Disulfonate compound, preparation method thereof, electrolyte and energy storage device

Abstract

The present invention relates to a disulfonate compound, a preparation method thereof, an electrolyte, and an energy storage device. The disulfonate compound has an #imgabs0# structure and is applied as an additive to an energy storage device, so that a stable SEI film can be formed on the negative electrode surface of the energy storage device, which can inhibit the decomposition of the solvent in the electrolyte. Since a stable SEI film can be formed on the negative electrode surface, the insertion and deintercalation of lithium ions at low temperatures become smooth, thereby improving the low-temperature performance of the energy storage device. On the other hand, the sulfonate group in the disulfonate compound can coordinate with transition metal ions to form a complex, passivating the positive electrode surface, inhibiting the dissolution of positive electrode metal ions, and reducing the decomposition effect of high-oxidation active substances on the solvent, thereby improving the electrochemical performance of the energy storage device under high-temperature conditions. In the energy storage device, the disulfonate compound can inhibit the increase of DC internal resistance, thereby improving the high-temperature performance and low-temperature performance of the energy storage device.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytes, and in particular to a disulfonate compound and a preparation method thereof, as well as an electrolyte and an energy storage device. Background Art

[0002] Lithium-ion batteries are widely used in power, energy storage, aerospace, digital and other fields due to their advantages such as high energy density, high charging efficiency and long cycle life. With the continuous advancement of technology, consumers have higher requirements for battery performance. In addition to expecting batteries to have good performance at room temperature, they also expect batteries to have good performance under high and low temperature conditions. At present, in order to improve the high-temperature performance of batteries, solvents with higher boiling points are generally selected to prepare electrolytes; in order to improve the low-temperature performance of batteries, solvents with lower melting points are selected to prepare electrolytes. Such methods can improve the high-temperature performance or low-temperature performance of batteries to a certain extent, but as the scope of battery use continues to expand, such methods that cannot take into account both high-temperature and low-temperature performance cannot meet the requirements of battery use. Summary of the Invention

[0003] Based on this, it is necessary to provide a disulfonate compound and a preparation method thereof, as well as an electrolyte and an energy storage device. The disulfonate compound is applied to the electrolyte to take into account both the high temperature performance and the low temperature performance of the energy storage device.

[0004] A disulfonate compound having the structure shown in general formula (I):

[0005]

[0006] Wherein, R1 is selected from a chain alkyl group having 1 to 6 carbon atoms, a three-membered cycloalkyl group, a four-membered cycloalkyl group, a five-membered cycloalkyl group, a six-membered cycloalkyl group, a phenyl group, a tolyl group, a five-membered heterocyclic group or a six-membered heterocyclic group; R2 and R3 are independently selected from a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms or a halogenated alkyl group having 1 to 6 carbon atoms.

[0007] In one embodiment, R1 is a three-membered cycloalkyl group, a four-membered cycloalkyl group, a five-membered cycloalkyl group, a six-membered cycloalkyl group, a phenyl group, a five-membered heterocyclic group or a six-membered heterocyclic group, and It is in the ortho, meta or para position.

[0008] In one embodiment, R1 is selected from methylene, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, phenyl, furan, thiophene, pyrrole, thiazole, imidazole, pyridine, pyrazine, pyrimidine or pyridazine.

[0009] In one embodiment, R2 and R3 are independently selected from hydrogen atom, fluorine atom, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, isohexyl, fluoromethyl, fluoroethyl, fluoropropyl, fluorobutyl, fluoropentyl, fluorohexyl, fluoroisopropyl, fluoroisobutyl, fluorosec-butyl, fluorotert-butyl, fluoroisopentyl or fluoroisohexyl.

[0010] In one embodiment, R2 and R3 are independently selected from trifluoromethyl, trifluoroethyl, trifluoropropyl, trifluorobutyl, trifluoropentyl, trifluorohexyl, trifluoroisopropyl, trifluoroisobutyl, trifluorosec-butyl, trifluorotert-butyl, trifluoroisopentyl or trifluoroisohexyl.

[0011] A method for preparing the disulfonate compound described in any of the above embodiments comprises the following steps:

[0012] Under a protective gas atmosphere, a bishydroxy compound having the general formula II, a first sulfonyl halide having the general formula III, and a second sulfonyl halide having the general formula IV are reacted in a solvent containing a base.

