Electrolyte, battery monomer, battery device and energy storage device

Abstract

The invention relates to the technical field of batteries, in particular to an electrolyte, a battery monomer, a battery device and an energy storage device. The electrolyte comprises a cyano siloxane compound shown in the formula, R1, R2, R3 and R4 independently comprise one of cyano, hydrogen, substituted or unsubstituted alkane, substituted or unsubstituted alkylene and substituted or unsubstituted alkyne, and at least two of R1, R2, R3 and R4 comprise cyano; r5, R6, R7, R8, R9 and R10 each independently comprise a substituted or unsubstituted alkane group. The electrolyte provided by the invention has good stability at normal temperature and high temperature, and is not easy to decompose.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an electrolyte, a battery cell, a battery device, and an energy storage device. Background Technology

[0002] Lithium-ion batteries are widely used in daily life, work, and production. As society develops, people have increasingly higher requirements for them, such as higher energy density. Methods to improve energy density include using high-energy-density cathode materials (such as high-nickel ternary cathode materials) and increasing the battery charging voltage. However, these methods can reduce the stability of the electrolyte and make it more prone to decomposition.

[0003] Adding additives to electrolytes is an important way to improve their stability. Some additives containing multiple functional groups can improve the stability of electrolytes at high temperatures, but they can reduce the stability of electrolytes at room temperature, making it difficult to improve the stability of electrolytes at both room temperature and high temperature at the same time. Summary of the Invention

[0004] This application is made in view of the above-mentioned technical problems, and its purpose is to solve the problem that electrolyte additives containing multiple functional groups are difficult to improve the room temperature and high temperature stability of electrolytes at the same time.

[0005] To achieve the above objectives, this application provides an electrolyte, a battery cell, a battery device, and an energy storage device.

[0006] The first aspect of this application provides an electrolyte comprising a cyanosiloxane compound of formula (1):

[0007]

[0008] R1, R2, R3, and R4 each independently include one of the following: a cyano group (-CN), hydrogen, a substituted or unsubstituted alkane group, a substituted or unsubstituted alkene group, or a substituted or unsubstituted alkynyl group, and at least two of R1, R2, R3, and R4 include a cyano group; R5, R6, R7, R8, R9, and R 10 Each can independently include substituted or unsubstituted alkane groups.

[0009] The electrolyte in this embodiment contains a cyanosiloxane compound of formula (1), which contains at least two cyano groups and at least two siloxane groups [-O-SiR5R6R7, -O-SiR8R9R]. 10 This cyanosiloxane compound can significantly improve the stability of the electrolyte at both room temperature and high temperature, making it less prone to decomposition at both conditions. The possible mechanism is as follows:

[0010] This cyanosiloxane compound can participate in the formation of the positive electrode electrolyte membrane (CEI membrane), forming a stable CEI membrane rich in cyano groups on the positive electrode surface. The cyano groups in the CEI membrane can adsorb or coordinate with transition metals in the positive electrode, thereby inhibiting the dissolution of transition metals and alleviating electrolyte decomposition caused by transition metals. Simultaneously, the siloxane groups in the cyanosiloxane compound structure can interact with HF and H2O in the electrolyte, eliminating HF and H2O. Since H2O reacts with lithium salt LiPF6 in the electrolyte to generate HF, the presence of HF directly accelerates electrolyte decomposition and also corrodes the positive electrode material, causing the dissolution of transition metals, which in turn causes electrolyte decomposition. Therefore, using siloxane groups to eliminate HF and H2O can also inhibit electrolyte decomposition. Moreover, the cyanosiloxane compound can exert the above-mentioned effects at both room temperature and high temperature, making the electrolyte of this embodiment highly stable and resistant to decomposition at both temperatures.

[0011] In some embodiments, the unsaturation degrees of R1, R2, R3, and R4 are independently 0 to 4, and optionally independently 2 to 4. The unsaturation degree of the functional groups has a significant impact on the formation and stability of the interfacial film between the electrolyte and the electrode. Under certain saturation levels, R1, R2, R3, and R4 can facilitate the redox reaction of cyanosiloxane compounds, thereby forming a stable interfacial film on the positive electrode surface. This results in a stable CEI film rich in cyano groups on the positive electrode surface. The cyano groups in the CEI film can adsorb or coordinate with transition metals in the positive electrode, thereby inhibiting the dissolution of transition metals and alleviating electrolyte decomposition caused by transition metals.

[0012] In some embodiments, R1 and R2 are both cyano groups; and / or, R3 and R4 are both cyano groups. In this case, the two cyano groups are bonded to the same carbon atom, and the cyano groups have a stronger adsorption or coordination complexation effect on the transition metal, which can better suppress the dissolution of the transition metal in the positive electrode and alleviate the electrolyte decomposition caused by the transition metal.

[0013] In some embodiments, one or both of R1, R2, R3 and R4 include substituted or unsubstituted alkane groups;

[0014] Alternatively, one of R1, R2, R3, and R4 includes a substituted or unsubstituted alkane group, and another includes a substituted or unsubstituted alkene group.

[0015] Alternatively, one of R1, R2, R3 and R4 includes a substituted or unsubstituted alkane group, and another includes a substituted or unsubstituted alkynyl group;

[0016] Alternatively, one of R1, R2, R3 and R4 includes a substituted or unsubstituted olefinic group, and another includes a substituted or unsubstituted alkyneic group;

[0017] Alternatively, three of R1, R2, R3, and R4 may include a cyano group, and one may include a substituted or unsubstituted olefinic group.

[0018] In some embodiments, the cyanosiloxane compound includes one or more of compounds 1 to 6:

[0019]

[0020]

[0021] Practice has shown that when R1, R2, R3, and R4 are selected from these groups, and when cyanosiloxane compounds are selected from these compounds, the stability of the electrolyte at both high and low temperatures can be improved effectively.

[0022] In some embodiments, the cyanosiloxane compound has a mass content of 0.1% to 10% in the electrolyte, optionally 0.1% to 5%. The cyanosiloxane compound can participate in the formation of the positive electrode CEI film, forming a cyano-rich CEI film, which inhibits the dissolution of transition metals in the positive electrode. Simultaneously, the siloxane groups can eliminate HF and H2O in the electrolyte, thereby improving electrolyte decomposition. Batteries containing this electrolyte exhibit advantages such as reduced gas production and increased cycle life. At a suitable mass content of the cyanosiloxane compound, the battery can have very low gas production and a long cycle life. Furthermore, at this mass content, the CEI film formed has a moderate thickness and low impedance.

