WO2023050360A1 - 电化学装置和包含其的电子装置 - Google Patents

电化学装置和包含其的电子装置 Download PDF

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WO2023050360A1
WO2023050360A1 PCT/CN2021/122316 CN2021122316W WO2023050360A1 WO 2023050360 A1 WO2023050360 A1 WO 2023050360A1 CN 2021122316 W CN2021122316 W CN 2021122316W WO 2023050360 A1 WO2023050360 A1 WO 2023050360A1
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positive electrode
compound
active material
electrochemical device
region
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PCT/CN2021/122316
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English (en)
French (fr)
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王可飞
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宁德新能源科技有限公司
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Priority to PCT/CN2021/122316 priority Critical patent/WO2023050360A1/zh
Priority to CN202180012300.XA priority patent/CN115053362A/zh
Publication of WO2023050360A1 publication Critical patent/WO2023050360A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/586—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries inside the batteries, e.g. incorrect connections of electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/59—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries characterised by the protection means

Definitions

  • the present application relates to the field of energy storage, in particular to an electrochemical device and an electronic device containing it, especially a lithium ion battery.
  • Lithium-ion batteries are widely used in electric vehicles and consumer electronics due to their advantages such as high energy density, high output power, long cycle life and low environmental pollution.
  • lithium-ion batteries are subjected to abnormal conditions such as extrusion, collision or puncture, they are prone to fire and explosion, causing serious hazards. Therefore, the safety problems of lithium-ion batteries have largely limited the application and popularization of lithium-ion batteries.
  • the present application solves the problems existing in the prior art to some extent by providing an electrochemical device and an electronic device that can improve the intermittent cycle performance of the electrochemical device under high temperature and high pressure, and effectively improve the safety performance under high voltage. question.
  • the present application provides an electrochemical device, the electrochemical device includes: a positive electrode, a negative electrode and an electrolyte, the positive electrode includes a positive electrode current collector and a positive electrode active material area on the positive electrode current collector , an insulating region and an interactive region; the interactive region is located between the positive active material region and the insulating region, and is connected to the positive active material region and the insulating region; the positive active material region includes a positive electrode active material; the insulating region includes inorganic filler; the interactive region includes the positive active material and the inorganic filler; and the electrolyte includes at least one of a compound with a cyano group or a compound with a sulfur-oxygen double bond kind.
  • the electrolyte includes a compound with a cyano group and a compound with a sulfur-oxygen double bond, wherein based on the mass of the electrolyte, the mass percentage of the compound with a cyano group is a%, and the The mass percentage of the compound having sulfur-oxygen double bonds is b%, wherein a and b satisfy: 0.1 ⁇ a+b ⁇ 15; and 0.5 ⁇ a/b ⁇ 20.
  • the mass of the positive electrode active material region is A 1 mg/1540.25mm 2
  • the mass of the insulating region is A 2 mg/1540.25mm 2
  • a 1 and A 2 satisfy: A 1 /A 2 >1.2.
  • the mass of the positive electrode active material region is A 1 mg/1540.25mm 2 , and the value of A 1 ranges from 100 to 400.
  • the mass percentage of the inorganic filler in the insulating region is M 1 %, and the mass of the insulating region is A 2 g/1540.25mm 2 , wherein M 1 and A 2 Satisfy: 0.3 ⁇ M 1 /A 2 ⁇ 1.5.
  • the mass of the positive electrode active material region is A 1 mg/1540.25mm 2 , wherein based on the mass of the electrolyte, the mass percentage of the compound having a cyano group is a%, wherein A 1 and a satisfies: A 1 /a>8.
  • the inorganic filler includes at least one of silica, alumina, hydrated alumina, titania, magnesia, magnesium hydroxide, alumina doped silica, or boehmite.
  • the compound having a cyano group includes at least one of the following compounds: succinonitrile, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyano Hexyl hexane, tetramethylsuccinonitrile, 2-methylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 1,4-di Cyanopentane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, ethylene glycol bis(propionitrile) ether, 3,5-dioxa- Pimelonitrile, 1,4-bis(cyanoethoxy)butane, diethylene glycol bis(2-cyanoethyl)ether, triethylene glycol bis(2-cyanoethyl)ether, tetra Ethylene glycol bis(2-cyanoethyl)
  • the compound having a cyano group includes at least two dinitrile compounds.
  • the compound having a cyano group includes dinitrile compounds and trinitrile compounds.
  • the compound having a cyano group includes a dinitrile compound having an ether linkage or a trinitrile compound having an ether linkage.
  • the compound having a sulfur-oxygen double bond includes at least one of the following compounds: bicyclic sulfate, bicyclic sultone, vinyl sulfate, propylene sulfate, 1,3-propane sultone , 1,3-propene sultone, methylene methanedisulfonate or ethylene methanedisulfonate; wherein based on the quality of the electrolyte, the mass percent of the compound with a sulfur-oxygen double bond is b %, the value range of b is 0.001 to 8.
  • the compound having a sulfur-oxygen double bond includes a compound of formula 1:
  • Each instance of L is independently selected from a single bond or methylene; m is 1, 2, 3 or 4;
  • the compound of formula 1 includes at least one of the following compounds:
  • the compound of formula 1 includes at least one of the following compounds:
  • the bicyclic sultone comprises a compound of formula 2:
  • a 1 , A 2 , A 3 , and A 4 are each independently selected from substituted or unsubstituted alkylene groups
  • a 1 , A 2 , A 3 , and A 4 are each independently substituted, the substituents are selected from halogen, alkyl or halogen-substituted alkyl.
  • the compound of formula 2 includes at least one of the following compounds:
  • the positive active material region includes a polyhydric alcohol.
  • the polyol includes at least one of the following compounds: methylene glycol, ethylene glycol, propylene glycol, isoprene glycol, 1,3-butanediol, 1,4-butanediol, Diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, glycerin, diglycerol, or polyglycerol.
  • the present application provides an electronic device, which includes the electrochemical device according to the embodiment of the present application.
  • the electrochemical device provided by the present application has improved intermittent cycle performance and safety performance under high temperature and high pressure.
  • Figure 1 shows a picture of the surface of the positive electrode in one embodiment of the present application.
  • FIG. 2 shows a schematic structural view of the positive electrode surface in a comparative example of the present application.
  • Fig. 3 shows a schematic structural view of the positive electrode surface in one embodiment of the present application.
  • Fig. 4 shows a schematic structural view of the positive electrode surface in one embodiment of the present application.
  • a list of items linked by the terms “one of”, “one of”, “one of” or other similar terms may mean that any of the listed items one.
  • the phrase “one of A and B” means only A or only B.
  • the phrase “one of A, B, and C” means only A; only B; or only C.
  • Item A may contain a single element or multiple elements.
  • Item B may contain a single element or multiple elements.
  • Item C may contain a single element or multiple elements.
  • a list of items linked by the terms “at least one of”, “at least one of”, “at least one of” or other similar terms may mean that the listed items any combination of .
  • the phrase “at least one of A and B” means only A; only B; or A and B.
  • the phrase “at least one of A, B, and C” means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.
  • Item A may contain a single element or multiple elements.
  • Item B may contain a single element or multiple elements.
  • Item C may contain a single element or multiple elements.
  • the present application provides an electrochemical device, and the electrochemical device includes a positive electrode, a negative electrode, and an electrolyte.
  • the positive electrode includes a positive electrode current collector and a positive electrode active material region on one or both surfaces of the positive electrode current collector.
  • the positive active material region includes a positive active material.
  • the positive electrode active material region may be one or more layers, and each layer in the multilayer positive electrode active material region may contain the same or different positive electrode active materials.
  • the positive electrode active material is any material capable of reversibly intercalating and deintercalating metal ions such as lithium ions.
  • the discharge capacity of the positive active material is smaller than the chargeable capacity of the positive active material to prevent unintentional deposition of lithium metal on the negative electrode during charging.
  • the positive electrode current collector has a current collector exposed portion that does not form a positive electrode active material region, and the positive electrode current collector exposed portion is measured from the winding axis direction of the wound electrode body (that is, the sheet width perpendicular to the above-mentioned length direction) Direction) formed in such a way that one end protrudes outward.
  • the positive electrode current collector exposed portion is joined to the positive electrode current collector.
  • the positive electrode has an insulating region formed on the positive current collector and an alternating region formed on the positive current collector.
  • the insulating region is disposed along the end of the positive electrode active material region on the side where the positive electrode current collector is exposed, and the insulating region extends along the length direction of the positive electrode.
  • the insulating region is located between the positive electrode active material region and the positive electrode current collector exposed portion in the width direction of the positive electrode. In some embodiments, the exposed portion of the positive current collector is covered by an insulating region.
  • the interaction region is located at the boundary between the insulating region and the positive electrode active material region, and the interaction region extends along the length direction of the positive electrode. Therefore, the interaction region is located between the positive electrode active material region and the insulating region. In addition, the interaction region is in contact with the positive electrode active material region and the insulating region.
  • Figure 1 shows a picture of the surface of the positive electrode in one embodiment of the present application. It can be seen from FIG. 1 that the interaction region is located between the positive electrode active material region and the insulating region, and extends along the length direction of the positive electrode.
  • FIG. 2 shows a schematic structural view of the positive electrode surface in a comparative example of the present application, where 200 is the positive electrode surface, 210 is the positive electrode active material area on the positive electrode current collector, and 220 is the exposed part of the positive electrode current collector. In this example, the exposed portion of the positive electrode current collector was not covered.
  • 3 shows a schematic view of the structure of the positive electrode surface in one embodiment of the present application, wherein 300 is the positive electrode surface, 310 is the positive electrode active material area located on the positive electrode current collector, 320 is the interaction area located on the positive electrode current collector, and 330 is the positive electrode active material area located on the positive electrode current collector.
  • Figure 4 shows a schematic view of the structure of the positive electrode surface in one embodiment of the present application, wherein 400 is the positive electrode surface, 410 is the positive electrode active material area located on the positive electrode current collector, 420 is the interaction area located on the positive electrode current collector, and 430 is the positive electrode active material area located on the positive electrode current collector.
  • the insulating region on the positive current collector, and 440 is the exposed part of the positive current collector. In this example, the exposed portion of the positive electrode collector was not completely covered.
  • the mass of the positive electrode active material region is A 1 mg/1540.25mm 2
  • the mass of the insulating region is A 2 mg/1540.25mm 2
  • a 1 and A 2 satisfy: A 1 /A 2 >1.2.
  • the mass of the positive electrode active material region is A 1 mg/1540.25mm 2 , and the value of A 1 ranges from 100 to 400.
  • the value of A1 is 100, 120, 140, 150, 160, 180, 200, 220, 240, 250, 280, 300, 330, 350, 380, 400 or any two of these values range of composition.
  • the mass of the insulating region is A 2 mg/1540.25mm 2 , and the value of A 2 is 60 to 250. In some embodiments, the value of A2 is 60, 70, 80, 100, 120, 140, 150, 160, 180, 200, 220, 230, 240, 250 or a combination of any two of these values scope.
  • the mass percentage of the inorganic filler in the insulating region is M 1 %, and the mass of the insulating region is A 2 g/1540.25mm 2 , wherein M 1 and A 2 Satisfy: 0.3 ⁇ M 1 /A 2 ⁇ 1.5.
  • M 1 /A 2 0.6 ⁇ M 1 /A 2 ⁇ 1.5. In some embodiments, the value of M 1 /A 2 is 0.3, 0.5, 0.6, 0.7, 0.9, 1.2, 1.4, 1.5 or a range consisting of any two of these values.
  • the range of M 1 is 80-95. In some embodiments, the range of M 1 is 85-95. In some embodiments, the value of M 1 is 80, 82, 85, 88, 90, 92, 95 or a range consisting of any two of these values.
  • the insulating region is located on both surfaces or one surface of the positive current collector. In some embodiments, the interaction region is located on both sides or one side of the positive current collector.
  • the inorganic filler includes at least one of silica, alumina, hydrated alumina, titania, magnesia, magnesium hydroxide, alumina doped silica, or boehmite.
  • the shape of the inorganic filler may be particle shape, fiber shape, plate shape, flake shape and the like.
  • the average particle diameter of the inorganic filler is not less than 0.01 ⁇ m and not more than 10 ⁇ m, preferably not less than 0.1 ⁇ m and not more than 5 ⁇ m, more preferably not less than 0.5 ⁇ m and not more than 3 ⁇ m.
  • the average particle size (median particle size D50) of the inorganic filler can be measured, for example, by laser diffraction scattering method or the like.
  • the inorganic filler is an insulating inorganic particle.
  • examples of the inorganic particles include, but are not limited to, inorganic oxides (such as aluminum oxide, magnesium oxide, silicon dioxide, titanium oxide, etc.), nitrides (such as aluminum nitride, silicon nitride, etc. ), alumina hydrate, metal hydroxides other than alumina hydrate (such as potassium hydroxide, magnesium hydroxide, etc.), clay minerals (such as mica, talc, zeolite, apatite, kaolin, etc.), glass fibers, etc. . These may be used alone or in combination of two or more.
  • the insulating region may contain an adhesive.
  • the adhesive includes, but is not limited to, acrylic adhesive, styrene butadiene rubber (SBR), polyolefin adhesive, etc., and polyvinylidene fluoride ( PVDF), polytetrafluoroethylene (PTFE) and other fluorine-based polymers.
  • the content of the binder in the insulating region is not particularly limited.
  • the content of the binder is not less than 1% and not more than 30%, preferably not less than 3% and not more than 25%.
  • the content of the binder is 1%, 5%, 10%, 15%, 20%, 25%, 30%, or a range consisting of any two of these values.
  • the interaction area at least contains: the positive active material contained in the positive active material area; and the inorganic filler contained in the insulating area.
  • the interaction region is a layer formed by mixing the above components of the positive electrode active material region and the above components of the insulating region. Therefore, the alternating region may contain constituent components of the positive electrode active material region and/or constituent components of the insulating region other than the above-mentioned positive electrode active material and the above-mentioned inorganic filler. For example, the interactive region further contains a binder in the positive electrode active material region and/or the insulating region.
  • the interactive region contains a positive electrode active material, a conductive material , the binder of the positive electrode active material area, the inorganic filler, the binder of the insulating area.
  • the interactive zone contains alumina hydrate.
  • the alternating region contains alumina hydrate
  • the alternating region contains alumina hydrate in addition to the above-mentioned positive electrode active material and the above-mentioned inorganic filler.
  • the alternating region contains alumina hydrate in addition to the above-mentioned positive electrode active material and the above-mentioned inorganic filler.
  • the alumina hydrate contains hydroxyl groups.
  • alumina hydrates include, but are not limited to, aluminum oxyhydroxide (AlOOH) as crystalline alumina monohydrate; aluminum hydroxide (Al(OH) 3 ); and alumina gel, which is amorphous alumina hydrate, and the like.
  • AlOOH aluminum oxyhydroxide
  • Al(OH) 3 aluminum hydroxide
  • alumina gel which is amorphous alumina hydrate, and the like.
  • the crystalline alumina hydrate ie, crystalline alumina monohydrate and crystalline alumina trihydrate
  • the aluminum oxide hydrate is preferably aluminum oxyhydroxide, such as boehmite, which can further improve the safety performance.
  • the average particle diameter (median particle diameter D50) of the alumina hydrate is not particularly limited.
  • the average particle size of the alumina hydrate is preferably 0.5 ⁇ m or more.
  • the average particle size of the alumina hydrate is preferably 3 ⁇ m or less.
  • the average particle diameter (median diameter D50) of alumina hydrate can be measured by laser diffraction scattering method etc., for example.
  • the interactive region can be formed by applying the paste forming the positive electrode active material region and the paste forming the insulating region on the positive electrode current collector simultaneously or sequentially in such a way that they are adjacent to each other, and applying these The paste dries at the same time. At this time, before drying, the paste forming the positive electrode active material region and the paste forming the insulating region are mixed at the interface, and thus an interactive region is formed at the interface of the positive electrode active material region and the insulating region.
