Electrolyte and battery

Abstract

The invention provides an electrolyte and a battery. The electrolyte comprises a lithium salt, an organic solvent and a functional additive, the structural formula of the functional additive is # imgabs0, wherein R1 comprises at least one of a primary amine group, a secondary amine group and a tertiary amine group; at least one of R4 and R5 comprises a cyano group. According to the electrolyte, the specific functional additive is introduced, so that the electrolyte has good film forming characteristics on the positive electrode side and the negative electrode side, and therefore, the positive electrode side and the negative electrode side have relatively good interface stability under high voltage, and the long-term cycle performance and the high-temperature storage performance of the high-voltage battery are further improved.

Description

Technical Field

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

[0002] Developing high-voltage ternary positive electrode materials is an effective way to increase the energy density of lithium-ion batteries. However, with the increase of nickel content in ternary materials or the continuous increase of limiting voltage, the gram capacity of battery materials gradually increases, while the high and low temperature performance of the battery is difficult to take into account. High-temperature storage is prone to gas production, the internal resistance increases rapidly during the cycle, and long cycle life cannot be guaranteed.

[0003] Currently, lithium-ion battery electrolytes mostly use traditional film-forming additives such as vinylene carbonate (VC) or fluoroethylene carbonate (FEC), but VC has poor oxidation resistance. Although FEC is antioxidant, it easily decomposes at high temperatures to produce hydrofluoric acid (HF), which will further aggravate the dissolution of metal ions in the ternary positive electrode material and deteriorate battery performance.

[0004] In addition, for ternary positive electrode materials, the oxidation states of Ni, Co, and Mn are +2, +3, and +4, respectively. During charging, since lithium ions will be deintercalated from the positive electrode, Ni will change from +2 to +3 or even +4. At the same time, the positive electrode will react with the electrolyte to form a solid electrolyte interface (CEI layer). The CEI layer will protect the positive electrode (similar to the SEI film of the negative electrode), hindering the further reaction of the positive electrode and the electrolyte, and improving the stability of the positive electrode under delithiation conditions. However, the formation of the CEI film will also cause problems such as increased battery impedance, rate attenuation, capacity attenuation, and gas generation. Therefore, it is particularly important to form the best positive electrode CEI film by optimizing the electrolyte components. Of course, the formation of a good SEI film on the negative electrode side is also particularly important for the performance of the battery.

[0005] As a result, a new ternary high-voltage lithium-ion battery electrolyte was developed to ensure that it has good film-forming properties on both the positive and negative electrode sides, which is of great significance for further optimizing the battery interface stability and battery performance. Summary of the invention

[0006] In order to solve the problems and shortcomings in the prior art, the present invention provides an electrolyte and a battery. The electrolyte introduces specific functional additives so that the electrolyte has good film-forming properties on both the positive and negative electrode sides, thereby ensuring that the positive and negative electrodes have good interface stability under high voltage, thereby improving the long-term cycle performance and high-temperature storage performance of the high-voltage battery.

[0007] According to a first aspect of the present invention, an electrolyte is provided, comprising a lithium salt, an organic solvent, and a functional additive; the structural formula of the functional additive is:

[0008] Wherein, R1 includes at least one of a primary amine group, a secondary amine group, and a tertiary amine group; and at least one of R4 and R5 includes a cyano group.

[0009] The introduction of the functional additives with the above-mentioned specific structure effectively improves the overall performance of the electrolyte, thereby effectively improving the cycle performance and high-temperature storage performance of the battery, and effectively reduces the battery DCR growth rate.

[0010] Specifically, firstly, the above-mentioned functional additives have structures such as benzene rings and double bonds, and the conjugated structure they form can improve the conductivity and ion conductivity of the electrolyte and reduce the DCR growth rate of the battery; and the double bonds can be polymerized during the battery formation process, which is beneficial to the formation of uniform and dense CEI and SEI films at the positive and negative electrode interfaces, thereby improving the stability of the positive and negative electrode interfaces, and thus optimizing the battery cycle performance and high-temperature storage performance; structures such as benzene rings can also improve the stability of the molecular structure, which is beneficial to improving the overall stability of the electrolyte, thereby improving the high-voltage antioxidant performance and thermal stability of the electrolyte.

