A kind of dispersing technology of lithium iron phosphate positive materialTechnical field
The invention belongs to technical field of lithium ion, and in particular to a kind of LiFePO4 containing graphene conductive agent is justPole material dispersing technology.
Background technique
Ferric phosphate lithium cell is the battery made using lithium iron phosphate positive material, and ferric phosphate lithium cell has high magnification,High circulation service life, the advantage of high safety performance and low cost and no pollution to the environment are widely used in electric automobiles.WithDomestic electric vehicle industry development and country the landing of new energy electric motor vehicle subsidy policy is implemented, as electric vehicle heartLithium ion battery receive more and more attention and test；And dispatch a joint document according to Ministry of Industry and Information, the Department of Science and Technology, the Ministry of Finance " aboutTissue declares the notice of 2012 annual new-energy automobile industrial technology innovation engineering projects ", it is distinctly claimed the ratio energy of battery cellAmount reaches 150Wh/kg or more, and the specific energy to the year two thousand twenty battery cell reaches 300Wh/kg；Therefore research has higher energyThe battery of density and excellent cycling performance by be all battery Corporation R & Ds emphasis.
LiFePO 4 material possesses rhombic system olivine structural for nickel-cobalt-manganese ternary material, and lithium ion is de-After out/insertion, crystal structure hardly happens rearrangement, to possess high security performance and cycle life, becomes electronic automobile-usedThe mainstay material of battery.But its own conductivity is poor, lithium ion diffusion is slow, and general conductive agent is added and is difficult to have its capacityEffect plays；And nano-level conducting agent large specific surface area, activity are high, traditional homogenate technique can not effectively disperse, the group of be easy to causeingPoly- accumulation, manufactured battery with two side terminals not can guarantee, and are assembled into mould group and cause security risk during charge-discharge test.
The two dimensional crystal for only one layer of atomic thickness that graphene is constituted as carbon atom is that discovery conduction is led up to nowA kind of strongest novel nano-material of hot property.It is added in lithium iron phosphate positive material as conductive agent, can effectively be mentionedThe diffusion transport of high-lithium ion reduces the internal resistance of cell, so that the capacity and cycle performance of ferric phosphate lithium cell are increased substantially, it is rightThe raising of battery specific energy and the promotion of electric vehicle course continuation mileage have the improvement of essence.
Traditional lithium iron phosphate cathode slurry preparation process time is long, and nano-level conducting agent dispersion effect is poor, equipment energy consumptionGreatly, it causes cost to waste industrialized production, is unfavorable for the environmentally protective concept of electric vehicle production.
Summary of the invention
The purpose of the present invention is simultaneously, effectively shorten homogenate based on the specific energy and cycle performance for improving ferric phosphate lithium cellThe time of dispersing technology saves industrial production cost.
The present invention is implemented as follows:
A kind of dispersing technology of lithium iron phosphate positive material, specifically comprises the following steps:
Step 1: by LiFePO 4 material, conductive black (Super P-Li), graphite powder (KS-6), graphene respectively-Vacuum bakeout 8h under the conditions of 0.095MPa pressure, 120 DEG C of ± 5 DEG C of temperature.Dispersing agent (Hypermer KD-1), KynoarVacuum bakeout 3h under the conditions of -0.095MPa pressure, 80 DEG C of ± 5 DEG C of temperature respectively.After baking, be naturally cooling to 50 DEG C withLower use.
Step 2: conductive black (Super P-Li), graphite powder (KS-6), graphene are added by the mass ratio of 1:1:1In ball mill mixing tank, conductive black (Super P-Li), graphite powder (KS-6), graphene gross mass and middle or small porcelain ball it is totalMass ratio is 1:1, wherein middle porcelain bulb diameter 40mm, small porcelain bulb diameter 20mm, the mass ratio of middle or small porcelain ball are 1:1, ball mill mixingTank uses 30r/min revolving speed, disperses 30min~60min, obtains conductive agent.
Step 3: conductive agent (including conductive black (Super P-Li), graphite powder after the completion of above-mentioned steps two are dispersed(KS-6), graphene), dispersing agent and N-Methyl pyrrolidone be added in ultra micron pulverizer in 4.5:0.5:95 ratio；Ultra microGrain pulverizer uses the revolving speed of 2000r/min~2500r/min, and 10 microns~30 microns of gap carries out high-speed circulating dispersionElectrocondution slurry is made in 30min~60min.
