CN114937850A - Electrochemical device and electronic device - Google Patents

Electrochemical device and electronic device Download PDF

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Publication number
CN114937850A
CN114937850A CN202210730989.6A CN202210730989A CN114937850A CN 114937850 A CN114937850 A CN 114937850A CN 202210730989 A CN202210730989 A CN 202210730989A CN 114937850 A CN114937850 A CN 114937850A
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electrochemical device
positive electrode
electrolyte
compound
negative electrode
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王仁和
王子沅
余乐
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Envision Power Technology Jiangsu Co Ltd
Envision Ruitai Power Technology Shanghai Co Ltd
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Envision Power Technology Jiangsu Co Ltd
Envision Ruitai Power Technology Shanghai 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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • 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
    • 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
    • H01M10/0566—Liquid materials
    • 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

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  • Secondary Cells (AREA)
  • Electric Double-Layer Capacitors Or The Like (AREA)

Abstract

The invention discloses an electrochemical device and an electronic device. The electrochemical device comprises a diaphragm and an electrolyte, wherein the electrolyte comprises a carboxylic ester compound, and the specific surface area of the diaphragm is 0.1-0.3. The high-temperature cycle performance of the electrochemical device of the present invention is improved.

Description

Electrochemical device and electronic device
Technical Field
The present invention relates to the field of electrochemical devices, and particularly to an electrochemical device and an electronic device.
Background
Because the lithium ion battery has the important advantages of high voltage and high capacity, long cycle life and good safety performance, the lithium ion battery has wide application prospect in various aspects such as portable electronic equipment, electric automobiles, space technology, industry and the like.
The electrolyte is the blood of the lithium battery, is one of four key raw materials of the lithium battery, is a carrier for ion transmission in the battery, plays a role in conducting lithium ions between a positive electrode and a negative electrode, and has important influences on the energy density, specific capacity, working temperature range, cycle life, safety performance and the like of the lithium battery.
In order to develop a suitable high-performance electrolyte, a suitable electrolyte additive is often added to the electrolyte, and the commonly used electrolyte additive includes boron-containing additives, organic phosphorus additives, carbonate additives, carboxylic ester additives, sulfur-containing additives, ionic liquid additives, and the like. However, the conventional electrolyte additive is difficult to achieve the aim of improving the high-temperature cycle of the battery through a simple formula and a few additives.
The specific surface area of the separator determines its capacity to occlude the electrolyte and the diffusion path length of the substances in the electrolyte. Generally, in a certain range, the larger the specific surface area of the separator, the greater the degree of the electrolyte occlusion, the more uniform the electrolyte in contact with the electrode sheet, the easier the substance diffusion, and the better the additive film forming effect. However, if the specific surface area of the diaphragm is too large, the electrolyte is mainly adsorbed by the diaphragm, the substance exchange is hindered, the mass transfer process is hindered, and the long cycle performance of the battery is deteriorated; if the specific surface area of the separator is too small, the electrolyte is unevenly distributed due to the influence of gravity, and the cycle performance of the battery is also affected.
Disclosure of Invention
In view of the disadvantages of the prior art, it is an object of the present invention to provide an electrochemical device and an electronic device, in which high-temperature cycle performance is improved.
One of the objectives of the present invention is to provide an electrochemical device, and to achieve the objective, the present invention adopts the following technical scheme:
an electrochemical device comprising a separator and an electrolyte, the electrolyte comprising a carboxylic acid ester compound, the separator having a specific surface area of 0.1 to 0.3.
According to the electrochemical device, the electrolyte adopts the carboxylic ester compound, and the high-temperature cycle performance of the prepared electrochemical device is improved by adjusting the specific surface area of the diaphragm.
In the present invention, the specific surface area of the separator is 0.1 to 0.3, for example, 0.1, 0.15, 0.2, 0.25, 0.3, or the like.
