Secondary battery and its manufacturing method, battery module, battery pack, and electrical device

Abstract

The present application provides a secondary battery, comprising a negative electrode sheet including a negative electrode material layer, a positive electrode sheet including a positive electrode material layer, and an electrolyte, wherein at least one of the negative electrode material layer, the positive electrode material layer, and the electrolyte comprises an interface passivator, the interface passivator being a compound containing an element E, the element E being selected from lithium, sodium, beryllium, magnesium, potassium, calcium, aluminum, gallium, and germanium. The present application further relates to a method for manufacturing the secondary battery, and a battery module, a battery pack, and an electric device including the secondary battery. The secondary battery of the present application has improved impedance and balanced cycle performance and storage performance.

Description

[Technical Field]

[0001] The present application relates to the technical field of lithium batteries, and more particularly to a secondary battery and a method for manufacturing the same, a battery module including the secondary battery, a battery pack, and an electric device. [Background technology]

[0002] As electric vehicles (EVs) and hybrid vehicles (HEVs) are widely used, people are increasingly paying attention to vehicle usage time and usage costs. Naturally, the cycle life of secondary batteries as vehicle energy storage devices has become one of the performances that is attracting attention in the field. As expected, secondary batteries have good cycle performance and long battery life, which not only reduces user usage costs but also reduces resource consumption.

[0003] Conventional techniques have not been able to effectively improve the cycle performance of secondary batteries, and it is difficult to balance cycle performance and storage performance. Therefore, there is a need in the art for a secondary battery with improved cycle and storage performance and a method for manufacturing the same. Summary of the Invention [Problem to be solved by the invention]

[0004] The present application has been made in view of the above-mentioned problems, and aims to provide a secondary battery having improved cycle and storage performance, and a method for manufacturing the same. [Means for solving the problem]

[0005] To achieve the above object, the present application provides a secondary battery and a manufacturing method thereof, a battery module, a battery pack, and an electric device.

[0006] A first aspect of the present application provides a secondary battery, comprising: a negative electrode sheet including a negative electrode material layer; a positive electrode sheet including a positive electrode material layer; and an electrolyte, wherein at least one of the negative electrode material layer, the positive electrode material layer, and the electrolyte comprises an interfacial passivator, the interfacial passivator being a compound containing element E, where E is selected from lithium, sodium, beryllium, magnesium, potassium, calcium, aluminum, gallium, and germanium. By including the interfacial passivator, the secondary battery can form a beneficial ternary layer on the surface of the negative electrode material layer.

[0007] In an optional embodiment, the negative electrode layer has an ADE ternary layer on its surface, where A is selected from alkali metal elements and is different from E, and D is silicon or carbon, and the ADE ternary layer is formed by the interfacial passivation agent acting on the surface of the negative electrode layer during at least one charging of the secondary battery. By providing the ternary passivation layer on the surface of the negative electrode layer, the secondary battery of the present application can significantly reduce battery impedance and improve the cycle life and storage performance of the battery.

[0008] In any embodiment, the interfacial passivation agent is selected from at least one of compounds of beryllium, magnesium, calcium, aluminum, and gallium, and preferably selected from at least one of compounds of beryllium, magnesium, calcium, and aluminum. By selecting a compound containing the above metal elements, the stabilization effect of the ternary layer can be further improved, thereby more effectively improving the performance of the secondary battery.

[0009] In any embodiment, the interfacial passivator may be a substituted or unsubstituted C 1-20 carboxylic acid salts, and the substituent is C 1-6 Alkyl group, C 2-6 Cycloalkyl group, hydroxyl group, amino group, oxo group, acyl group, C 1-6The interfacial passivation agent may be one or more selected from alkylthio, phenyl, benzoylthio, phenylthio, and phenoxy groups, amino acid salts, enoates, phosphates, sulfates, sulfonylimides, sulfonates, benzoates, phthalates, acetylacetonates, inorganic oxyacid salts, and double salts containing at least two of the above non-transition metal cations. By selecting the above compounds as the interfacial passivation agent, the resistance, cycle life, and storage performance of the secondary battery can be more effectively improved.

[0010] In any embodiment, the interfacial passivator is doped and mixed into at least one of the positive electrode material layer, the negative electrode material layer, and the electrolyte solution, and the performance of the secondary battery can be effectively improved by doping and mixing the interfacial passivator into the positive electrode material, the negative electrode material, and the electrolyte solution.

[0011] In some embodiments, the ADE ternary layer is selected from the group consisting of Li-Si-Ca, Li-Si-Mg, Li-Si-Be, Li-Si-Al, Li-C-Ca, Li-C-Mg, Li-C-Be, Li-C-Al, Na-Si-Ca, Na-Si-Mg, Na-Si-Be, Na-Si-Al, Na-C-Ca, Na-C-Mg, Na-C-Be, and Na-C-Al ternary layers, and combinations thereof. Preferably, the ADE ternary layer is selected from the group consisting of Li-Si-Ca, Li-Si-Mg, Li-Si-Be, Li-Si-Al, Na-Si-Ca, Na-Si-Mg, Na-Si-Be, and Na-Si-Al ternary layers, and combinations thereof. The inclusion of such ternary layers in a secondary battery can effectively improve battery impedance, cycle life, and storage performance.

[0012] In any embodiment, before the at least one charge, the positive electrode material layer comprises 0.001 wt % to 20 wt %, preferably 1 wt % to 10 wt %, of the interface passivator, based on the total weight of the positive electrode material layer.

[0013] In any embodiment, before the at least one charge, the negative electrode material layer comprises 0.001 wt % to 20 wt %, preferably 0.05 wt % to 5 wt %, of the interface passivator, based on the total weight of the negative electrode material layer.

[0014] In any embodiment, prior to the at least one charge, the electrolyte solution comprises 0.001 wt % to 20 wt %, preferably 0.1 wt % to 5 wt %, of the interface passivator, based on the total weight of the electrolyte solution.

[0015] By controlling the content of the passivating agent within the above range, the battery performance can be further improved.

[0016] In any embodiment, the negative electrode layer includes a negative electrode active material, and the negative electrode active material has a D50 of 1 μm to 20 μm, preferably 2 μm to 10 μm. By using a negative electrode active material having the above D50, the function of the ternary interface passivation layer of the present invention can be effectively exerted, and the performance of the secondary battery can be significantly improved.

[0017] In any embodiment, the negative electrode material layer includes a negative electrode active material, and the negative electrode active material has a Span value of 0.9 to 1.8, preferably 0.9 to 1.2; where:

number

[0018] A second aspect of the present application provides a secondary battery, the secondary battery comprising: i) providing a negative electrode sheet including a negative electrode material layer, a positive electrode sheet including a positive electrode material layer, and an electrolyte solution to manufacture an uncycled secondary battery, wherein at least one of the negative electrode material layer, the positive electrode material layer, and the electrolyte solution includes an interface passivator, the interface passivator being a compound including an element E, and the element E being selected from the group consisting of lithium, sodium, beryllium, magnesium, potassium, calcium, aluminum, gallium, and germanium; ii) charging and discharging the uncycled secondary battery for at least one cycle.

[0019] A third aspect of the present application provides a method for manufacturing a secondary battery, i) providing a negative electrode sheet including a negative electrode material layer, a positive electrode sheet including a positive electrode material layer, and an electrolyte solution to manufacture an uncycled secondary battery, wherein at least one of the negative electrode material layer, the positive electrode material layer, and the electrolyte solution includes an interface passivator, the interface passivator being a compound including an element E, and the element E being selected from the group consisting of lithium, sodium, beryllium, magnesium, potassium, calcium, aluminum, gallium, and germanium; ii) charging and discharging the uncycled secondary battery for at least one cycle to form an ADE ternary layer and obtain the secondary battery, wherein A is selected from alkali metal elements and is different from E, and D is silicon or carbon.