[0013] HO-R1-OH (Ⅱ)

[0014]

[0015] wherein X1 and X2 are independently selected from halogen atoms; the reaction temperature is -50°C to 100°C; and the reaction time is 0.1h to 24h.

[0016] In one embodiment, the ratio of the sum of the amounts of the first sulfonyl halide and the second sulfonyl halide to the amount of the dihydroxy compound is (0.5-5):1; the ratio of the sum of the amounts of the first sulfonyl halide and the second sulfonyl halide to the amount of the base is 1:(0.5-3).

[0017] In one embodiment, the base is one or more of potassium hydroxide, potassium carbonate, sodium hydroxide, calcium hydroxide, pyridine, pyrrole, imidazole, trimethylamine and triethylamine; and / or,

[0018] The solvent is one or more of toluene, dichloroethane, acetonitrile, dimethyl sulfoxide and acetone.

[0019] An electrolyte comprises an electrolyte, a solvent and an additive, wherein the additive is the disulfonate compound described in any one of the above embodiments.

[0020] In one embodiment, the electrolyte accounts for 5% to 20% of the weight of the electrolyte.

[0021] In one embodiment, the additive accounts for 0.01% to 10% by weight of the electrolyte.

[0022] In one embodiment, the electrolyte is one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorophosphate and lithium bis(fluorosulfonyl)imide.

[0023] In one embodiment, the solvent includes a cyclic solvent and a linear solvent.

[0024] In one embodiment, the cyclic solvent is one or more of ethylene carbonate, propylene carbonate, γ-butyrolactone, phenyl acetate, 1,4-butane sultone and 3,3,3-trifluoropropylene carbonate; the linear solvent is one or more of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate, methylpropyl carbonate, propyl propionate, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 2,2-difluoroethyl acetate, 2,2-difluoroethyl propionate and 2,2-difluoroethyl methyl carbonate.

[0025] An energy storage device, wherein the additive in the electrolyte of the energy storage device is the disulfonate compound described in any one of the above embodiments.

[0026] In one embodiment, the energy storage device is a lithium-ion battery or a supercapacitor.

[0027] The above-mentioned bissulfonate compound is applied as an additive to the energy storage device. The bissulfonate compound decomposes, allowing a stable SEI film to form on the negative electrode surface of the energy storage device, which can inhibit the decomposition of the solvent in the electrolyte. Since a stable SEI film can be formed on the negative electrode surface, the insertion and deintercalation of lithium ions at low temperatures becomes smooth, thereby improving the low-temperature performance of the energy storage device. On the other hand, the sulfonate group in the bissulfonate compound can coordinate with the transition metal ions to form a complex, passivating the positive electrode surface, inhibiting the dissolution of the positive electrode metal ions, and at the same time reducing the decomposition effect of the active substance in the high oxidation state on the solvent, thereby improving the electrochemical performance of the energy storage device under high temperature conditions. In the energy storage device, the bissulfonate compound can inhibit the increase of the DC internal resistance, thereby improving the high-temperature performance and low-temperature performance of the energy storage device.

[0028] The preparation method of the above-mentioned disulfonate compound is to obtain it through esterification reaction of a dihydroxy compound and a sulfonyl halide. The reaction conditions are mild and the preparation method is simple.

[0029] The additive in the electrolyte of the above-mentioned energy storage device is the above-mentioned bissulfonate compound. Due to the action of the bissulfonate compound, a stable SEI film can be formed on the negative electrode surface of the energy storage device, the positive electrode surface is passivated, and the bissulfonate compound can inhibit the increase of the DC internal resistance, thereby making the above-mentioned energy storage device have good high-temperature performance and low-temperature performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 : is the NMR fluorine spectrum of the bissulfonate compound in Example 3.

[0031] Figure 2 : is the H NMR spectrum of the bissulfonate compound in Example 3. DETAILED DESCRIPTION

[0032] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0033] It should be noted that when an element is referred to as being “fixed to” another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or there may be an intermediate element.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] One embodiment of the present invention provides a disulfonate compound having a structure shown in general formula (I):

[0036]

[0037] Wherein, R1 is selected from a chain alkyl group having 1 to 6 carbon atoms, a three-membered cycloalkyl group, a four-membered cycloalkyl group, a five-membered cycloalkyl group, a six-membered cycloalkyl group, a phenyl group, a tolyl group, a five-membered heterocyclic group or a six-membered heterocyclic group; R2 and R3 are independently selected from a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms or a halogenated alkyl group having 1 to 6 carbon atoms.

