CN112018427A - Gel polymer battery and preparation method thereof - Google Patents

Gel polymer battery and preparation method thereof Download PDF

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Publication number
CN112018427A
CN112018427A CN201910449710.5A CN201910449710A CN112018427A CN 112018427 A CN112018427 A CN 112018427A CN 201910449710 A CN201910449710 A CN 201910449710A CN 112018427 A CN112018427 A CN 112018427A
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gel polymer
ether
carbonate
electrolyte
battery
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李静
郭姿珠
马永军
吴荣方
陈嵩
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BYD Co Ltd
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BYD Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0065—Solid electrolytes
    • H01M2300/0082—Organic polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0085—Immobilising or gelification of electrolyte
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The invention provides a gel polymer battery which comprises a positive electrode, a negative electrode and a gel polymer electrolyte, wherein the positive electrode is made of a material with voltage larger than 3.5V, the negative electrode is made of metal lithium, the gel polymer electrolyte is of a laminated structure and comprises an ether gel polymer electrolyte layer and a carbonate gel polymer electrolyte layer, the ether gel polymer electrolyte layer is close to one side of the negative electrode, and the carbonate polymer electrolyte layer is close to one side of the positive electrode. The gel polymer electrolyte contains the ether and carbonate gel electrolyte, so that the gel polymer electrolyte can be used in a battery system with a metal lithium as a negative electrode and a high-voltage material as a positive electrode, the energy density of the battery is greatly improved, and the safety performance of the battery is also greatly improved by using the gel polymer electrolyte.

Description

Gel polymer battery and preparation method thereof
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a gel polymer battery and a preparation method thereof.
Background
Lithium ion batteries have the advantages of high energy density, good cycle performance, small size and the like, and are widely applied, so that along with the development of lithium batteries, people put forward higher and higher requirements on the safety performance, the capacity and the like of the batteries. The existing lithium ion battery mostly adopts liquid organic electrolyte, and because the battery contains volatile and flammable organic solvent, the safety problems of liquid leakage, air blowing, combustion and the like are difficult to avoid, so that the safety performance of the battery can be well improved by adopting safer gel electrolyte to replace the liquid organic electrolyte, and compared with solid electrolyte, gel polymer electrolyte has higher ionic conductivity and can ensure good battery cycle performance. The electrode potential of the metal lithium is most negative, and the metal lithium is used as a battery cathode to improve the energy density of the battery and is an ideal cathode material; the ternary anode material has higher voltage and higher specific capacity, so that the requirement of people on higher battery capacity can be met by adopting the ternary material as the anode and the metal lithium as the cathode. However, the carbonate electrolyte with high voltage commonly used at present is not well compatible with the metal lithium cathode, and the carbonate electrolyte with high voltage is in contact with the metal lithium and reacts with the metal lithium to cause bad influence on the battery. Therefore, other proper electrolyte needs to be matched in the battery system, so that the battery capacity can be expected to be improved, and meanwhile, the safety performance of the battery can be improved.
Disclosure of Invention
The invention provides a gel polymer battery and a preparation method thereof, aiming at solving the technical problems that a battery system assembled by a lithium metal cathode and a high-voltage cathode material has no proper electrolyte and the battery safety hidden trouble exists by adopting liquid electrolyte in the prior art.
In order to achieve the above object, in a first aspect, the present invention provides a gel polymer battery, including a positive electrode, a negative electrode and a gel polymer electrolyte, wherein the positive electrode is made of a material with a voltage greater than 3.5V, the negative electrode is made of lithium metal, the gel polymer electrolyte is a layered structure, and includes an ether gel polymer electrolyte layer and a carbonate gel polymer electrolyte layer, the ether gel polymer electrolyte layer is close to one side of the negative electrode, and the carbonate gel polymer electrolyte layer is close to one side of the positive electrode.
