WO2024000477A1 - 一种电化学装置及包含该电化学装置的电子装置 - Google Patents

一种电化学装置及包含该电化学装置的电子装置 Download PDF

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Publication number
WO2024000477A1
WO2024000477A1 PCT/CN2022/103000 CN2022103000W WO2024000477A1 WO 2024000477 A1 WO2024000477 A1 WO 2024000477A1 CN 2022103000 W CN2022103000 W CN 2022103000W WO 2024000477 A1 WO2024000477 A1 WO 2024000477A1
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electrochemical device
additive
positive electrode
active material
electrolyte
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PCT/CN2022/103000
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English (en)
French (fr)
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周娟
郎野
袁国霞
徐磊敏
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宁德新能源科技有限公司
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Priority to PCT/CN2022/103000 priority Critical patent/WO2024000477A1/zh
Priority to CN202280055331.8A priority patent/CN117941104A/zh
Publication of WO2024000477A1 publication Critical patent/WO2024000477A1/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
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/139—Processes of manufacture
    • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers

Definitions

  • the present application relates to the field of energy storage, and specifically to an electrochemical device and an electronic device including the electrochemical device.
  • electrochemical devices such as lithium-ion batteries
  • advantages such as light weight and high energy density.
  • cathode active materials such as lithium manganate are required to have higher charge and discharge capacity, and electrochemical devices are also required to have better cycle performance and storage performance.
  • the present application relates to an electrochemical device, which includes a positive electrode piece, a negative electrode piece and an electrolyte, the positive electrode piece includes a positive active layer, the positive active layer includes a positive active material, so
  • the positive active material includes additives to charge and discharge the electrochemical device, wherein when the electrochemical device is in a fully discharged state, the X-ray diffraction pattern of the positive electrode plate at a diffraction angle 2 ⁇ is 17.5° to There is a characteristic diffraction peak 1 in the range of 19.5°, where the additive contains manganese element.
  • the additive can supplement the lithium ions consumed by the positive electrode active material to form the CEI film during the first charge.
  • the additive can also provide diffusion channels for lithium ions to facilitate the intercalation and rapid deintercalation of lithium ions.
  • the additive has a lower voltage platform and can be used during cycling and During the storage process, it is conducive to the slow back-intercalation of lithium ions, thereby increasing the charge and discharge capacity of the cathode active material, and significantly improving the cycle performance and high-temperature storage performance of the electrochemical device.
  • the positive active material includes lithium manganate.
  • the X-ray diffraction pattern of the positive electrode plate when the electrochemical device is in a fully charged state, also has a characteristic diffraction peak 2 in the range of a diffraction angle 2 ⁇ of 17.5° to 19.5°.
  • the peak position difference between the characteristic diffraction peak 1 and the characteristic diffraction peak 2 satisfies 0.33° ⁇ 1 ⁇ 0.53°.
  • the positive active material includes lithium iron phosphate.
  • the X-ray diffraction pattern of the positive electrode plate has a characteristic diffraction peak 3 in the range of a diffraction angle 2 ⁇ of 19.8° to 21.8°.
  • the peak position difference between the characteristic diffraction peak 3 and the characteristic diffraction peak 1 satisfies 2° ⁇ 2 ⁇ 3°.
  • the mass percentage of the additive in the cathode active material is 3% to 20%. Limiting the content of the additive within the above range can improve the performance of the electrochemical device. First charge gram capacity and first coulomb efficiency.
  • the positive active layer includes element M, which includes Al, Nb, Mg, Ti, Ce, W, Ga, Zr, W, Y, V, Na, Sr, Mo, Cr, At least one of Sn or La, based on the mass of the cathode active layer, the mass percentage of the element M is 0.03% to 3.5%.
  • the element M can inhibit metal dissolution, stabilize the structure of the cathode active material, and improve the diffusion of lithium ions , improve the cycle performance and high-temperature storage performance of electrochemical devices.
  • the mass percentage of the element M is 0.3% to 1.5% based on the mass of the cathode active layer.
  • the electrolyte includes an electrolyte additive that includes at least one of a sulfur-oxygen double bond compound, vinylene carbonate, or fluoroethylene carbonate, based on the mass of the electrolyte.
  • the mass percentage of the electrolyte additive is 0.001% to 10%.
  • the electrolyte additive can stabilize the original morphology and structure of the positive electrode active material, and at the same time form a dense interface protective film on the surface of the positive electrode piece, improve the stability of the positive electrode material, reduce the positive electrode interface impedance, and further improve the cycle performance of the electrochemical device .
  • the mass percentage of the electrolyte additive is 0.01% to 5% based on the mass of the electrolyte.
  • the sulfur-oxygen double bond-containing compound includes at least one of 1,3-propane sultone (PS), 1,3-propene sultone (PES) or vinyl sulfate (DTD). A sort of.
  • the positive active material includes aluminum element. Based on the mass of the positive active material, the mass percentage of the aluminum element is C%, and the mass percentage of vinylene carbonate (VC) in the electrolyte is D %, C/D satisfies 0.03 ⁇ C/D ⁇ 0.5. Adding aluminum element will further stabilize the structure of the cathode active material, and VC can form a stable CEI film at the cathode interface. By controlling the mass percentage of aluminum element and VC to satisfy the above relationship, the structure of the cathode active material can be further stabilized and the electrochemical device can be improved. High temperature storage performance and cycle performance.
  • the additive particles have a layered structure, and their surfaces have steps with a width of 1 nm to 1000 nm.
  • the active ions consumed in the formation of CEI can be replenished when the electrochemical device is first charged, which is beneficial to improving the cycle and storage performance of the electrochemical device, and can also provide lithium
  • the ions provide diffusion channels and increase the charge and discharge capacity of the cathode active material, further improving the rate performance, high-temperature storage and cycle performance of the electrochemical device.
  • the additive has an average particle size of F, and F ranges from 5 ⁇ m to 40 ⁇ m.
  • F ranges from 5 ⁇ m to 40 ⁇ m.
  • the present application relates to an electronic device comprising an electrochemical device according to any of the preceding embodiments.
  • an additive containing manganese is added to the positive active material.
  • the X-ray diffraction pattern of the positive electrode plate has a diffraction angle 2 ⁇ in the range of 17.5° to 19.5°. Characteristic diffraction peak 1.
  • the added manganese-containing additive can supplement the lithium ions consumed by the positive electrode active material to form the CEI film during the first charge.
  • the additive can provide a diffusion channel for lithium ions to facilitate the insertion and rapid deintercalation of lithium ions, and the additive has The lower voltage platform is conducive to the slow back-intercalation of lithium ions during cycling and storage, thereby increasing the capacity of the cathode active material and significantly improving the cycling performance and high-temperature storage performance of the electrochemical device.
  • Figure 1 is an XRD pattern of the positive electrode piece of the electrochemical device of Example 1-1 in a fully discharged state.
  • Figure 2 is an XRD pattern of the positive electrode piece of the electrochemical device of Comparative Example 1-1 in a fully discharged state.
  • 3(a) and 3(b) are SEM images of the positive electrode active material of Example 1-1 in a fully discharged state.
  • a list of items connected by the term “one of,” “one of,” “one of,” or other similar terms may mean any of the listed items.
  • 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 component or multiple components.
  • Item B may contain a single component or multiple components.
  • Item C may contain a single component or multiple components.
  • a list of items connected by the term "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 component or multiple components.
  • Item B may contain a single component or multiple components.
  • Item C may contain a single component or multiple components.
  • the present application relates to an electrochemical device, which includes a positive electrode piece, a negative electrode piece and an electrolyte, the positive electrode piece includes a positive active layer, the positive active layer includes a positive active material, so
  • the positive active material includes additives to charge and discharge the electrochemical device, wherein when the electrochemical device is in a fully discharged state, the X-ray diffraction (XRD) pattern of the positive electrode piece at a diffraction angle 2 ⁇ is There is a characteristic diffraction peak 1 in the range of 17.5° to 19.5°, where the additive contains manganese element.
  • the characteristic diffraction peak 1 is the characteristic diffraction peak of the additive.
  • This additive can replenish the lithium ions consumed by the cathode active material to form the cathode-electrolyte interface (CEI) when charging for the first time, which is beneficial to improving the cycle performance and high-temperature storage performance of the electrochemical device. It can provide diffusion channels for lithium ions and facilitate lithium ions.
  • the additive includes a layered structure of a manganese-containing compound.
  • the manganese-containing compound includes at least one of LiMn 2 O 3 , Li 2 MnO 3 or LiMnO 2 .
  • the positive active material includes lithium manganate
  • the X-ray diffraction pattern of the positive electrode piece is in the range of 17.5° to 19.5° at a diffraction angle 20 It also has a characteristic diffraction peak 2, and the peak position difference between the characteristic diffraction peak 1 and the characteristic diffraction peak 2 satisfies 0.33° ⁇ 1 ⁇ 0.53°.
  • the positive active material includes lithium iron phosphate.
  • the electrochemical device When the electrochemical device is in a fully discharged state, it has a diffraction peak 3 at a diffraction angle 2 ⁇ of 19.8° to 21.8°.
  • the characteristic diffraction peak The peak position difference between 3 and the characteristic diffraction peak 1 satisfies 2° ⁇ 2 ⁇ 3°.
