CN101740750B

CN101740750B - Method for preparing anode active substance, anode active substance, anode and battery

Info

Publication number: CN101740750B
Application number: CN2008101892354A
Authority: CN
Inventors: 田野; 程堂利; 席小兵
Original assignee: BYD Co Ltd
Current assignee: BYD Co Ltd
Priority date: 2008-11-05
Filing date: 2008-12-26
Publication date: 2013-04-10
Anticipated expiration: 2028-12-26
Also published as: CN101740750A

Abstract

The invention provides a method for preparing an anode active substance, the anode active substance prepared by the method, an anode comprising the anode active substance and a battery comprising the anode. The method for preparing the anode active substance comprises the step of sintering a mixture which comprises a raw material 1 and a raw material 2; the raw material 1 is one or more of compounds represented by general formulas: LixM'y(XO4)z, LiM'XO5, LiM'XO6 and LiM'X2O7, wherein x/z is more than 0 and less than or equal to 1, y/z is more than 0 and less than or equal to 1.1, M' is one or more of Na, Mn, Fe, Co, Ni, Ti, V, Y, Mg, Ca and Zn, and X is P, S, As, Mo or W; and the raw material 2 is one or more of compounds represented by a general formula: AaMbNcOd, wherein A, M, and N are different from one another, and are IIA, IIIA, IVA, VA, IB, IIB, IIIB, IVB, VB, VIB, VIIB or VIII group metallic elements respectively, and a and b are not simultaneously 0. The anode active substance prepared by the method can obviously improve the specific capacity of quality and cycle performance of the battery.

Description

The preparation method of positive active material and positive active material and Anode and battery

Technical field

The invention relates to a kind of preparation method of positive active material and the positive active material that is made by this preparation method and the positive pole that comprises this positive active material and comprise the battery that this is anodal, positive active material and the positive pole that comprises this positive active material that especially makes about a kind of preparation method of positive active material of lithium secondary battery and by this preparation method and comprise the battery that this is anodal.

Background technology

Lithium secondary battery also is the first-selected power supply of following electric automobile and hybrid-electric car because of the ideal source that it has that specific energy is large, self discharge is little, has extended cycle life, lightweight and advantages of environment protection becomes portable type electronic product.Therefore lithium secondary battery and associated materials thereof have become one of study hotspot of countries in the world scientific research personnel.Wherein positive active material owing on the high side, specific capacity is on the low side become the restriction lithium secondary battery by the bottleneck of large-scale application.At present the inorganic metal compound material is by the metal sulfide of the first generation, develop into the metal oxide of the second generation, but above-mentioned two classes have the shortcoming that some are difficult to overcome separately as the material of positive active material, and are on the low side such as specific capacity, price is higher, cycle performance is not very good and the potential safety hazard factor is relatively outstanding etc.Polyanion type compound has good performance as cathode active material for lithium secondary battery, very likely is pushed to be third generation cathode active material for lithium secondary battery.

Polyanion type compound is a series of tetrahedron or octahedra anion structure unit (XO of containing _m) ^N-The general name of the compound of (X=P, S, As, Mo and W).These construction units are linked to be three-dimensional net structure by strong covalent bond and form the space that is occupied by other metal ion of higher coordination, so that polyanion type compound-material has the crystal phase structure different with the metallic compound material and by the various outstanding performance of structures shape.What report was many at present is the polyanion shaped material with olivine and two kinds of structure types of NASICON.This series material has two outstanding advantages: the first, and the crystal frame structure of material is stable, even if a large amount of lithium secondary takes off embedding, this point and the metal oxide of the second generation have larger different; The second, be easy to the discharge potential platform of modulation material.But the shortcoming of polyanion shaped material is that conductance is lower, and the heavy-current discharge performance of material is relatively poor.Mostly be material to be carried out the methods such as carbon coating or doping high-valency metal to improve its electronic conductivity to the method for material modification at present, but it is not ideal to improve effect.

For this reason, disclose a kind of positive active material among the US 2007/0207385A1, comprised compound one and compound two, compound one general formula A _3xM1 _2y(PO ₄) ₃Represent that compound two is for being selected from SiC, BN and formula M 2 _aO _bAt least a compound in the group that the metal oxide of expression forms and be coated on the surface of compound one, wherein, A is for being selected from least a atom among IA, IIA, the IIIA, M1 and M2 respectively do for oneself and are selected from least a element in the group that is comprised of IIA, IIIA, IVA and VA and transition metal, are preferably separately at least a element in the group that is comprised of Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Be, Mg, Ca, Sr, B, Al, Sn, Ga, In, Si and Ge.And enumerated in an embodiment LiFePO ₄/ ZnO/C, LiFePO ₄/ ZnAlO ₂/ C, LiFePO ₄/ CuO/C and LiFePO ₄/ ZnAlO/C.

Although above-mentionedly increase by the electronic conductivity that coats the positive active material that compound two obtains on the surface of compound one, its electronic conductivity is still lower, generally only is 10 ^-5S/cm, and the specific discharge capacity of the battery that is made by this positive active material is lower, cycle performance is relatively poor.

Summary of the invention

The defective that specific discharge capacity is lower, cycle performance is relatively poor of the battery that the electronic conductivity that the object of the invention is to overcome existing positive active material is lower, made by this positive active material, thus provide specific discharge capacity that a kind of electronic conductivity of the positive active material that can Effective Raise makes can improve battery and cycle performance positive active material preparation method and the positive active material that is made by this preparation method and comprise the anodal of this positive active material and comprise the battery that this is anodal.

The invention provides a kind of preparation method of positive active material, wherein, this preparation method comprises that with a kind of mixture sintering this mixture contains raw material one and raw material two, and described raw material one is general formula Li _xM ' _y(XO ₄) _z, LiM ' XO ₅, LiM ' XO ₆, LiM ' X ₂O ₇In the compound of expression one or more, 0＜x/z≤1,0＜y/z≤1.1, M ' is one or more among Na, Mn, Fe, Co, Ni, Ti, V, Y, Mg, Ca, the Zn, X is P, S, As, Mo or W; Described raw material two is general formula A _aM _bN _cO _dIn the compound of expression one or more, A, M, N are different in twos, respectively do for oneself IIA, IIIA, IVA, VA, IB, IIB, IIIB, IVB, VB, VIB, VIIB or VIII family metallic element, 0≤a≤6,0≤b≤6,0＜c≤6,0＜d≤12, and a, b are not 0 simultaneously.

The present invention also provides a kind of positive active material that is made by above-mentioned preparation method.

The present invention also provides a kind of positive pole, this positive pole comprises plus plate current-collecting body and coating and/or is filled in positive electrode on this plus plate current-collecting body, described positive electrode contains positive active material and adhesive, and wherein, described positive active material is positive active material provided by the invention.

