Electrolyte, battery and electric equipment

Abstract

The invention relates to an electrolyte, a battery and electric equipment. The electrolyte comprises a first additive, and the first additive is a fluorine-containing organic phosphate lithium salt compound.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to an electrolyte, a battery, and an electrical device. Background Technology

[0002] In the field of battery technology, lithium-ion batteries have become an indispensable energy source in modern new energy technologies due to their advantages such as high energy density, high capacity, fast charging, longer cycle life, low self-discharge rate, smaller size, lighter weight, and higher environmental friendliness. Common battery electrolytes suffer from high levels of side reactions at the solvent-electrode interface and large electrolyte consumption during long-term use. Therefore, there is a need to provide an electrolyte that can form a stable interfacial film at the electrode interface, reduce electrolyte consumption during cycling, and extend the battery's lifespan. Summary of the Invention

[0003] In view of this, this application provides an electrolyte, a battery, and an electrical device, wherein the electrolyte can form a stable SEI film at the interface of the negative electrode, reducing the electrolyte's cycle consumption and enabling the battery to have better cycle stability and a longer service life.

[0004] This application provides an electrolyte comprising a first additive, wherein the first additive is a fluorinated organophosphate lithium salt compound.

[0005] Furthermore, the structural formula of the first additive is as follows: .

[0006] Furthermore, the electrolyte also includes a second additive, the structural formula of which is: A includes hydrogen, methyl, ethyl, isopropyl, vinyl, At least one of them.

[0007] Furthermore, in the electrolyte, the mass fraction of the first additive is a, and the mass fraction of the second additive is b, then the electrolyte satisfies the relationship: 0.1≤b / a≤10.

[0008] Furthermore, the electrolyte satisfies the following relationship: 0.2% ≤ a + b ≤ 2%.

[0009] Furthermore, the mass fraction 'a' of the first additive is in the range of 0.1% ≤ a ≤ 1%.

[0010] Furthermore, the mass fraction b of the second additive is in the range of 0.1% ≤ b ≤ 1%.

[0011] Furthermore, the electrolyte also includes a solvent, which includes at least three of the following: dimethyl carbonate, diethyl carbonate, propylene carbonate, ethylene carbonate, methyl ethyl carbonate, ethyl acetate, propyl acetate, ethyl propionate, and propyl propionate.

[0012] This application provides a battery comprising a housing, an electrode assembly, and an electrolyte. The housing has a receiving cavity; the electrode assembly is located within the receiving cavity; and the electrolyte is located within the receiving cavity for wetting at least a portion of the electrode assembly.

[0013] This application also provides an electrical device, which includes: a device body and a battery provided in this application, wherein the battery supplies power to the device body.

[0014] In this application, the first additive is a fluorinated organophosphate lithium salt compound. Firstly, the first additive has a high fluorine content, which allows it to form a uniform, dense, and high-fluorine-content SEI film (Solid Electrolyte Interphase) on the surface of the negative electrode. This SEI film effectively suppresses side reactions between the solvent in the electrolyte and the negative electrode, significantly reducing electrolyte consumption during cycling and thus significantly improving the cycle life of the battery. Furthermore, a fluorine-rich SEI film exhibits better thermal stability, broadening the operating temperature range of the electrolyte and improving its applicability. Secondly, the first additive includes organic oxygen-containing segments. The incorporation of these organic segments increases the stability of the anions in the first additive, enhancing the electrolyte's tolerance to moisture. Simultaneously, it increases the organic component of the SEI film formed on the surface of the negative electrode, preventing excessive lithium fluoride content from increasing the SEI film's resistance to the transport of active ions, thereby reducing electrolyte consumption. When the negative electrode undergoes volume expansion and contraction during charging and discharging, or when stress arises at the interface due to thermal expansion and contraction at high and low temperatures, the flexible organic segments can offset the volume stress through their own deformation. This allows the interface between the negative electrode and the electrolyte to have a certain degree of expansion tolerance, thereby improving interface stability. The first additive in the electrolyte of this application combines the flexibility of the organic segments with the hydrophobic properties of fluoride ions, giving the electrolyte good water resistance and chemical stability. When the electrolyte is applied to a battery, it can give the battery good cycle stability and a long service life. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the implementation will be briefly introduced below. Obviously, the drawings described below are some implementations of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of an energy storage system according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of an energy storage system according to another embodiment of this application; Figure 3 This is a schematic diagram of the structure of an energy storage system according to another embodiment of this application; Figure 4 This is a partial cross-sectional structural diagram of a battery according to an embodiment of this application; Figure 5 This is a circuit block diagram of an electrical device according to an embodiment of this application; Figure 6 This is a schematic diagram of the structure of an electrical device according to an embodiment of this application.

[0017] Explanation of reference numerals in the attached figures: 100 - Energy storage system; 110 - First power conversion device; 120 - First user load; 130 - Second user load; 140 - Energy storage device; 150 - High-voltage cable; 160 - Second power conversion device; 170 - Photovoltaic-energy storage-charging station; 180 - Automobile; 200 - Battery; 210 - Housing; 211 - Receptacle; 220 - Electrode assembly; 221 - Positive electrode; 222 - Separator; 223 - Negative electrode; 230 - Electrolyte; 300 - Electrical equipment; 310 - Equipment body. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0020] In this document, references to "embodiment" or "implementation" mean that a particular feature, structure, or characteristic described in connection with an embodiment or implementation may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0021] In the field of battery technology, lithium-ion batteries have become an indispensable energy source in modern new energy technologies due to their advantages such as high energy density, high capacity, fast charging, longer cycle life, lower self-discharge rate, smaller size, lighter weight, and higher environmental friendliness. Common electrolytes in batteries suffer from the following problems during long-term use: First, there is a high degree of side reaction at the solvent-electrode interface, resulting in large electrolyte consumption; second, during battery cycling, the interfacial impedance is relatively high, easily causing significant polarization loss; third, existing electrolytes have a narrow operating temperature range, unable to meet the requirements of extremely low temperatures of -20℃ and -30℃ as well as high temperatures of 45℃ or even higher, exhibiting poor temperature adaptability. Insufficient interfacial stability of the electrolyte also leads to higher safety risks in the use of energy storage cells, making it difficult to meet the comprehensive requirements of long life, wide temperature range, low polarization, and high safety for energy storage cells.

[0022] Therefore, there is a need to provide an electrolyte that can form a stable interfacial film at the electrode interface, reduce the amount of electrolyte consumed in circulation, and extend the service life of the battery.