In the present invention, the content of the carboxylic ester compound is 0.5 to 5% by mass, for example, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, or 5% by mass based on the mass of the electrolyte solution, and if the amount of the carboxylic ester compound is too small, the effect is not significantly less than 0.5% by mass; if the amount of the carboxylic ester compound is too large, more than 5% will result in a decrease in the circulating capacity.
In the invention, the carboxylic ester compound comprises a compound shown as a formula (I):
Figure RE-GDA0003764237320000021
R 1 、R 3 、R 4 each independently selected from hydrogen, substituted or unsubstituted C 1-12 A hydrocarbon group of (1); r 2 Is selected from C 1-12 When substituted, the substituent is a halogen atom.
Preferably, the compound represented by the formula (I) comprises dimethyl fumarate
Figure RE-GDA0003764237320000031
Methacrylic acid methyl ester
Figure RE-GDA0003764237320000032
Maleic acid dimethyl ester
Figure RE-GDA0003764237320000033
Methacrylic acid 1,1,1,3,3, 3-hexafluoroisopropyl ester
Figure RE-GDA0003764237320000034
Methacrylic acid vinyl ester
Figure RE-GDA0003764237320000035
Any one or a mixture of two or more of them. Typical but not limiting combinations of said mixtures are mixtures of two, three, four or five, for example mixtures of dimethyl fumarate, methyl methacrylate, dimethyl fumarate, dimethyl maleate, mixtures of dimethyl fumarate, 1,1,3,3, 3-hexafluoroisopropyl methacrylate, mixtures of dimethyl fumarate, vinyl methacrylate, mixtures of dimethyl fumarate, methyl methacrylate, dimethyl maleate, mixtures of dimethyl fumarate, methyl methacrylate, 1,1,3,3, 3-hexafluoroisopropyl methacrylate, mixtures of dimethyl fumarate, methyl methacrylate, vinyl methacrylate, methyl methacrylate, dimethyl maleate, 1,1, a mixture of 3,3, 3-hexafluoroisopropyl esters, a mixture of methyl methacrylate, dimethyl maleate, vinyl methacrylate, dimethyl maleate, 1,1,3,3, 3-hexafluoroisopropyl methacrylate, a mixture of vinyl methacrylate, dimethyl fumarate, methyl methacrylate, dimethyl maleate, a mixture of 1,1,1,3,3, 3-hexafluoroisopropyl methacrylate, a mixture of dimethyl fumarate, methyl methacrylate, dimethyl maleate, vinyl methacrylate, methyl methacrylate, dimethyl methacrylate, 1,1,1,3,3, 3-hexafluoroisopropyl methacrylate, a mixture of vinyl methacrylate, dimethyl fumarate, methyl methacrylate, dimethyl maleate, dimethyl methacrylate, dimethyl maleate, vinyl methacrylate, dimethyl fumarate, dimethyl maleate, vinyl methacrylate, vinyl acetate, or vinyl acetate, or vinyl acetate, vinyl acetate, 1,1,1,3,3, 3-hexafluoroisopropyl methacrylate, vinyl methacrylate.
Preferably, the specific surface area of the separator is 0.2 to 0.3.
In the present invention, the electrochemical device further comprises a positive electrode and a negative electrode; the positive electrode comprises a positive electrode active material, and the positive electrode active material comprises a lithium nickel cobalt manganese composite oxide or lithium iron phosphate.
In the present invention, the metal ion content of the positive electrode is 0.05ppm to 200ppm, for example, 0.05ppm, 0.1ppm, 0.2ppm, 0.3ppm, 0.4ppm, 0.5ppm, 0.6ppm, 0.7ppm, 0.8ppm, 0.9ppm, 1ppm, 2ppm, 3ppm, 4ppm, 5ppm, 6ppm, 7ppm, 8ppm, 9ppm, 10ppm, 20ppm, 30ppm, 40ppm, 50ppm, 60ppm, 70ppm, 80ppm, 90ppm, 100ppm, 110ppm, 120ppm, 130ppm, 140ppm, 150ppm, 160ppm, 170ppm, 180ppm, 190ppm or 200 ppm; if the metal ion content of the positive electrode is too low, below 0.05ppm, it is difficult to measure, and if the metal ion content of the positive electrode is too high, above 200ppm, it causes more reaction with electrolyte additives, affecting the film forming effect.
