improve the battery performance.

Drawings

FIG. 1 is a schematic structural diagram of an inorganic/organic composite separator according to an embodiment of the present invention;

FIG. 2 is a schematic structural view of an inorganic/organic composite separator according to another embodiment of the present invention;

fig. 3 is a flowchart of a method for manufacturing an inorganic/organic composite separator according to another embodiment of the present invention;

FIG. 4 is a scanning electron micrograph showing a cross section of a film obtained in example 1;

FIG. 5 is a scanning electron micrograph showing a cross section of a film obtained in example 4;

FIG. 6 is a graph of time-voltage and time-current illustrating the voltage and current measured for different number of charge-discharge cycles at room temperature for a Li-Cu half-cell assembled with the membrane obtained in comparative example 3 as a separator;

FIG. 7 is a graph of time-voltage and time-current, illustrating the voltage and current measured in the last 20 charge-discharge cycles at room temperature of a Li-Cu half-cell assembled with the membrane obtained in comparative example 3 as a separator;

fig. 8 is a graph of time versus voltage and time versus current, which is a graph of time versus voltage and time versus current, illustrating the voltage and current measured at different times of charge and discharge cycles of the Li-Cu half cell assembled with the membrane obtained in example 1 as the separator at normal temperature;

description of component reference numerals

1 … base film

2 … inorganic layer

3 … organic solid electrolyte

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

As shown in fig. 1, an embodiment of the present invention provides an inorganic/organic composite separator, which includes: the organic solid electrolyte comprises a base film 1, an inorganic layer 2 and an organic solid electrolyte 3, wherein the inorganic layer 2 is formed on one surface of the base film 1 and has internal pores, the organic solid electrolyte 3 is filled in the internal pores of the inorganic layer 2 and distributed on one surface of the inorganic layer 2, and the organic solid electrolyte 3 comprises an organic polymer which is formed by in-situ polymerization reaction between the internal pores of the inorganic layer 2 and the surface of the inorganic layer 2.

Specifically, the base film may be a PE base film or a PP base film, and may be a wet base film or a dry base film.

Specifically, the internal porosity of the inorganic layer may be greater than 0%, less than 30%.

In particular, the inorganic layer may include one or a combination of inorganic solid electrolytes, inorganic ceramics. For example, the inorganic solid electrolyte includes a combination of one or more of an oxide solid electrolyte, a sulfide solid electrolyte. Also for example, the oxide solid electrolyte includes lithium lanthanum zirconium oxide, lithium titanium aluminum phosphate, garnet-type oxide LixLn₃M₂O₁₂Wherein Ln is La or Y, M is Zr, Nb, Sn, Sb, Te, Hf or Ta, x is between 3 and 7, and the sulfide solid electrolyte comprises a combination of one or more of LGPS, LPS, LPSCl, LSnPS, LSiPS, LGSiPS, LAlPS, LGS, LGZS, LSiS, LSAlS. By way of further example, the inorganic ceramic comprises a combination of one or more of alumina, silica, metal oxides, metal nitrides, metal phosphides, metal sulfides, and metal borides.

In particular, the inorganic layer may include one or a combination of inorganic solid electrolytes, inorganic ceramics. For example, the inorganic solid electrolyte includes a combination of one or more of a garnet-type conductive material, a sulfide-type conductive material, a perovskite-type conductive material, a LiSiON-type conductive material, a LiPON-type conductive material, and a Li 3N-type conductive material. By way of further example, the inorganic ceramic comprises a combination of one or more of alumina, silica, metal oxides, metal nitrides, metal phosphides, metal sulfides, and metal borides.

Specifically, the organic polymer may include one or a combination of more of polyethers, polycarbonates, polyvinylidene fluoride, polyurethanes, polyacrylonitriles, polyimides, polyacrylics, and metal polyacrylates.

Specifically, the organic solid electrolyte may further include a lithium salt in addition to the organic polymer. The addition of the lithium salt can increase the number of charge carriers in the solid electrolyte to improve the conductivity of the battery, and examples thereof include one or a combination of more of lithium hexafluorophosphate, lithium dioxalate borate, lithium bistrifluoromethanesulfonylimide, lithium bifluorosulfonylimide, lithium perchlorate, lithium difluorooxalylimide, and lithium tetrafluoroborate.

Specifically, the organic solid electrolyte may further include a lithium salt, a plasticizer, in addition to the organic polymer. As previously mentioned, the addition of a lithium salt can increase the number of charge carriers in the solid electrolyte to increase the conductivity of the battery, examples of which include a combination of one or more of lithium hexafluorophosphate, lithium dioxalate borate, lithium bistrifluoromethanesulfonylimide, lithium difluorooxalato borate, and lithium tetrafluoroborate. The plasticizer is added to lower the Tg temperature of the organic solid electrolyte (2) to improve the conductivity of the battery, and examples thereof include one or a combination of more of propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, fluoroethylene carbonate, difluoroethylene carbonate, vinyl chloride, 1, 3-dioxolane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, 1, 3-propane sultone, and succinonitrile.

