Secondary battery and electric device

Abstract

The present application relates to the technical field of batteries, and relates to a secondary battery and an electric device. The secondary battery comprises a non-aqueous electrolyte containing a cyclic sulfate compound. The present application further relates to an electric device comprising the secondary battery.

Description

Secondary battery and power-consuming device Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a secondary battery and an electrical device. Background Art

[0002] Lithium-ion secondary batteries, due to their high operating potential, long lifespan, and environmental friendliness, have become the most popular energy storage system. They are now widely used in pure electric vehicles, hybrid electric vehicles, smart grids, and other fields. However, current lithium-ion batteries struggle to meet the increasing demand for battery life. To overcome the "range anxiety" associated with electric vehicles, the development of lithium-ion batteries with higher energy density is urgently needed.

[0003] During the first charge of a battery, a solid electrolyte layer (SEI) forms on the surface of the negative electrode. SEI is a good lithium ion conductor and a poor electron conductor, inhibiting the continuation of lithium-consuming reactions and protecting the electrode. However, the formation of SEI consumes a large amount of lithium source, converting lithium into inactive lithium-containing compounds such as lithium carbonate, lithium fluoride, and alkyl lithium, resulting in the loss of cyclable lithium and reducing the battery's first cycle coulombic efficiency and battery capacity. In a battery system using a graphite negative electrode, the first charge consumes about 10% of the lithium source, and the first coulombic efficiency is about 90%. When using high-specific-capacity negative electrode materials such as alloys (silicon, tin, aluminum), oxides (silicon oxide, tin oxide, titanium oxide), and amorphous carbon negative electrodes, the consumption of lithium source is further exacerbated.

[0004] Summary of the Invention

[0005] To increase the energy density of lithium-ion batteries, one solution is to pre-supplement the positive electrode with lithium. This can be done by adding a lithium-rich metal oxide to the positive electrode as a lithium supplement. This provides an excess lithium source during the initial charge, compensating for the lithium consumption caused by SEI formation, thereby increasing the energy density of the lithium-ion battery and improving the battery's initial coulombic efficiency and cycling performance.

[0006] During the first cycle of charging of a secondary battery with a positive lithium supplement, as the lithium-rich oxide in the lithium supplement is activated, oxygen anions are activated and participate in the reaction during the delithiation process (O 2- / O - ). Oxygen on the surface of the positive electrode lithium supplement or lithium-rich positive electrode is released from the lattice position, and part of it will be oxidized to O 2 and O 2- , O 2 and O 2- It will accelerate the oxidation and decomposition of the electrolyte to generate electrolyte by-product RH + , RH +It will further reduce and consume lithium at the negative electrode and destroy the SEI film of the negative electrode, causing the electrolyte to react violently with the negative electrode, thereby deteriorating the initial efficiency and cycle performance of the battery cell.

[0007] The present application provides a secondary battery and an electric device to solve the problem of RH generated by the oxygen release and oxidation of the electrolyte during the lithium removal process of the positive electrode lithium supplement agent. + The resulting negative electrode damage and poor battery cell cycle performance are the problems.

[0008] A first aspect of the present application provides a secondary battery comprising a positive electrode plate and a non-aqueous electrolyte, wherein the non-aqueous electrolyte comprises an additive, wherein the additive comprises a cyclic sulfate compound having a structure represented by general formula (I):

[0009] Among them, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group,

[0010] R 5 and R 6 Each is independently selected from any one of a group having a structure represented by the general formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group;

[0011] The positive electrode plate includes a positive electrode material layer, the positive electrode material layer contains a lithium supplement, and the lithium supplement includes but is not limited to Li2M 1 O2、Li2M 2 O3、Li3M 3 O4、Li5M 4 O4、Li6M 5 One or more of O4, among which M 1 Including one or more of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, M 2 Including one or more of Mn, Sn, Mo, Ru, Ir, M 3 Including one or more of V, Nb, Cr, Mo, M 4 Including one or more of Fe, Cr, V, Mo, M 5 Including one or more of Co, V, Cr, Mo, and Li2M 1 O2、Li2M2 O3、Li3M 3 O4、Li5M 4 O4、Li6M 5 In O4, the valence state of each metal element except Li is lower than its own highest oxidation state.

[0012] In some embodiments, in the additive, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group and a sulfonic acid group,

[0013] R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group and a sulfonic acid group.

[0014] In some embodiments, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C3 alkyl group and a cyano group.

[0015] In some embodiments, R 5 and R 6 Each is independently selected from any one of a hydrogen atom and a C1-C3 alkyl group.

[0016] In some embodiments, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group and a cyano group.

[0017] In some embodiments, R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a methyl group, an ethyl group, a propyl group and an isopropyl group.

[0018] In some embodiments, the group represented by the general formula (II) is selected from any one of the following groups:

[0019] Wherein, X is a F atom, a Cl atom or a Br atom.

[0020] In some embodiments, the group represented by the general formula (II) is selected from any one of the following groups:

[0021] In some embodiments, the cyclic sulfate compound is selected from any one or more of the following compounds:

[0022] In some embodiments, the mass content of the cyclic sulfate compound in the non-aqueous electrolyte is W1, wherein 0.005%≤W1≤10%, optionally 0.05%≤W1≤5%.

[0023] In some embodiments, the lithium supplement includes but is not limited to Li2M 1 O2、Li5M 4 O4、Li6M 5 One or more of O4, among which M 1 Including one or more of Ni, Cu, M 4 Including one or more of Fe, Cr, V, Mo, M 5 Including one or more of Co, V, Cr, and Mo.

[0024] In some embodiments, Li2M 1 O2 is Li2Cu x Ni y O2, where x+y=1.

[0025] In some embodiments, the lithium supplement includes but is not limited to one or more of the following: Li2Cu 0.6 Ni 0.4 O2, Li2NiO2, Li5FeO4, Li6CoO4.

[0026] In some embodiments, the mass proportion of the lithium supplement in the positive electrode material layer is W2, wherein 0.1%≤W2≤10%; optionally 1%≤W2≤8%, optionally 1%≤W2≤5%.

[0027] In some embodiments, the secondary battery further includes a negative electrode plate, the negative electrode plate includes a negative electrode material layer, and the negative electrode material layer includes a negative electrode active material; the average particle size Dv50 of the negative electrode active material is 3 to 25 μm; optionally 5 μm≤Dv50≤20 μm, optionally 7 μm≤Dv50≤15 μm.

[0028] In some embodiments, the active specific surface area of ​​the positive electrode sheet is B, wherein 0<B≤20m 2 ·g -1 , optionally 2m 2 / g≤B≤10m 2 / g.

[0029] A second aspect of the present application provides an electrical device, comprising a secondary battery, wherein the secondary battery comprises any one of the secondary batteries of the first aspect.