[0023] In some embodiments, the electrolyte further includes one or more of cyclic carbonate electrolyte additives, cyclic sulfonyl lactone electrolyte additives, cyclic sulfate electrolyte additives, and lithium salt electrolyte additives. Exemplary cyclic carbonate electrolyte additives include one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), and ethylene ethylene carbonate (VEC). Exemplary cyclic sulfonyl lactone electrolyte additives include one or more of 1,3-propanesulfonyl lactone (PS) and 1,3-propenesulfonyl lactone (PST). Exemplary cyclic sulfate electrolyte additives include vinyl sulfate (DTD). Exemplary lithium salt electrolyte additives include one or more of lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiODFB), lithium bis(oxalate borate) (LiBOB), lithium tetrafluoroborate (LiBF4), and lithium difluorooxalate phosphate (LiODFP).

[0024] The mass content of cyclic carbonate electrolyte additives, cyclic sulfonyl lactone electrolyte additives, cyclic sulfate electrolyte additives, and lithium salt electrolyte additives in the electrolyte is independently 0.1% to 20%, and optionally independently 0.2% to 5%.

[0025] Optionally, the lithium salt electrolyte additive has a mass content of 0.5% to 2% in the electrolyte.

[0026] Optionally, the cyclic carbonate electrolyte additive has a mass content of 0.2% to 1% in the electrolyte.

[0027] Optionally, the cyclic sulfonyl lactone electrolyte additive has a mass content of 0.1% to 0.5% in the electrolyte.

[0028] Optionally, the cyclic sulfate electrolyte additive has a mass content of 0.5% to 1% in the electrolyte.

[0029] Cyclic carbonate electrolyte additives, cyclic sulfonyl lactone electrolyte additives, cyclic sulfate electrolyte additives, and lithium salt electrolyte additives are important additives that can improve the electrochemical performance of batteries, such as inhibiting electrolyte decomposition and improving battery cycle performance. By combining cyanosiloxane compounds with multiple additives, synergistic effects can be achieved, resulting in electrolytes with better stability and improved battery performance.

[0030] A second aspect of this application provides a battery cell including the electrolyte described above.

[0031] The electrolyte exhibits excellent stability at both room temperature and high temperature, is not easily decomposed, and reduces gas generation, enabling the battery cells to exhibit long cycle life, low internal resistance, and low gas production at both room temperature and high temperature.

[0032] A third aspect of this application provides a battery device comprising a plurality of the aforementioned battery cells.

[0033] The battery cell in this application embodiment includes an electrolyte containing cyanosiloxane compounds. This electrolyte exhibits excellent stability and is not easily decomposed at either room temperature or high temperature. This not only reduces gas generation but also minimizes thickness expansion during use or storage at both temperatures, resulting in excellent stability and safety. Furthermore, the battery cell demonstrates a long cycle life. Therefore, applying this battery cell to a battery device improves the safety of the device and extends its storage and operating time.

[0034] A fourth aspect of this application provides an energy storage device, including a plurality of the above-described battery cells or a plurality of the above-described battery devices, wherein the battery cells or battery devices are used to store or provide electrical energy.

[0035] The aforementioned battery cells and battery devices are used to store or provide electrical energy for energy storage devices, which can improve the safety of energy storage devices and extend the storage and battery life of energy storage devices. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of a battery cell according to one embodiment of this application;

[0038] Figure 2 for Figure 1 An exploded view of a battery cell according to one embodiment of this application is shown. Detailed Implementation

[0039] The embodiments of this application are hereby disclosed in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0040] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0" and "5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0041] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0042] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0043] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0044] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0045] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0046] Methods to improve the energy density of lithium-ion batteries include using high-energy-density cathode materials (such as high-nickel ternary cathode materials) and increasing the battery charging voltage. High-nickel ternary cathode materials, due to their high nickel content, can provide higher discharge specific capacity and volumetric energy density, so researchers have attempted to use them to improve the high energy density of lithium-ion batteries. However, this approach has adverse effects on the electrolyte. For example, excessively high nickel content in this material reduces the stability of the cathode material. During charging and discharging, nickel is usually in an unstable trivalent state, and unstable trivalent nickel ions can cause oxidative decomposition of the electrolyte at the cathode. Simultaneously, increasing the battery charging voltage can increase the battery's voltage plateau, thereby also increasing the battery's energy density. However, due to the low oxidation potential of the solvent in the electrolyte, it is difficult to remain stable at high voltages, and due to other factors, increasing the battery charging voltage makes the electrolyte more susceptible to oxidative decomposition. Oxidative decomposition of the electrolyte can lead to a series of problems such as battery swelling, increased interfacial impedance, and reduced cycle life. Therefore, it is necessary to develop an electrolyte formulation with good stability and resistance to decomposition.

[0047] Common methods to improve electrolyte stability include adding specific additives. Related research has used compounds containing siloxane groups as electrolyte additives. These additives exhibit dehydration and deacidification effects, thus mitigating electrolyte decomposition caused by water and acid. Simultaneously, some groups have film-forming properties, participating in the formation of a solid electrolyte interfacial film on the electrode surface, optimizing the electrode-electrolyte interfacial performance, and thus improving electrolyte stability. Other groups exhibit adsorption or coordination complexation with transition metals, thereby alleviating electrolyte decomposition problems caused by transition metals.

[0048] Because additives containing only one functional group have a limited effect on improving electrolyte stability, multiple additives containing different functional groups need to be added simultaneously to improve electrolyte stability from multiple perspectives. However, research has found that this approach is not very effective in improving electrolyte decomposition; moreover, to achieve different functions, multiple additives need to be added to the electrolyte, which is costly and complex to operate.

[0049] Considering that many electrolyte additives primarily utilize specific functional groups to achieve specific functions, one could explore combining these different groups into a single compound—that is, using a compound containing various functional groups as an additive. This way, adding a single additive to the electrolyte could achieve multiple different functions. However, practice shows that if an additive contains different functional groups, it may only improve the stability of the electrolyte under certain conditions, but its effect on the stability of the electrolyte under other conditions is not significant, and may even cause a deterioration in electrolyte stability. For example, some additives containing multiple functional groups may improve the stability of the electrolyte at high temperatures, but may reduce the stability of the electrolyte at room temperature.

[0050] Based on this, this application provides an electrolyte containing a cyanosiloxane compound that simultaneously contains siloxane and cyano groups. The siloxane and cyano groups are combined in the same compound in a certain way. This compound can effectively remove water and acid by utilizing the siloxane group, and can adsorb or coordinate with transition metals by utilizing the cyano group. Under the combined action of these two groups, the stability of the electrolyte at room temperature and high temperature can be improved at the same time.