Step 4: the ratio of electrocondution slurry in mass ratio 2%~5% made of Kynoar and above-mentioned steps three is addedEnter in planetary dispersion machine, is carried out using the revolving speed of revolution 15r/min~35r/min, rotation 1500r/min~3500r/minVacuum dispersion, jitter time are 3h~6h, and conductive rubber is made after the completion of dispersion, takes out from planetary dispersion machine.
Step 5: lithium iron phosphate positive material being added in the conductive rubber of above-mentioned preparation, and the mass ratio of addition is 30%~70%, it is put into another planetary dispersion machine, uses revolution revolving speed 15r/min~35r/min, rotation revolving speed 1000r/min~3500r/min is dispersed, jitter time 1h~4h.10% N-Methyl pyrrolidone is added after the completion of dispersion, uses public affairsWalk around fast 15r/min~35r/min, rotation revolving speed 1000r/min~3500r/min, carries out vacuum and disperses 0.5h~3h, thusThe lithium iron phosphate cathode slurry of solid content and viscosity needed for being made.
The above-mentioned Kynoar PVDF used is U.S. Solef5130.Graphene is the preparation of graphite oxide reduction methodGraphene.Dispersing agent uses the big Hypermer KD-1 of Britain's standing grain.
The beneficial effects of the present invention are:
SP, KS-6, graphene are tentatively mixed by using ball mill mixing method first, three kinds of conductive agents is made divide for the first timeDissipate mixing.
Secondly conductive agent, the dispersing agent by tentatively dispersing are added into N-methyl pyrrolidones, is crushed using ultra micronMachine carries out high speed shear with the gap of micron level, and finely dispersed conductive agent slurry is made.
Then third time dispersion is carried out using planetary dispersion machine by the way that Kynoar binder is added, after the completion of dispersionObtain conductive rubber.
Lithium iron phosphate positive material is added later, by the solid content of control slurry, carries out efficient high viscosity dispersion, fromAnd merge material of main part sufficiently with conductive agent, binder.
It ultimately joining N-methyl pyrrolidones and adjusts slurry viscosity, lithium iron phosphate cathode slurry dispersion effect obtained is good,Modest viscosity, coating performance are excellent.
Conventional commercial production method needs the dispersion Kynoar of 4~5h, and shelve 12h~carry out afterwards for 24 hours using.And conductive agent is directly added into solvent and carries out planetary dispersion, nanoscale conductive agent can not be uniformly dispersed.
The invention patent sufficiently merges by the way that conductive rubber is made in conductive agent, without shelving, substantially reduces homogenate workThe skill time reduces cost and reduces the wasting of resources.And by four dispersions, including dispersing agent change graphene surface is added and livesProperty, using the extreme shearing force continuous shear stress of ultra micron pulverizer, manufactured slurry is uniformly dispersed, and stability is good.
Detailed description of the invention
Fig. 1 is to use 5Ah soft-package battery made of a kind of dispersing technology of lithium iron phosphate positive material of the invention and makeIt is compared with the discharge capacity of the conventional batteries without containing graphene conductive agent, wherein the curve of top is using present invention process systemAt the discharge capacity of battery；
Fig. 2 is to use 5Ah soft-package battery made of a kind of dispersing technology of lithium iron phosphate positive material of the invention and makeWith 1000 discharge capacitances comparison of the conventional batteries without containing graphene conductive agent, wherein top curve is using thisDischarge capacity of the cell conservation rate is made in invented technology.
Specific embodiment
The present invention is described further with reference to the accompanying drawings and examples.
