An electrolyte and a battery comprising the same

Abstract

The application provides an electrolyte and a battery containing the same. The electrolyte comprises a lithium salt, an organic solvent and a first functional additive. The structural formula of the first functional additive is: in the electrolyte, the first functional additive with a specific structure is contained, the specific functional additive can form a film on the positive and negative electrode sides, and the stability of the positive and negative electrodes is promoted. In particular for a silicon negative electrode, the specific functional additive promotes the stable growth of an SEI film on the negative electrode side, effectively alleviates the volume expansion effect of silicon, and thus effectively improves the electrochemical performance of the battery, in particular the cycle performance and rate performance of a silicon-based battery.

Description

Technical Field

[0001] This application belongs to the field of lithium-ion battery technology, specifically relating to an electrolyte and a battery containing the electrolyte. Background Technology

[0002] Silicon is widely recognized as the most promising anode material for lithium-ion batteries, possessing the following advantages: (1) High capacity. After complete alloying, silicon forms a Li-silicon alloy with a theoretical specific capacity of approximately 4200 mAh / g; (2) Low lithium insertion / extraction potential. When matched with the cathode, silicon operates at a potential of approximately 0.4V, resulting in a higher output voltage and higher energy density; (3) Abundant reserves, good environmental compatibility, good environmental friendliness, and electrochemical stability. These advantages make silicon one of the most promising materials for next-generation high-performance battery anode materials.

[0003] However, like all alloyed lithium storage anode materials, silicon faces an unavoidable problem: rapid volume expansion during cycling, which leads to poor cycling stability. During alloying, the volume of the silicon-lithium alloy expands to 3 to 4 times that of the un-lithium-intercalated state, and then shrinks rapidly during dealloying, which severely restricts the application of silicon anodes.

[0004] During the lithiation and delithiation process, the large volume change of silicon is the primary reason for the sharp decline in battery capacity. The main limiting mechanisms are as follows: (1) The large volume change causes huge stress inside the material. In subsequent cycles, the silicon particles gradually break or even pulverize. (2) With the continuous volume expansion and contraction of the cycle, most of the active materials lose electrical contact with adjacent active materials, conductive agent network and current collector, resulting in the phenomenon of "self-isolation" of silicon material. At the same time, the electrode plate cracks and breaks, which significantly reduces the conductivity. (3) The volume change of silicon will cause the SEI film to break. The fresh silicon surface will be exposed to the electrolyte, resulting in the continuous generation of the SEI film and the continuous consumption of electrolyte. As the cycle continues, a thick SEI film will cover the surface of the silicon particles.

[0005] Developing novel electrolytes compatible with silicon anodes is one of the effective means to improve the electrochemical performance of silicon anodes. However, currently available commercial electrolytes are more suitable for graphite anodes than silicon-based anodes, mainly because organic solvents are reduced and decomposed within the lithiation voltage range of silicon. Furthermore, due to the volume change of silicon, each expansion is accompanied by electrolyte decomposition, resulting in the formation of a thick SEI film at the interface, causing a rapid decline in electrode performance. Therefore, developing electrolytes suitable for the lithiation characteristics of silicon anodes is of great significance for the electrochemical performance of silicon-based lithium batteries, including cycle performance, rate performance, and energy density. Summary of the Invention

[0006] To address the problems and shortcomings of existing technologies, this application provides an electrolyte and a battery containing the electrolyte, wherein the electrolyte contains a first functional additive with a specific structure. This specific functional additive can form films on the positive and negative electrode sides, promoting the stability of the positive and negative electrodes. In particular, for silicon negative electrodes, the specific functional additive promotes the stable growth of the SEI film on the negative electrode side, effectively mitigating the silicon volume expansion effect, thereby effectively improving the electrochemical performance of the battery, especially silicon-based batteries, such as cycle performance and rate performance.

