Electrolyte, battery, battery pack and electric equipment

Abstract

The invention relates to an electrolyte, a battery, a battery pack and electric equipment. The electrolyte contains an ether organic solvent, a first lithium salt and a second lithium salt, wherein the first lithium salt contains LiNO3 and an organic fluorine-containing sulfimide lithium salt; the second lithium salt contains LiPO2F2 and lithium oxalate containing salt; the ether organic solvent comprises at least one of cyclic ether with the carbon atom number of 3-5 and aliphatic ether with the carbon atom number of 3-5. According to the electrolyte disclosed by the invention, the dynamic performance and interface stability of the battery can be improved, the cycling stability, high-temperature storage performance and low-temperature dynamic performance of a battery system are improved, and the electrolyte has certain application potential.

Description

Technical Field

[0001] The present disclosure relates to the field of new energy, and in particular, to an electrolyte, a battery, a battery pack and an electrical device. Background Art

[0002] Lithium-ion batteries are the most successful commercial secondary batteries today, with advantages such as high actual energy density and long cycle life. Ether electrolytes have the characteristics of low melting point, high ionic conductivity, high solubility for some electrolyte additives with low solubility in carbonate systems, and can be regulated and assisted in the forward design to form a thinner, inorganic-rich SEI film. They have been widely used in lithium metal batteries and are potential electrolyte application directions. However, ether electrolytes are difficult to use in positive electrode-graphite secondary lithium-ion batteries. Specifically, the graphite negative electrode has the problem of ether solvent co-embedding in the basic ether electrolyte, which causes the graphite to fall off and peel off during the cycle, resulting in poor performance. In addition, when charging under low temperature conditions, lithium ions cannot be embedded in graphite, and lithium deposition occurs on its surface, which creates a safety hazard. In addition, at low voltage, ether electrolytes are also likely to be reduced, and the reduction reaction reduces the stability of the electrolyte system. It can be seen that the interface stability problem between the graphite negative electrode and the electrolyte is a problem that hinders the improvement of electrolyte performance and even hinders the development of lithium-ion battery technology. On the positive electrode side, ethers may easily come into direct contact with active particles, causing a series of uncontrollable oxidation side reactions. The instability of the interface between ether solvents and the positive electrode will also lead to deterioration of battery performance.

[0003] The design of high entropy electrolyte is a research direction to improve the above interface problems. The high entropy system is a mixture of multiple components (which can be lithium salts, solvents, additives), which uses the unique properties of each component and even the new characteristics of the mixed high entropy system to enhance the stability of the battery interface. + -The problem of solvent co-embedding in graphite negative electrode affects the cycle stability and low-temperature kinetic performance of the battery, limiting its industrial application. Summary of the invention

[0004] The object of the present disclosure is to provide an electrolyte, a battery, a battery pack and an electrical device, wherein the electrolyte can improve the cycle stability, high-temperature storage performance and low-temperature kinetic performance of the battery.

[0005] In order to achieve the above-mentioned purpose, the first aspect of the present disclosure provides an electrolyte, which includes an ether organic solvent, a first lithium salt and a second lithium salt; wherein the first lithium salt includes LiNO3 and an organic fluorine-containing sulfonyl imide lithium salt; the second lithium salt includes LiPO2F2 and a lithium oxalate salt; the ether organic solvent includes at least one of a cyclic ether with a carbon number of 3-5 and a fatty ether with a carbon number of 3-5.

[0006] Optionally, the organic fluorine-containing sulfonyl imide lithium salt includes LiFSI and / or LiTFSI; and / or, the lithium oxalate salt includes LiBOB and / or LiODFB.

[0007] Optionally, in the electrolyte, a weight ratio of the ether organic solvent, the first lithium salt and the second lithium salt is 100:(9-63):(0.3-9.0), preferably 100:(19-42):(3-7).

[0008] Optionally, the weight ratio of the organic fluorinated sulfonyl imide lithium salt to the LiNO3 in the electrolyte is 100:(3-110), preferably 100:(5-40);

[0009] The weight ratio of the lithium oxalate salt to the LiPO2F2 is (10-500):100, preferably (65-200):100.