  • the mass percentage of the additive is 3% to 20% based on the mass of the cathode active material. In some embodiments, based on the mass of the cathode active material, the mass percentage of the additive is 3%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20 % or the range between any two values mentioned above.
  • the content of the additive is too small, the first charge gram capacity of the electrochemical device prepared therefrom is reduced.
  • the content of the additive is too high, the first Coulombic efficiency of the electrochemical device prepared therefrom is reduced. This is mainly because the additive has a relatively high The high first-charge gram capacity can compensate for the Li+ consumed by lithium manganate to form the CEI film during the first charge.
  • the mass percentage of the additive is 3% to 15% based on the mass of the cathode active material, at which time the electrochemical device has higher first charge gram capacity and Coulombic efficiency.
  • the single-sided coating weight of the cathode active layer is 100 mg to 500 mg/1540.25 mm 2 , wherein the mass of the cathode active layer and the mass percentage of the cathode active material are 94% to 98% .
  • the electrolyte includes an electrolyte additive that includes at least one of a sulfur-oxygen double bond compound, vinylene carbonate (VC), or fluoroethylene carbonate (FEC), based on
  • the mass of the electrolyte and the mass percentage of the electrolyte additive are 0.001% to 10%. In some embodiments, based on the mass of the electrolyte, the mass percentage of the additive is 0.001%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% Or the range between any two values mentioned above.
  • the sulfur-oxygen double bond-containing compound includes at least one of 1,3-propane sultone (PS), 1,3-propene sultone (PES) or vinyl sulfate (DTD).
  • PS 1,3-propane sultone
  • PES 1,3-propene sultone
  • DTD vinyl sulfate
  • PS 1,3-propane sultone
  • EES 1,3-propene sultone
  • DTD vinyl sulfate
  • VC and FEC can be used as CEI film-forming additives to form a more stable CEI film.
  • VC and FEC can also increase the flexibility of the CEI film and reduce the impedance of the cathode interface.
  • Compounds containing sulfur and oxygen double bonds can form a protective film at the positive and negative electrode interfaces, reduce side reactions between the positive and negative electrode interfaces and the electrolyte, and reduce the transmission impedance inside the battery, which is beneficial to improving the normal and high temperature cycle performance and high temperature storage of the battery. performance.
  • the above-mentioned electrolyte additives stabilize the original morphology and structure of the cathode active material, and at the same time form a dense interface film on the surface of the cathode plate, improve the stability of the cathode material, reduce side reactions, thereby reducing the impedance of the material and improving the battery cycle performance.
  • the mass percentage of the electrolyte additive is 0.01% to 5%.
  • the electrolyte additive can form a flexible protective film at the interface between the positive and negative electrodes, reduce the interface impedance, and effectively improve the normal/high temperature performance of the electrochemical device. Cycling performance and high temperature storage performance.
  • the positive active layer includes element M, wherein M includes Al, Nb, Mg, Ti, Ce, W, Ga, Zr, W, Y, V, Na, Sr, Mo, Cr, Sn or At least one of La.
  • the mass percentage of element M is 0.03% to 3.5% based on the mass of the cathode active layer.
  • the mass percentage of element M is 0.03%, 0.05%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4% , 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, 3.2%, 3.4%, 3.5% or the range between any two of the aforementioned values.
  • the element M can stabilize the structure of the cathode active material, reduce phase changes, inhibit the dissolution of transition metals, help the diffusion of lithium ions, and improve the cycle performance and high-temperature storage performance of the electrochemical device. When the element M content is too high, it will cause internal damage to the cathode active material.
  • the lattice expansion destroys the structural stability of the material and affects the cycle performance of the electrochemical device.
  • the mass percentage of element M is 0.03% to 1.5%. Within this content range, element M can effectively inhibit metal dissolution, improve the diffusion of lithium ions, and improve battery life. Cycling performance and high temperature storage performance of chemical devices.
  • the cathode active material includes aluminum element. Based on the mass of the cathode active layer, the mass percentage of aluminum element is C%, and the mass percentage of VC in the electrolyte is D%, satisfying 0.03 ⁇ C/D ⁇ 0.5. Adding aluminum element will further improve the structure of the cathode active material. VC can form a stable CEI film at the cathode interface. By controlling the mass percentage of aluminum element and VC to satisfy the above relationship, the structure of the cathode active material can be further stabilized and the performance of the electrochemical device can be improved. High temperature storage performance and cycle performance.
  • the average particle size of the additive is F, F ranges from 5 ⁇ m to 40 ⁇ m, and the surface of the additive particles has steps with a width of 1 nm to 1000 nm.
  • the larger particles are particles of the additive, which have a layered structure, with steps layer by layer on the surface, where the width of the steps ranges from 1 nm to 1000 nm.
  • the manganese-containing compound with a layered structure replenishes the lithium ions consumed to form CEI when the electrochemical device is first charged, which is beneficial to improving the cycle and storage performance of the electrochemical device.
  • it can provide diffusion channels for lithium ions and facilitate lithium ions.
  • the insertion and rapid de-intercalation of ions, and its low voltage platform (such as a 3.9V platform), is conducive to the slow back-intercalation of lithium ions during cycling and storage, thereby increasing the charge and discharge capacity of the cathode active material.
  • the present application relates to an electronic device comprising an electrochemical device according to any of the preceding embodiments.
  • the preparation method of the electrochemical device of the present application is described in detail below by taking a lithium-ion battery as an example.
  • Preparation of the negative electrode Disperse the negative active material, conductive agent, binder and thickener in the solvent system according to a certain mass ratio, stir thoroughly and mix evenly, then apply it on the negative electrode current collector, dry and cold press. Obtain the negative electrode piece.
  • the negative active material may be natural graphite, artificial graphite, mesophase microcarbon beads (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composite, SiO, Li-Sn alloy, Li-Sn-O alloy , Sn, SnO, SnO 2 , spinel structure lithium titanate Li 4 Ti 5 O 12 , one or more of Li-Al alloy and metallic lithium;
  • the conductive agent can be graphite, superconducting carbon, acetylene black , one or more of carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers;
  • the binder can be styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), One or more of polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), water-based acrylic resin (water-based acrylic resin) and carboxymethyl cellulose (CMC);
  • the thickener can be carboxylic acid Meth
  • the negative electrode current collector can be made of metal foil or porous metal plate, for example, foil or porous plate made of metal such as copper, nickel, titanium or iron or their alloys, such as copper foil.
  • the positive electrode active material lithium manganate (LiMn 2 O 4 ), lithium iron phosphate or other positive electrode active materials
  • the above-mentioned additives LiMn 2 O 4
  • the conductive agent LiMn 2 O 4
  • binder binder
  • the slurry is evenly coated on the positive electrode current collector aluminum foil and dried at 90°C to obtain the initial positive electrode piece.
  • the initial positive electrode piece is subjected to processes such as cold pressing and cutting to obtain the positive electrode piece.
  • the conductive agent improves the conductivity of the cathode active layer by providing a conductive path to the active material.
  • the conductive agent may include at least one of the following: acetylene black, Ketjen black, natural graphite, carbon black, carbon fiber, metal powder or metal fiber (such as copper, nickel, aluminum or silver), but the conductive agent Examples are not limited to this.
  • the amount of conductive agent can be appropriately adjusted. Based on 100 parts by weight of the total amount of the cathode active material, the conductive agent and the cathode binder, the amount of the conductive agent ranges from 1 to 30 parts by weight.
  • examples of the solvent include, but are not limited to, N-methylpyrrolidone, acetone, or water. In some embodiments, the amount of solvent can be adjusted appropriately.
  • the binder improves the binding properties of the positive active material particles to each other and to the current collector.
  • the positive electrode binder include, but are not limited to, the binder may be polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer One or more of EVA and polyvinyl alcohol (PVA).
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PVB polyvinyl butyral
  • EVA polyvinyl alcohol
  • the amount of the positive electrode binder ranges from 1 to 30 parts by weight based on 100 parts by weight of the total amount of the active material, the conductive agent and the positive electrode binder.
  • the current collector has a thickness in the range of 3 microns to 20 microns, although the disclosure is not limited thereto.
  • the current collector is electrically conductive and does not cause adverse chemical changes in the manufactured battery.
  • Examples of the current collector include copper, stainless steel, aluminum, nickel, titanium, or alloys (eg, copper-nickel alloys), but the disclosure is not limited thereto.
  • fine irregularities eg, surface roughness
  • the current collector can be used in various forms, and examples thereof include films, sheets, foils, meshes, porous structures, foams, or similar materials, but the disclosure is not limited thereto.
  • the embodiments of this application have no special restrictions on the isolation film.
  • the isolation film includes: a polyolefin microporous film, and a coating (coated on the surface of the polyethylene microporous film).
  • the isolation film is selected from Composed of one or more of polyethylene (PE), ethylene-propylene copolymer, polypropylene (PP), ethylene-butylene copolymer, ethylene-hexene copolymer, and ethylene-methyl methacrylate copolymer.
  • PE polyethylene
  • PP polypropylene
  • PP polypropylene
  • PP polypropylene
  • PP polypropylene
  • PP ethylene-butylene copolymer
  • ethylene-hexene copolymer ethylene-methyl methacrylate copolymer.
