Electrolyte additive, electrolyte containing same and battery

Abstract

The present invention provides an electrolyte additive, an electrolyte containing the same, and a battery. The electrolyte additive comprises an additive A having the following general formula I; X is independently selected from one of vinyl, propenyl, propargyl, acetonitrile, propionitrile, methylisocyanate, 1-fluoromethyl, 2-fluoromethyl, and 3-fluoromethyl groups. The electrolyte additive provided by the present invention has a positive and negative electrode film-forming effect. By reducing side reactions at the electrolyte interface with the positive and negative electrodes, it improves the battery's capacity and voltage decay during high-voltage cycling, thereby increasing the battery's cycle life. Furthermore, the electrolyte additive provided by the present invention can be directly added to the battery electrolyte for use, which is simple to operate, has a significant effect, and is suitable for industrial applications. #imgabs0#

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to an electrolyte additive, an electrolyte containing the same, and a battery Background Art

[0002] The continued prosperity of computers, communications, and consumer electronics has led to rapid development of the lithium-ion battery industry. The rise of new energy vehicles in recent years, in particular, has not only boosted the development of power lithium-ion batteries but also placed higher demands on their energy density and safety performance. Electric vehicle range has become one of the most important performance indicators for consumers, and the battery's energy density determines the vehicle's single-trip range. Improving battery energy density within limited space and weight has become a hot topic of research. Increasing the operating voltage of cathode materials is one of the primary approaches to improving the energy density of lithium-ion batteries. Currently, high-voltage cathode materials such as LNMO, high-voltage ternary materials, high-voltage lithium cobalt oxide, and layered lithium-rich oxide (LLO) have become a research hotspot. As the voltage of lithium-ion batteries continues to increase, the cathode material will have a higher electrode potential, leading to more intense electrolyte oxidative decomposition and interfacial reactions at the cathode. As the battery undergoes repeated charge and discharge cycles, its internal resistance gradually increases, resulting in a decrease in cycle capacity and rapid voltage decay. Currently, researchers mainly modify the positive electrode materials, such as surface coating, material microstructure design, element doping, etc., to improve the problems of positive electrode oxidation decomposition and positive electrode interface reaction caused by the above-mentioned high-voltage positive electrode materials. However, these material modification methods are complex and costly. Summary of the Invention

[0003] The present invention provides an electrolyte additive, an electrolyte containing the same, and a battery. The electrolyte additive has a positive and negative electrode film-forming effect, and improves the capacity decay and voltage decay of the battery during high-voltage cycling by reducing side reactions at the interface between the electrolyte and the positive and negative electrodes, thereby increasing the cycle life of the battery. In addition, the electrolyte additive provided by the present invention can be directly added to the electrolyte of the battery for use, is simple to operate, has obvious effects, and is conducive to industrial application.

[0004] According to a first aspect of the present invention, there is provided an electrolyte additive, the electrolyte additive comprising an additive A, wherein the additive A has the following general formula I:

[0005]

[0006] X is independently selected from one of vinyl, propenyl, propargyl, acetonitrile, propionitrile, methyl isocyanate, 1-fluoromethyl, 2-fluoromethyl, and 3-fluoromethyl.

[0007] The electrolyte additive provided by the present invention contains additive A, wherein additive A has the above-mentioned general structural formula I. Since X in the structure of the above-mentioned additive A contains an unsaturated functional group and can be oxidized or reduced, the additive is applied to the battery electrolyte. On the one hand, the above-mentioned additive A can form a uniform and dense CEI film on the positive electrode, effectively inhibiting the dissolution of TMs metal ions and the release of oxygen, thereby reducing side reactions at the electrolyte and positive electrode interface and providing a certain protective effect on the positive electrode interface. On the other hand, the above-mentioned additive A can also form a uniform and dense SEI film on the negative electrode, preventing TMs metal ions from depositing on the negative electrode surface, making the SEI film more stable during the cycle process and reducing the loss of active lithium. The electrolyte additive provided by the present invention has a positive and negative electrode film-forming effect. By reducing side reactions at the electrolyte and positive and negative electrode interfaces and in situ regulating the physical structure and chemical composition of the CEI film and SEI film, the internal resistance of the battery can be stabilized within a certain range, thereby improving the capacity decay and voltage decay of the battery during high-voltage cycling, thereby improving the cycle life of the battery. Furthermore, the electrolyte additive provided by the present invention can be directly added to the electrolyte of the battery for use, which is simple to operate and has obvious effects, and is conducive to industrial application.