[0011] Secondly, the sulfate group can further participate in the negative electrode film formation and improve the stability of the negative electrode SEI film. The sulfate group has a strong polarity and can interact with lithium ions, promote the dissociation and transmission of lithium ions in the electrolyte, and thus improve the ionic conductivity of the electrolyte. This helps to reduce the internal resistance of the battery and improve the battery's charge and discharge efficiency and rate performance.

[0012] Third, the cyano group has a wide chemical window, and the strong polarity of the cyano group helps to improve the compatibility between the electrolyte and the electrode, and improve the electrochemical properties of the battery such as high temperature and high pressure. Primary amines, secondary amines, and tertiary amines have a certain alkalinity and can interact with acidic impurities or lithium salts in the electrolyte, adjust the acidity and alkalinity of the electrolyte, reduce side reactions, or promote the dissociation and transmission of lithium ions in the electrolyte, improve the stability and performance of the electrolyte, and thus improve the cycle stability and safety of the battery. In addition, the N group in the cyano group, primary amine, secondary amine, and tertiary amine can complex with transition metal ions to reduce the damage of transition metal ions to the negative electrode, thereby further improving the stability of the negative electrode interface, thereby further improving the overall performance of the battery.

[0013] Preferably, R2 includes at least one of hydrogen, an alkyl chain, a substituted alkyl chain, and a halogen; R3 includes at least one of an alkyl chain, a substituted alkyl chain, an alkyl chain containing a double bond or a triple bond, and a substituted alkyl chain containing a double bond or a triple bond, and the number of carbon atoms in R3 is ≥0.

[0014] It should be noted here that when the number of carbon atoms in R3 = 0, the structural formula of the functional additive is:

[0015]

[0016] Preferably, R4 and R5 independently include cyano groups. When the functional additive includes two cyano groups, the electrolyte in which the functional additive is located exhibits better performance, so that the battery has better cycle performance and high temperature storage performance, and also makes the battery have a lower DCR growth rate. Therefore, when the functional additive includes two cyano groups, it is more conducive to the performance of the electrolyte and more conducive to the optimization of battery performance.

[0017] Preferably, R1 includes a primary amine group and hydrogen, R2 includes hydrogen, the number of carbon atoms in R3=0, and R4 and R5 independently include cyano groups.

[0018] Preferably, the structural formula of the functional additive is:

[0019]

[0020] Preferably, the functional additive accounts for 0.1-0.5% by mass in the electrolyte.

[0021] Preferably, the electrolyte further comprises a sulfur-containing additive, and the sulfur-containing additive comprises at least one of 1,3-propane sultone (PST), vinyl sulfite (ES), vinyl sulfite (VES), vinyl sulfate (DTD), methylene disulfonate (MMDS), thiophene derivatives (TH), fluorosulfonyloxybenzene (FSOB), phenyl methanesulfonate (PMS), and hydroquinone difluorosulfonate (HBFS). After the above-mentioned types of sulfur-containing additives are introduced into the electrolyte of the present invention, the battery prepared using the same exhibits better performance. This may be because the introduction of sulfur-containing additives further promotes the film formation stability and uniformity of the negative electrode SEI film, effectively reduces the side reactions on the negative electrode side, and the introduction of sulfur-containing additives and the use of the other functional additives are more conducive to improving the role of the functional additives on the positive electrode side, and further improve the positive electrode interface stability, thereby improving the positive and negative electrode interface stability to a certain extent, so that the performance of the battery is further optimized.

[0022] Preferably, the mass proportion of the sulfur-containing additive in the electrolyte is 0.5-1.5 wt %.

