Battery cell, lithium ion battery and electronic device comprising same

Abstract

The application discloses a battery cell, a lithium ion battery containing the battery cell and an electronic device. The battery cell adopts a two-injection scheme to inject electrolyte, and the electrolyte comprises one-injection electrolyte and two-injection electrolyte. The additive in the two-injection electrolyte comprises an active oxygen trapping agent. The active oxygen trapping agent comprises a first component and a second component. The first component is vinyl sulfite, and the second component comprises a primary amine compound and / or a compound containing a disulfide bond. The positive electrode material layer in the positive electrode sheet of the battery cell comprises lithium iron phosphate and a positive electrode lithium supplementing agent, and the positive electrode lithium supplementing agent comprises Li5FeO4. The battery cell has obviously improved gas production, and can have excellent high-temperature cycle performance and high-temperature storage stability.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of electric core and lithium ion battery and electronic equipment containing it. BACKGROUND

[0002] With the market demand for energy storage battery, the demand for long life of lithium iron phosphate energy storage battery is growing, in order to further improve the long life of lithium iron phosphate energy storage battery, the researchers in the related field are constantly exploring the technology of battery prelithiation.

[0003] The technology of battery prelithiation on the market mainly includes positive electrode prelithiation and negative electrode prelithiation. Due to the high processing difficulty of negative electrode prelithiation, it is difficult to develop due to factors such as existing equipment and processing environment, etc. At present, negative electrode prelithiation cannot be effectively implemented, and positive electrode prelithiation is mainly used for prelithiation of battery on the market. As for positive electrode prelithiation, there are two directions of using lithium-rich lithium nickelate lithium supplement material (chemical formula LiNiO2, referred to as LNO) and lithium-rich lithium iron supplement material (chemical formula Li5FeO4, referred to as LFO). Among them, LNO supplement material is gradually replaced by LFO supplement material due to its high price. However, LFO supplement material as a lithium supplement agent still has the problem of serious gas production, which needs to be solved urgently. SUMMARY

[0004] In order to solve the problem of serious gas production and poor high-temperature cycle performance and high-temperature storage stability when LFO is used as a positive electrode lithium supplement agent in the existing battery, the present application provides a kind of electric core and lithium ion battery and electronic equipment containing it. The gas production problem of the battery is obviously improved, and excellent high-temperature cycle performance and high-temperature storage stability can be considered.

[0005] In order to achieve the above purpose, the present application adopts the following technical scheme.

[0006] In the first aspect, the present application provides a kind of electric core, the electric core uses one-two injection scheme to inject electrolyte, the electrolyte includes one injection electrolyte and two injection electrolyte;

[0007] Among them, the additive in the two injection electrolyte includes active oxygen trapping agent;The active oxygen trapping agent includes first component and second component, the first component is ethylene sulfite, and the second component includes primary amine compound and / or compound containing disulfide bond;

[0008] The positive electrode material layer in the positive electrode sheet of the battery includes lithium iron phosphate and positive electrode lithium supplement agent, and the positive electrode lithium supplement agent includes Li5FeO4.

[0009] In the second aspect, the present application provides a lithium ion battery, which includes the electric core as described above.

[0010] In a third aspect, the present application provides an electronic device comprising the lithium ion battery as described above.

[0011] The positive progress effect of the present application is that:

[0012] The present application aims at the problems of serious gas production and poor cycle performance and high-temperature stability of the lithium ion battery with LFO as the positive lithium supplement agent. The electrolyte is injected by a two-injection scheme, and a composite active oxygen scavenger is added in the second injection electrolyte. The obtained battery cell has the following advantages:

[0013] (1) The gas production problem is significantly improved: after 60 days of storage at 60℃, the gas production percentage can be less than 13%, and even less than 7%;

[0014] (2) Excellent high-temperature storage stability: after 60 days of storage at 60℃, the high-temperature storage capacity recovery rate can reach more than 97.3%, and even more than 97.7%;

[0015] (3) And excellent high-temperature cycle performance: the capacity retention rate after 500 cycles at 45℃ can reach more than 95.8%, and even more than 97%. DETAILED DESCRIPTION

[0016] The present application will be further described by way of examples, but the present application is not limited to the scope of the examples. In the following examples, the experimental methods not specified in the specific conditions are selected according to the conventional methods and conditions, or according to the instructions of the goods.