[0051] The electrolyte of this application embodiment can be applied to battery cells, such as lithium secondary batteries, enabling the battery cells to exhibit long cycle life, low internal resistance, and low gas production at both room temperature and high temperature. This battery cell can be used in battery devices and energy storage devices.

[0052] The battery cell in this embodiment includes an electrolyte, and typically also includes a negative electrode, a positive electrode, and a separator. During battery charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator is disposed between the positive and negative electrodes, primarily to prevent short circuits between the positive and negative electrodes, while simultaneously allowing ions to pass through.

[0053] Electrolyte

[0054] The electrolyte acts as a conductor of ions between the positive and negative electrodes. In the embodiments of this application, the electrolyte includes cyanosiloxane compounds as shown in formula (1):

[0055]

[0056] R1, R2, R3, and R4 each independently include one of the following: a cyano group (-CN), H, a substituted or unsubstituted alkane group, a substituted or unsubstituted alkene group, or a substituted or unsubstituted alkyne group, and at least two of R1, R2, R3, and R4 include a cyano group; R5, R6, R7, R8, R9, and R 10Each can independently include substituted or unsubstituted alkane groups.

[0057] Understandably, the term "alkane group" refers to an organic group composed of saturated carbon-hydrogen bonds, derived from alkane molecules (alkanes are hydrocarbons containing only carbon-carbon and carbon-hydrogen single bonds, lacking double or triple bonds in their molecular structure). Alkane groups are typically chain-like, and can be straight-chain or branched; in some cases, alkane groups may also contain cyclic structures. In the embodiments of this application, alkane groups optionally include C1-C6 alkane groups, and optionally include C1-C3 alkane groups. Cx-Cy refers to the number of carbon atoms x-y; for example, C1-C6 alkane groups represent alkane groups with 1-6 carbon atoms. Exemplary alkane groups may include one or more of methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.

[0058] "Alkenyl group," also known as olefin group, can be considered as a group formed by removing one or more hydrogen atoms from an olefin molecule, containing one or more carbon-carbon double bonds. In the embodiments of this application, the olefin group includes C2-C6 olefin groups, optionally including C2-C3 olefin groups. Exemplary olefin groups include one or more of vinyl, propenyl, butenyl, pentenyl, hexenyl, butadienyl, pentadienyl, hexadienyl, and hextrienyl groups.

[0059] "Alkyne group," or alkynyl group, is a group containing a carbon-carbon triple bond (-C≡C-). In the embodiments of this application, the alkynyl group includes C2-C6 alkynyl groups, and optionally includes C2-C3 alkynyl groups. Exemplary alkynyl groups include one or more of ethynyl, propynyl, butynyl, pentyynyl, hexynyl, butyynyl, pentyynyl, hexadiynyl, and hexadiynyl.

[0060] "Substituted or unsubstituted" means that the hydrogen atom in the group is replaced by another group, or that the hydrogen atom in the group is not replaced by another group. The substituent group can include one or more of halogens, hydroxyl groups, and amino groups.

[0061] The structural formulas of cyanosiloxane compounds in the electrolyte and their substituents can be identified using gas chromatography-mass spectrometry (GC-MS).

[0062] The electrolyte in this embodiment contains a cyanosiloxane compound of formula (1), which contains at least two cyano groups and at least two siloxane groups [-O-SiR5R6R7, -O-SiR8R9R]. 10 This cyanosiloxane compound can significantly improve the stability of the electrolyte at both room temperature and high temperature, making it less prone to decomposition at both conditions. The possible mechanism is as follows:

[0063] This cyanosiloxane compound can participate in the formation of the positive electrode electrolyte membrane (CEI membrane), forming a stable CEI membrane rich in cyano groups on the positive electrode surface. The cyano groups in the CEI membrane can adsorb or coordinate with transition metals in the positive electrode, thereby inhibiting the dissolution of transition metals and alleviating electrolyte decomposition caused by transition metals. Simultaneously, the siloxane groups in the cyanosiloxane compound structure can interact with HF and H2O in the electrolyte, eliminating HF and H2O. Since H2O reacts with lithium salt LiPF6 in the electrolyte to generate HF, the presence of HF directly accelerates electrolyte decomposition and also corrodes the positive electrode material, causing the dissolution of transition metals, which in turn causes electrolyte decomposition. Therefore, using siloxane groups to eliminate HF and H2O can also inhibit electrolyte decomposition. Moreover, the cyanosiloxane compound can exert the above-mentioned effects at both room temperature and high temperature, making the electrolyte of this embodiment highly stable and resistant to decomposition at both temperatures.

[0064] In some implementations, the unsaturation of R1, R2, R3 and R4 is independently 0 to 4, and optionally independently 2 to 4, for example, it can be any point value of 0, 1, 2, 3, 4 or a range of values ​​between any two.

[0065] The degree of unsaturation of a functional group refers to the number of hydrogen atoms missing from the double bonds (C=C), triple bonds (C≡C), or ring structures formed by carbon atoms in the functional group compared to a fully saturated carbon group (i.e., all carbon atoms connected by single bonds). The types of functional groups R1, R2, R3, and R4 can be identified by GC-MS, and the degree of unsaturation can be calculated using the formula Ω = (2C + 2H + N) / 2, where Ω represents the degree of unsaturation, C represents the number of carbon atoms, H represents the number of hydrogen atoms, and N represents the number of nitrogen atoms.

[0066] The degree of unsaturation of functional groups has a significant impact on the formation and stability of the interfacial film between the electrolyte and the electrode. Under certain saturation, R1, R2, R3, and R4 can facilitate the redox reaction of cyanosiloxane compounds, thereby forming a stable interfacial film on the positive electrode surface. This results in a stable CEI film rich in cyano groups on the positive electrode surface. The cyano groups in the CEI film can adsorb or coordinate with transition metals in the positive electrode, thereby inhibiting the dissolution of transition metals and alleviating the electrolyte decomposition caused by transition metals.

[0067] In some embodiments, R1 and R2 are both cyano groups, and / or R3 and R4 are both cyano groups. In this case, the two cyano groups are bonded to the same carbon atom, and the cyano groups have a stronger adsorption or coordination complexation effect on the transition metal, which can better suppress the dissolution of the transition metal in the positive electrode and alleviate the electrolyte decomposition caused by the transition metal.

[0068] In some embodiments, one or both of R1, R2, R3 and R4 include substituted or unsubstituted alkane groups;

[0069] Alternatively, one of R1, R2, R3, and R4 includes a substituted or unsubstituted alkane group, and another includes a substituted or unsubstituted alkene group.