[0030] The secondary battery provided in this application adds a cyclic sulfate compound to the electrolyte to solve the problem of oxygen release and oxidation of the electrolyte to generate RH during the lithium removal process of the positive electrode lithium supplement agent. + The resulting negative electrode damage and poor battery cell cycle performance are the problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0032] FIG1 is a schematic diagram of a secondary battery according to an embodiment of the present application.

[0033] FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 1 .

[0034] FIG3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0035] FIG4 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0036] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application.

[0037] FIG6 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.

[0038] In the drawings, the drawings are not drawn to scale.

[0039] Explanation of reference numerals: 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 secondary battery; 51 housing; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0040] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0041] Below, the embodiments of the non-aqueous electrolyte, secondary battery and electrical device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0042] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0043] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0044] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0045] Unless otherwise specified, all steps of the present 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 may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0046] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0047] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: 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).

[0048] [Secondary battery]

[0049] A first aspect of the present application provides a secondary battery, the secondary battery comprising a non-aqueous electrolyte, the non-aqueous electrolyte comprising an additive, the additive comprising a cyclic sulfate compound having a structure represented by general formula (I),

[0050] Among them, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group,

[0051] R 5 and R 6 Each is independently selected from any one of a group having a structure represented by the general formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group;

[0052] The positive electrode plate includes a positive electrode material layer, the positive electrode material layer contains a lithium supplement, and the lithium supplement includes but is not limited to Li2M 1 O2、Li2M 2 O3、Li3M 3 O4、Li5M 4 O4、Li6M 5 One or more of O4, among which M 1 Including one or more of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, M 2 Including one or more of Mn, Sn, Mo, Ru, Ir, M 3 Including one or more of V, Nb, Cr, Mo, M 4 Including one or more of Fe, Cr, V, Mo, M 5 Including one or more of Co, V, Cr, Mo, and Li2M 1 O2、Li2M 2 O3、Li3M 3 O4、Li5M 4 O4、Li6M 5 In O4, the valence state of each metal element except Li is lower than its own highest oxidation state.

[0053] Secondary batteries, also known as rechargeable batteries or storage batteries, refer to batteries that can be recharged to activate active materials and continue to be used after the battery is discharged. Typically, secondary batteries include positive electrodes, negative electrodes, separators, and electrolytes. During the battery charging and discharging process, active ions (such as lithium ions) are embedded and released back and forth between the positive electrode and the negative electrode. The separator is arranged between the positive electrode and the negative electrode, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through. The electrolyte is between the positive electrode and the negative electrode, mainly to conduct active ions.

[0054] As mentioned above, due to the presence of lithium supplement, the battery releases oxygen, which triggers the oxidation and decomposition of the electrolyte to generate the by-product RH. + On the one hand, this byproduct will further reduce and consume lithium at the negative electrode, and on the other hand, it will also destroy the SEI film on the negative electrode side, making the reaction between the negative electrode and the electrolyte more intense, causing problems such as interface black spots and local lithium precipitation. In order to solve the above problems, the present invention uses an electrolyte including a cyclic sulfate compound while adding a lithium supplement material to the positive electrode. By utilizing the film-forming properties of the cyclic sulfate compound on the positive and negative electrode sides, a flexible CEI with SO bonds is formed on the positive electrode side, which is wrapped on the surface of the lithium-rich metal oxide, reducing RH. + On the other hand, SEI with a strong inorganic structure such as lithium sulfite is generated on the negative electrode side to avoid RH +Continuous destruction of the negative electrode SEI, thereby extending the cycle life of the battery.

[0055] [Non-aqueous electrolyte]

[0056] The secondary battery of the present application includes a non-aqueous electrolyte, the non-aqueous electrolyte including an additive, the additive including a cyclic sulfate compound having a structure represented by the above general formula (I). The cyclic sulfate rings in the above general formula (I) are all five-membered rings, which can form a denser SEI film.

[0057] In the above general formula (I), R 1 、R 2 、R 3 and R 4 It can be an alkyl group or a substituent containing F or N. By introducing substituents such as alkyl groups, an elastic SEI film with a longer organic chain can be generated at the negative electrode, which can cope with the volume change of the negative electrode during the cycle and avoid the destruction of the SEI film; the introduction of substituents such as F and N can participate in the film formation at the negative electrode, generate a SEI film rich in more inorganic components such as LiF and Li3N, improve the mechanical strength of the SEI film, and then improve the stability of the negative electrode SEI film, thereby achieving the purpose of further improving the battery cycle performance.

[0058] The above-mentioned alkyl group may be a straight-chain alkyl group, a branched-chain alkyl group or a cycloalkyl group, including but not limited to methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, cyclopropyl, cyclobutane, etc.; the alkyl group in the above-mentioned haloalkyl group includes but is not limited to a straight-chain alkyl group, a branched-chain alkyl group or a cycloalkyl group, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, cyclopropyl, cyclobutane, etc.; the halogen atom may be a fluorine atom, a chlorine atom or a bromine atom, and the halogen atom replaces any one or more hydrogen atoms on the alkyl group; the above-mentioned alkoxy group includes but is not limited to a cyclopropane group, an oxetane group, etc.; the halogen atom in the haloalkoxy group may be a fluorine atom, a chlorine atom or a bromine atom, and the halogen atom replaces any one or more hydrogen atoms on the alkoxy group; the alkenyl group includes but is not limited to -CH=CH2, -CH=CH2CH3, -CH2CH=CH2, -CH2CH=CH2CH3; the ester group includes but is not limited to methyl formate, ethyl formate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, etc.

[0059] In some embodiments, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group and a sulfonic acid group,

[0060] R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group and a sulfonic acid group.

[0061] In some embodiments, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C3 alkyl group and a cyano group.

[0062] In some embodiments, R 5 and R 6 Each is independently selected from any one of a hydrogen atom and a C1-C3 alkyl group.

[0063] In some embodiments, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group and a cyano group.

[0064] In some embodiments, R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a methyl group, an ethyl group, a propyl group and an isopropyl group.

[0065] In some embodiments, the group represented by the general formula (II) is selected from any one of the following groups:

[0066] Wherein, X is a F atom, a Cl atom or a Br atom.

[0067] In some embodiments, the group represented by the general formula (II) is selected from any one of the following groups:

[0068] In some embodiments, the cyclic sulfate compound is selected from any one or more of the following compounds:

[0069] The preparation method of the cyclic sulfate compound is simpler, easier to promote and implement in industry, and has a more stable effect on improving the cycle performance of secondary batteries.

[0070] In some embodiments, R1 and R 2 are not hydrogen atoms and R 3 and R 4 Not all hydrogen atoms.

[0071] In some embodiments, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 The following conditions are met:

[0072] R 1 and R 2 At the same time, it is a hydrogen atom and R 3 and R 4 One is a hydrogen atom and the other is any one of a group having a structure represented by general formula (II), a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group, and R 5 and R 6 Not all hydrogen atoms.

