Electrolyte, use, lithium-ion battery, battery module, battery pack

Abstract

The application relates to an electrolyte, comprising a solvent and a compound of general formula I having the following structure. By adding the compound of general formula I in the electrolyte, the oxidative decomposition of the solvent in the electrolyte can be effectively inhibited, so that the cycle performance of the battery is improved. The application also relates to a new use of the compound of general formula I, a lithium ion battery, a battery module, a battery pack and a power utilization device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to an electrolyte, an application, a lithium ion battery, a battery module, a battery pack and a power utilization device. BACKGROUND

[0002] With the development of technology, clean energy such as batteries gradually replaces traditional fossil energy to provide power for various scenes. In particular, lithium ion batteries have become the most popular energy storage system due to their low cost, long life, good safety and other characteristics, and have been widely used in pure electric vehicles, hybrid electric vehicles, smart grids and other fields. However, the chemical properties of the commonly used electrolyte in lithium ion batteries are unstable at the working voltage, which leads to the degradation of the cycle performance of the battery.

[0003] Therefore, it is necessary to develop an electrolyte which can improve the cycle performance of the battery. SUMMARY

[0004] In view of the problems in the background art, the present application provides an electrolyte which can improve the cycle performance of the battery.

[0005] The electrolyte provided by the first aspect of the present application comprises a solvent and a compound of general formula I having the following structure:

[0006]

[0007] wherein,

[0008] R 1 , R 2 and R 3 are each independently selected from hydrogen, nitro, cyano, halogen, hydroxyl, carboxyl, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkylsulfonyl;

[0009] R 4 is selected from perfluoroalkyl, -BF3 - ;

[0010] M x+ is selected from sodium ion, potassium ion, zinc ion, and x is the valence state of the metal element;

[0011] when R 4 is selected from perfluoroalkyl, m is 1 and n is 0;

[0012] when R 4 is selected from BF3 - , m is 1 or 2 and n is 1.

[0013] The technical scheme of the embodiments of the present application can effectively inhibit the oxidative decomposition of the solvent in the electrolyte, thereby improving the cycle performance of the battery. The specific principle is as follows: the solvent in the electrolyte is prone to solvation with lithium ions, and the solvated solvent has enhanced activity at the working voltage, is chemically active, and is prone to oxidative dehydrogenation decomposition. The compound of general formula I added in the present application can weaken the solvation ability of lithium ions or form solvation competition with the electrolyte solvent, thereby effectively inhibiting the solvation of the electrolyte solvent with lithium ions and avoiding the oxidative dehydrogenation decomposition of the solvent.

[0014] In addition, since the oxidative decomposition of the solvent in the electrolyte is effectively inhibited, the generation of hydrogen is also effectively inhibited, the gas generation behavior of the battery is improved, and the risk of combustion and explosion is avoided.

[0015] In some embodiments, according to the first aspect, a first example of the first aspect is proposed, R 1 , R 2 , and R 3 are selected from the group consisting of nitro, cyano, halogen, hydroxyl, carboxyl, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, and substituted or unsubstituted alkylsulfonyl.

[0016] R 1 , R 2 , and R 3 are selected from the group consisting of nitro, cyano, halogen, hydroxyl, carboxyl, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, and substituted or unsubstituted alkylsulfonyl.

[0017] In some embodiments, according to the first aspect, a second example of the first aspect is proposed, R 1 , R 2 , and R 3 are independently selected from the group consisting of hydrogen, nitro, cyano, carboxyl, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, and substituted or unsubstituted alkylsulfonyl.

[0018] By optimizing the substituents on the benzene ring, the oxidative decomposition of the electrolyte solvent can be further inhibited.

[0019] In some embodiments, according to the first aspect, a third example of the first aspect is proposed, R 1 , and R 3 are independently selected from the group consisting of hydrogen. R 2 is selected from the group consisting of nitro, cyano, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, and substituted or unsubstituted alkylsulfonyl.

[0020] R2 is a high electronegative group, and is located at the para position of R 4 The design is beneficial to increase the polarity of the compound of general formula I, and further enhance the solvation of the compound of general formula I with lithium ions, and weaken the solvation of the electrolyte solvent with lithium ions, thereby effectively inhibiting the oxidative decomposition of the electrolyte solvent.

[0021] In some embodiments, according to the first aspect, a fourth example of the first aspect is provided, the alkyl group is C1-C 20 alkyl group. The alkoxy group is C1-C 20 alkoxy group. The alkylsulfonyl group is C1-C 20 alkylsulfonyl group. The perfluoroalkyl group is C1-C 20 perfluoroalkyl group.

[0022] In the design, by optimizing each substituent on the benzene ring, the oxidative decomposition of the electrolyte solvent is further inhibited.

[0023] In some embodiments, according to the first aspect, a fifth example of the first aspect is provided, the compound of general formula I is selected from one or more of the following structures:

[0024]

[0025] When the compound of general formula I is selected from the above structures, the oxidative decomposition of the electrolyte solvent is effectively inhibited, and the cycle performance of the battery is significantly improved.

[0026] In some embodiments, according to the first aspect, a sixth example of the first aspect is provided, the solvent includes a cyclic carbonate.

[0027] The cyclic carbonate solvent has higher chemical activity after solvation with lithium ions, and is more prone to oxidative dehydrogenation decomposition. Therefore, by adding the compound of general formula I to the electrolyte containing such a solvent, the oxidative decomposition of the solvent can be more significantly inhibited, and the cycle performance of the battery can be improved.

[0028] In some embodiments, according to the first aspect, a seventh example of the first aspect is provided, the cyclic carbonate is selected from one or more of vinyl carbonate and propylene carbonate.

[0029] Vinyl carbonate and propylene carbonate are commonly used organic solvents in electrolytes. By adding the compound of general formula I to the electrolyte containing them, the decomposition thereof can be effectively inhibited, and the cycle performance of the battery using the solvent system can be optimized.

[0030] In some embodiments, according to the first aspect, an eighth example of the first aspect is provided, the mass fraction of the compound of general formula I in the electrolyte is 0.05%-1%.

