CN102723465B - Preparation method of porous LiFePO4 bulk electrode for lithium ion batteries - Google Patents
Preparation method of porous LiFePO4 bulk electrode for lithium ion batteries Download PDFInfo
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- CN102723465B CN102723465B CN201110159883.7A CN201110159883A CN102723465B CN 102723465 B CN102723465 B CN 102723465B CN 201110159883 A CN201110159883 A CN 201110159883A CN 102723465 B CN102723465 B CN 102723465B
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- 238000002360 preparation method Methods 0.000 title claims abstract description 24
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 18
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 18
- 229910052493 LiFePO4 Inorganic materials 0.000 title abstract 5
- 238000000034 method Methods 0.000 claims abstract description 51
- 230000008569 process Effects 0.000 claims abstract description 22
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 12
- 239000007772 electrode material Substances 0.000 claims abstract description 12
- 239000002245 particle Substances 0.000 claims abstract description 12
- 238000003825 pressing Methods 0.000 claims abstract description 7
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 238000009766 low-temperature sintering Methods 0.000 claims abstract description 3
- 229910010707 LiFePO 4 Inorganic materials 0.000 claims description 30
- 229910010710 LiFePO Inorganic materials 0.000 claims description 22
- 239000000126 substance Substances 0.000 claims description 22
- 239000011148 porous material Substances 0.000 claims description 20
- 239000007789 gas Substances 0.000 claims description 19
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 16
- 238000005229 chemical vapour deposition Methods 0.000 claims description 16
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 14
- 239000000843 powder Substances 0.000 claims description 12
- 229910052786 argon Inorganic materials 0.000 claims description 8
- 238000007599 discharging Methods 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 229910052757 nitrogen Inorganic materials 0.000 claims description 7
- 239000001257 hydrogen Substances 0.000 claims description 6
- 229910052739 hydrogen Inorganic materials 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 229920000877 Melamine resin Polymers 0.000 claims description 5
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical group NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 claims description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 230000001681 protective effect Effects 0.000 claims description 4
- 238000005245 sintering Methods 0.000 claims description 4
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 claims description 3
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 claims description 3
- 239000003595 mist Substances 0.000 claims description 3
- 238000007493 shaping process Methods 0.000 claims description 3
- 238000010792 warming Methods 0.000 claims description 3
- 238000013461 design Methods 0.000 claims description 2
- 150000002431 hydrogen Chemical class 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims description 2
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims description 2
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 claims description 2
- 238000010926 purge Methods 0.000 claims description 2
- 238000004062 sedimentation Methods 0.000 claims description 2
- 239000000853 adhesive Substances 0.000 abstract description 15
- 230000001070 adhesive effect Effects 0.000 abstract description 15
- 239000002904 solvent Substances 0.000 abstract description 6
- 238000012512 characterization method Methods 0.000 abstract description 4
- 239000012528 membrane Substances 0.000 abstract description 3
- 229910019142 PO4 Inorganic materials 0.000 abstract description 2
- 239000011248 coating agent Substances 0.000 abstract description 2
- 238000000576 coating method Methods 0.000 abstract description 2
- 239000003960 organic solvent Substances 0.000 abstract description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 abstract description 2
- 239000010452 phosphate Substances 0.000 abstract description 2
- 239000010406 cathode material Substances 0.000 abstract 2
- 239000005416 organic matter Substances 0.000 abstract 1
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 12
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000002202 Polyethylene glycol Substances 0.000 description 5
- 239000011149 active material Substances 0.000 description 5
- 230000004087 circulation Effects 0.000 description 5
- 239000003792 electrolyte Substances 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 239000010408 film Substances 0.000 description 4
- 229920001223 polyethylene glycol Polymers 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 239000006258 conductive agent Substances 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000005518 electrochemistry Effects 0.000 description 2
- 239000011267 electrode slurry Substances 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 2
- 229910052753 mercury Inorganic materials 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- OWEGMIWEEQEYGQ-UHFFFAOYSA-N 100676-05-9 Natural products OC1C(O)C(O)C(CO)OC1OCC1C(O)C(O)C(O)C(OC2C(OC(O)C(O)C2O)CO)O1 OWEGMIWEEQEYGQ-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 235000007926 Craterellus fallax Nutrition 0.000 description 1
- 240000007175 Datura inoxia Species 0.000 description 1