The present invention also provides a kind of lithium secondary battery, this lithium secondary battery comprises battery container, electrode group and electrolyte, and electrode group and electrolyte are sealed in the battery container, and the electrode group comprises reels or stacked positive pole, barrier film and negative pole successively, wherein, described positive pole just very provided by the invention.

Data from table 1 of the present invention can find out that the electronic conductivity of the positive active material that method provided by the invention makes can reach 1.8S/cm; Forming in the identical situation, Comparative Examples 1 is passed through ZnAlO ₂Be coated on LiFePO with C ₄The surface and the electronic conductivity of the positive active material that obtains only is 2.6 * 10 ^-5S/cm, the electronic conductivity of the positive active material that makes by the embodiment of the invention 7 then are 0.5S/cm, the latter be the former more than 19000 doubly.

In addition, data from table 2 of the present invention can be found out, the initial discharge specific discharge capacity of the battery A1-A15 that the positive active material that is made by method provided by the invention is made all is significantly higher than the reference cell AC1 of Comparative Examples, in the identical situation of other condition, the specific discharge capacity of the battery A7 that the positive active material that is made by method provided by the invention is made is 126 MAh/gs, and reference cell AC1 then only is 112 MAh/gs; Capacity dimension holdup after the battery A7 circulation 500 times is 96.44%, and reference cell AC1 only is 90.12% at the capacity dimension holdup of circulation after 500 times, has illustrated that thus positive electrode active material mass-energy that method provided by the invention makes significantly improves specific discharge capacity and the cycle performance of battery.

Description of drawings

Fig. 1 is the XRD diffraction pattern of the positive active material of embodiment 1 preparation;

Fig. 2 is the XRD diffraction pattern of the positive active material of embodiment 2 preparations;

Fig. 3 is the XRD diffraction pattern of the positive active material of embodiment 3 preparations;

Fig. 4 is the XRD diffraction pattern of the positive active material of embodiment 4 preparations;

Fig. 5 is the XRD diffraction pattern of the positive active material of embodiment 5 preparations;

Fig. 6 is the XRD diffraction pattern of the positive active material of embodiment 6 preparations.

Embodiment

Product behind raw material one of the present invention and raw material two sintering is mixed crystal, described mixed crystal refers to the mixed crystal that two or more compound forms through oversintering, chemical reaction does not occur between this two or more the compound, but the electronic conductivity with obvious raising, its mechanism may be interpreted as: between this two or more the compound chemical reaction does not occur, but in the process of sintering, but introduced a large amount of crystal defects, changed the electronics bonding state between the compound, so that mixed crystal a large amount of oxygen rooms and/or metal gap atom occur owing to lacking oxygen atom.These oxygen rooms and/or metal gap atom provide charge carrier, so that the electronic conductivity of this mixed crystal is greatly improved.

The electronic conductivity of the positive active material that method provided by the invention makes under 25 ℃ can reach 0.01-10S/cm, is preferably 0.1-2S/cm.

Wherein, the mol ratio of described raw material one and raw material two can be 1: 0.01-0.05.

Described raw material two can make with method as described below: with the oxygenatedchemicals of the oxygenatedchemicals of the oxygenatedchemicals of A, M and N with the ratio of mol ratio A: M: N=a: b: c at 400-1000 ℃ of lower sintering 8-15 hour.The sintering afterproduct can adopt the D/MAX-2200/PC type x-ray powder diffraction instrument of Rigaku company to measure, and obtains the XRD diffraction pattern, compare with standard diagram, thus the chemical formula of the product that affirmation makes.Wherein, the oxygenatedchemicals of described A can be for generating the compound of the oxide of A behind the oxide of A and/or the sintering, the compound that can generate the oxide of A behind the described sintering can be in the bicarbonate of the carbonate of the hydroxide of A, A, A one or more.The oxygenatedchemicals of described M can be for generating the compound of the oxide of M behind the oxide of M and/or the sintering, the compound that can generate the oxide of M behind the described sintering can be in the bicarbonate of the carbonate of the hydroxide of M, M, M one or more.The oxygenatedchemicals of described N can be for generating the compound of the oxide of N behind the oxide of N and/or the sintering, the compound that can generate the oxide of N behind the described sintering can be in the bicarbonate of the carbonate of the hydroxide of N, N, N one or more.

Among the present invention, general formula Li _xM ' _y(XO ₄) _zRepresented described raw material one can be olivine-type, NASICON type or monoclinic form, and the example of olivine-type can be enumerated LiMnPO ₄, LiCoPO ₄Deng, the example of NASICON type or monoclinic form can be enumerated Li ₃Fe ₂(PO ₄) ₃, LiTi ₂(PO ₄) ₃, Li ₃V ₂(PO ₄) ₃, Li ₂NaV ₂(PO ₄) ₃Deng, general formula LiM ' XO ₅Represented described raw material one can be enumerated LiTiPO ₅, general formula LiM ' XO ₆Represented described raw material one can be enumerated LiVMoO ₆, LiVWO ₆Deng, general formula LiM ' X ₂O ₇Represented described raw material one can be enumerated LiVP ₂O ₇, LiFeAs ₂O ₇Deng.

Wherein, general formula Li _XxM ' _Yy(XO ₄) _ZzIn the represented described raw material one, M ' is preferably one or more among Fe or Fe and Mn, Co, Ni, Ti, Y, Mg, Ca, the Zn, and the shared molar ratio of Fe is 90-100% among the M '.Specifically can list LiFePO ₄, Li _0.99Y _0.01FePO ₄And LiR _iFe _1-iPO ₄In the compound of expression one or more, wherein, 0＜i≤0.1, R is one or more among Co, Mn, Mg, Ca, Ni, Zn, the Ti.

Described raw material two can be Bi ₄Ti ₃O ₁₂, CuNb ₂O ₆, MnTaO ₄, FeWO ₄, ZnZrNb ₂O ₈, NiNb ₂O ₆, NiZrNb ₂O ₈, FeTiNb ₂O ₈, MnTiNb ₂O ₈, MgSnNb ₂O ₈, ZnTa ₂O ₆, Cu _0.85Zn _0.15Nb ₂O ₆, YBa ₃Ti ₂O _8.5, Zr _0.75Ti _0.75Sn _0.5O ₄, HfTiO ₄, MgNb ₂O ₆In one or more.