[0031] In the design, by optimizing the adding amount of the compound of general formula I, the battery performance can be further improved. The adding amount of the compound of general formula I cannot be too small, otherwise the effect of inhibiting the oxidative dehydrogenation decomposition of the solvent will be weakened, and the adding amount of the compound of general formula I cannot be too large, otherwise the conductivity of the electrolyte will be seriously reduced.

[0032] The second aspect of the application provides a use of the compound of general formula I for inhibiting the decomposition of the solvent in the electrolyte. The compound of general formula I has the following structure:

[0033]

[0034] wherein,

[0035] R 1 , R 2 and R 3 are independently selected from hydrogen, nitro, cyano, halogen, hydroxyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkylsulfonyl;

[0036] R 4 is selected from perfluoroalkyl, -BF3 - ;

[0037] M x+ is selected from sodium ion, potassium ion, zinc ion, and x is the valence state of the metal element;

[0038] In the case where R 4 is selected from perfluoroalkyl, m is 1 and n is 0;

[0039] In the case where R 4 is selected from BF3 - , m is 1 or 2 and n is 1.

[0040] The compound of general formula I of the application can inhibit the decomposition of the solvent in the electrolyte, effectively improving the cycle performance of the battery.

[0041] The third aspect of the application provides a lithium ion battery, comprising a positive electrode sheet, a negative electrode sheet, a separator and the electrolyte of the first aspect of the application.

[0042] In the technical solution of the embodiments of the application, since the electrolyte of the first aspect of the application is used, the lithium ion battery of the application has improved cycle performance.

[0043] In some embodiments, according to the third aspect, the first example of the third aspect is provided, the positive electrode sheet comprises a lithium supplementing agent. The lithium supplementing agent is selected from Li2O, Li2O2, Li5FeO4, Li6CoO4, Li y Ni a Cu b O 0.5(2+y)one or more of the following: a+b = 1, 1 < y < 3.

[0044] The application effectively inhibits the decomposition of the electrolyte solvent by adding the compound of general formula I in the electrolyte, and expands the application scenarios of the above-mentioned lithium supplement.

[0045] In some embodiments, according to the third aspect, a second example of the third aspect is provided, the positive electrode sheet further comprises a positive electrode active material. The proportion of the mass of the lithium supplement to the total mass of the positive electrode active material and the lithium supplement is (0.5-20):100.

[0046] The mass proportion of the lithium supplement affects the life and energy density of the battery. When the mass proportion of the lithium supplement is too low, the amount of lithium ions supplemented by the lithium supplement during the first charging process will be too small to meet the consumption of active lithium ions during long-term cycling of the battery, and long life cannot be achieved. When the mass proportion of the lithium supplement is too high, the proportion of active materials used for later reversible cycling will decrease, which is not conducive to the energy density of the battery. Therefore, it is particularly important to select a suitable proportion of lithium supplement to balance the life and energy density of the battery.

[0047] In some embodiments, according to the third aspect, a third example of the third aspect is provided, the average D50 particle size of the lithium supplement is 0.5-50 μm.

[0048] If the average D50 particle size of the lithium supplement material is too small, the positive electrode slurry will be prone to agglomeration and gelation, the viscosity will increase, and the solid content will decrease. If the particle size is too large, the polarization of lithium ion extraction reaction in the lithium supplement will increase, thereby reducing the lithium supplement efficiency.

[0049] The fourth aspect of the application provides a battery module comprising the lithium ion battery of the third aspect of the application.

[0050] In the technical solution of the embodiments of the application, since the electrolyte of the first aspect of the application is used, the battery module of the application has improved cycle performance.

[0051] The fifth aspect of the application provides a battery pack comprising the lithium ion battery of the third aspect of the application or the lithium ion battery of the third aspect of the application or the battery module of the fourth aspect of the application.

[0052] In the technical solution of the embodiments of the application, since the electrolyte of the first aspect of the application is used, the battery module of the application has improved cycle performance.

[0053] The sixth aspect of the application provides a power utilization device comprising at least one of the secondary battery of the third aspect of the application, the battery module of the fourth aspect of the application, and the battery pack of the fifth aspect of the application.

[0054] The technical scheme of the embodiment of the present application adopts the electrolyte of the first aspect of the present application, so that the power utilization device of the present application has improved cycle performance.

[0055] The above description is only a summary of the technical scheme of the present application. In order to more clearly understand the technical means of the present application, the content of the specification can be implemented, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. DETAILED DESCRIPTION

[0056] In order to make the purposes, technical schemes and beneficial technical effects of the present application clearer, the present application will be described in detail below in combination with specific embodiments. It should be understood that the embodiments described in the specification are only for the purpose of explaining the present application, and are not intended to limit the present application.

[0057] For the sake of simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form a range that is not explicitly recited; and any lower limit can be combined with other lower limits to form a range that is not explicitly recited, as can any upper limit with any other upper limit. Furthermore, although not explicitly recited, every point or individual number within a range is to be included as the range. Thus, every point or individual number can serve as its own lower limit or upper limit to combine with any other point or individual number or to combine with other lower limits or upper limits to form a range that is not explicitly recited.

[0058] In the description herein, it should be noted that, unless otherwise specified, "above", "below" are inclusive of the number, and "more than one" means two or more (including two).

[0059] The above summary of the present application is not intended to describe every disclosed embodiment or every implementation in the present application. The following description illustrates the exemplary embodiments more specifically. In many places throughout the application, guidance is provided by a series of embodiments, which can be used in various combinations. In each instance, the list is merely representative of a group, and should not be interpreted as exhaustive.

[0060] With the development of technology, clean energy such as secondary batteries gradually replaces traditional fossil energy to provide power for various scenes. In particular, lithium ion batteries have become the most popular energy storage system due to their low cost, long life, good safety and other characteristics, and have been widely used in pure electric vehicles, hybrid electric vehicles, smart grids and other fields. However, the chemical properties of the electrolyte commonly used in secondary batteries are not stable at the working voltage, which leads to the deterioration of the cycle performance of the battery. Therefore, it is necessary to develop an electrolyte that can improve the cycle performance of the battery.