[0038] In this embodiment, the disulfonate compound is applied as an additive to the energy storage device. The disulfonate compound decomposes, allowing a stable SEI film to form on the negative electrode surface of the energy storage device, which can inhibit the decomposition of the solvent in the electrolyte. Since a stable SEI film can be formed on the negative electrode surface, the insertion and deintercalation of lithium ions at low temperatures becomes smooth, thereby improving the low-temperature performance of the energy storage device. On the other hand, the sulfonate group in the disulfonate compound can coordinate with the transition metal ions to form a complex, passivating the positive electrode surface, inhibiting the dissolution of the positive electrode metal ions, and at the same time reducing the decomposition effect of the active substance in the high oxidation state on the solvent, thereby improving the electrochemical performance of the energy storage device under high temperature conditions. In the energy storage device, the disulfonate compound can inhibit the increase of the DC internal resistance, thereby improving the high-temperature performance and low-temperature performance of the energy storage device.

[0039] In a specific example, R1 is a three-membered cycloalkyl group, a four-membered cycloalkyl group, a five-membered cycloalkyl group, a six-membered cycloalkyl group, a phenyl group, a five-membered heterocyclic group or a six-membered heterocyclic group, and It is in the ortho, meta or para position.

[0040] In a specific example, R1 is selected from methylene, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, phenyl, furan, thiophene, pyrrole, thiazole, imidazole, pyridine, pyrazine, pyrimidine or pyridazine.

[0041] In a specific example, R2 and R3 are independently selected from a hydrogen atom, a fluorine atom, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, an isohexyl group, a fluoromethyl group, a fluoroethyl group, a fluoropropyl group, a fluorobutyl group, a fluoropentyl group, a fluorohexyl group, a fluoroisopropyl group, a fluoroisobutyl group, a fluorosec-butyl group, a fluorotert-butyl group, a fluoroisopentyl group or a fluoroisohexyl group.

[0042] Preferably, R2 and R3 contain fluorine atoms. The disulfonate compound composed of R2 and R3 containing fluorine atoms can form a stable and flexible SEI in the energy storage device, which is more conducive to improving the high-temperature performance and low-temperature performance of the energy storage device.

[0043] In a specific example, R2 and R3 are independently selected from trifluoromethyl, trifluoroethyl, trifluoropropyl, trifluorobutyl, trifluoropentyl, trifluorohexyl, trifluoroisopropyl, trifluoroisobutyl, trifluorosec-butyl, trifluorotert-butyl, trifluoroisopentyl or trifluoroisohexyl.

[0044] One embodiment of the present invention provides a method for preparing the above-mentioned disulfonate compound, comprising the following steps:

[0045] Under a protective gas atmosphere, a bishydroxy compound having the general formula II, a first sulfonyl halide having the general formula III, and a second sulfonyl halide having the general formula IV are reacted in a solvent containing a base.

[0046] HO-R1-OH (Ⅱ)

[0047]

[0048] wherein X1 and X2 are independently selected from halogen atoms; the reaction temperature is -50°C to 100°C; and the reaction time is 0.1h to 24h.

[0049] In a specific example, the protective gas atmosphere is a nitrogen protective atmosphere. It is understandable that the protective gas atmosphere can also be an inert gas protective atmosphere.

[0050] Preferably, the reaction temperature is between -20°C and 60°C. If the reaction temperature is too low, the reactivity of the reactants is low and the reaction time is long; if the reaction temperature is too high, the degree of side reactions will increase and even product decomposition may occur. When the reaction temperature is between -20°C and 60°C, the reactants are more active and the degree of side reactions is low, which is conducive to improving the reaction rate and reaction yield.

[0051] Preferably, the reaction time is 0.5 h to 10 h. If the reaction time is too short, reactants may remain, the reaction may be incomplete, and the reaction yield may be low. If the reaction time is too long, the degree of side reactions may increase and even product decomposition may occur. In actual production processes, the appropriate reaction time can be selected based on the reaction scale and reaction temperature.

[0052] In a specific example, the ratio of the sum of the amounts of the first sulfonyl halide and the second sulfonyl halide to the amount of the dihydroxy compound is (0.5-5):1; the ratio of the sum of the amounts of the first sulfonyl halide and the second sulfonyl halide to the amount of the base is 1:(0.5-3).