[0020] The above method can provide a secondary battery having a ternary passivation layer on the surface of the negative electrode material layer, thereby improving the impedance, cycle life and storage performance of the secondary battery.

[0021] In any embodiment, the interfacial passivator is selected from at least one of compounds of beryllium, magnesium, calcium, aluminum, and gallium, and preferably selected from at least one of compounds of beryllium, magnesium, calcium, and aluminum. By selecting the interfacial passivator, a ternary layer can be effectively formed, and performance such as cycle and storage of the secondary battery can be improved.

[0022] In any embodiment, the interfacial passivator may be a substituted or unsubstituted C 1-20 carboxylic acid salts, and the substituent is C 1-6 Alkyl group, C 2-6 Cycloalkyl group, hydroxyl group, amino group, oxo group, acyl group, C 1-6 The interfacial passivation agent is one or more selected from alkylthio groups, phenyl groups, benzoylthio groups, phenylthio groups, and phenoxy groups, amino acid salts, enoates, phosphates, sulfates, sulfonylimides, sulfonates, benzoates, phthalates, acetylacetonates, inorganic oxyacid salts, and double salts containing at least two of the above non-transition metal cations. By selecting the above interfacial passivation agent, secondary batteries with significantly improved resistance, cycle life, and storage performance can be manufactured.

[0023] In an optional embodiment, in step i), the interfacial passivator is doped and mixed into at least one of the positive electrode material layer, the negative electrode material layer, and the electrolyte solution, which facilitates the formation of a ternary layer and can further improve the performance of the secondary battery.

[0024] A fourth aspect of the present application provides a battery module including a secondary battery according to the first or second aspect of the present application or a secondary battery obtained by the method according to the third aspect of the present application.

[0025] A fifth aspect of the present application provides a battery pack including the battery module according to the fourth aspect of the present application.

[0026] A sixth aspect of the present application provides an electrical device including at least one selected from the secondary battery according to the first or second aspect of the present application, the secondary battery obtained by the method according to the third aspect of the present application, the battery module according to the fourth aspect, or the battery pack according to the fifth aspect. [Effects of the Invention]

[0027] The secondary battery of the present invention and the secondary battery obtained by the manufacturing method of the present invention have balanced cycle performance and storage performance, and low internal resistance. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a schematic diagram illustrating a secondary battery according to an embodiment of the present application. [Figure 2] FIG. 2 is an exploded view showing the secondary battery according to the embodiment of the present invention shown in FIG. [Figure 3] 1 is a schematic diagram illustrating a battery module according to an embodiment of the present application. [Figure 4] 1 is a schematic diagram illustrating a battery pack according to an embodiment of the present application. [Figure 5] 5 is an exploded view showing the battery pack according to the embodiment of the present invention shown in FIG. 4. [Figure 6] 1 is a schematic diagram illustrating an electrical device that uses a secondary battery as a power source according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the secondary battery, battery module, battery pack, and electrical device of the present application will be described in detail. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters and redundant description of the same actual structure may be omitted. This is to avoid unnecessarily lengthening the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0030] The "ranges" disclosed herein are defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of that particular range. Such defined ranges may be inclusive or exclusive, and may be arbitrarily combined; i.e., any lower limit may be combined with any upper limit to form a single range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if minimum range values ​​1 and 2 and maximum range values ​​3, 4, and 5 are listed, the following ranges are also contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. Unless otherwise specified, the numerical range "ab" herein refers to a shorthand notation for any combination of real numbers from a to b, where both a and b are real numbers. For example, the numerical range "0-5" refers to all real numbers between "0-5" listed herein, and "0-5" is simply a shorthand notation for combinations of these numbers. Also, when a parameter refers to an integer ≧2, this is equivalent to disclosing that the parameter is an integer, e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0031] Unless otherwise specified, all embodiments and preferred embodiments in this application can be combined with each other to form new technical solutions.

[0032] Unless otherwise specified, all technical features and preferred technical features of the present application can be combined with each other to form new technical solutions.

[0033] Unless otherwise specified, all steps herein may be performed sequentially or randomly, preferably sequentially. For example, a description of a method including steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a description of a method mentioned above that may include step (c) indicates that step (c) can be added to the method in any order, e.g., 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).

[0034] Unless otherwise specified, the terms "comprise" and "include" used in this application may be open-ended or exclusive. For example, the terms "comprise" and "include" may further comprise or include other components not listed, or may comprise or include only the listed components.

[0035] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the words "A or B" indicate "A, B, or both A and B." More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) but B is true (or exists), or both A and B are true (or exist).

[0036] As electric vehicles (EVs) and hybrid vehicles (HEVs) are widely used, people are increasingly paying attention to vehicle usage time and usage costs. Naturally, the cycle life of secondary batteries as vehicle energy storage devices has become one of the performances that is attracting attention in the field. As expected, secondary batteries have good cycle performance and long battery life, which not only reduces user usage costs but also reduces resource consumption.

[0037] The solid electrolyte interface (SEI) film on the sheet surface plays an important role in improving the cycling performance of secondary batteries. The formation of the SEI film consumes the electrolyte (or electrolyte ions in the electrolyte, i.e., active ions or charge carrier ions). Therefore, if the SEI film is repeatedly broken and regenerated during cycling, the transport kinetics of the active ions may deteriorate, which may lead to electrolyte depletion and a deterioration in battery cell performance.

[0038] However, currently commonly used positive and negative electrode active materials undergo varying degrees of volume change during cycling, which affects the integrity and stability of the SEI layer and further impairs battery performance. This problem is particularly pronounced for silicon-based negative electrode active materials, where the volume change is significant (100%-300%).

[0039] In this field, the SEI film layer that is compatible with the volume change of the material and can be fully maintained is sought. To achieve this, additives are usually added to the electrolyte or coated on the surface of the active material or sheet. However, the SEI layer obtained by these methods is not compatible with the volume change of the material, and therefore cannot significantly improve battery performance. As can be seen from the above, conventional methods cannot effectively solve the interface problem caused by the volume change of the material.

[0040] Another challenge is carefully balancing cycle performance and storage performance. As is known in the art, excellent storage performance and long cycle life require different, even inverse, requirements for the SEI film. Regarding cycle life, a relatively flexible and thin SEI is advantageous because it is more accommodating to volume changes of the negative electrode material, consumes less during repeated formation, and has low interfacial impedance. Regarding storage life, however, a non-porous and robust SEI is advantageous because it can prevent electrolyte penetration and current leakage. However, during cycling, such a thick and inflexible SEI cracks when volume changes of the negative electrode material occur, consuming additional electrolyte and affecting ion migration, resulting in a relatively low initial capacity and somewhat poor charging performance.

[0041] However, a secondary battery expected in this field should have excellent overall performance, that is, excellent cycle performance and storage performance.

[0042] One object of the present application is to provide a secondary battery with balanced overall performance, i.e., excellent cycle performance and storage performance. Another object of the present application is to provide a method for manufacturing a secondary battery. The secondary battery of the present application has excellent overall performance, low internal resistance of the battery after multiple cycles, longer cycle life, and better storage performance.

[0043] Hereinafter, the secondary battery, battery module, battery pack, and electrical device of the present application will be described with appropriate reference to the drawings.

[0044] Secondary battery and manufacturing method thereof In one embodiment, the present application provides a secondary battery, the secondary battery comprising: an anode sheet including an anode material layer; a cathode sheet including a cathode material layer; and an electrolyte, wherein at least one of the anode material layer, the cathode material layer, and the electrolyte comprises an interfacial passivator, the interfacial passivator being a compound containing element E, where E is selected from lithium, sodium, beryllium, magnesium, potassium, calcium, aluminum, gallium, and germanium. Without being bound by theory, the inclusion of the interfacial passivator in at least one of the cathode material layer, the electrolyte, and the anode material layer creates a beneficial ternary layer when the anode material absorbs active ions during at least one charging process after the secondary battery is newly fabricated, improving the sheet and battery performance.

