Electrolyte additive and preparation method thereof, electrolyte, battery and electric equipment

Abstract

The invention provides an electrolyte additive and a preparation method thereof, an electrolyte, a battery and electric equipment, and the electrolyte additive comprises a compound as shown in formula 1, and is beneficial to improving the cycle performance, storage performance and other electrochemical performance of the battery.

Description

Technical Field

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

[0002] Batteries are common electrochemical devices with a wide range of applications. For example, lithium-ion batteries are currently widely used in the field of new energy vehicle power batteries. With the rapid development of the new energy vehicle industry, consumers have higher requirements for driving range, that is, batteries need to have higher energy density.

[0003] Electrolyte is an important component of the battery, affecting its electrochemical properties such as cycle performance and storage performance. However, due to factors such as the electrolyte's easy side reactions with electrode materials, batteries generally have defects such as poor cycle performance and storage performance. Summary of the Invention

[0004] The present application provides an electrolyte additive and a preparation method thereof, an electrolyte, a battery, and an electrical device. The electrolyte additive can improve the cycle performance and storage performance of the battery, effectively overcoming the defects of the prior art.

[0005] In a first aspect, the present application provides an electrolyte additive, comprising a compound represented by Formula 1:

[0006] Formula 1,

[0007] wherein n1 and n2 are each independently selected from any integer of 1 to 5, R0 and R1 are each independently selected from an alkenyl group or an alkynyl group, and R2, R3, R4, and R5 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkane group having 1 to 5 carbon atoms, a substituted or unsubstituted unsaturated hydrocarbon group having 2 to 5 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, or a substituted or unsubstituted alkaryl group having 7 to 10 carbon atoms.

[0008] In one possible embodiment, the compound represented by Formula 1 includes the compound represented by Formula 1-1 and / or the compound represented by Formula 1-2.

[0009] In a possible embodiment, the compound represented by Formula 1-1 includes one or more of the compound represented by Formula 1-1-1, the compound represented by Formula 1-1-2, the compound represented by Formula 1-1-3, and the compound represented by Formula 1-1-4.

[0010] In a possible embodiment, the compound represented by Formula 1-2 includes one or more of the compound represented by Formula 1-2-1, the compound represented by Formula 1-2-2, and the compound represented by Formula 1-2-3.

[0011] In a second aspect, the present application also provides a method for preparing the above-mentioned additive, comprising the following steps: reacting the compound represented by Formula 2 with the compound represented by Formula 3 to obtain the electrolyte additive.

[0012] In one possible embodiment, the compound represented by Formula 3 includes the compound represented by Formula 3-1 and / or the compound represented by Formula 3-2.

[0013] In one possible embodiment, the compound represented by Formula 3-1 includes one or more of the compound represented by Formula 3-1-1, the compound represented by Formula 3-1-2, the compound represented by Formula 3-1-3, and the compound represented by Formula 3-1-4; and / or, the compound represented by Formula 3-2 includes one or more of the compound represented by Formula 3-2-1, the compound represented by Formula 3-2-2, and the compound represented by Formula 3-2-3.

[0014] In one possible embodiment, the preparation process of the compound represented by Formula 2 includes: reacting a raw material system including phosphoric acid and the compound represented by Formula 4 under the action of a first catalyst to generate a compound represented by Formula 5, and then reacting the compound represented by Formula 5 with a basic compound to obtain the compound represented by Formula 2.

[0015] In a third aspect, the present application also provides an electrolyte, comprising the above-mentioned electrolyte additive or the electrolyte additive prepared according to the preparation method of the above-mentioned electrolyte additive.

[0016] In a possible implementation, the electrolyte additive accounts for 0.1% to 10% by mass of the electrolyte.

[0017] In a fourth aspect, the present application also provides a battery comprising the above-mentioned electrolyte.

[0018] In a possible embodiment, the battery further includes a positive electrode sheet, the positive electrode sheet includes a positive electrode active material, the positive electrode active material includes one or more of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and a positive electrode ternary material, and the positive electrode ternary material includes a nickel-cobalt-manganese ternary material and / or a nickel-cobalt-aluminum ternary material.

[0019] In a fifth aspect, the present application also provides an electrical device comprising the above-mentioned battery.

[0020] The electrolyte additive of the present application includes the compound shown in 1, which can improve the stability of the interface between the electrode sheet and the electrolyte, inhibit the occurrence of side reactions between the electrode material and the electrolyte, thereby reducing battery gas production, inhibiting battery swelling, and inhibiting the dissolution of transition metal ions in the positive electrode active material, avoiding the dissolution and migration of transition metal ions to the negative electrode sheet, which may cause the destruction of the solid electrolyte interface protective film (SEI film) on the surface of the negative electrode sheet, and the resulting battery capacity decay and impedance increase. Problems such as these are beneficial to improving the battery's electrochemical properties such as cycle performance and storage performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the preparation process of the compound represented by Formula 1 in one embodiment of the present application;

[0022] Figure 2 This is a schematic diagram of the preparation process of the compound represented by Formula 1-1 in one embodiment of the present application;

[0023] Figure 3 This is a schematic diagram of the preparation process of the compound represented by Formula 1-2 in one embodiment of the present application;

[0024] Figure 4 This is a schematic diagram of the preparation process of the compound represented by Formula 1-1-1 in one embodiment of the present application;

[0025] Figure 5 This is a schematic diagram of the preparation process of the compound represented by Formula 1-2-3 in one embodiment of the present application. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions, and advantages of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0027] In related technologies, due to factors such as the electrolyte's easy side reactions with electrode materials, batteries generally have defects such as rapid impedance growth, poor cycle performance and storage performance.

[0028] Specifically, due to the high oxidizing property of the positive electrode active material, the electrolyte is prone to side reactions at the interface between the positive electrode sheet and the electrolyte, causing the battery to swell, reducing the battery's cycle performance and storage performance. In addition, the transition metal ions in the positive electrode active material will dissolve and migrate to the surface of the negative electrode sheet, destroying the solid electrolyte interface protective film on the surface of the negative electrode sheet, thereby causing the battery capacity to decay and the impedance to increase.

[0029] Especially in harsh environments such as high temperature or high voltage, the side reactions between electrode materials and electrolytes are usually more serious, causing the battery to swell and the cycle performance to deteriorate.

[0030] The present invention provides an electrolyte additive, including a compound represented by Formula 1:

[0031] Formula 1,

[0032] wherein n1 and n2 are each independently selected from any integer of 1 to 5, R0 and R1 are each independently selected from an alkenyl group or an alkynyl group, and R2, R3, R4, and R5 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkane group having 1 to 5 carbon atoms, a substituted or unsubstituted unsaturated hydrocarbon group having 2 to 5 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, or a substituted or unsubstituted alkaryl group having 7 to 10 carbon atoms.