As shown in fig. 2, another embodiment of the present invention provides an inorganic/organic composite separator, which is substantially similar to the structure shown in fig. 1, except that inorganic layers 2 are formed on both surfaces of a base film 1, an organic solid electrolyte 3 is distributed on one surface of each inorganic layer 2, and an organic polymer is formed on the surface of each inorganic layer 2 by in-situ polymerization. Compared with the structure shown in fig. 1 in which the organic/inorganic composite structure is formed on only a single surface of the base film and is in contact with only one of the positive electrode and the negative electrode to improve interface stability and improve battery performance, the structure shown in fig. 2 in which the organic/inorganic composite structure is formed on both surfaces of the base film and is in contact with the positive electrode and the negative electrode to improve interface stability and improve battery performance is more beneficial to the performance of battery electrical properties.

Referring to fig. 3, another embodiment of the present invention illustrates a method for preparing the inorganic/organic composite separator, which is described in detail as follows:

first, a base film is provided.

Specifically, the base film may be a PE base film or a PP base film.

Specifically, the base film may be a wet base film or a dry base film.

Next, an inorganic layer is formed on the base film, and the inorganic layer has internal pores.

Specifically, an inorganic layer may be formed on one surface of the base film. For example, an inorganic slurry is applied on one surface of the base film, and then dried to form an inorganic layer.

Specifically, inorganic layers may be formed on both surfaces of the base film. For example, an inorganic slurry is applied to each of both surfaces of the base film, and then dried to form an inorganic layer.

Specifically, the inorganic slurry may further include a solvent, a binder, in addition to one or more of an inorganic solid electrolyte and an inorganic ceramic. The addition of the solvent may dissolve the organic components in the inorganic slurry and disperse the inorganic components in the inorganic slurry so that the components of the inorganic slurry are uniformly distributed on the base film, and examples thereof include one or a combination of more of water, methanol, ethanol, isopropanol, acetonitrile, acetone, DMAc, NMP, THF, DMF, anhydrous hydrazine, toluene, n-heptane, xylene, and anisole. The addition of a binder may stabilize the inorganic layer on the base film, examples of which include a combination of one or more of PTFE, FEP copolymer, PFA resin, PCTFF, ECTFE copolymer, ETFE, PVDF, PVF. Further, under the condition that the inorganic slurry includes one of the inorganic solid electrolyte and the inorganic ceramic, the weight ratio between the inorganic solid electrolyte or the inorganic ceramic and the binder may be 3: 1-25: 1, preferably 5: 1-15: 1. moreover, the solvent may account for 40 wt% to 65 wt%, the inorganic solid electrolyte or the inorganic ceramic may account for 30 wt% to 50 wt%, and the binder may account for 2 wt% to 10 wt%, based on the total weight of the inorganic slurry. Under the condition that the inorganic slurry includes a combination of plural kinds of the inorganic solid electrolyte, the inorganic ceramic, the weight ratio between the entirety of the inorganic solid electrolyte and the inorganic ceramic and the binder may be 3: 1-25: 1, preferably 5: 1-15: 1. moreover, the solvent may account for 40 wt% to 65 wt%, the inorganic solid electrolyte and the inorganic ceramic may account for 30 wt% to 50 wt%, and the binder may account for 2 wt% to 10 wt%, based on the total weight of the inorganic slurry.

Specifically, the inorganic slurry may further include a dispersant, a solvent, and a binder, in addition to one or more of an inorganic solid electrolyte and an inorganic ceramic. The addition of the dispersant can make the components in the inorganic layer uniformly distributed, and examples thereof include one or a combination of more of polyvinyl alcohol, polyethylene oxide, polyacrylate, and polyvinyl pyrrolidone. The addition of the solvent may dissolve the organic components in the inorganic slurry and disperse the inorganic components in the inorganic slurry so that the components of the inorganic slurry are uniformly distributed on the base film, and examples thereof include one or a combination of more of water, methanol, ethanol, isopropanol, acetonitrile, acetone, DMAc, NMP, THF, DMF, anhydrous hydrazine, toluene, n-heptane, xylene, and anisole. The addition of a binder may stabilize the inorganic layer on the base film, examples of which include a combination of one or more of PTFE, FEP copolymer, PFA resin, PCTFF, ECTFE copolymer, ETFE, PVDF, PVF. Further, under the condition that the inorganic slurry includes one of the inorganic solid electrolyte and the inorganic ceramic, the weight ratio between the inorganic solid electrolyte or the inorganic ceramic and the binder may be 3: 1-25: 1, preferably 5: 1-15: 1. moreover, based on the total weight of the inorganic slurry, the solvent may account for 40 wt% to 65 wt%, the inorganic solid electrolyte or the inorganic ceramic may account for 30 wt% to 50 wt%, the dispersant may account for 0.05 wt% to 0.3 wt%, and the binder may account for 2 wt% to 10 wt%. Further, under the condition that the inorganic slurry includes a combination of plural kinds of the inorganic solid electrolyte and the inorganic ceramic, the weight ratio between the entirety of the inorganic solid electrolyte and the inorganic ceramic and the binder may be 3: 1-25: 1, preferably 5: 1-15: 1. moreover, based on the total weight of the inorganic slurry, the solvent may account for 40 wt% to 65 wt%, the inorganic solid electrolyte and the inorganic ceramic may account for 30 wt% to 50 wt%, the dispersant may account for 0.05 wt% to 0.3 wt%, and the binder may account for 2 wt% to 10 wt%.