[0073] In some embodiments, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 The following conditions are met:

[0074] R 3 and R 4 At the same time, it is a hydrogen atom and R 1 and R 2 One is a hydrogen atom and the other is any one of a group having a structure represented by general formula (II), a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group, and R 5 and R 6 Not all hydrogen atoms.

[0075] In some embodiments, R 5 and R 6 Each is independently selected from groups other than the structural group represented by the general formula (II).

[0076] In the present invention, the content of the cyclic sulfate ester compound in the non-aqueous electrolyte can be arbitrary. In some embodiments, the mass content of the cyclic sulfate ester compound in the non-aqueous electrolyte is W1, wherein 0.005% ≤ W1 ≤ 10%, and optionally 0.05% ≤ W1 ≤ 5%. The cyclic sulfate ester compound within the above content range significantly improves the cycling performance, and the battery cell can have better performance.

[0077] In some embodiments, W1 can be less than 0.001%, or 0.001% to 0.005%, 0.005% to 0.01%, 0.01% to 0.05%, 0.05% to 1%, 1% to 2%, 2% to 3%, 3% to 5%, 5% to 8%, 8% to 10%, 10% to 15%, or greater than 15%.

[0078] In some embodiments, the non-aqueous electrolyte used in the present invention also includes an electrolyte. As long as it is an electrolyte that can be generally used in non-aqueous electrolytes, it can be considered for application to the non-aqueous electrolyte of the present application. Those skilled in the art can make a selection based on the battery system in which the non-aqueous electrolyte is applied, such as selecting a conventional electrolyte suitable for secondary batteries. In some embodiments, the electrolyte includes an alkali metal salt electrolyte; optionally, the electrolyte includes a lithium salt; optionally, the lithium salt includes one or more selected from the group consisting of lithium hexafluorophosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide. Each of the above lithium salts can be used alone or in combination of two or more.

[0079] The content of electrolyte in the non-aqueous electrolyte can refer to the electrolyte content in conventional non-aqueous electrolyte. In some embodiments, the electrolyte content in the non-aqueous electrolyte is 0.1 mol / L-5 mol / L, for example, 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 4 mol / L or 5 mol / L.

[0080] In some embodiments, the non-aqueous electrolyte further comprises a non-aqueous solvent. Optionally, the non-aqueous solvent comprises any one or more selected from the group consisting of cyclic carbonates, chain carbonates, nitrile solvents, ketone solvents and sulfone solvents; further optionally, the non-aqueous solvent comprises one or more selected from the group consisting of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone, diethyl sulfone, tetrahydrofuran, ethylene glycol dimethyl ether, dioxolane, acetone, acetonitrile and butyronitrile. The above non-aqueous solvents can be used alone or in combination of two or more. For example, in order to improve the load characteristics and low-temperature characteristics of the secondary battery, a mixed solvent of cyclic carbonate and chain carbonate can be used. In some embodiments, EC+EMC (ethylene carbonate+ethyl methyl carbonate) is used as the non-aqueous solvent.

[0081] When the non-aqueous electrolyte of the present application is applied to a solid battery, a solid solvent such as dimethyl sulfone may be used.

[0082] In addition to the aforementioned additives, the additives may also include negative electrode film-forming additives, positive electrode film-forming additives, and additives capable of improving certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc. In some embodiments, the aforementioned additives further include, but are not limited to, one or more selected from the group consisting of sulfate compounds, sulfite compounds, sultone compounds, disulfonic acid compounds, nitrile compounds, aromatic compounds, isocyanate compounds, phosphazene compounds, cyclic acid anhydride compounds, phosphite compounds, phosphate compounds, borate compounds, and carboxylate compounds.

[0083] [Method for preparing a cyclic sulfate compound having a structure represented by general formula (I)]

[0084] The preparation method of the cyclic sulfate compound having the structure shown in the general formula (I) of the present application refers to the following synthetic route:

[0085] The reaction temperature of the first step is controlled at 30-60° C.; the reaction temperature of the second step is controlled at 10-30° C. The second step is catalyzed by a catalyst such as ruthenium trichloride trihydrate, and the oxidant can be sodium hypochlorite, ozone, etc.

[0086] [Positive electrode]

[0087] In order to improve the energy density of lithium-ion batteries, the present invention adds lithium-rich metal oxides to the positive electrode material layer of the positive electrode plate as a lithium supplement. The lithium-rich metal oxides that can be used as lithium supplements include but are not limited to the Li2M 1 O2、Li2M 2 O3、Li3M 3 O4、Li5M 4 O4、Li6M 5 One or more of O4.

[0088] In some embodiments, the lithium supplement includes but is not limited to Li2M 1 O2、Li5M 4 O4、Li6M 5 One or more of O4, among which M 1 Including one or more of Ni, Cu, M 4 Including one or more of Fe, Cr, V, Mo, M 5 Including one or more of Co, V, Cr, and Mo.

[0089] In some embodiments, Li2M 1 O2 is Li2Cu x Ni y O2, wherein x + y = 1. In some embodiments, x is 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1. In some embodiments, y is 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

[0090] In some embodiments, the lithium supplement includes but is not limited to one or more of the following: Li2Cu 0.6 Ni 0.4 O2, Li2CuO2, Li2NiO2, Li5FeO4, Li6CoO4. The above lithium supplements combined with an appropriate amount of cyclic sulfate compounds can better improve the capacity and cycle performance of lithium-ion batteries.

[0091] In some embodiments, the lithium supplement agent accounts for a mass percentage of W2 in the positive electrode material layer, wherein 0.1% ≤ W2 ≤ 10%, optionally 1% ≤ W2 ≤ 8%, and optionally 1% ≤ W2 ≤ 5%. When the lithium supplement agent accounts for a mass percentage within the above preferred range, the battery cell can exhibit excellent performance in capacity testing and cycling.

[0092] In some embodiments, W2 can be less than 0.05%, or 0.05% to 0.1%, 0.1% to 0.2%, 0.2% to 1%, 1% to 2%, 2% to 3%, 3% to 5%, 5% to 6%, 6% to 8%, 8% to 9%, 9% to 10%, 10% to 15% or greater than 15%.

[0093] The active specific surface area of ​​the positive electrode can characterize the number of active sites on the positive electrode that participate in the reaction during the charge and discharge process. In some embodiments, the active specific surface area of ​​the positive electrode is B, where 0 < B ≤ 20m 2 / g, optionally 2m 2 / g≤B≤10m 2 When the active specific surface area of ​​the positive electrode sheet is within the above preferred range, the oxidation capacity of the positive electrode sheet to the electrolyte can be reduced, the gas production in the first cycle can be reduced, and the RH can be reduced. + It is generated in the electrolyte, thereby improving the black spots on the negative electrode interface and the local lithium deposition problems of the negative electrode. At the same time, it will not significantly increase the polarization of the electrode, and thus can improve the energy density and performance of the battery under the condition of good battery dynamics.

