阅读说明：本技术 3d网络准固态电解质、准固态锂离子电池及其制备方法 (3D network quasi-solid electrolyte, quasi-solid lithium ion battery and preparation method thereof ) 是由 郑涛 刘婧 韩越 王磊 桑林 刘兴江 于 2021-09-03 设计创作，主要内容包括：本发明提供3D网络准固态电解质、准固态锂离子电池及其制备方法,包括：交联剂、聚合单体、锂盐、浸润剂以及引发剂；其中,所述锂盐的质量百分比30-60％,所述交联剂的质量百分比为0.1-1％,所述聚合单体的质量百分比为10-50％,所述浸润剂的质量百分比为10-50％,所述引发剂的质量百分比为0.01-0.1％。本发明的有益效果是准固态电池在一定程度上能够保证界面润湿,提高电池的安全性,并且准固态具有较高离子电导率,能够提高电池的电化学性能；3D网络准固态电解质具有较高的离子电导率,粘弹性较好,制备的固态锂离子电池具有较高的安全性,并且生产工艺易于实现。(The invention provides a 3D network quasi-solid electrolyte, a quasi-solid lithium ion battery and a preparation method thereof, wherein the preparation method comprises the following steps: a cross-linking agent, a polymerization monomer, a lithium salt, a wetting agent and an initiator; the lithium salt is 30-60% by mass, the cross-linking agent is 0.1-1% by mass, the polymerization monomer is 10-50% by mass, the impregnating compound is 10-50% by mass, and the initiator is 0.01-0.1% by mass. The quasi-solid battery has the beneficial effects that the quasi-solid battery can ensure the wetting of an interface to a certain extent, the safety of the battery is improved, and the quasi-solid battery has higher ionic conductivity and can improve the electrochemical performance of the battery; the 3D network quasi-solid electrolyte has high ionic conductivity and good viscoelasticity, and the prepared solid lithium ion battery has high safety and the production process is easy to realize.)

1. A3D network quasi-solid electrolyte, comprising: a cross-linking agent, a polymerization monomer, a lithium salt, a wetting agent and an initiator; the lithium salt is 30-60% by mass, the cross-linking agent is 0.1-1% by mass, the polymerization monomer is 10-50% by mass, the impregnating compound is 10-50% by mass, and the initiator is 0.01-0.1% by mass.

2. A 3D network quasi-solid electrolyte according to claim 1, wherein: the cross-linking agent is a multi-double-bond functional group monomer, preferably one or more of polyethylene glycol diacrylate, trihydroxy methyl propane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate and polyether polyacrylate; the comonomer is a compound with double bonds and epoxy bonds, and is preferably one or more of tetrahydrofuran acrylate, tetrahydrofuran methacrylate, 4-hydroxybutyl acrylate glycidyl ether, allyl glycidyl ether, glycidyl acrylate, 3, 4-epoxyhexyl methacrylate and glycidyl methacrylate.

3. A 3D network quasi-solid electrolyte according to claim 1 or 2, characterized in that: the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bistrifluoromethylsulfonyl imide, lithium bistrifluorosulfonimide, lithium difluorooxalate borate and lithium dioxalate borate, and plays a role in ring-opening in-situ polymerization of monomer epoxy.

4. A 3D network quasi-solid electrolyte according to any one of claims 1-3, wherein: the initiator is a double-bond initiator, preferably one of dibenzoyl oxide, dilauroyl peroxide, tert-butyl peroxy-2-ethylhexanoate and azobisisobutyronitrile;

the impregnating compound is one or more of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, fluoro-carbonate, adiponitrile, low molecular weight polymers and the like.

5. A method of preparing the 3D network quasi-solid electrolyte of claim 1, wherein: and sequentially mixing the cross-linking agent, the polymerization monomer, the lithium salt, the impregnating compound and the initiator to obtain a mixed solution after uniform mixing, and carrying out two-step in-situ polymerization on the mixed solution at a certain temperature to obtain the quasi-solid electrolyte.

6. The method for preparing a 3D network quasi-solid electrolyte according to claim 5, wherein: and in the step of mixing the cross-linking agent, the polymerized monomer, the lithium salt, the impregnating compound and the initiator in sequence for 3-5 hours to obtain the mixed solution, and then carrying out in-situ polymerization on the mixed solution for 12-36 hours at the temperature of 45-70 ℃ to obtain the quasi-solid electrolyte.