[0045] Herein, depending on the type of secondary battery, the active ions may be lithium ions or sodium ions, i.e., the active ions of a lithium-ion secondary battery are lithium ions, and the active ions of a sodium-ion secondary battery are sodium ions.

[0046] In some embodiments, the negative electrode layer has an ADE ternary layer formed on the surface thereof, where A is selected from alkali metal elements and is different from E, and D is silicon or carbon. The ADE ternary layer is formed by the interfacial passivation agent acting on the surface of the negative electrode layer during at least one charge of the secondary battery. The secondary battery of the present application has a ternary layer on the surface of the negative electrode layer, which stabilizes the negative electrode interface and accommodates volume changes, thereby improving sheet and battery performance, particularly achieving a careful balance between cycling performance and storage performance. Furthermore, with an increase in the number of charge / discharge cycles, the advantages of the secondary battery of the present application become more apparent, particularly significantly reduced battery impedance and improved battery cycle life and storage performance (e.g., improved capacity retention, especially after cycling and storage at high temperatures).

[0047] As used herein, the terms "ternary layer" and similar expressions have the same or similar meaning and can be used interchangeably.

[0048] In some embodiments, the secondary battery is a lithium ion secondary battery or a sodium ion secondary battery. In this case, the present interface passivator or the ternary layer can significantly improve the cycle performance, impedance, etc. of the battery. In some embodiments, the secondary battery is a lithium ion secondary battery.

[0049] In some embodiments, the interfacial passivator is a non-transition metal compound with an atomic number of 20 or less. Such a compound may be organic or inorganic. The inventors have discovered that, particularly for lithium-ion secondary batteries, it is ideal to use a compound of a metal element with an atomic number of 20 or less as the interfacial passivator. It is particularly desirable to select a compound of a metal with lower activity than the active ions of the secondary battery as the interfacial passivator. Without being bound by any theory, such interfacial passivators are prone to gain electrons in electrochemical reactions and to form ternary layers. In contrast, improving the performance of transition metal compounds can be difficult in some cases because the transition metal atoms contain many vacant orbitals, which are unfavorable for the formation of ternary layers and may actually promote interfacial reactions.

[0050] As used herein, the term "transition metal" has the meaning well known in the art, and generally refers to metallic elements in the d and ds regions of the periodic table (the d region elements include elements from groups IIIB to VIIB and group VIII of the periodic table, excluding the lanthanide and actinide elements, and the ds region includes elements from groups IB to IIB of the periodic table).

[0051] In some embodiments, the interfacial passivator has a metal cation moiety with a valence of 2 to 5. In some embodiments, the interfacial passivator can be selected from at least one of compounds of lithium, sodium, beryllium, magnesium, potassium, calcium, aluminum, gallium, and germanium, and is preferably at least one of compounds of beryllium, magnesium, potassium, calcium, aluminum, gallium, and germanium.

[0052] In some embodiments, the interfacial passivation agent is selected from at least one of compounds of beryllium, magnesium, calcium, aluminum, and gallium, and preferably selected from at least one of compounds of beryllium, magnesium, calcium, and aluminum. By selecting a compound containing the above metal elements, the effect of the interfacial passivation layer can be further improved, and the performance of the secondary battery can be more effectively improved.

[0053] In some embodiments, the interfacial passivator is selected from a combination of two or three of magnesium, aluminum, and calcium compounds, and the incorporation of such a combination of interfacial passivators can further improve the internal resistance, cycle, and storage performance of the battery.

[0054] In some embodiments, the interfacial passivator is a substituted or unsubstituted C 1-20 carboxylic acid salts, and the substituent is selected from at least one of C 1-6 Alkyl group, C 2-6 Cycloalkyl group, hydroxyl group, amino group, oxo group, acyl group, C 1-6 The non-transition metal cations may be one or more selected from alkylthio groups, phenyl groups, benzoylthio groups, phenylthio groups, and phenoxy groups, amino acid salts, enoates, phosphates, sulfates, sulfonylimides, sulfonates, benzoates, phthalates, acetylacetonates, inorganic oxyacid salts, and double salts containing at least two of the non-transition metal cations.

[0055] In some embodiments, the interfacial passivation agent is preferably selected from the group consisting of calcium propionate, calcium stearate, calcium acetate, calcium cyclohexanebutyrate, calcium formate, calcium DL-malate, calcium glycolate, calcium 3-methyl-2-oxobutyrate, calcium levulinate, calcium 2-ethylhexanoate, calcium 2-hydroxy-4-(methylthio)butyrate, calcium DL-glycerate, aluminum stearate, aluminum monostearate, alkali aluminum acetate, aluminum terephthalate, aluminum acetate, aluminum oxalate, aluminum bisstearate, aluminum lactate, magnesium stearate, magnesium lactate, magnesium oxalate, magnesium acetate, magnesium citrate, magnesium valproate, magnesium 2-ethylhexanoate, magnesium 2-ethylbutyrate, magnesium phenoxyacetate, calcium bis(nonafluorobutylsulfonyl)imide, calcium bis(fluorosulfonyl)imide, calcium bis(trifluoromethanesulfonyl)imide, and bis(trifluoromethanesulfonyl)imide. magnesium sulfonylimide, calcium methylsulfonate, calcium 2,5-dihydroxybenzenesulfonate, calcium trifluoromethanesulfonate, calcium dobesilate, magnesium trifluoromethanesulfonate, aluminum tris(trifluorosulfonate), calcium benzoate, calcium phthalate, calcium 4-aminosalicylate, calcium acetylacetonate, calcium hexafluoroacetylacetonate, beryllium acetylacetonate, magnesium acetylacetonate, bis(2,4-pentanedione)magnesium(II), magnesium trifluoroacetylacetonate, magnesium hexafluoroacetylacetonate, aluminum acetylacetonate, aluminum tris(trifluoro-2,4-pentanedionato), calcium metaborate, calcium nitrate, aluminum metaphosphate, aluminum perchlorate, dihydroaluminum phosphate, aluminum hypophosphite, aluminum phosphate, magnesium perchlorate, magnesium metaborate, magnesium nitrate, beryllium sulfate, calcium aluminumate, triethylaluminum,Trioctyl aluminum, tri-n-butyl aluminum, isopropyl dimethyl aluminum, tris(hexadecyl) aluminum, diocene magnesium, di-n-butyl magnesium, n-butylethyl magnesium, bis(ethylcyclopentadienyl) magnesium, bis(pentamethylcyclopentene) magnesium, bis(cyclopentadienyl) magnesium, bis(n-propylcyclopentadienyl) magnesium, bis(ethylcyclopentadienyl) magnesium, bis(2-(2-hydroxyphenyl)pyridine) beryllium, bis(pentamethylcyclopentadienyl) tetrahydrofuran calcium, isopropyl alcohol aluminum, ethyfen The compound is selected from at least one of aluminum t-butoxide, aluminum t-butoxide, aluminum sec-butyl alcohol, aluminum n-butoxide, aluminum hydroxyaluminum bis(2-ethylhexanoate), magnesium methanol, magnesium ethanol, magnesium tert-butoxide, magnesium aluminum silicate, calcium methacrylate, calcium sorbate (2,4-hexadienoic acid), aluminum acrylate, magnesium acrylate, calcium phytate, hemicalcium bis(2-ethylhexyl)phosphate, aluminum diethylphosphinate, magnesium lauryl sulfate, calcium phenylpyruvate, and calcium acetonidioate.