In the present invention, the metal includes any one of nickel, cobalt, manganese, and iron, or a mixture of two or more thereof. The metal ion content of the positive electrode is 0.05ppm to 200ppm, wherein ppm is a mass unit, and the metal ion content of the positive electrode is measured by the following measuring method: the electrolyte and the negative electrode active material layer in the battery are sampled for ICP test, and denominators are calculated by the total mass of the battery, for example, the total metal ion content of nickel, cobalt, manganese, iron in the positive electrode is 0.05ppm to 200 ppm.
In the present invention, the negative electrode contains a negative electrode active material containing a silicon oxide compound and/or graphite.
The electrochemical device of the present invention includes any device in which electrochemical reactions occur, and specific examples thereof include all kinds of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors. In particular, the electrochemical device is a lithium secondary battery including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
In some embodiments, the electrochemical device of the present invention is an electrochemical device including a positive electrode having a positive electrode active material capable of occluding and releasing metal ions and a negative electrode having a negative electrode active material capable of occluding and releasing metal ions.
It is another object of the present invention to provide an electronic device including the electrochemical device according to the first object.
The electronic devices include, but are not limited to, types such as notebook computers, pen-input computers, mobile computers, electronic book players, portable telephones, portable facsimile machines, portable copiers, portable printers, headphones, video recorders, liquid crystal televisions, portable cleaners, portable CDs, mini-discs, transceivers, electronic organizers, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, power-assisted bicycles, lighting fixtures, toys, game machines, clocks, electric tools, flashlights, cameras, large household batteries or lithium ion capacitors, and the like.
Compared with the prior art, the invention has the beneficial effects that:
the high-temperature cycle performance of the electrochemical device of the present invention is improved.
Detailed Description
The technical solution of the present invention is further described below by way of specific embodiments.
Unless otherwise specified, various starting materials of the present invention are commercially available or prepared according to conventional methods in the art.
The electrochemical device comprises a diaphragm and an electrolyte, wherein the electrolyte comprises a carboxylic ester compound, and the specific surface area of the diaphragm is 0.1-0.3.
In the present invention, the electrochemical device is a lithium ion battery, and the lithium ion battery is a primary lithium battery or a secondary lithium battery, including: the battery comprises a positive electrode, a negative electrode, a diaphragm positioned between the positive electrode and the negative electrode and an electrolyte.
The preparation method of the secondary lithium battery comprises the following steps:
(1)LiNi 0.55 Co 0.15 Mn 0.3 O 2 preparation of the positive electrode:
mixing the positive electrode active material (LiNi) 0.55 Co 0.15 Mn 0.3 O 2 ) Mixing polyvinylidene fluoride as a binder, carbon nano tubes as a conductive agent and Super P according to the weight ratio of 97.2:1:0.8:1, adding N-methyl pyrrolidone (NMP), and stirring under the action of a vacuum stirrer until the system is in a shape of a bottleThe slurry is uniform and transparent, and positive electrode slurry is obtained; uniformly coating the anode slurry on an aluminum foil; drying the aluminum foil at room temperature, transferring the aluminum foil to an oven for drying, and then performing cold pressing and slitting to obtain a positive electrode (a pole piece);
(2)LiNi 0.8 Co 0.1 Mn 0.1 O 2 preparation of the positive electrode:
mixing the positive electrode active material (LiNi) 0.8 Co 0.1 Mn 0.1 O 2 ) Mixing polyvinylidene fluoride serving as a binder and Super P serving as a conductive agent according to a weight ratio of 98:1:1, adding N-methylpyrrolidone (NMP), and stirring under the action of a vacuum stirrer until the system is uniform and transparent to obtain anode slurry; uniformly coating the anode slurry on an aluminum foil; drying the aluminum foil at room temperature, transferring the aluminum foil to an oven for drying, and then performing cold pressing and slitting to obtain a positive electrode (a pole piece);