[0094] In some embodiments, the active surface area of ​​the positive electrode sheet can be less than 1 m 2 / g, or 1m 2 / g~2m 2 / g, 2m 2 / g~4m 2 / g、4m 2 / g~8m 2 / g、8m 2 / g~10m 2 / g、10m 2 / g~15m 2 / g、15m 2 / g~20m 2 / g, 20m 2 / g~30m 2 / g or greater than 30m 2 / g.

[0095] The active specific surface area B of the positive electrode sheet can be obtained by the following test method, which includes the following steps:

[0096] A positive electrode plate to be tested, a negative electrode plate, and an electrolyte are assembled into a button half-cell, wherein the electrolyte contains an electrochemical redox probe molecule with a concentration of c, the redox potential of the probe molecule is 2V to 4V, and the probe molecule is dissolved in the electrolyte; a series of linear sweep voltammetry curves of different button half-cells at different scan rates V are measured using an electrochemical workstation to obtain an oxidation peak current ip (oxidation) and a reduction peak current ip (reduction); then, the obtained peak current ip of the series of button half-cells is plotted against the square root of the scan rate V to obtain a slope K; according to the Randles-Sevick equation, ip = 2.69*105*n 2 / 3 cD 1 / 2 AV 1 / 2 , where ip is the peak current, n is the number of electron transfers, D is the diffusion coefficient, and D(oxidation) = 1.41*10 6 cm 2 / s, D(reduction)=1.26*10 6 cm 2 / s, V is the scan rate, A is the active surface area of ​​the positive electrode, and c is the concentration of the probe molecules. The active surface area A of the positive electrode divided by the weight m of the positive electrode is the active specific surface area B of the positive electrode.

[0097] In the above test method, the negative electrode is a lithium metal sheet with a thickness of 0.4mm. The electrolyte is a common electrolyte, which is a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 1:1:1. Then, fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent at a ratio of 1 mol / L.

[0098] In the above test method, the probe molecule is preferably ferrocene, and the redox potential of the probe molecule is 2 V to 4 V. The concentration of the probe molecule is 0.05 mol / L.

[0099] The above method measures the cyclic voltammetry curve of a ferrocene solution at different scan rates on the surface of the active material to obtain the peak currents of the oxidation and reduction peaks. The slope is obtained by fitting the current i and the scan rate V, thereby calculating the reactive specific surface area of ​​the electrode. This method uses iron ions as the indicator element and the oxidation / reduction sites of iron ions on the electrode surface as the electrode active sites. Based on the Randles-Sevick equation and the cyclic voltammetry curve, a linear relationship is established to calculate the active reaction area.

[0100] In the above test method, the scanning rate is 0.01mV / s~3.50mV / s, the scanning voltage range is 2.9V~3.5V, D(oxidation)=1.41×10 6 cm 2 / s, D(reduction)=1.26×10 6 cm 2 / s.

[0101] The positive electrode sheet generally includes a positive electrode current collector and a positive electrode material layer disposed on at least one surface of the positive electrode current collector.

[0102] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode material layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0103] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum 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.).

[0104] In some embodiments, the positive electrode active material may adopt the positive electrode active material for batteries that is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0105] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0106] In some embodiments, the positive electrode film layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0107] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0108] [Negative electrode]

[0109] The secondary battery of the present invention may further include a negative electrode sheet, wherein the negative electrode sheet includes a negative electrode material layer, and the negative electrode material layer includes a negative electrode active material.

[0110] The particle size of the negative electrode active material can be represented by Dv50, which refers to the particle size corresponding to the cumulative volume percentage reaching 50%, that is, the median particle size of the volume distribution. In some embodiments, the average particle size Dv50 of the negative electrode active material is 3 to 25 μm, optionally 5 μm ≤ Dv50 ≤ 20 μm, and optionally 7 μm ≤ Dv50 ≤ 15 μm. When the negative electrode active material Dv50 is within the above preferred range, it is beneficial to form a uniform surface during coating and preparation of the electrode sheet, while also reducing side reactions on the negative electrode side of the battery, reducing repeated damage to the SEI, reducing lithium consumption, reducing battery capacity loss, maintaining cycle life, and enabling the battery to achieve better performance.

[0111] In some embodiments, Dv50 can be less than 3 μm, or 3 μm to 5 μm, 5 μm to 6 μm, 6 μm to 7 μm, 7 μm to 8 μm, 8 μm to 10 μm, 10 μm to 15 μm, 15 μm to 20 μm, 20 μm to 25 μm, 25 μm to 28 μm, or greater than 28 μm.

[0112] Dv50 can be measured using instruments and methods known in the art. For example, a Malvern Mastersizer 3000 laser diffraction particle size distribution analyzer (available from Malvern Instruments Ltd., UK) is used to measure the particle size distribution according to the particle size distribution laser diffraction method GB / T 19077-2016 to obtain Dv50.

[0113] The negative electrode sheet may include a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode material layer includes a negative electrode active material.

[0114] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0115] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0116] In some embodiments, the negative electrode active material may adopt the negative electrode active material for batteries known in the art. As an example, the negative electrode active material may include at least one of the following materials: graphite (such as artificial graphite, natural graphite), soft carbon, hard carbon, silicon-based materials, tin-based materials and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites and silicon alloys. The tin-based material can be selected from at least one of elemental tin, tin oxides and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0117] In some embodiments, the negative electrode film layer may further include a binder. For example, the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0118] In some embodiments, the negative electrode film layer may further include a conductive agent. For example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0119] In some embodiments, the negative electrode film layer may optionally further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0120] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0121] [Isolation film]

[0122] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0123] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0124] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0125] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0126] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the secondary battery can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0127] The present application has no particular limitation on the shape of the secondary battery, which may be cylindrical, square, or any other shape. For example, FIG1 shows a secondary battery 5 with a square structure as an example.

[0128] In some embodiments, referring to Figure 2, the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0129] In some embodiments, secondary batteries can be assembled into a battery module. The number of secondary batteries contained in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0130] Figure 3 shows an example battery module 4. Referring to Figure 3 , within the battery module 4, multiple secondary batteries 5 may be arranged sequentially along the length of the battery module 4. Of course, any other arrangement is also possible. Furthermore, the multiple secondary batteries 5 may be secured together using fasteners.

[0131] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.

[0132] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0133] Figures 4 and 5 illustrate an example battery pack 1. Referring to Figures 4 and 5 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be placed over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0134] In addition, the present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application. The secondary battery, battery module, or battery pack can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.

[0135] As the electrical device, a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.

[0136] Figure 6 shows an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery, a battery pack or battery module can be used.

