Electrolyte, lithium ion battery containing same and electronic device

Abstract

The application discloses an electrolyte, a lithium ion battery containing the electrolyte and electronic equipment. The electrolyte comprises 1,3-dioxane and a polyborate compound; the structure of the 1,3-dioxane is shown as formula I; the structure of the polyborate compound is shown as formula II-1 and / or formula II-2. The electrolyte has high conductivity, high ion transference coefficient, low viscosity, excellent chemical stability and electrochemical stability, the lithium ion battery containing the electrolyte has low impedance, high high-temperature capacity recovery rate, low high-temperature volume expansion rate, and low expansion rate of a full-charged negative electrode sheet after formation.

Description

TECHNICAL FIELD

[0001] The present application relates to an electrolyte, a lithium ion battery containing the same and an electronic device. BACKGROUND

[0002] With the improvement of global environmental awareness, new energy vehicles are rapidly becoming the first choice to replace traditional fuel vehicles. In recent years, electric vehicles have become more and more common in people's homes, greatly facilitating people's daily travel. At the same time, due to the short driving range, low energy density and other defects, the promotion and popularization of electric vehicles are limited to some extent, and fast charging technology has become the key innovation to solve this driving range shortage bottleneck. Compared with the traditional charging method, the fast charging technology significantly shortens the charging time, meets the needs of users for convenient and efficient charging, and further promotes the promotion and development of new energy vehicles.

[0003] With more and more consumers preferring new energy vehicles with higher energy density and longer driving range, the development and application of higher-silicon-content negative materials are greatly promoted. Due to the electrode structure rupture and active material peeling caused by the volume expansion of silicon material particles, the fresh interface generated has strong electrochemical reducibility, and the carbonate solvent system in the electrolyte is reduced to a certain extent. The interface side reaction caused by the volume expansion of these silicon materials will result in higher capacity loss. Therefore, it is urgent to develop a solvent with high electrical conductivity, high ion transference coefficient, low viscosity, and high chemical stability and electrochemical stability. SUMMARY

[0004] In order to solve the defects that the electrolyte in the existing lithium ion battery cannot balance high electrical conductivity, high ion transference coefficient, low viscosity and excellent chemical stability and electrochemical stability, the present application provides an electrolyte, a lithium ion battery containing the same and an electronic device. The electrolyte has high electrical conductivity, high ion transference coefficient, low viscosity and excellent chemical stability and electrochemical stability, the lithium ion battery containing the same has low impedance, high high-temperature capacity recovery rate, low high-temperature volume expansion rate, and low expansion rate of the full-charged negative electrode sheet after formation.

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

[0006] In the first aspect, the present application provides an electrolyte, which comprises 1,3-dioxane and a polyboronic acid compound; the structure of the 1,3-dioxane is shown in formula I; the structure of the polyboronic acid compound is shown in formula II-1 and / or formula II-2;

[0007] ;

[0008] wherein, in Formula I, n is selected from an integer within 1 to 4; in Formula II-1 and Formula II-2, n2 is each independently selected from an integer within 1 to 12; in Formula II-2, n3 is selected from an integer within 1 to 3;

[0009] R' in Formula II-1 is selected from one or more of hydrogen, alkyl having 1 to 10 carbon atoms, cyclic alkyl, alkenyl, cyclic alkenyl, alkynyl, cyclic alkynyl, haloalkyl, haloalkenyl, haloalkynyl, and aryl and benzyl having 6 to 10 carbon atoms;

[0010] M in Formula II-2 is selected from one or more of Li, Be, Na, Mg, K, Ca, Mn, Fe, Co, Ni, Cu, and Zn.

[0011] In a second aspect, the present application provides a lithium ion battery comprising the electrolyte as described above.

[0012] In a third aspect, the present application provides an electronic device comprising the lithium ion battery as described above.

[0013] The positive progress effect of the present application is that:

[0014] The present application aims at the problem that the electrolyte in lithium ion battery cannot simultaneously have high conductivity, high ion transference coefficient, low viscosity, and excellent chemical stability and electrochemical stability. The 1,3-dioxolane compound having Formula I structure and the polyborate compound having Formula II structure are used in the electrolyte. The electrolyte has high conductivity, high ion transference coefficient, low viscosity, and excellent chemical stability and electrochemical stability. The lithium ion battery containing the electrolyte has low impedance, high high-temperature capacity recovery rate, low high-temperature volume expansion rate, and low expansion rate of the full-charged negative electrode sheet after formation. DETAILED DESCRIPTION

[0015] The present application will be further described by way of examples below, but the present application is not limited to the examples. In the following examples, the experimental methods not specified in the examples are selected according to the conventional methods and conditions, or according to the instructions of the commercial products.

[0016] Electrolyte

[0017] In the electrolyte provided in the first aspect of the present application, the electrolyte comprises a 1,3-dioxolane compound and a polyborate compound; the structure of the 1,3-dioxolane compound is shown in Formula I; the structure of the polyborate compound is shown in Formula II-1 and / or Formula II-2;

[0018] ;

[0019] wherein n in Formula I is selected from an integer from 1 to 4; n2 in Formula II-1 and Formula II-2 is each independently selected from an integer from 1 to 12; n3 in Formula II-2 is selected from an integer from 1 to 3;

[0020] R' in Formula II-1 is selected from one or more of hydrogen, alkyl having a carbon number from 1 to 10, cyclic alkyl, alkenyl, cyclic alkenyl, alkynyl, cyclic alkynyl, haloalkyl, haloalkenyl, haloalkynyl, and aryl and benzyl having a carbon number from 6 to 10;

[0021] M in Formula II-2 is selected from one or more of Li, Be, Na, Mg, K, Ca, Mn, Fe, Co, Ni, Cu, and Zn.

[0022] In some preferred embodiments, the 1,3-dioxolane compound is selected from one or more of compounds a-c:

[0023] .

[0024] In some preferred embodiments, in Formula II-2, when M is one or more of Li, Na, and K, n3 is 1; when M is one or more of Be, Mg, Ca, Cu, and Zn, n3 is 2; when M is one or more of Mn, Fe, Co, and Ni, n3 is 2 or 3.