(3)LiFePO 4 preparation of the positive electrode:
mixing the positive active material (LiFePO) 4 ) Mixing polyvinylidene fluoride serving as a binder and Super P serving as a conductive agent according to a weight ratio of 97:2:1, adding N-methyl pyrrolidone (NMP), and stirring under the action of a vacuum stirrer until a system is uniform and transparent to obtain anode slurry; uniformly coating the anode slurry on an aluminum foil; drying the aluminum foil at room temperature, transferring the aluminum foil to an oven for drying, and then carrying out cold pressing and slitting to obtain a positive electrode (pole piece);
(4) preparing a graphite negative electrode:
mixing artificial graphite serving as a negative electrode active material, Super P serving as a conductive agent, sodium carboxymethylcellulose (CMC-Na) serving as a thickening agent and Styrene Butadiene Rubber (SBR) serving as a binder according to a mass ratio of 96:1:1:2, adding deionized water, and obtaining negative electrode slurry under the action of a vacuum stirrer; uniformly coating the negative electrode slurry on a copper foil of a negative electrode current collector; airing the copper foil at room temperature, transferring the copper foil to an oven for drying, and then carrying out cold pressing and slitting to obtain a negative electrode (pole piece);
(5) preparation of a silicon-oxygen negative electrode:
mixing silicon monoxide and artificial graphite according to the mass ratio of 1:9 to obtain a negative electrode active material, mixing the negative electrode active material with SWCNT (single-walled carbon nanotube) as a conductive agent and polyacrylic acid (PAA) as a binder according to the mass ratio of 96:0.2:3.8, adding deionized water, and obtaining negative electrode slurry under the action of a vacuum stirrer; uniformly coating the negative electrode slurry on a copper foil of a negative electrode current collector; the copper foil is dried at room temperature and then transferred to an oven for drying, and then a negative electrode (pole piece) is obtained through cold pressing and slitting;
(6) preparing an electrolyte:
at water content<In a 10ppm argon atmosphere glove box, battery grade Ethylene Carbonate (EC) and Ethyl Methyl Carbonate (EMC) were mixed in a mass ratio of 3:7 to form an organic solvent, and lithium hexafluorophosphate (LiPF) was added based on the mass of the electrolyte 6 ) The electrolyte is prepared by adding other components according to the quantitative composition of the electrolyte in the following table, and complementing the balance of organic solvent to 100% of the total mass of the electrolyte, and mixing uniformly to obtain the electrolyte; wherein FEC is fluoroethylene carbonate, DTD is vinyl sulfate, and VC is vinylene carbonate; the contents of the components in the table are weight percentages calculated based on the total weight of the electrolyte;
(7) preparing a diaphragm:
taking a polypropylene film as a diaphragm;
(8) preparation of secondary battery:
the positive electrode, the separator and the negative electrode prepared by the method are sequentially laminated by taking a polypropylene film (PP) with the thickness of 12 mu m as the separator, so that the separator is positioned between the positive electrode and the negative electrode to play a role of isolation. And then, wrapping an aluminum-plastic film, transferring the aluminum-plastic film to a vacuum oven for drying at 120 ℃, injecting the prepared electrolyte, sealing, and carrying out electrolyte formation to finally prepare the soft package battery (namely the lithium ion battery) with the capacity of 1 Ah.
In the examples of the present invention, the compound represented by formula (I) is five compounds, i.e., methyl methacrylate compound 1, dimethyl fumarate compound 2, dimethyl maleate compound 3, 1,1,3,3, 3-hexafluoroisopropyl methacrylate compound 4, and vinyl methacrylate compound 5.
The secondary battery of the present invention can be tested by the following method:
(1) high temperature cycle 80% turns
And (3) carrying out cyclic charge and discharge in an oven at the temperature of 45 ℃ in a specified potential interval by using the current of 1C, recording the discharge capacity of each circle, and ending the test when the battery capacity reaches 80% of the capacity of the first circle.