[0023] Preferably, the sulfur-containing additive includes 1,3-propane sultone and fluorosulfonyloxybenzene. When the sulfur-containing additive is a combination of the above two materials, the performance of the sulfur-containing additive in the electrolyte is more obvious, and it will not affect the functions of other components in the electrolyte, so it can further improve the overall performance of the electrolyte, and further improve the overall performance of the battery.

[0024] Preferably, the mass ratio of 1,3-propane sultone to fluorosulfonyloxybenzene is 3 to 7: 1. When the mass ratio of the two sulfur-containing additives is within the above range, the combination of the sulfur-containing additives can further optimize the performance of the electrolyte, and further optimize the cycle performance and high temperature storage performance of the battery.

[0025] Preferably, the invention further comprises a carbonate additive, wherein the carbonate additive comprises at least one of vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0026] Preferably, the carbonate additive accounts for 0.2-0.8 wt % in the electrolyte.

[0027] Preferably, the carbonate additive includes fluoroethylene carbonate (FEC).

[0028] Preferably, the electrolyte further comprises a lithium salt additive, and the lithium salt additive comprises at least one of lithium difluorophosphate (LiPO2F2), lithium bis(oxalatoborate) (LiBOB), and lithium difluorobis(oxalatophosphate) (LiODFP).

[0029] Preferably, the mass proportion of the lithium salt additive in the electrolyte is 0.5-1.5 wt %.

[0030] Preferably, the lithium salt additive includes lithium bis(oxalatoborate) (LiBOB). When the lithium salt additive is lithium bis(oxalatoborate), the synergistic effect between the lithium salt additive and the electrolyte components such as the functional additives, sulfur-containing additives and carbonate additives is optimal, that is, the battery prepared using the electrolyte has the best performance, especially in terms of cycle performance and high-temperature storage performance.

[0031] Preferably, the lithium salt includes lithium hexafluorophosphate; and the concentration of lithium hexafluorophosphate in the electrolyte is 1 to 1.5 mol / L.

[0032] Preferably, the organic solvent includes at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0033] Preferably, the organic solvent includes at least two or at least three of ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.

[0034] Preferably, the volume ratio of ethylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate is (20-40):(0-20):(0-20):(30-50).

[0035] According to a second aspect of the present invention, there is provided a battery, characterized in that it comprises the above-mentioned electrolyte.

[0036] Preferably, the battery includes a positive electrode, and the positive electrode includes a ternary nickel cobalt manganese positive electrode material. In particular, the electrolyte provided in the present application shows greater adaptability to the battery with a ternary nickel cobalt manganese positive electrode material system, and the obtained battery has better cycle performance and storage performance.

[0037] Preferably, the chemical formula of the ternary nickel cobalt manganese positive electrode material is Li(Ni x Co y Mn z )O2, where 0.5 ≤ x < 0.8, 0 < y ≤ 0.3, 0 < z ≤ 0.3, and x + y + z = 1.

[0038] Preferably, the above battery includes a negative electrode, and the negative electrode includes graphite. Detailed implementation manners

[0039] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0040] Embodiment 1

[0041] 1. Composition and preparation of the electrolyte

[0042] The electrolyte in this embodiment includes a lithium salt, an organic solvent, a functional additive, a sulfur-containing additive, a carbonate additive, and a lithium salt additive.

[0043] The lithium salt is lithium hexafluorophosphate (LiPF6), and the concentration of lithium hexafluorophosphate in the electrolyte is 1 mol / L.

[0044] The organic solvent is composed of ethylene carbonate, diethyl carbonate, and ethyl methyl carbonate. Based on the total volume of the organic solvent being 100%, the volume fraction of ethylene carbonate is 30%, the volume fraction of diethyl carbonate is 20%, and the volume fraction of ethyl methyl carbonate is 50%.

[0045] The functional additive is with a mass proportion in the electrolyte of 0.3 wt%.

[0046] The sulfur-containing additive is 1,3-propane sultone (PST), with a mass proportion in the electrolyte of 1 wt%.

[0047] The carbonate additive is fluoroethylene carbonate (FEC), with a mass proportion in the electrolyte of 0.5 wt%.