[0137] [Example]

[0138] Below, the embodiment of the application is described. The embodiment described below is exemplary, is only used to explain the application, and is not to be construed as limiting the application. Where specific techniques or conditions are not indicated in the embodiment, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not indicate the manufacturer are conventional products that can be obtained commercially. The remaining reagents or compound information are recorded in Table 1.

[0139] Table 1

[0140] Synthesis example

[0141] The preparation method of the cyclic sulfate compound having the structure shown in the general formula (I) of the present application refers to the following synthetic route:

[0142] The reaction temperature of the first step is controlled at 30-60° C.; the reaction temperature of the second step is controlled at 10-30° C. The second step is catalyzed by a catalyst such as ruthenium trichloride trihydrate, and the oxidant can be sodium hypochlorite, ozone, etc.

[0143] Synthesis Example 1: Compound 1 Synthesis

[0144] Step 1: Add 300g (2mol) of solid 1,6-dideoxygalactitol to a 5L three-necked flask, start stirring, and add 523g (4.4mol) of thionyl chloride dropwise to the three-necked flask. Control the temperature at about 15°C during the addition process. After the addition is completed, keep the reaction at 45°C for 4 hours. A large amount of pasty solid precipitates from the reaction solution. After cooling, slowly add 1L of deionized water dropwise, and quickly stir to break up the reaction system. The filtered solid is slurried and washed with deionized water several times until the pH is neutral. The filter cake is dried under reduced pressure at 60°C to obtain intermediate product 1.

[0145] Step 2: To a 3L three-necked flask, 184.2g (0.8mol) of intermediate 1 was added, 1000mL of acetonitrile was added, and 80mg of ruthenium trichloride trihydrate catalyst was added. After nitrogen displacement of the system, the system was cooled to 20°C, stirring was started, and 2000g of 20% sodium hypochlorite aqueous solution was added dropwise within 1h, and the reaction temperature was controlled at 10-20°C. After the addition was complete, the mixture was stirred at 10-20°C for 10min, separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch potassium iodide test paper did not turn blue. The liquid was separated again, the organic layer was concentrated, and crystallized from acetonitrile to obtain a white powder solid, which was the above-mentioned compound 1. 1H-NMR, CD3CN, δppm 5.42-5.39 (m, 2H), 5.36-5.34 (m, 2H), 1.67-1.65 (d, 6H).

[0146] Synthesis Example 2: Compound 2 Synthesis

[0147] Step 1: Add 356.5g (2mol) of solid 3,4,5,6-octanetrol to a 5L three-necked flask and start stirring. Add 523g (4.4mol) of thionyl chloride dropwise to the three-necked flask. Control the temperature at about 15°C during the addition. After the addition is completed, keep the reaction at 45°C for 4 hours. A large amount of pasty solid precipitates from the reaction solution. After cooling, slowly add 1L of deionized water dropwise, stir the reaction system rapidly to break it up, and wash the filtered solid with deionized water several times to a neutral pH. Dry the filter cake at 60°C under reduced pressure to obtain intermediate product 2.

[0148] Step 2: 216.2 g (0.8 mol) of intermediate product 2 was added to a 3L three-necked flask, 1000 mL of acetonitrile was added, 80 mg of ruthenium trichloride trihydrate catalyst was added, and after nitrogen replacement of the system, the system was cooled to 20 ° C, stirring was started, and 2000 g of 20% sodium hypochlorite aqueous solution was added dropwise within 1 h, and the reaction temperature was controlled at 10-20 ° C; after the addition was completed, stirred at 10-20 ° C for 10 min, separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch potassium iodide test paper did not turn blue; the liquid was separated again, the organic layer was concentrated, and acetonitrile was crystallized to obtain compound 2.

[0149] Synthesis Example 3: Compound 3 Synthesis

[0150] Step 1: Add 328.4 g (2 mol) of solid 2,3,4,5-heptetrol to a 5 L three-necked flask and start stirring. Add 523 g (4.4 mol) of thionyl chloride dropwise to the three-necked flask. Control the temperature at about 15°C during the addition. After the addition is complete, keep the reaction at 45°C for 4 hours. A large amount of pasty solid precipitates from the reaction solution. After cooling, slowly add 1 L of deionized water dropwise, stir the reaction system rapidly to break it up, and wash the filtered solid with deionized water several times until the pH is neutral. Dry the filter cake at 60°C under reduced pressure to obtain intermediate product 3.

[0151] Step 2: 205 g (0.8 mol) of intermediate 3 was added to a 3L three-necked flask, 1000 mL of acetonitrile was added, and the mixture was stirred until the solid was completely dissolved. 80 mg of ruthenium trichloride trihydrate catalyst was added. After nitrogen displacement of the system, the system was cooled to 20 ° C. and stirring was started. 2000 g of 20% sodium hypochlorite aqueous solution was added dropwise within 1 h, and the reaction temperature was controlled at 10-20 ° C. After the addition was complete, the mixture was stirred at 10-20 ° C for 10 min, separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch potassium iodide test paper did not turn blue; the liquid was separated again, the organic layer was concentrated, and the acetonitrile crystals were obtained to obtain compound 3 (163.1 g, yield 82.8%).

[0152] In addition, the synthesis methods of the following compounds refer to Synthesis Example 1, using the corresponding substrates in Table 2 to replace 1,6-dideoxygalactitol.

[0153] Table 2

[0154] Synthesis Example 4: Compound 5 Synthesis

[0155] Step 1: Add 392.4 g (2 mol) of solid 1,2,3,4,5,6-heptanhexaol to a 5 L three-necked flask and start stirring. Add 784.5 g (6.6 mol) of thionyl chloride dropwise to the three-necked flask. Control the temperature at about 15°C during the addition. After the addition is completed, keep the reaction at 45°C for 4 hours. A large amount of pasty solid precipitates from the reaction solution. After cooling, slowly add 1 L of deionized water dropwise, stir the reaction system rapidly to break it up, and wash the filtered solid with deionized water several times to neutral pH. Dry the filter cake at 60°C under reduced pressure to obtain intermediate product 4.

[0156] Step 2: 140 g (0.4 mol) of intermediate product 4 was added to a 4L three-necked flask, 1000 mL of acetonitrile was added, 110 mg of ruthenium trichloride trihydrate catalyst was added, and after nitrogen replacement of the system, the system was cooled to 20 ° C, stirring was started, and 1500 g of 20% sodium hypochlorite aqueous solution was added dropwise within 1 h, and the reaction temperature was controlled at 10-20 ° C; after the addition was complete, the mixture was stirred at 10-20 ° C for 10 min, separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch potassium iodide test paper did not turn blue; the liquid was separated again, the organic layer was concentrated, and the acetonitrile crystals were obtained to obtain compound 5.

[0157] In addition, the synthesis methods of the following compounds refer to Synthesis Example 4, using the corresponding substrates in Table 3 to replace 1,2,3,4,5,6-heptanhexaol.