Compared with the existing gel polymer battery, the gel polymer battery provided by the invention has the advantages that the adopted electrolyte is a composite electrolyte obtained by laminating the ether gel polymer electrolyte and the carbonate gel polymer electrolyte, the ether and carbonate gel polymer electrolytes can stably exist and do not have the phenomenon of mutual permeation, the properties of the ether and carbonate gel polymer electrolytes are kept, namely the ether gel polymer electrolyte can stably exist with the metal lithium, the metal lithium is protected, the metal lithium is prevented from being excessively consumed, the stability and the safety of the battery based on the metal lithium cathode are improved, and the carbonate gel polymer electrolyte can be matched with a high-voltage anode material. Based on the above, the gel polymer battery can adopt metal lithium as a negative electrode and a high-voltage material such as ternary lithium cobaltate as a positive electrode, so that a battery with high energy density can be obtained. In addition, compared with a liquid electrolyte battery system, the gel polymer battery provided by the invention has higher safety performance, and because the gel polymer electrolyte does not contain a flowing organic solvent, potential safety hazards such as liquid leakage, air blowing and the like in the production, transportation and use processes can be avoided, and the safety performance of the battery can be effectively improved. Moreover, the gel polymer electrolyte can inhibit the growth of lithium dendrites to a certain extent, and compared with an inorganic solid electrolyte, the gel polymer electrolyte has better interface compatibility with a positive electrode and a negative electrode, is beneficial to the transmission of lithium ions and improves the performance of a battery; and the gel polymer electrolyte has strong plasticity of shape and size, and can be suitable for batteries with different shapes and sizes.
In a second aspect, the present invention provides a method for preparing a gel polymer battery as described above, comprising the steps of:
(1) preparing an ether electrolyte containing an ether organic solvent, a lithium salt, a polymer monomer and an initiator: preparing a carbonate electrolyte containing a carbonate organic solvent, a lithium salt, a polymer monomer and an initiator;
(2) preparing a semi-finished battery from the negative electrode, the positive electrode, the ether electrolyte and the carbonate electrolyte in the step (1);
(3) and (3) placing the semi-finished product battery obtained in the step (2) in an oven to obtain the gel polymer battery.
The preparation method of the gel polymer battery provided by the invention is not a method of firstly preparing the polymer electrolyte layer and then assembling the battery in the prior art, but adopts an in-situ polymerization method, namely when the electrolyte solution is not polymerized to generate the gel electrolyte, the gel electrolyte is assembled into the battery and the polymerization reaction is generated in the battery. Compared with the scheme of obtaining the polymer electrolyte layer by polymerization, the scheme of in-situ polymerization provided by the invention ensures that the gel polymer electrolyte layer has better contact with the positive electrode and the negative electrode, thereby reducing the interface impedance in the battery, and being beneficial to the transmission of lithium ions and the improvement of the battery performance; meanwhile, the in-situ polymerization method omits the extraction of pore-forming agent in the polymer film-forming process in the traditional technology, greatly simplifies the process flow, reduces the requirements on equipment, and simultaneously reduces the use of organic solvent which pollutes the environment.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects solved by the present invention more apparent, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In a first aspect, the invention provides a gel polymer battery, which comprises a positive electrode, a negative electrode and a gel polymer electrolyte, wherein the positive electrode is made of a material with a voltage of more than 3.5V, the negative electrode is made of metal lithium, the gel polymer electrolyte is of a laminated structure and comprises an ether gel polymer electrolyte layer and a carbonate gel polymer electrolyte layer, the ether gel polymer electrolyte layer is close to one side of the negative electrode, and the carbonate polymer electrolyte layer is close to one side of the positive electrode.
The lithium metal has the lowest electrode potential and is an ideal battery cathode material, however, the carbonate electrolyte commonly used at present cannot be compatible with the lithium metal, and can generate side reaction with the lithium metal to influence the battery performance; the ether electrolyte is difficult to reduce, and can stably exist with metallic lithium, so that the ether electrolyte is used as a battery system of a lithium negative electrode. However, the ether electrolyte has a low oxidation potential and cannot be used in a battery system in which a high-voltage material such as a ternary material or a lithium cobaltate material is used as a positive electrode, and even if lithium is used for a negative electrode, the energy density of the battery cannot be improved because the potential of the positive electrode material is low. The carbonate electrolyte has higher oxidation potential and can be matched with a high-voltage anode material for use. Therefore, in order to improve the energy density of the battery, high-voltage materials such as ternary materials, lithium cobaltate materials and the like are required to be used as the anode, and metal lithium is required to be used as the cathode, so that the used electrolyte can be matched with the metal lithium and the high-voltage materials such as the ternary materials, the lithium cobaltate materials and the like, and the requirement of the high energy density of the battery can be met.
