Electrolyte, battery and electric device

Abstract

The application relates to an electrolyte, a battery and a power utilization device. The electrolyte comprises a first additive and a second additive, the first additive is an hydantoin additive, and the second additive is a phosphate additive.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to an electrolyte, a battery and an electric device. BACKGROUND

[0002] With the continuous development of energy storage technology, lithium ion batteries are required to have a lower life attenuation amplitude and a longer service life. In the cycle process of lithium ion batteries, the life attenuation of the battery is mainly because the SEI film on the surface of the negative electrode plate is not firm enough, and the lithium ions on the surface of the negative electrode plate have a side reaction, so that the lithium is deposited on the surface of the negative electrode plate in the form of a salt. Therefore, in the long-term cycle of lithium ion batteries, how to build a more firm SEI film is an important means to improve the cycle performance of the battery and prolong the cycle life of the battery. SUMMARY

[0003] In view of this, the present application provides an electrolyte, a battery and an electric device, which has good thermal stability.

[0004] The present application provides an electrolyte, which comprises a first additive and a second additive, the first additive is a hydantoin additive, and the second additive is a phosphate additive.

[0005] Further, 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≤a / b≤5.

[0006] Further, the structural formula of the first additive is: wherein R1 is selected from at least one of hydrogen, halogen, methyl, trifluoromethyl, phenyl, cyano and nitro, R2 is selected from at least one of hydrogen, halogen, methyl, trifluoromethyl, phenyl, cyano and nitro, and R3 is selected from at least one of hydrogen, halogen, methyl, trifluoromethyl, phenyl, cyano, nitro and vinyl.

[0007] Further, the first additive is selected from at least one of and .

[0008] Further, the mass fraction a of the first additive ranges from 0.05% to 3%.

[0009] Further, the structural formula of the second additive is: wherein R4, R5 and R6 are selected from siloxyl.

[0010] Further, the second additive is selected from and at least one of TMS, i-Pr, and Ph, wherein TMS is a trimethylsilyl group, i-Pr is an isopropyl group, and Ph is a phenyl group.

[0011] Further, the mass fraction b of the second additive ranges from 0.1% to 1%.

[0012] The application further provides a battery, comprising: a positive electrode sheet, a separator, a negative electrode sheet, and the electrolyte provided by the application; the electrolyte is used to soak the positive electrode sheet, the separator, and the negative electrode sheet.

[0013] The application further provides a power-using device, comprising: a device body and the battery provided by the application, wherein the battery supplies power to the device body.

[0014] In the present application, the electrolyte comprises a first additive, the first additive is a hydantoin-based additive, the first additive has a heteroatom nitrogen and a cyclic structure, so that the first additive has a narrow electrochemical window, thereby the first additive is easy to obtain electrons. When the electrolyte is applied to a battery, the first additive is easy to obtain electrons on the surface of the negative electrode plate, the first additive is preferentially reduced to form a SEI (Solid Electrolyte Interface) film on the surface of the negative electrode plate than other components in the electrolyte such as solvents, second additives, etc. The SEI film formed by the first additive has a lower solubility in the electrolyte and has a higher elasticity and adhesion, so that the SEI film formed by the first additive is not easy to dissolve in the electrolyte and is not easy to break down during the deintercalation of lithium ions, which can slow down the side reactions of lithium ions on the surface of the negative electrode plate during the charge and discharge cycles of the battery, and can avoid excessive consumption of active lithium ions in the electrolyte, thereby the electrolyte has good cycle stability. In addition, the electrolyte also comprises a second additive, the second additive is a phosphate-based additive, the first additive and the second additive have a synergistic effect, which can effectively improve the thermal stability of the electrolyte. Specifically, when the first additive and the second additive are used together, the first additive is reduced to break the -C(O)-NR- to form an intermediate product, and the intermediate product further reacts with the second additive to break the -P-O- structure in the second additive, so as to further form C(O)-NR-, -PR(=O)-NR- and phosphate structures, etc., so that the SEI film formed by the first additive and the second additive on the interface of the negative electrode plate not only has organic structures such as -C(O)-NR-, -PR(=O)-NR-, but also has inorganic structures such as lithium phosphate, and the SEI film with inorganic components has higher ionic conductivity and thermal stability, so that even if the battery is cycled at high temperature, the SEI film formed by the first additive and the second additive is not easy to be damaged, the side reactions of active lithium ions in the electrolyte on the interface of the negative electrode plate are reduced, and the consumption of lithium ions is reduced, thereby the electrolyte has good thermal stability, and the battery has good cycle performance. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0016] Figure 1Partially sectional structural schematic view of a battery according to an embodiment of the present application;

[0017] Figure 2 Structural schematic view of an electrical apparatus according to an embodiment of the present application;

[0018] Figure 3 Circuit block diagram of an electrical apparatus according to an embodiment of the present application.

[0019] Explanation of Reference Signs:

[0020] 100 - battery, 110 - positive electrode sheet, 120 - separator, 130 - negative electrode sheet, 140 - electrolyte, 200 - electrical apparatus, 210 - apparatus body. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0022] The terms "first", "second", and the like in the specification of the present application and the above drawings are used to distinguish different objects, rather than to describe a particular order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or apparatus including a series of steps or units is not limited to the listed steps or units, but can optionally include other steps or units not listed or can optionally include other steps or units inherent to the process, method, product or apparatus.

[0023] Reference herein to "an embodiment" or "embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment or embodiments can be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor does it necessarily refer to a particular embodiment in an exclusive sense. It is explicitly and implicitly understood that the embodiments described herein can be combined with other embodiments.

[0024] With the continuous development of energy storage technology, lower life attenuation amplitude and longer service life of lithium ion batteries are required. During the cycle of the lithium ion battery, the life attenuation of the battery is mainly because of the side reaction of lithium ions on the surface of the negative electrode plate, which causes lithium to be deposited on the surface of the negative electrode plate in the form of salt. Specifically, on the one hand, during the charging process of the lithium ion battery, ester solvents are easily reduced on the surface of the negative electrode plate at low potential, so that the ester solvent reacts with lithium ions and consumes active lithium; on the other hand, the lithium ion battery generally uses graphite as the active material of the negative electrode plate, and the delithiation and lithium intercalation behavior of lithium ions on the negative electrode plate will cause the graphite layer spacing to continuously increase and decrease, so that the SEI film on the surface of the negative electrode plate is continuously pulled, exposing the new graphite interface to contact and react with the electrolyte, thereby causing the consumption of active lithium ions. In the long-term cycle of the lithium ion battery, how to build a more solid SEI film is an important means to improve the cycle performance of the battery and prolong the cycle life of the battery.