[0025] In some preferred embodiments, the polyboronic acid compound is selected from one or more of compounds d-g:

[0026] .

[0027] In some alternative embodiments, the 1,3-dioxolane compound is present in an amount from 0.05% to 20%, preferably from 0.5% to 10%, for example 3%, 6%, 8%, or 15%, the percentage being a mass percentage of the electrolyte.

[0028] In some alternative embodiments, the polyboronic acid compound is present in an amount from 0.05% to 6%, preferably from 0.5% to 6%, for example 1%, the percentage being a mass percentage of the electrolyte.

[0029] In some alternative embodiments, the mass ratio of the 1,3-dioxolane compound to the polyboronic acid compound is (0.05-120): 1, preferably (1-60): 1, for example 6: 1, 12: 1, 15: 1, or 20: 1.

[0030] In a specific embodiment, the electrolyte comprises compound a and compound d; the compound a is present in an amount of, for example, 6%, and the compound d is present in an amount of, for example, 1%.

[0031] In a particular embodiment, the electrolyte comprises compound a, compound b and compound d; the content of compound a is for example 3%, the content of compound b is for example 3%, the content of compound d is for example 1%.

[0032] In a particular embodiment, the electrolyte comprises compound a, compound c and compound e; the content of compound a is for example 3%, the content of compound c is for example 3%, the content of compound e is for example 1%.

[0033] In a particular embodiment, the electrolyte comprises compound a, compound c, compound e and compound f; the content of compound a is for example 3%, the content of compound c is for example 3%, the content of compound e is for example 1%, the content of compound f is for example 2%.

[0034] In a particular embodiment, the electrolyte comprises compound a, compound c, compound e and compound f; the content of compound a is for example 3%, the content of compound c is for example 3%, the content of compound e is for example 3%, the content of compound f is for example 3%.

[0035] In a particular embodiment, the electrolyte comprises compound a and compound d; the content of compound a is for example 3%, the content of compound d is for example 1%.

[0036] In a particular embodiment, the electrolyte comprises compound a, compound d, compound e and compound f; the content of compound a is for example 3%, the content of compound d is for example 1%, the content of compound e is for example 1%, the content of compound f is for example 1%.

[0037] In a particular embodiment, the electrolyte comprises compound b, compound c, compound d, compound e and compound f; the content of compound b is for example 3%, the content of compound c is for example 3%, the content of compound d is for example 1%, the content of compound f is for example 1%, the content of compound e is for example 1%.

[0038] In a particular embodiment, the electrolyte comprises compound c and compound d; the content of compound c is for example 8%, the content of compound d is for example 1%.

[0039] In a particular embodiment, the electrolyte comprises compound c and compound e; the content of compound c is for example 6%, the content of compound e is for example 0.5%.

[0040] In a particular embodiment, the electrolyte comprises compound c and compound e; the content of compound c is for example 6% and the content of compound e is for example 0.1%.

[0041] In a particular embodiment, the electrolyte comprises compound c and compound f; the content of compound c is for example 6% and the content of compound f is for example 0.5%.

[0042] In a particular embodiment, the electrolyte comprises compound c, compound d and compound f; the content of compound c is for example 6%, the content of compound d is for example 3% and the content of compound f is for example 3%.

[0043] In a particular embodiment, the electrolyte comprises compound a, compound c and compound f; the content of compound a is for example 3%, the content of compound c is for example 3% and the content of compound f is for example 0.5%.

[0044] In a particular embodiment, the electrolyte comprises compound a, compound c and compound e; the content of compound a is for example 3%, the content of compound c is for example 3% and the content of compound e is for example 6%.

[0045] In a particular embodiment, the electrolyte comprises compound a and compound d; the content of compound a is for example 0.05% and the content of compound d is for example 1%.

[0046] In a particular embodiment, the electrolyte comprises compound a and compound d; the content of compound a is for example 10% and the content of compound d is for example 1%.

[0047] In a particular embodiment, the electrolyte comprises compound a and compound d; the content of compound a is for example 15% and the content of compound d is for example 1%.

[0048] In a particular embodiment, the electrolyte comprises compound a and compound d; the content of compound a is for example 20% and the content of compound d is for example 1%.

[0049] In a particular embodiment, the electrolyte comprises compound a and compound d; the content of compound a is for example 6% and the content of compound d is for example 0.05%.

[0050] In the present application, the solvent in the electrolyte can be a solvent commonly used in the art, and can generally include one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate, fluoroethylene carbonate, trifluoroethyl methyl carbonate, trifluoro propylene carbonate, trifluoromethyl propylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, butyl sulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0051] In some preferred embodiments, the solvent in the electrolyte includes one or more of cyclic carbonate, ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), trifluoroethyl methyl carbonate, trifluoro propylene carbonate, trifluoromethyl propylene carbonate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate; wherein the cyclic carbonate is preferably ethylene carbonate (EC) and / or propylene carbonate (PC).

[0052] In some alternative embodiments, the additive in the electrolyte includes one or both of fluoroethylene carbonate (FEC) and lithium bisoxalato borate (LiBOB).

[0053] In the present application, the lithium salt in the electrolyte can be a lithium salt commonly used in the art, and can generally include one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethylsulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro oxalate borate, lithium bisoxalato borate, lithium difluoro bisoxalato phosphate, and lithium tetrafluoro oxalato phosphate.

[0054] In some preferred embodiments, the lithium salt in the electrolyte includes one or both of lithium hexafluorophosphate and lithium bisfluorosulfonylimide.

[0055] In some alternative embodiments, the electrolyte includes cyclic carbonate and fluoroethylene carbonate, and the electrolyte satisfies the following conditions:

[0056] 1≤Y1 / (Y2+Y3)≤40;

[0057] 0.05≤Y2 / Y3≤70;

[0058] 0.1%≤Y1≤35%;

[0059] 0.1%≤Y2≤35%;

[0060] Y1 is the mass percentage of the cyclic carbonate in the electrolyte, Y2 is the mass percentage of the fluoroethylene carbonate in the electrolyte, and Y3 is the mass percentage of the 1,3-dioxolane compound in the electrolyte.

