Electrolyte and lithium ion battery

Abstract

The invention provides an electrolyte and a lithium ion battery. The electrolyte comprises a non-aqueous solvent, a lithium salt and an electrolyte additive; the electrolyte additive has the following structural formula: R1-O-R2, and R1 and / or R2 are / is independently selected from a fluoroacyl group. According to the electrolyte disclosed by the invention, by adding the specific electrolyte additive, stable solid electrolyte layers can be formed on the surfaces of the positive electrode active material and the negative electrode active material, so that further oxygenolysis of the electrolyte under high voltage potential and further reductive decomposition of the electrolyte under low potential are inhibited; therefore, the cycle life of the battery is prolonged, and the high energy density of the battery is kept.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion batteries and relates to an electrolyte and a lithium ion battery. Background Art

[0002] Lithium-ion batteries, with their high operating voltage, lightweight design, low self-discharge rate, and environmentally friendly characteristics, have become an important energy carrier in portable electronic devices and new energy vehicles. As a core component of the battery system, the electrolyte plays a key role in ion transport and, together with the positive and negative electrode materials and separators, constitutes the four core material systems of the battery. Modern electrolyte systems are typically composed of a precisely proportioned combination of high-purity organic solvents, lithium salt electrolytes, and functional additives. Their performance directly affects the battery's energy density, cycle life, and safety characteristics.

[0003] In recent years, with the promotion of lithium-ion battery applications, people's demand for lithium-ion battery energy density has become increasingly higher. There are two ways to improve the energy density of lithium-ion batteries: one is to improve the performance of positive and negative electrode materials and the battery structure, and the other is to use positive electrode materials with high charge cutoff potential, which is one of the important ways to improve the energy density of lithium-ion batteries. The first method is often long and costly, while the second method is convenient, efficient, and low-cost, making it an important way to improve the energy density of lithium-ion batteries.

[0004] However, the main reason why high-voltage positive electrode materials are difficult to commercialize is that the current commercial electrolytes cannot match high-voltage positive electrode materials. That is, when working above 4.5V, the electrolyte is prone to oxidative decomposition on the surface of the positive electrode material, causing battery performance to deteriorate, limiting the development and application of high-voltage positive electrode material battery systems.

[0005] Therefore, how to solve the problem of oxidative decomposition when the electrolyte is matched with a high-voltage positive electrode is a topic that urgently needs to be explored. Summary of the Invention

[0006] In response to the shortcomings of the prior art, the present invention aims to provide an electrolyte and a lithium-ion battery. The electrolyte of the present invention, through the addition of specific electrolyte additives, can oxidatively decompose on the surface of the positive electrode active material to form a stable solid electrolyte layer rich in inorganic components, inhibiting further oxidative decomposition of the electrolyte at high voltage potentials. Simultaneously, the electrolyte can be preferentially reduced at the negative electrode to form a solid electrolyte layer rich in inorganic components, inhibiting further reductive decomposition of the electrolyte, thereby extending the battery's cycle life and maintaining its high energy density.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides an electrolyte comprising a non-aqueous solvent, a lithium salt, and an electrolyte additive; the electrolyte additive has the following structural formula:

[0009] R1-O-R2,

[0010] Wherein, the R1 and / or the R2 are each independently selected from a fluoroacyl group.

[0011] It should be noted that R1 and R2 in the present invention can both be selected from fluoroacyl groups, or one of them can be selected from fluoroacyl groups. When one is selected, the remaining group is not limited in the present invention and will not affect the selection of group types for normal use of the electrolyte. The present invention is applicable to all of them, such as halogen groups, -H or substituted or unsubstituted C1-C3 optional alkyl groups, etc.