[0017] Battery cell

[0018] In the battery cell provided in the first aspect of the present application, the battery cell is injected with electrolyte by a two-injection scheme, and the electrolyte comprises a first injection electrolyte and a second injection electrolyte;

[0019] The additive in the second injection electrolyte comprises an active oxygen scavenger; the active oxygen scavenger comprises a first component and a second component, the first component is vinyl sulfite, and the second component comprises a primary amine compound and / or a compound containing a disulfide bond;

[0020] The positive material layer in the positive electrode sheet of the battery cell comprises lithium iron phosphate and a positive lithium supplement agent, and the positive lithium supplement agent comprises Li5FeO4.

[0021] In some optional embodiments, the primary amine compound is selected from one or more of p-phenylenediamine, benzylamine, phenethylamine, 1,2-phenylenediamine, propylenediamine, and butylenediamine.

[0022] In some alternative embodiments, the disulfide bond-containing compound is selected from one or more of lithium thiosulfate, lithium dithionate, lithium dithionite, and lithium thiosulfate derivatives.

[0023] In some alternative embodiments, the active oxygen scavenger is present in an amount of 1.5% to 9%, preferably 2% to 8%, more preferably 4% to 6%, by mass percentage of the bi- injection electrolyte.

[0024] In some alternative embodiments, the ethylene sulfite is present in an amount of 1% to 6%, for example 2% or 4%, by mass percentage of the bi-injection electrolyte.

[0025] In some alternative embodiments, the primary amine compound is present in an amount of 0.5% to 4%, for example 2% or 3%, by mass percentage of the bi-injection electrolyte.

[0026] In some alternative embodiments, the disulfide bond-containing compound is present in an amount of 0.5% to 4%, for example 2%, by mass percentage of the bi-injection electrolyte.

[0027] In some preferred embodiments, the active oxygen scavenger is ethylene sulfite and a primary amine compound, and the mass ratio of the ethylene sulfite to the primary amine compound is 1 : (0.2 to 3), preferably 1 : (0.5 to 2), for example 1 : 1.

[0028] In some specific embodiments, the active oxygen scavenger is ethylene sulfite and p- phenylenediamine; the ethylene sulfite is present in an amount of, for example, 4%, and the p- phenylenediamine is present in an amount of, for example, 2%.

[0029] In some specific embodiments, the active oxygen scavenger is ethylene sulfite and benzylamine; the ethylene sulfite is present in an amount of, for example, 4%, and the benzylamine is present in an amount of, for example, 2%.

[0030] In some specific embodiments, the active oxygen scavenger is ethylene sulfite and phenethylamine; the ethylene sulfite is present in an amount of, for example, 4%, and the phenethylamine is present in an amount of, for example, 2%.

[0031] In some specific embodiments, the active oxygen scavenger is ethylene sulfite and 1,2- phenylenediamine; the ethylene sulfite is present in an amount of, for example, 4%, and the 1,2- phenylenediamine is present in an amount of, for example, 2%.

[0032] In some specific embodiments, the active oxygen scavenger is ethylene sulfite and propylene diamine; the ethylene sulfite is present in an amount of, for example, 4%, and the propylene diamine is present in an amount of, for example, 2%.

[0033] In some embodiments, the active oxygen scavenger is vinyl sulfite and butanediamine; the content of the vinyl sulfite is, for example, 4%, and the content of the butanediamine is, for example, 2%.

[0034] In some preferred embodiments, the active oxygen scavenger is vinyl sulfite and a disulfide bond-containing compound, and the mass ratio of the vinyl sulfite and the disulfide bond-containing compound is 1 : (0.2-3), preferably 1 : (0.5-2), for example, 1 : 1.

[0035] In some embodiments, the active oxygen scavenger is vinyl sulfite and lithium thiosulfate; the content of the vinyl sulfite is, for example, 4%, and the content of the lithium thiosulfate is, for example, 2%.

[0036] In some embodiments, the active oxygen scavenger is vinyl sulfite and lithium dithionite; the content of the vinyl sulfite is, for example, 4%, and the content of the lithium dithionite is, for example, 2%.

[0037] In some preferred embodiments, the active oxygen scavenger is vinyl sulfite, a primary amine compound, and a disulfide bond-containing compound, and the mass ratio of the vinyl sulfite, the primary amine compound, and the disulfide bond-containing compound is 1 : (0.5-1) : (0.5-1), for example, 1 : 1 : 1.

[0038] In some embodiments, the active oxygen scavenger is vinyl sulfite, p-phenylenediamine, and lithium thiosulfate; the content of the vinyl sulfite is, for example, 2%, the content of the p-phenylenediamine is, for example, 2%, and the content of the lithium thiosulfate is, for example, 2%.

[0039] In some alternative embodiments, the lithium salt in the co-injection electrolyte is selected from one or more of lithium hexafluorophosphate, lithium bisfluorosulfonimide, and lithium bis(trifluoromethylsulfonyl)imide.