Under the preferable case, described mixture can also contain carbon source, the consumption of described carbon source so that in the positive active material of gained the content of carbon be the 1-5 % by weight.According to this preferred implementation, can further improve the electronic conductivity of prepared positive active material.Described carbon source can be various carbon sources well known in the art, for example can be DIC source and/or organic carbon source, described inorganic carbon source can be in carbon black, acetylene black, the graphite one or more, and described organic carbon source can be in glucose, sucrose, citric acid, starch, dextrin, the polyethylene glycol one or more.

The condition of described sintering can comprise that the heating rate with 5-20 ℃/min is warming up to 500-850 ℃, in 500-850 ℃ of lower sintering 5-32 hour; The atmosphere of described sintering is different because of the difference of raw material, and easy when oxidized under described sintering temperature when raw material, the atmosphere of described sintering is preferably inert atmosphere or reducing atmosphere; When raw material is difficult under described sintering temperature when oxidized, the atmosphere of described sintering can be any atmosphere.

The present invention also provides a kind of positive active material, and wherein, this positive active material is made by above-mentioned preparation method.

Need to prove, described in background technology of the present invention, although disclosed positive active material also comprises compound one and compound two among the US 2007/0207385A1, compound one general formula A _3xM1 _2y(PO ₄) ₃Represent that compound two is for being selected from SiC, BN and formula M 2 _aO _bAt least a compound in the group that the metal oxide of expression forms and be coated on the surface of compound one, wherein, A is for being selected from least a atom among IA, IIA, the IIIA, M1 and M2 respectively do for oneself and are selected from least a element in the group that is comprised of IIA, IIIA, IVA and VA and transition metal, and have specifically enumerated positive active material LiFePO in embodiment ₄/ ZnO/C, LiFePO ₄/ ZnAlO ₂/ C, LiFePO ₄/ CuO/C and LiFePO ₄/ ZnAlO/C, but in US 2007/0207385A1, be to prepare as follows positive active material:

(S11) preparation contains A ion, M1 ion and PO ₄ ^3-The solution of ion,

(S12) add M2 salt in mentioned solution,

(S13) pH that regulates mentioned solution is with formation M2 hydroxide, and so that M2 hydroxide becomes the M2 oxide.

(S14) make the dry and sintering of solution of the above-mentioned M2 of containing oxide, be coated with M2 to form the surface _aO _bA _3xM1 _2y(PO ₄) ₃

Can find out that from above-mentioned preparation method although sintering is also arranged among the US 2007/0207385A1, this sintering is in order to obtain end product ... the surface is coated with M2 _aO _bA _3xM1 _2y(PO ₄) ₃, and only pass through M2 _aO _bCoat A _3xM1 _2y(PO ₄) ₃The surface and the positive active material that obtains can not reach of the present invention and is the 0.01-10S/cm high electronic conductivities of 0.1-2S/cm particularly down at 25 ℃, and the product of the present invention after with raw material one and raw material two sintering is mixed crystal, this mixed crystal is the anoxic attitude, contain aerobic room and/or metal gap atom, the effect that these oxygen rooms and/or metal gap atom can play donor level improves the electronic conductivity of this mixed crystal, thereby can improve the electronic conductivity of the positive active material that the present invention makes, therefore the positive active material that makes of method provided by the invention is different from the positive active material described in the US 2007/0207385A1.

In addition, the present invention also provides a kind of positive pole, and this positive pole comprises plus plate current-collecting body and coating and/or be filled in positive electrode on this plus plate current-collecting body that described positive electrode contains positive active material and adhesive, wherein, described positive active material is positive active material provided by the invention.

Described adhesive can adopt any adhesive known in those skilled in the art, and preferred described adhesive is the mixture of hydrophobicity adhesive and hydrophilic adhesive.The ratio of described hydrophobicity adhesive and hydrophilic adhesive has no particular limits, and can determine according to actual needs, and for example, the part by weight of hydrophilic adhesive and hydrophobicity adhesive can be 0.3: 1-1: 1.Described adhesive can use with the aqueous solution or emulsion form, also can use with solid form, preferably use with the aqueous solution or emulsion form, have no particular limits the concentration of described hydrophilic adhesive solution and the concentration of described hydrophobicity adhesive agent emulsion this moment, the viscosity that can be coated with according to the slurry of positive pole to be prepared and cathode size and the requirement of operability are adjusted flexibly to this concentration, for example the concentration of described hydrophilic adhesive solution can be the 0.5-4 % by weight, and the concentration of described hydrophobicity adhesive agent emulsion can be the 10-80 % by weight.Described hydrophobicity adhesive can be polytetrafluoroethylene, butadiene-styrene rubber or their mixture.Described hydrophilic adhesive can be hydroxypropyl methylcellulose, sodium carboxymethylcellulose, hydroxyethylcellulose, polyvinyl alcohol or their mixture.The content of described adhesive is the 0.01-8 % by weight of positive active material, is preferably the 1-5 % by weight.

Under the preferable case, described positive electrode can also contain conductive agent, and described conductive agent can adopt any conductive agent known in those skilled in the art, for example can adopt in graphite, carbon fiber, carbon black, metal dust and the fiber one or more.The content of described conductive agent can for, for example, the 0.1-20 % by weight of described positive electrode total weight is preferably the 2-10 % by weight.

Described plus plate current-collecting body can be aluminium foil, Copper Foil, nickel plated steel strip or Punching steel strip.

The preparation method of described positive pole can adopt this area the whole bag of tricks commonly used, for example with solvent positive active material, adhesive and conductive agent are prepared into anode sizing agent, then prepared anode sizing agent slurry is coated in dry compressing tablet on the positive electrode collector, cut-parts obtain positive pole again.The temperature of described drying can be 100-150 ℃, and can be 2-10 hour drying time.

The used solvent of described anode sizing agent can be the various solvents that use in the prior art, as being selected from one or more in 1-METHYLPYRROLIDONE (NMP), dimethyl formamide (DMF), diethylformamide (DEF), dimethyl sulfoxide (DMSO) (DMSO), oxolane (THF) and water and the alcohols.The addition of this solvent is conventionally known to one of skill in the art, and the viscosity that can be coated with according to the slurry of anode sizing agent to be prepared and the requirement of operability are adjusted flexibly, described anode sizing agent can be coated on the described plus plate current-collecting body get final product.In general, it is the 40-90 % by weight that the consumption of this solvent makes the content of positive active material in the anode sizing agent, is preferably the 50-85 % by weight.

In lithium secondary battery, barrier film is arranged between positive pole and the negative pole, has electrical insulation capability and liquid retainability energy.In the present invention, described barrier film can be selected from and well known to a person skilled in the art various barrier films used in the lithium secondary battery, for example polyolefin micro porous polyolefin membrane, polyethylene felt, glass mat or ultra-fine fibre glass paper.