  • the coating includes inorganic ceramic particles, and the inorganic ceramic particles are selected from one or more of SiO 2 ,
  • the electrolyte solution includes a non-aqueous organic solvent and a lithium salt.
  • Non-aqueous organic solvents may include carbonates, carboxylates, ether compounds, sulfone compounds, or other aprotic solvents.
  • Examples of carbonate solvents include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dipropyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, Bis(2,2,2-trifluoroethyl) carbonate, etc.
  • ether compound solvent examples include glycol dimethyl ether, diglyme, tetraglyme, dibutyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, bis(2,2,2- Trifluoroethyl) ether, 1,3-dioxane, 1,4-dioxane, etc.
  • sulfone compound solvent examples include ethyl vinyl sulfone, methyl isopropyl sulfone, isopropyl sec-butyl sulfone, sulfolane, and the like.
  • the non-aqueous organic solvent in the electrolyte can be a single non-aqueous organic solvent or a mixture of multiple non-aqueous organic solvents.
  • a mixed solvent it can be determined according to the desired electrochemical device performance. Control the mixing ratio.
  • the lithium salt in the electrolyte includes or is selected from at least one of organic lithium salts or inorganic lithium salts, and the lithium salt includes or is selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium bisoxaloborate (LiB(C 2 O 4 ) 2 , LiBOB), lithium difluoroxalate borate (LiBF 2 (C 2 O 4 ), LiDFOB), lithium hexafluoroantimonate (LiSbF 6 ), Lithium hexafluoroarsenate (LiAsF 6 ), lithium perfluorobutane sulfonate (LiC 4 F 9 SO 3 ), lithium perchlorate (LiClO 4 ), lithium aluminate (LiAlO 2 ), lithium tetrachloroaluminate (LiAlCl 4 ), lithium disulfon
  • the bare battery core obtained by winding is placed in an outer package, electrolyte is injected and packaged, and a lithium-ion battery is obtained through processes such as formation, degassing, and trimming.
  • the present application provides an electronic device comprising the electrochemical device according to the foregoing content.
  • the electronic devices include, but are not limited to: notebook computers, pen-input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, head-mounted Stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power-assisted bicycles , bicycles, lighting equipment, toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries, etc.
  • the positive electrode piece Take a fully discharged lithium-ion battery, disassemble it to obtain the positive electrode piece, and perform an XRD test on the positive electrode piece.
  • the positive electrode piece is placed in the sample stage of the XRD testing instrument (model Bruker, D8), and scanned using a scanning rate of 2°/min. The angle range is 10° to 90°, and the XRD diffraction pattern is obtained. Read the corresponding diffraction peak and record its peak position and half-peak width.
  • Disassemble the lithium-ion battery to obtain the positive electrode piece Use a scanning electron microscope (JEOL company's JSM-6360LV model) to take SEM photos of the positive electrode piece obtained by disassembling the lithium-ion battery and observe the particle morphology of the positive electrode active material.
  • JEOL company's JSM-6360LV model to take SEM photos of the positive electrode piece obtained by disassembling the lithium-ion battery and observe the particle morphology of the positive electrode active material.
  • Disassemble the lithium-ion battery to obtain the positive electrode sheet use DMC to clean the positive electrode sheet obtained by disassembling the lithium-ion battery, scrape off the positive active layer of the cleaned positive electrode sheet with a scraper, and use a mixed solvent to dissolve the positive active layer (for example, For the 0.4g positive electrode active layer, use 10ml aqua regia (a mixed solvent of nitric acid and hydrochloric acid at a ratio of 1:1) and 2ml HF), adjust the volume to 100mL, and then use an ICP analyzer to test the Al, Nb, Mg, Ti, Ce, The mass percentage of W, Ga, Zr, W, Y, V, Na, Sr, Mo, Cr, Sn or La (based on the mass of the positive active layer).
  • a mixed solvent for example, 0.4g positive electrode active layer, use 10ml aqua regia (a mixed solvent of nitric acid and hydrochloric acid at a ratio of 1:1) and 2ml HF), adjust the volume to 100mL, and
  • 25°C cycle capacity retention rate (discharge capacity of the 1500th cycle/discharge capacity of the first cycle) ⁇ 100%.
  • 45°C cycle capacity retention rate (discharge capacity of the 400th cycle/discharge capacity of the first cycle) ⁇ 100%.
  • lithium-ion batteries prepared from the cathode materials shown in the Examples and Comparative Examples were taken from each group.
  • Voltage charging then perform constant current discharge at a current of 1C, discharge to 2.8V, record the discharge capacity, and record it as the capacity before storage; charge to 3.99V with a constant current of 0.5C, charge at a constant voltage until the current is lower than 0.05C
  • after storing the battery in a 60°C oven for 14D perform constant current discharge at a discharge current of 1C to 2.8V; then perform constant current and constant voltage charging at a charging current of 0.5C until the upper limit voltage is 4.2V , then perform constant current discharge at a discharge current of 1C, discharge to 2.8V, record the discharge capacity, and record it as the post-storage capacity.
  • 60°C high temperature storage capacity retention rate capacity after storage / capacity before storage ⁇ 100%.
  • the mixture precursor in a corundum crucible, introduce nitrogen at a rate of 2 m 3 /h, raise the temperature to 940°C at a heating rate of 5°C/min and maintain a constant temperature for 10 hours, then naturally cool to room temperature to obtain the additive.
  • the average particle size of the additive is 18.9 microns, and the surface of the additive particles has steps with a width of 600nm to 700nm, as shown in Figure 3(a) and Figure 3(b).
  • Step (2) Combine the positive active material lithium manganate (LiMn 2 O 4 ) (the average particle size of lithium manganate is 2.7 microns), the above-mentioned additives, conductive carbon black (Super P), carbon nanotubes (CNT), and polyethylene. Vinylidene fluoride (PVDF) is mixed according to the weight ratio of 90:5:1.8:1.2:2, and N-methylpyrrolidone (NMP) is added as the solvent to prepare a slurry with a solid content of 0.75, and stir evenly to obtain a slurry. . The slurry is evenly coated on both sides of the positive electrode current collector aluminum foil, and dried at 90°C to obtain the initial positive electrode piece. The initial positive electrode piece is subjected to processes such as cold pressing and cutting to obtain the positive electrode piece.
  • LiMn 2 O 4 the average particle size of lithium manganate is 2.7 microns
  • Super P conductive carbon black
  • CNT carbon nanotubes
  • NMP N-methylpyrrolidone
  • Negative electrode Mix graphite negative active material, conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) in a weight ratio of 97:1.0:2.0, add N-methylpyrrolidone (NMP) as a solvent, and prepare a solid A slurry with a content of 0.8 and stir evenly. The slurry is evenly coated on the negative electrode current collector copper foil and dried at 80°C to obtain the initial negative electrode piece. The initial negative electrode piece is subjected to processes such as cold pressing and cutting to obtain the negative electrode piece.
  • NMP N-methylpyrrolidone
  • Electrolyte In an argon atmosphere glove box with a water content of less than 10 ppm, add ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl propionate (EP), and propyl propionate. ester (PP), mix evenly according to the mass ratio of 1:1:1:1:1, and then dissolve the fully dried lithium salt LiPF 6 in the above-mentioned non-aqueous solvent to obtain a basic electrolyte, in which the mass percentage of LiPF 6 is 12.5 wt%
  • Isolation film PE porous polymer film is used as the isolation film.
  • Example 1-2 to 1-5 and Example 1-1 only lies in the content of the additive (wherein, the adjustment of the additive content is based on the total weight fraction of the additive and lithium manganate being 95%, The total weight of additives and lithium manganate accounts for 95% of the weight of the cathode active material).
  • the difference between Example 1-6 and Example 1-1 is that lithium iron phosphate is used to replace lithium manganate (wherein the average particle size of lithium iron phosphate is 0.4 micron), the difference between Examples 1-7 and 1-8 and Example 1-6 only lies in the content of the additive (wherein, the adjustment of the additive content is based on the total weight ratio of the additive and lithium iron phosphate being 95%.
  • the total weight of additives and lithium iron phosphate accounts for 95% of the weight of the cathode active material).
  • the cathode active material of Comparative Example 1-1 only contains lithium manganate, and the cathode active material of Comparative Example 1-2 only contains iron phosphate. lithium.
  • Table 1 shows the differences in composition and performance of the electrochemical devices of Examples 1-1 to 1-8 and Comparative Examples 1-1 and 1-2.
  • Diffraction peak 1 is the characteristic diffraction peak of the X-ray diffraction pattern of the positive electrode plate at the diffraction angle 2 ⁇ when it is fully discharged.
  • the peak position difference ⁇ 1 is the peak position difference between diffraction peak 1 and diffraction peak 2
  • the peak position difference ⁇ 2 is the peak position difference between diffraction peak 1 and diffraction peak 3, where the peak position difference should be understood as an absolute value.
  • Comparative Example 1-1 has no additive peaks. Therefore, the peak position difference ⁇ 1 in the above table is actually the diffraction peak 2 at the diffraction angle 2 ⁇ of the X-ray diffraction pattern of the positive electrode plate made of lithium manganate in the fully discharged state. .
  • Comparative Examples 1-2 do not have additive peaks. Therefore, the peak position difference ⁇ 2 in the above table is actually the diffraction peak 3 at the diffraction angle 2 ⁇ of the X-ray diffraction pattern of the positive electrode plate made of lithium iron phosphate in the fully discharged state. .
