Electrolyte additive, electrolyte and battery

Abstract

Disclosed in the invention are an electrolyte additive, an electrolyte and a battery. The electrolyte additive comprises a compound represented by formula 1 and an electrophilic film-forming additive, wherein R 1 and R 2 in the compound represented by formula 1 are independently a fluorine atom or fluoroalkyl with 1-10 carbon atoms.

Description

Electrolyte additives, electrolytes and batteries

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 30, 2023, with application number 202311621860.2 and application name “Electrolyte Additives, Electrolytes and Batteries”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention belongs to the field of batteries, and in particular relates to an electrolyte additive, an electrolyte and a battery. Background Art

[0003] Lithium-ion batteries, with their high voltage, large capacity, lack of memory effect, and long life, are widely used in electronics, electric vehicles, and other fields. While lithium-ion batteries have achieved tremendous success in the high-energy battery sector in recent years, consumers still expect batteries with even higher overall performance, which depends on the research and development of new electrode materials and electrolyte systems.

[0004] However, factors such as the dissolution of positive electrode metal ions, the occurrence of electrolyte side reactions, and degradation at the electrode-electrolyte interface make it difficult to improve the overall performance of lithium-ion batteries. Especially under high temperature conditions, the decomposition of lithium hexafluorophosphate, a common lithium salt in the electrolyte, is intensified. Its decomposition product, phosphorus pentafluoride (PF5), is a Lewis acid that catalyzes the decomposition of carbonate-based solvents in the electrolyte to form gases such as ethylene, carbon dioxide, and carbon monoxide, leading to battery gassing. Furthermore, HF, another decomposition product of lithium hexafluorophosphate, corrodes the positive electrode material, exacerbating the dissolution of transition ions. Transition metal ions can also catalyze the decomposition of carbonate-based solvents, further exacerbating gassing.

[0005] To address the high-temperature gassing issue in lithium-ion batteries, film-forming additives are typically used to regulate the formation of a stable SEI film at the electrode-electrolyte interface. However, the SEI films formed by current film-forming additives are relatively thick or have poor ion conductivity, resulting in high impedance in lithium-ion batteries and poor cycling and low-temperature performance. Therefore, it is crucial to provide an electrolyte additive with superior performance to enhance the overall performance of lithium-ion batteries.

[0006] Summary of the Invention

[0007] The present invention aims to at least partially address one of the technical problems in the related art. To this end, one object of the present invention is to provide an electrolyte additive, an electrolyte, and a battery. Adding this electrolyte additive to a lithium-ion battery can not only improve the battery's low-temperature discharge performance, but also enhance its high-temperature storage performance and high-temperature cycling performance.

[0008] One aspect of the present invention provides an electrolyte additive, comprising a compound represented by Formula 1 and an electrophilic film-forming additive.

[0009] Wherein, in the compound represented by formula 1, R1 and R2 are independently a fluorine atom or a fluoroalkyl group having 1 to 10 carbon atoms.

[0010] The electrolyte additive of the present invention comprises a compound represented by Formula 1 and an electrophilic film-forming additive. When the electrolyte additive is added to a lithium ion battery, the compound represented by Formula 1 decomposes into product A during the formation and circulation process. and product B The addition of an electrophilic film-forming additive can, on the one hand, utilize its electrophilicity to weaken the activity of the lone electron on the N atom in the product A of the reduction decomposition of the compound shown in Formula 1 after being attacked by electrons, thereby isolating the product A from attacking the carbonate solvent in the electrolyte, reducing the gas generated by the decomposition of the carbonate solvent, and thus improving the high-temperature storage performance of the battery; on the other hand, the electrophilic film-forming additive can regulate the electrode-electrolyte interface to construct a dense SEI film and CEI film containing N and S elements, and due to the presence of the benzene ring on the compound shown in Formula 1, the stability of the formed SEI film and CEI film can be improved, thereby enhancing the stability and ionic conductivity at the electrode-electrolyte interface, and thus significantly reducing the DC internal resistance of the battery, enhancing the cycle performance and low-temperature discharge performance of the lithium-ion battery. At the same time, the presence of the benzene ring can reduce the energy barrier of the reaction of the compound shown in Formula 1, making it easier for the compound shown in Formula 1 to undergo a reduction reaction during the formation process to quickly form an SEI film and CEI film, thereby reducing the side reactions between the electrode and the electrolyte and improving the cycle performance of the lithium-ion battery. In addition, the dense CEI film can prevent the compound shown in Formula 1 from being attacked by electrons and then decomposed to form decomposition product B. After further reaction, the corrosion of the positive electrode is reduced, the self-discharge phenomenon is reduced, and the cycle performance during high-temperature storage is improved. Therefore, adding this electrolyte additive to lithium-ion batteries can not only improve the battery's low-temperature discharge performance, but also improve the battery's high-temperature storage performance and high-temperature cycle performance.

[0011] In some embodiments, the mass ratio of the compound represented by Formula 1 to the electrophilic film-forming additive is 1:(0.7-5.3). This not only improves the low-temperature discharge performance of the battery, but also improves the high-temperature storage performance and high-temperature cycle performance of the battery.

[0012] In some embodiments, R1 and R2 are independently a fluorine atom, a fluoromethyl group, a fluoroethyl group, a fluoropropyl group, or a fluorobutyl group, thereby improving the cycle performance and low-temperature discharge performance of the battery.

