Summary of the invention
First technical problem to be solved by this invention provides a kind of Graphene/iron lithium phosphate compound anode active material.
Second technical problem to be solved by this invention provides the preparation method of a kind of Graphene/iron lithium phosphate compound anode active material.
The 3rd technical problem to be solved by this invention provides a kind of high performance lithium ion secondary battery with Graphene/iron lithium phosphate compound anode active material.
The technical scheme that the present invention is adopted for above-mentioned first technical problem of solution is: a kind of Graphene/iron lithium phosphate compound anode active material; It is characterized in that said positive electrode active materials is Graphene or the compound LiFePO 4 material of graphene oxide; Wherein the mass ratio of Graphene and LiFePO4 is 1/100~1/10, and the mass ratio of graphene oxide and LiFePO4 is 1/50~1/5.
The present invention for above-mentioned second technical scheme that technical problem adopted of solution is: the preparation method of a kind of Graphene/iron lithium phosphate compound anode active material; It is characterized in that step is: will contain lithium, iron content, phosphorous presoma and evenly mix through the mode of solid phase or liquid phase by a certain percentage with Graphene or graphene oxide; Obtain the compound LiFePO 4 material of Graphene through drying then; Obtain the compound lithium iron phosphate anode active material of Graphene through The high temperature anneal again, wherein said lithium, iron content and the phosphorous presoma of containing is by Li: Fe: P=1.00: 0.95~1.05: 0.95~1.05 mol ratio proportioning; The mass ratio of Graphene and LiFePO4 is 1/100~1/10, and the mass ratio of graphene oxide and LiFePO4 is 1/50~1/5.
Described Graphene is that the monoatomic layer or the number of plies are less than 5 layers graphite, and Graphene is through chemical stripping (S.Stankovich, D.A.Dikin, et al., Nature, 2006,442,282; " a kind of solution phase preparation method of Graphene ", Chinese invention patent, application number: 200910099595.X) or mechanical stripping method (K.S.Novoselov; 1A.K.Geim, et al., Science 2004; 306,666.) preparation, said graphene oxide is the oxide of Graphene; Be the Graphene that contains oxygen-containing functional groups such as hydroxyl, carbonyl, carboxyl that carbon-carbon double bond in the part Graphene obtains after oxidized, wherein the atomic ratio of oxygen and carbon is 1: 5~1: 1.
Described iron content presoma is one or more the combination in iron, ferrous oxide, di-iron trioxide, ferrous sulfate, ferric phosphate, ferrous nitrate, ferrous phosphate, ferrous oxalate, ferrous acetate, the ferrous citrate; Described phosphorous presoma is one or more the combination in phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, lithium dihydrogen phosphate, ferrous ammonium phosphate, the phosphorus pentoxide; The described lithium presoma that contains is one or more the combination in lithium hydroxide, lithium carbonate, lithium acetate, lithium nitrate, lithium dihydrogen phosphate, the lithium phosphate.
Described dry means can be spray drying, vacuum filtration drying or direct drying.
The described mechanical mixture that is mixed into solid phase or liquid phase, wherein solid phase mixing adopts mechanical means such as ball milling to carry out, and liquid-phase mixing can the mode through mechanical agitation or high energy milling be carried out in water or polar organic solvent.Solid phase described herein or liquid phase mechanical mixture are conventional method, no specific (special) requirements.
Described annealing is carried out under inert atmospheres such as argon gas or nitrogen, and annealing temperature is preferably 400~700 ℃, and annealing time is preferably 4~20 hours.
The present invention for above-mentioned the 3rd technical scheme that technical problem adopted of solution is: a kind of high performance lithium ion secondary battery; Comprise positive plate, negative plate, the barrier film between positive plate and negative plate and nonaqueous electrolytic solution; It is characterized in that: described positive plate is made up of one deck positive electrode active materials of coating on the plus plate current-collecting body; Positive electrode active materials is Graphene or the compound LiFePO 4 material of graphene oxide; Wherein the mass ratio of Graphene and LiFePO4 is 1/100~1/10, and the mass ratio of graphene oxide and LiFePO4 is 1/50~1/5.