[0008] Preferably, the above-mentioned electrolyte additives also include additive B, additive C and additive D; additive B is selected from at least one of vinylene carbonate (VC) and fluoroethylene carbonate (FEC); additive C is selected from at least one of LiFSI, LiPO2F2, LiBOB, and LiODFP; additive D is selected from at least one of 1,3-propanesulfonate (PS), 1,3-propylenesulfonate (PST), and dithiothreitol (DTD).

[0009] The electrolyte additives involved in this scheme also contain additives B, additives C and additives D, among which additive B can assist the above-mentioned additive A in forming a dense SEI film at the negative electrode, while additives C and additives D participate in the film formation process of the positive and negative electrodes at the same time, which is beneficial to assist the above-mentioned additive A in forming dense films at the positive and negative electrodes respectively, reducing the side reactions at the interface between the electrolyte and the positive and negative electrodes, making the internal resistance of the battery more stable, and thereby improving the cycle performance of the battery during the charge and discharge process.

[0010] Preferably, calculated by mass ratio, additive A: additive B: additive C: additive D = 0.3-1: 0-1: 0.5-1: 0.5-3.

[0011] According to a second aspect of the present invention, an electrolyte is provided, comprising the electrolyte additive.

[0012] Preferably, calculated as a percentage by mass, the content of the electrolyte additive in the above electrolyte is 0 to 5 wt %.

[0013] Preferably, calculated as a percentage by mass, the content of the electrolyte additive in the above electrolyte is 3.5-5 wt %.

[0014] Preferably, calculated by mass percentage, in the above electrolyte, the content of additive A is 0.3-1 wt %, the content of additive B is 0-1 wt %, the content of additive C is 0.5-1 wt %, and the content of additive D is 0.5-3 wt %.

[0015] This solution limits the mass ratio of additives A, B, C, and D in the electrolyte to a reasonable range, and applies the electrolyte to the battery, so that the electrolyte can stably form a uniform and dense film at the positive and negative electrodes, reducing side reactions at the interface between the electrolyte and the positive and negative electrodes, which is beneficial to improving the cycle performance of the battery during the charge and discharge process. If the amount of additive B added is too small, a dense SEI film cannot be formed at the negative electrode, while an excessive amount will cause the battery impedance to be too high and gas to be generated at high temperature; if the amount of additive C added is too small, it is difficult to form a dense CEI film and SEI film at the positive and negative electrodes respectively, while an excessive amount will cause additive C to be unable to completely dissolve in the electrolyte, thereby affecting the performance of the electrolyte and the battery; if the amount of additive D added is too small, it is difficult to form a dense CEI film and SEI film at the positive and negative electrodes respectively, while an excessive amount will cause the impedance of the CEI film and SEI film to be too large, thereby reducing the cycle performance of the battery. This solution enables the battery to have good cycle performance by limiting the mass ratio of additives A, additive B, additive C and additive D in the electrolyte to a reasonable range.

[0016] Preferably, the electrolyte further comprises a lithium salt and an organic solvent.

[0017] Preferably, the lithium salt is selected from at least one of LiPF6 and LiBF4.

[0018] Preferably, the organic solvent is obtained by mixing cyclic carbonate, chain carbonate, and chain carboxylic acid ester in a mass ratio of 1-15:20-70:5-20.

[0019] Preferably, the cyclic carbonate includes at least one of fluoroethylene carbonate and ethylene carbonate.

[0020] Preferably, the chain carbonate includes diethyl carbonate.

[0021] Preferably, the chain carboxylic acid ester includes ethyl difluoroacetate.

[0022] Preferably, calculated as a percentage by mass, the content of the organic solvent in the above electrolyte is 80-90 wt %.

[0023] Preferably, calculated as a percentage by mass, the content of lithium salt in the above electrolyte is 10-15 wt%.

[0024] Preferably, the electrolyte is prepared by the following steps: adding the electrolyte additive and lithium salt to an organic solvent, and stirring evenly at 8-12° C. to prepare the electrolyte.

[0025] According to a third aspect of the present invention, a battery is provided, comprising the above-mentioned electrolyte.

[0026] The electrolyte additive provided by the present invention is applied to the preparation of the electrolyte. During actual use, the battery containing the electrolyte can form a uniform and dense film on the positive and negative electrodes, reduce the side reactions at the interface between the electrolyte and the positive and negative electrodes, and have a certain protective effect on the positive and negative electrode interfaces, making the internal resistance of the battery more stable, thereby improving the capacity decay and voltage decay of the battery during the high-voltage cycle process, thereby giving the battery good cycle performance. DETAILED DESCRIPTION

[0027] The following is a further clear and complete description of the technical features of the technical solution provided by the present invention in conjunction with specific embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of the present invention.