[0013] In some embodiments, the compound represented by Formula 1 includes at least one of the following compounds:

[0014] As a result, not only the low-temperature discharge performance of the battery can be improved, but also the high-temperature storage performance and high-temperature cycle performance of the battery can be improved.

[0015] In some embodiments, the electrophilic film-forming additive includes at least one of a borate compound, a borate ester compound, a phosphite compound, an isocyanate compound, and an acid anhydride compound. This improves not only the low-temperature discharge performance of the battery but also the high-temperature storage performance and high-temperature cycling performance of the battery.

[0016] In some embodiments, the borate compound includes at least one of lithium bis(oxalatoborate), lithium difluorooxalatoborate, and lithium tetrafluoroborate. This improves not only the low-temperature discharge performance of the battery but also the high-temperature storage performance and high-temperature cycling performance of the battery.

[0017] In some embodiments, the borate ester compound includes a compound represented by Formula 2:

[0018] Wherein, R5, R6, and R7 are independently an alkyl group having 1 to 3 carbon atoms, a phenyl group, or a silane group with an unsaturation degree ≤ 2. This not only improves the low-temperature discharge performance of the battery, but also improves the high-temperature storage performance and high-temperature cycle performance of the battery.

[0019] In some embodiments, R5, R6, and R7 are independently methyl, trimethylsilyl, phenyl, or dimethylvinylsilyl. This not only improves the low-temperature discharge performance of the battery, but also improves the high-temperature storage performance and high-temperature cycling performance of the battery.

[0020] In some embodiments, the borate ester compound includes at least one of the following compounds:

[0021] As a result, not only the low-temperature discharge performance of the battery can be improved, but also the high-temperature storage performance and high-temperature cycle performance of the battery can be improved.

[0022] In some embodiments, the phosphite compound includes a compound represented by Formula 3:

[0023] Among them, R8, R9, R 10 Each of the groups is independently an alkyl group having 1 to 3 carbon atoms, a phenyl group, or a silane group with an unsaturation degree of ≤ 2. Thus, not only the low-temperature discharge performance of the battery can be improved, but also the high-temperature storage performance and high-temperature cycle performance of the battery can be improved.

[0024] In some embodiments, R8, R9, R 10 Each of the above groups is independently a trimethylsilyl group or a phenyl group. This not only improves the low-temperature discharge performance of the battery, but also improves the high-temperature storage performance and high-temperature cycle performance of the battery.

[0025] In some embodiments, the phosphite compound includes at least one of the following compounds:

[0026] As a result, not only the low-temperature discharge performance of the battery can be improved, but also the high-temperature storage performance and high-temperature cycle performance of the battery can be improved.

[0027] In some embodiments, the isocyanate compound includes a compound represented by Formula 4:

[0028] Among them, R 11 The alkyl group is an alkyl group, a phenyl group or an alkyl-substituted phenyl group having 1 to 10 carbon atoms. Thus, not only the low-temperature discharge performance of the battery can be improved, but also the high-temperature storage performance and high-temperature cycle performance of the battery can be improved.

[0029] In some embodiments, R 11 The alkyl group is hexyl, phenyl or methylphenyl. Thus, not only the low-temperature discharge performance of the battery can be improved, but also the high-temperature storage performance and high-temperature cycle performance of the battery can be improved.

[0030] In some embodiments, the isocyanate compound includes at least one of the following compounds:

[0031] As a result, not only the low-temperature discharge performance of the battery can be improved, but also the high-temperature storage performance and high-temperature cycle performance of the battery can be improved.

[0032] In some embodiments, the acid anhydride compound includes at least one of the compound represented by Formula 5 and the compound represented by Formula 6:

[0033] Wherein, R3 and R4 are independently a hydrogen atom or an alkyl group with 1 to 3 carbon atoms. Thus, not only the low-temperature discharge performance of the battery can be improved, but also the high-temperature storage performance and high-temperature cycle performance of the battery can be improved.

[0034] In some embodiments, R3 and R4 are independently hydrogen atoms or methyl groups. This not only improves the low-temperature discharge performance of the battery, but also improves the high-temperature storage performance and high-temperature cycle performance of the battery.

[0035] In some embodiments, the acid anhydride compound includes at least one of the following compounds:

[0036] As a result, not only the low-temperature discharge performance of the battery can be improved, but also the high-temperature storage performance and high-temperature cycle performance of the battery can be improved.

[0037] The second aspect of the present invention provides an electrolyte comprising the electrolyte additive described in the first aspect. Thus, when added to a lithium battery, the electrolyte can not only improve the battery's low-temperature discharge performance, but also improve the battery's high-temperature storage performance and high-temperature cycling performance.

[0038] In some embodiments, the mass of the compound represented by Formula 1 accounts for 0.1% to 1.5% based on the total mass of the electrolyte. This not only improves the low-temperature discharge performance of the battery, but also improves the high-temperature storage performance and high-temperature cycle performance of the battery.

[0039] In some embodiments, the electrophilic film-forming additive accounts for 0.1% to 3% by weight of the total mass of the electrolyte, thereby improving not only the low-temperature discharge performance of the battery but also the high-temperature storage performance and high-temperature cycling performance of the battery.

[0040] In some embodiments, the composition further comprises a solvent, wherein the solvent comprises a carbonate solvent.

[0041] The third aspect of the present invention provides a battery comprising the electrolyte according to the second aspect, thereby having excellent low-temperature discharge performance, high-temperature cycle performance, and high-temperature storage performance.