[0158] Table 3

[0159] Synthesis Example 5: Compound 7 Synthesis

[0160] Step 1: 484 g (2 mol) of solid octitol was added to a 5 L three-necked flask, stirring was started, and 1046 g (8.8 mol) of thionyl chloride was added dropwise to the three-necked flask. The temperature was controlled at about 15 ° C during the addition process. After the addition was completed, the reaction was kept at 45 ° C for 4 hours. A large amount of pasty solid precipitated from the reaction solution. After cooling, 1 L of deionized water was slowly added dropwise, and the reaction system was quickly stirred to break up. The filtered solid was washed with deionized water several times until the pH was neutral. The filter cake was dried under reduced pressure at 60 ° C to obtain intermediate product 5.

[0161] Step 2: 183.2 g (0.4 mol) of intermediate product 5 was added to a 4L three-necked flask, 1000 mL of acetonitrile was added, 150 mg of ruthenium trichloride trihydrate catalyst was added, and after nitrogen replacement of the system, the system was cooled to 20 ° C, stirring was started, and 2000 g of 20% sodium hypochlorite aqueous solution was added dropwise within 1 h, and the reaction temperature was controlled at 10-20 ° C; after the addition was complete, stirred at 10-20 ° C for 10 min, separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch potassium iodide test paper did not turn blue; the liquid was separated again, the organic layer was concentrated, and acetonitrile was crystallized to obtain compound 7.

[0162] Example 1

[0163] Electrolyte composition: Compound 1 is used as an additive, and its mass content in the electrolyte is 2%; LiPF6 is used as an electrolyte, and its content in the electrolyte is 10%; a mixture of EC+EMC (ethylene carbonate+ethyl methyl carbonate) with a volume ratio of 3:7 is used as a solvent.

[0164] Positive electrode preparation:

[0165] Positive electrode active material lithium iron phosphate (LiFePO4), lithium supplement (Li2Cu 0.6 Ni 0.4 O2), conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) are dissolved in solvent N-methylpyrrolidone (NMP) in a weight ratio of 95:2:2:1, and stirred thoroughly to obtain positive electrode slurry; the positive electrode slurry is then evenly coated on the positive electrode collector, and then dried, cold pressed, and cut to obtain the positive electrode sheet. The lithium supplement accounts for 2% by weight in the positive electrode sheet (excluding the current collector). The active specific surface area of ​​the positive electrode sheet is 8m 2 / g.

[0166] Determination of active specific surface area of ​​positive electrode:

[0167] The active specific surface area of ​​the positive electrode can accurately characterize the number of active sites on the positive electrode that participate in the reaction during the charge and discharge process.

[0168] The active specific surface area B of the positive electrode sheet can be obtained by the following test method, which includes the following steps:

[0169] A positive electrode plate to be tested, a negative electrode plate, and an electrolyte are assembled into a button half-cell, wherein the electrolyte contains an electrochemical redox probe molecule with a concentration of c, the redox potential of the probe molecule is 2V to 4V, and the probe molecule is dissolved in the electrolyte; a series of linear sweep voltammetry curves of different button half-cells at different scan rates V are measured using an electrochemical workstation to obtain an oxidation peak current ip (oxidation) and a reduction peak current ip (reduction); then, the obtained peak current ip of the series of button half-cells is plotted against the square root of the scan rate V to obtain a slope K; according to the Randles-Sevick equation, ip = 2.69*105*n 2 / 3 cD 1 / 2 AV 1 / 2 , where ip is the peak current, n is the number of electron transfers, D is the diffusion coefficient, and D(oxidation) = 1.41*10 6 cm 2 / s, D(reduction)=1.26*10 6 cm 2 / s, V is the scan rate, A is the active surface area of ​​the positive electrode, and c is the concentration of the probe molecules. The active surface area A of the positive electrode divided by the weight m of the positive electrode is the active specific surface area B of the positive electrode.

[0170] In the above test method, the negative electrode is a lithium metal sheet with a thickness of 0.4mm. The electrolyte is a common electrolyte, which is a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 1:1:1. Then, fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent at a ratio of 1 mol / L.

[0171] In the above test method, the probe molecule is ferrocene, the redox potential of the probe molecule is 2 V to 4 V, and the concentration of the probe molecule is 0.05 mol / L.

[0172] The above method measures the cyclic voltammetry curve of a ferrocene solution at different scan rates on the surface of the active material to obtain the peak currents of the oxidation and reduction peaks. The slope is obtained by fitting the current i and the scan rate V, thereby calculating the reactive specific surface area of ​​the electrode. This method uses iron ions as the indicator element and the oxidation / reduction sites of iron ions on the electrode surface as the electrode active sites. Based on the Randles-Sevick equation and the cyclic voltammetry curve, a linear relationship is established to calculate the active reaction area.

[0173] In the above test method, the scanning rate is 0.01mV / s~3.50mV / s, the scanning voltage range is 2.9V~3.5V, D(oxidation)=1.41×10 6 cm 2 / s, D(reduction)=1.26×10 6 cm 2 / s.

[0174] Negative electrode preparation:

[0175] Anode active material graphite (average particle size Dv50 of 10 μm), conductive agent carbon black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) are dissolved in deionized water at a weight ratio of 90:4:4:2 and mixed thoroughly to prepare anode slurry. The slurry is then evenly coated onto anode current collector copper foil once or multiple times. The negative electrode sheets are then dried, cold-pressed, and slit. The Dv50 of the negative electrode active material refers to the particle size corresponding to 50% of the cumulative volume of the negative electrode active material, i.e., the median particle size in the volume distribution, expressed in μm. Dv50 can be measured using instruments and methods known in the art. For example, a laser diffraction particle size distribution analyzer (Malvern Mastersizer 3000, available from Malvern Instruments Ltd., UK) is used to measure the particle size distribution according to the particle size distribution laser diffraction method (GB / T 19077-2016).

[0176] Diaphragm:

[0177] Conventional polypropylene film is used as the separator.

[0178] Lithium-ion battery assembly:

[0179] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive and negative electrode sheets to serve as an isolation, and then wound to obtain an electrode assembly; the electrode assembly is placed in a battery casing, dried, and then injected with electrolyte, and then undergoes formation, static and other processes to produce a lithium-ion battery.

[0180] Example 2-1

[0181] Compound 2 was used to replace compound 1, and the rest was the same as in Example 1.

[0182] Example 2-2

[0183] Compound 3 was used to replace compound 1, and the rest was the same as in Example 1.

[0184] Example 2-3

[0185] Compound 4 was used to replace compound 1, and the rest was the same as in Example 1.

[0186] Examples 2-4

[0187] Compound 5 was used to replace compound 1, and the rest was the same as in Example 1.

[0188] Examples 2-5

[0189] Compound 6 was used to replace compound 1, and the rest was the same as in Example 1.

[0190] Examples 2-6

[0191] Compound 7 was used to replace compound 1, and the rest was the same as in Example 1.