The cut-off voltage of charging and discharging is specifically as follows:
the positive electrode being LiNi 0.55 Co 0.15 Mn 0.3 O 2 When the voltage is in the range of 2.8-4.35V; the positive electrode being LiNi 0.8 Co 0.1 Mn 0.1 O 2 When the voltage is in the range of 2.8-4.25V; the positive electrode is LiFePO 4 The charging and discharging voltage range is 2.5-3.65V.
(2) Determination of specific surface area of separator
The specific surface area of the separator was measured using AUTOSOBE 3MP manufactured by Yuasa-ionics corporation, as follows:
as a pretreatment, 1g of polyethylene powder was put into a sample tube, and heated and degassed at 80 ℃ under 0.01mmHg for 12 hours in a sample pretreatment apparatus. Subsequently, the specific surface area of the separator was measured according to the BET method using nitrogen as an adsorption gas at a measurement temperature of-196 ℃.
The compositions of the positive electrode, the negative electrode and the electrolyte of examples 1 to 4 and comparative examples 1 to 3 of the present invention are shown in table 1-1, and the performance of the lithium ion battery prepared by the above preparation method was tested, and the test results are shown in table 1-2.
TABLE 1-1
Figure RE-GDA0003764237320000081
Note: "/" indicates no addition, the same is used below.
Tables 1 to 2
High temperature cycle 80% turns
Example 1 729
Example 2 1377
Example 3 1295
Example 4 788
Comparative example 1 528
Comparative example 2 746
Comparative example 3 672
As can be seen from the data of tables 1-2, the electrochemical device of the present invention, which uses LiNi, is based on 0.55 Co 0.15 Mn 0.3 O 2 When the compound 1 is adopted as the carboxylic ester compound and the mass content of the compound is limited to 1% and the specific surface area of the diaphragm of the embodiment 1 to 4 is 0.1 to 0.3, the high-temperature cycle performance test result of the prepared lithium battery is better; too small a specific surface area of the separator of comparative example 1 and too large a specific surface area of the separator of comparative example 2 both deteriorate high temperature cycle performance of the lithium battery.
Comparing example 2 with comparative example 3, it can be seen that the high temperature cycle performance of the lithium battery is reduced because no carboxylic ester compound is added in comparative example 3.
The compositions of the positive electrode, the negative electrode and the electrolyte of examples 5 to 7 and comparative examples 4 to 5 of the present invention are shown in table 2-1, and the performance of the lithium ion battery prepared by the above preparation method was tested, and the test results are shown in table 2-2.
TABLE 2-1
Figure RE-GDA0003764237320000091
Figure RE-GDA0003764237320000101
Tables 2 to 2
High temperature cycle of 80% turns
Example 5 914
Example 1 1377
Example 6 1193
Example 7 1086
Comparative example 4 828
Comparative example 5 719
As can be seen from the data of tables 2-2, the electrochemical device of the present invention, which uses LiNi 0.55 Co 0.15 Mn 0.3 O 2 When the specific surface area of the separator is 0.2 and the specific surface area of the separator is 0.5% to 5%, the electrolytes of examples 1 and 5 to 7 can improve the high-temperature cycle performance of the lithium battery, particularly, the high-temperature cycle performance of the lithium battery is optimal when the amount of the compound represented by the formula (I) is 1% to 5%, and the high-temperature cycle performance of the lithium battery is reduced when the amount of the compound represented by the formula (I) is too small in comparative example 4 and too much of the compound represented by the formula (I) is added in comparative example 5.
Examples 8 to 11
The composition of the positive electrode, the negative electrode, and the electrolyte solution in examples 8 to 11 of the present invention is different from that in example 1 in that the compound represented by the formula (I) in example 1 is compound 1, the compound represented by the formula (I) in example 8 is compound 2, the compound represented by the formula (I) in example 9 is compound 3, the compound represented by the formula (I) in example 10 is compound 4, the compound represented by the formula (I) in example 11 is compound 5, and the others are the same as those in example 1.