[0040] In some embodiments, the lithium salt in the co-injection electrolyte is lithium hexafluorophosphate.

[0041] In some alternative embodiments, the solvent in the co-injection electrolyte is selected from one or more of ethylene carbonate (EC), propylene carbonate, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, propyl formate, propyl propionate, and ethyl butyrate.

[0042] In some embodiments, the solvent in the co-injection electrolyte is ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate, and the mass ratio of the ethylene carbonate, ethyl methyl carbonate, and dimethyl carbonate is, for example, 3 : 3 : 4.

[0043] In some alternative embodiments, the additive in the two-shot electrolyte further comprises vinylene carbonate.

[0044] In some preferred embodiments, the content of the vinylene carbonate is preferably 5% to 12%, for example 10%.

[0045] In some preferred embodiments, the additive in the two-shot electrolyte further comprises fluoroethylene carbonate (FEC) and / or vinyl ethylene carbonate (VEC).

[0046] In some alternative embodiments, the lithium salt in the one-shot electrolyte is selected from one or more of lithium hexafluorophosphate, lithium bisfluorosulfonylimide and lithium bis(trifluoromethylsulfonyl)imide.

[0047] In some specific embodiments, the lithium salt in the one-shot electrolyte is lithium hexafluorophosphate.

[0048] In some alternative embodiments, the solvent in the one-shot electrolyte is selected from one or more of vinyl carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, propyl formate, propyl propionate and ethyl butyrate.

[0049] In some specific embodiments, the solvent in the one-shot electrolyte is vinyl carbonate, ethyl methyl carbonate and dimethyl carbonate, for example in a mass ratio of 3:3:4.

[0050] In some alternative embodiments, the additive in the one-shot electrolyte is selected from one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC) and vinyl sulfate (DTD).

[0051] In some specific embodiments, the additive in the one-shot electrolyte is vinylene carbonate, fluoroethylene carbonate and vinyl sulfate, for example in a mass ratio of 3:1:1.

[0052] In some alternative embodiments, the content of the lithium iron phosphate is 93% or more, for example 94%, the percentage being a mass percentage of the positive electrode material layer.

[0053] In some alternative embodiments, the content of the Li5FeO4 is 0.5% to 5%, for example 3%, the percentage being a mass percentage of the positive electrode material layer.

[0054] In some alternative embodiments, the sum of the content of the lithium iron phosphate and the Li5FeO4 is 98% or less, for example 97%, the percentage being a mass percentage of the positive electrode material layer.

[0055] In some alternative embodiments, the positive lithium supplement further comprises LiNiO2.

[0056] In some preferred embodiments, the mass ratio of the Li5FeO4 and the LiNiO2 is (4-5):1.

[0057] In some embodiments, the method for preparing the battery cell comprises the following steps: winding the positive electrode sheet, the separator and the negative electrode sheet in sequence, injecting a first electrolyte, performing formation and aging, injecting a second electrolyte, and performing heat sealing and capacity distribution.

[0058] In some preferred embodiments, the upper limit voltage of the formation is higher than 3.95V, preferably higher than 4.05V.

[0059] Positive electrode sheet

[0060] In some alternative embodiments, the positive electrode material layer further comprises a binder.

[0061] The type of the binder is not particularly limited and can be optionally selected from polyvinylidene fluoride, polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid (PAA), ethylene-propylene-diene terpolymer and sulfonated products thereof, styrene butadiene rubber (SBR), fluororubber, and various copolymers, for example, PVDF.

[0062] In some alternative embodiments, the content of the binder is 1%-10%, for example, 1.5% or 1.8%, and the percentage is the percentage of the total mass of the positive electrode material layer.

[0063] In some alternative embodiments, the positive electrode material layer further comprises a conductive agent.

[0064] The type of the conductive agent is not particularly limited and is an agent for ensuring good charge and discharge performance of the electrode. It can be optionally selected from graphite-based materials such as natural graphite and artificial graphite, carbon black-based materials such as carbon black SP, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal cracking carbon black, conductive fibers such as carbon fibers and metal fibers, metal powders such as fluorinated carbon powder, aluminum powder, nickel powder, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium dioxide, and polyphenylene derivatives.

[0065] In a specific embodiment, the conductive agent is conductive carbon SP.

[0066] In some alternative embodiments, the content of the conductive agent is 0.2%-3%, such as 0.75% or 1.2%, the percentage being the percentage of the total mass of the positive electrode material layer.

[0067] In some specific embodiments, the mass ratio of the lithium iron phosphate, the lithium supplementing agent, the conductive agent and the binder in the positive electrode material layer is 94:3:1.2:1.8.

