CN107528059A - Positive electrode active materials of Phosphate coating spinel structure and its preparation method and application - Google Patents

Positive electrode active materials of Phosphate coating spinel structure and its preparation method and application Download PDF

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CN107528059A
CN107528059A CN201710778059.7A CN201710778059A CN107528059A CN 107528059 A CN107528059 A CN 107528059A CN 201710778059 A CN201710778059 A CN 201710778059A CN 107528059 A CN107528059 A CN 107528059A
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lithium
positive electrode
electrode active
active materials
containing compound
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CN107528059B (en
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武怿达
起文斌
黄学杰
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Institute of Physics of CAS
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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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • 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
    • H01M4/131—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
    • H01M4/36—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
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • 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
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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Abstract

The present invention provides a kind of positive electrode active materials of Phosphate coating spinel structure, wherein, it is LiMn that the positive electrode active materials, which include the chemical formula with spinel structure,2‑xAxOyLithium-containing compound particle and be coated on the Phosphate coating layer on its surface, chemical formula LiMn2‑xAxOyIn, one or more of the A in Ni, Fe, Co, Ti, Y, Sc, Ru, Cu, Mo, Ge, W, Zr, Ca and Sr, 0≤x≤0.7, and 3.8≤y≤4.2；And wherein, the lithium-containing compound particle has a transition zone, the transition zone contains by being coated with and its rear optional calcining diffuses into the diffusion element in the lithium-containing compound particle.Purposes present invention also offers the preparation method of the positive electrode active materials and in lithium rechargeable battery.When the positive electrode active materials are used for lithium rechargeable battery, there is the stable circulation performance improved and coulombic efficiency.

Description

Positive electrode active materials of Phosphate coating spinel structure and its preparation method and application
Technical field
The present invention relates to a kind of positive electrode active materials of Phosphate coating spinel structure and its production and use.
Background technology
Lithium rechargeable battery has that operating voltage is high, in light weight, volume compared with others rechargeable battery system Small, memory-less effect, self-discharge rate are low, have extended cycle life, the advantages that energy density is high, are widely used to mobile phone, pen at present Remember the mobile terminal product such as this computer, tablet personal computer.In recent years, for the consideration in terms of environmental protection, electric automobile is each Obtained rapid development under the promotion of government of state and automaker, and lithium rechargeable battery by its excellent performance into For the ideal power source of New Generation of Electric Vehicle.At present, the positive electrode of lithium rechargeable battery of concern can substantially divide For three classes：With cobalt acid lithium (LiCoO2) be representative layered-type material, with LiFePO4 (LiFePO4) be representative olivine-type Material and with LiMn2O4 (LiMn2O4) be representative spinel structure material.In these materials, spinel structure material is because of it Raw material environmental protection, the advantages that cost is cheap, technique is simple, safe and forthright good again and be widely studied.Especially, there is point Nickel ion doped (the LiNi of spinel structure0.5Mn1.5O4) theoretical specific capacity be 146.7mAh/g, operating voltage 4.7V vs.Li/Li+, theoretical capacity density is the ideal material of following electric car lithium rechargeable battery up to 695Wh/kg.
However, for current spinel structure material, because traditional carbonates electrolyte can give birth under high pressure Into H2O is (even if the also inevitably H containing trace in fresh electrolyte2O), H2LiPF in O and electrolyte6Reaction life Into HF, HF can further corrode positive electrode surface, dissolve material surface, ultimately result in active material reduction.Together When, for such as nickel ion doped (LiNi0.5Mn1.5O4) positive electrode active materials, positive pole dissolving Mn ions can move to it is negative Pole, and in cathode deposition, promote the solid electrolyte interface film (SEI films) of negative terminal surface constantly to decompose, consume in battery system Active lithium, cause the decay of capacity.
In order to solve the above problems, there has been proposed various cladding schemes, wherein representational carried out using lithium phosphate Cladding, this is due to that lithium phosphate is high pressure resistant, can absorb hydrofluoric acid, and does not contain transition metal ions, and battery is made without secondary With.Wherein, method for coating commonly employed in the art includes：(1) by positive electrode to be covered and lithium phosphate solid phase mixing simultaneously Calcine so as to be coated；(2) lithium phosphate cladding is carried out to positive electrode to be covered using sol-gel method.However, For these methods, because the mismatch between lattice causes lithium phosphate to be difficult to be evenly distributed in positive electrode surface.
The content of the invention
It is therefore an object of the present invention to for the problems of prior art and deficiency, there is provided a kind of Phosphate coating Positive electrode active materials of spinel structure and its preparation method and application.
The above-mentioned purpose of the present invention is achieved through the following technical solutions.
On the one hand, the invention provides a kind of positive electrode active materials of Phosphate coating spinel structure, wherein, it is described just It is LiMn that pole active material, which includes the chemical formula with spinel structure,2-xAxOyLithium-containing compound particle and be coated on its table The Phosphate coating layer in face, chemical formula LiMn2-xAxOyIn, A is selected from Ni, Fe, Co, Ti, Y, Sc, Ru, Cu, Mo, Ge, W, Zr, Ca With the one or more in Sr, 0≤x≤0.7, and 3.8≤y≤4.2；And wherein, the lithium-containing compound particle had Cross layer, the transition zone, which contains, to be coated with by coating such as hydro-thermal method and its rear optional calcining diffuses into described contain Diffusion element in lithium compound particle.
The present inventor has found unexpectedly, using hydro-thermal method to spinel structure particle (lithium-containing compound Grain) coated phosphate when, the transition metal (diffusion element) contained in phosphate or its presoma and cladding solution is such as Fe, Co or Mn can diffuse into the inside of particle at high temperature under high pressure, so as to form transition zone in spinel structure particle.So Transition zone be advantageous to form firm structure between clad and the intragranular active material of spinel structure.
Further, present inventor has further discovered that, forged under certain condition when to positive-active of the invention When burning (heat treatment), at least part transition metal in the phosphate containing transition metal can diffuse into spinelle In structure particles, and at least part clad is changed into the lithium phosphate of the even compact without transition metal.
According to positive electrode active materials provided by the invention, wherein, chemical formula LiMn2-xAxOyMiddle A represents doped chemical.This hair In bright, doped chemical is used to replace transition metal Mn.In some embodiments, doped chemical A can be by formula ∑ wiAiTable Show, wiIt is AiAtomic percentage in whole doped chemical A, ∑ wi=1, wherein, 1≤i≤16, preferably 1≤i≤5, with And more preferably 1≤i≤3.