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

[0008]

[0009] In the electrolyte of this application, the first functional additive contains pyridine and ester functional groups, which effectively improves the stability of the electrolyte and the electrochemical performance of the battery. Firstly, the pyridine ring has a certain aromaticity and conjugated structure, which can increase the chemical stability of the electrolyte, making it less prone to redox decomposition reactions within the battery's operating voltage range and extending the electrolyte's lifespan. The nitrogen atom in pyridine has lone pairs of electrons, which can interact with lithium ions, promoting lithium ion dissociation and transport, and improving the migration efficiency of lithium ions in the electrolyte, thereby improving the battery's cycle performance and rate performance. Secondly, the ester group has a certain polarity, which can interact with solutes such as lithium salts in the electrolyte, helping the solutes to dissolve and disperse better in the electrolyte, thereby improving the ionic conductivity of the electrolyte, which is beneficial for lithium ion transport in the electrolyte, and thus improving the battery's charge and discharge efficiency. Third, both the pyridine ring and the ester group can react on the electrode surface, and the resulting products can participate in film formation on both the positive and negative electrode sides, improving the stability of the positive and negative electrode interface. In particular, the SEI film formed by its participation can effectively alleviate the volume expansion effect of silicon anode, avoid the fresh silicon surface being exposed to the electrolyte and the continuous formation of SEI film, which not only significantly improves the stability of SEI film, but also greatly improves the stability of silicon anode material during cycling, thus effectively improving the battery's cycle performance and rate performance and other electrochemical performance.

[0010] Preferably, in the first functional additive, at least one of R1, R2, R3, and R4 is a halogen-containing substituent; the halogen includes at least one of F, Cl, Br, and I. When at least one of R1, R2, R3, and R4 in the first functional additive is a halogen-containing substituent, the halogen group such as F, Cl, Br, or I can enhance the electronic absorption capacity of the functional additive, thereby improving its antioxidant performance. Moreover, halogen atoms may also participate in the chemical reaction on the electrode surface, further promoting the formation of a stable SEI film, optimizing the stability of the electrode material, and improving the cycle performance and rate performance of the battery. In addition, halogens also have high flame retardancy, thus further improving the safety performance of the battery.

[0011] Preferably, in the first functional additive, at least two of R1, R2, R3, and R4 are halogen-containing substituents; the halogen includes at least one of F, Cl, Br, and I.

[0012] Preferably, in the first functional additive, R1 includes an oxygen-containing substituent, which includes an ether-containing substituent or an alkoxy-containing substituent. The ether and alkoxy groups have a certain polarity, enabling them to interact with solutes such as lithium salts in the electrolyte, enhancing the solubility of the first functional additive in the solvent, and allowing for better and more uniform mixing of various components in the electrolyte, thereby improving the overall performance of the electrolyte. Simultaneously, the oxygen atoms in the ether and alkoxy groups can coordinate with lithium ions, participating in the solvation process of lithium ions, reducing the interaction force between lithium ions and anions, which is beneficial for improving lithium ion transport efficiency, increasing ionic conductivity, and optimizing battery rate performance. Furthermore, the ether and alkoxy groups can further promote the stable formation of the SEI or CEI film, further reduce interfacial side reactions, optimize the stability of the positive and negative electrode interfaces, and thus further improve the cycle stability and lifespan of the battery.

[0013] Preferably, in the first functional additive, R1 comprises an alkoxy or ether group, R2 comprises at least one of F, Cl, Br, and I, R3 comprises hydrogen or an alkyl chain, R4 comprises at least one of F, Cl, Br, and I, and R5 comprises an alkyl chain. Preferably, in the first functional additive, R1 comprises a methoxy group, R2 comprises Br, R3 comprises hydrogen, R4 comprises Br, and R5 comprises a methyl group.

[0014] Preferably, the relative molecular mass of the first functional additive is 150–400 g / mol. Controlling the relative molecular mass of the first functional additive within this range helps ensure its good solubility in the electrolyte while also enabling it to interact well with other components in the electrolyte, resulting in better overall electrolyte performance and thus improving the overall battery performance.

[0015] Preferably, the mass percentage of the first functional additive in the electrolyte is 0.5–3 wt%. Controlling the content of the first functional additive within this range serves two purposes: firstly, it avoids insufficient first functional additive content leading to inadequate performance optimization of the electrolyte and battery; secondly, it avoids excessive first functional additive content negatively impacting other components in the electrolyte or affecting the interactions between components, thus degrading the overall performance of the electrolyte and consequently affecting the battery's cycle performance, rate performance, and other electrochemical properties.

[0016] Preferably, the first functional additive comprises methyl 4,6-dibromo-3-methoxypyridine-2-carboxylate, with the structural formula shown below. When the first functional additive has the structural formula shown above, the electrolyte formed together with other components in the electrolyte exhibits better stability and promotes the stable formation of the SEI film on the negative electrode. It also further promotes the stable formation of the CEI film on the positive electrode, thus further improving the battery's cycle performance and rate performance. In particular, for silicon negative electrodes, the first functional additive in this structural formula can more significantly promote the formation of a stable SEI film, effectively alleviating the volume expansion problem of silicon negative electrodes, and thus effectively improving the electrochemical performance of silicon-based batteries.

