Electrolyte additive, electrolyte, battery and electrical device

Abstract

Electrolyte additive comprising a compound represented by formula 1 and a protective agent, wherein the protective agent comprises a chain compound with a degree of unsaturation greater than or equal to 3 and is able to undergo an addition reaction with a free radical containing a sulfone ester group, formed after a ring-opening reaction of the compound represented by formula 1.

Description

[0001] This application claims priority over Chinese patent application No. 202311341961.4, filed with the Chinese National Intellectual Property Administration on October 16, 2023, entitled “ELECTROLYTE ADDITIVE, ELECTROLYTE, BATTERY, AND ELECTRICAL DEVICE”, the entire contents of which are incorporated herein by reference. TECHNICAL AREA

[0002] The present disclosure relates to the field of batteries and in particular to an electrolyte additive, an electrolyte, a battery and an electrical device. BACKGROUND

[0003] Commercial electrolytes are currently typically produced by dissolving a lithium salt in a linear / cyclic carbonate solvent. Commonly used solvents include ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). These carbonate solvents not only determine the physical properties of the electrolyte but also contribute to the formation of a solid-electrolyte interphase film (SEI film) at the interface between the negative electrode and the electrolyte, ensuring the battery's cycle stability. However, the SEI film formed by solvent decomposition exhibits poor thermal stability, resulting in increased electrolyte side reactions under high-temperature conditions, which can lead to gas generation and other problems.Consequently, lithium-ion batteries are frequently affected by negative effects such as swelling and rapid capacity reduction under high-temperature conditions. In cases where the SEI film formed by the carbonate solvents has only limited capacity to protect the interface between the negative electrode and electrolyte, cyclic sulfonate additives are attracting considerable attention in the fields of electronic products and traction batteries. This is because such cyclic sulfonate additives can form a stable SEI film enriched with lithium alkylsulfonates and inorganic sulfides, which can prevent battery gas generation under high-temperature conditions.

[0004] Regarding the improvement of lithium battery performance, 1,3-propanesultone (PS) is a representative sulfonate additive that demonstrates excellent performance in terms of improving high-temperature cycle performance and battery performance after high-temperature storage. However, PS is regulated under the European Union's REACH Regulation, which limits its addition to a maximum of 0.8% of the total mass of the electrolyte. To meet operational requirements, however, an electrolyte generally needs to be added at a concentration of ≥1%. Consequently, it is necessary to provide an electrolyte additive capable of simultaneously improving both high-temperature cycle performance and battery performance after high-temperature storage. SUMMARY

[0005] The present disclosure aims to solve at least one of the technical problems existing in the prior art to some extent. To this end, one problem of the present disclosure is to provide an electrolyte additive, an electrolyte, a battery, and an electrical device. By adding the electrolyte additive to a lithium-ion battery, the high-temperature cycle performance and the battery's performance after high-temperature storage can be improved.

[0006] A first aspect of the present disclosure provides an electrolyte additive comprising a compound represented by formula 1 and a protective agent, wherein the protective agent comprises a chain compound having a degree of unsaturation greater than or equal to 3 and is capable of undergoing an addition reaction with a free radical containing a sulfone ester group, formed after a ring-opening reaction of the compound represented by formula 1.

[0007] The electrolyte additive of the present disclosure comprises the compound represented by Formula 1 and the protective agent. Upon addition of the electrolyte additive to the lithium-ion battery, the compound represented by Formula 1 undergoes a ring-opening reaction during the formation and cyclization processes to generate the free radical containing the sulfone ester group. The protective agent of the present disclosure comprises a chain compound with a degree of unsaturation greater than or equal to 3, which exhibits high activity and is capable of preferably undergoing an addition reaction with the free radical containing the sulfone ester group that was formed by the compound represented by Formula 1 above the cyclic solvent in the electrolyte.As a result, the catalytic decomposition of the cyclic solvent by the sulfone ester-containing free radical is reduced, thus preventing the generation of gases such as ethylene, carbon dioxide, and carbon monoxide due to the decomposition of the cyclic solvent at high temperatures. This reduces battery swelling and improves battery performance after high-temperature storage. After the compound represented by Formula 1 has undergone the ring-opening reaction and the resulting sulfone ester-containing free radical undergoes the addition reaction with the protective agent, a compact SEI film, enriched with the element sulfur, is formed on the surface of the negative electrode. In this way, the conductivity of the SEI film and the energy performance of the battery can be improved.Furthermore, the SEI film exhibits high strength, which reduces tearing and reconstruction of the SEI film during high-temperature battery cycling, decreases active lithium consumption, and improves the battery's high-temperature cycle performance. Consequently, adding the electrolyte additive to the lithium-ion battery can improve both its high-temperature cycle performance and its performance after high-temperature storage.

[0008] In some embodiments, the electrolyte additive includes a chain compound with an unsaturation level ranging from 3 to 8. Consequently, the energy output, high-temperature cycle performance, and battery performance after high-temperature storage can be improved.

[0009] In some embodiments, the mass ratio of the compound represented by formula 1 to the protective agent is 0.7:1 to 11:1. Consequently, the energy output, high-temperature cycle performance, and battery performance after high-temperature storage can be improved.

[0010] In some embodiments, the chain compound with a degree of unsaturation greater than or equal to 3 includes at least one silane compound, a carbonate compound, or a sulfonate compound. Consequently, the energy output, high-temperature cycle performance, and battery performance after high-temperature storage can be improved.

[0011] In some embodiments, the silane compound comprises a compound represented by formula 2, where R1, R2, R3, and R4 are each independently selected from the group consisting of hydrogen, fluorine, alkyl with 1 to 10 carbon atoms, silyl with 1 to 10 carbon atoms, siloxy with 1 to 10 carbon atoms, alkenyl with 2 to 10 carbon atoms, alkynyl with 2 to 10 carbon atoms, alkenylsiloxy with 2 to 10 carbon atoms, and alkynylsiloxy with 2 to 10 carbon atoms. Consequently, the energy output, high-temperature cycle performance, and battery performance after high-temperature storage can be improved.

[0012] In some embodiments, R1, R2, R3, and R4 in formula 2 are each independently selected from the group consisting of methyl, vinyl, ethynyl, ethynyldimethylsiloxy, and trivinylsiloxy. Consequently, the energy performance, high-temperature cycle performance, and battery performance after high-temperature storage can be improved.

[0013] In some embodiments, the silane compound includes at least one of the following compounds: or Consequently, the energy performance, high-temperature cycle performance, and battery performance after high-temperature storage can be improved.

[0014] In some embodiments, the carbonate compound comprises a compound represented by formula 3, where A is alkenyl with 2 to 6 carbon atoms or alkynyl with 2 to 6 carbon atoms; and R5 and R6 are each independently selected from the group consisting of hydrogen, fluorine, alkyl with 1 to 10 carbon atoms, alkenyl with 2 to 10 carbon atoms, alkynyl with 2 to 10 carbon atoms, an alkyl carbonate group with 2 to 10 carbon atoms, an alkyl sulfonate group with 1 to 10 carbon atoms, and fluoroalkyl with 1 to 10 carbon atoms, provided that at least one of R5 and R6 is an alkyl carbonate group with 2 to 10 carbon atoms. Consequently, the energy output, high-temperature cycle performance, and battery performance after high-temperature storage can be improved.

[0015] In some embodiments, R5 and R6 in formula 3 are each an alkyl carbonate group with 1 to 10 carbon atoms, preferably diethyl carbonate groups. Consequently, the energy output, high-temperature cycle performance, and battery performance after high-temperature storage can be improved.