Furthermore, a precursor is filled in the inner pores of the inorganic layer and distributed on the surface of the inorganic layer.

Specifically, the precursor may be dropped on the inorganic layer and coated, or the inorganic layer may be infiltrated in the precursor, such that the precursor is filled in the internal pores of the inorganic layer and distributed on the surface of the inorganic layer. For example, a precursor solution may be dropped on the inorganic layer and coated, or the inorganic layer may be soaked in the precursor solution, such that the precursor solution is filled in the internal pores of the inorganic layer and distributed on the surface of the inorganic layer.

Specifically, the precursor is a unit of a subsequently formed organic polymer, such as a monomer or an oligomer, and in order to accelerate the efficiency of filling the precursor in the internal pores of the inorganic layer and distributing the precursor on the surface thereof, the precursor preferably has a low viscosity. For example, the monomer may include a cyclic ether compound; the cyclic ether compound may contain 1 or more oxygen atoms, or may contain a single or more ring structures, or may contain a carbon-carbon double bond, or may contain 1 or more substituents. More specifically, the cyclic ether compound may be substituted or unsubstituted 1, 3-dioxolane or substituted or unsubstituted 1, 4-dioxahexane. Also for example, the oligomer may include polyethylene glycol diglycidyl ether.

Specifically, under the condition that the organic solid electrolyte obtained subsequently further includes lithium salt, after the lithium salt and the precursor can be mixed into a precursor solution, the precursor solution is dripped into the inorganic layer and coated or the inorganic layer is soaked into the precursor solution, so that the precursor solution is filled in the internal pores of the inorganic layer and distributed on the surface of the inorganic layer. Preferably, the prepolymer may comprise 90 wt% to 98 wt% and the lithium salt may comprise 2 wt% to 10 wt% based on the total weight of the prepolymer solution. Preferably, the prepolymer is an oligomer, such as polyethylene glycol diglycidyl ether. Also preferably, the prepolymer is a monomer, such as 1, 3-dioxolane or vinylene carbonate.

Specifically, under the condition that the organic solid electrolyte obtained subsequently further includes lithium salt and an initiator, after the lithium salt, the initiator and the prepolymer can be mixed into a prepolymer solution, the prepolymer solution is dripped into the inorganic layer and coated or the inorganic layer is soaked into the prepolymer solution, so that the prepolymer solution is filled in the internal pores of the inorganic layer and distributed on the surface of the inorganic layer. The initiator may initiate the reaction of the prepolymer to form the organic polymer. For example, the initiator may include common commercial thermal initiators, photoinitiators, or other lewis acids capable of initiating ring-opening polymerization of epoxy ethers. More by way of example, the initiator may include lithium hexafluorophosphate, lithium tetrafluoroborate, tin difluoride, trifluoroacetic acid, boron trifluoride, aluminum trifluoromethanesulfonate, magnesium trifluoromethanesulfonate, tin trifluoromethanesulfonate, bismuth trifluoromethanesulfonate, azobisisobutyronitrile, azobisisoheptonitrile, dimethyl azobisisobutyrate, benzoyl peroxide tert-butyl peroxide, benzophenone, 2-hydroxy-2-methyl-1-phenyl ketone, 1-hydroxy-cyclohexyl-1-phenyl ketone, 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone, benzoin dimethyl ether, ethyl 4- (N, N-dimethylamino) benzoate, isopropylthioxanthone, 4-chlorobenzophenone, benzophenone trifluor, One or more of methyl o-benzoylbenzoate, 4-methylbenzophenone, 4-phenylbenzophenone and 4-methyl dimethyl acetone. Preferably, the prepolymer may comprise 90 wt% to 98 wt% and the lithium salt may comprise 2 wt% to 10 wt% based on the total weight of the prepolymer solution. Preferably, the initiator may comprise from 0.4 wt% to 10 wt% based on the total weight of the prepolymer. Preferably, the prepolymer is an oligomer, such as polyethylene glycol diglycidyl ether. Also preferably, the prepolymer is a monomer, such as 1, 3-dioxolane or vinylene carbonate.