In some embodiments, chemical formula LiMn2-xAxOyMiddle A is selected from Co and Ni.
According to positive electrode active materials provided by the invention, wherein, chemical formula LiMn2-xAxOyIn, 0≤x≤0.5.At some X is 0 in embodiment, and 0.1≤x≤0.5 in some embodiments.
In some preferred embodiments, chemical formula can be used as LiMn2OyUndoped with lithium-containing compound particle. In some specific embodiments, the chemical formula of the lithium-containing compound particle is LiMn2O4。
According to positive electrode active materials provided by the invention, wherein, the lithium-containing compound particle chemical formula is LiMn2- xAxO4, 0.1≤x≤0.5.In some specific embodiments, the chemical formula of lithium-containing compound particle is LiNi0.5Mn1.5O4。
According to positive electrode active materials provided by the invention, wherein, the particle diameter of the lithium-containing compound particle is from low side point Value 0.1 μm (200nm), 0.2 μm (200nm) or 0.5 μm (500nm) paramount endpoint value 0.5 μm (500nm), 10 μm, 20 μm or 30 μm.In some embodiments, the particle diameter of the lithium-containing compound particle is 0.1~30 μm.In some preferred embodiments, The particle diameter of the lithium-containing compound particle is 0.1~10 μm, is in some preferred embodiments 0.2 μm~10 μm, Yi Ji It is 0.2~0.5 μm in certain preferred embodiments.
According to positive electrode active materials provided by the invention, wherein, the phosphate is selected from lithium phosphate and containing diffusion element Phosphoric acid lithium salts.In some specific embodiments, the phosphate is selected from LiCoPO4、LiFePO4、LiMnPO4And Li3PO4In One or more.
According to positive electrode active materials provided by the invention, wherein, the thickness of the Phosphate coating layer is 1~50nm, excellent Elect 5~15nm as.
According to positive electrode active materials provided by the invention, wherein, the Phosphate coating layer is in the lithium-containing compound The coverage on grain surface is 1~100%.In some embodiments, the Phosphate coating layer is in the lithium-containing compound Grain surface coverage be from low side point value 10%, 20%, 30%, 40%, 50% or 60% to high endpoint value 50%, 60%, 70%th, 80% or 90%.For example, in some preferred embodiments, the Phosphate coating layer is in the lithium-containing compound Grain surface coverage be 20~90%, and certain preferred embodiments be 60~80%.
According to positive electrode active materials provided by the invention, wherein, the Phosphate coating layer can be by the phosphate of individual layer Particle forms.In some specific embodiments, the particle diameter of the phosphate particle is 1~50nm, and specific real at some Apply in scheme is 5~20nm.
According to positive electrode active materials provided by the invention, wherein, the diffusion element can be with chemical formula LiMn2-xAxOyIn Metallic element in addition to lithium is identical or different.As described above, in some embodiments, the diffusion element is selected from One or more in Fe, Co and Mn.
In some preferred embodiments, one or more of the diffusion element in Fe, Co and Mn, it is described to contain lithium The chemical formula of compound particle is LiMn2Oy.In this case, doped chemical is free of in lithium-containing compound particle.
In other preferred embodiment, the diffusion element is Fe and/or Co, and the diffusion element is with changing Formula LiMn2-xAxOyIn metallic element (doped chemical A) in addition to lithium it is different, and in other preferred embodiment In, one or more of the diffusion element in Fe, Co and Mn, and the diffusion element and chemical formula LiMn2-xAxOy In metallic element in addition to lithium it is identical.
In some specific embodiments, the phosphate is substantially Li3PO4, it is described diffusion element be selected from Fe, Co and One or more in Mn, and in other specific embodiment, the phosphate is substantially LiFePO4Or LiMnPO4, the diffusion element is corresponding transition metal Fe or Mn in the phosphate.
According to positive electrode active materials provided by the invention, wherein, the thickness of the transition zone is 0~15 μm.
In some embodiments, the thickness of the transition zone is 0.1~5 μm, and is 100 in some embodiments ~250nm.In other embodiments, transition zone is distributed in 0~10nm of surface apart from the lithium-containing compound particle Between, and in some embodiments, transition zone is distributed between 0~5nm of surface of the lithium-containing compound particle.
According to positive electrode active materials provided by the invention, wherein, the amount of the diffusion element and the phosphatic material Than for more than 0 to less than or equal to 1.In some embodiments, the amount ratio of the diffusion element and the phosphatic material is 0.5~1.
According to positive electrode active materials provided by the invention, wherein, Phosphate coating layer and transition zone can be with this areas Any method measure known.For example, Phosphate coating layer can be determined by X-ray diffraction spectrum and x-ray photoelectron power spectrum Type, the distribution of each element and content in measurement transition zone are swept using the X-ray energy spectral line of spherical aberration correction transmission electron microscope.
On the other hand, the invention provides the preparation method of above-mentioned positive electrode active materials, the preparation method to include：
(1) phosphoric acid or its ammonium salt solution, the precursor salt solution of diffusion element and lithium precursor solution are added dropwise to containing lithiumation In the dispersion of polymer beads, it is stirred, obtains mixture；
(2) mixture obtained in step (1) is transferred in closed reactor, the hydro-thermal reaction at 120~250 DEG C 0.1~20 hour；
(3) material that hydro-thermal reaction obtains in step (2) is cooled to room temperature, with water and ethanol centrifuge clearly respectively Wash；With
(4) material after the cleaning that will be obtained in step (3) is dried 3~6 hours at 80~150 DEG C, obtains positive pole work Property material.
According to preparation method provided by the invention, wherein, in step (1) ammonium salt of phosphoric acid can be ammonium dihydrogen phosphate and/ Or diammonium hydrogen phosphate.
According to preparation method provided by the invention, wherein, the precursor salt that element is spread described in step (1) is selected from sulfuric acid Asia One or more in iron, cobaltous sulfate, manganese sulfate, cobalt nitrate, manganese nitrate, manganese chloride, cobalt chloride and frerrous chloride.
According to preparation method provided by the invention, wherein, lithium presoma described in step (1) is lithium hydroxide.
According to preparation method provided by the invention, wherein, solvent described in step (1) is water and/or ethanol.
According to preparation method provided by the invention, wherein, the solvent of the dispersion of the lithium-containing compound particle is water And/or ethanol.