[0068] In the present application, the positive electrode sheet of the battery cell comprises a positive electrode current collector, and the positive electrode material layer is arranged on at least one surface of the positive electrode current collector.

[0069] The positive electrode current collector can be a conventional positive electrode current collector in the art. The positive electrode current collector serves as a substrate for supporting the positive electrode material layer, and is usually a metal foil having a thickness of 3-500 microns. The material is not particularly limited as long as it has high electrical conductivity and does not react chemically in the system of the secondary battery. For example, it can be a foil formed after surface treatment of nickel, titanium, aluminum, nickel, silver, stainless steel, carbon, etc. The positive electrode current collector usually has a smooth surface, but can also have fine lines or the like formed on the surface to improve the adhesion between the positive electrode material layer and the positive electrode current collector. In addition to the foil, the positive electrode current collector can also be in the form of a film, a mesh, a porous material, a foam or a non-woven fabric, or any combination of one or more thereof. Generally, the positive electrode current collector is an aluminum foil.

[0070] In some embodiments, the method for preparing the positive electrode sheet comprises: coating the positive electrode slurry obtained by sufficiently stirring and mixing the components of the positive electrode material layer in a solvent on at least one surface of the positive electrode current collector, drying, and roll pressing to compact, to obtain the positive electrode sheet.

[0071] In some alternative embodiments, the solvent comprises one or more of N-methyl pyrrolidone (NMP), dimethyl carbonate, ethylene carbonate and diethylene carbonate, such as NMP.

[0072] Negative electrode sheet

[0073] In the present application, the negative electrode sheet of the battery cell comprises a negative electrode current collector and a negative electrode material layer arranged on at least one surface of the negative electrode current collector.

[0074] In the present application, the negative active material in the negative electrode material layer can be a negative active material of a lithium ion battery as conventional in the art, and the negative active material of the lithium ion battery can use a compound capable of reversibly intercalating and deintercalating lithium, and specific examples include, but are not limited to, carbon materials such as crystalline carbon (natural graphite and artificial graphite, etc.), amorphous carbon, carbon-coated graphite, and resin-coated graphite, or oxide materials such as indium oxide, silicon oxide, tin oxide, lithium titanate, zinc oxide, lithium oxide, and the like, and can also be lithium metal or a metal material capable of forming an alloy with lithium; wherein the metal material capable of forming an alloy with lithium is, for example, Cu, Sn, Si, Co, Mn, Fe, Sb, and Ag. A binary or ternary alloy containing these metals and lithium can also be used as the negative active material. These negative active materials can be used alone or in combination of two or more. From the perspective of high energy density, a carbon material such as graphite can also be used in combination with Si, Si alloy, Si oxide, or the like.

[0075] In some embodiments, the negative active material includes any one or a combination of at least two of soft carbon, hard carbon, artificial graphite, natural graphite, silicon, a silicon oxide compound, a silicon carbon compound, or lithium titanate.

[0076] In a specific embodiment, the negative active material is artificial graphite.

[0077] In some embodiments, the negative electrode material layer further includes a thickening agent.

[0078] The addition of the thickening agent can increase the system viscosity of the components in the negative electrode slurry, and the thickening agent can be a thickening agent conventionally used in the preparation of negative electrode sheets in the art, such as sodium carboxymethyl cellulose (CMC).

[0079] In some embodiments, the negative electrode material layer further includes a conductive agent.

[0080] The conductive agent is not particularly limited as long as it has conductivity without causing chemical changes in the battery. For example, specific examples include: graphite, such as natural graphite or artificial graphite; carbon-based materials, such as carbon black (Super P), acetylene black, ketjen black, slot black, furnace black, lamp black, thermal carbon black, or carbon fiber; metal powder or metal fiber, such as copper, nickel, aluminum, or silver; conductive whiskers, such as zinc oxide whiskers or potassium titanate whiskers; conductive metal oxides, such as titanium dioxide; or conductive polymers, such as polyphenylene derivatives, and the like.

[0081] In some embodiments, the negative electrode material layer further includes a binder.

[0082] The binder is not particularly limited and can be selected from polyvinylidene fluoride, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid (PAA), ethylene-propylene-diene terpolymer and sulfonated products thereof, styrene butadiene rubber (SBR), fluororubber, and various copolymers, such as PAA and SBR, for example.

[0083] In some embodiments, the mass ratio of the negative active material, the conductive agent, the binder, and the thickening agent in the negative electrode material layer is 97.2:0.5:1.8:0.5.