Described negative pole can adopt negative pole known in the field, and in general, negative pole comprises negative current collector and coating and/or is filled in negative material on this negative current collector.Described conductive current collector is conventionally known to one of skill in the art, for example can be in aluminium foil, Copper Foil, nickel plated steel strip, the Punching steel strip a kind of.Anticathode material of the present invention has no particular limits, and is the same with prior art, and described negative material contains negative electrode active material and adhesive usually.Described negative electrode active material can adopt various negative electrode active materials commonly used in the prior art, for example material with carbon element.Described material with carbon element can be non-graphitic carbon, graphite or the charcoal that obtained by high-temperature oxydation by polyyne family macromolecule material, also can use other material with carbon element such as pyrolytic carbon, coke, organic polymer sinter, active carbon etc.Described organic polymer sinter can be by the product with gained after the sintering such as phenolic resins, epoxy resin and the charing.

Described adhesive can be selected from the adhesive of lithium secondary battery routine, such as in polyvinyl alcohol, polytetrafluoroethylene, CMC (CMC) and the butadiene-styrene rubber (SBR) one or more.In general, the content of described adhesive is the 0.5-8 % by weight of negative electrode active material, is preferably the 2-5 % by weight.

Under the preferable case, described negative material can also contain conductive agent.Because conductive agent for increasing the conductivity of electrode, reduce the internal resistance of battery, so the present invention preferably contains conductive agent.The content of described conductive agent and kind are conventionally known to one of skill in the art, and for example, take negative material as benchmark, the content of conductive agent is generally the 0.1-12 % by weight.Described conductive agent can be selected from one or more in conductive carbon black, nickel powder, the copper powder.

The preparation method of described negative pole can adopt this area the whole bag of tricks commonly used, for example with solvent the conductive agent that negative electrode active material, adhesive and selectivity contain is prepared into cathode size, then prepared cathode size slurry is coated in dry compressing tablet on the negative electrode collector, cut-parts obtain negative pole again.The temperature of described drying can be 100-150 ℃, and can be 2-10 hour drying time.

The used solvent of described cathode size can be the various solvents that use in the prior art, as being selected from one or more in 1-METHYLPYRROLIDONE (NMP), dimethyl formamide (DMF), diethylformamide (DEF), dimethyl sulfoxide (DMSO) (DMSO), oxolane (THF) and water and the alcohols.The addition of this solvent is conventionally known to one of skill in the art, and the viscosity that can be coated with according to the slurry of cathode size to be prepared and the requirement of operability are adjusted flexibly, described cathode size can be coated on the described negative current collector get final product.In general, it is the 40-90 % by weight that the consumption of this solvent makes the content of negative electrode active material in the cathode size, is preferably the 50-85 % by weight.

In lithium secondary battery of the present invention, described electrolyte can be nonaqueous electrolytic solution.The solution that described nonaqueous electrolytic solution can form in nonaqueous solvents for electrolyte lithium salt.In the present invention, can use and well known to a person skilled in the art various nonaqueous electrolytic solutions.For example, described electrolyte lithium salt can be selected from lithium hexafluoro phosphate (LiPF ₆), lithium perchlorate (LiClO ₄), LiBF4 (LiBF ₄), hexafluoroarsenate lithium (LiAsF ₆), hexafluorosilicic acid lithium (LiSiF ₆), tetraphenyl lithium borate (LiB (C ₆H ₅) ₄), lithium chloride (LiCl), lithium bromide (LiBr), chlorine lithium aluminate (LiAlCl ₄) and fluorocarbon based Sulfonic Lithium (LiC (SO ₂CF ₃) ₃), LiCH ₃SO ₃, LiN (SO ₂CF ₃) ₂In one or more; Described nonaqueous solvents can be selected from chain acid esters and ring-type acid esters mixed solution, wherein the chain acid esters can be dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), methyl propyl carbonate (MPC), dipropyl carbonate (DPC) and other are fluorine-containing, sulfur-bearing or contain in the chain organosilane ester of unsaturated bond one or more, the ring-type acid esters can be ethylene carbonate (EC), propene carbonate (PC), vinylene carbonate (VC), gamma-butyrolacton (γ-BL), sultone and other are fluorine-containing, sulfur-bearing or contain in the ring-type organosilane ester of unsaturated bond one or more.In described nonaqueous electrolytic solution, the concentration of electrolyte lithium salt can be the 0.1-2 mol/L, is preferably the 0.8-1.2 mol/L.

The preparation method of lithium secondary battery provided by the invention can be method as well known to those skilled in the art, in general, this preparation method comprises and positive pole, barrier film and negative pole being reeled successively or stacked to form electrode cores, this electrode cores is inserted in the battery case, add electrolyte, then sealing obtains lithium secondary battery.Wherein, described coiling or method overlapping and sealing can be the known methods of those skilled in the art.The consumption of described electrolyte can adopt conventional amount used known in those skilled in the art.

The present invention is described in detail below by embodiment.

Embodiment 1

With MnCO ₃, TiO ₂, Nb ₂O ₅Mix as 1: 1: 1 ratio take mol ratio, ball milling 5 hours is warming up to 500 ℃ of roastings 10 hours with 10 ℃/min under nitrogen atmosphere, obtain sintered product.The XRD diffraction pattern of this sintered product that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is with MnTiNb ₂O ₈Standard diagram is compared, thereby confirms that this sintered product is MnTiNb ₂O ₈

With LiFePO ₄With the above-mentioned MnTiNb that makes ₂O ₈Mixing according to 1: 0.04 ratio of mol ratio, is that the amount of 5 % by weight adds the starch as carbon source according to the content of carbon in the positive active material that generates then, and ball milling 10 hours mixes; Then the mixture that ball milling is good is warming up to 600 ℃ with dried powder heating rate with 10 ℃/min under argon gas atmosphere 80 ℃ of oven dry, carries out the constant temperature sintering 20 hours, obtains positive active material LiFePO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

Adopt the XRD diffraction pattern of this positive active material that the D/MAX-2200/PC type x-ray powder diffraction instrument of Rigaku company records as shown in Figure 1, in the diffraction maximum of the positive active material that as can be seen from Figure 1 behind above-mentioned sintering, makes, except LiFePO ₄And MnTiNb ₂O ₈Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiFePO in this positive active material be described ₄And MnTiNb ₂O ₈Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiFePO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

Embodiment 2

With ZnO, Ta ₂O ₅Mix as 1: 1 ratio take mol ratio, ball milling 5 hours is warming up to 800 ℃ of roastings 8 hours with 15 ℃/min under air atmosphere, obtain sintered product.The XRD diffraction pattern of this sintered product that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is with ZnTa ₂O ₆Standard diagram is compared, thereby confirms that this sintered product is ZnTa ₂O ₆

With LiFePO ₄With the above-mentioned ZnTa that makes ₂O ₆Mix according to 1: 0.03 ratio of mol ratio, ball milling 10 hours mixes; Then the mixture that ball milling is good is warming up to 500 ℃ with dried powder heating rate with 5 ℃/min under argon gas atmosphere 80 ℃ of oven dry, carries out the constant temperature sintering 30 hours, obtains positive active material LiFePO ₄/ ZnTa ₂O ₆Mixed crystal.