[0025] Please refer to Figure 1 The battery 100 provided by the application comprises a positive electrode plate 110, a separator 120, a negative electrode plate 130 and an electrolyte 140 provided by the application; the electrolyte 140 is used to soak the positive electrode plate 110, the separator 120 and the negative electrode plate 130.

[0026] Understandably, the separator 120 is arranged on one side of the positive electrode plate 110, and the negative electrode plate 130 is arranged on the side of the separator 120 away from the positive electrode plate 110.

[0027] Understandably, the positive electrode plate 110, the separator 120 and the negative electrode plate 130 are arranged in layers, and the positive electrode plate 110, the separator 120 and the negative electrode plate 130 form an electrode assembly.

[0028] Optionally, in some embodiments, the battery 100 is a lithium ion battery.

[0029] Understandably, the electrolyte 140 is used to soak the positive electrode plate 110, the separator 120 and the negative electrode plate 130 to realize the transmission of active ions between the positive electrode plate 110 and the negative electrode plate 130 in the battery 100. When the battery 100 is a lithium ion battery 100, the active ions are lithium ions.

[0030] In the embodiment, the battery 100 comprises the electrolyte 140 provided by the application, the electrolyte 140 comprises a first additive and a second additive, the first additive is a hydantoin additive, the second additive is a phosphate additive, the first additive and the second additive have a synergistic effect, so that the SEI film formed by the first additive and the second additive on the surface of the negative electrode plate 130 has good chemical stability and thermal stability, which can slow down the consumption of lithium ions in the electrolyte 140 due to the side reaction between other components in the electrolyte 140 and the negative electrode plate 130, and can also reduce the lithium ions consumed due to the repair loss of the broken SEI film, and can reduce the life attenuation amplitude of the battery 100, so that the battery 100 has good cycle performance even in a high-temperature environment, and the battery 100 has a long service life.

[0031] The application provides an electrolyte 140, which comprises a first additive and a second additive, the first additive is a hydantoin additive, and the second additive is a phosphate additive.

[0032] It can be understood that the electrolyte 140 further comprises a solvent for dissolving the first additive and the second additive.

[0033] In the present embodiment, the electrolyte 140 comprises a first additive, which is a hydantoin-based additive, and the first additive has a heteroatom nitrogen and a cyclic structure, so that the first additive has a narrow electrochemical window, and thus the first additive is prone to obtain electrons. When the electrolyte 140 is applied to the battery 100, the first additive is prone to obtain electrons on the surface of the negative electrode plate 130, and the first additive is prone to have a reduction reaction than other components in the electrolyte 140, such as a solvent, a second additive, etc., so that a SEI (Solid Electrolyte Interface) film is preferentially formed on the surface of the negative electrode plate 130. The SEI film formed by the first additive has a lower solubility in the electrolyte 140, and has a higher elasticity and adhesion, so that the SEI film formed by the first additive is not prone to be dissolved in the electrolyte 140, and is not prone to be broken during the deintercalation of lithium ions, and thus the side reaction of lithium ions on the surface of the negative electrode plate 130 during the charge-discharge cycle of the battery 100 can be slowed down, and the active lithium ions in the electrolyte 140 can be prevented from being excessively consumed, so that the electrolyte 140 has good cycle stability. In addition, the electrolyte 140 further comprises a second additive, which is a phosphate-based additive, and the first additive and the second additive have a synergistic effect, so that the thermal stability of the electrolyte 140 can be effectively improved. Specifically, when the first additive and the second additive are used together, the first additive has a reduction reaction to break -C(O)-NR- to generate an intermediate product, and the intermediate product further reacts with the second additive to break -P-O- structure in the second additive, so that C(O)-NR-, -PR(=O)-NR-, and phosphate structures, etc. are further formed, so that the SEI film formed by the first additive and the second additive on the interface of the negative electrode plate 130 not only has organic structures such as -C(O)-NR-, -PR(=O)-NR-, etc., but also has inorganic structures such as lithium phosphate, and the SEI film with inorganic components has higher ionic conductivity and thermal stability, so that even if the battery 100 is cycled at high temperature, the SEI film formed by the first additive and the second additive is not prone to be damaged, the side reaction of active lithium ions in the electrolyte 140 on the interface of the negative electrode plate 130 can be reduced, and the consumption of lithium ions can be reduced, so that the electrolyte 140 has good thermal stability, and the battery 100 has good cycle performance.

[0034] It can be understood that the first additive has a narrow electrochemical window, and the HOMO energy of the first additive is high and the LUMO energy of the first additive is low, wherein the HOMO is the highest occupied molecular orbital of the first additive, the LUMO is the lowest unoccupied molecular orbital of the first additive, the higher the HOMO energy, the easier the first additive loses electrons, and the lower the LUMO energy, the easier the first additive obtains and accepts electrons.

[0035] It can be understood that the SEI film formed by the first additive and the second additive includes an organic layer containing amide and phosphoramide, and also includes an inorganic layer containing lithium phosphate.

[0036] It can be understood that, in the terms of the present application, "high temperature" is relative to "room temperature", and room temperature generally refers to a temperature between 10°C and 30°C, and high temperature generally refers to a temperature greater than 30°C. Here, only examples of high temperature and room temperature are given, and they should not be understood as limitations on high temperature and room temperature.

[0037] It can be understood that the electrolyte 140 further includes an electrolyte, which is a lithium salt, including but not limited to lithium hexafluorophosphate, and the electrolyte is dissolved in a solvent to provide lithium ions for the battery 100.

[0038] Optionally, the solvent is selected from at least one of ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate.

[0039] In some embodiments, the structural formula of the first additive is: wherein R1 is selected from at least one of hydrogen, halogen, methyl, trifluoromethyl, phenyl, cyano, and nitro, R2 is selected from at least one of hydrogen, halogen, methyl, trifluoromethyl, phenyl, cyano, and nitro, and R3 is selected from at least one of hydrogen, halogen, methyl, trifluoromethyl, phenyl, cyano, nitro, and vinyl.

[0040] It can be understood that in the structural formula of the first additive, R1, R2 and R3 can be selected from the same group of hydrogen, halogen, methyl, trifluoromethyl, phenyl, cyano, and nitro, and R1, R2 and R3 can also be selected from different groups of hydrogen, halogen, methyl, trifluoromethyl, phenyl, cyano, and nitro.

[0041] It can be understood that halogen includes fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At), and fluorine, trifluoromethyl, cyano, and nitro are electron-withdrawing groups that can further reduce the LUMO energy of the first additive.

[0042] It can be understood that in the terms of the present application, "at least one" means one or more, and "multiple" means greater than or equal to two.

