The preparation method of artificial graphite charcoal negative electrode material and the artificial graphite charcoal negative electrode material that makes
Technical field
The present invention relates to a kind of carbon cathode material and preparation method thereof, relate in particular to a kind of preparation method and artificial graphite charcoal negative electrode material obtained by this method of artificial graphite charcoal negative electrode material.
Background technology
From Sony corporation of Japan in 1991 succeed in developing be the lithium ion battery of negative pole with the raw material of wood-charcoal material since, the lithium ion battery industry develops rapidly, widely applies on mobile telephone, pick up camera, notebook computer and portable electronics.Lithium ion battery has that operating voltage height, volume are little, light weight, specific energy height, memory-less effect, pollution-free, characteristics such as self-discharge is little, have extended cycle life, and is the desirable energy of 21 century development.
The carbon cathode material of lithium-ion secondary cell mainly is graphite microparticles at present.Wherein, natural graphite has the ideal laminate structure, have very high electrical capacity (>350mAh/g), be easy to compacting (>1.60g/cm
3), but there is structural instability in it, easily causes the common insertion of solvent molecule, and its synusia in charge and discharge process is come off, and causes cycle performance of battery poor, poor stability.Common graphous graphite powder out-of-shape, specific surface area is big (common>5m
2/ g), causing the materials processing poor performance, efficient is low first.Special synthetic graphite-greying MCMB, Stability Analysis of Structures, the little (<2.0m of specific surface area
2/ g), and good cycle, security is good, so for a long time always in occupation of lithium ion carbon cathode material market, but its cost of manufacture height, the reversible lithium storage capacity is only about 310mAh/g.And the lithium storage content of other most artificial plumbago negative pole material is generally only about 300mAh/g, indivedual artificial plumbago negative pole materials of heavy body slightly, and it is big also to exist specific surface area, ash content big (>0.10%), shortcomings such as unstable properties, LiC in theory
6The reversible lithium storage capacity reach 372mAh/g, the capacity of negative material should also have the very big rising space.
Fast development along with global electronic information industries such as mobile communication, laptop computer, digital vedio recordings, various products improve constantly the requirement of miniaturization, lightweight and multi-functional, long-time drivingization, the requirement to lithium-ion secondary cell naturally and understandably also improves gradually, and is urgent day by day to the requirement of large vol, rapid charge, the contour performanceization of high-level efficiency.Therefore, for a long time, improve lithium ion battery negative material, the particularly specific storage of synthetic graphite class, reduce specific surface area, reduce first irreversible capacity and improve the emphasis that cyclical stability is research and development always.Particularly the modification for synthetic graphite has proposed many methods.
For example: liquid-phase oxidation or gaseous oxidation processing are carried out in the synthetic graphite surface, but the former cost height, and a large amount of waste liquids produce problem of environmental pollution, the latter then step is more, be primarily aimed at MCMB, cost higher (be referring to the applicant's application number 200310108402.5 Chinese patent application).Japanese documentation JP9-330703 has described the manufacture method of lithium ion secondary battery cathode, the material of making negative pole is the plain matrix material of synthetic graphite-charcoal, the preparation method of this matrix material is dissolved in the organism matrix material in the excessive solvent, after the graphite crystallization micropowder mixes, evaporation removes and desolvates, and forms the composition of graphite and organic binding material.Above-mentioned composition burnt till under inert atmosphere or non-oxidizing atmosphere contain the compound carbon material that graphite-charcoal element is arranged by the organic binding material charing, do not need to pulverize with graphite-carbonaceous product that this method generated, but the initial stage loading capacity is low, about 240mAh/g, and the initial stage cyclical stability is poor.And adopt existing method lower by the productive rate that synthetic graphite prepares carbon cathode material, be generally less than 100%.
Summary of the invention
One of purpose of the present invention is in order to solve above-mentioned problem, and the preparation method of the higher artificial graphite charcoal negative electrode material of a kind of environmental protection, productive rate is provided.