[0012] The oxidation potential of conventional electrolyte solvents and additives is usually lower than 4.3V (vs. Li+ / Li). When used in high-voltage systems, it far exceeds the antioxidant limit of the electrolyte. At the same time, under high voltage, the structural stability of the positive electrode active material deteriorates, and the transition metal elements it contains are easily dissolved and migrate to the negative electrode side with the electrolyte and precipitate, causing damage to the solid electrolyte layer on the negative electrode side, aggravating the reduction and decomposition of the electrolyte, and leading to a sharp deterioration of battery performance.

[0013] Therefore, the present invention adds an electrolyte additive with reducing electrophilic properties to the electrolyte, and uses it in the electrolyte system of non-aqueous solvent. On the one hand, it can form a close pairing with the nucleophilic site in the high-voltage positive electrode active material, and accept electrons and lithium ions from the nucleophilic site, thereby generating an electrochemical reaction, forming an oxidation-resistant organic-inorganic composite passivation layer on the surface of the positive electrode active material, and inhibiting further oxidative decomposition of the electrolyte; on the other hand, the strong electron-withdrawing effect of fluorine causes it to be preferentially reduced on the negative electrode side, forming a dense passivation layer, and preventing the reduction decomposition of the electrolyte on the negative electrode side. More importantly, the electrolyte additive uses a fluorinated acyl group, which has a low carbon content and the fluorine therein is easily released, which can form an inorganic-rich solid electrolyte interface layer mainly composed of LiF and Li2O, which can not only more effectively inhibit further redox decomposition of the electrolyte, but also has a lower Li + The diffusion energy barrier prolongs the cycle life of the battery and maintains the high energy density of the battery.

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0015] When one of R1 and R2 in the present invention is selected from a fluoroacyl group, it is further preferred that the remaining group is selected from a fluorine-containing group, such as a fluorine group, which is more conducive to forming a stable solid electrolyte layer mainly composed of LiF.

[0016] Preferably, the fluoroacyl group is selected from Any one of .

[0017] In the present invention, the above-mentioned acyl fluoride group, sulfuryl fluoride group or phosphoryl fluoride group is further preferred, which can better play the role of the additive in forming a stable passivation layer on the positive and negative electrode sides, thereby inhibiting further redox decomposition of the electrolyte.

[0018] Preferably, the electrolyte additive has a structural formula as shown in any one of Formulas I-VI:

[0019]

[0020] It should be noted that the electrolyte additive in the present invention can be directly synthesized by conventional synthesis methods, or can be purchased within a reasonable range. There is no need to specifically limit or explain the specific synthesis process in detail. Those skilled in the art can make adaptive selections and adjustments based on actual needs.

[0021] For example, the substance of structural formula I can be purchased directly, and the substance of structural formula II can be obtained by replacing the CF3 group in trifluoroacetic anhydride with fluorine.

[0022] Preferably, said R1 and said R2 are both selected from fluoroacyl groups.

[0023] In the present invention, when both R1 and R2 are selected from fluoroacyl groups, there is an advantage of forming a solid electrolyte layer richer in LiF and Li2O, further improving the stability of the electrolyte during the battery charge and discharge process, thereby exhibiting better battery performance.

[0024] Preferably, based on the total mass of the non-aqueous solvent and the lithium salt as 100%, the added mass of the electrolyte additive is 0.1% to 5%, preferably 0.2% to 2%, for example, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, etc., but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0025] It can be understood that the mixture of the non-aqueous solvent and the lithium salt in the present invention is the basic electrolyte.

[0026] For the present invention, a suitable amount of electrolyte additive can produce a better effect. Regulating the electrolyte additive to 0.1% to 5% of the total mass of the electrolyte is conducive to forming a stable interface passivation layer on the positive and negative electrode sides; and further preferably in the range of 0.2 to 2%, further optimizing the stability and ion conductivity of the passivation layer.

[0027] Preferably, the non-aqueous solvent includes a carbonate solvent.

[0028] It is understandable that the specific material types of the non-aqueous solvent of the present invention are further limited, and the selection of non-aqueous solvents is a conventional technical solution. The present invention is applicable to all conventional non-aqueous solvent types that can be used in electrolyte systems.

