Electrochemical apparatus and electronic apparatus including the same

Abstract

The present invention relates to an electrochemical device and an electronic device including the same. The electrochemical device includes an electrolytic solution, the electrolytic solution includes a carboxylic acid ester compound and fluoroethylene carbonate (FEC), and based on the total weight of the electrolytic solution, the content of the carboxylic acid ester compound and the content of the fluoroethylene carbonate are w 1 and w 2 respectively. When they are set as 5% ≦ w 1 ≦ 60%, 2% ≦ w 2 ≦ 12%, and 2 ≦ w 1 / w 2 ≦ 20. The electrochemical device exhibits excellent rapid charging characteristics and high-temperature interval cycle characteristics.

Description

[Technical Field]

[0001] The present invention relates to the field of energy storage technology, and more specifically to electrochemical devices and electronic devices including the same. [Background technology]

[0002] Rechargeable electrochemical devices are considered one of the most attractive energy storage systems due to their high energy density, relatively simple reaction mechanisms, high operating voltage, long lifespan, and environmental friendliness. Currently, electrochemical devices such as lithium-ion batteries are widely used in electronic products such as laptops, smartphones, and wearable devices.

[0003] As the market pursues rapid charging for electronic products, the demand for charging speed in electrochemical devices is increasing. This requires electrochemical devices to have excellent electrochemical properties, particularly excellent cycle characteristics, even at high current densities. Furthermore, rapid charging of electrochemical devices often generates heat, and the rise in temperature further deteriorates the cycle stability of the electrochemical device. For example, a laptop computer is initially charged to a full charge during use, maintained at a full charge for several hours, and finally discharged when disconnected from the charger. During this process, the battery in a laptop computer generates heat and becomes hot. When a laptop computer is subjected to the intermittent operating conditions of high-temperature storage and charge / discharge cycles, the degradation of battery capacity becomes severe, which places a higher demand on the high-temperature interval cycle (ITC) characteristics of the electrochemical device.

[0004] In light of this, it is urgent to obtain an electrochemical device with excellent rapid charging characteristics and high-temperature interval cycling characteristics in order to meet the above-mentioned needs of the people. [Overview of the Initiative]

[0005] The present invention improves the rapid charging characteristics and high-temperature interval cycling characteristics of an electrochemical apparatus by improving the electrolyte composition and / or designing the size of the electrochemical apparatus, in order to solve at least the above problems.

[0006] According to one aspect of the present invention, the present invention relates to an electrolyte, wherein the electrolyte comprises a carboxylic acid ester compound represented by formula (I) and fluoroethylene carbonate (FEC), [ka] R 11 R comprises at least one of hydrogen, a hydroxyl group, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C2-C20 linear alkenyl group, a C6-C30 aryl group, and a C6-C30 aryloxy group. 12 It comprises at least one of a C1-C20 alkyl group, a C2-C20 linear alkenyl group, and a C6-C30 aryl group. The present invention provides an electrolyte in which, based on the total weight of the electrolyte, the content of the carboxylic acid ester compound represented by formula (I) and the content of the fluoroethylene carbonate are w1 and w2, respectively, such that 5% ≤ w1 ≤ 60%, 2% ≤ w2 ≤ 12%, and 2 ≤ w1 / w2 ≤ 20.

[0007] According to an embodiment of the present invention, 4 ≤ w1 / w2 ≤ 10.

[0008] According to examples of the present invention, the carboxylic acid ester compound represented by formula (I) comprises at least one of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, n-butyl propionate, isobutyl propionate, n-amyl propionate, isoamyl propionate, ethyl n-butyrate, n-propyl n-butyrate, propyl isobutyrate, n-amyl n-butyrate, n-amyl isobutyrate, n-butyl n-butyrate, isobutyl isobutyrate, and n-amyl n-valerate.

[0009] According to an embodiment of the present invention, the carboxylic acid ester compound represented by the formula (I) includes propyl propionate and ethyl acetate.

[0010] According to an embodiment of the present invention, the electrolytic solution further includes a nitrile compound. When the content of the nitrile compound is w3 based on the total weight of the electrolytic solution, 0.1% ≤ w3 ≤ 12%.

[0011] According to an embodiment of the present invention, the nitrile compound includes at least one of the compounds represented by the formula (II) to the formula (V).

Chemical formula

[0012] According to an embodiment of the present invention, if the total molar amount of cyano groups (-CN) in the nitrile compound is x and the total molar amount of the nitrile compound is y, then the cyano group content ratio x / y satisfies 2.16 ≤ x / y ≤ 2.71.

[0013] According to an embodiment of the present invention, the cyano group content x / y, the content w1 of the carboxylic acid ester compound represented by formula (I), and the content w2 of the fluoroethylene carbonate are 2w1 2 -0.01w1+2.3>x / y>27w2 2 It satisfies -1.2w2+2.1.

[0014] According to embodiments of the present invention, the electrolyte comprises a lithium salt, the lithium salt comprising at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, LiSiF6, LiBOB, and LiDFOB.

[0015] According to another aspect of the present invention, the present invention further provides an electrochemical apparatus comprising the electrolyte described in the above-described embodiment of the present invention.

[0016] According to an embodiment of the present invention, the electrochemical apparatus further includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode, wherein the positive electrode, the negative electrode, and the separator are wound together to form a cell, and the length L and width W of the cell satisfy 20 mm ≤ L ≤ 300 mm, 20 mm ≤ W ≤ 100 mm, and 1 ≤ L / W ≤ 4.

[0017] According to embodiments of the present invention, the electrochemical apparatus satisfies at least one of the following: a) 1 ≤ L / W ≤ 3, b) 2 ≤ L / W ≤ 3, and c) 2 ≤ L / W ≤ 4.

[0018] According to an embodiment of the present invention, the electrochemical apparatus further includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode, wherein the positive electrode, the negative electrode, and the separator are wound together to form a cell, and the thickness T and width W of the cell satisfy 2 mm ≤ T ≤ 12 mm and W / T ≥ 5.

[0019] According to embodiments of the present invention, the electrochemical apparatus satisfies at least one of d) 5 ≤ W / T ≤ 25, e) 5 ≤ W / T ≤ 20, f) 5 ≤ W / T ≤ 15, and g) 10 ≤ W / T ≤ 25.

[0020] According to embodiments of the present invention, the electrochemical apparatus further comprises a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode, wherein the positive electrode, the negative electrode, and the separator are wound to form a cell, and the length L and width W of the cell, and the content w1 of the carboxylic acid ester compound represented by formula (I), satisfy w1 × 100 / (L / W) ≥ 10.

[0021] According to an embodiment of the present invention, the electrochemical apparatus satisfies at least one of the following conditions: h) 10 ≤ w1 × 100 / (L / W) ≤ 40, i) 20 ≤ w1 × 100 / (L / W) ≤ 30, j) 20 ≤ w1 × 100 / (L / W) ≤ 40, and k) 15 ≤ w1 × 100 / (L / W) ≤ 30.

[0022] According to another aspect of the present invention, the present invention further provides an electronic apparatus including the electrochemical apparatus described in the above-described embodiment of the present invention. [Brief explanation of the drawing]

[0023] Below, as embodiments of the present invention are described, drawings necessary to illustrate embodiments of the present invention or the prior art will be briefly described. Clearly, the drawings in the following description are merely some embodiments of the present application, and those skilled in the art can obtain other drawings based on these without progressive work. [Figure 1] Figure 1 shows the relationship between the cyano group content ratio x / y and the carboxylic acid ester compound content w1. [Figure 2] Figure 2 shows the relationship between the cyano group content ratio x / y and the fluoroethylene carbonate (FEC) content w2. [Figure 3] Figure 3 shows the length L, width W, and thickness T of the packaged cell. [Modes for carrying out the invention]

[0024] The following describes in detail embodiments of the present invention. These embodiments should not be construed as limiting the present invention.

[0025] As used in this application, the terms “include,” “contain,” and “incorporate” are intended to have an open and non-restrictive meaning.

[0026] In this specification, quantities, ratios, and other numerical values ​​may be presented in range form. Such range forms are for convenience and conciseness and should be interpreted flexibly. Such range forms include not only the numerical value explicitly designated as the range limit, but also all individual numerical values ​​or subranges included within the range, which is equivalent to each individual numerical value or subrange being explicitly designated.