[0056] In some embodiments, the interfacial passivator is preferably selected from at least one of fluorosulfonylimide salts, acetylacetone salts, and inorganic oxyacid salts. In some embodiments, the inorganic oxyacid salt is selected from at least one of metaboric acid, nitric acid, metaphosphoric acid, perchloric acid, phosphoric acid, hypophosphorous acid, sulfuric acid, and aluminum acid. In some embodiments, the interfacial passivator is selected from at least one of fluorosulfonylimide salts, acetylacetone salts, fluoroacetylacetone salts, nitrates, phosphates, perchlorates, and sulfates.

[0057] In some embodiments, the interfacial passivator is preferably selected from at least one of calcium bis(nonafluorobutylsulfonyl)imide, calcium nitrate, aluminum tris(trifluoro-2,4-pentanedionato), aluminum phosphate, magnesium hexafluoroacetylacetonate, magnesium perchlorate, beryllium acetylacetonate, and beryllium sulfate.

[0058] By selecting the above interfacial passivation agents, it is possible to reduce the resistance of the secondary battery and achieve a careful balance between cycle life and storage performance.

[0059] In some embodiments, the interfacial passivator is doped and mixed into at least one of the positive electrode material layer (or positive electrode slurry), the negative electrode material layer (or negative electrode slurry), and the electrolyte solution, which is advantageous for the formation of the ternary layer by directly adding the interfacial passivator to the battery system.

[0060] As used herein, "dope mixing" means that the interfacial passivation agent is directly doped and mixed and sprinkled (or dispersed) into the slurry or electrolyte. Dope mixing does not include coating.

[0061] In some embodiments, the ADE ternary layer is selected from Li-Si-Ca, Li-Si-Mg, Li-Si-Be, Li-Si-Al, Li-C-Ca, Li-C-Mg, Li-C-Be, Li-C-Al, Na-Si-Ca, Na-Si-Mg, Na-Si-Be, Na-Si-Al, Na-C-Ca, Na-C-Mg, Na-C-Be, Na-C-Al ternary layers, and combinations thereof. In some embodiments, the ADE ternary layer is preferably selected from Li-Si-Ca, Li-Si-Mg, Li-Si-Be, Li-Si-Al, Na-Si-Ca, Na-Si-Mg, Na-Si-Be, Na-Si-Al ternary layers, and combinations thereof. The inclusion of the ternary interfacial passivation layer in a secondary battery can effectively improve battery impedance, cycle life, and storage performance.

[0062] In some embodiments, the ternary layer is formed by the action of an interfacial passivator on the surface of the negative electrode material during at least one charge cycle of the secondary battery, hi some embodiments, the ternary layer is formed during 1-3, preferably 1-2, and more preferably 1 charge cycle of the secondary battery.

[0063] In some embodiments, before the at least one charge, the positive electrode material layer comprises 0.001 wt % to 20 wt %, preferably 1 wt % to 10 wt %, of the interface passivator, based on the total weight of the positive electrode material layer.

[0064] In some embodiments, before the at least one charge, the negative electrode layer comprises 0.001 wt % to 20 wt %, preferably 0.05 wt % to 5 wt %, of the interface passivator, based on the total weight of the negative electrode layer.

[0065] In some embodiments, the electrolyte comprises, based on the total weight of the electrolyte, 0.001 wt % to 20 wt %, preferably 0.1 wt % to 5 wt %, of the interfacial passivator, prior to the at least one charge. In some embodiments, the electrolyte preferably comprises, based on the total weight of the electrolyte, 0.2 wt % to 5 wt %, preferably 0.3 wt % to 5 wt %, of the interfacial passivator, prior to the at least one charge.

[0066] By controlling the content of the passivating agent within the above range, the battery performance can be further improved: if the content is too low, an effective ternary interfacial passivation layer cannot be formed, and if the content is too high, a ternary phase will also be formed in the bulk phase of the sheet material layer, reducing the energy density of the battery cell.

[0067] In some embodiments, the negative electrode layer advantageously includes the interfacial passivator, which can be added in small amounts to achieve the desired purpose while reducing the impact on electrolyte components or performance.

[0068] In some embodiments, the negative electrode active material layer comprises a silicon-based negative electrode active material or a carbon-based negative electrode active material. In particular, in some embodiments, the negative electrode layer comprises a silicon-based negative electrode active material. The benefits of including the ternary layer of the present invention in a secondary battery are particularly pronounced when using a negative electrode material with a large volume change. When the negative electrode layer comprises a silicon-based negative electrode material (and thus consists of a silicon-based negative electrode active material), adding the interface passivator of the present application to such a secondary battery system is particularly advantageous.

[0069] In some embodiments, the negative electrode active material has a D50 of 1 μm to 20 μm, preferably 2 μm to 10 μm. By using a material with a D50 in this range, the interfacial passivation effect of the ternary layer of the present invention can be effectively exerted, significantly improving secondary battery performance and balancing ease of sheet fabrication with superior performance. By using a material with a D50 in this range, excessive interfacial activity due to an excessively large specific surface area of ​​the material can be avoided, which is advantageous for the interfacial passivation layer to effectively achieve the desired performance improvement, while also avoiding the inhibition of active ion migration, which is advantageous for improving overall battery performance.

[0070] In some embodiments, the negative electrode active material has a Span value of 0.9 to 1.8, preferably 0.9 to 1.2. where:

number

[0071] As used herein, the term "Span value" characterizes the particle size distribution width of a material. The Span value is a dimensionless quantity as defined above. Selecting a negative electrode active material having a Span value within the above range is advantageous for the material to have relative interfacial stability, which contributes to the realization of improved battery performance.

[0072] In some embodiments, the negative electrode active material has a D50 of 1 μm-20 μm and a Span of 0.9-1.8, and in other embodiments, the negative electrode active material has a D50 of preferably 3 μm-10 μm and a Span of preferably 0.9-1.2.

[0073] A second aspect of the present application provides a secondary battery, the secondary battery comprising: i) providing a negative electrode sheet including a negative electrode material layer, a positive electrode sheet including a positive electrode material layer, and an electrolyte solution to manufacture an uncycled secondary battery, wherein at least one of the negative electrode material layer, the positive electrode material layer, and the electrolyte solution includes an interface passivator, the interface passivator being a compound including an element E, and the element E being selected from the group consisting of lithium, sodium, beryllium, magnesium, potassium, calcium, aluminum, gallium, and germanium; ii) charging and discharging the uncycled secondary battery for at least one cycle.

[0074] A third aspect of the present application provides a method for manufacturing a secondary battery, i) providing a negative electrode sheet including a negative electrode material layer, a positive electrode sheet including a positive electrode material layer, and an electrolyte solution to manufacture an uncycled secondary battery, wherein at least one of the negative electrode material layer, the positive electrode material layer, and the electrolyte solution includes an interface passivator, the interface passivator being a compound including an element E, and the element E being selected from the group consisting of lithium, sodium, beryllium, magnesium, potassium, calcium, aluminum, gallium, and germanium; ii) charging and discharging the uncycled secondary battery for at least one cycle to form an ADE ternary layer and obtain the secondary battery, wherein A is selected from alkali metal elements and is different from E, and D is silicon or carbon.

[0075] The secondary battery finally manufactured by the above method is a secondary battery having a ternary passivation layer on the surface of the negative electrode material layer, and has improved impedance, cycle life and storage performance.

[0076] In some embodiments, step i) comprises: a) providing a positive electrode slurry, a negative electrode slurry, and an electrolyte solution, wherein at least one of the positive electrode slurry, the negative electrode slurry, and the electrolyte solution is doped and mixed with an interfacial passivation agent.

[0077] In some embodiments, step i) further comprises b) applying the positive electrode slurry and the negative electrode slurry to at least one surface of a positive electrode current collector and a negative electrode current collector, respectively, to obtain a positive electrode sheet and a negative electrode sheet, and assembling the positive electrode sheet, the negative electrode slurry, and the electrolyte solution into the uncycled secondary battery.