[0029] For example, the carbonate solvent includes but is not limited to at least one of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) or diethyl carbonate (DEC).

[0030] In addition, the non-aqueous solvent in the present invention may also be a carboxylate solvent, such as ethyl acetate, ethyl propionate, methyl butyrate, cyclic carboxylate or fluorocarboxylate.

[0031] Preferably, the concentration of the lithium salt in the electrolyte is 0.8 to 1.5 mol / L, for example, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L or 1.5 mol / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] It should be noted that the specific types of lithium salts in the present invention are all conventional technical solutions, and those skilled in the art can make adaptive selections and adjustments based on actual needs.

[0033] For example, the lithium salt includes but is not limited to at least one of lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0034] Furthermore, the present invention can also add lithium salt additives, such as at least one of lithium difluorophosphate, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium difluorobis(oxalatophosphate), lithium tetrafluorooxalatophosphate, lithium trioxalatophosphate, lithium fluoride or lithium oxalate, to further improve the electrochemical properties of the electrolyte.

[0035] In a second aspect, the present invention provides a method for preparing the electrolyte according to the first aspect, the preparation method comprising:

[0036] The electrolyte is obtained by mixing a non-aqueous solvent, the electrolyte additive described in the first aspect, and a lithium salt.

[0037] The present invention does not impose any special restrictions on the specific preparation process of the electrolyte in the first aspect. The corresponding electrolyte can be obtained by using a conventional mixing method without the need for a complicated processing process, and is suitable for large-scale production processes.

[0038] In a second aspect, the present invention further provides a lithium-ion battery, comprising the electrolyte as described in the first aspect.

[0039] Preferably, the lithium-ion battery further comprises a positive electrode, a negative electrode and a separator.

[0040] Preferably, the positive electrode active material in the positive electrode includes a high working voltage positive electrode active material, and the high voltage is a voltage ≥4.5V, such as 4.5V, 4.55V, 4.6V, 4.65V, 4.7V, 4.75V or 4.8V, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] The lithium-ion battery in the present invention is a liquid lithium-ion battery and is more suitable for use at a high voltage, that is, for use at an operating voltage of ≥4.5V.

[0042] Furthermore, the high working voltage positive electrode active material described in the present invention includes any one or a combination of at least two of nickel-cobalt-manganese ternary positive electrode material (NCM), spinel nickel manganese oxide positive electrode material (LNMO), lithium cobalt oxide positive electrode material (LCO) or lithium-rich manganese-based solid solution positive electrode material (LMR).

[0043] In addition, the specific raw materials and preparation process of the lithium-ion battery of the present invention are conventional technical means, and those skilled in the art can make adaptive selections and adjustments based on actual needs, as long as the purpose of the present invention can be achieved.

[0044] Optionally, the positive electrode includes a positive electrode current collector and a positive electrode active material layer located on at least one side of the positive electrode current collector. In addition to the positive electrode active material, the positive electrode active material layer may also include a positive electrode conductor and / or a positive electrode binder.

[0045] Alternatively, the negative electrode may be a lithium metal negative electrode or a non-lithium metal negative electrode. The non-lithium metal negative electrode includes a negative electrode current collector and a negative electrode active material layer located on at least one surface of the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material and may further include a negative electrode conductive agent and / or a negative electrode binder.

[0046] Optionally, the negative electrode active material includes at least one of a graphite negative electrode material, a silicon-oxygen negative electrode material, a silicon-carbon negative electrode material or a lithium titanate negative electrode material.

[0047] Optionally, the diaphragm may be a pure polymer diaphragm or a functional diaphragm, such as a combined membrane layer of a base membrane and a functional coating. The specific functional coating can be adaptively selected and adjusted based on existing technologies.