[0023] Because the energy we need is highly time- and space-dependent, in order to utilize energy rationally and improve energy efficiency, it is necessary to store one form of energy in the same way or by converting it into another, and then release it in a specific energy form for future applications. Currently, the main way to generate green electricity is to develop green energy sources such as photovoltaics and wind power to replace fossil fuels. Currently, the generation of green electricity generally relies on solar, wind, and hydropower. However, wind and solar power are generally characterized by strong intermittency and large fluctuations, which can cause grid instability, insufficient power during peak demand periods, and excessive power during off-peak periods. Unstable voltage can also damage the power grid. Therefore, insufficient electricity demand or insufficient grid capacity may lead to the problem of "wind and solar curtailment." Solving these problems requires energy storage. This involves converting electrical energy into other forms of energy through physical or chemical means and storing it. When needed, this energy can be converted back into electrical energy and released. Simply put, energy storage is like a large "power bank," storing electrical energy when solar and wind power are abundant and releasing the stored electricity when needed.

[0024] Taking electrochemical energy storage as an example, this solution provides an energy storage device 140, which is applied to the energy storage system 100. The energy storage device 140 is equipped with a set of chemical batteries, which mainly use the chemical elements in the battery 200 as the energy storage medium. The charging and discharging process is accompanied by the chemical reaction or change of the energy storage medium. Simply put, the electrical energy generated by wind and solar energy is stored in the chemical battery. When the use of external electrical energy reaches its peak, the stored electrical energy is released for use, or transferred to places with a shortage of electricity for use.

[0025] Current energy storage applications are quite widespread, including generation-side energy storage, grid-side energy storage, and consumption-side energy storage. The corresponding energy storage devices (140 types) include: (1) Large-scale energy storage power stations (including multiple prefabricated energy storage modules) applied to wind power and photovoltaic power stations can help renewable energy power generation meet grid connection requirements and improve the utilization rate of renewable energy. As a high-quality active / reactive power regulation power source on the power supply side, the energy storage power station can realize the load matching of power in time and space, enhance the renewable energy absorption capacity, reduce instantaneous power changes, reduce the impact on the power grid, improve the problem of new energy power generation absorption, and is of great significance in power grid system backup, alleviating peak load power supply pressure and peak regulation and frequency regulation.

[0026] (2) The energy storage prefabricated cabin applied on the grid side mainly functions as peak regulation, frequency regulation and grid congestion relief. In terms of peak regulation, it can realize peak shaving and valley filling of electricity load, that is, charging the energy storage battery when the electricity load is low and releasing the stored electricity during the peak electricity load period, thereby achieving a balance between power production and consumption.

[0027] (3) Small energy storage cabinets applied to the electricity consumption side mainly function as self-consumption of electricity, peak-valley price arbitrage, capacity cost management, and improvement of power supply reliability. Depending on the application scenario, electricity consumption side energy storage can be divided into industrial and commercial energy storage cabinets, household energy storage devices 140, energy storage charging piles, etc., which are generally used in conjunction with distributed photovoltaics. Industrial and commercial users can use energy storage for peak-valley price arbitrage and capacity cost management. In the electricity market implementing peak-valley pricing, by charging the energy storage system 100 when the electricity price is low and discharging the energy storage system 100 when the electricity price is high, peak-valley price arbitrage can be achieved, reducing electricity costs. In addition, industrial enterprises subject to two-part tariffs can use the energy storage system 100 to store energy during the low electricity consumption period and discharge during the peak load period, thereby reducing peak power and the maximum demand declared, and achieving the goal of reducing capacity electricity costs. Household photovoltaics with energy storage can improve the level of self-consumption of electricity. Due to high electricity prices and poor power supply stability, the demand for household photovoltaic installations is driven. Given that photovoltaic power generation occurs during the day, while user load is generally higher at night, configuring energy storage can better utilize photovoltaic power, improve self-consumption levels, and reduce electricity costs. Furthermore, energy storage is needed in areas such as communication base stations and data centers for backup power.

[0028] In some embodiments, see Figure 1 , Figure 1 This is a schematic diagram of the structure of an energy storage system 100 according to an embodiment of this application. Figure 1 The embodiments are illustrated using a home energy storage scenario in user-side energy storage as an example. The energy storage device 140 in this application is not limited to an energy storage box in a home energy storage scenario.

[0029] This application provides an energy storage system 100, which includes a first power conversion device 110 (photovoltaic panel), a first user load 120 (household lighting fixtures), a second user load 130 (e.g., household appliances such as air conditioners), and the energy storage device 140 of this application. The energy storage device 140 is a small energy storage box that can be wall-mounted on an outdoor wall. However, the energy storage device 140 is not limited to wall mounting and can also be placed in a user's residence in other ways. Specifically, the photovoltaic panel can convert solar energy into electrical energy during periods of low electricity prices, and the energy storage device 140 is used to store this electrical energy and supply it to lighting fixtures and household appliances during periods of high electricity prices, or to provide power during power outages / power failures.

[0030] Optionally, the first power conversion device 110 may include, but is not limited to, a photovoltaic panel, and the first power conversion device 110 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy and mechanical energy into electrical energy.

[0031] In some embodiments, see Figure 2 , Figure 2This is a schematic diagram of the structure of an energy storage system 100 according to another embodiment of this application, and this application Figure 2 The embodiments are illustrated using a shared energy storage scenario on the generation / distribution side as an example. The energy storage device 140 in this application is not limited to a prefabricated energy storage module in a generation and distribution energy storage scenario.

[0032] This application provides an energy storage system 100, which includes: a high-voltage cable 150, a first power conversion device 110, a second power conversion device 160, and an energy storage device 140 provided in this application. In some embodiments of the power generation scenario, the second power conversion device 160 can be a wind power conversion device. Since the electricity generated by wind power conversion is volatile, random, and intermittent, the unstable electricity output by the wind power conversion device can be stored in the energy storage device 140 through grid connection. The energy storage device 140 is connected to the high-voltage cable and outputs smooth electricity to supply the power consumption side of the distribution network, realizing peak shaving and frequency regulation, and ensuring stable grid operation; or, wind power... The conversion device is always connected to the high-voltage cable. Under normal power generation conditions, the power output of the wind power conversion device is supplied to the power consumption side of the distribution network through the high-voltage cable. When the current power load is low and the wind power conversion device generates excess power, the excess power is first stored in the energy storage device 140 to reduce wind and solar curtailment rates and improve the problem of new energy power generation consumption. When the power load is high, the power grid issues an instruction to transmit the power stored in the energy storage device 140 together with the high-voltage cable 150 in grid-connected mode to supply power to the power consumption side. This provides the power grid with various services such as peak shaving, frequency regulation, and backup, giving full play to the peak shaving role of the power grid, promoting peak shaving and valley filling, and alleviating the power supply pressure of the power grid.

[0033] In some embodiments on the distribution network side, the first power conversion device 110 can be a photovoltaic panel, and the energy storage device 140 is connected to the high-voltage cable 150 and installed downstream of the high-voltage cable 150 between the user load and the user load. The electrical energy output by the photovoltaic power conversion device is stored in the energy storage device 140, which can respond in a timely manner to act as a backup power source when the power grid / distribution network fails; or, it can provide power supply support to alleviate line congestion when the high-voltage cable 150 transmission line is blocked, and to delay the economic pressure caused by the expansion of the power grid / distribution capacity when the power grid is planned to be expanded.