[0027] In the embodiments and claims for carrying out the invention, the terms “at least one of,” “at least one of,” “at least one type of,” or any list of items connected by other similar terms, mean any combination of the listed items. For example, if items A and B are listed, the phrase “at least one of A and B” means A only, B only, or A and B. In other specific examples, if items A, B, and C are listed, the phrase “at least one of A, B, and C” means A only, B only, C only, A and B (excluding C), A and C (excluding B), B and C (excluding A), or all of A, B, and C. Item A may consist of a single element or more elements. Item B may consist of a single element or more elements. Item C may consist of a single element or more elements.

[0028] The term "alkyl group" includes both linear and branched alkyl groups. For example, alkyl groups may be C1-C50 alkyl groups, C1-C40 alkyl groups, C1-C30 alkyl groups, C1-C20 alkyl groups, C1-C12 alkyl groups, C1-C10 alkyl groups, C1-C6 alkyl groups, C2-C6 alkyl groups, and C2-C5 alkyl groups. In some examples, alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl, and octyl. Alkyl groups may also be optionally substituted.

[0029] The term "alkenyl group" includes both linear and branched alkenyl groups. For example, the alkenyl group may be a C2-C50 alkenyl group, a C2-C40 alkenyl group, a C2-C30 alkenyl group, a C2-C20 alkenyl group, a C2-C12 alkenyl group, a C2-C10 alkenyl group, or a C2-C6 alkenyl group. The alkenyl group may also be optionally substituted.

[0030] The term "aryl group" encompasses both monocyclic and polycyclic groups. A polycyclic group may consist of two or more rings in which two carbon atoms are shared by two adjacent rings (these rings are "fused rings"), at least one of which is an aromatic ring, and the other rings may be, for example, a cycloalkyl group, a cycloalkenyl group, an aryl group, a heterocyclyl group, and / or a heteroaryl group. For example, an aryl group may be a C6-C50 aryl group, a C6-C40 aryl group, a C6-C30 aryl group, a C6-C20 aryl group, or a C6-C10 aryl group. The aryl group may also be optionally substituted.

[0031] The term "alkoxy group" refers to an organic group having -O-R1, where R1 is the linear or branched alkyl group described above.

[0032] The term "aryloxy group" refers to an organic group having -O-R2, where R2 is the aforementioned aryl group.

[0033] The term "alkylene group" includes both linear and branched alkylene groups. For example, the alkylene group may be a C1-C50 alkylene group, a C1-C40 alkylene group, a C1-C30 alkylene group, a C1-C20 alkylene group, a C1-C10 alkylene group, a C1-C6 alkylene group, a C2-C6 alkylene group, or a C2-C5 alkylene group. Furthermore, the alkylene group may be optionally substituted.

[0034] The term "alkenylene group" may refer to linear alkenylene groups or branched alkenylene groups. For example, the alkenylene group may be a C2-C50 alkenylene group, a C2-C40 alkenylene group, a C2-C30 alkenylene group, a C2-C20 alkenylene group, a C2-C10 alkenylene group, a C1-C6 alkenylene group, or a C2-C6 alkenylene group. Furthermore, the alkenylene group may be optionally substituted.

[0035] The term "heterocyclylene group" includes, but is not limited to, aziridine groups, oxirane groups (epoxides, ethylene oxides), ethylene sulfide groups (episulfide groups), dioxirane groups, azetidine groups, oxetane groups, thietan groups, dioxetane groups, dithietan groups, dithieto groups, azolidine groups, pyrrolidine groups, pyrroline groups, oxolane groups, dihydrofuran groups, and furan groups.

[0036] If the group is substituted, the substituent can be independently selected from the group consisting of alkyl groups, alkenyl groups, aryl groups, alkoxy groups, aryloxy groups, silane groups, siloxane groups, amino groups, ether groups, ester groups, carboxyl groups, sulfonic acid groups, mercapto groups, cyano groups, halogens, and combinations thereof.

[0037] I, electrolyte The electrolyte, as a crucial component of an electrochemical apparatus, is used to transport lithium ions between the positive and negative electrodes, ensuring that lithium ions are constantly absorbed and released into and from the positive and negative electrode materials, thereby performing the charging and discharging functions. Therefore, the electrolyte has a critical influence on the electrochemical properties of the electrochemical apparatus.

[0038] To improve the rapid charging characteristics of electrochemical devices, the present invention enhances the transport rate of lithium ions in the electrolyte by adding a carboxylic acid ester compound with lower viscosity to the electrolyte. However, the present invention has further found that carboxylic acid ester compounds have a narrow electrochemical window and poor high-temperature stability. For example, under the intermittent operating conditions of high-temperature storage and charge-discharge cycles in electronic devices (e.g., laptop computers), the carboxylic acid ester compound reacts at the negative electrode, consuming active lithium, destroying the solid electrolyte interface (SEI) film on the negative electrode surface, and resulting in a rapid decay of battery capacity.

[0039] To effectively mitigate the breakdown of the negative electrode SEI film by carboxylic acid ester compounds and to repair the negative electrode SEI film in a timely manner, the present invention further adds fluoroethylene carbonate (FEC) to the electrolyte. However, the present invention has further found that when the electrochemical apparatus is under high-temperature storage and intermittent operation conditions of charge-discharge cycles, the structure of the positive electrode becomes more susceptible to breakdown, an oxygen release reaction occurs, at which point the FEC is easily oxidized and decomposed, generating CO2, and as a result the electrochemical apparatus swells due to gas generation.

[0040] However, the present invention has unexpectedly discovered that by adjusting the content and ratio of carboxylic acid ester compounds and fluoroethylene carbonate in the electrolyte, the rapid charging characteristics of an electrochemical apparatus can be effectively improved without degrading, or only slightly degrading, the high-temperature interval cycle characteristics of the electrochemical apparatus. In some examples, when the content of carboxylic acid ester compounds and fluoroethylene carbonate is w1 and w2, respectively, based on the total weight of the electrolyte, the following conditions are met: 5% ≤ w1 ≤ 60%, 2% ≤ w2 ≤ 12%, and 2 ≤ w1 / w2 ≤ 20.

[0041] In some embodiments, w1 may be 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, or 60%, and may be within the range of any two of the above values, but is not limited to these. For example, 10% ≤ w1 ≤ 50% or 15% ≤ w1 ≤ 50%.

[0042] In some embodiments, w2 may be 2%, 4%, 6%, 8%, 10%, or 12%, and may be within the range of any two of the above values, but is not limited to these. For example, 4% ≤ w2 ≤ 12% or 4% ≤ w2 ≤ 10%.

[0043] In some embodiments, w1 / w2 may be 2, 4, 6, 8, 10, 12, 14, 16, 18, or 20, and may be within the range of any two of the above numbers, but is not limited to these. For example, 4 ≤ w1 / w2 ≤ 16 or 4 ≤ w1 / w2 ≤ 10.

[0044] In some examples, the carboxylic acid ester compound is a carboxylic acid ester compound represented by the following formula (I): [ka] R 11 R comprises at least one of hydrogen, a hydroxyl group, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C2-C20 linear alkenyl group, a C6-C30 aryl group, and a C6-C30 aryloxy group. 12 It comprises at least one of a C1-C20 alkyl group, a C2-C20 linear alkenyl group, and a C6-C30 aryl group.

[0045] In some examples, the carboxylic acid ester compound represented by formula (I) includes at least one of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, n-butyl propionate, isobutyl propionate, n-amyl propionate, isoamyl propionate, ethyl n-butyrate, n-propyl n-butyrate, propyl isobutyrate, n-amyl n-butyrate, n-amyl isobutyrate, n-butyl n-butyrate, isobutyl isobutyrate, and n-amyl n-valerate.

[0046] In some examples, the carboxylic acid ester compound represented by formula (I) contains at least propyl propionate. Compared to other carboxylic acid ester compounds, propyl propionate is advantageous for stabilizing the cathode structure, thereby improving the rapid charging characteristics of the electrochemical apparatus, improving high-temperature ITC characteristics, and suppressing gas generation, thereby improving the overall characteristics of the electrochemical apparatus.