[0061] In some preferred embodiments, 0.5≤Y2 / Y3≤12.

[0062] Lithium ion battery

[0063] In the second aspect of the present application, the lithium ion battery comprises the electrolyte as described above.

[0064] In the present application, the lithium ion battery comprises a positive electrode sheet, a negative electrode sheet, and a separator.

[0065] Positive electrode sheet

[0066] In the present application, the positive electrode sheet in the lithium ion battery 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.

[0067] In the present application, the positive electrode active material in the lithium ion battery can be a positive electrode active material commonly used in the art, and is generally selected from lithium transition metal oxides and modified compounds thereof; wherein the lithium transition metal oxide preferably comprises one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide; wherein the content of manganese element in the positive electrode active material in the lithium ion battery is preferably >0.5%, the percentage being a molar ratio of the total number of moles of metal elements other than lithium in the positive electrode active material.

[0068] In some optional embodiments, the positive electrode active material in the lithium ion battery is one or more of manganese iron lithium compounds, iron lithium compounds, and manganese lithium compounds, preferably one or more of lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium manganese oxide, manganese iron lithium phosphate, and lithium nickel manganese cobalt oxide.

[0069] In some optional embodiments, the content of manganese element in the positive electrode active material in the lithium ion battery is >10%, the percentage being a molar ratio of the total number of moles of metal elements other than lithium in the positive electrode active material.

[0070] In some preferred embodiments, the positive electrode active material in the lithium ion battery is selected from LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.2 Mn 0.3O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.5 Mn 1.5 O4, LiFe 0.4 Mn 0.6 PO4and LiFeMnPO4.

[0071] In some alternative embodiments, the content of the positive electrode active material is 90% or more, for example, 97%, the percentage being a percentage of the total mass of the positive electrode material layer.

[0072] In some alternative embodiments, the positive electrode material layer further includes a binder.

[0073] The kind of the binder is not particularly limited, and can be optionally one or more of polyvinylidene fluoride, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid (PAA), ethylene-propylene-diene terpolymer and sulfonated products thereof, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, styrene butadiene rubber (SBR), fluororubber, and fluorine-containing acrylate resin, for example, PVDF.

[0074] In some alternative embodiments, the content of the binder is 1% to 10%, the percentage being a percentage of the total mass of the positive electrode material layer.

[0075] In some alternative embodiments, the positive electrode material layer further includes a conductive agent.

[0076] The kind of the conductive agent is not particularly limited, and is an agent for ensuring that the electrode has good charge and discharge properties. It can be optionally one or more of 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, and the like, conductive fibers such as carbon fibers and metal fibers, metal powders such as fluorinated carbon powder, aluminum powder, nickel powder, and the like, conductive whiskers such as zinc oxide and potassium titanate, and conductive metal oxides such as titanium dioxide, and polyphenylene derivatives.

[0077] In a specific embodiment, the conductive agent is acetylene black.

[0078] In some alternative embodiments, the content of the conductive agent is 0.2%-3%, for example 2%, the percentage being the percentage of the total mass of the positive electrode material layer.

[0079] In some specific embodiments, the mass ratio of the positive electrode active material, the conductive agent and the binder in the positive electrode material layer is 97:2:1.

[0080] In the present application, the positive electrode current collector can be a conventional positive electrode current collector in the art. The positive electrode current collector, as a substrate for supporting the positive electrode material layer, can be a metal foil or a composite current collector. There is no particular limitation on the material, as long as it has high electrical conductivity and does not cause chemical reactions in the system of the secondary battery.

[0081] In some preferred embodiments, the metal foil is preferably an aluminum foil or an aluminum alloy.

[0082] In some preferred embodiments, the composite current collector comprises a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer; the composite current collector can be obtained by compounding a metal material on a polymer material. The metal material preferably comprises one or more of aluminum, an aluminum alloy, nickel, a nickel alloy, a silver-based silver alloy and a titanium alloy; the polymer material substrate preferably comprises one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyethylene (PE).

[0083] Generally, the positive electrode current collector is an aluminum foil.

[0084] 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, cold pressing, trimming, cutting, and slitting, to obtain the positive electrode sheet.

[0085] In some alternative embodiments, the solvent comprises one or more of N-methyl pyrrolidone (NMP), dimethyl carbonate, ethylene carbonate and diethylene carbonate, for example NMP.

[0086] Negative electrode sheet

[0087] In the present application, the negative electrode sheet in the lithium ion battery comprises a negative electrode current collector and a negative electrode material layer arranged on at least one surface of the negative electrode current collector.

[0088] In this invention, the negative electrode active material in the lithium-ion battery can be a negative electrode active material conventionally used in the art, preferably including one or more of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material preferably includes one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys; the tin-based material preferably includes one or more of elemental tin, tin oxide compounds, and tin alloys.

[0089] In some alternative embodiments, the negative electrode active material in the lithium-ion battery is selected from graphite and / or silicon materials; wherein, the graphite preferably includes artificial graphite and / or natural graphite; the silicon material preferably includes silicon-oxygen materials and / or silicon-carbon materials; the content of Si element in the silicon material is preferably ≥10%, and the percentage is the mass percentage of the silicon material.

[0090] In some preferred embodiments, the negative electrode active material in the lithium-ion battery includes silicon, the electrolyte includes fluoroethylene carbonate, and the electrolyte meets the following conditions:

[0091] 0.1≤(Y2+Y3) / Z1≤1;

[0092] 0.1%≤Z1≤30%;

[0093] 0.1%≤Y2≤30%;

[0094] Wherein, Z1 is the mass percentage of the silicon material in the negative electrode active material; Y2 is the mass percentage of the fluoroethylene carbonate in the electrolyte; and Y3 is the mass percentage of the 1,3-dioxane compound in the electrolyte.

[0095] In one specific implementation, the negative electrode active material is a silicon-carbon composite and artificial graphite.

[0096] In some implementations, the negative electrode material layer also includes a thickener.