[0017] Preferably, the electrolyte further includes a second functional additive, which includes siloxane additives; the siloxane additives include at least one of tri(trimethylsilyl)borate (TMSB) and tri(trimethylsilane)phosphate (TMSP). The Si-O bonds in these two siloxane additives can remove water and suppress acid, thus further improving the stability of the SEI and CEI films, reducing interfacial side reactions between the electrode material and the electrolyte, improving the cycle stability of the electrode material, and thereby optimizing battery performance. Furthermore, both of these siloxane additives reduce impedance to a certain extent, which is beneficial for improving the battery's rate performance.

[0018] Preferably, when the second functional additive includes a siloxane additive, the mass percentage of the second functional additive in the electrolyte is 0.2 to 4 wt%.

[0019] Preferably, the siloxane additives include tris(trimethylsilyl) borate and tris(trimethylsilane) phosphate. When both of these siloxane additives are present, both boron (B) and phosphorus (P) atoms are present, which can further promote the stable formation of the SEI film on the negative electrode, improve lithium-ion transport performance, reduce battery internal resistance, and optimize battery cycle performance and rate performance. Simultaneously, the electron-deficient B atoms can complex with transition metal ions dissolved from the positive electrode during charging and discharging, improving the stability of the positive electrode, thus further enhancing the overall performance of the battery.

[0020] Preferably, the mass percentage of tri(trimethylsilyl) borate in the electrolyte is 0.5–2 wt%; and the mass percentage of tri(trimethylsilane) phosphate in the electrolyte is 0.2–1.5 wt%.

[0021] Preferably, the organic solvent includes at least one of linear carbonates and cyclic carbonates.

[0022] Preferably, the linear carbonate includes at least one of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and methyl propyl carbonate.

[0023] Preferably, the cyclic carbonate includes at least one of ethylene carbonate, fluoroethylene carbonate, and propylene carbonate.

[0024] Preferably, the organic solvent includes linear carbonates and cyclic carbonates. Preferably, the volume ratio of linear carbonates to cyclic carbonates is 60-80:20-40.

[0025] Preferably, the organic solvent includes diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, and ethylene carbonate, with a volume ratio of 15–40:5–80:10–30:30–60. Preferably, the volume ratio of diethyl carbonate, methyl ethyl carbonate, fluoroethylene carbonate, and ethylene carbonate is 25:12:18:45.

[0026] Preferably, the lithium salt includes at least one of lithium hexafluorophosphate, lithium trifluoromethanesulfonylimide, lithium tetrafluoroborate, lithium perchlorate, lithium difluorosulfonylimide, and lithium dioxalateborate.

[0027] Preferably, the concentration of lithium salt in the electrolyte is 1–1.5 mol / L.

[0028] A second battery according to this application includes the aforementioned electrolyte. The battery prepared using the aforementioned electrolyte exhibits effectively improved cycle performance and rate performance. The improvement is particularly pronounced for batteries with silicon-based anode systems. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments.

[0030] Example 1

[0031] 1. Composition and preparation of electrolyte

[0032] The electrolyte in this embodiment includes lithium salt, organic solvent, first functional additive, and second functional additive.

[0033] The lithium salt includes lithium hexafluorophosphate (LiPF6), and the concentration of lithium hexafluorophosphate in the electrolyte is 1 mol / L.

[0034] The first functional additive is methyl 4,6-dibromo-3-methoxypyridine-2-carboxylate, which accounts for 1.7 wt% of the electrolyte. The second functional additive includes tris(trimethylsilyl)borate (TMSB) and tris(trimethylsilane)phosphate (TMSP), with tris(trimethylsilyl)borate accounting for 1.3 wt% and tris(trimethylsilane)phosphate accounting for 0.8 wt% of the electrolyte.

[0035] The organic solvents include diethyl carbonate (DEC), fluoroethylene carbonate (FEC), ethylene carbonate (EC), and methyl ethyl carbonate (EMC), and the volume ratio of diethyl carbonate, fluoroethylene carbonate, ethylene carbonate, and methyl ethyl carbonate is 25:12:18:45.

[0036] The electrolyte is prepared according to the following steps: Under an argon atmosphere, the above-mentioned lithium salt, functional additives, and film-forming additives are mixed evenly in an organic solvent, and the mixture is stirred at low temperature during the mixing process.