  • the interactive region can contain alumina hydrate; or, the paste for forming the positive electrode active material region, the paste for forming the insulating region and the paste for forming the interactive region can also be used.
  • the paste containing alumina hydrate in the region is used to form the positive electrode active material region, the insulating region and the interactive region.
  • the positive active material region further includes polyhydric alcohol.
  • the polyol includes at least one of the following compounds: methylene glycol, ethylene glycol, propylene glycol, isoprene glycol, 1,3-butanediol, 1,4-butanediol, Diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, glycerin, diglycerol, or polyglycerol.
  • the content of the polyhydric alcohol is not more than 0.3%. In some embodiments, based on the total weight of the positive electrode active material region, the content of the polyol is 0.01%, 0.05%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.25%, 0.28% , 0.3%, or a range consisting of any two of these values.
  • the type of the positive electrode active material is not particularly limited, as long as it can absorb and release metal ions (eg, lithium ions) electrochemically.
  • the positive active material is a material containing lithium and at least one transition metal. Examples of positive active materials may include, but are not limited to, lithium transition metal composite oxides and lithium transition metal phosphate compounds.
  • the transition metals in the lithium transition metal composite oxide include V, Ti, Cr, Mn, Fe, Co, Ni, Cu, and the like.
  • lithium transition metal composite oxides include lithium cobalt composite oxides such as LiCoO 2 , lithium nickel composite oxides such as LiNiO 2 , lithium manganese composite oxides such as LiMnO 2 , LiMn 2 O 4 , Li 2 MnO 4 , lithium nickel manganese cobalt composite oxides such as LiNi 1/3 Mn 1/3 Co 1/3 O 2 , LiNi 0.5 Mn 0.3 Co 0.2 O 2 , etc., in which a part of the transition metal atom which is the main body of these lithium transition metal composite oxides is Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, W and other elements substituted .
  • lithium transition metal composite oxides may include, but are not limited to, LiNi 0.5 Mn 0.5 O 2 , LiNi 0.85 Co 0.10 Al 0.05 O 2 , LiNi 0.33 Co 0.33 Mn 0.33 O 2 , LiNi 0.45 Co 0.10 Al 0.45 O 2 , LiMn 1.8 Al 0.2 O 4 and LiMn 1.5 Ni 0.5 O 4 etc.
  • combinations of lithium transition metal composite oxides include, but are not limited to, combinations of LiCoO 2 and LiMn 2 O 4 , wherein a part of Mn in LiMn 2 O 4 may be replaced by transition metals (for example, LiNi 0.33 Co 0.33 Mn 0.33 O 2 ), part of Co in LiCoO 2 can be replaced by transition metals.
  • the transition metals in the lithium-containing transition metal phosphate compound include V, Ti, Cr, Mn, Fe, Co, Ni, Cu, and the like.
  • lithium-containing transition metal phosphate compounds include iron phosphates such as LiFePO 4 , Li 3 Fe 2 (PO 4 ) 3 , LiFeP 2 O 7 , and cobalt phosphates such as LiCoPO 4 , wherein as these lithium transition metal phosphate compounds Some of the transition metal atoms of the main body are replaced by other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si, etc.
  • lithium phosphate is included in the positive active material, which can improve the continuous charging characteristics of the electrochemical device.
  • the use of lithium phosphate is not limited.
  • the positive electrode active material and lithium phosphate are used in combination.
  • the content of lithium phosphate is greater than 0.1%, greater than 0.3% or greater than 0.5% relative to the weight of the positive electrode active material and lithium phosphate.
  • the content of lithium phosphate is less than 10%, less than 8% or less than 5% relative to the weight of the positive electrode active material and lithium phosphate.
  • the content of lithium phosphate is within the range formed by any two values above.
  • a substance different from its composition may be attached to the surface of the positive electrode active material.
  • surface attachment substances may include, but are not limited to: oxides such as alumina, silica, titania, zirconia, magnesia, calcium oxide, boron oxide, antimony oxide, bismuth oxide; lithium sulfate, sodium sulfate, potassium sulfate , magnesium sulfate, calcium sulfate, aluminum sulfate and other sulfates; lithium carbonate, calcium carbonate, magnesium carbonate and other carbonates; carbon, etc.
  • these surface attachment substances can be attached to the surface of the positive electrode active material by the following methods: dissolving or suspending the surface attachment substances in a solvent and infiltrating them into the positive electrode active material and drying them; making the surface attachment A method of dissolving or suspending the substance precursor in a solvent, infiltrating and adding it to the positive electrode active material, and then reacting it by heating; and a method of firing while adding it to the positive electrode active material precursor.
  • attaching carbon a method of mechanically attaching a carbon material (for example, activated carbon, etc.) can also be used.
  • the content of the surface attachment substance is greater than 0.1 ppm, greater than 1 ppm or greater than 10 ppm based on the weight of the positive electrode active material region. In some embodiments, the content of the surface attachment material is less than 10%, less than 5% or less than 2% based on the weight of the positive electrode active material region. In some embodiments, based on the weight of the positive electrode active material region, the content of the surface attachment substance is within the range formed by any two values above.
  • the oxidation reaction of the electrolyte solution on the surface of the positive electrode active material can be suppressed, and the life of the electrochemical device can be improved.
  • the amount of the surface-attached substance is too small, the effect cannot be fully expressed; when the amount of the surface-attached substance is too large, it will hinder the entry and exit of lithium ions, so the resistance may increase.
  • a positive electrode active material having a composition different from the positive electrode active material attached to the surface of the positive electrode active material is also referred to as a "positive electrode active material”.
  • the shape of the positive active material includes, but is not limited to, block shape, polyhedron shape, spherical shape, ellipsoidal shape, plate shape, needle shape, columnar shape, and the like.
  • the positive active material particles include primary particles, secondary particles, or a combination thereof. In some embodiments, primary particles may agglomerate to form secondary particles.
  • the tap density of the positive active material is greater than 0.5 g/cm 3 , greater than 0.8 g/cm 3 or greater than 1.0 g/cm 3 .
  • the tap density of the positive electrode active material is within the above-mentioned range, the amount of dispersion medium required for the formation of the positive electrode active material region and the required amount of the conductive material and the positive electrode binder can be suppressed, thereby ensuring the filling of the positive electrode active material rate and capacity of the electrochemical device.
  • a composite oxide powder having a high tap density a high-density positive electrode active material region can be formed. The larger the tap density is generally, the more preferable it is, and there is no particular upper limit.
  • the tap density of the positive active material is less than 4.0 g/cm 3 , less than 3.7 g/cm 3 or less than 3.5 g/cm 3 .
  • the tap density of the positive electrode active material has the upper limit as described above, a decrease in load characteristics can be suppressed.
  • the tap density of the positive active material can be calculated in the following way: put 5g to 10g of positive active material powder into a 10mL glass measuring cylinder, and vibrate 200 times with a stroke of 20mm to obtain the powder packing density (tap density ).
  • the median diameter (D50) of the positive electrode active material particles refers to the primary particle diameter of the positive electrode active material particles.
  • the median diameter (D50) of the positive electrode active material particles refers to the secondary particle diameter of the positive electrode active material particles.
  • the median diameter (D50) of the positive electrode active material particles is greater than 0.3 ⁇ m, greater than 0.5 ⁇ m, greater than 0.8 ⁇ m or greater than 1.0 ⁇ m. In some embodiments, the median diameter (D50) of the positive electrode active material particles is less than 30 ⁇ m, less than 27 ⁇ m, less than 25 ⁇ m or less than 22 ⁇ m. In some embodiments, the median diameter (D50) of the positive electrode active material particles is within the range formed by any two values above. When the median diameter (D50) of the positive electrode active material particles is within the above-mentioned range, a positive electrode active material with a high tap density can be obtained, and a decrease in the performance of the electrochemical device can be suppressed.
  • the positive electrode active material particle median diameter (D50) can be measured by a laser diffraction/scattering particle size distribution analyzer: in the case of using LA-920 manufactured by HORIBA Corporation as a particle size distribution meter, use 0.1% sodium hexametaphosphate aqueous solution as The dispersion medium used in the measurement was measured after 5 minutes of ultrasonic dispersion with the refractive index set to 1.24.
  • the electrolytic solution used in the electrochemical device of the present application includes an electrolyte and a solvent for dissolving the electrolyte. In some embodiments, the electrolyte solution used in the electrochemical device of the present application further includes additives.
  • the electrolyte solution includes at least one of a compound having a cyano group or a compound having a sulfur-oxygen double bond.
  • the compound having a cyano group includes at least one of the following compounds: succinonitrile, glutaronitrile, adiponitrile, 1,5-dicyanopentane, 1,6-dicyano Hexyl hexane, tetramethylsuccinonitrile, 2-methylglutaronitrile, 2,4-dimethylglutaronitrile, 2,2,4,4-tetramethylglutaronitrile, 1,4-di Cyanopentane, 1,2-dicyanobenzene, 1,3-dicyanobenzene, 1,4-dicyanobenzene, ethylene glycol bis(propionitrile) ether, 3,5-dioxa- Pimelonitrile, 1,4-bis(cyanoethoxy)butane, diethylene glycol bis(2-cyanoethyl)ether, triethylene glycol bis(2-cyanoethyl)ether, tetra Ethylene glycol bis(2-cyanoethyl)
  • the above-mentioned compounds having a cyano group can be used alone or in any combination. If the electrolyte contains two or more compounds with cyano groups, the content of the compounds with cyano groups refers to the total content of the two or more compounds with cyano groups.
  • the mass percentage of the compound having a cyano group is a%, and the value of a ranges from 0.1 to 15. In some embodiments, the value of a is 0.1, 0.4, 0.8, 1, 1.6, 2.0, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or these A range consisting of any two of the values.
  • the compound having a cyano group includes at least two dinitrile compounds. In some embodiments, the compound having a cyano group includes dinitrile compounds and trinitrile compounds. In some embodiments, the compound having a cyano group includes a dinitrile compound having an ether linkage or a trinitrile compound having an ether linkage.
  • a 1 and a satisfy: A 1 /a>8. In some embodiments, A 1 and a satisfy: A 1 /a ⁇ 10. In some embodiments, A 1 and a satisfy: A 1 /a ⁇ 15. In some embodiments, A 1 and a satisfy: A 1 /a ⁇ 20. In some embodiments, A 1 and a satisfy: A 1 /a ⁇ 30. In some embodiments, A 1 and a satisfy: A 1 /a ⁇ 40. In some embodiments, the value of A 1 /a is 8, 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, 45 or any of these values range of both.
  • the compound having a sulfur-oxygen double bond includes at least one of the following compounds: bicyclic sulfate, bicyclic sultone, vinyl sulfate, propylene sulfate, 1,3-propane sultone , 1,3-propene sultone, methylene methanedisulfonate or ethylene methanedisulfonate.
  • the compound having a sulfur-oxygen double bond includes a compound of formula 1:
  • Each instance of L is independently selected from a single bond or methylene; m is 1, 2, 3 or 4;
  • the compound of formula 1 includes at least one of the following compounds:
  • the compound of formula 1 includes at least one of the following compounds:
  • the bicyclic sultone comprises a compound of formula 2:
  • a 1 , A 2 , A 3 , and A 4 are each independently selected from substituted or unsubstituted alkylene groups
  • a 1 , A 2 , A 3 , and A 4 are each independently substituted, the substituents are selected from halogen, alkyl or halogen-substituted alkyl.
  • the compound of formula 2 includes at least one of the following compounds:
  • the mass percentage of the compound having a sulfur-oxygen double bond is b%, and the value of b ranges from 0.001 to 8. In some embodiments, the value of b is 0.001, 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8 or among these values Any range consisting of the two.
  • the electrolytic solution includes a compound having a cyano group and a compound having a sulfur-oxygen double bond, and satisfies the relationships: 0.1 ⁇ a+b ⁇ 15; and 0.5 ⁇ a/b ⁇ 20. In some embodiments, 0.1 ⁇ a+b ⁇ 15; and 2 ⁇ a/b ⁇ 12. In some embodiments, the value of a+b is 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or among these values Any range consisting of the two. In some embodiments, the value of a/b is 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 , 19, 20, or a range consisting of any two of these values.
  • the electrolyte solution further comprises any non-aqueous solvent known in the prior art as a solvent for the electrolyte solution.
  • the non-aqueous solvent includes, but is not limited to, one or more of the following: cyclic carbonate, chain carbonate, cyclic carboxylate, chain carboxylate, cyclic Ethers, chain ethers, phosphorus-containing organic solvents, sulfur-containing organic solvents, and aromatic fluorinated solvents.
  • examples of the cyclic carbonate may include, but are not limited to, one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate.
  • the cyclic carbonate has 3-6 carbon atoms.
  • examples of the chain carbonate may include, but are not limited to, one or more of the following: dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate (DEC), methyl carbonate Chain carbonates such as ethyl n-propyl carbonate, ethyl n-propyl carbonate, di-n-propyl carbonate, etc.
  • chain carbonates substituted with fluorine may include, but are not limited to, one or more of the following: bis(fluoromethyl)carbonate, bis(difluoromethyl)carbonate, bis(trifluoromethyl)carbonate base) carbonate, bis(2-fluoroethyl)carbonate, bis(2,2-difluoroethyl)carbonate, bis(2,2,2-trifluoroethyl)carbonate, 2-fluoroethyl methyl carbonate, 2,2-difluoroethyl methyl carbonate and 2,2,2-trifluoroethyl methyl carbonate, etc.
  • examples of the cyclic carboxylate may include, but are not limited to, one or more of the following: one or more of ⁇ -butyrolactone and ⁇ -valerolactone.
  • some of the hydrogen atoms of the cyclic carboxylate may be replaced by fluorine.
  • examples of the chain carboxylate may include, but are not limited to, one or more of the following: methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate ester, sec-butyl acetate, isobutyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate, butyric acid Propyl ester, methyl isobutyrate, ethyl isobutyrate, methyl valerate, ethyl valerate, methyl pivalate and ethyl pivalate, etc.
  • part of the hydrogen atoms of the chain carboxylate may be substituted by fluorine.
  • examples of fluorine-substituted chain carboxylic acid esters may include, but are not limited to, methyl trifluoroacetate, ethyl trifluoroacetate, propyl trifluoroacetate, butyl trifluoroacetate, and trifluoroacetic acid 2,2,2-trifluoroethyl ester, etc.
  • examples of the cyclic ether may include, but are not limited to, one or more of the following: tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 2-methyl 1,3-dioxolane, 4-methyl 1,3-dioxolane, 1,3-dioxane, 1,4-dioxane and dimethoxypropane.
  • examples of the chain ethers may include, but are not limited to, one or more of the following: dimethoxymethane, 1,1-dimethoxyethane, 1,2- Dimethoxyethane, diethoxymethane, 1,1-diethoxyethane, 1,2-diethoxyethane, ethoxymethoxymethane, 1,1-ethoxy Methoxyethane and 1,2-ethoxymethoxyethane, etc.
  • examples of the phosphorus-containing organic solvent may include, but are not limited to, one or more of the following: trimethyl phosphate, triethyl phosphate, dimethyl ethyl phosphate, methyl phosphate Diethyl ester, ethylene methyl phosphate, ethylene ethyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, triphenyl phosphite, tris(2,2,2- phosphate Trifluoroethyl) ester and tris(2,2,3,3,3-pentafluoropropyl) phosphate, etc.
  • examples of the sulfur-containing organic solvent may include, but are not limited to, one or more of the following: sulfolane, 2-methylsulfolane, 3-methylsulfolane, dimethylsulfone, disulfone Ethyl sulfone, ethyl methyl sulfone, methyl propyl sulfone, dimethyl sulfoxide, methyl methanesulfonate, ethyl methanesulfonate, methyl ethanesulfonate, ethyl ethanesulfonate, dimethyl sulfate , diethyl sulfate and dibutyl sulfate.