Adopt the XRD diffraction pattern of this positive active material that the D/MAX-2200/PC type x-ray powder diffraction instrument of Rigaku company records as shown in Figure 2, in the diffraction maximum of the positive active material that as can be seen from Figure 2 behind above-mentioned sintering, makes, except LiFePO ₄And ZnTa ₂O ₆Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiFePO in this positive active material be described ₄And ZnTa ₂O ₆Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiFePO ₄/ ZnTa ₂O ₆Mixed crystal.

Embodiment 3

With Y ₂O ₃, BaCO ₃, TiO ₂Mix as 0.5: 3: 2 ratio take mol ratio, ball milling 5 hours is warming up to 1000 ℃ of roastings 15 hours with 7 ℃/min under nitrogen atmosphere, obtain sintered product.The XRD diffraction pattern of this sintered product that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is with YBa ₃Ti ₃O _8.5Standard diagram is compared, thereby confirms that this sintered product is YBa ₃Ti ₂O _8.5

With LiFePO ₄With the above-mentioned YBa that makes ₃Ti ₂O _8.5Mixing according to 1: 0.02 ratio of mol ratio, is that the amount of 2 % by weight adds the carbon black as carbon source according to the content of carbon in the positive active material that generates then, and ball milling 10 hours mixes; Then the mixture that ball milling is good is warming up to 800 ℃ with dried powder heating rate with 20 ℃/min under argon gas atmosphere 80 ℃ of oven dry, carries out the constant temperature sintering 8 hours, obtains positive active material LiFePO of the present invention ₄/ YBa ₃Ti ₂O _8.5The mixed crystal of/C.

Adopt the XRD diffraction pattern of this positive active material that the D/MAX-2200/PC type x-ray powder diffraction instrument of Rigaku company records as shown in Figure 3, in the diffraction maximum of the positive active material that as can be seen from Figure 3 behind above-mentioned sintering, makes, except LiFePO ₄And YBa ₃Ti ₂O _8.5Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiFePO in this positive active material be described ₄And YBa ₃Ti ₂O _8.5Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiFePO ₄/ YBa ₃Ti ₂O _8.5The mixed crystal of/C.

Embodiment 4

With CuO, ZnO, Nb ₂O ₅Mix as 0.85: 0.15: 1 ratio take mol ratio, ball milling 5 hours is warming up to 1000 ℃ of roastings 15 hours with 7 ℃/min under nitrogen atmosphere, obtain sintered product.The XRD diffraction pattern of this sintered product that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is with Cu _0.85Zn _0.15Nb ₂O ₆Standard diagram is compared, thereby confirms that this sintered product is Cu _0.85Zn _0.15Nb ₂O ₆

Prepare positive active material according to embodiment 1 described method, different is to use respectively LiCoPO ₄Replace LiFePO ₄, with the above-mentioned Cu that makes _0.85Zn _0.15Nb ₂O ₆Replace MnTiNb ₂O ₈, make positive active material LiCoPO ₄/ Cu _0.85Zn _0.15Nb ₂O ₆The mixed crystal of/C.

Adopt the XRD diffraction pattern of this positive electrode that the D/MAX-2200/PC type x-ray powder diffraction instrument of Rigaku company records as shown in Figure 4, in the diffraction maximum of the positive active material that as can be seen from Figure 4 behind above-mentioned sintering, makes, except LiCoPO ₄And Cu _0.85Zn _0.15Nb ₂O ₆Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiCoPO in this positive active material be described ₄And Cu _0.85Zn _0.15Nb ₂O ₆Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiCoPO ₄/ Cu _0.85Zn _0.15Nb ₂O ₆The mixed crystal of/C.

Embodiment 5

With ZrO ₂, TiO ₂, SnO ₂Mix as 0.75: 0.75: 0.5 ratio take mol ratio, ball milling 5 hours is warming up to 1000 ℃ of roastings 15 hours with 7 ℃/min under nitrogen atmosphere, obtain sintered product.The XRD diffraction pattern of this sintered product that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is with Zr _0.75Ti _0.75Sn _0.5O ₄Standard diagram is compared, thereby confirms that this sintered product is Zr _0.75Ti _0.75Sn _0.5O ₄

Prepare positive active material according to embodiment 1 described method, different is, with the above-mentioned Zr that makes _0.75Ti _0.75Sn _0.5O ₄Replace MnTiNb ₂O ₈, make positive active material LiFePO ₄/ Zr _0.75Ti _0.75Sn _0.5O ₄The mixed crystal of/C.

Adopt the XRD diffraction pattern of this positive electrode that the D/MAX-2200/PC type x-ray powder diffraction instrument of Rigaku company records as shown in Figure 5, in the diffraction maximum of the positive active material that as can be seen from Figure 5 behind above-mentioned sintering, makes, except LiFePO ₄And Zr _0.75Ti _0.75Sn _0.5O ₄Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiFePO in this positive active material be described ₄And Zr _0.75Ti _0.75Sn _0.5O ₄Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiFePO ₄/ Zr _0.75Ti _0.75Sn _0.5O ₄The mixed crystal of/C.

Embodiment 6

With FeO, WO ₃Mix as 1: 1 ratio take mol ratio, ball milling 5 hours is warming up to 800 ℃ of roastings 8 hours with 15 ℃/min under air atmosphere, obtain sintered product.The XRD diffraction pattern of this sintered product that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is with FeWO ₄Standard diagram is compared, thereby confirms that this sintered product is FeWO ₄

Prepare positive active material according to embodiment 1 described method, different is, with the above-mentioned FeWO that makes ₄Replace MnTiNb ₂O ₈, make positive active material LiFePO ₄/ FeWO ₄The mixed crystal of/C.

Adopt the XRD diffraction pattern of this positive electrode that the D/MAX-2200/PC type x-ray powder diffraction instrument of Rigaku company records as shown in Figure 6, in the diffraction maximum of the positive active material that as can be seen from Figure 6 behind above-mentioned sintering, makes, except LiFePO ₄And FeWO ₄Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiFePO in this positive active material be described ₄And FeWO ₄Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiFePO ₄/ FeWO ₄The mixed crystal of/C.