[0037] 2. Battery manufacturing

[0038] Preparation of lithium-ion batteries

[0039] (1) Preparation of positive electrode

[0040] Ternary material NCM (LiNi) 0.9 Co 0.05 Mn 0.05 O2) positive electrode active material, binder PVDF (polyvinylidene fluoride), and conductive agent SP (conductive carbon black Super-P) are mixed and stirred evenly at a mass ratio of 96:1.8:2.2 to obtain positive electrode slurry. Then, the positive electrode slurry is coated onto aluminum foil through a coating process, and after vacuum drying and cold pressing, a positive electrode sheet is obtained.

[0041] (2) Preparation of negative electrode

[0042] Silicon-carbon anode material (silicon content 40-60 wt%), conductive agent SP (Super-P conductive carbon black), SWCNT (single-walled carbon nanotubes), and binder PAA (polyacrylic acid) are mixed and stirred evenly in a mass ratio of 83.5:8:0.5:8 to obtain a negative electrode slurry. The solid content is controlled at 30%. The negative electrode slurry is then coated onto copper foil through a coating process. After vacuum drying and cold pressing, a negative electrode sheet is obtained.

[0043] (3) Selection of electrolyte

[0044] The electrolyte prepared using this embodiment.

[0045] (4) Selection of the separator

[0046] Polyethylene (PE) + ceramic was chosen as the separator for lithium-ion batteries.

[0047] (5) Preparation of lithium-ion batteries

[0048] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. The bare cell is placed in the outer packaging shell, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a soft-pack lithium-ion battery is obtained.

[0049] Example 2

[0050] The difference between this embodiment and Example 1 is that the first functional additive in the prepared electrolyte is adjusted to methyl 3-methoxypyridine-2-carboxylate, with the structural formula [structure not provided]. The rest is the same as in Example 1.

[0051] Example 3

[0052] The difference between this embodiment and Embodiment 1 is that the first functional additive in the prepared electrolyte is adjusted to... The rest is the same as in Example 1.

[0053] Example 4

[0054] The difference between this embodiment and Example 1 is that the first functional additive in the prepared electrolyte is adjusted to methyl 4,6-dichloro-3-methoxypyridinecarboxylate, with the structural formula [insert structural formula here]. The rest is the same as in Example 1.

[0055] Example 5

[0056] The difference between this embodiment and Example 1 is that the first functional additive in the prepared electrolyte is adjusted to methyl 4,6-dibromopyridinecarboxylate, with the structural formula [insert structural formula here]. The rest is the same as in Example 1.

[0057] Example 6

[0058] The difference between this embodiment and Example 1 is that the first functional additive in the prepared electrolyte is adjusted to methyl 4,6-dibromo-3-hydroxypyridinecarboxylate, with the structural formula [insert structural formula here]. The rest is the same as in Example 1.

[0059] Example 7

[0060] The difference between this embodiment and Embodiment 1 is that the first functional additive in the prepared electrolyte is adjusted to... The rest is the same as in Example 1.

[0061] Example 8

[0062] The difference between this embodiment and Embodiment 1 is that the mass percentage of the first functional additive in the prepared electrolyte is adjusted to 0.3 wt%; the rest is the same as in Embodiment 1.

[0063] Example 9

[0064] The difference between this embodiment and Embodiment 1 is that the mass percentage of the first functional additive in the prepared electrolyte is adjusted to 3.5 wt%; the rest is the same as in Embodiment 1.

[0065] Example 10

[0066] The difference between this embodiment and Example 1 is that the electrolyte prepared does not contain tris(trimethylsilyl) phosphate, that is, the second functional additive contains only tris(trimethylsilyl) borate, and its mass percentage in the electrolyte is 1.3 wt%; the rest is the same as in Example 1.

[0067] Example 11

[0068] The difference between this embodiment and Example 1 is that the electrolyte prepared does not contain tris(trimethylsilyl) borate, that is, the second functional additive contains only tris(trimethylsilyl) phosphate, and its mass percentage in the electrolyte is 0.8 wt%; the rest is the same as in Example 1.

[0069] Example 12

[0070] The difference between this embodiment and Example 1 is that no second functional additive is added to the prepared electrolyte, that is, no tri(trimethylsilyl) borate (TMSB) and tri(trimethylsilane) phosphate (TMSP) are added; otherwise, it is the same as Example 1.