According to preparation method provided by the invention, wherein, phosphoric acid or its ammonium salt, the precursor salt for spreading element in step (1) With lithium presoma added according to following ratio：The mol ratio of phosphorus, diffusion element and lithium is 1：0.5~2：0.5~6.One In a little embodiments, phosphoric acid or its ammonium salt, the precursor salt of diffusion element and lithium presoma are added according to following ratio in step (1) Add：The mol ratio of phosphorus, diffusion element and lithium is 1：0.5~1：3~6.
According to preparation method provided by the invention, wherein, the concentration of phosphoric acid or its ammonium salt solution is in step (1) 0.1mol/L~0.3mol/L.
According to preparation method provided by the invention, wherein, the concentration of the precursor salt solution of diffusion element is in step (1) 0.1mol/L~0.3mol/L.
According to preparation method provided by the invention, wherein, in step (1) concentration of lithium precursor solution be 0.3mol/L~ 1.8mol/L, preferably 0.3mol/L~0.9mol/L.
According to preparation method provided by the invention, wherein, contain lithium in step (1) in the dispersion of lithium-containing compound particle The mass fraction of compound particle is the weight % of 30 weight %~50.
According to preparation method provided by the invention, wherein, phosphoric acid or its ammonium salt, the precursor salt for spreading element in step (1) Can arbitrarily it be adjusted with the dropwise addition order of lithium presoma.
According to preparation method provided by the invention, wherein, the temperature of hydro-thermal reaction is 150~200 DEG C in step (2), excellent Elect 180 DEG C as.
According to preparation method provided by the invention, wherein, the time of hydro-thermal reaction is 5~15 hours in step (2), preferably For 10 hours.
According to preparation method provided by the invention, wherein, the preparation method also includes：
(5) positive electrode active materials obtained in step (4) are calcined 0.1~10 hour at 350~900 DEG C, so as to Positive electrode active materials after to sintering.
According to preparation method provided by the invention, wherein, the temperature of calcining is 450~700 DEG C in step (5).
According to preparation method provided by the invention, wherein, the time of calcining is 1~5 hour in step (5), and preferably 3 is small When.
According to preparation method provided by the invention, wherein, calcining is in oxygen, air, containing reduction described in step (5) The atmosphere or inert atmosphere of gas such as hydrogen under nitrogen or argon gas as carried out.
Another aspect, the invention provides the positive electrode active materials as made from above-mentioned preparation method.
Another aspect, the invention provides the positive electrode active materials lithium rechargeable battery purposes.
Further, the invention provides a kind of lithium ion secondary battery positive electrode, the positive pole to include collector and load Positive electrode active materials on a current collector, wherein, the positive electrode active materials be positive electrode active materials provided by the invention or According to positive electrode active materials made from the inventive method.
According to lithium ion secondary battery positive electrode provided by the invention, wherein, the positive pole also includes conductive additive and glued Tie agent.
According to lithium ion secondary battery positive electrode provided by the invention, wherein, the conductive additive can be in this area It is not particularly limited by conventional electric additive, the present invention.In some embodiments, the conductive additive is carbon black.
According to lithium ion secondary battery positive electrode provided by the invention, wherein, described adhesive can be conventional in this area Adhesive, the present invention it is not particularly limited.In some embodiments, described adhesive is polyvinylidene fluoride (PVDF)。
Further, present invention also offers a kind of lithium rechargeable battery, the battery include positive pole, negative pole, barrier film and Electrolyte, wherein, the positive pole is positive pole provided by the invention.
According to lithium rechargeable battery provided by the invention, wherein, the battery also includes housing, and wherein, positive pole, Negative pole, barrier film (being referred to as electrode group) and electrolyte are sealed in housing.
According to lithium metal secondary battery provided by the invention, wherein, the negative pole, barrier film and electrolyte can use ability They are not particularly limited by conventional negative pole, barrier film and electrolyte material in domain, the present invention.In some embodiments, bear Extremely lithium metal；In some embodiments, barrier film is the trilamellar membrane for the PP/PE/PP that dual coating has aluminum oxide；And one In a little embodiments, electrolyte is LiPF6Concentration be 1mol/L ethylene carbonate (EC)/dimethyl carbonate (DMC) it is non-aqueous It is electrolyte, wherein, EC and DMC volume ratio are 1：1.
Positive electrode active materials provided by the invention, the positive electrode and electricity of spinel structure are significantly reduced by cladding The reactivity between liquid is solved, stabilizes the surface texture of the positive electrode active materials of spinel structure, it is suppressed that in HTHP Under the conditions of in cyclic process the surface of positive electrode active material of spinel structure manganese dissolving, so as to improve its capability retention and Discharge and recharge coulombic efficiency.
Positive electrode active materials provided by the invention can be used as the positive electrode active materials of lithium rechargeable battery, be done by the material Into battery there is excellent cycle performance.
The preparation method of positive electrode active materials provided by the invention, hence it is evident that improve the cyclical stability of positive electrode active materials Energy and coulombic efficiency.Bound by theory is not intended to think, by method provided by the invention, below Phosphate coating layer, Transition zone is formd in lithium-containing compound particle with spinel structure, so that cladding more firmly uniform densification.This Kind cladding at least partly inhibits corrosion of the electrolyte to positive electrode active materials, so as to reduce the capacity attenuation of material.Comprising this The lithium rechargeable battery of the positive electrode active materials of invention can be used as electric tool, electric bicycle, hybrid electric traffic The energy source of the application such as instrument and pure electric vehicle.
Brief description of the drawings
Hereinafter, embodiment of the present invention is described in detail with reference to accompanying drawing, wherein：
Fig. 1 is LiMn2O4With embodiment 1 made from positive electrode active materials sweep collection of illustrative plates soon in 10~80 ° of XRD；
Fig. 2 is LiMn2O4With embodiment 1 made from positive electrode active materials sweep collection of illustrative plates slowly in 20~35 ° of XRD；
Fig. 3 is content distribution of surface of positive electrode active material Mn, P, Fe and O elements in different depth made from embodiment 1 Figure；
Fig. 4 is Li3PO4And the XPS collection of illustrative plates of surface of positive electrode active material P elements made from embodiment 1 and embodiment 3；
Fig. 5 is LiMn2O4And the XPS collection of illustrative plates of surface of positive electrode active material ferro element made from embodiment 1 and embodiment 3；
Fig. 6 is that the SEM of positive electrode active materials made from embodiment 1 schemes；
Fig. 7 is that the SEM of positive electrode active materials made from embodiment 2 schemes；
Fig. 8 is the SEM figures of positive electrode active materials prepared by embodiment 5；
Fig. 9 is the SEM figures of positive electrode active materials prepared by embodiment 6；
Figure 10 is using LiMn2O4It is bent with the charge and discharge cycles of the lithium rechargeable battery of the positive electrode active materials of embodiment 3 Line；
Figure 11 is using LiMn2O4It is bent with the coulombic efficiency of the lithium rechargeable battery of the positive electrode active materials of embodiment 3 Line；
Figure 12 is using LiNi0.5Mn1.5O4With the discharge and recharge of the lithium rechargeable battery of the positive electrode active materials of embodiment 6 Cyclic curve；
Figure 13 is using LiNi0.5Mn1.5O4Imitated with the coulomb of the lithium rechargeable battery of the positive electrode active materials of embodiment 6 Rate curve.