The gel polymer electrolyte adopted by the gel polymer battery provided by the invention contains the ether gel polymer electrolyte and the carbonate gel polymer electrolyte at the same time, and is of a layered structure, the two polymer electrolytes can exist independently, so that the ether polymer electrolyte can be used on one side of a lithium metal negative electrode, the carbonate polymer electrolyte can be used on one side of a high-voltage positive electrode material, and the two polymer electrolytes can exist stably, the phenomenon of mutual dissolution and other structure damage can not occur, the assembly of the battery with metal lithium as the negative electrode and the high-voltage material as the positive electrode can be realized, and the energy density of the battery can be further improved. In addition, the gel electrolyte has higher safety compared with a liquid organic electrolyte, thereby improving the safety performance of the battery. Moreover, the plasticity of the gel polymer electrolyte enables the gel polymer electrolyte to be suitable for batteries with different shapes, and the application range is wide.
In one embodiment, the positive electrode is one or more of a lithium cobaltate material or a ternary material.
In one embodiment, the ternary material is LiNi1-x-yCoxMnyO2Wherein x is more than or equal to 0.1 and less than or equal to 0.4, y is more than or equal to 0.2 and less than or equal to 0.5, preferably, the ternary material can be selected from NCM111 (namely of Ni, Co and Mn elements)The molar ratio is 1:1: 1), NCM622, NCM 523.
In one embodiment, the thickness ratio of the ether gel polymer electrolyte layer to the carbonate gel polymer electrolyte layer is 1:2 to 2: 1.
When the thickness ratio of the two is lower than 1:2, namely the ether gel polymer electrolyte layer is thin and is not enough to protect the metal lithium negative electrode, so that the metal lithium negative electrode can be influenced by the carbonate electrolyte; when the ratio of the two is higher than 2:1, namely the carbonate gel polymer electrolyte layer is thin, the polymer electrolyte layer is not high enough to resist high voltage, so that the polymer electrolyte layer cannot be well matched with a high-voltage anode material. Therefore, the gel polymer electrolyte within the proportion range can be used in a battery system assembled by a lithium metal cathode and a high-voltage anode material, thereby being beneficial to improving the energy density of the battery.
In one embodiment, the ether gel polymer electrolyte layer has a thickness of 5 to 10 μm.
The ether gel polymer electrolyte layer within the thickness range can protect the lithium metal cathode from being influenced by the carbonate electrolyte; and the whole gel polymer electrolyte layer is not too thick, because the electrolyte layer is thick, the transmission path of lithium ions in the battery is increased, the multiplying power performance of the battery is influenced, the whole thickness and the volume of the battery are increased, and the volume energy density of the battery is reduced.
In one embodiment, the ether gel polymer electrolyte layer is prepared from an ether organic solvent, a lithium salt, a polymer monomer and an initiator, and the number of moles of the lithium salt is the same as that of the ether organic solvent in a unit volume; the carbonate gel polymer electrolyte layer is prepared from a carbonate organic solvent, a lithium salt, a polymer monomer and an initiator, wherein the mole number of the lithium salt is the same as that of the carbonate organic solvent in unit volume.
In order to match the gel polymer electrolyte with both metallic lithium and high-voltage positive electrode materials, the gel polymer electrolyte needs to contain both an ether electrolyte stable to metallic lithium and a carbonate electrolyte stable to high-voltage positive electrode materials, and the two electrolytes need to be independent and immiscible. The gel polyelectrolyte is formed in situ in the preparation of the battery, namely, the gel polyelectrolyte is polymerized after the battery is assembled, so that the gel polyelectrolyte layer has better contact with the positive electrode and the negative electrode, and the internal interface impedance of the battery is lower. Therefore, when the solution is prepared, the number of moles of the lithium salt per unit volume is the same as the number of moles of the organic solvent, and the molar ratio is 1:1, so that the solvent molecules are fixed and do not move, that is, when the ether electrolyte is in contact with the carbonate electrolyte, the solvent molecules do not move, and even if the solvent molecules are not polymerized into a gel state, the two-layer structure can be maintained. If the number of moles of the lithium salt is not equal to the number of moles of the organic solvent, that is, the number of moles of the lithium salt is less than or more than the number of moles of the organic solvent, solvent molecules cannot be well locked and immobilized by the lithium salt, so that mutual permeation between ether organic solvent molecules and carbonate organic solvent molecules occurs, and the layered structure is damaged.
