Electrolyte of Li / CFx battery and Li / CFx battery containing electrolyte

Abstract

The invention belongs to the field of batteries, and provides an electrolyte of a Li / CFx battery and the Li / CFx battery containing the electrolyte, the electrolyte comprises an electrolyte matrix and a silane additive; the silane additive contains an alkenyl group and an alkoxy group. The silane containing alkenyl double bonds is introduced into the electrolyte, so that free radical polymerization or ionic polymerization can be carried out under the action of carbocations / carbon free radicals generated by carbon fluoride, and a passivation layer is formed on the active surface of the positive electrode to block the contact between the electrolyte and the carbon fluoride; silane containing alkoxy has extremely high HF removal capacity, free fluorine of the electrolyte can be effectively captured, and removal of unstable fluorocarbon bonds is facilitated; therefore, through the synergistic effect of silane containing alkenyl double bonds and silane containing alkoxy, the stability of a positive electrode, the stability of a negative electrode and the stability of an electrolyte are effectively improved, and the long-term and high-temperature storage stability of the lithium carbon fluoride battery is improved.

Description

Technical Field

[0001] The present invention belongs to the field of battery technology and relates to an electrolyte of a Li / CFx battery and a Li / CFx battery containing the electrolyte x Battery. Background Art

[0002] Li / CF x (Lithium / carbon fluoride) battery is a non-aqueous primary battery with lithium metal as the negative electrode and carbon fluoride material as the positive electrode. Due to its advantages such as high energy density, long life, good storage stability and wide operating temperature range, Li / CF x Batteries are widely used in military, aerospace, medical equipment, and portable electronic devices.

[0003] The chemical structure of carbon fluoride materials is usually represented by CF x , where the x value is usually between 0.5 and 1.0. In fluorinated carbon materials, the bonding forms between carbon atoms and fluorine atoms are diverse, including CF single bonds, CF double bonds and CF triple bonds. These different bonding forms give fluorinated carbon materials unique electrochemical properties. However, some unstable carbon-fluorine bonds in fluorinated carbon materials are prone to homolytic or heterolytic cleavage at high temperatures or during long-term storage, producing carbon radicals, fluorine radicals or carbon cations, and fluoride ions. These highly chemically active intermediate species will trigger the decomposition of the electrolyte and generate by-products inside the battery, further leading to rapid decay of the battery capacity, thereby affecting the overall performance of the battery.

[0004] For example, CN114628670A discloses a nitrogen-doped-carbon-coated fluorinated carbon for use in lithium / fluorinated carbon batteries, which uses an aqueous solution of trishydroxymethylaminomethane (Tris) as a buffer, first obtains a polydopamine fluorinated carbon composite material through a self-polymerization reaction of dopamine hydrochloride, and then the composite material is calcined at high temperature under an inert atmosphere, and finally obtains a nitrogen-doped-carbon-coated fluorinated carbon electrode material. The nitrogen-doped-carbon coating layer can not only effectively block the direct contact between the electrolyte and the fluorinated carbon material, reduce the self-discharge phenomenon of the battery, but also improve the high-temperature shelf performance of the battery. However, the preparation process of the nitrogen-doped-carbon-coated fluorinated carbon material is relatively complicated, and it is necessary to go through multiple steps, including self-polymerization reaction, high-temperature calcination, etc., which undoubtedly greatly increases the production cost, and is particularly unfavorable for large-scale industrial production. In addition, the thickness and uniformity of the nitrogen-doped-carbon coating layer have a significant effect on the battery performance, and the control difficulty is relatively large, which easily leads to performance differences between batches.

[0005] Considering Li / CF xThe deterioration of battery performance is caused by the reaction between the carbon fluoride material and the electrolyte. In addition to modifications such as coating the carbon fluoride material itself, improving and optimizing the electrolyte is also a feasible research direction.

[0006] For example, CN114175320A discloses an electrolyte composition of an electrochemical cell comprising a lithium anode, which is formed by adding a certain proportion of fluorocarbonates, such as fluoroethylene carbonate (FEC) or fluoropropylene carbonate (FPC) to the electrolyte, so that the introduction of fluorocarbonates can form a dense solid electrolyte interface film (SEI film) on the surface of metallic lithium, thereby effectively inhibiting the side reaction of metallic lithium and electrolyte, reducing the self-discharge rate of the battery, and improving the storage stability of the battery. In addition, fluorocarbonates also have high oxidation stability, which can prevent the decomposition of the electrolyte at high temperature to a certain extent, and further improve the high temperature performance of the battery. It can be seen that although the introduction of fluorocarbonates significantly improves the stability of the negative electrode metallic lithium, it cannot completely solve the problem of the reaction of positive electrode fluorinated carbon with the electrolyte. The unstable carbon-fluorine bond in the fluorinated carbon material will still react with the electrolyte during high temperature or long-term storage, resulting in the attenuation of the battery capacity. Therefore, the improvement effect of the introduction of fluorocarbonates alone is limited.