[0061] The inventors have found that the reason for the chemical instability of the electrolyte at the working voltage is that the solvation of the polar solvent with lithium ions causes a change in the charge distribution on the solvent molecules, making the carbon-hydrogen bond in the solvent molecule far from the lithium ion more easily broken, reducing the activation energy of the dehydrogenation reaction and increasing the reactivity. If Li2O, Li2O2, Li5FeO4 and other high-voltage positive electrode lithium supplement agents that release oxygen are used, the solvent is more likely to be oxidized and dehydrogenated at the working voltage, and more HF is generated, which seriously affects the cycle performance of the battery.

[0062] To solve this problem, existing additives such as 3-isopropyl benzene borate ethylene glycol ester passivate the positive electrode by replacing solvent decomposition to form a highly stable CEI film, thereby inhibiting the oxidative decomposition of the solvent. Through in-depth research, the inventors have designed an electrolyte comprising a solvent and a compound of general formula I. By adding the compound of general formula I to the electrolyte, the solvation of lithium ions with the solvent can be weakened, and the oxidative decomposition of the solvent in the electrolyte can be effectively inhibited, thereby improving the cycle performance of the battery. The specific principle is as follows. The benzene ring of the compound of general formula I is provided with a perfluoroalkyl group or a trifluoroborate group (-BF3 - ). Since F atoms have the highest electronegativity, the perfluoroalkyl group such as trifluoromethyl (-CF3) becomes a strong electron-withdrawing group. In the presence of a perfluoroalkyl group, the compound of general formula I itself has strong polarity and can compete with the electrolyte solvent to form solvation, reducing the solvation of the electrolyte solvent with lithium ions, reducing the activity of the solvent, and making it less likely to undergo oxidative decomposition. Alternatively, in the presence of a trifluoroborate group BF3 - , the six F atoms on two compounds of general formula I can form a 6-coordinated compound with a Li ion, weakening the solvation ability of the lithium ion, making it less likely to solvate with the electrolyte solvent, and thus reducing the activity of the electrolyte solvent, making it less likely to undergo oxidative decomposition. In addition, the benzene ring of the compound of general formula I can also be provided with a high electronegativity group. By providing a high electronegativity group, the polarity of the compound of general formula I is increased, thereby enhancing the solvation of the compound of general formula I with lithium ions, and correspondingly weakening the solvation of the electrolyte solvent with lithium ions, thereby effectively inhibiting the oxidative decomposition of the electrolyte solvent. Therefore, the addition of the compound of general formula I can effectively inhibit the solvation of the electrolyte solvent with lithium ions, avoid the oxidative dehydrogenation decomposition of the solvent, and thus improve the cycle performance of the battery.

[0063] In addition, since the dehydrogenation reaction of the solvent in the electrolyte is effectively inhibited, the generation of hydrogen is also effectively inhibited, the gas generation behavior of the battery is improved, and the risk of combustion and explosion is avoided.

[0064] The technical solutions described in the embodiments of the present application are not only suitable for electrolyte, but also suitable for lithium ion battery using electrolyte, battery module using lithium ion battery, battery pack using battery module, and electric device using at least one of lithium ion battery, battery module and battery pack.

[0065] Specifically, the first aspect of the present application provides an electrolyte, comprising: a solvent and a compound of general formula I having the following structure:

[0066]

[0067] wherein,

[0068] R 1 , R 2 and R 3 are independently selected from hydrogen, nitro, cyano, halogen, hydroxyl, carboxyl, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkylsulfonyl;

[0069] R 4 is selected from perfluoroalkyl, -BF3 - ;

[0070] M x+ is selected from sodium ion, potassium ion, zinc ion, and x is the valence state of the metal element;

[0071] In the case where R 4 is selected from perfluoroalkyl, m is 1 and n is 0;

[0072] In the case where R 4 is selected from BF3 - , m is 1 or 2 and n is 1.

[0073] In some specific embodiments, the solvent can be selected from one or more of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl sulfone (ESE).

[0074] In some embodiments, R 1 , R 2 and R 3At least one of them is selected from nitro, cyano, halogen, hydroxyl, carboxyl, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkylsulfonyl.

[0075] R 1 R 2 and R 3 At least one of them is a highly electronegative group. The presence of these highly electronegative groups is beneficial to increasing the polarity of the compound of general formula I, thereby enhancing the solvation interaction between the compound of general formula I and lithium ions, and correspondingly weakening the solvation interaction between the electrolyte solvent and lithium ions, thus effectively inhibiting the oxidative decomposition of the electrolyte solvent.

[0076] In some embodiments, R 1 R 2 and R 3 They are independently selected from hydrogen, nitro, cyano, carboxyl, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkylsulfonyl.

[0077] Optimizing the substituents on the benzene ring can help to further suppress the oxidative decomposition of the electrolyte solvent.

[0078] In some embodiments, R 1 and R 3 They are independently selected from hydrogen. R 2 It is selected from nitro, cyano, substituted or unsubstituted alkyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkylsulfonyl.

[0079] R 2 It is a highly electronegative group located at R 4 At the para position, the highly electronegative group can attract electrons to R. 2 The proximity of the functional groups increases the polarity of the compound of general formula I, thereby enhancing the solvation effect between the compound of general formula I and lithium ions, while weakening the solvation effect between the electrolyte solvent and lithium ions, thus effectively inhibiting the oxidative decomposition of the electrolyte solvent.

[0080] In some embodiments, the alkyl group is C1-C. 20 Alkyl group. Alkoxy group is C1-C. 20 Alkoxy group. Alkyl sulfonyl group is C1-C. 20 Alkyl sulfonyl group. Perfluoroalkyl group is C1-C. 20 Perfluoroalkyl.

[0081] Optimizing the substituents on the benzene ring can help to further suppress the oxidative decomposition of the electrolyte solvent.