Embodiment
The present invention is further described in detail with reference to embodiment, the embodiment provided is only for explaining The bright present invention, the scope being not intended to be limiting of the invention.
X-ray diffraction (XRD)
The D8X x ray diffractometer xs produced using German Brooker company (Bruker) are analyzed material, and this X ray spreads out Penetrate instrument equipment LYNXEYE_XE detectors, the voltage and operating current of X-ray tube are 40kV and 40mA respectively, the X ray given off It is Cu KαRay (wavelength ), wherein, scanning step is 0.02 °, sweeps the speed of collection of illustrative plates soon often to walk 0.3 second, The slow speed for sweeping spectrogram is often step 3 seconds.
SEM (SEM)
Ground using the model S4800 of Japanese Hitachi (Hitachi, Ltd) productions field emission scanning electron microscope Study carefully the microscopic appearance of sample.
Spherical aberration correction electron microscope (STEM)
Using 2100F spherical aberrations correction-scanning transmission electron microscope of Japanese JEOL companies production come the original of study sample The microscopic appearance of sub- yardstick and the content distribution of surface-element.
X-ray photoelectron power spectrum (XPS)
Powder is studied using the x-ray photoelectron spectroscopy of the ESCALAB 250 models number of Thermo Fisher companies production The species and chemical environment of last sample surfaces element, wherein, x-ray radiation source is Mg K α.
Inductively Coupled Plasma Atomic Emission Spectrometry (ICP)
The iCAP produced using Thermo Fisher companiesTM7200 ICP-OES plasma spectrometers determine powder The content of different elements in sample.
Embodiment 1
By 10.52g LiMn2O4Material (particle diameter 200nm) is added in 20ml water and is stirred continuously, so as to obtain LiMn2O4Dispersion.FeSO by 10ml concentration for 0.2mol/L respectively4The aqueous solution, 10ml concentration are 0.2mol/L's NH4H2PO4The aqueous solution and the LiOH aqueous solution that 10ml concentration is 0.6mol/L are added in above-mentioned dispersion, and are stirred continuously. Obtained mixture is transferred in 100ml ptfe autoclaves, 10 hours are incubated at 180 DEG C.Reaction is received after terminating Collect the powder in product, with water eccentric cleaning 3 times, then with absolute ethyl alcohol eccentric cleaning once, it is small that 3 are dried at 80 DEG C When, obtain positive electrode active materials.
Fig. 1 shows LiMn2O4With embodiment 1 made from positive electrode active materials sweep collection of illustrative plates soon in 10~80 ° of XRD.From figure 1 as can be seen that LiMn2O4Almost there is no difference with the XRD spectrum of the positive electrode active materials of embodiment 1, both there is cube point Spinel structure.
Fig. 2 shows LiMn2O4With embodiment 1 made from positive electrode active materials sweep collection of illustrative plates slowly in 20~35 ° of XRD.From figure 2 as can be seen that there is lithium phosphate peak between 20~35 ° in positive electrode active materials made from embodiment 1.
Fig. 1 and Fig. 2 show, LiMn after being coated by hydro-thermal method2O4The main crystal structure of material does not change, But form lithium phosphate.
Fig. 3 shows surface of positive electrode active material spherical aberration correction electron microscope linear sweep graph made from embodiment 1.From Fig. 3 It can obtain, for embodiment 1, P is distributed in 0~5nm layers of material most surface, and higher closer to surface concentrations, iron point Cloth subsurface 5~15nm layers, it is and higher closer to surface concentrations.
Fig. 4 shows the XPS collection of illustrative plates of surface of positive electrode active material P elements made from lithium phosphate and embodiment 1.With reference to figure 1st, 2 and 4, show after being coated by hydro-thermal method, lithium phosphate is formd on the surface of positive electrode active materials.
Fig. 5 shows LiMn2O4With embodiment 1 made from surface of positive electrode active material ferro element XPS collection of illustrative plates.As a result show Show, after hydro-thermal reaction, surface observation has arrived Fe signal, LiMn2O4In ferro element come from cladding during add FeSO4。
Fig. 6 shows the representational SEM figures of positive electrode active materials prepared by embodiment 1.SEM characterization results are shown, are led to Cross addition FeSO4, in LiMn2O4Material surface equably covers one layer of 5nm or so particle, and coverage is about 80%.Together When, the information of Fig. 1~6 shows that this layer of 5nm or so particle is lithium phosphate.
Therefore, the surface of positive electrode active materials prepared by embodiment 1 has lithium phosphate clad, in LiMn2O4Particle surface There is the transition zone for including ferro element (spreading element), and LiMn at 0~10nm below2O4Particle still has cube point brilliant Stone structure.
Embodiment 2
By 10.52g LiMn2O4Material (particle diameter 200nm) is added in 20ml water and is stirred continuously, so as to obtain LiMn2O4Dispersion.NH by 10ml concentration for 0.2mol/L respectively4H2PO4The aqueous solution and 10ml concentration are 0.6mol/L's The LiOH aqueous solution is added in above-mentioned dispersion, and is stirred continuously.It is anti-that obtained mixture is transferred to 100ml polytetrafluoroethylene (PTFE) Answer in kettle, 10 hours are incubated at 180 DEG C.The powder in product is collected in reaction after terminating, with water eccentric cleaning 3 times, then With absolute ethyl alcohol eccentric cleaning once, dried 3 hours at 80 DEG C, obtain lithium phosphate and LiMn2O4Mixture.