Specifically, under the condition that the organic solid electrolyte obtained subsequently further includes lithium salt and plasticizer, after the lithium salt, plasticizer and prepolymer can be mixed into a prepolymer solution, the prepolymer solution is dropped into the inorganic layer and coated or the inorganic layer is soaked into the prepolymer solution, so that the prepolymer solution is filled in the internal pores of the inorganic layer and distributed on the surface. Preferably, based on the total weight of the prepolymer solution, the prepolymer may be 45 wt% to 53 wt%, the lithium salt may be 2 wt% to 10 wt%, and the plasticizer may be 35 wt% to 45 wt%. Preferably, the prepolymer is a monomer, such as 1, 3-dioxolane or vinylene carbonate. Also preferably, the prepolymer is an oligomer, such as polyethylene glycol diglycidyl ether.

Specifically, under the condition that the organic solid electrolyte obtained subsequently further includes a lithium salt, a plasticizer and an initiator, after the lithium salt, the plasticizer, the initiator and the pre-polymer can be mixed into a pre-polymer solution, the pre-polymer solution is dripped into the inorganic layer and coated or the inorganic layer is soaked into the pre-polymer solution, so that the pre-polymer solution is filled in the internal pores of the inorganic layer and distributed on the surface. The initiator may initiate the reaction of the prepolymer to form the organic polymer. For example, the initiator may include common commercial thermal initiators, photoinitiators, or other lewis acids capable of initiating ring-opening polymerization of epoxy ethers. More by way of example, the initiator may include lithium hexafluorophosphate, lithium tetrafluoroborate, tin difluoride, trifluoroacetic acid, boron trifluoride, aluminum trifluoromethanesulfonate, magnesium trifluoromethanesulfonate, tin trifluoromethanesulfonate, bismuth trifluoromethanesulfonate, azobisisobutyronitrile, azobisisoheptonitrile, dimethyl azobisisobutyrate, benzoyl peroxide tert-butyl peroxide, benzophenone, 2-hydroxy-2-methyl-1-phenyl ketone, 1-hydroxy-cyclohexyl-1-phenyl ketone, 2-methyl-1- (4-methylthiophenyl) -2-morpholinyl-1-propanone, benzoin dimethyl ether, ethyl 4- (N, N-dimethylamino) benzoate, isopropylthioxanthone, 4-chlorobenzophenone, benzophenone trifluor, One or more of methyl o-benzoylbenzoate, 4-methylbenzophenone, 4-phenylbenzophenone and 4-methyl dimethyl acetone. Preferably, based on the total weight of the prepolymer solution, the prepolymer may be 45 wt% to 53 wt%, the lithium salt may be 2 wt% to 10 wt%, and the plasticizer may be 35 wt% to 45 wt%. Preferably, the initiator may comprise from 0.4 wt% to 10 wt% based on the total weight of the prepolymer. Preferably, the prepolymer is a monomer, such as 1, 3-dioxolane or vinylene carbonate. Also preferably, the prepolymer is an oligomer, such as polyethylene glycol diglycidyl ether.

Finally, the precursor is in-situ polymerized in the internal pores of the inorganic layer and on the surface of the inorganic layer to form an organic polymer, thereby obtaining an organic solid electrolyte filled in the internal pores of the inorganic layer and distributed on the surface of the inorganic layer and including the organic polymer.

Specifically, the in situ polymerization may be carried out by standing at room temperature, heating or irradiation with light. In general, the method and conditions for in situ polymerization may be determined depending on the type of prepolymer. For example, the heating temperature is 25 ℃ to 80 ℃.

In addition, an embodiment of the present invention provides a solid-state lithium battery, which includes a positive electrode, a negative electrode, and a solid-state electrolyte, wherein the solid-state electrolyte is the solid-state electrolyte composite membrane described above.

The main improvement of the solid-state lithium battery provided is that a new solid-state electrolyte is adopted, and the composition of the positive electrode and the negative electrode and the arrangement mode (connection mode) of the positive electrode, the negative electrode and the solid-state electrolyte can be the same as those in the prior art, and those skilled in the art can know that details are not described herein.