[0053] Preferably, the ratio of the sum of the amounts of the first sulfonyl halide and the second sulfonyl halide to the amount of the dihydroxy compound is (0.9-2.3):1; the ratio of the sum of the amounts of the first sulfonyl halide and the second sulfonyl halide to the amount of the base is 1:(0.9-1.3).

[0054] In a specific example, the base is one or more of potassium hydroxide, potassium carbonate, sodium hydroxide, calcium hydroxide, pyridine, pyrrole, imidazole, trimethylamine and triethylamine; and / or,

[0055] The solvent is one or more of toluene, dichloroethane, acetonitrile, dimethyl sulfoxide and acetone.

[0056] An embodiment of the present invention provides an electrolyte solution including an electrolyte, a solvent, and an additive, wherein the additive is the above-mentioned disulfonate compound.

[0057] In one specific example, the electrolyte accounts for 5% to 20% of the weight of the electrolyte. When the electrolyte accounts for 5% to 20% of the weight of the electrolyte, the positive and negative ions have a higher transmission rate, which can improve the electrochemical performance of the energy storage device. Preferably, the electrolyte accounts for 10% to 18% of the weight of the electrolyte.

[0058] In a specific example, the additive accounts for 0.01% to 10% by weight of the electrolyte. If the additive content is too low, the improvement effect on the high and low temperature performance of the energy storage device will be poor; if the additive content is too high (the additive accounts for more than 10% by weight of the electrolyte), the SEI film will be too thick, which will increase the impedance of the battery.

[0059] Preferably, the additive accounts for 0.01% to 0.08%, 0.1% to 5%, or 6% to 9% of the weight of the electrolyte. More preferably, the bissulfonate compound accounts for 0.05%, 0.5%, 1%, 2%, 3%, or 8% of the weight of the electrolyte.

[0060] In a specific example, the electrolyte is one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorophosphate, and lithium bis(fluorosulfonyl)imide.

[0061] In a specific example, the solvent includes a cyclic solvent and a linear solvent.

[0062] In a specific example, the cyclic solvent is one or more of ethylene carbonate, propylene carbonate, γ-butyrolactone, phenyl acetate, 1,4-butane sultone and 3,3,3-trifluoropropylene carbonate; the linear solvent is one or more of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate, methylpropyl carbonate, propyl propionate, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 2,2-difluoroethyl acetate, 2,2-difluoroethyl propionate and 2,2-difluoroethyl methyl carbonate.

[0063] An embodiment of the present invention provides an energy storage device, wherein the additive in the electrolyte of the energy storage device is the above-mentioned disulfonate compound.

[0064] In one embodiment, the energy storage device is a lithium-ion battery or a supercapacitor.

[0065] In a specific example, the positive electrode material of the energy storage device includes Li 1+a (Ni x Co y M 1-x-y )O2、Li(Ni p Mnq Co 2-p-q )O4 and LiM h (PO4) m One or more of the following; wherein 0≤a≤0.3, 0≤x≤1, 0≤y≤1, 0<x+y≤1; 0≤p≤2, 0≤q≤2, 0<p+q≤2; 0<h<5, 0<m<5; M is Fe, Ni, Co, Mn, Al or V.

[0066] In a specific example, the negative electrode material of the energy storage device includes one or more of metallic lithium, lithium alloy, carbon, silicon-based negative electrode material and tin-based negative electrode material.

[0067] The aforementioned bissulfonate compound is an additive in the electrolyte of the energy storage device in this embodiment. Due to the action of the bissulfonate compound, a stable SEI film forms on the negative electrode surface of the energy storage device, passivating the positive electrode surface. Furthermore, the bissulfonate compound suppresses the increase in DC internal resistance, thereby enabling the energy storage device to exhibit excellent high- and low-temperature performance. This energy storage device exhibits excellent high- and low-temperature performance, maintaining good capacity retention during storage or use under both high and low temperature conditions.

[0068] The following are specific examples.

[0069] 1. Assemble lithium-ion batteries.

[0070] Example 1

[0071] (1) The structural formula of the disulfonate compound in this embodiment is shown in Formula (V).

[0072]

[0073] The preparation method of the bissulfonate compound in formula (V) is as follows: under a nitrogen atmosphere and at room temperature, hydroquinone, toluene, and triethylamine are added to a reaction kettle, and then a first sulfonyl halide (R2 is a trifluoromethyl group, X1 is a fluorine atom) and a second sulfonyl halide (R3 is a trifluoromethyl group, X2 is a fluorine atom) are added to the reaction kettle at 0°C to 10°C. The reaction temperature is adjusted to 40°C to 45°C, and the reaction time is 8 hours to 10 hours.