[0192] Examples 2-7

[0193] Compound 8 was used to replace compound 1, and the rest was the same as in Example 1.

[0194] Examples 2-8

[0195] Compound 9 was used to replace compound 1, and the rest was the same as in Example 1.

[0196] Example 3-1

[0197] The mass content of compound 1 was adjusted to 0.001%, and the rest was the same as in Example 1.

[0198] Example 3-2

[0199] The mass content of compound 1 was adjusted to 0.01%, and the rest was the same as in Example 1.

[0200] Example 3-3

[0201] The mass content of compound 1 was adjusted to 3%, and the rest was the same as in Example 1.

[0202] Examples 3-4

[0203] The mass content of compound 1 was adjusted to 8%, and the rest was the same as in Example 1.

[0204] Examples 3-5

[0205] The mass content of compound 1 was adjusted to 15%, and the rest was the same as in Example 1.

[0206] Example 4-1

[0207] Use lithium supplement Li2NiO2 to replace lithium supplement Li2Cu 0.6 Ni 0.4 O2, and the rest is the same as in Example 1.

[0208] Example 4-2

[0209] Use lithium supplement Li2CuO2 to replace lithium supplement Li2Cu 0.6 Ni 0.4 O2, and the rest is the same as in Example 1.

[0210] Example 4-3

[0211] The lithium supplement Li5FeO4 with a mass content of 1.5% is used to replace the lithium supplement Li2Cu with a mass content of 2%. 0.6 Ni 0.4 O2, the mass content of the positive electrode active material is adjusted to 95.5%, and the rest is the same as in Example 1.

[0212] Example 4-4

[0213] The lithium supplement Li6CoO4 with a mass content of 1% is used to replace the lithium supplement Li2Cu with a mass content of 2%. 0.6 Ni 0.4 O2, the mass content of the positive electrode active material is adjusted to 96%, and the rest is the same as in Example 1.

[0214] Example 5-1

[0215] The mass proportion of the lithium supplement agent in the positive electrode sheet (excluding the current collector) is adjusted to 0.05%, and the rest is the same as in Example 1.

[0216] Example 5-2

[0217] The mass proportion of the lithium supplement agent in the positive electrode sheet (excluding the current collector) is adjusted to 0.2%, and the rest is the same as in Example 1.

[0218] Example 5-3

[0219] The mass proportion of the lithium supplement agent in the positive electrode sheet (excluding the current collector) is adjusted to 3%, and the rest is the same as in Example 1.

[0220] Example 5-4

[0221] The mass proportion of the lithium supplement agent in the positive electrode sheet (excluding the current collector) is adjusted to 6%, and the rest is the same as in Example 1.

[0222] Example 5-5

[0223] The mass proportion of the lithium supplement agent in the positive electrode sheet (excluding the current collector) is adjusted to 9%, and the rest is the same as in Example 1.

[0224] Examples 5-6

[0225] The mass proportion of the lithium supplement agent in the positive electrode sheet (excluding the current collector) is adjusted to 15%, and the rest is the same as in Example 1.

[0226] Example 6-1

[0227] The average particle size Dv50 of the negative electrode active material was adjusted to 3 μm, and the rest was the same as in Example 1.

[0228] Example 6-2

[0229] The average particle size Dv50 of the negative electrode active material was adjusted to 6 μm, and the rest was the same as in Example 1.

[0230] Example 6-3

[0231] The average particle size Dv50 of the negative electrode active material was adjusted to 8 μm, and the rest was the same as in Example 1.

[0232] Example 6-4

[0233] The average particle size Dv50 of the negative electrode active material was adjusted to 15 μm, and the rest was the same as in Example 1.

[0234] Example 6-5

[0235] The average particle size Dv50 of the negative electrode active material was adjusted to 20 μm, and the rest was the same as in Example 1.

[0236] Example 6-6

[0237] The average particle size Dv50 of the negative electrode active material was adjusted to 25 μm, and the rest was the same as in Example 1.

[0238] Examples 6-7

[0239] The average particle size Dv50 of the negative electrode active material was adjusted to 28 μm, and the rest was the same as in Example 1.

[0240] Examples 6-8

[0241] The average particle size Dv50 of the negative electrode active material was adjusted to 2.5, and the rest was the same as in Example 1.

[0242] Example 7-1

[0243] The active surface area of ​​the positive electrode is adjusted to 1m 2 / g, and the rest is the same as in Example 1.

[0244] Example 7-2

[0245] The active surface area of ​​the positive electrode is adjusted to 4m 2 / g, and the rest is the same as in Example 1.

[0246] Example 7-3

[0247] The active surface area of ​​the positive electrode is adjusted to 15m 2 / g, and the rest is the same as in Example 1.

[0248] Example 7-4

[0249] The active surface area of ​​the positive electrode is adjusted to 30m 2 / g, and the rest is the same as in Example 1.

[0250] Comparative Example 1-1

[0251] The other steps were the same as in Example 1 except that Compound 1 was not added.

[0252] Performance testing:

[0253] 1) Lithium-ion battery capacity test

[0254] At 25°C, charge the lithium-ion battery at a constant current of 0.33C to 4.2V, then charge it at a constant voltage of 4.2V to a current of ≤0.05C, and then discharge it at a constant current of 0.33C to 2.5V. Record its actual capacity as C0 (mAh). The gram capacity of a lithium-ion battery is C0 / W3 (mAh / g), where W3 is the mass of the positive electrode active material (g).

[0255] 2) 60℃ cycle performance test

[0256] At 60°C, charge the lithium-ion battery at a constant current of 1C to a voltage of 3.65V. Then, charge it at a constant voltage of 3.65V to a current of ≤0.05C. Then, discharge the battery at a constant current of 1C to a voltage of 2.5V. This is one charge and discharge process. The discharge capacity at this time is recorded as the discharge capacity of the battery's first cycle. Repeat the charge and discharge cycles in this way, and calculate the number of cycles corresponding to the battery's capacity retention rate of 80%.

[0257] The capacity retention rate (%) of the battery after N cycles at 60° C. = (discharge capacity of the battery at the Nth cycle / discharge capacity of the battery at the first cycle)×100%.

[0258] The results are recorded in Table 4.

[0259] Table 4

[0260] By introducing positive electrode lithium replenisher into lithium iron phosphate, the consumption of lithium by the formation of SEI film between positive and negative electrodes can be effectively compensated, thus improving the specific capacity of lithium-ion batteries. However, positive electrode lithium replenisher will generate oxygen free radicals during the delithiation process, which will further generate oxygen, O2 - and O2 will also oxidize the electrolyte to produce byproduct RH + On the one hand, this byproduct will further reduce and consume lithium at the negative electrode, and on the other hand, it will also damage the SEI film on the negative electrode side, exacerbating the reaction between the negative electrode and the electrolyte, causing problems such as interface black spots and local lithium precipitation, thereby deteriorating the initial efficiency and cycle performance of the battery cell. From the results of Examples 1 and 2-1 to 2-8 and Comparative Example 1-1, it can be seen that cyclic sulfate compounds can form films on the positive and negative electrode sides, reducing the problem of increased lithium consumption caused by byproduct reduction or damage to the SEI film at the negative electrode, thereby improving a series of problems such as abnormal battery capacity and poor cycle performance.