[0070] Alternatively, one of R1, R2, R3 and R4 includes a substituted or unsubstituted alkane group, and another includes a substituted or unsubstituted alkynyl group;

[0071] Alternatively, one of R1, R2, R3 and R4 includes a substituted or unsubstituted olefinic group, and another includes a substituted or unsubstituted alkyneic group;

[0072] Alternatively, three of R1, R2, R3, and R4 may include a cyano group, and one may include a substituted or unsubstituted olefinic group.

[0073] In some embodiments, the cyanosiloxane compound includes one or more of compounds 1 to 6:

[0074]

[0075] Practice has shown that when R1, R2, R3, and R4 are selected from these groups, and when cyanosiloxane compounds are selected from these compounds, the stability of the electrolyte at both high and low temperatures can be improved effectively.

[0076] In some embodiments, the cyanosiloxane compound in the electrolyte contains 0.1% to 10% by mass, optionally 0.1% to 5%, and even more optionally 0.1% to 1%. For example, the mass content can be any one of 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, or a range between any two.

[0077] The mass content of cyanosiloxane compounds can be analyzed using gas chromatography-mass spectrometry (GC-MS). Understandably, during electrolyte preparation, cyanosiloxane compounds can be added to the electrolyte at the mass content described above. Furthermore, after the electrolyte is applied to the battery and during battery operation, although some cyanosiloxane compounds are consumed due to their participation in the formation of the positive electrode CEI film, the consumption is negligible because the CEI film is typically very thin. Therefore, the mass content of cyanosiloxane compounds in the electrolyte usually does not change significantly after application to a lithium battery and during battery operation. Moreover, when the cyanosiloxane compounds include specific compounds with different structural formulas, these compounds can be combined in any proportion. For example, if the cyanosiloxane compounds are a combination of compound 1 and compound 6, they can be combined in any proportion, as long as their total mass content remains within the aforementioned range.

[0078] Cyanosiloxane compounds can participate in the formation of the CEI film in the positive electrode, forming a cyano-rich CEI film. These cyano groups are used to inhibit the dissolution of transition metals in the positive electrode. Simultaneously, the siloxane groups can eliminate HF and H2O in the electrolyte, thereby improving electrolyte decomposition. Batteries containing this type of electrolyte exhibit advantages such as reduced gas production and increased cycle life. At appropriate mass concentrations of cyanosiloxane compounds, the battery can achieve very low gas production and long cycle life. Furthermore, at these mass concentrations, the CEI film formed has a suitable thickness and low impedance.

[0079] In some embodiments, the electrolyte further includes one or more of cyclic carbonate electrolyte additives, cyclic sulfonyl lactone electrolyte additives, cyclic sulfate electrolyte additives, and lithium salt electrolyte additives. Exemplary cyclic carbonate electrolyte additives include one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), and ethylene ethylene carbonate (VEC). Exemplary cyclic sulfonyl lactone electrolyte additives include one or more of 1,3-propanesulfonyl lactone (PS) and 1,3-propenesulfonyl lactone (PST). Exemplary cyclic sulfate electrolyte additives include vinyl sulfate (DTD). Exemplary lithium salt electrolyte additives include one or more of lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiODFB), lithium bis(oxalate borate) (LiBOB), lithium tetrafluoroborate (LiBF4), and lithium difluorooxalate phosphate (LiODFP).

[0080] The mass content of cyclic carbonate electrolyte additives, cyclic sulfonyl lactone electrolyte additives, cyclic sulfate electrolyte additives, and lithium salt electrolyte additives in the electrolyte is independently 0.1% to 20%, and optionally independently 0.2% to 5%, for example, any one of 0.1%, 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 16%, 18%, 20%, or any range between two of them.

[0081] Optionally, the lithium salt electrolyte additive has a mass content of 0.5% to 2% in the electrolyte, for example, any one of 0.5%, 1%, 1.5%, or 2%, or a range between any two. Optionally, the cyclic carbonate electrolyte additive has a mass content of 0.2% to 1% in the electrolyte, for example, any one of 0.2%, 0.5%, or 1%, or a range between any two. Optionally, the cyclic sulfonyl lactone electrolyte additive has a mass content of 0.1% to 0.5% in the electrolyte, for example, any one of 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%, or a range between any two. Optionally, the cyclic sulfate electrolyte additive has a mass content of 0.5% to 1% in the electrolyte, for example, any one of 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1%, or a range between any two.

[0082] Cyclic carbonate electrolyte additives, cyclic sulfonyl lactone electrolyte additives, cyclic sulfate electrolyte additives, and lithium salt electrolyte additives are important additives that can improve the electrochemical performance of batteries, such as inhibiting electrolyte decomposition and improving battery cycle performance. By combining cyanosiloxane compounds with multiple additives, synergistic effects can be achieved, resulting in electrolytes with better stability and improved battery performance.

[0083] In some embodiments, the electrolyte also includes a solvent and an electrolyte lithium salt.

[0084] The solvent may be a non-aqueous organic solvent, such as one or more of ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), propylene carbonate (PC), diethyl carbonate (DEC), propylene carbonate (PC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), and ethyl butyrate (EB), optionally two or more.

[0085] The electrolyte lithium salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium bis(oxalate borate) (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorooxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP). It is understood that the "electrolyte lithium salt" in the embodiments of this application is a different concept from the "lithium salt electrolyte additive" mentioned above. The "electrolyte lithium salt" refers to the main component in the electrolyte that provides lithium ions, playing a role in ion transport during battery charging and discharging; while the "lithium salt electrolyte additive" is a small amount of substance added to the electrolyte to improve certain specific battery performance.

[0086] The concentration of the lithium electrolyte salt in the electrolyte can range from 0.5 to 2 mol / L, for example, any one of 0.5 mol / L, 0.6 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.5 mol / L, and 2 mol / L, or any range between two values. The mass content of the lithium electrolyte salt in the electrolyte can be 5% to 20%, optionally 10% to 15%, for example, any one of 5%, 10%, 13%, 15%, and 20%, or any range between two values.

[0087] The electrolyte in this embodiment can be prepared by the following method:

[0088] Under a protective atmosphere (such as argon or nitrogen), electrolyte lithium salts, cyanosiloxane compounds, and other additives are dissolved in a solvent.

[0089] [Positive electrode plate]

[0090] The battery cell in this application embodiment includes a positive electrode sheet, which includes a positive current collector and a positive active layer disposed on at least one side of the positive current collector. The positive active layer includes a positive active material, a conductive agent, and a binder.

[0091] In some embodiments, the positive electrode active material comprises a transition metal, such as one or more of nickel, cobalt, and manganese. The cyano groups provided by the cyanosiloxane compounds in the electrolyte of this application embodiment can adsorb or coordinate with these transition metals, mitigating their dissolution.