[0078] Without being bound by any theory, when the negative electrode sheet material layer contains an interfacial passivator, the interfacial passivator acts directly on the negative electrode sheet material layer to form a ternary layer during at least one charge-discharge cycle. When the positive electrode sheet material layer and / or the electrolyte contain an interfacial passivator, the interfacial passivator migrates to the surface of the negative electrode sheet material layer under the action of voltage to form a ternary layer during at least one charge-discharge cycle. For example, the interfacial passivator, the active ions of the secondary battery, and the negative electrode active material form the ternary layer under the action of voltage. The present application achieves improved battery performance by forming a ternary layer on the surface of the negative electrode sheet material layer.

[0079] In some embodiments, the at least one cycle described in step ii) is performed at a voltage between 3V and 4.3V.

[0080] In some embodiments, step ii) is a conversion step.

[0081] As used herein, the term "formation" has the meaning well known in the art, and generally refers to a first charge of a newly manufactured secondary battery, during which absorption and desorption of lithium ions occurs, activating the negative electrode active material and forming a passivation layer, for example, a solid electrolyte interface film (SEI film), on the surface of the negative electrode material layer.

[0082] In some embodiments, the interfacial passivator is selected from at least one of compounds of beryllium, magnesium, calcium, aluminum, and gallium, and preferably, the interfacial passivator is selected from at least one of compounds of beryllium, magnesium, calcium, and aluminum.

[0083] In some embodiments, before the at least one charge, the positive electrode material layer comprises 0.001 wt % to 20 wt %, preferably 1 wt % to 10 wt %, of the interface passivator, based on the total weight of the positive electrode material layer.

[0084] In some embodiments, before the at least one charge, the negative electrode layer comprises 0.001 wt % to 20 wt %, preferably 0.05 wt % to 5 wt %, of the interface passivator, based on the total weight of the negative electrode layer.

[0085] In some embodiments, prior to the at least one charge, the electrolyte solution comprises 0.001 wt % to 20 wt %, preferably 0.1 wt % to 5 wt %, of the interface passivator, based on the total weight of the electrolyte solution.

[0086] In some embodiments, the interfacial passivator is added to the positive electrode sheet material slurry, the negative electrode sheet material slurry, or the electrolyte by doping (or mixing).

[0087] The cathode material slurry includes a cathode active material, an interfacial passivator, a solvent, and optional additives. In some embodiments, the cathode material slurry includes 0.001 wt % to 20 wt %, preferably 1 wt % to 10 wt %, of the interfacial passivator, based on the dry weight of the cathode material slurry.

[0088] The negative electrode material slurry includes a negative electrode active material, an interfacial passivator, a solvent, and optional additives. In some embodiments, the negative electrode material slurry includes 0.001 wt % to 20 wt %, preferably 0.05 wt % to 5 wt %, of the interfacial passivator, based on the dry weight of the negative electrode material slurry.

[0089] By using the interfacial passivator in the above content range, a ternary layer can be effectively formed on the surface of the negative electrode sheet material layer, thereby passivating and protecting the interface and improving the performance of the secondary battery.

[0090] In some embodiments, the anode slurry includes an anode active material. The anode active material may include a silicon-based anode active material or a carbon-based anode active material. In particular, in some embodiments, the anode slurry includes a silicon-based anode active material. The advantages of the interface passivator and the ternary layer formed thereon are particularly pronounced when using anode materials with large volume changes.

[0091] In addition, the components other than the interface passivator in each component of the secondary battery will be described below.

[0092] [Positive electrode sheet] The positive electrode sheet includes a positive electrode current collector and a positive electrode material layer provided on at least one surface of the positive electrode current collector, the positive electrode material layer including a positive electrode active material.

[0093] For example, the positive electrode current collector has two surfaces facing each other in the thickness direction thereof, and the positive electrode film layer is provided on either one or both of the two facing surfaces of the positive electrode current collector.

[0094] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector includes a polymer substrate layer and a metal layer formed on at least one surface of the polymer substrate layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0095] In some embodiments, the positive electrode active material may be a battery positive electrode active material known in the art. For example, the positive electrode active material may include at least one of lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and modified compounds thereof. The present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials in 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 include lithium cobalt oxide (e.g., LiCoO), lithium nickel oxide (e.g., LiNiO), lithium manganese oxide (e.g., LiMnO, LiMnO), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM 333 (can also be abbreviated as LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM 523 (can also be abbreviated as LiNi 0.5 Co 0.25 Mn 0.25 O2(NCM 211 (can also be abbreviated as LiNi 0.6 Co 0.2 Mn 0.2O2(NCM 622 (can also be abbreviated as LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM 811 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 O2) and modified compounds thereof, etc. Examples of the lithium-containing phosphate having an olivine structure include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which can also be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0096] In the secondary battery described in the present invention, the positive electrode active material is preferably selected from materials that undergo a volume change during the absorption-desorption of battery active ions (e.g., lithium ions, sodium ions, or potassium ions) and / or whose material interface has catalytic activity with respect to the electrolyte. In some embodiments, the positive electrode active material is selected from one or more of lithium iron phosphate (LFP), lithium manganese iron phosphate (LFMP), lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium-rich materials, sodium or potassium oxide compounds, and compounds obtained by adding other metals to the above compounds, where the other metals are selected from one or more transition metals and / or non-transition metals other than beryllium, magnesium, calcium, and aluminum. However, those skilled in the art will understand that the present invention is not limited to these materials.

[0097] In some embodiments, the positive electrode film layer preferably further includes a binder. The type and content of the binder are not specifically limited and can be selected according to actual needs. For example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0098] In some embodiments, the positive electrode layer may further include a conductive agent. The type and content of the conductive agent are not particularly limited and may be selected according to actual needs. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, cochin black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0099] In some embodiments, a positive electrode sheet can be manufactured as follows: the components for manufacturing the positive electrode sheet, such as the positive electrode active material, conductive agent, binder, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then coated onto a positive electrode current collector, followed by processes such as drying and cold pressing, to obtain a positive electrode sheet.

[0100] [Negative electrode sheet] The negative electrode sheet includes a negative electrode current collector and a negative electrode material layer provided on at least one surface of the negative electrode current collector, and the negative electrode material layer includes a negative electrode active material.

[0101] For example, the negative electrode current collector has two surfaces opposing each other in the thickness direction thereof, and the negative electrode film layer is provided on either one or both of the two opposing surfaces of the negative electrode current collector.

[0102] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. The composite current collector may include a polymer substrate layer and a metal layer formed on at least one surface of the polymer substrate layer. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0103] In some embodiments, the negative electrode active material may be a battery positive electrode active material known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of tin, stannate compounds, and tin alloys. However, the present application is not limited to these materials, and other conventional materials usable as negative electrode active materials in batteries may also be used. These negative electrode active materials may be used alone or in combination.

[0104] In the secondary battery described in the present invention, the negative electrode active material is preferably selected from materials that undergo a volume change during the absorption-desorption of battery active ions (e.g., sodium ions, lithium ions, or potassium ions) and / or whose material interface has catalytic activity with respect to the electrolyte. In some embodiments, the negative electrode active material is selected from silicon-based negative electrode materials. In some embodiments, the negative electrode active material is preferably selected from one or more of graphite, soft carbon, hard carbon, mesocarbon microbeads, carbon fiber, carbon nanotubes, elemental silicon, silicone compounds, silicon-carbon composites, and compounds obtained by adding other metals to the above materials, where the other metals are selected from one or more of transition metals and / or non-transition metals other than beryllium, magnesium, calcium, and aluminum. However, those skilled in the art will understand that the present invention is not limited to these materials.

[0105] In some embodiments, the negative electrode active material is selected from silicon-based negative electrode materials, hi some embodiments, the negative electrode active material is selected from one or more of elemental silicon, silicone compounds, and silicon-carbon composites.