[0048] Optionally, the polymer film or base film in the separator may be at least one of a polypropylene (PP) film, a polyethylene (PE) film, a PE / PP film, a PE / PP / PE film, or a PP / PE / PP film.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] The present invention adds an electrolyte additive with reducing electrophilic properties to the electrolyte and uses it in a non-aqueous solvent electrolyte system. On the one hand, it can form a close pairing with the nucleophilic sites in the high-voltage positive electrode active material and accept electrons and lithium ions from the nucleophilic sites, thereby generating an electrochemical reaction and forming an oxidation-resistant organic-inorganic composite passivation layer on the surface of the positive electrode active material, inhibiting further oxidative decomposition of the electrolyte; on the other hand, the strong electron-withdrawing effect of fluorine causes it to be preferentially reduced on the negative electrode side, forming a dense passivation layer, which prevents the reductive decomposition of the electrolyte on the negative electrode side. More importantly, the electrolyte additive uses a fluorinated acyl group, which has a low carbon content and the fluorine therein is easily released, which can form an inorganic-rich solid electrolyte interface layer mainly composed of LiF and Li2O. It can not only more effectively inhibit further redox decomposition of the electrolyte, but also has a lower Li+ diffusion energy barrier, thereby extending the cycle life of the battery and retaining the high energy density of the battery. DETAILED DESCRIPTION

[0051] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0052] 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 application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions.

[0053] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0054] Example 1

[0055] This embodiment provides an electrolyte, which includes a non-aqueous solvent, a lithium salt, and an electrolyte additive;

[0056] The non-aqueous solvent includes EC:EMC:DEC in a volume ratio of 3:4:3, respectively, and the lithium salt is lithium hexafluorophosphate with a concentration of 1 mol / L in the electrolyte.

[0057] The electrolyte additive has a structural formula shown in Formula I, and based on the total mass of the non-aqueous solvent and the lithium salt being 100%, the added mass of the electrolyte additive is 1%:

[0058]

[0059] The preparation method of the electrolyte is as follows:

[0060] In a glove box, an appropriate amount of lithium salt was weighed and dissolved in a carbonate mixed solvent to prepare 100 g of a basic electrolyte, wherein the basic electrolyte was composed of 1 mol / L LiPF6 and EC:EMC:DEC in a volume ratio of 3:4:3, respectively. 1 g of the electrolyte additive provided by Formula I was added to the above basic electrolyte and stirred until completely dissolved to obtain a high-voltage electrolyte.

[0061] Example 2

[0062] The difference between this embodiment and embodiment 1 is that in this embodiment, the total mass of the non-aqueous solvent and the lithium salt is 100%, and the mass of the electrolyte additive added is 0.2%.

[0063] In the preparation method, the amount of electrolyte additive added is adaptively adjusted to 0.2 g.

[0064] The other conditions are the same as those in Example 1.

[0065] Example 3

[0066] The difference between this embodiment and embodiment 1 is that in this embodiment, the total mass of the non-aqueous solvent and the lithium salt is 100%, and the mass of the electrolyte additive added is 2%.

[0067] In the preparation method, the amount of electrolyte additive added is adaptively adjusted to 2 g.

[0068] The other conditions are the same as those in Example 1.

[0069] Example 4

[0070] The difference between this embodiment and embodiment 1 is that in this embodiment, the total mass of the non-aqueous solvent and the lithium salt is 100%, and the mass of the electrolyte additive added is 5%.

[0071] In the preparation method, the amount of electrolyte additive added is adaptively adjusted to 5g.

[0072] The other conditions are the same as those in Example 1.

[0073] Example 5

[0074] The difference between this embodiment and embodiment 1 is that the electrolyte additive in this embodiment has the structural formula shown in formula II:

[0075]

[0076] The other conditions are the same as those in Example 1.

[0077] Example 6

[0078] The difference between this embodiment and embodiment 1 is that the electrolyte additive in this embodiment has the structural formula shown in formula IV:

[0079]

[0080] The other conditions are the same as those in Example 1.

[0081] Example 7

[0082] The difference between this embodiment and embodiment 1 is that the electrolyte additive in this embodiment has an additive represented by formula III:

[0083]

[0084] The other conditions are the same as those in Example 1.