[0042] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. DETAILED DESCRIPTION

[0043] The embodiments of the present invention are described in detail below, which are intended to explain the present invention but are not to be construed as limiting the present invention.

[0044] The technical solution of this application is based on the following discovery: The compound represented by Formula 1 significantly improves the battery's cycling performance and low-temperature discharge performance, but it cannot suppress battery expansion during high-temperature storage and suffers from low capacity retention. The main reasons are as follows: During the battery formation and cycling process, the compound represented by Formula 1 undergoes a reduction and decomposition process after being attacked by electrons, as shown below: The decomposition product A has a strong electron-donating ability, specifically due to the lone electron on its N atom. Decomposition product A can be free in the electrolyte and attack the carbonate solvent in the electrolyte, causing the solvent to decompose and produce carbon dioxide, olefins, carbon monoxide and other gases. When the ambient temperature rises, the process will become more intense, leading to increased gas production in the battery. In addition, decomposition product B is a relatively unstable "transition state" structure, which is easy to decompose again under high temperature conditions to form F - , forming hydrofluoric acid in the electrolyte, which in turn corrodes the positive electrode active material, causing ion dissolution and damage to the structure of the positive electrode active material, which in turn aggravates the self-discharge of the electrode and ultimately leads to a decrease in the cycle performance of the battery during high-temperature storage.

[0045] In view of this, one aspect of the present invention provides an electrolyte additive, comprising a compound represented by Formula 1 and an electrophilic film-forming additive.

[0046] Wherein, in the compound represented by formula 1, R1 and R2 are independently a fluorine atom or a fluoroalkyl group having 1 to 10 carbon atoms.

[0047] The electrolyte additive of the present invention comprises a compound represented by formula 1 and an electrophilic film-forming additive. When the electrolyte additive is added to a lithium ion battery, the compound represented by formula 1 decomposes into product A. and product B The addition of electrophilic film-forming additives, on the one hand, can utilize their electrophilicity to weaken the activity of the lone electron on the N atom in the product A of the reduction decomposition of the compound shown in Formula 1 after being attacked by electrons, thereby isolating it from attacking the carbonate solvent in the electrolyte, reducing the gas generated by the decomposition of the carbonate solvent, and thus improving the high-temperature storage performance of the battery; on the other hand, the electrophilic film-forming additives can regulate the electrode-electrolyte interface to construct a dense SEI film and CEI film containing N and S elements, and due to the presence of the benzene ring on the compound shown in Formula 1, the stability of the formed SEI film and CEI film can be improved, thereby enhancing the stability and ionic conductivity at the electrode-electrolyte interface, and thus significantly reducing the DC internal resistance of the battery, and enhancing the cycle performance and low-temperature discharge performance of the lithium-ion battery. At the same time, the presence of the benzene ring can reduce the energy barrier of the reaction of the compound represented by Formula 1 (specifically, the electron cloud on the N atom of the compound represented by Formula 1 has a conjugated effect with the large π bond of the benzene ring, which disperses the electron cloud density on the N atom, thereby weakening the strength of the NS bond in the compound represented by Formula 1. In addition, the F atom has a strong electronegativity, which makes the electron cloud on the NS bond more inclined to approach the F atom. Theoretical calculation data found that when the compound represented by Formula 1 is attacked by electrons, the energy barrier for the reduction reaction is low (-86.98 Cal / mol), indicating that the compound represented by Formula 1 is very easy to undergo an electroreduction reaction. When attacked by electrons, its NS bond is preferentially broken, that is, during the first charge of the lithium battery, the compound represented by Formula 1 will undergo a reduction decomposition reaction by breaking the NS bond, quickly forming an SEI film and a CEI film). This makes it easier for the compound represented by Formula 1 to undergo a reduction reaction during the formation process to quickly generate an SEI film and a CEI film, thereby reducing the side reactions between the electrode and the electrolyte and improving the cycle performance of the lithium-ion battery. In addition, the dense CEI film can prevent the compound shown in Formula 1 from being attacked by electrons and then decomposed into decomposition products B. After further reaction, the corrosion of the positive electrode is reduced, the self-discharge phenomenon is reduced, and the cycle performance during high-temperature storage is improved. Therefore, adding this electrolyte additive to lithium-ion batteries can not only improve the battery's low-temperature discharge performance, but also improve the battery's high-temperature storage performance and high-temperature cycle performance.

[0048] In some embodiments of the present invention, the mass ratio of the compound shown in Formula 1 to the electrophilic film-forming additive is 1:(0.7-5.3). For example, the mass ratio of the compound shown in Formula 1 to the electrophilic film-forming additive is 1:0.7, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.3, etc., or can be a range composed of any of the above numerical values. Thus, the compound shown in Formula 1 and the electrophilic film-forming additive are compounded according to the above mass ratio, which can effectively utilize the electrophilicity of the electrophilic film-forming additive, block the attack of the decomposition product A of the compound shown in Formula 1 on the carbonate solvent, reduce the gas generated by the decomposition of the carbonate solvent, improve the high temperature storage performance of the battery, and significantly improve the density and stability of the SEI film and the CEI film. The dense CEI film can prevent the decomposition product B of the compound shown in Formula 1 from further reacting to corrode the positive electrode, thereby improving the low temperature discharge performance of the battery and the cycle performance during high temperature storage.