[0048] The lithium salt additive is lithium difluorophosphate (LiPO2F2), with a mass proportion in the electrolyte of 1.0 wt%.

[0049] The preparation of the electrolyte follows the following steps: in an argon atmosphere, adding a formulated amount of carbonate additive, lithium salt additive, sulfur-containing additive and functional additive to an organic solvent, then adding lithium salt, stirring and mixing at a temperature of 10° C. to obtain an electrolyte.

[0050] 2. Preparation of batteries

[0051] Preparation of lithium-ion batteries

[0052] (1) Preparation of positive electrode

[0053] The ternary positive electrode material NCM523, the binder PVDF (polyvinylidene fluoride), and the conductive agent SP (conductive carbon black Super-P) are mixed and stirred evenly in a mass ratio of 94:3:3 to obtain a positive electrode slurry. The positive electrode slurry is then coated on an aluminum foil through a coating process, and a positive electrode sheet is obtained after vacuum drying and cold pressing processes.

[0054] (2) Preparation of negative electrode

[0055] The negative electrode material graphite, conductive agent SP (conductive carbon black Super-P), binder CMC (carboxymethyl cellulose) and SBR (styrene-butadiene rubber) are mixed and stirred evenly in a mass ratio of 94:1:2:3 to obtain a negative electrode slurry, and then the negative electrode slurry is coated on a copper foil through a coating process, and a negative electrode sheet is obtained after vacuum drying and cold pressing processes.

[0056] (3) Selection of electrolyte

[0057] The electrolyte prepared in this example is used.

[0058] (4) Selection of isolation membrane

[0059] Celgard 2400 was selected as the separator for lithium-ion batteries.

[0060] (5) Preparation of lithium-ion batteries

[0061] The positive electrode sheet, isolation film (Celgard2400), and negative electrode sheet are stacked in order, so that the isolation film is between the positive electrode sheet and the negative electrode sheet to play an isolating role. The bare battery cell is placed in an outer packaging shell, and the electrolyte is injected after drying. After vacuum packaging, standing, forming, shaping and other processes, a soft-pack lithium-ion battery is obtained.

[0062] Example 2

[0063] The difference between this embodiment and embodiment 1 is that in the prepared electrolyte, the functional additive is adjusted to The CAS number is 122533-89-5; the rest is consistent with Example 1.

[0064] Example 3

[0065] The difference between this embodiment and embodiment 1 is that in the prepared electrolyte, the functional additive is adjusted to The CAS number is 116396-16-8; the rest is consistent with Example 1.

[0066] Example 4

[0067] The difference between this embodiment and embodiment 1 is that in the prepared electrolyte, the functional additive is adjusted to The CAS number is 137996-26-0; the rest is consistent with Example 1.

[0068] Example 5

[0069] The difference between this embodiment and embodiment 1 is that, in the prepared electrolyte, the mass proportion of the functional additive in the electrolyte is adjusted to 0.6wt%; the rest is consistent with embodiment 1.

[0070] Example 6

[0071] The difference between this embodiment and embodiment 1 is that in the prepared electrolyte, the sulfur-containing additive is adjusted to 1,3-propane sultone and fluorosulfonyloxybenzene, and the mass ratio of the two is 5:1, and the total amount of the sulfur-containing additive added remains unchanged; the rest is consistent with embodiment 1.

[0072] Example 7

[0073] The difference between this embodiment and embodiment 1 is that in the prepared electrolyte, the sulfur-containing additive is adjusted to 1,3-propane sultone and fluorosulfonyloxybenzene, and the mass ratio of the two is 5:1, and the total amount of the sulfur-containing additive added remains unchanged; the rest is consistent with embodiment 1.

[0074] Example 8

[0075] The difference between this embodiment and embodiment 1 is that in the prepared electrolyte, the sulfur-containing additive is adjusted to hydroquinone difluorosulfonate (HBFS); the rest is the same as embodiment 1.

