Additive for electrolyte, preparation method of additive, electrolyte and electrochemical device

Abstract

The invention relates to an additive for an electrolyte, a preparation method of the additive, the electrolyte and an electrochemical device, and the additive added into the electrolyte can reduce the acidity of a whole battery system, and reduce the dissolution of transition metal in a positive electrode active material and the loss of a negative electrode active material. Compared with other additives in the electrolyte, the additive has higher oxygenolysis potential, oxygenolysis of the electrolyte is effectively inhibited, the stability of solvents such as organic carbonic esters in the electrolyte is improved, the high-temperature resistance and high-voltage resistance stability of the lithium ion battery are further improved, meanwhile, the electrolyte can have good wettability and low viscosity, and the electrolyte can be used for lithium ion batteries. The lithium ion conductivity can be well improved, the rate capability and the safety of the battery are improved, and the electrolyte additive is a novel electrolyte additive for the lithium ion battery.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical technology, and in particular to an additive for an electrolyte and a preparation method thereof, an electrolyte, and an electrochemical device. Background Art

[0002] Lithium-ion batteries have been widely used in electronic products, electric vehicles, and large-scale energy storage due to their high energy density, long service life, and low self-discharge rate. At present, the energy density of lithium-ion batteries cannot meet the growing demand. High-nickel ternary materials, lithium-manganese-rich materials, lithium cobalt oxide and other positive electrode active materials are considered to be the most promising positive electrode materials for the development of high-energy-density lithium-ion batteries due to their high specific capacity and energy density. However, these materials still have some shortcomings in application, such as poor material structure stability, high voltage, high temperature, short cycle life, fast capacity decay during the cycle, and no matching high-voltage electrolyte. At the same time, silicon-based negative electrode materials, as a potential next-generation lithium-ion battery negative electrode active material with greater specific capacity, also have the problems of volume expansion and repeated thickening of the interface layer during the cycle that need to be overcome.

[0003] At present, the electrolyte will decompose on the electrode surface during the battery cycle, generating various compounds containing phosphorus and fluorine, and finally further decompose to form hydrofluoric acid. Hydrofluoric acid will corrode the positive electrode active material, causing the dissolution of transition metals, and will also react with the negative electrode active material, causing the loss of negative electrode active material, resulting in the attenuation of capacity and cycle life. Summary of the invention

[0004] The purpose of the present application is to provide an additive for an electrolyte and a preparation method thereof, an electrolyte, and an electrochemical device. The additive added to the electrolyte can reduce the acidity of the entire battery system, reduce the dissolution of transition metals in the positive electrode active material and the loss of the negative electrode active material, and improve the capacity and cycle life of the battery.

[0005] In a first aspect, the present application provides an additive for an electrolyte, wherein the additive comprises a functional compound of the structural formula shown in Formula I:

[0006]

[0007] In the structural formula shown in Formula I, R 1 Selected from C1-C5 alkyl, C1-C5 alkoxy;

[0008] R 2 , R 3 and R 4 Each independently selected from C1-C5 alkyl, C1-C5 alkoxy, -(CH2)3N(CH2CH2CN)2, -(CH2)4N(CH2CH2CN)2, -R5 OCH2CH2N + (CH3)3A - , and R 2 , R 3 and R 4 At least one of -(CH2)3N(CH2CH2CN)2, -(CH2)4N(CH2CH2CN)2 or -R 5 OCH2CH2N + (CH3)3A - ; Among them, R 5 Selected from -(CH2)2-, -(CH2)3-, -(CH2)2CO-, -(CH2)3CO-, anion A - Selected from Cl - Br - ,I - TFSI - PF6 - ;

[0009] n is a natural number selected from 0 to 4.

[0010] In some embodiments, the functional compound is selected from the compounds of the following structural formula I-1:

[0011]

[0012] In the structural formula shown in Formula I-1, R 3 , R 4 All selected from -R 5 OCH2CH2N + (CH3)3A - ;or,

[0013] R 3 and R 4 One of them is selected from C1-C5 alkyl or C1-C5 alkoxy, and the other is selected from -(CH2)3N(CH2CH2CN)2, -(CH2)4N(CH2CH2CN)2 or -R 5 OCH2CH2N + (CH3)3A - .

[0014] In some embodiments, when n is selected from a natural number of 1 to 4, R 2 , R 3 and R 4 One or two of the groups are selected from C1-C5 alkyl or C1-C5 alkoxy, and the remaining groups are selected from -(CH2)3N(CH2CH2CN)2, -(CH2)4N(CH2CH2CN)2 or -R 5OCH2CH2N + (CH3)3A - .

[0015] In a second aspect, the present application provides a method for preparing an additive for an electrolyte, the preparation method comprising:

[0016] Under the protection of inert gas, a double bond compound containing an amino group and an ionic liquid group or a double bond compound containing an amino group and a nitrile group and an organic siloxane are subjected to a hydrosilylation reaction under the action of a catalyst to obtain a functional compound.

[0017] In some embodiments, the molar ratio of the double bond compound containing an amino group and an ionic liquid group or the double bond compound containing an amino group and a nitrile group to the organosilane is 1:(1.0-1.2).

[0018] In some embodiments, the double bond compound containing an amino group and an ionic liquid group is selected from acryloyloxyethyltrimethylammonium chloride or 2-methacryloyloxyethyltrimethylammonium chloride.

[0019] In some embodiments, the temperature of the hydrosilylation reaction is 45°C to 130°C.

[0020] In some embodiments, the hydrosilylation reaction time is 4 hours to 24 hours.

[0021] In some embodiments, the organosiloxane is selected from 1,1,1,3,3-pentamethyldisiloxane, 1,1,3,3-tetramethyldisiloxane or 1,1,3,3,5,5,5-heptamethyltrisiloxane.

[0022] In some embodiments, the catalyst is selected from chloroplatinic acid or Karstedt's catalyst.

[0023] In some embodiments, the molar ratio of the catalyst to the double bond compound containing an amino group and an ionic liquid group or the double bond compound containing an amino group and a nitrile group is (0.1-1):1.

[0024] In some embodiments, the method further comprises preparing a double bond compound containing a nitrile group, and the method further comprises preparing a double bond compound containing a nitrile group and an amino group, comprising the following steps:

[0025] Under the protection of inert gas, 3,3-iminodipropionitrile is subjected to a substitution reaction with a brominated double bond compound to prepare a double bond compound containing a nitrile group and an amino group; wherein the brominated double bond compound is allyl bromide or 4-bromo-1-butene.