[0007] The electrolyte is Li / CF x An important component of the battery, it is not only responsible for the transmission of lithium ions, but also plays a key role in the electrochemical performance and safety of the battery. At present, it is still of great significance and value to select and develop electrolytes to avoid or solve the reaction with fluorinated carbon materials, thereby improving the stability of the battery and extending its service life. Summary of the invention

[0008] In view of the problems existing in the prior art, the object of the present invention is to provide a Li / CF x Battery electrolyte and Li / CF containing the same x The battery, the electrolyte includes an electrolyte matrix and a silane additive; the silane additive contains alkenyl and alkoxy groups. By introducing silane containing alkenyl double bonds and silane containing alkoxy groups as additives in the electrolyte, the stability of the fluorinated carbon material itself is improved, thereby improving the Li / CF x Long-term storage and high-temperature storage stability of batteries.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a Li / CF x The electrolyte of the battery comprises an electrolyte matrix and a silane additive; the silane additive contains alkenyl and alkoxy groups.

[0011] The present invention can introduce silane containing alkenyl double bonds to carry out free radical polymerization or ion polymerization under the action of carbon cations / carbon free radicals generated by carbon fluoride, and form a passivation layer on the active surface of the positive electrode to block the contact between the electrolyte and the carbon fluoride. At the same time, it can also form a stable passivation layer on the surface of metallic lithium to further inhibit the decomposition of the electrolyte at the positive and negative electrodes; and the silane containing alkoxy groups has a very strong ability to remove HF, can effectively capture the free fluorine of the electrolyte, and the oxygen in the alkoxy groups can react with the carbon in the active carbon fluoride bond to generate nucleophilic reaction, which is beneficial to the removal of unstable carbon fluorine bonds; therefore, the present invention can effectively improve the stability of the positive and negative electrodes and the electrolyte through the synergistic effect of the silane containing alkenyl double bonds and the silane containing alkoxy groups, thereby achieving the improvement of the long-term and high-temperature storage stability of the lithium carbon fluoride battery.

[0012] The following are preferred technical solutions of the present invention, but are not intended to be limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0013] As a preferred technical solution of the present invention, the silane additive includes silane A containing alkenyl groups and silane B containing alkoxy groups, and / or includes silane C containing both alkenyl groups and alkoxy groups.

[0014] It should be noted that the silane additive in the present invention can be a combination of silane A and silane B, or a combination of silane A, silane B and silane C, or only silane C is used to ensure that the silane additive contains both alkenyl and alkoxy groups.

[0015] As a preferred technical solution of the present invention, the chemical formula of the alkenyl-containing silane A includes R 1 b Si a R 2 2a+2-b , wherein a is 1 or 2, b is an integer from 1 to 6, such as 1, 2, 3, 4, 5 or 6; 2a+2-b is an integer from 0 to 5, such as 0, 1, 2, 3, 4 or 5; R 1 is a C2-C4 alkenyl group, such as at least one of vinyl, propenyl or butenyl, preferably vinyl; R 2 It is a C1-C3 alkyl group, for example, at least one of a methyl group, an ethyl group or a butyl group.

[0016] Preferably, the alkenyl-containing silane A includes at least one of vinyltrimethylsilane, vinyltriethylsilane, divinyldimethylsilane, divinyldipropylsilane, trivinylmethylsilane, trivinylethylsilane, trivinylpropylsilane, tetravinylsilane, tetraallylsilane or divinyltetramethyldisilane; preferably at least one of divinyldimethylsilane, trivinylmethylsilane, trivinylethylsilane or tetravinylsilane.

[0017] As a preferred technical solution of the present invention, the chemical formula of the alkoxy-containing silane B includes R 4 4-c Si(OR 3 ) c , wherein c is an integer from 1 to 4, such as 1, 2, 3 or 4; R 3 including at least one of a C1-C3 alkyl group, such as a methyl group, an ethyl group or a butyl group; R 4 It includes at least one of C1-C20 alkyl or halogenated alkyl, preferably methyl, halogenated methyl, ethyl, halogenated ethyl, propyl or halogenated propyl, or C5-C20 aryl or halogenated aryl, preferably phenyl or halogenated phenyl.

[0018] It should be noted that R 4 When a halogenated alkyl group or a halogenated aryl group is included, R 4 The hydrogen atoms in are partially or fully substituted by halogen atoms, preferably partially or fully substituted by fluorine atoms.

[0019] Preferably, the alkoxy-containing silane B includes at least one of tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, phenyltrimethoxysilane, trifluoropropanetrimethoxysilane, dimethyldimethoxysilane, methylcyclohexyldimethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, triethylmethoxysilane or methoxydimethylphenylsilane; preferably, at least one of ethyltrimethoxysilane, phenyltrimethoxysilane, trifluoropropanetrimethoxysilane, dimethyldimethoxysilane or methoxydimethylphenylsilane.