[0097] The addition of the thickener can increase the viscosity of the system of each component in the negative electrode slurry. It can be a thickener commonly used in the art to prepare negative electrode sheets, such as sodium carboxymethyl cellulose (CMC).

[0098] In some implementations, the negative electrode material layer further includes a conductive agent.

[0099] The conductive agent is not particularly limited, as long as it is conductive and does not cause chemical changes in the battery. For example, specific materials that can be used include: graphite, such as natural or artificial graphite; carbon-based materials, such as carbon black (Super P), acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, or carbon fiber; metal powders or metal fibers, 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, etc.

[0100] In one specific implementation, the conductive agent is conductive carbon black.

[0101] In some implementations, the negative electrode material layer further includes a binder.

[0102] The type of adhesive is not particularly limited and can be selected from one or more of polyvinylidene fluoride, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid (PAA), lithium polyacrylate (PAALi), ethylene-propylene-diene terpolymer and its sulfonates, styrene-butadiene rubber (SBR), fluororubber and various copolymers, such as PAALi, PAA or SBR.

[0103] In some specific embodiments, the mass ratio of the negative electrode active material, conductive agent, binder and thickener in the negative electrode material layer is 96:2:1:1.

[0104] In this invention, the negative electrode current collector can be a conventional negative electrode current collector in the art. The negative electrode current collector, serving as the substrate supporting the negative electrode material layer, can be a metal foil or a composite current collector. There are no particular restrictions on the material, as long as it has high conductivity and does not produce a chemical reaction in the secondary battery system.

[0105] In some preferred embodiments, the metal foil is preferably copper foil.

[0106] In some preferred embodiments, the composite current collector comprises a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate; the composite current collector can be obtained by laminating a metal material onto the polymer material. The metal material preferably includes one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys; the polymer material substrate preferably includes one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0107] Generally, the negative electrode current collector is copper foil.

[0108] In some embodiments, the method for preparing the negative electrode sheet includes the following steps: coating the negative electrode slurry obtained by thoroughly mixing the components of the negative electrode material layer in a solvent onto at least one surface of the negative electrode current collector, drying, cold pressing, trimming, cutting, and slitting to obtain the final product.

[0109] diaphragm

[0110] In this invention, the separator in the lithium-ion battery can be a separator conventionally used in the art. The separator can be a single-layer membrane or a multi-layer composite membrane. There are no particular limitations on the type of separator; its material includes one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. When the separator is a multi-layer composite membrane, the materials of each layer can be the same or different.

[0111] In some alternative embodiments, the diaphragm may be a polypropylene film or a polyethylene film.

[0112] The air permeability of the diaphragm can be 180-380 s / 100mL.

[0113] The porosity of the diaphragm can be 30%-50%.

[0114] The thickness of the diaphragm can be 5-40 μm, preferably 7-16 μm.

[0115] In one specific embodiment, the diaphragm is a polyethylene film; the thickness of the diaphragm is 11 μm; the air permeability of the diaphragm is 230 s / 100 mL; and the porosity of the diaphragm is 40%.

[0116] In this invention, the lithium ion preparation method can adopt conventional preparation methods in the art, generally including using a winding process or a stacking process to form an electrode assembly from a positive electrode sheet, a separator, and a negative electrode sheet.

[0117] In some embodiments, the method for preparing the lithium-ion battery includes the following steps: stacking the positive electrode, separator, and negative electrode in sequence; then wrapping them with an aluminum-plastic film to obtain a dry cell; after drying, injecting the electrolyte; and then encapsulating, allowing it to stand, and forming it to finally prepare a pouch battery.

[0118] electronic devices

[0119] The electronic device provided in the third aspect of the present invention includes a lithium-ion battery as described above.

[0120] For example, the electronic devices described in this invention may be, but are not limited to, mobile devices (such as mobile phones, tablets, laptops, video recorders, portable printers / copiers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems and backup power supplies, etc.

[0121] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention. The present invention is further illustrated below by way of embodiments, but this does not limit the present invention to the scope of the described embodiments. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or according to the product instructions. Unless otherwise specified, all reagents and raw materials used in the present invention are commercially available.

[0122] Example 1

[0123] (1) Preparation of electrolyte:

[0124] In an argon-atmospheric glove box with a water content of <1 ppm, EC, PC, EMC, and DEC were mixed in a mass ratio of 10:20:60:10 to obtain a mixed solvent. Lithium hexafluorophosphate (10%) and lithium difluorosulfonylimide (6%) were dissolved in the mixed solvent. Then, compound I (compound a, 6%) and compound II (compound d, 1%) were added and mixed thoroughly to obtain the electrolyte.

[0125] (2) Preparation of the positive electrode:

[0126] The positive electrode active material is lithium nickel manganese cobalt oxide (LiNi 0.8 Co 0.1 Mn 0.1 O2), conductive agent acetylene black, and binder polyvinylidene fluoride are mixed in a mass ratio of 97:2:1 (total 100 parts by mass) and dissolved in NMP solvent to prepare a positive electrode slurry. The positive electrode slurry is then coated onto a current collector aluminum foil, dried, cold-pressed, trimmed, cut, and slit to obtain the positive electrode sheet.

[0127] (3) Preparation of negative electrode:

[0128] The negative electrode active material (silicon-carbon composite and artificial graphite, with the silicon-carbon composite accounting for 12% of the negative electrode active material by mass, wherein the silicon element: carbon element in the silicon-carbon composite is 1:1), conductive carbon black, thickener CMC, and binder PAALi are mixed in a mass ratio of 96:2:1:1 (total 100 parts by mass), and deionized water is added as a solvent. The mixture is then stirred evenly under vacuum to obtain a negative electrode slurry (the solid content of the slurry is controlled between 45% and 50%). The negative electrode slurry is then coated onto a current collector copper foil, dried, cold-pressed, trimmed, cut, and slit to obtain the negative electrode sheet.