[0016] In some embodiments, the carbonate compound includes at least one of the following compounds: or Consequently, the energy performance, high-temperature cycle performance, and battery performance after high-temperature storage can be improved.

[0017] In some embodiments, the sulfonate compound comprises a compound represented by formula 4, where R7 and R8 are each independently selected from the group consisting of a hydrogen atom, a fluorine atom, alkyl with 1 to 10 carbon atoms, fluoroalkyl with 1 to 10 carbon atoms, alkenyl with 2 to 10 carbon atoms, and alkynyl with 2 to 10 carbon atoms. Consequently, the energy output, high-temperature cycle performance, and battery performance after high-temperature storage can be improved.

[0018] In some embodiments, R7 and R8 in formula 4 are each independently selected from the group consisting of methyl, trifluoromethyl, ethynyl, vinyl, and a fluorine atom. Consequently, the energy performance, high-temperature cycle performance, and battery performance after high-temperature storage can be improved.

[0019] In some embodiments, the sulfonate compound includes at least one of the following compounds: or Consequently, the energy performance, high-temperature cycle performance, and battery performance after high-temperature storage can be improved.

[0020] A second aspect of the present disclosure provides an electrolyte that includes the electrolyte additive as described in the first aspect. Consequently, by adding the electrolyte to the lithium-ion battery, the high-temperature cycle performance and the battery's performance after high-temperature storage can be improved.

[0021] In some embodiments, the mass fraction of the compound represented by Formula 1 ranges from 0.3% to 4%. Consequently, adding the electrolyte to the lithium-ion battery can improve the high-temperature cycle performance and the battery's performance after high-temperature storage.

[0022] In some embodiments, the electrolyte further includes a solvent, and the solvent includes a cyclic solvent.

[0023] In some embodiments, the cyclic solvent includes at least one of butylene carbonate, ethylene carbonate, fluoroethylene carbonate, propylene carbonate or 1,4-butyrolactone.

[0024] In some embodiments, the mass fraction of the cyclic solvent, based on the total mass of the electrolyte, is in the range of 10% to 30%.

[0025] A third aspect of the present disclosure provides a battery that incorporates the electrolyte described in the second aspect. Consequently, the battery exhibits excellent energy performance, high-temperature cycle performance, and performance after high-temperature storage.

[0026] In some embodiments, the battery further includes an active material for the positive electrode. The active material for the positive electrode comprises at least one of LiCoO2, LiMn2O4, Li 1+y Mn 1-x M x O2, LiFe 1-x M x PO4, or Li2Mn 1-x O4, M contains at least one of Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V or Ti, 0≤y≤0.2, and 0≤x<1.

[0027] In some embodiments, the active material of the positive electrode includes at least one of LiCoO2 or Li 1+y Mn ı - x M x O2, and M contains at least two of Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V or Ti.

[0028] A fourth aspect of the present disclosure provides an electrical device that includes the battery as described in the third aspect. Consequently, the electrical device has an excellent lifespan.

[0029] Further aspects and advantages of the present disclosure are partly provided in the following description, or become partly obvious from the following description, or can be learned from the practical implementation of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The foregoing and / or additional aspects and advantages of the present disclosure will become more obvious and better understood from the following description of embodiments when considered together with the accompanying drawings. Fig. Figure 1 shows a theoretically calculated electrostatic potential of 2,4-BS (a compound represented by formula 1). DETAILED DESCRIPTION

[0031] The embodiments of the present disclosure are described in detail below, which is intended to explain the present disclosure and not to limit it.

[0032] The technical solutions of the present disclosure are further developed by the inventor(s) based on the following results. 2,4-BS (a compound represented by formula 1), when added to a battery as a derivative of PS (1,3-propanesultone) during the formation and cycling processes, can also form a film enriched with lithium alkylsulfonates and inorganic sulfides on the surface of the negative electrode. Consequently, 2,4-BS is frequently used as a substitute for PS to address the poor high-temperature performance of lithium-ion batteries. However, when a small amount of 2,4-BS is added, the substance is unable to participate in the SEI film repair process in the later stages of the charge-discharge cycle, thus failing to ensure the stability of the lithium-ion battery in these later stages.An increase in the amount of 2,4-BS can indeed lead to the formation of a large amount of sulfur-enriched SEI film, which improves the stability of the interface between the negative electrode and the electrolyte. However, it has been observed that such an increase in the 2,4-BS content leads to significant gas generation during high-temperature storage of the battery. To investigate this phenomenon, the inventor(s) have conducted in-depth research and theoretical calculations (regarding the electrostatic potential, as described in [reference]). Fig.(1 shown). The results showed that the electron cloud distribution of 2,4-BS is uneven and that the charge of the negative electron cloud is higher. This means that a sulfonate-containing free radical formed after the ring opening of 2,4-BS has a greater tendency to sacrifice electrons. Consequently, this free radical tends to attack the cyclic solvent in an electrolyte, causing its decomposition and the production of gases such as ethylene, carbon dioxide, and carbon monoxide, resulting in gas generation by the battery.

[0033] In light of this, a first aspect of the present disclosure provides an electrolyte additive comprising a compound represented by Formula 1 and a protective agent. The protective agent includes a chain compound with a degree of unsaturation greater than or equal to 3 and is capable of undergoing an addition reaction with a free radical containing a sulfone ester group, formed after a ring-opening reaction of the compound represented by Formula 1.

[0034] The electrolyte additive of the present disclosure comprises the compound represented by Formula 1 and the protective agent. Upon addition of the electrolyte additive to the lithium-ion battery, the compound represented by Formula 1 undergoes a ring-opening reaction during the formation and cyclization processes to generate the free radical containing the sulfone ester group. The protective agent of the present disclosure comprises a chain compound with a degree of unsaturation greater than or equal to 3, which exhibits high activity and is capable of preferably undergoing an addition reaction with the free radical containing the sulfone ester group that was formed by the compound represented by Formula 1 above the cyclic solvent in the electrolyte.As a result, the catalytic decomposition of the cyclic solvent by the sulfone ester-containing free radical is reduced, thus preventing the generation of gases such as ethylene, carbon dioxide, and carbon monoxide due to the decomposition of the cyclic solvent at high temperatures. This reduces battery swelling and improves battery performance after high-temperature storage. After the compound represented by Formula 1 has undergone the ring-opening reaction and the resulting sulfone ester-containing free radical undergoes the addition reaction with the protective agent, a compact SEI film, enriched with the element sulfur, is formed on the surface of the negative electrode. In this way, the conductivity of the SEI film and the energy performance of the battery can be improved.Furthermore, the SEI film exhibits high strength, which reduces tearing and reconstruction of the SEI film during high-temperature battery cycling, decreases the consumption of active lithium, and improves the battery's high-temperature cycle performance. Moreover, the protective agent used in the present disclosure is the chain compound. Compared to a cyclic compound, the chain compound protective agent of the present disclosure exhibits higher activity and is more inclined to undergo the addition reaction with the sulfone ester-containing free radical generated by the ring opening of the compound represented by Formula 1. Consequently, by adding the electrolyte additive to the lithium-ion battery, the high-temperature cycle performance and the battery's performance after high-temperature storage can be improved.

[0035] In the present disclosure, the degree of unsaturation of the protective agent is given by: number of double bonds in the protective agent + number of triple bonds in the protective agent × 2. Since the "protective agent" preferentially reacts with the free radical containing the sulfone ester group, which is generated by the ring-opening reaction of the compound represented by formula 1 above the cyclic solvent, it also protects the cyclic solvent. Accordingly, it is referred to as a "protective agent".