[0084] In the present application, the negative current collector can be a conventional negative current collector in the art. The negative current collector serves as a substrate to support the negative electrode material layer and is typically a metal foil having a thickness of 3-500 microns. The material is not particularly limited as long as it has high electrical conductivity and does not chemically react in the system of the secondary battery. For example, it can be a foil formed after surface treatment of nickel, titanium, aluminum, nickel, silver, stainless steel, carbon, etc. The negative current collector typically has a smooth surface, but fine lines or the like can be formed on the surface to improve the adhesion between the negative electrode material layer and the negative current collector. In addition to the foil, the negative current collector can also be in the form of a film, a mesh, a porous material, a foam, or a non-woven fabric, or any combination of one or more thereof. Generally, the negative current collector is a copper foil.

[0085] In some embodiments, the method for preparing the negative electrode sheet comprises the following steps: coating the negative electrode slurry obtained by thoroughly mixing the components of the negative electrode material layer in a solvent on at least one surface of the negative current collector, drying, cold pressing, and slitting to obtain the negative electrode sheet.

[0086] Separator

[0087] In the present application, the separator in the battery cell can be a conventional separator used in the art.

[0088] In some optional embodiments, the separator can be a polypropylene film or a polyethylene film.

[0089] The air permeability of the separator can be 180-380 s / 100 mL.

[0090] The porosity of the separator can be 30%-50%.

[0091] The thickness of the separator can be 9-18 microns.

[0092] In a specific embodiment, the separator is a polyethylene film; the thickness of the separator is 11 μm; the air permeability of the separator is 230 s / 100 mL; and the porosity of the separator is 40%.

[0093] Lithium ion battery

[0094] In the second aspect of the present application, the lithium ion battery comprises the battery cell as described above.

[0095] In the present application, the lithium ion battery is generally a square hard-shell battery, a soft-pack battery, and a cylindrical battery.

[0096] In the present application, the lithium ion battery can be prepared by a conventional method in the art.

[0097] Electronic device

[0098] In the third aspect of the present application, the electronic device comprises the lithium ion battery as described above.

[0099] Exemplarily, the electronic device of the present application can be, but is not limited to, a mobile device (such as a mobile phone, a tablet computer, a notebook computer, a video recorder, a portable printer / copier, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, and a backup power supply, etc.

[0100] On the basis of common general knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily, i.e. to obtain each preferred example of the present application. The present application is further illustrated by the following examples, but the present application is not limited in scope by the examples described. The experimental methods in the following examples, for which no specific conditions are indicated, are carried out according to conventional methods and conditions, or according to the instructions of the commercial suppliers. The reagents and materials used in the present application are commercially available, unless otherwise specified.

[0101] Example 1

[0102] The preparation of the battery cell comprises the following steps:

[0103] (1) Preparation of the positive electrode sheet: the positive electrode active material lithium iron phosphate, polyvinylidene fluoride (PVDF), conductive carbon SP, and lithium supplement LFO are mixed uniformly in a solvent NMP (45 parts by mass) according to the mass ratio of lithium iron phosphate: PVDF: conductive carbon SP: lithium supplement LFO = 94: 1.8: 1.2: 3 (100 parts by mass in total), the obtained slurry is coated on an aluminum foil, and the positive electrode sheet is obtained after drying.

[0104] (2) Preparation of the negative electrode sheet: the negative electrode active material artificial graphite, polyacrylic acid (PAA), CMC, conductive carbon SP, and SBR were mixed uniformly in a solvent deionized water (50 parts by mass) according to the mass ratio of graphite: PAA: CMC: conductive carbon SP: SBR = 97.2: 1.3: 0.5: 0.5: 0.5, and the obtained slurry was coated on a copper foil, and the negative electrode sheet was obtained after drying.

[0105] (3) Preparation of the electrolyte: in an argon atmosphere glove box with oxygen and water content less than 1 ppm, ethylene carbonate (EC), methyl ethyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed according to the mass ratio of 3:3:4 to obtain a mixed solvent, 1 mol / L lithium hexafluorophosphate was added to the mixed solvent as a conductive salt, and the mixture was dissolved and mixed uniformly to obtain an initial salt solution without additives.

[0106] Preparation of the first injection electrolyte: the initial salt solution was added with additives: vinylene carbonate (VC, content of 3%), fluoroethylene carbonate (FEC, content of 1%), and vinyl sulfate (DTD, content of 1%), and the mixture was uniformly mixed to obtain the first injection electrolyte.

[0107] Preparation of the second injection electrolyte: the initial salt solution was added with additives: vinylene carbonate (VC, content of 10%) and active oxygen scavenger; wherein the active oxygen scavenger was vinyl sulfite (ES, content of 4%) and p-phenylenediamine (content of 2%), and the mixture was uniformly mixed to obtain the second injection electrolyte.