7. A quasi-solid lithium ion battery comprising the 3D network quasi-solid electrolyte of claim 1, wherein: the quasi-solid lithium ion battery comprises a positive plate prepared from a positive active material, a diaphragm, a negative plate prepared from a negative active material, and the quasi-solid electrolyte.

8. The quasi-solid state lithium ion battery of claim 7, wherein: the positive active material includes, but is not limited to, NCA, NCM523, NCM622, NCM811, Cr_xO_y、LiFePO₄One of lithium-rich manganese base and sulfur;

the negative active material is one or more of graphite, silicon monoxide, lithium metal, lithium aluminum alloy, lithium silicon alloy and lithium boron alloy;

the diaphragm is selected from one of a polyethylene diaphragm, a polyimide diaphragm, a polytetrafluoroethylene diaphragm, a non-woven fabric diaphragm and a polyethylene terephthalate diaphragm which are coated or embedded with oxide electrolyte.

9. The quasi-solid state lithium ion battery of claim 8, wherein: the oxide electrolyte is selected from one of LATP, LAGP and LLZO.

10. A method of making the quasi-solid state lithium ion battery of claim 7, wherein: the positive plate, the diaphragm and the negative plate are stacked by using a lamination process to prepare a dry battery cell, and then the quasi-solid electrolyte is injected into the dry battery cell and prepared by adopting a process of injecting liquid firstly and then carrying out in-situ polymerization.

Technical Field

The invention belongs to the technical field of solid-state batteries, and particularly relates to a preparation method of a 3D network quasi-solid-state electrolyte and a quasi-solid-state lithium ion battery.

Background

With the rapid development of new energy industry, the energy density of the lithium ion battery is also greatly improved, and the development of the lithium ion battery is also troubled by the following safety problem. The existing lithium ion battery adopts liquid electrolyte, so that the dangers of liquid leakage, burning and the like are easy to occur in the using process, and the use safety is seriously influenced.

The solid-state battery developed by adopting the solid-state electrolyte to replace the organic electrolyte in the traditional lithium ion battery can well relieve the safety problem of the battery and can break through the glass ceiling with energy density. However, the interface contact between the solid electrolyte and the pole piece is poor, no effective lithium ion conduction element exists among the particles in the pole piece, the interface transmission of lithium ions is seriously influenced, and the ionic conductivity of most solid electrolyte systems is low at normal temperature, so that the use range of the solid battery is reduced.

Disclosure of Invention

The invention aims to solve the problems that a 3D network quasi-solid electrolyte, a quasi-solid lithium ion battery and a preparation method thereof are provided, the 3D network prepared in double in-situ is utilized to effectively solve the problems that the safety performance of high energy density is poor, the interface contact between the solid electrolyte and a pole piece is poor, no effective lithium ion conduction element exists among particles in the pole piece, the interface transmission of lithium ions is seriously influenced, the ionic conductivity of most solid electrolyte systems is low at normal temperature, and the use interval of the solid battery is reduced.

In order to solve the technical problems, the invention adopts the technical scheme that: A3D network quasi-solid electrolyte, comprising: a cross-linking agent, a polymerization monomer, a lithium salt, a wetting agent and an initiator; the lithium salt is 30-60% by mass, the cross-linking agent is 0.1-1% by mass, the polymerization monomer is 10-50% by mass, the impregnating compound is 10-50% by mass, and the initiator is 0.01-0.1% by mass.

Preferably, the cross-linking agent is a multi-double-bond functional group monomer, and is preferably one or more of polyethylene glycol diacrylate, trihydroxy methyl propane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate and polyether polyacrylate; the comonomer is a compound with double bonds and epoxy bonds, and is preferably one or more of tetrahydrofuran acrylate, tetrahydrofuran methacrylate, 4-hydroxybutyl acrylate glycidyl ether, allyl glycidyl ether, glycidyl acrylate, 3, 4-epoxyhexyl methacrylate and glycidyl methacrylate.

Preferably, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bistrifluoromethylsulfonyl imide, lithium bistrifluorosulfonimide, lithium difluorooxalato borate and lithium dioxalate borate, and plays a role in ring-opening in-situ polymerization of monomer epoxy.

Preferably, the initiator is a double-bond initiator, preferably one of dibenzoyl oxide, dilauroyl peroxide, tert-butyl peroxy-2-ethylhexanoate and azobisisobutyronitrile;

the impregnating compound is one or more of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, fluoro-carbonate, adiponitrile, low molecular weight polymers and the like.