[0033] The electrolyte additive of the present application can form a dense and stable interface protection film on the surface of the electrode sheet, improve the stability of the electrode sheet and the electrolytic interface, reduce the contact between the electrolyte and the electrode material, and thereby reduce the side reactions between the electrolyte and the electrode material, and the resulting battery gas production and other problems, inhibit battery expansion, and improve the battery's cycle performance and storage performance. At the same time, the interface protection film (CEI film) formed on the surface of the positive electrode sheet can also inhibit the dissolution of transition metal ions in the positive electrode active material, avoid the dissolution and migration of transition metals to the negative electrode sheet, resulting in the destruction of the SEI film on the surface of the negative electrode sheet, and the resulting battery capacity decay and impedance increase.

[0034] Specifically, in the above-mentioned system, the electrolyte additive is a dioxaphospholane derivative with a bicyclic structure. Compared to the solvent molecules in the electrolyte, it has a higher highest occupied molecular orbital (HOMO) energy level and a lower oxidation potential. It can preferentially oxidize and decompose on the surface of the positive electrode to form an interfacial protective film (CEI film). The protective film (i.e., CEI film) formed is complete, dense, and uniform, which helps to improve the stability of the interface between the positive electrode and the electrolyte. In addition, the CEI film can effectively reduce the contact between the electrolyte and the positive electrode active material, inhibit the dissolution of transition metal ions in the positive electrode active material, and prevent the dissolution and migration of transition metal ions to the negative electrode, which would cause damage to the solid electrolyte interface protective film (SEI film) on the negative electrode surface. This reduces battery gas production and improves battery cycle performance and storage performance. In addition, the electron-withdrawing effect of the double-ring structure of the electrolyte additive improves the electron-accepting ability of the central atom (P atom), and the electrolyte additive contains unsaturated bonds, which makes it easier to reduce on the surface of the negative electrode to form a solid electrolyte interface protection film (SEI film). The passivation film (ie, SEI film) formed by it is more stable than that formed by a single-ring structure (ie, a single-ring dioxaphosphorus heterocycle), which is beneficial to inhibiting the decomposition of the electrolyte, thereby improving the cycle life and storage performance of the battery, especially improving the high-temperature cycle life and high-temperature storage performance of the battery.

[0035] Specifically, n1 can be selected from 1, 2, 3, 4 or 5, n2 can be selected from 1, 2, 3, 4 or 5, n1 and n2 can be the same or different, R0 and R1 can be the same or different, the halogen atom can be a fluorine atom (F), a chlorine atom (Cl) or a bromine atom (Br), the carbon number of the substituted or unsubstituted alkane group having 1 to 5 carbon atoms can be 1, 2, 3, 4 or 5, which can be a straight-chain alkane group or a branched alkane group, the carbon number of the substituted or unsubstituted unsaturated hydrocarbon group having 2 to 5 carbon atoms can be 2, 3, 4 or 5, the carbon number of the substituted or unsubstituted aryl group having 6 to 10 carbon atoms can be 6, 7, 8, 9 or 10, and the carbon number of the substituted or unsubstituted alkaryl group having 7 to 10 carbon atoms can be 7, 8, 9 or 10.

[0036] In some embodiments, the compound represented by Formula 1 includes the compound represented by Formula 1-1 and / or the compound represented by Formula 1-2, which is more conducive to the electrolyte additive to form a dense and stable interface protection film on the surface of the electrode sheet, further improving the stability of the electrode sheet and the electrolytic interface, reducing the contact between the electrolyte and the electrode material, and thereby reducing the side reactions between the electrolyte and the electrode material, and the resulting battery gas production and other problems, inhibiting battery expansion, and improving the battery's cycle performance and storage performance. At the same time, it is more conducive to the formation of an interface protection film (CEI film) on the surface of the positive electrode sheet, and can also inhibit the dissolution of transition metal ions in the positive electrode active material, avoiding the dissolution and migration of transition metals to the negative electrode sheet, resulting in the destruction of the SEI film on the surface of the negative electrode sheet, and the resulting battery capacity decay and impedance increase.

[0037] Formula 1-1,

[0038] Formula 1-2.

[0039] Specifically, R2 and R5 may be the same or different, and R3 and R4 may be the same or different. For example, when R2 and R5 are the same, and R3 and R4 are the same, the structure of the compound represented by Formula 1-1 is shown in Formula 1-1-5, and the structure of the compound represented by Formula 1-2 is shown in Formula 1-2-4:

[0040] Formula 1-1-5,

[0041] Formula 1-2-4.

[0042] In some embodiments, the compound represented by Formula 1 includes the compound represented by Formula 1-1 and the compound represented by Formula 1-2, which is beneficial for further improving the electrochemical properties of the battery, such as room temperature cycle performance, high temperature cycle performance, and storage performance.

[0043] In some embodiments, the compound represented by Formula 1-1 includes the compound represented by Formula 1-1-1 (dihydro-2-propargyloxy-1,3,2-dioxaphosphole [2-propargyloxy-1,3,2-dioxaphosphole] 2,5-dioxide), the compound represented by Formula 1-1-2 (dihydro-2-ynbutyloxy-1,3,2-dioxaphosphole [2-ynbutyloxy-1,3,2-dioxaphosphole] 2,5-dioxide), the compound represented by Formula 1-1-3 One or more of (dihydro-2-(1-ethynylethyl)oxy-1,3,2-dioxaphosphole [2-(1-ethynylethyl)oxy-1,3,2-dioxaphosphole] 2,5-dioxide), the compound represented by formula 1-1-4 (dihydro-2-(1-ethynyl-1-methylethyl)oxy-1,3,2-dioxaphosphole [2-(1-ethynyl-1-methylethyl)oxy-1,3,2-dioxaphosphole] 2,5-dioxide):

[0044] Formula 1-1-1,

[0045] Formula 1-1-2,

[0046] Formula 1-1-3,

[0047] Formula 1-1-4.

[0048] Under the above system, when the compound shown in Formula 1-1 includes the above compound, the electrolyte additive has a higher degree of unsaturation, which is more conducive to the formation of a CEI film on the positive electrode sheet, protecting the stability of the interface between the positive electrode sheet and the electrolyte, while being more conducive to the formation of a SEI film on the negative electrode sheet, further inhibiting the decomposition of the electrolyte, reducing the battery impedance, and improving the battery's electrochemical properties such as high-temperature storage performance.

