Electrolyte and application thereof

Abstract

The invention provides an electrolyte and application thereof. The electrolyte at least comprises the following components: a lithium salt; a solvent; the additive comprises a first additive and a second additive, the structural general formula of the first additive is # imgabs0 #, R1 and R2 are respectively and independently selected from one of H, C1-6 alkyl substituted or unsubstituted by a first substituent, C2-6 alkenyl substituted or unsubstituted by a second substituent and C3-6 cycloalkyl substituted or unsubstituted by a third substituent, and R1 and R2 are respectively and independently selected from one of H, C1-6 alkyl substituted or unsubstituted by the first substituent, C3-6 alkenyl substituted or unsubstituted by the second substituent and C3-6 cycloalkyl substituted or unsubstituted by the third substituent. The first substituent group, the second substituent group and the third substituent group are independently selected from alkyl or halogen atoms, and the second additive comprises lithium nitrate. According to the electrolyte and the application thereof provided by the invention, the growth of lithium dendrites can be effectively inhibited, the safety and the cycle performance of a battery are improved, and the impedance of the battery is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power batteries, and in particular to an electrolyte and applications thereof. Background Art

[0002] As a representative of the new generation of high-energy storage technology, lithium metal batteries have the advantages of ultra-high energy density and low self-discharge rate, leading the innovation direction in the field of energy storage. However, in the actual application of lithium metal batteries, the formation of lithium dendrites will not only reduce battery efficiency, but also cause battery short circuit or even explosion, which will greatly reduce the safety of the battery and seriously restrict the further development and application of the battery. Summary of the invention

[0003] The present invention provides an electrolyte and an application thereof. The electrolyte provided by the present invention and the application thereof can effectively inhibit the growth of lithium dendrites, improve the safety and cycle performance of the battery, and reduce the impedance of the battery.

[0004] In order to solve the above technical problems, the present invention provides an electrolyte comprising at least the following components:

[0005] Lithium salts;

[0006] Solvents; and

[0007] The additive comprises a first additive and a second additive, and the general structural formula of the first additive is: Wherein, R1 and R2 are each independently selected from one of H, a C1-6 alkyl substituted or unsubstituted by a first substituent, a C2-6 alkenyl substituted or unsubstituted by a second substituent, and a C3-6 cycloalkyl substituted or unsubstituted by a third substituent, the first substituent, the second substituent and the third substituent are each independently selected from an alkyl or a halogen atom, and the second additive includes lithium nitrate.

[0008] In one embodiment of the present invention, R1 is hydrogen, and R2 is methyl.

[0009] In one embodiment of the present invention, the content of the first additive in the electrolyte is 0.1 wt %-3.0 wt %.

[0010] In one embodiment of the present invention, the content of the second additive in the electrolyte is 0.1wt%-4.0wt%.

[0011] In one embodiment of the present invention, the solvent is selected from at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate.

[0012] In one embodiment of the present invention, the lithium salt includes at least one of lithium hexafluorophosphate or lithium bis(fluorosulfonyl)imide.

[0013] In one embodiment of the present invention, the lithium salt includes the lithium hexafluorophosphate and the lithium bis(fluorosulfonyl)imide, and the mass content of the lithium hexafluorophosphate in the electrolyte is greater than the mass content of the lithium bis(fluorosulfonyl)imide in the electrolyte.

[0014] In one embodiment of the present invention, the additive further includes a third additive, and the third additive includes stannous octoate.

[0015] In one embodiment of the present invention, the content of the third additive in the electrolyte is 0.2wt%-0.8wt%.

[0016] The present invention also provides a battery, comprising at least:

[0017] A positive electrode, comprising a positive electrode active material, wherein the positive electrode active material is selected from at least one of lithium iron phosphate, lithium nickel manganese oxide, lithium-rich manganese base, lithium manganese iron phosphate, lithium cobalt oxide or nickel cobalt lithium manganese oxide ternary materials;

[0018] a negative electrode including lithium metal;

[0019] a separator disposed between the positive electrode and the negative electrode; and

[0020] An electrolyte is selected from the above electrolytes.