[0026] In some embodiments, the temperature of the substitution reaction is 70-100°C.

[0027] In some embodiments, the substitution reaction time is 10 h to 24 h.

[0028] In some embodiments, the molar ratio of the 3,3-imidodipropionitrile to the brominated double bond compound is 1:(1.05-1.5).

[0029] In a third aspect, the present application provides an electrolyte, wherein the electrolyte comprises the additive for the electrolyte described in the first aspect.

[0030] In some embodiments, based on the total mass of the electrolyte being 100%, the mass proportion of the additive in the electrolyte is 0.1% to 5%.

[0031] In some embodiments, the electrolyte further includes a solvent and a lithium salt, and the concentration of the lithium salt in the electrolyte is 0.5 mol / L to 1.5 mol / L.

[0032] In some embodiments, the solvent includes a carbonate ester, and the carbonate ester includes at least one of dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, butylene carbonate, or methyl propyl carbonate.

[0033] In some embodiments, the solvent includes ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate in a mass ratio of 1:1:1.

[0034] In a third aspect, the present application provides an electrochemical device, comprising a positive electrode plate, a negative electrode plate, a separator and the electrolyte described in the second aspect, wherein the positive electrode plate comprises a lithium cobalt oxide material.

[0035] In some embodiments, the negative electrode plate includes a negative electrode active material, and the negative electrode active material includes at least one of graphite, silicon, silicon-oxygen material, silicon-carbon composite, silicon-nitrogen composite, silicon alloy and hard carbon.

[0036] In a fourth aspect, the present application provides an electronic device, wherein the electronic device comprises the above-mentioned electrochemical device.

[0037] Compared with the prior art, this application has at least the following beneficial effects:

[0038] The additive for the electrolyte provided in the present application can be oxidized on the surface of the positive electrode plate before other components in the electrolyte, and reduced on the surface of the negative electrode plate before other components in the electrolyte, forming a stable electrode-electrolyte interface layer, isolating the electrolyte and the positive electrode active material and the negative electrode active material from contacting each other, reducing the dissolution of transition metals in the positive electrode active material, and improving the strength of the negative electrode plate interface.

[0039] Secondly, the amino group in the siloxane compound, as an alkaline group, can neutralize the hydrogen fluoride produced by the decomposition of the electrolyte, reduce the acidity of the battery system, and increase the life of the positive and negative electrodes. The nitrile group or ionic liquid group in the siloxane compound can form an ion complex with the transition metal in the positive electrode active material, reduce the dissolution of the transition metal in the positive electrode active material, and extend the cycle life of the positive electrode sheet.

[0040] Finally, compared with other additives in the electrolyte, siloxane compounds have a higher oxidative decomposition potential, which can effectively inhibit the oxidative decomposition of the electrolyte, improve the stability of solvents such as organic carbonates in the electrolyte, and thus improve the high temperature and high voltage stability of lithium-ion batteries (the voltage can reach above 4.5V). At the same time, the electrolyte can have good wettability and low viscosity, which can greatly improve the lithium ion conductivity and improve the battery's rate performance and safety. It is a new type of electrolyte additive for lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present application is further described below in conjunction with the accompanying drawings and embodiments.

[0042] Figure 1 A schematic diagram of the system structure of the lithium-ion battery provided in this application;

[0043] Figure 2a The nuclear magnetic resonance hydrogen mass spectrum of the double bond compound A containing a nitrile group and an amino group provided in Example 1 of the present application;

[0044] Figure 2b The carbon nuclear magnetic resonance mass spectrum of the double bond compound A containing a nitrile group and an amino group provided in Example 1 of the present application;

[0045] Figure 3a This is the nuclear magnetic resonance hydrogen mass spectrum of the cyano-functionalized organosiloxane compound (TMSPAN) provided in Example 1 of the present application;

[0046] Figure 3b This is the carbon nuclear magnetic resonance mass spectrum of the cyano-functionalized organosiloxane compound (TMSPAN) provided in Example 1 of the present application;

[0047] Figure 3c The NMR silicon mass spectrum of the cyano-functionalized organosiloxane compound (TMSPAN) provided in Example 1 of the present application;

[0048] Figure 4a This is a nuclear magnetic resonance hydrogen mass spectrum of the cyano-functionalized organosiloxane compound (abbreviated as TSOMCN) provided in Example 2 of the present application;

[0049] Figure 4b This is the carbon NMR mass spectrum of the cyano-functionalized organosiloxane compound (TSOMCN) provided in Example 2 of the present application;

[0050] Figure 4c The NMR silicon mass spectrum of the cyano-functionalized organosiloxane compound (TSOMCN) provided in Example 2 of the present application;

[0051] Figure 5a This is a nuclear magnetic resonance hydrogen mass spectrum of the cyano-functionalized organosiloxane compound (abbreviated as TSOECN) provided in Example 3 of the present application;

[0052] Figure 5b This is the carbon nuclear magnetic resonance mass spectrum of the cyano-functionalized organosiloxane compound (TSOECN) provided in Example 3 of the present application;

[0053] Figure 5c The NMR silicon mass spectrum of the cyano-functionalized organosiloxane compound (TSOECN) provided in Example 3 of the present application;

[0054] Figure 6 This is a linear scanning test curve diagram of the functional compound of Example 1 of the present invention;

[0055] Figure 7 A linear scan test curve diagram of a battery in which the functional compound (TSOMCN) of Example 2 is added and a battery in Comparative Example 1 of the present application;

[0056] Figure 8 Impedance diagram of a battery with functional compound (TSOECN) of Example 3 added to the present application and a battery of Comparative Example 1;

[0057] Figure 9a The charge and discharge curves of the battery added with the functional compound of Example 2 and the battery of Comparative Example 1 at 25°C are shown in the figure;

[0058] Figure 9b The charge and discharge curves of the battery with the functional compound of Example 2 added in the present application and the battery of Comparative Example 1 at 45°C;

[0059] Fig.10 The charge and discharge cycle curves of the battery to which the functional compound of Example 2 is added and the battery of Comparative Example 1 at 25°C are shown. DETAILED DESCRIPTION

[0060] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0061] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0062] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0063] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0064] Figure 1 A schematic diagram of a lithium-ion battery provided for this application, such as Figure 1 As shown in the figure, lithium-ion batteries include positive electrode sheets, negative electrode sheets, electrolytes, diaphragms, and corresponding circuits. The positive and negative active materials are the main parts of lithium batteries that perform energy storage functions and determine the energy density, cycle performance, and safety performance of the battery cell. The electrolyte is the carrier for the transmission of lithium ions between the positive and negative electrodes. The ion-conducting but electronically insulating diaphragm ensures the migration of lithium ions while separating the positive and negative electrodes to prevent short circuits. Among them, the electrolyte is the medium for the transmission of lithium ions between the positive and negative electrodes, and plays an important role in the electrochemical performance and safety performance of the battery.