[0049] As an example, the fluoroalkyl group having 1 to 10 carbon atoms includes, but is not limited to, fluoromethyl, fluoroethyl, fluoropropyl, fluorobutyl, fluoropentyl, fluorohexyl, fluoroheptyl, etc. Preferably, in the compound represented by Formula 1, R1 and R2 are each independently a fluoroalkyl group having 1 to 3 carbon atoms.

[0050] In some specific embodiments of the present invention, in the compound represented by Formula 1, R1 and R2 are independently a fluorine atom, a fluoromethyl group, a fluoroethyl group, a fluoropropyl group or a fluorobutyl group.

[0051] As an example, the compound represented by the above formula 1 includes at least one of the following compounds:

[0052] Therefore, the addition of the compound shown in Formula 1 can improve the stability of the formed SEI film and CEI film due to the presence of the benzene ring, thereby enhancing the stability and ionic conductivity at the electrode-electrolyte interface, and thus significantly reducing the DC internal resistance of the battery, and enhancing the cycle performance and low-temperature discharge performance of the lithium-ion battery. At the same time, the presence of the benzene ring can reduce the energy barrier of the reaction of the compound shown in Formula 1, making it easier for the compound shown in Formula 1 to undergo a reduction reaction during the formation process to quickly generate an SEI film and a CEI film, thereby reducing the side reaction between the electrode and the electrolyte and improving the cycle performance of the lithium-ion battery. In addition, the above-mentioned dense CEI film can prevent the decomposition product B of the compound shown in Formula 1 from being attacked by electrons after reduction and decomposition. After further reaction, the corrosion of the positive electrode is reduced, the self-discharge phenomenon is reduced, and the cycle performance during high-temperature storage is improved.

[0053] In some embodiments of the present invention, the electrophilic film-forming additive includes at least one of a borate compound, a borate ester compound, a phosphite compound, an isocyanate compound, and an anhydride compound. The central atom in the borate compound and the borate ester compound is a B atom, which has electrophilicity; the central atom in the phosphite compound is a P atom, which has electrophilicity; both the isocyanate compound and the anhydride compound have unsaturated double bonds, and the double bonds have electrophilicity. The addition of such electrophilic film-forming additives can, on the one hand, utilize their electrophilicity to weaken the product A of the reduction decomposition of the compound shown in Formula 1 after being attacked by electrons. The activity of the lone electron on the N atom in the electrolyte is blocked, thereby preventing it from attacking the carbonate solvent in the electrolyte, reducing the gas generated by the decomposition of the carbonate solvent, and thus improving the high-temperature storage performance of the battery; on the other hand, this type of electrophilic film-forming additive can regulate the electrode-electrolyte interface to construct a dense SEI film and CEI film containing N and S elements. In addition, the dense CEI film can prevent the compound shown in Formula 1 from being attacked by electrons and then reducing and decomposing the product B After further reaction, the corrosion of the positive electrode is reduced, the self-discharge phenomenon is reduced, and the cycle performance during high-temperature storage is improved.

[0054] As an example, the borate compound includes at least one of lithium bis(oxalatoborate), lithium difluorooxalatoborate and lithium tetrafluoroborate.

[0055] In some embodiments of the present invention, the borate ester compound includes a compound represented by Formula 2:

[0056] Wherein, R5, R6, and R7 are each independently an alkyl group having 1 to 3 carbon atoms, a phenyl group, or a silane group having an unsaturation degree ≤ 2.

[0057] In the present application, in the compound represented by Formula 2, the degree of unsaturation in the silyl group = the number of double bonds in the silyl group + the number of triple bonds in the silyl group × 2. Silyl groups include, but are not limited to, trimethylsilyl, dimethylvinylsilyl, and the like.

[0058] Therefore, the borate compound of this composition is used as an electrophilic film-forming additive. On the one hand, its electrophilicity can be used to weaken the product A of the reduction decomposition of the compound shown in Formula 1 after being attacked by electrons. The activity of the lone electron on the N atom in the electrolyte is blocked, thereby preventing it from attacking the carbonate solvent in the electrolyte, reducing the gas generated by the decomposition of the carbonate solvent, and thus improving the high-temperature storage performance of the battery; on the other hand, this type of electrophilic film-forming additive can regulate the electrode-electrolyte interface to construct a dense SEI film and CEI film containing N and S elements. In addition, the dense CEI film can prevent the compound shown in Formula 1 from being attacked by electrons and then reducing and decomposing the product B After further reaction, the corrosion of the positive electrode is reduced, the self-discharge phenomenon is reduced, and the cycle performance during high-temperature storage is improved.

[0059] In some specific embodiments of the present invention, in the above formula 2, R5, R6, and R7 are independently methyl, trimethylsilyl, phenyl, or dimethylvinylsilyl.

[0060] As an example, the borate ester compound includes at least one of the following compounds:

[0061] In some embodiments of the present invention, the phosphite compound includes a compound represented by Formula 3:

[0062] Among them, R8, R9, R 10 Each is independently an alkyl group having 1 to 3 carbon atoms, a phenyl group or a silane group having an unsaturation degree ≤ 2.

[0063] In the present application, in the compound represented by Formula 3, the degree of unsaturation in the silyl group = the number of double bonds in the silyl group + the number of triple bonds in the silyl group × 2. Silyl groups include, but are not limited to, trimethylsilyl, dimethylvinylsilyl, and the like.