[0074] The amounts of the first sulfonyl halide and the second sulfonyl halide are equal, and the ratio of the sum of the amounts of the first sulfonyl halide and the second sulfonyl halide to the amount of hydroquinone is 2:1. The ratio of the sum of the amounts of the first sulfonyl halide and the second sulfonyl halide to the amount of triethylamine is 1:1.

[0075] (2) Assembling lithium-ion batteries:

[0076] In this embodiment, the disulfonate compound accounts for 1% of the weight of the electrolyte; the electrolyte is lithium hexafluorophosphate, and the electrolyte accounts for 13% of the weight of the electrolyte; the solvent is a mixture of ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2; the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O2; the negative electrode material is artificial graphite; the separator is polyethylene film. Soft-pack batteries are assembled according to conventional methods.

[0077] Example 2

[0078] (1) The structural formula of the disulfonate compound in this embodiment is shown in Formula (V).

[0079] (2) Assembling lithium-ion batteries:

[0080] In this embodiment, the disulfonate compound accounts for 0.5% by weight of the electrolyte; the electrolyte is lithium hexafluorophosphate, and the electrolyte accounts for 13% by weight of the electrolyte; the solvent is a mixture of ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2; the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O2; the negative electrode material is artificial graphite; the separator is polyethylene film. Soft-pack batteries are assembled according to conventional methods.

[0081] Example 3

[0082] (1) The structural formula of the bissulfonate compound in this embodiment is shown in Formula (VI).

[0083]

[0084] The preparation method of the bissulfonate compound in formula (VI) is as follows: under a nitrogen atmosphere, hydroquinone, toluene, and triethylamine are added to a reaction kettle at room temperature, and then a first sulfonyl halide (R2 is a fluorine atom, X1 is a fluorine atom) and a second sulfonyl halide (R3 is a fluorine atom, X2 is a fluorine atom) are added to the reaction kettle at 0°C to 10°C. The reaction temperature is adjusted to 43°C to 50°C, and the reaction time is 1 hour to 4 hours.

[0085] The amounts of the first sulfonyl halide and the second sulfonyl halide are equal, and the ratio of the sum of the amounts of the first sulfonyl halide and the second sulfonyl halide to the amount of hydroquinone is 2:1. The ratio of the sum of the amounts of the first sulfonyl halide and the second sulfonyl halide to the amount of triethylamine is 1:1.

[0086] The nuclear magnetic resonance fluorine spectrum of the disulfonate compound in formula (VI) is as follows: Figure 1 As shown, 19F-NMR (400 MHz, deuterated DMSO), δ 39.2 ppm (s, 2F).

[0087] The nuclear magnetic resonance hydrogen spectrum of the disulfonate compound in formula (VI) is as follows: Figure 2 As shown, 1 H-NMR (400 MHz, deuterated DMSO), δ 7.9 ppm (s, 4H).

[0088] (2) Assembling lithium-ion batteries:

[0089] In this embodiment, the disulfonate compound accounts for 1% of the weight of the electrolyte; the electrolyte is lithium hexafluorophosphate, and the electrolyte accounts for 13% of the weight of the electrolyte; the solvent is a mixture of ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2; the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O2; the negative electrode material is artificial graphite; the separator is polyethylene film. Soft-pack batteries are assembled according to conventional methods.

[0090] Example 4

[0091] (1) The structural formula of the bissulfonate compound in this embodiment is shown in Formula (VI).

[0092] (2) Assembling lithium-ion batteries:

[0093] In this embodiment, the disulfonate compound accounts for 10% by weight of the electrolyte; the electrolyte is lithium hexafluorophosphate, and the electrolyte accounts for 13% by weight of the electrolyte; the solvent is a mixture of ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2; the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O2; the negative electrode material is artificial graphite; the separator is polyethylene film. Soft-pack batteries are assembled according to conventional methods.

[0094] Example 5

[0095] (1) The structural formula of the bissulfonate compound in this embodiment is shown in Formula (VI).

[0096] (2) Assembling lithium-ion batteries:

[0097] In this embodiment, the disulfonate compound accounts for 1% of the weight of the electrolyte; the electrolyte is lithium hexafluorophosphate, and the electrolyte accounts for 13% of the weight of the electrolyte; the solvent is a mixture of ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2; the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1O2; the negative electrode material is a silicon-carbon composite material; the separator is a polyethylene film. Soft-pack batteries are assembled according to conventional methods.