[0036] In some embodiments of the present disclosure, the electrolyte additive comprises a chain compound with a degree of unsaturation ranging from 3 to 8. The degree of unsaturation of the protective agent is, for example, 3, 4, 5, 6, 7, or 8. Consequently, the protective agent of the present disclosure exhibits high activity and is preferably capable of undergoing an addition reaction with the sulfone ester-containing free radical formed by the compound represented by Formula 1 above the cyclic solvent in the electrolyte. As a result, the catalytic decomposition of the cyclic solvent by the sulfone ester-containing free radical is reduced, thereby preventing the generation of gases such as ethylene, carbon dioxide, and carbon monoxide due to the decomposition of the cyclic solvent at high temperatures.This reduces battery swelling and improves battery performance after high-temperature storage. After the compound represented by Formula 1 undergoes the ring-opening reaction and the resulting free radical, containing the sulfone ester group, undergoes the addition reaction with the protective agent, a compact SEI film enriched with element sulfur is formed on the surface of the negative electrode. This improves the conductivity of the SEI film and the energy performance of the battery. Furthermore, the SEI film exhibits high strength, which reduces tearing and reconstruction during high-temperature battery cycling, decreases active lithium consumption, and improves the battery's high-temperature cycle performance.Furthermore, the protective agent with this degree of unsaturation can also mitigate the problem of high battery impedance caused by the participation of too many unsaturated bonds in the formation of the SEI film.

[0037] In some embodiments of the present disclosure, the mass ratio of the compound represented by Formula 1 to the protective agent ranges from 0.7:1 to 11:1, for example 0.7:1, 0.9:1, 1:1, 3:1, 5:1, 7:1, 9:1, 11:1, or can be a range formed from any of the foregoing values. Consequently, by mixing the compound represented by Formula 1 and the protective agent according to the foregoing mass ratio, the protective agent can completely combine with the sulfone ester-containing free radical generated by the ring opening of the compound represented by Formula 1. As a result, the catalytic decomposition of the cyclic solvent by the sulfone ester-containing free radical is reduced, thereby preventing the generation of gases such as ethylene, carbon dioxide, and carbon monoxide due to the decomposition of the cyclic solvent at high temperatures.This reduces battery swelling and improves battery performance after high-temperature storage. After the compound represented by Formula 1 undergoes the ring-opening reaction and the resulting free radical, containing the sulfone ester group, undergoes the addition reaction with the protective agent, a compact SEI film enriched with element sulfur is formed on the surface of the negative electrode. This improves the conductivity of the SEI film and the energy performance of the battery. Furthermore, the SEI film exhibits high strength, which reduces tearing and reconstruction during high-temperature battery cycling, decreases active lithium consumption, and improves the battery's high-temperature cycle performance.

[0038] In some embodiments of the present disclosure, the aforementioned chain compound is selected from the group consisting of a silane compound, a carbonate compound, a sulfonate compound and a combination thereof, having a degree of unsaturation greater than or equal to 3.

[0039] In some embodiments of the present disclosure, the foregoing silane compound comprises a compound represented by formula 2, wherein R1, R2, R3 and R4 are each independently selected from the group consisting of hydrogen, fluorine, alkyl having 1 to 10 carbon atoms, silyl having 1 to 10 carbon atoms, siloxy having 1 to 10 carbon atoms, alkenyl having 2 to 10 carbon atoms, alkynyl having 2 to 10 carbon atoms, alkenylsiloxy having 2 to 10 carbon atoms and alkynylsiloxy having 2 to 10 carbon atoms.

[0040] Consequently, the substance, using the silane compound with a degree of unsaturation greater than or equal to 3 in this composition, is able to preferably undergo an addition reaction with the sulfone ester-containing free radical formed by the compound represented by Formula 1 above the cyclic solvent in the electrolyte. As a result, the catalytic decomposition of the cyclic solvent by the sulfone ester-containing free radical is reduced, thereby preventing the generation of gases such as ethylene, carbon dioxide, and carbon monoxide due to the decomposition of the cyclic solvent at high temperatures. This reduces battery swelling and improves battery performance after high-temperature storage.After the compound represented by Formula 1 has undergone the ring-opening reaction and the resulting free radical containing the sulfone ester group undergoes the addition reaction with the protective agent, a compact SEI film enriched with the element sulfur is formed on the surface of the negative electrode. This improves the conductivity of the SEI film and the energy performance of the battery. Furthermore, the SEI film exhibits high strength, which reduces tearing and reconstruction during high-temperature battery cycling, decreases active lithium consumption, and improves the battery's high-temperature cycle performance. Additionally, the silicon atoms on the SEI film readily react with fluorine. -This reduces the HF concentration in the electrolyte. This suppresses HF erosion of the positive electrode and thus prevents the dissolution of transition metal ions into the electrolyte, which would otherwise catalyze the decomposition of cyclic solvents. Consequently, the SEI film formed in this way increases the stability of the cathode-electrolyte interface and prevents gas generation.

[0041] The preceding alkyl group with 1 to 10 carbon atoms includes, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, and the like, but is not limited to these. The silyl group with 1 to 10 carbon atoms includes, but is not limited to, trimethylsilyl. The siloxy group with 1 to 10 carbon atoms includes, but is not limited to, dimethylsiloxy. The alkenyl group with 2 to 10 carbon atoms includes, but is not limited to, vinyl, propenyl, butadienyl, pentadienyl, and the like. The alkynyl group with 2 to 10 carbon atoms includes, but is not limited to, ethynyl, propynyl, butynyl, and the like. The alkenylsiloxy group with 2 to 10 carbon atoms includes, but is not limited to, ethynyldimethylsiloxy. The alkynylsiloxy group with 2 to 10 carbon atoms includes ethynyldimethylsiloxy and the like, but is not limited to these.

[0042] In some specific embodiments of the foregoing disclosure, in the compound represented by formula 2 as described above, R1, R2, R3 and R4 are each independently selected from the group consisting of methyl, vinyl, ethynyl, ethynyldimethylsiloxy and trivinylsiloxy.

[0043] For example, the silane compound includes at least one of the following compounds: or In some embodiments, the CAS number of the compound represented by formula 2-1 is 1112-55-6; the CAS number of the compound represented by formula 2-1 is 1675-60-1; the CAS number of the compound represented by formula 2-3 is 75144-60-4; the CAS number of the compound represented by formula 2-4 is 4180-02-3; and the CAS number of the compound represented by formula 2-5 is 18244-95-6.

[0044] In some specific embodiments of the present disclosure, the carbonate compound comprises a compound represented by formula 3, wherein A is alkenyl having 2 to 6 carbon atoms or alkynyl having 2 to 6 carbon atoms; and R5 and R6 are each independently selected from the group consisting of hydrogen, fluorine, alkyl having 1 to 10 carbon atoms, alkenyl having 2 to 10 carbon atoms, alkynyl having 2 to 10 carbon atoms, an alkyl carbonate group having 2 to 10 carbon atoms, an alkyl sulfonate group having 1 to 10 carbon atoms, and fluoroalkyl having 1 to 10 carbon atoms, provided that at least one of R5 and R6 is an alkyl carbonate group having 2 to 10 carbon atoms.

[0045] Consequently, the substance, using the carbonate compound with a degree of unsaturation greater than or equal to 3 in this composition, is able to preferably undergo an addition reaction with the sulfone ester-containing free radical formed by the compound represented by Formula 1 above the cyclic solvent in the electrolyte. As a result, the catalytic decomposition of the cyclic solvent by the sulfone ester-containing free radical is reduced, thereby preventing the generation of gases such as ethylene, carbon dioxide, and carbon monoxide due to the decomposition of the cyclic solvent at high temperatures. This reduces battery swelling and improves battery performance after high-temperature storage.After the compound represented by Formula 1 undergoes the ring-opening reaction and the resulting free radical, containing the sulfone ester group, undergoes the addition reaction with the protective agent, a compact SEI film enriched with element sulfur is formed on the surface of the negative electrode. This improves the conductivity of the SEI film and the energy performance of the battery. Furthermore, the SEI film exhibits high strength, which reduces tearing and reconstruction during high-temperature battery cycling, decreases active lithium consumption, and improves the battery's high-temperature cycle performance. Additionally, the carbonate compound in this composition exhibits good compatibility with the electrolyte solvent, thereby reducing electrolyte side reactions and suppressing gas generation within the battery.