[0049] In some embodiments, the compound represented by Formula 1-2 includes one or more of the compound represented by Formula 1-2-1 (dihydro-2-allyloxy-1,3,2-dioxaphosphole [2-allyloxy-1,3,2-dioxaphosphole] 2,5-dioxide), the compound represented by Formula 1-2-2 (dihydro-2-allylbutyloxy-1,3,2-dioxaphosphole [2-allylbutyloxy-1,3,2-dioxaphosphole] 2,5-dioxide), and the compound represented by Formula 1-2-3 (dihydro-2-(1-vinyl-1-methylethyl)oxy-1,3,2-dioxaphosphole [2-(1-vinyl-1-methylethyl)oxy-1,3,2-dioxaphosphole] 2,5-dioxide):

[0050] Formula 1-2-1,

[0051] Formula 1-2-2,

[0052] Formula 1-2-3.

[0053] In the above system, when the compound represented by Formula 1-2 includes the above compound, it is beneficial to further improve the highest occupied molecular orbital (HOMO) energy level of the electrolyte additive, further reduce its oxidation potential, and is more conducive to the formation of a CEI film on the surface of the positive electrode sheet, and is conducive to the formation of a SEI film on the surface of the negative electrode sheet, inhibiting the decomposition of the electrolyte and the dissolution of transition metals, thereby inhibiting battery swelling and improving the battery's electrochemical properties such as room temperature storage performance.

[0054] The present invention also provides a method for preparing the above-mentioned additive, comprising the following steps: reacting the compound represented by Formula 2 with the compound represented by Formula 3 to obtain the electrolyte additive:

[0055] Formula 2,

[0056] Wherein, M is a cationic group, the cationic group may include a metal cationic group, the metal cationic group may include an alkali metal cationic group, and the alkali metal cationic group includes a sodium ion,

[0057] Formula 3,

[0058] wherein a is independently selected from any integer of 1 to 5, R6 is selected from an alkenyl group or an alkynyl group, R7 and R8 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkane group having 1 to 5 carbon atoms, a substituted or unsubstituted unsaturated hydrocarbon group having 2 to 5 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, or a substituted or unsubstituted alkaryl group having 7 to 10 carbon atoms, and X is selected from a halogen atom.

[0059] Specifically, a may be 1, 2, 3, 4 or 5, the carbon number of the substituted or unsubstituted alkyl group having 1 to 5 carbon atoms may be 1, 2, 3, 4 or 5, the carbon number of the substituted or unsubstituted unsaturated hydrocarbon group having 2 to 5 carbon atoms may be 2, 3, 4 or 5, the carbon number of the substituted or unsubstituted aryl group having 6 to 10 carbon atoms may be 6, 7, 8, 9 or 10, the carbon number of the substituted or unsubstituted alkaryl group having 7 to 10 carbon atoms may be 7, 8, 9 or 10, and the halogen atom may be a fluorine atom (F), a chlorine atom (Cl) or a bromine atom (Br).

[0060] In the above preparation process, the compound represented by Formula 2 and the compound represented by Formula 3 can react under the action of a second catalyst to obtain an electrolyte additive. The second catalyst includes tetrabutylammonium bromide.

[0061] In some embodiments, the process of reacting the compound represented by Formula 2 with the compound represented by Formula 3 includes: mixing the compound represented by Formula 2 with the compound represented by Formula 3, and reacting at 80° C. to 100° C. for 6 to 12 hours to obtain an electrolyte additive.

[0062] In some embodiments, the compound of Formula 3 includes the compound of Formula 3-1 and / or the compound of Formula 3-2:

[0063] Formula 3-1, Formula 3-2.

[0064] In some embodiments, the compound represented by Formula 3-1 includes one or more of the compound represented by Formula 3-1-1 (3-chloropropyne), the compound represented by Formula 3-1-2, the compound represented by Formula 3-1-3, and the compound represented by Formula 3-1-4:

[0065] Formula 3-1-1, Formula 3-1-2,

[0066] Formula 3-1-3, Formula 3-1-4.

[0067] In some embodiments, the compound represented by Formula 3-2 includes one or more of the compound represented by Formula 3-2-1, the compound represented by Formula 3-2-2, and the compound represented by Formula 3-2-3 (3-chloro-3-methyl-1-butene):

[0068] Formula 3-2-1, Formula 3-2-2,

[0069] Formula 3-2-3.

[0070] In some embodiments, the preparation process of the compound represented by Formula 2 includes: reacting a raw material system including phosphoric acid (structure shown in Formula 6) and a compound represented by Formula 4 under the action of a first catalyst to produce a compound represented by Formula 5, and then reacting the compound represented by Formula 5 with a basic compound to obtain the compound represented by Formula 2:

[0071] Formula 4, Formula 5,

[0072] Formula 6,

[0073] Wherein, Y1, Y2, Y3, and Y4 are each independently selected from a halogen atom, which may be a fluorine atom (F), a chlorine atom (Cl), or a bromine atom (Br), and the alkaline compound may include an inorganic base, which may include an alkali metal hydroxide, and which may include sodium hydroxide.

[0074] In some embodiments, the preparation process of the compound represented by Formula 2 includes: reacting a raw material system including phosphoric acid and a compound represented by Formula 4 at 100°C to 150°C for 2 to 3 hours under the action of a first catalyst to generate a compound represented by Formula 5, and then reacting the compound represented by Formula 5 with an alkaline compound at 60°C to 100°C for 6 to 12 hours to obtain the compound represented by Formula 2.

[0075] In some embodiments, the first catalyst includes a Lewis acid catalyst, which may include one or more of aluminum trichloride (AlCl 3 ), ferric trichloride (FeCl 3 ), and zirconium tetrachloride (ZrCl 4 ).

[0076] In a specific implementation, the compound of Formula 1 can be prepared by the following process: heating the compound of Formula 4 with phosphoric acid and generating the compound of Formula 5 under the action of a first catalyst, then reacting the compound of Formula 5 with a basic compound to generate the compound of Formula 2, and then reacting the compound of Formula 2 with the compound of Formula 3 under the action of tetrabutylammonium bromide to obtain the compound of Formula 1, as shown in FIG. Figure 1 shown.

[0077] For example, the compound represented by Formula 4 may be the compound represented by Formula 4-1, the alkaline compound may be sodium hydroxide, the compound represented by Formula 2 may be the compound represented by Formula 2-1, and the compound represented by Formula 3 may be the compound represented by Formula 3-1. In this case, the preparation process of the compound represented by Formula 1-1 is as follows: Figure 2 As shown:

[0078] Formula 4-1, Formula 2-1.