The making of lithium rechargeable battery adopts traditional process route to carry out
Anodal preparation method be with positive electrode active materials and conductive agent and binding agent blend in solvent, coat on the collector after mixing, drying is the formation positive plate afterwards.Positive electrode active materials used herein is the LiFePO 4 material of Graphene modification or graphene oxide modification.Conductive agent can be conductive carbon material, and like conductive carbon black, Super P, collector is an aluminium foil.
The preparation method of negative pole be with negative active core-shell material and binding agent blend in solvent, coat on the collector after mixing, dry back forms negative plate.Said negative active core-shell material is lithium metal, material with carbon element, or can form the material of alloy with lithium, and wherein, said material with carbon element is the organic high molecular compound of graphite, RESEARCH OF PYROCARBON, coke, carbon fiber or high temperature sintering etc.; Described can be metallic element such as Mg, B, Al, Ga, In, Si, Sn, Pb, Sb, Bi, Cd, Ag, Zn, Hf, Zr or Y with the material that lithium forms alloy, contains alloy such as the SiB of Si and Sn
4, SiB
6, Mg
2Si, Mg
2Sn, Ni
2Si, TiSi
2, MoSi
2, CoSi
2, NiSi
2, CaSi
2, CrSi
2, Cu
5Si, FeSi
2, MnSi
2, NbSi
2, TaSi
2, VSi
2, WSi
2Perhaps ZnSi
2Perhaps other active materials such as SiC, Si
3N
4, Si
2N
2O, Ge
2N
2O or SiO
x, 0<x≤2, SnO
x, 0<x≤2; LiSiO or LiSnO etc.Collector is Copper Foil or nickel foil.
Described barrier film is the macromolecule membrane of one type of porous between positive plate and negative plate, like microporous polypropylene film etc.
Said nonaqueous electrolytic solution is made up of nonaqueous solvents and electrolyte; Wherein, Described nonaqueous solvents is dimethyl carbonate, dipropyl carbonate, propene carbonate, ethylene carbonate, butylene, gamma butyrolactone, sulfolane, methyl sulfolane, 1; 2-dimethoxy-ethane, 1, the mixture of one or more in 2-diethoxyethane, oxolane, 2-methyltetrahydrofuran, methylpropanoic acid, methylbutanoic acid, acetonitrile, propionitrile, methyl phenyl ethers anisole, acetate, lactate and the propionic ester; Said electrolyte is salt such as LiCl, LiBr, the LiPF that contains lithium
6, LiClO
4, LiAsF
6, LiBF
4, LiCH
3SO
3, LiCF
3SO
3, LiN (CF
3SO
2)
2Or LiB (C
6H
5)
4Deng.
Therefore compared with prior art, the invention has the advantages that: Graphene has the layer inner structure identical with graphite, has very good electric conductivity, the amorphous carbon material in the conventional carbon coating means; The two-dimentional lamellar structure of Graphene makes it can more effectively form three-dimensional conductive network with the LiFePO4 compound tense simultaneously, thereby further improves the chemical property of combination electrode material, is particluarly suitable for the application in the high rate charge-discharge.Synthesis technique of the present invention is easy, is easy to the preparation and the application of scale, has advantages such as capacity height, multiplying power discharging property and cyclical stability be outstanding based on the lithium rechargeable battery of this positive electrode active materials, and great practical value is arranged.
Embodiment
Embodiment describes in further detail the present invention below in conjunction with accompanying drawing.
The preparation of the first step, Graphene composite lithium iron phosphate material
Adopt the method for solid phase or liquid phase mechanical mixture evenly to mix with Graphene or graphene oxide iron content, presoma phosphorous and that contain lithium.Obtain the LiFePO 4 material of Graphene modification through reprocessing means such as dry (for the liquid-phase mixing system), high annealings.
Described iron content presoma is one or more the combination in iron, ferrous oxide, di-iron trioxide, ferrous sulfate, ferric phosphate, ferrous nitrate, ferrous phosphate, ferrous oxalate, ferrous acetate, the ferrous citrate.
Described phosphorous presoma is one or more the combination in phosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, lithium dihydrogen phosphate, ferrous ammonium phosphate, the phosphorus pentoxide.