[0034] Optionally, the first power conversion device 110 may include, but is not limited to, a wind power conversion device, and the second power conversion device 160 may include, but is not limited to, a photovoltaic panel. The first power conversion device 110 and the second power conversion device 160 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy, and mechanical energy into electrical energy.

[0035] In some embodiments, see Figure 3 , Figure 3This is a schematic diagram of the structure of an energy storage system 100 according to another embodiment of this application, and this application Figure 3 The embodiments are illustrated using an industrial and commercial energy storage scenario as an example. The energy storage device 140 of this application is not limited to an energy storage cabinet in an industrial and commercial energy storage scenario.

[0036] This application provides an energy storage system 100, which includes: an energy storage device 140, a high-voltage cable 150, a factory equipped with a first power conversion device 110, a photovoltaic-energy storage-charging station 170 equipped with a second power conversion device 160, and a vehicle 180. In some embodiments of industrial and commercial scenarios, the first power conversion device 110 can be a photovoltaic panel, which converts solar energy into electrical energy and stores it in the energy storage device 140 in the factory. In the event of a power grid failure, the energy storage device 140 provides power to ensure the safe and stable operation of the factory without interruption. Alternatively, when the factory's power load is high, the power grid issues an instruction to transmit the electricity stored in the energy storage device 140 in conjunction with the high-voltage cable 150 in a grid-connected mode to supply the factory with electricity, providing various services such as peak shaving / frequency regulation and backup for the power grid operation. In addition, the second power conversion device 160 can also be a photovoltaic panel, which converts solar energy into electrical energy and stores it in the energy storage device 140 of the photovoltaic-energy storage-charging station 170, directly charging the vehicle 180 through the photovoltaic-energy storage-charging station 170, which is fast and convenient.

[0037] Optionally, the first power conversion device 110 and the second power conversion device 160 may include, but are not limited to, photovoltaic panels. The first power conversion device 110 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy, and mechanical energy into electrical energy.

[0038] Optionally, the energy storage device 140 may include, but is not limited to, energy storage applications such as energy storage power stations, hydropower / thermal / wind power generation systems, solar power generation systems, mobile power systems, smart home systems, or temporary power supply systems, and may also be applied in multiple fields such as data centers, military equipment, aerospace, charging piles, and electric vehicles.

[0039] Optionally, the energy storage device 140 may include, but is not limited to, single-cell batteries, or battery modules, battery packs, battery clusters, power banks, energy storage cabinets / prefabricated energy storage compartments, and other battery integrated systems composed of single-cell batteries. The actual application form of the energy storage device 140 provided in this application embodiment may be, but is not limited to, the listed products, and may also be other application forms. This application embodiment does not strictly limit the application form of the energy storage device 140. This application embodiment only uses a multi-cell battery of the energy storage device 140 as an example for illustration.

[0040] Optionally, the individual battery cells constituting the energy storage device 140 can be, but are not limited to, at least one of cylindrical, prismatic, prismatic, or other shaped batteries.

[0041] Optionally, the energy storage device 140 may include, but is not limited to, energy storage applications such as energy storage power stations, hydropower / thermal / wind power generation systems, solar power generation systems, mobile power systems, smart home systems, or temporary power supply systems, and may also be applied in multiple fields such as data centers, military equipment, aerospace, charging piles, and electric vehicles.

[0042] Optionally, the energy storage device 140 may include battery modules, battery packs, battery clusters, mobile power supplies, energy storage cabinets / prefabricated energy storage compartments, and other battery integrated systems composed of individual batteries. The actual application form of the energy storage device 140 provided in this application embodiment may be, but is not limited to, the listed products, and may also be other application forms. This application embodiment does not strictly limit the application form of the energy storage device 140.

[0043] Alternatively, the single cell is not limited to at least one of cylindrical, square, prismatic, or other shaped cells.

[0044] Optionally, the single cell can be a rechargeable battery, which refers to a single cell that can be recharged after discharge to activate the active materials and continue to be used. The single cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this application does not specifically limit it.

[0045] Please see Figure 4 This application provides an electrolyte 230, which includes a first additive, the first additive being a fluorinated organophosphate lithium salt compound.

[0046] Understandably, the fluorinated organophosphate lithium salt compound includes organic oxygen-containing segments.

[0047] Understandably, the electrolyte 230 is applied to the battery 200, which includes a housing 210 and an electrode assembly 220. The housing 210 has a receiving cavity 211, and the electrolyte 230 and the electrode assembly 220 are located within the receiving cavity 211. The electrolyte 230 is used to wet at least a portion of the electrode assembly 220.

[0048] Understandably, the electrode assembly 220 includes a positive electrode 221, a diaphragm 222, and a negative electrode 223 stacked sequentially.

[0049] Understandably, the battery 200 is a lithium-ion battery, and the active ions in the battery 200 are lithium ions.

[0050] In this embodiment, the first additive is a fluorinated organophosphate lithium salt compound. Firstly, the first additive has a high fluorine content, which can form a uniform, dense, and high-fluorine-content SEI film (Solid Electrolyte Interphase) on the surface of the negative electrode 223. This SEI film can effectively suppress side reactions between the solvent in the electrolyte 230 and the negative electrode 223, significantly reducing the consumption of the electrolyte 230 during cycling, thereby significantly improving the cycle life of the battery 200. Furthermore, the fluorine-rich SEI film has better thermal stability, which can broaden the operating temperature range of the electrolyte 230, thereby improving the applicability of the electrolyte 230. Secondly, the first additive includes organic oxygen-containing segments. The incorporation of these organic segments can increase the stability of the anions in the first additive, improving the electrolyte 230's tolerance to moisture. Simultaneously, the organic component of the SEI film formed by the electrolyte 230 on the surface of the negative electrode 223 can be increased to avoid increasing the resistance of the SEI film to the transport of active ions due to excessive lithium fluoride content, thereby reducing the consumption of electrolyte 230. When the negative electrode 223 undergoes volume expansion and contraction during charging and discharging, or when stress is generated at the interface due to thermal expansion and contraction at high and low temperatures, the flexible organic segments can offset the volume stress through their own deformation, so that the interface between the negative electrode 223 and the electrolyte 230 has a certain degree of expansion tolerance, improving interface stability. The first additive of the electrolyte 230 in this application takes into account both the flexibility of the organic segments and the hydrophobic properties of fluoride ions, so that the electrolyte 230 has good water resistance and chemical stability. When the electrolyte 230 is applied to the battery 200, the battery 200 can have good cycle stability and a long service life.

[0051] In some embodiments, the structural formula of the first additive is: .