[0079] For example, the compound represented by Formula 4 may be the compound represented by Formula 4-1, the alkaline compound may be sodium hydroxide, the compound represented by Formula 2 may be the compound represented by Formula 2-1, and the compound represented by Formula 3 may be the compound represented by Formula 3-2. In this case, the preparation process of the compound represented by Formula 1-2 is as follows: Figure 3 shown.

[0080] An embodiment of the present application also provides an electrolyte, including the above-mentioned electrolyte additive or the electrolyte additive prepared according to the preparation method of the above-mentioned electrolyte additive, which has properties corresponding to the above-mentioned electrolyte additive and is not further described here.

[0081] In some embodiments, the mass percentage of the electrolyte additive in the electrolyte is 0.1% to 10%, for example, 0.1%, 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or a range consisting of any two of them. When the mass percentage of the electrolyte additive in the electrolyte is not less than 0.1%, it is beneficial to improve the stability of the interface between the positive electrode sheet and the electrolyte, inhibit the occurrence of electrolyte side reactions, thereby inhibiting battery swelling, and can inhibit the dissolution of transition metal ions, which is beneficial to reducing the impedance of the battery and improving the battery's cycle life, storage performance and other electrochemical properties. At the same time, when the mass percentage of the electrolyte additive in the electrolyte is not more than 10%, it is beneficial for the electrolyte to maintain a suitable viscosity, further improving the battery's electrochemical properties such as cycle life and storage performance, preferably 1% to 3%.

[0082] In some embodiments, the electrolyte further includes an electrolyte salt.

[0083] In some embodiments, the electrolyte salt may include a lithium salt, including one or more of lithium hexafluorophosphate (LiPF6), lithium perchlorate, lithium tetrafluoroborate, lithium bisfluorooxalatoborate, lithium bisfluorobisoxalatophosphate, lithium tetrafluorooxalatophosphate, lithium bis(trifluoromethylsulfonyl)imide, and lithium bisfluorosulfonylimide (LiFSI).

[0084] Specifically, the electrolyte may be an electrolyte for lithium-ion batteries.

[0085] In some embodiments, the lithium salt includes one or more of lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, which is beneficial for improving the conductivity of the electrolyte and improving the electrochemical properties of the battery, such as the cycle performance and storage performance.

[0086] In some embodiments, the lithium salt includes lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate. The combination of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide can not only improve the conductivity and thermal decomposition temperature of the electrolyte, but also reduce the decomposition of lithium hexafluorophosphate, thereby further improving the cycle life and other performance of the battery.

[0087] In some embodiments, the concentration of the electrolyte salt in the electrolyte is 0.5 mol / L~2 mol / L, for example, 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.3 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L or a range consisting of any two thereof, preferably 0.8 mol / L~1.3 mol / L, which is beneficial to promote the migration of lithium ions in the battery and improve the electrochemical properties of the battery, such as the cycle life.

[0088] In some embodiments, the concentration of lithium bis(fluorosulfonyl)imide in the electrolyte is 0.1 mol / L to 0.5 mol / L, for example, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, or a range consisting of any two thereof, which is beneficial to further improve the conductivity and thermal decomposition temperature of the electrolyte, and inhibit the decomposition of lithium hexafluorophosphate, thereby further improving the cycle life of the battery.

[0089] In the embodiment of the present application, the electrolyte may be a non-aqueous electrolyte. Specifically, the electrolyte further includes a solvent, and the solvent may include an organic solvent.

[0090] In some embodiments, the organic solvent may include an ester solvent, the ester solvent may include a carbonate solvent and / or a carboxylate solvent, the carbonate solvent may include one or more of ethylene carbonate (EC), propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and methylpropyl carbonate, and the carboxylate solvent may include one or more of γ-butyrolactone, methyl formate, ethyl acetate, methyl acetate, propyl acetate (EP), butyl acetate, ethyl propionate, propyl propionate, and butyl propionate.

[0091] An embodiment of the present application further provides a battery, including the above-mentioned electrolyte, and having properties corresponding to the above-mentioned electrolyte, which will not be described in detail here.

[0092] The battery in the embodiment of the present application may be a lithium-ion battery.

[0093] In some embodiments, the battery further includes a positive electrode sheet, which includes a positive electrode active material, which includes one or more of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and a positive electrode ternary material, and the positive electrode ternary material includes a nickel-cobalt-manganese ternary material (NCM) and / or a nickel-cobalt-aluminum ternary material.

[0094] Specifically, the nickel-cobalt-manganese ternary material may include LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523).

[0095] According to the inventors' research, using high-voltage cathode active materials such as NCM523 can effectively increase the battery's energy density. However, high-voltage cathode materials have a high operating voltage. Under high voltage, they are highly oxidizing, exacerbating electrolyte side reactions at the interface between the cathode and the electrolyte, leading to battery swelling and a decrease in cycle life and storage performance. This is particularly serious under high-temperature conditions. Furthermore, transition metal ions in the high-voltage cathode active materials dissolve and migrate to the surface of the anode, destroying the solid electrolyte interface (SEI) film on the anode surface, leading to battery capacity decay and increased impedance.

[0096] The electrolyte additive of the present application can still form a dense and stable interface protection film on the surface of the electrode sheet under high voltage conditions, thereby improving the stability of the electrode sheet and the electrolytic interface, reducing the contact between the electrolyte and the electrode material, and thereby reducing the side reactions between the electrolyte and the electrode material, and the resulting battery gas production and other problems, inhibiting battery expansion, and improving the battery's cycle performance and storage performance under high voltage. At the same time, the interface protection film (CEI film) formed on the surface of the positive electrode sheet can inhibit the dissolution of transition metal ions in the positive electrode active material under high voltage conditions, avoid the dissolution and migration of transition metals to the negative electrode sheet, resulting in the destruction of the SEI film on the surface of the negative electrode sheet, and the resulting battery capacity decay and impedance increase.

[0097] Specifically, the positive electrode sheet includes a positive electrode collector and a positive electrode coating (positive electrode active material layer) located on at least one side surface of the positive electrode collector. Specifically, the positive electrode coating can be provided on one side surface of the positive electrode collector, or the positive electrode coating can be provided on both sides of the positive electrode collector in the thickness direction.

[0098] Specifically, the positive electrode coating layer may include a positive electrode active material (positive electrode active material), a positive electrode conductor, and a positive electrode binder.