[0020] As a preferred technical solution of the present invention, the chemical formula of the silane C containing both alkenyl and alkoxy groups includes R 5 d R 7 4-d-e Si(OR 6 ) e , wherein d is an integer from 1 to 3, such as 1, 2 or 3; e is an integer from 1 to 3, such as 1, 2 or 3; 4-de is an integer from 0 to 2, such as 0, 1 or 2; R 5It includes C2-C20 alkenyl, preferably at least one of vinyl, propenyl or butenyl, and more preferably vinyl; R 6 Including C1-C3 alkyl; R 7 It includes at least one of C1-C20 alkyl or halogenated alkyl, preferably methyl, halogenated methyl, ethyl, halogenated ethyl, propyl or halogenated propyl, or C5-C20 aryl or halogenated aryl, preferably phenyl or halogenated phenyl.

[0021] It should be noted that R 7 When a halogenated alkyl group or a halogenated aryl group is included, R 7 The hydrogen atoms in are partially or fully substituted by halogen atoms, preferably partially or fully substituted by fluorine atoms.

[0022] Preferably, the silane C containing both alkenyl and alkoxy groups includes at least one of vinyltrimethoxysilane, methylvinyldimethoxysilane, vinylphenylmethylmethoxysilane or methylvinyldiethoxysilane.

[0023] It should be noted that silanes containing alkoxy groups can easily affect the stability of metallic lithium, especially at high temperatures; while silanes containing alkenyl groups can form films on the surface of metallic lithium and improve the stability of metallic lithium; when using silanes containing both alkenyl groups and alkoxy groups, the ratio of alkenyl groups to alkoxy groups and the amount of silane added must be strictly controlled.

[0024] As a preferred technical solution of the present invention, the mass of the silane additive accounts for the Li / CF x 0.1% to 15% of the total mass of the battery's electrolyte, for example 0.1%, 0.3%, 0.5%, 0.8%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, etc., preferably 0.1% to 5%, more preferably 0.1% to 2%, but it is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0025] As a preferred technical solution of the present invention, the mass of the alkenyl-containing silane A accounts for the Li / CF x 0.1% to 10% of the total mass of the electrolyte of the battery, for example, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%, etc., preferably 0.1% to 5%, more preferably 0.1% to 2%, but it is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0026] Preferably, the mass of the alkoxy-containing silane B accounts for x 0.1% to 5% of the total mass of the electrolyte of the battery, for example, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.3%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8% or 5%, etc., preferably 0.1% to 1%, more preferably 0.1% to 0.5%, but it is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0027] Preferably, the mass of the silane C containing alkenyl and alkoxy groups accounts for x 0.1% to 5% of the total mass of the electrolyte of the battery, for example, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.3%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8% or 5%, etc., preferably 0.1% to 1%, more preferably 0.1% to 0.5%, but it is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0028] In the present invention, the amount of silane containing alkoxy groups is preferably less than 0.5%. Excessive addition may easily cause instability of the metal lithium negative electrode, and the amount added should not be too much; and the content of silane containing alkenyl groups should not be too much, preferably <5%, otherwise it may easily lead to serious passivation of the negative electrode.

[0029] As a preferred technical solution of the present invention, the electrolyte matrix includes a solvent and an electrolyte salt.

[0030] Preferably, the electrolyte salt comprises a lithium salt, and the lithium salt comprises at least one of lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bistrifluoromethanesulfonyl imide, lithium bisfluorosulfonyl imide or lithium trifluoromethanesulfonate, for example, typical but non-limiting combinations include a combination of lithium perchlorate and lithium hexafluorophosphate, a combination of lithium perchlorate and lithium tetrafluoroborate, a combination of lithium perchlorate and lithium bistrifluoromethanesulfonyl imide, a combination of lithium perchlorate and lithium bisfluorosulfonyl imide, a combination of lithium perchlorate and lithium trifluoromethanesulfonate, a combination of lithium hexafluorophosphate and lithium tetrafluoroborate, a combination of lithium bistrifluoromethanesulfonyl imide and lithium bisfluorosulfonyl imide, or a combination of lithium hexafluorophosphate and lithium trifluoromethanesulfonate, etc.

[0031] Preferably, the lithium salt is in the Li / CF xThe concentration of the electrolyte of the battery is 0.5-2 mol / L, for example 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L or 2 mol / L, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0032] Preferably, the solvent comprises an organic solvent, and the organic solvent comprises at least one of ethylene glycol dimethyl ether, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate or gamma-martinol, for example, typical but non-limiting combinations include a combination of ethylene glycol dimethyl ether and ethylene carbonate, a combination of propylene carbonate and dimethyl carbonate, a combination of diethyl carbonate and ethyl methyl carbonate, a combination of gamma-martinol and ethylene glycol dimethyl ether, a combination of ethylene carbonate and propylene carbonate, a combination of dimethyl carbonate and diethyl carbonate, or a combination of ethyl methyl carbonate and gamma-martinol, etc.