[0028] In the specific embodiment of the present invention, the The method used in Example 9 The method used in Example 10 All of them were prepared according to the synthesis method given in the foreign journal article "Cyclic tertiary sulfamates: Selective inhibition of the tumor-associated carbonic anhydrases IX and XII by N-and O-substituted acesulfame derivatives" (European Journal of Medicinal Chemistry 84 (2014) 240-246).

[0029] Example 1

[0030] This embodiment provides an electrolyte comprising 3.5 wt % of an electrolyte additive, 10 wt % of a lithium salt, and 86.5 wt % of an organic solvent;

[0031] Among them, the electrolyte additives are Vinylene carbonate (VC), LiPO2F2 and 1,3-propane sultone (PS) were mixed in a mass ratio of 0.5:0.5:0.5:2;

[0032] The lithium salt is lithium hexafluorophosphate (LiPF6);

[0033] The organic solvent is obtained by mixing fluoroethylene carbonate, ethylene carbonate, ethyl difluoroacetate and diethyl carbonate in a mass ratio of 5:5:15:45;

[0034] The electrolyte provided in this embodiment is prepared by the following steps: adding electrolyte additives and lithium salt to an organic solvent under a nitrogen atmosphere, and stirring at 10° C. to obtain the electrolyte of this embodiment.

[0035] Example 2

[0036] This embodiment provides an electrolyte comprising 5 wt % of an electrolyte additive, 15 wt % of a lithium salt, and 80 wt % of an organic solvent;

[0037] Among them, the electrolyte additives are Vinylene carbonate (VC), LiPO2F2 and 1,3-propane sultone (PS) were mixed in a mass ratio of 1:1:1:3;

[0038] The lithium salt is lithium hexafluorophosphate (LiPF6);

[0039] The organic solvent is prepared by mixing fluoroethylene carbonate, ethylene carbonate, ethyl difluoroacetate and diethyl carbonate in a mass ratio of 7.5:7.5:20:70;

[0040] The electrolyte provided in this embodiment is prepared by the following steps: adding electrolyte additives and lithium salt to an organic solvent under a nitrogen atmosphere, and stirring evenly at 12° C. to obtain the electrolyte of this embodiment.

[0041] Example 3

[0042] This embodiment provides an electrolyte comprising 3.5 wt % of an electrolyte additive, 12 wt % of a lithium salt, and 84.5 wt % of an organic solvent;

[0043] Among them, the electrolyte additives are LiPO2F2 and 1,3-propanesulfonate (PS) were mixed in a mass ratio of 0.3:0.8:0.5;

[0044] The lithium salt is lithium hexafluorophosphate (LiPF6);

[0045] The organic solvent is prepared by mixing fluoroethylene carbonate, ethylene carbonate, ethyl difluoroacetate and diethyl carbonate in a mass ratio of 0.5:0.5:5:20;

[0046] The electrolyte provided in this embodiment is prepared by the following steps: adding electrolyte additives and lithium salt to an organic solvent under a nitrogen atmosphere, and stirring evenly at 8° C. to obtain the electrolyte of this embodiment.

[0047] Example 4

[0048] This embodiment provides an electrolyte. Compared with embodiment 1, the difference in composition is that the electrolyte additive consists of Vinylene carbonate (VC), LiPO2F2 and 1,3-propane sultone (PS) were mixed in a mass ratio of 0.5:3:0.5:2. Except for the above differences, the materials, formulations and preparation procedures used in this example were strictly consistent with those in Example 1.

[0049] Example 5

[0050] This embodiment provides an electrolyte. Compared with embodiment 1, the difference in composition is that the electrolyte additive consists of Vinylene carbonate (VC), LiPO2F2 and 1,3-propane sultone (PS) were mixed in a mass ratio of 0.5:0.5:0.1:2. Except for the above differences, the materials, formulations and preparation procedures used in this example were strictly consistent with those in Example 1.

[0051] Example 6

[0052] This embodiment provides an electrolyte. Compared with embodiment 1, the difference in composition is that the electrolyte additive consists of Vinylene carbonate (VC), LiPO2F2 and 1,3-propane sultone (PS) were mixed in a mass ratio of 0.5:0.5:2:2. Except for the above differences, the materials, formulations and preparation procedures used in this example were strictly consistent with those in Example 1.