[0021] In summary, the present invention provides an electrolyte and its application, wherein the first additive and the second additive work synergistically to inhibit the reaction between the lithium metal negative electrode and the solvent in the electrolyte, effectively inhibit the growth of lithium dendrites, and improve the safety and cycle performance of the battery. The third additive, the second additive and the first additive work synergistically to further inhibit the growth of lithium dendrites, further improve the safety and cycle performance of the battery, and reduce the impedance of the battery. DETAILED DESCRIPTION

[0022] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0023] It should be understood that the present invention can be implemented in different forms and should not be interpreted as limited to the embodiments set forth herein. On the contrary, these embodiments are provided to make the disclosure thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0024] The technical scheme of the present invention is further described in detail below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] The present invention provides an electrolyte, comprising at least a lithium salt, a solvent and an additive, wherein the additive comprises a first additive and a second additive, and the general structural formula of the first additive is: Formula 1; wherein R1 and R2 are each independently selected from one of H, an alkyl group substituted or unsubstituted by a first substituent, an alkenyl group substituted or unsubstituted by a second substituent, and a cycloalkyl group substituted or unsubstituted by a third substituent, the first substituent, the second substituent, and the third substituent are each independently selected from an alkyl group or a halogen atom, and the second additive includes lithium nitrate. In the electrolyte provided by the present invention, the first additive and the second additive act synergistically to inhibit the growth of lithium dendrites and improve the safety and cycle performance of the battery.

[0026] In one embodiment of the present invention, in Formula 1, the structures of R1 and R2 may be the same or different. Further, in this embodiment, R1 is, for example, H, and R2 is, for example, methyl, that is, the first additive is, for example, Compound 1. The content of the first additive in the electrolyte is, for example, 0.1wt%-3.0wt%, and further, for example, 0.5wt%-1wt%. By controlling the content of the first additive, the cycle performance, impedance and lithium dendrite growth of the battery can be taken into account.

[0027] In one embodiment of the present invention, the second additive is, for example, lithium nitrate, and the content of the second additive in the electrolyte is, for example, 0.1wt%-4.0wt%, and further, for example, 0.3wt%-2wt%. The first additive and the second additive can act synergistically to inhibit the growth of lithium dendrites and improve the safety and cycle performance of the battery. Specifically, the amide group in the first additive can provide a high number of donors, thereby accelerating the dissociation of the second additive and increasing the solubility of the second additive. The second additive with high solubility can effectively form an inorganic SEI layer, and the first additive can form an organic SEI layer. The combination of the organic SEI layer and the inorganic SEI layer can effectively inhibit the growth of lithium dendrites and inhibit the reaction between the lithium metal negative electrode and the solvent in the electrolyte, thereby improving the safety and cycle performance of the battery.

[0028] In one embodiment of the present invention, the additive further includes a third additive, the third additive includes stannous octoate (Sn(Oct)2), and the content of the third additive in the electrolyte is, for example, 0.2wt%-0.8wt%. By introducing the third additive, the third additive, the second additive and the first additive work synergistically to further inhibit the growth of lithium dendrites, further improve the safety and cycle performance of the battery, and at the same time reduce the impedance of the battery. Moreover, by controlling the content of the third additive, the cycle performance, impedance and lithium dendrite growth of the battery can be taken into account.

[0029] In one embodiment of the present invention, the solvent is selected from at least one of ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) or diethyl carbonate (DEC).

[0030] In another embodiment of the present invention, the solvent includes cyclic carbonate and chain carbonate, etc., the cyclic carbonate is selected from at least one of EC or PC, etc., the chain carbonate is selected from at least one of DMC, EMC or DEC, etc., and the mass ratio of the chain carbonate to the cyclic carbonate is, for example, (1.5-4): 1. By controlling the ratio of the cyclic carbonate and the chain carbonate, while exerting the performance of the electrolyte, the problem of excessive viscosity of the electrolyte leading to reduced ion conductivity and wettability of the electrolyte is avoided.