[0092] In some embodiments, the positive electrode active material includes 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, and lithium nickel cobalt manganese oxide [such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2(NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811)], lithium nickel cobalt aluminum oxides [such as LiNi] 0.8 Co 0.15 Al 0.05 O2, LiNi 0.8 Co 0.1 Al 0.1 One or more of O2 (i.e., NCA811) and its modified compounds. These positive electrode active materials can be used alone or in combination of two or more. Optionally, the positive electrode active materials include NCM811, LiNi 0.8 Co 0.15 Al 0.05 O2, one or more of NCA811, NCM811, LiNi 0.8 Co 0.15 Al 0.05 O2 and NCA811 have high nickel content, resulting in high specific capacity and high energy density, which is beneficial for improving the energy density of batteries. In this application, cyanosiloxane compounds are added to the electrolyte, which significantly improves the stability of the electrolyte and makes it less prone to decomposition, regardless of the cathode active material used in the battery; the improvement is particularly pronounced in electrolyte stability under high-nickel cathode active material systems.

[0093] The mass content of the positive electrode active material in the positive electrode active layer can be, but is not limited to, 70% to 98%, or 80% to 98%, for example, any one of 70%, 75%, 80%, 85%, 90%, 92%, 94%, 96%, 98%, or any range between two.

[0094] In some embodiments, the binder in the positive electrode active layer may include one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyethylene ether, polymethyl methacrylate (PMMA), polyhexafluoropropylene, and styrene-butadiene rubber (SBR).

[0095] In some embodiments, the conductive agent in the positive electrode active layer may include one or more of acetylene black, conductive carbon black (SP), Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0096] The mass content of binder and conductive agent in the positive electrode active layer can be independently, including but not limited to 0.5% to 10%, or 1% to 10%, for example, any one of the values ​​of 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any range between the two.

[0097] In some embodiments, the positive electrode active layer may optionally include a thickener, which may include one or more of sodium carboxymethyl cellulose (CMC-Na) and sodium alginate.

[0098] In some embodiments, the positive electrode active layer may optionally include additives, such as additives that can improve certain properties of the positive electrode, such as additives with lithium replenishment effects, such as additives that can improve the regulation of CEI composition.

[0099] In some embodiments, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0100] In some embodiments, the positive current collector includes one or more of a metal foil and a composite current collector. For example, aluminum 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 can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate [such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.].

[0101] In some implementations, the positive electrode sheet can be prepared in the following manner:

[0102] The components used to prepare the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, are dispersed in a solvent (e.g. N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0103] The compaction density of the positive electrode sheet after cold pressing is typically 3 g / cm³. 3 ~5g / cm 3 For example, 3.5g / cm 3 ~4.2g / cm 3 For example, 3g / cm 3 3.5g / cm 3 4g / cm 3 4.2g / cm 3 4.5g / cm 3 5g / cm 3 The value of any one of the points or the range between any two.

[0104] [Negative electrode plate]

[0105] The battery cell in this application embodiment includes a negative electrode sheet, which includes a negative current collector and a negative active layer disposed on at least one side of the negative current collector. The negative active layer includes a negative active material, a conductive agent, and a binder.

[0106] In some embodiments, the negative electrode active material includes one or more of graphite (artificial graphite, natural graphite), soft carbon, hard carbon, silicon-based materials, tin-based materials, and titanium-based materials. Silicon-based materials may include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include one or more of elemental tin, tin oxide compounds, and tin alloys. Titanium-based materials may include lithium titanate. It is understood that this application is not limited to these materials, and other materials that can be used as negative electrode active materials in batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0107] The mass content of the negative electrode active material in the negative electrode active layer can range from 70% to 98%, or even 90% to 98%, for example, any one of the values ​​or any range between 70%, 75%, 80%, 85%, 90%, 92%, 94%, 96%, and 98%. A high content of negative electrode active material can provide high energy density for the battery.

[0108] In some embodiments, the binder may include one or more of styrene-butadiene rubber (SBR), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS). The mass content of the binder in the negative electrode active layer may be 0.1% to 10%, for example, any one or a range between 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%.

[0109] In some embodiments, the conductive agent may include one or more of acetylene black, conductive carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The mass content of the conductive agent in the negative electrode active layer includes 0.5% to 10%, for example, any one of 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%, or a range between any two.

[0110] In some embodiments, the negative electrode active layer may optionally include other additives, such as thickeners, like carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (CMC-Na), etc.

[0111] In some embodiments, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector. The negative electrode current collector includes one or more of metal foil and composite current collector. For example, copper foil can be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate [such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.].

[0112] In some implementations, the negative electrode sheet can be prepared in the following manner:

[0113] The components used to prepare the negative electrode sheet, such as negative electrode active material, binder, and conductive agent (and may also include any other components), are dispersed in a solvent (e.g., water) to form a negative electrode slurry; the negative electrode slurry is coated on at least one side of the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0114] The compaction density of the negative electrode sheet after cold pressing is typically 1.3 g / cm³. 3 ~2g / cm 3 For example, 1.3g / cm3 ~1.7g / cm 3 For example, 1.3g / cm 3 1.5g / cm 3 1.7g / cm 3 1.9g / cm 3 2g / cm 3 The value of any one of the points or the range between any two.

[0115] [Isolation membrane]

[0116] Separating membranes are typically stacked between the positive and negative electrodes to separate them, preventing electrons from passing freely and thus preventing short circuits between the electrodes. At the same time, they allow ions in the electrolyte to pass freely between the positive and negative electrodes.

[0117] In the battery of this application, the type of separator can be any known porous structure separator with good chemical and mechanical stability.

[0118] The material of the separator membrane can include one or more of the following: glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride (PVDF). The separator membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. The surface of the separator membrane can be coated with a ceramic coating, such as an alumina coating.

[0119] Positive electrode, negative electrode and separator can be made into electrode assembly by winding process or stacking process.

[0120] [Outer Packaging]

[0121] A single battery cell may include an outer packaging that can be used to encapsulate an electrode assembly containing a positive electrode, a negative electrode, a separator, and an electrolyte.

[0122] The outer packaging can be a hard shell, such as a hard plastic shell, aluminum shell, or steel shell; or it can be a soft package, such as a pouch. The material of the soft package can be plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0123] The outer packaging can be cylindrical, square, or any other shape. For example, Figure 1 The battery cell, as an example, has a square outer packaging shape.

[0124] Reference Figure 2The outer packaging may include a housing 01 and a cover plate 02. The housing 01 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 01 has an opening communicating with the receiving cavity, and the cover plate 02 can be placed over the opening to close the receiving cavity. A positive electrode, a negative electrode, and a separator can be formed into an electrode assembly 03 via a winding or stacking process. One or more electrode assemblies 03 are encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 03.