[0010] Optionally, the second lithium salt further comprises LiClO4;

[0011] The weight ratio of the lithium oxalate salt, the LiPO2F2 and the LiClO4 is (10-500):100:(10-500), preferably (65-200):100:(50-200).

[0012] Optionally, the ether organic solvent includes one or more of 1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, 1,3,5-trioxane, tetrahydrofuran and dimethanol formal.

[0013] Optionally, the electrolyte further contains a flame retardant and / or a high voltage additive:

[0014] The flame retardant comprises one or more of triethyl phosphate, trimethyl phosphate, triphenyl phosphate and ethoxy pentafluorocyclotriphosphazene; and / or,

[0015] The high voltage additive includes one or more of fluoroethylene carbonate, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and tris(trimethylsilyl)phosphite.

[0016] Optionally, the flame retardant comprises triphenyl phosphate and ethoxy pentafluorocyclotriphosphazene, and the weight ratio of the triphenyl phosphate to the ethoxy pentafluorocyclotriphosphazene is 1:(0.5-5);

[0017] The high voltage additive comprises fluoroethylene carbonate and tris(trimethylsilyl)phosphite, and the weight ratio of the fluoroethylene carbonate to the tris(trimethylsilyl)phosphite is 1:(0.5-5).

[0018] Optionally, the weight ratio of the ether organic solvent, the first lithium salt, the second lithium salt, the flame retardant and the high voltage additive in the electrolyte is 100:(9-63):(0.3-9):(0.1-5):(0.1-5), preferably 100:(19-42):(3-7):(1-3):(1-4).

[0019] A second aspect of the present disclosure provides a battery, comprising the electrolyte provided by the first aspect of the present disclosure.

[0020] A third aspect of the present disclosure provides a battery pack, comprising the battery provided by the second aspect of the present disclosure.

[0021] A fourth aspect of the present disclosure provides an electrical device, wherein the electrical device comprises the battery provided in the second aspect of the present disclosure or the battery pack provided in the third aspect of the present disclosure.

[0022] Through the above technical scheme, the first lithium salt containing LiNO3 and organic fluorinated sulfonyl imide lithium salt and the second lithium salt containing LiPO2F2 and lithium oxalate salt are compounded with ether organic solvents in the electrolyte of the present invention. Among them, the first lithium salt and the ether organic solvent can form a special solvation structure, thereby effectively avoiding the problem of ether solvent co-embedding of the graphite negative electrode in the basic ether electrolyte; after the second lithium salt is decomposed, a CEI film is formed on the positive electrode side and a SEI film is formed on the negative electrode side, which improves the stability of the positive and negative electrode interfaces while also improving the dynamic performance of the interface. Therefore, the electrolyte of the present invention can improve the interface stability and dynamic performance of batteries (such as lithium-ion batteries), so that it has better cycle stability, high temperature storage performance and low temperature dynamic performance.

[0023] Other features and advantages of the present disclosure will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0024] The specific embodiments of the present disclosure are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0025] In a first aspect, the present disclosure provides an electrolyte, which includes an ether organic solvent, a first lithium salt and a second lithium salt; wherein the first lithium salt includes LiNO3 and an organic fluorine-containing sulfonyl imide lithium salt; the second lithium salt includes LiPO2F2 and a lithium oxalate salt; the ether organic solvent includes at least one of a cyclic ether with a carbon number of 3-5 and an aliphatic ether with a carbon number of 3-5.