[0065] During the charging process, under the action of the external circuit, lithium ions are deintercalated from the positive electrode active material and embedded into the negative electrode through the electrolyte diaphragm. At the same time, the positive electrode loses electrons and flows out from the external circuit through the current collector. The discharge process is the opposite. Lithium ions are deintercalated from the negative electrode back to the positive electrode. At the same time, electrons move from the negative electrode to the positive electrode through the external circuit to release energy. The electrolyte is the carrier for lithium ions to be transmitted between the positive and negative electrodes. The ion-conducting but electronically insulating diaphragm ensures the migration of lithium ions while separating the positive and negative electrodes to prevent short circuits.

[0066] The positive and negative electrode active materials are the main parts of lithium batteries that perform energy storage functions and determine the energy density, cycle performance and safety performance of the battery cell.

[0067] At present, the electrolyte will decompose on the surface of the positive and negative electrodes during the battery cycle, generating various compounds containing phosphorus and fluorine, and finally further decompose to form hydrofluoric acid. Hydrofluoric acid will corrode the positive electrode active material, causing the dissolution of transition metals, and will also react with the negative electrode active material, causing the loss of negative electrode active material, resulting in the attenuation of capacity and cycle life.

[0068] In some embodiments, in order to protect the positive electrode, a large amount of nitrile compounds are generally added to the electrolyte, and nitrile compounds can bring about the improvement of the impedance of the battery system. In order to limit the growth of impedance, other phosphate and sulfate compounds need to be added to the electrolyte, but the screening and adaptation of various additives require a lot of time and cost. Similarly, in order to protect the negative electrode, a large amount of fluoroethylene carbonate is generally added to the electrolyte to generate a protective solid electrolyte film on the negative electrode surface, protect the negative electrode and improve the cycle performance. However, the film-forming product of fluoroethylene carbonate is difficult to resist the volume expansion stress of silicon, resulting in the rupture of the solid electrolyte film on the negative electrode surface, and the electrolyte continues to contact with the negative electrode active material, and causes the sustainable thickening of the interface product, thereby causing the volume expansion of the battery cell and a substantial increase in impedance.

[0069] In other embodiments, in order to reduce the acidity of the electrolyte system, electron-deficient borane (such as tri(pentafluorophenyl)borane) is added to neutralize the hydrofluoric acid in the electrolyte, but such materials are expensive and it is difficult to suppress the increase in impedance.

[0070] In order to solve the above problems, the present application proposes an additive for electrolyte. Adding the additive to the electrolyte can reduce the acidity of the entire battery system, reduce the dissolution of transition metals in the positive electrode active material and the loss of the negative electrode active material, and improve the capacity and cycle life of the battery.

[0071] As an optional technical solution of the present application, the electrolyte includes a solvent, a lithium salt and an additive.

[0072] As an optional technical solution of the present application, the solvent includes a carbonate, and the carbonate includes at least one of dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, butylene carbonate or methyl propyl carbonate.

[0073] As an optional technical solution of the present application, the lithium salt includes at least one of lithium perchlorate (LiClO4), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), and lithium trifluoromethanesulfonate (LiCF3SO3).

[0074] In this embodiment, the additive includes a compound of the structural formula shown in Formula I:

[0075]

[0076] In the structural formula shown in Formula I, R 1 Selected from C1-C5 alkyl, C1-C5 alkoxy;

[0077] R 2 , R 3 and R 4Each independently selected from C1-C5 alkyl, C1-C5 alkoxy, -(CH2)3N(CH2CH2CN)2, -(CH2)4N(CH2CH2CN)2, -R 5 OCH2CH2N + (CH3)3A - , and R 2 , R 3 and R 4 At least one of -(CH2)3N(CH2CH2CN)2, -(CH2)4N(CH2CH2CN)2 or -R 5 OCH2CH2N + (CH3)3A - ; Among them, R 5 Selected from -(CH2)2-, -(CH2)3-, -(CH2)2CO-, -(CH2)3CO-, anion A - Selected from Cl - Br - ,I - TFSI - PF6 - ;

[0078] n is a natural number selected from 0 to 4.

[0079] In the above scheme, the amino group in the siloxane compound acts as an alkaline group, which can neutralize the hydrogen fluoride produced by the decomposition of the electrolyte, reduce the acidity of the battery system, and increase the life of the positive and negative electrodes. The nitrile group or ionic liquid group in the siloxane compound can form an ion complex with the transition metal in the positive electrode active material, reduce the dissolution of the transition metal in the positive electrode active material, and extend the cycle life of the positive electrode sheet.

[0080] Moreover, under high voltage conditions, the siloxane compound in the additive can be oxidized on the surface of the positive electrode plate before other components in the electrolyte, and reduced on the surface of the negative electrode plate before other components in the electrolyte, forming a stable electrode-electrolyte interface layer, isolating the electrolyte and the positive electrode active material, and the negative electrode active material from contacting each other, reducing the dissolution of transition metals in the positive electrode active material, and improving the strength of the negative electrode plate interface.

[0081] Finally, compared with other additives in the electrolyte, siloxane compounds have a higher oxidative decomposition potential, which can effectively inhibit the oxidative decomposition of the electrolyte, improve the stability of solvents such as organic carbonates in the electrolyte, and thus improve the high temperature and high voltage stability of lithium-ion batteries (the voltage can reach above 4.5V). At the same time, the electrolyte can have good wettability and low viscosity, which can greatly improve the lithium ion conductivity and improve the battery's rate performance and safety. It is a new type of electrolyte additive for lithium-ion batteries.