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- GUBGYTABKSRVRQ-PICCSMPSSA-N Maltose Natural products O[C@@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@@H]1[C@@H](CO)OC(O)[C@H](O)[C@H]1O GUBGYTABKSRVRQ-PICCSMPSSA-N 0.000 description 1
- 241000235342 Saccharomycetes Species 0.000 description 1
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 description 1
- 229930006000 Sucrose Natural products 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000005030 aluminium foil Substances 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229960005070 ascorbic acid Drugs 0.000 description 1
- 235000010323 ascorbic acid Nutrition 0.000 description 1
- 239000011668 ascorbic acid Substances 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 description 1
- GUBGYTABKSRVRQ-QUYVBRFLSA-N beta-maltose Chemical compound OC[C@H]1O[C@H](O[C@H]2[C@H](O)[C@@H](O)[C@H](O)O[C@@H]2CO)[C@H](O)[C@@H](O)[C@@H]1O GUBGYTABKSRVRQ-QUYVBRFLSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000002848 electrochemical method Methods 0.000 description 1
- PQVSTLUFSYVLTO-UHFFFAOYSA-N ethyl n-ethoxycarbonylcarbamate Chemical compound CCOC(=O)NC(=O)OCC PQVSTLUFSYVLTO-UHFFFAOYSA-N 0.000 description 1
- 239000008103 glucose Substances 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- GLXDVVHUTZTUQK-UHFFFAOYSA-M lithium hydroxide monohydrate Substances [Li+].O.[OH-] GLXDVVHUTZTUQK-UHFFFAOYSA-M 0.000 description 1
- 229940040692 lithium hydroxide monohydrate Drugs 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 239000012429 reaction media Substances 0.000 description 1
- 230000000306 recurrent effect Effects 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000002336 sorption--desorption measurement Methods 0.000 description 1
- 239000005720 sucrose Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Classifications
-
- 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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- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention, relating to the field of lithium ion batteries, belongs to a preparation technique of phosphate bulk electrodes and an accurate electrode material characterization technique, particularly discloses a preparation method of a porous LiFePO4 bulk electrode containing no adhesive and no organic solvent for lithium ion batteries. The invention is suitable for improving high capacity bulk electrodes and let the characteristics of electrode material performance be predicted accurately. The method comprises the following steps: mixing a certain amount of cathode materials with organic matter, and carrying out cold pressing into blocks; then acquiring a positive bulk electrode with a porous structure by low temperature sintering, or simultaneously uniformly coating the surface of the porous LiFePO4 particles with a layer of continuous conductive carbon film to obtain excellent conductivity. According to the invention, the problems of long and complex process of conventionally preparing LiFePO4 positive plates, need of various process equipment, and expensive adhesives and solvents for dissolving the adhesives are solved; on that basis, the problem that the use of membrane electrodes predicts the electrochemical performance of the LiFePO4 cathode materials inaccurately in conventional characterization is solved.
Description
Technical field
The present invention relates to field of lithium ion battery, belong to technology of preparing and the electrode material characterization technique accurately of phosphate type bulk electrode, be specially a kind of not containing the lithium ion battery porous LiFePO of any adhesive and organic solvent
4the preparation method of bulk electrode, is applicable to improve Large Copacity bulk electrode and energy accurate Characterization electrode material performance.
Background technology
Along with the continuous progress of human living standard, people increase day by day to the serious hope possessing high power capacity small size battery.Lithium battery is the battery of the performance that in the secondary chemical sources of electric energy of all commercialization uses so far, energy density is the highest, but himself capacity less than normal still can not meet the requirement of large scale equipment.Therefore, a large amount of in recent years scientific research energy is used for the electrode that research and development have high power capacity (energy) low cost.But, be subject to the electrode fabrication of traditional and complexity and coarse electrochemical Characterization means, lithium ion battery overall performance improved further and is restricted.
Lithium ion battery by positive pole, negative pole, barrier film and electrolyte four part form.For traditional electrode preparation technology, positive active material and negative electrode active material are coated in the metal forming as collector, and usually, aluminium foil is as positive collector, and Copper Foil is as negative collector.As shown in Fig. 1 (a), traditional LiFePO
4the preparation flow of positive plate comprises: mixing LiFePO
4slurrying → coating → roll-in → cutting → the drying of positive electrode, conductive agent, adhesive, obtains LiFePO
4positive plate.This technological process is complicated, and need adhesive and kinds of processes equipment, electrode manufacturing cost is high, refers to document Nature 414,359-367, described in (2001).