The preparation method of a kind of artificial graphite charcoal negative electrode material of the present invention, it comprises the steps:
1. reinforced: as alternately to add weight ratio while stirring and be 1.5~19: 1 synthetic graphite micro mist and pitch, add the material back and continue to stir 0.5~3 hour, then in 10~50 minutes, add the reaction promoter that accounts for graphite microparticles and pitch gross weight 4~20%;
2. heat up: begin simultaneously to heat up adding solvent, require to be warming up to 500~600 ℃ in 4~10 hours, wherein negative pressure extracts light constituent in the above-mentioned material after beginning to heat up 1~2 hour;
3. constant temperature: 500~600 ℃ of constant temperature 3~8 hours, negative pressure extracted heavy constituent and the reaction promoter in the above-mentioned material simultaneously;
4. be cooled to room temperature;
5. greying;
Wherein, the step after adding graphite and pitch is all carried out under protection against oxidation.
Above-mentioned preparation method in fact also is a kind of surface modification technology of raw material of wood-charcoal material raw material, particularly synthetic graphite.Wherein, the synthetic graphite of step described in 1. is meant any common artificial graphite microparticles that can be used as carbon cathode material in the prior art, as the still irregular common artificial graphite microparticles of form such as Graphite Electrodes, greying refinery coke and greying coal-tar pitch Jiao, its particle diameter (D
50) generally at 6~40 mu m ranges, preferred 10-30 μ m, more preferably 14-24 μ m, its specific surface area is no more than 8m
2/ g, preferred 4~7m
2/ g;
Described pitch is meant the various pitches that now are applicable to preparation carbon cathode material field, as petroleum pitch and/or coal-tar pitch, its in technology of the present invention as surface-modifying agent;
And described reaction promoter is meant solubilized surface-modifying agent pitch, so that the mixed uniformly preferably solvent of synthetic graphite raw material and pitch.For ease of from reaction product, removing recycling, can adopt the naphthenic hydrocarbon and/or the aromatic solvent that can gasify below 400 ℃, as carbolineum, washing oil, benzene,toluene,xylene etc., from environmental protection and cost consideration, the preferred industrial washing oil of the present invention, carbolineum etc.
Synthetic graphite and bituminous ratio are too high among the preparation method of the present invention, particularly surpass 19: 1, and then artificial graphite surface modifying is handled not thorough, the carbon cathode material specific surface area that makes is too big, granularity is inhomogeneous, and consistence is poor, and the cycle performance of battery and safety performance etc. are made in influence; And ratio is too low, particularly is lower than 1.5: 1, and then pitch is too much, and the carbon cathode material loading capacity of making reduces.
On the other hand, the consumption of reaction promoter is too many, and the ratio that particularly accounts for graphite and pitch gross weight surpasses 20%, and then reaction mass is dispersed relatively poor, can not uniform mixing, and increase the intensity and the cost of recovery; And consumption is very little, and the ratio that particularly accounts for graphite and pitch gross weight is lower than 4%, and then reaction mass is dispersed relatively poor, can not uniform mixing, do not have promoter effect.
And the temperature of technology of the present invention is too low and/or the time is too short, can make the reaction of surface modification complete inadequately; Otherwise temperature is too high and/or the time is oversize, then may make overreact; All influence the performance of the finished product.
In a preferred embodiment of the present invention, 1. middle synthetic graphite micro mist of above-mentioned steps and bituminous weight ratio are 3~9: 1, add the material back and continue to stir 1~2 hour, then in 15~40 minutes, add the reaction promoter that accounts for graphite microparticles and pitch gross weight 8.5~14.5%.
And preparation method's of the present invention step preferably requires to be warming up to 530~570 ℃ in 5~8 hours in 2.;
And 3. constant temperature preferably 4~6 hours of step.
As for step 2. in light constituent in the said material be meant material, the particularly lower component of pitch mid-boiling point, its usually after beginning to heat up 1~2 hour gasification form gaseous impurities; And step 3. in heavy constituent in the said material be meant the component that the material mid-boiling point is higher relatively, its formation gaseous impurities that in the time of 500~600 ℃, gasified usually; The negative pressure that gaseous impurities in above-mentioned two steps is extracted usually<0.1Mpa (absolute pressure) get final product, certain vacuum tightness is the bigger the better, the present invention adopts vacuum pump, its vacuum tightness is generally in 0.06~0.08Mpa scope.