[0082] In some embodiments, the siloxane compound is selected from the compounds represented by the following structural formula I-1:

[0083]

[0084] In the structural formula shown in Formula I-1, R 3 , R 4 All selected from -R 5 OCH2CH2N + (CH3)3A - ;or,

[0085] R 3 and R 4 One of them is selected from C1-C5 alkyl or C1-C5 alkoxy, and the other is selected from -(CH2)3N(CH2CH2CN)2, -(CH2)4N(CH2CH2CN)2 or -R 5 OCH2CH2N + (CH3)3A - .

[0086] In some embodiments, when n is selected from a natural number of 1 to 4, R 2 , R 3 and R 4 One or two of the groups are selected from C1-C5 alkyl or C1-C5 alkoxy, and the remaining groups are selected from -(CH2)3N(CH2CH2CN)2, -(CH2)4N(CH2CH2CN)2 or -R 5 OCH2CH2N + (CH3)3A - .

[0087] In some embodiments, the additive accounts for 0.1% to 5% of the total mass of the electrolyte, based on 100% of the total mass of the electrolyte. If the mass content of the additive added to the electrolyte is less than 0.1%, a SEI film cannot be formed at the electrode interface; if the mass content of the additive added to the electrolyte is higher than 5%, the amount of additive added increases, and the cost of the electrolyte increases.

[0088] Specifically, the mass proportion of the additive in the electrolyte is 0.1%, 0.15%, 0.18%, 2%, 2.3%, 2.8%, 3%, 3.4%, 4.5%, 4.7% or 5%, etc., and of course it can also be other values ​​within the above range, which is not limited here. The amount of additive added is controlled within the above range, which can not only reduce the acidity of the battery system and improve the life of the positive and negative electrodes, but also reduce the dissolution of transition metals in the positive electrode active material and extend the cycle life of the positive electrode sheet.

[0089] In a second aspect, the present application provides a method for preparing an additive for an electrolyte, comprising the following steps:

[0090] Under the protection of inert gas, a double bond compound containing an amino group and an ionic liquid group or a double bond compound containing an amino group and a nitrile group and an organic siloxane are subjected to a hydrosilylation reaction under the action of a catalyst to obtain a functional compound.

[0091] The hydrosilylation reaction mechanism of the double bond compound containing amino group and ionic liquid group and organosiloxane is as shown in the following formula II-1 or formula II-2:

[0092]

[0093] Wherein, n1 is selected from a natural number of 1 to 4, n2 is selected from 1 or 2; anion A - Selected from Cl - Br - ,I - TFSI - PF6 - .

[0094] In some embodiments, the molar ratio of the double bond compound containing amino group and ionic liquid to the organosilane is 1:(1.0-1.2), specifically 1:1, 1:1.05, 1:1.06, 1:1.08, 1:1.1, 1:1.12, 1:1.15, 1:1.18, 1:1.19 or 1:1.2, etc., and of course, it can also be other values ​​within the above range, which is not limited here. Controlling the molar ratio of the two within the above range can ensure that the hydrosilation reaction is fully carried out.

[0095] In some embodiments, the double bond compound containing an amino group and an ionic liquid is selected from acryloyloxyethyltrimethylammonium chloride or 2-methacryloyloxyethyltrimethylammonium chloride.

[0096] In another embodiment, the hydrosilylation reaction mechanism of the double bond compound containing nitrile group and amino group and the organosiloxane is shown in the following formula II-3:

[0097] Formula II-3

[0098]

[0099] Among them, n1 is selected from a natural number of 1 to 4, and n2 is selected from 1 or 2.

[0100] In some embodiments, the molar ratio of the double bond compound containing nitrile group and amino group to the organosilane is 1:(1.0-1.2), specifically 1:1, 1:1.05, 1:1.06, 1:1.08, 1:1.1, 1:1.12, 1:1.15, 1:1.18, 1:1.19 or 1:1.2, etc., and of course, it can also be other values ​​within the above range, which is not limited here. Controlling the molar ratio of the two within the above range can ensure that the hydrosilylation reaction is fully carried out.

[0101] As shown in formula II-3, the method further comprises: preparing a double bond compound containing a nitrile group and an amino group. The specific synthesis steps are:

[0102] Under the protection of inert gas, 3,3-iminodipropionitrile is subjected to a substitution reaction with a brominated double bond compound to prepare a double bond compound containing a nitrile group and an amino group; wherein the brominated double bond compound is allyl bromide or 4-bromo-1-butene.

[0103] Specifically, the cyano group-containing double bond compound may be double bond imine dipropionitrile.

[0104] In some embodiments, the temperature of the substitution reaction is 70-100°C, specifically 70°C, 80°C, 85°C, 90°C, 95°C or 100°C, etc.; the reaction time is 10h-24h, specifically 10h, 12h, 16h, 18h, 20h, 22h or 24h, etc., and of course it can also be other values ​​within the above range, which is not limited here.

[0105] In some embodiments, the molar ratio of 3,3-imidodipropionitrile to the brominated double bond compound is 1:(1.05-1.5), specifically 1:1.05, 1:1.08, 1:1.2, 1:1.5, 1:1.2, 1:1.3, 1:1.35, 1:1.4 or 1:1.5, etc., and of course, it can also be other values ​​within the above range, which is not limited here. Controlling the molar ratio of the two within the above range can ensure that the substitution reaction is fully carried out.

[0106] In the hydrosilylation reaction shown in formula II-1, II-2 or II-3 of the present application, the temperature of the hydrosilylation reaction is 45°C to 130°C, and specifically can be 45°C, 45°C, 45°C, 45°C, 45°C, 45°C, 45°C, 45°C, 45°C, 45°C, 45°C or 45°C, etc., and of course can also be other values ​​within the above range, which is not limited here.

[0107] The time of the hydrosilylation reaction is 4 h to 24 h, and specifically can be 4 h, 5 h, 6 h, 7 h, 8 h, 10 h, 12 h, 15 h, 18 h, 20 h or 24 h, etc., and of course can also be other values ​​within the above range, which is not limited here.

[0108] In some embodiments, the organosiloxane is 1,1,1,3,3-pentamethyldisiloxane, 1,1,3,3-tetramethyldisiloxane or 1,1,3,3,5,5,5-heptamethyltrisiloxane.

[0109] In some embodiments, the catalyst is selected from chloroplatinic acid or Karstedt's catalyst. Karstedt's catalyst is an organic platinum compound extracted from divinyl disiloxane. This coordination complex can be used for hydroxysilylation catalysis. It is a colorless solid and is generally considered to be a mixture of related Pt(0)-olefin complexes.