[0031] In one embodiment of the present invention, the lithium salt is selected from at least one of lithium hexafluorophosphate (LiPF6) or lithium bis(fluorosulfonyl)imide (LiFSI), and the content of the lithium salt in the electrolyte is, for example, 10wt%-18wt%. Specifically, in this embodiment, the lithium salt includes, for example, LiPF6 and LiFSI, and the content of LiPF6 in the electrolyte is, for example, greater than the content of LiFSI in the electrolyte.

[0032] In one embodiment of the present invention, when preparing the electrolyte, in a glove box with a stable gas atmosphere such as argon, the cyclic carbonate and the chain carbonate are mixed uniformly according to a mass ratio to obtain a mixed solvent, and the lithium salt, the first additive, the second additive and the third additive are added to the mixed solvent and mixed uniformly to prepare the electrolyte. The moisture content in the glove box is, for example, less than 10 ppm.

[0033] The present invention also proposes a battery, and the battery includes a positive electrode, a separator, a negative electrode and an electrolyte, the separator is located between the positive electrode and the negative electrode to prevent a short circuit between the positive electrode and the negative electrode, so that lithium ions can pass through, and the electrolyte is filled between the positive electrode, the separator and the negative electrode, and the electrolyte is the above electrolyte, which plays a role in conducting ions. Among them, the battery is, for example, a lithium metal battery.

[0034] In one embodiment of the present invention, the positive electrode includes a positive electrode current collector and a positive electrode active layer coated on at least one surface of the positive electrode current collector. The positive electrode current collector is, for example, a foil formed by surface treatment of nickel, titanium, aluminum, nickel, silver, stainless steel or carbon. In addition to the foil, the positive electrode current collector can also be used in any one or more combinations of various forms such as film, mesh, porous, foam or non-woven fabric.

[0035] In one embodiment of the present invention, the positive electrode active layer includes a positive electrode active material, a conductive agent, and a binder. Among them, the ratio of the positive electrode active material, the conductive agent, and the binder can be selected according to actual needs. In this embodiment, the positive electrode active material is selected from at least one of lithium iron phosphate, lithium nickel manganese oxide, lithium-rich manganese base, lithium iron manganese phosphate, lithium cobalt oxide, or nickel cobalt lithium manganese oxide ternary material. Among them, the chemical formula of the nickel cobalt lithium manganese oxide ternary material is, for example, LiNi x Co y Mn z O2,x+y+z=1.

[0036] In one embodiment of the present invention, the conductive agent is, for example, selected from at least one of conductive carbon black (SuperP), acetylene black, carbon nanotubes or graphene, and the binder is, for example, selected from at least one of polyvinylidene fluoride (PVDF), polyethylene oxide (PEO), polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyvinylether, polymethyl methacrylate (PMMA), ethylene-propylene-diene terpolymer (EPDM), polyhexafluoropropylene or styrene butadiene rubber (SBR).

[0037] In one embodiment of the present invention, the positive electrode current collector is, for example, aluminum foil, the positive electrode active material is, for example, lithium iron phosphate, the conductive agent is, for example, acetylene black, and the binder is, for example, PVDF. The positive electrode active material, the conductive agent, and the binder are mixed, for example, in a mass ratio of 95:3:2, dissolved in an organic solvent, and stirred under the action of a vacuum stirrer until the system is uniform to obtain a positive electrode slurry, and then the positive electrode slurry is evenly coated on the aluminum foil, and then transferred to an oven for drying after drying at room temperature, and the positive electrode is obtained through processes such as rolling and cutting. Among them, the organic solvent is, for example, N-methylpyrrolidone (NMP).

[0038] In one embodiment of the present invention, the negative electrode includes lithium metal, for example, and the lithium metal is selected from pure lithium metal or lithium alloys such as copper-lithium metal. Specifically, the negative electrode is a foil formed by surface treatment of pure lithium metal or lithium alloy.