[0052] In this embodiment, the first additive has hexafluorophosphate ions on both sides, and the 1,2-difluoroethane in the middle chain segment is connected to the phosphorus atoms on both sides through two oxygen atoms, forming a diphosphate ester structure. On the one hand, the first additive has a high fluorine content, and the SEI film formed on the surface of the negative electrode 223 contains a large amount of lithium fluoride, so that the SEI film has good chemical and thermal stability and can effectively resist the continuous corrosion of the solvent. In addition, due to the high fluorine content of the first additive, only a very small amount of the first additive is needed to quickly and uniformly form a film on the interface of the negative electrode 223, which reduces the amount of the first additive used and can quickly achieve passivation protection of the interface of the negative electrode 223, blocking the side reaction between the electrolyte 230 and the negative electrode 223 in advance, reducing the ineffective consumption of the electrolyte 230 from the source, and ensuring a dual improvement in film formation efficiency and interface protection effect. On the other hand, the first additive includes organic oxygen-containing segments, which provide bridging connections for the hexafluorophosphate ions on both sides, providing a stable molecular framework for electron conjugation and transfer. The negative charges at both ends can achieve uniform charge dispersion and conjugation delocalization through the oxygen-containing segments, making the electron cloud distribution of the entire molecule more stable and raising the energy barrier for the reduction of electrons in the molecule. Ultimately, this results in a significant positive shift in the reduction potential of the first additive, so that during the first charge and discharge process of the battery 200, the first additive can preferentially undergo reduction and decomposition reactions with other components in the electrolyte 230, preferentially forming a dense and continuous SEI film on the surface of the negative electrode 223, improving the interfacial stability between the negative electrode 223 and the electrolyte 230, and meeting the comprehensive requirements of the battery 200 for long life, wide temperature range, low polarization, and high safety.

[0053] In some embodiments, the electrolyte 230 further includes a second additive, the second additive having the following structural formula: A includes hydrogen, methyl, ethyl, isopropyl, vinyl, At least one of them.

[0054] Understandably, when A includes methyl, ethyl, isopropyl, vinyl, When at least one of the following is present, the second additive is a 4-substituted vinyl sulfate.

[0055] Understandably, the second additive is a cyclic sulfate compound.

[0056] In this embodiment, the structural formula of the second additive is as follows: When A is hydrogen, the second additive, as a cyclic sulfate ester, possesses specific ring-opening film-forming potential and exhibits good solubility in the electrolyte 230. When A includes methyl, ethyl, isopropyl, vinyl, ... When at least one of the following is present, the second additive is a 4-substituted vinyl sulfate. Compared to unsubstituted vinyl sulfate, the 4-substituent can hinder water molecules from approaching the sulfur atom on the ring through steric hindrance, significantly reducing the hydrolysis rate of the cyclic sulfate, improving the water resistance of the second additive in the electrolyte 230, reducing the formation of hydrolysis products such as sulfate, and lowering the risk of increased interfacial impedance and loss of active lithium ions caused by hydrolysis products. Furthermore, by substituting at the 4-position of the vinyl sulfate, the electron cloud of the entire group can be pulled in a specific direction, making the second additive more prone to ring-opening and breaking. The second additive forms a polymer and forms a film on the surface of the negative electrode 223. When the electrolyte 230 includes the first additive and the second additive, the first additive preferentially forms an SEI film on the surface of the negative electrode 223, thereby making the SEI film, from the inside out, consist of an inorganic layer rich in lithium fluoride, an intermediate layer of organic and organic mixtures, and an organic layer rich in sulfur. The interface film between the negative electrode 223 and the electrolyte 230 has good thermal stability and chemical stability, good expansion tolerance, and good ion transport performance. It can effectively reduce the side reactions of the electrolyte 230, reduce the ineffective loss of the electrolyte 230, improve the interface stability between the negative electrode 223 and the electrolyte 230, and enable the electrolyte 230 to meet the requirements of a wide temperature range, thereby improving the safety performance, cycle performance, and rate performance of the battery 200.

[0057] In some embodiments, in the electrolyte 230, the mass fraction of the first additive is a and the mass fraction of the second additive is b, then the electrolyte 230 satisfies the relationship: 0.1≤b / a≤10.

[0058] Understandably, the mass fraction of the first additive is the ratio of the mass of the first additive to the mass of the electrolyte 230. The mass fraction of the second additive is the ratio of the mass of the second additive to the mass of the electrolyte 230.

[0059] Specifically, the value of b / a can be, but is not limited to, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 9.9 and 10.

[0060] Understandably, when the electrolyte 230 satisfies the relationship 0.1≤b / a≤10, the mass fraction a of the first additive in the electrolyte 230 is greater than the mass fraction of the second additive; when the value of b / a is 1, the mass fraction a of the first additive in the electrolyte 230 is equal to the mass fraction of the second additive; when the electrolyte 230 satisfies the relationship 0.1≤b / a≤10, the mass fraction a of the first additive in the electrolyte 230 is less than the mass fraction of the second additive.

[0061] In this embodiment, when the electrolyte 230 satisfies the relationship 0.1 ≤ b / a ≤ 10, the mass fractions of both the first additive and the second additive are within a reasonable range. The first and second additives can work synergistically to avoid interfacial imbalance between the electrolyte 230 and the negative electrode 223. Specifically, the first additive preferentially forms a fluorine-rich inorganic layer on the surface of the negative electrode 223, and the expansion tolerance of the fluorine-containing inorganic layer is optimized by the organic segments in the first additive. Furthermore, the second additive further forms a sulfur-rich organic layer on the surface of the negative electrode 223 to improve the ion-conducting characteristics of the SEI film. The first and second additives work together to create a uniformly configured FS cross-linked ion-conducting network within the SEI film, improving the interfacial stability between the electrolyte 230 and the negative electrode 223, and ultimately improving the cycle stability and rate performance of the battery 200 when the electrolyte 230 is applied. When the value of b / a is too large, the content of the first additive is too low or the content of the second additive is too high. If the content of the first additive is too low, it will be difficult for the first additive to form a lithium fluoride-rich SEI film on the surface of the negative electrode 223, making it difficult to improve the chemical and thermal stability of the SEI film. During the charging and discharging process of the battery 200, this may increase the consumption of the electrolyte 230 and reduce the cycle stability of the battery 200. If the content of the second additive is too high, it may make the viscosity of the electrolyte 230 too high, increasing the resistance to the transport of active ions in the electrolyte 230 and reducing the conductivity of the electrolyte 230. Active ions will be difficult to replenish from the electrolyte 230 to the surface of the negative electrode 223 in a timely manner, thereby generating concentration polarization and reducing the safety performance of the battery 200. When the b / a value is too low, the content of the first additive is too high or the content of the second additive is too low. If the content of the first additive is too high, the inorganic component in the SEI film formed on the surface of the negative electrode 223 will be too high, which may lead to an excessively thick SEI film, increasing the interfacial impedance between the negative electrode 223 and the electrolyte 230, and reducing the rate performance of the battery 200 when the electrolyte 230 is used. If the content of the second additive is too low, the second additive will be unable to increase the organic component and sulfur content in the SEI film formed on the surface of the negative electrode 223, thereby making it difficult to improve the ion conduction performance of the SEI film, increasing the interfacial impedance between the negative electrode 223 and the electrolyte 230, and reducing the rate performance of the battery 200 when the electrolyte 230 is used.