A kind of lithium iron phosphate positive material dispersing technology containing graphene conductive agent, by LiFePO 4 material, conductive charcoalBlack (Super P-Li), graphite powder (KS-6), graphene carry out 120 DEG C ± 5 DEG C, 8h, vacuum bakeout.Hypermer KD-1 gathersVinylidene carries out 80 DEG C ± 5 DEG C, 3h, vacuum bakeout.Baking reaches required temperature with temperature and starts timing, after baking,Be naturally cooling to 50 DEG C it is used below.By Super P-Li, it is mixed that ball milling is added in the ratio of KS-6, graphene 1:1:1 in mass ratioIn batch can, medium and small porcelain ball (diameter 40mm, 20mm) (ratio 1:1) is added by material ratio (1:1), uses 30r/min revolving speed, dispersion30min.By the conductive agent after the completion of above-mentioned dispersion, Hypermer KD-1, N-Methyl pyrrolidone 4.5:0.5:95 in mass ratioRatio be added in ultra micron pulverizer, using 2000r/min, 10 microns of gap carries out high-speed circulating and disperses 30min, is madeElectrocondution slurry.The ratio of Kynoar and above-mentioned manufactured electrocondution slurry 3:97 in proportion are added in planetary dispersion machine,Vacuum dispersion is carried out using the revolving speed of revolution 35r/min, rotation 3500r/min, jitter time 3h is made after the completion of dispersion and leadsElectric colloid.Lithium iron phosphate positive material is added in the conductive rubber of above-mentioned preparation, using revolution revolving speed 25r/min, is walked around certainlyFast 1000r/min is dispersed, jitter time 2h, additional proportion 6:4.A certain amount of N- methylpyrrole is added after the completion of dispersionAlkanone is carried out vacuum and is dispersed 30min using revolution revolving speed 35r/min, rotation revolving speed 3500r/min, to contain admittedly needed for being madeThe lithium iron phosphate cathode slurry of amount and viscosity.
The present invention is first by lithium iron phosphate positive material PT30 (Tianjin Sitelan Energy Science Co., Ltd) graphene (northThe self-control of capital Wanyuan Industrial Co., Ltd) conductive black (Super P-Li) graphite powder (KS-6)
(TIMCAL company).Use 120 DEG C of progress 8h bakings of vacuum drying oven (Dongguan Ke Rui mechanical & electronic equipment corporation, Ltd).It is poly-Vinylidene (U.S. Solef5130), Hypermer KD-1 (Britain's standing grain is big) carry out 80 DEG C of 3h bakings in vacuum oven.BakingReach required temperature with temperature and start timing, after baking, be naturally cooling to 50 DEG C it is used below.By Super P-Li, KS-6, graphene is added in ball mill mixing tank in the ratio of 1:1:1, by the medium and small porcelain ball of material ratio (1:1) addition (diameter 40mm,20mm) (ratio 1:1) disperses 30min using 30r/min revolving speed.By the conductive agent after the completion of above-mentioned dispersion, HypermerKD-1, N-Methyl pyrrolidone in proportion 4.5:0.5:95 ratio be added ultra micron pulverizer (Japan increase good fortune industry strain formula meetingSociety) in, using 2000r/min, 10 microns of gap carries out high-speed circulating and disperses 30min, electrocondution slurry is made.By polyvinylidene fluorideThe ratio of alkene and above-mentioned manufactured electrocondution slurry 3:97 in proportion are added in planetary dispersion machine that (the sharp electromechanical equipment of Dongguan section is limitedCompany), vacuum dispersion, jitter time 3h, after the completion of dispersion are carried out using the revolving speed of revolution 35r/min, rotation 3500r/minConductive rubber is made.Lithium iron phosphate positive material PT3 is added in the conductive rubber of above-mentioned preparation, uses revolution revolving speed 25r/Min, rotation revolving speed 1000r/min are dispersed, jitter time 2h, additional proportion 6:4.It is added after the completion of dispersion a certain amount ofN-Methyl pyrrolidone is carried out vacuum and is dispersed 30min, vacuum degree using revolution revolving speed 35r/min, rotation revolving speed 3500r/min(- 0.095MPa), it is 40%~50% that obtained anode sizing agent contains admittedly, viscosity 3000mpa~8000mpa；Use 150 mesh screensIt is sieved, final lithium iron phosphate cathode slurry dispersion consistency obtained is excellent, and finished battery is functional.
The present invention is using 5Ah soft-package battery made of the dispersing technology and uses the conventional electricity without containing graphene conductive agentPond performance comparison is as shown in table 1, and discharge capacity compares as shown in Figure 1:
The comparison of 1 battery performance of table
It is recycled and is compared using 5Ah soft-package battery made of the dispersing technology and conventional 5Ah soft-package battery, 1C charge and dischargeFor 1000 capacity retention ratios 99.5%, conventional batteries capacity retention ratio is 91.6%.Cyclic curve is as shown in Figure 2.
Implementation method of the invention is explained in detail above in conjunction with embodiment, but the present invention is not limited to above-mentioned realitiesExample is applied, it within the knowledge of a person skilled in the art, can also be without departing from the purpose of the present inventionVarious changes can be made.The content that description in the present invention is not described in detail can use the prior art.