A method of preparing the 3D network quasi-solid electrolyte of claim 1, wherein: and sequentially mixing the cross-linking agent, the polymerization monomer, the lithium salt, the impregnating compound and the initiator to obtain a mixed solution after uniform mixing, and carrying out in-situ polymerization on the mixed solution at a certain temperature to obtain the quasi-solid electrolyte.

Preferably, in the step of sequentially mixing the cross-linking agent, the polymerized monomer, the lithium salt, the impregnating compound and the initiator, the mixing time is 3-5 hours, so as to obtain the mixed solution, and then the mixed solution is subjected to in-situ polymerization for 12-36 hours at the temperature of 45-70 ℃, so as to obtain the quasi-solid electrolyte.

In a quasi-solid lithium ion battery comprising the 3D network quasi-solid electrolyte of claim 1, wherein: the quasi-solid lithium ion battery comprises a positive plate prepared from a positive active material, a diaphragm, a negative plate prepared from a negative active material, and the quasi-solid electrolyte.

Preferably, the positive active material includes, but is not limited to, NCA, NCM523, NCM622, NCM811, Cr_xO_y、LiFePO₄One of lithium-rich manganese base and sulfur;

the negative active material is one or more of graphite, silicon monoxide, lithium metal, lithium aluminum alloy, lithium silicon alloy and lithium boron alloy;

the diaphragm is selected from one of a polyethylene diaphragm, a polyimide diaphragm, a polytetrafluoroethylene diaphragm, a non-woven fabric diaphragm and a polyethylene terephthalate diaphragm which are coated or embedded with oxide electrolyte.

Preferably, the oxide electrolyte is selected from one of LATP, LAGP, LLZO.

A method of making the quasi-solid state lithium ion battery of claim 7, wherein: the positive plate, the diaphragm and the negative plate are stacked by using a lamination process to prepare a dry cell, and then the quasi-solid electrolyte is injected into the dry cell, wherein the quasi-solid electrolyte is prepared by adopting a process of injecting liquid firstly and then carrying out in-situ polymerization.

By adopting the technical scheme, the quasi-solid battery is in an intermediate form in the process of transferring the liquid lithium ion battery to the solid battery, the interface wetting can be ensured to a certain extent, the safety of the battery is improved, and the quasi-solid battery has higher ionic conductivity and can improve the electrochemical performance of the battery.

The 3D network quasi-solid electrolyte and the quasi-solid lithium ion battery are prepared by two types of synchronous in-situ polymerization methods, the 3D network quasi-solid electrolyte prepared by the method has high ionic conductivity and good viscoelasticity, the prepared solid lithium ion battery has high safety, and the production process is easy to realize.

Drawings

FIG. 1 is a cycle curve of a quasi-solid lithium ion battery according to an embodiment of the present invention at 0.33C magnification

Detailed Description

The invention is further illustrated by the following examples and figures:

A3D network quasi-solid electrolyte, comprising: a cross-linking agent, a polymerization monomer, a lithium salt, a wetting agent and an initiator; wherein, the mass percent of the lithium salt is 30-60%, the mass percent of the cross-linking agent is 0.1-1%, the mass percent of the polymerization monomer is 10-50%, the mass percent of the impregnating compound is 10-50%, and the mass percent of the initiating agent is 0.01-0.1%. Wherein the content of the first and second substances,

the cross-linking agent is a multi-double-bond functional group monomer, and preferably is one or more of polyethylene glycol diacrylate, trihydroxy methyl propane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate and polyether polyacrylate.

The comonomer is a compound with double bonds and epoxy bonds, and is preferably one or more of tetrahydrofuran acrylate, tetrahydrofuran methacrylate, 4-hydroxybutyl acrylate glycidyl ether, allyl glycidyl ether, glycidyl acrylate, 3, 4-epoxyhexyl methacrylate and glycidyl methacrylate.

The lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bistrifluoromethylsulfonyl imide, lithium bistrifluorosulfonimide, lithium difluorooxalate borate and lithium dioxalate borate, and the lithium salt plays a role in ring-opening in-situ polymerization of the monomer epoxy.

The initiator is a double-bond initiator, preferably one of dibenzoyl oxide, dilauroyl peroxide, tert-butyl peroxy-2-ethylhexanoate and azobisisobutyronitrile.

The impregnating compound is one or more of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, fluoro-carbonate, adiponitrile, low molecular weight polymers and the like.