[0043] In the present embodiment, the first additive has a structural formula of The first additive has a cyclic structure and has two nitrogen atoms, so that the first additive preferentially obtains electrons on the surface of the negative electrode plate 130 over other components in the electrolyte 140 and forms a stable SEI film to slow down the reduction of the solvent in the electrolyte 140 on the surface of the negative electrode plate 130 to consume too many lithium ions. In addition, when the first additive and the second additive are used together, the intermediate product formed by the reduction of the first additive can combine with the second additive, so that an SEI film containing organic components and inorganic components is formed on the surface of the negative electrode plate 130, to improve the thermal stability of the SEI film and make the electrolyte 140 have better thermal stability. Further, R1, R2may be selected from at least one of hydrogen, halogen, methyl, trifluoromethyl, phenyl, cyano, nitro, and R3may be selected from at least one of hydrogen, halogen, methyl, trifluoromethyl, phenyl, cyano, nitro, and vinyl, which is conducive to improving the richness of the components of the SEI film formed by the first additive, thereby further improving the thermal stability of the SEI film, reducing the consumption of lithium ions for repairing the SEI film, and thus making the electrolyte 140 have better thermal stability and the battery 100 have higher capacity retention rate.

[0044] In particular, when at least one of R1, R2and R3is selected from electron-withdrawing groups such as fluorine, trifluoromethyl, cyano and nitro, the electron-withdrawing group will lower the LUMO energy of the first additive, making the first additive more likely to obtain electrons, ensuring that the first additive forms an SEI film on the surface of the negative electrode plate 130 better than other components in the electrolyte 140, and in addition, the SEI film formed by the first additive containing fluorine or trifluoromethyl has more lithium fluoride, and the inorganic component lithium fluoride can further reduce the solubility of the SEI film in the electrolyte 140, thereby slowing down the dissolution of the SEI film in the electrolyte 140 during charge and discharge cycles, improving the thermal stability of the SEI film, and making the electrolyte 140 have better thermal stability.

[0045] In particular, when at least one of R1, R2and R3is selected from phenyl, the organic polymer containing phenyl can improve the flexibility of the SEI film, reduce the possibility of the SEI film being broken during repeated delithiation and lithiation, thereby improving the stability of the SEI film, avoiding the consumption of too many lithium ions in the electrolyte 140 for repairing the SEI film, and the electrolyte 140 has better stability, and the battery 100 has better cycle performance.

[0046] In some embodiments, the first additive is selected from at least one of and

[0047] ​In the present embodiment, when the first additive is selected from at least one of and , the first additive can preferentially form a stable SEI film on the surface of the negative electrode sheet 130 to insulate the electrolyte 140 and the negative electrode sheet 130, and slow down the reduction reaction of the solvent in the electrolyte 140 on the surface of the negative electrode sheet 130 to consume too much lithium ion. In addition, the first additive and the second additive have a synergistic effect, and the intermediate product formed by the reduction reaction of the first additive can combine with the second additive to form an SEI film containing organic and inorganic components on the surface of the negative electrode sheet 130, thereby improving the thermal stability of the SEI film and the thermal stability of the electrolyte 140. In particular, and contain electron-withdrawing groups, so that the first additive has a lower LUMO energy and is more likely to obtain electrons, ensuring that the first additive is superior to other components in the electrolyte 140 in forming an SEI film on the surface of the negative electrode sheet 130. In addition, the SEI film formed by the first additive containing fluorine or a trifluoromethyl group has more lithium fluoride, and the inorganic component lithium fluoride can further reduce the solubility of the SEI film in the electrolyte 140, thereby slowing down the dissolution of the SEI film in the electrolyte 140 during charging and discharging cycles, improving the thermal stability of the SEI film, and improving the thermal stability of the electrolyte 140. contains a phenyl group, the first additive can form a polymer containing a phenyl group and form an SEI film. The organic polymer containing a phenyl group can improve the flexibility of the SEI film and reduce the possibility of the SEI film being broken during repeated lithium extraction and lithium intercalation, thereby improving the stability of the SEI film, avoiding the consumption of too much lithium ion in the electrolyte 140 due to the repair of the SEI film, and improving the stability of the electrolyte 140 and the cycle performance of the battery 100. contains a vinyl group, so that the SEI film formed by the first additive has a higher degree of polymerization and structural stability, further inhibiting the destruction of the SEI film by hydrogen fluoride in the electrolyte 140, thereby improving the cycle stability of the battery 100. is dimethyl-substituted, which can inhibit the dissociation of hydrogen on the nitrogen atom, prevent the increase of the content of hydrogen fluoride in the electrolyte 140, maintain the structural stability of the first additive, and further improve the cycle performance of the battery 100.

[0048] In some embodiments, the structural formula of the second additive is: wherein R4, R5, and R6 are selected from siloxyl groups.

[0049] It is appreciated that R4, R5, and R6 can be independently selected from substituted siloxy groups, and R4, R5, and R6 can also be independently selected from unsubstituted siloxy groups.

[0050] In this embodiment, the second additive has a structural formula of The second additive is a phosphate-based additive and has a -P-O- structure. When the first additive and the second additive are used together, the intermediate product formed by the reduction reaction of the first additive reacts with the second additive, so that the -P-O- structure in the second additive is broken, facilitating the further formation of C(O)-NR- structure, -PR(=O)-NR- structure, phosphate structure, and the like. After the reduction reaction of the second additive, lithium phosphate can also be formed by the combination of lithium ions in the electrolyte 140, so that the SEI film formed by the first additive and the second additive not only has organic structures such as -C(O)-NR-, -PR(=O)-NR-, but also has inorganic structures such as lithium phosphate. The SEI film with inorganic components has higher ionic conductivity and thermal stability. Therefore, even if the battery 100 is under high-temperature cycling, the SEI film formed by the first additive and the second additive is not easily damaged, the side reactions of active lithium ions in the electrolyte 140 at the interface of the negative electrode tab 130 are reduced, the consumption of lithium ions is reduced, so that the electrolyte 140 has good thermal stability, and the battery 100 has good cycle performance. Further, R4, R5, and R6 are selected from siloxy groups, which can react with hydrogen fluoride in the electrolyte to generate phosphorus-containing organic matter, and then participate in the construction of the SEI film, so that the content of lithium phosphate in the generated SEI film is higher, which is beneficial to improve the thermal stability of the SEI film, further improve the thermal stability of the electrolyte 140, and inhibit the decomposition of the electrolyte 140.

[0051] Alternatively, the structural general formula of the siloxy group is -OSiR7R8R9, and R7, R8, and R9 are selected from any group, in other words, there is no any limitation on the types of R7, R8, and R9. For example, R7, R8, and R9 are each independently selected from alkyl groups, phenyl groups, fluorine atoms, and the like.

[0052] In some embodiments, the second additive is selected from at least one of and wherein TMS is a trimethylsilyl group, and i-Pr is an isopropyl group.