[0106] In some embodiments, the negative electrode film layer preferably further includes a binder. The type and content of the binder are not specifically limited and can be selected according to actual needs. 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).

[0107] In some embodiments, the negative electrode film layer preferably further comprises a conductive agent. The type and content of the conductive agent are not specifically limited and can be selected according to actual needs. The conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, cochin black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0108] In some embodiments, the negative electrode membrane layer preferably further comprises other auxiliary agents, such as a thickener (eg, carboxymethylcellulose sodium (CMC-Na)).

[0109] In some embodiments, the negative electrode sheet can be manufactured as follows: the components for manufacturing the negative electrode sheet, such as the negative electrode active material, conductive agent, binder, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, which is then coated onto a negative electrode current collector, followed by processes such as drying and cold pressing, to obtain a negative electrode sheet.

[0110] [Electrolytes] The electrolyte serves to conduct ions between the positive and negative electrode pieces. This application is not specifically limited to the type of electrolyte, and it can be selected as needed. For example, the electrolytes commonly seen in this analysis can be liquid, gelled, or all-solid. This application mainly refers to liquid electrolytes.

[0111] In some embodiments, the electrolyte is an electrolytic solution, which includes an electrolyte salt and a solvent.

[0112] In the present application, the type of electrolyte salt is not specifically limited and can be selected as needed. In some embodiments, the electrolyte salt is lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bisfluorosulfonylimide (LiFSI), lithium bistrifluoromethanesulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiCFSO), lithium difluorophosphate, lithium difluorooxaloborate, lithium bis(oxalo)borate (LiBOB), lithium difluorooxalophosphate, lithium tetrafluorooxalophosphate, and LiN(C x F 2x +1SO2)(C y F 2y +1SO2) (where x and y are natural numbers). Although only examples of electrolyte salts used in lithium ion secondary batteries have been given above, the present invention is not limited thereto. For secondary batteries having other active ions, the corresponding electrolyte salts are not specifically limited and can be selected as needed.

[0113] The present application does not specifically limit the type of organic solvent for the electrolyte and can be selected as needed. In some embodiments, the organic solvent can include one or more of a chain carbonate ester, a cyclic carbonate ester, a carboxylic acid ester, and an ether. The present application does not specifically limit the type of the chain carbonate ester, the cyclic carbonate ester, the carboxylic acid ester, and the ether and can be selected as needed. In some embodiments, the organic solvent can preferably include one or more of diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, methyl formate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, tetrahydrofuran, dimethyl ether, diethyl ether, and ethylene glycol dimethyl ether.

[0114] In some embodiments, the electrolyte solution preferably further contains an additive. For example, the additive may include a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve certain battery performance, such as an additive that improves the overcharge performance of the battery or an additive that improves the high-temperature or low-temperature performance of the battery.

[0115] In some embodiments, the electrolyte additive is selected from at least one of a cyclic carbonate compound containing an unsaturated bond, a halogen-substituted cyclic carbonate compound, a sulfate compound, a sulfite compound, a sultonic acid ester compound, a disulfonic acid compound, a nitrile compound, an aromatic compound, an isocyanate compound, a phosphazene compound, a cyclic acid anhydride compound, a phosphite compound, a phosphate compound, a borate ester compound, and a carboxylate ester compound.

[0116] [Separator] In some embodiments, the secondary battery further includes a separator. The present application is not particularly limited to the type of separator, and any known porous separator having excellent chemical and mechanical stability can be selected.

[0117] In some embodiments, the separator may be made of at least one material selected from the group consisting of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator is not particularly limited and may be a single-layer thin film or a multi-layer composite thin film. When the separator is a multi-layer composite thin film, the materials of each layer are not particularly limited and may be the same or different.

[0118] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be manufactured into an electrode assembly by a winding process or a lamination process.

[0119] In some embodiments, the secondary battery may include an outer casing, which can be used to seal the electrode assembly and electrolyte.

[0120] In some embodiments, the exterior of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the exterior of the secondary battery may be a soft bag, such as a pouch soft bag. The soft bag may be made of plastic, such as polypropylene, polybutylene terephthalate, or polybutylene succinate.

[0121] The present application is not particularly limited to the shape of the secondary battery, and it may be cylindrical, rectangular, or any other shape. For example, Fig. 1 shows an example of a secondary battery 5 having a rectangular structure.

[0122] In some embodiments, referring to FIG. 2 , the exterior may include a housing 51 and a cover plate 53. The housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates may surround the housing 51 to form a storage chamber. The housing 51 may have an opening communicating with the storage chamber, and the cover plate 53 may cover the opening to close the storage chamber. The positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is sealed in the storage chamber. An electrolyte is impregnated into the electrode assembly 52. ​​The secondary battery 5 may include one or more electrode assemblies 52, and this can be selected by those skilled in the art according to specific practical needs.

[0123] In some embodiments, the secondary batteries can be assembled into a battery module, and the number of secondary batteries included in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0124] FIG. 3 shows an example of a battery module 4. Referring to FIG. 3, in the battery module 4, a plurality of secondary batteries 5 are arranged in a sequential manner along the length of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fastened together with fasteners.

[0125] Preferably, the battery module 4 may further include an outer case having a storage space, and the plurality of secondary batteries 5 are stored in the storage space.

[0126] In some embodiments, the battery modules can be further assembled into a battery pack, and the battery pack can include one or more battery modules, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery modules.

[0127] 4 and 5 show an example of a battery pack 1. Referring to FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 provided in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 may be covered by the lower housing 3 to form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 may be distributed in any manner within the battery box.

[0128] The present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided herein. The secondary battery, battery module, or battery pack can be used as a power source for the electric device and also as an energy storage unit for the electric device. The electric device includes, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), trains, ships, satellites, energy storage systems, etc.

[0129] The electrical device can be selected from a secondary battery, a battery module, or a battery pack depending on the usage requirements.

[0130] 6 shows an example of an electric device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density demands of the secondary battery of the electric device, a battery pack or a battery module can be used.

[0131] Other examples of the device may be a mobile phone, a tablet, a laptop, etc. Such devices are usually required to be thin and can use a secondary battery as a power source.

[0132] Example

[0133] The following examples of the present application are described. The examples described below are merely illustrative and are used only to interpret the present application, and should not be understood as limiting the present application. If specific techniques or conditions are not specified in the examples, they should be carried out according to the techniques or conditions described in the literature in the field or according to the product specifications. If the manufacturer of the reagents or equipment used is not specified, they are conventional products that can be purchased commercially.

[0134] The secondary batteries of the present invention and the comparative examples are both manufactured according to the following method.

[0135] 1. Manufacturing of positive electrode sheets According to Table 1 below, the positive electrode active material, acetylene black as a conductive agent, and polyvinylidene fluoride (PVDF) as a binder are dissolved in N-methylpyrrolidone (NMP) as a solvent in a weight ratio of 90:5:5, and the interface passivation agent of the present invention (if any) is added thereto, and the mixture is thoroughly stirred to obtain a positive electrode slurry. 2 The coated aluminum foil positive electrode current collector was uniformly coated with the amount of the coated aluminum foil, dried, and cold pressed. 2 Cut into positive electrode sheets.

[0136] In the following tables, when the positive electrode material layer or the negative electrode material layer includes an interfacial passivator, the content of the interfacial passivator is in weight percent (wt%) of the positive electrode material layer or the negative electrode material layer, respectively, on a dry basis; when the electrolyte includes an interfacial passivator, the content of the interfacial passivator is in weight percent of the total weight of the electrolyte.