[0047] In some examples, the carboxylic acid ester compound represented by formula (I) includes ethyl propionate and ethyl acetate. In some examples, the carboxylic acid ester compound represented by formula (I) includes propyl propionate and ethyl acetate. In some examples, the carboxylic acid ester compound represented by formula (I) includes propyl propionate and ethyl propionate. In some examples, the carboxylic acid ester compound represented by formula (I) includes ethyl acetate, ethyl propionate, and propyl propionate.

[0048] In some embodiments, the electrolyte further contains a nitrile compound. The nitrile compound contains a cyano (-CN) functional group. In some embodiments, when the content of the nitrile compound is w3 based on the total weight of the electrolyte, 0.1% ≤ w3 ≤ 12%. In some embodiments, w3 may be 0.1%, 1%, 2%, 4%, 6%, 8%, 10%, or 12%, and may be within the range of any two of the above values, but is not limited to these. When the content of the nitrile compound is within the above range, the high-temperature ITC characteristics of the electrochemical apparatus can be improved and gas generation suppressed, while considering the rapid charging characteristics of the electrochemical apparatus. This is because the nitrile compound forms a nitrile protective film with excellent properties on the surface of the positive electrode, stabilizing the active metal in the positive electrode active material well, suppressing the elution of the active metal, and reducing the oxygen release reaction.

[0049] In some examples, the nitrile compound comprises at least one of the compounds represented by formulas (II) to (V). [ka] R 21 It comprises at least one of a substituted or unsubstituted C1-C12 alkylene group and a substituted or unsubstituted C1-C12 alkylene oxy group, R 31 , R 32Each independently comprises hydrogen and at least one of substituted or unsubstituted C1-C12 alkylene groups. R 41 , R 42 , R 43 Each independently comprises at least one of hydrogen, a substituted or unsubstituted C1-C12 alkylene group, and a substituted or unsubstituted C1-C12 alkylene oxy group. R 51 It comprises at least one of the following: a substituted or unsubstituted C1-C12 alkylene group, a substituted or unsubstituted C2-C12 alkenylene group, a substituted or unsubstituted C6-C26 arylene group, and a substituted or unsubstituted C2-C12 heterocyclylene group, wherein the heteroatom is at least one of N, S, and O. In the case of substitution, the substituent is a halogen.

[0050] In some examples, the nitrile compound includes at least one of adiponitrile, succinonitrile, glutalonitrile, malononitrile, 2-methylglutalonitrile, pimeronitrile, sebaconitrile, azelanitrile, 1,4-dicyano-2-butene, ethylene glycol bis(propionitrile) ether, 3,3'-oxydipropionitrile, thiodipropionitrile, 2-hexendinitrile, butenedinitrile, 2-pentenedinitrile, ethylsuccinonitrile, 3-hexendinitrile, 2-methyleneglutalonitrile, 4-cyanopimeronitrile, 1,3,6-hexanetricarbonitride, 1,3,5-hexanetricarbonitride, 1,2,3-propanetricarbonitride, and 1,2,3-tris(2-cyanoethoxy)propane.

[0051] This invention evaluates the effect of cyano group content on electrochemical properties. Here, cyano group content is the ratio of the total molar amount x of cyano groups (-CN) in a nitrile compound to the total molar amount y of the nitrile compound. This invention found that, compared to adding a single nitrile compound, such as a dinitrile compound (i.e., x / y=2) or a trinitrile compound (i.e., x / y=3), to the electrolyte, satisfying a cyano group content x / y of 2.16 ≤ x / y ≤ 2.71 significantly improves the high-temperature ITC characteristics of the electrochemical apparatus, suppresses gas generation, and greatly reduces the adverse effects of nitrile compounds on the rapid charging characteristics of the electrochemical apparatus. In other words, it is possible to simultaneously improve both rapid charging characteristics and high-temperature ITC characteristics. This is presumed to be because, compared to a thick SEI film made of a high-molecular-weight nitrile compound with many cyano groups (e.g., trinitrile compound) and an unstable SEI film made of a small-molecule nitrile compound with few cyano groups (e.g., dinitrile compound), adding multiple nitrile compounds with different numbers of cyano groups to the electrolyte allows for the simultaneous formation of a nitrile-containing SEI film on the positive electrode surface, which is a composite of high-molecular-weight and small-molecule compounds, resulting in a superior effect.

[0052] Furthermore, the present invention further investigated the relationship between the content w1 of the carboxylic acid ester compound, the content w2 of fluoroethylene carbonate, and the cyano group content ratio x / y. Specifically, the curve shown by the circular dots in Figure 1 represents x / y = 2w1 2 -0.01w1+2.3, but the curve indicated by the square dots in Figure 2 is x / y=27w2 2 -1.2w2 + 2.1. In research, the present invention is based on the cyano group content ratio x / y > 2w1 2 We found that when the ratio is -0.01w1 + 2.3, the concentration of cyano groups increases, which to some extent improves the viscosity of the electrolyte, inhibiting lithium ion transport and the intercalation and release of lithium ions in the positive and negative electrode active materials. This increases the probability that lithium ions will precipitate at the positive and negative electrodes and form lithium dendrites. Furthermore, we found that the cyano group content ratio x / y < 27w2 2We found that when the ratio is -1.2w2+2.1, the concentration of cyano groups decreases, resulting in slightly inferior structural stability of the SEI film formed on the cathode active surface, which increases the probability of blistering due to gas generation.

[0053] Therefore, the relationship between the content w1 of carboxylic acid ester compounds, the content w2 of fluoroethylene carbonate, and the cyano group content x / y is 2w1 2 -0.01w1+2.3>x / y>27w2 2 Satisfying -1.2w2+2.1 improves the rapid charging characteristics of the electrochemical apparatus by maintaining the viscosity of the electrolyte within a more appropriate range, improving lithium ion transport in the electrolyte, and significantly reducing the risk of lithium deposition. Furthermore, it improves the high-temperature ITC characteristics of the electrochemical apparatus and suppresses gas generation by strengthening the complexing protection of nitrile compounds against transition metals in the positive electrode active material, reducing oxygen release from the positive electrode under high-temperature intermittent cycle operating conditions, and improving the structural stability of the positive electrode. In other words, the electrochemical apparatus should be 2w1 2 -0.01w1+2.3>x / y>27w2 2 Satisfying the -1.2w2+2.1 condition simultaneously improves the rapid charging characteristics and high-temperature ITC characteristics of the electrochemical apparatus while suppressing gas generation.

[0054] In some embodiments, the electrolyte according to the present invention further comprises a lithium salt. Examples of lithium salts include inorganic lithium salts such as LiPF6, LiBF4, LiClO4, LiAlF4, LiSbF6, and LiWF7; lithium tungstate systems such as LiWOF5; lithium carboxylate systems such as HCO2Li, CH3CO2Li, CH2FCO2Li, CHF2CO2Li, CF3CO2Li, CF3CH2CO2Li, CF3CF2CO2Li, CF3CF2CF2CO2Li, and CF3CF2CF2CF2CO2Li; and FSO3Li, CH3SO3Li, and CH2FSO3L i, lithium sulfonate salts such as CHF2SO3Li, CF3SO3Li, CF3CF2SO3Li, CF3CF2CF2SO3Li, CF3CF2CF2CF2SO3Li; LiN(FCO)2, LiN(FCO)(FSO2), LiN(FSO2)2, LiN(FSO2)(CF3SO2), LiN(CF3SO2)2, LiN(C2F5SO2)2, cyclic 1,2-perfluoroethanedisulfonyliimide lithium, cyclic 1,3-perfluoropropanedisulfonyliimide lithium, LiN Lithium imide salts such as (CF3SO2)(C4F9SO2); methylated lithium salts such as LiC(FSO2)3, LiC(CF3SO2)3, LiC(C2F5SO2)3; lithium malonate salts such as lithium bis(malonate)borate and lithium difluoro(malonate)borate; lithium tris(malonate)phosphate, lithium difluorobis(malonate)phosphate, and lithium tetrafluoro(malonate)phosphate. Thium salts; and fluorine-containing organolithium salts such as LiPF4(CF3)2, LiPF4(C2F5)2, LiPF4(CF3SO2)2, LiPF4(C2F5SO2)2, LiBF3CF3, LiBF3C2F5, LiBF3C3F7, LiBF2(CF3)2, LiBF2(C2F5)2, LiBF2(CF3SO2)2, LiBF2(C2F5SO2)2; lithium oxalate borate salts such as lithium difluoro(oxalate)borate and lithium bis(oxalate)borate;This may include, but is not limited to, lithium tetrafluorooxalate phosphate, lithium difluorobis(oxalate) phosphate, lithium tris(oxalate) phosphate, and other oxalate phosphate lithium salt systems.