[0082] In some specific embodiments, the alkoxy group may be C1-C. 12alkylsulfonyl, which can be C1-C6alkylsulfonyl, for example, can be methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl, or hexylsulfonyl.

[0083] In some embodiments, the alkylsulfonyl group can be C1-C 12 alkylsulfonyl, which can be C1-C6alkylsulfonyl, for example, can be methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl, or hexylsulfonyl.

[0084] In some embodiments, the perfluoroalkyl group can be C1-C 12 perfluoroalkyl, which can be C1-C6perfluoroalkyl, for example, can be perfluoromethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, or perfluorohexyl.

[0085] In some embodiments, the compound of general formula I is selected from one or more of the following structures:

[0086] When the compound of general formula I is selected from the above structures, the oxidative decomposition of the electrolyte solvent is effectively inhibited, and the cycle performance of the battery is significantly improved.

[0087] In some embodiments, the solvent includes a cyclic carbonate.

[0088] The cyclic carbonate solvent has higher chemical activity after solvation with lithium ions and is more prone to oxidative dehydrogenation decomposition. Therefore, by adding the compound of general formula I to an electrolyte containing such a solvent, the oxidative decomposition of the solvent can be more significantly inhibited, and the cycle performance of the battery can be improved.

[0089] In some embodiments, the mass ratio of the compound of general formula I to the cyclic carbonate can be (0.05-2):(68-72).

[0090] By optimizing the mass ratio of the compound of general formula I to the cyclic carbonate, the solvent oxidative dehydrogenation can be effectively inhibited. If the amount of the compound of general formula I added is too small, the solvent dehydrogenation cannot be effectively inhibited. If the amount added is too much, the conductivity of the electrolyte will be deteriorated.

[0091] In some embodiments, the mass ratio of the compound of general formula I to the cyclic carbonate can be 0.05:72, 0.06:72, 0.07:72, 0.08:72, 0.09:72, 1:72, 1.1:72, 1.2:72, 1.3:72, 1.4:72, 1.5:72, 1.6:72, 1.7:72, 1.8:72, 1.9:72, 2:72, 0.05:68, 0.06:68, 0.07:68, 0.08:68, 0.09:68, 1:68, 1.1:68, 1.2:68, 1.3:68, 1.4:68, 1.5:68, 1.6:68, 1.7:68, 1.8:68, 1.9:68, or 2:68.

[0092] In some embodiments, the cyclic carbonate is selected from one or more of ethylene carbonate, propylene carbonate.

[0093] Ethylene carbonate and propylene carbonate are commonly used organic solvents in electrolyte, and the decomposition thereof can be effectively inhibited by adding the compound of general formula I in the electrolyte containing the same, and the cycle performance of the battery using the solvent system can be optimized.

[0094] In some embodiments, the mass fraction of the compound of general formula I in the electrolyte is 0.05%-1%.

[0095] In the design, by optimizing the addition amount of the compound of general formula I, the battery performance can be further improved. The addition amount of the compound of general formula I cannot be too small, otherwise the effect of inhibiting the oxidative dehydrogenation decomposition of the solvent will be weakened, and the addition amount thereof cannot be too large, otherwise the conductivity of the electrolyte will be seriously reduced.

[0096] In some embodiments, the mass fraction of the compound of general formula I in the electrolyte can be 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, or 1%. Alternatively, the mass fraction of the compound of general formula I in the electrolyte is 0.2%-1%, 0.2%-0.5%, 0.4%-0.8%, or 0.5%-1%.

[0097] The electrolyte further comprises an electrolyte salt.

[0098] As an example, the electrolyte salt can be selected from one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalato borate (LiDFOB), lithium bisoxalato borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalato phosphate (LiDFOP), and lithium tetrafluorooxalato phosphate (LiTFOP).

[0099] In some embodiments, the electrolyte further comprises an additive. For example, the additive can comprise a negative electrode film-forming additive, or a positive electrode film-forming additive, or an additive capable of improving certain properties of the battery, such as an additive capable of improving overcharge performance of the battery, an additive capable of improving high-temperature performance of the battery, an additive capable of improving low-temperature performance of the battery, and the like.

[0100] The second aspect of the present application provides a use of a compound of general formula I for inhibiting solvent decomposition in an electrolyte. The compound of general formula I has the following structure:

[0101]

[0102] wherein,

[0103] R 1 , R 2 , and R 3 are each independently selected from hydrogen, nitro, cyano, halogen, hydroxyl, substituted or unsubstituted alkoxy, substituted or unsubstituted alkylsulfonyl;

[0104] R 4 is selected from perfluoroalkyl, -BF3 - ;

[0105] M x+ is selected from sodium ion, potassium ion, zinc ion, and x is the valence state of the metal element;

[0106] In the case where R 4 is selected from perfluoroalkyl, m is 1 and n is 0;

[0107] In the case where R 4 is selected from BF3 - , m is 1 or 2 and n is 1.

[0108] The compound of general formula I of the present application can inhibit solvent decomposition in an electrolyte, effectively improving the cycle performance of a battery.

[0109] The third aspect of the present application provides a lithium ion battery, comprising a positive electrode sheet, a negative electrode sheet, a separator, and the electrolyte of the first aspect of the present application.

[0110] During the charging and discharging process of the battery, active ions are embedded and extracted between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, and plays a role of isolation. The electrolyte plays a role of ion conduction between the positive electrode sheet and the negative electrode sheet.

[0111] In the technical solution of the embodiment of the application, the lithium ion battery of the application has improved cycle performance because the electrolyte of the first aspect of the application is used.