[0108] (4) Preparation of the battery cell: the positive electrode sheet, the separator, and the negative electrode sheet were sequentially stacked and wound to prepare a battery cell, which was packaged with an aluminum plastic film, the capacity of the battery cell was designed to be 40 Ah, 119 g of the first injection electrolyte was injected, and the battery cell was formed, aged, and then sealed with the second injection electrolyte, 21 g in total, to obtain the battery cell. The separator was a polyethylene film, the thickness of the separator was 11 μm, the air permeability of the separator was 230 s / 100 mL, and the porosity of the separator was 40%.

[0109] Examples 2-6

[0110] Examples 2-6 and Example 1 differ only in that benzylamine, phenethylamine, 1,2-phenylenediamine, propylenediamine, and butylenediamine are respectively used to replace p-phenylenediamine in the second injection electrolyte, and the rest of the conditions are the same as those in Example 1.

[0111] Examples 7-8

[0112] Examples 7-8 and Example 1 differ only in that lithium thiosulfate and lithium hyposulfite are respectively used to replace p-phenylenediamine in the second injection electrolyte, and the rest of the conditions are the same as those in Example 1.

[0113] Examples 9-10

[0114] Examples 9-10 and Example 1 differ only in that the upper limit voltage of formation is 4.2 V and 3.95 V, respectively, and the rest of the conditions are the same as those of Example 1.

[0115] Example 11

[0116] Example 11 and Example 1 differ only in that the content of vinyl sulfite is 2% and the content of p-phenylenediamine is 5% in the two-injection electrolyte, and the rest of the conditions are the same as those of Example 1.

[0117] Example 12

[0118] Example 12 and Example 1 differ only in that the content of vinyl sulfite is 6% and the content of p-phenylenediamine is 3% in the two-injection electrolyte, and the rest of the conditions are the same as those of Example 1.

[0119] Example 13

[0120] Example 13 and Example 1 differ only in that the content of vinyl sulfite is 1% and the content of p-phenylenediamine is 0.5% in the two-injection electrolyte, and the rest of the conditions are the same as those of Example 1.

[0121] Example 14

[0122] Example 14 and Example 1 differ only in that the active oxygen scavenger is vinyl sulfite (content of 2%), p-phenylenediamine (content of 2%) and lithium thiosulfate (content of 2%) in the two-injection electrolyte, and the rest of the conditions are the same as those of Example 1.

[0123] Example 15

[0124] Example 15 and Example 1 differ only in that the lithium supplementing agent is LFO and LNO, and the mass ratio of lithium iron phosphate, PVDF, conductive carbon SP, lithium supplementing agent LFO and LNO is 94:1.5:0.75:3:0.75 (total 100 parts by mass), and the rest of the conditions are the same as those of Example 1.

[0125] Comparative Example 1

[0126] This comparative example and Example 1 differ only in that no active oxygen scavenger is used in the two-injection electrolyte, and the rest of the conditions are the same as those of Example 1.

[0127] Comparative Example 2

[0128] This comparative example and Example 1 differ only in that the active oxygen scavenger is only p-phenylenediamine (content of 2%) in the two-injection electrolyte, and there is no vinyl sulfite, and the rest of the conditions are the same as those of Example 1.

[0129] Comparative Example 3

[0130] The difference between the present comparative example and Example 1 is that the active oxygen scavenger in the two-injection electrolyte is only vinyl sulfite (content of 4%), without p-phenylenediamine, and the rest of the conditions are the same as those in Example 1.

[0131] Comparative Example 4

[0132] The difference between the present comparative example and Example 1 is that the active oxygen scavenger in the two-injection electrolyte is only p-phenylenediamine (content of 6%), without vinyl sulfite, and the rest of the conditions are the same as those in Example 1.

[0133] Comparative Example 5

[0134] The difference between the present comparative example and Example 1 is that the active oxygen scavenger in the two-injection electrolyte is only vinyl sulfite (content of 6%), without p-phenylenediamine, and the rest of the conditions are the same as those in Example 1.

[0135] Comparative Example 6

[0136] The difference between the present comparative example and Example 14 is that the active oxygen scavenger in the two-injection electrolyte is p-phenylenediamine (content of 2%) and lithium thiosulfate (content of 2%), without vinyl sulfite, and the rest of the conditions are the same as those in Example 14.