The lithium ion battery prepared by the preparation method is tested for performance, and the test results are shown in table 3.
TABLE 3
High temperature cycle of 80% turns
Example 1 1377
Example 8 1318
Example 9 1334
Example 10 1220
Example 11 1263
Comparative example 3 672
As can be seen from the data in Table 3, the electrochemical device of the present invention, which uses LiNi, was constructed 0.55 Co 0.15 Mn 0.3 O 2 When the positive electrode and the graphite are used as the negative electrode and the specific surface area of the separator is 0.2, the five different carboxylic ester compounds are adopted as the compounds shown in the formula (I) in the electrolytes of examples 1 and 8 to 11, and the high-temperature cycle performance of the prepared lithium battery is obviously improved compared with that of a lithium battery prepared by a comparative example 3 without adding the carboxylic ester compounds.
The compositions of the positive electrode, the negative electrode and the electrolyte of examples 12 to 15 and comparative examples 6 to 7 of the present invention are shown in table 4-1, and the performance of the lithium ion battery prepared by the above preparation method was tested, and the test results are shown in table 4-2.
TABLE 4-1
Figure RE-GDA0003764237320000111
TABLE 4-2
High temperature cycle 80% turns
Example 12 757
Example 13 1068
Example 14 1231
Example 15 775
Comparative example 6 350
Comparative example 7 514
As can be seen from the data of Table 4-2, the electrochemical device of the present invention, which uses LiNi 0.8 Co 0.1 Mn 0.1 O 2 When the anode and the silicon oxide are used as cathodes, and the electrolyte is added with a carboxylic ester compound, the carboxylic ester compound adopts the compound 1 and the mass content of the compound 1 is limited to be 1%, and the specific surface area of the diaphragm of the embodiment 12 to 15 is 0.1 to 0.3, the high-temperature cycle performance test result of the prepared lithium battery is better; the specific surface area of the separator of comparative example 6 was too small, and the specific surface of the separator of comparative example 7Too large a volume will degrade the high temperature cycling performance of the lithium battery.
The compositions of the positive electrode, the negative electrode and the electrolyte of examples 16 to 18 and comparative examples 8 to 9 of the present invention are shown in table 5-1, and the performance of the lithium ion battery prepared by the above-described preparation method was tested, and the test results are shown in table 5-2.
TABLE 5-1
Figure RE-GDA0003764237320000121
TABLE 5-2
High temperature cycle 80% turns
Example 16 814
Example 13 1068
Example 17 967
Example 18 943
Comparative example 8 806
Comparative example 9 522
As can be seen from the data of Table 5-2, the electrochemical device of the present invention, which uses LiNi 0.8 Co 0.1 Mn 0.1 O 2 When the specific surface area of the separator is 0.2 for the positive electrode and the silicon oxide for the negative electrode, the high-temperature cycle performance of the lithium battery prepared in examples 13 and 16 to 18 can be improved by adjusting the amount of the compound represented by formula (I) to 0.5% to 5%, and particularly, the high-temperature cycle performance of the lithium battery prepared in examples 1% to 5% is optimized, and the high-temperature cycle performance of the lithium battery prepared in comparative example 8 is reduced by adding too little of the compound represented by formula (I) and the high-temperature cycle performance of the lithium battery prepared in comparative example 9 is reduced by adding too much of the compound represented by formula (I).
Examples 19 to 22
The positive electrode, the negative electrode, and the electrolyte composition of examples 19 to 22 of the present invention are different from those of example 13 in that the compound represented by the formula (I) of example 13 is compound 1, the compound represented by the formula (I) of example 19 is compound 2, the compound represented by the formula (I) of example 20 is compound 3, the compound represented by the formula (I) of example 21 is compound 4, the compound represented by the formula (I) of example 22 is compound 5, and the others are the same as those of example 13.
Comparative example 10
This comparative example is different from example 13 in that the compound represented by the formula (I) was not added, the amount of the compound represented by the formula (I) was decreased to make up the organic solvent, and the rest was the same as in example 13.