[0099] Among them, the positive electrode conductor and the positive electrode binder can both be conventional materials in the field. For example, the positive electrode conductor may include one or more of conductive carbon black, carbon nanotubes (CNTs), acetylene black, graphene, Ketjen black, and carbon fiber; the positive electrode binder may include one or more of polyvinylidene fluoride (PVDF), polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, polyvinyl chloride, carboxylated polyvinyl chloride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, etc.

[0100] The embodiment of the present invention may adopt a conventional positive electrode current collector in the art, for example, the positive electrode current collector includes aluminum foil.

[0101] In the embodiments of the present invention, the positive electrode sheet can be prepared by conventional methods in the art, such as by a coating method. Specifically, the components used to form the positive electrode coating, such as the positive electrode active material, positive electrode conductive agent, and positive electrode binder, can be dispersed in a positive electrode solvent, such as N-methylpyrrolidone (NMP), to prepare a positive electrode slurry, which is then coated on the surface of the positive electrode current collector. After drying and roller pressing, the positive electrode sheet is prepared. The coating, drying, and roller pressing steps involved are conventional operations for preparing positive electrode sheets using the coating method and are not particularly limited thereto.

[0102] Generally speaking, a battery consists of a cell, an electrolyte, and a casing that encapsulates the cell. The electrolyte is injected into the cell within the casing. The cell includes a positive electrode sheet, a negative electrode sheet, and a separator located between the positive and negative electrodes. The cell can be a wound cell and / or a stacked cell.

[0103] The embodiments of the present invention can prepare batteries by conventional methods in the field. For example, the positive electrode sheets, separators, and negative electrode sheets can be stacked in an alternating manner to produce a laminated battery cell; or the positive electrode sheets, separators, and negative electrode sheets can be wound in sequence to produce a wound battery cell. The battery cell is then placed in a casing and subjected to conventional processes such as liquid injection (i.e., injection of electrolyte), packaging, standing, formation, and capacity separation to produce a battery.

[0104] Specifically, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer (negative electrode coating) located on at least one side surface of the negative electrode current collector. Specifically, the negative electrode coating can be provided on one side surface of the negative electrode current collector, or on both sides of the negative electrode current collector in the thickness direction. The negative electrode coating is respectively provided on the surface.

[0105] Specifically, the negative electrode coating may include a negative electrode active material (negative electrode active material), a negative electrode conductor, a thickener and a negative electrode binder, all of which may be conventional materials in the art. For example, the negative electrode active material may include graphite, and the graphite includes artificial graphite; the negative electrode conductor may include one or more of conductive carbon black, carbon nanotubes (CNTs), acetylene black, graphene, Ketjen black, and carbon fibers; the negative electrode binder may include one or more of styrene-butadiene rubber (SBR), polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate; and the thickener may include carboxymethyl cellulose (CMC).

[0106] The embodiment of the present invention may adopt a conventional negative electrode current collector in the art, for example, the negative electrode current collector includes copper foil.

[0107] In the embodiments of the present invention, the negative electrode sheet can be prepared by conventional methods in the art, such as a coating method. Specifically, the components used to form the negative electrode coating, such as the negative electrode active material, negative electrode conductive agent, thickener, and negative electrode binder, can be dispersed in a negative electrode solvent, such as water, to prepare a negative electrode slurry. The slurry is then applied to the surface of the negative electrode current collector. After drying and roller pressing, the negative electrode sheet is prepared. The coating, drying, and roller pressing steps involved are conventional operations for preparing negative electrode sheets using a coating method and are not particularly limited thereto.

[0108] In an embodiment of the present invention, a diaphragm is used to separate the positive electrode sheet and the negative electrode sheet to prevent the positive electrode sheet and the negative electrode sheet from short-circuiting. In an embodiment of the present invention, a conventional diaphragm in the art may be used. For example, the diaphragm includes one or more of a polypropylene film (PP film) and a polyethylene film (PE film), but is not limited thereto.

[0109] In the embodiment of the present invention, the battery cell may be encapsulated with conventional shell materials in the art. The shell may include, for example, soft packaging materials such as aluminum-plastic film (the battery in this case is a soft-package battery), but is not limited thereto.

[0110] Generally, the battery can be a single cell, or in the form of a battery module, battery pack, or other similar battery configuration. A battery module or battery pack includes multiple single cells, which are connected to form a battery module or battery pack. These single cells can be electrically connected using conventional methods in the art, such as series connection, parallel connection, or a combination of these connection methods, and this application does not impose any particular limitations thereon.

[0111] An embodiment of the present application also provides an electrical device, including the above-mentioned battery, and having properties corresponding to the above-mentioned battery.

[0112] The electrical equipment in the embodiments of the present application can be conventional electrical equipment in the field, such as power equipment (such as electric vehicles, electric cars), electronic equipment (such as mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (such as watches, bracelets, VR glasses, etc.), energy storage power stations, etc.

[0113] The present invention is further described below through specific examples.

[0114] Example 1

[0115] 1. Preparation of electrolyte additives

[0116] The compound of formula 4-1 is mixed with phosphoric acid, and aluminum chloride is added to obtain a mixed system. The mixed system is heated to 120°C and reacted for 3 hours to generate the compound of formula 5. Then, sodium hydroxide is added thereto and reacted at 80°C for 10 hours to generate the compound of formula 2-1. Tetrabutylammonium bromide and the compound of formula 3-1-1 are added and reacted at 90°C for 8 hours to obtain the compound of formula 1-1-1. The reaction process is as follows: Figure 4 shown.

[0117] 2. Preparation of electrolyte

[0118] Fill the glove box with 99.999% pure argon, control the moisture content in the glove box to ≤ 0.1 ppm, and control the temperature to room temperature. Prepare the electrolyte in the glove box:

[0119] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of 3:2:5 to obtain a mixed solvent, and then lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) are added thereto and dissolved in the above-mentioned mixed solvent. Then, the compound represented by formula 1-1-1 is added thereto, and after uniform mixing, an electrolyte is obtained; wherein, the mass percentage of the compound represented by formula 1-1-1 in the electrolyte is 0.5%, the concentration of lithium hexafluorophosphate is 0.9 mol / L, and the concentration of lithium bis(fluorosulfonyl)imide is 0.3 mol / L.

[0120] 2. Preparation of positive electrode

[0121] LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523), conductive carbon black, and polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 96.8:2.0:1.2, and NMP is added and stirred evenly to prepare a positive electrode slurry;

[0122] The positive electrode slurry is coated on the front and back surfaces of the aluminum foil. After drying and roller pressing, a positive electrode coating is formed on the front and back surfaces of the aluminum foil to produce a positive electrode sheet.