[0026] The electrolyte disclosed in the present invention uses an ether organic solvent as the main solvent, which has a weak solvation effect on the first lithium salt. Specifically, the present invention uses a first lithium salt containing an organic fluorinated sulfonyl imide lithium salt and LiNO3 (lithium nitrate, CAS No. 7790-69-4) and a second lithium salt containing LiPO2F2 (lithium difluorophosphate, CAS No. 24389-25-1) and lithium oxalate salt in combination, which can significantly improve the interfacial stability and kinetic performance of lithium-ion batteries. Specifically, the first lithium salt can form a special solvation structure with the ether organic solvent, and the solvation structure makes the proportion of aggregates (AGG) and contact ion pairs (CIP) in the electrolyte system high, so that the anions provided by the organic fluorinated sulfonyl imide lithium salt can be preferentially decomposed, and the reduction forms an inorganic, dense SEI film dominated by anion decomposition, which can effectively avoid the occurrence of subsequent ether co-embedding reactions and help LiNO3 dissolve in ether organic solvents; and Li3N and LiN formed by the decomposition of LiNO3 x O y The inorganic SEI components are Li + It is an excellent conductor that can improve the kinetic properties of the interface, and the inorganic SEI can also enhance the cycle stability. The lack of LiNO3 will cause the polymerization of ether organic solvents. The reduction and decomposition of LiPO2F2 in the second lithium salt can form inorganic SEI components such as LiF and Li3PO4. The inorganic SEI components based on Li3PO4 can support rapid lithium ion transmission, block electron tunneling, promote desolvation of the interface, and help improve the low-temperature kinetic properties of the battery. In addition, the solubility of LiPO2F2 in the electrolyte system of the present invention can reach more than 7% by weight, and it can also form an inorganic CEI film rich in the positive electrode, which can also improve the interface kinetics and stability of the positive electrode. Lithium oxalate salts can form films at both the positive and negative electrodes, and the formed Li-BO inorganic SEI can provide effective protection for the interface of the battery cell, which is beneficial to improving the high voltage stability and life of the battery cell. The electrolyte disclosed in the present invention adopts a specific ether organic solvent. Through the synergistic effect of the first lithium salt and the second lithium salt, the electrolyte can effectively improve the interface stability and kinetic performance of the lithium-ion battery, and improve the cycle stability, high-temperature storage performance and low-temperature kinetic performance of the battery system.

[0027] In a specific embodiment of the present disclosure, the organic fluorine-containing sulfonyl imide lithium salt includes LiFSI (lithium bis(fluorosulfonyl)imide, CAS No. 171611-11-3) and / or LiTFSI (lithium bis(trifluoromethylsulfonyl)imide, CAS No. 90076-65-6); and / or, the lithium oxalate salt includes LiBOB (lithium bis(oxalatoborate, CAS No. 244761-29-3) and / or LiODFB (lithium difluorooxalatoborate, CAS No. 409071-16-5). In this embodiment, the first lithium salt can form a special solvation structure with an ether organic solvent, which makes the proportion of aggregates (AGG) and contact ion pairs (CIP) in the electrolyte system high, and the anion FSI provided by LiFSI is - and LiTFSI provided anion TFSI - It can be preferentially decomposed, and the reduction forms an inorganic, dense SEI film dominated by anion decomposition, which can effectively avoid the subsequent ether co-embedding reaction and improve the cycle stability of the battery.

[0028] According to the present disclosure, the weight ratio of the ether organic solvent, the first lithium salt and the second lithium salt in the electrolyte can vary within a wide range. In a specific embodiment of the present disclosure, the weight ratio of the ether organic solvent, the first lithium salt and the second lithium salt is 100:(9-63):(0.3-9.0), preferably 100:(19-42):(3-7). In this embodiment, the contents of the organic solvent, the first lithium salt and the second lithium salt are appropriate, so that the electrolyte has a better effect of improving the interfacial stability and kinetic performance of lithium ions when used in batteries.

[0029] According to the present disclosure, the weight ratio of each component in the first lithium salt can vary within a wide range. In a specific embodiment of the present disclosure, the weight ratio of the organic fluorinated sulfonyl imide lithium salt to LiNO3 in the electrolyte is 100:(3-110), preferably 100:(5-40). In this embodiment, the ratio of the two components in the first lithium salt is appropriate, and the electrolyte containing the first lithium salt of this composition can more effectively avoid the co-embedding of the graphite negative electrode in the presence of ether solvents in the basic ether electrolyte, which is beneficial to further improve the kinetic properties of the interface while enhancing the cycle stability.

[0030] According to the present disclosure, the weight ratio of each component in the second lithium salt can vary within a wide range. In a specific embodiment of the present disclosure, the weight ratio of the lithium oxalate salt to LiPO2F2 is (10-500):100, preferably (65-200):100. In this embodiment, the ratio of each component in the second lithium salt is appropriate, so that the electrolyte has a better effect of providing effective protection to the battery cell interface, and is conducive to further improving the high voltage stability and life of the battery cell.