A method of preparing a 3D network quasi-solid electrolyte: the preparation method comprises the following steps of sequentially mixing a cross-linking agent, a polymerization monomer, lithium salt, a wetting agent and an initiator to obtain a mixed solution after uniform mixing, and carrying out in-situ polymerization on the mixed solution at a certain temperature to obtain the quasi-solid electrolyte.

And in the step of mixing the cross-linking agent, the polymerized monomer, the lithium salt, the impregnating compound and the initiator in sequence for 3-5 hours to obtain the mixed solution, and then carrying out in-situ polymerization on the mixed solution for 12-36 hours at the temperature of 45-70 ℃ to obtain the quasi-solid electrolyte.

In a quasi-solid lithium ion battery comprising a 3D network quasi-solid electrolyte: the quasi-solid lithium ion battery comprises a positive plate prepared from a positive active material, a diaphragm, a negative plate prepared from a negative active material and a quasi-solid electrolyte.

Positive active materials include, but are not limited to, NCA, NCM523, NCM622, NCM811, Cr_xO_y、LiFePO₄One of lithium-rich manganese base and sulfur;

the negative active material is one or more of graphite, silicon monoxide, lithium metal, lithium aluminum alloy, lithium silicon alloy and lithium boron alloy;

the diaphragm is selected from one of polyethylene diaphragm, polyimide diaphragm, polytetrafluoroethylene diaphragm, non-woven fabric diaphragm and polyethylene terephthalate diaphragm coated or embedded with oxide electrolyte.

The oxide electrolyte is selected from one of LATP, LAGP and LLZO.

A method for preparing a quasi-solid state lithium ion battery comprises the following steps: the positive plate, the diaphragm and the negative plate are superposed by using a lamination process to prepare a dry cell, and then the quasi-solid electrolyte is injected into the positive and dry cell, wherein the quasi-solid electrolyte is prepared by adopting a process of injecting liquid firstly and then carrying out in-situ polymerization, namely, a cross-linking agent, a polymerization monomer, a lithium salt, a wetting agent and an initiator are uniformly mixed and then injected between the positive plate and the negative plate, standing is carried out for 18-30h, and then in-situ polymerization is carried out for 12-36h under the environment of the temperature of 45-70 ℃ to obtain the quasi-solid battery.

Several specific examples are listed below:

example 1

Adding carbon nanotubes and graphene into a PVDF NMP solution, uniformly mixing, then adding a positive electrode active substance NCM811 with the mass concentration of 97.4%, stirring the above materials for 2-8h, and fully mixing to prepare a slurry. And (3) coating the slurry on two sides of the aluminum foil after 10um, performing forced air drying at 85 ℃ for 20 hours, and then preparing the positive plate through a sheet punching process.

Adding carbon nano tubes and carbon black into a CMC aqueous solution, uniformly mixing, then adding negative active substances graphite and silicon monoxide, wherein the mass concentration of the graphite and the silicon oxide is 95%, stirring the materials for 4 hours to fully mix, then adding the rest CMC, stirring for 1 hour, adjusting the viscosity, then adding SBR, and uniformly mixing. And coating the slurry on two sides of a copper foil of 6um, drying, and then preparing the negative plate through a punching process.

Preparation of 3D network quasi-solid electrolyte 1: 0.75g of lithium hexafluorophosphate, 0.25g of lithium bis (fluorosulfonyl) imide, 0.05g of bis (pentaerythritol) tetraacrylate and 0.0016g of azobisisobutyronitrile are weighed and added into a mixed solution of 0.2g of tetrahydrofuran acrylate and 0.7g of ethylene carbonate and fluoroethylene carbonate, stirred for 4h, then coated on a polyimide diaphragm coated with a LLZO electrolyte, heated at 60 ℃ for 24h to prepare a 3D network quasi-solid electrolyte 1, then the impedance of the 3D network quasi-solid electrolyte 1 is measured by adopting alternating current impedance, and the ionic conductivity of the 3D network quasi-solid electrolyte is calculated according to a conductivity formula, wherein the ionic conductivity is 5.7 multiplied by 10, and the ionic conductivity is 5.7 multiplied by 10^-4S/cm。

Preparing a quasi-solid battery from the positive plate, the diaphragm and the negative plate by adopting a lamination preparation process, injecting the 3D network quasi-solid electrolyte 1 into the dry battery core, standing for 24h, and curing for 24h at 60 ℃ to obtain the quasi-solid battery.