[0125] [Battery cell]

[0126] In this embodiment, the battery cell can be a rechargeable battery, which refers to a battery cell that can be recharged after discharge to activate the active materials and continue to be used. Optionally, the battery cell in this embodiment can be a lithium-ion battery.

[0127] The battery cell includes an electrolyte containing cyanosiloxane compounds. This electrolyte has good stability at both room temperature and high temperature, is not easily decomposed, and reduces gas production. This allows the battery cell to exhibit characteristics such as long cycle life, low internal resistance, and low gas production at both room temperature and high temperature.

[0128] [Battery Device]

[0129] This application provides a battery apparatus including multiple battery cells. Specifically, the battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells, which are connected in series, parallel, or mixed connections via a busbar.

[0130] The battery cells of this application embodiment have the advantages of low gas production (small thickness expansion) when used or stored at room temperature or high temperature, exhibiting excellent stability and safety, and also demonstrating a long cycle life. Therefore, applying this battery cell to a battery device is beneficial to improving the safety of the battery device and extending its storage and operating time.

[0131] In some implementations, a battery cell assembly is typically formed by arranging multiple battery cells.

[0132] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties.

[0133] In some implementations, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0134] As an example, the battery cell assembly can be a battery module, and the battery cell assembly can be housed in the housing by fixing the battery module in the housing.

[0135] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0136] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0137] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0138] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0139] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft.

[0140] [Energy Storage Device]

[0141] This application provides an energy storage device, including multiple battery cells or multiple battery devices, wherein the battery cells or battery devices are used to store or provide electrical energy.

[0142] The aforementioned battery cells and battery devices are used to store or provide electrical energy for energy storage devices, which can improve the safety of energy storage devices and extend the storage and battery life of energy storage devices.

[0143] In some implementations, the energy storage device includes one or more battery clusters to increase the voltage and capacity of the energy storage device. A battery cluster may include multiple battery units connected in series via a busbar to increase the voltage of the energy storage device. When the energy storage device includes multiple battery clusters, the battery clusters are connected in parallel to increase the capacity of the energy storage device.

[0144] Energy storage devices can be used in energy storage power stations, wind power generation systems, solar power generation systems, mobile power systems, or temporary power supply systems. Energy storage devices can store electrical energy as needed and output it when appropriate. For example, an energy storage device can store electrical energy during off-peak hours and provide power to relevant users or electrical equipment during peak hours. The energy storage system provided in this application embodiment can be any power system that requires energy storage devices.

[0145] In some implementations, the energy storage device is an energy storage container or an energy storage cabinet.

[0146] In some implementations, the energy storage device may include a cabinet and one or more battery clusters housed within the cabinet.

[0147] In some implementations, the energy storage device may include modules such as a thermal management module, a main control module, a central control module, a power distribution module, and a fire protection module.

[0148] As an example, the thermal management module may include a liquid cooling unit that supplies coolant to each battery device via piping to regulate the temperature of the individual battery cells.

[0149] As an example, the main control module can serve as the battery management unit for the battery cluster, used to monitor and manage the battery cluster. The main control module can monitor information such as the current, voltage, power, or temperature of the battery cluster. For instance, it can control the charging and discharging current and voltage of the battery cluster. The main control module includes modules such as an auxiliary battery management unit (SBMU) and a fusion switch.

[0150] As an example, the central control module can serve as the battery management unit for an energy storage device, used to monitor and manage the device. The central control module can monitor information such as the energy storage device's current, voltage, power, state of charge, or temperature. For instance, it can control the charging and discharging current and voltage of the energy storage device. As an example, the central control module includes modules such as an Insulation Monitoring Module (IMM), a Master Battery Management Unit (MBMU), an Ethernet (ETH) module, and a fiber optic conversion module.

[0151] As an example, the fire protection module includes a control panel, detectors, alarm devices, etc., used to detect, alarm, or extinguish fires in the energy storage system.

[0152] As an example, a power distribution module can be used to distribute power to modules in an energy storage device that require electricity.

[0153] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0154] Example 1

[0155] 1. Positive electrode sheet

[0156] LiNi, the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2 (NCM811), conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) were thoroughly mixed in an N-methylpyrrolidone solvent system at a mass ratio of 95:3:2. The mixture was then coated onto aluminum foil, dried, and cold-pressed to obtain the positive electrode sheet with a compacted density of 3.5 g / cm³. 3 .

[0157] 2. Negative electrode plate

[0158] The negative electrode active material graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) were thoroughly mixed in a deionized water solvent system at a mass ratio of 96:2:1:1. The mixture was then coated onto Cu foil, dried, and cold-pressed to obtain the negative electrode sheet with a compaction density of 1.65 g / cm³. 3 .

[0159] 3. Electrolyte

[0160] Electrolyte was prepared in a glove box (nitrogen content 99.999%, actual oxygen content 0.1 ppm, moisture content 0.1 ppm). Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a mass ratio of 3:5:2 to obtain a mixed solvent. 13% LiPF6 and additives were added to the mixed solvent and mixed thoroughly to obtain the electrolyte. The additives included Compound 1, lithium difluorophosphate (LiPO2F2), vinylene carbonate (VC), 1,3-propanesulfonate lactone (PS), and vinyl sulfate (DTD), with the following mass percentages in the electrolyte: 1% Compound 1, 1% LiPO2F2, 0.5% VC, 0.2% PS, and 0.8% DTD.

[0161] The structural formula of compound 1 is:

[0162] 4. Separating membrane

[0163] A coated isolation membrane was obtained by using 9μm polyethylene as the base film and coating the base film with a 3μm thick nano-alumina coating.

[0164] 5. Battery assembly

[0165] The prepared positive electrode, separator, and negative electrode are stacked sequentially, with the separator positioned between the positive and negative electrodes to provide isolation, resulting in a bare cell. The bare cell is then placed in an aluminum-plastic film, baked at 80°C to remove moisture, injected with electrolyte, and sealed. After further processing, including standing, hot and cold pressing, formation, clamping, and capacity testing, the finished soft-pack nickel-cobalt-manganese battery is obtained.

[0166] Example 2

[0167] The difference between this embodiment and Embodiment 1 is that compound 1 in the electrolyte is replaced with an equal mass of compound 2.

[0168] The structural formula of compound 2 is:

[0169] Example 3

[0170] The difference between this embodiment and Embodiment 1 is that compound 1 in the electrolyte is replaced with an equal mass of compound 3.