The amount of the lithium salt to be added is determined according to the amount of the organic solvent, and since the number of moles of the lithium salt is the same as the number of moles of the organic solvent, the number of moles of the organic solvent can be estimated from the amount of the organic solvent used, and the number of moles of the lithium salt to be added can be known, and the concentration of the lithium salt can be known.
In one embodiment, the mass percentage of the polymer monomer is 1-20%, and the mass percentage of the initiator is 0.5-10%.
If the polymer monomer ratio is too low, i.e., less than 1%, it may be difficult to form a complete gel polymer electrolyte; if the content of the polymer monomer is too high, i.e., more than 20%, the solid content of the gel polymer electrolyte is caused to be high, thereby affecting the ionic conductivity of the gel polymer electrolyte. If the mass ratio of the initiator is less than 0.5%, it is difficult to initiate polymerization, and if it is more than 10%, it is disadvantageous to form a complete gel.
In one embodiment, the ether organic solvent is one or more of dimethyl ether, 1, 3-dioxolane, dipropylene glycol propyl ether, and tetraethylene glycol dimethyl ether.
In one embodiment, the carbonate organic solvent is one or more of ethylene carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate.
In one embodiment, the lithium salt is LiTFSI, LiFSI, LiBOB, LiDOFB, LiPF6，LiBF4One or more of them.
In one embodiment, the polymer monomer is one or more of polyethylene glycol diglycidyl ether, propylene oxide, diglycidyl ether and glycidyl methyl ether; the initiator is LiPF6，LiBF4One kind of (1).
The combination of the polymer monomer and the initiator can cause polymerization reaction between the polymer monomers, thereby obtaining the gel-like polymer electrolyte.
In one embodiment, the polymer monomer is one or more of 2-phenoxyethyl acrylate, triethylene glycol dimethacrylate, polyethylene glycol monomethyl ether methacrylate, ethylene glycol diacrylate and ethoxylated trimethylolpropane triacrylate; the initiator is one of azodiisobutyronitrile and dibenzoyl peroxide.
The combination of the polymer monomer and the initiator is helpful for the polymerization reaction of the polymer monomer, so that the gel polymer electrolyte can be obtained
In one embodiment, a septum is also included.
In one embodiment, the gel polymer electrolyte has a thickness of 10-20 μm.
The gel polymer electrolyte has a relatively thick thickness, which increases the overall thickness of the battery, increases the volume of the battery, and affects the energy density of the battery.
In one embodiment, the separator is positioned between the positive electrode and the negative electrode.
The diaphragm acts to isolate the positive and negative electrodes and avoid short circuit contact, so that the diaphragm is only required to be positioned between the positive and negative electrodes. Because the diaphragm has wettability and can be wetted by the gel polymer electrolyte, the diaphragm and the gel polymer electrolyte are not of a layered structure.
In a second aspect, the present invention provides a method for preparing the gel polymer battery as described above, comprising the steps of:
(1) preparing ether electrolyte containing ether organic solvent, lithium salt, polymer monomer and initiator; preparing a carbonate electrolyte containing a carbonate organic solvent, a lithium salt, a polymer monomer and an initiator;
(2) preparing a semi-finished battery from the negative electrode, the positive electrode, the ether electrolyte and the carbonate electrolyte in the step (1);
(3) and (3) placing the semi-finished product battery obtained in the step (2) in an oven to obtain the gel polymer battery.
In one embodiment, in the step (1), the number of moles of the lithium salt per unit volume is the same as the number of moles of the organic solvent; the addition amount of the polymer monomer accounts for 1-20wt% of the ether electrolyte or the carbonate electrolyte, and the addition amount of the initiator accounts for 0.5-10wt% of the ether electrolyte or the carbonate electrolyte.
The addition amount of the lithium salt in the ether electrolyte and the carbonate electrolyte can be calculated according to the molar weight of the solvent molecules.
In the ether electrolyte and the carbonate electrolyte, the number of moles of the lithium salt per unit volume is the same as that of the organic solvent, so that the solvent molecules do not flow, and thus the carbonate electrolyte layer and the ether electrolyte layer in the step (2) do not dissolve each other, but exist in two layers.