[0110] In some embodiments, the molar ratio of the catalyst to the double bond compound containing a nitrile group and an amino group or the double bond compound containing an ionic liquid and an amino group is (0.1-1):1, specifically 0.1:1, 0.2:1, 0.3:1, 0.5:1, 0.7:1, 0.8:1, 0.9:1 or 1:1, etc., and of course, it can also be other values ​​within the above range, which are not limited here. Controlling the amount of catalyst added can ensure that the hydrosilation reaction is fully carried out.

[0111] In a third aspect, the present application provides an electrochemical device, which includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte.

[0112] Specifically, the negative electrode plate includes a negative electrode current collector and a negative electrode active layer disposed on the surface of the negative electrode current collector, wherein the negative electrode active layer includes a negative electrode active material, a conductive material and a binder.

[0113] In some embodiments, the negative electrode active material includes at least one of elemental silicon, silicon oxide, silicon carbon composite, silicon nitrogen composite and silicon alloy. For example, the silicon oxide may be silicon monoxide. The silicon alloy may be silicon magnesium alloy, silicon lithium alloy and the like.

[0114] In some embodiments, the silicon-carbon composite material can be a silicon-carbon composite material obtained by carbon coating a silicon material, a silicon-carbon composite material obtained by sintering a silicon material, a silicon-carbon composite material obtained by ball milling a silicon material and a carbon material, or a silicon-carbon composite material obtained by chemical vapor deposition a silicon material and a carbon material, etc. It can also be a composite material of silicon oxide and carbon material, which is not limited here. In the present application, a silicon-based negative electrode active material with a gram capacity greater than 600 mAh / g can be selected to increase the specific capacity of the negative electrode sheet.

[0115] In some other embodiments, the negative electrode active material may further include a phosphorus-based material, the phosphorus-based material including at least one of elemental phosphorus and a phosphorus-carbon composite. Exemplarily, the elemental phosphorus includes at least one of red phosphorus, black phosphorus, purple phosphorus or blue phosphorus. Exemplarily, the phosphorus-carbon composite is prepared by compounding elemental phosphorus and a carbon material by ball milling or vapor deposition, and the carbon material includes at least one of graphite, carbon nanotubes, porous carbon, hard carbon, soft carbon or graphene, which is not limited here.

[0116] It can be understood that the active material in the negative electrode active layer is a silicon-based negative electrode active material or a phosphorus-based material with a higher theoretical capacity, which can improve the comprehensive specific capacity of the negative electrode plate.

[0117] Furthermore, the positive electrode plate includes a positive electrode current collector and a positive electrode active layer arranged on the surface of the positive electrode current collector, wherein the positive electrode active layer includes a positive electrode active material, a conductive material and a binder.

[0118] As an optional technical solution of the present application, the positive electrode current collector may be aluminum foil or nickel foil, etc., which is not limited here. As an optional technical solution of the present application, the positive electrode active material includes lithium cobalt oxide.

[0119] The conductive material includes at least one of conductive graphite, conductive carbon black, acetylene black, carbon nanotubes and graphene.

[0120] The binder can improve the bonding between the positive electrode active material particles and also improve the bonding between the positive electrode active material and the positive electrode current collector. Optionally, the binder includes at least one of polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (ester) styrene-butadiene rubber, epoxy resin or nylon.

[0121] In the above electrochemical device, the electrolyte includes a lithium salt and a solvent, the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(oxalatoborate), lithium difluoro(oxalatoborate), lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, and lithium bis(fluorosulfonyl)imide. The solvent includes at least one of ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC).

[0122] The electrolyte also includes other additives. There is no particular limitation on the types of other additives. They may be negative electrode film-forming additives, positive electrode film-forming additives, or additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high temperature performance, additives that improve battery low temperature performance, etc.

[0123] As an optional technical solution of the present application, the isolation membrane is selected from a composite of one or more of polyethylene film, polypropylene film, and polyvinylidene fluoride film. Of course, an inorganic or organic coating can also be coated on the surface of the isolation membrane substrate according to actual needs to enhance the hardness of the battery cell or improve the adhesion between the isolation membrane and the cathode and anode interfaces.

[0124] In a specific embodiment, the electrochemical device may be a primary battery, a secondary battery, a solid-state battery or a lithium-ion battery, which is not limited here.

[0125] In some embodiments, the preparation of the battery comprises the following steps:

[0126] The prepared negative electrode sheet is subjected to rolling, striping, die-cutting, assembly and other processes, and is matched with a suitable positive electrode sheet to prepare a lithium-ion battery. The battery manufacturing process can be lamination or winding. The battery specifications can be cylindrical cells, soft-pack cells, square-shell cells or other types of lithium-ion batteries.

[0127] Environment and equipment required for preparation: planetary high-speed stirring and dispersing equipment, extrusion coating equipment, transfer coating equipment, vacuum heating equipment, lithium-ion battery production equipment, clean room, etc., not limited here.

[0128] In a fourth aspect, the present application further provides an electronic device, wherein the electronic device is the electrochemical device described in the third aspect. The electrochemical device of the present application has good cycle performance and safety performance, and therefore, the above electrochemical device is applied in the electronic device, so that the electronic device has good safety performance and can also extend the service life of the electronic device.

[0129] The electronic devices in this application may specifically be mobile phones, computers, tablet computers, smart bracelets, smart watches, etc., without limitation herein.

[0130] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

[0131] The present application is further described below by taking lithium-ion batteries as an example through specific embodiments and comparative examples.

[0132] Example 1

[0133] (1) Synthesis of double bond compounds containing nitrile group and amino group:

[0134] Under Ar atmosphere, allyl bromide (150g, 1.25mol) and 3,3-imidodipropionitrile (102.6g, 0.834mol) were added to a 500mL two-necked flask in sequence, and the reaction was stopped after 16h at 80℃. A certain amount of deionized water was added to the reaction flask, and the aqueous phase was separated by ether extraction. The aqueous phase was adjusted to PH=9 with 10% NaOH solution, and then extracted three times with ethyl acetate. The organic phases were combined and dried over anhydrous sodium sulfate to obtain 114.57g of the initial product, with a yield of 84.3%. Double bond compounds A (AZNDPAN, boiling point: 147℃, 2.1mmHg) and B (DANPAN, boiling point: 52℃, 3.2mmHg) containing nitrile and amino groups were obtained by reduced pressure distillation.