[0076] Example 9

[0077] The difference between this embodiment and the first embodiment is that in the prepared electrolyte, the carbonate additive is adjusted to vinylene carbonate (VC); the rest is the same as the first embodiment.

[0078] Example 10

[0079] The difference between this embodiment and embodiment 6 is that in the prepared electrolyte, the carbonate additive is adjusted to vinylene carbonate (VC); the rest is the same as embodiment 6.

[0080] Embodiment 11

[0081] The difference between this embodiment and embodiment 1 is that in the prepared electrolyte, the lithium salt additive is adjusted to lithium difluorophosphate (LiPO2F2) and lithium bis(oxalatoborate) (LiBOB), and the mass ratio of the two is 2:1, and the total amount of the lithium salt additive added remains unchanged; the rest is consistent with embodiment 1.

[0082] Example 12

[0083] The difference between this embodiment and embodiment 1 is that in the prepared electrolyte, the lithium salt additive is adjusted to lithium bis(oxalatoborate) (LiBOB); the rest is the same as embodiment 1.

[0084] Example 13

[0085] The difference between this embodiment and embodiment 6 is that in the prepared electrolyte, the lithium salt additive is adjusted to lithium bis(oxalatoborate) (LiBOB); the rest is the same as embodiment 6.

[0086] Comparative Example 1

[0087] The difference between this comparative example and Example 1 is that no functional additive is added to the prepared electrolyte; the rest is the same as Example 1.

[0088] Comparative Example 2

[0089] The difference between this comparative example and Example 1 is that in the prepared electrolyte, the functional additive is adjusted to The CAS number is 99-97-8; the rest is consistent with Example 1.

[0090] Comparative Example 3

[0091] The difference between this comparative example and Example 1 is that in the prepared electrolyte, the functional additive is adjusted to The CAS number is 825-44-5; the rest is consistent with Example 1.

[0092] Comparative Example 4

[0093] The difference between this comparative example and Example 1 is that in the prepared electrolyte, the functional additive is adjusted to The CAS number is 58068-69-2; the rest is consistent with Example 1.

[0094] Test Case

[0095] 1. Experimental Construction Method

[0096] The HF content of the electrolytes prepared in all the above embodiments and comparative examples was measured, and the cycle performance, DCR growth rate and high temperature storage performance of the batteries prepared in all the above embodiments and comparative examples were tested. The specific test methods are as follows.

[0097] (1) Cyclic performance test and DCR growth rate test

[0098] Cycle performance: At 45°C, the lithium-ion battery is charged at a constant current of 1.0C (nominal capacity) to a voltage of 4.4V, then charged at a constant voltage of 4.4V to a current ≤0.05C, left for 10 minutes, and then discharged at a constant current of 1C to a cut-off voltage of 2.8V. The above is one charge and discharge cycle. The lithium-ion battery is charged and discharged 300 times at 45°C under the above conditions.

[0099] The capacity retention rate (%) of a lithium-ion battery after N cycles = (discharge capacity at the Nth cycle / initial discharge capacity) × 100%, where N is the number of cycles of the lithium-ion battery.

[0100] DCR growth rate: At 45°C, the battery DCR growth rate test is carried out according to the following steps: ①1C charge to 4.2V, (1 / 50)C cutoff, charge to 100% SOC; ②set aside for 1h, take the final standby voltage as U1; ③2C discharge for 30s, take the voltage at the end of the 10th second as U2; ④calculate, DCIR calculation formula: DCIR=(U2-U1) / 2C*1000; DCIR growth rate calculation formula: DCIR growth rate=DCIR / initial DCIR.

[0101] (3) High temperature storage performance test

[0102] The battery was tested for 5 charge and discharge cycles at room temperature with a charge and discharge rate of 1C, and then charged to a fully charged state at a rate of 1C. The 1C capacity Q0 and battery volume V0 were recorded respectively. The fully charged battery was stored at 60°C for 90 days, and the battery volume V1 and 1C discharge capacity Q1 were recorded. The battery was then charged and discharged at a rate of 1C for 5 weeks at room temperature, and the 1C discharge capacity Q2 was recorded. The experimental data such as the battery's high-temperature storage capacity retention rate, capacity recovery rate, and volume change rate were calculated, and the recorded results are shown in the following table. The calculation formulas used are as follows: Capacity retention rate (%) = Q1 / Q0×100%; Capacity recovery rate (%) = Q2 / Q0×100%; Volume change rate (%) = (V1-V0) / V0×100%.