[0031] In a specific embodiment of the present disclosure, the second lithium salt further contains LiClO4 (lithium perchlorate, CAS No. 13453-78-6), and the weight ratio of the lithium oxalate salt, the LiPO2F2 and the LiClO4 is (10-500):100:(10-500), preferably (65-200):100:(50-200). In this embodiment, LiClO4 has the effect of reduction decomposition and forming a Li2O-rich inorganic SEI component, and the proportion of each component in the second lithium salt is appropriate, which can further improve the kinetic performance of the interface and improve the cycle stability and safety of the battery.

[0032] In a specific embodiment of the present disclosure, the number of oxygen atoms contained in the ether organic solvent molecule is 1, 2 or 3; the number of ring atoms of the cyclic ether is 5 or 6; the ether organic solvent includes one or more of 1,3-dioxolane (DOL), 1,3-dioxane, 1,4-dioxane, 1,3,5-trioxane, tetrahydrofuran and dimethanol formal, preferably 1,3-dioxane. In this embodiment, the above-mentioned types of ether organic solvents have a better weak solvation effect on the first lithium salt, and using them in combination with the first lithium salt and the second lithium salt can more effectively avoid the occurrence of ether co-embedding reaction.

[0033] In order to further improve the safety of the electrolyte, in a specific embodiment of the present disclosure, the electrolyte also contains a flame retardant: the flame retardant can be well known to those skilled in the art, for example, it can include an organic phosphorus flame retardant, optionally including one or more of triethyl phosphate (TEP), trimethyl phosphate (TMP), triphenyl phosphate (TPP) and ethoxy pentafluorocyclotriphosphazene (PFPN). In this embodiment, the above-mentioned flame retardant can be reduced to form a film at the negative electrode, wherein the organic phosphate has the function of forming an inorganic SEI film containing Li-PO, and the cyclophosphazene can form a mixed inorganic SEI film such as LiF, Li3N, Li-PO, etc. due to its rich P, N, and F elements, which is conducive to further improving the dynamic performance and stability of the interface.

[0034] In order to improve the effect of improving the high voltage stability of the battery when the electrolyte is used in the battery, in a specific embodiment of the present disclosure, the electrolyte also contains a high voltage additive. The high voltage additive is an additive that can improve the high voltage stability that is well known to those skilled in the art, and may include one or more of fluoroethylene carbonate (FEC), triethylene glycol dimethyl ether (G3), tetraethylene glycol dimethyl ether (G4) and tris (trimethylsilyl) phosphite (TMSP). In this embodiment, FEC is a fluorinated solvent with good high voltage stability. An appropriate amount of addition can improve the high voltage resistance level of the electrolyte system, and the CEI film formed by the decomposition of FEC can effectively reduce the direct contact area between the electrolyte and the positive electrode active particles, and inhibit the decomposition of the electrolyte. G3 and G4 have excellent oxidation stability, and an appropriate amount of addition can also improve the high voltage resistance level of the electrolyte system. TMSP has a higher HOMO energy level and can decompose preferentially over solvents to form a uniform SEI / CEI film rich in P and Si, thereby effectively reducing the direct contact area between the electrolyte and the positive electrode active particles and inhibiting the decomposition of the electrolyte. In addition, TMSP can also neutralize harmful substances such as HF in the electrolyte system. By using the above-mentioned high-voltage additives, the effect of the electrolyte on improving the interfacial stability and kinetic performance of the battery can be further enhanced.

[0035] In a preferred embodiment of the present disclosure, the flame retardant includes triphenyl phosphate and ethoxy pentafluorocyclotriphosphazene, and the weight ratio of the triphenyl phosphate to the ethoxy pentafluorocyclotriphosphazene is 1:(0.5-5), preferably 1:(1-3); the high voltage additive includes fluoroethylene carbonate and tris(trimethylsilyl)phosphite, and the weight ratio of the fluoroethylene carbonate to the tris(trimethylsilyl)phosphite is 1:(0.5-5), preferably 1:(1-4). In this embodiment, by making the electrolyte contain a specific type of flame retardant and / or high voltage additive, the effect of the electrolyte on improving the interface stability and dynamic performance of the battery can be further enhanced.