[0039] In another embodiment of the present invention, the negative electrode includes, for example, a negative electrode current collector and a negative electrode active layer coated on at least one surface of the negative electrode current collector, wherein the negative electrode current collector is, for example, selected from a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foam copper current collector, or a stainless steel current collector.

[0040] In one embodiment of the present invention, the negative electrode active layer includes a negative electrode active material, a conductive agent, and a binder. Among them, the ratio of the negative electrode active material, the conductive agent, and the binder can be selected according to actual needs. In this embodiment, the negative electrode active material is selected from at least one of graphite, silicon, or silicon dioxide. Further, the negative electrode active material is selected from at least one of artificial graphite, natural graphite, soft carbon, hard carbon, pure silicon, silicon oxide compounds, and silicon carbon compounds.

[0041] In one embodiment of the present invention, the binder is selected from at least one of PVDF, PEO, PA, polypropylene, polyacrylate, polyvinyl ether, PMMA, carboxymethyl cellulose sodium (CMC), polyhexafluoropropylene or SBR, etc. The conductive agent is selected from at least one of conductive carbon black, acetylene black, Ketjen black, carbon nanotubes or graphene, etc.

[0042] In one embodiment of the present invention, the negative electrode current collector is, for example, copper foil, the negative electrode active material is, for example, silicon dioxide, the conductive agent is, for example, acetylene black, and the binder is, for example, CMC. Specifically, the negative electrode active material, the conductive agent, and the binder carbon are mixed in a mass ratio of 96:2:2, and a deionized water solvent is added, and then the mixture is stirred and mixed evenly under the action of a vacuum mixer to obtain a negative electrode slurry, which is coated on a copper foil, and then transferred to an oven for drying after drying at room temperature, and then subjected to processes such as rolling and cutting to obtain a negative electrode.

[0043] In one embodiment of the present invention, the diaphragm is, for example, a conventional diaphragm, a ceramic diaphragm, a polymer diaphragm, a non-woven fabric or an inorganic-organic composite diaphragm, etc. Specifically, the diaphragm is, for example, a single-layer polypropylene (PP) film, a single-layer polyethylene (PE) film, a double-layer PP / PE film, a double-layer PP / PP film or a three-layer PP / PE / PP film, etc. In this embodiment, for example, a single-layer PP film is selected as the diaphragm.

[0044] In one embodiment of the present invention, the above-mentioned positive electrode, separator and negative electrode are placed in sequence, so that the separator is located between the positive electrode and the negative electrode to play an isolating role, and are encapsulated in an aluminum-plastic film to obtain a dry battery cell. The dry battery cell is then baked at 80°C to remove water, and then the electrolyte is injected into the dry battery cell and packaged to obtain a battery.

[0045] Hereinafter, the present invention will be explained in more detail by citing examples, which should not be construed as limiting. Appropriate modifications may be made within the scope consistent with the gist of the present invention, all of which fall within the technical scope of the present invention.

[0046] Example 1

[0047] Preparation of the positive electrode: lithium iron phosphate, acetylene black and PVDF are mixed in a mass ratio of 95:3:2, dissolved in NMP organic solvent, and stirred under the action of a vacuum mixer until the system is uniform to obtain a positive electrode slurry. The positive electrode slurry is then evenly coated on an aluminum foil, and then dried at room temperature and transferred to an oven for drying. The positive electrode is obtained through processes such as rolling and cutting.

[0048] Preparation of negative electrode: Pure lithium metal is pressed into pure lithium metal foil as the negative electrode.

[0049] Preparation of electrolyte: In an argon atmosphere glove box with a moisture content of less than 1ppm, according to the composition of the electrolyte described in Table 1, EC, EMC and DEC were mixed in a mass ratio of 3:5:2 to obtain a mixed solvent, and then LiPF6, LiFSI, compound 1 and lithium nitrate were added to the mixed solvent and mixed to prepare an electrolyte. Among them, the contents of LiPF6, LiFSI, compound 1 and DTD in the electrolyte were 10wt%, 3wt%, 0.1wt% and 0.5wt%, respectively.