[0046] The aforementioned alkyl carbonate group with 2 to 10 carbon atoms includes, for example, methyl carbonate, ethyl carbonate, and the like, but is not limited to these. The alkyl sulfonate group with 1 to 10 carbon atoms includes, for example, methyl sulfonate, ethyl sulfonate, and the like, but is not limited to these. The fluoroalkyl group with 1 to 10 carbon atoms includes, but is not limited to, trifluoromethyl, difluoroethyl, and the like.

[0047] In some specific embodiments of the present disclosure, R5 and R6 in the compound represented by formula 3 each comprise an alkyl carbonate group with 1 to 10 carbon atoms, preferably diethyl carbonate groups.

[0048] For example, the carbonate compound includes at least one of the following compounds: or in some embodiments, the CAS number of formula 3-1 is 197244-14-7, and the CAS number of formula 3-2 is 219839-52-8.

[0049] In some embodiments of the present disclosure, the sulfonate compound comprises a compound represented by formula 4, wherein R7 and R8 are each independently selected from the group consisting of a hydrogen atom, a fluorine atom, alkyl having 1 to 10 carbon atoms, fluoroalkyl having 1 to 10 carbon atoms, alkenyl having 2 to 10 carbon atoms and alkynyl having 2 to 10 carbon atoms.

[0050] Consequently, the substance, using the sulfonate compound with a degree of unsaturation greater than or equal to 3 in this composition, is able to preferably undergo an addition reaction with the free radical containing the sulfonate ester group, which is formed by the compound represented by Formula 1 above the cyclic solvent in the electrolyte. As a result, the catalytic decomposition of the cyclic solvent by the free radical containing the sulfonate ester group is reduced, thereby preventing the generation of gases such as ethylene, carbon dioxide, and carbon monoxide due to the decomposition of the cyclic solvent at high temperatures. This reduces battery swelling and improves battery performance after high-temperature storage.After the compound represented by Formula 1 has undergone the ring-opening reaction and the resulting free radical containing the sulfone ester group undergoes the addition reaction with the protective agent, a compact SEI film enriched with element sulfur is formed on the surface of the negative electrode. This improves the conductivity of the SEI film and the energy performance of the battery. Furthermore, the SEI film exhibits high strength, which reduces tearing and reconstruction during high-temperature battery cycling, decreases active lithium consumption, and improves the battery's high-temperature cycle performance.

[0051] In some specific embodiments of the present disclosure, in formula 4 as described above, R7 and R8 are each independently selected from the group consisting of methyl, trifluoromethyl, ethynyl, vinyl and a fluorine atom.

[0052] For example, the sulfonate compound contains at least one of the following compounds: or

[0053] In some embodiments, the CAS number of formula 4-1 is 16156-58-4; the CAS number of formula 4-2 is 7459-72-5; and the CAS number of formula 4-3 is 41029-46-3.

[0054] A second aspect of the present disclosure provides an electrolyte that includes the electrolyte additive as described in the first aspect. Consequently, by adding this electrolyte to the lithium-ion battery, the high-temperature cycle performance and the battery's performance after high-temperature storage can be improved.

[0055] In some embodiments of the present disclosure, based on a total mass of the electrolyte, a mass fraction of the compound represented by Formula 1 of 0.3% to 4% is sufficient, for example 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or may be a range formed from any of the foregoing values. Consequently, such a content of the compound represented by Formula 1 can, on the one hand, meet the requirement for the SEI film repair process in the later stages of the battery's charge-discharge cycling and thereby improve the battery's stability in the later stages of cycling.On the other hand, the protective agent in the electrolyte additive, due to its presence, is able to preferably undergo an addition reaction with the sulfone ester-containing free radical formed by the compound represented by Formula 1 above the cyclic solvent in the electrolyte. As a result, the catalytic decomposition of the cyclic solvent by the sulfone ester-containing free radical is reduced, thus preventing the generation of gases such as ethylene, carbon dioxide, and carbon monoxide due to the decomposition of the cyclic solvent at high temperatures. This reduces battery swelling and improves battery performance after high-temperature storage. Furthermore, at such a concentration, the compound represented by Formula 1 also participates in the formation of the SEI film, leading to its enrichment with sulfur.In this way, the conductivity of the SEI film and the energy performance of the battery can be improved. Furthermore, the SEI film exhibits high strength, which reduces cracking and reconstruction of the SEI film during high-temperature cycling of the battery, decreases the consumption of active lithium, and improves the high-temperature cycle performance of the battery.

[0056] In some embodiments of the present disclosure, the electrolyte further comprises a solvent, and the solvent comprises a cyclic solvent. For example, the cyclic solvent comprises at least one of butylene carbonate, ethylene carbonate, fluoroethylene carbonate, propylene carbonate, or 1,4-butyrolactone.

[0057] In some embodiments of the present disclosure, based on the total mass of the electrolyte, a mass fraction of cyclic solvent of 10% to 30% is sufficient, for example 10%, 15%, 20%, 25%, 30%, or it may be a range formed from any of the foregoing values. Consequently, at this concentration, the thermal stability of the electrolyte can be improved by adding the cyclic solvent to the electrolyte, and the side reactions of the electrolyte can be reduced.

[0058] In some embodiments of the present disclosure, the electrolyte may include at least one further solvent of diethyl carbonate, dimethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate or ethyl propyl carbonate.

[0059] In some embodiments of the present disclosure, the electrolyte may further comprise an electrolyte salt. The electrolyte salt may comprise at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium difluorosulfonylimide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoroethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, or lithium tetrafluorooxalate phosphate.

[0060] In some embodiments of the present disclosure, the electrolyte may further include an additive forming a film on the negative electrode, an additive forming a film on the positive electrode, and additives capable of improving a certain performance of the battery, for example, an additive to improve the overcharge performance of the battery and an additive to improve the high-temperature or low-temperature performance of the battery.

[0061] It should be noted that the additive forming a film on the negative electrode, the additive forming a film on the positive electrode, and the additives capable of improving a specific battery performance are all types of additives commonly used in practice. A person skilled in the art can select them according to their specific needs; relevant details are omitted here. Furthermore, the properties and advantages described for the aforementioned electrolyte additives are also applicable to this electrolyte, and relevant details are omitted here.

[0062] A third aspect of the present disclosure provides a battery. According to the embodiments of the present disclosure, the battery includes the electrolyte as described in the second aspect.

[0063] Consequently, during the battery formation and cycling processes in the electrolyte, the compound represented by Formula 1 undergoes a ring-opening reaction, generating a free radical containing the sulfone ester group. The protective agent in the electrolyte additive exhibits high activity and is capable of preferably undergoing an addition reaction with the sulfone ester-containing free radical formed by the compound represented by Formula 1 above the cyclic solvent in the electrolyte. As a result, the catalytic decomposition of the cyclic solvent by the sulfone ester-containing free radical is reduced, thus preventing the generation of gases such as ethylene, carbon dioxide, and carbon monoxide due to the decomposition of the cyclic solvent at high temperatures.This reduces battery swelling and improves battery performance after high-temperature storage. After the compound represented by Formula 1 undergoes the ring-opening reaction and the resulting free radical containing the sulfone ester group undergoes the addition reaction with the protective agent, a compact SEI film enriched with element sulfur is formed on the surface of the negative electrode. This improves the conductivity of the SEI film and the energy performance of the battery. Furthermore, the SEI film exhibits high strength, which reduces tearing and reconstruction during high-temperature battery cycling, decreases active lithium consumption, and improves the battery's high-temperature cycle performance. Consequently, the battery of the present disclosure exhibits excellent performance after high-temperature storage and excellent high-temperature cycle performance.