[0036] According to the present disclosure, the weight ratio of the organic solvent, the first lithium salt, the second lithium salt, the flame retardant and the high voltage additive can vary within a large range. In a specific embodiment of the present disclosure, the weight ratio of the ether organic solvent, the first lithium salt, the second lithium salt, the flame retardant and the high voltage additive in the electrolyte is 100: (9-63): (0.3-9): (0.1-5): (0.1-5), preferably 100: (19-42): (3-7): (1-3): (1-4). The components in the lithium ion electrolyte are appropriately proportioned within the above-mentioned dosage range, so that the electrolyte has a better interface stability and kinetic performance of the battery.

[0037] The second aspect of the present disclosure provides a battery, the battery containing the electrolyte provided by the first aspect of the present disclosure. In one embodiment, the battery comprises a lithium ion battery. The battery disclosed in the present disclosure has excellent cycle stability, high temperature storage performance and low temperature kinetic performance.

[0038] The third aspect of the present disclosure provides a battery pack, the battery pack comprising the battery provided by the second aspect of the present disclosure. The battery pack of the present disclosure has excellent cycle stability, high temperature storage performance and low temperature kinetic performance.

[0039] A fourth aspect of the present disclosure provides an electrical device, which includes the battery provided by the second aspect of the present disclosure or the battery pack provided by the third aspect.

[0040] The electrical equipment in the present disclosure may be any equipment that requires a battery pack, such as but not limited to automobiles, commercial vehicles, energy storage, two-wheeled electric vehicles, three-wheeled electric vehicles, 3C digital products, drones, etc.

[0041] The present disclosure is further illustrated below by way of examples, but the present disclosure is not limited thereby.

[0042] Unless otherwise specified, the reagents and materials used in the following examples and comparative examples were commercially available.

[0043] Example 1

[0044] The electrolyte of this embodiment contains an ether organic solvent, a first lithium salt, a second lithium salt, a flame retardant and a high voltage additive.

[0045] Among them, the ether organic solvent is 1,3-dioxolane (DOL), the first lithium salt is LiFSI and LiNO3, the second lithium salt is LiPO2F2, LiClO4 and LiBOB, the flame retardant is triethyl phosphate (TPP) and ethoxypentafluorocyclotriphosphazene (PFPN), the additive is fluoroethylene carbonate (FEC) and tris(trimethylsilyl) phosphite (TMSP), and the weight dosage of the above components in the electrolyte is shown in Table 1.

[0046] Embodiment 2-20

[0047] The composition of the electrolyte in Examples 2-20 is similar to that in Example 1, as specifically shown in Table 1.

[0048] Comparative Examples 1-9

[0049] The compositions of the electrolytes in Comparative Examples 1-9 are shown in Table 1.

[0050] Test Case

[0051] (1) Preparation of batteries

[0052] The electrolytes obtained in Examples 1-20 and Comparative Examples 1-9 were respectively assembled with pole pieces into soft-pack cells, and the prepared lithium-ion batteries were named A1-A20 and C1-C9.

[0053] The specific preparation method is as follows: disperse the positive electrode active material LFP, the conductive material CNT, the conductive carbon black and the binder (polyvinylidene fluoride) PVDF in the solvent NMP in a mass ratio of 94:2:2:2 to obtain a positive electrode active material layer slurry; evenly coat the positive electrode active material layer slurry on the surface of the positive electrode current collector aluminum foil, and obtain the positive electrode sheet after drying, rolling, baking, slitting and spot welding the pole ears.

[0054] The negative electrode active material artificial graphite, conductive agent conductive carbon black, CNT, sodium carboxymethyl cellulose and binder SBR are dispersed in deionized water in a mass ratio of 95:1.25:1.25:1.25:1.25, and stirred evenly to obtain a negative electrode active material layer slurry; the negative electrode active material layer slurry is evenly coated on the surface of the negative electrode collector copper foil, and the negative electrode sheet is obtained after drying, rolling, baking, slitting and spot welding of the electrode ears, and the N / P ratio of the positive and negative electrode sheets is 1.1.