Example 2

The preparation of the positive and negative electrode sheets was the same as in example 1 and will not be described herein.

Preparing a 3D network quasi-solid electrolyte 2: 0.75g of lithium hexafluorophosphate, 0.25g of lithium bis (fluorosulfonyl) imide, 0.05g of bis (pentaerythritol) tetraacrylate and 0.0016g of azobisisobutyronitrile are weighed and added into a mixed solution of 0.2g of glycidyl methacrylate and 0.7g of ethylene carbonate and fluoroethylene carbonate, stirred for 4h, then coated on a polyimide diaphragm coated with a LLZO electrolyte, heated at 60 ℃ for 24h to prepare a 3D network quasi-solid electrolyte 2, then the impedance of the 3D network quasi-solid electrolyte 2 is measured by adopting alternating current impedance, and the ionic conductivity of the 3D network quasi-solid electrolyte is calculated according to a conductivity formula, wherein the ionic conductivity is 6.3 multiplied by 10, and the ionic conductivity is 6.3 multiplied by 10^-4S/cm。

Preparing a quasi-solid battery from the positive plate, the diaphragm and the negative plate by adopting a lamination preparation process, injecting the 3D network quasi-solid electrolyte 2 into the dry battery core, standing for 24h, and curing for 24h at 60 ℃ to obtain the quasi-solid battery.

Example 3

The preparation of the positive and negative electrode sheets was the same as in example 1 and will not be described herein.

Preparation of 3D network quasi-solid electrolyte 3: 0.75g of lithium hexafluorophosphate, 0.25g of lithium bis (fluorosulfonyl) imide, 0.05g of bis (pentaerythritol) tetraacrylate and 0.0016g of azobisisobutyronitrile are weighed and added into a mixed solution of 0.4g of tetrahydrofuran acrylate and 0.7g of ethylene carbonate and fluoroethylene carbonate, stirred for 4h, then coated on a polyimide diaphragm coated with a LLZO electrolyte, heated at 60 ℃ for 24h to prepare a 3D network quasi-solid electrolyte 3, then the impedance of the 3D network quasi-solid electrolyte 3 is measured by adopting alternating current impedance, and the ionic conductivity of the 3D network quasi-solid electrolyte 3 is calculated according to a conductivity formula, wherein the ionic conductivity is 4.1 multiplied by 10, and the ionic conductivity is 4.1 multiplied by 10^-4S/cm。

Preparing a quasi-solid battery by adopting a lamination preparation process for the positive plate, the diaphragm and the negative plate, injecting the 3D network quasi-solid electrolyte 3 into the dry battery core, standing for 24h, and curing for 24h at 60 ℃ to obtain the quasi-solid battery.

Example 4

The preparation of the positive and negative electrode sheets was the same as in example 1 and will not be described herein.

Preparing a 3D network quasi-solid electrolyte 4: weighing 0.5g of lithium hexafluorophosphate, 0.15g of lithium bis (fluorosulfonyl) imide, 0.15g of lithium bis (trifluoromethanesulfonyl) imide, 0.05g of pentaerythritol tetraacrylate and 0.0016g of azobisisobutyronitrile, adding the mixture into a mixed solution of 0.2g of tetrahydrofuran acrylate and 0.7g of ethylene carbonate and fluoroethylene carbonate, stirring for 4 hours, coating the mixed solution on a polyimide diaphragm coated with a LLZO electrolyte, heating for 24 hours at 60 ℃ to prepare a 3D network quasi-solid electrolyte 4, measuring the impedance of the 3D network quasi-solid electrolyte 4 by adopting alternating current impedance, and calculating the ionic conductivity of the 3D network quasi-solid electrolyte 4 according to a conductivity formula, wherein the ionic conductivity is 6.1 multiplied by 10, and the ionic conductivity is 6.1 multiplied by 10^-4S/cm。

Preparing a quasi-solid battery from the positive plate, the diaphragm and the negative plate by adopting a lamination preparation process, injecting the 3D network quasi-solid electrolyte 4 into the dry battery core, standing for 24h, and curing for 24h at 60 ℃ to obtain the quasi-solid battery.

As shown in fig. 1, a circulation curve of a quasi-solid-state lithium ion battery with a magnification of 0.33C, the quasi-solid-state lithium ion battery prepared by the technical scheme has good circulation performance at normal temperature, and has high safety, and the production process is easy to implement and is suitable for mass production.

The embodiments of the present invention have been described in detail, but the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.