[0064] In some embodiments of the present disclosure, the battery further comprises an active material of the positive electrode. The active material of the positive electrode comprises at least one of LiCoO2, LiMn2O4, Li 1+y Mn ı - x M x O2, LiFe 1-x M x PO4 or Li2Mn 1-x O4. M contains at least one of Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V or Ti, 0≤y≤0.2, and 0≤x<1.

[0065] For example, x can be in Li 1+y Mn ı - x M x O2, LiFe 1-x M x PO4 and Li2Mn 1-x O4 can be 0, 0.1, 0.3, 0.5, 0.7, 0.9, or a range formed from any of the foregoing values, and y can be 0, 0.1, 0.2, or a range formed from any of the foregoing values. For example, Li 1+y Mn 1-x M x O2 LiMnO2, LiMn 0,5 Co 0,3 Ni 0,2 O2, Li 1,2 Mn 0,5 Co0,3 Ni 0,2 It includes, but is not limited to, O2 and similar substances. 1-x M x PO4 can be LiFePO4, LiFe 0,8 Mn 0,2 It includes, but is not limited to, PO4 and similar materials, as well as Li2Mn. 1-x O4 can contain Li2MnO4 and the like, but is not limited to it.

[0066] In some embodiments of the present disclosure, the active material of the positive electrode comprises LiCoO2 or Li 1+y Mn ı - x M x O2, and M contains at least two of Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V or Ti, for example LiNi 0,5 Co 0,3 Mn 0.2 O2, LiNi 0,6 Co 0,2 Mn 0,2 O2, LiNi 0,65 Co 0,25 Mn 0,1 O2, LiNi 0,7 Co 0,2 Mn 0,1 O2, LiNi 0,7 Co 0,2 Al 0,1 O2 and LiNi 0,5 Co 0,3 Al 0,2O2. In some embodiments, when a ternary active material and lithium cobalt oxide are used as the positive electrode active materials for the lithium-ion battery, gas generation, swelling, and a decrease in capacity frequently occur, which becomes even more severe under high-temperature conditions. These phenomena are generally caused by increased side reactions of the electrolyte. Under high-temperature conditions, problems such as the decomposition of the lithium salt, the dissolution of transition metal ions, and the formation of microcracks in the crystal structure of the positive electrode active material further intensify electrolyte side reactions, ultimately leading to significant gas generation and a reduction in capacity.By adding the electrolyte additive comprising the compound shown in Formula 1 and the protective agent to the electrolyte of the present disclosure, a compact and thermally stable cathode-electrolyte interphase film (CEI film) and a similar SEI film can be formed at the electrode-electrolyte interfaces. These films effectively suppress side reactions of the electrolyte occurring at the electrode surfaces and prevent the active materials of the positive electrode from being corroded by byproducts of electrolyte degradation. Consequently, the dissolution of transition metal ions and the formation of microcracks are prevented, further reducing side reactions of the electrolyte.Overall, the electrolyte additive of the present disclosure improves the stability of the positive electrodes composed of ternary active material and lithium cobalt oxide, thereby preventing gas generation and capacity reduction.

[0067] A typical battery contains a positive electrode panel, a negative electrode panel, an electrolyte, and a separator. During charging and discharging, active ions are intercalated and deintercalated between the positive and negative electrode panels. The electrolyte facilitates the flow of active ions between these two panels. The separator, positioned between the positive and negative electrode panels, primarily prevents a short circuit between them while allowing the free flow of ions.

[0068] The positive electrode array includes a current collector of the positive electrode and an active material layer of the positive electrode, formed on at least one side surface of the current collector of the positive electrode. The active material layer of the positive electrode comprises the active material of the positive electrode described above.

[0069] In some embodiments of the present disclosure, the positive electrode current collector can comprise a metal foil or a positive electrode current collector made of composite material. For example, an aluminum foil can be used as the metal foil. The positive electrode current collector made of composite material can comprise a substrate layer of a high-molecular-weight material and a metal layer formed on at least one side of the substrate layer made of high-molecular-weight material. For example, the positive electrode current collector made of composite material can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, and the like) on a high-molecular-weight material substrate (for example, polypropylene (PP), polyethylene glycol terephthalate (PET), and polybutylene terephthalate (PBT)).

[0070] In some embodiments of the present disclosure, the active material layer of the positive electrode may optionally further include a conductive means. For example, the conductive means may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, a carbon dot, a carbon nanotube, graphene, or a carbon nanofiber.

[0071] In some embodiments of the present disclosure, the active material layer of the positive electrode may optionally further comprise a binder. The binder may, for example, comprise 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, or a fluorine-containing acrylate resin.

[0072] In some embodiments of the present disclosure, the positive electrode panel can be produced by: dispersing the aforementioned components for producing the positive electrode panel, for example, the active material of the positive electrode, the conductive agent, and the binder, in a solvent (for example, N-methylpyrrolidone) to form a positive electrode slurry; and applying the positive electrode slurry to a positive electrode current collector, followed by drying, cold pressing, and further processes to obtain the positive electrode panel.

[0073] The negative electrode array includes a negative electrode current collector and a layer of negative electrode active material formed on at least one side of the negative electrode current collector. The negative electrode active material layer comprises a negative electrode active material.

[0074] In some embodiments of the present disclosure, the current collector of the negative electrode can be a metal foil or a current collector made of composite material. For example, a copper foil can be used as the metal foil. The current collector made of composite material can comprise a substrate layer of high-molecular-weight material and a metal layer formed on at least one surface of a substrate made of high-molecular-weight material. For example, the current collector made of composite material can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, and the like) on a substrate of high-molecular-weight material (for example, a substrate of polypropylene (PP), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT)).

[0075] In some embodiments, the active material of the negative electrode can be a negative electrode active material generally known for batteries in the art. For example, the negative electrode active material can comprise at least one of graphite, soft graphite, hard carbon, a silicon-based material, a tin-based material, or lithium titanate. The silicon-based material can comprise at least one of elemental silicon, a silicon-oxygen compound, a silicon-carbon complex, a silicon-nitrogen complex, or a silicon alloy. The tin-based material can comprise at least one of elemental tin, a tin oxide compound, or a tin alloy.

[0076] In some embodiments of the present disclosure, the active material layer of the negative electrode may optionally further comprise a binder. The binder may comprise 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), or carboxymethyl chitosan (CMCS).

[0077] In some embodiments of the present disclosure, the active material layer of the negative electrode may optionally further comprise a conductive means. The conductive means may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, a carbon dot, a carbon nanotube, graphene, or a carbon nanofiber.

[0078] In some embodiments of the present disclosure, the active material layer of the negative electrode may optionally further comprise additional additives such as a thickening agent (for example, sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0079] In some embodiments of the present disclosure, the negative electrode panel can be produced by: dispersing the aforementioned components used to produce the negative electrode panel, for example, the active material of the negative electrode, the conductive agent, the binder, and any further components in a solvent (for example, deionized water) to form a negative electrode slurry; and applying the negative electrode slurry to a negative electrode current collector, followed by drying, cold pressing, and further processes to obtain the negative electrode panel.