In laboratory, go out corresponding less thin-film electro pole piece by by the membrane electrode punch prepared by conventional preparation techniques.The amount of the active material contained by this pole piece is generally no more than 5mg/cm
2, therefore very harsh to the requirement of electronic balance.Add the thick insulating polymer glue prepared needed for electrode slurry, further difficulty is brought to accurate proportioning electrode slurry.So, the chemical property symbolized by above-mentioned conventional method and easily cause larger error.
Summary of the invention
The object of the present invention is to provide a kind of do not use organic bond and metal collector for the preparation of lithium ion battery porous LiFePO
4the method of bulk electrode.The method significantly improves the chemical property of bulk electrode, shortens conventional process flow, solves conventional preparation LiFePO
4the technique of positive plate redundant and complicated, needs the problem of the solvent of plurality of devices and expensive adhesive and dissolved adhesive.Further, the amount of contained in unit volume active material gets a promotion greatly.Therefore, can the chemical property of more accurate exosyndrome material intrinsic.
Technical scheme of the present invention is:
As shown in Fig. 1 (b), the present invention is by Homogeneous phase mixing LiFePO
4after organic substance, then make it shaping by the method for cold moudling.Low-temperature sintering, makes LiFePO
4positive electrode and LiFePO
4particle is connected to each other and forms loose structure simultaneously, or will form the LiFePO of loose structure again
4particle surface obtains porous, electrically conductive LiFePO by the even coated one deck conductive carbon film of the method for chemical vapour deposition (CVD)
4bulk electrode.Its concrete steps are as follows:
(1) electrode material LiFePO is synthesized
4powder, mixed uniformly with organic substance pore creating material by powder subsequently, organic substance accounts for the 0wt%-90wt% (being preferably 30wt%-60wt%) of mixture gross mass, by the dried powder cold moudling in a mold mixed, cold pressing pressure 1-500MPa, colds pressing time 1-6000 second.
Synthesize electrode material LiFePO
4the process of powder is routine techniques, refers to document Nature 414,359-367, (2001).
(2) block of forming is put into the flat-temperature zone of tube furnace, protective gas is passed into after discharging furnace air subsequently, then within after being warming up to design temperature 200-400 DEG C constant temperature 10-60 minute, carry out drainage sunk well and form loose structure, the technical parameter of loose structure: porosity 10%-99% (being preferably 50-90%), there is macroporous structure, central hole structure and microcellular structure, the volume fraction of the whole pore volumes shared by macroporous structure is 1%-99% (being preferably 30-60%), the volume fraction of the whole pore volumes shared by central hole structure is 1%-99% (being preferably 30-60%), all the other are microcellular structure, 50nm-500 μm, macroporous structure aperture (macroporous structure aperture is not containing 50nm), central hole structure aperture 2-50nm, microcellular structure aperture is less than 2nm.After temperature rises to 500-800 DEG C subsequently, within constant temperature 10-180 minute, carry out sintering processes.
Or pass into carbon-source gas again and carry out chemical vapour deposition (CVD), to form the LiFePO of loose structure
4the even coated one deck conductive carbon of particle surface obtains porous, electrically conductive LiFePO
4bulk electrode, the thickness of conductive carbon is: 1-100nm.
The parameter of chemical vapour deposition (CVD) is as follows:
Carbon source gas volumetric percentage is 1-20%, chemical vapour deposition (CVD) temperature 500-800 DEG C, sedimentation time 10 minutes-3 hours; Post-depositional sample naturally cools to room temperature with stove, takes out and obtains porous, electrically conductive LiFePO
4bulk electrode.
In the present invention, organic substance is the one or more kinds of mixtures of citric acid, melamine, saccharomycete, glucose, sucrose, maltose.
In the present invention, the LiFePO used
4particle diameter be 10nm-100 μm.
In the present invention, described tube furnace is horizontal type stove or shaft (tower) furnace.
In the present invention, the mode of described discharge furnace air and water vapour is for vacuumizing or using inert gas purge.
In the present invention, step (2) described carbon-source gas is acetylene or propylene.
In the present invention, described protective gas is one of nitrogen, argon gas, or the mist of one of nitrogen, argon gas and hydrogen, and the volume ratio of nitrogen or argon gas and hydrogen is 1: (10-0).