[0129] (4) Preparation of lithium-ion batteries:

[0130] The prepared positive electrode, separator, and negative electrode are stacked sequentially and placed in an aluminum-plastic film to obtain a dry cell. The dry cell is then dried at 80°C. Electrolyte is injected into the dry cell, which is then sealed and placed at 45°C for 36 hours. After removal, it is charged in stages at 45°C and normal pressure: first, it is charged to 3.05V at 0.02C, then to 3.4V at 0.05C. A portion of the cells used for negative electrode expansion rate testing is then charged to a full charge state of 3.75V at 0.33C. After aging and capacity testing, the final product is obtained. The separator is a polyethylene film with a thickness of 11μm, an air permeability of 230s / 100mL, and a porosity of 40%.

[0131] Example 2

[0132] The only difference between Example 2 and Example 1 is that in the preparation of the electrolyte, the compounds of Formula I are compound a (content of 3%) and compound b (content of 3%); the compound of Formula II is compound d (content of 1%), and the other conditions are the same as in Example 1.

[0133] Example 3

[0134] The only difference between Example 3 and Example 1 is that in the preparation of the electrolyte, the compounds of Formula I are compound a (content of 3%) and compound c (content of 3%); the compound of Formula II is compound e (content of 1%), and the other conditions are the same as in Example 1.

[0135] Example 4

[0136] The only difference between Example 4 and Example 2 is that the content of lithium hexafluorophosphate in the preparation of the electrolyte is 14.9%, and lithium difluorosulfonylimide is not used. The other conditions are the same as in Example 2.

[0137] Example 5

[0138] The only difference between Example 5 and Example 1 is that in the preparation of the electrolyte, the compounds of Formula I are compound b (content of 3%) and compound c (content of 3%); the compound of Formula II is compound f (content of 1%), and the other conditions are the same as in Example 1.

[0139] Example 6

[0140] The only difference between Example 6 and Example 1 is that in the preparation of the electrolyte, the compounds of Formula I are compound a (content of 3%) and compound c (content of 3%); the compounds of Formula II are compound e (content of 1%) and compound f (content of 2%), and the other conditions are the same as in Example 1.

[0141] Example 7

[0142] The only difference between Example 7 and Example 1 is that in the preparation of the electrolyte, the compounds of Formula I are compound a (content of 3%) and compound c (content of 3%); the compounds of Formula II are compound e (content of 3%) and compound f (content of 3%), and the other conditions are the same as in Example 1.

[0143] Example 8

[0144] The only difference between Example 8 and Example 4 is that in the preparation of the electrolyte, the compounds of Formula I are compound a (content of 3%) and compound c (content of 3%); the compound of Formula II is compound f (content of 1%), and the other conditions are the same as in Example 4.

[0145] Example 9

[0146] The only difference between Example 9 and Example 1 is that in the preparation of the electrolyte, the content of lithium hexafluorophosphate is 14.9%, and lithium bisfluorosulfonylimide is not used; the content of compound a is 3%, and the other conditions are the same as in Example 1.

[0147] Example 10

[0148] The only difference between Example 10 and Example 1 is that in the preparation of the electrolyte, the content of lithium hexafluorophosphate is 14.9%, and lithium difluorosulfonylimide is not used; the compound of Formula I is compound a (content is 3%); the compounds of Formula II are compound d (content is 1%), compound e (content is 1%) and compound f (content is 1%), and the other conditions are the same as in Example 1.

[0149] Example 11

[0150] The only difference between Example 11 and Example 1 is that in the preparation of the electrolyte, the content of lithium hexafluorophosphate is 14.9%, and lithium difluorosulfonylimide is not used; the compounds of Formula I are compound b (content of 3%) and compound c (content of 3%); the compounds of Formula II are compound d (content of 1%), compound e (content of 1%) and compound f (content of 1%), and the other conditions are the same as in Example 1.

[0151] Example 12

[0152] The only difference between Example 12 and Example 1 is that in the preparation of the electrolyte, the content of lithium hexafluorophosphate is 14.9%, and lithium bisfluorosulfonylimide is not used; the compound of Formula I is compound c (content is 8%); the compound of Formula II is compound d (content is 1%), and the other conditions are the same as in Example 1.

[0153] Example 13

[0154] The only difference between Example 13 and Example 1 is that in the preparation of the electrolyte, the content of lithium hexafluorophosphate is 14.9%, and lithium difluorosulfonylimide is not used; the compound of Formula I is compound c (content is 6%); the compound of Formula II is compound e (content is 0.5%), and the other conditions are the same as in Example 1.

[0155] Example 14

[0156] The only difference between Example 14 and Example 1 is that in the preparation of the electrolyte, the content of lithium hexafluorophosphate is 14.9%, and lithium difluorosulfonylimide is not used; the compound of Formula I is compound c (content is 6%); the compound of Formula II is compound e (content is 0.1%), and the other conditions are the same as in Example 1.

[0157] Example 15

[0158] The only difference between Example 15 and Example 1 is that in the preparation of the electrolyte, the content of lithium hexafluorophosphate is 14.9%, and lithium difluorosulfonylimide is not used; the compound of Formula I is compound c (content is 6%); the compound of Formula II is compound f (content is 0.5%), and the other conditions are the same as in Example 1.

[0159] Example 16

[0160] The only difference between Example 16 and Example 1 is that in the preparation of the electrolyte, the content of lithium hexafluorophosphate is 14.9%, and lithium difluorosulfonylimide is not used; the compound of Formula I is compound c (content is 6%); the compounds of Formula II are compound d (content is 3%) and compound f (content is 3%), and the other conditions are the same as in Example 1.

[0161] Example 17

[0162] The only difference between Example 17 and Example 1 is that in the preparation of the electrolyte, the compounds of Formula I are compound a (content of 3%) and compound c (content of 3%); the compound of Formula II is compound f (content of 0.5%), and the other conditions are the same as in Example 1.

[0163] Example 18

[0164] The only difference between Example 18 and Example 1 is that in the preparation of the electrolyte, the compounds of Formula I are compound a (content of 3%) and compound c (content of 3%); the compound of Formula II is compound e (content of 6%), and the other conditions are the same as in Example 1.

[0165] Example 19

[0166] The only difference between Example 19 and Example 1 is that the content of compound a in the preparation of the electrolyte is 0.05%, and the other conditions are the same as in Example 1.