[0171] The structural formula of compound 3 is:

[0172] Example 4

[0173] The difference between this embodiment and Embodiment 1 is that compound 1 in the electrolyte is replaced with an equal mass of compound 4.

[0174] The structural formula of compound 4 is:

[0175] Example 5

[0176] The difference between this embodiment and Embodiment 1 is that compound 1 in the electrolyte is replaced with an equal mass of compound 5.

[0177] The structural formula of compound 5 is:

[0178] Example 6

[0179] The difference between this embodiment and Embodiment 1 is that Compound 1 in the electrolyte is replaced with Compound 6; and multiple sets of experiments are set up, with the mass content of Compound 6 in the electrolyte set to 0.1%, 0.5%, 1%, 3%, 5%, and 10%, respectively.

[0180] The structural formula of compound 6 is:

[0181] Example 7

[0182] The difference between this embodiment and Embodiment 1 is that Compound 6 is added to the electrolyte simultaneously, and the mass content of both Compound 1 and Compound 6 in the electrolyte is adjusted to 0.5%.

[0183] Comparative Example 1

[0184] The difference between Comparative Example 1 and Example 1 is that Compound 1 was not added to the electrolyte.

[0185] Comparative Example 2

[0186] The difference between this comparative example and Example 1 is that compound 1 is replaced with an equal mass of benzyloxymethoxysilane (CAS: 14642-79-6).

[0187] The structural formula of benzyloxymethoxysilane is:

[0188] Comparative Example 3

[0189] The difference between this comparative example and Example 1 is that compound 1 is replaced with an equal mass of 1,4-bis(trimethylsiloxy)benzene (CAS: 2117-24-0).

[0190] The structural formula of 1,4-bis(trimethylsiloxy)benzene is:

[0191] The performance of the nickel-cobalt-manganese batteries in each embodiment and comparative example was tested using the following methods:

[0192] (1) Cyclic life at ambient temperature

[0193] After capacity testing, the fully charged battery is discharged at 25°C at 1C to 2.8V, and the initial discharge capacity is recorded as DC(1-R). Then, it is charged at 25°C at a constant current and constant voltage of 1C to 4.2V, with a cutoff current of 0.05C. After resting for 5 minutes, it is discharged again at 1C to 2.8V, and the discharge capacity is recorded as DC(2-R). This cycle is repeated N times until the discharge capacity DC(NR) < 80% of DC(1-R). The number of discharges N is recorded, and N is the room temperature cycle life.

[0194] (2) High-temperature cycle life

[0195] After capacity testing, the fully charged battery is placed in a 45°C incubator and discharged at 1C to 2.8V. The initial discharge capacity is recorded as DC(1-H). Then, it is charged at a constant current and voltage of 1C to 4.2V, with a cutoff current of 0.05C. After resting for 5 minutes, it is discharged again at 1C to 2.8V, and the discharge capacity is recorded as DC(2-H). This cycle is repeated N times until DC(NH) < 80% of DC(1-H). The number of discharges, N, is recorded as the high-temperature cycle life.

[0196] (3) Gas production rate and DCR (direct current resistance) growth rate during high-temperature storage

[0197] After being fully charged at room temperature (25℃), the battery was left to stand for 30 minutes, then discharged at 4C for 30 seconds until it reached 2.8V. The initial full-charge discharge rate (DCR) (0-S) was recorded, and the initial cell volume (Vol(0-S)) was measured simultaneously. The battery was then stored in a 60℃ constant temperature chamber for n days. After being removed, the battery was charged at room temperature with a constant current and voltage of 1C to 4.2V, with a cutoff current of 0.05C. After standing for 30 minutes, the battery was discharged at 4C for 30 seconds, and the full-charge discharge rate (DCR) (nS) after n days of storage was recorded. The DCR growth rate after n days of high-temperature storage is calculated as 100% * [DCR(nS) - DCR(0-S)] / DCR(0-S). Simultaneously, the cell volume (Vol(nS)) after n days was measured, and the gas production rate after n days of high-temperature storage is calculated as 100% * [Vol(nS) - Vol(0-S)] / Vol(0-S).

[0198] The test results are shown in Table 1 below.

[0199] [Table 1]

[0200]

[0201] (1) Comparative Examples 1 to 3

[0202] Test results show that, in Comparative Example 1, no cyanosiloxane compounds were added to the electrolyte as additives. The battery exhibited high high-temperature storage gas generation rate and high-temperature storage DCR growth rate, but shorter cycle life at both high and room temperatures. The high high-temperature storage gas generation rate indicates that the electrolyte is prone to decomposition and instability at high temperatures under these conditions; electrolyte decomposition leads to increased impedance and shortened cycle life.

[0203] Considering that siloxane groups have dehydration and deacidification properties, and that some compounds containing benzene rings can improve electrolyte stability and protect the electrolyte from oxidation under high voltage, while others containing benzene rings can form a stable electrolyte interface film on the electrode surface, optimizing the electrode-electrolyte interface performance and improving battery cycle stability, this application investigated experiments using siloxane groups and benzene rings in the same compound as electrolyte additives, namely Comparative Examples 2 and 3. Benzyloxymethoxysilane and 1,4-bis(trimethylsiloxy)benzene, which simultaneously contain siloxane groups and benzene rings, were added to the electrolyte. The results showed that using the compounds in Comparative Examples 2 and 3 as electrolyte additives led to a decrease in cycle life at room temperature. This indicates that combining unsuitable functional groups in the same compound as an electrolyte additive may cause performance degradation.

[0204] (2) Examples 1 to 7

[0205] Compared to Comparative Examples 1 to 3, Examples 1 to 7 added cyanosiloxane compounds, such as Compound 1 to Compound 6, which are composed of siloxane and cyano groups in a certain structure, to the electrolyte. As a result, compared to Comparative Example 1, it can not only significantly reduce the high-temperature storage gas generation rate and the high-temperature storage DCR growth rate, and improve the high-temperature cycle life, but also, compared to Comparative Examples 2 to 3, it does not cause a decrease in the room temperature cycle life, but can simultaneously improve the room temperature cycle life.

[0206] 1) Gas production rate during high-temperature storage

[0207] Since the gas production in the battery mainly originates from the decomposition of the electrolyte, a decrease in gas production rate during high-temperature storage indicates a reduction in electrolyte decomposition. Therefore, it can be concluded that adding cyanosiloxane compounds such as Compounds 1 to 6 to the electrolyte can improve the electrolyte's stability at high temperatures, making it less prone to decomposition at high temperatures.