[0112] In some embodiments, the positive electrode sheet comprises a lithium supplement agent. The lithium supplement agent is selected from one or more of Li2O, Li2O2, Li5FeO4, Li6CoO4, Li y Ni a Cu b O 0.5(2+y) wherein a+b=1, 1

[0113] Li2O, Li2O2, Li5FeO4, Li6CoO4, Li y Ni a Cu b O 0.5(2+y) The normal positive electrode lithium supplement agent has a much higher gram capacity than the traditional positive electrode material, and can increase the Li content in the active substance. During the first charging process, the surface of the negative electrode sheet will consume a large amount of lithium source due to the formation of a solid electrolyte interface (SEI) layer, resulting in a loss of circulatable lithium. By adding a positive electrode lithium supplement agent, the loss can be compensated for, and the charging and discharging capacity and service life of the secondary battery can be improved. However, the electrochemical activity of these lithium supplement agents is usually poor, and they need to be delithiated at a high voltage. At a high voltage, carbonate solvents are easily oxidized and dehydrogenated, and then hydrogen gas is generated. In addition, these lithium supplement agents release oxygen gas at the same time as delithiation, further enhancing the oxidation of the solvent. More seriously, hydrogen and oxygen mixed together have the risk of explosion, so the application of such lithium supplement agents is limited. By adding a compound of general formula I to the electrolyte, the decomposition of the electrolyte solvent is effectively inhibited, and the application scenarios of the above-mentioned lithium supplement agents are expanded.

[0114] In some embodiments, the positive electrode sheet further comprises a positive electrode active substance. The mass ratio of the lithium supplement agent to the total mass of the positive electrode active substance and the lithium supplement agent is (0.5-20):100.

[0115] The mass ratio of the lithium supplement agent affects the life and energy density of the battery. When the mass ratio of the lithium supplement agent is too low, the amount of lithium ions supplemented by the lithium supplement agent during the first charging process is too small to meet the consumption of active lithium ions during long-term cycling of the battery, and long life cannot be achieved. When the mass ratio of the lithium supplement agent is too high, the proportion of active materials used for later reversible cycling decreases, thereby affecting the energy density of the battery. Therefore, it is particularly important to select a suitable proportion of the lithium supplement agent to balance the life and energy density of the battery.

[0116] In some embodiments, the ratio of the mass of the lithium supplement agent to the total mass of the positive active material and the lithium supplement agent can be 0.5:100, 1:100, 2:100, 3:100, 4:100, 5:100, 6:100, 7:100, 8:100, 9:100, 10:100, 11:100, 12:100, 13:100, 14:100, 15:100, 16:100, 17:100, 18:100, 19:100, or 20:100. Alternatively, the ratio of the mass of the lithium supplement agent to the total mass of the positive active material and the lithium supplement agent can be (2-10):100 or (10-20):100.

[0117] In some embodiments, the average D50 particle size of the lithium supplement agent is 0.5-50 μm.

[0118] If the average D50 particle size of the lithium supplement material is too small, the positive electrode slurry is prone to agglomeration and gelation, the viscosity increases, and the solid content decreases. If the particle size is too large, the polarization of the lithium ion extraction reaction in the lithium supplement agent increases, thereby reducing the lithium supplement efficiency.

[0119] In some embodiments, the average D50 particle size of the lithium supplement agent can be 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm, 25 μm, 26 μm, 27 μm, 28 μm, 29 μm, 30 μm, 31 μm, 32 μm, 33 μm, 34 μm, 35 μm, 36 μm, 37 μm, 38 μm, 39 μm, 40 μm, 41 μm, 42 μm, 43 μm, 44 μm, 45 μm, 46 μm, 47 μm, 48 μm, 49 μm, or 50 μm. Alternatively, the average D50 particle size of the lithium supplement agent can be 0.5-30 μm, 0.5-20 μm, or 0.5-15 μm.

[0120] In some embodiments, the positive electrode tab includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. The positive electrode film layer includes a positive active material.

[0121] As an example, the positive electrode current collector has two surfaces opposite in the thickness direction thereof, and the positive electrode film layer is provided on either one or both of the two surfaces of the positive electrode current collector.

[0122] In some embodiments, the positive electrode current collector can employ a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base material such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0123] In some embodiments, the positive electrode active material can employ a positive electrode active material for a battery known in the art. As an example, the positive electrode active material can include at least one of a lithium-containing phosphate of an olivine structure, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material for a battery can also be used. These positive electrode active materials can be used alone only one or two or more can be used in combination. Among them, examples of the lithium transition metal oxide can include, but are not limited to, lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(also can be abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(also can be abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2(also can be abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2(also can be abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(also can be abbreviated as NCM811), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05O2) and modified compounds thereof, etc. Examples of the lithium-containing phosphate of olivine structure can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (which can also be referred to simply as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon.

[0124] In some embodiments, the positive electrode film layer further optionally includes a binder. As an example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0125] In some embodiments, the positive electrode film layer further optionally includes a conductive agent. As an example, the conductive agent can include at least one of super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0126] In some embodiments, the positive electrode tab can be prepared by dispersing components for preparing the positive electrode tab, such as the positive electrode active material, the lithium supplement agent, the conductive agent, the binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry, coating the positive electrode slurry on a positive electrode current collector, and subjecting the same to processes such as drying, cold pressing, etc. to obtain the positive electrode tab.

[0127] In some embodiments, the negative electrode tab includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector. The negative electrode film layer includes a negative electrode active material.

[0128] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0129] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. As a metal foil, for example, a copper foil can be used. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base layer (such as a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0130] In some embodiments, the negative active material can employ a negative active material for a battery known in the art. As an example, the negative active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from at least one of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative active material for a battery can also be used. These negative active materials can be used alone or in combination of two or more.

[0131] In some embodiments, the negative electrode film layer can further optionally include a binder. The binder can be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0132] In some embodiments, the negative electrode film layer can further optionally include a conductive agent. The conductive agent can be selected from at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0133] In some embodiments, the negative electrode film layer can further optionally include other auxiliary agents, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0134] In some embodiments, the negative electrode sheet can be prepared by dispersing components for preparing the negative electrode sheet, such as a negative active material, a conductive agent, a binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry, coating the negative electrode slurry on a negative current collector, and then drying, cold-pressing, and the like to obtain the negative electrode sheet.

[0135] The type of the separator film is not particularly limited in the present application, and any known porous structure separator film having good chemical stability and mechanical stability can be used.