[0167] Example 20

[0168] The only difference between Example 20 and Example 1 is that the content of compound a in the preparation of the electrolyte is 10%, and the other conditions are the same as in Example 1.

[0169] Example 21

[0170] The only difference between Example 21 and Example 1 is that the content of compound a in the preparation of the electrolyte is 15%, and the other conditions are the same as in Example 1.

[0171] Example 22

[0172] The only difference between Example 22 and Example 1 is that the content of compound a in the preparation of the electrolyte is 20%, and the other conditions are the same as in Example 1.

[0173] Example 23

[0174] The only difference between Example 23 and Example 1 is that the content of compound d in the preparation of the electrolyte is 0.05%, and the other conditions are the same as in Example 1.

[0175] Example 24

[0176] The only difference between Example 24 and Example 1 is that the positive electrode active material is a lithium iron manganese compound (LiFe). 0.4 Mn 0.6 PO4), and the other conditions are the same as in Example 1.

[0177] Example 25

[0178] The only difference between Example 25 and Example 1 is that, in the preparation of the electrolyte, when adding compounds of Formula I and Formula II, LiBOB (at a content of 1%) is also added, and the other conditions are the same as in Example 1.

[0179] Example 26

[0180] The only difference between Example 26 and Example 1 is that, in the preparation of the electrolyte, when adding compounds of Formula I and Formula II, FEC (at a content of 3%) is also added, and the other conditions are the same as in Example 1.

[0181] Example 27

[0182] The only difference between Example 27 and Example 1 is that, in the preparation of the electrolyte, when adding compounds of Formula I and Formula II, LiBOB (content of 1%) and FEC (content of 3%) are also added, and the other conditions are the same as in Example 1.

[0183] Comparative Example 1

[0184] The only difference between this comparative example and Example 1 is that FEC (at a content of 6%) was used to replace compounds of formula I and formula II in the preparation of the electrolyte, while the other conditions were the same as in Example 1.

[0185] Comparative Example 2

[0186] The only difference between this comparative example and Example 4 is that FEC (at a content of 6%) was used to replace compounds of formula I and formula II in the preparation of the electrolyte, while the other conditions were the same as in Example 1.

[0187] Comparative Example 3

[0188] The only difference between this comparative example and Example 1 is that FEC (at a content of 3%) was used to replace compounds of formula I and formula II in the preparation of the electrolyte, while the other conditions were the same as in Example 1.

[0189] Comparative Example 4

[0190] The only difference between this comparative example and Example 4 is that FEC (at a content of 3%) was used to replace compounds of formula I and formula II in the preparation of the electrolyte, while the other conditions were the same as in Example 1.

[0191] Comparative Example 5

[0192] The only difference between this comparative example and Example 4 is that FEC (6% content) and LiBOB (1% content) were used to replace compounds of formula I and formula II in the preparation of the electrolyte, while the other conditions were the same as in Example 1.

[0193] Comparative Example 6

[0194] The only difference between this comparative example and Example 1 is that, in the preparation of the electrolyte, compound I is compound a (content of 3%), and FEC (content of 3%) is used to replace compound II, while the other conditions are the same as in Example 1.

[0195] Comparative Example 7

[0196] The only difference between this comparative example and Example 1 is that the electrolyte preparation does not include compound II, while the other conditions are the same as in Example 1.

[0197] Comparative Example 8

[0198] The only difference between this comparative example and Example 4 is that in the preparation of the electrolyte, there is no compound of formula II, and the compounds of formula I are compound a (content of 3%) and compound b (content of 3%). The other conditions are the same as in Example 1.

[0199] Comparative Example 9

[0200] The only difference between this comparative example and Example 1 is that LiBOB (content of 1%) was used to replace compound II in the preparation of the electrolyte, while the other conditions were the same as in Example 1.

[0201] Comparative Example 10

[0202] The only difference between this comparative example and Example 4 is that, in the preparation of the electrolyte, the compounds of Formula I are compound c (content of 3%) and compound b (content of 3%), and LiBOB (content of 1%) is used to replace the compound of Formula II. The other conditions are the same as in Example 1.

[0203] Comparative Example 11

[0204] The only difference between this comparative example and Example 16 is that the electrolyte preparation does not include compound I; all other conditions are the same as in Example 16.

[0205] Comparative Example 12

[0206] The only difference between this comparative example and Example 18 is that the electrolyte preparation does not include compound I; all other conditions are the same as in Example 18.

[0207] The contents of components other than solvents in the electrolytes obtained in Examples 1-27 and Comparative Examples 1-12 are shown in Table 1.

[0208] Example 1

[0209] The following performance tests were performed on the lithium-ion batteries prepared in Examples 1-27 and Comparative Examples 1-12:

[0210] (1) Low-temperature DCR

[0211] At 25°C, the lithium-ion battery was charged at a constant current of 1 / 3C to 4.25V, and then charged at a constant voltage to a current of 0.05C. The battery was then discharged at a constant current of 1 / 3C to 2.8V. This charging process was repeated, and the charging capacity was recorded as C0. The battery was then discharged at a constant current of 1 / 3C to (50% × C0). The battery was then placed at -20°C, and the initial voltage was recorded as U0. The battery was then discharged at a constant current of 1C for 30 seconds, and the final voltage was recorded as U1.

[0212] DCR at -20℃ = (U0-U1) / (C0×1).

[0213] (2)Normal temperature DCR

[0214] At 25°C, the lithium-ion battery was charged at a constant current of 1 / 3C to 4.25V, and then charged at a constant voltage to a current of 0.05C. The battery was then discharged at a constant current of 1 / 3C to 2.8V. This charging process was repeated, and the charging capacity was recorded as C1. The battery was then discharged at a constant current of 1 / 3C to (50% × C1), and the initial voltage was recorded as U2. The battery was then discharged at a constant current of 1C for 30 seconds, and the final voltage was recorded as V3.

[0215] DCR=(U2-U3) / (C1×1) at 25℃.