[0053] Example 7

[0054] This embodiment provides an electrolyte. Compared with embodiment 1, the difference in composition is that the electrolyte additive consists of Vinylene carbonate (VC), LiPO2F2 and 1,3-propane sultone (PS) were mixed in a mass ratio of 0.5:0.5:0.5:0.1. Except for the above differences, the materials, formulations and preparation procedures used in this example were strictly consistent with those in Example 1.

[0055] Example 8

[0056] This embodiment provides an electrolyte. Compared with embodiment 1, the difference in composition is that the electrolyte additive consists of Vinylene carbonate (VC), LiPO2F2 and 1,3-propane sultone (PS) were mixed in a mass ratio of 0.5:0.5:0.5:4. Except for the above differences, the materials, formulations and preparation procedures used in this example were strictly consistent with those in Example 1.

[0057] Example 9

[0058] This embodiment provides an electrolyte. Compared with embodiment 1, the difference in composition is that the electrolyte additive consists of Vinylene carbonate (VC), LiPO2F2 and 1,3-propane sultone (PS) were mixed in a mass ratio of 0.5:0.5:0.5:2. Except for the above differences, the materials, formulations and preparation procedures used in this example were strictly consistent with those in Example 1.

[0059] Example 10

[0060] This embodiment provides an electrolyte. Compared with embodiment 1, the difference in composition is that the electrolyte additive consists of Vinylene carbonate (VC), LiPO2F2 and 1,3-propane sultone (PS) were mixed in a mass ratio of 0.5:0.5:0.5:2. Except for the above differences, the materials, formulations and preparation procedures used in this example were strictly consistent with those in Example 1.

[0061] Comparative Example 1

[0062] This comparative example provides an electrolyte, which is different from Example 1 in that the electrolyte additive does not contain Except for the above differences, the materials, formula ratios and preparation operations used in this comparative example are strictly consistent with those in Example 1.

[0063] Comparative Example 2

[0064] This embodiment provides an electrolyte comprising 10 wt % of a lithium salt and 90 wt % of an organic solvent;

[0065] The lithium salt is lithium hexafluorophosphate (LiPF6);

[0066] The organic solvent is obtained by mixing fluoroethylene carbonate, ethylene carbonate, ethyl difluoroacetate and diethyl carbonate in a mass ratio of 5:5:15:45;

[0067] The electrolyte provided in this example was prepared by the following steps: adding lithium salt to an organic solvent under a nitrogen atmosphere, and stirring evenly at 10° C. to obtain the electrolyte of this comparative example.

[0068] Test Case

[0069] The electrolytes provided in Examples 1 to 10 and Comparative Examples 1 to 2 were applied to lithium-ion batteries, and relevant performance tests were conducted using the lithium-ion batteries. The specific preparation method of the lithium-ion batteries used for the test is as follows: a slurry of graphite, a conductive agent, acetylene black, and a binder, CMC and SBR, was prepared in a mass percentage of 94:1:2:3 and coated on a copper foil current collector. The slurry was then vacuum-dried to obtain a negative electrode sheet. A positive electrode material, 0.25Li2MnO3·0.75LiMn 0.375 Ni 0.375 Co 0.25 A slurry of O2, conductive agent acetylene black, and binder PVDF (94:3:3 mass ratio) was prepared and coated onto an aluminum foil current collector. The slurry was then vacuum-dried to produce a positive electrode. Pouch cells were assembled with the positive and negative electrodes, along with a Celgard 2400 separator and the electrolytes prepared in Examples 1-10 and Comparative Examples 1-2, respectively. Electrochemical testing was performed using a Xinwei charge-discharge test cabinet.

[0070] (1) Normal temperature cycle performance test

[0071] At 25°C, charge the lithium-ion battery at a constant current of 0.5C (nominal capacity) to a voltage of 4.6V, then charge at a constant voltage of 4.6V to a current of ≤0.05C. After 10 minutes of storage, discharge at a constant current of 1C to a cut-off voltage of 2.5V. This constitutes one charge-discharge cycle. Perform 1000 charge-discharge cycles of the lithium-ion battery at 25°C under the above conditions.

[0072] 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.

[0073] The average voltage (V) of a lithium-ion battery after N cycles = discharge energy of the Nth cycle / discharge capacity of the Nth cycle, where N is the number of cycles of the lithium-ion battery.