[0050] Choice of diaphragm: Choose single-layer PP film as the diaphragm.

[0051] Preparation of the battery: The positive electrode, separator and negative electrode are placed in sequence and loaded into an aluminum-plastic film to obtain a dry battery cell. The dry battery cell is then baked at 80°C to remove water, and the electrolyte is injected into the dry battery cell and packaged to obtain a lithium metal battery.

[0052] Example 2

[0053] The content of compound 1 in the electrolyte is 0.3 wt %. The other steps are the same as those in Example 1.

[0054] Example 3

[0055] The content of compound 1 in the electrolyte is 0.5 wt %. The other steps are the same as those in Example 1.

[0056] Example 4

[0057] The content of compound 1 in the electrolyte is 1 wt %, and the other steps are the same as those in Example 1.

[0058] Example 5

[0059] The content of compound 1 in the electrolyte is 3 wt %. The other steps are the same as those in Example 1.

[0060] Example 6

[0061] The content of lithium nitrate in the electrolyte is 0.1 wt %. The other steps are the same as those in Example 3.

[0062] Example 7

[0063] The content of lithium nitrate in the electrolyte is 1 wt %, and the other steps are the same as those in Example 3.

[0064] Example 8

[0065] The content of lithium nitrate in the electrolyte is 2 wt %, and the other steps are the same as those in Example 3.

[0066] Example 9

[0067] The content of lithium nitrate in the electrolyte is 4 wt %, and the other steps are the same as those in Example 3.

[0068] Example 10

[0069] The electrolyte also contains Sn(Oct)2, and the content of Sn(Oct)2 in the electrolyte is 0.5wt%. The other steps are the same as Example 8.

[0070] Embodiment 11

[0071] The content of Sn(Oct)2 in the electrolyte is 0.2wt%, and the other steps are the same as Example 10.

[0072] Example 12

[0073] The content of Sn(Oct)2 in the electrolyte is 0.8wt%, and the other steps are the same as Example 10.

[0074] Comparative Example 1

[0075] The content of lithium nitrate in the electrolyte is 0, and the other steps are the same as those in Example 3.

[0076] Comparative Example 2

[0077] The content of compound 1 in the electrolyte is 0, and the other steps are the same as those in Example 3.

[0078] Comparative Example 3

[0079] The content of compound 1 in the electrolyte is 0, and the other steps are the same as those in Comparative Example 1.

[0080] The raw material component contents and raw material mass ratios required for the electrolytes prepared in the embodiments and comparative examples are shown in Table 1. The content of each component is the mass percentage calculated based on the total mass of the electrolyte.

[0081] Table 1. Composition of the electrolyte in Examples 1-12 and Comparative Examples 1-3

[0082]

[0083]

[0084] In the present invention, performance tests were performed on lithium metal batteries prepared using different electrolyte ratios in Examples 1-12 and Comparative Examples 1-3. The test results are shown in Table 2.

[0085] In one embodiment of the present invention, for example, a direct current resistance (DCR) test is performed on a lithium metal battery. Specifically, at 25°C, the uncycled battery is charged to 4.25V at a constant current of 1 / 3C, and then charged to a current of 0.05C at a constant voltage. The battery is then discharged to 2.5V at a constant current of 1 / 3C. Repeat the above charging steps, and record the charging capacity as C1. The battery is discharged to (50%*C1) at a constant current of 1 / 3C, and the initial voltage is recorded as V2. The battery is discharged at a constant current of 1C for 30s, and the terminal voltage is recorded as V3. Calculate DCR according to the following formula:

[0086] DCR=(V2-V3) / (C1*1).