The lithium ion battery prepared by the preparation method is tested for performance, and the test results are shown in table 6.
TABLE 6
High temperature cycle of 80% turns
Example 13 1068
Example 19 1115
Example 20 1164
Example 21 1308
Example 22 1011
Comparative example 10 703
As can be seen from the data in Table 6, the electrochemical device of the present invention, which uses LiNi, was fabricated using LiNi 0.8 Co 0.1 Mn 0.1 O 2 When the anode is a cathode and silicon oxide is an anode and the specific surface area of the separator is 0.2, the five different carboxylic ester compounds are adopted in the compounds shown in the formula (I) in the electrolytes of examples 13 and 19 to 22, and compared with comparative example 10, the high-temperature cycle performance of the prepared lithium battery is obviously improved without adding the carboxylic ester compounds.
The compositions of the positive electrode, the negative electrode and the electrolyte of examples 23 to 26 and comparative examples 11 to 12 of the present invention are shown in table 7-1, and the performance of the lithium ion battery prepared by the above-described preparation method was tested, and the test results are shown in table 7-2.
TABLE 7-1
Figure RE-GDA0003764237320000141
Figure RE-GDA0003764237320000151
TABLE 7-2
High temperature cycle 80% turns
Example 23 665
Example 24 1163
Example 25 970
Example 26 659
Comparative example 11 463
Comparative example 12 645
As can be seen from the data in Table 7-2, the electrochemical device of the present invention employs LiFePO 4 Adding carboxylic ester compound into the electrolyte, wherein the carboxylic ester compound is compound 1 and limited to itWhen the mass content is 1% and the specific surface area of the separator of examples 23 to 26 is 0.1 to 0.3, the high-temperature cycle performance test result of the prepared lithium battery is better; too small a specific surface area of the separator of comparative example 11 and too large a specific surface area of the separator of comparative example 12 both degrade the high temperature cycle performance of the lithium battery.
The compositions of the positive electrode, the negative electrode and the electrolyte of examples 27 to 29 and comparative examples 13 to 14 of the present invention are shown in table 8-1, and the performance of the lithium ion battery prepared by the above-described preparation method was tested, and the test results are shown in table 8-2.
TABLE 8-1
Figure RE-GDA0003764237320000152
TABLE 8-2
High temperature cycle 80% turns
Example 27 806
Example 24 1163
Example 28 835
Example 29 789
Comparative example 13 645
Comparative example 14 793
As can be seen from the data in Table 8-2, the electrochemical device of the present invention employs LiFePO 4 When the specific surface area of the separator is 0.2 for the positive electrode and graphite for the negative electrode, the high-temperature cycle performance of the lithium battery obtained in examples 24 and 27 to 29 can be improved by adjusting the amount of the compound represented by formula (I) to 0.5% to 5%, and particularly, the high-temperature cycle performance of the lithium battery obtained in examples 1% to 5% is optimized, and the high-temperature cycle performance of the lithium battery obtained in comparative example 13, in which the compound represented by formula (I) is added too little, and the high-temperature cycle performance of the lithium battery obtained in comparative example 14, in which the compound represented by formula (I) is added too much, is degraded.
Examples 30 to 33
The compositions of the positive electrode, the negative electrode, and the electrolyte solutions of examples 30 to 33 of the present invention are different from those of example 24 in that the compound represented by the formula (I) of example 24 is compound 1, the compound represented by the formula (I) of example 30 is compound 2, the compound represented by the formula (I) of example 31 is compound 3, the compound represented by the formula (I) of example 32 is compound 4, the compound represented by the formula (I) of example 33 is compound 5, and the others are the same as those of example 24.
Comparative example 15
This comparative example differs from example 24 in that the compound of formula (I) was not added, the amount of the compound of formula (I) added was decreased to make up the organic solvent, and the rest was the same as in example 24.
The lithium ion battery prepared by the preparation method is tested for performance, and the test results are shown in table 9.