  • the lithium manganate cathode active material compare Examples 1-1 to 1-5 with Comparative Example 1-1, and for the lithium iron phosphate cathode active material, compare Examples 1-6 to 1-8 with Comparative Example 1-2, It can be seen that compared with the corresponding comparative examples without additives, the electrochemical properties of the examples with additives (first discharge gram capacity at 25°C and 0.2°C, 1500 cycles at 25°C, and 400 cycles at 45°C The capacity retention rate at 60°C and the high-temperature storage capacity retention rate at 60°C) are significantly improved. This is mainly because the additive can supplement the Li consumed by the positive electrode active material to form the SEI during the first charge, which is beneficial to improving the cycle and storage performance of lithium-ion batteries.
  • It can provide diffusion channels for lithium ions to facilitate the insertion and rapid insertion of lithium ions. It is deintercalated and has a lower voltage platform, which is conducive to the slow reintercalation of lithium ions during cycling and storage, thereby increasing the capacity of the cathode active material.
  • Example 2-1 to 2-10 and Example 1-1 lies in the difference in the A1 element content in the positive electrode active layer of Examples 2-1 to 2-7 and the difference in the VC content in the electrolyte used.
  • Examples 2-2 to 2-7 are when aluminum element is added to the additive.
  • the difference between the preparation process and Example 1-1 lies in step b): mix anhydrous Mn3O4 and LiOH according to Li:Mn of 1.05. ⁇ 1 molar ratio, and at the same time add nano-Al 2 O 3 according to the required Al:Mn element ratio, use a mixing device to mix for 8 hours to obtain a mixture precursor, and then prepare an additive containing aluminum elements.
  • the specific content is as shown in the table 2.
  • Table 2 below shows the differences in composition and performance of the electrochemical devices of Example 1-1 and Examples 2-1 to 2-7.
  • C is the value of the mass percentage of aluminum element based on the mass of the positive active layer
  • D is the value of the mass percentage of VC in the electrolyte.
  • the cycle performance and high-temperature storage performance of lithium-ion batteries can be further improved.
  • the capacity retention rates of Examples 2-1 to 2-7 that add aluminum element after 1500 cycles at 25°C and 400 times at 45°C, and 65°C The high-temperature storage capacity retention rate under the conditions has been significantly improved. This is mainly because the aluminum element can improve the stability of the unit cell when lithium ions are inserted or extracted, stabilize the crystal structure, thereby making the cathode active material structure more stable and improving the cycle performance of lithium-ion batteries.
  • the aluminum element can be added to the additive or to the lithium manganate, or both the additive and the lithium manganate contain aluminum element to stabilize the crystal structure of the material and improve the insertion or extraction of lithium ions.
  • the material structure stability is improved to improve the cycle performance of lithium-ion batteries.
  • anhydrous Mn 3 O 4 and LiOH are weighed according to a molar ratio of Li:Mn of 1.05:1, At the same time, add nano-Al 2 O 3 according to the required Al:Mn molar ratio, and mix using a mixing device for 8 hours to obtain a mixture precursor.
  • aluminum element is added to lithium manganate, it can be prepared by those skilled in the art based on common technical means in the art.
  • Example 3-1 to 3-8 The only difference between Examples 3-1 to 3-8 and Example 1-1 lies in the types and contents of additives in the electrolyte.
  • Example 3-1 Take Example 3-1 as an example to illustrate the preparation of the electrolyte: in an argon atmosphere glove box with a water content of ⁇ 10 ppm, add ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate ( DEC), ethyl propionate (EP), and propyl propionate (PP), mix them evenly according to the mass ratio of 1:1:1:1:1, and then dissolve the fully dried lithium salt LiPF6 in the above-mentioned non-aqueous solvent, An electrolyte solution was obtained, in which the mass percentage of LiPF6 was 12.5%. 1,3-propane sultone (PS) was added to the electrolyte in an amount of 1.5% (based on the mass of the electrolyte).
  • EC ethylene carbonate
  • PC propylene carbonate
  • DEC diethyl carbonate
  • EP ethyl propionate
  • PP propyl propionate
  • Embodiments 3-2 to 38 are basically the same as those of Embodiment 3-1, and the only difference lies in the types and contents of electrolyte additives.