[0136] In some embodiments, the material of the separator film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0137] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator film can be used to prepare an electrode assembly through a winding process or a stacking process.

[0138] In some embodiments, the lithium ion battery can comprise an outer package. The outer package can be used to encapsulate the electrode assembly and the electrolyte described above.

[0139] The fourth aspect of the present application provides a battery module comprising the lithium ion battery of the third aspect of the present application.

[0140] In the technical solution of the embodiments of the present application, since the electrolyte of the first aspect of the present application is adopted, the battery module of the present application has improved cycle performance.

[0141] The number of lithium ion batteries contained in the battery module can be one or more, and the specific number can be selected by a person skilled in the art according to the application and capacity of the battery module.

[0142] The fifth aspect of the present application provides a battery pack comprising the lithium ion battery of the third aspect of the present application or the battery module of the fourth aspect of the present application.

[0143] In the technical solution of the embodiments of the present application, since the electrolyte of the first aspect of the present application is adopted, the battery pack of the present application has improved cycle performance.

[0144] The number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by a person skilled in the art according to the application and capacity of the battery pack.

[0145] The sixth aspect of the present application provides a power consumption device comprising at least one of the secondary battery of the third aspect of the present application, the battery module of the fourth aspect of the present application, and the battery pack of the fifth aspect of the present application.

[0146] In the technical solution of the embodiments of the present application, since the electrolyte of the first aspect of the present application is adopted, the power consumption device of the present application has improved cycle performance.

[0147] The power consumption device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0148] Definitions and explanations of terms

[0149] The term "halogen" refers to F, Cl, Br or I.

[0150] The term "C1-C 20 The term "alkyl" is understood to preferably mean a straight-chain or branched saturated monovalent hydrocarbon group having 1 to 20 carbon atoms, preferably C1-C 12 alkyl, more preferably C1-C6alkyl. The term "C1-C 12"alkyl" should be understood to preferably refer to a straight-chain or branched saturated monovalent hydrocarbon group having 1 to 12 carbon atoms. The term "C1-C6 alkyl" should be understood to preferably refer to a straight-chain or branched saturated monovalent hydrocarbon group having 1, 2, 3, 4, 5, or 6 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl The group comprises methyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl or 1,2-dimethylbutyl or isomers thereof. In particular, the group has 1, 2, 3 or 4 carbon atoms (“C1-C4 alkyl”), such as methyl, ethyl, propyl, butyl, isopropyl, isobutyl, sec-butyl, tert-butyl; more particularly, the group has 1, 2 or 3 carbon atoms (“C1-C3 alkyl”), such as methyl, ethyl, n-propyl or isopropyl.

[0151] The term "alkoxy" refers to an alkyl group bonded by one oxygen atom. The term "C1-C"... 20 "Alkoxy" should be understood to preferably refer to a straight-chain or branched alkyloxy group having 1 to 20 carbon atoms, preferably C1-C. 12 Alkoxy, more preferably C1-C6 alkoxy. The term "C1-C6" is used to describe the alkoxy group. 12 "Alkoxy" should be understood as a straight-chain or branched alkyloxy group having 1 to 12 carbon atoms. The term "C1-C6 alkoxy" should be understood as a straight-chain or branched alkyloxy group having 1 to 6 carbon atoms.

[0152] The term "perfluoroalkyl" refers to an alkyl group in which all hydrogen atoms are replaced by fluorine atoms.

[0153] The term "alkylsulfonyl" refers to an alkyl group bonded by the group S(=O)2.

[0154] The present invention will be further illustrated below with reference to embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0155] Preparation of electrolyte

[0156] Example 1

[0157] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), organic solvent ethylene carbonate (EC) / ethylmethyl carbonate (EMC) was mixed uniformly in a volume ratio of 3 / 7, LiPF6 was dissolved in the organic solvent, and stirred uniformly; 4-methylsulfonylphenyl potassium trifluoroborate (indicated as additive in Table 1 below) was added to the above electrolyte, and stirred uniformly, to obtain an electrolyte, wherein the mass fraction of LiPF6 in the electrolyte was 12.5 wt%, the mass fraction of 4-methylsulfonylphenyl potassium trifluoroborate in the electrolyte was 0.05 wt%, and the mass ratio of 4-methylsulfonylphenyl potassium trifluoroborate to ethylene carbonate (EC) was 0.1:72.

[0158] Example 2

[0159] The method described in Example 1 was performed, except that the mass fraction of 4-methylsulfonylphenyl potassium trifluoroborate in the electrolyte was 0.2 wt%, and the mass ratio of 4-methylsulfonylphenyl potassium trifluoroborate to ethylene carbonate (EC) was 0.4:72.

[0160] Example 3

[0161] The method described in Example 1 was performed, except that the mass fraction of 4-methylsulfonylphenyl potassium trifluoroborate in the electrolyte was 0.4 wt%, and the mass ratio of 4-methylsulfonylphenyl potassium trifluoroborate to ethylene carbonate (EC) was 0.8:72.

[0162] Example 4

[0163] The method described in Example 1 was performed, except that the mass fraction of 4-methylsulfonylphenyl potassium trifluoroborate in the electrolyte was 0.5 wt%, and the mass ratio of 4-methylsulfonylphenyl potassium trifluoroborate to ethylene carbonate (EC) was 1:72.

[0164] Example 5

[0165] The method described in Example 1 was performed, except that the mass fraction of 4-methylsulfonylphenyl potassium trifluoroborate in the electrolyte was 0.8 wt%, and the mass ratio of 4-methylsulfonylphenyl potassium trifluoroborate to ethylene carbonate (EC) was 1.6:72.

[0166] Example 6

[0167] The method described in Example 1 was performed, except that the mass fraction of 4-methylsulfonylphenyl potassium trifluoroborate in the electrolyte was 1 wt%, and the mass ratio of 4-methylsulfonylphenyl potassium trifluoroborate to ethylene carbonate (EC) was 2:72.