[0080] The type of separator is not specifically limited in the present disclosure. Any well-known separator with a porous structure and good chemical and mechanical stability can be chosen.

[0081] In some embodiments of the present disclosure, the separator material may comprise at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene or polyvinylidene fluoride.

[0082] Furthermore, the properties and advantages described above for the electrolyte are also applicable to this battery, and corresponding details are omitted here.

[0083] A fourth aspect of the present disclosure provides an electrical device that includes the battery as described in the third aspect. Consequently, the battery has an excellent lifespan. The electrical device may include, for example, a mobile phone, a laptop computer, a pure electric vehicle, a hybrid electric vehicle, and the like, but is not limited to such devices.

[0084] It is understood that the properties and advantages described above for the battery are also applicable to this electrical device, and corresponding details are omitted here.

[0085] The embodiments of the present disclosure are described in detail below. It is understood that the embodiments described below are purely illustrative and are intended to explain, not limit, the present disclosure. Furthermore, unless explicitly stated otherwise, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods set forth herein or known to the person skilled in the art. Reaction conditions not listed can be readily obtained by a person skilled in the art. Example 11. Production of a positive electrode array

[0086] An active material of the positive electrode, LiNi 0,8 Co 0,1 Mn0,1 O2, a conductive agent (conductive carbon black), and a binder (polyvinylidene fluoride (PVDF)) were mixed in a mass ratio of 96.8:2:1.2 and added to N-methylpyrrolidone (NMP) to form a positive electrode slurry (with a solids content of 68 wt% in the positive electrode slurry). The positive electrode slurry was applied to the top and bottom surfaces of an aluminum foil, dried, and cold-rolled, followed by edge trimming, sheet cutting, and jointing to obtain the positive electrode sheet. 2. Production of a negative electrode array

[0087] Graphite, a conductive agent (conductive carbon black), a thickening agent (carboxymethylcellulose (CMC)), and a binder (styrene-butadiene rubber (SBR)) were mixed in a mass ratio of 95:1.5:2:1.5 and dispersed in deionized water to form a negative electrode slurry (with a solids content of 49 wt% in the negative electrode slurry). The negative electrode slurry was applied to the top and bottom surfaces of a copper foil and dried, followed by cold rolling, edge trimming, sheet cutting, and jointing to obtain the negative electrode sheet. 3. Preparation of an electrolyte

[0088] In an argon-filled glovebox, an electrolyte additive containing a protective agent represented by formula 2-1 and a compound represented by formula 1 was added to an organic solvent. The organic solvent contained ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate. Based on the total mass of the electrolyte, the mass fraction of ethyl carbonate was 30%, the mass fraction of ethyl methyl carbonate was 43.75%, and the mass fraction of diethyl carbonate was 13.75%. After thorough mixing, LiPF6 was slowly added. Once the lithium salt had completely dissolved, an electrolyte with a lithium salt concentration of 1 mol / L was obtained. 4. Separator

[0089] A 16-µm polyethylene film was used as a separator. 5. Manufacturing a lithium-ion battery

[0090] The positive electrode array, separator, and negative electrode array were stacked on top of each other, with the separator positioned between the positive and negative electrode arrays to isolate them. The stacked assembly was wound to form a bare cell, to which tabs were welded. The bare cell was placed in an external casing, and the electrolyte, prepared as described above, was injected into the dried cell. Processes such as sealing, setting, forming, molding, and the like were carried out to complete the manufacture of the lithium-ion battery.

[0091] In Examples 2 to 28 and Comparative Examples 1 to 17, the lithium-ion battery was prepared in the same manner as in Example 1, except that the composition of the electrolyte additive and the solvent system were varied, as shown in Table 1. In Examples 29 and Comparative Examples 15 to 17, the lithium-ion battery was also prepared in the same manner as in Example 1, except that LiCoO2 was used as the active material of the positive electrode. Table 1 Electrolyte additive solvent electrolyte The compound represented by formula 1 Protective agents Mass ratio between the connection represented by formula 1 and the protective element l Cyclic solvent Other solvents Amount added to the electrolyte, wt.% Amount added to the electrolyte, wt.% composition Amount added to the electrolyte, wt.% composition Amount added to the electrolyte, wt.% composition Amount added to the electrolyte, wt.% Example 1 2 Formula 2-1 0,4 5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,35+13,75 12,5 Example 2 2 Formula 2-2 0,4 5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,35+13,75 12,5 Example 3 2 Formula 2-3 0,4 5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,35+13,75 12,5 Example 4 2 Formula 2-4 0,4 5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,35+13,75 12,5 Example 5 2 Formula 2-5 0,4 5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,35+13,75 12,5 Example 6 2 Formula 3-1 0,4 5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,35+13,75 12,5 Example 7 2 Formula 3-2 0,4 5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,35+13,75 12,5 Example 8 2 Formula 4-1 0,4 5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,35+13,75 12,5 Example 9 2 Formula 4-2 0,4 5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,35+13,75 12,5 Example 10 2 Formula 4-3 0,4 5:1 Ethylene carbonate 30 Ethyl methyl carbonate + diethyl carbonate 41,35+13,75 12,5 Example 11 0,3 Formula 2-1 0,4 0,75:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 43,05+13,75 12,5 Example 12 0,8 Formula 2-1 0,4 2:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 42,55+13,75 12,5 Example 13 1 Formula 2-1 0,4 2,5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 42,35+13,75 12,5 Example 14 1,5 Formula 2-1 0,4 3,75:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,85+13,75 12,5 Example 15 2,5 Formula 2-1 0,4 6,25:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 40,85+13,75 12,5 Example 16 3 Formula 2-1 0,4 7,5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 40,35+13,75 12,5 Example 17 3,5 Formula 2-1 0,4 8,75:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 39,85+13,75 12,5 Example 18 4 Formula 2-1 0,4 10:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 39,35+13,75 12,5 Example 19 2 Formula 4-1 2,86 0,7:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 38,89+13,75 12,5 Example 20 2 Formula 4-1 2 1:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 39,75+13,75 12,5 Example 21 2 Formula 4-1 0,67 3:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,08+13,75 12,5 Example 22 2 Formula 4-1 0,25 8:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,5+13,75 12,5 Example 23 2 Formula 4-1 0,2 10:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,55+13,75 12,5 Example 24 2 Formula 4-1 0,19 11:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,56+13,75 12,5 Example 25 2 Formula 2-1 0,4 5:1 Ethylene carbonate +Fluoroethylene carbonate 20+10 Ethyl methyl carbonate + diethyl carbonate 41,35+13,75 12,5 Example 26 2 Formula 2-1 0,4 5:1 Ethylene carbonate +Propylene carbonate 20+10 Ethyl methyl carbonate +diethyl carbonate 41,35+13,75 12,5 Example 27 2 Formula 2-1 0,4 5:1 Ethylene carbonate 10 Ethyl methyl carbonate +diethyl carbonate 61,35+13,75 12,5 Example 28 2 Formula 2-1 0,4 5:1 Ethylene carbonate 20 Ethyl methyl carbonate +diethyl carbonate 51,35+13,75 12,5 Example 29 2 Formula 2-1 0,4 5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,35+13,75 12,5 Comparison example 1 / / / / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 43,75+13,75 12,5 Comparison example 2 2 / / / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,75+13,75 12,5 Comparison example 3 / Formula 2-1 0,4 / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 43,35+13,75 12,5 Comparison example 4 / Formula 2-2 0,4 / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 43,35+13,75 12,5 Comparison example 5 / Formula 2-3 0,4 / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 43,35+13,75 12,5 Comparison example 6 / Formula 2-4 0,4 / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 43,35+13,75 12,5 Comparison example 7 / Formula 2-5 0,4 / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 43,35+13,75 12,5 Comparison example 8 / Formula 3-1 0,4 / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 43,35+13,75 12,5 Comparison example 9 / Formula 3-2 0,4 / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 43,35+13,75 12,5 Comparison example 10 / Formula 4-1 0,4 / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 43,35+13,75 12,5 Comparison example 11 / Formula 4-2 0,4 / Ethylene carbonate 30 Ethyl methyl carbonate + diethyl carbonate 43,35+13,75 12,5 Comparison example 12 / Formula 4-3 0,4 / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 43,35+13,75 12,5 Comparison example 13 2 Vinyl carbonate 0,4 5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,35+13,75 12,5 Comparison example 14 2 0,4 5:1 Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,35+13,75 12,5 Comparison example 15 / / / / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 43,75+13,75 12,5 Comparative example 16 2 / / / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 41,75+13,75 12,5 Comparative example 17 / Formula 2-1 0,4 / Ethylene carbonate 30 Ethyl methyl carbonate +diethyl carbonate 43,35+13,75 12,5