Embodiment 7

With ZnO, Al ₂O ₃Mix as 2: 1 ratio take mol ratio, ball milling 5 hours is warming up to 800 ℃ of roastings 8 hours with 15 ℃/min under air atmosphere, obtain sintered product.The XRD diffraction pattern of this sintered product that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is with ZnAlO ₂Standard diagram is compared, thereby confirms that this sintered product is ZnAlO ₂

Prepare positive active material according to embodiment 1 described method, different is, with the above-mentioned ZnAlO that makes ₂Replace MnTiNb ₂O ₈, make positive active material LiFePO ₄/ ZnAlO ₂The mixed crystal of/C.

The XRD diffraction pattern of this positive electrode that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is in the diffraction maximum of the positive active material that makes behind above-mentioned sintering as can be seen from the figure, except LiFePO ₄And ZnAlO ₂Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiFePO in this positive active material be described ₄And ZnAlO ₂Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiFePO ₄/ ZnAlO ₂The mixed crystal of/C.

Comparative Examples 1

Prepare positive active material LiFePO according to the disclosed method of Example B among the US 2007/0207385A1 ₄And ZnAlO ₂Mol ratio be 1: 0.04, the content of carbon be 5 % by weight by ZnAlO ₂Be coated on LiFePO with C ₄The surface and the positive active material LiFePO that forms ₄/ ZnAlO ₂/ C.

Embodiment 8

" anode material for lithium-ion batteries Li in " functional material " the 5th phase in 2005 of employing (36) volume _0.99Y _0.01FePO ₄Preparation " method described in the literary composition prepares Li _0.99Y _0.01FePO ₄

Prepare positive active material according to embodiment 1 described method, different is, with the above-mentioned Li that makes _0.99Y _0.01FePO ₄Replace LiFePO ₄, make positive active material Li _0.99Y _0.01FePO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

The XRD diffraction pattern of this positive active material that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is in the diffraction maximum of the positive active material that makes behind above-mentioned sintering as can be seen from the figure, except Li _0.99Y _0.01FePO ₄And MnTiNb ₂O ₈Characteristic peak outside, do not find the New Characteristics peak, thereby contained Li in this positive active material be described _0.99Y _0.01FePO ₄And MnTiNb ₂O ₈Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is Li _0.99Y _0.01FePO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

Embodiment 9

Adopt interim " the anode material for lithium-ion batteries LiNi of volume the 4th in " China YouSe Acta Metallurgica Sinica " April in 2006 the 16th _0.1Fe _0.9PO ₄Synthetic and performance " method described in the literary composition, with Li ₂CO ₃, FeC ₂O ₄2H ₂O, NH ₄H ₂PO ₄And TiO ₂With LiTi _0.05Fe _0.95PO ₄Stoichiometric proportion mix, ball milling is 5 hours in ethanol medium, the gained powder dries to remove ethanol at low temperatures, then with mixed-powder under the protection of argon gas, be warming up to 320 ℃ of constant temperature 7 hours, 700 ℃ of lower sintering 24 hours, make LiTi again _0.05Fe _0.95PO ₄

Prepare positive active material according to embodiment 1 described method, different is, with the above-mentioned LiTi that makes _0.05Fe _0.95PO ₄Replace LiFePO ₄, make positive active material LiTi _0.05Fe _0.95PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

The XRD diffraction pattern of this positive active material that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is in the diffraction maximum of the positive active material that makes behind above-mentioned sintering as can be seen from the figure, except LiTi _0.05Fe _0.95PO ₄And MnTiNb ₂O ₈Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiTi in this positive active material be described _0.05Fe _0.95PO ₄And MnTiNb ₂O ₈Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiTi _0.05Fe _0.95PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

Embodiment 10

Adopt interim " the anode material for lithium-ion batteries LiNi of volume the 4th in " China YouSe Acta Metallurgica Sinica " April in 2006 the 16th _0.1Fe _0.9PO ₄Synthetic and performance " method described in the literary composition, with Li ₂CO ₃, FeC ₂O ₄2H ₂O, NH ₄H ₂PO ₄And Ni (CH ₃COO) ₂4H ₂O is with LiNi _0.1Fe _0.9PO ₄Stoichiometric proportion mix, ball milling is 5 hours in ethanol medium, the gained powder dries to remove ethanol at low temperatures, then with mixed-powder under the protection of argon gas, be warming up to 320 ℃ of constant temperature 7 hours, 700 ℃ of lower sintering 24 hours, make LiNi again _0.1Fe _0.9PO ₄

Prepare positive active material according to embodiment 1 described method, different is, with the above-mentioned LiNi that makes _0.1Fe _0.9PO ₄Replace LiFePO ₄, make positive active material LiNi _0.1Fe _0.9PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

The XRD diffraction pattern of this positive active material that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is in the diffraction maximum of the positive active material that makes behind above-mentioned sintering as can be seen from the figure, except LiNi _0.1Fe _0.9PO ₄And MnTiNb ₂O ₈Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiNi in this positive active material be described _0.1Fe _0.9PO ₄And MnTiNb ₂O ₈Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiNi _0.1Fe _0.9PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

Embodiment 11

Adopt embodiment 10 described methods to prepare LiCo _0.01Fe _0.99PO ₄, different is to replace Ni (CH with CoO ₃COO) ₂4H ₂O and with LiCo _0.01Fe _0.99PO ₄Stoichiometric proportion mix.

Prepare positive active material according to embodiment 1 described method, different is, with the above-mentioned LiCo that makes _0.01Fe _0.99PO ₄Replace LiFePO ₄, make positive active material LiCo _0.01Fe _0.99PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

The XRD diffraction pattern of this positive active material that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is in the diffraction maximum of the positive active material that makes behind above-mentioned sintering as can be seen from the figure, except LiCo _0.01Fe _0.99PO ₄And MnTiNb ₂O ₈Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiCo in this positive active material be described _0.01Fe _0.99PO ₄And MnTiNb ₂O ₈Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiCo _0.01Fe _0.99PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

Embodiment 12

Adopt embodiment 10 described methods to prepare LiMn _0.02Fe _0.98PO ₄, different is to use MnCO ₃Replace Ni (CH ₃COO) ₂4H ₂O and with LiMn _0.02Fe _0.98PO ₄Stoichiometric proportion mix.

Prepare positive active material according to embodiment 1 described method, different is, with the above-mentioned LiMn that makes _0.02Fe _0.98PO ₄Replace LiFePO ₄, make positive active material LiMn _0.02Fe _0.98PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

The XRD diffraction pattern of this positive active material that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is in the diffraction maximum of the positive active material that makes behind above-mentioned sintering as can be seen from the figure, except LiMn _0.02Fe _0.98PO ₄And MnTiNb ₂O ₈Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiMn in this positive active material be described _0.02Fe _0.98PO ₄And MnTiNb ₂O ₈Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiMn _0.02Fe _0.98PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

Embodiment 13

Adopt embodiment 10 described methods to prepare LiMg _0.03Fe _0.97PO ₄, different is to replace Ni (CH with MgO ₃COO) ₂4H ₂O and with LiMg _0.03Fe _0.97PO ₄Stoichiometric proportion mix.

