Embodiment
The preparation method of used as negative electrode of Li-ion battery composite material provided by the invention comprises silica flour, graphite, thermal cracking carbon precursor and solvent even, make slurry, wherein, described silica flour comprises micron silica flour and nano silica fume, and the weight ratio of described micron silica flour and nano silica fume is 2-20: 1; Remove the solvent in the slurry and carry out first sintering under inert gas shielding, carry out first ball milling then, carry out second sintering again under inert gas shielding, carry out second ball milling then, wherein, the temperature of second sintering is higher than the temperature of first sintering.
The weight ratio 1 of described silica flour, graphite, thermal cracking carbon precursor and solvent: 1-5: 1-5: 5-50.
The weight ratio of described micron silica flour and nano silica fume is preferably 3-15: 1.
The particle size range of described micron silica flour is the 1-10 micron, is preferably the 1-5 micron; The particle size range of nano silica fume is the 10-50 nanometer, is preferably the 20-40 nanometer.
Described graphite does not have specific (special) requirements, is modified artificial graphite under the preferable case, and the preferable particle size scope is the 1-5 micron.
Described thermal cracking carbon precursor can be selected suitable solvent according to used thermal cracking carbon precursor for the various compounds that can generate charcoal simple substance in cracking under the sintering condition of routine.For example, described thermal cracking carbon precursor can be in sucrose, starch, asccharin and the glucose one or more, and described solvent can be the mixed solvent of alcohol and water; Described thermal cracking carbon precursor can be pitch, and described solvent can be in carbon tetrachloride, quinoline and the polyvinyl chloride one or more; Described thermal cracking carbon precursor can be phenolic resins, and described solvent can be alcohol or ketone; Described thermal cracking carbon precursor can be the poly-third ethene nitrile, and described solvent can be dimethyl pyrrolidone; Perhaps, described thermal cracking carbon precursor can be CMC and/or polyethylene glycol, and described solvent can be water.
Under the preferable case, described thermal cracking carbon precursor is one or more in sucrose, starch, asccharin and the glucose, and described solvent is that volume ratio is 1: the second alcohol and water of 3-5.
The method of removing the solvent in the slurry can be the whole bag of tricks of routine, for example can with slurry 80-110 ℃ dry 3-6 hour down, perhaps under vacuum condition with slurry drying.
The method of described sintering can be the sintering method of routine.The temperature of first sintering is preferably 600-750 ℃, and the time is preferably 8-12 hour; The temperature of second sintering is preferably 900-1100 ℃, and the time is preferably 10-25 hour.
Described inert gas can be any gas that does not participate in reacting, and is preferably in nitrogen and the group 0 element gas one or more.
The method of described ball milling is conventionally known to one of skill in the art.The preferred planetary ball mill that uses, the condition of first ball milling and second ball milling comprises separately: ball material weight ratio is preferably 100-300: 1, rotational speed of ball-mill is preferably 150-350 rev/min, and the ball milling time is preferably 20-30 hour.
Lithium ion battery negative provided by the invention comprises conducting base and the negative material that is carried on this conducting base, described negative material comprises negative electrode active material and adhesive, wherein, described negative electrode active material comprises the used as negative electrode of Li-ion battery composite material by method preparation provided by the present invention.
Described negative pole conducting base can be for negative pole conducting base conventional in the lithium ion battery, as stamped metal, and metal forming, net metal, foamed metal uses Copper Foil as the negative pole conducting base in specific embodiments of the present invention.
The kind of described adhesive and content are conventionally known to one of skill in the art, for example one or more in fluorine resin and polyolefin compound such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), butadiene-styrene rubber (SBR), hydroxypropyl methylcellulose, sodium carboxymethylcellulose, hydroxyethylcellulose, the polyvinyl alcohol; In general, according to the difference of adhesive therefor kind, be benchmark with the weight of negative electrode active material, the content of negative pole adhesive is 0.01-10 weight %, is preferably 0.02-5 weight %.
Can also comprise that in described negative material conductive agent to increase the conductivity of electrode, reduces the internal resistance of cell.Described conductive agent is not particularly limited, and can be the cathode conductive agent of this area routine, such as in carbon black, nickel powder, the copper powder one or more.Weight with negative electrode active material is benchmark, and the content of described conductive agent is 0-12 weight %, is preferably 2-10 weight %.