TABLE 9
High temperature cycle 80% turns
Example 24 1163
Example 30 1169
Example 31 1209
Example 32 1164
Example 33 1018
Comparative example 15 583
As can be seen from the data in Table 9, the electrochemical device of the present invention employs LiFePO 4 When the positive electrode and the graphite are used as the negative electrode and the specific surface area of the separator is 0.2, the five different carboxylic ester compounds are adopted as the compounds shown in the formula (I) in the electrolytes of examples 24 and 30 to 33, and the high-temperature cycle performance of the prepared lithium battery is obviously improved compared with that of a lithium battery prepared by a comparative example 15 without adding the carboxylic ester compounds.
The positive and negative electrodes, the electrolyte formulations, and the separators of the batteries of examples 34 to 37 were the same as those of example 24, except that the metal ion content of the positive electrode of example 24 was 0.05ppm, and the nickel-manganese-cobalt-iron mixed salts were added to the batteries of examples 34 to 37, respectively, so that the metal ion contents of the positive electrode were adjusted to 50ppm, 100ppm, 200ppm, and 250ppm (ppm is based on the total weight of the battery), respectively.
The lithium ion battery prepared by the preparation method is tested for performance, and the test results are shown in table 10.
Watch 10
Content of Metal ion (ppm) High temperature cycle 80% turns
Example 24 0.05 1163
Example 34 50 961
Example 35 100 956
Example 36 200 833
Example 37 250 520
As can be seen from the data in Table 10, the electrochemical device of the present invention employs LiFePO 4 The lithium battery is a positive electrode and graphite is a negative electrode, when the specific surface area of the diaphragm is 0.2 and the metal dissolution rate of the positive electrode is 0.05ppm to 250ppm, the high-temperature cycle performance of the lithium battery is better, and particularly when the metal dissolution rate of the positive electrode is 0.05ppm to 200ppm, the high-temperature cycle performance of the lithium battery is optimal.
The present invention is illustrated by the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, i.e. it is not meant to imply that the present invention must rely on the above-mentioned detailed process equipment and process flow to be practiced. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims (10)

1. An electrochemical device comprising a separator and an electrolyte, wherein the electrolyte comprises a carboxylic acid ester compound, and the specific surface area of the separator is 0.1 to 0.3.
2. The electrochemical device according to claim 1, wherein the carboxylic ester compound is contained in an amount of 0.5 to 5% by mass based on the mass of the electrolyte.
3. The electrochemical device according to claim 1, wherein the carboxylate compound comprises a compound represented by formula (I):
Figure FDA0003713443590000011
R 1 、R 3 、R 4 each independently selected from hydrogen, substituted or unsubstituted C 1-12 A hydrocarbon group of (a); r 2 Is selected from C 1-12 When substituted, the substituent is a halogen atom.
4. The electrochemical device according to claim 3, wherein the compound represented by formula (I) comprises one or a mixture of two or more of dimethyl fumarate, methyl methacrylate, dimethyl maleate, 1,1,1,3,3, 3-hexafluoroisopropyl methacrylate, and vinyl methacrylate.
5. The electrochemical device according to any one of claims 1 to 4, characterized in that the specific surface area of the separator is 0.2 to 0.3.
6. The electrochemical device according to any one of claims 1 to 4, further comprising a positive electrode and a negative electrode;
the positive electrode comprises a positive electrode active material, and the positive electrode active material comprises a lithium nickel cobalt manganese composite oxide or lithium iron phosphate.
7. The electrochemical device according to claim 6, wherein the metal ion content of the positive electrode is 0.05ppm to 200 ppm.
8. The electrochemical device according to claim 7, wherein the metal comprises any one or a mixture of two or more of nickel, cobalt, manganese, and iron.
9. The electrochemical device according to claim 6, wherein the negative electrode comprises a negative electrode active material comprising a silicon-oxygen compound and/or graphite.
10. An electronic device comprising the electrochemical device according to any one of claims 1 to 9.
CN202210730989.6A 2022-06-24 2022-06-24 Electrochemical device and electronic device Pending CN114937850A (en)

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