The same with charcoal preparation methods in the prior art; for preventing the reaction mass oxidation; the step of the present invention after adding graphite and pitch also carried out under anti-oxidation condition, can adopt ordinary method, comprises vacuum environment or feeds rare gas element such as nitrogen or hydrogen is protected.In other words, the present invention extracts the operation except that carrying out negative pressure, all will feed an amount of rare gas element in the remaining reaction process and protect, and preferably feeds nitrogen, and its flow is 0.4~2m
3/ h.
Step among the preparation method of the present invention 4., 5. all can adopt ordinary method, the step 5. graphitization temperature that adopts of greying is controlled at and is not less than 2500 ℃, is generally 2500~2800 ℃.
Two of purpose of the present invention provides that a kind of loading capacity is higher, specific surface area is less, the good comprehensive properties artificial graphite charcoal negative electrode material.
This artificial graphite charcoal negative electrode material is with particle diameter (D
50) be 6~40 μ m, specific surface area is no more than 8m
2The synthetic graphite micro mist of/g adopts above-mentioned preparation method to make as raw material.
Preparation method of the present invention utilizes organic polymer that synthetic graphite is carried out surface modification treatment, the recyclable utilization of wherein used reaction promoter, and not only environmental protection also reduces cost; Adopted a small amount of liquid phase, volume solid phase mixing process for treating surface in the middle of the production process, and formed required product, reduced the working strength of solvent recuperation and processing through pyroprocessing; And adopt preparation method's of the present invention productive rate height, in graphite microparticles generally greater than 100%.According to its principle, natural graphite is coated processing, or STRENGTH ON COKE carries out finishing and handles when making carbon cathode material, all can adopt preparation method of the present invention.
Wherein, be that the specific surface area of the artificial plumbago-carbon negative pole material of the present invention that makes of raw material is lower with selected synthetic graphite, structure is more stable, the compacted density height, safety performance is good, and gram volume is higher, and its performance perameter is as shown in table 1 below.
Table 1
Sequence number | Project | Index | Instrument title and model | Manufacturer | |
1 | Particle diameter (D
50,μm)
| 6~45 | Laser particle size distribution instrument MS2000 | Britain Ma Erwen company |
2 | True density (g/cm
3)
| ≥2.20 | Super Water Tank with Temp.-controlled SC-15 | Shanghai balance factory |
3 | Ash content (%) | ≤0.10 | High-temperature electric resistance furnace SX2-2.5-12 | The PVG glad scientific instrument factory that jumps |
4 | Tap density (g/cm
3)
| ≥0.90 | Tap density instrument FZS4-4 | Beijing Iron and Steel Research Geueral Inst |
5 | Specific surface area (m
2/g)
| ≤2.6 | Specific surface area measuring instrument NOVA2000 | U.S. Kang Ta company |
6 | Chemical property | Loading capacity (mAh/g) first | 345.0 | Hyperchannel battery test system Bt2000 type | U.S. ARBIN company |
Discharging efficiency (%) first | ≥93 | Hyperchannel battery test system Bt2000 type | U.S. ARBIN company |
As seen, artificial graphite charcoal negative electrode material of the present invention has not only kept the advantage of former artificial graphite, has also reduced specific surface area, has improved gram volume, when it makes button cell first loading capacity greater than 345mAh/g, near natural graphite.The high comprehensive performance of the battery made from this material, mainly contain following advantage: 1. compacted density is higher, and compacted density can reach more than 1.55 under water-based system; 2. discharge platform higher (88.0~90.0%); 3. the discharge platform conservation rate is higher; 4. internal resistance lower (<40 milliohm); 5. heavy-current discharge performance better (3C/1C:94.5~97%); 6. over-charging better (3C/5V OK); 7. security better (130 ℃/60 minutes, not quick-fried, do not rise); 8. better to electrolytic solution and other additive adaptability; 9. product property is stable, does not almost have difference between batch.
Description of drawings
Fig. 1 is the first charge-discharge curve of the artificial plumbago-carbon negative pole material of the present invention.
Fig. 2 is the sem photograph of the artificial plumbago-carbon negative pole material of the present invention.
Fig. 3 is the cycle performance figure of the artificial plumbago-carbon negative pole material of the present invention.