The preparation method of negative pole provided by the present invention comprises ion battery negative electrode active material provided by the present invention, adhesive and solvent, applies and/or is filled on the described conducting base, and drying is rolled or do not rolled, and can obtain described negative pole.
Described solvent can be selected from one or more in N-methyl pyrrolidone (NMP), dimethyl formamide (DMF), diethylformamide (DEF), dimethyl sulfoxide (DMSO) (DMSO), oxolane (THF) and water and the alcohols.The consumption of solvent can make described pastel have viscosity and flowability, can be coated on the described conducting base to get final product.In general, be benchmark with the weight of negative electrode active material, the content 50-150 weight % of described solvent is preferably 70-120 weight %.
Described drying, the method for calendering and condition are conventionally known to one of skill in the art.For example, the temperature of described drying is generally 100-150 ℃.
Lithium ion battery provided by the invention comprises electrode group and nonaqueous electrolytic solution, and described electrode group and nonaqueous electrolytic solution are sealed in the battery container, and described electrode group comprises positive pole, negative pole and barrier film, and wherein, described negative pole is a negative pole provided by the present invention.
Because improvements of the present invention only relate to the negative pole of lithium ion battery, therefore in lithium ion battery provided by the invention, positive pole, barrier film and non-aqueous electrolytic solution to battery have no particular limits, and can use all types of positive poles, membrane layer and the non-aqueous electrolytic solution that can use in lithium rechargeable battery.Those of ordinary skill in the art can be according to the instruction of prior art, can select and prepare positive pole, membrane layer and the non-aqueous electrolytic solution of lithium rechargeable battery of the present invention easily, and make lithium rechargeable battery of the present invention by described positive pole, silicium cathode of the present invention, membrane layer and non-aqueous electrolytic solution.
Consisting of of described positive pole is conventionally known to one of skill in the art.In general, positive pole comprises conducting base and coating and/or is filled in positive electrode on the conducting base that described positive electrode comprises positive active material, conductive agent and adhesive.
The kind of described anodal conducting base has been conventionally known to one of skill in the art, for example can be selected from aluminium foil, Copper Foil, Punching steel strip.In the specific embodiment of the present invention, use aluminium foil as anodal conducting base.
The kind of the adhesive in the described positive electrode and content are conventionally known to one of skill in the art, for example one or more in fluorine resin and polyolefin compound such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) and the butadiene-styrene rubber (SBR).In general, according to the difference of adhesive therefor kind, be benchmark with the weight of positive active material, the content of adhesive is 0.01-10 weight %, is preferably 0.02-5 weight %.
Under positive active material be not particularly limited, can be the common active material in this area, such as in cobalt acid lithium, lithium nickelate, LiFePO4 and the LiMn2O4 one or more.
Described conductive agent is not particularly limited, and can be the anodal conductive agent of this area routine, at least a such as in acetylene black, conductive carbon black and the electrically conductive graphite.Weight with positive active material is benchmark, and the content of described conductive agent is 0.5-15 weight %, is preferably 1-10 weight %.
Described barrier film is arranged between positive pole and the negative pole, has electrical insulation capability and liquid retainability energy.Described barrier film can be selected from various barrier films used in the lithium ion battery, as polyolefin micro porous polyolefin membrane, polyethylene felt, glass mat or ultra-fine fibre glass paper.The position of described barrier film, character and kind are conventionally known to one of skill in the art.
Described nonaqueous electrolytic solution is the mixed solution of electrolyte lithium salt and nonaqueous solvents, and it is not particularly limited, and can use the nonaqueous electrolytic solution of this area routine.Be selected from lithium hexafluoro phosphate (LiPF6), lithium perchlorate, LiBF4, hexafluoroarsenate lithium, lithium halide, chlorine lithium aluminate and the fluorocarbon based sulfonic acid lithium one or more such as electrolyte lithium salt.Organic solvent is selected chain acid esters and ring-type acid esters mixed solution for use, wherein the chain acid esters can be dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), carbonic acid first propyl ester (MPC), dipropyl carbonate (DPC) and other are fluorine-containing, sulfur-bearing or contain at least a in the chain organosilane ester of unsaturated bond, the ring-type acid esters can be ethylene carbonate (EC), propene carbonate (PC), vinylene carbonate (VC), gamma-butyrolacton (γ-BL), sultone and other are fluorine-containing, sulfur-bearing or contain at least a in the ring-type organosilane ester of unsaturated bond.The injection rate of electrolyte is generally 1.5-4.9 gram/ampere-hour, the concentration of electrolyte be generally 0.1-2.0 rub/liter.