In the step (3), the assembled semi-finished battery is placed in an oven for reaction, so that the ether electrolyte and the carbonate electrolyte are thermally initiated to carry out polymerization reaction, and thus a gel-state ether polymer electrolyte layer and a gel-state carbonate polymer electrolyte layer can be formed. Because the polymerization is not carried out, the electrolyte can be in a flowing state and is easy to volatilize, so that safety problems are caused, and meanwhile, the gel electrolyte after polymerization can further limit the flowing state of the electrolyte and prevent the ether electrolyte and the carbonate electrolyte from mutually diffusing.
The step of preparing the semi-finished battery in the step (2) is not limited, and in one embodiment, a diaphragm may be placed on the negative electrode, an ether electrolyte and a carbonate electrolyte are sequentially dropped on the diaphragm, and the positive electrode is placed to obtain the semi-finished battery.
In one embodiment, a diaphragm can be placed on the surface of the positive electrode, carbonate electrolyte and ether electrolyte are sequentially dropped on the diaphragm, and then the negative electrode is placed, so that a semi-finished battery is obtained.
In one embodiment, the ether electrolyte may be dropped on the surface of the negative electrode, the separator may be placed thereon, the carbonate electrolyte may be dropped on the separator, and the positive electrode may be placed thereon, so as to obtain a semi-finished battery.
In one embodiment, a carbonate electrolyte may be dropped on the surface of the positive electrode, a separator may be placed on the carbonate electrolyte, an ether electrolyte may be dropped on the separator, and a negative electrode may be placed on the separator to obtain a semi-finished battery.
The preparation method of the gel polymer battery provided by the invention is a method for carrying out polymerization reaction of electrolyte after the battery is assembled to obtain gel-state polyelectrolyte, namely in-situ polymerization. The method can ensure that the contact between the polymer electrolyte and the positive electrode and the negative electrode is good, thereby reducing the internal interface impedance of the battery and ensuring the good cycle performance of the battery. The polymer electrolyte is polymerized in advance to obtain the polymer electrolyte, and then the battery is assembled, so that the contact effect between the polymer electrolyte layer and the positive electrode and the negative electrode of the battery is poor, the interface impedance is large, and the performance of the battery is not favorably exerted. Therefore, the gel polymer battery prepared by the in-situ polymerization method provided by the invention has smaller internal impedance and better battery performance. Meanwhile, the in-situ polymerization method omits the extraction of pore-forming agent in the polymer film-forming process in the traditional technology, greatly simplifies the process flow, reduces the requirements on equipment, and simultaneously reduces the use of organic solvent which pollutes the environment.
The present invention is further illustrated by the following specific examples, which are provided only for illustrating and explaining the present invention and are not intended to limit the present invention.
Example 1
(1) Preparing an ether electrolyte:
adding lithium salt LiFSI into ether organic solvent tetraethylene glycol dimethyl ether (TEGDME) to enable the molar ratio of the lithium salt to the organic solvent to be 1:1, adding polymer monomers of ethoxylated trimethylolpropane triacrylate (ETPTA) and ethylene glycol diacrylate (PEGDA) to enable the mass ratio to be 5%, adding initiator Azobisisobutyronitrile (AIBN) to enable the mass ratio to be 0.5wt%, and carrying out magnetic stirring for 0.5h at room temperature to obtain the ether electrolyte.
(2) Preparation of carbonate electrolyte
Adding lithium salt LiFSI into a carbonic ester organic solvent diethyl carbonate (DEC) to enable the molar ratio of the lithium salt to the organic solvent to be 1:1, adding polymer monomers of ethoxylated trimethylolpropane triacrylate (ETPTA) and ethylene glycol diacrylate (PEGDA) to enable the mass ratio to be 5%, adding an initiator of Azobisisobutyronitrile (AIBN) to enable the mass ratio to be 0.5%, and magnetically stirring for 0.5h at room temperature to obtain the carbonic ester electrolyte.
(3) And (3) placing a diaphragm on the surface of the lithium sheet, sequentially dropwise adding the ether electrolyte in the step (1) and the carbonate electrolyte in the step (2) on the diaphragm, placing the ternary positive electrode on the carbonate electrolyte to form a button cell, and placing the button cell in a 60 ℃ oven for 24 hours to obtain the gel polymer battery, wherein the thickness of the ether gel polymer electrolyte layer is 5 microns, and the thickness of the carbonate gel polymer electrolyte layer is 5 microns.