Example 1

Selecting LiOH. H₂O as a lithium source, La (OH)₃As a source of lanthanum, ZrO₂As a source of zirconium, Al₂O₃As an aluminum source. Respectively weighing LiOH & H according to stoichiometric ratio (the lithium source is excessive by 10-15 percent)₂O、La(OH)₃、ZrO₂、Al₂O₃. The four raw materials are moved into a zirconia ball milling tank, zirconia balls with the diameter of 10 mm (the weight ratio of the balls to the materials is 10: 1) are added, the rotating speed is set to be 400rpm/min, and ball milling is carried out for 10 hours. Transferring the mixed mixture powder into a magnesium oxide crucible, putting the magnesium oxide crucible into a box-type muffle furnace for calcination, keeping the calcination temperature at 950 ℃ and preserving the heat for 12 hours. And naturally cooling to obtain calcined product powder. And ball milling the calcined product powder under the following conditions: the medium is isopropanol, the diameter of a zirconia grinding ball is 3 mm (the ball material weight ratio is 10: 1), the set rotating speed is 400rpm/min, the ball milling time is 24 hours, then the ball milling ball is dried for 6 hours at 50 ℃, the obtained powder is ground by a mortar and sieved, and the Al-doped LLZO powder (Al-LLZO) is obtained.

0.3 g of a dispersant with a solid content of 45 percent is added into 100 g of deionized water to be fully stirred and dissolved, 96 g of the Al-LLZO powder is added, and the mixture is stirred at a high speed to form a LLZO dispersion liquid. Then, 17 g of a binder with a solid content of 30% was added, stirred uniformly, and finally a small amount of a surface wetting agent was added to form a solid electrolyte slurry.

And (3) selecting a wet-process porous base membrane with the thickness of 9 microns, coating the LLZO solid electrolyte slurry on one surface of the porous base membrane to the thickness of 3 microns, and drying through an oven to obtain the membrane coated with the LLZO layer.

After 5ml of 1, 3-dioxolane (about 5.3g) and 5ml of ethylene glycol dimethyl ether (about 4.3325g) were mixed uniformly, 0.72g of lithium bistrifluoromethanesulfonimide was added and dissolved with stirring, and then 0.076g of lithium hexafluorophosphate was weighed out and rapidly dissolved in the above solution to prepare a prepolymer solution of a polymer electrolyte.

And dripping the prepolymer solution on the membrane coated with the LLZO layer, fully wetting the membrane, penetrating into the internal pores of the LLZO layer and uniformly distributing on one surface of the LLZO layer, standing for 24 hours, and fully performing polymerization reaction on the prepolymer solution to obtain the composite diaphragm.

Example 2

Al-doped LLZO powder (Al-LLZO) and solid electrolyte slurry were prepared as in example 1.

After 10g of polyethylene glycol diglycidyl ether was weighed, 0.72g of lithium bistrifluoromethanesulfonimide was added, 0.076g of lithium hexafluorophosphate was slowly added thereto, and dissolved by stirring to prepare a prepolymer solution of a polymer electrolyte.

And dropwise adding the prepolymer solution to the membrane coated with the LLZO layer to fully wet the membrane, penetrating the membrane to the inner pores of the LLZO layer and uniformly distributing the membrane on one surface of the LLZO layer, and standing for 24 hours to enable the prepolymer solution to perform polymerization reaction, thereby obtaining the composite diaphragm.

Example 3

And (3) selecting a wet porous base membrane with the thickness of 9 microns, coating the LLZO solid electrolyte slurry on the two side surfaces of the porous base membrane, wherein the coating thickness is 1.5 microns respectively, and then drying the porous base membrane by an oven to obtain the membrane with the LLZO layer coated on the two sides.

The prepolymer solution was as in example 1.

And (3) dropwise adding the prepolymer solution to the membrane coated with the LLZO layer on two sides to fully wet the membrane, penetrating the membrane to the inner pores of the LLZO layer and uniformly distributing the membrane on one surface of the LLZO layer, and standing the membrane at room temperature for 24 hours to enable the prepolymer solution to perform polymerization reaction, thereby obtaining the composite diaphragm.

Example 4

Al-doped LLZO powder (Al-LLZO) was prepared as in example 1.

0.3 g of a dispersant having a solid content of 45% was added to 100 g of deionized water and sufficiently stirred to dissolve the dispersant, and 56 g of the Al-LLZO powder was added thereto and stirred at a high speed to form a LLZO dispersion. Then, 10g of a binder with a solid content of 30% is added, the mixture is uniformly stirred, and finally a small amount of a surface wetting agent is added to form the solid electrolyte slurry.

The polymer electrolyte prepolymer solution was prepared as in example 1.