According to the preparation method of lithium ion battery provided by the invention, except described negative pole prepared according to method provided by the invention, other step was conventionally known to one of skill in the art.In general, positive pole and negative pole winding are separated formation electrode group, electrode group and the electrolyte that obtains is sealed in the battery case, can obtain lithium ion battery provided by the invention by membrane layer.The method for winding of the membrane layer between positive pole and negative pole is conventionally known to one of skill in the art, does not repeat them here.
To the present invention be described in more detail by embodiment below.
Embodiment 1
This embodiment is used to illustrate the preparation method of used as negative electrode of Li-ion battery composite material provided by the invention.
Preparation 500mL ethanol water, the ratio of second alcohol and water is volume ratio 1: 3.5, it is complete to add 50g sucrose stirring and dissolving, (particle size range is the 1-5 micron to add 16 gram silica flours again in solution, available from Beijing Non-Fervoous Metal Inst.), 3 gram particles footpaths scope be the 20-40 nanometer silica flour (available from clear international) and 35 restrain artificial modified graphite (particle size range be the 1-5 micron, available from Shenzhen Bei Terui), stir.In baking box, toasted 12 hours under 100 ℃ then.With dried mixture in high temperature furnace under the argon shield 650 ℃ carry out sintering; time is 10 hours; it is 200: 1 in ball material weight ratio then; rotating speed is a ball milling 20 hours in 300 rev/mins the planetary ball mill, crosses 300 mesh sieves, 1000 ℃ of following heat treatment 20 hours under argon shield then; taking-up is 150: 1 in ball material weight ratio; rotating speed is a ball milling 20 hours in 300 rev/mins the planetary ball mill, takes out the back and crosses 400 mesh sieves, obtains used as negative electrode of Li-ion battery composite A 1.
Embodiment 2
This embodiment is used to illustrate the preparation method of used as negative electrode of Li-ion battery composite material provided by the invention.
Method according to identical with embodiment 1 obtains used as negative electrode of Li-ion battery composite A 2.Difference is, in ethanol water, add 45 gram sucrose, 15 gram micron silica flours (particle size range is the 1-5 micron), 5 gram nano silica fumes (particle size range is the 20-40 nanometer) and 35 gram artificial modified graphites (particle size range is the 1-5 micron) obtain 65 gram negative active core-shell material A2.
Embodiment 3
This embodiment is used to illustrate the preparation method of used as negative electrode of Li-ion battery composite material provided by the invention.
Preparation 500mL ethanol water, the ratio of second alcohol and water is volume ratio 1: 4, it is complete to add 40 sucrose stirring and dissolving, adding 20 gram silica flours (particle size range is the 1-5 micron), 4 gram particles footpath scope are the silica flour and the 35 gram artificial modified graphites (particle size range is the 1-5 micron) of 20-40 nanometer in solution again, stir.Then in baking box 100 ℃ the baking 12 hours; with dried mixture in high temperature furnace under the argon shield 700 ℃ carry out sintering; time is 12 hours; it is 250: 1 in ball material weight ratio then; rotating speed is a ball milling 25 hours in 200 rev/mins the planetary ball mill; cross 300 mesh sieves; 1000 ℃ of following heat treatment 14 hours under argon shield then; taking-up is 300: 1 in ball material weight ratio; rotating speed is a ball milling 25 hours in 250 rev/mins the planetary ball mill; take out the back and cross 400 mesh sieves, obtain 65 gram used as negative electrode of Li-ion battery composite A 3.
Embodiment 4
This embodiment is used to illustrate the preparation method of used as negative electrode of Li-ion battery composite material provided by the invention.