[0137] [Table 1]

[0138] 2. Manufacturing of negative electrode sheets According to Table 2 below, each negative electrode active material, acetylene black as a conductive agent, styrene butadiene rubber (SBR) as a binder, and sodium carboxymethyl cellulose (CMC) as a thickener were dissolved in deionized water as a solvent in a weight ratio of 90:4:4:2, and the interfacial passivation agent of the present invention (if any) was added thereto, and the mixture was thoroughly stirred to obtain a negative electrode slurry. Next, the negative electrode slurry was added one or more times to obtain a 0.12 mg / mm 2 The negative electrode current collector copper foil is uniformly coated with the amount of the coating, dried, cold pressed, and cut into 60,000mm 2 A negative electrode sheet of

[0139] [Table 2] Here, " / " indicates "and", i.e., "calcium bis(nonafluorobutylsulfonyl)imide / magnesium perchlorate" means "calcium bis(nonafluorobutylsulfonyl)imide and magnesium perchlorate". Similar expressions below have the same meaning.

[0140] 3. Electrolyte production According to Table 3 below, in a glove box under an argon gas atmosphere (HO<0.1 ppm, O<0.1 ppm), organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed uniformly in a volume ratio of 3 / 7. 12.5 wt. % lithium hexafluorophosphate (LiPF) was added to the mixed organic solvent to dissolve the electrolyte salt. 1 wt. % 1,3-propanesulfonic acid lactone (PS), 0.5% ethylene sulfate (DTD), 0.5% vinylene carbonate (VC), and 2% fluoroethylene carbonate (FEC) were added as additives, along with the present interface passivator (if any), and the mixture was stirred uniformly to obtain an electrolyte solution. The resulting weight percentages are calculated based on the total weight of the electrolyte solution.

[0141] [Table 3]

[0142] 4. Secondary battery manufacturing (1) As shown in Table 4 below, a positive electrode sheet, a separator, and a negative electrode sheet are stacked in order, and a separator is placed between the positive and negative electrodes to tightly seal them and serve as an insulator. The separator is then wound up to obtain an electrode assembly. The electrode assembly is placed in a battery housing, dried, and then an electrolyte solution is injected in an amount of 2.4 g / Ah to obtain a newly manufactured secondary battery. (2) The secondary battery is formed by sealing under normal pressure at a formation temperature of 45°C, a current of 0.1C, and a voltage of 3-4.3V, and then allowed to stand to finally produce secondary batteries according to the present invention and comparative examples.

[0143] [Table 4-1] [Table 4-2]

[0144] 5. Test 5.1 Ternary Layer Detection The ternary layer can be detected by means commonly known in the art, such as solid-state nuclear magnetism, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, or a combination of the above means.

[0145] 5.2 Internal resistance of the initial secondary battery and the internal resistance of the secondary battery after 1000 cycles (1) The secondary battery (hereinafter referred to as "new battery") manufactured in the above steps is charged at a constant current of 1 C to 4.3 V at 45°C, then charged at a constant voltage of 4.3 V until the current becomes less than 0.05 C, and then the lithium-ion battery is discharged at a constant current of 1 C to 3.0 V, which constitutes one charge-discharge process (i.e., one cycle). The above cycle is repeated 1000 times to obtain a secondary battery that has been cycled 1000 times at 45°C (hereinafter referred to as "battery with 1000 cycles at 45°C"). (2) At 25°C, the newly manufactured batteries and the batteries that had been cycled 1000 times at 45°C were charged at a constant current of 1C to 4.3V, then charged at a constant voltage of 4.3V until the current fell below 0.05C, and discharged at 1C for 30 minutes, adjusting the charge level of the secondary batteries to 50% SOC. Next, the positive and negative pens of a TH2523A AC internal resistance tester (Tonghui Electronics) were placed in contact with the positive and negative terminals of the two secondary batteries under test, respectively, and the internal resistance values ​​of the batteries were read via the internal resistance tester, which were taken as the internal resistance of the initial secondary battery and the internal resistance of the secondary battery after 1000 cycles, respectively.

[0146] 5.3 Capacity retention after 1000 cycles at 45°C The test was performed using a Wuhan Blue Battery. At 45°C, the secondary battery was charged at a constant current of 1C to 4.3V, then charged at a constant voltage of 4.3V until the current fell below 0.05C. The lithium-ion battery was then discharged at a constant current of 1C to 3.0V. This constituted one charge-discharge cycle (i.e., one cycle, or the first cycle), and the discharge capacity of the first cycle was recorded. This cycle was repeated 1000 times, and the discharge capacity of the 1000th cycle was recorded. The capacity retention rate of the secondary battery after 1000 cycles was calculated using the following formula: Capacity retention (%) of a lithium-ion battery after 1000 cycles at 45°C = (discharge capacity at 1000th cycle / discharge capacity at first cycle) x 100%.

[0147] 5.4 Capacity retention after 300 days storage at 60℃ At 25°C, the lithium-ion battery was charged at a constant current of 1C until the voltage reached 4.3V, then charged at a constant voltage of 0.05C at 4.3V, and then discharged at a constant current of 1C until the voltage reached 3.0V. This constitutes one charge-discharge cycle (i.e., one cycle, or the first cycle). At this point, the discharge capacity of the secondary battery was tested for the first cycle. Next, the fully charged secondary battery was placed in a thermostatic box at 60°C and stored for 300 days, and the discharge capacity after 300 days of storage was tested. Capacity retention (%) after storing a lithium-ion battery at 60°C for 300 days = (discharge capacity after 300 days of storage / discharge capacity of the first cycle) x 100%.

[0148] The above test results are recorded in Table 5-9 below.

[0149] [Table 5]

[0150] As can be seen from the table above, the secondary battery in Comparative Example 1, which uses LFP as the positive electrode active material and a silicon carbon composite as the negative electrode active material, does not contain the interfacial passivator of the present invention, and the cycle life of the secondary battery is short. In contrast, the secondary batteries in Examples 1-2 and 4-5 contain the interfacial passivator of the present invention, which effectively improves capacity retention, reduces battery impedance, and improves battery performance.

[0151] Regardless of the theory, the poor cycle life of Comparative Example 1 is primarily due to the silicon-carbon composite material contained in the negative electrode undergoing large volume changes during the lithium absorption / desorption process during charge / discharge cycling, resulting in cracking and regeneration of the interface components. After multiple cycles, the interface components thickened. Consequently, the secondary battery of Comparative Example 1 exhibited high internal resistance after 1,000 cycles, and the active lithium was consumed due to interface cracking and regeneration, resulting in a rapid decrease in capacity retention during cycling. Furthermore, the fully charged silicon-based negative electrode exhibited high interface activity, resulting in excessive electrolyte consumption, resulting in a low capacity retention after 300 days of storage at 60°C. However, in the secondary battery of the present application, the included interface passivator formed a ternary interface passivation layer at the interface between the negative electrode material layer and the electrolyte during charge / discharge cycling, thereby reducing the reactivity of the negative electrode interface. Furthermore, the above advantages of the secondary battery of the present application became more pronounced with increasing cycle count.

[0152] Furthermore, from the data in the above table, it can be seen that the secondary battery of Example 3 contains cobalt salt and the secondary battery of Example 6 contains manganese salt, which do not achieve the beneficial effects of Examples 1-2 and 4-5, and instead worsen battery performance.

[0153] [Table 6]

[0154] As can be seen from the table above, the secondary battery in Comparative Example 2, in which the positive electrode active material is NCM811 and the negative electrode active material is a silicon carbon composite, exhibits poor cycle life. However, the secondary batteries in Examples 7-8 (in which the negative electrode material layer contains an interfacial passivator) and 10-11 (in which the electrolyte contains an interfacial passivator) exhibit significantly improved cycle performance.

[0155] Regardless of the theory, the reason why the secondary battery of Comparative Example 2 has such a poor cycle life is that in addition to the large volume change of the silicon-carbon material itself and the instability of the NCM811 structure, the migration and catalytic action of transition metal ions are also important factors that lead to interfacial instability.