[0087] In one embodiment of the present invention, for example, a lithium metal battery is subjected to a cycle performance test. Specifically, at 45°C, the battery is charged to 3.8V at a constant current of 1 / 3C, and then charged to a current of 0.05C at a constant voltage. The battery is then discharged to 2.0V at a constant current of 1 / 3C, and the capacity C0 of the battery is recorded. The above charge and discharge steps are repeated 1000 times, and the discharge capacity C1 of the battery after 1000 cycles is recorded, and the capacity retention rate of the battery is calculated according to the following formula:

[0088] Capacity retention rate = C1 / C0*100%.

[0089] In one embodiment of the present invention, for example, the length of lithium dendrites in a lithium metal battery is tested. Specifically, the battery after cycling is disassembled, the negative electrode in the battery is taken out, and the negative electrode is placed under a microscope to measure the length of the lithium dendrites. Among them, 9 sites are evenly selected on each negative electrode, and the length of the lithium dendrites at different sites is measured respectively, and finally the average value of the length of the lithium dendrites at the 9 sites is taken as the average length of the lithium dendrites.

[0090] Table 2 Performance test results of lithium metal batteries in Examples 1-12 and Comparative Examples 1-3

[0091]

[0092] Please refer to Table 1 and Table 2. By comparing Comparative Example 1 and Comparative Example 3, it can be seen that when the electrolyte contains Compound 1, the capacity retention rate of the battery increases, but the impedance and the average length of the lithium dendrites also increase, indicating that: although the introduction of Compound 1 can improve the cycle performance of the battery, it also leads to impedance degradation and the growth of lithium dendrites.

[0093] Please refer to Table 1 and Table 2. By comparing Comparative Example 1 and Comparative Example 2, it can be seen that when the electrolyte contains lithium nitrate, the capacity retention rate of the battery increases, the average length of the lithium dendrites remains almost unchanged, but the impedance increases, which shows that: although the introduction of lithium nitrate can improve the cycle performance of the battery, it causes the impedance of the battery to deteriorate, and the inhibitory effect on the growth of lithium dendrites is not obvious.

[0094] Please refer to Table 1 and Table 2. By comparing Example 3 and Comparative Examples 1-3, it can be seen that when the electrolyte contains both Compound 1 and lithium nitrate, the capacity retention rate of the battery is significantly increased, the average length of the lithium dendrites is significantly reduced, but the impedance of the battery is also increased, which shows that Compound 1 and lithium nitrate work synergistically to inhibit the growth of lithium dendrites and improve the cycle performance of the battery, but cause the impedance of the battery to deteriorate.

[0095] Please refer to Table 1 and Table 2. By comparing Examples 1-5, it can be seen that as the content of Compound 1 increases, the impedance gradually increases, and the capacity retention first increases and then decreases, that is, the cycle performance of the battery shows a trend of first increasing and then decreasing, and the average length of the lithium dendrites gradually decreases, which shows that by controlling the content of Compound 1, the cycle performance, impedance and lithium dendrite growth of the battery can be taken into account.

[0096] Please refer to Table 1 and Table 2. By comparing Examples 6-9, it can be seen that as the lithium nitrate content increases, the impedance gradually increases, and the capacity retention first increases and then decreases, that is, the cycle performance of the battery shows a trend of first increasing and then decreasing, and the average length of the lithium dendrites gradually decreases, which shows that by controlling the lithium nitrate content, the cycle performance, impedance and lithium dendrite growth of the battery can be taken into account.

[0097] Please refer to Table 1 and Table 2. By comparing Example 8 and Example 10, it can be seen that when the electrolyte contains Sn(Oct)2, the capacity retention rate of the battery increases, and the impedance and the average length of the lithium dendrites decrease. This shows that Sn(Oct)2, compound 1 and lithium nitrate work synergistically to further improve the battery's cycle performance and inhibit the growth of lithium dendrites while reducing the battery's impedance.