[0092] Note: In Table 1 above, the expression “the composition is A+B and the amount added to the electrolyte is a+b” is to be understood as “the composition is a mixture of A and B in which the proportion of A is accordingly a % and the proportion of B is accordingly b %”.

[0093] The energy performance, cycle life, and performance after high-temperature storage of the lithium-ion batteries obtained in Examples 1 to 29 and Comparison Examples 1 to 17 were characterized. The results of the characterization are shown in Table 2.

[0094] The following describes a test procedure for the cycle performance and energy performance of the lithium-ion battery.

[0095] The battery was charged at 45 °C with a constant current of 1.0 C to 4.4 V, then charged at a constant voltage until a cutoff current of 0.05 C was reached. The battery was then discharged with a constant current of 1.0 C. The discharge capacity was recorded as C0. The charge-discharge cycles were repeated until the capacity dropped to 80% of C0, and the number of cycles was recorded.

[0096] After undergoing the high-temperature cycling described above until the capacity was reduced to 80% of C0, the battery was charged at 1C to 4.4V and then charged at a constant voltage to a current of 0.05C. The battery was allowed to stand for 30 minutes, then discharged at 1C for 0.5 hours and allowed to stand for another 30 minutes. After standing, the voltage was recorded as V1. The battery was then discharged at 2C for 10 seconds with a sampling interval of 0.1 seconds, and the voltage at the end of the discharge was recorded as V2. The battery's direct-current internal resistance (DCR) was calculated using the following formula: DCR = (V1 - V2) / I, where I = 2C.

[0097] The following describes a procedure for testing the performance of the lithium-ion battery after high-temperature storage.

[0098] The battery was charged at 25 °C at a constant current of 1.0 C to 4.4 V and then charged at a constant voltage of 4.4 V until a cutoff current of 0.05 C was reached. The battery was then discharged at a constant current of 0.5 C. The discharge capacity was recorded as C1. The battery was removed, and its initial thickness was measured using a thickness gauge as T1. The battery was then charged at 25 °C at a constant current of 1.0 C to 4.4 V and then charged at a constant voltage of 4.4 V until a cutoff current of 0.05 C was reached. Afterward, the battery was transferred to an environment at 60 °C and left to stand for 15 days. After this 15-day period, its thickness was measured using a thickness gauge as T2. The battery was then discharged at a constant current of 1.0 C, and the discharge capacity was recorded as C2.The capacity retention rate after storage at 60 °C for 15 days was equal to C2 / C1*100%, and the threshold rate of the battery was equal to 100%*(T2-T1) / T1. Table 2 DCR after cycling (mhom) Capacity retention rate after storage at 60 °C for 15 days (%) Swell rate after storage at 60 °C for 15 days (%) Number of cycles until capacity reduction to 80% of CO2 Example 1 65,97 92,11 8,59 428 Example 2 67,14 91,99 9,55 401 Example 3 63,85 95,14 8,20 461 Example 4 65,14 91,67 8,26 433 Example 5 70,68 88,55 10,07 382 Example 6 64,14 90,11 8,4 458 Example 7 65,69 88,89 10,98 439 Example 8 63,39 94,22 6,39 557 Example 9 64,27 93,47 6,92 462 Example 10 66,14 88,27 7,47 421 Example 11 74,58 87,12 7,23 335 Example 12 72,47 89,01 7,51 349 Example 13 71,02 90,12 8,12 352 Example 14 69,78 91,98 8,5 366 Example 15 63,51 93,32 9,03 467 Example 16 62,28 93,46 9,21 526 Example 17 60,11 94,17 9,32 549 Example 18 59,05 95,51 9,69 632 Example 19 67,68 97,13 3,23 399 Example 20 65,31 96,53 4,61 442 Example 21 64,17 94,92 5,12 529 Example 22 61,36 92,13 7,02 651 Example 23 59,21 91,34 7,26 653 Example 24 59,29 90,95 7,2 667 Example 25 68,77 92,14 6,34 459 Example 26 63,82 90,57 7,45 451 Example 27 59,14 89,54 5,14 386 Example 28 61,64 90,47 6,24 401 Example 29 72,34 88,37 12,94 399 Comparison example 1 80,08 79,68 20,65 138 Comparison example 2 75,17 71,78 26,49 146 Comparison example 3 84,91 86,44 7,05 110 Comparison example 4 84,33 90,15 5,87 114 Comparison example 5 90,31 86,01 8,15 84 Comparison example 6 85,72 86,36 7,98 107 Comparison example 7 82,34 88,64 6,98 121 Comparison example 8 84,93 87,15 8,11 110 Comparison example 9 82,86 85,69 9,02 120 Comparison example 10 70,87 89,47 3,05 328 Comparison example 11 71,48 86,47 5,98 288 Comparison example 12 72,99 85,47 7,18 228 Comparison example 13 67,44 85,98 15,5 375 Comparison example 14 70,68 80,91 17,6 305 Comparison example 15 78,34 67,34 34,56 101 Comparative example 16 86,21 60,89 50,37 124 Comparative example 17 85,44 81,39 10,39 103

[0099] Conclusions: The data in Table 2 show that each of the lithium-ion batteries in Examples 1 to 29 exhibits a significantly lower DCR after cycling and a significantly lower threshold rate compared to the comparison examples 1 to 2. Furthermore, the capacity retention rates after storage at 60 °C and the cycle performance of the lithium-ion batteries in Examples 1 to 29 demonstrate that, as described in the present disclosure, the electrolyte additive containing the compound represented by Formula 1 and the chain compound with a degree of unsaturation greater than or equal to 3 can improve the performance, high-temperature storage performance, and cycle performance of lithium-ion batteries.

[0100] Compared to Comparison Example 3, Example 1; Comparison Example 4, Example 2; Comparison Example 5, Example 3; Comparison Example 6, Example 4; Comparison Example 7, Example 5; Comparison Example 8, Example 6; Comparison Example 9, Example 7; Comparison Example 10, Example 8; Comparison Example 11, Example 9; and Comparison Example 12, Example 10, the lithium-ion batteries of Examples 1 to 10 exhibit lower DCR values, higher capacity retention after storage at 60 °C, improved cycle performance, and higher threshold rates after cycling. This is due to the fact that the electrolyte additive of Examples 1 to 10 contains the compound represented by Formula 1, which causes gas generation in the electrolyte and consequently increases the battery's threshold rate.The SEI film formed in this process exhibits higher ionic conductivity and compactness, thereby reducing the DCR and improving capacity retention after storage at 60 °C as well as cycle life. A comparison of Examples 1 to 10 with the comparative example 13 clearly shows that the lithium battery of Example 5 exhibits a higher DCR. This is due to the degree of unsaturation of the protective agent used in Example 5 being 3, resulting in a lower degree of copolymerization with the compound of Formula 1 and consequently a lower sulfur content in the formed SEI film, leading to a higher DCR. Nevertheless, the lithium batteries of Examples 1 to 10 showed higher capacity retention, improved cycle life, and a lower threshold rate after storage at 60 °C.This is due to the fact that the protective agent used in examples 1 to 10 is a linear compound, which facilitates film formation and improves the thermal stability of the SEI film, thereby reducing the DCR and threshold rate after cycling and improving capacity retention after storage at 60 °C as well as the cycle performance of the battery.