Example 5

Mixing Li₃PO₄、Al₂O₃(200-300 mesh) TiO₂(40Nm) and (NH)₄)₂HPO₄Are mixed in stoichiometric proportions (Li)₃PO₄Excess 20 mol%). Ball-milling the mixture, zirconia balls and ethanol in a ball mill for 12 hours, wherein the mass ratio of the zirconia balls to the mixture to the ethanol is 3: 1: 0.6, the rotation speed of the planetary ball mill is 300 rpm/min. The mixed slurry was then heated in an oven at 70 ℃ until the ethanol was completely evaporated. Fully grinding the powder after evaporation to drynessAnd calcining the mixture for 10 hours at 900 ℃ in a muffle furnace at the heating rate of 3 ℃/min. And grinding the sintered powder, performing ball milling for 12 hours according to the proportion again, evaporating ethanol at 70 ℃ until the ethanol is completely dried, fully grinding and sieving to obtain LATP powder.

0.5 g of dispersant with the solid content of 37 percent is added into 100 g of deionized water to be fully stirred and dissolved, and then 85 g of LATP powder is added to be stirred at high speed to form LATP dispersion liquid. Then, 8.5 g of a binder having a solid content of 45% was added thereto, and the mixture was stirred uniformly to form a solid electrolyte slurry.

And (3) selecting a wet-process porous base membrane with the thickness of 9 microns, coating the solid electrolyte slurry on one surface of the porous base membrane to the thickness of 3 microns, and drying the porous base membrane through an oven to obtain the membrane coated with the LATP layer.

0.72g of LiTFSI was dissolved in 5ml of vinylene carbonate (VC, ca.6.8 g) with stirring, and then 0.033g of Azobisisobutyronitrile (AIBN) was added and dissolved with stirring to obtain a prepolymer solution.

And dropwise coating the precursor solution on one surface of the LATP layer, and heating at 60 ℃ for 5 hours to perform polymerization reaction on the precursor solution, thereby obtaining the composite diaphragm.

Example 6

The LATP powder and solid electrolyte slurry preparation process was as in example 5.

And (3) selecting a wet-process porous base membrane with the thickness of 9 micrometers, coating the solid electrolyte slurry on the two side surfaces of the porous base membrane with the coating thickness of 1.5 micrometers respectively, and drying the porous base membrane by using an oven to obtain the membrane with the two sides coated with the LATP layers.

The prepolymer solution was as in example 5.

And dropwise coating the precursor solution on the surface of the double-sided LATP layer, and heating at 60 ℃ for 5 hours to perform polymerization reaction on the precursor solution, thereby obtaining the composite diaphragm.

Example 7

0.11 g of a dispersant with a solid content of 45% was added to 100 g of deionized water and sufficiently stirred to dissolve, and 80 g of alumina powder was added thereto and stirred at a high speed to form a LLZO dispersion. And then, adding 14.4 g of a binder with the solid content of 42%, and uniformly stirring to obtain the alumina slurry.

And then, selecting a wet porous base membrane with the thickness of 9 microns, coating the alumina slurry on one surface of the porous base membrane with the coating thickness of 3 microns, and drying through an oven to obtain the membrane coated with the alumina layer.

The prepolymer solution was prepared as in example 1.

And dropwise coating the precursor solution on one surface of the alumina layer of the membrane, and standing at room temperature for 24 hours to perform polymerization reaction on the precursor solution, thereby obtaining the composite membrane.

Comparative example 1

Comparative example 2

Comparative example 3

The alumina slurry was prepared as in example 7.

Performance characterization analysis

And (3) characterizing the porosity of the coating: and intercepting the cross section of the sample, and acquiring the characteristic information of the microstructure of the interface of the sample by adopting a scanning electron microscope for photographing. The inorganic matter proportion of the organic/inorganic coating is estimated by software identification and fitting of the inorganic/organic bright-dark background contrast difference in the organic/inorganic coating of the cross section, so that the porosity of the coating is calculated. Referring to fig. 4 and 5, the cross-sections of the films of examples 1 and 4 are shown by scanning electron microscope, except for the base film, the inorganic electrolyte layer is formed on the base film, and the organic polymer is distributed in the inner pores of the inorganic electrolyte layer and on the inorganic electrolyte layer.

Ionic conductivity: assembling a diaphragm sample to be tested into a 2025 button cell, clamping the diaphragm between two stainless steel sheets, and dropwise adding a proper amount of electrolyte (LiPF with the molarity of 1M)₆Dissolved in EC/EMC/DMC 1:1:1 (vol%)) to fully wet the separator, forming an ion-blocked cell. And testing the cross-linking impedance spectrum by using an electrochemical workstation, fitting an impedance value according to a spectrogram result, and calculating according to a formula sigma L/(R multiplied by S) to obtain the ionic conductivity of the sample. Wherein L is the thickness of the sample, S is the area of the sample, and R is the resistance value.