[0261] The results of Examples 3-1 to 3-5 show that too little cyclic sulfate compound does not significantly improve performance, while too much may thicken the films formed on the positive and negative electrodes, increasing the polarization of the battery cell, which, to a certain extent, affects capacity and worsens cycling performance at high temperatures. When the mass percentage of the cyclic sulfonate additive used in this application in the electrolyte is within the preferred range, the battery cell can achieve better performance.

[0262] It can be seen from the results of Examples 4-1 to 4-4 that by introducing an appropriate amount of other positive electrode lithium supplements into lithium iron phosphate, such as Li2CuO2, Li2NiO2, Li5FeO4, Li6CoO4, etc., and at the same time adding an appropriate amount of cyclic sulfate compounds, the capacity and cycle performance of lithium-ion batteries can be improved.

[0263] The results of Examples 5-1 to 5-6 show that when the positive electrode lithium replenisher is too little, the improvement in battery cell capacity and cycle performance is limited. When the positive electrode lithium replenisher is too much, the positive electrode releases oxygen severely, producing a large amount of electrolyte byproducts that undermine the stability of the battery, resulting in poor performance. When the proportion of the positive electrode lithium replenisher in the present application is within the above preferred range, the battery cell can demonstrate excellent performance in capacity testing and cycling.

[0264] The results of Examples 6-1 to 6-8 show that when the Dv50 of the negative electrode active material is too low, resulting in an excessively large specific surface area, the electrode may experience increased contact with the electrolyte, leading to more intense side reactions and accumulation of byproducts on the electrode surface, increasing the negative electrode impedance and, consequently, increasing capacity loss during high-temperature cycling. Therefore, when the Dv50 of the negative electrode active material is within the preferred range, the battery can achieve better performance.

[0265] The results of Examples 7-1 to 7-4 show that reducing the active surface area of ​​the positive electrode may increase electrode polarization, which is not conducive to capacity utilization. However, an excessively large active surface area of ​​the positive electrode increases the ability of the positive electrode to oxidize the electrolyte, thereby deteriorating the battery cell's cycling performance and affecting capacity utilization. Therefore, when the active surface area of ​​the positive electrode is within the preferred range, the energy density and performance of the battery can be improved while maintaining good battery kinetics.

[0266] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A secondary battery comprising a positive electrode and a non-aqueous electrolyte, in, The non-aqueous electrolyte includes an additive, wherein the additive includes a cyclic sulfate ester compound having a structure represented by general formula (I), Among them, R 1 , R 2 , R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group, R 5 and R 6 Each is independently selected from any one of a group having a structure represented by the general formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group; The positive electrode plate includes a positive electrode material layer, and the positive electrode material layer contains a lithium supplement, and the lithium supplement includes but is not limited to Li 2 M 1 O 2 , Li 2 M 2 O 3 , Li 3 M 3 O 4 , Li 5 M 4 O 4 , Li 6 M 5 O 4 One or more of the following, where M 1 Including one or more of Ni, Co, Fe, Mn, Zn, Mg, Ca, Cu, M 2 Including one or more of Mn, Sn, Mo, Ru, Ir, M 3 Including one or more of V, Nb, Cr, Mo, M 4 Including one or more of Fe, Cr, V, Mo, M 5 Including one or more of Co, V, Cr, Mo, and Li 2 M 1 O 2 , Li 2 M 2 O 3 , Li 3 M 3 O 4 , Li 5 M 4 O 4 , Li 6 M 5 O 4 In the ion exchange reaction, the valence state of each metal element except Li is lower than its own highest oxidation state.

2. The secondary battery according to claim 1, wherein the additive comprises: 1 , R 2 , R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group and a sulfonic acid group, R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group and a sulfonic acid group; Optionally, R 1 , R 2 , R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C3 alkyl group and a cyano group; Optionally, R 5 and R 6 Each is independently selected from any one of a hydrogen atom and a C1-C3 alkyl group; Optionally, R 1 , R 2 , R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group and a cyano group; Optionally, R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a methyl group, an ethyl group, a propyl group and an isopropyl group; Optionally, the group of the structure represented by the general formula (II) is selected from any one of the following groups: in, X is a F atom, a Cl atom or a Br atom; Optionally, the group of the structure represented by the general formula (II) is selected from any one of the following groups:

3. The secondary battery according to claim 1 or 2, wherein in the additive, the cyclic sulfate ester compound is selected from any one or more of the following compounds: 4 . The secondary battery according to claim 1 , wherein the mass content of the cyclic sulfate ester compound in the non-aqueous electrolyte is W1, wherein 0.005%≤W1≤10%, optionally 0.05%≤W1≤5%.

5. The secondary battery according to any one of claims 1 to 4, wherein the lithium supplement includes but is not limited to Li 2 M 1 O 2 , Li 5 M 4 O 4 , Li 6 M 5 O 4 One or more of in, M 1 Including one or more of Ni and Cu, M 4 Including one or more of Fe, Cr, V, Mo, M 5 Including one or more of Co, V, Cr, Mo, Optionally, Li 2 M 1 O 2 For Li 2 Cu x Ni y O 2 , where x+y=1; Optionally, the lithium supplement includes but is not limited to one or more of the following: Li 2 Cu 0.6 Ni 0.4 O 2 , Li 2 CuO 2 , Li 2 NiO 2 , Li 5 FeO 4 , Li 6 CoO 4 .

6. The secondary battery according to any one of claims 1 to 5, in, The mass proportion of the lithium supplement in the positive electrode material layer is W 2 , where 0.1% ≤ W 2 ≤10%; optionally 1%≤W 2 ≤8%, optionally 1%≤W 2 ≤5%.

7. The secondary battery according to any one of claims 1 to 6, further comprising a negative electrode plate, wherein the negative electrode plate comprises a negative electrode material layer, wherein the negative electrode material layer comprises a negative electrode active material; wherein the average particle size Dv50 of the negative electrode active material is 3 to 25 μm; optionally, 5 μm≤Dv50≤20 μm, optionally, 7 μm≤Dv50≤15 μm.

8. The secondary battery according to any one of claims 1 to 7, wherein the active specific surface area of ​​the positive electrode sheet is B, wherein 0<B≤20m 2 / g, optional 2m 2 / g≤B≤10m 2 / g.

9. An electrical device comprising a secondary battery, in, The secondary battery comprises the secondary battery according to any one of claims 1 to 8.

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