Advantage of the present invention is:
1, first the present invention prepares electrode material, subsequently by electrode material and quantity of organic Homogeneous phase mixing, then by the method for cold moudling by its briquet.Subsequently by the loose structure block that the block pressed obtains containing a large amount of electrode material powder by low sintering method, or simultaneously by the method for chemical vapour deposition (CVD) by the LiFePO of loose structure
4the conductive carbon film of particle surface coated one deck uniformly continous obtains the more excellent bulk electrode of conductivity.Bulk electrode prepared by the present invention, only containing a large amount of active materials and a small amount of conductive agent, therefore can be avoided in experimentation owing to measuring the experimental error that balance inaccuracy is brought.
2, the inventive method does not use organic binder bond, without the need to the solvent of dissolved adhesive, and without the need to using metal collector, therefore greatly can save cost.
3, present invention process process and simple, simplifies the manufacture process of electrode, therefore reduce further the manufacturing cost of electrode.
4, the inventive method can use nano-electrode material to prepare bulk electrode containing different size pore structure, therefore significantly can improve the chemical property of bulk electrode.
5, the electrode that prepared by the present invention does not use organic bond, and specific discharge capacity comparatively traditional preparation methods is high.And prepared bulk electrode tool high power capacity, the features such as high-energy-density.
6, by the porous blocks electrode prepared by the inventive method, after the circulation of electrochemistry several times, electrolyte can completely and active contacts, and therefore drawn chemical property is accurate.
In a word, the bulk electrode good conductivity adopting the method to prepare, in unit volume electrode charge/discharge capacity and specific capacity is high, preparation technology simple, bulk electrode low cost of manufacture, and considerably improve the chemical property of bulk electrode and shorten the preparation flow of traditional handicraft, solving conventional preparation LiFePO
4the operation of positive plate redundant and complicated, needs the problem of the solvent of kinds of processes equipment and expensive adhesive and dissolved adhesive.On this basis, solve tradition and characterize use membrane electrode to characterize LiFePO
4the coarse problem of positive electrode chemical property.
Accompanying drawing explanation
Fig. 1 is that the present invention compares with conventional process flow.Wherein, (a) is conventional process flow; B () is present invention process flow process.
Fig. 2 is porous, electrically conductive LiFePO in embodiment 1
4the stereoscan photograph of bulk electrode, display bulk electrode is cellular and even pore distribution.
The porous, electrically conductive LiFePO that Fig. 3 obtains for embodiment 1
4the transmission photo of positive pole block.
Fig. 4 is that the bulk electrode of embodiment 1 is carried out: (a) nitrogen adsorption desorption curve and (b) Mercury injection.
The battery that assembles of the bulk electrode that Fig. 5 is embodiment 1 is under different cycle-index: (a) Nyquist schemes and the graph of a relation of bearing two/first power of (b) impedance and frequency.
Fig. 6 is the bulk electrode chemical property of embodiment 1: (a) charging and discharging curve under different current status and (b) cycle performance.
Fig. 7 is the bulk electrode chemical property of embodiment 2: (a) charging and discharging curve under different current status and (b) cycle performance.
Fig. 8 is the bulk electrode chemical property of embodiment 3: (a) charging and discharging curve under different current status and (b) cycle performance.
Fig. 9 (a)-(b) is the stereoscan photograph of block in embodiment 4, shows the bulk electrode gone out synthesized by the method by embodiment 4 and presents a fairly large number of mesopore (a) and macroporous structure (b).
Figure 10 is the chemical property of bulk electrode in embodiment 4: (a) charging and discharging curve under different current status and (b) cycle performance.
Embodiment
Embodiment 1:
Choose 6.69g Lithium hydroxide monohydrate, be dissolved in 30mL water.To be dissolved complete after, add 4mL phosphoric acid (concentration is 85wt%) to it, now generate Li
3pO
4suspension-turbid liquid.After question response completes, add 0.225g ascorbic acid and 14.6g ferrous sulfate heptahydrate to it, the blue slurry of final formation.In mixture, introduce 20mL polyethylene glycol (200) more subsequently, make polyethylene glycol (200) remain 2: 4 with the volume ratio of water.Blue slurry is transferred to rapidly in sealed reactor 180 DEG C of hydro-thermal reactions 1 hour.Then be separated, obtain single-phase LiFePO
4; In the present embodiment, LiFePO
4the particle diameter of powder is 50-500nm.