[0064] Therefore, the phosphite compound of the composition is used as an electrophilic film-forming additive. On the one hand, its electrophilicity can be used to weaken the product A of the reduction decomposition of the compound shown in Formula 1 after being attacked by electrons. The activity of the lone electron on the N atom in the electrolyte is blocked, thereby preventing it from attacking the carbonate solvent in the electrolyte, reducing the gas generated by the decomposition of the carbonate solvent, and thus improving the high-temperature storage performance of the battery; on the other hand, this type of electrophilic film-forming additive can regulate the electrode-electrolyte interface to construct a dense SEI film and CEI film containing N and S elements. In addition, the dense CEI film can prevent the compound shown in Formula 1 from being attacked by electrons and then reducing and decomposing the product B After further reaction, the corrosion of the positive electrode is reduced, the self-discharge phenomenon is reduced, and the cycle performance during high-temperature storage is improved.

[0065] In some specific embodiments of the present invention, in the above formula 3, R8, R9, R 10 are each independently trimethylsilyl or phenyl.

[0066] As an example, the phosphite compound includes at least one of the following compounds:

[0067] In some embodiments of the present invention, the isocyanate compound includes a compound represented by Formula 4:

[0068] Among them, R11 It is an alkyl group having 1 to 10 carbon atoms, a phenyl group, or a phenyl group substituted with an alkyl group.

[0069] The above-mentioned alkyl group having 1 to 10 carbon atoms includes, but is not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, hexyl, and the like.

[0070] Therefore, the isocyanate compound of this composition is used as an electrophilic film-forming additive. On the one hand, its electrophilicity can be used to weaken the product A of the reduction decomposition of the compound shown in Formula 1 after being attacked by electrons. The activity of the lone electron on the N atom in the electrolyte is blocked, thereby preventing it from attacking the carbonate solvent in the electrolyte, reducing the gas generated by the decomposition of the carbonate solvent, and thus improving the high-temperature storage performance of the battery; on the other hand, this type of electrophilic film-forming additive can regulate the electrode-electrolyte interface to construct a dense SEI film and CEI film containing N and S elements. In addition, the dense CEI film can prevent the compound shown in Formula 1 from being attacked by electrons and then reducing and decomposing the product B After further reaction, the corrosion of the positive electrode is reduced, the self-discharge phenomenon is reduced, and the cycle performance during high-temperature storage is improved.

[0071] In some specific embodiments of the present invention, in the above formula 4, R 11 is hexyl, phenyl or methylphenyl.

[0072] As an example, the isocyanate compound includes at least one of the following compounds:

[0073] In some embodiments of the present invention, the acid anhydride compound includes at least one of the compound represented by Formula 5 and the compound represented by Formula 6:

[0074] Wherein, R3 and R4 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

[0075] Therefore, the use of anhydride compounds as electrophilic film-forming additives can, on the one hand, utilize their electrophilicity to weaken the product A of the reduction decomposition of the compound shown in Formula 1 after being attacked by electrons. The activity of the lone electron on the N atom in the electrolyte is blocked, thereby preventing it from attacking the carbonate solvent in the electrolyte, reducing the gas generated by the decomposition of the carbonate solvent, and thus improving the high-temperature storage performance of the battery; on the other hand, this type of electrophilic film-forming additive can regulate the electrode-electrolyte interface to construct a dense SEI film and CEI film containing N and S elements. In addition, the dense CEI film can prevent the compound shown in Formula 1 from being attacked by electrons and then reducing and decomposing the product B After further reaction, the corrosion of the positive electrode is reduced, the self-discharge phenomenon is reduced, and the cycle performance during high-temperature storage is improved.

[0076] In some embodiments of the present invention, in Formula 5 and Formula 6, R3 and R4 are each independently a hydrogen atom or a methyl group.

[0077] As an example, the acid anhydride compound includes at least one of the following compounds:

[0078] Therefore, adding the electrolyte additive comprising the compound represented by Formula 1 and an electrophilic film-forming additive of the present application to a lithium-ion battery can not only improve the low-temperature discharge performance of the battery, but also improve the high-temperature storage performance and high-temperature cycle performance of the battery.

[0079] The second aspect of the present invention provides an electrolyte comprising the electrolyte additive described in the first aspect. Thus, when added to a lithium battery, the electrolyte can not only improve the battery's low-temperature discharge performance, but also improve the battery's high-temperature storage performance and high-temperature cycling performance.

[0080] In some embodiments of the present invention, based on the total mass of the electrolyte, the mass proportion of the compound represented by formula 1 is 0.1%-1.5%. For example, 0.1%, 0.2%, 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%, etc., or it can be a range composed of any of the above numerical values. Thus, by adding the compound represented by formula 1 in this content to the electrolyte, a stable SEI film and CEI film can be quickly formed at the electrode-electrolyte interface, reducing the DC internal resistance of the battery and the side reaction between the electrode and the electrolyte, thereby improving the cycle performance and low-temperature discharge performance of the lithium-ion battery.

[0081] In some embodiments of the present invention, based on the total mass of the electrolyte, the mass proportion of the electrophilic film-forming additive is 0.1%-3%. For example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, etc., or it can be a range composed of any of the above values. Thus, the electrophilic film-forming additive is added to the electrolyte in such an amount that it synergizes with the compound shown in Formula 1. On the one hand, its electrophilicity can be used to weaken the product A of the reduction decomposition of the compound shown in Formula 1 after being attacked by electrons. The activity of the lone electron on the N atom in the electrolyte is blocked, thereby preventing it from attacking the carbonate solvent in the electrolyte, reducing the gas generated by the decomposition of the carbonate solvent, and thus improving the high-temperature storage performance of the battery; on the other hand, this type of electrophilic film-forming additive can regulate the electrode-electrolyte interface to construct a dense SEI film and CEI film containing N and S elements. In addition, the dense CEI film can prevent the compound shown in Formula 1 from being attacked by electrons and then reducing and decomposing the product B After further reaction, the corrosion of the positive electrode is reduced, the self-discharge phenomenon is reduced, and the cycle performance during high-temperature storage is improved.