  • some hydrogen atoms of the sulfur-containing organic solvent may be replaced by fluorine.
  • the aromatic fluorinated solvent includes, but is not limited to, one or more of the following: fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene and trifluoromethylbenzene.
  • the solvent used in the electrolyte of the present application includes cyclic carbonates, chain carbonates, cyclic carboxylates, chain carboxylates, and combinations thereof.
  • the solvent used in the electrolyte of the present application comprises an organic solvent selected from the group consisting of ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl propionate, propyl propionate , n-propyl acetate, ethyl acetate, and combinations thereof.
  • the solvent used in the electrolyte of the present application includes: ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl propionate, propyl propionate, ⁇ -butyrolactone and combinations thereof.
  • the electrolyte is not particularly limited, and any known substance as an electrolyte can be used arbitrarily.
  • lithium salts are generally used.
  • electrolytes may include, but are not limited to, inorganic lithium salts such as LiPF 6 , LiBF 4 , LiClO 4 , LiAlF 4 , LiSbF 6 , LiWF 7 ; lithium tungstates such as LiWOF 5 ; HCO 2 Li, CH 3 CO 2 Li, CH 2 FCO 2 Li, CHF 2 CO 2 Li, CF 3 CO 2 Li, CF 3 CH 2 CO 2 Li, CF 3 CF 2 CO 2 Li, CF 3 CF 2 CO 2 Li, CF 3 CF 2 CF 2 CO 2 Li, CF 3 CF 2 CF 2 Lithium carboxylate salts such as CF 2 CO 2 Li; FSO 3 Li, CH 3 SO 3 Li, CH 2 FSO 3 Li, CHF 2 SO 3 Li, CF 3 SO 3 Li, CF 3 CF 2 SO 3 Li, CF 3
  • the electrolyte is selected from LiPF 6 , LiSbF 6 , FSO 3 Li, CF 3 SO 3 Li, LiN(FSO 2 ) 2 , LiN(FSO 2 )(CF 3 SO 2 ), LiN(CF 3 SO 2 ) 2 , LiN(C 2 F 5 SO 2 ) 2 , cyclic lithium 1,2-perfluoroethanebissulfonimide, cyclic lithium 1,3-perfluoropropanebissulfonimide, LiC(FSO 2 ) 3 , LiC(CF 3 SO 2 ) 3 , LiC(C 2 F 5 SO 2 ) 3 , LiBF 3 CF 3 , LiBF 3 C 2 F 5 , LiPF 3 (CF 3 ) 3 , LiPF 3 (C 2 F 5 ) 3.
  • Lithium difluorooxalate borate, lithium bis(oxalate)borate or lithium difluorobis(oxalato)phosphate which help to improve the output power characteristics, high-rate charge-discharge characteristics, and high-temperature storage characteristics of electrochemical devices and cycle characteristics, etc.
  • the content of the electrolyte is not particularly limited as long as the effect of the present application is not impaired.
  • the total molar concentration of lithium in the electrolyte is greater than 0.3 mol/L, greater than 0.4 mol/L or greater than 0.5 mol/L.
  • the total molar concentration of lithium in the electrolyte is less than 3 mol/L, less than 2.5 mol/L or less than 2.0 mol/L.
  • the total molar concentration of lithium in the electrolyte is within the range formed by any two values above. When the electrolyte concentration is within the above range, the lithium as charged particles will not be too small, and the viscosity can be kept in an appropriate range, so it is easy to ensure good electrical conductivity.
  • the electrolyte includes at least one salt selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate.
  • the electrolyte includes a salt selected from the group consisting of monofluorophosphate, oxalate, and fluorosulfonate.
  • the electrolyte includes a lithium salt.
  • the salt selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate is present at greater than 0.01% or greater than 0.1% by weight of the electrolyte.
  • the salt selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate comprises less than 20% or less than 10% by weight of the electrolyte. In some embodiments, the content of the salt selected from the group consisting of monofluorophosphate, borate, oxalate and fluorosulfonate is within the range formed by any two values above.
  • the electrolyte includes one or more substances selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate and one or more salts other than these.
  • Other salts include the lithium salts exemplified above, and in some examples, LiPF 6 , LiN(FSO 2 )(CF 3 SO 2 ), LiN(CF 3 SO 2 ) 2 , LiN( C 2 F 5 SO 2 ) 2 , cyclic lithium 1,2-perfluoroethanebissulfonimide, cyclic lithium 1,3-perfluoropropanebissulfonimide, LiC(FSO 2 ) 3 , LiC (CF 3 SO 2 ) 3 , LiC(C 2 F 5 SO 2 ) 3 , LiBF 3 CF 3 , LiBF 3 C 2 F 5 , LiPF 3 (CF 3 ) 3 , LiPF 3 (C 2 F 5 ) 3 .
  • the additional salt is LiPF 6
  • the additional salts are present at greater than 0.01% or greater than 0.1% by weight of the electrolyte. In some embodiments, the additional salts are present at less than 20%, less than 15%, or less than 10% by weight of the electrolyte. In some embodiments, the content of other salts is within the range formed by any two values above. Salts other than these having the above content contribute to the balance of the electrical conductivity and viscosity of the electrolytic solution.
  • the negative electrode includes a negative electrode current collector and a negative electrode active material region disposed on one or both surfaces of the negative electrode current collector, and the negative electrode active material layer contains the negative electrode active material.
  • the negative electrode active material layer may be one or more layers, and each layer of the multilayer negative electrode active material may contain the same or different negative electrode active materials.
  • the negative electrode active material is any material capable of reversibly intercalating and deintercalating metal ions such as lithium ions.
  • the chargeable capacity of the negative active material is greater than the discharge capacity of the positive active material, so as to prevent unintentional precipitation of lithium metal on the negative electrode during charging.
  • any known current collector can be used arbitrarily.
  • negative electrode current collectors include, but are not limited to, metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. In some embodiments, the negative current collector is copper.
  • the form of the negative electrode current collector may include, but not limited to, metal foil, metal cylinder, metal strip, metal plate, metal film, expanded metal, stamped metal, foamed metal, etc.
  • the negative electrode current collector is a metal film.
  • the negative electrode current collector is copper foil.
  • the negative electrode current collector is a rolled copper foil based on a rolling method or an electrolytic copper foil based on an electrolytic method.
  • the thickness of the negative electrode current collector is greater than 1 ⁇ m or greater than 5 ⁇ m. In some embodiments, the thickness of the negative electrode current collector is less than 100 ⁇ m or less than 50 ⁇ m. In some embodiments, the thickness of the negative electrode current collector is within the range formed by any two values above.
  • the negative electrode active material is not particularly limited as long as it can reversibly store and release lithium ions.
  • Examples of negative electrode active materials may include, but are not limited to, carbon materials such as natural graphite and artificial graphite; metals such as silicon (Si) and tin (Sn); or oxides of metal elements such as Si and Sn.
  • the negative electrode active materials can be used alone or in combination.
  • the negative active material layer may further include a negative binder.
  • the negative electrode binder can improve the combination of the negative electrode active material particles and the combination of the negative electrode active material and the current collector.
  • the type of negative electrode binder is not particularly limited, as long as it is a material stable to the electrolyte solution or the solvent used in electrode production.
  • the negative binder includes a resin binder.
  • resin binders include, but are not limited to, fluororesins, polyacrylonitrile (PAN), polyimide resins, acrylic resins, polyolefin resins, and the like.
  • the negative electrode binder When using a water-based solvent to prepare the negative electrode mixture slurry, the negative electrode binder includes, but is not limited to, carboxymethyl cellulose (CMC) or its salt, styrene-butadiene rubber (SBR), polyacrylic acid (PAA) or Its salt, polyvinyl alcohol, etc.
  • CMC carboxymethyl cellulose
  • SBR styrene-butadiene rubber
  • PAA polyacrylic acid
  • Its salt polyvinyl alcohol, etc.
  • the negative electrode can be prepared by the following method: coating the negative electrode mixture slurry comprising negative electrode active material, resin binder, etc. on the negative electrode current collector, after drying, calendering to form negative electrode active material layers on both sides of the negative electrode current collector, thus Negative pole is available.
  • a separator is usually provided between the positive electrode and the negative electrode.
  • the electrolytic solution of the present application is usually used by permeating the separator.
  • the material and shape of the separator are not particularly limited as long as the effect of the present application is not significantly impaired.
  • the separator can be resin, glass fiber, inorganic material, etc. formed of materials stable to the electrolyte solution of the present application.
  • the separator includes a porous sheet or a non-woven fabric-like substance with excellent liquid retention properties.
  • the material of the resin or fiberglass separator may include, but are not limited to, polyolefin, aramid, polytetrafluoroethylene, polyethersulfone, and the like.
  • the polyolefin is polyethylene or polypropylene.
  • the polyolefin is polypropylene.
  • the materials for the above separators may be used alone or in any combination.
  • the isolation film can also be a material formed by laminating the above materials, examples of which include, but not limited to, a three-layer isolation film formed by laminating polypropylene, polyethylene, and polypropylene in this order.
  • Examples of materials of inorganic substances may include, but are not limited to, oxides such as aluminum oxide and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, sulfates (eg, barium sulfate, calcium sulfate, etc.).
  • Inorganic forms may include, but are not limited to, granular or fibrous.
  • the form of the separator may be in the form of a film, examples of which include, but are not limited to, non-woven fabrics, woven fabrics, microporous films, and the like.
  • the pore diameter of the isolation membrane is 0.01 ⁇ m to 1 ⁇ m, and the thickness is 5 ⁇ m to 50 ⁇ m.
  • the following separator can also be used: a separator formed by forming a composite porous layer containing the above-mentioned inorganic particles on the surface of the positive electrode and/or negative electrode using a resin-based binder,
  • a separator is formed by using fluororesin as a binder to form porous layers on both sides of the positive electrode with 90% of the alumina particles having a particle size of less than 1 ⁇ m.
  • the thickness of the separator is arbitrary. In some embodiments, the thickness of the isolation film is greater than 1 ⁇ m, greater than 5 ⁇ m, or greater than 8 ⁇ m. In some embodiments, the thickness of the isolation film is less than 50 ⁇ m, less than 40 ⁇ m or less than 30 ⁇ m. In some embodiments, the thickness of the isolation film is within the range formed by any two values above. When the thickness of the separator is within the above range, insulation and mechanical strength can be ensured, and rate characteristics and energy density of the electrochemical device can be ensured.
  • the porosity of the separator is arbitrary.
  • the isolation membrane has a porosity greater than 10%, greater than 15%, or greater than 20%.
  • the separator has a porosity of less than 60%, less than 50%, or less than 45%.
  • the porosity of the isolation membrane is within the range formed by any two values above. When the porosity of the separator is within the above range, insulation and mechanical strength can be ensured, and membrane resistance can be suppressed, so that the electrochemical device has good safety characteristics.
  • the average pore diameter of the separator is also arbitrary. In some embodiments, the average pore size of the isolation membrane is less than 0.5 ⁇ m or less than 0.2 ⁇ m. In some embodiments, the average pore size of the isolation membrane is greater than 0.05 ⁇ m. In some embodiments, the average pore diameter of the isolation membrane is within the range formed by any two values above. When the average pore diameter of the separator exceeds the above-mentioned range, short circuits are likely to occur. When the average pore diameter of the isolation membrane is within the above range, the electrochemical device has good safety characteristics.
  • the electrochemical device assembly includes an electrode group, a current collecting structure, an outer casing and a protection element.
  • the electrode group may have either a laminated structure in which the positive electrode and the negative electrode are laminated with the separator interposed therebetween, or a structure in which the positive electrode and the negative electrode are wound in a spiral shape with the separator interposed therebetween.
  • the ratio of the mass of the electrode group to the internal volume of the battery is greater than 40% or greater than 50%.
  • the electrode set occupancy is less than 90% or less than 80%.
  • the occupancy of the electrode group is within the range formed by any two values above. When the electrode group occupancy ratio is within the above range, the capacity of the electrochemical device can be ensured, and at the same time, the decrease in characteristics such as repeated charge-discharge performance and high-temperature storage due to an increase in internal pressure can be suppressed.
  • the current collecting structure is not particularly limited. In some embodiments, the current collecting structure is a structure that reduces the resistance of the wiring portion and the bonding portion.
  • the electrode group has the above-mentioned laminated structure, it is suitable to use a structure in which the metal core portions of the electrode layers are bundled and welded to the terminal.
  • the internal resistance increases, so it is also suitable to provide two or more terminals in the electrode to reduce the resistance.
  • the electrode group has the above-mentioned winding structure, the internal resistance can be reduced by providing two or more lead wire structures on the positive electrode and the negative electrode respectively, and bundling them on the terminals.
  • the material of the outer case is not particularly limited, as long as it is stable to the electrolyte solution used.
  • metals such as nickel-plated steel sheets, stainless steel, aluminum or aluminum alloys, and magnesium alloys, or laminated films of resin and aluminum foil can be used, but not limited to.
  • the outer casing is aluminum or aluminum alloy metal or a laminated film.
  • Metal exterior cases include, but are not limited to, encapsulation and sealing structures formed by welding metals together by laser welding, resistance welding, or ultrasonic welding; or riveted structures using the above-mentioned metals through resin spacers.
  • the exterior case using the above-mentioned laminated film includes, but is not limited to, a package sealing structure formed by thermally bonding resin layers to each other, and the like. In order to improve the sealability, a resin different from the resin used in the laminated film may be interposed between the above-mentioned resin layers.
  • a resin having a polar group or a modified resin into which a polar group is introduced can be used as the interposed resin due to the bonding between the metal and the resin.
  • the shape of the exterior body is also arbitrary, and for example, any of cylindrical, square, laminated, button-shaped, large, and the like may be used.
  • Protection elements can use positive temperature coefficient (PTC) whose resistance increases when abnormal heat generation or excessive current flows, temperature fuses, thermistors, cut off by causing the internal pressure of the battery or the internal temperature to rise sharply at the time of abnormal heat generation A valve (current cut-off valve) for the current flowing in the circuit, etc.
  • PTC positive temperature coefficient
  • the above-mentioned protection element can be selected under the condition that it does not work in the normal use of high current, and it can also be designed in such a way that abnormal heat dissipation or thermal runaway will not occur even if there is no protection element.
  • the electrochemical device of the present application includes any device that undergoes an electrochemical reaction, and its specific examples include all kinds of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors.
  • the electrochemical device is a lithium secondary battery, including a lithium metal secondary battery or a lithium ion secondary battery.
  • the present application further provides an electronic device, which includes the electrochemical device according to the present application.
  • the application of the electrochemical device of the present application is not particularly limited, and it can be used in any electronic device known in the prior art.
  • the electrochemical device of the present application can be used in, but not limited to, notebook computers, pen-based computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, head-worn Stereo headphones, VCRs, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, motors, automobiles, motorcycles, power assist Bicycles, bicycles, lighting equipment, toys, game consoles, clocks, electric tools, flashlights, cameras, large household storage batteries and lithium-ion capacitors, etc.
  • the lithium ion battery is taken as an example below and the preparation of the lithium ion battery is described in conjunction with specific examples. Those skilled in the art will understand that the preparation method described in this application is only an example, and any other suitable preparation methods are described in this application. within range.
  • Lithium cobaltate (Hunan Shanshan LC9000E), Super-P and polyvinylidene fluoride were mixed with N-methylpyrrolidone according to the mass ratio of 95%:2%:3%, and stirred evenly to obtain the positive electrode active region slurry.
  • the inorganic filler and polyvinylidene fluoride are mixed with N-methylpyrrolidone according to the mass ratio of 90%:10% to obtain the insulating region slurry.