Example 2
Different from the embodiment 1, in the step (3), the ether electrolyte in the step (1) is firstly dripped on the surface of the lithium sheet, a diaphragm is placed on the ether electrolyte, then the carbonate electrolyte is dripped on the diaphragm, and then the ternary positive electrode is placed on the carbonate electrolyte to form the button cell; in the obtained battery, the ether gel polymer electrolyte layer had a thickness of 10 μm, and the carbonate gel polymer electrolyte layer had a thickness of 10 μm.
Example 3
Unlike example 1, the ether-based gel polymer electrolyte layer had a thickness of 7.5 μm, and the carbonate-based gel polymer electrolyte layer had a thickness of 7.5 μm.
Example 4
Different from the embodiment 1, the tetraglyme in the embodiment one is replaced by dimethyl ether, and the diethyl carbonate is replaced by ethylene carbonate. In the obtained gel polymer battery, the ether-based gel polymer electrolyte layer had a thickness of 5 μm, and the carbonate-based gel polymer electrolyte layer had a thickness of 10 μm.
Example 5
In contrast to example 1, tetraethylene glycol dimethyl ether in example 1 was replaced by DOL and diethyl carbonate was replaced by ethylene carbonate. In the obtained gel polymer battery, the ether-based gel polymer electrolyte layer had a thickness of 10 μm, and the carbonate-based gel polymer electrolyte layer had a thickness of 10 μm.
Example 6
Unlike example 1, the ether-based gel polymer electrolyte layer had a thickness of 4 μm and the carbonate-based gel polymer electrolyte layer had a thickness of 20 μm.
Example 7
Unlike example 1, the ether-based gel polymer electrolyte layer had a thickness of 20 μm and the carbonate-based gel polymer electrolyte layer had a thickness of 4 μm.
Example 8
Unlike example 1, the ether-based gel polymer electrolyte layer had a thickness of 12 μm, and the carbonate-based gel polymer electrolyte layer had a thickness of 12 μm.
Example 9
Unlike example 1, the ether-based gel polymer electrolyte layer had a thickness of 4 μm, and the carbonate-based gel electrolyte layer had a thickness of 4 μm.
Comparative example 1
Unlike example 1, there was no carbonate-based gel polymer electrolyte layer, only one ether-based gel polymer electrolyte layer, and the thickness of the electrolyte layer was 10 μm.
Comparative example 2
Unlike example 1, there was no ether gel polymer electrolyte layer, only one layer of carbonate gel polymer electrolyte, and the thickness of the electrolyte layer was 10 μm.
Comparative example 3
Unlike example 1, the ether electrolyte and the carbonate electrolyte each have a smaller number of moles of lithium salt than the organic solvent, so that the ether electrolyte and the carbonate electrolyte are mixed together after the dropping in step (3), so that the electrolyte in the resulting gel polymer battery is a gel polymer electrolyte in which ethers and carbonates are mixed.
And (3) testing the cycle performance:
the button cells obtained in the above examples and comparative examples were subjected to charge and discharge cycles 100 times at room temperature of 25 deg.c, a cut-off voltage of 2.7-4.2V, and a current of 0.1C. The test results are given in the following table:
Figure DEST_PATH_IMAGE001
as can be seen from the above table, in a battery system in which metal lithium is used as a negative electrode and a ternary material is used as a positive electrode, good battery cycle performance cannot be obtained by using only a single ether gel polymer electrolyte or a carbonate gel polymer electrolyte or a mixed gel polymer electrolyte thereof, but the ether and carbonate gel polymer electrolytes, which are provided by the present invention and are layered together, can be applied to the battery system and can exhibit good battery performance.

Claims (19)

1. The gel polymer battery is characterized by comprising a positive electrode, a negative electrode and a gel polymer electrolyte, wherein the positive electrode is made of a material with a voltage of more than 3.5V, the negative electrode is made of metal lithium, the gel polymer electrolyte is of a laminated structure and comprises an ether gel polymer electrolyte layer and a carbonate gel polymer electrolyte layer, the ether gel polymer electrolyte layer is close to one side of the negative electrode, and the carbonate polymer electrolyte layer is close to one side of the positive electrode.
2. The gel polymer battery as claimed in claim 1, wherein the positive electrode is one or more of a lithium cobaltate material or a ternary material.