[0137] Effect Example 1

[0138] The gas production and capacity performance of the batteries obtained in Examples 1-15 and Comparative Examples 1-6 were tested:

[0139] (1) Gas production percentage and high-temperature storage capacity recovery rate

[0140] The obtained batteries were subjected to storage test at 60°C high temperature, and the capacity recovery rate of the batteries and the gas production of the batteries after 60 days of testing were tested, and the specific steps were as follows:

[0141] The initial volume of the tested battery was V0, and after 60 days of storage at 60°C high temperature, the volume of the battery V1 was tested, and the gas production percentage of the battery was (V1-V0) / V0;

[0142] After the capacity test of the battery, the initial capacity was defined as C0, and the fully charged battery was stored at 60°C high temperature for 60 days, and then the battery was charged and discharged for three cycles at a small current, and the capacity of each cycle was tested, and the average value of the three cycles was taken as C1, and the value of C1 / C0 was the high-temperature storage capacity recovery rate;

[0143] The above test results are shown in Table 1.

[0144] (2) High-temperature cycle capacity retention rate

[0145] The capacity retention rate of the test battery 1P / 1P at 45℃ high temperature after 500 cycles was tested, and the specific test steps were as follows:

[0146] Under the condition of 45℃, after 0.33C charge-discharge cycle activation for 3 cycles, 1C charging to 80% SOC, 0.33C charging 80%-100% SOC (3.65V), 1C discharging to 2.5V; the capacity of the first cycle using this process is C 初 , the capacity after 500 cycles using this process is C n ; the capacity retention rate after 500 cycles at room temperature is C n / C 初 ×100%. The test results are shown in Table 1.

[0147]

[0148] As can be seen from Table 1, on the basis of using LFO lithium supplementing agent, the electrolyte is injected by the one-two injection scheme, and the active oxygen scavenger of the composite component is added in the second injection electrolyte, the gas production problem of the obtained battery is obviously improved, and excellent high temperature cycle performance and high temperature storage stability can be considered. Specifically, after 60 days of storage at 60℃ high temperature, the gas production percentage can be less than 13%, even less than 7%; after 60 days of storage at high temperature 60℃, the high temperature storage capacity recovery rate can reach more than 97.3%, even more than 97.7%; the capacity retention rate of 500 cycles at 45℃ high temperature can reach more than 95.8%, even more than 97%.

[0149] In Comparative Examples 1-6, no active oxygen scavenger is used, or only the first component or the second component is used as an active oxygen scavenger, and compared with the composite active oxygen scavenger including the first component and the second component in the inventive Examples 1-15, the gas production percentage, the high temperature storage capacity recovery rate and the high temperature cycle capacity retention rate are all relatively poor. This may be because the ethylene sulfite as the first component absorbs active oxygen and is oxidized to ethylene sulfate, and then the ethylene sulfate continues to form a film reaction at the negative electrode; on the basis of the first component, the primary amine compound as the second component captures active oxygen, which generates a compound containing nitrogen and oxygen, which often has a lower delithiation barrier and can also achieve the effect of ensuring lithium ion transmission capacity, and cooperates with the film product of ethylene sulfate, so as to ensure the interface high temperature stability and excellent ion conductivity, and finally effectively improve the cycle performance. As the second component, the compound containing disulfide bond can cooperate and regulate the repair of the damaged SEI film after cycle on the basis of the first component, so that the SEI film is more stable and the inorganic component has a higher proportion, which ensures the excellent lithium ion transmission capacity at the interface, thereby effectively improving the cycle performance. However, when the first component or the second component is simply used as an active oxygen scavenger, the synergistic effect cannot be effectively achieved, and the above effects cannot be achieved. Specifically:

[0150] Compared with Example 1, the active oxygen scavenger was not used in the two-injection electrolyte of Comparative Example 1, and after 60 days of storage at 60°C, the gas generation percentage was greatly increased to 29.2%, the gas generation problem was serious, and the high-temperature storage capacity recovery rate and the high-temperature cycle capacity retention rate were significantly reduced.

[0151] Compared with Example 1, in the two-injection electrolytes of Comparative Examples 3 and 5, the active oxygen scavenger was only the first component vinyl sulfite (the content was 4% and 6%, respectively), and there was no second component, and after 60 days of storage at 60°C, the gas generation percentage, the high-temperature storage capacity recovery rate, and the high-temperature cycle capacity retention rate were all significantly worse, and the high-temperature stability was poor. Even though the amount of vinyl sulfite in Comparative Example 5 was as high as 6%, the gas generation percentage was still about 3% lower, but compared with the examples of the present application, the gas generation problem was still very serious, and the high-temperature storage stability and high-temperature cycle performance were also poor.