[0098] Please refer to Table 1 and Table 2. Comparative Examples 10-12 show that when the content of Sn(Oct)2 in the electrolyte increases from 0.2wt% to 0.5wt%, although the impedance of the battery increases, the capacity retention rate also increases significantly, and the average length of the lithium dendrites decreases. When the content of Sn(Oct)2 in the electrolyte continues to increase from 0.5wt% to 0.8wt%, the impedance of the battery continues to increase, and the capacity retention rate decreases slightly, and the average length of the lithium dendrites increases slightly, indicating that: as the content of Sn(Oct)2 gradually increases, although the impedance performance of the battery is affected, the cycle performance of the battery and the growth of lithium dendrites show a trend of first improving and then deteriorating. Therefore, by controlling the content of Sn(Oct)2, the cycle performance, impedance and growth of lithium dendrites of the battery can be taken into account.

[0099] The present invention also provides an electronic device, the electronic device includes at least one of the above-mentioned batteries, and the battery is used to provide electrical energy. Among them, the electronic device can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy and an electric tool, etc. In one embodiment of the present invention, the vehicle is, for example, a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. Spacecraft include airplanes, rockets, space shuttles and spacecrafts, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers, etc. The electronic device includes the above-mentioned battery, so the advantages of the above-mentioned battery are not elaborated here.

[0100] In summary, the present invention provides an electrolyte and its application, by introducing a first additive and a second additive into the electrolyte, the first additive and the second additive work synergistically, can effectively inhibit the growth of lithium dendrites, inhibit the reaction between the lithium metal negative electrode and the solvent in the electrolyte, and improve the safety and cycle performance of the battery. Moreover, by introducing a third additive into the electrolyte, the third additive, the second additive and the first additive work synergistically, can further inhibit the growth of lithium dendrites, further improve the safety and cycle performance of the battery, and reduce the impedance of the battery.

[0101] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept, such as a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

[0102] Except for the technical features described in the specification, the remaining technical features are known technologies to those skilled in the art. In order to highlight the innovative features of the present invention, the remaining technical features will not be described here in detail.

Claims

1. An electrolyte, characterized in that: At least the following components are included: Lithium salts; Solvents; as well as The additive comprises a first additive and a second additive, and the general structural formula of the first additive is: Wherein, R1 and R2 are each independently selected from one of H, a C1-6 alkyl substituted or unsubstituted by a first substituent, a C2-6 alkenyl substituted or unsubstituted by a second substituent, and a C3-6 cycloalkyl substituted or unsubstituted by a third substituent, the first substituent, the second substituent and the third substituent are each independently selected from an alkyl or a halogen atom, and the second additive includes lithium nitrate.

2. The electrolyte according to claim 1, characterized in that R1 is hydrogen and R2 is methyl.

3. The electrolyte according to claim 1, characterized in that The content of the first additive in the electrolyte is 0.1 wt%-3.0 wt%.

4. The electrolyte according to claim 1, characterized in that The content of the second additive in the electrolyte is 0.1wt%-4.0wt%.

5. The electrolyte according to claim 1, characterized in that The solvent is selected from at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate.

6. The electrolyte according to claim 1, characterized in that The lithium salt includes at least one of lithium hexafluorophosphate and lithium bis(fluorosulfonyl)imide.

7. The electrolyte according to claim 6, characterized in that The lithium salt includes the lithium hexafluorophosphate and the lithium bisfluorosulfonyl imide, and the mass content of the lithium hexafluorophosphate in the electrolyte is greater than the mass content of the lithium bisfluorosulfonyl imide in the electrolyte.

8. The electrolyte according to claim 1, characterized in that The additives further include a third additive, and the third additive includes stannous octoate.

9. The electrolyte according to claim 8, characterized in that The content of the third additive in the electrolyte is 0.2wt%-0.8wt%.

10. A battery, characterized in that: At least: A positive electrode, comprising a positive electrode active material, wherein the positive electrode active material is selected from at least one of lithium iron phosphate, lithium nickel manganese oxide, lithium-rich manganese base, lithium manganese iron phosphate, lithium cobalt oxide or nickel cobalt lithium manganese oxide ternary materials; a negative electrode including lithium metal; a separator disposed between the positive electrode and the negative electrode; and An electrolyte, wherein the electrolyte is selected from the electrolyte described in any one of claims 1 to 9.

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