Embodiment
Further specify the present invention with embodiment below, but the present invention is not limited to this.
Embodiment 1
Take by weighing 300 kilograms of (kg) synthetic graphite micro mist (D
5023.8 μ m, specific surface area 7.8m
2/ g) and the 125kg coal-tar pitch, gradation while stirring alternately joins in the reactor, and back (the nitrogen flow 0.4m under nitrogen protection that finishes feeds intake
3/ h), continue to stir after 1 hour and in 15 minutes, add 45L (47.25kg, account for graphite microparticles and pitch gross weight 11.12%) the solvent washing oil, adding solvent begins to heat up simultaneously, heat up and open vacuum pump after 1 hour, make the interior vacuum tightness of still under 0.06~0.08MPa, keep 20 minutes, logical then nitrogen balance to extract the light constituent in the material, balance finishes follow-up continuous logical nitrogen, and nitrogen flow is 0.4m
3/ h.Temperature rises to 530 ℃ after beginning to heat up 6 hours, beginning vacuumizes to extract heavy constituent and the solvent washing oil (solvent reclaims separately) in the material for the second time, vacuum tightness is 0.06~0.08MPa, and constant temperature 260 minutes to reaction finishes under the temperature of this negative pressure and 530 ℃, carry out conventional greying (2500 ℃) again after afterwards reaction product being cooled to room temperature, make artificial graphite charcoal negative electrode material of the present invention, productive rate is 118.6%.
Embodiment 2
Take by weighing 330kg synthetic graphite micro mist (D
5018.6 μ m, specific surface area 4.1m
2/ g) and the 110kg coal-tar pitch, gradation while stirring alternately joins in the reactor, and back (the nitrogen flow 0.8m under nitrogen protection that finishes feeds intake
3/ h), continue to stir after 1.5 hours and in 40 minutes time, add 60.8L (63.8kg, account for graphite microparticles and pitch gross weight 14.5%) the solvent washing oil, adding solvent begins to heat up simultaneously, heat up and open vacuum pump after 1 hour, make the interior vacuum tightness of still under 0.06~0.08MPa, keep 30 minutes, logical then nitrogen balance to extract the light constituent in the material, balance finishes follow-up continuous logical nitrogen, and nitrogen flow is 0.8m
3/ h.Temperature rises to 570 ℃ after beginning to heat up 8 hours, beginning vacuumizes to extract heavy constituent and the solvent washing oil (solvent reclaims separately) in the material for the second time, vacuum tightness is 0.06~0.08MPa, and constant temperature 6 hours to reaction finishes under the temperature of this negative pressure and 570 ℃, carry out conventional greying (2600 ℃) again after afterwards reaction product being cooled to room temperature, make artificial graphite charcoal negative electrode material of the present invention, productive rate is 112.2%.
Embodiment 3
Take by weighing 450kg synthetic graphite micro mist (D
5020.9 μ m, specific surface area 6.4m
2/ g) and the 40kg coal-tar pitch, gradation while stirring alternately joins in the reactor, and back (the nitrogen flow 1.2m under nitrogen protection that finishes feeds intake
3/ h), continue to stir after 0.5 hour and in 20 minutes time, add 39.7L (41.65kg, account for graphite microparticles and pitch gross weight 8.5%) the washing oil solvent, adding solvent begins to heat up simultaneously, heat up and open vacuum pump after 1.5 hours, make the interior vacuum tightness of still under 0.06~0.08MPa, keep 40 minutes, logical then nitrogen balance to extract the light constituent in the material, balance finishes follow-up continuous logical nitrogen, and nitrogen flow is 1.2m
3/ h.Temperature rises to 560 ℃ after beginning to heat up 5 hours, beginning vacuumizes to extract heavy constituent and the solvent washing oil (solvent reclaims separately) in the material for the second time, vacuum tightness is the same, and constant temperature 3 hours to reaction finishes under the temperature of this negative pressure and 560 ℃, carry out greying (2800 ℃) again after afterwards reaction product being cooled to room temperature, make artificial graphite charcoal negative electrode material of the present invention, productive rate is 102.6%.