  • the positive electrode active region slurry and the insulating region slurry were coated on a 12 ⁇ m aluminum foil at the same time, dried, cold pressed, cut into pieces, and welded to tabs to obtain a positive electrode.
  • the surface of the positive electrode is shown in Figure 3.
  • the inorganic fillers used and their particle sizes are as follows: boehmite 1.2 ⁇ m, alumina 1.5 ⁇ m, silica 2 ⁇ m, titanium oxide 1.5 ⁇ m, magnesium oxide 2.5 ⁇ m, magnesium hydroxide 1.5 ⁇ m.
  • the electrolyte solution is poured from the liquid injection port, packaged, and then the lithium-ion battery is produced through processes such as formation and capacity.
  • the lithium-ion batteries were charged at a constant current of 0.5C to 4.7V, then charged at a constant voltage to a current of 0.05C, left to stand for 20 hours, and then discharged to 3.0V at a constant current of 0.5C. According to the above conditions, the lithium ion battery was charged/discharged several times, and the capacity retention rate after 400 cycles was calculated.
  • the capacity retention rate after cycling is calculated according to the following formula:
  • Capacity retention rate after cycle (discharge capacity after 400 cycles/discharge capacity at first cycle) ⁇ 100%.
  • Overcharge deformation rate [(T2-T1)/T1] ⁇ 100%.
  • the lithium-ion battery stand still for 30 minutes, then charge it to 4.7V with a constant current at a rate of 0.5C, then charge it at a constant voltage at 4.7V to 0.05C, let it stand for 60 minutes, and measure the thickness T3 of the lithium-ion battery .
  • the battery was then short-circuited at 100 m ⁇ for 10 seconds, and the thickness T4 of the Li-ion battery was measured.
  • Short-circuit deformation rate [(T4-T3)/T3] ⁇ 100%.
  • Table 1 shows the influence of the insulating region and the electrolyte on the intermittent cycle performance and safety performance of the lithium-ion battery under high temperature and high pressure.
  • the inorganic filler in the insulating region is boehmite, and the content of the compound with cyano group or the compound with sulfur-oxygen double bond in the electrolyte is adjusted in Examples 1-1 to 1-26 in Table 1.
  • the positive electrode in Comparative Example 1-1 has no insulating region.
  • Comparative Example 1-2 the positive electrode has no insulating region, and the electrolyte solution does not contain compounds with cyano groups and compounds with sulfur-oxygen double bonds.
  • the only difference between Example 1-2 to Example 1-26 and Example 1-1 is the parameters in Table 1.
  • the resistance of the interactive region is higher than that of the positive active material region, and there is a resistance difference between the interactive region and the positive active material region, so that charge carriers are accumulated on the side of the interactive region during charging and discharging, without utilizing the interactive region
  • the positive active material contained in it As a result, polarization occurs inside the positive electrode, and the interaction region becomes the starting point for the overall deterioration of the positive electrode.
  • Compounds with cyano groups or compounds with sulfur-oxygen double bonds can form a film on the surface of the positive electrode active material, so that the resistance difference between the surface of the positive electrode active material area and the interaction area becomes smaller, reducing polarization, thereby improving battery performance .
  • Selecting suitable compounds with cyano groups to use in combination such as selecting two different dinitrile compounds, dinitrile compounds and trinitrile compounds, will have a better film-forming effect on the surface of the positive electrode active material, and further improved effects can also be obtained.
  • Example 2 shows the influence of the insulating region and the electrolyte on the intermittent cycle performance and safety performance of the lithium-ion battery under high temperature and high pressure.
  • the inorganic filler in Example 1-1 is boehmite, and the electrolyte contains 4% SN; Examples 2-1 to 2-19 adjust the components of the inorganic filler and the composition of the electrolyte.
  • Examples 2-1 to 2-19 by changing the components of the inorganic filler, excellent intermittent cycle performance and safety performance under high temperature and high pressure are also obtained. Specifically, when inorganic fillers with weak alkalinity such as boehmite and magnesium hydroxide are selected, the influence on the resistance of the interaction region is smaller, and further improved effects can be obtained.
  • weak alkalinity such as boehmite and magnesium hydroxide
  • Table 3 shows the relationship between the content (a%) of the compound with cyano group and the content (b%) of the compound with sulfur-oxygen double bond to the intermittent cycle performance and safety performance of the lithium-ion battery under high temperature and high pressure Influence.
  • the inorganic filler in embodiment 1-1 is boehmite, and the electrolyte includes 4% SN; the inorganic filler in embodiment 3-1 to 3-14 is boehmite, and the compound with cyano group and the compound with sulfur-oxygen double bond are adjusted content.
  • the formed film has better stability and can further improve the intermittent cycle performance and safety under high temperature and high pressure.
  • the effect of performance, especially for the improvement of high-temperature short-circuit safety performance is particularly obvious. More specifically, by controlling the content of the compound with cyano group and the compound with sulfur-oxygen double bond in an appropriate range, especially satisfying the relationship: 0.1 ⁇ a+b ⁇ 15, 0.5 ⁇ a/b ⁇ 20, it can be more fully improved
  • the interfacial stability of the positive electrode active material region further improves the intermittent cycle performance and safety performance under high temperature and high pressure.
  • Table 4 shows the impact of the mass per unit area of the positive active material region (A 1 mg/1540.25mm 2 ) and the mass per unit area of the insulating region (A 2 mg/1540.25mm 2 ) on the intermittent cycle performance of lithium-ion batteries under high temperature and high pressure and safety performance.
  • the only difference between Examples 4-1 to 4-11 and Example 1-1 lies in the parameters listed in Table 4.
  • Table 5 shows the impact of the mass percentage (M 1 %) of the inorganic filler in the insulating region and the mass per unit area (A 2 mg/1540.25mm 2 ) of the insulating region on the intermittent cycle performance and safety performance of the lithium-ion battery under high temperature and high pressure Impact.
  • Examples 5-1 to 5-9 used the same inorganic filler and electrolyte as Example 1-1, the only difference being the parameters listed in Table 5.
  • Table 6 shows the influence of the mass per unit area of the positive electrode active material area (A 1 mg/1540.25mm 2 ) and the content of the compound with cyano group (a%) on the intermittent cycle and safety performance of the lithium-ion battery under high temperature and high pressure .