[0216] (3) High-temperature storage performance

[0217] After fully charging the battery to 4.25V at 25℃, it was discharged at a rate of 0.33C to 2.8V, and the discharge capacity was recorded as C2. After storing the lithium-ion battery at 60℃ for 30 days, the battery was first placed at 25℃ and discharged at a constant current of 1 / 3C to 2.8V, then charged at a constant current of 1 / 3C to 4.25V, then charged at a constant voltage to a current of 0.05C, and finally discharged at a constant current of 1 / 3C to 2.8V, and the discharge capacity was recorded as C3.

[0218] ① The capacity recovery rate after 30 days of storage at 60℃ is (C3 / C2)×100%.

[0219] Repeat the charging steps above and record the charging capacity as C4. Discharge the battery at a constant current of 1 / 3C to (50% × C4) and record the initial voltage as U4. Discharge the battery at a constant current of 1C for 30 seconds and record the final voltage as U5.

[0220] ② At 60℃, DCR = (U4 - U5) / (C4 × 1).

[0221] ③ The DCR growth rate after 30 days of storage at 60℃ is (DCR after 30 days of storage - initial DCR) / initial DCR × 100%.

[0222] Record the volume V1 of the lithium-ion battery at 25°C before storage at 60°C and the volume V2 at room temperature after storage at 60°C for 30 days.

[0223] ④ Volume expansion rate after 30 days of storage at 60℃ = (V2-V1) / V1×100%.

[0224] (4) Expansion rate of negative electrode after formation

[0225] The expansion rate of the negative electrode sheet after formation = (thickness of the negative electrode sheet after formation - thickness of the negative electrode sheet in the dry cell after drying) / thickness of the negative electrode sheet in the dry cell after drying × 100%.

[0226] The test results are shown in Table 2.

[0227]

[0228]

[0229] Note: In Table 1, " / " indicates that the condition parameter is not involved in the specific experiment.

[0230] As shown in Tables 1 and 2, the electrolyte of this invention uses 1,3-dioxane compounds (Formula I) and polyboronic acid compounds (Formula II) with specific structures. This electrolyte exhibits high conductivity, high ion mobility coefficient, low viscosity, and excellent chemical and electrochemical stability. Lithium-ion batteries containing this electrolyte have lower impedance, higher high-temperature capacity recovery rate, lower high-temperature volume expansion rate, and lower expansion rate of the fully charged negative electrode after formation.

[0231] In Examples 1-27 of this invention, the addition of 1,3-dioxane compounds and polyboronic acid compounds to the electrolyte results in excellent chemical and electrochemical stability. Lithium-ion batteries containing these compounds exhibit a DCR growth rate of less than 40%, and even less than 20%, after 30 days of storage at 60°C; the volume expansion rate after 30 days of storage at 60°C is less than 30%, and even less than 15%. Furthermore, the DCR is less than 350 mΩ at -20°C, less than 100 mΩ at 25°C, and the capacity recovery rate after 30 days of storage at 60°C can reach over 94%; the expansion rate of the fully charged negative electrode after formation is less than 10%.

[0232] In this invention, when a compound of formula I or formula ⅠⅠ is used alone in the electrolyte, even when combined with additives such as FEC or LIBOB, the aforementioned excellent effects cannot be achieved. Only when both are used together can the aforementioned effects be achieved. This is likely because compounds of Formula I exhibit better high-temperature stability and fewer interfacial side reactions, which is beneficial for improving cycle kinetics and significantly improving cycle life. Furthermore, their lower electrochemical reactivity and lower gas production from side reactions effectively reduce electron gain and loss at the interface. Simultaneously, these Formula I compounds can form a dense mesh-like SEI film on anodes, especially silicon anodes, where volume expansion is significant. This film exhibits high toughness and density, effectively suppressing the volume expansion of the anode sheet after formation. The interfacial film formed on silicon particles can compensate for defects such as active lithium loss and low initial efficiency caused by silicon materials. Compared to sintering and coating the silicon surface, the cost of performance improvement is also lower. Furthermore, Formula Ⅰ compounds readily form electron-deficient inorganic interfacial films on the cathode side, easily attracting electron-rich Formula Ⅱ compounds, thus facilitating the formation of a high-charge-density double-ion layer at the interface. This further reduces interfacial polarization and is more conducive to lithium-ion insertion / extraction kinetics.

[0233] Compared to Example 1, the electrolytes of Comparative Examples 1 and 3 contained FEC, but not compounds of Formula I and Formula II. The lithium-ion batteries containing these compounds showed significantly improved DCR growth rate after 30 days of storage at 60°C, DCR at -20°C, and DCR at 25°C. However, the volume expansion rate and capacity recovery rate after 30 days of storage at 60°C were significantly worse, and the expansion rate of the fully charged negative electrode after formation was also significantly increased. Similarly, compared to Example 4, the electrolytes of Comparative Examples 2 and 4 only contained FEC, without the addition of compounds of Formula I and Formula II, and the above performance was significantly worse. Even in the electrolyte of Comparative Example 5, which contained both FEC and LiBOB, the above effects were not improved and remained very poor.

[0234] In Comparative Example 6, the electrolyte used both FEC and Compound I. Compared to Comparative Example 1, which used only FEC, although the capacity recovery rate was improved after 30 days of storage at 60°C, the DCR at -20°C, DCR at 25°C, the DCR growth rate after 30 days of storage at 60°C, and the volume expansion rate after 30 days of storage at 60°C were all reduced. However, compared to Example 1, the DCR at -20°C, DCR at 25°C, the DCR growth rate after 30 days of storage at 60°C, and the volume expansion rate after 30 days of storage at 60°C were still significantly higher, and the capacity recovery rate after 30 days of storage at 60°C was significantly worse.

[0235] Compared to Example 1, the electrolyte in Comparative Example 7 contained only Compound I and no Compound II. Although the expansion rate of the fully charged negative electrode after formation was comparable, the lithium-ion battery containing Compound II exhibited poor capacity recovery and volume expansion rates after 30 days of storage at 60°C. Furthermore, the DCR growth rate, DCR at -20°C, and DCR at 25°C all significantly deteriorated, making it impossible to achieve optimal performance. Comparative Example 8, compared to Example 4, showed similar results and also failed to achieve superior performance.