[0071] Example 13

[0072] The difference between this embodiment and Example 1 is that diethyl carbonate (DEC) is not added to the organic solvent in the prepared electrolyte, and the volume ratio of fluoroethylene carbonate, ethylene carbonate, and methyl ethyl carbonate is 12:18:45; the rest is the same as in Example 1.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is that the electrolyte prepared in this example does not contain the first functional additive, i.e., it does not contain methyl 4,6-dibromo-3-methoxypyridine-2-carboxylate; otherwise, it is the same as in Example 1.

[0075] Comparative Example 2

[0076] The difference between this comparative example and Example 1 is that the first functional additive in the prepared electrolyte is adjusted to... The rest is the same as in Example 1.

[0077] Comparative Example 3

[0078] The difference between this comparative example and Example 1 is that the first functional additive in the prepared electrolyte is adjusted to... The rest is the same as in Example 1.

[0079] Test case

[0080] 1. Experimental Construction Method

[0081] The batteries prepared in all the above embodiments and comparative examples were tested at room temperature (25°C) on the LAND battery testing system of Wuhan Jinno Electronics Co., Ltd., with the charge and discharge voltage limited to 2.5V to 4.2V. The specific test methods for performance such as first-efficiency, cycle life, and rate capability are as follows:

[0082] 1) First Coulomb efficiency

[0083] At 25°C, the battery was charged at a constant current and constant voltage of 0.33C to 4.2V, allowed to stand for 10 minutes, and then discharged at a constant current of 0.33C to 2.5V, allowed to stand for 10 minutes. The initial coulombic efficiency of the battery was then calculated.

[0084] Initial coulombic efficiency (%) = Total capacity of battery during initial discharge at 0.33C / Total capacity of battery during initial charge at 0.33C × 100%.

[0085] 2) Capacity retention rate after 1000 cycles at room temperature (1°C) / 1°C

[0086] At 25°C, the battery was charged at a constant current and constant voltage of 1C to 4.2V, with a cutoff current of 0.05C. After resting for 10 minutes, the battery was discharged at a constant current of 1C to 2.5V and then rested for 10 minutes. This constitutes one charge-discharge cycle. The battery was charged and discharged for 1000 cycles using the above method. The capacity retention rate after 1000 charge-discharge cycles at 1C / 1C was calculated.

[0087] The capacity retention rate (%) of a battery after N cycles = (discharge capacity of the Nth cycle / initial discharge capacity) × 100%, where N is the number of battery cycles.

[0088] 3) Capacity retention rate after 1000 cycles at 45℃ (1C / 1C)

[0089] At 45°C, the battery is charged at a constant current and constant voltage of 1C to 4.2V, with a cutoff current of 0.05C. After resting for 10 minutes, the battery is discharged at a constant current of 1C to 2.5V and then rested for 10 minutes. This constitutes one charge-discharge cycle. The battery is charged and discharged for 1000 cycles using the above method. The capacity retention rate after 1000 charge-discharge cycles at 1C / 1C is calculated.

[0090] The capacity retention rate (%) of a battery after N cycles = (discharge capacity of the Nth cycle / initial discharge capacity) × 100%, where N is the number of battery cycles.

[0091] 4) Room temperature 6C rate performance - constant current charge ratio

[0092] At 25℃, the battery was discharged at a constant current rate of 1C to 2.5V, left to stand for 10 minutes, and then charged at a constant current and constant voltage rate of 6C to 4.2V with a cutoff current of 0.05C. After standing for 10 minutes, the constant current charging capacity Q1 and the total constant current and constant voltage charging capacity Q2 were recorded. The constant current charging ratio at the 6C rate was calculated using the following formula: 6C rate charging constant current charging ratio = constant current charging capacity Q1 / total constant current and constant voltage charging capacity Q2 × 100%.

[0093] 2. Experimental Results

[0094] The performance test results of the batteries prepared in all the above embodiments and comparative examples are shown in Table 1.

[0095] Table 1. Performance test results of batteries prepared in the examples and comparative examples.