[0101] A comparison of Examples 1 to 10 with Comparison Example 14 reveals that the lithium-ion batteries in Examples 1 to 10 exhibit a higher capacity retention rate and improved cycle life, as well as lower threshold rates and DCR values, after storage at 60 °C. This is due to the fact that the protective agent used in Examples 1 to 10 is a linear compound, which facilitates film formation and improves the thermal stability of the SEI film. This reduces the DCR and threshold rate after cycling and improves both the capacity retention after storage at 60 °C and the battery's cycle life. A comparison of Example 29 with Comparison Examples 15 to 17 reveals that, compared to Comparison Examples 15 and 16, Example 29 exhibits a higher capacity retention rate and improved cycle life, as well as a lower threshold rate and DCR value, after storage at 60 °C.Example 29 also shows a lower threshold rate compared to example 17. This is because the electrolyte additive in Example 29 contains the compound represented by Formula 1, which causes gas generation in the electrolyte and consequently increases the threshold rate of the lithium-ion battery. The resulting SEI film exhibits higher ionic conductivity and compactness, which reduces the DCR and improves capacity retention after storage at 60 °C as well as cycle performance.

[0102] In this description, phrases such as "one embodiment," "some embodiments," "examples," "specific examples," "some examples," etc., indicate that specific features, structures, materials, or properties described in connection with the embodiment or example are included in at least one embodiment or example of this disclosure. In this description, the schematic representations of the foregoing terms need not necessarily refer to the same embodiment or example. Furthermore, the described specific features, structures, materials, or properties may be combined in one or more embodiments or examples in a suitable manner.Furthermore, the person skilled in the art can combine different embodiments or examples and features of the different embodiments or examples described in this description without contradicting each other.

[0103] Even though embodiments have been shown and described in accordance with the present disclosure, the person skilled in the art will recognize that the foregoing embodiments are illustrative and should not be considered as limiting the present disclosure, and that changes, alternatives, modifications and variations may be made without deviating from the scope of protection of the present disclosure. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] CH 202311341961.4

[0001]

Claims

[1] Electrolyte additive comprising a compound represented by formula 1 and a protective agent, wherein the protective agent comprises a chain compound with a degree of unsaturation greater than or equal to 3 and is able to undergo an addition reaction with a free radical containing a sulfone ester group, formed after a ring-opening reaction of the compound represented by formula 1. [2] Electrolyte additive according to claim 1, wherein the protective agent comprises a chain compound with a degree of unsaturation ranging from 3 to 8. [3] Electrolyte additive according to claim 1 or 2, wherein a mass ratio of the compound represented by formula 1 to the protective agent ranges from 0.7:1 to 11:

1. [4] Electrolyte additive according to claim 1 or 2, wherein the chain compound with a degree of unsaturation greater than or equal to 3 comprises at least one of a silane compound, a carbonate compound or a sulfonate compound. [5] Electrolyte additive according to claim 4, wherein the silane compound comprises a compound represented by formula 2, wherein R1, R2, R3 and R4 are each independently selected from the group consisting of hydrogen, fluorine, alkyl with 1 to 10 carbon atoms, silyl with 1 to 10 carbon atoms, siloxy with 1 to 10 carbon atoms, alkenyl with 2 to 10 carbon atoms, alkynyl with 2 to 10 carbon atoms, alkenylsiloxy with 2 to 10 carbon atoms and alkynylsiloxy with 2 to 10 carbon atoms. [6] Electrolyte additive according to claim 5, wherein R1, R2, R3 and R4 are each independently selected from the group consisting of methyl, vinyl, ethynyl, ethynyldimethylsiloxy and trivinylsiloxy. [7] Electrolyte additive according to claim 5 or 6, wherein the silane compound comprises at least one of the following compounds: or [8] Electrolyte additive according to claim 5, wherein the carbonate compound comprises a compound represented by formula 3, where: AAlkenyl with 2 to 6 carbon atoms or Alkynyl with 2 to 6 carbon atoms; and R5 and R6 are each independently selected from the group consisting of hydrogen, fluorine, alkyl with 1 to 10 carbon atoms, alkenyl with 2 to 10 carbon atoms, alkynyl with 2 to 10 carbon atoms, an alkyl carbonate group with 2 to 10 carbon atoms, an alkyl sulfonate group with 1 to 10 carbon atoms, and fluoroalkyl with 1 to 10 carbon atoms, provided that at least one of R5 and R6 is an alkyl carbonate group with 2 to 10 carbon atoms. [9] Electrolyte additive according to claim 8, wherein R5 and R6 are each an alkyl carbonate group having 1 to 10 carbon atoms. [10] Electrolyte additive according to claim 9, wherein R5 and R6 are each a diethyl carbonate group with 1 to 10 carbon atoms. [11] Electrolyte additive according to any one of claims 8 to 10, wherein the carbonate compound comprises at least one of the following compounds: or [12] Electrolyte additive according to claim 4, wherein the sulfonate compound comprises a compound represented by formula 4, wherein R7 and R8 are each independently selected from the group consisting of a hydrogen atom, a fluorine atom, alkyl with 1 to 10 carbon atoms, fluoroalkyl with 1 to 10 carbon atoms, alkenyl with 2 to 10 carbon atoms and alkynyl with 2 to 10 carbon atoms. [13] Electrolyte additive according to claim 12, wherein R7 and R8 are each independently selected from the group consisting of methyl, trifluoromethyl, ethynyl, vinyl and a fluorine atom. [14] Electrolyte additive according to claim 12 or 13, wherein the sulfonate compound comprises at least one of the following compounds: or [15] Electrolyte comprising the electrolyte additive according to any one of claims 1 to 14. [16] Electrolyte according to claim 15, wherein, based on a total mass of the electrolyte, a mass fraction of the compound represented by formula 1 ranges from 0.3% to 4%. [17] Electrolyte according to claim 16, further comprising a solvent, wherein the solvent comprises a cyclic solvent. [18] Electrolyte according to claim 17, wherein the cyclic solvent comprises at least one of butylene carbonate, ethylene carbonate, fluoroethylene carbonate, propylene carbonate or 1,4-butyrolactone. [19] Electrolyte according to claim 18, wherein, based on the total mass of the electrolyte, a mass fraction of the cyclic solvent ranges from 10% to 30%. [20] Battery comprising the electrolyte according to any one of claims 15 to 19. [21] Battery according to claim 20, further comprising an active material of the positive electrode, wherein the active material of the positive electrode is at least one of LiCoO2, LiMn2O4, Li 1+y Mn ı - x M x O2, LiFe 1-x M x PO4 or Li2Mn 1-x O4 includes: M includes at least one of Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V or Ti; 0 ≤ y ≤ 0.2; and 0 ≤ x < 1. [22] Battery according to claim 21, wherein the active material of the positive electrode is at least one of LiCoO2 or Li 1+y Mn 1-x M x O2 comprises, where M comprises at least two of Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V or Ti. [23] Electrical device comprising the battery according to any one of claims 20 to 22.

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