  • Table 7 shows the impact of positive electrode additive polyols on the intermittent cycle performance and safety performance of lithium-ion batteries under high temperature and high pressure.
  • references to “some embodiments”, “partial embodiments”, “one embodiment”, “another example”, “example”, “specific example” or “partial example” in the entire specification mean that At least one embodiment or example in this application includes a specific feature, structure, material or characteristic described in the embodiment or example.
  • descriptions that appear throughout the specification such as: “in some embodiments”, “in an embodiment”, “in one embodiment”, “in another example”, “in an example In”, “in a particular example” or “example”, they are not necessarily referring to the same embodiment or example in this application.
  • the particular features, structures, materials, or characteristics herein may be combined in any suitable manner in one or more embodiments or examples.

Abstract

本申请涉及电化学装置和包含其的电子装置。本申请的电化学装置包括：正极、负极和电解液，所述正极包括正极集流体和位于所述正极集流体上的正极活性物质区、绝缘区和交互区；所述交互区位于所述正极活性物质区和所述绝缘区之间，并且与所述正极活性物质区和所述绝缘区相接；所述正极活性物质区包括正极活性物质；所述绝缘区包括无机填料；所述交互区包括所述正极活性物质和所述无机填料；并且所述电解液包括具有氰基的化合物或具有硫氧双键的化合物中的至少一种。本申请提供的电化学装置具有改善的高温高压下的间歇循环性能和安全性能。

Description

电化学装置和包含其的电子装置 技术领域
本申请涉及储能领域，具体涉及一种电化学装置和包含其的电子装置，特别是锂离子电池。
背景技术
锂离子电池由于具备能量密度大、输出功率高、循环寿命长和环境污染小等优点而被广泛应用于电动汽车以及消费类电子产品中。然而锂离子电池在受到挤压、碰撞或穿刺等异常情况时很容易发生着火、爆炸，从而引起严重危害。因此锂离子电池的安全问题很大程度地限制了锂离子电池的应用和普及。
当由于发生碰撞、挤压、穿刺等异常情况而导致电池发生内短路时，电池温度会上升。现有技术中有采用在金属集流体的材料中加入低熔点合金的技术方案，随着电池温度的上升，该集流体中的低熔点合金发生熔融，从而造成极片断路，由此切断电流，从而改善了电池的安全性；或采用具有树脂层两面复合有金属层的多层结构的集流体，随着电池温度的上升，当达到树脂层材料的熔点时，该集流体的树脂层熔融而使极片破损，由此切断电流，从而改善电池的安全问题。
然而现有技术中的这些方法都无法有效地阻止锂离子电池内短路的发生，而且也无法保证在异常情况发生后电池还可以继续工作。因此，有必要提供一种能在碰撞、挤压、穿刺等异常情况发生后，有效地防止电池由于内短路的发生而引起的着火、爆炸等事故且不影响电池正常工作的电池设计。
发明内容
本申请通过提供一种能够改善电化学装置在高温高压下的间歇循环性能，而且有效提高高电压下的安全性能的电化学装置和电子装置，以在某种程度上解决存在于现有技术的问题。
在一个实施例中，本申请提供了一种电化学装置，所述电化学装置包括：正极、负极和电解液，所述正极包括正极集流体和位于所述正极集流体上的正极活性物质区、绝 缘区和交互区；所述交互区位于所述正极活性物质区和所述绝缘区之间，并且与所述正极活性物质区和所述绝缘区相接；所述正极活性物质区包括正极活性物质；所述绝缘区包括无机填料；所述交互区包括所述正极活性物质和所述无机填料；并且所述电解液包括具有氰基的化合物或具有硫氧双键的化合物中的至少一种。
在一些实施例中，所述电解液包括具有氰基的化合物和具有硫氧双键的化合物，其中基于所述电解液的质量，所述具有氰基的化合物的质量百分比为a％，所述具有硫氧双键的化合物的质量百分比为b％，其中a和b满足：0.1≤a+b≤15；和0.5≤a/b≤20。
在一些实施例中，所述正极活性物质区的质量为A 1mg/1540.25mm 2，所述绝缘区的质量为A 2mg/1540.25mm 2，其中A 1和A 2满足：A 1/A 2>1.2。
在一些实施例中，所述正极活性物质区的质量为A 1mg/1540.25mm 2，所述A 1的取值范围为100至400。
在一些实施例中，基于所述绝缘区的质量，所述绝缘区中无机填料的质量百分比为M 1％，所述绝缘区的质量为A 2g/1540.25mm 2，其中M 1和A 2满足：0.3≤M 1/A 2≤1.5。
在一些实施例中，所述正极活性物质区的质量为A 1mg/1540.25mm 2，其中基于所述电解液的质量，所述具有氰基的化合物的质量百分比为a％，其中A 1和a满足：A 1/a>8。
在一些实施例中，所述无机填料包括二氧化硅、氧化铝、水合氧化铝、氧化钛、氧化镁、氢氧化镁、氧化铝掺杂二氧化硅或勃姆石中的至少一种。
在一些实施例中，所述具有氰基的化合物包括以下化合物中的至少一种：丁二腈、戊二腈、己二腈、1,5-二氰基戊烷、1,6-二氰基己烷、四甲基丁二腈、2-甲基戊二腈、2,4-二甲基戊二腈、2,2,4,4-四甲基戊二腈、1,4-二氰基戊烷、1,2-二氰基苯、1,3-二氰基苯、1,4-二氰基苯、乙二醇双(丙腈)醚、3,5-二氧杂-庚二腈、1,4-二(氰基乙氧基)丁烷、二乙二醇二(2-氰基乙基)醚、三乙二醇二(2-氰基乙基)醚、四乙二醇二(2-氰基乙基)醚、1,3-二(2-氰基乙氧基)丙烷、1,4-二(2-氰基乙氧基)丁烷、1,5-二(2-氰基乙氧基)戊烷、乙二醇二(4-氰基丁基)醚、1,4-二氰基-2-丁烯、1,4-二氰基-2-甲基-2-丁烯、1,4-二氰基-2-乙基-2-丁烯、1,4-二氰基-2,3-二甲基-2-丁烯、1,4-二氰基-2,3-二乙基-2-丁烯、1,6-二氰基-3-己烯、1,6-二氰基-2-甲基-3-己烯、1,3,5-戊三甲腈、1,2,3-丙三甲腈、1,3,6-己三甲腈、1,2,6-己三甲腈、1,2,3-三(2-氰基乙氧基)丙烷、1,2,4-三(2-氰基乙氧基)丁烷、1,1,1-三(氰基乙氧基亚甲基)乙烷、1,1,1-三(氰基乙氧基亚甲基)丙烷、3-甲基-1,3,5-三(氰基乙氧基)戊烷、1,2,7-三(氰基乙氧基)庚烷、1,2,6-三(氰基乙氧基)己烷或1,2,5-三(氰基乙氧基)戊烷；其 中基于所述电解液的质量，所述具有氰基的化合物的质量百分比为a％，a的取值范围为0.1至15。
在一些实施例中，所述具有氰基的化合物包括至少两种二腈化合物。
在一些实施例中，所述具有氰基的化合物包括二腈化合物和三腈化合物。
在一些实施例中，所述具有氰基的化合物包括具有醚键的二腈化合物或具有醚键的三腈化合物。
在一些实施例中，所述具有硫氧双键的化合物包括以下化合物中的至少一种：双环硫酸酯、双环磺内酯、硫酸乙烯酯、硫酸丙烯酯、1,3-丙磺酸内酯、1,3-丙烯磺酸内酯、甲烷二磺酸亚甲酯或甲烷二磺酸亚乙酯；其中基于所述电解液的质量，所述具有硫氧双键的化合物的质量百分比为b％，b的取值范围为0.001至8。
在一些实施例中，所述具有硫氧双键的化合物包括式1化合物：
Figure PCTCN2021122316-appb-000001
其中，
W选自
Figure PCTCN2021122316-appb-000002
L的每一实例独立地选自单键或亚甲基；m为1、2、3或4；
n为0、1或2；且p为0、1、2、3、4、5或6。
在一些实施例中，所述式1化合物包括以下化合物中的至少一种：
Figure PCTCN2021122316-appb-000003
在一些实施例中，所述式1化合物包括以下化合物中的至少一种：
Figure PCTCN2021122316-appb-000004
Figure PCTCN2021122316-appb-000005
在一些实施例中，所述双环磺内酯包括式2化合物：
Figure PCTCN2021122316-appb-000006
其中，A 1、A 2、A 3、A 4各自独立地选自取代或未取代的亚烷基，
其中A 1、A 2、A 3、A 4各自独立地经取代时，取代基选自卤素、烷基或卤素取代的烷基。
在一些实施例中，所述式2化合物包括以下化合物中的至少一种：
Figure PCTCN2021122316-appb-000007
在一些实施例中，所述正极活性物质区包含多元醇。
在一些实施例中，所述多元醇包括以下化合物中的至少一种：甲二醇、乙二醇、丙二醇、异戊二醇、1,3-丁二醇、1,4-丁二醇、二乙二醇、二丙二醇、聚乙二醇、聚丙二醇、甘油、二甘油或聚甘油。
在另一个实施例中，本申请提供一种电子装置，其包括根据本申请的实施例所述的电化学装置。
本申请提供的电化学装置具有改善的高温高压下的间歇循环性能和安全性能。
本申请实施例的额外层面及优点将部分地在后续说明中描述和显示，或是经由本申请实施例的实施而阐释。
附图说明
图1示出了本申请一个实施例中正极表面的图片。
图2示出了本申请一个对比例中正极表面的结构示意图。
图3示出了本申请一个实施例中正极表面的结构示意图。
图4示出了本申请一个实施例中正极表面的结构示意图。
具体实施方式
本申请的实施例将会被详细的描示在下文中。本申请的实施例不应该被解释为对本申请的限制。
另外，有时在本文中以范围格式呈现量、比率和其它数值。应理解，此类范围格式是用于便利及简洁起见，且应灵活地理解，不仅包含明确地指定为范围限制的数值，而且包含涵盖于所述范围内的所有个别数值或子范围，如同明确地指定每一数值及子范围一般。
在具体实施方式及权利要求书中，由术语“中的一者”、“中的一个”、“中的一种”或其他相似术语所连接的项目的列表可意味着所列项目中的任一者。例如，如果列出项目A及B，那么短语“A及B中的一者”意味着仅A或仅B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的一者”意味着仅A；仅B；或仅C。项目A可包含单个元件或多个元件。项目B可包含单个元件或多个元件。项目C可包含单个元件或多个元件。
在具体实施方式及权利要求书中，由术语“中的至少一者”、“中的至少一个”、“中的至少一种”或其他相似术语所连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短语“A及B中的至少一者”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。项目A可包含单个元件或多个元件。项目B可包含单个元件或多个元件。项目C可包含单个元件或多个元件。
一、电化学装置
在一些实施例中，本申请提供了一种电化学装置，所述电化学装置包括正极、负极和电解液。
I、正极
在一些实施例中，正极包括正极集流体和位于所述正极集流体的一个或两个表面上的正极活性物质区。
在一些实施例中，所述正极活性物质区包含正极活性物质。所述正极活性物质区可以是一层或多层，多层正极活性物质区中的每层可以包含相同或不同的正极活性物质。正极活性物质为任何能够可逆地嵌入和脱嵌锂离子等金属离子的物质。在一些实施例中，正极活性物质的放电容量小于正极活性物质的可充电容量，以防止在充电期间锂金属无意地析出在负极上。
在一些实施例中，正极集流体具有没有形成正极活性物质区的集流体露出部，正极集流体露出部以从卷绕电极体的卷绕轴方向(即与上述长度方向正交的片材宽度方向)的一端向外侧伸出的方式形成。正极集流体露出部与正极集流体接合。
在一些实施例中，所述正极具有形成于正极集流体上的绝缘区和形成于正极集流体上的交互区。在一些实施例中，所述绝缘区沿着所述正极活性物质区的正极集流体露出部侧的端部设置，绝缘区沿着正极的长度方向延伸。在一些实施例中，所述绝缘区在正极的宽度方向上位于所述正极活性物质区和所述正极集流体露出部之间。在一些实施例中，所述正极集流体露出部被绝缘区覆盖。
在一些实施例中，所述交互区位于所述绝缘区与所述正极活性物质区的边界部，所述交互区沿着正极的长度方向延伸。因此，所述交互区位于所述正极活性物质区与所述绝缘区之 间。另外，所述交互区与所述正极活性物质区和所述绝缘区相接。
图1示出了本申请一个实施例中正极表面的图片。由图1可以看出，交互区位于正极活性物质区与绝缘区之间，且沿着正极的长度方向延伸。
图2示出了本申请一个对比例中正极表面的结构示意图，其中200为正极表面，210为位于正极集流体上的正极活性物质区，且220为正极集流体的露出部。在该实施例中，正极集流体的露出部未被覆盖。
图3示出了本申请一个实施例中正极表面的结构示意图，其中300为正极表面，310为位于正极集流体上的正极活性物质区，320为位于正极集流体上的交互区，330为位于正极集流体上的绝缘区。在该实施例中，交互区位于正极活性物质区和绝缘区之间，并且与正极活性物质区和绝缘区相接，且集流体被完全覆盖。
图4示出了本申请一个实施例中正极表面的结构示意图，其中400为正极表面，410为位于正极集流体上的正极活性物质区，420为位于正极集流体上的交互区，430为位于正极集流体上的绝缘区，且440为正极集流体的露出部。在该实施例中，正极集流体的露出部未被完全覆盖。
在一些实施例中，所述正极活性物质区的质量为A 1mg/1540.25mm 2，所述绝缘区的质量为A 2mg/1540.25mm 2，其中A 1和A 2满足：A 1/A 2>1.2。
在一些实施例中，A 1/A 2≥2、A 1/A 2≥2.5、A 1/A 2≥3、A 1/A 2≥4或A 1/A 2≥5。
在一些实施例中，所述正极活性物质区的质量为A 1mg/1540.25mm 2，所述A 1的取值范围为100至400。在一些实施例中，A 1的取值为100、120、140、150、160、180、200、220、240、250、280、300、330、350、380、400或这些数值中任意两者组成的范围。
在一些实施例中，所述绝缘区的质量为A 2mg/1540.25mm 2，所述A 2的取值为60至250。在一些实施例中，所述A 2的取值为60、70、80、100、120、140、150、160、180、200、220、230、240、250或这些数值中任意两者组成的范围。
在一些实施例中，基于所述绝缘区的质量，所述绝缘区中无机填料的质量百分比为M 1％，所述绝缘区的质量为A 2g/1540.25mm 2，其中M 1和A 2满足：0.3≤M 1/A 2≤1.5。
在一些实施例中，0.6≤M 1/A 2≤1.5。在一些实施例中，M 1/A 2的值为0.3、0.5、0.6、0.7、0.9、1.2、1.4、1.5或这些数值中任意两者组成的范围。
在一些实施例中，M 1的取值范围为80-95。在一些实施例中，M 1的取值范围为85-95。 在一些实施例中，M 1的取值为80、82、85、88、90、92、95或这些数值中任意两者组成的范围。
在一些实施例中，所述绝缘区位于所述正极集流体的两面上，或者单面上。在一些实施例中，所述交互区位于所述正极集流体的两面上，或者单面上。
在一些实施例中，所述无机填料包括二氧化硅、氧化铝、水合氧化铝、氧化钛、氧化镁、氢氧化镁、氧化铝掺杂二氧化硅或勃姆石中的至少一种。
在一些实施例中，所述无机填料的形状可以为粒子状、纤维状、板状、薄片状等。在一些实施例中，所述无机填料的平均粒径为0.01μm以上且10μm以下，优选为0.1μm以上且5μm以下，更优选为0.5μm以上且3μm以下。在一些实施例中，所述无机填料的平均粒径(中值粒径D50)例如可通过激光衍射散射法等测量。