[0062] In some embodiments, the electrolyte 230 satisfies the relationship: 0.2%≤a+b≤2%.

[0063] Specifically, the value of a+b can be, but is not limited to, 0.2%, 0.22%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, and 2%.

[0064] In this embodiment, when the electrolyte 230 satisfies the relationship 0.2% ≤ a + b ≤ 2%, the mass fractions of the first additive and the second additive in the electrolyte 230 are both within a reasonable range. The first additive and the second additive can work synergistically to construct a complete SEI film on the surface of the negative electrode 223 that balances a stable inorganic interface framework and a tough organic interface. This improves the interfacial stability between the negative electrode 223 and the electrolyte 230, reduces unnecessary consumption of the electrolyte 230, and enhances the cycle performance of the battery 200. Furthermore, it avoids increasing the viscosity of the electrolyte 230 due to excessively high levels of the first additive and / or the second additive, ensuring that active ions have good transport performance in the electrolyte 230 and improving the rate performance of the battery 200. When the value of a+b is too small, the content of the first additive and the second additive in the electrolyte 230 is too low, making it difficult to construct a complete SEI film on the surface of the negative electrode 223 that balances a stable inorganic interface framework and a tough organic interface. An incomplete SEI film will cause the volume of the electrolyte 230 to directly contact the negative electrode 223, potentially leading to the consumption of active lithium ions in the electrolyte 230, reducing the interfacial stability between the electrolyte 230 and the negative electrode 223, and ultimately shortening the cycle life of the battery 200. When the value of a+b is too large, the content of the first additive and / or the second additive in the electrolyte 230 is too high. On the one hand, this may increase the viscosity of the electrolyte 230, reduce its ionic conductivity, and trigger concentration polarization. On the other hand, excessive amounts of the first and second additives may lead to the formation of an excessively thick and loose SEI film on the surface of the negative electrode 223, which significantly increases the interfacial transport resistance of lithium ions and reduces the charge and discharge efficiency and rate performance of the battery 200.

[0065] In some embodiments, the mass fraction a of the first additive is in the range of 0.1% ≤ a ≤ 1%.

[0066] Specifically, the mass fraction 'a' of the first additive can be, but is not limited to, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 0.99%, and 1%.

[0067] In this embodiment, when the mass fraction 'a' of the first additive is within the range of 0.1% ≤ a ≤ 1%, the mass fraction of the first additive is within a reasonable range. On the one hand, the first additive can form a lithium fluoride-rich SEI film on the surface of the negative electrode 223, thereby improving the chemical and thermal stability of the SEI film, significantly reducing the consumption of electrolyte 230 during cycling, and thus significantly improving the cycle life of the battery 200. On the other hand, the first additive includes organic oxygen-containing segments, which can prevent the impedance of the interfacial film formed by the first additive on the surface of the negative electrode 223 from being too high, thus improving the rate performance of the battery 200. When the mass fraction of the first additive is too high, the inorganic component in the SEI film formed on the surface of the negative electrode 223 will be too high, and it may lead to an excessively thick SEI film, increasing the interfacial impedance between the negative electrode 223 and the electrolyte 230, and reducing the rate performance of the battery 200 when the electrolyte 230 is used in the battery 200. In addition, it may cause waste of the first additive, needlessly increasing the preparation cost of the electrolyte 230. When the mass fraction of the first additive is too small, it is difficult for the first additive to form a lithium fluoride-rich SEI film on the surface of the negative electrode 223, which makes it difficult to improve the chemical and thermal stability of the SEI film. The consumption of the electrolyte 230 is large, which reduces the cycle stability of the battery 200 when the electrolyte 230 is applied to the battery 200.

[0068] In some embodiments, the mass fraction b of the second additive is in the range of 0.1% ≤ b ≤ 1%.

[0069] Specifically, the mass fraction b of the second additive can be, but is not limited to, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 0.99%, and 1%.

[0070] In this embodiment, when the mass fraction b of the second additive is within the range of 0.1% ≤ b ≤ 1%, the mass fraction of the second additive is within a reasonable range. The first additive and the second additive have a good synergistic effect, so that the SEI film formed on the surface of the negative electrode 223 has both good stability and high ion conduction characteristics, thereby giving the battery 200 good cycle performance and rate performance. At the same time, it can avoid increasing the resistance to the transport of active ions in the electrolyte 230 due to an excessively high mass fraction of the second additive, thus improving the performance of the electrolyte 230. When the mass fraction of the second additive is too high, on the one hand, it may make the viscosity of the electrolyte 230 too high, increasing the resistance to the transport of active ions in the electrolyte 230 and reducing the conductivity of the electrolyte 230. Active ions are difficult to replenish from the electrolyte 230 to the surface of the negative electrode 223 in time, thereby generating concentration polarization. On the other hand, it may lead to excessively high acidity of the electrolyte 230, which is not conducive to the storage of the electrolyte 230, thereby shortening the service life of the electrolyte 230. When the mass fraction of the second additive is too small, the synergistic effect between the second additive and the first additive is weakened. The second additive is unable to increase the organic components and sulfur content in the SEI film formed on the surface of the negative electrode 223, thereby making it difficult to improve the ion conduction performance of the SEI film, increasing the interfacial impedance between the negative electrode 223 and the electrolyte 230, and reducing the rate performance of the battery 200 when the electrolyte 230 is applied to the battery 200.

[0071] In some embodiments, the electrolyte 230 further includes a solvent, which includes at least three of the following: dimethyl carbonate, diethyl carbonate, propylene carbonate, ethylene carbonate, methyl ethyl carbonate, ethyl acetate, propyl acetate, ethyl propionate, and propyl propionate.

[0072] Optionally, in some embodiments, the solvent has a molar ratio of 1 mol / L in the electrolyte 230.

[0073] In this embodiment, the solvent is used to dissolve the first additive and the second additive. Compared with the solvent and other components in the solvent, the first additive and the second additive can preferentially form a stable SEI film at the interface of the negative electrode 223, so as to improve the cycle stability of the battery 200 when the electrolyte 230 is applied to the battery 200.

[0074] Optionally, the electrolyte 230 further includes a film-forming additive, which includes at least one of vinylene carbonate (VC), fluoroethylene carbonate (FEC), propenyl sulfonate lactone (PS), vinylene carbonate (VEC), 1,3-propane sulfonate lactone (PST), and ethylene sulfate (ES). The film-forming additive works in conjunction with the first additive and the second additive to form a stable SEI film on the surface of the negative electrode 223.

[0075] Optionally, in some embodiments, the mass fraction of the film-forming additive in the electrolyte 230 ranges from 1% to 3%. Specifically, the mass fraction of the film-forming additive can be, but is not limited to, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, and 3%.