[0085] Example 8

[0086] The difference between this embodiment and embodiment 1 is that the electrolyte additive in this embodiment has the structural formula shown in Formula VII:

[0087]

[0088] The other conditions are the same as those in Example 1.

[0089] Example 9

[0090] The difference between this embodiment and embodiment 1 is that in this embodiment, the total mass of the non-aqueous solvent and the lithium salt is 100%, and the mass of the electrolyte additive added is 8%.

[0091] In the preparation method, the amount of electrolyte additive added is adaptively adjusted to 8 g.

[0092] The other conditions are the same as those in Example 1.

[0093] Comparative Example 1

[0094] The difference between this comparative example and Example 1 is that the electrolyte in this comparative example does not contain electrolyte additives.

[0095] In the preparation method, no electrolyte additives are added.

[0096] The other conditions are the same as those in Example 1.

[0097] Comparative Example 2

[0098] The difference between this comparative example and Example 1 is that the electrolyte additive in this comparative example is lithium difluorophosphate.

[0099] The other conditions are the same as those in Example 1.

[0100] Comparative Example 3

[0101] The difference between this comparative example and Example 1 is that the electrolyte additive in this comparative example is methylsulfonyl fluoride, and the structural formula is:

[0102]

[0103] The other conditions are the same as those in Example 1.

[0104] [Battery preparation and performance testing]

[0105] ①Battery preparation:

[0106] (1) Preparation of positive electrode sheet

[0107] The spinel lithium nickel manganese oxide positive electrode material LiNi 0.5 Mn 1.5 O4 (LNMO), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 90:5:5, and an appropriate amount of N-methylpyrrolidone (NMP) is added as a solvent. The mixture is stirred and dispersed evenly. The mixed solution is scraped onto aluminum foil and dried at 90°C to obtain a porous positive electrode sheet for use.

[0108] (2) Preparation of negative electrode sheet

[0109] Graphite, conductive carbon black (Super P), hydroxymethyl cellulose binder, and styrene-butadiene rubber latex binder were mixed in a weight ratio of 92:3:2:3. Deionized water was added as a solvent and stirred to disperse the mixture evenly. The mixed solution was then applied by knife coating onto copper foil and dried at 70°C to obtain a porous negative electrode sheet for later use.

[0110] (3) Battery Assembly: A polyethylene (PE) separator with a thickness of 12 μm was selected and laminated in a Z-shaped pattern. The separator had a positive electrode and a negative electrode on either side, with the separator between the electrodes. After lamination, the tabs were welded and then placed in an aluminum-plastic film. The top and side seals were performed, and the electrolytes provided in Examples 1-9 and Comparative Examples 1-3 were injected. The cells were then packaged and soaked at room temperature for 24 hours and at high temperature for 12 hours, respectively, to obtain the corresponding batteries of Examples 1-9 and Comparative Examples 1-3.

[0111] ②Performance testing

[0112] The batteries provided in Examples 1-9 and Comparative Examples 1-3 were subjected to performance tests, specifically:

[0113] (a) Cycling tests were conducted on a Xinwei test system. The battery adopted constant current-constant potential charge / constant current discharge (CC-CV / DC) mode. The charge and discharge cut-off voltages were 4.7 V and 3.0 V, respectively. The cut-off current of the constant potential was 0.05 C. The battery rested for 5 minutes between each charge and discharge cycle. The battery was cycled at a charge and discharge rate of 0.2 / 1.0 C at 25°C. After 200 cycles, the corresponding capacity retention rate was obtained. The specific results are shown in Table 1.