Embodiment 4
Take by weighing 360kg synthetic graphite micro mist (D
5013.9 μ m, specific surface area 5.3m
2/ g) and 40kg petroleum pitch, gradation while stirring alternately joins in the reactor, and back (the nitrogen flow 1.5m under nitrogen protection that finishes feeds intake
3/ h), continue to stir after 1.8 hours and in 10 minutes time, add 15.4L (16.2kg, account for graphite microparticles and pitch gross weight 4.05%) the washing oil solvent, adding solvent begins to heat up simultaneously, heat up and open vacuum pump after 1 hour, make the interior vacuum tightness of still under 0.06~0.08MPa, keep 50 minutes, logical then nitrogen balance to extract the light constituent in the material, balance finishes follow-up continuous logical nitrogen, and nitrogen flow is 1.5m
3/ h.Temperature rises to 500 ℃ after beginning to heat up 4 hours, beginning vacuumizes to extract heavy constituent and the solvent washing oil (solvent reclaims separately) in the material for the second time, vacuum tightness is the same, and constant temperature 4 hours to reaction finishes under the temperature of this negative pressure and 500 ℃, carry out greying (2800 ℃) again after after reaction finishes reaction product being cooled to room temperature, make artificial graphite charcoal negative electrode material of the present invention, productive rate is 101.5%.
Embodiment 5
Take by weighing 240kg synthetic graphite micro mist (D
506.08 μ m, specific surface area 7.9m
2/ g) and 160kg petroleum pitch, gradation while stirring alternately joins in the reactor, and back (the nitrogen flow 2m under nitrogen protection that finishes feeds intake
3/ h), continue to stir after 2 hours and in 50 minutes time, add 74L (79.2kg, account for graphite microparticles and pitch gross weight 19.8%) solvent carbolineum, adding solvent begins to heat up simultaneously, heat up and open vacuum pump after 2 hours, make the interior vacuum tightness of still under 0.06~0.08MPa, keep 20 minutes, logical then nitrogen balance to extract the light constituent in the material, balance finishes follow-up continuous logical nitrogen, and nitrogen flow is 2m
3/ h.Temperature rises to 600 ℃ after beginning to heat up 10 hours, beginning vacuumizes to extract heavy constituent and the solvent carbolineum (solvent reclaims separately) in the material for the second time, vacuum tightness is the same, and constant temperature 8 hours to reaction finishes under the temperature of this negative pressure and 600 ℃, carry out greying (2600 ℃) again after afterwards reaction product being cooled to room temperature, make artificial graphite charcoal negative electrode material of the present invention, productive rate is 136.2%.
Embodiment 6
Take by weighing 300kg synthetic graphite micro mist (D
5010.2 μ m, specific surface area 5.8m
2/ g) and 50kg petroleum pitch, gradation while stirring alternately joins in the reactor, and back (the nitrogen flow 1m under nitrogen protection that finishes feeds intake
3/ h), continue to stir after 1.5 hours and in 30 minutes time, add 31.4L (33.6kg, account for graphite microparticles and pitch gross weight 9.6%) solvent carbolineum, adding solvent begins to heat up simultaneously, heat up and open vacuum pump after 2 hours, make the interior vacuum tightness of still under 0.06~0.08MPa, keep 30 minutes, logical then nitrogen balance to extract the light constituent in the material, balance finishes follow-up continuous logical nitrogen, and nitrogen flow is 1m
3/ h.Temperature rises to 540 ℃ after beginning to heat up 7 hours, beginning vacuumizes to extract heavy constituent and the solvent carbolineum (solvent reclaims separately) in the material for the second time, vacuum tightness is the same, and constant temperature 5 hours to reaction finishes under the temperature of this negative pressure and 540 ℃, carry out greying (2700 ℃) again after afterwards reaction product being cooled to room temperature, make artificial graphite charcoal negative electrode material of the present invention, productive rate is 102.2%.