Fig. 7 shows the representational SEM figures of positive electrode prepared by embodiment 2.From figure 7 it can be seen that it is being added without FeSO4In the case of, LiMn2O4Material surface is smooth.But swept soon with reference to XRD and sweep test slowly and found, in LiMn2O4Particle with 50nm or so lithium phosphate particle, and the skewness of lithium phosphate are observed between particle.By can compared with embodiment 1 To find, by adding FeSO in being coated in hydro-thermal method4, can be below lithium phosphate clad, LiMn2O4Formed in particle Layer is crossed, and transition zone is advantageous to lithium phosphate clad in LiMn2O4Particle surface uniformly coats.
Embodiment 3
By 10.52g LiMn2O4Material (particle diameter 200nm) is added in 20ml water and is stirred continuously, so as to obtain LiMn2O4Dispersion.FeSO by 10ml concentration for 0.2mol/L respectively4The aqueous solution, 10ml concentration are 0.2mol/L's NH4H2PO4The aqueous solution and the LiOH aqueous solution that 10ml concentration is 0.6mol/L are added in above-mentioned dispersion, and are stirred continuously.Will Obtained mixture is transferred in 100ml ptfe autoclaves, and 10 hours are incubated at 180 DEG C.Reaction is collected after terminating Powder in product, with water eccentric cleaning 3 times, then with absolute ethyl alcohol eccentric cleaning once, dried 3 hours in 80 DEG C.Will Dry powder is calcined 3 hours for 450 DEG C in atmosphere, obtains positive electrode active materials.
The XRD of embodiment 3 sweeps collection of illustrative plates and sweeps collection of illustrative plates slowly soon to be shown, after being calcined in hydro-thermal method cladding and air LiMn2O4The main crystal structure of particle does not change, but forms lithium phosphate.
Fig. 4 also show the XPS collection of illustrative plates of surface of positive electrode active material P elements made from embodiment 3.Fig. 4 explanations pass through water After hot method cladding, LiMn2O4Material surface forms lithium phosphate.
Fig. 5 also show the XPS collection of illustrative plates of surface of positive electrode active material ferro element made from embodiment 3.As a result show, pass through After hydro-thermal reaction, surface observation has arrived Fe signal, LiMn2O4Ferro element in material adds during coming from cladding FeSO4。
Reference picture 5, by embodiment 1 and embodiment 3 are compared it can be found that by the later stage forging at 450 DEG C Burn, material surface ferro element that XPS is measured letter weakens, but measures ferro element containing in embodiment 1 and embodiment 3 using ICP Measure constant.This shows that ferro element in calcination process in transition zone to particle diffusion inside, therefore deduces that cladding process In the genesis analysis of element spread in caused transition zone influenceed by later stage calcining heat.
The SEM figures of positive electrode prepared by embodiment 3 show, LiMn2O4Surface uniformly covers one layer of 5nm's or so Particle, coverage are about 80%.
The surface of positive electrode active materials prepared by embodiment 3 has lithium phosphate clad, in LiMn2O4Below particle surface With the transition zone comprising ferro element, and LiMn2O4Particle still has cubic spinel structure.
Embodiment 4
By 10.52g LiMn2O4Material (particle diameter 200nm) is added in 20ml water and is stirred continuously, so as to obtain LiMn2O4Dispersion.Successively respectively by 10ml concentration be 0.2mol/L MnSO4The aqueous solution, 10ml concentration are 0.2mol/L's NH4H2PO4The aqueous solution and the LiOH aqueous solution that 10ml concentration is 0.6mol/L are added in above-mentioned dispersion, and are stirred continuously.Will Obtained mixture is transferred in 100ml ptfe autoclaves, and 10 hours are incubated at 180 DEG C.Reaction is collected after terminating Powder in product, with water eccentric cleaning 3 times, then with absolute ethyl alcohol eccentric cleaning once, dried 3 hours at 80 DEG C, Obtain positive electrode active materials.
The XRD of embodiment 4 sweeps collection of illustrative plates and sweeps collection of illustrative plates slowly soon to be shown, LiMn after being coated by hydro-thermal method2O4The main body of particle Crystal structure does not change, but forms lithium manganese phosphate on surface.
The surface of positive electrode active material spherical aberration correction electron microscope linear sweep graph of embodiment 4 shows that P is distributed in material most table 0~5nm layers in face, and it is higher closer to surface concentrations.In 5~10nm layers of subsurface, the content of manganese apparently higher than its His region, and it is higher closer to surface concentrations.
The SEM figures of positive electrode active materials prepared by embodiment 4 show, LiMn2O4Material surface equably covers one layer 5nm or so particle, coverage are about 70%.
The surface of positive electrode active materials prepared by embodiment 4 has lithium manganese phosphate clad, in LiMn2O4Particle surface with There is the transition zone rich in Mn elements, and LiMn at lower 0~5nm2O4Particle still has cubic spinel structure.
Embodiment 5
By 9.14g LiNi0.5Mn1.5O4Material (particle diameter 500nm) is added in 20ml water and is stirred continuously, so as to To LiNi0.5Mn1.5O4Dispersion.CoSO by 10ml concentration for 0.1mol/L respectively4The aqueous solution, 10ml concentration are 0.1mol/ L NH4H2PO4The aqueous solution and the LiOH aqueous solution that 10ml concentration is 0.3mol/L are added in above-mentioned dispersion, and are constantly stirred Mix.Obtained mixture is transferred in 100ml ptfe autoclaves, 10 hours are incubated at 180 DEG C.After reaction terminates The powder in product is collected, with water eccentric cleaning 3 times, then with absolute ethyl alcohol eccentric cleaning once, it is small that 3 are dried at 80 DEG C When, obtain positive electrode active materials.
Fig. 8 is the representational SEM figures of positive electrode active materials prepared by embodiment 5.Characterized from SEM as can be seen that preparing Surface of positive electrode active material equably cover particle of the one layer of size for 10nm or so, coverage 70%.
In addition, further characterized using characterization method same as Example 1.As a result show, prepared by embodiment 5 The surface of positive electrode active materials has lithium phosphate clad, in LiNi0.5Mn1.5O4There is bag below particle surface at 0~10nm Transition zone containing cobalt element, and LiNi0.5Mn1.5O4Particle still has cubic spinel structure.