[0098] Example 6

[0099] (1) The structural formula of the bissulfonate compound in this embodiment is shown in Formula (VI).

[0100] (2) Assembling lithium-ion batteries:

[0101] In this embodiment, the disulfonate compound accounts for 1% of the weight of the electrolyte; the electrolyte is lithium hexafluorophosphate, and the electrolyte accounts for 13% of the weight of the electrolyte; the solvent is a mixture of ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2; the positive electrode material is LiNi 0.6 Co 0.2 Mn 0.2 O2; the negative electrode material is artificial graphite; the separator is polyethylene film. Soft-pack batteries are assembled according to conventional methods.

[0102] Example 7

[0103] (1) The structural formula of the bissulfonate compound in this embodiment is shown in Formula (VI).

[0104] (2) Assembling lithium-ion batteries:

[0105] In this embodiment, the disulfonate compound accounts for 1% of the weight of the electrolyte; the electrolyte is lithium hexafluorophosphate, and the electrolyte accounts for 18% of the weight of the electrolyte; the solvent is a mixture of ethylene carbonate and dimethyl carbonate in a weight ratio of 1:2; the positive electrode material is LiNi 0.6 Co 0.2 Mn 0.2 O2; the negative electrode material is artificial graphite; the separator is polyethylene film. Soft-pack batteries are assembled according to conventional methods.

[0106] Example 8

[0107] (1) The structural formula of the disulfonate compound in this embodiment is shown in Formula (V).

[0108] (2) Assembling lithium-ion batteries:

[0109] In this embodiment, the disulfonate compound accounts for 1% of the weight of the electrolyte; the electrolyte is lithium hexafluorophosphate, and the electrolyte accounts for 13% of the weight of the electrolyte; the solvent is a solvent composed of ethylene carbonate and 2,2-difluoroethyl propionate in a weight ratio of 1:2; the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O2; the negative electrode material is artificial graphite; the separator is polyethylene film. Soft-pack batteries are assembled according to conventional methods.

[0110] Example 9

[0111] (1) The structural formula of the disulfonate compound in this embodiment is shown in Formula (V).

[0112] (2) Assembling lithium-ion batteries:

[0113] In this embodiment, the bissulfonate compound accounts for 1% of the weight of the electrolyte; the electrolyte is lithium hexafluorophosphate and lithium bisfluorosulfonyl imide, and the lithium hexafluorophosphate and lithium bisfluorosulfonyl imide account for 10% and 3% of the weight of the electrolyte respectively; the solvent is a solvent composed of ethylene carbonate and 2,2-difluoroethyl propionate in a weight ratio of 1:2; the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O2; the negative electrode material is artificial graphite; the separator is polyethylene film. Soft-pack batteries are assembled according to conventional methods.

[0114] Example 10

[0115] (1) The structural formula of the disulfonate compound in this embodiment is shown in Formula (V).

[0116] (2) Assembling lithium-ion batteries:

[0117] In this embodiment, the disulfonate compound accounts for 1% of the weight of the electrolyte; the electrolyte is lithium hexafluorophosphate, accounting for 13% of the weight of the electrolyte; the solvent is a mixture of 3,3,3-trifluoropropylene carbonate and 2,2-difluoroethyl acetate in a weight ratio of 1:2; the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O2; the negative electrode material is artificial graphite; the separator is polyethylene film. Soft-pack batteries are assembled according to conventional methods.

[0118] Comparative Example 1

[0119] Compared with Example 1, Comparative Example 1 is different in that the electrolyte does not contain a disulfonate compound.

[0120] Comparative Example 2

[0121] Compared with Comparative Example 1, Comparative Example 2 is different in that the additive is vinyl sulfate additive accounting for 1% by weight of the electrolyte.

[0122] Comparative Example 3

[0123] Compared with Comparative Example 1, Comparative Example 3 is different in that the additive is 1,3-propane sultone additive accounting for 1% by weight of the electrolyte.

[0124] 2. High and low temperature performance test of lithium-ion batteries.

[0125] The lithium ion batteries in Examples 1 to 10 and Comparative Examples 1 to 3 were tested for high and low temperature performance using the following test methods:

[0126] High-temperature cycling performance: The lithium-ion battery was placed in a constant temperature box at 45°C, charged to 4.2V at a constant current and constant voltage of 1C, and then discharged to 3.0V at a constant current of 1C. The cycle was repeated 400 times to determine the capacity retention rate of the lithium-ion battery.