Embodiment 7
Take by weighing 475kg synthetic graphite micro mist (D
5039.7 μ m, specific surface area 4.0m
2/ g) and the 25kg coal-tar pitch, gradation while stirring alternately joins in the reactor, and back (the nitrogen flow 0.6m under nitrogen protection that finishes feeds intake
3/ h), continue to stir after 0.5 hour and in 25 minutes time, add 19L (20kg, account for graphite microparticles and pitch gross weight 4%) the solvent washing oil, adding solvent begins to heat up simultaneously, heat up and open vacuum pump after 1.5 hours, make the interior vacuum tightness of still under 0.06~0.08MPa, keep 20 minutes, logical then nitrogen balance to extract the light constituent in the material, balance finishes follow-up continuous logical nitrogen, and nitrogen flow is 0.6m
3/ h.Temperature rises to 550 ℃ after beginning to heat up 6 hours, beginning vacuumizes to extract heavy constituent and the solvent washing oil (solvent reclaims separately) in the material for the second time, vacuum tightness is the same, and constant temperature 5 hours to reaction finishes under the temperature of this negative pressure and 550 ℃, carry out greying (2600 ℃) again after afterwards reaction product being cooled to room temperature, make artificial graphite charcoal negative electrode material of the present invention, productive rate is 100.8%.
Embodiment 8
Take by weighing 400kg synthetic graphite micro mist (D
5029.6 μ m, specific surface area 5.2m
2/ g) and the 100kg coal-tar pitch, gradation while stirring alternately joins in the reactor, and back (the nitrogen flow 1.5m under nitrogen protection that finishes feeds intake
3/ h), continue to stir after 3 hours and in 30 minutes time, add 56L (60kg, account for graphite microparticles and pitch gross weight 12%) solvent carbolineum, adding solvent begins to heat up simultaneously, heat up and open vacuum pump after 1.5 hours, make the interior vacuum tightness of still under 0.06~0.08MPa, keep 20 minutes, logical then nitrogen balance to extract the light constituent in the material, balance finishes follow-up continuous logical nitrogen, and nitrogen flow is 1.5m
3/ h.Temperature rises to 540 ℃ after beginning to heat up 7 hours, beginning vacuumizes to extract heavy constituent and the solvent carbolineum (solvent reclaims separately) in the material for the second time, vacuum tightness is the same, and constant temperature 5 hours to reaction finishes under the temperature of this negative pressure and 540 ℃, carry out greying (2700 ℃) again after afterwards reaction product being cooled to room temperature, make artificial graphite charcoal negative electrode material of the present invention, productive rate is 107.8%.
Comparative example's (comparative example) 1
Do not add surface-modifying agent, the synthetic graphite micro mist is handled making carbon cathode material by technology of the present invention.
Take by weighing 400kg synthetic graphite micro mist (D
5020.4 μ m, specific surface area 6.2m
2/ g), joining while stirring in the reactor, back (the nitrogen flow 0.8m under nitrogen protection that finishes feeds intake
3/ h), continue to stir the solvent washing oil that in 25 minutes time, adds 32.4L (34kg) after 1 hour, adding solvent begins to heat up simultaneously, heat up and open vacuum pump after 1 hour, make the interior vacuum tightness of still under 0.06~0.08MPa, keep 40 minutes to extract the light constituent in the material, logical then nitrogen balance, balance finish follow-up continuous logical nitrogen, and nitrogen flow is 0.8m
3/ h.Temperature rises to 540 ℃ after beginning to heat up 6 hours, beginning vacuumizes to extract heavy constituent and the solvent washing oil (solvent reclaims separately) in the material for the second time, vacuum tightness is the same, and constant temperature 5 hours to reaction finishes under the temperature of this negative pressure and 540 ℃, carry out greying (2700 ℃) again after afterwards reaction product being cooled to room temperature, make carbon cathode material, productive rate is 86.8%.
Raw material in the foregoing description is conventional commercially available prod.