Get dried LiFePO
4powder 2g, with 1g citric acid Homogeneous phase mixing in grinding.Subsequently by the dried powder mixed by be placed on Φ 8mm mould in cold moudling, pressure of colding pressing is 100MPa, and the time of colding pressing is 30 seconds.Block after shaping is placed into the flat-temperature zone of tube furnace, then half an hour (vacuum degree reaches about 10Pa) is vacuumized, after discharging the air in stove, pass into the mist of high-purity argon gas (bulk purity >=99.999%) and hydrogen again, the volume ratio of argon gas and hydrogen is 1: 0.03, after being warming up to 350 DEG C, constant temperature carries out drainage sunk well in 1 hour, the water that citric acid pyrolysis is gone out fully is discharged, form loose structure simultaneously, the technical parameter of loose structure: porosity 58.8%, there is macroporous structure, central hole structure and microcellular structure, the volume fraction of the whole pore volumes shared by macroporous structure is 41%, the volume fraction of the whole pore volumes shared by central hole structure is 42%, all the other are microcellular structure, macroporous structure aperture 90nm-3 μm, central hole structure aperture 2-50nm, microcellular structure aperture is less than 2nm.After end temperature rises to 700 DEG C, constant temperature carries out sintering processes in 30 minutes, RESEARCH OF PYROCARBON can be made to have more excellent electrical conductance simultaneously.Pass into acetylene gas subsequently, and continue insulation 30 minutes at 700 DEG C, carry out the process of bag carbon.After temperature retention time terminates, sample cools to room temperature with the furnace, takes out and obtains porous, electrically conductive LiFePO
4bulk electrode (Fig. 2).
The quality of this bulk electrode and volume for not reach ~ 52.7mg and ~ 50mm
3.And form the active material particle sintered bond each other of this bulk electrode, and have ~ homogeneous continuously the conductive carbon film (Fig. 3) of 3nm.By to LiFePO
4bulk electrode carries out absorption attaching and Mercury injection, draws LiFePO
4there is macropore and central hole structure in bulk electrode, and porous nickel is distributed in bulk electrode (Fig. 4).Make positive pole with this bulk electrode, use lithium metal as battery cathode, be assembled into 2032 button cells, after different recurrent state, ac resistance analysis is carried out to this battery.Result shows (Fig. 5) after primary electrochemical circulation, is no matter lithium ion diffusion coefficient or the electronic conductance of electrode are obtained for obvious lifting, but the then change that circulates again is little.Represent that the bulk electrode by going out synthesized by the method can be able to make electrolyte infiltrate into electrode interior completely by once circulating.By this battery constant current charge-discharge under 0.443mA electric current, this porous, electrically conductive LiFePO
4bulk electrode has good charge and discharge platform, and (Fig. 6 a).Discharge capacity is up to 8.22mAh first, is more than 100 times that conventional method prepares the battery capacity measured by pole piece.And specific capacity also reaches the 158mAh/g close to theoretical capacity.Illustrate, according to the electrode prepared by this method, there is high capacity and specific capacity, and measured data are accurate.Along with electric current be increased to 0.886mA time, the discharge capacity first of this bulk electrode is reach 7.97mAh, and specific capacity also reaches 153mAh/g.Fig. 6 b is the chemical property of this bulk electrode under different current status.As seen from the figure, this electric bulk electrode shows good electrochemistry cycle performance under the current status of 0.443mA and 0.886mA.
Embodiment 2:
Difference from Example 1 is, synthesis LiFePO
4polyethylene glycol (200) is not added in process.But using water as reaction medium completely, the amount of water used is 60mL.Other conditions are all same as embodiment 1, in the present embodiment, and porosity 61%, there is macroporous structure, central hole structure and microcellular structure, the volume fraction of the whole pore volumes shared by macroporous structure is 46%, and the volume fraction of the whole pore volumes shared by central hole structure is 43%, and all the other are microcellular structure; Macroporous structure aperture 90nm-5 μm, central hole structure aperture 2-50nm, microcellular structure aperture is less than 2nm.