[0055] The prepared positive electrode sheet, negative electrode sheet and separator are stacked in order, Celgard2400 polypropylene film is selected as the separator, and the separator is placed between the positive electrode sheet and the negative electrode sheet. After winding, the battery cell is placed in an aluminum-plastic film package, dried, and sealed by injecting electrolyte. After standing, forming, secondary sealing, capacity division and other processes, a lithium-ion battery is obtained.

[0056] (2) Battery cell experiment

[0057] The battery cells were subjected to 60°C full-charge high-temperature storage and 1C rate 60°C high-temperature cycle experiments, -10°C 25% SOC, 1C discharge and low-temperature DCIR measurement, and electrochemical data were collected. The results are shown in Table 2.

[0058] High temperature (60°C) storage performance test: the battery was charged to 3.8V at 1C constant current to constant voltage at 25°C, cut off at 0.05C, left to stand for 0.5h, and then discharged to 2.2V at 1C constant current. This discharge capacity was counted as the initial capacity C0. The battery was charged to 3.8V at 1C constant current to constant voltage at 25°C, cut off at 0.05C, and the fully charged battery was transferred to a high temperature test cabinet and stored at 60°C for 15 days. After the storage was completed, the test battery was taken out, left at room temperature for 8h, and then discharged to 2.2V at 1C constant current, left for 0.5h, charged to 3.8V at 1C constant current to constant voltage, cut off at 0.05C, left to stand for 0.5h, and then discharged to 2.2V at 1C constant current after 1C constant current to constant voltage, and the discharge capacity C1 was recorded. High temperature (60°C) storage capacity recovery rate (%) = (C1 / C0)*100%. For test data, please see 15D high temperature storage capacity recovery rate in Table 1.

[0059] High temperature (60°C) cycle performance test: The battery is charged to 3.8V at 1C constant current to constant voltage at 25°C, cut off at 0.05C, let stand for 0.5h, and then discharged to 2.2V at 1C constant current. This discharge capacity is counted as the initial capacity C0. The battery is transferred to a high temperature test cabinet and cycled at 60°C for the following days: charge to 3.8V at 1C constant current to constant voltage, cut off at 0.05C, let stand for 0.5h, and then discharge to 2.2V at 1C constant current. After completion, take out the test battery, leave it at room temperature for 8h, then discharge it at 1C constant current to 2.2V, leave it for 0.5h, charge it at 1C constant current to constant voltage to 3.8V, cut off at 0.05C, leave it for 0.5h, discharge it at 1C constant current to 2.2V, and record the discharge capacity C1; High temperature (60℃) cycle capacity retention rate (%) = (C1 / C0) * 100%. For test data, please see the 100-cycle high temperature cycle capacity retention rate in Table 1.

[0060] Low temperature discharge DCIR test: the battery is charged to 3.8V at 25℃ with 1C constant current to constant voltage, cut off at 0.05C, and then let stand for 0.5h, and then discharged to 2.2V with 1C constant current. The discharge capacity is counted as the initial capacity C0. The battery is charged to 3.8V at 25℃ with 1C constant current to constant voltage, cut off at 0.05C, and then discharged to 0.75C0 capacity. The battery cell is placed in a -10℃ constant temperature box and let stand for more than 6h, and then discharged at 1C current for 30s, with a sampling frequency of 0.1s. The voltage of the last step of standing is recorded as V0, and the voltage of the last step of discharge is recorded as Vs. The DCIR value is (V0-Vs) / C0. For test data, please see the low temperature discharge DCIR in Table 1.