[0076] Please see Figure 4 This application provides a battery 200, which includes a housing 210, an electrode assembly 220, and an electrolyte 230 provided in this application. The housing 210 has a receiving cavity 211; the electrode assembly 220 is located in the receiving cavity 211; and the electrolyte 230 is located in the receiving cavity 211 for wetting at least a portion of the electrode assembly 220.

[0077] Optionally, the battery 200 can be, but is not limited to, a square battery, a round battery, etc.

[0078] In this embodiment, the battery 200 includes the electrolyte 230 provided in this application. The electrolyte 230 is disposed in the accommodating cavity 211 and is used to wet at least a portion of the electrode assembly 220. The electrolyte 230 includes the first additive, which has a high fluorine content and can form a uniform, dense, and high fluorine content SEI film on the surface of the negative electrode 223. This interface film has good chemical and thermal stability and can effectively suppress the side reactions between the solvent in the electrolyte 230 and the negative electrode 223, significantly reducing the consumption of the electrolyte 230 during the cycle process, thereby significantly improving the cycle life of the battery 200. Furthermore, the first additive includes organic oxygen-containing segments, which can increase the organic component of the SEI film formed by the electrolyte 230 on the surface of the negative electrode 223. This avoids increasing the resistance of the SEI film to the transport of active ions due to excessive lithium fluoride content, thereby reducing the consumption of electrolyte 230. Simultaneously, it can give the interface between the negative electrode 223 and the electrolyte 230 a certain degree of expansion tolerance, improving interface stability. The battery 200 of this embodiment has good cycle stability and a long service life.

[0079] Optionally, the electrode assembly 220 includes a positive electrode 221, a diaphragm 222, and a negative electrode 223 stacked sequentially.

[0080] Optionally, the positive electrode 221 includes a positive electrode active material, the positive electrode active material includes lithium iron phosphate, and the compaction density of the positive electrode 221 is in the range of 2.3 g / cm³. 3 Up to 2.7 g / cm 3 Specifically, the compaction density of the positive electrode 221 can be, but is not limited to, 2.3 g / cm³. 3 2.32 g / cm 3 2.35g / cm 3 2.38g / cm 3 2.4g / cm 3 2.42 g / cm 3 2.45g / cm 3 2.48 g / cm 3 2.5g / cm 3 2.52g / cm 3 2.55g / cm 3 2.6g / cm 3 2.62 g / cm 3 2.65g / cm 3 and 2.7g / cm 3 wait.

[0081] Optionally, the negative electrode 223 comprises a negative electrode active material, the negative electrode active material comprising graphite, and the compaction density of the negative electrode 223 is in the range of 1.3 g / cm³. 3 Up to 1.6 g / cm 3 Specifically, the compaction density of the positive electrode 221 can be, but is not limited to, 1.3 g / cm³. 3 1.32g / cm 3 1.35g / cm 3 1.38g / cm 3 1.4g / cm 3 1.42g / cm 3 1.45g / cm 3 1.48g / cm 3 1.5g / cm 3 1.52g / cm 3 1.55g / cm 3 1.58g / cm 3 and 1.6g / cm 3 wait.

[0082] The technical solution of this application will be further described below with reference to several embodiments: Examples 1 to 16, Comparative Examples 1 to 6: 1. Preparation of electrolyte 230: The solvent of electrolyte 230 used in this experiment had a water content of less than 10 ppm after dehydration by molecular sieve. The type and mass ratio of the solvent was (DMC, dimethyl carbonate): (EMC, ethyl methyl carbonate): (EC, ethylene carbonate) = 1:1:1. Film-forming additives were added, and the types and contents of the film-forming additives were: 2% by mass of vinylene carbonate (VC) and 1% by mass of fluoroethylene carbonate (FEC). The total molar number of lithium salt was 1 mol / L. Then, the first additive and the second additive provided in this application were added, mixed evenly, sealed and stored at low temperature to obtain electrolyte 230 of Examples 1 to 16 and Comparative Examples 1 to 6.

[0083] The values ​​of the mass fraction a of the first additive, the type of the substituent at the 4-position of the second additive, the mass fraction b of the second additive, the value of a+b, and the value of b / a in the electrolyte 230 of Examples 1 to 16 and Comparative Examples 1 to 6 are shown in Table 1.

[0084] 2. Preparation of positive electrode 221: The positive electrode 221 used in this experiment was made of lithium iron phosphate as the positive electrode active material. Conductive carbon and polyvinylidene fluoride (PVDF) with a mass fraction of 0.2% were added to the lithium iron phosphate solid powder and dry-mixed. After uniform mixing, a certain amount of solvent N-methylpyrrolidone (NMP) was added and stirred and kneaded, with the kneaded solid content controlled at 72%-74%. Then, NMP was continuously added for high-speed dispersion, followed by a series of processes such as viscosity adjustment, vacuum slow stirring to remove bubbles, and filtration, to form a positive electrode slurry with uniform viscosity and fineness. This slurry was then coated onto aluminum foil, with the coating thickness controlled within the range of (0.5 to 0.6) g / (1540.25 mm2). The positive electrode 221 of Examples 1 to 16 and Comparative Examples 1 to 6 was then produced through baking, rolling, slitting, and cutting. Simultaneously, the carbon content of the anode was detected by scraping powder from the electrode material area using a carbon-sulfur analyzer.

[0085] 3. Preparation of negative electrode 223: The negative electrode 223 used in this experiment is made of artificial graphite as the negative electrode active material. The process involves adding 0.1% by mass of conductive carbon and carboxymethyl cellulose (CMC) to graphite powder, mixing it with a certain amount of deionized water, then adding a binder / additive, stirring and dispersing, followed by the addition of a certain amount of styrene-butadiene rubber (SBR) and stirring. After vacuum slow stirring to remove bubbles and filtration, a negative electrode slurry with uniform viscosity and fineness is formed. This slurry is then coated onto copper foil, with the coating thickness controlled at (0.24 to 0.3) g / (1540.25 mm). 2 Within the range of ), the negative electrode sheets 223 of Examples 1 to 16 and Comparative Examples 1 to 6 are then produced through processes such as baking, rolling, slitting, and cutting.

[0086] 4. Preparation of diaphragm 222: Use 16μm polypropylene (PP) diaphragm 222.

[0087] 5. Assembly of battery 200: The prepared positive electrode 221 and negative electrode 223 are separated by a separator 222, folded and wound into a bare cell, and injected with electrolyte 230 after hot pressing, welding, top and side sealing, drying and dehydration. Then, through a series of processes such as standing, formation, aging, capacity testing and K-value testing, implementation cells 1 to 16 and comparison cells 1 to 6 are obtained.

[0088] In this embodiment, the electrolyte 230 of Example 1 is used in the experimental battery 1, the electrolyte 230 of Example 2 is used in the experimental battery 2, the electrolyte 230 of Comparative Example 1 is used in the control battery 1, the electrolyte 230 of Comparative Example 2 is used in the control battery 2, and so on.