[0152] Compared with Example 1, in the two-injection electrolytes of Comparative Examples 2 and 4, the active oxygen scavenger only contained the second component (p-phenylenediamine, the content was 2% and 6%, respectively), and there was no first component, and after 60 days of storage at 60°C, the gas generation percentage was significantly increased, and the high-temperature storage capacity recovery rate and the high-temperature cycle capacity retention rate were also deteriorated to varying degrees. Even though the amount of active oxygen scavenger in Comparative Example 4 was 6%, but compared with the examples of the present application, not only the gas generation problem was not improved, but also the high stability and cycle performance were still poor.

[0153] Compared with Example 14, in the two-injection electrolyte of Comparative Example 6, the active oxygen scavenger only contained the second component (p-phenylenediamine and lithium thiosulfate), and there was no first component, and after 60 days of storage at 60°C, the gas generation percentage was greatly increased, the gas generation problem was serious, and the high-temperature storage capacity recovery rate and the high-temperature cycle capacity retention rate were all significantly decreased.

[0154] The above specific examples further illustrate the purpose, technical solutions and advantages of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. An electric cell, characterized by, The battery cell adopts a two-injection scheme to inject electrolyte, and the electrolyte includes a first-injected electrolyte and a second-injected electrolyte; The additive in the second-injected electrolyte includes an active oxygen trapping agent; the active oxygen trapping agent includes a first component and a second component, the first component is vinyl sulfite, and the second component includes a primary amine compound and a disulfide bond-containing compound; the disulfide bond-containing compound is selected from one or more of lithium thiosulfate, lithium dithionate, lithium dithionite, and lithium thiosulfate derivatives; the content of the active oxygen trapping agent is 1.5%-9%, and the percentage is the mass percentage of the second-injected electrolyte; The positive material layer in the positive sheet of the battery cell includes lithium iron phosphate and a positive lithium supplement agent, and the positive lithium supplement agent includes Li5FeO4.

2. The cell of claim 1, wherein, The primary amine compound is selected from one or more of p-phenylenediamine, benzylamine, phenethylamine, 1,2-phenylenediamine, propylenediamine, and butylenediamine.

3. The cell of claim 1, wherein, The second-injected electrolyte meets one or more of the following conditions a-c: a. The content of the vinyl sulfite is 1%-6%, and the percentage is the mass percentage of the second-injected electrolyte; b. The content of the primary amine compound is 0.5%-4%, and the percentage is the mass percentage of the second-injected electrolyte; c. The content of the disulfide bond-containing compound is 0.5%-4%, and the percentage is the mass percentage of the second-injected electrolyte.

4. The cell of claim 1, wherein, The active oxygen trapping agent is vinyl sulfite, a primary amine compound, and a disulfide bond-containing compound, and the mass ratio of the vinyl sulfite, the primary amine compound, and the disulfide bond-containing compound is 1:(0.5-1):(0.5-1).

5. The cell of claim 1, wherein, The second-injected electrolyte meets one or more of the following conditions a-c: a. The lithium salt in the second-injected electrolyte is selected from one or more of lithium hexafluorophosphate, lithium bisfluorosulfonimide, and lithium bis(trifluoromethylsulfonyl)imide; b. The solvent in the second-injected electrolyte is selected from one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, propyl formate, propyl propionate, and ethyl butyrate; c. The additive in the second-injected electrolyte further includes vinylene carbonate.

6. The cell of claim 1 wherein, The first-injected electrolyte meets one or more of the following conditions a-c: a. The lithium salt in the first-injected electrolyte is selected from one or more of lithium hexafluorophosphate, lithium bisfluorosulfonimide, and lithium bis(trifluoromethylsulfonyl)imide; b. The solvent in the first-injected electrolyte is selected from one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, propyl formate, propyl propionate, and ethyl butyrate; c. The additive in the first-injected electrolyte is selected from one or more of vinylene carbonate, fluoroethylene carbonate, and ethylene sulfate.

7. The cell of claim 1 wherein, The positive material layer meets one or more of the following conditions a-d: a. The content of the lithium iron phosphate is 93% or more, and the percentage is the mass percentage of the positive material layer; b. the content of the Li5FeO4 is 0.5%-5%, the percentage is the mass percentage of the positive electrode material layer; c. the sum of the content of the lithium iron phosphate and the Li5FeO4 is 98% or less, the percentage is the mass percentage of the positive electrode material layer; d. the positive electrode lithium supplementing agent further comprises LiNiO2.

8. A lithium-ion battery, characterized by, The battery includes the battery cell as claimed in any one of claims 1-7.

9. An electronic device, comprising: The lithium ion battery includes the battery cell as claimed in claim 8.

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