[0053] In this embodiment, when the second additive is selected from at least one of and When the second additive is added into the electrolyte 140, the second additive can react with the first additive and form SEI film with organic structure of -C(O)-NR-, -PR(=O)-NR-, etc. and inorganic structure of lithium phosphate, etc. SEI film with inorganic component has higher ionic conductivity and thermal stability. Therefore, even if the battery 100 is under high temperature cycling, SEI film formed by the first additive and the second additive is not easy to be damaged. The side reaction of active lithium ions in the electrolyte 140 at the interface of the negative electrode plate 130 is reduced, the consumption of lithium ions is reduced, so that the electrolyte 140 has better thermal stability, and the battery 100 has better cycle performance. Further, and all contain silicon elements. The silicon-containing groups can react with hydrogen fluoride in the electrolyte to generate phosphorus-containing organic matter, which further participates in the construction of SEI film, so that the content of lithium phosphate in the generated SEI film is higher, which is beneficial to improve the thermal stability of SEI film, further improve the thermal stability of electrolyte 140, and inhibit the decomposition of electrolyte 140.

[0054] In some embodiments, the mass fraction a of the first additive ranges from 0.05% to 3%.

[0055] It can be understood that in the electrolyte 140, the mass fraction a of the first additive is the ratio of the mass of the first additive to the mass of the electrolyte 140.

[0056] Specifically, the mass fraction a of the first additive can be, but is not limited to, 0.05%, 0.08%, 0.1%, 0.3%, 0.55%, 0.6%, 0.7%, 0.85%, 0.9%, 1%, 1.2%, 1.3%, 1.45%, 1.5%, 1.6%, 1.7%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.5%, 2.6%, 2.9%, and 3%, etc.

[0057] In the present embodiment, when the mass fraction a of the first additive satisfies the range 0.05%≤a≤3%, the mass fraction of the first additive is within a reasonable range. On the one hand, the first additive can preferentially form an SEI film on the surface of the negative electrode sheet 130, so as to reduce the contact between the solvent in the electrolyte 140 and the negative electrode sheet 130, slow down the reaction between the solvent and the negative electrode sheet 130, reduce the consumption of active lithium ions while providing a stable SEI film, thereby making the electrolyte 140 have better stability. On the other hand, the intermediate product of the first additive in the reduction process can react with the second additive and form an SEI film with both organic structures such as -C(O)-NR-, -PR(=O)-NR-, and inorganic structures such as lithium phosphate, thereby making the SEI film have better thermal stability. Even if the battery 100 is in a high-temperature environment or the temperature rises as the charge and discharge cycle progresses, the SEI film can still remain intact, improving the thermal stability of the electrolyte 140, and the battery 100 has better cycle performance in a high-temperature environment. When the mass fraction of the first additive is too large, the SEI film formed by the first additive is too thick, which increases the impedance of lithium ions in the electrolyte 140 passing through the SEI film, affects the kinetic performance of the battery 100, causes lithium precipitation in the battery 100 during the charge and discharge cycle, consumes too much active lithium ion, and reduces the cycle performance of the battery 100. When the mass fraction of the first additive is too small, although the first additive can preferentially form an SEI film on the surface of the negative electrode sheet 130, the SEI film formed by the first additive is difficult to completely cover the surface of the negative electrode sheet 130, and the solvent in the electrolyte 140 is easy to directly contact the negative electrode sheet 130 and react to consume lithium ions in the electrolyte 140, which is an irreversible loss and reduces the cycle performance of the battery 100. Furthermore, too large or too small mass fraction of the first additive will result in too single composition of the SEI film formed by the first additive and the second additive, thereby being not conducive to improving the thermal stability of the SEI film, and when the battery 100 is in a high-temperature environment or the temperature of the battery 100 rises during the charge and discharge process, the SEI film is easy to be damaged and consume more lithium ions in the electrolyte 140 to repair, thereby making the thermal stability of the electrolyte 140 low and the cycle performance of the battery 100 in a high-temperature environment poor.

[0058] Preferably, the mass fraction a of the first additive satisfies the range 0.3%≤a≤1%. Specifically, the value of the mass fraction a of the first additive can be, but is not limited to, 0.3%, 0.55%, 0.6%, 0.7%, 0.85%, 0.9%, 1%, and the like.

[0059] In some embodiments, the mass fraction b of the second additive satisfies the range 0.1%≤b≤1%.

[0060] It can be understood that in the electrolyte 140, the mass fraction b of the second additive is the ratio of the mass of the second additive to the mass of the electrolyte 140.

[0061] Specifically, the value of the mass fraction b of the second additive can be, but is not limited to, 0.1%, 0.2%, 0.25%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.75%, 0.8%, 0.9%, and 1%, etc.

[0062] In the present embodiment, when the mass fraction b of the second additive satisfies the range 0.1%≤b≤1%, the mass fraction of the second additive is within a reasonable range, and the second additive can combine with the intermediate product formed by the reduction reaction of the first additive to form an SEI film with both organic structures such as -C(O)-NR-, -PR(=O)-NR-, etc. and inorganic structures such as lithium phosphate, thereby enhancing the thermal stability of the SEI and improving the cycle performance of the battery 100 in a high-temperature environment. When the mass fraction of the second additive is too large, the SEI film formed by the second additive is too thick, increasing the impedance of lithium ions in the electrolyte 140 passing through the SEI film, affecting the kinetic performance of the battery 100, causing lithium to be precipitated during the charge and discharge cycle of the battery 100, consuming too much active lithium ion, and reducing the cycle performance of the battery 100. In addition, the second additive can also consume too much lithium ion to form lithium phosphate, thereby reducing the amount of active lithium ion in the electrolyte 140. When the mass fraction of the second additive is too small, the proportion of -P=O- structures in the electrolyte 140 is small, and when the first additive and the second additive are used together, the SEI film formed by the first additive and the second additive has less lithium phosphate formed by the combination of -P=O- structures and lithium ions, in other words, the SEI film has less inorganic components, thereby making the thermal stability of the SEI film poor, and reducing the cycle performance of the battery 100 in a high-temperature environment. Furthermore, too large or too small mass fraction of the second additive will cause the components of the SEI film formed by the first additive and the second additive to be too single, thereby being not conducive to improving the thermal stability of the SEI film, and when the battery 100 is in a high-temperature environment or the temperature of the battery 100 increases during the charge and discharge process, the SEI film is easily damaged and consumes more lithium ions of the electrolyte 140 to repair, thereby making the thermal stability of the electrolyte 140 low and the cycle performance of the battery 100 in a high-temperature environment poor.

[0063] Preferably, the mass fraction b of the second additive ranges from 0.2% to 0.5%. Specifically, the value of the mass fraction b of the second additive can be, but is not limited to, 0.2%, 0.25%, 0.3%, 0.4%, and 0.5%, etc.