[0208] This is likely because these cyanosiloxane compounds can participate in the formation of the CEI film at the positive electrode, creating a stable CEI film rich in cyano groups on the positive electrode surface. The cyano groups in the CEI film can adsorb or coordinate with nickel in the positive electrode, thereby inhibiting nickel dissolution and mitigating electrolyte decomposition caused by nickel dissolution. Simultaneously, the siloxane groups in the cyanosiloxane compounds can interact with HF and H2O in the electrolyte, eliminating them. Since H2O reacts with lithium salt LiPF6 in the electrolyte to generate HF, the presence of HF directly accelerates electrolyte decomposition and also corrodes the positive electrode material, causing nickel dissolution, which in turn leads to electrolyte decomposition. Therefore, under the action of cyanosiloxane compounds such as compounds 1 to 6, the decomposition problem of the electrolyte at high temperatures is suppressed, and its stability is improved.

[0209] 2) High-temperature storage DCR growth rate

[0210] For high-nickel batteries, their impedance is usually correlated with nickel dissolution. As mentioned earlier, adding these cyanosiloxane compounds to the electrolyte can suppress nickel dissolution, which is beneficial for reducing the DCR growth rate during high-temperature storage.

[0211] In addition, tests revealed that the negative electrode electrolyte interface film (SEI film) contains inorganic component L3N, reflecting that cyanosiloxane compounds can induce the formation of an SEI film containing L3N. L3N has low impedance, which is also beneficial to reduce battery impedance.

[0212] 3) Cycle life

[0213] The addition of cyanosiloxane compounds such as Compounds 1 to 6 to the electrolyte improves its stability, making it less prone to decomposition and suppressing nickel dissolution. This reduces the loss of electrolyte and positive electrode active material during battery cycling, resulting in an improved high-temperature cycle life. Notably, the room-temperature cycle life of Examples 1 to 7 is also significantly improved compared to Comparative Examples 1 to 3. This is likely because the siloxane groups and cyano groups in the cyanosiloxane compounds can also play the role described in 1) above at room temperature, improving the electrolyte's stability at room temperature and suppressing nickel dissolution, thus enhancing the battery's room-temperature cycle life.

[0214] In summary, by adding cyanosiloxane compounds to the electrolyte, the stability of the electrolyte at both room temperature and high temperature can be improved, making it less prone to decomposition; thereby, the gas generation, impedance, and cycle life of batteries containing such electrolytes can be improved.

[0215] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. An electrolyte, characterized in that, Including cyanosiloxane compounds represented by formula (1): R1, R2, R3, and R4 each independently include one of the following: a cyano group, hydrogen, a substituted or unsubstituted alkane group, a substituted or unsubstituted alkene group, or a substituted or unsubstituted alkyne group, and at least two of R1, R2, R3, and R4 include a cyano group; R5, R6, R7, R8, R9, and R 10 Each can independently include substituted or unsubstituted alkane groups.

2. The electrolyte according to claim 1, characterized in that, The unsaturation degrees of R1, R2, R3 and R4 are independently 0 to 4.

3. The electrolyte according to claim 1 or 2, characterized in that, The unsaturation degrees of R1, R2, R3 and R4 are independently 2 to 4.

4. The electrolyte according to any one of claims 1 to 3, characterized in that, R1 and R2 are both cyano groups; and / or R3 and R4 are both cyano groups.

5. The electrolyte according to any one of claims 1 to 4, characterized in that, One or both of R1, R2, R3 and R4 include substituted or unsubstituted alkane groups; Alternatively, one of R1, R2, R3, and R4 includes a substituted or unsubstituted alkane group, and another includes a substituted or unsubstituted alkene group. Alternatively, one of R1, R2, R3 and R4 includes a substituted or unsubstituted alkane group, and another includes a substituted or unsubstituted alkynyl group; Alternatively, one of R1, R2, R3 and R4 includes a substituted or unsubstituted olefinic group, and another includes a substituted or unsubstituted alkyneic group; Alternatively, three of R1, R2, R3, and R4 may include a cyano group, and one may include a substituted or unsubstituted olefinic group.

6. The electrolyte according to any one of claims 1 to 5, characterized in that, The cyanosiloxane compounds include one or more of the following compounds 1 to 6:

7. The electrolyte according to any one of claims 1 to 6, characterized in that, The cyanosiloxane compound has a mass content of 0.1% to 10% in the electrolyte.

8. The electrolyte according to any one of claims 1 to 7, characterized in that, The cyanosiloxane compound has a mass content of 0.1% to 5% in the electrolyte.

9. The electrolyte according to any one of claims 1 to 8, characterized in that, The electrolyte also includes one or more of the following: cyclic carbonate electrolyte additives, cyclic sulfonyl lactone electrolyte additives, cyclic sulfate electrolyte additives, and lithium salt electrolyte additives.

10. The electrolyte according to claim 9, characterized in that, The cyclic carbonate electrolyte additives include one or more of vinylene carbonate, fluoroethylene carbonate, and ethylene ethylene carbonate; and / or, The cyclic sulfonyl lactone electrolyte additive includes one or more of 1,3-propanesulfonyl lactone and 1,3-propenesulfonyl lactone; and / or The cyclic sulfate electrolyte additives include vinyl sulfate; and / or, The lithium salt electrolyte additives include one or more of lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium tetrafluoroborate, and lithium difluorooxalate phosphate.

11. The electrolyte according to claim 9 or 10, characterized in that, The mass content of the cyclic carbonate electrolyte additive, the cyclic sulfonyl lactone electrolyte additive, the cyclic sulfate electrolyte additive, and the lithium salt electrolyte additive in the electrolyte is independently 0.1% to 20%.

12. The electrolyte according to claim 11, characterized in that, The mass content of the cyclic carbonate electrolyte additive, the cyclic sulfonyl lactone electrolyte additive, the cyclic sulfate electrolyte additive, and the lithium salt electrolyte additive in the electrolyte is independently 0.2% to 5%.

13. The electrolyte according to claim 11 or 12, characterized in that, The lithium salt electrolyte additive has a mass content of 0.5% to 2% in the electrolyte; and / or, The cyclic carbonate electrolyte additive is present in the electrolyte at a mass content of 0.2% to 1%; and / or, The cyclic sulfonyl lactone electrolyte additive has a mass content of 0.1% to 0.5% in the electrolyte; and / or, The cyclic sulfate electrolyte additive has a mass content of 0.5% to 1% in the electrolyte.

14. A single battery cell, characterized in that, Includes the electrolyte described in any one of claims 1 to 13.

15. A battery device, characterized in that, It includes multiple battery cells as described in claim 14.

16. An energy storage device, characterized in that, It includes a battery cell as described in claim 14 or a battery device as described in claim 15, wherein the battery cell or the battery device is used to store or provide electrical energy.

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