[0033] It should be noted that the present invention is not limited to the Li / CF x The preparation method of the electrolyte of the battery exemplarily includes mixing the solvent in a glove box filled with an inert gas (such as argon) to obtain a mixed solvent, and then adding an electrolyte salt and a silane additive to the mixed solvent to obtain the Li / CF x The electrolyte of the battery.

[0034] In a second aspect, the present invention provides a Li / CF x Battery, comprising the Li / CF described in the first aspect x The electrolyte of the battery.

[0035] As a preferred technical solution of the present invention, the Li / CF x The electrolyte injection coefficient of the battery is 1.0 to 1.6 g / Ah, for example, 1.0 g / Ah, 1.05 g / Ah, 1.1 g / Ah, 1.15 g / Ah, 1.2 g / Ah, 1.25 g / Ah, 1.3 g / Ah, 1.35 g / Ah, 1.4 g / Ah, 1.45 g / Ah, 1.5 g / Ah, 1.55 g / Ah or 1.6 g / Ah, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0036] It is understandable that the Li / CF x The battery contains the Li / CF xIn addition to the electrolyte of the battery, it also contains necessary components, parts and structures including positive electrode sheet, negative electrode sheet and separator, etc. The active material of the positive electrode sheet includes carbon fluoride, and the negative electrode sheet includes a metal lithium sheet.

[0037] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0038] The present invention introduces a silane additive containing alkenyl and alkoxy groups, and utilizes the alkenyl-containing silane to undergo free radical / ion polymerization with carbon free radicals / carbon cations in the carbon fluoride material to form a passivation layer / interface layer on the surface of the carbon fluoride, thereby improving the stability of the positive electrode. At the same time, the alkenyl-containing silane can form a dense passivation layer on the surface of the metal lithium negative electrode, further improving the stability of the metal lithium; and the oxygen in the alkoxysilane has strong alkalinity / nucleophilicity, and can preferentially react with the active carbon-fluorine bonds in the solvent and the positive electrode carbon fluoride, thereby inhibiting the decomposition of the electrolyte. At the same time, the fluoride ions or hydrofluoric acid generated by the decomposition of the carbon fluoride are also directly captured by the alkoxy-containing silane. Therefore, the long-term storage and high-temperature storage stability of the lithium / carbon fluoride battery are jointly improved through the synergistic effect of the alkenyl-containing silane and the alkoxy-containing silane. Moreover, the silane additive of the present invention can be directly added to the electrolyte matrix, which not only facilitates the preparation and production of the electrolyte, but also makes it easier and more feasible to improve and optimize the carbon fluoride on the electrolyte side, and facilitates the large-scale preparation and production of high-stability lithium / carbon fluoride batteries. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0040] It should be clear to those skilled in the art that the embodiments are only intended to help understand the present invention and should not be considered as specific limitations of the present invention.

[0041] Example 1

[0042] This embodiment provides a Li / CF x The electrolyte of the battery comprises an electrolyte matrix and a silane additive; the electrolyte matrix comprises a solvent and an electrolyte salt; the solvent is propylene carbonate and ethylene glycol dimethyl ether; the electrolyte salt comprises a lithium salt, and the lithium salt is lithium hexafluorophosphate; the silane additive comprises a silane A containing an alkenyl group and a silane B containing an alkoxy group, wherein the silane A containing an alkenyl group is tetravinylsilane, and the silane B containing an alkoxy group is ethyltrimethoxysilane; the electrolyte salt is in the Li / CF x The concentration of the electrolyte in the battery is 0.8 mol / L; x When the total mass of the electrolyte of the battery is 100%, the mass of the alkenyl-containing silane A accounts for 1.5%, and the mass of the alkoxy-containing silane B accounts for 0.2%.

[0043] Example 2

[0044] This embodiment provides a Li / CF x The electrolyte of the battery comprises an electrolyte matrix and a silane additive; the electrolyte matrix comprises a solvent and an electrolyte salt; the solvent is propylene carbonate and ethylene glycol dimethyl ether; the electrolyte salt comprises a lithium salt, and the lithium salt is lithium hexafluorophosphate; the silane additive comprises a silane A containing an alkenyl group and a silane B containing an alkoxy group, wherein the silane A containing an alkenyl group is divinyltetramethyldisilane, and the silane B containing an alkoxy group is methyltrimethoxysilane; the electrolyte salt is in the Li / CF x The concentration of the electrolyte in the battery is 0.8 mol / L; x When the total mass of the electrolyte of the battery is 100%, the mass of the alkenyl-containing silane A accounts for 1.5%, and the mass of the alkoxy-containing silane B accounts for 0.3%.