3. The gel polymer cell of claim 2, wherein the ternary material is LiNi1-x- yCoxMnyO2Wherein x is more than or equal to 0.1 and less than or equal to 0.4, and y is more than or equal to 0.2 and less than or equal to 0.5.
4. The gel polymer battery according to claim 1, wherein a thickness ratio of the ether-based gel polymer electrolyte layer to the carbonate-based gel polymer electrolyte layer is 1:2 to 2: 1.
5. The gel polymer battery according to claim 4, wherein the ether-based gel polymer electrolyte layer has a thickness of 5 to 10 μm.
6. The gel polymer battery according to claim 1, wherein the ether gel polymer electrolyte layer is prepared from a mixed solution containing an ether organic solvent, a lithium salt, a polymer monomer and an initiator, and the number of moles of the lithium salt per unit volume is the same as that of the ether organic solvent; the carbonate gel polymer electrolyte layer is prepared from a mixed solution containing a carbonate organic solvent, a lithium salt, a polymer monomer and an initiator, and the mole number of the lithium salt is the same as that of the carbonate organic solvent in unit volume.
7. The gel polymer battery according to claim 6, wherein the mass ratio of the polymer monomer is 1 to 20%, and the mass ratio of the initiator is 0.5 to 10%.
8. The gel polymer battery according to claim 6, wherein the ether organic solvent is one or more of dimethyl ether, 1, 3-dioxolane, dipropylene glycol propyl ether, and tetraethylene glycol dimethyl ether.
9. The gel polymer electrolyte as claimed in claim 6, wherein the carbonate organic solvent is one or more selected from ethylene carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate.
10. The gel polymer cell of claim 6, wherein said lithium salt is LiTFSI, LiFSI, LiBOB, LiDOFB, LiPF6，LiBF4One or more of them.
11. The gel polymer battery according to claim 6, wherein the polymer monomer is one or more of polyethylene glycol diglycidyl ether, propylene oxide, diglycidyl ether, and glycidyl methyl ether; the initiator is LiPF6，LiBF4One kind of (1).
12. The gel polymer battery as claimed in claim 6, wherein the polymer monomer is one or more of 2-phenoxyethyl acrylate, triethylene glycol dimethacrylate, polyethylene glycol monomethyl ether methacrylate, ethylene glycol diacrylate and ethoxylated trimethylolpropane triacrylate; the initiator is one of azodiisobutyronitrile and dibenzoyl peroxide.
13. The gel polymer battery as claimed in claim 1, further comprising a separator.
14. The gel polymer battery as claimed in claim 1, wherein the thickness of the gel polymer electrolyte is 10-20 μm.
15. A method for preparing a gel polymer battery according to claim 1, comprising the steps of:
(1) preparing an ether electrolyte containing an ether organic solvent, a lithium salt, a polymer monomer and an initiator: preparing a carbonate electrolyte containing a carbonate organic solvent, a lithium salt, a polymer monomer and an initiator;
(2) preparing a semi-finished battery from the negative electrode, the positive electrode, the ether electrolyte and the carbonate electrolyte in the step (1);
(3) and (3) placing the semi-finished product battery obtained in the step (2) in an oven to obtain the gel polymer battery.
16. The preparation method according to claim 15, wherein the step (2) comprises placing a separator on the surface of the negative electrode, sequentially dropping an ether electrolyte and a carbonate electrolyte on the separator, and placing the positive electrode to obtain a semi-finished battery.
17. The preparation method according to claim 15, wherein the step (2) comprises placing a separator on the surface of the positive electrode, sequentially dropping carbonate electrolyte and ether electrolyte on the separator, and placing the negative electrode to obtain the semi-finished battery.
18. The production method according to claim 15, wherein the step (2) comprises dropping the ether electrolyte on the negative electrode, placing the separator, dropping the carbonate electrolyte on the separator, and placing the positive electrode to obtain the semi-finished battery.
19. The production method according to claim 15, wherein the step (2) comprises dropping a carbonate electrolyte on the surface of the positive electrode, placing a separator, dropping an ether electrolyte on the separator, and placing the negative electrode to obtain the semi-finished battery.
CN201910449710.5A 2019-05-28 2019-05-28 Gel polymer battery and preparation method thereof Pending CN112018427A (en)

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