The described lithium presoma that contains is one or more the combination in lithium hydroxide, lithium carbonate, lithium acetate, lithium nitrate, lithium dihydrogen phosphate, the lithium phosphate.
Second step, be the making of the lithium rechargeable battery of positive electrode with the Graphene composite lithium iron phosphate
The making of lithium rechargeable battery adopts traditional process route to carry out.Battery is made up of positive pole, negative pole, barrier film and nonaqueous electrolytic solution.
Anodal preparation method be with positive electrode active materials and conductive agent and binding agent blend in solvent, coat on the collector after mixing, drying is the formation positive plate afterwards.Positive electrode active materials used herein is a Graphene modified phosphate iron lithium material.Conductive agent can be conductive carbon material, and like conductive carbon black, Super P, collector is an aluminium foil.
The preparation method of negative pole be with negative active core-shell material and binding agent blend in solvent, coat on the collector after mixing, dry back forms negative plate.The negative active core-shell material active material can be lithium metal; Material with carbon element is like organic high molecular compound of graphite, RESEARCH OF PYROCARBON, coke, carbon fiber and high temperature sintering etc.; Can form the material of alloy with lithium, comprising metallic element (like Mg, B, Al, Ga, In, Si, Sn, Pb, Sb, Bi, Cd, Ag, Zn, Hf, Zr or Y etc.), the alloy that contains Si and Sn is (like SiB
4, SiB
6, Mg
2Si, Mg
2Sn, Ni
2Si, TiSi
2, MoSi
2, CoSi
2, NiSi
2, CaSi
2, CrSi
2, Cu
5Si, FeSi
2, MnSi
2, NbSi
2, TaSi
2, VSi
2, WSi
2Perhaps ZnSi
2Deng); And other active materials, like SiC, Si
3N
4, Si
2N
2O, Ge
2N
2O or SiO
x(0<x≤2), SnO
x(0<x≤2), LiSiO or LiSnO etc.Collector is Copper Foil or nickel foil.
Barrier film is the macromolecule membrane of one type of porous between positive plate and negative plate, like microporous polypropylene film etc.Nonaqueous electrolytic solution is made up of nonaqueous solvents and electrolyte.Wherein nonaqueous solvents is dimethyl carbonate, dipropyl carbonate, propene carbonate, ethylene carbonate, butylene, gamma butyrolactone, sulfolane, methyl sulfolane, 1; 2-dimethoxy-ethane, 1, the mixture of one or more in 2-diethoxyethane, oxolane, 2-methyltetrahydrofuran, methylpropanoic acid, methylbutanoic acid, acetonitrile, propionitrile, methyl phenyl ethers anisole, acetate, lactate and the propionic ester etc.Electrolyte is the salt that contains lithium, like LiCl, LiBr, LiPF
6, LiClO
4, LiAsF
6, LiBF
4, LiCH
3SO
3, LiCF
3SO
3, LiN (CF
3SO
2)
2Perhaps LiB (C
6H
5)
4Deng.
Embodiment 1
The first step is scattered in the ratio of ferrous oxalate and lithium dihydrogen phosphate 1.00: 0.95 in molar ratio~1.05 in the water, add subsequently graphene oxide (with the mass ratio of LiFePO4 be 1/50~1/5) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step; The lithium iron phosphate anode active material of Graphene modification and conductive agent Super P and binding agent Kynoar are mixed in n-formyl sarcolysine base pyrrolidones in 80: 15: 5 ratio of mass ratio; And be coated on the aluminium foil, 80 ℃ of following dryings obtain positive plate.Be negative pole with the lithium sheet subsequently, microporous polypropylene film is a barrier film, and the LiPF4 non-aqueous solution of 1mol/L (solvent is the mixed solvent of isopyknic dimethyl carbonate and dipropyl carbonate) is an electrolyte, positive plate assembling therewith, preparation lithium rechargeable battery.
Embodiment 2
The first step is scattered in lithium carbonate, ferrous oxalate and ammonium dihydrogen phosphate in the water by 1.00: 1.90~2.10: 1.90~2.10 mol ratio, add subsequently graphene oxide (with the mass ratio of LiFePO4 be 1/50~1/5) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 1.