[0236] Compared to Example 1, Comparative Example 9, which used a LiBOB-substituted compound II, showed comparable expansion rates of the fully charged negative electrode after formation. However, the volume expansion rate, capacity recovery rate, DCR growth rate, and DCR at -20°C and 25°C were significantly worse. Similarly, compared to Example 4, Comparative Example 10, which used a LiBOB-substituted compound II, also showed comparable expansion rates of the fully charged negative electrode after formation. However, the resulting lithium-ion battery exhibited poorer volume expansion rates after 30 days of storage at 60°C, and other performance characteristics were also significantly worse.

[0237] Compared with Example 16, the electrolyte of Comparative Example 11 contained only compound II and no compound I. The resulting lithium-ion battery showed worse DCR at -20°C, DCR at 25°C, DCR growth rate after 30 days of storage at 60°C, and capacity recovery rate after 30 days of storage at 60°C. In addition, the volume expansion rate of the lithium-ion battery after 30 days of storage at 60°C was significantly worse, and the expansion rate of the fully charged negative electrode after formation was also poor.

[0238] Compared with Example 18, the electrolyte of Comparative Example 12 contained only compound II and no compound I. The resulting lithium-ion battery showed worse DCR at -20°C, DCR at 25°C, DCR growth rate after 30 days of storage at 60°C, and capacity recovery rate after 30 days of storage at 60°C. Furthermore, the volume expansion rate of the lithium-ion battery after 30 days of storage at 60°C increased significantly, and the expansion rate of the fully charged negative electrode after formation also deteriorated significantly.

[0239] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electrolyte, characterized in that, The electrolyte comprises a 1,3-dioxane compound and a polyboronic acid compound; the structure of the 1,3-dioxane compound is shown in Formula I; the structure of the polyboronic acid compound is shown in Formula II-1 and / or Formula II-2. ； Formula I, Formula II-1, Formula II-2; In Equation I, n is selected from integers from 1 to 4; in Equations II-1 and II-2, n2 is selected independently from integers from 1 to 12; in Equation II-2, n3 is selected from integers from 1 to 3. In Formula II-1, R' is selected from one or more of hydrogen, alkyl, cyclic alkyl, alkenyl, cyclic alkenyl, alkynyl, cyclic alkenyl, haloalkyl, haloalkenyl, haloalkynyl, aryl and benzyl with 6 to 10 carbon atoms; In Formula II-2, M is selected from one or more of Li, Be, Na, Mg, K, Ca, Mn, Fe, Co, Ni, Cu, and Zn; The content of the 1,3-dioxane compound is 6% to 20%, which is the mass percentage of the electrolyte. The content of the polyboronic acid compound is 0.05% to 6%, and the percentage is the mass percentage of the electrolyte.

2. The electrolyte as described in claim 1, characterized in that, The 1,3-dioxane compound is selected from one or more of compound ac: 。 3. The electrolyte as described in claim 1, characterized in that, The polyboronic acid compound is selected from one or more of the compound dg: 。 4. The electrolyte as described in claim 1, characterized in that, The electrolyte satisfies one or more of the following conditions a: a. The content of the 1,3-dioxane compound is 6%~15%; b. The mass ratio of the 1,3-dioxane compound to the polyboronic acid compound is (0.05-120):1; c. The solvent in the electrolyte includes one or more of the following: cyclic carbonates, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, trifluoroethyl methyl carbonate, trifluoropropylene carbonate, trifluoromethyl propylene carbonate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate. d. The additives in the electrolyte include one or both of fluoroethylene carbonate and lithium dioxalate borate; e. The lithium salt in the electrolyte includes one or both of lithium hexafluorophosphate and lithium difluorosulfonylimide.

5. The electrolyte as described in claim 4, characterized in that, The electrolyte satisfies one or more of the following conditions: a. The content of the 1,3-dioxane compound is 6%~10%; b. The content of the polyboronic acid compound is 0.5%~6%; c. The mass ratio of the 1,3-dioxane compound to the polyboronic acid compound is (1-60):1; d. The cyclic carbonate is ethylene carbonate and / or propylene carbonate.

6. The electrolyte as described in claim 1, characterized in that, The electrolyte comprises cyclic carbonates and fluoroethylene carbonates, and the electrolyte satisfies the following conditions: 1≤Y1 / (Y2+Y3)≤40; 0.05≤Y2 / Y3≤70; 0.1%≤Y1≤35%； 0.1%≤Y2≤35%； Wherein, the cyclic carbonate is ethylene carbonate and / or propylene carbonate, Y1 is the mass percentage of the cyclic carbonate in the electrolyte, Y2 is the mass percentage of the fluoroethylene carbonate in the electrolyte, and Y3 is the mass percentage of the 1,3-dioxane compound in the electrolyte.

7. A lithium-ion battery, characterized in that, The lithium-ion battery includes the electrolyte as described in any one of claims 1-6.

8. The lithium-ion battery as described in claim 7, characterized in that, The lithium-ion battery satisfies one or more of the following conditions: a. The positive electrode active material in the lithium-ion battery is one or more of lithium iron manganese compound, lithium iron phosphate compound, and lithium manganese compound; b. The content of manganese in the positive electrode active material of the lithium-ion battery is >10%, and the percentage is the molar ratio of the total number of moles of metal elements other than lithium in the positive electrode active material; c. The negative electrode active material in the lithium-ion battery is selected from graphite and / or silicon materials.

9. The lithium-ion battery as described in claim 7, characterized in that, The negative electrode active material in the lithium-ion battery includes silicon, and the electrolyte includes fluoroethylene carbonate. The electrolyte meets the following conditions: 0.1≤(Y2+Y3) / Z1≤1; 0.1%≤Z1≤30%； 0.1%≤Y2≤30%； Wherein, Z1 is the mass percentage of the silicon material in the negative electrode active material; Y2 is the mass percentage of the fluoroethylene carbonate in the electrolyte; and Y3 is the mass percentage of the 1,3-dioxane compound in the electrolyte.

10. An electronic device, characterized in that, It includes lithium-ion batteries as described in any one of claims 7-9.

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