在一些实施例中，所述无机填料为具有绝缘性的无机颗粒。在一些实施例中，所述无机颗粒的例子包括，但不限于，无机氧化物(例如氧化铝、氧化镁、二氧化硅、氧化钛等)、氮化物(例如氮化铝、氮化硅等)、氧化铝水合物、氧化铝水合物以外的金属氢氧化物(例如氢氧化钾、氢氧化镁等)、粘土矿物(例如云母、滑石、沸石、磷灰石、高岭土等)、玻璃纤维等。它们可以单独使用，或者可以将两种以上组合使用。
在一些实施例中，所述绝缘区可以含有粘合剂。在一些实施例中，所述粘合剂包括，但不限于，丙烯酸系粘合剂、苯乙烯丁二烯橡胶(SBR)、聚烯烃系粘合剂等，也可使用聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)等氟系聚合物。
在一些实施例中，对所述绝缘区中粘合剂的含量没有特别限制。例如基于所述绝缘区的质量，所述粘合剂的含量为1％以上且30％以下，优选为3％以上且25％以下。在一些实施例中，所述粘合剂的含量为1％、5％、10％、15％、20％、25％、30％或这些数值中任意两者组成的范围。
在一些实施例中，所述交互区至少含有：所述正极活性物质区中含有的所述正极活性物质；和所述绝缘区含有的所述无机填料。
在一些实施例中，所述交互区为正极活性物质区的上述构成成分与绝缘区的上述构成成分相互混合而形成的层。因此，交互区可含有上述正极活性物质和上述无机填料以外的、正极活性物质区的构成成分和/或绝缘区的构成成分。例如，交互区进一步含有正极活性物质区和/或绝缘区中的粘合剂。
在一些实施例中，在所述正极活性物质区含有正极活性物质、导电材料和粘合剂，并且绝缘区含有无机填料和粘合剂的情况下，所述交互区含有正极活性物质、导电材料、正极活性物质区的粘合剂、无机填料、绝缘区的粘合剂。
在一些实施例中，所述交互区含有氧化铝水合物。在交互区含有氧化铝水合物的一个方式中，除了上述正极活性物质和上述无机填料外，交互区还含有氧化铝水合物。在交互区含有氧化铝水合物的另一方式中，交互区含有上述正极活性物质和上述无机填料外，该无机填料为氧化铝水合物。
在一些实施例中，所述氧化铝水合物含有羟基。在一些实施例中，氧化铝水合物包括，但不限于，作为结晶性氧化铝一水合物的羟基氧化铝(AlOOH)；作为结晶性氧化铝三水合物的氢氧化铝(Al(OH) 3)；和作为非晶性氧化铝水合物的氧化铝凝胶等。在一些实施例中，结晶性氧化铝水合物(即结晶性氧化铝一水合物和结晶性氧化铝三水合物)可以为α型和β型的任一者，优选为α型。在一些实施例中，氧化铝水合物优选为羟基氧化铝，例如勃姆石，可以进一步提高安全性能。
在一些实施例中，氧化铝水合物的平均粒径(中值粒径D50)没有特别限定。在氧化铝水合物的平均粒径过小时，在电解液中变得容易产生酸(特别是HF)，有可能导致正极活性物质的劣化。因此，氧化铝水合物的平均粒径优选为0.5μm以上。另一方面，在氧化铝水合物的平均粒径过大时，在电解液中酸(特别是HF)变得难以产生，影响间歇循环性能。因此，氧化铝水合物的平均粒径优选3μm以下。氧化铝水合物的平均粒径(中值粒径D50)例如可通过激光衍射散射法等测定。
在一些实施例中，所述交互区可通过如下方法形成：将形成正极活性物质区的糊膏和形成绝缘区的糊膏在正极集流体上以它们邻接的方式同时或依次涂布，将这些糊膏同时干燥。此时，在干燥前，形成正极活性物质区的糊膏和形成绝缘区的糊膏的在界面处发生混合，因此，在正极活性物质区和绝缘区的界面形成交互区。通过选择氧化铝水合物作为形成绝缘区糊膏中的无机填料，能够使交互区含有氧化铝水合物；或者，也可以使用形成正极活性物质区的糊膏、形成绝缘区的糊膏和形成交互区的含有氧化铝水合物的糊膏来形成正极活性物质区、绝缘区和交互区。
在一些实施例中，所述正极活性物质区进一步包括多元醇。在一些实施例中，所述多元醇包括以下化合物中的至少一种：甲二醇、乙二醇、丙二醇、异戊二醇、1,3-丁二醇、1,4-丁二醇、二乙二醇、二丙二醇、聚乙二醇、聚丙二醇、甘油、二甘油或聚甘油。
在一些实施例中，基于所述正极活性物质区的总重量，所述多元醇的含量为不大于0.3％。在一些实施例中，基于所述正极活性物质区的总重量，所述多元醇的含量为0.01％、0.05％、0.1％、0.12％、0.15％、0.18％、0.2％、0.25％、0.28％、0.3％或这些数值中任意两者组成的范围。
在一些实施例中，所述正极活性物质的种类没有特别限制，只要是能够以电化学方式吸藏和释放金属离子(例如，锂离子)即可。在一些实施例中，正极活性物质为含有锂和至少一种过渡金属的物质。正极活性物质的实例可包括，但不限于，锂过渡金属复合氧化物和含锂过渡金属磷酸化合物。
在一些实施例中，锂过渡金属复合氧化物中的过渡金属包括V、Ti、Cr、Mn、Fe、Co、Ni、Cu等。在一些实施例中，锂过渡金属复合氧化物包括LiCoO 2等锂钴复合氧化物、LiNiO 2等锂镍复合氧化物、LiMnO 2、LiMn 2O 4、Li 2MnO 4等锂锰复合氧化物、LiNi 1/3Mn 1/3Co 1/3O 2、LiNi 0.5Mn 0.3Co 0.2O 2等锂镍锰钴复合氧化物，其中作为这些锂过渡金属复合氧化物的主体的过渡金属原子的一部分被Na、K、B、F、Al、Ti、V、Cr、Mn、Fe、Co、Li、Ni、Cu、Zn、Mg、Ga、Zr、Si、Nb、Mo、Sn、W等其它元素所取代。锂过渡金属复合氧化物的实例可包括，但不限于，LiNi 0.5Mn 0.5O 2、LiNi 0.85Co 0.10Al 0.05O 2、LiNi 0.33Co 0.33Mn 0.33O 2、LiNi 0.45Co 0.10Al 0.45O 2、LiMn 1.8Al 0.2O 4和LiMn 1.5Ni 0.5O 4等。锂过渡金属复合氧化物的组合的实例包括，但不限于，LiCoO 2与LiMn 2O 4的组合，其中LiMn 2O 4中的一部分Mn可被过渡金属所取代(例如，LiNi 0.33Co 0.33Mn 0.33O 2)，LiCoO 2中的一部分Co可被过渡金属所取代。
在一些实施例中，含锂过渡金属磷酸化合物中的过渡金属包括V、Ti、Cr、Mn、Fe、Co、Ni、Cu等。在一些实施例中，含锂过渡金属磷酸化合物包括LiFePO 4、Li 3Fe 2(PO 4) 3、LiFeP 2O 7等磷酸铁类、LiCoPO 4等磷酸钴类，其中作为这些锂过渡金属磷酸化合物的主体的过渡金属原子的一部分被Al、Ti、V、Cr、Mn、Fe、Co、Li、Ni、Cu、Zn、Mg、Ga、Zr、Nb、Si等其它元素所取代。
在一些实施例中，正极活性物质中包含磷酸锂，其可提高电化学装置的连续充电特性。磷酸锂的使用没有限制。在一些实施例中，正极活性物质和磷酸锂混合使用。在一些实施例中，相对于上述正极活性物质与磷酸锂的重量，磷酸锂的含量为大于0.1％、大于0.3％或大于0.5％。在一些实施例中，相对于上述正极活性物质与磷酸锂的重量，磷酸锂的含量为小于10％、小于8％或小于5％。在一些实施例中，磷酸锂的含量在上述任意两个数值所组成的范围内。
在一些实施例中，在上述正极活性物质的表面可附着有与其组成不同的物质。表面附着物质的实例可包括，但不限于：氧化铝、二氧化硅、二氧化钛、氧化锆、氧化镁、氧化钙、氧化硼、氧化锑、氧化铋等氧化物；硫酸锂、硫酸钠、硫酸钾、硫酸镁、硫酸钙、硫酸铝等硫酸盐；碳酸锂、碳酸钙、碳酸镁等碳酸盐；碳等。
在一些实施例中，这些表面附着物质可以通过下述方法附着于正极活性物质表面：使表面附着物质溶解或悬浮于溶剂中而渗入添加到该正极活性物质中并进行干燥的方法；使表面附着物质前体溶解或悬浮于溶剂中，在渗入添加到该正极活性物质中后，利用加热等使其反应的方法；以及添加到正极活性物质前体中同时进行烧制的方法等等。在附着碳的情况下，还可以使用将碳材料(例如，活性炭等)进行机械附着的方法。
在一些实施例中，基于正极活性物质区的重量，表面附着物质的含量为大于0.1ppm、大于1ppm或大于10ppm。在一些实施例中，基于正极活性物质区的重量，表面附着物质的含量为小于10％、小于5％或小于2％。在一些实施例中，基于正极活性物质区的重量，表面附着物质的含量在上述任意两个数值所组成的范围内。
通过在正极活性物质表面附着物质，可以抑制正极活性物质表面的电解液的氧化反应，可以提高电化学装置的寿命。当表面附着物质的量过少时，其效果无法充分表现；当表面附着物质的量过多时，会阻碍锂离子的出入，因而电阻有时会增加。
本申请中，将在正极活性物质的表面附着有与其组成不同的物质的正极活性物质也称为“正极活性物质”。
在一些实施例中，正极活性物质的形状包括，但不限于，块状、多面体状、球状、椭圆球状、板状、针状和柱状等。在一些实施例中，正极活性物质颗粒包括一次颗粒、二次颗粒或其组合。在一些实施例中，一次颗粒可以凝集而形成二次颗粒。
在一些实施例中，正极活性物质的振实密度为大于0.5g/cm 3、大于0.8g/cm 3或大于1.0g/cm 3。当正极活性物质的振实密度在上述范围内时，可以抑制正极活性物质区形成时所需要的分散介质量及导电材料和正极粘合剂的所需量，由此可以确保正极活性物质的填充率和电化学装置的容量。通过使用振实密度高的复合氧化物粉体，可以形成高密度的正极活性物质区。振实密度通常越大越优选，没有特别的上限。在一些实施例中，正极活性物质的振实密度为小于4.0g/cm 3、小于3.7g/cm 3或小于3.5g/cm 3。当正极活性物质的振实密度的具有如上所述的上限时，可以抑制负荷特性的降低。
正极活性物质的振实密度可通过以下方式计算：将5g至10g的正极活性物质粉体放入 10mL的玻璃制量筒中，进行200次冲程20mm的振动，得出粉体填充密度(振实密度)。
当正极活性物质颗粒为一次颗粒时，正极活性物质颗粒的中值粒径(D50)指的是正极活性物质颗粒一次粒径。当正极活性物质颗粒的一次颗粒凝集而形成二次颗粒时，正极活性物质颗粒的中值粒径(D50)指的是正极活性物质颗粒二次粒径。
在一些实施例中，正极活性物质颗粒的中值粒径(D50)为大于0.3μm、大于0.5μm、大于0.8μm或大于1.0μm。在一些实施例中，正极活性物质颗粒的中值粒径(D50)为小于30μm、小于27μm、小于25μm或小于22μm。在一些实施例中，正极活性物质颗粒的中值粒径(D50)在上述任意两个数值所组成的范围内。当正极活性物质颗粒的中值粒径(D50)在上述范围内时，可得到高振实密度的正极活性物质，可以抑制电化学装置性能的降低。另一方面，在电化学装置的正极的制备过程中(即，将正极活性物质、导电材料和粘合剂等用溶剂浆料化而以薄膜状涂布时)，可以防止条纹产生等问题。此处，通过将具有不同中值粒径的两种以上的正极活性物质进行混合，可以进一步提高正极制备时的填充性。
正极活性物质颗粒中值粒径(D50)可利用激光衍射/散射式粒度分布测定装置测定：在使用HORIBA社制造的LA-920作为粒度分布计的情况下，使用0.1％六偏磷酸钠水溶液作为测定时使用的分散介质，在5分钟的超声波分散后将测定折射率设定为1.24而进行测定。
II、电解液
本申请的电化学装置中使用的电解液包括电解质和溶解该电解质的溶剂。在一些实施例中，本申请的电化学装置中使用的电解液进一步包括添加剂。
在一些实施例中，所述电解液包括具有氰基的化合物或具有硫氧双键化合物中的至少一种。
在一些实施例中，所述具有氰基的化合物包括以下化合物中的至少一种：丁二腈、戊二腈、己二腈、1,5-二氰基戊烷、1,6-二氰基己烷、四甲基丁二腈、2-甲基戊二腈、2,4-二甲基戊二腈、2,2,4,4-四甲基戊二腈、1,4-二氰基戊烷、1,2-二氰基苯、1,3-二氰基苯、1,4-二氰基苯、乙二醇双(丙腈)醚、3,5-二氧杂-庚二腈、1,4-二(氰基乙氧基)丁烷、二乙二醇二(2-氰基乙基)醚、三乙二醇二(2-氰基乙基)醚、四乙二醇二(2-氰基乙基)醚、1,3-二(2-氰基乙氧基)丙烷、1,4-二(2-氰基乙氧基)丁烷、1,5-二(2-氰基乙氧基)戊烷、乙二醇二(4-氰基丁基)醚、1,4-二氰基-2-丁烯、1,4-二氰基-2-甲基-2-丁烯、1,4-二氰基-2-乙基-2-丁烯、1,4-二氰基-2,3-二甲基-2-丁烯、1,4-二氰基-2,3-二乙基-2-丁烯、1,6-二氰基-3-己烯、1,6-二氰基-2-甲基-3-己烯、1,3,5-戊三甲腈、1,2,3-丙三甲腈、1,3,6-己三甲腈、1,2,6-己三甲腈、1,2,3-三(2-氰基乙氧基)丙烷、1,2,4- 三(2-氰基乙氧基)丁烷、1,1,1-三(氰基乙氧基亚甲基)乙烷、1,1,1-三(氰基乙氧基亚甲基)丙烷、3-甲基-1,3,5-三(氰基乙氧基)戊烷、1,2,7-三(氰基乙氧基)庚烷、1,2,6-三(氰基乙氧基)己烷或1,2,5-三(氰基乙氧基)戊烷。
上述具有氰基的化合物可单独使用或任意组合使用。若电解液含两种或多种具有氰基的化合物时，具有氰基的化合物的含量是指两种或多种具有氰基的化合物的总含量。
在一些实施例中，基于所述电解液的质量，所述具有氰基的化合物的质量百分比为a％，a的取值范围为0.1至15。在一些实施例中，a的取值为0.1、0.4、0.8、1、1.6、2.0、3、4、5、6、7、8、9、10、11、12、13、14、15或这些数值中任意两者组成的范围。
在一些实施例中，所述具有氰基的化合物包括至少两种二腈化合物。在一些实施例中，所述具有氰基的化合物包括二腈化合物和三腈化合物。在一些实施例中，所述具有氰基的化合物包括具有醚键的二腈化合物或具有醚键的三腈化合物。
在一些实施例中，A 1和a满足：A 1/a>8。在一些实施例中，A 1和a满足：A 1/a≥10。在一些实施例中，A 1和a满足：A 1/a≥15。在一些实施例中，A 1和a满足：A 1/a≥20。在一些实施例中，A 1和a满足：A 1/a≥30。在一些实施例中，A 1和a满足：A 1/a≥40。在一些实施例中，A 1/a的取值为8、10、12、15、18、20、22、25、28、30、32、35、38、40、42、45或这些数值中任意两者组成的范围。
在一些实施例中，所述具有硫氧双键的化合物包括以下化合物中的至少一种：双环硫酸酯、双环磺内酯、硫酸乙烯酯、硫酸丙烯酯、1,3-丙磺酸内酯、1,3-丙烯磺酸内酯、甲烷二磺酸亚甲酯或甲烷二磺酸亚乙酯。
在一些实施例中，所述具有硫氧双键的化合物包括式1化合物：
Figure PCTCN2021122316-appb-000008
其中，
W选自
Figure PCTCN2021122316-appb-000009
L的每一实例独立地选自单键或亚甲基；m为1、2、3或4；
n为0、1或2；且p为0、1、2、3、4、5或6。
在一些实施例中，所述式1化合物包括以下化合物中的至少一种：
Figure PCTCN2021122316-appb-000010
在一些实施例中，所述式1化合物包括以下化合物中的至少一种：
Figure PCTCN2021122316-appb-000011
在一些实施例中，所述双环磺内酯包括式2化合物：
Figure PCTCN2021122316-appb-000012
其中，A 1、A 2、A 3、A 4各自独立地选自取代或未取代的亚烷基，
其中A 1、A 2、A 3、A 4各自独立地经取代时，取代基选自卤素、烷基或卤素取代的烷基。
在一些实施例中，所述式2化合物包括以下化合物中的至少一种：
Figure PCTCN2021122316-appb-000013
Figure PCTCN2021122316-appb-000014
在一些实施例中，基于所述电解液的质量，所述具有硫氧双键的化合物的质量百分比为b％，b的取值范围为0.001至8。在一些实施例中，b的取值为0.001、0.1、0.5、1、1.5、2、2.5、3、3.5、4、4.5、5、5.5、6、6.5、7、7.5、8或这些数值中任意两者组成的范围。
在一些实施例中，所述电解液包括具有氰基的化合物和具有硫氧双键的化合物，且满足关系：0.1≤a+b≤15；和0.5≤a/b≤20。在一些实施例中，0.1<a+b<15；和2<a/b<12。在一些实施例中，a+b的取值为0.1、0.5、1、2、3、4、5、6、7、8、9、10、11、12、13、14、15或这些数值中任意两者组成的范围。在一些实施例中，a/b的取值为0.5、1、2、3、4、5、6、7、8、9、10、11、12、13、14、15、16、17、18、19、20或这些数值中任意两者组成的范围。
在一些实施例中，所述电解液进一步包含现有技术中已知的任何可作为电解液的溶剂的非水溶剂。
在一些实施例中，所述非水溶剂包括，但不限于，以下中的一种或多种：环状碳酸酯、链状碳酸酯、环状羧酸酯、链状羧酸酯、环状醚、链状醚、含磷有机溶剂、含硫有机溶剂和芳香族含氟溶剂。
在一些实施例中，所述环状碳酸酯的实例可包括，但不限于，以下中的一种或多种：碳酸乙烯酯(EC)、碳酸丙烯酯(PC)和碳酸亚丁酯。在一些实施例中，所述环状碳酸酯具有3-6个碳原子。