[0064] In some embodiments, in the electrolyte 140, the mass fraction of the first additive is a, and the mass fraction of the second additive is b, and the electrolyte 140 satisfies the relationship: 0.1≤a / b≤5.

[0065] Specifically, the value of a / b can be, but is not limited to, 0.1, 0.2, 0.35, 0.5, 0.6, 0.8, 0.9, 1, 1.1, 1.3, 1.4, 1.5, 1.7, 1.8, 1.9, 2, 2.1, 2.3, 2.5, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.7, and 5, etc.

[0066] In the embodiment, when the mass fraction a of the first additive and the mass fraction b of the second additive satisfy the relationship 0.1≤a / b≤5, the value of the mass fraction a of the first additive and the value of the mass fraction b of the second additive are both within a reasonable range, and the first additive and the second additive have a good synergistic effect, so that the SEI film formed by the first additive and the second additive under a high-temperature environment has good stability, thereby making the electrolyte 140 have good stability. Specifically, the first additive can preferentially form a SEI film on the surface of the negative electrode tab 130 to reduce the contact between the solvent in the electrolyte 140 and the negative electrode tab 130, slow down the reaction between the solvent and the negative electrode tab 130, reduce the consumption of active lithium ions while providing a stable SEI film, thereby making the electrolyte 140 have good stability. In addition, the amount of the intermediate product of the first additive in the reduction process is within a reasonable range, which can synergistically react with the second additive and form a SEI film having both organic structures such as -C(O)-NR-, -PR(=O)-NR-, and inorganic structures such as lithium phosphate, thereby making the SEI film have good thermal stability. Even if the battery 100 is in a high-temperature environment or the temperature rises as the charge and discharge cycles proceed, the SEI film can still remain intact, improving the thermal stability of the electrolyte 140, and the battery 100 has good cycle performance in a high-temperature environment. When the value of a / b is too large, the mass fraction of the first additive is too large, or the mass fraction of the second additive is too small, on the one hand, it can cause the SEI film formed by the first additive and the second additive to be too thick, thereby increasing the internal resistance of the battery 100 and reducing the cycle performance of the battery 100; on the other hand, it can cause the content of inorganic components such as lithium phosphate in the formed SEI film to be too low, thereby causing the thermal stability of the SEI film to decrease, the capacity retention rate of the battery 100 in a high-temperature environment to decrease, and the high-temperature cycle performance of the battery 100 to be poor. When the value of a / b is too small, the mass fraction of the first additive is too small, or the mass fraction of the second additive is too large, although the first additive can preferentially form a SEI film on the surface of the negative electrode tab 130, the SEI film formed by the first additive is difficult to completely cover the surface of the negative electrode tab 130, and the solvent in the electrolyte 140 is easy to directly contact the negative electrode tab 130 and react to consume lithium ions in the electrolyte 140, which is an irreversible loss, thereby reducing the cycle performance of the battery 100. In addition, the first additive generates less intermediate product in the reduction process, which is difficult to effectively combine with the second additive, thereby making it difficult for the second additive to form lithium phosphate, and also causing the content of inorganic components such as lithium phosphate in the formed SEI film to be too low, thereby causing the thermal stability of the SEI film to decrease, the capacity retention rate of the battery 100 in a high-temperature environment to decrease, and the high-temperature cycle performance of the battery 100 to be poor.Therefore, if the value of a / b is too large or too small, the SEI film formed by the first additive and the second additive will have too single composition, and thus the thermal stability of the electrolyte 140 will be poor.

[0067] Preferably, the electrolyte 140 satisfies the relationship: 1≤a / b≤2. Specifically, the value of a / b 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, and 2, etc.

[0068] Alternatively, in some embodiments, the electrolyte 140 also satisfies the relationship: 0.6%≤a+b≤1.5%. Specifically, the value of a+b can be, but is not limited to, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, and 1.5%, etc.

[0069] In the present embodiment, when the electrolyte 140 satisfies the relationship 0.6%≤a+b≤1.5%, the mass fraction of the first additive and the mass fraction of the second additive in the electrolyte 140 are both within a reasonable range, and the first additive and the second additive have a good synergistic effect, so that the SEI film formed by the first additive and the second additive under high temperature environment has good stability, thereby making the electrolyte 140 have good stability. When the electrolyte 140 is applied to the battery 100, the battery 100 has good cycle performance.

[0070] The technical solutions of the present application will be further introduced in the following embodiments:

[0071] Embodiments 1 to 31, Comparative Examples 1 to 6:

[0072] 1. Preparation of the electrolyte 140:

[0073] In an argon atmosphere glove box with water content ≤1 ppm, ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate were mixed according to a mass ratio of 1:1:1, and then the dry electrolyte lithium salt lithium hexafluorophosphate was dissolved into the solvent, stirred until completely dissolved and uniform, the first additive and the second additive were added, and the electrolyte 140 of embodiments 1 to 31 and comparative examples 1 to 6 was obtained after uniform mixing. The obtained electrolyte 140 is composed of: the solvent is composed of ethylene carbonate, dimethyl carbonate, and methyl ethyl carbonate with a mass ratio of 1:1:1, and the lithium salt concentration is 1 mol / L.

[0074] In the electrolyte 140 of embodiments 1 to 31 and comparative examples 1 to 6, the type of the first additive, the value of the mass fraction a of the first additive, the type of the second additive, the value of the mass fraction b of the second additive, and the value of a / b are shown in Table 1.

[0075] 2. Preparation of the positive electrode tab 110:

[0076] The positive electrode active material lithium iron phosphate, the positive electrode conductive agent conductive carbon black (SP), and the positive electrode binder polyvinylidene fluoride (PVDF) are dispersed into the solvent N-methyl-2-pyrrolidone (NMP) in a proportioning manner to mix uniformly to obtain a positive electrode slurry with a solid content of 60wt%, the positive electrode slurry is coated on the positive electrode current collector (aluminum foil), the coating weight of the positive electrode slurry is 300mg / 1540.25mm 2 After drying, cold pressing, slitting, and cutting, the positive electrode tab 110 is obtained.

[0077] 3. Preparation of the negative electrode tab 130:

[0078] The negative electrode active material hard carbon, the negative electrode conductive agent conductive carbon black (SP), the negative electrode thickening agent carboxymethyl cellulose (CMC), the negative electrode binder styrene-butadiene rubber (SBR), and asphalt are dispersed in deionized water in a proportioning manner to mix uniformly to obtain a negative electrode slurry with a solid content of 50wt%, the negative electrode slurry is coated on the negative electrode current collector (copper foil), the coating weight of the negative electrode slurry is 144mg / 1540.25mm 2 After drying, cold pressing, slitting, and cutting, the negative electrode tab 130 is obtained.