[0103] The above-mentioned charge-discharge cycle at a charge-discharge rate of 1C or the charge-discharge rate of 1C means that

[0104] 1.0C (nominal capacity) constant current charge to the voltage of 4.4V, then 4.4V constant voltage charge to the current ≤ 0.05C, after leaving for 10 minutes, 1C constant current discharge to 2.8V, the above is one charge and discharge cycle or one charge and discharge.

[0105] 2. Experimental results

[0106] The relevant performance test results of the batteries prepared in all the above embodiments and comparative examples are shown in Table 1.

[0107] Table 1. Test results of relevant performance of the batteries prepared in the examples and comparative examples

[0108]

[0109] It can be seen from Table 1 that the battery prepared using the electrolyte provided by the present invention not only has good high temperature (45°C) cycle performance, but also has good high temperature (60°C) storage performance. Therefore, the electrolyte provided by the present invention can achieve the effect of further optimizing the battery performance, with specific reference to Examples 1 to 13.

[0110] The electrolyte of comparative example 1 has no functional additives, the electrolyte of comparative example 2 has cyano, sulfate and benzene rings connected by sulfate in the functional additives, the electrolyte of comparative example 3 has no cyano, amine and benzene rings connected by amine in the functional additives, and the electrolyte of comparative example 4 has no sulfate and benzene rings connected by sulfate in the functional additives; the above factors cause a significant decline in battery performance, especially the electrolyte of comparative example 1 has no functional additives, resulting in a more significant decline in both high temperature cycle performance and high temperature storage performance of the battery. Therefore, the above results show that the introduction of specific functional additives in the present invention plays a key role in optimizing the performance of the electrolyte and the battery, and the specific functional groups of the functional additives also have a great influence on the performance of the electrolyte and the battery.

[0111] Further comparing Example 1 with Examples 2 to 4, the alkyl chain after the secondary amine in the functional additive of Example 2 is longer, the alkyl chain after the secondary amine in the functional additive of Example 3 is longer, and there is also an alkenyl group in R3, the amine group in the functional additive is a primary amine, and there is also a methyl group in R1. Finally, the high temperature cycle performance of Examples 2 to 4 is higher than that of Example 1, the DCR growth rate is higher than that of Example 1, and in the high temperature storage performance, the volume expansion rate is higher than that of Example 1, and the capacity retention rate and capacity recovery rate are both worse than those of Example 1. This shows that even if there are small changes in the structural formula of the functional additive, it will affect the performance of the functional additive in the electrolyte, and then affect the overall performance of the electrolyte, and ultimately lead to a certain degradation of the battery performance.

[0112] Comparing Example 1 and Example 5, the content of the functional additive in Example 5 is too high, which also causes a decrease in the high-temperature cycle performance and high-temperature storage performance of the battery in Example 5. This is because too much functional additive will affect its solubility and the role of other components of the electrolyte, thereby causing a decrease in the overall performance of the battery, and ultimately causing the battery performance to deteriorate.