Prepare positive active material according to embodiment 1 described method, different is, with the above-mentioned LiMg that makes _0.03Fe _0.97PO ₄Replace LiFePO ₄, make positive active material LiMg _0.03Fe _0.97PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

The XRD diffraction pattern of this positive active material that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is in the diffraction maximum of the positive active material that makes behind above-mentioned sintering as can be seen from the figure, except LiMg _0.03Fe _0.97PO ₄And MnTiNb ₂O ₈Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiMg in this positive active material be described _0.03Fe _0.97PO ₄And MnTiNb ₂O ₈Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiMg _0.03Fe _0.97PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

Embodiment 14

Adopt embodiment 10 described methods to prepare LiCa _0.05Fe _0.95PO ₄, different is to replace Ni (CH with CaO ₃COO) ₂4H ₂O and with LiCa _0.05Fe _0.95PO ₄Stoichiometric proportion mix.

Prepare positive active material according to embodiment 1 described method, different is, with the above-mentioned LiCa that makes _0.05Fe _0.95PO ₄Replace LiFePO ₄, make positive active material LiCa _0.05Fe _0.95PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

The XRD diffraction pattern of this positive active material that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is in the diffraction maximum of the positive active material that makes behind above-mentioned sintering as can be seen from the figure, except LiCa _0.05Fe _0.95PO ₄And MnTiNb ₂O ₈Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiCa in this positive active material be described _0.05Fe _0.95PO ₄And MnTiNb ₂O ₈Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiCa _0.05Fe _0.95PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

Embodiment 15

Adopt embodiment 10 described methods to prepare LiZn _0.07Fe _0.93PO ₄, different is to use ZnCO ₃Replace Ni (CH ₃COO) ₂4H ₂O and with LiZn _0.07Fe _0.93PO ₄Stoichiometric proportion mix.

Prepare positive active material according to embodiment 1 described method, different is, with the above-mentioned LiZn that makes _0.07Fe _0.93PO ₄Replace LiFePO ₄, make positive active material LiZn _0.07Fe _0.93PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

The XRD diffraction pattern of this positive active material that the D/MAX-2200/PC type x-ray powder diffraction instrument of employing Rigaku company records is in the diffraction maximum of the positive active material that makes behind above-mentioned sintering as can be seen from the figure, except LiZn _0.07Fe _0.93PO ₄And MnTiNb ₂O ₈Characteristic peak outside, do not find the New Characteristics peak, thereby contained LiZn in this positive active material be described _0.07Fe _0.93PO ₄And MnTiNb ₂O ₈Still exist with two phase structure, do not have new material and generate, the positive active material that has proved thus above-mentioned preparation is LiZn _0.07Fe _0.93PO ₄/ MnTiNb ₂O ₈The mixed crystal of/C.

The electronic conductivity test of positive active material

The positive active material that under 25 ℃ embodiment 1-15 and Comparative Examples 1 is made respectively depresses to cylinder in the briquetting pressure of 30MPa, then measure respectively this cylindrical height l, bottom surface diameter d and resistance R, calculate respectively the electronic conductivity σ of embodiment 1-15 and Comparative Examples 1 positive active material, σ=4l/ (π Rd by following formula ²), the result is as shown in table 1 below.

Table 1

The positive active material source	Electronic conductivity (S/cm) under 25 ℃ of positive active material
		Embodiment
1	0.175
		Embodiment 2	0.21
Embodiment 3	1.8
		Embodiment 4	1.2
Embodiment 5	1.5
		Embodiment 6	0.8
Embodiment 7	0.5
		Comparative Examples 1	2.6×10 ^-5
Embodiment 8	0.83
		Embodiment 9	0.76
Embodiment 10	0.63
		Embodiment 11	0.94
Embodiment 12	0.87
		Embodiment 13	1.3
Embodiment 14	0.96
		Embodiment 15	0.83

Embodiment 16-30 and Comparative Examples 2

(1) anodal preparation

The positive active material and 5 that respectively 90 grams is made by embodiment 1-15 and Comparative Examples 1 restrains adhesive Kynoar (PVDF) and 5 gram conductive agent acetylene blacks join in the 50 gram 1-METHYLPYRROLIDONEs, then stirs in de-airing mixer and forms uniform anode sizing agent.This anode sizing agent is coated on the both sides that thickness is 20 microns aluminium foil equably, then in 150 ℃ of lower oven dry, roll-in, cut to make and be of a size of 540 * 43.5 millimeters positive pole, wherein contain the positive active materials of 5.2 grams of having an appointment.

(2) preparation of battery

The preparation of negative pole

90 gram negative electrode active material native graphites, 5 gram adhesive Kynoar, 5 gram conductive agent carbon blacks are joined in the 100 gram 1-METHYLPYRROLIDONEs, then in de-airing mixer, stir and form uniform cathode size.This cathode size is coated on the both sides that thickness is 12 microns Copper Foil equably, then in 90 ℃ of lower oven dry, roll-in, cut to make and be of a size of 500 * 44 millimeters negative pole, wherein contain the 3.8 gram negative electrode active material native graphites of having an appointment.

The assembling of battery

Respectively above-mentioned positive and negative electrode and polypropylene screen are wound into the pole piece of a square lithium secondary battery, subsequently with LiPF ₆Concentration by 1 mol/L is dissolved in EC/EMC/DEC=1: form nonaqueous electrolytic solution in 1: 1 the mixed solvent, this electrolyte is injected battery aluminum shell with the amount of 3.8g/Ah, lithium secondary secondary cell A1-A15, AC1 are made respectively in sealing.

The performance test of battery

The above-mentioned lithium secondary battery A1-A15 that makes and AC1 are placed on respectively test cashier's office in a shop, under 25 ℃ of conditions, carry out constant current charge with 0.5C first, charging upper limit is 3.8 volts; After shelving 20 minutes, be discharged to 2.5 volts with the electric current of 0.5C from 3.8 volts, the gained capacity is designated as the first discharge capacity of battery, and calculates according to the following equation the specific discharge capacity of battery; The result is as shown in table 2 below.

Specific discharge capacity=battery is discharge capacity (MAH)/positive active material weight (gram) first

Then repeat above-mentioned charging, shelve, after the discharge step each 500 times, the discharge capacity of record battery.By the capacity dimension holdup after the following formula computation cycles 500 times.The capacity dimension holdup is larger, illustrates that then the cycle performance of battery is better.The result is as shown in table 2 below.