在一些实施例中，所述链状碳酸酯的实例可包括，但不限于，以下中的一种或多种：碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯(DEC)、碳酸甲基正丙基酯、碳酸乙基正丙基酯、碳酸二正丙酯等链状碳酸酯等。被氟取代的链状碳酸酯的实例可包括，但不限于，以下中的一种或多种：双(氟甲基)碳酸酯、双(二氟甲基)碳酸酯、双(三氟甲基)碳酸酯、双(2-氟乙基)碳 酸酯、双(2,2-二氟乙基)碳酸酯、双(2,2,2-三氟乙基)碳酸酯、2-氟乙基甲基碳酸酯、2,2-二氟乙基甲基碳酸酯和2,2,2-三氟乙基甲基碳酸酯等。
在一些实施例中，所述环状羧酸酯的实例可包括，但不限于，以下中的一种或多种：γ-丁内酯和γ-戊内酯中的一种或多种。在一些实施例中，环状羧酸酯的部分氢原子可被氟取代。
在一些实施例中，所述链状羧酸酯的实例可包括，但不限于，以下中的一种或多种：乙酸甲酯、乙酸乙酯、乙酸丙酯、乙酸异丙酯、乙酸丁酯、乙酸仲丁酯、乙酸异丁酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸异丙酯、丁酸甲酯、丁酸乙酯、丁酸丙酯、异丁酸甲酯、异丁酸乙酯、戊酸甲酯、戊酸乙酯、特戊酸甲酯和特戊酸乙酯等。在一些实施例中，链状羧酸酯的部分氢原子可被氟取代。在一些实施例中，氟取代的链状羧酸酯的实例可包括，但不限于，三氟乙酸甲酯、三氟乙酸乙酯、三氟乙酸丙酯、三氟乙酸丁酯和三氟乙酸2,2,2-三氟乙酯等。
在一些实施例中，所述环状醚的实例可包括，但不限于，以下中的一种或多种：四氢呋喃、2-甲基四氢呋喃、1,3-二氧戊环、2-甲基1,3-二氧戊环、4-甲基1,3-二氧戊环、1,3-二氧六环、1,4-二氧六环和二甲氧基丙烷。
在一些实施例中，所述链状醚的实例可包括，但不限于，以下中的一种或多种：二甲氧基甲烷、1,1-二甲氧基乙烷、1,2-二甲氧基乙烷、二乙氧基甲烷、1,1-二乙氧基乙烷、1,2-二乙氧基乙烷、乙氧基甲氧基甲烷、1,1-乙氧基甲氧基乙烷和1,2-乙氧基甲氧基乙烷等。
在一些实施例中，所述含磷有机溶剂的实例可包括，但不限于，以下中的一种或多种：磷酸三甲酯、磷酸三乙酯、磷酸二甲基乙酯、磷酸甲基二乙酯、磷酸亚乙基甲酯、磷酸亚乙基乙酯、磷酸三苯酯、亚磷酸三甲酯、亚磷酸三乙酯、亚磷酸三苯酯、磷酸三(2,2,2-三氟乙基)酯和磷酸三(2,2,3,3,3-五氟丙基)酯等。
在一些实施例中，所述含硫有机溶剂的实例可包括，但不限于，以下中的一种或多种：环丁砜、2-甲基环丁砜、3-甲基环丁砜、二甲基砜、二乙基砜、乙基甲基砜、甲基丙基砜、二甲基亚砜、甲磺酸甲酯、甲磺酸乙酯、乙磺酸甲酯、乙磺酸乙酯、硫酸二甲酯、硫酸二乙酯和硫酸二丁酯。在一些实施例中，含硫有机溶剂的部分氢原子可被氟取代。
在一些实施例中，所述芳香族含氟溶剂包括，但不限于，以下中的一种或多种：氟苯、二氟苯、三氟苯、四氟苯、五氟苯、六氟苯和三氟甲基苯。
在一些实施例中，本申请的电解液中使用的溶剂包括环状碳酸酯、链状碳酸酯、环状羧酸酯、链状羧酸酯及其组合。在一些实施例中，本申请的电解液中使用的溶剂包含选自由下 列物质组成的群组的有机溶剂：碳酸乙烯酯、碳酸丙烯酯、碳酸二乙酯、丙酸乙酯、丙酸丙酯、乙酸正丙酯、乙酸乙酯及其组合。在一些实施例中，本申请的电解液中使用的溶剂包含：碳酸乙烯酯、碳酸丙烯酯、碳酸二乙酯、丙酸乙酯、丙酸丙酯、γ-丁内酯及其组合。
在一些实施例中，电解质没有特别限制，可以任意地使用作为电解质公知的物质。在锂二次电池的情况下，通常使用锂盐。电解质的实例可包括，但不限于，LiPF 6、LiBF 4、LiClO 4、LiAlF 4、LiSbF 6、LiWF 7等无机锂盐；LiWOF 5等钨酸锂类；HCO 2Li、CH 3CO 2Li、CH 2FCO 2Li、CHF 2CO 2Li、CF 3CO 2Li、CF 3CH 2CO 2Li、CF 3CF 2CO 2Li、CF 3CF 2CF 2CO 2Li、CF 3CF 2CF 2CF 2CO 2Li等羧酸锂盐类；FSO 3Li、CH 3SO 3Li、CH 2FSO 3Li、CHF 2SO 3Li、CF 3SO 3Li、CF 3CF 2SO 3Li、CF 3CF 2CF 2SO 3Li、CF 3CF 2CF 2CF 2SO 3Li等磺酸锂盐类；LiN(FCO) 2、LiN(FCO)(FSO 2)、LiN(FSO 2) 2、LiN(FSO 2)(CF 3SO 2)、LiN(CF 3SO 2) 2、LiN(C 2F 5SO 2) 2、环状1,2-全氟乙烷双磺酰亚胺锂、环状1,3-全氟丙烷双磺酰亚胺锂、LiN(CF 3SO 2)(C 4F 9SO 2)等酰亚胺锂盐类；LiC(FSO 2) 3、LiC(CF 3SO 2) 3、LiC(C 2F 5SO 2) 3等甲基化锂盐类；双(丙二酸根合)硼酸锂盐、二氟(丙二酸根合)硼酸锂盐等(丙二酸根合)硼酸锂盐类；三(丙二酸根合)磷酸锂、二氟双(丙二酸根合)磷酸锂、四氟(丙二酸根合)磷酸锂等(丙二酸根合)磷酸锂盐类；以及LiPF 4(CF 3) 2、LiPF 4(C 2F 5) 2、LiPF 4(CF 3SO 2) 2、LiPF 4(C 2F 5SO 2) 2、LiBF 3CF 3、LiBF 3C 2F 5、LiBF 3C 3F 7、LiBF 2(CF 3) 2、LiBF 2(C 2F 5) 2、LiBF 2(CF 3SO 2) 2、LiBF 2(C 2F 5SO 2) 2等含氟有机锂盐类；二氟草酸硼酸锂、双(草酸)硼酸锂等草酸硼酸锂盐类；四氟草酸根合磷酸锂、二氟双(草酸根合)磷酸锂、三(草酸根合)磷酸锂等草酸根合磷酸锂盐类等。
在一些实施例中，电解质选自LiPF 6、LiSbF 6、FSO 3Li、CF 3SO 3Li、LiN(FSO 2) 2、LiN(FSO 2)(CF 3SO 2)、LiN(CF 3SO 2) 2、LiN(C 2F 5SO 2) 2、环状1,2-全氟乙烷双磺酰亚胺锂、环状1,3-全氟丙烷双磺酰亚胺锂、LiC(FSO 2) 3、LiC(CF 3SO 2) 3、LiC(C 2F 5SO 2) 3、LiBF 3CF 3、LiBF 3C 2F 5、LiPF 3(CF 3) 3、LiPF 3(C 2F 5) 3、二氟草酸硼酸锂、双(草酸)硼酸锂或二氟双(草酸根合)磷酸锂，其有助于改善电化学装置的输出功率特性、高倍率充放电特性、高温保存特性和循环特性等。
电解质的含量没有特别限制，只要不损害本申请的效果即可。在一些实施例中，电解液中的锂的总摩尔浓度为大于0.3mol/L以上、大于0.4mol/L或大于0.5mol/L。在一些实施例中，电解液中的锂的总摩尔浓度为小于3mol/L、小于2.5mol/L或小于2.0mol/L以下。在一些实施例中，电解液中的锂的总摩尔浓度在上述任意两个数值所组成的范围内。当电解质浓度在上述范围内时，作为带电粒子的锂不会过少，并且可以使粘度处于适当的范围，因而容易确保良好的电导率。
当使用两种以上的电解质的情况下，电解质包括至少一种为选自由单氟磷酸盐、硼酸盐、 草酸盐和氟磺酸盐组成的组中的盐。在一些实施例中，电解质包括选自由单氟磷酸盐、草酸盐和氟磺酸盐组成的组中的盐。在一些实施例中，电解质包括锂盐。在一些实施例中，基于电解质的重量，选自由单氟磷酸盐、硼酸盐、草酸盐和氟磺酸盐组成的组中的盐的含量为大于0.01％或大于0.1％。在一些实施例中，基于电解质的重量，选自由单氟磷酸盐、硼酸盐、草酸盐和氟磺酸盐组成的组中的盐的含量为小于20％或小于10％。在一些实施例中，选自由单氟磷酸盐、硼酸盐、草酸盐和氟磺酸盐组成的组中的盐的含量在上述任意两个数值所组成的范围内。
在一些实施例中，电解质包含选自由单氟磷酸盐、硼酸盐、草酸盐和氟磺酸盐组成的组中的一种以上物质和除此以外的一种以上的盐。作为除此以外的盐，可以举出在上文中例示的锂盐，在一些实施例中为LiPF 6、LiN(FSO 2)(CF 3SO 2)、LiN(CF 3SO 2) 2、LiN(C 2F 5SO 2) 2、环状1,2-全氟乙烷双磺酰亚胺锂、环状1,3-全氟丙烷双磺酰亚胺锂、LiC(FSO 2) 3、LiC(CF 3SO 2) 3、LiC(C 2F 5SO 2) 3、LiBF 3CF 3、LiBF 3C 2F 5、LiPF 3(CF 3) 3、LiPF 3(C 2F 5) 3。在一些实施例中，除此以外的盐为LiPF 6。
在一些实施例中，基于电解质的重量，除此以外的盐的含量为大于0.01％或大于0.1％。在一些实施例中，基于电解质的重量，除此以外的盐的含量为小于20％、小于15％或小于10％。在一些实施例中，除此以外的盐的含量在上述任意两个数值所组成的范围内。具有上述含量的除此以外的盐有助于平衡电解液的电导率和粘度。
III、负极
负极包括负极集流体和设置在所述负极集流体的一个或两个表面上的负极活性物质区，负极活性物质层包含负极活性物质。负极活性物质层可以是一层或多层，多层负极活性物质中的每层可以包含相同或不同的负极活性物质。负极活性物质为任何能够可逆地嵌入和脱嵌锂离子等金属离子的物质。在一些实施例中，负极活性物质的可充电容量大于正极活性物质的放电容量，以防止在充电期间锂金属无意地析出在负极上。
作为保持负极活性物质的集流体，可以任意使用公知的集流体。负极集流体的实例包括，但不限于，铝、铜、镍、不锈钢、镀镍钢等金属材料。在一些实施例中，负极集流体为铜。
在负极集流体为金属材料的情况下，负极集流体形式可包括，但不限于，金属箔、金属圆柱、金属带卷、金属板、金属薄膜、金属板网、冲压金属、发泡金属等。在一些实施例中，负极集流体为金属薄膜。在一些实施例中，负极集流体为铜箔。在一些实施例中，负极集流体为基于压延法的压延铜箔或基于电解法的电解铜箔。
在一些实施例中，负极集流体的厚度为大于1μm或大于5μm。在一些实施例中，负极集流体的厚度为小于100μm或小于50μm。在一些实施例中，负极集流体的厚度在上述任意两个数值所组成的范围内。
负极活性物质没有特别限制，只要能够可逆地吸藏、放出锂离子即可。负极活性物质的实例可包括，但不限于，天然石墨、人造石墨等碳材料；硅(Si)、锡(Sn)等金属；或Si、Sn等金属元素的氧化物等。负极活性物质可以单独使用或组合使用。
负极活性物质层还可包括负极粘合剂。负极粘合剂可提高负极活性物质颗粒彼此间的结合和负极活性物质与集流体的结合。负极粘合剂的种类没有特别限制，只要是对于电解液或电极制造时使用的溶剂稳定的材料即可。在一些实施例中，负极粘合剂包括树脂粘合剂。树脂粘合剂的实例包括，但不限于，氟树脂、聚丙烯腈(PAN)、聚酰亚胺树脂、丙烯酸系树脂、聚烯烃树脂等。当使用水系溶剂制备负极合剂浆料时，负极粘合剂包括，但不限于，羧甲基纤维素(CMC)或其盐、苯乙烯-丁二烯橡胶(SBR)、聚丙烯酸(PAA)或其盐、聚乙烯醇等。
负极可以通过以下方法制备：在负极集流体上涂布包含负极活性物质、树脂粘合剂等的负极合剂浆料，干燥后，进行压延而在负极集流体的两面形成负极活性物质层，由此可以得到负极。
IV、隔离膜
为了防止短路，在正极与负极之间通常设置有隔离膜。这种情况下，本申请的电解液通常渗入该隔离膜而使用。
对隔离膜的材料及形状没有特别限制，只要不显著损害本申请的效果即可。所述隔离膜可为由对本申请的电解液稳定的材料所形成的树脂、玻璃纤维、无机物等。在一些实施例中，所述隔离膜包括保液性优异的多孔性片或无纺布状形态的物质等。树脂或玻璃纤维隔离膜的材料的实例可包括，但不限于，聚烯烃、芳香族聚酰胺、聚四氟乙烯、聚醚砜等。在一些实施例中，所述聚烯烃为聚乙烯或聚丙烯。在一些实施例中，所述聚烯烃为聚丙烯。上述隔离膜的材料可以单独使用或任意组合使用。
所述隔离膜还可为上述材料层积而成的材料，其实例包括，但不限于，按照聚丙烯、聚乙烯、聚丙烯的顺序层积而成的三层隔离膜等。
无机物的材料的实例可包括，但不限于，氧化铝、二氧化硅等氧化物、氮化铝、氮化硅等氮化物、硫酸盐(例如，硫酸钡、硫酸钙等)。无机物的形式可包括，但不限于，颗粒状或纤维状。
所述隔离膜的形态可为薄膜形态，其实例包括，但不限于，无纺布、织布、微多孔性膜等。在薄膜形态中，所述隔离膜的孔径为0.01μm至1μm，厚度为5μm至50μm。除了上述独立的薄膜状隔离膜以外，还可以使用下述隔离膜：通过使用树脂类的粘合剂在正极和/或负极的表面形成含有上述无机物颗粒的复合多孔层而形成的隔离膜，例如，将氟树脂作为粘合剂使90％粒径小于1μm的氧化铝颗粒在正极的两面形成多孔层而形成的隔离膜。
所述隔离膜的厚度是任意的。在一些实施例中，所述隔离膜的厚度为大于1μm、大于5μm或大于8μm。在一些实施例中，所述隔离膜的厚度为小于50μm、小于40μm或小于30μm。在一些实施例中，所述隔离膜的厚度在上述任意两个数值所组成的范围内。当所述隔离膜的厚度在上述范围内时，则可以确保绝缘性和机械强度，并可以确保电化学装置的倍率特性和能量密度。
在使用多孔性片或无纺布等多孔质材料作为隔离膜时，隔离膜的孔隙率是任意的。在一些实施例中，所述隔离膜的孔隙率为大于10％、大于15％或大于20％。在一些实施例中，所述隔离膜的孔隙率为小于60％、小于50％或小于45％。在一些实施例中，所述隔离膜的孔隙率在上述任意两个数值所组成的范围内。当所述隔离膜的孔隙率在上述范围内时，可以确保绝缘性和机械强度，并可以抑制膜电阻，使电化学装置具有良好的安全特性。
所述隔离膜的平均孔径也是任意的。在一些实施例中，所述隔离膜的平均孔径为小于0.5μm或小于0.2μm。在一些实施例中，所述隔离膜的平均孔径为大于0.05μm。在一些实施例中，所述隔离膜的平均孔径在上述任意两个数值所组成的范围内。若所述隔离膜的平均孔径超过上述范围，则容易发生短路。当隔离膜的平均孔径在上述范围内时，使电化学装置具有良好的安全特性。
V、电化学装置组件
电化学装置组件包括电极组、集电结构、外装壳体和保护元件。
电极组
电极组可以是由上述正极和负极隔着上述隔离膜层积而成的层积结构、以及上述正极和负极隔着上述隔离膜以漩涡状卷绕而成的结构中的任一种。在一些实施例中，电极组的质量在电池内容积中所占的比例(电极组占有率)为大于40％或大于50％。在一些实施例中，电极组占有率为小于90％或小于80％。在一些实施例中，电极组占有率在上述任意两个数值所组成的范围内。当电极组占有率在上述范围内时，可以确保电化学装置的容量，同时可以抑制与内部压力上升相伴的反复充放电性能及高温保存等特性的降低。
集电结构
集电结构没有特别限制。在一些实施例中，集电结构为降低配线部分及接合部分的电阻的结构。当电极组为上述层积结构时，适合使用将各电极层的金属芯部分捆成束而焊接至端子上所形成的结构。一片的电极面积增大时，内部电阻增大，因而在电极内设置2个以上的端子而降低电阻也是适合使用的。当电极组为上述卷绕结构时，通过在正极和负极分别设置2个以上的引线结构，并在端子上捆成束，从而可以降低内部电阻。
外装壳体
外装壳体的材质没有特别限制，只要是对于所使用的电解液稳定的物质即可。外装壳体可使用，但不限于，镀镍钢板、不锈钢、铝或铝合金、镁合金等金属类、或者树脂与铝箔的层积膜。在一些实施例中，外装壳体为铝或铝合金的金属或层积膜。
金属类的外装壳体包括，但不限于，通过激光焊接、电阻焊接、超声波焊接将金属彼此熔敷而形成的封装密闭结构；或者隔着树脂制垫片使用上述金属类形成的铆接结构。使用上述层积膜的外装壳体包括，但不限于，通过将树脂层彼此热粘而形成的封装密闭结构等。为了提高密封性，还可以在上述树脂层之间夹入与层积膜中所用的树脂不同的树脂。在通过集电端子将树脂层热粘而形成密闭结构时，由于金属与树脂的接合，可使用具有极性基团的树脂或导入了极性基团的改性树脂作为夹入的树脂。另外，外装体的形状也是任意的，例如可以为圆筒形、方形、层积型、纽扣型、大型等中的任一种。
保护元件
保护元件可以使用在异常放热或过大电流流过时电阻增大的正温度系数(PTC)、温度熔断器、热敏电阻、在异常放热时通过使电池内部压力或内部温度急剧上升而切断在电路中流过的电流的阀(电流切断阀)等。上述保护元件可选择在高电流的常规使用中不工作的条件的元件，亦可设计成即使不存在保护元件也不至于发生异常放热或热失控的形式。
VI、应用
本申请的电化学装置包括发生电化学反应的任何装置，它的具体实例包括所有种类的一次电池、二次电池、燃料电池、太阳能电池或电容器。特别地，该电化学装置是锂二次电池，包括锂金属二次电池或锂离子二次电池。
本申请另提供了一种电子装置，其包括根据本申请所述的电化学装置。
本申请的电化学装置的用途没有特别限定，其可用于现有技术中已知的任何电子装置。 在一些实施例中，本申请的电化学装置可用于，但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
下面以锂离子电池为例并且结合具体的实施例说明锂离子电池的制备，本领域的技术人员将理解，本申请中描述的制备方法仅是实例，其他任何合适的制备方法均在本申请的范围内。
实施例
一、锂离子电池的制备
1、负极的制备