[0082] In some embodiments of the present invention, the electrolyte further comprises a solvent, and the solvent comprises a carbonate solvent. As an example, the carbonate solvent includes but is not limited to at least one of dimethyl carbonate, diethyl carbonate, propylene carbonate, ethylene carbonate, and ethyl methyl carbonate.

[0083] In some embodiments of the present invention, the electrolyte may further include an electrolyte salt, and the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0084] In some embodiments of the present application, the electrolyte may also include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.

[0085] It should be noted that the negative electrode film-forming additives, positive electrode film-forming additives and additives that can improve certain battery properties are all types of additives commonly used in this field. Those skilled in the art can choose according to actual needs and will not be repeated here. The characteristics and advantages described for the above-mentioned electrolyte additives are also applicable to the electrolyte and will not be repeated here.

[0086] A third aspect of the present invention provides a battery comprising the electrolyte described in the second aspect.

[0087] Thus, the above electrolyte additive is added to the lithium ion battery, and during the formation and circulation process, the compound shown in formula 1 decomposes into product A and product B The addition of an electrophilic film-forming additive can, on the one hand, utilize its electrophilicity to weaken the activity of the lone electron on the N atom in the product A of the reduction decomposition of the compound represented by Formula 1 after electron attack, thereby isolating it from attacking the carbonate solvent in the electrolyte, reducing the gas generated by the decomposition of the carbonate solvent, and thus improving the high-temperature storage performance of the battery. On the other hand, the electrophilic film-forming additive can regulate the electrode-electrolyte interface to construct a dense SEI film and CEI film containing N and S elements. The presence of the benzene ring on the compound represented by Formula 1 can improve the stability of the formed SEI film and CEI film, thereby enhancing the stability and ionic conductivity at the electrode-electrolyte interface, thereby significantly reducing the DC internal resistance of the battery and enhancing the cycling performance and low-temperature discharge performance of the lithium-ion battery. At the same time, the presence of the benzene ring can reduce the energy barrier of the reaction of the compound represented by Formula 1, making it easier for the compound represented by Formula 1 to undergo a reduction reaction during the formation process to quickly form SEI and CEI films, thereby reducing side reactions between the electrode and the electrolyte and improving the cycling performance of the lithium-ion battery. Furthermore, the dense CEI film prevents the product B, which is formed by the reduction and decomposition of the compound represented by Formula 1 after electron attack, from further reacting and corroding the positive electrode, thereby reducing self-discharge and improving cycling performance during high-temperature storage. Therefore, adding this electrolyte additive to lithium-ion batteries can not only improve the battery's low-temperature discharge performance, but also enhance its high-temperature storage and cycling performance.

[0088] Typically, a battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0089] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector, wherein the positive electrode active material layer includes a positive electrode active material.

[0090] In some embodiments of the present application, the positive electrode current collector may include a metal foil or a composite positive electrode current collector. For example, the metal foil may be aluminum foil. The composite positive electrode current collector may include a polymer material base layer and a metal layer formed on at least one side of the polymer material base layer. For example, the composite negative electrode current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).

[0091] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0092] In some embodiments of the present application, the positive electrode active material layer may further include a positive electrode active material. The positive electrode active material may be a positive electrode active material for batteries known in the art.

[0093] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O2) or at least one of its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, or a composite material of lithium iron manganese phosphate and carbon.

[0094] In some embodiments of the present application, the positive electrode active material layer may further optionally include a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0095] In some embodiments of the present application, the positive electrode active material layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0096] In some embodiments of the present application, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, and the binder, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0097] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.

[0098] In some embodiments of the present application, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, etc.) on a polymer substrate (such as a substrate made of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).

[0099] In some embodiments of the present application, the negative electrode active material may be a negative electrode active material for batteries known in the art. For example, the negative electrode active material may include at least one of the following materials: graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may include at least one of elemental silicon, silicon oxides, silicon-carbon complexes, silicon-nitrogen complexes, and silicon alloys. The tin-based material may include at least one of elemental tin, tin oxides, and tin alloys.

[0100] In some embodiments of the present application, the negative electrode active material layer may further optionally include a binder. The binder may include at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0101] In some embodiments of the present application, the negative electrode active material layer may further include a conductive agent, which may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0102] In some embodiments of the present application, the negative electrode active material layer may optionally further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0103] In some embodiments of the present application, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0104] The present application has no particular limitation on the type of isolation membrane, and any known isolation membrane with a porous structure having good chemical stability and mechanical stability can be selected.

[0105] In some embodiments of the present application, the material of the isolation membrane may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, or polyvinylidene fluoride.

[0106] It should be noted that the features and advantages described above for the electrolyte are also applicable to the battery and will not be repeated here.

[0107] The following embodiments of the present invention are described in detail. It should be noted that the following embodiments are illustrative and are intended only to explain the present invention and are not to be construed as limiting the present invention. In addition, unless otherwise expressly stated, all reagents used in the following embodiments are commercially available or can be synthesized according to methods described herein or known methods. Reaction conditions not listed are also readily available to those skilled in the art.