[0113] Comparing Example 1 with Examples 6 to 8, the sulfur-containing additive in Example 6 is 1,3-propane sultone and fluorosulfonyloxybenzene, and the mass ratio is in the range of 3 to 7:1; the sulfur-containing additive in Example 7 is 1,3-propane sultone and fluorosulfonyloxybenzene, but the mass ratio is not in the range of 3 to 7:1; the sulfur-containing additive in Example 8 is hydroquinone difluorosulfonate (HBFS); and the various performances of the battery in Example 6 are better than those in Example 1, and the various performances in Examples 7 and 8 are worse than those in Example 1. Comparing Example 1 with Example 9, the carbonate additive in Example 9 is vinylene carbonate (VC), and the various performances of the battery in Example 9 are worse than those in Example 1. Comparing Example 6 with Example 10, the carbonate additive in Example 10 is vinylene carbonate (VC), and the various performances of the battery in Example 10 are worse than those in Example 6. Comparing Example 1 with Examples 11-12, the lithium salt additive in Example 11 is lithium difluorophosphate (LiPO2F2) and lithium bis(oxalate borate) (LiBOB), and the lithium salt additive in Example 12 is lithium bis(oxalate borate) (LiBOB), and the various performances of the battery in Example 11 are better than those in Example 1, and the various performances of the battery in Example 12 are worse than those in Example 1. Comparing Example 6 with Example 13, the lithium salt additive in Example 13 is lithium bis(oxalate borate) (LiBOB), and the various performances of the battery in Example 13 are better than those in Example 6. The above results show that for sulfur-containing additives, carbonate additives, and lithium salt additives, the selection of their types and / or mass ratios will have a certain effect on the performance of the electrolyte, and thus lead to a certain effect on the performance of the final battery. Therefore, further optimizing the materials or the matching of the materials of sulfur-containing additives, carbonate additives, and lithium salt additives, and limiting specific ratios, can be more conducive to exerting a better overall performance of the electrolyte, and further optimizing the performance of the battery.

[0114] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention is described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the technical solutions of the present invention can be modified or equivalently replaced, but these modifications or replacements are all within the protection scope of the present invention.

Claims

1. An electrolyte, characterized in that: Including lithium salts, organic solvents, and functional additives; The structural formula of the functional additive is: Wherein, R1 includes at least one of a primary amine group, a secondary amine group, and a tertiary amine group; At least one of R4 and R5 includes a cyano group.

2. The electrolyte according to claim 1, characterized in that: R2 includes at least one of hydrogen, alkyl chain, substituted alkyl chain, and halogen; R3 includes at least one of an alkyl chain, a substituted alkyl chain, an alkyl chain containing a double bond or a triple bond, and a substituted alkyl chain containing a double bond or a triple bond, and the number of carbon atoms in R3 is ≥0.

3. The electrolyte according to claim 1, characterized in that: R4 and R5 independently include cyano.

4. The electrolyte according to claim 1, characterized in that The structural formula of the functional additive is: The functional additive accounts for 0.1-0.5% by weight in the electrolyte.

5. The electrolyte according to claim 1, characterized in that: Also included is a sulfur-containing additive, wherein the sulfur-containing additive includes at least one of 1,3-propane sultone, vinyl sulfite, vinyl sulfite, vinyl sulfate, methylene disulfonate, thiophene derivatives, fluorosulfonyloxybenzene, phenyl methanesulfonate, and hydroquinone difluorosulfonate; The sulfur-containing additive accounts for 0.5-1.5 wt % in the electrolyte.

6. The electrolyte according to claim 5, characterized in that: The sulfur-containing additive includes the 1,3-propane sultone and the fluorosulfonyloxybenzene; The mass ratio of the 1,3-propane sultone to the fluorosulfonyloxybenzene is 3 to 7:

1.

7. The electrolyte according to claim 1, characterized in that: Also included is a carbonate additive, wherein the carbonate additive includes at least one of vinylene carbonate and fluoroethylene carbonate; The carbonate additive accounts for 0.2-0.8 wt % in the electrolyte.

8. The electrolyte according to claim 1, characterized in that: Also included is a lithium salt additive, wherein the lithium salt additive includes at least one of lithium difluorophosphate, lithium bis(oxalatoborate), and lithium difluorobis(oxalatophosphate); The lithium salt additive accounts for 0.5-1.5 wt % in the electrolyte.

9. The electrolyte according to claim 1, characterized in that: The lithium salt additive includes the lithium bis(oxalatoborate).

10. A battery, characterized in that: Comprising the electrolyte as claimed in any one of claims 1 to 9.

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