[0089] Table 1 below shows the composition parameters of the electrolyte 230 in Examples 1 to 16 and Comparative Examples 1 to 6.

[0090] Table 1: Composition parameters of electrolyte 230 in Examples 1 to 16 and Comparative Examples 1 to 6.

[0091]

[0092] Battery 200 performance test: 1. Room temperature cycling performance tests of batteries 1 to 16 and control batteries 1 to 6: Implemented batteries 1 to 16 and control batteries 1 to 6 were selected, and their room temperature cycle performance was tested sequentially. The specific steps included: first, charging at 25℃ with 0.5P for three cycles to activate the cell, and recording the initial capacity of the third cycle as C0; then, charging to 3.65V and discharging to 2.5V with 0.5P at 25℃ for 500 cycles, recording the discharge capacity of the last cycle as C1, the charging energy of the last cycle as W1, and the discharge energy as W2. Then, the capacity retention rate after 500 cycles at 25℃ with 0.5P = C1 / C0, and the energy efficiency after 500 cycles at 25℃ with 0.5P = W2 / W1.

[0093] Table 2 shows the capacity retention rate and energy efficiency of the implementation batteries 1 to 16 and the comparative batteries 1 to 6 at 25°C and 0.5P for 500 cycles.

[0094] 2. High-temperature cycle performance tests were conducted on batteries 1 to 16 and control batteries 1 to 6. Implemented batteries 1 to 16 and control batteries 1 to 6 were selected, and their high-temperature cycling performance was tested sequentially. The specific steps included: First, a charge-discharge test was conducted at 45℃, charging to 3.65V with 1P and discharging to 2.5V with 1P, cycling three times to activate the cell. The initial capacity of the third cycle was recorded as C2. At 45℃, a charge-discharge test was conducted for 500 cycles, charging to 3.65V with 1P and discharging to 2.5V with 1P. The discharge capacity of the last cycle was recorded as C3, the charging energy as W3, and the discharging energy as W4. Therefore, the capacity retention rate after 500 cycles at 45℃ with 0P is C3 / C2, and the energy efficiency after 500 cycles at 45℃ with 0.5P is W4 / W3.

[0095] Table 2 shows the capacity retention rate and energy efficiency at 45°C and 1P for 500 cycles for both experimental batteries 1 to 16 and comparative batteries 1 to 6.

[0096] 3. Electrolyte 230 consumption test in batteries 1 to 16 and control batteries 1 to 6: Implemented cells 1 to 16 and control cells 1 to 6 were selected after 500 cycles at 25℃ and 0.5P / 0.5P. The cells were discharged to 2.0V using 0.02C. Then, acetonitrile calibration solvent (acetonitrile solution containing 10% cyclohexyl) was injected into the cells using a syringe to maintain 50% of the electrolyte volume (m1). The needle hole was sealed with A and B glue, and the seal was allowed to solidify. The cells were then soaked for 3 days. Electrolyte 230 was sampled and subjected to GC (gas chromatography) testing. The accurate mass m2 of electrolyte 230 was obtained by using the concentration and mass of the acetonitrile calibration solution, as well as the mass percentage of the calibration solution in the soaking solution during GC testing. The electrolyte 230 consumption was calculated as {(m1-m2) / m1}×100%.

[0097] The values ​​of electrolyte 230 consumption in implementation batteries 1 to 16 and comparative batteries 1 to 6 are shown in Table 2.

[0098] Table 2 below shows the performance parameters of implementation batteries 1 to 16 and comparison batteries 1 to 6.

[0099] Table 2: Performance parameters of implementation batteries 1 to 16 and comparison batteries 1 to 6.

[0100]

[0101] Please refer to Tables 1 and 2. From the data of Examples 1 to 6, Comparative Examples 1 and 2, it can be seen that, under the same conditions, the mass fraction 'a' of the first additive in the electrolyte 230 of Examples 1 to 6 all meet the range of 0.1% ≤ a ≤ 1%, and the 4-position substituent of the second additive is hydrogen. However, the electrolyte 230 in Comparative Example 1 does not contain either the first additive or the second additive, and the electrolyte 230 in Comparative Example 2 does not contain the first additive. This makes the capacity retention rate, energy efficiency, and capacity retention rate of Implemented Batteries 1 to 6 at 25°C and 0.5P for 500 cycles, as well as the energy efficiency at 45°C and 1P for 500 cycles, all better, and the consumption of electrolyte 230 is lower. This is because the first additive has a high fluorine content, which can form a uniform, dense SEI film with a high fluorine content on the surface of the negative electrode 223, thereby improving the interfacial stability between the electrolyte 230 and the negative electrode 223. Furthermore, the second additive can improve the ion transport performance of the SEI film. The first and second additives work together to ensure that the implemented batteries 1 to 6 have good cycle stability and rate performance at both room temperature and high temperature, and to reduce the loss of the electrolyte 230.

[0102] Furthermore, under otherwise unchanged conditions, as the mass fraction of the first additive gradually increases, the cycle performance of the corresponding battery 200 shows a trend of first increasing and then decreasing. This is because the SEI film formed by the first additive has good chemical and thermal stability, which can reduce the side reactions between the electrolyte 230 and the negative electrode 223. However, increasing the content of the first additive also leads to an increase in the lithium fluoride content in the SEI film, which in turn increases the interfacial impedance of the negative electrode 223. Therefore, it is necessary to adjust the mass fraction of the first additive to ensure the cycle performance of the battery 200. Preferably, when the mass fraction of the first additive is 0.5%, the A substituent of the second additive is hydrogen, and its content satisfies the range of 0.1%≤b≤1%, the corresponding battery 200 has a capacity retention rate of ≥95.32% after 500 cycles at 25℃ and 0.5P, with an optimal value of 100.04%, and a capacity retention rate of ≥96.01% after 500 cycles at 45℃ and 1P, with an optimal value of 96.22%. This indicates that maintaining the content of the second additive within a certain range can ensure the stability of the cycle interface, improve cycle performance, and simultaneously improve energy efficiency and reduce electrolyte 230 consumption.