[0079] 4. Preparation of the separator 120:

[0080] The 16um polyethylene film is used as the separator 120.

[0081] 5. Preparation of the battery 100:

[0082] The prepared positive electrode tab 110, the separator 120, and the negative electrode tab 130 are stacked in order, with the separator 120 in the middle of the positive electrode tab 110 and the negative electrode tab 130, the electrode assembly is obtained after winding the positive electrode tab 110, the separator 120, and the negative electrode tab 130, the electrode assembly is assembled into the outer package after welding the tab, the prepared electrolyte 140 is injected, and the cell is packaged, placed, formed, shaped, and tested for capacity, etc., finally the implementation batteries 1 to 31 and the comparison batteries 1 to 6 are prepared.

[0083] Among them, the electrolyte 140 of Example 1 is applied to the implementation battery 1, the electrolyte 140 of Example 2 is applied to the implementation battery 2, the electrolyte 140 of Comparative Example 1 is applied to the comparison battery 1, the electrolyte 140 of Comparative Example 2 is applied to the comparison battery 2, and so on.

[0084] Table 1 below is the component parameter table of the electrolyte 140 of Examples 1 to 31 and Comparative Examples 1 to 6.

[0085] Table 1: Component parameters of electrolyte 140 of Examples 1-31 and Comparative Examples 1-6.

[0086]

[0087]

[0088] It can be understood that the electrolyte 140 of Comparative Example 1 does not include the first additive nor the second additive, the electrolyte 140 of Comparative Example 2 includes only the first additive but not the second additive, and the electrolyte 140 of Comparative Example 3 includes only the second additive but not the first additive.

[0089] In Table 1, the structural formula of the first additive of Formula 1-1 is The structural formula of the first additive of Formula 1-2 is The structural formula of the first additive of Formula 1-3 is The structural formula of the first additive of Formula 1-4 is The structural formula of the first additive of Formula 1-5 is The structural formula of the first additive of Formula 1-6 is

[0090] In Table 1, the structural formula of the second additive of Formula 2-1 is The structural formula of the second additive of Formula 2-2 is The structural formula of the second additive of Formula 2-3 is The structural formula of the second additive of Formula 2-4 is

[0091] Performance test of battery 100:

[0092] Test of cycle performance of Examples 1-31 and Comparative Examples 1-6 at high temperature:

[0093] The above Examples 1-31 and Comparative Examples 1-6 were subjected to constant current charge-discharge cycle test on a charge-discharge instrument, the test temperature was 45°C, the charge-discharge rate was 1P (the size of the charge-discharge current is usually represented by the charge-discharge rate, and the calculation formula of the charge-discharge current is: charge-discharge power = battery 100 voltage platform (3.2V) x rated capacity of battery 100), the charge-discharge voltage window was 2.5V to 3.65V (i.e. the charge cut-off voltage of battery 100 was 3.65V, and the discharge cut-off voltage of battery 100 was 2.5V; it is generally considered that when the charge cut-off voltage is ≥4V, the charge cut-off voltage of battery 100 is high), the capacity retention rate after 1000 cycles was calculated, and the calculation formula was: capacity retention rate after the Nth cycle = (discharge capacity after the Nth cycle / discharge capacity of the first cycle) x 100%.

[0094] wherein, generally, one complete charge-discharge is referred to as one charge-discharge cycle, that is, the battery 100 is first charged from 2.5 V to 3.65 V, and then discharged from 3.65 V to 2.5 V, thereby forming one charge-discharge cycle. The cycle is repeated N times, i.e., the above process is repeated N times.

[0095] The values of the capacity retention rate of the battery 1 to the battery 31, the comparative battery 1 to the comparative battery 6 cycled 1000 times at 45°C are shown in Table 2.

[0096] Table 2 below is the performance parameters of the battery 1 to the battery 31, the comparative battery 1 to the comparative battery 6.

[0097] Table 2: Performance parameters of the battery 1 to the battery 31, the comparative battery 1 to the comparative battery 6.

[0098]

[0099]

[0100] It can be understood that the capacity retention rate cycled 1000 times at 45°C can represent the cycle performance of the battery 100 in a high temperature environment, and the greater the capacity retention rate cycled 1000 times at 45°C, the better the cycle performance of the battery 100 in a high temperature environment.

[0101] As can be seen from Table 1 and Table 2, the capacity retention of Comparative Battery 1 to Comparative Battery 3 at 45°C for 1000 cycles at 1P is lower than that of Example Battery 1 to Example Battery 31 at 45°C for 1000 cycles at 1P, because: the electrolyte 140 of Comparative Example 1 does not include the first additive and the second additive, during the charge-discharge cycle of the battery 100, with the embedding and stripping of lithium ions on the surface of the negative electrode plate 130, the SEI film is constantly expanding and shrinking, so that the cycle stability of the SEI film at high temperature is poor, therefore the SEI film is constantly destroyed and repaired, and the process of generating the SEI film is the process of the components of the electrolyte 140 losing and gaining electrons on the surface of the active material, which is accompanied by the loss of active lithium ions, and it is irreversible loss, the decrease of the content of active lithium ions leads to the poor charge-discharge cycle capacity of Comparative Battery 1. The electrolyte 140 of Comparative Example 2 only includes the first additive but not the second additive, and the electrolyte 140 of Comparative Example 3 only includes the second additive but not the first additive, the cycle performance of Comparative Battery 2 and Comparative Battery 3 is slightly improved compared with Comparative Battery 1. However, when the electrolyte 140 only includes at least one of the first additive and the second additive, the first additive and the second additive cannot work synergistically, in other words, the stability of the SEI film formed by the electrolyte 140 of Comparative Example 2 and Comparative Example 3 is still poor, so that the stability of the electrolyte 140 is poor, and the cycle performance of Comparative Battery 2 and Comparative Battery 3 is poor.