And (3) stability characterization: the diaphragm is characterized by the Li-Cu half-cell cycle short-circuit time for lithium deposition stability, so that the regulation and control of the diaphragm on lithium deposition and the inhibition effect of lithium dendrite are reflected. Specifically, a diaphragm sample to be tested is assembled into a button cell, the diaphragm is clamped between a lithium sheet and a copper foil, the single-side coating diaphragm coating surface is opposite to the copper foil, and a proper amount of electrolyte (the mass molar concentration is 1M LiTFSI is dissolved in DOL/DME ═ 1:1 (vol%) and 1 wt% LiNO is dripped₃) The membrane is fully infiltrated. Testing the charge-discharge cycle stability of the battery by adopting a LAND battery charge-discharge instrument, and setting the constant current charge-discharge current density to be 0.25mA/cm²The time is 30 minutes, the charge cut-off voltage is 1V, and the time until the charge voltage is always lower than 0.05V is taken as the lithium dendrite short-circuit time t of the battery. As shown in FIGS. 6 (FIG. 7 is a partial enlarged view of the battery in the end of cycle short circuit in FIG. 6) and 8, which are graphs of the voltage and current of the Li-Cu half-cell with the diaphragm of comparative example 3 and example 1 as the separator, respectively, in the charge-discharge cycle at room temperature for different times, it can be seen that the Li-Cu half-cell assembled with the diaphragm of example 1 undergoes a long-time charge-discharge cycle (>3400 times), the stable electrical performance can be still provided, the short circuit condition of the diaphragm does not appear, and the cycle stability is far better than that of the comparative example 3<183 times), namely, the separator provided by the invention has excellent performanceThe lithium ion battery has the advantages of dendritic crystal resistance, lithium deposition regulation and control capability and better stability for an electrode, thereby having great potential in the aspects of improving the long-term cycle performance and safety of the battery.

The results of the above tests are listed in table 1 below:

the above matters related to the common general knowledge are not described in detail and can be understood by those skilled in the art.

The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. An inorganic/organic composite separator, characterized in that: the method comprises the following steps:

a base film;

an inorganic layer; and

an organic solid electrolyte;

the inorganic layer is formed on the base film and has internal pores, the organic solid electrolyte is filled in the internal pores of the inorganic layer and distributed on the surface of the inorganic layer, and the organic solid electrolyte comprises an organic polymer formed by in-situ polymerization reaction between the internal pores of the inorganic layer and the surface of the inorganic layer.

2. The inorganic/organic composite separator according to claim 1, characterized in that:

the organic polymer comprises one or more of polyethers, polycarbonates, polyvinylidene fluoride, polyurethanes, polyacrylonitriles, polyimides, polyacrylic acids and polyacrylic acid metal salts.

3. The inorganic/organic composite separator according to claim 2, characterized in that:

the basement membrane is a PE basement membrane or a PP basement membrane; and/or

The inorganic layer comprises one or more of an inorganic solid electrolyte, an inorganic ceramic, or a combination thereof; and/or

The inorganic layer has an internal porosity of less than 30%.

4. The inorganic/organic composite separator according to claim 3, characterized in that:

the inorganic solid electrolyte comprises one or more of oxide solid electrolyte and sulfide solid electrolyte, and the oxide solid electrolyte comprises lithium lanthanum zirconium oxygen, titanium aluminum lithium phosphate, garnet oxide LixLn₃M₂O₁₂Wherein Ln is La or Y, M is Zr, Nb, Sn, Sb, Te, Hf or Ta, x is between 3 and 7, and said sulfide solid electrolyte comprises a combination of one or more of LGPS, LPS, LPSCl, LSnPS, LSiPS, LGSiPS, LAlPS, LGS, LGZS, LSiS, LSAlS.

5. The inorganic/organic composite separator according to claim 3, characterized in that:

the inorganic solid electrolyte comprises one or more of garnet type conductive material, sulfide type conductive material, perovskite type conductive material, LiSiON type conductive material, LiPON type conductive material and Li3N type conductive material.

6. The inorganic/organic composite separator according to claim 3, characterized in that:

the inorganic ceramic comprises one or more of alumina, silica, metal oxide, metal nitride, metal phosphide, metal sulfide and metal boride.

7. The inorganic/organic composite separator according to claim 2, characterized in that:

the organic solid electrolyte further comprises a lithium salt; or

The organic solid electrolyte further comprises lithium salt and plasticizer.

8. The inorganic/organic composite separator according to claim 7, wherein:

the lithium salt comprises one or more of lithium hexafluorophosphate, lithium dioxalate borate, lithium bistrifluoromethanesulfonylimide, lithium bifluorosulfonylimide, lithium difluorooxalate borate and lithium tetrafluoroborate;

the plasticizer comprises one or more of propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, fluoroethylene carbonate, difluoroethylene carbonate, vinyl chloride, 1, 3-dioxolane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, 1, 3-propane sultone and succinonitrile.