[0061]

[0062]

[0063] In the examples and comparative examples in Table 1, "DOL accounts for 100%" means that the organic solvent consists of 100 parts by weight of DOL, "THF accounts for 100%" means that the organic solvent consists of 100 parts by weight of THF, "DMM accounts for 100%" means that the organic solvent consists of 100 parts by weight of DMM, "1,3-dioxane accounts for 100%" means that the organic solvent consists of 100 parts by weight of 1,3-dioxane, "1,4-dioxane accounts for 100%" means that the organic solvent consists of 1,4-dioxane, "1,3,5-trioxane accounts for 100%" means that the organic solvent consists of 100 parts by weight of 1,3,5-trioxane, "1,2-dimethoxyethane accounts for 100%" means that the organic solvent consists of 100 parts by weight of 1,2-dimethoxyethane, "EC+DEC+EMC, 1:1:1in Vol. 100” consists of EC, DEC and EMC in a volume ratio of 1:1:1, and the total weight of EC, DEC and EMC is 100 parts by weight.

[0064] Table 2

[0065]

[0066]

[0067] As can be seen from Table 2, the electrolyte disclosed in the present invention can improve the kinetic performance and interface stability of lithium-ion batteries, improve the low-temperature kinetic performance and cycle stability of the battery system, and has certain application potential.

[0068] The preferred embodiments of the present disclosure are described in detail above; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0069] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0070] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. An electrolyte, characterized in that: The electrolyte includes an ether organic solvent, a first lithium salt and a second lithium salt; wherein the first lithium salt includes LiNO3 and an organic fluorine-containing sulfonyl imide lithium salt; the second lithium salt includes LiPO2F2 and a lithium oxalate salt; the ether organic solvent includes at least one of a cyclic ether with a carbon number of 3-5 and an aliphatic ether with a carbon number of 3-5.

2. The electrolyte according to claim 1, wherein The organic fluorine-containing sulfonyl imide lithium salt includes LiFSI and / or LiTFSI; and / or, the lithium oxalate salt includes LiBOB and / or LiODFB.

3. The electrolyte according to claim 1 or 2, wherein The weight ratio of the ether organic solvent, the first lithium salt and the second lithium salt in the electrolyte is 100:(9-63):(0.3-9.0), preferably 100:(19-42):(3-7).

4. The electrolyte according to claim 1 or 2, wherein The weight ratio of the organic fluorinated sulfonyl imide lithium salt to the LiNO3 in the electrolyte is 100:(3-110), preferably 100:(5-40); The weight ratio of the lithium oxalate salt to the LiPO2F2 is (10-500):100, preferably (65-200):

100.

5. The electrolyte according to claim 1 or 2, wherein The second lithium salt also includes LiClO4; The weight ratio of the lithium oxalate salt, the LiPO2F2 and the LiClO4 is (10-500):100:(10-500), preferably (65-200):100:(50-200).

6. The electrolyte according to claim 1 or 2, wherein The ether organic solvent includes one or more of 1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, 1,3,5-trioxane, tetrahydrofuran and dimethanol formal.

7. The electrolyte according to claim 1 or 2, wherein The electrolyte also includes a flame retardant and / or a high voltage additive: The flame retardant comprises one or more of triethyl phosphate, trimethyl phosphate, triphenyl phosphate and ethoxy pentafluorocyclotriphosphazene; and / or, The high voltage additive includes one or more of fluoroethylene carbonate, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and tris(trimethylsilyl)phosphite.

8. The electrolyte according to claim 7, wherein The flame retardant comprises triphenyl phosphate and ethoxy pentafluorocyclotriphosphazene, and the weight ratio of the triphenyl phosphate to the ethoxy pentafluorocyclotriphosphazene is 1:(0.5-5); The high voltage additive comprises fluoroethylene carbonate and tris(trimethylsilyl)phosphite, and the weight ratio of the fluoroethylene carbonate to the tris(trimethylsilyl)phosphite is 1:(0.5-5).

9. The electrolyte according to claim 7, wherein The weight ratio of the ether organic solvent, the first lithium salt, the second lithium salt, the flame retardant and the high voltage additive in the electrolyte is 100:(9-63):(0.3-9):(0.1-5):(0.1-5), preferably 100:(19-42):(3-7):(1-3):(1-4).

10. A battery, characterized in that: The battery comprises the electrolyte according to any one of claims 1 to 9.

11. A battery pack, characterized in that: The battery pack comprises the battery according to claim 10.

12. An electrical equipment, characterized in that: The electrical device comprises the battery according to claim 10 or the battery pack according to claim 11.

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