[0102] As can be seen from the data of Example 1 to Example 20, in the first aspect, as can be seen from the data of Example 1 to Example 5 and Comparative Example 4, the structural formula of the first additive in the electrolyte 140 of Example 1 to Example 5 is The mass fraction a of the first additive satisfies the range 0.05%≤a≤3%, and a / b satisfies the range 0.1≤a / b≤5, while the mass fraction of the first additive in Comparative Example 4 is less than 0.05%, and the value of a / b is less than 0.1, which makes the capacity retention rate of the batteries 1 to 5 at 45°C at 1P for 1000 cycles higher than that of the comparative battery 4 at 45°C at 1P for 1000 cycles, and as the mass fraction of the first additive gradually increases, the cycle performance of the corresponding battery 100 first improves and then decreases, because: when the value of a is in a reasonable range, and a / b is in a reasonable range, the first additive and the second additive have a good synergistic effect, the first additive can preferentially form an SEI film on the surface of the negative electrode plate 130 to reduce the contact between the solvent in the electrolyte 140 and the negative electrode plate 130, slow down the reaction between the solvent and the negative electrode plate 130, and reduce the consumption of active lithium ions while providing a stable SEI film. In addition, the amount of intermediate product of the first additive in the reduction process is in a reasonable range, which can react with the second additive to form an SEI film with both organic structures such as -C(O)-NR-, -PR(=O)-NR-, and inorganic structures such as lithium phosphate, so that the SEI film has good thermal stability, thereby making the corresponding battery 100 have good cycle performance. Furthermore, when the mass fraction a of the first additive is too small or too small, the first additive can form an SEI film on the surface of the negative electrode plate 130, but the SEI film formed by the first additive is difficult to completely cover the surface of the negative electrode plate 130, and the solvent in the electrolyte 140 is easy to directly contact with the negative electrode plate 130 and react to consume lithium ions in the electrolyte 140, and this process is irreversible, which reduces the cycle performance of the battery 100. When the mass fraction a of the first additive is too large, the SEI film formed by the first additive is too thick, which increases the impedance of lithium ions in the electrolyte 140 passing through the SEI film, affects the kinetic performance of the battery 100, causes lithium precipitation in the battery 100 during the charge and discharge cycle, consumes too much active lithium ions, and reduces the cycle performance of the battery 100. Therefore, as the mass fraction a of the first additive increases, the cycle performance of the corresponding battery 100 first improves and then decreases.

[0103] Similarly, from the data of Examples 6 to 8, it can be seen that the structural formula of the first additive in the electrolyte 140 of Examples 6 to 8 is and as the mass fraction of the first additive gradually increases, the cycle performance of the corresponding battery 100 first improves and then decreases. From the data of Examples 9 to 11, it can be seen that the structural formula of the first additive in the electrolyte 140 of Examples 9 to 11 is and with the gradual increase of the mass fraction of the first additive, the cycle performance of the battery 100 corresponding thereto first increases and then decreases. From the data of Example 12 to Example 14, it can be known that the structural formula of the first additive in the electrolyte 140 of Example 12 to Example 14 is and with the gradual increase of the mass fraction of the first additive, the cycle performance of the battery 100 corresponding thereto first increases and then decreases. From the data of Example 15 to Example 17, it can be known that the structural formula of the first additive in the electrolyte 140 of Example 15 to Example 17 is and with the gradual increase of the mass fraction of the first additive, the cycle performance of the battery 100 corresponding thereto first increases and then decreases. From the data of Example 18 to Example 20, it can be known that the structural formula of the first additive in the electrolyte 140 of Example 18 to Example 20 is and with the gradual increase of the mass fraction of the first additive, the cycle performance of the battery 100 corresponding thereto first increases and then decreases.

[0104] Furthermore, from the data of Example 3, Example 7, Example 10, Example 13, Example 16 and Example 19, it can be known that under the condition of the same other conditions, the type of the first additive of the electrolyte 140 can affect the cycle performance of the battery 100. Among them, the first additive of Example 3 and Example 7 includes fluorine, so that the content of LiF in the SEI film generated thereby is increased, and the thermal stability and acid resistance of the SEI film are improved. The first additive of Example 13 includes a phenyl group, and the polymer containing the phenyl group is beneficial to improve the flexibility of the SEI film, reduce the possibility of the SEI film from being broken in the process of repeated lithium intercalation and deintercalation, thereby improving the high-temperature performance of the battery 13. The first additive of Example 16 includes a vinyl group, so that the SEI film formed by the first additive has higher polymerization degree and structural stability, further inhibits the destruction of hydrogen fluoride in the electrolyte 140 to the SEI film, thereby making the battery 16 have better cycle stability. The first additive of Example 19 includes a dimethyl group, which can inhibit the dissociation of hydrogen on the nitrogen atom, prevent the increase of the content of hydrogen fluoride in the electrolyte 140, while also maintaining the structural stability of the first additive, and further improve the cycle performance of the battery 19.

[0105] Referring to the data of Examples 21 to 24, the mass fraction b of the second additive of Examples 21 to 24 satisfies the range 0.1%≤b≤1%, and the range of a / b also satisfies the range 0.1≤a / b≤5. With the increase of the mass fraction of the second additive, the cycle performance of the battery 100 corresponding to the second additive first increases and then decreases, because: when the value of b is in a reasonable range, and a / b is in a reasonable range, the second additive can combine with the intermediate product formed by the reduction reaction of the first additive to form an SEI film which has both organic structures such as -C(O)-NR-, -PR(=O)-NR-, etc., and inorganic structures such as lithium phosphate, thereby enhancing the thermal stability of the SEI, and improving the cycle performance of the battery 100 in a high-temperature environment, so the cycle capacity retention rates of the implementation battery 22 and the implementation battery 23 are higher. When the value of b is too small, the proportion of -P=O- structure in the electrolyte 140 is small, and when the first additive and the second additive are used together, the SEI film formed by the first additive and the second additive has less lithium phosphate formed by the combination of -P=O- structure and lithium ion, in other words, the inorganic component in the SEI film is less, thereby making the thermal stability of the SEI film poor, reducing the cycle performance of the battery 100 in a high-temperature environment, so the cycle capacity retention rate of the implementation battery 21 is too low. When the value of b is too large, the SEI film formed by the second additive is too thick, which increases the impedance of lithium ion in the electrolyte 140 passing through the SEI film, affects the kinetic performance of the battery 100, causes lithium precipitation in the battery 100 during the charge and discharge cycle, consumes too much active lithium ion, and reduces the cycle performance of the battery 100. In addition, the second additive may also consume too much lithium ion to form lithium phosphate, thereby reducing the amount of active lithium ion in the electrolyte 140, so the cycle capacity retention rate of the implementation battery 24 is too low.

[0106] Referring to the data of Examples 3, 25 to 27, under the condition that other conditions are the same, the type of the second additive of the electrolyte 140 can affect the cycle performance of the battery 100. The structural formula of the second additive of Example 3 is The structural formula of the second additive of Example 25 is The structural formula of the second additive of Example 26 is The structural formula of the second additive of Example 27 is Among them, the capacity retention of the implementation battery 27 is the highest when cycled at 1P for 1000 times at 45℃, because: the second additive of example 27 contains more fluorine atoms, so that there are more LiF in the SEI film formed by the first additive and the second additive, so that the SEI film has higher thermal stability, so that the implementation battery 27 has better cycle performance in high temperature environment. In addition, the second additives of example 3, example 25 and example 27 all include siloxyl, which can react with hydrogen fluoride in the electrolyte to generate phosphorus-containing organic matter, and then participate in the construction of the SEI film, so that the content of lithium phosphate in the generated SEI film is higher, which is beneficial to improve the thermal stability of the SEI film, further improve the thermal stability of the electrolyte 140, and inhibit the decomposition of the electrolyte 140, so that the corresponding battery 100 has higher stability.