Embodiment 3
The first step is scattered in di-iron trioxide and lithium dihydrogen phosphate in the water by 1.00: 1.90~2.10 mol ratio, add subsequently graphene oxide (with the mass ratio of LiFePO4 be 1/50~1/5) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 1.
Embodiment 4
The first step is scattered in the ratio of lithium carbonate, di-iron trioxide and ammonium dihydrogen phosphate 1.00: 0.95 in molar ratio~1.05: 1.90~2.10 in the water, add subsequently graphene oxide (with the mass ratio of LiFePO4 be 1/50~1/5) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 1.
Embodiment 5
The first step is scattered in the ratio of lithium carbonate and ferric phosphate 1.00: 1.90 in molar ratio~2.10 in the water, add subsequently graphene oxide (with the mass ratio of LiFePO4 be 1/50~1/5) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 1.
Embodiment 6
The first step is scattered in the ratio of lithium hydroxide and ferric phosphate 1.00: 0.95 in molar ratio~1.05 in the water, add subsequently graphene oxide (with the mass ratio of LiFePO4 be 1/50~1/5) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 1.
Embodiment 7
The first step is scattered in the ratio of lithium acetate and ferric phosphate 1.00: 0.95 in molar ratio~1.05 in the water, add subsequently graphene oxide (with the mass ratio of LiFePO4 be 1/50~1/5) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 1.
Embodiment 8
The first step is scattered in the ratio of ferrous citrate and lithium dihydrogen phosphate 1.00: 2.85 in molar ratio~3.15 in the water, add subsequently graphene oxide (with the mass ratio of LiFePO4 be 1/50~1/5) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 1.
Embodiment 9
The first step; With ferric phosphate, ferrous oxalate, lithium carbonate and lithium dihydrogen phosphate by Li: Fe: P=1.00: 0.95~1.05: 0.95~1.05 mol ratio is scattered in the water (proportioning between these four kinds of reaction raw materials can allotment arbitrarily under the mol ratio condition of the Li that confirms, Fe, P), add subsequently graphene oxide (with the mass ratio of LiFePO4 be 1/50~1/5) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second the step with embodiment 1 in the first step identical.
Embodiment 10
The first step; With ferric phosphate, ferrous oxalate, lithium hydroxide and lithium dihydrogen phosphate by Li: Fe: P=1.00: 0.95~1.05: 0.95~1.05 mol ratio is scattered in the water (proportioning between these four kinds of reaction raw materials can allotment arbitrarily under the mol ratio condition of the Li that confirms, Fe, P), add subsequently graphene oxide (with the mass ratio of LiFePO4 be 1/50~1/5) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 1.
Embodiment 11
The first step; With di-iron trioxide, ferrous oxalate, lithium hydroxide, lithium carbonate and ammonium dihydrogen phosphate by Li: Fe: P=1.00: 0.95~1.05: 0.95~1.05 mol ratio is scattered in the water (proportioning between these five kinds of reaction raw materials can allotment arbitrarily under the mol ratio condition of the Li that confirms, Fe, P), add subsequently graphene oxide (with the mass ratio of LiFePO4 be 1/50~1/5) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 1.
Embodiment 12
The first step is scattered in the ratio of ferrous oxalate and lithium dihydrogen phosphate 1.00: 0.95 in molar ratio~1.05 in the water, add subsequently Graphene (with the mass ratio of LiFePO4 be 1/100~1/10) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene
Second step; The lithium iron phosphate anode active material of Graphene modification and conductive agent Super P and binding agent Kynoar are mixed in n-formyl sarcolysine base pyrrolidones in 80: 15: 5 ratio of mass ratio; And be coated on the aluminium foil, 80 ℃ of following dryings obtain positive plate.Be negative pole with the lithium sheet subsequently, microporous polypropylene film is a barrier film, and the LiPF4 non-aqueous solution of 1mol/L (solvent is the mixed solvent of isopyknic dimethyl carbonate and dipropyl carbonate) is an electrolyte, positive plate assembling therewith, preparation lithium rechargeable battery.