[0103] As can be seen from the data of Examples 7 to 11 and Comparative Example 4, under the same conditions, the mass fraction b of the second additive in the electrolyte 230 of Examples 7 to 11 all meet the range of 0.1% ≤ b ≤ 1%, while the electrolyte 230 in Comparative Example 4 does not include the second additive. This makes the capacity retention rate, energy efficiency and capacity retention rate of the battery 7 to the battery 11 at 25°C and 0.5P for 500 cycles, and energy efficiency at 45°C and 1P for 500 cycles all better, and the consumption of electrolyte 230 is lower. This indicates that the first additive and the second additive have a synergistic effect. The second additive can introduce sulfur- and oxygen-containing organic flexible components into the SEI film, effectively increasing the organic components in the SEI film and thus improving its flexibility. This results in the SEI film formed on the surface of the negative electrode 223 by the first and second additives having better expansion resistance, thereby improving the performance of the electrolyte 230. Furthermore, the second additive can introduce Li2S and Li2SO4, which have superior ion-conducting properties, into the SEI film, effectively improving the transport performance of active ions and reducing the risk of reduced interfacial diffusion efficiency of active ions between the negative electrode 223 and the electrolyte 230 due to excessive lithium fluoride. Ultimately, this results in good cycle performance of batteries 7 to 11 at both room temperature and high temperature, while also reducing electrolyte consumption. Preferably, when the mass fraction of the first additive is within the range of 0.1% ≤ a ≤ 1%, and the A substituent of the second additive is hydrogen, and its content is within the range of 0.1% ≤ b ≤ 1%, the corresponding battery 200 has a capacity retention rate of ≥ 97.82% after 500 cycles at 25°C and 0.5P, with an optimal value of 100.04%, and a capacity retention rate of ≥ 88.23% after 500 cycles at 45°C and 1P, with an optimal value of 90.98%. This indicates that maintaining the content of the second additive within a certain range can ensure the stability of the cycle interface, improve cycle performance, and simultaneously improve energy efficiency and reduce electrolyte 230 consumption.

[0104] Data from Examples 3, 12 to 16 show that, under the same conditions, different types of the second additive affect the cycle performance of the corresponding battery 200 at both room temperature and high temperature. Preferably, in Example 12, when the substituent at position 4 is a vinyl sulfate group, the corresponding battery 200 exhibits better cycle stability.

[0105] Furthermore, data from Examples 3, 2, and 3 show that the electrolytes 230 in Comparative Examples 2 and 3 do not contain the first additive. This results in poorer cycle stability of Comparative Battery 2 and Comparative Battery 3 at both room temperature and high temperature, further demonstrating the role of the first additive in improving the interfacial stability between the negative electrode 223 and the electrolyte 230. In addition, the cycle performance of Comparative Battery 2 is better than that of Comparative Battery 3. This is because the mass fraction of the second additive in the electrolyte 230 of Comparative Example 3 is too high, which increases the viscosity of the electrolyte 230, increases the transport resistance of active ions in the electrolyte 230, and ultimately affects the cycle performance of Comparative Battery 3.

[0106] Furthermore, data from Comparative Examples 5 and 6 show that the electrolyte 230 in Comparative Example 5 only includes the first additive, and the mass fraction of the first additive is too high. The electrolyte 230 in Comparative Example 6 includes both the first and second additives, but the mass fractions of both are too high. This results in poor cycle stability for both Comparative Battery 5 and Comparative Battery 6, and a high consumption of electrolyte 230. This is because: when the mass fraction of the first additive is too high, the inorganic component in the SEI film formed on the surface of the negative electrode 223 is too high, potentially leading to an excessively thick SEI film. This increases the interfacial impedance between the negative electrode 223 and the electrolyte 230, reducing the cycle performance of the corresponding battery 200. When the mass fraction of the second additive is too high, the viscosity of the electrolyte 230 is too high, increasing the resistance to the transport of active ions in the electrolyte 230 and reducing the conductivity of the electrolyte 230. Active ions are difficult to replenish from the electrolyte 230 to the surface of the negative electrode 223 in a timely manner, resulting in concentration polarization and reducing the safety performance of the corresponding battery 200.

[0107] Please see Figure 5 and Figure 6 This application provides an electrical device 300, which includes a device body 310 and a battery 200 provided in this application, wherein the battery 200 supplies power to the device body 310.

[0108] Understandably, the device body 310 and the battery 200 are electrically connected.

[0109] In this embodiment, the battery 200 includes the electrolyte 230 provided in this application, and the battery 200 has good cycle stability and high rate efficiency. When the battery 200 is applied to the electrical device 300, the battery 200 can provide stable power to the device body 310, which is beneficial to improving the user experience.

[0110] Optionally, the electrical device 300 in this application embodiment can be, but is not limited to, portable electronic devices such as mobile phones, tablets, laptops, desktop computers, smart bracelets, smartwatches, e-readers, and game consoles. It can also be a vehicle such as a car, truck, sedan, van, freight train, high-speed train, or electric vehicle. Furthermore, it can be various household appliances. Figure 6 In this embodiment, the electrical equipment 300 is an energy storage battery cabinet.

[0111] It is understood that the electrical device 300 described in this embodiment is merely one form of the electrical device 300 used by the battery 200, and should not be construed as a limitation on the electrical device 300 provided in this application, nor should it be construed as a limitation on the electrical device 300 provided in various embodiments of this application.

[0112] In this application, the terms "embodiment" and "implementation" mean that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of these phrases in various locations throughout the specification does not necessarily refer to the same embodiment, nor are they independent or alternative embodiments mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this application can be combined with other embodiments. Furthermore, it should be understood that the features, structures, or characteristics described in the various embodiments of this application can be arbitrarily combined to form another embodiment that does not depart from the spirit and scope of the technical solution of this application, provided there is no contradiction between them.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.

Claims

1. An electrolyte, characterized in that, The electrolyte includes a first additive, which is a fluorinated organophosphate lithium salt compound.

2. The electrolyte according to claim 1, characterized in that, The structural formula of the first additive is .

3. The electrolyte according to claim 1, characterized in that, The electrolyte further includes a second additive, the structural formula of which is: A includes hydrogen, methyl, ethyl, isopropyl, vinyl, At least one of them.

4. The electrolyte according to claim 3, characterized in that, In the electrolyte, the mass fraction of the first additive is a, and the mass fraction of the second additive is b. Then the electrolyte satisfies the relationship: 0.1≤b / a≤10.

5. The electrolyte according to claim 4, characterized in that, The electrolyte satisfies the following relationship: 0.2%≤a+b≤2%.

6. The electrolyte according to claim 2 or claim 4, characterized in that, The mass fraction 'a' of the first additive is in the range of 0.1% ≤ a ≤ 1%.

7. The electrolyte according to claim 4, characterized in that, The mass fraction b of the second additive is in the range of 0.1% ≤ b ≤ 1%.

8. The electrolyte according to any one of claims 1 to 7, characterized in that, The electrolyte further includes a solvent, which includes at least three of the following: dimethyl carbonate, diethyl carbonate, propylene carbonate, ethylene carbonate, methyl ethyl carbonate, ethyl acetate, propyl acetate, ethyl propionate, and propyl propionate.

9. A battery, characterized in that, The battery includes: A housing having a receiving cavity; Electrode assembly, the electrode assembly being located within the accommodating cavity; and The electrolyte according to any one of claims 1 to 8, wherein the electrolyte is located within the accommodating cavity for wetting at least a portion of the electrode assembly.

10. An electrical appliance, characterized in that, The electrical equipment includes: The equipment itself; and The battery of claim 9, wherein the battery supplies power to the device body.

Images