[0107] Please refer to the data of Examples 28 to 31, Comparative Example 5 and Comparative Example 6, when the sum of the mass fraction of the first additive and the mass fraction of the second additive is constant, by adjusting the value of the mass fraction a of the first additive and the value of the mass fraction b of the second additive, the value of a / b can be adjusted, the value of a / b in the electrolyte 140 of Examples 28 to 31 satisfies the range 0.1≤a / b≤5, while the value of a / b in the electrolyte 140 of Comparative Example 5 is too small, and the value of a / b in the electrolyte 140 of Comparative Example 7 is too large, so that the capacity retention rate of Examples 28 to 31 at 45°C with 1P for 1000 cycles is higher than that of Comparative Examples 5 and 6 at 45°C with 1P for 1000 cycles, and as the value of a / b gradually increases, the cycle performance of the corresponding battery 100 first increases and then decreases, because: when the value of a / b is in a reasonable range, the first additive and the second additive have a good synergistic effect, so that the SEI film formed by the first additive and the second additive under high temperature environment has good stability, thereby making the electrolyte 140 have good stability. When the value of a / b is too large or too large, it may cause the SEI film formed by the first additive and the second additive to be too thick and increase the internal resistance of the battery 100, thereby reducing the cycle performance of the battery 100; it may also cause the content of inorganic components such as lithium phosphate in the formed SEI film to be too low, thereby causing the thermal stability of the SEI film to decrease, the capacity retention rate of the battery 100 under high temperature environment to decrease, and the high temperature cycle performance of the battery 100 to be poor. When the value of a / b is too small or too small, the first additive can preferentially form a SEI film on the surface of the negative electrode plate 130, but the SEI film formed by the first additive is difficult to completely cover the surface of the negative electrode plate 130, and the solvent in the electrolyte 140 is easy to directly contact with the negative electrode plate 130 and react to consume lithium ions in the electrolyte 140, and this process is irreversible, which reduces the cycle performance of the battery 100. In addition, the first additive generates less intermediate product in the reduction process, which is difficult to effectively combine with the second additive, so that the second additive is difficult to form lithium phosphate, which also causes the content of inorganic components such as lithium phosphate in the formed SEI film to be too low, thereby causing the thermal stability of the SEI film to decrease, the capacity retention rate of the battery 100 under high temperature environment to decrease, and the high temperature cycle performance of the battery 100 to be poor.

[0108] Please refer to Figure 2 and Figure 3 The application also provides a power utilization device 200, which comprises a device body 210 and the battery 100 provided by the application, and the battery 100 supplies power to the device body 210.

[0109] It can be understood that the battery 100 is electrically connected with the device body 210.

[0110] In the embodiment, the electrolyte 140 of the battery 100 comprises a first additive and a second additive, the first additive is a hydantoin additive, and the second additive is a phosphate additive. The first additive and the second additive have a synergistic effect, so that the SEI film formed by the first additive and the second additive on the surface of the negative electrode plate 130 has good chemical stability and thermal stability, can slow down the side reaction between other components in the electrolyte 140 and the negative electrode plate 130 to consume lithium ions in the electrolyte 140, can also reduce the lithium ions consumed due to the repair of the broken SEI film, and can reduce the life attenuation amplitude of the battery 100, so that the battery 100 has good cycle performance in a high-temperature environment, and the battery 100 has a long service life. When the battery 100 is applied to the power consumption device 200, the battery 100 can provide stable electric energy for the device body 210, which is beneficial to improve the user experience.

[0111] Optionally, the power consumption device 200 of the embodiment of the application can be, but is not limited to, a mobile phone, a tablet computer, a notebook computer, a desktop computer, a smart bracelet, a smart watch, an electronic reader, a game console, and the like. It can also be a vehicle such as a car, a truck, a car, a truck, a motor car, a high-speed train, an electric automatic car, and the like. In addition, it can also be various household appliances and the like. The application Figure 2 The power consumption device 200 of the embodiment is an energy storage battery cabinet.

[0112] It can be understood that the power consumption device 200 described in the embodiment is only one form of the power consumption device 200 to which the battery 100 is applied, and should not be understood as a limitation on the power consumption device 200 provided by the application, nor should it be understood as a limitation on the power consumption device 200 provided by each embodiment of the application.

[0113] In the present application, the phrase "embodiment" or "embodiment" means that the specific features, structures or characteristics described in conjunction with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in the specification does not necessarily mean the same embodiment, nor is it an independent or alternative embodiment that is not mutually exclusive with other embodiments. The skilled person in the art explicitly and implicitly understands that the embodiments described in the application can be combined with other embodiments. In addition, it should also be understood that the features, structures or characteristics described in the embodiments of the application can be combined with each other without contradiction, to form another embodiment that does not depart from the spirit and scope of the technical solution of the application.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. An electrolyte, characterized in that, The electrolyte includes a first additive and a second additive, wherein the first additive is a hydantoin additive and the second additive is a phosphate ester additive; the structural formula of the first additive is: Wherein, R1 is selected from at least one of hydrogen, halogen, methyl, trifluoromethyl, phenyl, cyano, and nitro; R2 is selected from at least one of hydrogen, halogen, methyl, trifluoromethyl, phenyl, cyano, and nitro; and R3 is selected from at least one of hydrogen, halogen, methyl, trifluoromethyl, phenyl, cyano, nitro, and vinyl; the structural formula of the second additive is: Among them, R4, R5 and R6 are all selected from siloxy groups; If the mass fraction of the first additive is a and the mass fraction of the second additive is b, then the electrolyte satisfies the following relationship: 0.1 ≤ a / b ≤ 5; the range of the mass fraction a of the first additive is: 0.05% ≤ a ≤ 3%; and the range of the mass fraction b of the second additive is: 0.1% ≤ b ≤ 1%.

2. The electrolyte according to claim 1, characterized in that, The first additive is selected from , , , , and At least one of them.

3. The electrolyte according to claim 1, characterized in that, The second additive is selected from , , and At least one of the following, wherein TMS is a trimethylsilyl group and i-Pr is isopropyl.

4. A battery, characterized in that, The battery includes: Positive electrode sheet; Diaphragm; Negative electrode sheet; and The electrolyte according to any one of claims 1 to 3, wherein the electrolyte is used to wet the positive electrode, the separator and the negative electrode.

5. An electrical appliance, characterized in that, The electrical equipment includes: The equipment itself; and The battery of claim 4, wherein the battery supplies power to the device body.

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