[0123] 3. Preparation of negative electrode sheet

[0124] Graphite, conductive carbon black, carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) were mixed in a mass ratio of 96.0:1.0:1.5:1.5, deionized water was added, and the mixture was stirred evenly to prepare a negative electrode slurry;

[0125] The negative electrode slurry is coated on the front and back surfaces of the copper foil. After drying and roller pressing, a negative electrode coating is formed on the front and back surfaces of the copper foil to produce a negative electrode sheet.

[0126] 4. Battery assembly

[0127] The positive electrode sheets, separators (PE films) and negative electrode sheets are alternately stacked to assemble into a laminated battery cell. The laminated battery cell is placed in an aluminum-plastic film packaging shell, injected with the above-mentioned electrolyte, and subjected to processes such as static standing, hot and cold pressing, formation, and capacity separation to produce a battery.

[0128] Example 2

[0129] The difference from Example 1 is that the mass percentage of the compound represented by Formula 1-1-1 in the electrolyte is 1%, and the other steps and conditions are consistent with Example 1.

[0130] Example 3

[0131] The difference from Example 1 is that the mass percentage of the compound represented by Formula 1-1-1 in the electrolyte is 1.5%, and the other steps and conditions are consistent with Example 1.

[0132] Example 4

[0133] The difference from Example 1 is that the mass percentage of the compound represented by Formula 1-1-1 in the electrolyte is 2%, and the other steps and conditions are consistent with Example 1.

[0134] Example 5

[0135] The difference from Example 1 is that the mass percentage of the compound represented by Formula 1-1-1 in the electrolyte is 2.5%, and the other steps and conditions are consistent with Example 1.

[0136] Example 6

[0137] The difference from Example 1 is that the mass percentage of the compound represented by Formula 1-1-1 in the electrolyte is 3%, and the other steps and conditions are consistent with Example 1.

[0138] Example 7

[0139] The difference from Example 1 is that:

[0140] 1. Preparation of electrolyte additives

[0141] The compound of formula 1-1-2 is prepared by the preparation method of the compound of formula 1-1-1 in reference example 1. The difference from example 1 is that the compound of formula 3-1-2 is used instead of the compound of formula 3-1-1.

[0142] 2. Preparation of electrolyte

[0143] Fill the glove box with 99.999% pure argon, control the moisture content in the glove box to ≤ 0.1 ppm, and control the temperature to room temperature. Prepare the electrolyte in the glove box:

[0144] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of 3:2:5 to obtain a mixed solvent, and then lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) are added thereto and dissolved in the above-mentioned mixed solvent. Then, the compound represented by formula 1-1-2 is added thereto, and after uniform mixing, an electrolyte is obtained; wherein, the mass percentage of the compound represented by formula 1-1-2 in the electrolyte is 2%, the concentration of lithium hexafluorophosphate is 0.9 mol / L, and the concentration of lithium bis(fluorosulfonyl)imide is 0.3 mol / L.

[0145] The remaining steps and conditions remained the same as in Example 1.

[0146] Example 8

[0147] The difference from Example 1 is that:

[0148] 1. Preparation of electrolyte additives

[0149] The compound of formula 1-1-3 is prepared by the preparation method of the compound of formula 1-1-1 in reference example 1. The difference from example 1 is that the compound of formula 3-1-3 is used instead of the compound of formula 3-1-1.

[0150] 2. Preparation of electrolyte

[0151] Fill the glove box with 99.999% pure argon, control the moisture in the glove box to ≤0.1ppm, and control the temperature to room temperature. Prepare the electrolyte in the glove box:

[0152] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of 3:2:5 to obtain a mixed solvent, and then lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) are added thereto and dissolved in the above-mentioned mixed solvent. Then, the compound represented by formula 1-3 is added thereto, and after uniform mixing, an electrolyte is obtained; wherein, the mass percentage of the compound represented by formula 1-1-3 in the electrolyte is 2%, the concentration of lithium hexafluorophosphate is 0.9 mol / L, and the concentration of lithium bis(fluorosulfonyl)imide is 0.3 mol / L.

[0153] The remaining steps and conditions remained the same as in Example 1.

[0154] Example 9

[0155] The difference from Example 1 is that:

[0156] 1. Preparation of electrolyte additives

[0157] The compound of formula 1-1-4 is prepared by the preparation method of the compound of formula 1-1-1 in reference example 1. The difference from example 1 is that the compound of formula 3-1-4 is used instead of the compound of formula 3-1-1.

[0158] 2. Preparation of electrolyte

[0159] Fill the glove box with 99.999% pure argon, control the moisture content in the glove box to ≤ 0.1 ppm, and control the temperature to room temperature. Prepare the electrolyte in the glove box:

[0160] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of 3:2:5 to obtain a mixed solvent, and then lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) are added thereto and dissolved in the above-mentioned mixed solvent. Then, the compound represented by formula 1-1-4 is added thereto, and after uniform mixing, an electrolyte is obtained; wherein, the mass percentage of the compound represented by formula 1-1-4 in the electrolyte is 2%, the concentration of lithium hexafluorophosphate is 0.9 mol / L, and the concentration of lithium bis(fluorosulfonyl)imide is 0.3 mol / L.

[0161] The remaining steps and conditions remained the same as in Example 1.

[0162] Example 10

[0163] The difference from Example 1 is that:

[0164] 1. Preparation of electrolyte additives

[0165] The compound of formula 1-2-1 is prepared by the preparation method of the compound of formula 1-1-1 in reference example 1. The difference from example 1 is that the compound of formula 3-2-1 is used instead of the compound of formula 3-1-1.

[0166] 2. Preparation of electrolyte

[0167] Fill the glove box with 99.999% pure argon, control the moisture content in the glove box to ≤ 0.1 ppm, and control the temperature to room temperature. Prepare the electrolyte in the glove box:

[0168] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of 3:2:5 to obtain a mixed solvent, and then lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) are added thereto and dissolved in the above-mentioned mixed solvent. Then, the compound represented by formula 1-2-1 is added thereto, and after uniform mixing, an electrolyte is obtained; wherein, the mass percentage of the compound represented by formula 1-2-1 in the electrolyte is 2%, the concentration of lithium hexafluorophosphate is 0.9 mol / L, and the concentration of lithium bis(fluorosulfonyl)imide is 0.3 mol / L.

[0169] The remaining steps and conditions remained the same as in Example 1.