[0055] In some examples, the lithium salt comprises at least one of LiPF6, LiBF4, LiAsF6, LiClO4, LiB(C6H5)4, LiCH3SO3, LiCF3SO3, LiN(SO2CF3)2, LiC(SO2CF3)3, LiSiF6, LiBOB, and LiDFOB.

[0056] In some examples, the lithium salt content, based on the total weight of the electrolyte, is 0.01wt% to 20wt%, 0.01wt% to 10wt%, 0.01wt% to 5wt%, 0.01wt% to 3wt%, 0.1wt% to 20wt%, 0.1wt% to 10wt%, 0.1wt% to 5wt%, 0.1wt% to 3wt%, 1wt% to 20wt%, 1wt% to 10wt%, 1wt% to 5wt%, or 1wt% to 3wt%.

[0057] In some embodiments, the electrolyte further comprises one of the non-aqueous solvents used as solvents for electrolytes known in the prior art.

[0058] In some examples, the non-aqueous solvent includes, but is not limited to, one or more of cyclic carbonates, linear carbonates, cyclic ethers, linear ethers, phosphorus-containing organic solvents, sulfur-containing organic solvents, and aromatic fluorine-containing solvents.

[0059] In some examples, the cyclic carbonate may include, but is not limited to, one or more of ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate. In some examples, the cyclic carbonate has 3 to 6 carbon atoms.

[0060] In some examples, the chain carbonate may include, but is not limited to, one or more chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate (DEC), methyl-n-propyl carbonate, ethyl-n-propyl carbonate, and di-n-propyl carbonate. The fluorine-substituted chain carbonate may include, but is not limited to, one or more chain carbonates such as bis(fluoromethyl) carbonate, bis(difluoromethyl) carbonate, bis(trifluoromethyl) carbonate, bis(2-fluoroethyl) carbonate, bis(2,2-difluoroethyl) carbonate, bis(2,2,2-trifluoroethyl) carbonate, 2-fluoroethylmethyl carbonate, 2,2-difluoroethylmethyl carbonate, and 2,2,2-trifluoroethylmethyl carbonate.

[0061] In some examples, the cyclic ether may include, but is not limited to, one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 2-methyl-1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, and dimethoxypropane.

[0062] In some examples, the examples of the chain ether may include, but are not limited to, one or more of dimethoxyethane, 1,1-dimethoxyethane, 1,2-dimethoxyethane, diethoxyethane, 1,1-diethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 1,1-ethoxymethoxyethane, and 1,2-ethoxymethoxyethane.

[0063] In some examples, the phosphorus-containing organic solvent may include, but is not limited to, one or more of the following: trimethyl phosphate, triethyl phosphate, dimethylethyl phosphate, methyldiethyl phosphate, methylethylene phosphate, ethylethylene phosphate, triphenyl phosphate, triethyl phosphate, triphenyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, and tris(2,2,3,3,3-pentafluoropropyl) phosphate.

[0064] In some examples, the sulfur-containing organic solvent may include, but is not limited to, one or more of sulfolane, 2-methylsulfolane, 3-methylsulfolane, dimethylsulfone, diethylsulfone, ethylmethylsulfone, methylpropylsulfone, dimethyl sulfoxide, methyl methanesulfonate, ethyl methanesulfonate, methyl ethanesulfonate, and ethyl ethanesulfonate. In some examples, some of the hydrogen atoms in the sulfur-containing organic solvent may be substituted with fluorine.

[0065] In some examples, the aromatic fluorine-containing solvent includes, but is not limited to, one or more of fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, and trifluoromethylbenzene.

[0066] II, Positive electrode The positive electrode comprises a positive electrode current collector and a positive electrode active material layer placed on at least one surface of the positive electrode current collector, the positive electrode active material layer containing positive electrode active material. The positive electrode active material layer may be a single layer or multiple layers. Each layer of the multiple positive electrode active material layers may contain the same or different positive electrode active material. The positive electrode active material is any material capable of reversibly intercepting and releasing metal ions such as lithium ions.

[0067] The type of positive electrode active material is not limited and should be capable of electrochemically intercalating and releasing metal ions (e.g., lithium ions). In some examples, the positive electrode active material contains lithium and at least one transition metal. Examples of positive electrode active materials may include, but are not limited to, lithium transition metal composite oxides and lithium-containing transition metal phosphate compounds.

[0068] In some examples, the transition metal in lithium transition metal composite oxides includes V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. In some examples, the lithium transition metal composite oxide is lithium cobalt composite oxide such as LiCoO2, lithium nickel composite oxide such as LiNiO2, lithium manganese composite oxide such as LiMnO2, LiMn2O4, Li2MnO4, LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, LiLiLi 0.5 Mn 0.3 Co 0.2 Lithium transition metal composite oxides include lithium nickel manganese cobalt composite oxides such as O2, and some of the transition metal atoms that make up these lithium transition metal composite oxides are substituted with other elements such as Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W. An example of a lithium transition metal composite oxide is LiNi 0.5 Mn 0.5 O2, LiLiLi 0.85 Co 0.10 Al 0.05 O2, LiLiLi 0.33 Co 0.33 Mn 0.33 O2, LiLiLi 0.45 Co 0.10 Al 0.45 O2, LiMn 1.8 Al 0.2 O4 and LiMn 1.5 Ni 0.5It may include, but is not limited to, O4, etc. Examples of lithium transition metal composite oxide combinations include, but are not limited to, the combination of LiCoO2 and LiMn2O4, and some of the Mn in LiMn2O4 may be substituted with a transition metal (for example, LiNi 0.33 Co 0.33 Mn 0.33 In O2, some of the Co in LiCoO2 may be substituted with a transition metal.

[0069] In some examples, the transition metals in lithium-containing transition metal phosphate compounds include V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. In some examples, lithium-containing transition metal phosphate compounds include iron phosphate-based compounds such as LiFePO4, Li3Fe2(PO4)3, and LiFeP2O7, and cobalt phosphate-based compounds such as LiCoPO4. Some of the transition metal atoms that make up these lithium transition metal phosphate compounds are substituted with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, and Si.

[0070] A substance with a different composition may be attached to the surface of the positive electrode active material. Examples of substances attached to the surface include oxides such as aluminum oxide, silica, titanium dioxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulfates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; and carbon, but are not limited to these. By attaching a substance to the surface of the positive electrode active material, the oxidation reaction of the electrolyte on the surface of the positive electrode active material can be suppressed, and the lifespan of the electrochemical apparatus can be improved. If the amount of substance attached to the surface is too small, the effect cannot be fully exerted, but if the amount of substance attached to the surface is too large, the inflow and outflow of lithium ions may be inhibited, which may increase resistance. In this invention, a positive electrode active material with a substance with a different composition attached to its surface is also referred to as a "positive electrode active material".

[0071] In some examples, it is preferable to use lithium cobaltate or lithium nickelcobaltmanganate as the "positive electrode active material".

[0072] In some embodiments, the shape of the positive electrode active material particles includes, but is not limited to, lumpy, polyhedral, spherical, ellipsoidal, plate-like, needle-like, and columnar shapes. In some embodiments, the positive electrode active material particles include primary particles, secondary particles, or a combination thereof. In some embodiments, primary particles may aggregate to form secondary particles.

[0073] The positive electrode further includes a positive electrode conductive material to improve its conductivity. The type of positive electrode conductive material is not limited, and any known conductive material may be used. Examples of positive electrode conductive materials include, but are not limited to, graphite such as natural graphite and artificial graphite; carbon black such as acetylene black; carbon materials such as amorphous carbon such as needle coke; carbon nanotubes; graphene, etc. The positive electrode conductive materials may be used individually or in any combination.