  • carbonic acid is added in an amount of 1.5%.
  • VC vinylene ester
  • Table 3 below shows the differences in composition and performance of the electrochemical devices of Example 1-1 and Examples 3-1 to 3-8.
  • the performance of the electrochemical device can be further improved by adding electrolyte additives.
  • electrolyte additives for example, by adding 1,3-propane sultone (PS), vinylene carbonate (VC), 1,3-propene sultone (PES), and fluoroethylene carbonate (FEC) to the electrolyte or at least one of vinyl sulfate (DTD), the high-temperature storage capacity retention of the electrochemical device was improved both after 1500 cycles at 25°C and at 60°C. This is mainly because different electrolyte additives have different effects on improving the battery system. Among them, VC and FEC can be used as CEI film-forming additives to form a more stable CEI film.
  • VC and FEC can also increase the flexibility of the CEI film and reduce the The impedance of the positive electrode interface.
  • Compounds containing sulfur and oxygen double bonds can form a protective film on the positive and negative electrode interfaces, reduce side reactions between the positive and negative electrode interfaces and the electrolyte, reduce the transmission impedance inside the lithium-ion battery, and help improve the normal temperature of the battery. and high-temperature cycle performance and high-temperature storage performance.
  • the additives described in this technology stabilize the original morphology and structure of the positive electrode active material, and at the same time form a dense interface film on the surface of the positive electrode, improve the stability of the positive electrode material, reduce side reactions, thereby reducing the material
  • the impedance improves the cycle performance of lithium-ion batteries.
  • references throughout this specification to “some embodiments,” “partial embodiments,” “one embodiment,” “another example,” “example,” “specific example,” or “partial example” mean the following: At least one embodiment or example in this application includes a specific feature, structure, material or characteristic described in the embodiment or example. Accordingly, phrases such as “in some embodiments,” “in an embodiment,” “in one embodiment,” “in another example,” “in one example,” etc. may appear in various places throughout this specification. "in”, “in a particular example” or “for example” do not necessarily refer to the same embodiment or example in this application. Furthermore, the specific features, structures, materials, or characteristics herein may be combined in any suitable manner in one or more embodiments or examples.

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Abstract

本申请涉及一种电化学装置，其包括正极极片、负极极片和电解液，所述正极极片包括正极活性层，所述正极活性层包括正极活性材料，所述正极活性材料包括添加剂，对所述电化学装置进行充放电，其中，当所述电化学装置在满放状态下时，所述正极极片的X射线衍射图谱在衍射角2θ为17.5°至19.5°具有特征衍射峰1，其中所述添加剂包含锰元素，可显著提高正极活性材料的充放电容量，改善电化学装置的循环性能和高温存储性能。

Description

一种电化学装置及包含该电化学装置的电子装置 技术领域
本申请涉及储能领域，具体涉及一种电化学装置及包含该电化学装置的电子装置。
背景技术
电化学装置如锂离子电池由于其重量轻，能量密度高等优势，市场占有率逐年递增。随着新能源汽车和储能领域的快速发展，要求正极活性材料如锰酸锂等具有更高的充放电容量，同时也要求电化学装置具有更优的循环性能和存储性能。
发明内容
根据本申请的一方面，本申请涉及一种电化学装置，其包括正极极片、负极极片和电解液，所述正极极片包括正极活性层，所述正极活性层包括正极活性材料，所述正极活性材料包括添加剂，对所述电化学装置进行充放电，其中，当所述电化学装置在满放状态下时，所述正极极片的X射线衍射图谱在衍射角2θ为17.5°至19.5°的范围内具有特征衍射峰1，其中所述添加剂包含锰元素。添加剂可补充正极活性材料在首次充电时形成CEI膜消耗的锂离子，同时可为锂离子提供扩散通道，便于锂离子的嵌入和快速脱嵌，且该添加剂具有较低的电压平台，在循环和存储过程中，有利于锂离子的缓慢回嵌，从而提高正极活性材料的充放电容量，显著改善电化学装置的循环性能和高温存储性能
在一些实施例中，所述正极活性材料包括锰酸锂。
在一些实施例中，当所述电化学装置在满放状态下，所述正极极片的X射线衍射图谱在衍射角2θ为17.5°至19.5°的范围内还具有特征衍射峰2。
在一些实施例中，所述特征衍射峰1和所述特征衍射峰2的峰位差满足0.33°≤Δθ1≤0.53°。
在一些实施例中，所述正极活性材料包括磷酸铁锂。
在一些实施例中，当所述电化学装置在满放状态下，所述正极极片的X射线衍射图谱在衍射 角2θ为19.8°至21.8°的范围内具有特征衍射峰3。
在一些实施例中，所述特征衍射峰3和所述特征衍射峰1的峰位差满足2°≤Δθ2≤3°。
在一些实施例中，基于所述正极活性材料的质量，所述添加剂占所述正极活性材料的质量百分比为3％至20％，将添加剂的含量限定在上述范围内，可提高电化学装置的首次充电克容量和首次库伦效率。
在一些实施例中，所述正极活性层包含元素M，所述元素M包含Al、Nb、Mg、Ti、Ce、W、Ga、Zr、W、Y、V、Na、Sr、Mo、Cr、Sn或La中的至少一种，基于所述正极活性层的质量，所述元素M的质量百分比为0.03％至3.5％，元素M可抑制金属溶出，稳定正极活性材料结构，提高锂离子的扩散，提升电化学装置的循环性能和高温存储性能。
在一些实施例中，基于所述正极活性层的质量，所述元素M的质量百分比为0.3％至1.5％。
在一些实施例中，所述电解液包含电解液添加剂，所述电解液添加剂包括硫氧双键化合物、碳酸亚乙烯酯或氟代碳酸乙烯酯中的至少一种，基于所述电解液的质量，所述电解液添加剂的质量百分比为0.001％至10％，。所述电解液添加剂可稳定正极活性材料的原始形貌和结构，同时可在正极极片表面形成致密的界面保护膜，提高正极材料稳定性，降低正极界面阻抗，进一步提升电化学装置的循环性能。在一些实施例中，基于所述电解液的质量，所述电解液添加剂的质量百分比为0.01％至5％。
在一些实施例中，所述含硫氧双键化合物包含1，3-丙烷磺酸内酯(PS)、1，3-丙烯磺酸内酯(PES)或硫酸乙烯酯(DTD)中的至少一种。
在一些实施例中，所述正极活性材料包含铝元素，基于所述正极活性材料质量，铝元素的质量百分比为C％，所述电解液中的碳酸亚乙烯酯(VC)的质量百分比为D％，C/D满足0.03≤C/D≤0.5。添加铝元素会进一步稳定正极活性材料的结构，VC可在正极界面形成稳定的CEI膜，通过控制铝元素与VC的质量百分比满足上述关系式，可进一步稳定正极活性材料的结构，提升电化学装置的高温存储性能和循环性能。
在一些实施例中，所述添加剂颗粒具有层状结构，且其表面具有宽度为1nm至1000nm的台阶。通过将层状结构的含锰化合物添加剂加入到正极活性材料中，可在电化学装置首次充电时补充形成CEI所消耗的活性离子，有利于改善电化学装置的循环和存储性能，同时可为锂离子提供 扩散通道，提高正极活性材料的充放电容量，使电化学装置的倍率性能、高温存储以及循环性能得到进一步提升。