[0170] Example 11

[0171] The difference from Example 1 is that:

[0172] 1. Preparation of electrolyte additives

[0173] The compound of formula 1-2-2 is prepared by the preparation method of the compound of formula 1-1-1 in reference example 1. The difference from example 1 is that the compound of formula 3-2-2 is used instead of the compound of formula 3-1-1.

[0174] 2. Preparation of electrolyte

[0175] Fill the glove box with 99.999% pure argon, control the moisture content in the glove box to ≤ 0.1 ppm, and control the temperature to room temperature. Prepare the electrolyte in the glove box:

[0176] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of 3:2:5 to obtain a mixed solvent, and then lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) are added thereto and dissolved in the above-mentioned mixed solvent. Then, the compound represented by formula 1-2-2 is added thereto, and after uniform mixing, an electrolyte is obtained; wherein, the mass percentage of the compound represented by formula 1-2-2 in the electrolyte is 2%, the concentration of lithium hexafluorophosphate is 0.9 mol / L, and the concentration of lithium bis(fluorosulfonyl)imide is 0.3 mol / L.

[0177] The remaining steps and conditions remained the same as in Example 1.

[0178] Example 12

[0179] The difference from Example 1 is that:

[0180] 1. Preparation of electrolyte additives

[0181] The compound of formula 1-2-3 was prepared by the preparation method of the compound of formula 1-1-1 in reference example 1. The difference from example 1 is that the compound of formula 3-2-3 is used instead of the compound of formula 3-1-1. The reaction process is as follows: Figure 5 shown.

[0182] 2. Preparation of electrolyte

[0183] Fill the glove box with 99.999% pure argon, control the moisture content in the glove box to ≤ 0.1 ppm, and control the temperature to room temperature. Prepare the electrolyte in the glove box:

[0184] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of 3:2:5 to obtain a mixed solvent, and then lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) are added thereto and dissolved in the above-mentioned mixed solvent. Then, the compound represented by formula 1-2-3 is added thereto, and after uniform mixing, an electrolyte is obtained; wherein, the mass percentage of the compound represented by formula 1-2-3 in the electrolyte is 2%, the concentration of lithium hexafluorophosphate is 0.9 mol / L, and the concentration of lithium bis(fluorosulfonyl)imide is 0.3 mol / L.

[0185] The remaining steps and conditions remained the same as in Example 1.

[0186] Example 13

[0187] The difference from Example 1 is that:

[0188] 2. Preparation of electrolyte

[0189] Fill the glove box with 99.999% pure argon, control the moisture content in the glove box to ≤ 0.1 ppm, and control the temperature to room temperature. Prepare the electrolyte in the glove box:

[0190] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a mass ratio of 3:2:5 to obtain a mixed solvent, and then lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) are added thereto and dissolved in the above-mentioned mixed solvent. Then, the compound represented by formula 1-1-1 and the compound represented by formula 1-2-1 are added thereto, and the mixture is uniformly mixed to obtain an electrolyte; wherein the mass percentage of the compound represented by formula 1-1-1 in the electrolyte is 1%, the mass percentage of the compound represented by formula 1-2-1 in the electrolyte is 1%, the concentration of lithium hexafluorophosphate is 0.9 mol / L, and the concentration of lithium bis(fluorosulfonyl)imide is 0.3 mol / L.

[0191] The remaining steps and conditions remained the same as in Example 1.

[0192] Example 14

[0193] The difference from Example 1 is that the mass percentage of the compound represented by Formula 1-1-1 in the electrolyte is 6.0%, and the other steps and conditions are consistent with Example 1.

[0194] Example 15

[0195] The difference from Example 1 is that the mass percentage of the compound represented by Formula 1-1-1 in the electrolyte is 10.0%, and the remaining steps and conditions are the same as those in Example 1.

[0196] The difference from Example 1 is that:

[0197] The compound represented by Formula 1-1-1 is replaced by tripropargyl phosphate (the compound represented by Formula 7), and the mass percentage of tripropargyl phosphate in the electrolyte is 2%.

[0198] Formula 7, the remaining steps and conditions are consistent with Example 1.

[0199] Comparative Example 2

[0200] The difference from Example 1 is that:

[0201] The compound represented by Formula 1-1-1 is replaced by triallyl phosphate (the compound represented by Formula 8), and the mass percentage of triallyl phosphate in the electrolyte is 2%.

[0202] Formula 8, the remaining steps and conditions are consistent with Example 1.

[0203] Comparative Example 3

[0204] The difference from Example 1 is that:

[0205] The compound represented by Formula 1-1-1 is replaced by 2-propargyloxy-2-oxo-1,3,2-dioxaphospholane (the compound represented by Formula 9), and the mass percentage of 2-propargyloxy-2-oxo-1,3,2-dioxaphospholane in the electrolyte is 2%.

[0206] Formula 9, the remaining steps and conditions are consistent with Example 1.

[0207] The types of electrolyte additives and the contents of the electrolyte additives (ie, the mass percentage of the electrolyte additives in the electrolyte) in the examples and comparative examples are summarized in Table 1.

[0208] The batteries in the embodiment and the comparative example were tested by the following process, and the results are shown in Table 2:

[0209] (1) Normal temperature cycle performance test

[0210] In a constant temperature box at 25°C, the battery was charged to 4.5V at a constant current of 1C, then charged at a constant voltage to a cutoff current of 0.05C, left to stand for 0.5h, and then discharged to 2.8V at a constant current of 1C to obtain the first-week discharge capacity, recorded as C0. The above process was recorded as one charge and discharge cycle, and then 800 cycles were performed according to the above conditions; the discharge capacity of the 800th cycle was recorded as C1, and the room temperature cycle capacity retention rate = (C1 / C0)×100%.

[0211] (2) High temperature cycle performance test

[0212] In a constant temperature box at 45°C, the battery was charged to 4.5V at a constant current of 1C, then charged at a constant voltage to a cutoff current of 0.05C, allowed to stand for 0.5h, and then discharged to 2.8V at a constant current of 1C to obtain the first-week discharge capacity, recorded as C2. The above process was recorded as one charge and discharge cycle, and then 400 cycles were performed under the above conditions. The discharge capacity of the 400th cycle was recorded as C3; high-temperature cycle capacity retention rate = (C3 / C2)×100%.