[0135] Among them, the double bond compound A containing a nitrile group and an amino group is 3-(diallylamino)propionitrile, and the compound B containing a nitrile group and an amino group is (bis-2-propenylamino)propionitrile, and the chemical structural formula is shown in the formula:

[0136]

[0137] Figure 2a The nuclear magnetic resonance hydrogen mass spectrum of the double bond compound A containing a nitrile group and an amino group provided in Example 1 of the present application is as follows: Figure 2a As shown, the double bond compound A containing nitrile group and amino group 1 H NMR spectrum (400 MHz, CDCl3): δ 5.84-5.77 (m, 1H), 5.26-5.18 (dd, 2H), 5.84-5.77 (m, 1H), 3.20-3.18 (m, 2H), 2.88-2.85 (t, J = 4 Hz, 4H), 2.49-2.45 (t, J = 6.8 Hz, 4H);

[0138] Figure 2b The carbon nuclear magnetic resonance mass spectrum of the double bond compound A containing a nitrile group and an amino group provided in Example 1 of the present application is as follows: Figure 2b As shown, the double bond compound A containing nitrile group and amino group 13 C-NMR (100MHz, CDCl3): δ134.2,118.7,118.5,56.6,49.3,16.9.

[0139] (2) subjecting a double bond compound A containing a nitrile group and an amino group to a hydrosilylation reaction with an organosiloxane:

[0140] In an Ar atmosphere, pentamethyldisiloxane (95.64 g, 0.646 mol), a certain amount of chloroplatinic acid and a double bond compound A containing a nitrile group and an amino group (70.23 g, 0.431 mol) were added to a 25 mL two-necked flask in sequence, and the reaction was stopped after the hydrosilylation reaction at 100 ° C for 5 h. After reduced pressure distillation, 110 g of a cyano-functionalized organosiloxane compound (boiling point: 175 ° C, 2.5 mmHg) was obtained.

[0141] The chemical structure of the cyano-functionalized organosiloxane compound (abbreviated as TMSPAN) is shown below:

[0142]

[0143] Figure 3a The nuclear magnetic resonance hydrogen mass spectrum of the cyano-functionalized organosiloxane compound (TMSPAN) provided in Example 1 of the present application is as follows: Figure 3a As shown, the cyano-functionalized organosiloxane compound 1 H NMR spectrum (400 MHz, CDCl3): δ 2.87 (t, J = 6.8 Hz, 4H), 2.52 (t, J = 7.4 Hz, 2H), 2.46 (t, J = 6.8 Hz, 4H), 1.50-1.40 (m, 2H), 0.53-0.44 (m, 2H), 0.09-0.04 (m, 15H).

[0144] Figure 3b The carbon NMR mass spectrum of the cyano-functionalized organosiloxane compound (TMSPAN) provided in Example 1 of the present application is as follows: Figure 3b As shown, the cyano-functionalized organosiloxane compound 13 C-NMR (100MHz, CDCl3): δ118.5, 55.7, 49.6, 21.1, 16.9, 15.4, 1.9, 0.3.29 Si-NMR (100MHz, CDCl3): δ7.262, 7.083.

[0145] Figure 3c The NMR silicon mass spectrum of the cyano-functionalized organosiloxane compound (TMSPAN) provided in Example 1 of the present application is as follows: Figure 3c As shown, the cyano-functionalized organosiloxane compound 29 Si-NMR (100MHz, CDCl3): δ7.262,7.083.

[0146] (3) Preparation of electrolyte

[0147] The cyano-functionalized organosiloxane compound prepared in step (2) is added to the basic electrolyte with a mass content of 0.2 wt%. The basic electrolyte is from Shanghai Xiaoyuan Energy Technology Co., Ltd. and contains 1 mol / L LiPF6, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate in a mass ratio of 1:1:1.

[0148] Example 2

[0149] (1) A double bond compound A containing a nitrile group and an amino group is subjected to a hydrosilylation reaction with an organosiloxane:

[0150] Under Ar atmosphere, 1,1,1,3,5,5,5-heptamethyltrisiloxane (5 g, 22.51 mmol), 3-(diallylamino)propionitrile (3.5 g, 21.44 mmol) and a certain amount of chloroplatinic acid were added in sequence into a 25 ml two-necked flask. The mixture was refluxed at 120 °C for 15 h and the target product was obtained by distillation under reduced pressure (boiling point: 178 °C, 2 mmHg).

[0151] in, Figure 4a This is a nuclear magnetic resonance hydrogen mass spectrum of the cyano-functionalized organosiloxane compound (abbreviated as TSOMCN) provided in Example 2 of the present application. The chemical structure of the cyano-functionalized organosiloxane compound (TSOMCN) is shown below:

[0152]

[0153] Cyano-functionalized organosiloxane compounds (TSOMCN) 1 H NMR spectrum (400 MHz, CDCl3): δ 2.87 (t, J = 6.8 Hz, 4H), 2.54-2.43 (m, 6H), 1.50-1.38 (m, 2H), 0.49-0.38 (m, 2H), 0.09 (s, 18H), 0.02 (s, 3H). 13 C-NMR (100MHz, CDCl3): δ118.5,56.4,49.6,20.8,16.9,14.6,1.7,0.4. 29 Si-NMR (100MHz, CDCl3): δ7.5, -22.0.

[0154] Figure 4b This is the carbon NMR mass spectrum of the cyano-functionalized organosiloxane compound (TSOMCN) provided in Example 2 of the present application; Figure 4c This is the NMR silicon mass spectrum of the cyano-functionalized organosiloxane compound (TSOMCN) provided in Example 2 of the present application.

[0155] (2) Preparation of electrolyte

[0156] The cyano-functionalized organosiloxane compound prepared in step (1) is added to the basic electrolyte with a mass content of 0.2 wt%. The basic electrolyte is from Shanghai Xiaoyuan Energy Technology Co., Ltd. and contains 1 mol / L LiPF6, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate in a mass ratio of 1:1:1.