From Fig. 7 a, under 0.425mA constant current charge-discharge condition, this discharge capacity of the cell is up to 7.24mAh, and specific capacity also reaches 144mAh/g.Illustrate, according to the electrode prepared by this method, there is high capacity and specific capacity, and measured data are accurate.Along with electric current be increased to 0.851mA time, the discharge capacity first of this bulk electrode still reaches 6.91mAh, and specific capacity also reaches 138mAh/g.This battery decays (Fig. 7 b) without obvious after experienced by 20 circulations.Embody, by the bulk electrode prepared by the method, there is good cycle performance.
Embodiment 3
Difference from Example 1 is, synthesis LiFePO
4in process to add the amount of polyethylene glycol (200) different.
Polyethylene glycol: the volume ratio of water is 1: 1, and other conditions are all same as embodiment 1.In the present embodiment, porosity 56.5%, has macroporous structure, central hole structure and microcellular structure, and the volume fraction of the whole pore volumes shared by macroporous structure is 39%, and the volume fraction of the whole pore volumes shared by central hole structure is 46%, and all the other are microcellular structure; Macroporous structure aperture 80nm-2 μm, central hole structure aperture 2-50nm, microcellular structure aperture is less than 2nm.
From Fig. 8 a, under 0.425mA constant current charge-discharge condition, this discharge capacity of the cell is up to 7.36mAh, and specific capacity also reaches 147mAh/g.Illustrate, according to the electrode prepared by this method, there is high capacity and specific capacity, and measured data are accurate.Along with electric current be increased to 0.851mA time, the discharge capacity first of this bulk electrode still reaches 7.25mAh, and specific capacity also reaches 145mAh/g.This battery decays (Fig. 8 b) without obvious after experienced by 20 circulations.
Embodiment 4
Difference from Example 1 is, the pore creating material added is melamine.
Other conditions are all same as embodiment 1.In the present embodiment, the technical parameter of loose structure: porosity 68.1%, has macroporous structure, central hole structure and microcellular structure, and the volume fraction of the whole pore volumes shared by macroporous structure is 47%, the volume fraction of the whole pore volumes shared by central hole structure is 45%, and all the other are microcellular structure; Macroporous structure aperture 50nm-10 μm, central hole structure aperture 2-50nm, microcellular structure aperture is less than 2nm.
As shown in Figure 9, by selecting melamine to be pore creating material, macroporous structure can be produced in bulk electrode.From Figure 10 a, under 0.432mA and 0.863mA constant current charge-discharge condition, this discharge capacity of the cell is up to 8.28mAh, and specific capacity also reaches 163mAh/g.Illustrate, according to the electrode prepared by this method, there is high capacity and specific capacity, and measured data are accurate.Along with electric current be increased to 1.725mA time, the discharge capacity first of this bulk electrode still reaches 7.41mAh, and specific capacity also reaches 146mAh/g.This battery decays (Figure 10 b) without obvious after experienced by 15 circulations.This example explanation, compared with citric acid, by using melamine to contain the pore structure compared with horn of plenty as the bulk electrode prepared by pore creating material, therefore make electrolyte enter the inside of bulk electrode smoothly, thus improve the charge-discharge magnification performance of bulk electrode further.
Embodiment result shows, the present invention can prepare porous, electrically conductive LiFePO when not using the solvent of any adhesive, dissolved adhesive and collector
4bulk electrode.Adopt the bulk electrode good conductivity prepared of the method, density is high, and the charge/discharge capacity of bulk electrode and specific capacity high.Present invention process is simple, the low cost of manufacture of bulk electrode, and the preparation flow shortening traditional handicraft greatly, solves conventional preparation LiFePO
4the technique of positive plate redundant and complicated, need kinds of processes equipment and expensive adhesive, the solvent of dissolved adhesive and the problem of collector.And there is in its unit volume the feature of the amount of high active material, making it when characterizing the chemical property of electrode material, have and very accurately wait various features.