[0074] The type of solvent used to form the positive electrode slurry is not limited; any solvent capable of dissolving or dispersing the positive electrode active material, conductive material, positive electrode binder, and any thickener used as needed is acceptable. Examples of solvents for forming the positive electrode slurry may include either an aqueous solvent or an organic solvent. Examples of aqueous solvents may include, but are not limited to, water and mixed solvents of alcohol and water. Examples of organic solvents may include, but are not limited to, aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N,N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide, and tetrahydrofuran (THF); amides such as N-methylpyrrolidone (NMP), dimethylformamide, and dimethylacetamide; and aprotic polar solvents such as hexamethylphosphoramide and dimethyl sulfoxide.

[0075] Thickening agents are generally used to adjust the viscosity of slurries. When using aqueous solvents, slurries may be formed using a thickening agent and a styrene-butadiene rubber (SBR) emulsion. The type of thickening agent is not particularly limited and may include, but is not limited to, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. The thickening agents may be used alone or in any combination.

[0076] The type of positive electrode current collector is not particularly limited, but may be any material known to be suitably used as a positive electrode current collector. Examples of positive electrode current collectors include, but are not limited to, metallic materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; and carbon materials such as carbon cloth and carbon paper. In some embodiments, the positive electrode current collector is made of a metallic material. In some embodiments, the positive electrode current collector is made of aluminum.

[0077] To reduce the electrical contact resistance between the positive electrode current collector and the positive electrode active material layer, the surface of the positive electrode current collector may contain a conductive additive. Examples of conductive additives include, but are not limited to, carbon and precious metals such as gold, platinum, and silver.

[0078] A positive electrode can be manufactured by forming a positive electrode active material layer containing a positive electrode active material and a binder on a current collector. The manufacture of a positive electrode using a positive electrode active material can be carried out by conventional methods. Specifically, the positive electrode active material and binder, along with conductive materials and thickeners as needed, are dry-mixed and formed into a sheet. The resulting sheet is then pressed onto a positive electrode current collector, or these materials are dissolved or dispersed in a liquid solvent to form a slurry. This slurry is then applied to the positive electrode current collector and dried to form a positive electrode active material layer on the current collector, thereby obtaining the positive electrode.

[0079] In some embodiments, when the weight fraction of the positive electrode active material is M% based on the total weight of the positive electrode active material layer, the relationship is 90 ≤ M ≤ 99.5. In some embodiments, the relationship is 95 ≤ M ≤ 99. In some embodiments, M may be 90, 92, 94, 95, 96, 97, 98, or 99, and may be within the range of any two of the above values. When the weight fraction of the positive electrode active material in the positive electrode active material layer satisfies the above relationship, the energy density of the electrochemical apparatus can be significantly improved.

[0080] III, negative electrode The negative electrode comprises a negative electrode current collector and a negative electrode active material layer placed on at least one surface of the negative electrode current collector, the negative electrode active material layer comprising a negative electrode active material. The negative electrode active material layer may be a single layer or multiple layers, and each layer of the multiple negative electrode active material may contain the same or different negative electrode active material. The negative electrode active material is any material capable of reversibly intercalating and releasing metal ions such as lithium ions. In some embodiments, the rechargeable capacity of the negative electrode active material is greater than the discharge capacity of the positive electrode active material to prevent lithium metal from unintentionally depositing on the negative electrode during charging.

[0081] Any known current collector may be used as the current collector that holds the negative electrode active material. Examples of negative electrode current collectors include, but are not limited to, metallic materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. In some embodiments, the negative electrode current collector is made of copper.

[0082] When the negative electrode current collector is made of a metallic material, the form of the negative electrode current collector may include, but is not limited to, metal foil, metal cylinder, metal strip coil, metal plate, metal film, expanded metal, punched metal, foamed metal, etc. In some embodiments, the negative electrode current collector is a metal film. In some embodiments, the negative electrode current collector is copper foil. In some embodiments, the negative electrode current collector is rolled copper foil produced by a rolling method or electrolytic copper foil produced by an electrolytic method.

[0083] In some embodiments, the thickness of the negative electrode current collector is greater than 1 μm or greater than 5 μm. In some embodiments, the thickness of the negative electrode current collector is less than 100 μm or less than 50 μm. In some embodiments, the thickness of the negative electrode current collector is within the range of any two of the above values.

[0084] The negative electrode active material is not limited, but it should be capable of reversibly intercalating and releasing lithium ions. Examples of negative electrode active materials include, but are not limited to, carbon materials such as natural graphite and artificial graphite; metals such as silicon (Si) and tin (Sn); or oxides of metallic elements such as Si and Sn. The negative electrode active material may be used alone or in any combination.

[0085] The negative electrode active material layer may further contain a negative electrode binder. The negative electrode binder can improve the bonding between negative electrode active material particles and the bonding between the negative electrode active material and the current collector. The type of negative electrode binder is not limited, but any material that is stable to the solvent used in the manufacture of the electrolyte or electrode is acceptable. In some examples, the negative electrode binder includes a resin binder. Examples of resin binders include, but are not limited to, fluororesins, polyacrylonitrile (PAN), polyimide resins, acrylic acid resins, and polyolefin resins. When preparing a slurry of the negative electrode mixture using an aqueous solvent, the negative electrode binder includes, but is not limited to, carboxymethylcellulose (CMC) or its salts, styrene-butadiene rubber (SBR), polyacrylic acid (PAA) or its salts, and polyvinyl alcohol.

[0086] The negative electrode can be manufactured by the following method: A slurry of a negative electrode mixture containing negative electrode active material and a resin binder is applied to a negative electrode current collector, dried, and then rolled to form a negative electrode active material layer on both sides of the negative electrode current collector, thereby obtaining the negative electrode.

[0087] IV, Separator To prevent short circuits, a separator is generally installed between the positive and negative electrodes. In this case, the electrolyte of the present invention is generally used by permeating this separator.

[0088] The material and shape of the separator are not limited, as long as they do not significantly impair the effects of the present invention. The separator may be a resin, glass fiber, inorganic material, etc., formed from a material stable with respect to the electrolyte of the present invention. In some embodiments, the separator includes porous sheets or nonwoven fabrics with excellent liquid retention properties. Examples of materials for resin or glass fiber separators include, but are not limited to, polyolefins, aromatic polyamides, polytetrafluoroethylenes, and polyethersulfones. In some embodiments, the polyolefin is polyethylene or polypropylene. In some embodiments, the polyolefin is polypropylene. The materials of the separator may be used individually or in any combination.

[0089] The separator may be made of materials laminated together as described above, and examples include, but are not limited to, a three-layer separator made of polypropylene, polyethylene, and polypropylene laminated in that order.

[0090] Examples of inorganic materials may include, but are not limited to, oxides such as aluminum oxide and silica, nitrides such as aluminum nitride and silicon nitride, and sulfates (e.g., barium sulfate, calcium sulfate, etc.). The form of the inorganic material may include, but is not limited to, particulate or fibrous forms.

[0091] The separator may be in the form of a film, and examples include, but are not limited to, nonwoven fabrics, woven fabrics, and microporous membranes. When the separator is in the form of a film, the pore size is 0.01 μm to 1 μm and the thickness is 5 μm to 50 μm. In addition to the above independent film-like separator, a separator may be used in which a composite porous layer containing the above inorganic particles is formed on the surface of the positive electrode and / or negative electrode using a resin-based binder. For example, a separator may be used in which a porous layer is formed on both sides of the positive electrode using fluororesin as the binder and aluminum oxide particles, 90% of which have a particle size of less than 1 μm.

[0092] The thickness of the separator is arbitrary. In some embodiments, the thickness of the separator is greater than 1 μm, greater than 5 μm, or greater than 8 μm. In some embodiments, the thickness of the separator is less than 50 μm, less than 40 μm, or less than 30 μm. In some embodiments, the thickness of the separator is within the range of any two of the above values. When the thickness of the separator is within the above range, insulating properties and mechanical strength can be ensured, and the rate characteristics and energy density of the electrochemical apparatus can be ensured.