Capacity dimension holdup=(the N time cyclic discharge capacity/first discharge capacity) * 100%

Table 2

The battery source	The battery numbering	Specific discharge capacity (MAh/g, 0.5C)	Capacity dimension holdup after 500 times circulates
				Embodiment 16	A1	123	95.21％
Embodiment 17	A2	124	95.87％
				Embodiment 18	A3	135	98.87％
Embodiment 19	A4	131	97.56％
				Embodiment
20	A5	133	98.50％
				Embodiment 21	A6	128	97.05％
Embodiment 22	A7	126	96.44％
				Comparative Examples 2	AC1	112	90.12％
Embodiment 23	A8	128	97.10％
				Embodiment 24	A9	127	97.01％
Embodiment 25	A10	126	96.87％
				Embodiment 26	A11	129	97.25％
Embodiment 27	A12	129	97.15％
				Embodiment 28	A13	132	97.87％
Embodiment 29	A14	129	97.26％
				Embodiment 30	A15	128	97.10％

Data from above-mentioned table 1 can find out that the electronic conductivity of the positive active material that method provided by the invention makes can reach 1.8S/cm; Forming in the identical situation, Comparative Examples 1 is passed through ZnAlO ₂Be coated on LiFePO with C ₄The surface and the electronic conductivity of the positive active material that obtains only is 2.6 * 10 ^-5S/cm, the electronic conductivity of the positive active material that makes by the embodiment of the invention 7 then are 0.5S/cm, the latter be the former more than 19000 doubly.

In addition, data from above-mentioned table 2 can be found out, the initial discharge specific discharge capacity of the battery A1-A15 that the positive active material that is made by method provided by the invention is made all is significantly higher than the reference cell AC1 of Comparative Examples, in the identical situation of other condition, the specific discharge capacity of the battery A7 that the positive active material that is made by method provided by the invention is made is 126 MAh/gs, and reference cell AC1 then only is 112 MAh/gs; Capacity dimension holdup after the battery A7 circulation 500 times is 96.44%, and reference cell AC1 only is 90.12% at the capacity dimension holdup of circulation after 500 times, has illustrated that thus positive electrode active material mass-energy that method provided by the invention makes significantly improves specific discharge capacity and the cycle performance of battery.

Claims

1. the preparation method of a positive active material is characterized in that, this preparation method comprises that with a kind of mixture sintering this mixture contains raw material one and raw material two, and described raw material one is general formula Li _xM ' _y(XO ₄) _z, LiM ' XO ₅, LiM ' XO ₆, LiM ' X ₂O ₇In the compound of expression one or more, 0＜x/z≤1,0＜y/z≤1.1, M ' is one or more among Na, Mn, Fe, Co, Ni, Ti, V, Y, Mg, Ca, the Zn, X is P, S, As, Mo or W; Described raw material two is general formula A _aM _bN _cO _dIn the compound of expression one or more, A, M, N are different in twos, 0≤a≤6,0≤b≤6,0＜c≤6,0＜d≤12, and a, b be not 0 simultaneously, the compound that is represented by above-mentioned general formula is Bi ₄Ti ₃O ₁₂, CuNb ₂O ₆, MnTaO ₄, ZnZrNb ₂O ₈, NiNb ₂O ₆, NiZrNb ₂O ₈, FeTiNb ₂O ₈, MnTiNb ₂O ₈, MgSnNb ₂O ₈, ZnTa ₂O ₆, Cu _0.85Zn _0.15Nb ₂O ₆, YBa ₃Ti ₂O _8.5, Zr _0.75Ti _0.75Sn _0.5O ₄, HfTiO ₄, MgNb ₂O ₆In one or more; Be mixed crystal with the product behind raw material one and raw material two sintering.

2. the preparation method of positive active material according to claim 1, wherein, the mol ratio of described raw material one and raw material two is 1:0.01-0.05.

3. the preparation method of positive active material according to claim 1, wherein, described raw material two is by the oxygenatedchemicals of the oxygenatedchemicals of the oxygenatedchemicals of A, M and the N ratio with mol ratio A:M:N=a:b:c was obtained at 400-1000 ℃ of lower sintering 8-15 hour.

4. the preparation method of positive active material according to claim 1, wherein, M ' is one or more the combination among Fe or Fe and Mn, Co, Ni, Ti, Y, Mg, Ca, the Zn, and the shared molar ratio of Fe is 90-100% among the M '.

5. the preparation method of positive active material according to claim 1, wherein, described raw material one is LiFePO ₄, LiMnPO ₄, LiCoPO ₄, Li ₃Fe ₂(PO ₄) ₃, LiTi ₂(PO ₄) ₃, Li ₃V ₂(PO ₄) ₃, Li ₂NaV ₂(PO ₄) ₃, Li _0.99Y _0.01FePO ₄, LiR _iFe _1-iPO ₄, LiTiPO ₅, LiVMoO ₆, LiVWO ₆, LiVP ₂O ₇, LiFeAs ₂O ₇In one or more, wherein, 0＜i≤0.1, R is one or more among Co, Mn, Mg, Ca, Ni, Zn, the Ti.

6. the preparation method of positive active material according to claim 5, wherein, described raw material one is LiFePO ₄, Li _0.99Y _0.01FePO ₄And LiR _iFe _1-iPO ₄In the compound of expression one or more.

7. the preparation method of the described positive active material of any one according to claim 1-6, wherein, mixture also contains carbon source, the consumption of described carbon source so that in the positive active material of gained the content of carbon be the 1-5 % by weight, described carbon source is one or more in carbon black, graphite, glucose, sucrose, citric acid, starch, dextrin, the polyethylene glycol.

8. the preparation method of positive active material according to claim 7, wherein, described carbon black is acetylene black.

9. the preparation method of positive active material according to claim 1, wherein, the condition of described sintering comprised that the heating rate with 5-20 ℃/min is warming up to 500-850 ℃, in 500-850 ℃ of lower sintering 5-32 hour.

10. a positive active material is characterized in that, this positive active material is made by the described method of any one among the claim 1-9.

11. positive pole, this positive pole comprises plus plate current-collecting body and coating and/or is filled in positive electrode on this plus plate current-collecting body, described positive electrode contains positive active material and adhesive, it is characterized in that, described positive active material is positive active material claimed in claim 10.

12. lithium secondary battery, this lithium secondary battery comprises battery container, electrode group and electrolyte, and electrode group and electrolyte are sealed in the battery container, and the electrode group comprises reels or stacked positive pole, barrier film and negative pole successively, it is characterized in that the described positive pole of described just very claim 11.