[0045] Example 3

[0046] This embodiment provides a Li / CF x The electrolyte of the battery comprises an electrolyte matrix and a silane additive; the electrolyte matrix comprises a solvent and an electrolyte salt; the solvent is propylene carbonate and ethylene glycol dimethyl ether; the electrolyte salt comprises a lithium salt, and the lithium salt is lithium hexafluorophosphate; the silane additive comprises a silane A containing an alkenyl group and a silane B containing an alkoxy group, wherein the silane A containing an alkenyl group is trivinylethylsilane, and the silane B containing an alkoxy group is dimethyldimethoxysilane; the electrolyte salt is in the Li / CF x The concentration of the electrolyte in the battery is 0.8 mol / L; x The total mass of the electrolyte of the battery is 100%, the mass of the alkenyl-containing silane A accounts for 0.5%, and the mass of the alkoxy-containing silane B accounts for 0.1%.

[0047] Example 4

[0048] This embodiment provides a Li / CF x The electrolyte of the battery comprises an electrolyte matrix and a silane additive; the electrolyte matrix comprises a solvent and an electrolyte salt; the solvent is propylene carbonate and ethylene glycol dimethyl ether; the electrolyte salt comprises a lithium salt, and the lithium salt is lithium hexafluorophosphate; the silane additive comprises a silane A containing an alkenyl group and a silane B containing an alkoxy group, wherein the silane A containing an alkenyl group is tetraallylsilane, and the silane B containing an alkoxy group is methoxydimethylphenylsilane; the electrolyte salt is in the Li / CF x The concentration of the electrolyte in the battery is 0.8 mol / L;x When the total mass of the electrolyte of the battery is 100%, the mass of the alkenyl-containing silane A accounts for 1.3%, and the mass of the alkoxy-containing silane B accounts for 0.2%.

[0049] Example 5

[0050] This embodiment provides a Li / CF x The electrolyte of the battery comprises an electrolyte matrix and a silane additive; the electrolyte matrix comprises a solvent and an electrolyte salt; the solvent is propylene carbonate and ethylene glycol dimethyl ether; the electrolyte salt comprises a lithium salt, and the lithium salt is lithium hexafluorophosphate; the silane additive comprises a silane C containing both an alkenyl group and an alkoxy group, and the silane C is vinyl trimethoxy silane; the electrolyte salt is in the Li / CF x The concentration of the electrolyte in the battery is 0.8 mol / L; x The total mass of the electrolyte of the battery is 100%, and the mass of the silane C containing both alkenyl and alkoxy groups accounts for 0.2%.

[0051] Example 6

[0052] This embodiment provides a Li / CF x The electrolyte of the battery comprises an electrolyte matrix and a silane additive; the electrolyte matrix comprises a solvent and an electrolyte salt; the solvent is propylene carbonate and ethylene glycol dimethyl ether; the electrolyte salt comprises a lithium salt, and the lithium salt is lithium hexafluorophosphate; the silane additive comprises a silane C containing both an alkenyl group and an alkoxy group, and the silane C is methyl vinyl dimethoxy silane; the electrolyte salt is in the Li / CF x The concentration of the electrolyte in the battery is 0.8 mol / L; x The total mass of the electrolyte of the battery is 100%, and the mass of the silane C containing both alkenyl and alkoxy groups accounts for 0.1%.

[0053] Example 7

[0054] This embodiment provides a Li / CF x The electrolyte of the battery comprises an electrolyte matrix and a silane additive; the electrolyte matrix comprises a solvent and an electrolyte salt; the solvent is propylene carbonate and ethylene glycol dimethyl ether; the electrolyte salt comprises a lithium salt, and the lithium salt is lithium hexafluorophosphate; the silane additive comprises a silane C containing both an alkenyl group and an alkoxy group, and the silane C is vinylphenylmethylmethoxysilane; the electrolyte salt is in the Li / CF x The concentration of the electrolyte in the battery is 0.8 mol / L; x The total mass of the electrolyte of the battery is 100%, and the mass of the silane C containing both alkenyl and alkoxy groups accounts for 0.4%.

[0055] Example 8

[0056] This embodiment provides a Li / CF x The electrolyte of the battery comprises an electrolyte matrix and a silane additive; the electrolyte matrix comprises a solvent and an electrolyte salt; the solvent is propylene carbonate and ethylene glycol dimethyl ether; the electrolyte salt comprises a lithium salt, and the lithium salt is lithium hexafluorophosphate; the silane additive comprises a silane C containing both an alkenyl group and an alkoxy group, and the silane C is methyl vinyl diethoxy silane; the electrolyte salt is in the Li / CF x The concentration of the electrolyte in the battery is 0.8 mol / L; x The total mass of the electrolyte of the battery is 100%, and the mass of the silane C containing both alkenyl and alkoxy groups accounts for 0.2%.