Embodiment 6
By 9.14g LiNi0.5Mn1.5O4Material (particle diameter 500nm) is added in 20ml water and is stirred continuously, so as to To LiNi0.5Mn1.5O4Dispersion.CoSO by 10ml concentration for 0.1mol/L respectively4The aqueous solution, 10ml concentration are 0.1mol/ L NH4H2PO4The aqueous solution and the LiOH aqueous solution that 10ml concentration is 0.3mol/L are added in above-mentioned dispersion, and are constantly stirred Mix.Obtained mixture is transferred in 100ml ptfe autoclaves, 10 hours are incubated at 180 DEG C.After reaction terminates The powder in product is collected, with water eccentric cleaning 3 times, then with absolute ethyl alcohol eccentric cleaning once, it is small that 3 are dried at 80 DEG C When.Positive electrode active materials are obtained after dry powder is heated 3 hours at 550 DEG C in atmosphere.
Fig. 9 is the representational SEM figures of positive electrode prepared by embodiment 6.It can be seen from SEM signs LiNi0.5Mn1.5O4Material surface equably covers lithium phosphate particle of the one layer of size for 12nm or so, and coverage is about 60%
Further characterized using characterization method same as Example 1, as a result shown, positive pole prepared by embodiment 6 The surface of active material has lithium phosphate clad, in LiNi0.5Mn1.5O4There is the transition comprising cobalt element below particle surface Layer, and LiNi0.5Mn1.5O4Particle still has cubic spinel structure.Particularly, the calcining by the later stage at 550 DEG C, The material surface cobalt element letter that XPS is measured weakens, but measures content of the cobalt element in embodiment 5 and embodiment 6 not using ICP Become.This shows cobalt element in calcination process in transition zone to particle diffusion inside, therefore deduces that and produces during cladding The genesis analysis of element is spread in raw transition zone to be influenceed by later stage calcining heat.
Embodiment 7
By 9.14g LiNi0.5Mn1.5O4Material (particle diameter 500nm) is added in 20ml water and is stirred continuously, so as to To LiNi0.5Mn1.5O4Dispersion.CoSO by 10ml concentration for 0.1mol/L respectively4The aqueous solution, 10ml concentration are 0.1mol/ L NH4H2PO4The aqueous solution and the LiOH aqueous solution that 10ml concentration is 0.3mol/L are added in above-mentioned dispersion, and are constantly stirred Mix.Obtained mixture is transferred in 100ml ptfe autoclaves, 10 hours are incubated at 180 DEG C.After reaction terminates The powder in product is collected, with water eccentric cleaning 3 times, then with absolute ethyl alcohol eccentric cleaning once, it is small that 3 are dried at 80 DEG C When.Positive electrode active materials are obtained after dry powder is heated 3 hours at 700 DEG C in atmosphere.
Characterized using characterization method same as Example 1, as a result shown, positive-active material prepared by embodiment 7 Material uniformly covers lithium phosphate particle of the one layer of size for 15nm or so, coverage 30%, LiNi0.5Mn1.5O4There is the transition zone comprising cobalt element, and LiNi below particle surface0.5Mn1.5O4Particle still have cube Spinel structure.Particularly, the calcining by the later stage at 700 DEG C, the material surface cobalt element letter that XPS is measured weakens, but profit It is constant that content of the cobalt element in embodiment 5 and embodiment 7 is measured with ICP.This shows the cobalt in transition zone in heating process Element to particle diffusion inside, therefore deduce that spread in caused transition zone during cladding the genesis analysis of element by The influence of later stage calcining heat.
Embodiment 8
By 16.085g LiNi0.5Mn1.5O4Material (particle diameter 500nm) is added in 20ml water and is stirred continuously, so as to Obtain LiNi0.5Mn1.5O4Dispersion.CoSO by 10ml concentration for 0.15mol/L respectively4The aqueous solution, 10ml concentration are 0.3mol/L NH4H2PO4The aqueous solution and the LiOH aqueous solution that 10ml concentration is 0.9mol/L are added in above-mentioned dispersion, and It is stirred continuously.Obtained mixture is transferred in 100ml ptfe autoclaves, 10 hours are incubated at 180 DEG C.Reaction The powder in product is collected after end, with water eccentric cleaning 3 times, then with absolute ethyl alcohol eccentric cleaning once, at 80 DEG C Dry 3 hours.
Characterized using characterization method same as Example 1.As a result show, positive-active material prepared by embodiment 8 Material uniformly covers lithium phosphate particle of the one layer of size for 5nm or so, coverage 70%, in LiNi0.5Mn1.5O4 There is the transition zone comprising cobalt element, and LiNi below particle surface at 0~10nm0.5Mn1.5O4Particle still has cube point Spinel structure.
Embodiment 9
By 16.085g LiNi0.5Mn1.5O4Material (particle diameter 500nm) is added in 20ml water and is stirred continuously, so as to Obtain LiNi0.5Mn1.5O4Dispersion.Successively respectively by 10ml concentration be 0.3mol/L CoSO4The aqueous solution, 10ml concentration are 0.3mol/L NH4H2PO4The aqueous solution and the LiOH aqueous solution that 10ml concentration is 1.8mol/L are added in above-mentioned dispersion, and It is stirred continuously.Obtained mixture is transferred in 100ml ptfe autoclaves, 10 hours are incubated at 180 DEG C.Reaction The powder in product is collected after end, with water eccentric cleaning 3 times, then with absolute ethyl alcohol eccentric cleaning once, at 80 DEG C Dry 3 hours.
Characterized using characterization method same as Example 1, as a result shown, positive-active material prepared by embodiment 9 Material uniformly covers lithium phosphate particle of the one layer of size for 5nm or so, coverage 73%, in LiNi0.5Mn1.5O4 There is the transition zone comprising cobalt element, and LiNi below particle surface at 0~10nm0.5Mn1.5O4Particle still has cube point Spinel structure.
Performance test
The positive electrode active materials prepared in embodiment are assembled into button cell according to the steps.
(1) anode pole piece is prepared
The positive electrode active materials prepared in embodiment, carbon black are made as conductive additive and polyvinylidene fluoride (PVDF) For binding agent, according to weight than 80:10:10 are scattered in 1-METHYLPYRROLIDONE (NMP), are well mixed, and are prepared into uniform Anode sizing agent.Uniform anode sizing agent is coated uniformly in the aluminum foil current collector that thickness is 15 μm, dried at 55 DEG C, formed Thickness is 100 μm of pole piece, and pole piece is placed in into roll-in under roll squeezer, and (pressure is about 1MPa × 1.5cm2), it is cut into a diameter of Disk, be subsequently placed in vacuum drying oven and dried 6 hours at 120 DEG C, after natural cooling, taking-up be placed in glove box As anode pole piece.