在一些实施例中，所述添加剂的平均粒径为F，F的范围为5μm至40μm。将添加剂的平均粒径控制在上述范围内时，可提高正极活性材料的充放电容量，提升电化学装置的高温存储以及循环性能。
根据本申请的另一方面，本申请涉及包含根据前述任一实施例所述的电化学装置的电子装置。
本申请中，在正极活性材料中加入含有锰元素的添加剂，电化学装置在满放状态下时，所述正极极片的X射线衍射图谱在衍射角2θ为17.5°至19.5°的范围内具有特征衍射峰1，加入的含锰添加剂可补充正极活性材料在首次充电时形成CEI膜消耗的锂离子，同时可为锂离子提供扩散通道，便于锂离子的嵌入和快速脱嵌，且该添加剂具有较低的电压平台，在循环和存储过程中，有利于锂离子的缓慢回嵌，从而提高正极活性材料的容量，显著改善电化学装置的循环性能和高温存储性能。
附图说明
图1是实施例1-1的电化学装置在满放状态下的正极极片的XRD图。
图2是对比例1-1的电化学装置在满放状态下的正极极片的XRD图。
图3(a)和图3(b)是满放态下的实施例1-1的正极活性材料的SEM图。
具体实施方式
下文中，对本申请进行详细说明。应当理解，在说明书和所附权利要求中使用的术语不应被解释为限于一般和词典的含义，而是在发明人被允许适当定义术语以进行最佳解释的原则的基础上基于与本申请的技术方面相对应的含义和概念来解释。因此，说明书中所述的实施方案中所示的描述仅仅是用于说明的目的的具体实例，而不旨在显示本申请的所有技术方面，并且应当理解，在提交本申请时可以对其完成多种可选等价体和变体。
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。
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。
一、电化学装置
根据本申请的一方面，本申请涉及一种电化学装置，其包括正极极片、负极极片和电解液，所述正极极片包括正极活性层，所述正极活性层包括正极活性材料，所述正极活性材料包括添加剂，对所述电化学装置进行充放电，其中，当所述电化学装置在满放状态下时，所述正极极片的X射线衍射(XRD)图谱在衍射角2θ为17.5°至19.5°的范围内具有特征衍射峰1，其中所述添加剂包含锰元素。所述特征衍射峰1是添加剂的特征衍射峰。该添加剂可以补充正极活性材料在首次充电时形成正极-电解质界面(CEI)所消耗的锂离子，有利于改善电化学装置的循环性能和高温存储性能，可为锂离子提供扩散通道，便于锂离子的嵌入和快速脱嵌；且具有较低的电压平台(如3.9V的平台)，在电化学装置的循环和存储过程中，有利于锂离子的缓慢回嵌，从而提升正极活性材料的充放电容量。
在一些实施例中，所述添加剂包括层状结构的含锰化合物。在一些实施例中，所述含锰化合物包括LiMn 2O 3、Li 2MnO 3或LiMnO 2中的至少一种。
在一些实施例中，所述正极活性材料包括锰酸锂，当所述电化学装置在满放状态下，所述正极极片的X射线衍射图谱在衍射角20为17.5°至19.5°的范围内还具有特征衍射峰2，所述特征衍射峰1和所述特征衍射峰2的峰位差满足0.33°≤Δθ1＜0.53°。
在一些实施例中，所述正极活性材料包括磷酸铁锂，当所述电化学装置在满放状态下，在衍射角2θ为19.8°至21.8°的位置具有衍射峰3，所述特征衍射峰3和所述特征衍射峰1的峰位差满足2°≤Δθ2≤3°。
在一些实施例中，基于所述正极活性材料的质量，所述添加剂的质量百分比为3％至20％。在一些实施例中，基于所述正极活性材料的质量，所述添加剂的质量百分比为3％、4％、6％、8％、10％、12％、14％、16％、18％、20％或前述任意两数值之间的范围。当添加剂的含量过少时，由其制备的电化学装置的首次充电克容量降低，当添加剂含量过高时，由其制备的电化学装置的首次库伦效率降低，这主要是因为所述添加剂具有较高的首次充电克容量，可补偿锰酸锂在首次充电时用于形成CEI膜消耗的Li+，但添加剂在首次放电时，仅有部分Li可以回嵌。通过研究，将添加剂的含量限定在上述范围内，电化学装置的首次充电克容量和首次库伦效率均明显提升。在一些实施例中，基于所述正极活性材料的质量，所述添加剂的质量百分比为3％至15％，此时电化学装置具有较高的首次充电克容量和库伦效率。
在一些实施例中，所述正极活性层的单面涂布重量为100mg至500mg/1540.25mm 2，其中，所述正极活性层的质量，所述正极活性材料的质量百分比为94％至98％。
在一些实施例中，所述电解液包含电解液添加剂，所述电解液添加剂包括硫氧双键化合物、碳酸亚乙烯酯(VC)或氟代碳酸乙烯酯(FEC)中的至少一种，基于所述电解液的质量，所述电解液添加剂的质量百分比为0.001％至10％。在一些实施例中，基于所述电解液的质量，所述添加剂的质量百分比为0.001％、2％、3％、4％、5％、6％、7％、8％、9％、10％或前述任意两数值之间的范围。在一些实施例中，所述含硫氧双键化合物包含1，3-丙烷磺酸内酯(PS)、1，3-丙烯磺酸内酯(PES)或硫酸乙烯酯(DTD)中的至少一种。不同电解液添加剂对电池体系起到了不同的改善作用。其中，VC、FEC可作为CEI成膜添加剂，可形成更稳定的CEI膜，VC、FEC还可以增加CEI膜的柔性，降低正极界面的阻抗。含硫氧双键的化合物可在正负极界面形成保护膜，减少正负极界面和电解液间的副反应，降低电池内部的传输阻抗，有利于提高电池的常温和高温循环性能以及高温存储性能。上述电解液添加剂稳定了正极活性材料的原始形貌和结构，同时使得正极极片表面形成致密的界面膜，提高正极材料稳定性，减少副反应，从而降低了材料的阻抗，提高了电池的循环性能。在一些实施例中，所述电解液添加剂的质量百分比为0.01％至5％，此时电解液添加剂可在正负极界面形成柔性保护膜，降低界面阻抗，有效提升电化学装置的常/高温循环性 能和高温存储性能。
在一些实施例中，所述正极活性层包含元素M，其中M包含Al、Nb、Mg、Ti、Ce、W、Ga、Zr、W、Y、V、Na、Sr、Mo、Cr、Sn或La中的至少一种。在一些实施例中，基于所述正极活性层的质量，元素M的质量百分比为0.03％至3.5％。在一些实施例中，基于所述正极活性层的质量，元素M的质量百分比为0.03％、0.05％、0.1％、0.2％、0.4％、0.6％、0.8％、1.0％、1.2％、1.4％、1.6％、1.8％、2.0％、2.2％、2.4％、2.6％、2.8％、3.0％、3.2％、3.4％、3.5％或前述任意两数值之间的范围。元素M可稳定正极活性材料结构，减少相变，抑制过渡金属溶出，有助于锂离子的扩散，提升电化学装置的循环性能及高温存储性能，元素M含量过高时会使正极活性材料内部晶格膨胀，破坏材料结构稳定性，影响电化学装置的循环性能。在一些实施例中，基于所述正极活性层的质量，元素M的质量百分比为0.03％至1.5％，在此含量范围内时，元素M可有效抑制金属溶出，提高锂离子的扩散，提升电化学装置的循环性能和高温存储性能。
在一些实施例中，所述正极活性材料包含铝元素，基于所述正极活性层的质量，铝元素的质量百分比为C％，所述电解液中的VC的质量百分比为D％，满足0.03≤C/D≤0.5。添加铝元素会进一步正极活性材料的结构，VC可在正极界面形成稳定的CEI膜，通过控制铝元素与VC的质量百分比满足上述关系式，可进一步稳定正极活性材料的结构，提升电化学装置的高温存储性能和循环性能。
在一些实施例中，所述添加剂的平均粒径为F，F的范围为5μm至40μm，且所述添加剂颗粒的表面具有宽度为1nm至1000nm的台阶。参见附图3(a)和3(b)，较大的颗粒是添结剂的颗粒，其是层状结构，表面具有一层一层的台阶，其中台阶的宽度为1nm至1000nm。通过将层状结构的含锰化合物加入到正极活性材料中，电化学装置的容量、倍率性能、高温存储以及循环性能都得到显著提升。这主要是因为层状结构的含锰化合物在电化学装置首次充电时补充形成CEI所消耗的锂离子，有利于改善电化学装置的循环和存储性能，同时可为锂离子提供扩散通道，便于锂离子的嵌入和快速脱嵌，且其具有较低的电压平台(如3.9V的平台)，在循环和存储过程中，有利于锂离子的缓慢回嵌，从而提升正极活性材料的充放电容量。
根据本申请的另一方面，本申请涉及包含根据前述任一实施例所述的电化学装置的电子装置。
二、电化学装置的制备
如下以锂离子电池为例详细描述了本申请的电化学装置的制备方法。
负极的制备：将负极活性材料、导电剂、粘结剂和增稠剂按一定的质量比分散于溶剂体系中充分搅拌混合均匀后，涂覆于负极集流体上，经过烘干、冷压，得到负极极片。
作为示例，负极活性物质可以是天然石墨、人造石墨、中间相微碳球(MCMB)、硬碳、软碳、硅、硅-碳复合物、SiO、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO 2、尖晶石结构的钛酸锂Li 4Ti 5O 12、Li-Al合金及金属锂中的一种或多种；导电剂可以是石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种或多种；粘结剂可以是丁苯橡胶(SBR)、聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇缩丁醛(PVB)、水性丙烯酸树脂(water-basedacrylic resin)及羧甲基纤维素(CMC)中的一种或多种；增稠剂可以是羧甲基纤维素(CMC)。
负极集流体可以使用金属箔材或多孔金属板等材料，例如使用铜、镍、钛或铁等金属或它们的合金的箔材或多孔板，如铜箔。
正极的制备：
正极活性材料中的添加剂的制备：
a)将Mn 3O 4放置在刚玉坩埚中，在空气气氛下，以5℃/min的升温速率升温至500℃并保持恒温1h，得到无水Mn 3O 4。
b)将无水Mn 3O 4与LiOH按照Li∶Mn为1.05∶1的摩尔比例进行称取，同时按照Al∶Mn元素质量比为0.015∶1的比例加入纳米Al 2O 3，使用混合设备混合8h，得到混合物前驱体。
c)将混合物前驱体放置在刚玉坩埚中，以2m 3/h的速度通入氮气，以5℃/min的升温速率升温至940℃并保持恒温10h，自然冷却至室温，即得到所述添加剂。
将正极活性材料(锰酸锂(LiMn 2O 4)、磷酸铁锂或其它正极活性材料)、上述添加剂、导电剂、粘结剂按照一定的重量比进行混合，加入溶剂中并搅拌均匀得到浆料。将浆料均匀涂覆在正极集流体铝箔上，90℃条件下烘干，得到初始正极极片。将初始正极极片经冷压、裁切等工序，得到正极极片。
在一些实施例中，导电剂以通过向活性物质提供导电路径来改善所述正极活性层的导电性。所述导电剂可以包括如下中的至少一种：乙炔黑、科琴黑、天然石墨、炭黑、碳纤维、金属粉末或金属纤维(例如铜、镍、铝或银)，但所述导电剂的示例并不限于此。在一些实施例中，可适宜的调节导电剂的量。基于100重量份的正极活性物质、导电剂和正极粘结剂的总量，所述导电剂的量的范围为1重量份至30重量份。
在一些实施例中，所述溶剂的示例包括但不限于N-甲基吡咯烷酮、丙酮或水。在一些实施例中，可适当的调节溶剂的量。