[0213] (3) High temperature storage performance, battery gas production, and battery resistance growth rate tests

[0214] The battery thickness was measured to obtain the battery thickness H0 before storage. The battery was then charged to 4.5 V at a constant current of 1 C at 25°C, switched to constant voltage charging to a cutoff of 0.05 C, allowed to stand for 0.5 h, and then discharged at a constant current of 1 C to 2.8 V to obtain the discharge capacity, recorded as the initial capacity C4. The battery state of charge (SOC) was adjusted to 50%, and discharged at a current density of 1.5 C for 10 s. The DC internal resistance (DCIR) value of the battery at this time was tested and recorded as D0. The battery was then transferred to a high-temperature test cabinet and stored at 55°C for 14 days. After storage, the battery was taken out and placed at room temperature for 4 hours. The battery thickness at this time was measured, that is, the battery thickness after storage, which was recorded as H1. It was then discharged at a constant current of 1C to 2.8V to obtain a discharge capacity of C5. After placing it for 2 hours, it was charged at a constant current of 1C to a constant voltage to 4.5V, cut off at 0.05 C, and placed for 0.5 hours. It was then discharged at a constant current of 1C to 2.8V to obtain a discharge capacity of C6. The SOC was adjusted to 50%, the battery state of charge (SOC) was adjusted to 50%, and it was discharged at a current density of 1.5C for 10 seconds. The DC internal resistance (DCIR) value of the battery at this time was tested and recorded as D1.

[0215] Among them, the high-temperature storage performance is reflected by the high-temperature storage capacity remaining rate and the high-temperature storage capacity recovery rate: High-temperature storage capacity remaining rate = (C5 / C4) 100%; High temperature storage capacity recovery rate = (C6 / C4) 100%.

[0216] The degree of battery swelling is reflected by the battery thickness growth rate: Battery thickness growth rate = [(H1-H0) / H0] 100%.

[0217] Battery internal resistance change rate (DCIR change rate) = [(D1-D0) / D0] 100%.

[0218] Table 1

[0219]

[0220] Table 2

[0221]

[0222]

[0223] As shown in Table 2, compared with Comparative Examples 1 to 3, the electrolytes in Examples 1 to 15 include the compound represented by Formula 1, which is beneficial for reducing the resistance growth of the battery, inhibiting battery swelling, and improving the electrochemical properties of the battery, such as room temperature cycle life, high temperature cycle life, and high temperature storage performance.

[0224] Compared with Example 4 and Example 10, the electrolyte additive in Example 13 includes the compound represented by Formula 1-1-1 and the compound represented by Formula 1-2-1. While reducing the battery resistance and inhibiting battery swelling, it further improves the battery's electrochemical properties such as room temperature cycle life, high temperature cycle life, and high temperature storage performance.

[0225] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrolyte additive, characterized in that Including the compound shown in formula 1: Formula 1, wherein n1 and n2 are each independently selected from any integer of 1 to 5, R0 and R1 are each independently selected from an alkenyl group or an alkynyl group, and R2, R3, R4, and R5 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkane group having 1 to 5 carbon atoms, a substituted or unsubstituted unsaturated hydrocarbon group having 2 to 5 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, or a substituted or unsubstituted alkaryl group having 7 to 10 carbon atoms.

2. The electrolyte additive according to claim 1, characterized in that The compound represented by Formula 1 includes the compound represented by Formula 1-1 and / or the compound represented by Formula 1-2: Formula 1-1, Formula 1-2.

3. The electrolyte additive according to claim 2, characterized in that The compound represented by Formula 1-1 includes one or more of the compound represented by Formula 1-1-1, the compound represented by Formula 1-1-2, the compound represented by Formula 1-1-3, and the compound represented by Formula 1-1-4: Formula 1-1-1, Formula 1-1-2, Formula 1-1-3, Formula 1-1-4.

4. The electrolyte additive according to claim 2, characterized in that The compound represented by Formula 1-2 includes one or more of the compound represented by Formula 1-2-1, the compound represented by Formula 1-2-2, and the compound represented by Formula 1-2-3: Formula 1-2-1, Formula 1-2-2, Formula 1-2-3.

5. A method for preparing the electrolyte additive according to any one of claims 1 to 4, characterized in that: The following steps are involved: The compound represented by Formula 2 is reacted with the compound represented by Formula 3 to obtain the electrolyte additive: Formula 2, Wherein, M is a cationic group, Formula 3, wherein a is independently selected from any integer of 1 to 5, R6 is selected from an alkenyl group or an alkynyl group, R7 and R8 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkane group having 1 to 5 carbon atoms, a substituted or unsubstituted unsaturated hydrocarbon group having 2 to 5 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, or a substituted or unsubstituted alkaryl group having 7 to 10 carbon atoms, and X is selected from a halogen atom.

6. The method for preparing the electrolyte additive according to claim 5, characterized in that: The compound represented by Formula 3 includes the compound represented by Formula 3-1 and / or the compound represented by Formula 3-2: Formula 3-1, Formula 3-2.

7. The method for preparing the electrolyte additive according to claim 6, characterized in that: The compound represented by formula 3-1 includes one or more of the compound represented by formula 3-1-1, the compound represented by formula 3-1-2, the compound represented by formula 3-1-3, and the compound represented by formula 3-1-4: Formula 3-1-1, Formula 3-1-2, Formula 3-1-3, Formula 3-1-4; And / or, the compound represented by formula 3-2 includes one or more of the compound represented by formula 3-2-1, the compound represented by formula 3-2-2, and the compound represented by formula 3-2-3: Formula 3-2-1, Formula 3-2-2, Formula 3-2-3.

8. The method for preparing the electrolyte additive according to claim 5, characterized in that: The preparation process of the compound represented by Formula 2 includes: reacting a raw material system including phosphoric acid and a compound represented by Formula 4 under the action of a first catalyst to generate a compound represented by Formula 5, and then reacting the compound represented by Formula 5 with a basic compound to obtain the compound represented by Formula 2: Formula 4, Formula 5, wherein Y1, Y2, Y3, and Y4 are each independently selected from a halogen atom.

9. An electrolyte, characterized in that The electrolyte additive comprises the electrolyte additive according to any one of claims 1 to 4 or the electrolyte additive prepared according to the preparation method of the electrolyte additive according to any one of claims 5 to 8.

10. The electrolyte according to claim 9, characterized in that The electrolyte additive accounts for 0.1% to 10% by mass of the electrolyte.

11. A battery, characterized in that: Comprising the electrolyte according to claim 9 or 10.

12. The battery according to claim 11, characterized in that The battery also includes a positive electrode sheet, which includes a positive electrode active material. The positive electrode active material includes one or more of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, and a positive electrode ternary material. The positive electrode ternary material includes a nickel-cobalt-manganese ternary material and / or a nickel-cobalt-aluminum ternary material.

13. An electrical device, characterized in that: A battery comprising the battery according to claim 11 or 12.

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