(2) lithium rechargeable battery is assembled
In the glove box full of inert atmosphere, the negative pole of battery, the PP/ of dual coating aluminum oxide are used as using lithium metal PE/PP trilamellar membrane is put between a positive electrode and a negative electrode as barrier film, and 1M LiPF are added dropwise6It is dissolved in EC/DMC (volume ratios 1：1) Non-aqueous electrolyte, using step (1) prepare anode pole piece as positive pole, be assembled into model CR2032 button cell.
The test of embodiment 1~5
(1) high temperature circulation：
After the button cell of preparation is stood into 10 hours under the conditions of room temperature (25 DEG C), surveyed using blue electric battery charging and discharging Try instrument and charge and discharge cycles test is carried out to the button cell of above-mentioned preparation.(25 DEG C) first at ambient temperature, with 0.1C times Rate circulate 1 week, then continued cycling through 4 weeks with 0.2C multiplying power, wherein, control battery charging/discharging voltage scope be 3V~ 4.3V.Then, button cell is transferred in 55 DEG C of hot environment, is continued cycling through 50 weeks with 0.2C multiplying power, controlled simultaneously The charging/discharging voltage scope of battery is still 3V~4.3V.
(2) room temperature cycles：
After the button cell of preparation is stood into 10 hours under the conditions of room temperature (25 DEG C), surveyed using blue electric battery charging and discharging Try instrument and charge and discharge cycles test is carried out to the button cell of above-mentioned preparation.(25 DEG C) first at ambient temperature, with 0.1C times Rate circulate 1 week, then continued cycling through 49 weeks with 0.2C multiplying power, wherein, control battery charging/discharging voltage scope be 3V~ 4.3V。
The test of embodiment 6~9
(1) high temperature circulation：
After the button cell of preparation is stood into 10 hours under the conditions of room temperature (25 DEG C), surveyed using blue electric battery charging and discharging Try instrument and charge and discharge cycles test is carried out to the button cell of above-mentioned preparation.(25 DEG C) first at ambient temperature, with 0.1C times Rate circulate 1 week, then continued cycling through 4 weeks with 0.2C multiplying power, wherein, control battery charging/discharging voltage scope be 3.5V~ 4.9V.Then, button cell is transferred in 55 DEG C of hot environment, is continued cycling through 50 weeks with 0.2C multiplying power, controlled simultaneously The charging/discharging voltage scope of battery is still 3.5V~4.9V.
(2) room temperature cycles：
After the button cell of preparation is stood into 10 hours under the conditions of room temperature (25 DEG C), surveyed using blue electric battery charging and discharging Try instrument and charge and discharge cycles test is carried out to the button cell of above-mentioned preparation.(25 DEG C) first at ambient temperature, with 0.1C times Rate circulate 1 week, then continued cycling through 49 weeks with 0.2C multiplying power, wherein, control battery charging/discharging voltage scope be 3.5V~ 4.9V。
Compareed with being used as using the material itself before cladding of the embodiment of the present invention, the section Example data measured are listed in table In 1.
The chemical property of the positive electrode of the various embodiments of the present invention of table 1.
Especially, Figure 10 is shown using LiMn2O4With the lithium rechargeable battery of the positive electrode active materials of embodiment 3 Charge and discharge cycles curve.As a result show, uncoated LiMn2O4The battery that material is assembled under 55 DEG C of high temperature test environment, Capacity after 50 weeks is 98.9mAh/g, and conservation rate is about 91.5%, and capacity attenuation is very fast, and this is due in high temperature side Under test ring border, electrolyte decomposition, and Mn dissolving aggravations, cause the capacity attenuation of material very fast；Coat LiMn2O4Material afterwards Under 55 DEG C of high temperature test environment, the capacity after 50 weeks is 104mAh/g, and conservation rate is about 93.1%, and this is due to Coated by lithium phosphate, hinder LiMn2O4Directly contacting between material and electrolyte, electrolyte decomposition and Mn dissolve to obtain Suppress, so that the cyclical stability of battery improves.
Figure 11 is using LiMn2O4It is bent with the coulombic efficiency of the lithium rechargeable battery of the positive electrode active materials of embodiment 3 Line.As a result show, uncoated LiMn2O4The battery being assembled into is flat after 50 weeks under 55 DEG C of high temperature test environment Equal coulombic efficiency is about 98.9%；Coat the LiMn after lithium phosphate2O4Under 55 DEG C of high temperature test environment, after 50 weeks Average coulombic efficiency be about 99.4%.It is probably to be coated by lithium phosphate the reason for coulombic efficiency difference occur, is hindered LiMn2O4Directly contacting between material and electrolyte, it is suppressed that the decomposition of electrolyte is so that the cyclical stability of battery carries It is high.
Figure 12 is using LiNi0.5Mn1.5O4With the lithium ion two of the positive electrode active materials of the positive electrode active materials of embodiment 6 The charge and discharge cycles curve of primary cell.As a result show, uncoated LiNi0.5Mn1.5O4High temperature of the battery being assembled at 55 DEG C Under test environment, the capacity after 50 weeks is 109.6mAh/g, and conservation rate is about 83.98%, and capacity attenuation is very fast, and this is Due under high temperature test environment, electrolyte decomposition and Mn dissolving aggravations, causing the capacity attenuation of material very fast；Coat phosphoric acid LiNi after lithium0.5Mn1.5O4Under 55 DEG C of high temperature test environment, the capacity after 50 weeks is 124mAh/g, conservation rate About 95.38%, because after being coated by lithium phosphate, hinder LiNi0.5Mn1.5O4Directly contacting between electrolyte, Electrolyte decomposition and Mn dissolvings are inhibited, so that the cyclical stability of battery improves.
Figure 13 is using LiNi0.5Mn1.5O4With the lithium ion two of the positive electrode active materials of the positive electrode active materials of embodiment 6 The coulombic efficiency curve of primary cell.As a result show, uncoated LiNi0.5Mn1.5O4High temperature side of the battery being assembled at 55 DEG C Under test ring border, the average coulombic efficiency after 50 weeks is about 96.5%, coats the LiNi after lithium phosphate0.5Mn1.5O455 DEG C high temperature test environment under, the average coulombic efficiency after 50 weeks is about 97.9%.There is the original of coulombic efficiency difference Because being probably to be coated by lithium phosphate, LiNi is hindered0.5Mn1.5O4Directly contacting between electrolyte, it is suppressed that electrolyte Decomposition so that battery cyclical stability improve.