[0127] High-temperature storage performance: The formed lithium-ion battery was charged to 4.2V at room temperature using a 1C constant current and constant voltage (CCCV) current. The initial capacity of the battery was measured. After storage at 60°C for 30 days, the battery was discharged to 3V at a 1C current and then recharged to 4.2V. The capacity retention of the lithium-ion battery was measured.

[0128] Low-temperature discharge performance: The formed lithium-ion battery is charged to 4.2V at room temperature using a constant current and constant voltage of 1C, and the initial capacity of the battery is measured. The battery is then placed in a constant temperature box at -20°C and discharged to 2.5V at 0.5C, and the capacity retention rate of the lithium-ion battery is measured.

[0129] The test results are shown in Table 1:

[0130] Table 1

[0131]

[0132] As can be seen from Table 1, the high-temperature cycle performance, high-temperature storage performance, and low-temperature discharge performance of the lithium-ion batteries in Examples 1 to 10 are better than those in Comparative Examples 1 to 3, indicating that the electrolyte additives in Examples 1 to 10 can effectively improve the high-temperature performance and low-temperature performance of lithium-ion batteries.

[0133] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0134] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. An energy storage device, characterized in that: The additive in the electrolyte of the energy storage device is a disulfonate compound having a structure represented by general formula (I): wherein R1 is selected from phenyl or tolyl; R2 and R3 are independently selected from halogen atoms; The positive electrode material of the energy storage device includes Li 1+a (Ni x Co y M 1-x-y )O2, wherein 0≤a≤0.3, 0<x<1, 0<y<1, 0<x+y<1, M is Mn, and the negative electrode material of the energy storage device is graphite.

2. The energy storage device according to claim 1, characterized in that and It is in the ortho, meta or para position.

3. The energy storage device according to claim 1, characterized in that R2 and R3 are independently selected from fluorine atoms.

4. The energy storage device according to any one of claims 1 to 3, characterized in that: The preparation method of the disulfonate compound comprises the following steps: Under a protective gas atmosphere, a bishydroxy compound having the general formula II, a first sulfonyl halide having the general formula III, and a second sulfonyl halide having the general formula IV are reacted in a solvent containing a base. HO-R1-OH (Ⅱ) wherein X1 and X2 are independently selected from halogen atoms; the reaction temperature is -50°C to 100°C; and the reaction time is 0.1h to 24h.

5. The energy storage device according to claim 4, characterized in that The ratio of the sum of the amounts of the first sulfonyl halide and the second sulfonyl halide to the amount of the dihydroxy compound is (0.5-5):1; the ratio of the sum of the amounts of the first sulfonyl halide and the second sulfonyl halide to the amount of the base is 1:(0.5-3).

6. The energy storage device according to claim 4, characterized in that The base is one or more of potassium hydroxide, potassium carbonate, sodium hydroxide, calcium hydroxide, pyridine, pyrrole, imidazole, trimethylamine and triethylamine; and / or, The solvent is one or more of toluene, dichloroethane, acetonitrile, dimethyl sulfoxide and acetone.

7. The energy storage device according to any one of claims 1 to 3, characterized in that: The electrolyte further comprises an electrolyte and a solvent, and the electrolyte accounts for 5% to 20% of the weight of the electrolyte.

8. The energy storage device according to claim 7, characterized in that The additive accounts for 0.01% to 10% of the weight of the electrolyte.

9. The energy storage device according to claim 1, characterized in that The electrolyte is one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluorophosphate and lithium bis(fluorosulfonyl)imide.

10. The energy storage device according to claim 7, characterized in that: The solvent includes a cyclic solvent and a linear solvent.

11. The energy storage device according to claim 10, characterized in that The cyclic solvent is one or more of ethylene carbonate, propylene carbonate, γ-butyrolactone, phenyl acetate, 1,4-butane sultone and 3,3,3-trifluoropropylene carbonate; the linear solvent is one or more of dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate, methylpropyl carbonate, propyl propionate, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 2,2-difluoroethyl acetate, 2,2-difluoroethyl propionate and 2,2-difluoroethyl methyl carbonate.

12. The energy storage device according to any one of claims 1 to 3, characterized in that: The energy storage device is a lithium-ion battery.

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