[0093] When a porous material such as a porous sheet or nonwoven fabric is used as a separator, the porosity of the separator is arbitrary. In some embodiments, the porosity of the separator is greater than 10%, greater than 15%, or greater than 20%. In some embodiments, the porosity of the separator is less than 60%, less than 50%, or less than 45%. In some embodiments, the porosity of the separator is within the range of any two of the above values. When the porosity of the separator is within the above range, insulation and mechanical strength can be ensured, sheet resistance can be suppressed, and good safety characteristics can be provided to the electrochemical apparatus.

[0094] The average pore diameter of the separator is also arbitrary. In some embodiments, the average pore diameter of the separator is less than 0.5 μm or less than 0.2 μm. In some embodiments, the average pore diameter of the separator is greater than 0.05 μm. In some embodiments, the average pore diameter of the separator is within the range of any two of the above values. If the average pore diameter of the separator exceeds the above range, short circuits are more likely to occur. If the average pore diameter of the separator is within the above range, the electrochemical apparatus can be given good safety characteristics.

[0095] V, Electrochemical apparatus The electrochemical apparatus according to the present invention includes any apparatus in which an electrochemical reaction occurs, and specific examples include a lithium metal secondary battery or a lithium ion secondary battery. The electrochemical apparatus according to the present invention includes the electrolyte described in the above examples. In some examples, the electrochemical apparatus according to the present invention further includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode.

[0096] Considering the design space allocated for electrochemical devices in laptops, these devices generally tend to have an elongated shape. Elongated batteries are prone to lithium deposition at the top and bottom edges when charged at room or low temperatures due to uneven current distribution and uneven SEI film formation, leading to capacity degradation. Furthermore, deposited lithium dendrites can puncture the separator between the positive and negative electrodes, short-circuiting the battery and potentially causing safety issues.

[0097] In some embodiments, a cell is formed by winding a positive electrode, a negative electrode, and a separator. In some embodiments, a cell is formed by stacking a positive electrode, a negative electrode, and a separator.

[0098] This invention has found that by adjusting the cell size, the charge rate window of an electrochemical apparatus can be improved, thereby improving lithium deposition and thus enhancing the rapid charging characteristics of the electrochemical apparatus.

[0099] In some embodiments, the cell length L and width W satisfy 20mm ≤ L ≤ 300mm, 20mm ≤ W ≤ 100mm, and 1 ≤ L / W ≤ 4. In some embodiments, the cell length L may be 20mm, 50mm, 75mm, 100mm, 125mm, 150mm, 175mm, 200mm, 225mm, 250mm, 275mm, or 300mm, and may be within the range of any two of the above values, but is not limited thereto. In some embodiments, the cell width W may be 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, or 100mm, and may be within the range of any two of the above values, but is not limited thereto. In some embodiments, the cell aspect ratio L / W may be 1, 2, 3, or 4, and may be within the range of any two of the above values, but is not limited thereto.

[0100] In some embodiments, the cell thickness T satisfies 2 mm ≤ T ≤ 12 mm. In some embodiments, the cell thickness T may be 2, 4, 6, 8, 10, or 12, and may be within the range of any two of the above values, but is not limited to these. In some embodiments, the cell width-to-thickness ratio W / T satisfies W / T ≥ 5. In some embodiments, the cell width-to-thickness ratio W / T satisfies W / T ≤ 25. In some embodiments, W / T may be 5, 10, 15, 20, or 25, and may be within the range of any two of the above values, but is not limited to these.

[0101] In some embodiments, the charge rate window of the electrochemical apparatus can be further improved and lithium deposition improved by designing the size of the battery and optimizing the content of the carboxylic acid ester compound in the electrolyte, thereby further improving the rapid charging characteristics of the electrochemical apparatus. In some embodiments, the cell length L and width W, and the content w1 of the carboxylic acid ester compound represented by formula (I) satisfy w1 × 100 / (L / W) ≥ 10. In some embodiments, the cell length L and width W, and the content w1 of the carboxylic acid ester compound represented by formula (I) satisfy w1 × 100 / (L / W) ≤ 40. In some embodiments, w1 × 100 / (L / W) may be 10, 15, 20, 25, 30, 35, or 40, and may be within the range of any two of the above values, but is not limited to these.

[0102] VI, electronic equipment The present invention further provides electronic devices including the electrochemical apparatus described in the present invention. The applications of the electrochemical apparatus of the present invention are not particularly limited and may be used in any of the electronic devices known in the prior art. In some embodiments, the electrochemical apparatus of the present invention may be applied to, but is not limited to, notebook computers, pen-input computers, mobile computers, e-book players, mobile phones, portable facsimile machines, portable copiers, portable printers, stereo headsets, video recorders, LCD televisions, portable cleaners, portable CD players, MiniDiscs, transceivers, electronic notebooks, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, motorcycles, auxiliary bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashes, cameras, large home storage batteries, and lithium-ion capacitors. Examples

[0103] In the following, the preparation of lithium-ion batteries will be described using lithium-ion batteries as an example and referring to specific embodiments. Those skilled in the art should understand that the preparation methods described in this invention are merely illustrative and that any other suitable preparation methods are within the scope of this invention.

[0104] (I) Preparation of lithium-ion batteries (1) Preparation of the positive electrode Lithium cobalt oxide (LiCoO2), the positive electrode active material, Super P, the conductive agent, and polyvinylidene fluoride, the binder, were mixed in a weight ratio of 97:1:2. N-methylpyrrolidone (NMP) was added, and the mixture was uniformly stirred using a vacuum stirrer to obtain a positive electrode slurry. The positive electrode slurry was uniformly coated onto aluminum foil, which was the positive electrode current collector. The aluminum foil was dried, then cold-rolled, cut, and slit, and finally dried under vacuum conditions to obtain a positive electrode piece.

[0105] (2) Preparation of the negative electrode A negative electrode slurry was obtained by mixing artificial graphite, a thickener sodium carboxymethylcellulose (CMC), and a binder styrene-butadiene rubber (SBR) in a weight ratio of 97:1:2, adding deionized water, and stirring under vacuum. The negative electrode slurry was uniformly coated onto copper foil, which was the negative electrode current collector. The copper foil was dried, then cold-rolled, cut, and slit, and finally dried under vacuum conditions to obtain a negative electrode piece.

[0106] (3) Preparation of electrolyte In a glove box under a dry argon gas atmosphere, ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) were mixed in a weight ratio of 1:3:6, and LiPF6, a lithium salt, was added and mixed uniformly to form the base electrolyte. The concentration of LiPF6 was 1.2 mol / L. Additives were added to the base electrolyte as needed to obtain the electrolytes used in the examples and comparative examples of the present invention. The specific types of additives and their contents are shown in Table 1-3 below.

[0107] (4) Preparation of separators Boehmite was mixed with polyacrylic acid ester and dissolved in deionized water to form a coating layer slurry. Then, the coating layer slurry was uniformly applied to both surfaces of a polyethylene porous substrate using a microgravure coating method, and after drying, the required separator was obtained.

[0108] (5) Preparation of lithium-ion batteries A cell was obtained by stacking the positive electrode, separator, and negative electrode in that order, with a separator interposed between them to act as an isolation, and then winding them up. After welding tabs, the cell was placed in an aluminum plastic film, which served as the outer foil, leaving an injection port. The electrolyte prepared above was injected into the dried cell through the injection port, and a lithium-ion battery was obtained through a process including vacuum packaging, standing, chemical conversion, shaping, and capacity measurement.

[0109] (II) Measurement method 1. Method for measuring electrolyte components and their content The battery was discharged to 2.8V with a constant current of 0.1C, and its weight was determined to be m. The battery was then disassembled, and the cells and the aluminum plastic film outer foil were immediately extracted in high-purity acetonitrile (purity ≥ 99.9%). The resulting solution was measured by gas chromatography to obtain the individual components and their relative content p in the electrolyte. The extracted cells and aluminum plastic outer foil were dried in a vacuum oven, and their total weight was determined to be m'. The weight of the electrolyte was n = m - m'. The weight of each component in the battery was defined as the product of n and the relative content p of each component.

[0110] 2. Method for calculating the percentage of cyano groups The percentage of cyano groups was calculated using the following formula.

number

[0111] 3. How to measure cell size The outer foil, an aluminum plastic film, was disassembled and removed to obtain the cells. As shown in Figure 4, the length L, width W, and thickness T of the cells were measured using a micrometer.