[0108] Example 1

[0109] 1. Preparation of positive electrode sheet

[0110] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1O2, conductive carbon black, and binder polyvinylidene fluoride (PVDF) are added to N-methylpyrrolidone (NMP) in a mass ratio of 96.8:2:1.2 to prepare a positive electrode slurry (the solid content in the positive electrode slurry is 68wt%). The positive electrode slurry is coated on the upper and lower surfaces of the aluminum foil and dried and then cold pressed. The positive electrode sheets are then made after trimming, cutting, and striping.

[0111] 2. Preparation of negative electrode sheet

[0112] Graphite, conductive carbon black, thickener carboxymethyl cellulose (CMC), and adhesive styrene-butadiene rubber (SBR) are mixed in deionized water at a mass ratio of 95:1.5:2:1.5 to prepare a negative electrode slurry (the solid content in the negative electrode slurry is 49wt%). The negative electrode slurry is coated on the upper and lower surfaces of copper foil and dried. It is then cold pressed, trimmed, cut into pieces, and slit into strips to make negative electrode sheets.

[0113] 3. Preparation of electrolyte

[0114] In an argon-filled glove box, an electrolyte additive comprising the compound shown in Formula 1 and an electrophilic film-forming additive is added to an organic solvent. After mixing evenly, LiPF6 is slowly added. After the lithium salt is completely dissolved, an electrolyte with a lithium salt concentration of 1 mol / L is obtained.

[0115] 4. Isolation film

[0116] A 16 μm polyethylene film was used as the separator.

[0117] 5. Lithium-ion battery preparation

[0118] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive and negative electrode sheets to isolate the positive and negative electrodes. The bare battery cell is wound and the tabs are welded. The bare battery cell is placed in an outer package, and the prepared electrolyte is injected into the dried battery cell. The battery cell is packaged, allowed to stand, formed, and shaped to complete the preparation of the lithium-ion battery.

[0119] The preparation methods of the lithium ion batteries of Examples 1-27 and Comparative Examples 1-6 are the same as those of Example 1, except that the composition and content of the electrolyte additives are different, as shown in Table 1.

[0120] Table 1

[0121] The room temperature cycle performance, high temperature cycle performance, high temperature storage performance and low temperature discharge performance of the lithium ion batteries obtained in Examples 1-29 and Comparative Examples 1-6 were characterized. The characterization results are shown in Table 2.

[0122] (1) Normal temperature cycle performance test method:

[0123] Charge the battery at 1.0C constant current to 4.4V at 25℃, then charge it at constant voltage to a cutoff current of 0.05C, and then discharge it at 1.0C constant current. The discharge capacity is recorded as C0. Repeat the charge and discharge until the capacity decays to 80% of C0, and record the number of cycles.

[0124] (2) High temperature cycle performance test method:

[0125] Charge the battery at 45°C at a constant current of 1.0C to 4.4V, then charge it at a constant voltage to a cutoff current of 0.05C, and then discharge it at a constant current of 1.0C. The discharge capacity is recorded as C0. Repeat the charge and discharge until the capacity decays to 80% of C0, and record the number of cycles.

[0126] (3) High temperature storage performance test method:

[0127] At 25°C, charge the battery at a constant current of 1.0C to 4.4V, charge it at a constant voltage of 4.4V to a cutoff current of 0.05C, then discharge it at a constant current of 0.5C, and record the discharge capacity as C1. Remove the battery and use a thickness tester to measure its initial thickness, which is T1. At 25°C, charge it at a constant current of 1.0C to 4.4V, charge it at a constant voltage of 4.4V to a cutoff current of 0.05C, then transfer the battery to 60°C and let it sit for 15 days. Use a thickness tester to measure its thickness after 15 days, which is T2. Then discharge the battery at a constant current of 1.0C, and record the discharge capacity as C2. After 15 days of storage at 60°C, the capacity retention rate = C2 / C1*100%, and the battery expansion rate = 100%*(T2-T1) / T1.

[0128] (4) Low temperature discharge performance test method:

[0129] At 25°C, charge the battery at a constant current of 1.0C to 4.4V, charge it at a constant voltage of 4.4V to a cutoff current of 0.05C, and then discharge it at a constant current of 0.5C. The discharge capacity is recorded as C4. At -20°C, let it sit for 4 hours, then discharge it at a constant current of 0.5C. The discharge capacity is recorded as C5. The -20°C low-temperature discharge capacity retention rate = C5 / C4*100%.

[0130] Table 2

[0131] Conclusion: It can be seen from the data in Table 2 that compared with Comparative Examples 1-6, the high-temperature storage capacity retention rate of the battery of Example 1-29 is significantly higher than that of the battery of Comparative Example 1-6, and the high-temperature storage battery expansion rate of the battery of Example 1-29 is significantly lower than that of the battery of Comparative Example 1-6. In addition, the room temperature cycle performance, high temperature cycle performance and low-temperature discharge capacity retention rate of the battery of Example 1-29 are also significantly better than those of the battery of Comparative Example 1-6, indicating that adding the electrolyte additive of the present application to the battery not only makes the battery have excellent cycle performance (low-temperature cycle performance and high-temperature cycle performance) and low-temperature discharge performance, but also significantly improves the high-temperature storage performance of the battery.