[0114] (b) Irreversible capacity loss

[0115] The cycle test was carried out on the Xinwei test system. The battery adopted constant current-constant potential charge / constant current discharge (CC-CV / DC) mode. The charge and discharge cut-off voltages were 4.7V and 3.0V respectively. The cut-off current of the constant potential was 0.05C. The fresh battery was charged and discharged once at a charge and discharge rate of 0.05C. The discharge capacity was recorded as Q fresh The battery after 200 cycles is also charged and discharged at a charge and discharge rate of 0.05C, and the discharge capacity is recorded as Q EOL , then the irreversible capacity loss R after 200 cycles of the battery is: R 不可逆容量损失 =(Q fresh- Q EOL ) / Q fresh ×100%. The corresponding capacity retention rate was obtained, and the specific results are shown in Table 1.

[0116] Table 1

[0117]

[0118]

[0119] From Table 1 we can conclude that:

[0120] In the electrolyte provided by the present invention, the electrolyte additive must have R1-O-R2 and the R1 and / or the R2 must be independently selected from fluoroacyl groups, so that it can play the role of forming a stable solid electrolyte layer rich in inorganic components while undergoing redox decomposition on the surface of the positive and negative active materials, thereby extending the cycle life of the battery and retaining the high energy density of the battery. In addition, the irreversible capacity loss of the battery is also greatly improved, ensuring the stability of the positive and negative electrode interfaces.

[0121] In summary, the present invention adds an electrolyte additive with reducing electrophilic properties to the electrolyte, and uses it in a non-aqueous solvent electrolyte system. On the one hand, it can form a tight pairing with the nucleophilic site in the high-voltage positive electrode active material, and accept electrons and lithium ions from the nucleophilic site, thereby generating an electrochemical reaction, forming an oxidation-resistant organic-inorganic composite passivation layer on the surface of the positive electrode active material, and inhibiting further oxidative decomposition of the electrolyte; on the other hand, the strong electron-withdrawing effect of fluorine causes it to be preferentially reduced on the negative electrode side, forming a dense passivation layer, and preventing the reductive decomposition of the electrolyte on the negative electrode side. More importantly, the electrolyte additive uses a fluorinated acyl group, which has a low carbon content and the fluorine therein is easily released, which can form an inorganic-rich solid electrolyte interface layer mainly composed of LiF and Li2O, which can not only more effectively inhibit further redox decomposition of the electrolyte, but also has a lower Li + Diffusion energy barrier. The electrolyte provided by the present invention forms a more stable passivation layer on the positive and negative electrode sides, which can reduce the loss of active lithium and reduce irreversible capacity loss, thereby extending the cycle life of the battery.

[0122] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. An electrolyte, characterized in that: The electrolyte includes a non-aqueous solvent, a lithium salt and an electrolyte additive; the electrolyte additive has the following structural formula: R1—O—R2, Wherein, the R1 and / or the R2 are each independently selected from a fluoroacyl group.

2. The electrolyte according to claim 1, characterized in that The fluoroacyl group is selected from Any one of .

3. The electrolyte according to claim 2, characterized in that The electrolyte additive has a structural formula as shown in any one of Formulas I-VI:

4. The electrolyte according to claim 1 or 2, characterized in that The R1 and R2 are both selected from fluoroacyl groups.

5. The electrolyte according to claim 1, characterized in that Based on the total mass of the non-aqueous solvent and the lithium salt being 100%, the added mass of the electrolyte additive is 0.1% to 5%, preferably 0.2% to 2%.

6. The electrolyte according to claim 1, characterized in that The non-aqueous solvent includes a carbonate solvent.

7. The electrolyte according to claim 1, characterized in that The concentration of the lithium salt in the electrolyte is 0.8 to 1.5 mol / L.

8. A lithium ion battery, characterized in that: The lithium-ion battery comprises the electrolyte according to any one of claims 1 to 7.

9. The lithium-ion battery according to claim 8, characterized in that The lithium-ion battery further includes a positive electrode, a negative electrode and a separator.

10. The lithium-ion battery according to claim 9, characterized in that The positive electrode active material in the positive electrode includes a high working voltage positive electrode active material, and the high voltage is a voltage ≥4.5V.

Images