在一些实施例中，粘结剂改善正极活性物质颗粒彼此间以及正极活性物质颗粒与集流体的粘结性能。所述正极粘结剂的示例包括但不限于粘结剂可以是聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚乙烯醇缩丁醛(PVB)、乙烯-醋酸乙烯酯共聚物(EVA)及聚乙烯醇(PVA)中的一种或多种。基于100重量份的活性物质、导电剂和正极粘结剂的总量，所述正极粘结剂的量的范围为1重量份至30重量份。
在一些实施例中，所述集流体具有3微米至20微米范围内的厚度，但本公开内容不限于此。所述集流体是导电的，且不在所制造的电池中引起不利的化学变化。所述集流体的实施例包括铜、不锈钢、铝、镍、钛或合金(例如铜-镍合金)，但不公开内容不限于此。在一些实施例中，所述集流体的表面上可包括细小的不规则物(例如，表面粗糙度)以增强所述集流体的表面对活性物质的粘合。在一些实施例中，集流体可以多种形式使用，其实施例包括膜、片、箔、网、多孔结构体、泡沫体或无妨物，但本公开内容不限于此。
隔离膜：本申请的实施例对隔离膜无特别限制，所述的隔离膜包含：聚烯烃微多孔膜，以及涂层(涂覆于聚乙烯微多孔膜的表面上)，所述的隔膜选自聚乙烯(PE)、乙烯-丙烯共聚物、聚丙烯(PP)、乙烯-丁烯共聚物、乙烯-己烯共聚、乙烯-甲基丙烯酸甲酯共聚物中的一种或多种组成的单层或多层的聚烯烃微多孔膜。所述涂层包括无机陶瓷颗粒，所述无机陶瓷颗粒选自SiO 2、Al 2O 3、CaO、TiO 2、ZnO 2、MgO、ZrO 2以及SnO 2中的一种或几种。
电解液：根据本申请的实施例，所述电解液包含非水有机溶剂和锂盐。非水有机溶剂可以包含碳酸酯、羧酸酯、醚化合物、砜化合物或其他非质子溶剂。碳酸酯溶剂的示例包含有碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸二丙酯、碳酸乙烯酯、碳酸丙烯 酯、碳酸丁烯酯、二(2，2，2-三氟乙基)碳酸酯等。醚化合物溶剂的示例包含有乙二醇二甲醚、二乙二醇二甲醚、四乙二醇二甲醚、二丁醚、四氢呋喃、2-甲基四氢呋喃、双(2，2，2-三氟乙基)醚、1，3-二氧六环、1，4-二氧六环等。砜化合物溶剂的示例包含有乙基乙烯基砜、甲基异丙基砜、异丙基仲丁基砜、环丁砜等。
根据本申请的实施例，所述电解液中非水有机溶剂，可以使用单非水有机溶剂，也可以使用多种非水有机溶剂混合，当使用混合溶剂时，可以根据期望的电化学装置性能进行控制混合比。
根据本申请的实施例，所述电解液中的锂盐包括或选自有机锂盐或无机锂盐中的至少一种，所述锂盐包括或选自六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、双草酸硼酸锂(LiB(C 2O 4) 2，LiBOB)、二氟草酸硼酸锂(LiBF 2(C 2O 4)，LiDFOB)、六氟锑酸锂(LiSbF 6)、六氟砷酸锂(LiAsF 6)、全氟丁基磺酸锂(LiC 4F 9SO 3)、高氯酸锂(LiClO 4)、铝酸锂(LiAlO 2)、四氯铝酸锂(LiAlCl 4)、双磺酰亚胺锂(LiN(C xF 2x+1SO 2)(C yF 2y+1SO 2)，其中x和y是自然数)、氯化锂(LiCl)、氟化锂(LiF)中的至少一种。
电解液的制备：在含水量＜10ppm的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)、丙酸乙酯(EP)、丙酸丙酯(PP)，按照1∶1∶1∶1∶1的质量比混合均匀，再将充分干燥的锂盐LiPF6溶解于上述非水溶剂，得到基础电解液，其中LiPF6的质量百分比为12.5％
将正极、隔离膜、负极按顺序叠好，使隔离膜处于正负极中间起到隔离的作用，并卷绕得到裸电芯。将经卷绕所得裸电芯置于外包装中，注入电解液并封装，经过化成、脱气、切边等工艺流程获得锂离子电池。
三、电子装置
本申请提供了一种电子装置，其包含根据前述内容所述的电化学装置。
根据本申请的一些实施例，所述电子装置包括，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、家庭用大型蓄电池等。
三、具体的实施例
下面以锂离子电池为例，结合实施例，对本申请做进一步详细的描述。然而，应理解，以下实施例仅是示例，本申请的实施例方式不限于此。
性能测试方法
XRD的测试方法
取满放态锂离子电池，拆解得到正极极片，对正极极片进行XRD测试，正极极片放置在XRD测试仪器(型号布鲁克，D8)样品台中，使用2°/min的扫描速率，扫描角度范围10°至90°，得到XRD衍射图。读取相应衍射峰，记录其峰位和半峰宽。
颗粒形貌测试
拆解锂离子电池得到正极极片，利用扫描电子显微镜(JEOL公司的JSM-6360LV型)拍摄拆解锂离子电池得到的正极极片的SEM照片，观察正极活性材料颗粒形貌。
平均粒径测试
拆解锂离子电池得到正极极片，利用扫描电子显微镜拍摄拆解锂离子电池得到的正极极片的SEM照片，观察正极活性材料颗粒，然后，使用图像解析软件，从SEM照片中随机地选出30个颗粒，求出这些颗粒各自的面积，接着，假设颗粒是球形，通过以下公式求出各自的粒径D(直径)：D＝2×(S1/π)1/2；其中，S1为颗粒的面积；并将所得30个颗粒的粒径进行算数平均，从而求得所述颗粒的平均粒径。
元素含量测试方法
拆解锂离子电池得到正极极片，用DMC清洗拆解锂离子电池得到的正极极片，将清洗后的正极极片的正极活性层用刮刀刮下，使用混合溶剂溶解正极活性层(例如，0.4g正极活性层使用10ml王水(硝酸与盐酸按照1∶1混合)与2ml HF的混合溶剂)，定容至100mL，然后使用ICP分析仪测试溶液中Al、Nb、Mg、Ti、Ce、W、Ga、Zr、W、Y、V、Na、Sr、Mo、Cr、Sn或La的质量百分比(基于正极活性层的质量)。
锂离子电池的容量测试-25℃0.2C首次放电克容量(mAh g -1)
将使用实施例和对比例中所示的正极材料制备的锂离子电池每组分别取4块，在25℃恒温条件下，先利用0.5C(即2h内完全放掉理论容量的电流值)的电流进行恒流充电，充电至4.2V 后进行恒压充电，然后在0.2C的电流下进行恒流放电，放电至2.8V，计算0.2C首次放电容量作为电池的容量。
锂离子电池的循环性能测试
将使用实施例和对比例中所示的正极材料制备的锂离子电池每组分别取4块，通过以下步骤分别对4块锂离子电池进行重复充电和放电，并计算锂离子电池的放电容量保持率。
首先，分别在25/45℃的环境中，进行首次充电和放电，先利用0.5C的电流进行恒流充电，充电至4.2V后进行恒压充电，然后在1C的电流下进行恒流放电，放电至2.8V，记录首次循环的放电容量；然后进行1500/400次的充电和放电循环，记录第1000/500次循环的放电容量。
25℃循环容量保持率＝(第1500次循环的放电容量/首次循环的放电容量)×100％。
45℃循环容量保持率＝(第400次循环的放电容量/首次循环的放电容量)×100％。
锂离子电池的高温存储测试
将使用实施例和对比例中所示的正极材料制备的锂离子电池每组分别取4块，在60℃的环境中，先利用0.5C的电流进行恒流充电，充电至4.2V后进行恒压充电，然后在1C的电流下进行恒流放电，放电至2.8V，记录放电容量，记为存储前容量；以0.5C恒定电流充电至3.99V，在恒定电压下充电至电流低于0.05C，将电池置于60℃烘箱存储14D后，在1C的放电电流下进行恒流放电，放电至2.8V；然后在0.5C的充电电流下进行恒流和恒压充电，直到上限电压为4.2V，然后在1C的放电电流下进行恒流放电，放电至2.8V，记录放电容量，记为存储后容量。
60℃高温存储容量保持率＝存储后容量/存储前容量×100％。
A.实施例1-1至1-8和对比例1-2
实施例1-1的制备方法：
步骤(1)：
a)将MnOOH放置在刚玉坩埚中，在空气气氛下，以5℃/min的升温速率升温至500℃并保持恒温1h，得到无水Mn 3O 4。
b)将无水Mn 3O 4与LiOH按照Li∶Mn为1.05∶1的摩尔比例进行称取，同时按照Cr∶ Mn元素质量比为0.015∶1的比例加入纳米Cr 2O 3，使用混合设备混合8h，得到混合物前驱体。
c)将混合物前驱体放置在刚玉坩埚中，以2m 3/h的速度通入氮气，以5℃/min的升温速率升温至940℃并保持恒温10h，自然冷却至室温，即得到添加剂。其中，添加剂的平均粒径为18.9微米，添加剂颗粒表面具有宽度为600nm至700nm的台阶，可参见图3(a)和图3(b)。
步骤(2)：将正极活性材料锰酸锂(LiMn 2O 4)(锰酸锂的平均粒径为2.7微米)、上述添加剂、导电炭黑(Super P)、碳纳米管(CNT)、聚偏二氟乙烯(PVDF)按照重量比90∶5∶1.8∶1.2∶2进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成为固含量为0.75的浆料，并搅拌均匀得到浆料。将浆料均匀涂覆在正极集流体铝箔的双面上，90℃条件下烘干，得到初始正极极片。将初始正极极片经冷压、裁切等工序，得到正极极片。
负极：将石墨负极活性材料、导电炭黑(Super P)、聚偏二氟乙烯(PVDF)按照重量比97∶1.0∶2.0进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成为固含量为0.8的浆料，并搅拌均匀。将浆料均匀涂覆在负极集流体铜箔上，80℃条件下烘干，得到初始负极极片。将初始负极极片经冷压、裁切等工序，得到负极极片。
电解液：在含水量＜10ppm的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)、丙酸乙酯(EP)、丙酸丙酯(PP)，按照1∶1∶1∶1∶1的质量比混合均匀，再将充分干燥的锂盐LiPF 6溶解于上述非水溶剂，得到基础电解液，其中LiPF 6的质量百分比为12.5wt％
隔离膜：以PE多孔聚合薄膜作为隔离膜。
将正极、隔离膜、负极按顺序叠好，使隔离膜处于正负极中间起到隔离的作用，并卷绕、置于外包装中，注入配好的电解液并封装，经过化成，脱气，切边等工艺得到锂离子电池。
实施例1-2至1-5与实施例1-1的区别仅在于添加剂的含量的不同(其中，添加剂含量的调节是以添加剂和锰酸锂的总重量分数为95％为基准进行的，添加剂和锰酸锂的总重量占正极活性材料重量的95％)，实施例1-6与实施例1-1的区别在于用磷酸铁锂替换锰酸锂(其中磷酸铁锂的平均粒径为0.4微米)，实施例1-7和1-8与实施例1-6的区别仅在于添加剂的含量的不同(其中，添加剂含量的调节是以添加剂和磷酸铁锂的总重量比为95％为基准进行 的，添加剂和磷酸铁锂的总重量占正极活性材料重量的95％)，对比例1-1的正极活性材料只含有锰酸锂，对比例1-2的正极活性材料只含有磷酸铁锂。具体请参见如下表1，其给出了实施例1-1至1-8与对比例1-1和1-2的电化学装置组成的差异以及性能。
表1：
Figure PCTCN2022103000-appb-000001