[0096]

[0097] As shown in Table 1, the battery prepared using the electrolyte provided in this application exhibits good performance in terms of initial efficiency, room temperature and high temperature cycling performance, and 6C constant current charge ratio. This is because the electrolyte provided in this application, especially the introduced first functional additive, can form films on both the positive and negative electrode sides, promoting the stability of the positive and negative electrodes. Particularly for the silicon negative electrode, this specific functional additive promotes the stable growth of the SEI film on the negative electrode side, effectively mitigating the silicon volume expansion effect, thus effectively improving the electrochemical performance of the battery, especially the cycle performance and rate performance of silicon-based batteries. See Examples 1-13 for details. In contrast, Comparative Example 1 lacks the first functional additive, Comparative Example 2's first functional additive lacks an ester group, and Comparative Example 3's first functional additive lacks a pyridine ring (it is a benzene ring), all of which led to a decrease in battery performance in various aspects. This demonstrates that the primary functional additive plays a crucial role in improving the performance of the electrolyte. At the same time, changes in some groups in the primary functional additive can significantly affect its performance, leading to a significant decline in the performance of the electrolyte composed of the primary functional additive. Consequently, it cannot effectively improve the stability of the negative and positive electrode interface or alleviate the volume expansion of the silicon negative electrode, ultimately resulting in the deterioration of the battery performance.

[0098] Further comparing Examples 1 and Examples 2-6, in Example 2, the first functional additive contained no halogen substituents; in Example 3, the first functional additive contained only one halogen substituent (Br); in Example 4, the first functional additive contained two Cl substituents; and in Example 5, R1 in the first functional additive was H (not an oxygen-containing substituent). All these changes resulted in a decrease in the performance of the batteries in Examples 2-6. However, further comparing Examples 2-4, the battery performance in Example 3 was slightly better than that in Example 2, and the battery performance in Example 4 was better than that in Examples 2-3. This indicates that containing two Br halogen substituents simultaneously is more beneficial for optimizing electrolyte performance, thus further improving battery performance.

[0099] Comparing Examples 1 and 8 and 9, the first functional additive in Examples 8 and 9 was too little and too much, respectively, which caused a decrease in the performance of the batteries in Examples 8 and 9. This shows that controlling the amount of the first functional additive within a specific range is more conducive to the overall performance of the electrolyte and further optimizes the performance of the battery.

[0100] Comparing Examples 1 and 10-12, Example 10 contained only tris(trimethylsilyl)borate as the second functional additive, Example 11 contained only tris(trimethylsilyl)phosphate as the second functional additive, and Example 12 contained no second functional additive. This resulted in a decrease in the performance of the batteries in Examples 10-12, especially in Example 12. This indicates that using the first functional additive in combination with the second functional additive is more conducive to exerting the improving effect of the electrolyte on the battery, thereby further optimizing the battery performance.

[0101] Comparing Example 1 and Example 13, in Example 13, diethyl carbonate (DEC) was not added to the organic solvent. This may reduce the interaction effect of the solute in the solvent, thus reducing the overall performance of the electrolyte and ultimately leading to a decrease in battery performance.

[0102] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application, but such modifications or substitutions are all within the scope of protection of this application.

Claims

1. An electrolyte, characterized in that: Including lithium salts, organic solvents, and primary functional additives; The first functional additive includes methyl 4,6-dibromo-3-methoxypyridine-2-carboxylate, with the following structural formula: ； The electrolyte is used in silicon-based anode systems.

2. The electrolyte as described in claim 1, characterized in that: The first functional additive accounts for 0.5~3wt% of the mass of the electrolyte.

3. The electrolyte as described in claim 1, characterized in that: It also includes a second functional additive, which includes siloxane additives; the siloxane additives include at least one of tri(trimethylsilyl) borate and tri(trimethylsilane) phosphate. The second functional additive accounts for 0.2~4 wt% of the mass of the electrolyte.

4. The electrolyte as described in claim 3, characterized in that: The siloxane additives include the tri(trimethylsilyl) borate ester and the tri(trimethylsilane) phosphate ester; The tri(trimethylsilyl) borate ester has a mass percentage of 0.5~2 wt% in the electrolyte; The tris(trimethylsilane) phosphate ester has a mass percentage of 0.2~1.5 wt% in the electrolyte.

5. The electrolyte as described in claim 1, characterized in that: The organic solvent includes at least one of linear carbonates and cyclic carbonates; The linear carbonate includes at least one of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and methyl propyl carbonate. The cyclic carbonates include at least one of ethylene carbonate, fluoroethylene carbonate, and propylene carbonate.

6. The electrolyte as described in claim 1, characterized in that: The lithium salt includes at least one of lithium hexafluorophosphate, lithium trifluoromethanesulfonylimide, lithium tetrafluoroborate, lithium perchlorate, lithium difluorosulfonylimide, and lithium dioxalateborate. The concentration of the lithium salt in the electrolyte is 1~1.5 mol / L.

7. A battery, characterized in that: Includes the electrolyte as described in any one of claims 1 to 6.

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