Claims (8)
1. a lithium ion battery porous LiFePO
4the preparation method of bulk electrode, is characterized in that, by Homogeneous phase mixing LiFePO
4after organic substance, then make it shaping by the method for cold moudling; Low-temperature sintering, makes LiFePO
4positive electrode and LiFePO
4particle is connected to each other and forms loose structure simultaneously, then will form the LiFePO of loose structure
4particle surface obtains porous, electrically conductive LiFePO by the even coated one deck conductive carbon film of the method for chemical vapour deposition (CVD)
4bulk electrode, its concrete steps are as follows:
(1) electrode material LiFePO is synthesized
4powder, LiFePO
4the particle diameter of powder is 50-500 nm; Mixed uniformly with organic substance pore creating material by powder subsequently, organic substance accounts for 30 wt%-60 wt% of mixture gross mass, by the dried powder cold moudling in a mold mixed;
Described organic substance is melamine;
(2) block of forming is put into the flat-temperature zone of tube furnace, pass into protective gas after discharging furnace air subsequently, within after being then warming up to design temperature 200-400 DEG C constant temperature 10-60 minute, carry out drainage sunk well and form loose structure; After temperature rises to 500-800 DEG C subsequently, within constant temperature 10-180 minute, carry out sintering processes;
In described step (2), the technical parameter of loose structure: porosity 10 %-99 %, there is macroporous structure, central hole structure and microcellular structure, the volume fraction of the whole pore volumes shared by macroporous structure is 1 %-99 %, the volume fraction of the whole pore volumes shared by central hole structure is 1 %-99 %, and all the other are microcellular structure; Macroporous structure aperture 50 nm-500 μm, central hole structure aperture 2-50 nm, microcellular structure aperture is less than 2 nm;
After described step (2), pass into carbon-source gas and carry out chemical vapour deposition (CVD), to form the LiFePO of loose structure
4the even coated one deck conductive carbon of particle surface obtains porous, electrically conductive LiFePO
4bulk electrode.
2. according to lithium ion battery porous LiFePO according to claim 1
4the preparation method of bulk electrode, is characterized in that: the thickness of conductive carbon is: 1-100 nm.
3. according to the lithium ion battery porous LiFePO described in claims 1
4the preparation method of bulk electrode, is characterized in that: carbon source gas volumetric percentage is 1-20 %, chemical vapour deposition (CVD) temperature 500-800 DEG C, sedimentation time 10 minutes-3 hours; Post-depositional sample naturally cools to room temperature with stove, takes out and obtains porous, electrically conductive LiFePO
4bulk electrode.
4. according to the lithium ion battery porous LiFePO described in claims 1
4the preparation method of bulk electrode, is characterized in that: carbon-source gas is acetylene or propylene.
5. according to the lithium ion battery porous LiFePO described in claims 1
4the preparation method of bulk electrode, is characterized in that: in described step (2), and tube furnace is horizontal type stove or shaft (tower) furnace.
6. according to the lithium ion battery porous LiFePO described in claims 1
4the preparation method of bulk electrode, is characterized in that: in described step (2), and the mode of furnace air and water vapour of discharging is for vacuumizing or using inert gas purge.
7. according to the lithium ion battery porous LiFePO described in claims 1
4the preparation method of bulk electrode, is characterized in that: in described step (2), and protective gas is one of nitrogen, argon gas, or the mist of one of nitrogen, argon gas and hydrogen, and the volume ratio of nitrogen or argon gas and hydrogen is 1:(10-0).
8. according to the lithium ion battery porous LiFePO described in claims 1
4the preparation method of bulk electrode, is characterized in that: in described step (1), and cold pressing pressure 1-500 MPa, colds pressing time 1-6000 second.
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| CN104730292B (en) * | 2015-02-12 | 2017-10-24 | 天津力神电池股份有限公司 | A kind of preparation of embedding lithium state negative pole electron microscopic sample of lithium ion battery and observation procedure |
| CN106450217B (en) * | 2016-11-07 | 2020-08-04 | 珠海格力电器股份有限公司 | Method for modifying nickel cobalt lithium manganate ternary material |
| KR102160710B1 (en) * | 2017-07-04 | 2020-09-28 | 주식회사 엘지화학 | Electrode and Lithium Secondary Battery Comprising the Same |
| CN108258199B (en) * | 2018-01-19 | 2020-09-01 | 河北力滔电池材料有限公司 | Lithium iron phosphate composite pole piece and preparation method thereof |
| CN110858641B (en) * | 2018-08-22 | 2021-04-20 | 比亚迪股份有限公司 | Positive electrode material of lithium ion battery, preparation method of positive electrode material and lithium ion battery |
| CN113991070A (en) * | 2021-09-14 | 2022-01-28 | 陕西创普斯新能源科技有限公司 | Lithium iron phosphate composite material and preparation method and application thereof |
| CN115159589A (en) * | 2021-09-23 | 2022-10-11 | 贵州振华新材料有限公司 | Lithium ion battery anode material, preparation method and application |
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