[0057] Example 9

[0058] This embodiment provides a Li / CF x The electrolyte of the battery comprises an electrolyte matrix and a silane additive; the electrolyte matrix comprises a solvent and an electrolyte salt; the solvent is propylene carbonate and ethylene glycol dimethyl ether; the electrolyte salt comprises a lithium salt, and the lithium salt is lithium hexafluorophosphate; the silane additive comprises a silane A containing an alkenyl group, a silane B containing an alkoxy group, and a silane C containing both an alkenyl group and an alkoxy group; wherein the silane A containing an alkenyl group is divinyldipropylsilane, the silane B containing an alkoxy group is trifluoropropanetrimethoxysilane, and the silane C containing both an alkenyl group and an alkoxy group is methylvinyldiethoxysilane; the electrolyte salt is in the Li / CF x The concentration of the electrolyte in the battery is 0.8 mol / L; x The total mass of the electrolyte of the battery is 100%, the mass of the alkenyl-containing silane A accounts for 1%, the mass of the alkoxy-containing silane B accounts for 0.2%, and the mass of the silane C containing both alkenyl and alkoxy accounts for 0.2%.

[0059] Example 10

[0060] This embodiment provides a Li / CF xThe electrolyte of the battery comprises an electrolyte matrix and a silane additive; the electrolyte matrix comprises a solvent and an electrolyte salt; the solvent is propylene carbonate and ethylene glycol dimethyl ether; the electrolyte salt comprises a lithium salt, and the lithium salt is lithium hexafluorophosphate; the silane additive comprises a silane A containing an alkenyl group, a silane B containing an alkoxy group, and a silane C containing both an alkenyl group and an alkoxy group; wherein the silane A containing an alkenyl group is tetravinylsilane, the silane B containing an alkoxy group is 3,3,3-trifluoropropylmethyldimethoxysilane, and the silane C containing both an alkenyl group and an alkoxy group is vinylphenylmethylmethoxysilane; the electrolyte salt is in the Li / CF x The concentration of the electrolyte in the battery is 0.8 mol / L; x The total mass of the electrolyte of the battery is 100%, the mass of the alkenyl-containing silane A accounts for 0.5%, the mass of the alkoxy-containing silane B accounts for 0.1%, and the mass of the silane C containing both alkenyl and alkoxy accounts for 0.3%.

[0061] Embodiment 11

[0062] This embodiment provides a Li / CF x The electrolyte of the battery, keeping the electrolyte matrix unchanged, adjusting the mass proportion of the alkenyl-containing silane A from 1.5% to 0.07%. Except for the above, other conditions are exactly the same as those in Example 1.

[0063] Example 12

[0064] This embodiment provides a Li / CF x The electrolyte of the battery, keeping the electrolyte matrix unchanged, adjusting the mass proportion of the alkenyl-containing silane A from 1.5% to 0.5%. Except for the above, other conditions are exactly the same as those in Example 1.

[0065] Example 13

[0066] This embodiment provides a Li / CF x The electrolyte of the battery, keeping the electrolyte matrix unchanged, adjusting the mass proportion of the alkenyl-containing silane A from 1.5% to 1.1%. Except for the above, other conditions are exactly the same as those in Example 1.

[0067] Embodiment 14

[0068] This embodiment provides a Li / CF x The electrolyte of the battery, keeping the electrolyte matrix unchanged, adjusting the mass proportion of the alkenyl-containing silane A from 1.5% to 4%. Except for the above, other conditions are exactly the same as those in Example 1.

[0069] Embodiment 15

[0070] This embodiment provides a Li / CF x The electrolyte of the battery, keeping the electrolyte matrix unchanged, adjusting the mass proportion of the alkenyl-containing silane A from 1.5% to 7%. Except for the above, other conditions are exactly the same as those in Example 1.

[0071] Example 16

[0072] This embodiment provides a Li / CF x The electrolyte of the battery, keeping the electrolyte matrix unchanged, adjusting the mass proportion of the alkoxy-containing silane B from 0.2% to 0.07%. Except for the above, other conditions are exactly the same as those in Example 1.

[0073] Embodiment 17

[0074] This embodiment provides a Li / CF x The electrolyte of the battery, keeping the electrolyte matrix unchanged, adjusting the mass proportion of the alkoxy-containing silane B from 0.2% to 0.35%. Except for the above, other conditions are exactly the same as those in Example 1.

[0075] Embodiment 18

[0076] This embodiment provides a Li / CF x The electrolyte of the battery, keeping the electrolyte matrix unchanged, adjusting the mass proportion of the alkoxy-containing silane B from 0.2% to 0.5%. Except for the above, other conditions are exactly the same as those in Example 1.