[0168] Example 7

[0169] The procedure described in Example 4 was followed except that ethylene carbonate (EC) was replaced with propylene carbonate (PC) and the mass ratio of potassium 4-methylsulfonylphenyltrifluoroborate to propylene carbonate (PC) was 1 :68.

[0170] Example 8

[0171] The procedure described in Example 4 was followed except that potassium 4-methylsulfonylphenyltrifluoroborate was replaced with potassium (4-nitrophenyl)trifluoroborate.

[0172] Example 9

[0173] The procedure described in Example 4 was followed except that potassium 4-methylsulfonylphenyltrifluoroborate was replaced with potassium (4-methylphenyl)trifluoroborate.

[0174] Example 10

[0175] The procedure described in Example 4 was followed except that potassium 4-methylsulfonylphenyltrifluoroborate was replaced with potassium (4-methoxyphenyl)trifluoroborate.

[0176] Example 11

[0177] The procedure described in Example 4 was followed except that potassium 4-methylsulfonylphenyltrifluoroborate was replaced with potassium (3-nitrophenyl)trifluoroborate.

[0178] Example 12

[0179] The procedure described in Example 4 was followed except that potassium 4-methylsulfonylphenyltrifluoroborate was replaced with potassium (4-cyanophenyl)trifluoroborate.

[0180] Example 13

[0181] The procedure described in Example 4 was followed except that potassium 4-methylsulfonylphenyltrifluoroborate was replaced with potassium (3-carboxy-5-nitrophenyl)trifluoroborate.

[0182] Example 14

[0183] The procedure described in Example 4 was followed except that potassium 4-methylsulfonylphenyltrifluoroborate was replaced with 1-(methylsulfonyl)-4-(trifluoromethyl)benzene.

[0184] Example 15

[0185] The procedure described in Example 4 was followed except that potassium 4-methylsulfonylphenyltrifluoroborate was replaced with trifluoromethylbenzene.

[0186] Example 16

[0187] The method described in Example 4 was followed, except that potassium 4-methylsulfonylphenyltrifluoroborate was replaced by potassium phenyltrifluoroborate.

[0188] Comparative Example 1

[0189] The method described in Example 4 was followed, except that potassium 4-methylsulfonylphenyltrifluoroborate was not used.

[0190] Comparative Example 2

[0191] The method described in Example 4 was followed, except that the mass fraction of potassium 4-methylsulfonylphenyltrifluoroborate in the electrolyte was 3% by weight, and the mass ratio of potassium 4-methylsulfonylphenyltrifluoroborate to ethylene carbonate (EC) was 6:72.

[0192] Lithium ion batteries were prepared according to the general preparation method below using the electrolytes prepared in the above examples and comparative examples.

[0193] Preparation of lithium ion battery

[0194] Positive electrode sheet preparation:

[0195] Li5FeO4 lithium supplement with an average D50 particle size of 10 μm, lithium iron phosphate material, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) were mixed in a weight ratio of 5:92:1:2 in an N-methylpyrrolidone (NMP) solvent system to obtain a positive electrode slurry. The positive electrode slurry was then uniformly coated on a positive electrode current collector, followed by drying, cold pressing, and slitting to obtain a positive electrode sheet.

[0196] Negative electrode sheet preparation:

[0197] The active material artificial graphite, conductive agent carbon black, binder styrene butadiene rubber (SBR), and thickening agent sodium hydroxymethyl cellulose (CMC) were dissolved in deionized water in a weight ratio of 97.2:0.8:0.8:1.2, and the mixture was uniformly mixed to prepare a negative electrode slurry. The negative electrode slurry was uniformly coated on a negative electrode current collector copper foil one or more times, and the negative electrode sheet was obtained by drying, cold pressing, and slitting.

[0198] Separator film:

[0199] A polypropylene film was used as the separator film.

[0200] Lithium ion battery preparation:

[0201] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in sequence and wound to obtain an electrode assembly; the electrode assembly is placed in an outer package, the prepared electrolyte is added, and after processes such as packaging, standing, formation, and aging, a lithium ion battery is obtained.

[0202] To prove the influence of the average D50 particle size and the amount of the Li5FeO4 lithium supplement on the battery performance, the following examples and comparative examples are given.

[0203] Example 17

[0204] The lithium ion battery is prepared according to the above general method using the electrolyte prepared in Example 4, except that the average D50 particle size of the Li5FeO4 lithium supplement is 5 μm.

[0205] Example 18

[0206] The lithium ion battery is prepared according to the above general method using the electrolyte prepared in Example 4, except that the average D50 particle size of the Li5FeO4 lithium supplement is 15 μm.

[0207] Example 19

[0208] The lithium ion battery is prepared according to the above general method using the electrolyte prepared in Example 4, except that the average D50 particle size of the Li5FeO4 lithium supplement is 30 μm.

[0209] Example 20

[0210] The lithium ion battery is prepared according to the above general method using the electrolyte prepared in Example 4, except that the average D50 particle size of the Li5FeO4 lithium supplement is 50 μm.

[0211] Example 21

[0212] The lithium ion battery is prepared according to the above general method using the electrolyte prepared in Example 4, except that the weight ratio of the Li5FeO4 lithium supplement to the lithium iron phosphate material is 0.5:96.5.

[0213] Example 22

[0214] The lithium ion battery is prepared according to the above general method using the electrolyte prepared in Example 4, except that the weight ratio of the Li5FeO4 lithium supplement to the lithium iron phosphate material is 10:87.

[0215] Example 23

[0216] The lithium ion battery is prepared according to the above general method using the electrolyte prepared in Example 4, except that the weight ratio of the Li5FeO4 lithium supplement to the lithium iron phosphate material is 19:78.

[0217] Comparative Example 3

[0218] A lithium ion battery was prepared according to the general method described above using the electrolyte prepared in Example 4, except that the average D50 particle size of the Li5FeO4lithium supplement was 100 pm.

[0219] Comparative Example 4

[0220] A lithium ion battery was prepared according to the general method described above using the electrolyte prepared in Example 4, except that no Li5FeO4lithium supplement was used.