[0074] (2) High temperature cycle performance test:

[0075] At 45°C, the lithium-ion battery is charged at a constant current of 1.0C (nominal capacity) to a voltage of 4.6V, then charged at a constant voltage of 4.6V to a current of ≤0.05C. After 10 minutes, it is discharged at a constant current of 1C to a cut-off voltage of 2.5V. The above is one charge and discharge cycle. The lithium-ion battery is subjected to 800 charge and discharge cycles at 45°C under the above conditions.

[0076] 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.

[0077] The average voltage (V) of a lithium-ion battery after N cycles = discharge energy of the Nth cycle / discharge capacity of the Nth cycle, where N is the number of cycles of the lithium-ion battery.

[0078] Table 1 Relevant performance test results of lithium-ion batteries

[0079]

[0080] The relevant performance test results of lithium ion batteries are shown in Table 1. The electrolytes provided in Examples 1 to 3 contain 0 to 5 wt% electrolyte additives. The electrolyte additives are Vinylene carbonate (VC), LiPO2F2 and 1,3-propane sulfone (PS) are mixed in a mass ratio of 0.3-1:0-1:0.5-1:0.5-3. When the electrolyte is applied to a lithium-ion battery, the electrolyte can stably form a uniform and dense film at the positive and negative electrodes, reduce the side reaction at the interface between the electrolyte and the positive and negative electrodes, and is beneficial to improving the cycle performance of the lithium-ion battery during the charge and discharge process. Specifically, the capacity retention rates of the lithium-ion battery after 1000 cycles at 25°C and 800 cycles at 45°C are 78.1-86.5% and 75.3-83.8%, respectively. Compared with Examples 1 to 2, the electrolyte provided in Example 3 does not contain VC. When it is applied to lithium-ion batteries, it is difficult to form a dense SEI film lithium at the negative electrode, which reduces the cycle performance of the lithium-ion battery. The capacity retention rates after 1000 cycles at 25°C and 800 cycles at 45°C are 78.1% and 75.3%, respectively, which are significantly lower than those in Examples 1 to 2.

[0081] Compared with Example 1, the electrolyte additive contained in the electrolyte provided in Example 4 is Vinylene carbonate (VC), LiPO2F2 and 1,3-propanesulfonate (PS) are mixed in a mass ratio of 0.5:3:0.5:2. When the electrolyte is applied to a lithium-ion battery, the capacity retention rates of the lithium-ion battery after 1000 cycles at 25°C and 800 cycles at 45°C are 84.5% and 82.3%, respectively, which are both lower than those in Example 1. This is mainly because the VC content in the electrolyte is too high, which will lead to a large impedance of the lithium-ion battery and high-temperature gas generation, thereby causing a decrease in the cycle performance of the lithium-ion battery.

[0082] Compared with Example 1, the electrolyte provided in Example 5 contains the electrolyte additives, The mass ratio of vinylene carbonate (VC), LiPO2F2 and 1,3-propanesulfonate (PS) is 0.5:0.5:0.1:2. When the electrolyte is applied to a lithium-ion battery, the capacity retention rates of the lithium-ion battery after 1000 cycles at 25°C and 800 cycles at 45°C are 85.0% and 82.3%, respectively, which are slightly lower than those in Example 1. The electrolyte additives contained in the electrolyte provided in Example 6 are The mass ratio of vinylene carbonate (VC), LiPO2F2 and 1,3-propanesulfonate (PS) is 0.5:0.5:2:2. When the electrolyte is applied to a lithium-ion battery, the capacity retention rates of the lithium-ion battery after 1000 cycles at 25°C and 800 cycles at 45°C are 85.5% and 82.8%, respectively, which are slightly lower than those in Example 1. The reason for the above phenomenon is that the amount of LiPO2F2 added in the electrolyte provided in Example 5 is too small, making it difficult to form a dense CEI film and SEI film on the positive and negative electrodes, respectively, resulting in a decrease in the cycle performance of the lithium-ion battery. The amount of LiPO2F2 added in the electrolyte provided in Example 6 is too large, resulting in the inability of LiPO2F2 to be completely dissolved in the electrolyte, thereby affecting the cycle performance of the electrolyte and the lithium-ion battery.