[0112] 4. Measurement of the rapid charging characteristics of lithium-ion batteries The lithium-ion batteries were divided into three groups, and charge-discharge cycle tests were performed at currents of 0.7C, 1.5C, and 3C for each group. Each group consisted of 10 lithium-ion batteries. The lithium-ion batteries were left standing at 25°C for 30 minutes, then charged to 4.5V at 0.7C, 1.5C, and 3C respectively, then charged at a constant voltage to 0.05C, and finally discharged at a constant current to 3.0V at 0.7C, 1.5C, and 3C respectively. The above process was repeated for 250 charge-discharge cycles. The initial discharge capacity of each lithium-ion battery was recorded, and the average value for batteries within the group was taken as C1. The discharge capacity of each lithium-ion battery after 250 cycles was recorded, and the average value for batteries within the group was taken as C250. The cycle capacity retention rate of lithium-ion batteries at 0.7C, 1.5C, and 3C was calculated using the following formula. Cycle capacity maintenance rate = (C250 / C1) × 100%

[0113] 5. Measurement of high-temperature interval cycling (ITC) of lithium-ion batteries The lithium-ion battery was placed in a 45°C incubator and left undisturbed for 30 minutes. Then, the lithium-ion battery was discharged to 3.0V with a current of 0.5C, and then charged to 4.5V with a current of 1C, followed by 24 hours of undisturbed storage. This constituted one charge-discharge cycle. Fifty charge-discharge cycles were performed following the above procedure. The initial discharge capacity and the discharge capacity after 50 cycles were recorded and denoted as C and C', respectively. The cycle capacity retention rate of the lithium-ion battery was calculated using the following formula. Cycle capacity maintenance rate = (C' / C) × 100% In addition, the initial thickness η and the thickness η' after 50 cycles of the lithium-ion battery were measured using a micrometer. The thickness increase rate of the lithium-ion battery was calculated using the following formula. Thickness increase rate = (η' / η-1) × 100%

[0114] (III) Measurement results Table 1 shows the effects of the content and ratio of carboxylic acid ester compounds and FECs in the electrolyte on the rapid charging characteristics and high-temperature ITC characteristics of lithium-ion batteries.

[0115] [Table 1] Note: The symbol " / " indicates that there is no corresponding component.

[0116] From the electrochemical measurement results in Table 1, it can be seen that by adding carboxylic acid ester compounds and FEC to the electrolyte and adjusting their content and their ratio to satisfy 5% ≤ w1 ≤ 60%, 2% ≤ w2 ≤ 12%, and 2 ≤ w1 / w2 ≤ 20, the rapid charging characteristics of the electrochemical apparatus can be improved without degrading, or only slightly degrading, the high-temperature ITC characteristics of the electrochemical apparatus.

[0117] Comparative Examples 1-1 to 1-3 show that adding FEC alone to the electrolyte and keeping its content within an appropriate range can improve the rapid charging characteristics of an electrochemical device to some extent. However, if the FEC content is too high (e.g., more than 12%), gas generation worsens, and the thickness of the battery clearly increases during high-temperature interval cycling. Furthermore, if the FEC content is too high, the rapid charging characteristics of the electrochemical device at high currents (e.g., 1.5C and 3C) worsen rather than improve. This is because an appropriate amount of FEC effectively mitigates the breakdown of the negative electrode SEI film during battery charging and discharging, allowing for timely repair, thereby improving overcharge characteristics. However, if the FEC content is too high, it becomes easier to form an excessively thick SEI film, and the progress of the film formation reaction further leads to lithium deposition in the cell, resulting in a rapid decrease in battery capacity. Furthermore, if the FEC content is too high, under the intermittent cycle operation conditions of the ITC, the structure of the positive electrode is destroyed, an oxygen release reaction occurs, the FEC is oxidized and CO2 is generated, and as a result, swelling occurs in the battery due to gas generation.

[0118] Comparative Examples 1-4 to 1-6, compared to Comparative Example 1-1, showed improved rapid charging characteristics of the electrochemical apparatus, particularly at high currents (e.g., 1.5C and 3C), due to the addition of a chain-like carboxylic acid ester compound to the electrolyte. Ethyl propionate and propyl propionate, compared to ethyl acetate, improved rapid charging characteristics without substantially degrading high-temperature ITC characteristics, and may even improve high-temperature ITC characteristics.

[0119] Comparing Examples 1-1 to 1-4 with Comparative Examples 1-5, 1-7 to 1-9, it can be seen that if the content and ratio of carboxylic acid ester compounds and FEC satisfy 5% ≤ w1 ≤ 60%, 2% ≤ w2 ≤ 12%, and 2 ≤ w1 / w2 ≤ 20, the rapid charging characteristics of the electrochemical apparatus can be improved without degrading, or only slightly degrading, the high-temperature ITC characteristics of the electrochemical apparatus. Comparing Examples 1-5 and 1-6 with Comparative Example 1-5, it can be seen that by further adjusting w1 / w2 to be within the range of 4 ≤ w1 / w2 ≤ 10, not only can the rapid charging characteristics of the electrochemical apparatus be improved, but the high-temperature ITC characteristics can also be improved. Comparing Examples 1-7 and 1-8 with Comparative Examples 1-4 and 1-10, or comparing Examples 1-9 to 1-11 with Comparative Example 1-6, similar conclusions can be reached.

[0120] Examples 1-12 to 1-15 demonstrate that by using combinations of multiple carboxylic acid ester compounds, satisfying the conditions 5% ≤ w1 ≤ 60%, 2% ≤ w2 ≤ 12%, and 2 ≤ w1 / w2 ≤ 20, it is possible to simultaneously improve both rapid charging characteristics and high-temperature ITC characteristics. For example, by simultaneously adding propyl propionate and ethyl propionate to the electrolyte, it is possible to more efficiently improve rapid charging characteristics while maintaining excellent high-temperature ITC characteristics.

[0121] Table 2 shows the effects of cyano group content and the content of carboxylic acid esters and FECs in the electrolyte on the rapid charging characteristics and high-temperature ITC characteristics of lithium-ion batteries. The examples in Table 2 are improvements based on Examples 1-14, the main difference being the addition of nitrile compounds to the electrolyte.

[0122] The results of the characteristic measurements in Table 2 show that by adding an appropriate amount of nitrile compound to the electrolyte, the high-temperature ITC characteristics can be improved without degrading the rapid charging characteristics of the electrochemical apparatus, or at least slightly degrading them.

[0123] Examples 2-1 to 2-8, compared to Example 1-14, involved adding a single nitrile compound to the electrolyte, which slightly worsened the rapid charging characteristics of the electrochemical apparatus but clearly improved the high-temperature ITC characteristics. However, adding an excessive amount of a single nitrile compound increased the viscosity of the electrolyte to some extent, resulting in lithium ions not being released in a timely manner and lithium precipitation, which negatively affected the high-temperature ITC characteristics to some degree.

[0124] Examples 2-9 to 2-29 involved the addition of multiple nitrile compounds to the electrolyte compared to Example 1-14. As shown in Examples 2-9 to 2-17, when the amount of nitrile compounds added is constant, if the cyano group content ratio x / y satisfies 2.16 ≤ x / y ≤ 2.71, the high-temperature ITC characteristics can be effectively improved without substantially degrading the rapid charging characteristics of the electrochemical apparatus.

[0125] Furthermore, the data in Table 2 shows that by controlling the cyano group content ratio x / y to satisfy 2.16 ≤ x / y ≤ 2.71 and the nitrile compound content w3 to be within the range of 0.1% ≤ w3 ≤ 12%, it is possible to surpass the improvement effect of adding a single nitrile compound on high-temperature ITC characteristics and effectively mitigate the adverse effects of a single nitrile compound on rapid charging characteristics.

[0126] Furthermore, Examples 2-26 to 2-29 demonstrate that, assuming the cyano group content satisfies the above range, the total amount of nitrile compounds should not be too much or too little. However, comparison with Examples 2-19 and 2-25 shows that when the cyano group content x / y satisfies 2.16 ≤ x / y ≤ 2.71, it is possible to exceed the upper limit of the amount of a single nitrile compound used, thereby maximizing the improvement of high-temperature ITC characteristics.