注：衍射峰1是满放状态下时，正极极片的X射线衍射图谱在衍射角2θ的特征衍射峰。峰位差Δθ 1是衍射峰1和衍射峰2的峰位差，峰位差Δθ 2是衍射峰1和衍射峰3的峰位差，其中，峰位差应理解为绝对值。对比例1-1没有添加剂的峰，因此，上述表格中的峰位差Δθ1实际是在满放状态下，由锰酸锂制备的正极极片的X射线衍射图谱在衍射角2θ的衍射峰2。对比例1-2没有添加剂的峰，因此，上述表格中的峰位差Δθ2实际是在满放状态下，由磷酸铁锂制备的正极极片的X射线衍射图谱在衍射角2θ的衍射峰3。
参考表1以及附图1、图2可知，实施例1-1至1-8的正极活性层中加入了添加剂，当所述电化学装置在满放状态下时，所述正极极片的X射线衍射(XRD)图谱在衍射角2θ为17.5°至19.5°的范围内具有特征衍射峰1。对于锰酸锂正极活性材料，对比实施例1-1至1-5与对比例1-1，对于磷酸铁锂正极活性材料，对比实施例1-6至1-8与对比例1-2，可知，相较于相应的不含有添加剂的对比例，具有添加剂的实施例的电化学性能(25℃、0.2C条件下的首次放电克容量、25℃下循环1500次、45℃下循环400次时的容量保持率，以及60℃下的高温存储容量保持率)均得到显著改善。这主要是因为，该添加剂可以补充正极活性材料在首次充电时形成SEI所消耗的Li，有利于改善锂离子电池的循环和存储性能，可为锂离子提供扩散通道，便于锂离子的嵌入和快速 脱嵌且具有较低的电压平台，在循环和存储过程中，有利于锂离子的缓慢回嵌，从而提升正极活性材料的容量。
B.实施例1-1与实施例2-1至实施例2-10
实施例2-1至2-10与实施例1-1的区别仅在于实施例2-1至实施例2-7的正极活性层中A1元素含量的不同以及所用电解液中VC含量的不同。实施例2-2至实施例2-7为将铝元素加入至添加剂中时、，其制备工艺与实施例1-1的不同在于步骤b)：将无水Mn3O4与LiOH按照Li∶Mn为1.05∶1的摩尔比例进行称取，同时按照所需Al∶Mn元素比例来加入纳米Al 2O 3，使用混合设备混合8h，得到混合物前驱体，进而制备得到含铝元素的添加剂，具体含量如表2，如下表2示出了实施例1-1与实施例2-1至实施例2-7的电化学装置组成的差异以及性能。
表2：
Figure PCTCN2022103000-appb-000002
注：C为基于正极活性层的质量，铝元素的质量百分比的数值；D为电解液中的VC的质量百分比的数值。
通过参考表2可以看出，通过对正极活性材料添加铝元素，可以进一步改善锂离子电池的循环性能和高温存储性能。例如，相对于未包含铝元素的实施例1-1，添加铝元素的实施例2-1至2-7的25℃下循环1500次、45℃下循环400次的容量保持率，以及65℃下的高温存储容量保持率均得到显著改善。这主要是因为，铝元素可改善锂离子嵌入或脱出时的晶胞稳定性，稳定晶体结构，进而使正极活性材料结构更加稳定，改善锂离子电池的循环性能。本申请研究发现，通过将元素的种类和含量限定在0.1％至3.5％，可以使锂离子电池具有较优的性能。根据本申请实施例，当0.2＜A/B＜1.5或0.03≤C/D≤0.5时，电化学装置的的循环性能和高温存储性能更佳。添加铝 元素会进一步正极活性材料的结构，VC可在正极界面形成稳定的CEI膜，通过控制铝元素与VC的质量百分比满足上述关系式，可进一步稳定正极活性材料和保护正极界面，提升锂离子电池的高温存储性能和循环性能。另外，应当理解，铝元素既可以加入至添加剂中，也可以加入至在锰酸锂中，或者添加剂和锰酸锂中均含有铝元素，达到稳定材料的晶体结构，改善锂离子嵌入或脱出时的材料结构稳定性，提升锂离子电池的循环性能。当将铝元素加入至添加剂中时，其制备工艺与实施例1-1的不同在于步骤b)：将无水Mn 3O 4与LiOH按照Li∶Mn为1.05∶1的摩尔比例进行称取，同时按照所需Al∶Mn摩尔比例来加入纳米Al 2O 3，使用混合设备混合8h，得到混合物前驱体。当将铝元素加入至锰酸锂中时，其可以由本领域技术人员基于本领域惯用技术手段来制备。
C.实施例1-1与实施例3-1至实施例3-8
实施例3-1至3-8与实施例1-1的区别仅在于电解液中添加剂的种类和含量的不同。
如下以实施例3-1为例来说明其电解液的制备：在含水量＜10ppm的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)、丙酸乙酯(EP)、丙酸丙酯(PP)，按照1∶1∶1∶1∶1的质量比混合均匀，再将充分干燥的锂盐LiPF6溶解于上述非水溶剂，得到电解液，其中LiPF6的质量百分比为12.5％。向电解液中以1.5％的量添加1，3-丙烷磺酸内酯(PS)(基于电解液的质量)。
实施例3-2至38的电解液的制备方法与实施例3-1基本相同，区别仅在于电解液添加剂的种类和含量的不同，例如，实施例3-2除了以1.5％的量将碳酸亚乙烯酯(VC)添加进电解液以外，重复实施例3-1的步骤。
如下表3给出了实施例1-1与实施例3-1至实施例3-8的电化学装置组成的差异以及性能。
表3：
Figure PCTCN2022103000-appb-000003
Figure PCTCN2022103000-appb-000004
通过表3的实施例可以看出，通过加入电解液添加剂，可以进一步改善电化学装置的性能。例如，通过向电解液中添加1，3-丙烷磺酸内酯(PS)、碳酸亚乙烯酯(VC)、1，3-丙烯磺酸内酯(PES)、氟代碳酸乙烯酯(FEC)或硫酸乙烯酯(DTD)中的至少一种，电化学装置在25℃下循环1500次以及60℃下的高温存储容量保持率均得到改善。这主要是因为不同电解液添加剂对电池体系起到了不同的改善作用，其中，VC、FEC可作为CEI成膜添加剂，可形成更稳定的CEI膜，VC、FEC还可以增加CEI膜的柔性，降低正极界面的阻抗，含硫氧双键的化合物可在正负极界面形成保护膜，减少正负极界面和电解液间的副反应，降低锂离子电池内部的传输阻抗，有利于提高电池的常温和高温循环性能以及高温存储性能，本技术所述添加剂稳定了正极活性材料的原始形貌和结构，同时使得正极表面形成致密的界面膜，提高正极材料稳定性，减少副反应，从而降低了材料的阻抗，提升了锂离子电池的循环性能。
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 (13)

  1. 一种电化学装置，其包括正极极片、负极极片和电解液，所述正极极片包括正极活性层，所述正极活性层包括正极活性材料，所述正极活性材料包括添加剂，对所述电化学装置进行充放电，其中，当所述电化学装置在满放状态下时，所述正极极片的X射线衍射图谱在衍射角2θ为17.5°至19.5°的范围内具有特征衍射峰1，所述添加剂包含锰元素。
  2. 根据权利要求1所述的电化学装置，其中所述正极活性材料包括锰酸锂。
  3. 根据权利要求2所述的电化学装置，当所述电化学装置在满放状态下，所述正极极片的X射线衍射图谱在衍射角2θ为17.5°至19.5°的范围内还具有特征衍射峰2。
  4. 根据权利要求3所述的电化学装置，所述特征衍射峰2和所述特征衍射峰1的峰位差Δθ1满足0.33°≤Δθ1≤0.53°。
  5. 根据权利要求1所述的电化学装置，其中所述正极活性材料包括磷酸铁锂。
  6. 根据权利要求5所述的电化学装置，当所述电化学装置在满放状态下，所述正极极片的X射线衍射图谱在衍射角2θ为19.8°至21.8°的范围内具有特征衍射峰3。
  7. 根据权利要求6所述的电化学装置，所述特征衍射峰3和所述特征衍射峰1的峰位差Δθ2满足2°≤Δθ2≤3°。
  8. 根据权利要求1所述的电化学装置，其中基于所述正极活性材料的质量，所述添加剂的质量百分比为3％至20％，优选地，所述添加剂的质量百分比为3％至15％。
  9. 根据权利要求1所述的电化学装置，其中所述正极活性层包含元素M，所述元素M包含Al、Nb、Mg、Ti、Ce、W、Ga、Zr、W、Y、V、Na、Sr、Mo、Cr、Sn或La中的至少一种，基于所述正极活性层的质量，所述元素M的质量百分比为0.03％至3.5％，优选地，所述元素M的质量百分比为0.3％至1.5％。
  10. 根据权利要求1所述的电化学装置，其中所述电解液包含电解液添加剂，所述电解液添加剂包括硫氧双键化合物、碳酸亚乙烯酯或氟代碳酸乙烯酯中的至少一种，基于所述电解液的质量，所述电解液添加剂的质量百分比为0.001％至10％，优选地，所述电解液添加剂的质量百分比为0.01％至5％。
  11. 根据权利要求1所述的电化学装置，其中所述正极活性层包含铝元素，基于所述正极活性层的质量，所述铝元素的质量百分比为C(％)，所述电解液中的碳酸亚乙烯酯的质量 百分比为D％，C/D满足0.03≤C/D≤0.5。
  12. 根据权利要求1所述的电化学装置，其中所述添加剂满足如下至少一者：
    (1)所述添加剂的平均粒径为F，F的范围为5μm至40μm；
    (2)所述添加剂颗粒的表面具有宽度为1nm至1000nm的台阶。
  13. 一种电子装置，其包括根据权利要求1-12中任一项所述的电化学装置。
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JP2002167220A (ja) * 2000-09-20 2002-06-11 Mitsubishi Chemicals Corp リチウムマンガン複合酸化物、リチウム二次電池用正極材料、リチウム二次電池用正極、リチウム二次電池及びリチウムマンガン複合酸化物の製造方法
CN102130331A (zh) * 2011-01-26 2011-07-20 郭兆靖 一种锂电池的改性方法
CN102376948A (zh) * 2010-08-06 2012-03-14 株式会社日立制作所 锂二次电池用正极材料，锂二次电池及采用它的二次电池模块
JP2017168255A (ja) * 2016-03-15 2017-09-21 株式会社東芝 非水電解質二次電池、電池パック及び車両

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JP2002068747A (ja) * 2000-09-04 2002-03-08 Mitsubishi Chemicals Corp リチウムマンガン複合酸化物、リチウム二次電池用正極材料、正極、及びリチウム二次電池
JP2002167220A (ja) * 2000-09-20 2002-06-11 Mitsubishi Chemicals Corp リチウムマンガン複合酸化物、リチウム二次電池用正極材料、リチウム二次電池用正極、リチウム二次電池及びリチウムマンガン複合酸化物の製造方法
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JP2017168255A (ja) * 2016-03-15 2017-09-21 株式会社東芝 非水電解質二次電池、電池パック及び車両

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