Embodiment 13
The first step is scattered in lithium carbonate, ferrous oxalate and ammonium dihydrogen phosphate in the water by 1.00: 1.90~2.10: 1.90~2.10 mol ratio, add subsequently Graphene (with the mass ratio of LiFePO4 be 1/100~1/10) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 12.
Embodiment 14
The first step is scattered in di-iron trioxide and lithium dihydrogen phosphate in the water by 1.00: 1.90~2.10 mol ratio, add subsequently Graphene (with the mass ratio of LiFePO4 be 1/100~1/10) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 12.
Embodiment 15
The first step; With ferric phosphate, ferrous oxalate, lithium carbonate and lithium dihydrogen phosphate by Li: Fe: P=1.00: 0.95~1.05: 0.95~1.05 mol ratio is scattered in the water (proportioning between these four kinds of reaction raw materials can allotment arbitrarily under the mol ratio condition of the Li that confirms, Fe, P), add subsequently Graphene (with the mass ratio of LiFePO4 be 1/100~1/10) and fully mix.This mixture is obtained the combination electrode material presoma through spray drying.With this precursor powder under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with the 4th step among the embodiment 12.
Embodiment 16
The first step with the ferrous oxalate and the lithium dihydrogen phosphate of mol ratio 1.00: 0.95~1.05, and mixes with method that the mass ratio of LiFePO4 is 1/25~1/5 graphene oxide through solid phase mechanical lapping.Subsequently with this mixture under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 1.
Embodiment 17
The first step is 1.00: 1.90~2.10: 1.90~2.10 lithium carbonates, ferrous oxalate and ammonium dihydrogen phosphate with mol ratio, and mixes with method that the mass ratio of LiFePO4 is 1/50~1/5 graphene oxide through solid phase mechanical lapping.Subsequently with this mixture under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 1.
Embodiment 18
The first step; According to Li: Fe: P=1.00: 0.95~1.05: 0.95~1.05 mol ratio is ferric phosphate, ferrous oxalate, lithium carbonate and lithium dihydrogen phosphate (proportioning between these four kinds of reaction raw materials can allotment arbitrarily under the mol ratio condition of the Li that confirms, Fe, P), and mixes with method that the mass ratio of LiFePO4 is 1/50~1/5 graphene oxide through solid phase mechanical lapping.Subsequently with this mixture under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 1.
Embodiment 19
The first step with the ferrous oxalate and the lithium dihydrogen phosphate of mol ratio 1.00: 0.95~1.05, and mixes with method that the mass ratio of LiFePO4 is 1/100~1/10 Graphene through solid phase mechanical lapping.Subsequently with this mixture under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 12.
Embodiment 20
The first step is 1.00: 1.90~2.10: 1.90~2.10 lithium carbonates, ferrous oxalate and ammonium dihydrogen phosphate with mol ratio, and mixes with method that the mass ratio of LiFePO4 is 1/100~1/10 Graphene through solid phase mechanical lapping.Subsequently with this mixture under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 12.
Embodiment 21
The first step; According to Li: Fe: P=1.00: 0.95~1.05: 0.95~1.05 mol ratio is ferric phosphate, ferrous oxalate, lithium carbonate and lithium dihydrogen phosphate (proportioning between these four kinds of reaction raw materials can allotment arbitrarily under the mol ratio condition of the Li that confirms, Fe, P), and mixes with method that the mass ratio of LiFePO4 is 1/100~1/10 Graphene through solid phase mechanical lapping.Subsequently with this mixture under argon shield in 400-700 ℃ of following annealing in process 4-20 hour, obtain the compound LiFePO 4 material of Graphene.
Second step is identical with second step among the embodiment 12.
Graphene provided by the invention/iron lithium phosphate compound anode active material all is significantly improved on high power charging-discharging and cyclical stability than the LiFePO 4 material that conventional carbon coats.Described in the above embodiment is that the lithium ion battery of positive electrode active materials discharges under the high magnification of 30C with Graphene/composite ferric lithium phosphate material, and its specific capacity still maintains more than 60% (as shown in Figure 3) of the capacity of changing into; Cycle charge-discharge is 1000 times under the high magnification condition of 10C charging-20C discharge, and its capacity attenuation is less than 10%.Explained that material that embodiment obtains compares with traditional lithium ion battery and on performance, to have advantage.