[0157] Example 3

[0158] (1) A double bond compound A containing a nitrile group and an amino group is subjected to a hydrosilylation reaction with an organosiloxane:

[0159] Under Ar atmosphere, 1,1,1,3,3,5,5-heptamethyltrisiloxane (45.8 g, 0.206 mol), 3-(diallylamino)propionitrile (32 g, 0.196 mol) and a certain amount of Karstedt's reagent were added in sequence into a 100 mL two-necked flask, reacted at 80 ° C for 5 h, and the target product was obtained by reduced pressure distillation (boiling point: 184 ° C, 1.05 mmHg).

[0160] in, Figure 5a This is a nuclear magnetic resonance hydrogen mass spectrum of the cyano-functionalized organosiloxane compound (abbreviated as TSOECN) provided in Example 3 of the present application. The chemical structure of the cyano-functionalized organosiloxane compound (TSOECN) is shown below:

[0161]

[0162] Cyano-functionalized organosiloxane compounds (TSOECN) 1 H NMR spectrum (400 MHz, CDCl3): δ 2.86 (t, J = 6.8 Hz, 4H), 2.52 (t, J = 7.2 Hz, 2H), 2.46 (t, J = 6.8 Hz, 4H), 1.51-1.42 (m, 2H), 0.54-0.48 (m, 2H), 0.08 (s, 15H), 0.02 (s, 6H). 13 C-NMR (100MHz, CDCl3): δ118.5,56.8,49.7,21.1,17.0,15.4,1.8,1.2,0.2. 29 Si-NMR (79.5MHz, CDCl3): δ7.2, 7.1, -20.8.

[0163] Figure 5b This is the carbon nuclear magnetic resonance mass spectrum of the cyano-functionalized organosiloxane compound (TSOECN) provided in Example 3 of the present application; Figure 5c This is the silicon nuclear magnetic resonance mass spectrum of the cyano-functionalized organosiloxane compound (TSOECN) provided in Example 3 of the present application.

[0164] (2) Preparation of electrolyte

[0165] The ionic liquid functionalized organosiloxane compound prepared in step (1) is added to the basic electrolyte with a mass content of 0.2 wt%. The basic electrolyte is from Shanghai Xiaoyuan Energy Technology Co., Ltd. and contains 1 mol / L LiPF6, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate in a mass ratio of 1:1:1.

[0166] Example 4

[0167] (1) Hydrosilylation of a double bond compound containing an ionic liquid group with an organosiloxane:

[0168] Under Ar atmosphere, 2-methacryloyloxyethyltrimethylammonium chloride (2.284 g, 11 mmol), a certain amount of Karstedt's catalyst and pentamethyldisiloxane (4.38 g, 10 mmol) were added in sequence into a 25 ml two-necked flask, and the hydrosilylation reaction was carried out at 50°C for 12 h to obtain an ionic liquid functionalized organosiloxane compound.

[0169] The chemical structure of the ionic liquid functionalized organosiloxane compound is shown below:

[0170]

[0171] (2) Preparation of electrolyte

[0172] The ionic liquid functionalized organosiloxane compound prepared in step (1) is added to the basic electrolyte with a mass content of 0.2 wt%. The basic electrolyte is from Shanghai Xiaoyuan Energy Technology Co., Ltd. and contains 1 mol / L LiPF6, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate in a mass ratio of 1:1:1.

[0173] Comparative Example 1

[0174] Basic electrolyte without any additives.

[0175] The subsequent steps are the same as those in Example 1.

[0176] Preparation and testing of soft pack batteries:

[0177] Preparation of positive electrode sheet: 97g of lithium cobalt oxide, 0.5g of acetylene black, and 2.5g of polyvinylidene fluoride were mechanically mixed, and then N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 65wt%, and stirred evenly to obtain a uniform positive electrode slurry. The positive electrode slurry was coated on aluminum foil, and the aluminum foil was dried, cold pressed, cut, slit, and dried to obtain a positive electrode sheet.

[0178] Preparation of negative electrode sheets: After mixing silicon oxide and graphite in a weight ratio of 2:8, 5% battery binder, 5% superconductive carbon black and 90% of the above mixed negative electrode powder are evenly dispersed, an appropriate amount of deionized water is added, and high-speed dispersion and stirring is performed for 5 hours to obtain a uniform slurry with a solid content of 50wt%. The copper foil is dried, cold pressed, cut, slit, and dried to obtain the negative electrode sheet.

[0179] The positive electrode sheet, separator (Celgard 2400), and negative electrode sheet prepared above are stacked in order to obtain a bare cell. The bare cell is placed in an aluminum-plastic film packaging bag, and after drying, the electrolyte is injected, and after vacuum packaging, standing, formation, degassing and other processes, a soft-pack lithium-ion battery is obtained.

[0180] Performance Test:

[0181] At room temperature of 25°C, the soft-pack lithium-ion battery was subjected to constant current charge and discharge tests on a battery testing instrument. The charge and discharge cut-off voltage range was 3.0-4.3V, and the charge and discharge current density was set to 0.1C for 3 weeks, 0.5C for 3 weeks, and then 1C charge and discharge cycles.

[0182] Battery impedance test:

[0183] After the battery cycle was completed, the alternating current impedance spectroscopy (EIS) was tested on an electrochemical workstation with an amplitude of 5 mV and a frequency range of 0.01 Hz to 100 kHz.

[0184] Figure 6 This is a linear scanning test curve diagram of the functional compound of Example 1 of the present invention, such as Figure 6 It can be seen that the cyano-functionalized organosiloxane compound (abbreviated as TMSPAN) will slowly begin to oxidatively decompose at 3.97V, indicating that the functional compound can be used as a film-forming additive in batteries to improve the high temperature and high voltage stability of lithium-ion batteries.

[0185] Figure 7 The linear scan test curve of the battery with the functional compound (TSOMCN) of Example 2 added to this application and the battery of Comparative Example 1 is as follows: Figure 7 As shown, through high temperature cycle comparison, it is found that the battery capacity of Example 2 is slightly improved compared with the battery of Comparative Example 1.

[0186] Figure 8 The impedance diagram of the battery with the functional compound (TSOECN) of Example 3 added to this application and the battery of Comparative Example 1 is as follows: Figure 8 As shown, through high temperature cycle comparison, it is found that the additive of the battery of Example 3 can significantly reduce the impedance of the interface film on the surface of the positive electrode material compared with the battery of Comparative Example 1.