9. A preparation method of an inorganic/organic composite diaphragm is characterized by comprising the following steps: the method comprises the following steps:

providing a base film;

forming an inorganic layer on the base film, the inorganic layer having internal pores;

filling a precursor in the internal pores of the inorganic layer and distributing the precursor on the surface of the inorganic layer; and

polymerizing the precursor in situ in the internal pores of the inorganic layer and on the surface of the inorganic layer to form an organic polymer, thereby obtaining an organic solid electrolyte filled in the internal pores of the inorganic layer and distributed on the surface of the inorganic layer and including the organic polymer.

10. The method for producing an inorganic/organic composite separator according to claim 9, wherein:

the in-situ polymerization is carried out by standing at room temperature, heating or illumination.

11. The method for producing an inorganic/organic composite separator according to claim 9, wherein:

the step of forming the inorganic layer includes:

and coating an inorganic slurry on the base film, and then drying to form an inorganic layer.

12. The method for producing an inorganic/organic composite separator according to claim 11, wherein:

the inorganic slurry comprises an inorganic solid electrolyte, one or more of inorganic ceramic, a solvent and a binder; or

The inorganic slurry comprises one or more of an inorganic solid electrolyte, an inorganic ceramic, a dispersant, a solvent, and a binder.

13. The method for producing an inorganic/organic composite separator according to claim 12, wherein:

the weight ratio of the combination of one or more of the inorganic solid electrolyte and the inorganic ceramic to the binder is 3: 1-25: 1.

14. the method for producing an inorganic/organic composite separator according to claim 12, wherein:

under the condition that the inorganic slurry comprises inorganic solid electrolyte, one or more combination of inorganic ceramic, solvent and binder, based on the total weight of the inorganic slurry, the solvent accounts for 40 wt% -65 wt%, the one or more combination of inorganic solid electrolyte and inorganic ceramic accounts for 30 wt% -50 wt%, and the binder accounts for 2 wt% -10 wt%;

under the condition that the inorganic slurry comprises inorganic solid electrolyte, one or more combinations of inorganic ceramics, a dispersant, a solvent and a binder, based on the total weight of the inorganic slurry, the solvent accounts for 40 wt% -65 wt%, the one or more combinations of inorganic solid electrolyte and inorganic ceramics accounts for 30 wt% -50 wt%, the dispersant accounts for 0.05 wt% -0.3 wt%, and the binder accounts for 2 wt% -10 wt%.

15. The method for producing an inorganic/organic composite separator according to claim 9, wherein:

the step of filling the pre-polymer comprises:

and dripping a precursor solution on the inorganic layer and coating or soaking the inorganic layer in the precursor solution to ensure that the precursor solution is filled in the internal pores of the inorganic layer and distributed on the surface of the inorganic layer.

16. The method for producing an inorganic/organic composite separator according to claim 9, wherein:

the prepolymer is a monomer or oligomer, and the monomer comprises a cyclic ether compound.

17. The method for producing an inorganic/organic composite separator according to claim 16, wherein:

the monomer comprises 1, 3-dioxolane or vinylene carbonate, and the oligomer comprises polyethylene glycol diglycidyl ether.

18. The method for producing an inorganic/organic composite separator according to claim 15, wherein:

the prepolymer solution comprises lithium salt and a prepolymer;

the prepolymer solution comprises a lithium salt, a prepolymer and an initiator;

the prepolymer solution comprises lithium salt, plasticizer and prepolymer; or

The prepolymer solution comprises a lithium salt, a plasticizer, a prepolymer and an initiator.

19. The method for producing an inorganic/organic composite separator according to claim 18, wherein:

under the condition that the prepolymer solution comprises lithium salt and prepolymer, the prepolymer accounts for 90-98 wt% and the lithium salt accounts for 2-10 wt% of the total weight of the prepolymer solution;

under the condition that the precursor solution comprises lithium salt, precursor and initiator, the precursor accounts for 90-98 wt% of the total weight of the precursor solution, the lithium salt accounts for 2-10 wt%, and the initiator accounts for 0.4-10 wt% of the total weight of the precursor solution;

under the condition that the precursor solution comprises lithium salt, plasticizer and precursor, based on the total weight of the precursor solution, the precursor accounts for 45-53 wt%, the lithium salt accounts for 2-10 wt%, and the plasticizer accounts for 35-45 wt%;

under the condition that the prepolymer solution comprises lithium salt, plasticizer, prepolymer and initiator, based on the total weight of the prepolymer solution, the prepolymer accounts for 45 wt% to 53 wt%, the lithium salt accounts for 2 wt% to 10 wt%, the plasticizer accounts for 35 wt% to 45 wt%, and based on the total weight of the prepolymer, the initiator accounts for 0.4 wt% to 10 wt%.