[0221] Comparative Example 5

[0222] A lithium ion battery was prepared according to the general method described above using the electrolyte prepared in Example 4, except that no potassium 4-methylsulfonylphenyl trifluoroborate was used, and no Li5FeO4lithium supplement was used.

[0223] Conductivity test of electrolyte

[0224] 1) Turn on the conductivity meter (Shanghai Raygen, model DDSJ-318) and preheat for 30 min, and calibrate the instrument; 2) Pour 30 mL of the electrolyte sample to be tested into a dry and clean plastic centrifuge tube, and place it in a constant temperature oven at 25°C for 30 min; 3) Use a dust-free paper to dry the moisture on the electrode (DJS-1C type platinum black electrode), and place the electrode vertically into the uniform sample to be tested, click “measurement” on the interface of the conductivity meter, and read the value after the value is stable, repeat three times and take the average value, which is the conductivity of the electrolyte. The test results are shown in Table 1.

[0225] Battery performance test

[0226] Battery capacity retention rate test:

[0227] Taking Example 1 as an example, the battery capacity retention rate test process is as follows: at 60°C, the battery corresponding to Example 1 is charged at 1 / 3C constant current to the terminal voltage, and then charged at constant voltage to 0.05C, and then left for 5 min, and then discharged at 1 / 3C to the discharge cut-off voltage, and the obtained capacity is recorded as the initial capacity C0. Repeat the above steps for the same battery, and record the discharge capacity Cn of the battery after the nth cycle, then the battery capacity retention rate Pn = Cn / C0*100% after each cycle. In this test process, the first cycle corresponds to n = 1, the second cycle corresponds to n = 2, and the 500th cycle corresponds to n = 500. The battery capacity retention rate data corresponding to Example 1 in Table 1 is the data measured after 500 cycles under the above test conditions, i.e. the value of P500. The test process of other examples and comparative examples is the same as above. The test results are shown in Table 1 below.

[0228] Table 1

[0229]

[0230]

[0231]

[0232]

[0233] As can be seen from Examples 1-6, as the amount of the compound of general formula I increases, the conductivity of the electrolyte gradually decreases, while the capacity retention rate of the lithium ion battery corresponding to Examples 1-6 shows a trend of first increasing and then decreasing, therefore, it is necessary to control the amount of the compound of general formula I within a suitable range to ensure that the electrolyte has good conductivity and the battery has a high capacity retention rate. When the mass fraction of the compound of general formula I in the electrolyte is 0.5% by weight, the effect is best.

[0234] As can be seen by comparing Example 4 and Comparative Examples 1-2, the electrolyte of Comparative Example 1 does not add the compound of general formula I, and the capacity retention rate of the lithium ion battery corresponding thereto is significantly lower than that of the battery corresponding to Example 4. The electrolyte of Comparative Example 2 adds an excessive amount of the compound of general formula I, and the capacity retention rate of the lithium ion battery corresponding thereto is higher, but the conductivity of the electrolyte is significantly reduced.

[0235] As can be seen by comparing Examples 17-20 and Comparative Example 3, as the average D50 particle size of the lithium supplementing agent increases, the capacity retention rate of the lithium ion battery corresponding thereto gradually decreases, and when the particle size is too large, the capacity retention rate is significantly reduced, therefore, it is necessary to control the average D50 particle size of the lithium supplementing agent within a suitable range.

[0236] As can be seen by comparing Example 4 and Comparative Example 4, the positive electrode sheet of Comparative Example 4 does not add the lithium supplementing agent, and the capacity retention rate of the lithium ion battery corresponding thereto is significantly lower than that of the lithium ion battery corresponding to Example 4. It can be seen that the addition of the lithium supplementing agent has an important influence on the capacity retention rate. In addition, as can be seen from Example 4 and Examples 21-23, as the amount of the lithium supplementing agent increases, the capacity retention rate of the lithium ion battery corresponding thereto gradually increases. However, the amount of the lithium supplementing agent should not be too large, so as to avoid causing the proportion of active materials used for later reversible cycles to decrease, thereby being detrimental to the energy density of the battery.

[0237] Comparative Example 5 serves as a blank control group, which does not add the compound of general formula I and the lithium supplementing agent, and the capacity retention rate of the lithium ion battery corresponding thereto is significantly low.

[0238] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical scope disclosed by the present application, which can be easily thought by those skilled in the art, should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A lithium-ion battery, characterized in that, It includes a positive electrode, a negative electrode, a separator, and an electrolyte; wherein the electrolyte includes a solvent and 1-(methanesulfonyl)-4-(trifluoromethyl)benzene; The positive electrode includes a lithium replenishing agent, which is selected from Li₂O, Li₂O₂, Li₅FeO₄, Li₆CoO₄, and Li₂O. y Ni a Cu b O 0.5(2+y) One or more of the following, where a+b=1, 1 <y<3。 2. The lithium-ion battery according to claim 1, characterized in that, The positive electrode sheet also includes a positive electrode active material, and the mass ratio of the lithium replenishing agent to the total mass of the positive electrode active material and the lithium replenishing agent is (0.5~20):

100.

3. The lithium-ion battery according to claim 1 or 2, characterized in that, The average D50 particle size of the lithium supplement is 0.5-50 μm.

4. The lithium-ion battery according to claim 1, characterized in that, The solvent includes cyclic carbonates.

5. The lithium-ion battery according to claim 4, characterized in that, The cyclic carbonate is selected from one or more of ethylene carbonate and propylene carbonate.

6. The lithium-ion battery according to claim 1 or 2, characterized in that, The mass fraction of 1-(methanesulfonyl)-4-(trifluoromethyl)benzene in the electrolyte is 0.05%-1%.

7. A battery module, characterized in that, The lithium-ion battery includes any one of claims 1-6.

8. A battery pack, characterized in that, Includes the lithium-ion battery according to any one of claims 1-6 or the battery module according to claim 7.

9. An electrical device, characterized in that, It includes at least one of the lithium-ion battery according to any one of claims 1-6, the battery module according to claim 7, and the battery pack according to claim 8.

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