[0083] Compared with Example 1, the electrolyte provided in Example 7 contains the electrolyte additives: The mass ratio of vinylene carbonate (VC), LiPO2F2 and 1,3-propanesulfonate (PS) is 0.5:0.5:0.5:0.1. When the electrolyte is applied to a lithium-ion battery, the capacity retention rates of the lithium-ion battery after 1000 cycles at 25°C and 800 cycles at 45°C are 83.0% and 80.3%, respectively, which are slightly lower than those in Example 1. The electrolyte additives contained in the electrolyte provided in Example 8 are The mass ratio of vinylene carbonate (VC), LiPO2F2 and 1,3-propanesulfonate (PS) is 0.5:0.5:0.5:4. When the electrolyte is applied to a lithium-ion battery, the capacity retention rates of the lithium-ion battery after 1000 cycles at 25°C and 800 cycles at 45°C are 85.7% and 83.0%, respectively, which are slightly lower than those in Example 1. The reason for the above phenomenon is that the amount of 1,3-propanesulfonate (PS) added to the electrolyte provided in Example 7 is too small, making it difficult to form a dense CEI film and SEI film on the positive and negative electrodes, respectively. The amount of 1,3-propanesulfonate (PS) added to the electrolyte provided in Example 8 is too large, resulting in excessive impedance of the CEI film and SEI film. All of the above situations will lead to a decrease in the cycle performance of the lithium-ion battery.

[0084] Compared with Example 1, the electrolyte provided in Example 9 uses Alternative The electrolyte provided in Example 10 uses Alternative The electrolytes provided in Examples 9 and 10 were applied to lithium-ion batteries. The capacity retention rates of the lithium-ion batteries after 1000 cycles at 25° C. and 800 cycles at 45° C. were comparable to those of Example 1.

[0085] The electrolyte provided in Comparative Example 1 does not contain any electrolyte additives. When the electrolyte is applied to a lithium-ion battery, the capacity retention rates of the lithium-ion battery after 1000 cycles at 25°C and 800 cycles at 45°C are 68.0% and 72.4%, respectively, which are significantly lower than those in Example 1. However, the electrolyte additive also contains vinylene carbonate (VC), LiPO2F2 and 1,3-propanesulfonate (PS), so that the corresponding average voltage can still be basically consistent with that in Example 1. The electrolyte provided in Comparative Example 2 does not contain electrolyte additives. When the electrolyte is applied to a lithium-ion battery, the capacity retention rates of the lithium-ion battery after 1000 cycles at 25°C and 800 cycles at 45°C are 40.0% and 45.2%, respectively, and the corresponding average voltages are 3.4500V and 3.4300V, respectively. The capacity retention rate and average voltage are significantly lower than those in Example 1.

[0086] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents, but these modifications or replacements are all within the scope of protection of the present invention.

Claims

1. An electrolyte, characterized in that: The electrolyte includes an electrolyte additive; The electrolyte additive includes additive A, and the additive A has the following general formula I: , formula Ⅰ; The X is independently selected from one of vinyl, propenyl, propargyl, acetonitrile, propionitrile, and methyl isocyanate.

2. The electrolyte according to claim 1, wherein: The electrolyte additives also include additive B, additive C and additive D; The additive B is selected from at least one of vinylene carbonate and fluoroethylene carbonate; The additive C is selected from at least one of LiFSI, LiPO2F2, LiBOB, and LiODFP; The additive D is selected from at least one of 1,3-propane sultone, 1,3-propylene sultone, and vinyl sulfate.

3. The electrolyte according to claim 2, wherein: Calculated according to the mass ratio, the additive A: the additive B: the additive C: the additive D=0.3~1:0~1:0.5~1:0.5~3.

4. The electrolyte according to claim 1, wherein: Calculated by mass percentage, the content of the electrolyte additive in the electrolyte is 0-5wt%.

5. The electrolyte according to claim 1, wherein: The electrolyte further comprises a lithium salt and an organic solvent; The lithium salt is selected from at least one of LiPF6 and LiBF4; The organic solvent is obtained by mixing cyclic carbonate, chain carbonate and chain carboxylate in a mass ratio of 1-15:20-70:5-20.

6. The electrolyte according to claim 5, wherein: The cyclic carbonate includes at least one of fluoroethylene carbonate and ethylene carbonate; The chain carbonate includes diethyl carbonate; The chain carboxylic acid ester includes ethyl difluoroacetate.

7. The electrolyte according to claim 5, wherein: Calculated by mass percentage, the content of the organic solvent in the electrolyte is 80-90wt%.

8. The electrolyte according to claim 5, wherein: Calculated by mass percentage, the content of the lithium salt in the electrolyte is 10-15wt%.

9. A battery, characterized in that: Comprising the electrolyte according to any one of claims 1 to 8.

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