[0127] [Table 2(1)] [Table 2(2)] [Table 2(3)] Note: The symbol " / " indicates that there is no corresponding component.

[0128] Table 3 shows the effects of cell size and the content of carboxylic acid ester compounds in the electrolyte on the high-temperature ITC characteristics of lithium-ion batteries. The examples in Table 3 are improvements based on Examples 2-23, the differences being specifically in the cell size and / or the content of carboxylic acid ester compounds in the electrolyte.

[0129] [Table 3]

[0130] The measurement results in Table 3 show that by conforming the battery size and the content of carboxylic acid ester compounds in the electrolyte to a certain relationship, the battery's charge rate window can be widened and lithium deposition can be improved, thereby improving the rapid charging characteristics of the electrochemical device.

[0131] Examples 3-1 to 3-12 show that, without changing the electrolyte, the rapid charging characteristics of the electrochemical device can be improved by having the aspect ratio L / W within the range of 1 ≤ L / W ≤ 4, or the width-to-thickness ratio W / T within the range of W / T ≥ 5. In particular, the rapid charging characteristics at high-rate currents of 1.5C or higher can be significantly improved. This is mainly because, when the cell is within the above range, the improvement in current density and temperature during charging in the upper and lower edge regions and the outer peripheral electrode region does not differ significantly from the main body region, thus reducing lithium deposition in the edge regions and outer peripheral electrode region, and thereby improving the rapid charging characteristics.

[0132] Examples 3-13 to 3-17 show that, when the cell size does not change, the rapid charging characteristics of the electrochemical device can be improved by adjusting the content of the carboxylic acid ester compound in the electrolyte to satisfy w1 × 100 / (L / W) ≥ 10, and in particular, the rapid charging characteristics at high-rate currents of 1.5C or higher can be significantly improved. Adding a carboxylic acid ester compound can improve the rapid charging characteristics of the electrochemical device, but it adversely affects the high-temperature ITC characteristics. Therefore, considering the size limitations of the electrochemical device applied to notebook computers, designing the cell size and adjusting the carboxylic acid ester is considered an effective measure to balance dynamic characteristics and battery safety.

[0133] Throughout this specification, any reference by “Example,” “Part of an Example,” “One Example,” “Another Example,” “Example,” “Specific Example,” or “Part of an Example” means that at least one example or example of the present invention includes the specific features, structures, materials, or properties described in that example or example. Therefore, any reference by “In some examples,” “In an example,” “In one example,” “In another example,” “In one example,” “In a particular example,” or “Example” anywhere in this specification does not necessarily refer to the same example or example in the present invention. Furthermore, the specific features, structures, materials, or properties described herein can be combined in any preferred manner in one or more examples or examples.

[0134] While exemplary embodiments have been disclosed and described, those skilled in the art should understand that the embodiments can be modified, substituted, and altered insofar as they do not limit the invention and do not depart from the technical spirit, principles, and scope of the invention.

Claims

1. An electrolyte comprising a carboxylic acid ester compound represented by formula (I) and fluoroethylene carbonate (FEC), 【Chemistry 1】 R １１ It comprises at least one of hydrogen, a hydroxyl group, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C2-C20 linear alkenyl group, a C6-C30 aryl group, and a C6-C30 aryloxy group. R １２ It comprises at least one of a C1-C20 alkyl group, a C2-C20 linear alkenyl group, and a C6-C30 aryl group. The carboxylic acid ester compound represented by formula (I) includes propyl propionate and ethyl acetate. Based on the total weight of the electrolyte, the content of the carboxylic acid ester compound represented by formula (I) and the content of the fluoroethylene carbonate are, respectively, w １ and w ２ In that case, 5% ≤ w １ ≤60%, 2%≤w ２ ≤12% and 2 ≤ w １ / w ２ An electrolyte solution with a coefficient of ≤20.

2. 4 ≤ w １ / w ２ ≤ 10, the electrolytic solution according to claim 1.

3. The electrolyte further comprises a nitrile compound, Based on the total weight of the electrolyte, the nitrile compound content is w ３ In that case, 0.1% ≤ w ３ The electrolyte according to claim 1, wherein the concentration is ≤12%.

4. The nitrile compound comprises at least one of the compounds represented by formulas (II) to (V), 【Chemistry 2】 R ２１ It comprises at least one of a substituted or unsubstituted C1-C12 alkylene group and a substituted or unsubstituted C1-C12 alkylene oxy group, R ３１ , R ３２ Each independently comprises hydrogen and at least one of substituted or unsubstituted C1-C12 alkylene groups. R ４１ , R ４２ , R ４３ Each independently comprises at least one of a substituted or unsubstituted C1-C12 alkylene group and a substituted or unsubstituted C1-C12 alkylene oxy group, R ５１ It comprises at least one of the following: a substituted or unsubstituted C1-C12 alkylene group, a substituted or unsubstituted C2-C12 alkenylene group, a substituted or unsubstituted C6-C26 arylene group, and a substituted or unsubstituted C2-C12 heterocyclylene group, wherein the heteroatom is at least one of N, S, and O. The electrolyte according to claim 3, wherein, in the case of substitution, the substituent is a halogen.

5. The electrolyte according to claim 3, wherein when the total molar amount of cyano groups (-CN) in the nitrile compound is x, and the total molar amount of the nitrile compound is y, the cyano group content ratio x / y satisfies 2.16 ≤ x / y ≤ 2.

71.

6. The cyano group content ratio x / y and the content w of the carboxylic acid ester compound represented by formula (I) １ and the content of the fluoroethylene carbonate w ２ 2w １ ２ -0.01w １ +2.3>x / y>27w ２ ２ -1.2w ２ The electrolyte according to claim 5, satisfying +2.

1.

7. The electrolyte contains a lithium salt, The lithium salt is LiPF ６ LiBF ４ LiAsF ６ LiClO ４ LiB(C) ６ H ５ ) ４ LiCH ３ SO ３ LiCF ３ SO ３ , LiN (SO ２ CF ３ ) ２ , LiC (SO ２ CF ３ ) ３ LiSiF ６ The electrolyte according to claim 1, comprising at least one of LiBOB and LiDFOB.

8. An electrochemical apparatus comprising the electrolyte according to any one of claims 1 to 7.

9. The electrochemical apparatus further includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode. The electrochemical apparatus according to claim 8, wherein the positive electrode, the negative electrode, and the separator are wound together to form a cell, and the length L and width W of the cell satisfy 20 mm ≤ L ≤ 300 mm, 20 mm ≤ W ≤ 100 mm, and 1 ≤ L / W ≤ 4.

10. The electrochemical apparatus is, a) 1≦L / W≦3, b) 2 ≤ L / W ≤ 3, and c) 2 ≤ L / W ≤ 4 The electrochemical apparatus according to claim 9, which satisfies at least one of the following conditions.

11. The electrochemical apparatus further includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode. The electrochemical apparatus according to claim 8, wherein the positive electrode, the negative electrode, and the separator are wound together to form a cell, and the thickness T and width W of the cell satisfy 2 mm ≤ T ≤ 12 mm and W / T ≥ 5.

12. The electrochemical apparatus is, d) 5≦W / T≦25, e) 5≦W / T≦20, f) 5 ≤ W / T ≤ 15, and g) 10≦W / T≦25 The electrochemical apparatus according to claim 11, satisfying at least one of the following conditions.

13. The electrochemical apparatus further includes a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode. The positive electrode, the negative electrode, and the separator are wound together to form a cell, and the length L and width W of the cell, and the content w of the carboxylic acid ester compound represented by formula (I) １ , lol １ The electrochemical apparatus according to claim 8, satisfying ×100 / (L / W) ≥ 10.

14. The electrochemical apparatus is, h)10≦w １ ×100 / (L / W)≦40、 i)20≦w １ ×100 / (L / W)≦30、 j) 20 ≤ w １ ×100 / (L / W) ≤ 40, and k)15≦w １ ×100 / (L / W)≦30 The electrochemical apparatus according to claim 13, satisfying at least one of the following conditions.

15. An electronic apparatus including the electrochemical apparatus described in claim 8.

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