[0187] The battery prepared in Example 2 and the battery in Comparative Example 1 were placed on a Shenzhen Xinwei system for charge / discharge testing, with a charge / discharge voltage of 4.6 V and temperatures of 25° C. and 45° C., respectively. Figure 9a The charge and discharge curves at 25° C. of the battery to which the functional compound of Example 2 is added and the battery of Comparative Example 1 are shown in FIG. Figure 9b The charge and discharge curves of the battery with the functional compound of Example 2 added in this application and the battery of Comparative Example 1 at 45°C are as follows: Figure 9a and Figure 9b As shown, the cycle performance of the battery of Example 2 at room temperature and high temperature is significantly improved compared with that of Comparative Example 1, and the expansion performance is also improved.

[0188] Fig.10 The charge / discharge cycle curves of the battery with the functional compound of Example 2 added to this application and the battery of Comparative Example 1 at 25°C are shown, wherein the battery is charged / discharged on the Shenzhen Xinwei system, the charge / discharge voltage is 3V-4.6V, and the battery of Example 2 and Comparative Example 1 is charged / discharged at a constant current of 1C. Fig.10 As shown, after 150 cycles, the cycle performance of Example 2 is significantly improved compared with that of Comparative Example 1.

Claims

1. An additive for an electrolyte, characterized in that: The additive includes a functional compound of the structural formula shown in Formula I: In the structural formula shown in Formula I, R 1 Selected from C1-C5 alkyl, C1-C5 alkoxy; R 2 , R 3 and R 4 Each independently selected from C1-C5 alkyl, C1-C5 alkoxy, -(CH2)3N(CH2CH2CN)2, -(CH2)4N(CH2CH2CN)2, -R 5 OCH2CH2N + (CH3)3A - , and R 2 , R 3 and R 4 At least one of -(CH2)3N(CH2CH2CN)2, -(CH2)4N(CH2CH2CN)2 or -R 5 OCH2CH2N + (CH3)3A - ; Among them, R 5 Selected from -(CH2)2-, -(CH2)3-, -(CH2)2CO-, -(CH2)3CO-, anion A - Selected from Cl - Br - ,I - TFSI - PF6 - ; n is a natural number selected from 0 to 4.

2. The additive according to claim 1, characterized in that The functional compound is selected from the compounds of the following structural formula I-1: In the structural formula shown in Formula I-1, R 3 , R 4 All selected from -R 5 OCH2CH2N + (CH3)3A - ;or, R 3 and R 4 One of them is selected from C1-C5 alkyl or C1-C5 alkoxy, and the other is selected from -(CH2)3N(CH2CH2CN)2, -(CH2)4N(CH2CH2CN)2 or -R 5 OCH2CH2N + (CH3)3A - .

3. The additive according to claim 1, characterized in that When n is a natural number from 1 to 4, R 2 , R 3 and R 4 One or two of the groups are selected from C1-C5 alkyl or C1-C5 alkoxy, and the remaining groups are selected from -(CH2)3N(CH2CH2CN)2, -(CH2)4N(CH2CH2CN)2 or -R 5 OCH2CH2N + (CH3)3A - .

4. A method for preparing an additive for an electrolyte according to any one of claims 1 to 3, characterized in that: The preparation method comprises: Under the protection of inert gas, a double bond compound containing an amino group and an ionic liquid group or a double bond compound containing an amino group and a nitrile group and an organic siloxane are subjected to a hydrosilylation reaction under the action of a catalyst to obtain a functional compound.

5. The preparation method according to claim 4, characterized in that: The preparation method meets at least one of the following characteristics: 1) The molar ratio of the double bond compound containing an amino group and an ionic liquid group or the double bond compound containing an amino group and a nitrile group to the organosilane is 1:(1.0-1.2); 2) the double bond compound containing an amino group and an ionic liquid group is selected from acryloyloxyethyl trimethyl ammonium chloride or 2-methacryloyloxyethyl trimethyl ammonium chloride; 3) The temperature of the hydrosilation reaction is 45°C to 130°C; 4) The hydrosilation reaction time is 4h to 24h; 5) the organosiloxane is selected from 1,1,1,3,3-pentamethyldisiloxane, 1,1,3,3-tetramethyldisiloxane or 1,1,3,3,5,5,5-heptamethyltrisiloxane; 6) The catalyst is selected from chloroplatinic acid or Karstedt's catalyst; 7) The molar ratio of the catalyst to the double bond compound containing an amino group and an ionic liquid group or the double bond compound containing an amino group and a nitrile group is (0.1-1):

1.

6. The preparation method according to claim 4, characterized in that: The method also includes preparing a double bond compound containing a nitrile group and an amino group, comprising the following steps: Under the protection of inert gas, 3,3-iminodipropionitrile is subjected to a substitution reaction with a brominated double bond compound to prepare a double bond compound containing a nitrile group and an amino group; wherein the brominated double bond compound is allyl bromide or 4-bromo-1-butene.

7. The preparation method according to claim 6, characterized in that: The preparation method meets at least one of the following characteristics: 1) The temperature of the substitution reaction is 70-100°C, 2) The substitution reaction time is 10h to 24h; 3) The molar ratio of the 3,3-imidodipropionitrile to the brominated double bond compound is 1:(1.05-1.5).

8. An electrolyte, characterized in that: The electrolyte comprises the additive for electrolyte according to any one of claims 1 to 3.

9. The electrolyte according to claim 8, characterized in that Taking the total mass of the electrolyte as 100%, the mass proportion of the additive in the electrolyte is 0.1% to 5%.

10. The electrolyte according to claim 9, characterized in that The electrolyte further includes a solvent and a lithium salt, and the electrolyte satisfies at least one of the following characteristics: 1) The concentration of the lithium salt in the electrolyte is 0.5 mol / L to 1.5 mol / L; 2) the solvent comprises a carbonate, and the carbonate comprises at least one of dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, butylene carbonate or methylpropyl carbonate; 3) The solvent comprises ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate in a mass ratio of 1:1:

1.

11. An electrochemical device, characterized in that: The electrochemical device comprises a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte according to any one of claims 8 to 10, wherein the positive electrode sheet comprises a lithium cobalt oxide material.

12. The electrochemical device according to claim 11, characterized in that The negative electrode plate includes a negative electrode active material, and the negative electrode active material includes at least one of graphite, silicon, silicon-oxygen material, silicon-carbon composite, silicon-nitrogen composite, silicon alloy and hard carbon.

13. An electronic device, characterized in that: The electronic device comprises the electrochemical device according to claim 11 or 12.

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