[0156] In Examples 7-8 and 10-11 of the present application, by including an interfacial passivation agent, such a multivalent salt can form an interfacial passivation layer with silicon, stabilizing the electrode-electrolyte interface, effectively improving the capacity retention rate of the secondary battery, reducing the impedance of the secondary battery, and improving the performance of the secondary battery.

[0157] The inclusion of a cobalt salt in the negative electrode of Example 9 and a manganese salt in the electrolyte of Example 12 do not improve cycle performance.

[0158] [Table 7]

[0159] In Comparative Example 2, the positive electrode secondary battery made of NCM811 uses an unmodified silicon carbon composite material, and the cycle life of the secondary battery is poor.

[0160] The secondary batteries of Examples 13, 15-16 and 18-19 contain calcium, magnesium, aluminum and beryllium interfacial passivation agents, which effectively improve the capacity retention rate, reduce the battery impedance and improve the battery performance.

[0161] The inclusion of nickel, cobalt, and manganese salts in Examples 14, 17, and 20 deteriorates the performance of the secondary battery.

[0162] [Table 8]

[0163] In Comparative Example 2, the secondary battery in which the positive electrode material is NCM811 does not use the interface passivator of the present invention, and the cycle life of the secondary battery is poor.

[0164] The secondary batteries of Examples 21-22 contain organic or inorganic salts of calcium, magnesium, aluminum, or beryllium, resulting in significantly improved cycle performance. The secondary batteries of Examples 23-27 contain nickel, cobalt, or manganese salts, resulting in significant degradation of the secondary battery performance. In Examples 24 and 25, although the negative electrode contains cobalt, which degrades performance, the positive electrode and electrolyte contain beryllium, magnesium, or aluminum, which slightly reduces the degradation.

[0165] [Table 9]

[0166] In Example 28, the negative electrode active material was surface-coated with aluminum phosphate, which had a certain effect on improving battery performance compared to Comparative Example 2, but the degree of improvement was small. The coating layer structure was not stable enough to interact with the negative electrode active material to form the ternary layer described in this application, and it was difficult to avoid cracking of the interface layer even after the coating layer was cycled multiple times, resulting in very limited performance improvement.

[0167] The addition of an interfacial passivation agent calcium salt to the negative electrode material of Example 7 significantly improved the overall performance of the secondary battery compared to Comparative Example 2, and the degree of improvement was much higher than that of Example 28. The addition of two types of multivalent salts to the materials of Examples 29 and 30 significantly improved the performance of the secondary battery compared to the addition of a single multivalent salt to Example 7. This indicates that the effect of the combined additives is superior to the improvement effect of a single salt.

[0168] [Table 10]

[0169] Compared with Example 2, Examples 31-50 investigated the addition of different amounts of multivalent salt additives to the positive electrode, negative electrode, and electrolyte, respectively. The results show that the secondary batteries of Examples 31-50 contain organic or inorganic salts of calcium, magnesium, aluminum, and beryllium, which significantly improves battery cell performance compared to Comparative Example 2, which does not contain any additives.

[0170] The present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea within the scope of the technical solution of the present application and that achieves similar effects is included within the technical scope of the present application. Furthermore, various modifications of the embodiments that a person skilled in the art can conceive of, and other forms constructed by combining some of the components of the embodiments, are also included within the scope of the present application, as long as they do not deviate from the gist of the present application. [Explanation of symbols]

[0171] 1 battery pack 2 Upper box 3 Lower box 4 Battery Module 5 Secondary battery 51 Housing 52 Electrode Assembly 53 Top cover assembly

Claims

1. A secondary battery comprising: a negative electrode sheet including a negative electrode material layer; a positive electrode sheet including a positive electrode material layer; and an electrolyte; wherein the positive electrode material layer includes an interface passivator, the interface passivator being a compound containing element E, wherein the element E is selected from lithium, sodium, beryllium, magnesium, potassium, aluminum, gallium, and germanium.

2. 2. The secondary battery according to claim 1, wherein the negative electrode layer has an A-D-E ternary layer on its surface, wherein A is selected from alkali metal elements and is different from E, and D is silicon or carbon, and the A-D-E ternary layer is formed by the action of the interfacial passivation agent on the surface of the negative electrode layer during at least one charging process of the secondary battery.

3. 3. The secondary battery according to claim 1, wherein the interface passivation agent is selected from at least one of compounds of beryllium, magnesium, aluminum, and gallium.

4. The interfacial passivator may be a substituted or unsubstituted C １－２０ carboxylic acid salts, and the substituent is selected from at least one of C １－６ Alkyl group, C ２－６ Cycloalkyl group, hydroxyl group, amino group, oxo group, acyl group, C １－６ 3. The secondary battery according to claim 1, wherein the E is one or more selected from the group consisting of alkylthio groups, phenyl groups, benzoylthio groups, phenylthio groups, and phenoxy groups, amino acid salts, enoates, phosphates, sulfates, sulfonylimides, sulfonates, benzoates, phthalates, acetylacetonates, inorganic oxyacid salts, and double salts of cations containing at least two of the E groups.

5. 3. The secondary battery according to claim 1, wherein the interface passivator is mixed into the positive electrode material layer by doping.

6. 3. The secondary battery of claim 2, wherein the A-D-E ternary layer is selected from Li-Si-Mg, Li-Si-Be, Li-Si-Al, Li-C-Mg, Li-C-Be, Li-C-Al, Na-Si-Mg, Na-Si-Be, Na-Si-Al, Na-C-Mg, Na-C-Be, Na-C-Al ternary layers, and combinations thereof.

7. 3. The secondary battery according to claim 2, wherein the positive electrode material layer contains 0.001% by weight to 20% by weight of the interface passivator, based on the total weight of the positive electrode material layer, before the at least one charging.

8. 3. The secondary battery according to claim 1, wherein the negative electrode layer contains a negative electrode active material, and the negative electrode active material has a D50 of 1 μm to 20 μm.

9. the negative electrode material layer contains a negative electrode active material, and the negative electrode active material has a Span value of 0.9 to 1.8; where: and 3. The secondary battery according to claim 1, wherein D90, D10, and D50 represent particle sizes corresponding to cumulative distribution rates of 90%, 10%, and 50%, respectively.

10. A method for manufacturing a secondary battery, i) providing a negative electrode sheet including a negative electrode material layer, a positive electrode sheet including a positive electrode material layer, and an electrolyte to manufacture an uncycled secondary battery, wherein the positive electrode material layer includes an interface passivator, the interface passivator being a compound including an element E, and the element E being selected from lithium, sodium, beryllium, magnesium, potassium, aluminum, gallium, or germanium; ii) charging and discharging the uncycled secondary battery for at least one cycle to form an A-D-E ternary layer to obtain the secondary battery, wherein A is selected from alkali metal elements and is different from E, and D is silicon or carbon.

11. 11. The method of claim 10, wherein the interfacial passivator is selected from at least one of compounds of beryllium, magnesium, aluminum, and gallium.

12. The interfacial passivator may be a substituted or unsubstituted C １－２０ carboxylic acid salts, and the substituent is selected from at least one of C １－６ Alkyl group, C ２－６ Cycloalkyl group, hydroxyl group, amino group, oxo group, acyl group, C １－６ 12. The method according to claim 10 or 11, wherein the non-transition metal cation is one or more selected from the group consisting of alkylthio groups, phenyl groups, benzoylthio groups, phenylthio groups and phenoxy groups, amino acid salts, enoates, phosphates, sulfates, sulfonylimides, sulfonates, benzoates, phthalates, acetylacetonates, inorganic oxyacid salts, and double salts containing at least two of the non-transition metal cations.

13. 12. The method of claim 10 or 11, wherein in step i) the interfacial passivation agent is mixed into the positive electrode material layer by doping.

14. A battery module comprising the secondary battery according to claim 1 .

15. A battery pack comprising the battery module according to claim 14.

16. An electrical device comprising the secondary battery of claim 1.

Images