[0132] Compared to Comparative Example 2, Examples 1-13 add an electrophilic film-forming agent to the electrolyte of Comparative Example 2. The room temperature cycle performance, high temperature cycle performance, high temperature storage capacity retention rate, high temperature storage battery expansion rate, and low temperature discharge capacity retention rate of Examples 1-13 all have obvious advantages over Comparative Example 2. In particular, the high temperature storage battery expansion rate is significantly lower than the high temperature storage battery expansion rate of the battery of Comparative Example 2, and the high temperature storage capacity retention rate is significantly higher than the high temperature storage capacity retention rate of the battery of Comparative Example 2. This indicates that the compound represented by Formula 1 and the electrophilic film-forming agent are added to the electrolyte of the present application, and the two work synergistically to improve the cycle performance and low temperature discharge performance of the battery. At the same time, the addition of the electrophilic film-forming agent significantly improves the high temperature storage performance of the battery.

[0133] Compared to Example 6, Comparative Examples 5 and 6 respectively use fluorosulfonyl imide substances without a benzene ring. Although electrophilic film-forming agents are also added to the electrolytes of Comparative Examples 5 and 6, the cycle performance, high temperature storage performance, and low temperature discharge performance of the batteries of Comparative Examples 5 and 6 are significantly lower than the battery performance of Example 6, indicating that the use of existing conventional fluorosulfonyl imide substances cannot synergize with electrophilic film-forming agents, or the electrophilic film-forming agent is added to the electrolyte alone (Comparative Example 4), and the effect of improving the cycle performance, high temperature storage performance, and low temperature discharge performance of the battery is not significant. In summary, it is explained that due to the presence of a benzene ring in the compound represented by Formula 1 of the present application, it can synergize with the electrophilic film-forming agent, thereby significantly improving the overall performance of the battery.

[0134] In the description of this specification, the reference terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are mutually inconsistent.

[0135] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An electrolyte additive, wherein: It comprises a compound represented by formula 1 and an electrophilic film-forming additive, Wherein, in the compound represented by formula 1, R1 and R2 are independently fluorine atoms or fluoroalkyl groups having 1 to 10 carbon atoms.

2. The electrolyte additive according to claim 1, wherein The mass ratio of the compound represented by Formula 1 to the electrophilic film-forming additive is 1:(0.7-5.3).

3. The electrolyte additive according to claim 1, wherein R1 and R2 are each independently a fluorine atom, a fluoromethyl group, a fluoroethyl group, a fluoropropyl group or a fluorobutyl group.

4. The electrolyte additive according to claim 3, wherein The compound represented by Formula 1 includes at least one of the following compounds:

5. The electrolyte additive according to any one of claims 1 to 4, wherein The electrophilic film-forming additive includes at least one of borate compounds, borate ester compounds, phosphite compounds, isocyanate compounds and acid anhydride compounds.

6. The electrolyte additive according to claim 5, wherein The borate compound includes at least one of lithium bis(oxalatoborate), lithium difluorooxalatoborate and lithium tetrafluoroborate.

7. The electrolyte additive according to claim 5, wherein The borate ester compound includes a compound shown in Formula 2: Wherein, R5, R6, and R7 are independently an alkyl group having 1 to 3 carbon atoms, a phenyl group, or a silane group having an unsaturation degree ≤2.

8. The electrolyte additive according to claim 7, wherein R5, R6, and R7 are each independently methyl, trimethylsilyl, phenyl, or dimethylvinylsilyl.

9. The electrolyte additive according to claim 8, wherein The borate ester compound includes at least one of the following compounds:

10. The electrolyte additive according to claim 5, wherein The phosphite compound includes a compound shown in Formula 3: Among them, R8, R9, R 10 Each is independently an alkyl group having 1 to 3 carbon atoms, a phenyl group or a silane group having an unsaturation degree of ≤2.

11. The electrolyte additive according to claim 10, wherein R8, R9, R 10 are each independently trimethylsilyl or phenyl.

12. The electrolyte additive according to claim 11, wherein The phosphite compound includes at least one of the following compounds:

13. The electrolyte additive according to claim 5, wherein The isocyanate compound includes a compound shown in Formula 4: Among them, R 11 It is an alkyl group having 1 to 10 carbon atoms, a phenyl group, or a phenyl group substituted with an alkyl group.

14. The electrolyte additive according to claim 13, wherein R 11 It is hexyl, phenyl or methylphenyl.

15. The electrolyte additive according to claim 14, wherein The isocyanate compound includes at least one of the following compounds:

16. The electrolyte additive according to claim 5, wherein The acid anhydride compound includes at least one of the compound shown in Formula 5 and the compound shown in Formula 6: Wherein, R3 and R4 are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

17. The electrolyte additive according to claim 16, wherein R3 and R4 are each independently a hydrogen atom or a methyl group.

18. The electrolyte additive according to claim 17, wherein The acid anhydride compound includes at least one of the following compounds:

19. An electrolyte, wherein The electrolyte additive comprises the electrolyte additive described in any one of claims 1 to 18.

20. The electrolyte according to claim 19, wherein Based on the total mass of the electrolyte, the mass proportion of the compound represented by Formula 1 is 0.1%-1.5%.

21. The electrolyte according to claim 19, wherein Based on the total mass of the electrolyte, the mass proportion of the electrophilic film-forming additive is 0.1%-3%.

22. The electrolyte according to any one of claims 19 to 21, wherein: The electrolyte further includes a solvent, and the solvent includes a carbonate solvent.

23. A battery, wherein: Comprising the electrolyte described in any one of claims 19-22.

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