Adopt conventional determining method to measure the artificial graphite charcoal material physical properties and the chemical property of the foregoing description and comparative example 1, and with comparative example 2---commercially available similar artificial graphite charcoal negative electrode material (uses pitch, washing oil equally, making but adopt other existing technology that the synthetic graphite micro mist is carried out the modification processing, is the CMS-3 product that Shanghai Shanshan Science and Technology Co., Ltd produces) compare.Wherein the chemical property measuring method is:
Graphite sample, the N-Methyl pyrrolidone that contains 6~7% polyvinylidene difluoride (PVDF) and 2% graphitized carbon black mix, and are applied on the Copper Foil, and it is that 110 ℃ of vacuum drying oven vacuum-dryings 4 hours are standby that the pole piece that coats is put into temperature.Simulated battery is assemblied in the German Braun glove box of applying argon gas and carries out, and electrolytic solution is 1M LiPF
6+ EC: DEC: DMC=1: 1: 1 (volume ratio), metal lithium sheet are counter electrode, and electrochemical property test carries out on U.S. ArbinBT2000 type cell tester, and the charging/discharging voltage scope is 0.005 to 1.0V, and charge-discharge velocity is 0.1C.
Each embodiment and comparative example's performance perameter is as shown in the table:
Embodiment | Particle diameter (μ m) | True density (g/cm
3)
| Tap density (g/cm
3)
| Specific surface area (m
2/g)
| Loading capacity (mAh/g) | Efficient (%) first |
1 | 27.6 | 2.20 | 1.04 | 1.5 | 354.5 | 96.3 |
2 | 23.7 | 2.22 | 1.06 | 1.0 | 354.1 | 95.3 |
3 | 22.9 | 2.23 | 1.08 | 1.9 | 355.7 | 95.8 |
4 | 14.5 | 2.21 | 0.92 | 2.3 | 350.1 | 93.3 |
5 | 8.6 | 2.20 | 0.91 | 2.4 | 351.6 | 93.8 |
6 | 11.8 | 2.21 | 1.02 | 2.0 | 353.5 | 94.1 |
7 | 40.2 | 2.20 | 1.03 | 2.1 | 351.4 | 94.6 |
8 | 31.2 | 2.21 | 1.04 | 1.8 | 354.6 | 95.1 |
Comparative example 1 | 20.6 | 2.25 | 0.78 | 5.0 | 355.5 | 90.7 |
Comparative example 2 | 24.9 | 2.16 | 1.16 | 2.3 | 333.7 | 94.0 |
From top data as can be seen, the specific surface area of comparative example 1 is big, is 5.0m
2/ g, efficient is low first only 90.7%; The loading capacity of comparative example 2 is low to be 333.7mAh/g; Adopt the negative material of the described method preparation of patent, specific surface area is reduced in 2.6m greatly
2Below/the g, capacity can reach more than the 350mAh/g, and the size-grade distribution of product is more even simultaneously, as shown in Figure 2.
Application Example 1
The carbon cathode material of getting the embodiment of the invention 2,3 is made into battery and carries out performance relatively, makes the battery design condition and is:
Battery design capacity: 810mAh;
Negative pole list gram volume design: 330mAh/g, compacted density: 1.60g/cm
3
Anodal single gram volume design: 140mAh/g.
The results are shown in shown in the following table:
The negative material of the embodiment of the invention is made battery performance relatively
The sample title | Embodiment | 2 | Embodiment 3 | Comparative example 2 |
First charge-discharge efficiency (%) | 92.9 | 93.3 | 87.5 |
Internal resistance (m Ω) | 33.5 | 33.3 | 35.9 |
1C platform occupation rate (%) | 86.9 | 87.8 | 82.2 |
1C/0.2C(%) | 99.6 | 99.4 | 98.2 |
2C/0.2C(%) | 98.0 | 97.9 | 96.1 |
3C/0.2C(%) | 95.7 | 95.9 | 92.6 |
As seen from the above table, adopt the corresponding raising of performance of the battery that battery that the carbon cathode material of embodiment 2 and 3 makes all makes than comparative example 2 in aspect performances such as first charge-discharge efficiency, material platform occupation rate, large current discharging capabilities.Wherein, gram volume is higher, can improve the energy of battery; Irreversible capacity loss is low, can reduce anodal consumption to a certain extent; Compaction capacity is good, can effectively improve the material usage of unit surface; Specific surface is low, helps suppressing lithium-ion battery system and produces ballooning, and the safety performance of battery is good; Over-charging is better; The pole piece processibility is good; Ideal voltage platform, sparking voltage are very fast to reach plateau, as shown in Figure 1; High-rate performance is better; Good cycle, the capability retention that circulates after 400 times is near 90%, as shown in Figure 3.