将人造石墨、丁苯橡胶和羧甲基纤维素钠按照96％:2％:2％的质量比例与去离子水混合，搅拌均匀，得到浆料。将浆料涂布在9μm的铜箔上。干燥，冷压，再经过裁片、焊接极耳，得到负极。
2、正极的制备
将钴酸锂(湖南杉杉LC9000E)、Super-P和聚偏氟乙烯按照95％:2％:3％的质量比例与N-甲基吡咯烷酮混合，搅拌均匀，得到正极活性区浆料。将无机填料和聚偏氟乙烯按照90％:10％的质量比例与N-甲基吡咯烷酮混合，得到绝缘区浆料。将该正极活性区浆料和绝缘区浆料同时涂布在12μm的铝箔上，干燥，冷压，再经过裁片、焊接极耳，得到正极，其中正极表面如图3所示。所用无机填料及其粒径如下所示：勃姆石1.2μm，氧化铝1.5μm，二氧化硅2μm，氧化钛1.5μm，氧化镁2.5μm，氢氧化镁1.5μm。
3、电解液的制备
在干燥氩气环境下，将EC、PC和DEC(重量比1：1：1)混合，加入LiPF 6混合均匀，形成基础电解液，其中LiPF 6的含量为12％。在基础电解液中加入不同含量添加剂得到不同实施例和对比例的电解液。其中电解液中各添加剂的含量为基于电解液的质量进行计算。
电解液中组分的缩写及其名称如下表所示：
材料名称 缩写 材料名称 缩写
碳酸乙烯酯 EC 碳酸丙烯酯 PC
碳酸二乙酯 DEC 己二腈 ADN
丁二腈 SN 乙二醇双(丙腈)醚 EDN
1,3,6-己烷三腈 HTCN 1,2,3-三(2-氰基乙氧基)丙烷 TCEP
1,3-丙磺酸内酯 PS 1,2-乙二醇硫酸酯 DTD
式1-1化合物 式1-1 式1-2化合物 式1-2
式2-1化合物 式2-1 式2-2化合物 式2-2
氟代碳酸乙烯酯 FEC 丙酸丙酯 PP
4、隔离膜的制备
以8μm聚乙烯多孔膜作为隔离膜。
5、锂离子电池的制备
将得到的正极、隔离膜和负极按次序卷绕，置于外包装箔中，留下注液口。从注液口灌注电解液，封装，再经过化成、容量等工序制得锂离子电池。
二、测试方法
1、锂离子高温高压下间歇循环性能的测试方法
在50℃下，将锂离子电池分别在0.5C恒流充电至4.7V，然后恒压充电截至电流为0.05C，静置20小时，然后0.5C恒流放电至3.0V。按照上述条件使锂离子电池进行多次充电/放电，计算400次后的容量保持率。循环后的容量保持率按照下式进行计算：
循环后的容量保持率＝(400次循环后的放电容量/首次循环的放电容量)×100％。
2、锂离子电池过充变形率的测试方法
在25℃下，将锂离子电池静置30分钟，然后以0.5C倍率恒流充电至4.7V，再在4.7V下恒压充电至0.05C，静置60分钟，测量锂离子电池的厚度T1。然后以0.1C倍率恒流充电60分钟，静置30分钟，重复这一步骤5次，使锂离子电池达到150％荷电状态(SOC)，测量锂离子电池的厚度T2。
过充变形率＝[(T2-T1)/T1]×100％。
3、锂离子电池高温短路变形率的测试方法
在25℃下，将锂离子电池静置30分钟，然后以0.5C倍率恒流充电至4.7V，再在4.7V下恒压充电至0.05C，静置60分钟，测量锂离子电池的厚度T3。然后以100mΩ使电池短路10秒钟，然后测量锂离子电池的厚度T4。
短路变形率＝[(T4-T3)/T3]×100％。
三、测试结果
A、表1展示了绝缘区以及电解液对锂离子电池高温高压下的间歇循环性能和安全性能的影响。其中绝缘区中无机填料为勃姆石，表1中实施例1-1至1-26调整电解液中具有氰基的化合物或具有硫氧双键的化合物的含量。对比例1-1中正极没有绝缘区。对比例1-2中正极没有绝缘区，电解液也不含具有氰基的化合物和具有硫氧双键的化合物。实施例1-2至实施例1-26与实施例1-1的区别仅为表1中的参数。
表1
Figure PCTCN2021122316-appb-000015
“—”表示不存在该物质。
如实施例1-1至1-26的测试结果所示，当正极上设置绝缘区和正极活性物质区，绝缘区 中具有无机填料，且电解液含有具有氰基的化合物和/或具有硫氧双键化合物时，锂离子电池的高温高压下的间歇循环性能和安全性能得到显著改善。而对比例1-1和1-2所示，正极中没有绝缘区，或是既没有绝缘区且电解液中也不含具有氰基的化合物和具有硫氧双键的化合物，则无法实现改善高温高压下间歇循环性能和安全性能的效果。
这可能是由于交互区的电阻比正极活性物质区的电阻高，在交互区与正极活性物质区之间存在电阻差，因此在充放电时，电荷载体在交互区侧蓄积，而没有利用交互区中包含的正极活性物质。其结果是正极内部产生极化，交互区成为正极整体劣化的起点。具有氰基的化合物或具有硫氧双键化合物能够在正极活性物质的表面形成被膜，使得正极活性物质区的表层整体与交互区的电阻差变小，减小极化，从而使得电池性能得到提升。选择合适的具有氰基的化合物组合使用，例如选择两种不同的二腈化合物、二腈化合物和三腈化合物，在正极活性物质的表面成膜效果更好，也能够获得进一步改善的效果。
B、表2展示了绝缘区以及电解液对锂离子电池高温高压下的间歇循环性能和安全性能的影响。其中实施例1-1的无机填料为勃姆石，电解液包括4％的SN；实施例2-1至2-19调整无机填料的组分和电解液组成。
表2
Figure PCTCN2021122316-appb-000016
Figure PCTCN2021122316-appb-000017
“—”表示不存在该物质。
如实施例2-1至2-19所示，通过改变无机填料的组分，也获得了优异的高温高压下间歇循环性能和安全性能。具体来说，无机填料选择勃姆石、氢氧化镁等具有弱碱性的无机物时，对于交互区电阻的影响更小，能够获得进一步改善的效果。
C、表3展示了具有氰基的化合物的含量(a％)和具有硫氧双键化合物的含量(b％)之间的关系对锂离子电池的高温高压下的间歇循环性能和安全性能的影响。其中实施例1-1无机填料为勃姆石，电解液包括4％的SN；实施例3-1至3-14无机填料为勃姆石，调整具有氰基的化合物和具有硫氧双键化合物的含量。
表3
Figure PCTCN2021122316-appb-000018
“—”表示不存在该物质。
由以上测试结果可以看出，当把具有氰基的化合物和具有硫氧双键的化合物组合使用时，所形成的被膜稳定性更好，也能够获得进一步改善高温高压下的间歇循环性能和安全性能的效果，尤其对于高温短路安全性能的改善尤其明显。更具体地，通过控制具有氰基的化合物和具有硫氧双键化合物的含量在合适的范围内，尤其满足关系：0.1≤a+b≤15，0.5≤a/b≤20，可以更充分改善正极活性物质区的界面稳定性，从而进一步改善高温高压下的间歇循环性能和安全性能。
D、表4展示了正极活性物质区单位面积质量(A 1mg/1540.25mm 2)和绝缘区的单位面积质量(A 2mg/1540.25mm 2)对锂离子电池的高温高压下的间歇循环性能和安全性能的影响。实施例4-1至4-11与实施例1-1的区别仅在于表4所列参数。
表4
Figure PCTCN2021122316-appb-000019
由以上测试结果可以看出，通过调控正极活性物质区单位面积质量和绝缘区的单位面积质量满足A 1/A 2>1.2时，能够获得进一步改善高温高压下的间歇循环性能和安全性能的效果，尤其对于高温短路安全性能的改善尤其明显。特别地，当满足A 1/A 2≥2时，进一步提高了锂离子电池的性能。
E、表5展示了绝缘区中无机填料的质量百分比(M 1％)和绝缘区的单位面积质量(A 2mg/1540.25mm 2)对锂离子电池的高温高压下的间歇循环性能和安全性能的影响。实施例5-1至5-9与实施例1-1中使用的无机填料和电解液相同，区别仅在于表5所列参数。
表5
Figure PCTCN2021122316-appb-000020
由以上测试结果可以看出，通过调整正极活性物质区单位面积质量和绝缘区的单位面积质量满足0.3≤M 1/A 2≤1.5时，能够获得进一步改善高温高压下的间歇循环性能和安全性能的效果，尤其对于高温短路安全性能的改善尤其明显。
F、表6展示了正极活性物质区单位面积质量(A 1mg/1540.25mm 2)和具有氰基的化合物的含量(a％)对锂离子电池的高温高压下的间歇循环和安全性能的影响。实施例6-1至6-7与实施例1-1的区别仅在于表6所列参数。
表6
Figure PCTCN2021122316-appb-000021
由以上测试结果可以看出，通过调整正极活性物质区单位面积质量和具有氰基的化合物的含量满足A 1/a>8时，能够获得进一步改善高温高压下的间歇循环和安全性能的效果，尤其对于高温短路安全性能的改善尤其明显。
G、表7展示了正极助剂多元醇对锂离子电池的高温高压下的间歇循环性能和安全性能的影响。实施例7-1至7-13与实施例1-1的区别仅在于表7所列参数。实施例7-1至7-13中正极的制备方法：将钴酸锂(湖南杉杉LC9000E)、Super-P和聚偏氟乙烯按照95％:2％:3％的质量比例与N-甲基吡咯烷酮混合，再在浆料中加入表7中的助剂，搅拌均匀，得到正极活性区浆料。将该正极活性区浆料和绝缘区浆料同时涂布在12μm的铝箔上，干燥，冷压，再经过裁片、焊接极耳，得到正极。
表7
Figure PCTCN2021122316-appb-000022
Figure PCTCN2021122316-appb-000023
“—”表示不存在该物质。
由以上测试结果可以看，当在正极浆料中添加0.1％至0.5％多元醇时，也获得了优异的高压高温下的间歇循环性能和安全性能。可能是因为多元醇对涂布浆料的的分散发挥特殊作用，大大减小极化，从而抑制电池中热引发的副反应，意想不到的是对短路变形率改善明显。
整个说明书中对“一些实施例”、“部分实施例”、“一个实施例”、“另一举例”、“举例”、“具体举例”或“部分举例”的引用，其所代表的意思是在本申请中的至少一个实施例或举例包含了该实施例或举例中所描述的特定特征、结构、材料或特性。因此，在整个说明书中的各处所出现的描述，例如：“在一些实施例中”、“在实施例中”、“在一个实施例中”、“在另一个举例中”，“在一个举例中”、“在特定举例中”或“举例“，其不必然是引用本申请中的相同的实施例或示例。此外，本文中的特定特征、结构、材料或特性可以以任何合适的方式在一个或多个实施例或举例中结合。
尽管已经演示和描述了说明性实施例，本领域技术人员应该理解上述实施例不能被解释为对本申请的限制，并且可以在不脱离本申请的精神、原理及范围的情况下对实施例进行改变，替代和修改。

Claims (20)

  1. 一种电化学装置，其包括：正极、负极和电解液，
    所述正极包括正极集流体和位于所述正极集流体上的正极活性物质区、绝缘区和交互区；
    所述交互区位于所述正极活性物质区和所述绝缘区之间，并且与所述正极活性物质区和所述绝缘区相接；
    所述正极活性物质区包括正极活性物质；
    所述绝缘区包括无机填料；
    所述交互区包括所述正极活性物质和所述无机填料；并且
    所述电解液包括具有氰基的化合物或具有硫氧双键的化合物中的至少一种。
  2. 根据权利要求1所述的电化学装置，其中所述电解液包括具有氰基的化合物和具有硫氧双键的化合物，其中基于所述电解液的质量，所述具有氰基的化合物的质量百分比为a％，所述具有硫氧双键的化合物的质量百分比为b％，其中a和b满足：0.1≤a+b≤15；和0.5≤a/b≤20。
  3. 根据权利要求1所述的电化学装置，其中所述正极活性物质区的质量为A 1mg/1540.25mm 2，所述绝缘区的质量为A 2mg/1540.25mm 2，其中A 1和A 2满足：A 1/A 2>1.2。
  4. 根据权利要求1所述的电化学装置，其中所述正极活性物质区的质量为A 1mg/1540.25mm 2，所述A 1的取值范围为100至400。
  5. 根据权利要求1所述的电化学装置，其中基于所述绝缘区的质量，所述绝缘区中无机填料的质量百分比为M 1％，所述绝缘区的质量为A 2g/1540.25mm 2，其中M 1和A 2满足：0.3≤M 1/A 2≤1.5。
  6. 根据权利要求1所述的电化学装置，其中所述正极活性物质区的质量为A 1mg/1540.25mm 2，其中基于所述电解液的质量，所述具有氰基的化合物的质量百分比为a％，其中A 1和a满足：A 1/a>8。
  7. 根据权利要求1所述的电化学装置，其中所述无机填料包括二氧化硅、氧化铝、水合氧化铝、氧化钛、氧化镁、氢氧化镁、氧化铝掺杂二氧化硅或勃姆石中的至少一种。
  8. 根据权利要求1所述的电化学装置，其中所述具有氰基的化合物包括以下化合物中的至少一种：丁二腈、戊二腈、己二腈、1,5-二氰基戊烷、1,6-二氰基己烷、四甲基丁二腈、2-甲基戊二腈、2,4-二甲基戊二腈、2,2,4,4-四甲基戊二腈、1,4-二氰基戊烷、1,2-二氰基苯、1,3-二氰基苯、1,4-二氰基苯、乙二醇双(丙腈)醚、3,5-二氧杂-庚二腈、1,4-二(氰基乙氧基)丁烷、二乙二醇二(2-氰基乙基)醚、三乙二醇二(2-氰基乙基)醚、四乙二醇二(2-氰基乙基)醚、1,3-二(2-氰基乙氧基)丙烷、1,4-二(2-氰基乙氧基)丁烷、1,5-二(2-氰基乙氧基)戊烷、乙二醇二(4-氰基丁基)醚、1,4-二氰基-2-丁烯、1,4-二氰基-2-甲基-2-丁烯、1,4-二氰基-2-乙基-2-丁烯、1,4-二氰基-2,3-二甲基-2-丁烯、1,4-二氰基-2,3-二乙基-2-丁烯、1,6-二氰基-3-己烯、1,6-二氰基-2-甲基-3-己烯、1,3,5-戊三甲腈、1,2,3-丙三甲腈、1,3,6-己三甲腈、1,2,6-己三甲腈、1,2,3-三(2-氰基乙氧基)丙烷、1,2,4-三(2-氰基乙氧基)丁烷、1,1,1-三(氰基乙氧基亚甲基)乙烷、1,1,1-三(氰基乙氧基亚甲基)丙烷、3-甲基-1,3,5-三(氰基乙氧基)戊烷、1,2,7-三(氰基乙氧基)庚烷、1,2,6-三(氰基乙氧基)己烷或1,2,5-三(氰基乙氧基)戊烷；
    其中基于所述电解液的质量，所述具有氰基的化合物的质量百分比为a％，a的取值范围为0.1至15。
  9. 根据权利要求1所述的电化学装置，其中所述具有氰基的化合物包括至少两种二腈化合物。
  10. 根据权利要求1所述的电化学装置，其中所述具有氰基的化合物包括二腈化合物和三腈化合物。
  11. 根据权利要求1所述的电化学装置，其中所述具有氰基的化合物包括具有醚键的二腈化合物或具有醚键的三腈化合物。
  12. 根据权利要求1所述的电化学装置，其中所述具有硫氧双键的化合物包括以下化合物中的至少一种：双环硫酸酯、双环磺内酯、硫酸乙烯酯、硫酸丙烯酯、1,3-丙磺酸内酯、1,3-丙烯磺酸内酯、甲烷二磺酸亚甲酯或甲烷二磺酸亚乙酯；
    其中基于所述电解液的质量，所述具有硫氧双键的化合物的质量百分比为b％，b的取 值范围为0.001至8。
  13. 根据权利要求1所述的电化学装置，其中所述具有硫氧双键的化合物包括式1化合物：
    Figure PCTCN2021122316-appb-100001
    其中，
    W选自
    Figure PCTCN2021122316-appb-100002
    L的每一实例独立地选自单键或亚甲基；
    m为1、2、3或4；
    n为0、1或2；且
    p为0、1、2、3、4、5或6。
  14. 根据权利要求13所述的电化学装置，其中所述式1化合物包括以下化合物中的至少一种：
    Figure PCTCN2021122316-appb-100003
  15. 根据权利要求13所述的电化学装置，其中所述式1化合物包括以下化合物中的至少一种：
    Figure PCTCN2021122316-appb-100004
    Figure PCTCN2021122316-appb-100005
  16. 根据权利要求12所述的电化学装置，其中所述双环磺内酯包括式2化合物：
    Figure PCTCN2021122316-appb-100006
    其中，A 1、A 2、A 3、A 4各自独立地选自取代或未取代的亚烷基，
    其中A 1、A 2、A 3、A 4各自独立地经取代时，取代基选自卤素、烷基或卤素取代的烷基。
  17. 根据权利要求16所述的电化学装置，其中所述式2化合物包括以下化合物中的至少一种：
    Figure PCTCN2021122316-appb-100007
  18. 根据权利要求1所述的电化学装置，其中所述正极活性物质区包含多元醇。
  19. 根据权利要求18所述的电化学装置，其中所述多元醇包括以下化合物中的至少一种：甲二醇、乙二醇、丙二醇、异戊二醇、1,3-丁二醇、1,4-丁二醇、二乙二醇、二丙二醇、聚乙二醇、聚丙二醇、甘油、二甘油或聚甘油。
  20. 一种电子装置，其包括根据权利要求1-19中任一项所述的电化学装置。
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