[0077] Embodiment 19

[0078] This embodiment provides a Li / CF x The electrolyte of the battery, keeping the electrolyte matrix unchanged, adjusting the mass proportion of the alkoxy-containing silane B from 0.2% to 1%. Except for the above, other conditions are exactly the same as those in Example 1.

[0079] Embodiment 20

[0080] This embodiment provides a Li / CF x The electrolyte of the battery, keeping the electrolyte matrix unchanged, adjusting the mass proportion of the alkoxy-containing silane B from 0.2% to 3%. Except for the above, other conditions are exactly the same as those in Example 1.

[0081] Comparative Example 1

[0082] This comparative example provides a Li / CF xThe electrolyte of the battery, keeping the electrolyte matrix unchanged, adjusting the mass proportion of the alkenyl-containing silane A from 1.5% to 0%, and adjusting the mass proportion of the alkoxy-containing silane B from 0.3% to 0%, that is, without using any silane additives. Except for the above, other conditions are exactly the same as those in Example 1.

[0083] The Li / CF x The preparation method of the electrolyte of the battery is to mix the solvents in a glove box filled with argon gas to obtain a mixed solvent, and then add electrolyte salt and silane additive to the mixed solvent to obtain the Li / CF x The electrolyte of the battery.

[0084] Application Example 1

[0085] This application example provides a Li / CF x A battery comprising a carbon fluoride positive electrode sheet, a metal lithium negative electrode sheet, a separator and the Li / CF provided in any one of Examples 1 to 20 or Comparative Example 1 x Battery electrolyte;

[0086] The preparation method of the carbon fluoride positive electrode plate includes: mixing the carbon fluoride active material, the conductive agent and the binder solution according to the mass ratio of the carbon fluoride active material, the conductive agent and the binder of 87:8:5 to form a high viscosity slurry with a viscosity of 12000cp, coating it on the carbon-coated aluminum foil, coating the A side once, and then coating the B side once, the coating thickness is 100μm, and the plate load is 120g / m 2 After drying at 100℃, roller compaction, compaction density 1.26g / cm 3 , porosity 52%, cutting or die-cutting into corresponding sizes to obtain a carbon fluoride positive electrode sheet;

[0087] The battery cell assembly method comprises: cutting the lithium strip into corresponding sizes to obtain a negative electrode lithium sheet with a thickness of 50 μm as a metal lithium negative electrode sheet; assembling the battery cell by winding the carbon fluoride positive electrode sheet, the metal lithium negative electrode sheet and the separator; x The electrolyte of the battery is injected into the battery cell with an injection coefficient of 1.3g / Ah, and the Li / CF x Battery.

[0088] The storage stability of the obtained battery was evaluated by testing the prepared Li / CF x The battery was placed in a 70°C oven and stored for 1 month. The capacity retention rate of the new battery after storage was tested to evaluate the storage stability of the battery. The discharge rate was 0.01C. The results are shown in Table 1.

[0089] Table 1

[0090]

[0091] It can be seen from Table 1 that:

[0092] Comparing Comparative Example 1 with Example 1, it is found that the addition of alkenyl-containing silane and alkoxy-containing silane can improve the storage stability of the lithium carbon fluoride battery.

[0093] Comparing Examples 1-10 and Comparative Example 1, the combined use of alkenyl-containing silanes and alkoxy-containing silanes in appropriate dosage ratios can significantly improve the storage stability of the battery. The alkenyl-containing silanes can form a stable passivation layer on the surface of metallic lithium to inhibit the corrosion and consumption of alkoxysilanes on the surface of metallic lithium. The alkoxy-containing silanes can effectively remove free fluorine and active carbon-fluorine bonds in the fluorinated carbon material, thereby improving the stability of the material.

[0094] Comparing Example 1 and Examples 11-15, the change in the content of alkenyl-containing silane has a significant effect on the storage stability of the battery cell. When the content of alkenyl-containing silane is low (mass proportion <0.1%), it cannot play a good passivation role on metallic lithium. When the content of alkenyl-containing silane is high (mass proportion >5%), it is easy to increase the turbidity of the electrolyte, significantly increase the impedance of the battery cell, and reduce the storage stability.

[0095] Comparing Example 1 and Examples 16-20, when the content of alkoxy-containing silane is low (mass proportion <0.1%), the free fluorine in the fluorinated carbon material cannot be removed, and the storage stability of the battery cell is limitedly improved. When the content of alkoxy-containing silane is high (mass proportion >0.5%), the alkoxysilane is prone to cause severe corrosion to metallic lithium, and the storage stability of the battery cell is reduced.

[0096] In summary, by introducing silane containing alkenyl double bonds and silane containing alkoxy groups as additives in the electrolyte, the stability of the fluorinated carbon material itself is improved, thereby improving the Li / CF x Long-term storage and high-temperature storage stability of batteries.

[0097] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0098] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0099] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A Li / CF x An electrolyte for a battery, characterized in that The invention comprises an electrolyte matrix and a silane additive; the silane additive contains alkenyl and alkoxy groups.