Finally it should be noted that various embodiments above is merely to illustrate technical scheme, rather than its limitations；To the greatest extent The present invention is described in detail with reference to foregoing embodiments for pipe, it will be understood by those within the art that：Its according to The technical scheme described in foregoing embodiments can so be modified, either which part or all technical characteristic are entered Row equivalent substitution；And these modifications or replacement, the essence of appropriate technical solution is departed from various embodiments of the present invention technology The scope of scheme.

Claims (10)

1. a kind of positive electrode active materials of Phosphate coating spinel structure, wherein, the positive electrode active materials, which include, has point The chemical formula of spinel structure is LiMn2-xAxOyLithium-containing compound particle and be coated on the Phosphate coating layer on its surface, change Formula LiMn2-xAxOyIn, one or more of the A in Ni, Fe, Co, Ti, Y, Sc, Ru, Cu, Mo, Ge, W, Zr, Ca and Sr, 0 ≤ x≤0.7, and 3.8≤y≤4.2；And wherein, the lithium-containing compound particle has transition zone, the transition zone contains logical Cross and be coated with and its rear optional calcining and the diffusion element that diffuses into the lithium-containing compound particle.
2. positive electrode active materials according to claim 1, wherein, chemical formula LiMn2-xAxOyMiddle A is selected from Co and Ni；
Preferably, chemical formula LiMn2-xAxOyIn, 0≤x≤0.5, preferably 0.1≤x≤0.5；
Preferably, the chemical formula of the lithium-containing compound particle is LiMn2O4Or LiNi0.5Mn1.5O4；
Preferably, the particle diameter of the lithium-containing compound particle is 0.1~30 μm, preferably 0.2 μm~10 μm, more preferably 0.2 ~0.5 μm.
3. positive electrode active materials according to claim 1 or 2, wherein, the phosphate is selected from LiCoPO4、LiFePO4、 LiMnPO4And Li3PO4In one or more；
Preferably, the thickness of the Phosphate coating layer is 1~50nm, preferably 5~15nm；
Preferably, the Phosphate coating layer is 1~100% in the coverage of the lithium-containing compound particle surface, is preferably 20~90%, more preferably 60~80%.
4. positive electrode active materials according to any one of claim 1 to 3, wherein, the diffusion element be selected from Fe, Co and One or more in Mn；
Preferably, the phosphate is substantially Li3PO4, one or more of the diffusion element in Fe, Co and Mn；
Preferably, the phosphate is substantially LiFePO4Or LiMnPO4, the diffusion element is corresponding in the phosphate Transition metal Fe or Mn；
Preferably, the thickness of the transition zone is 0~15 μm, preferably 0.1~5 μm, more preferably 100~250nm；
Preferably, the transition zone is distributed in 0~10nm of surface apart from the lithium-containing compound particle, preferably 0~5nm it Between；
Preferably, the amount ratio of diffusion element and the phosphatic material be more than 0 to less than or equal to 1, preferably 0.5~ 1。
5. the preparation method of the positive electrode active materials any one of Claims 1-4, methods described include：
(1) phosphoric acid or its ammonium salt solution, the precursor salt solution of diffusion element and lithium precursor solution are added dropwise to lithium-containing compound In the dispersion of particle, it is stirred, obtains mixture；
(2) mixture obtained in step (1) is transferred in closed reactor, at 120~250 DEG C hydro-thermal reaction 0.1~ 20 hours；
(3) material that hydro-thermal reaction obtains in step (2) is cooled to room temperature, carries out eccentric cleaning with water and ethanol respectively；With
(4) material after the cleaning that will be obtained in step (3) is dried 3~6 hours at 80~150 DEG C, obtains positive-active material Material.
6. preparation method according to claim 5, wherein, the ammonium salt of phosphoric acid is ammonium dihydrogen phosphate and/or phosphorus in step (1) The sour ammonium of hydrogen two；
Preferably, the precursor salt that element is spread described in step (1) is selected from ferrous sulfate, cobaltous sulfate, manganese sulfate, cobalt nitrate, nitre One or more in sour manganese, manganese chloride, cobalt chloride and frerrous chloride；
Preferably, lithium presoma described in step (1) is lithium hydroxide；
Preferably, solvent described in step (1) is water and/or ethanol；
Preferably, the solvent of the dispersion of the lithium-containing compound particle is water and/or ethanol；
Preferably, phosphoric acid or its ammonium salt, the precursor salt of diffusion element and lithium presoma are added according to following ratio in step (1) 's：The mol ratio of phosphorus, diffusion element and lithium is 1：0.5~2：0.5~6, preferably 1：0.5~1：3~6；
Preferably, the concentration of phosphoric acid or its ammonium salt solution is 0.1mol/L~0.3mol/L in step (1)；
Preferably, the concentration of the precursor salt solution of diffusion element is 0.1mol/L~0.3mol/L in step (1)；
Preferably, the concentration of lithium precursor solution is 0.3mol/L~1.8mol/L in step (1), preferably 0.3mol/L~ 0.9mol/L；
Preferably, the mass fraction of lithium-containing compound particle is 30 weights in the dispersion of lithium-containing compound particle in step (1) Measure the weight % of %~50；
Preferably, the temperature of hydro-thermal reaction is 150~200 DEG C in step (2), such as 180 DEG C, and the time of hydro-thermal reaction is preferably 5~15 hours, such as 10 hours.
7. the preparation method according to claim 5 or 6, wherein, the preparation method also includes：
(5) positive electrode active materials obtained in step (4) are calcined 0.1~10 hour at 350~900 DEG C, so as to be burnt Positive electrode active materials after knot；
Preferably, the temperature of calcining is 450~700 DEG C in step (5)；
Preferably, the time of calcining is 1~5 hour, preferably 3 hours in step (5)；
Preferably, calcining is carried out under oxygen, air, the atmosphere containing reducing gas or inert atmosphere described in step (5) 's.
8. positive electrode active materials any one of Claims 1-4 are in the purposes of lithium rechargeable battery.
9. a kind of lithium ion secondary battery positive electrode, the positive pole includes the Claims 1-4 of collector and load on a current collector Any one of positive electrode active materials.
10. a kind of lithium rechargeable battery, the battery includes positive pole, negative pole, barrier film and the electrolyte described in claim 9；
Preferably, the battery also includes housing, wherein, positive pole, negative pole, barrier film and electrolyte are sealed in housing.
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