2. Li / CF according to claim 1 x An electrolyte for a battery, characterized in that The mass of the silane additive accounts for the Li / CF x The content is 0.1% to 15%, preferably 0.1% to 5%, and more preferably 0.1% to 2% of the total mass of the electrolyte solution of the battery.

3. Li / CF according to claim 1 or 2 x An electrolyte for a battery, characterized in that The silane additive includes a silane A containing an alkenyl group and a silane B containing an alkoxy group, and / or includes a silane C containing both an alkenyl group and an alkoxy group.

4. Li / CF according to claim 3 x An electrolyte for a battery, characterized in that The chemical formula of the alkenyl-containing silane A includes R 1 b Si a R 2 2a+2-b , wherein a is 1 or 2, b is an integer from 1 to 6, and 2a+2-b is an integer from 0 to 5; R 1 is C2-C4 alkenyl; R 2 is a C1-C3 alkyl group; Preferably, the alkenyl-containing silane A includes at least one of vinyltrimethylsilane, vinyltriethylsilane, divinyldimethylsilane, divinyldipropylsilane, trivinylmethylsilane, trivinylethylsilane, trivinylpropylsilane, tetravinylsilane, tetraallylsilane or divinyltetramethyldisilane; preferably at least one of divinyldimethylsilane, trivinylmethylsilane, trivinylethylsilane or tetravinylsilane.

5. Li / CF according to claim 3 or 4 x An electrolyte for a battery, characterized in that The chemical formula of the alkoxy-containing silane B includes R 4 4-c Si(OR 3 ) c , where c is an integer from 1 to 4; R 3 Including C1-C3 alkyl; R 4 Including at least one of a C1-C20 alkyl group or a halogenated alkyl group, or a C5-C20 aryl group or a halogenated aryl group; Preferably, the alkoxy-containing silane B includes at least one of tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, phenyltrimethoxysilane, trifluoropropanetrimethoxysilane, dimethyldimethoxysilane, 3,3,3-trifluoropropylmethyldimethoxysilane, triethylmethoxysilane or methoxydimethylphenylsilane; preferably, at least one of ethyltrimethoxysilane, phenyltrimethoxysilane, trifluoropropanetrimethoxysilane, dimethyldimethoxysilane or methoxydimethylphenylsilane.

6. Li / CF according to any one of claims 3 to 5 x An electrolyte for a battery, characterized in that The chemical formula of the silane C containing both alkenyl and alkoxy groups includes R 5 d R 7 4-d-e Si(OR 6 ) e , wherein d is an integer from 1 to 3, e is an integer from 1 to 3, and 4-de is an integer from 0 to 2; R 5 Including C2-C20 alkenyl; R 6 Including C1-C3 alkyl; R 7 Including at least one of a C1-C20 alkyl group or a halogenated alkyl group, or a C5-C20 aryl group or a halogenated aryl group; Preferably, the silane C containing both alkenyl and alkoxy groups includes at least one of vinyltrimethoxysilane, methylvinyldimethoxysilane, vinylphenylmethylmethoxysilane or methylvinyldiethoxysilane.

7. Li / CF according to any one of claims 3 to 6 x An electrolyte for a battery, characterized in that The mass of the alkenyl-containing silane A accounts for the Li / CF x 0.1% to 10% of the total mass of the electrolyte of the battery, preferably 0.1% to 5%, more preferably 0.1% to 2%; Preferably, the mass of the alkoxy-containing silane B accounts for x 0.1% to 5% of the total mass of the electrolyte of the battery, preferably 0.1% to 1%, more preferably 0.1% to 0.5%; Preferably, the mass of the silane C containing alkenyl and alkoxy groups accounts for x The content is 0.1% to 5%, preferably 0.1% to 1%, and more preferably 0.1% to 0.5% of the total mass of the electrolyte solution of the battery.

8. Li / CF according to any one of claims 3 to 7 x An electrolyte for a battery, characterized in that The electrolyte matrix includes a solvent and an electrolyte salt; Preferably, the electrolyte salt comprises a lithium salt, and the lithium salt comprises at least one of lithium perchlorate, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl imide), lithium bis(fluorosulfonyl imide) or lithium trifluoromethanesulfonate; Preferably, the lithium salt is in the Li / CF x The concentration in the battery electrolyte is 0.5 to 2 mol / L; Preferably, the solvent comprises an organic solvent, and the organic solvent comprises at least one of ethylene glycol dimethyl ether, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate or gamma-martinolactone.

9. A Li / CF x A battery, characterized in that Containing the Li / CF according to any one of claims 1 to 8 x The electrolyte of the battery.

10. Li / CF according to claim 9 x A battery, characterized in that The Li / CF x The electrolyte injection coefficient of the battery is 1.0 to 1.6 g / Ah.

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