Preparation 500mL ethanol water, the ratio of second alcohol and water is volume ratio 1: 3, it is complete to add 45g starch stirring and dissolving, adding 26 gram silica flours (particle size range is the 1-5 micron), 2 gram particles footpath scope are the silica flour and the 45 gram artificial modified graphites (particle size range is the 1-5 micron) of 20-40 nanometer in solution again, stir.Then in baking box 100 ℃ the baking 12 hours; with dried mixture in high temperature furnace under the argon shield 750 ℃ carry out sintering; time is 8 hours; it is 200: 1 in ball material weight ratio then; rotating speed is a ball milling 25 hours in 300 rev/mins the planetary ball mill; cross 300 mesh sieves; 1100 ℃ of following heat treatment 12 hours under argon shield then; taking-up is 300: 1 in ball material weight ratio; rotating speed is a ball milling 12 hours in 250 rev/mins the planetary ball mill; take out the back and cross 400 mesh sieves, obtain 80 gram used as negative electrode of Li-ion battery composite A 4.
Embodiment 5
This embodiment is used to illustrate the preparation method of used as negative electrode of Li-ion battery composite material provided by the invention.
Preparation 500mL ethanol water, the ratio of second alcohol and water is volume ratio 1: 4.5, add the 30g asccharin, stirring and dissolving is complete, adding 25 gram silica flours (particle size range is the 1-5 micron), 5 gram particles footpath scope are the silica flour and the 30 gram artificial modified graphites (particle size range is the 1-5 micron) of 20-40 nanometer in solution again, stir.Then in baking box 100 ℃ the baking 12 hours; with dried mixture in high temperature furnace under the argon shield 600 ℃ carry out sintering; time is 12 hours; it is 300: 1 in ball material weight ratio then; rotating speed is a ball milling 30 hours in 350 rev/mins the planetary ball mill; cross 300 mesh sieves; 950 ℃ of following heat treatment 14 hours under argon shield then; taking-up is 250: 1 in ball material weight ratio; rotating speed is a ball milling 20 hours in 150 rev/mins the planetary ball mill; take out the back and cross 400 mesh sieves, obtain 50 gram used as negative electrode of Li-ion battery composite A 5.
Embodiment 6-10
Embodiment 6-10 is respectively applied for preparation and contains the battery A6-A10 of the resulting lithium ion battery negative active material of embodiment 1-5, and measures first charge-discharge capacity and 50 circulation back capability retentions of battery A6-A10 respectively.
The method for preparing battery is as follows:
(1) making of negative pole
100 weight portion Si-C composite materials, 4 weight portion adhesive polytetrafluoroethylene (PTFE)s, 3 weight portion conductive agent carbon blacks are joined in 135 parts by weight of deionized water, stir then and form cathode size stable, homogeneous.
This slurry is coated on long 416 millimeters, wide 45 millimeters, the thick 12 microns Copper Foil equably, and covering the material amount is volume density 1.8g/cm
3, through 120 ℃ of oven dry, obtain negative pole, wherein contain 1.88 gram negative electrode active materials.
(2) Zheng Ji making
With positive active material cobalt acid lithium (LiCoO
2), conductive agent acetylene black, binding agent PVDF and organic solvent N-dimethyl pyrrolidone (NMP) be according to mass ratio LiCoO
2: acetylene black: PVDF: NMP=100: 4: 4: 85 mixing and stirring, make anode sizing agent, this slurry is coated on long 424 millimeters, wide 44 millimeters, the thick 16 microns aluminium foil equably 120 ℃ of oven dry then, obtain positive pole, wherein contain 8.75 gram positive active materials.
(3) assembling of battery
With LiPF
6Be configured to LiPF with ethylene carbonate (EC) and diethyl carbonate (DEC)
6Concentration is the solution (wherein, the volume ratio of EC and DEC is 1: 1) of 1.0 mol, obtains nonaqueous electrolytic solution.With obtaining to such an extent that cathode pole piece and polypropylene screen are wound into the pole piece of a square ion battery in the anode pole piece 1 that obtains in (1), (2), then nonaqueous electrolytic solution is injected battery case with the amount of 3.8g/Ah, lithium ion battery is made in sealing.
The method of measuring battery first charge-discharge performance, back capability retention and the specific capacity of circulating for 50 times is as follows:
(1) measure the first charge-discharge capacity, method for the current charges of 1C (1C is a design capacity, and 1C of the present invention is 1000 milliamperes) to 4.2V, then with the 0.5C current discharge to 2.7V, the battery charging and discharging capability value of record gained.
Measurement result is as shown in table 1.
(2) measure circulation back conservation rate 50 times, assay method carries out constant current charge for the constant current with 10mA to battery, and charging is by voltage 4.2V, and rising to 4.2V at voltage carries out constant voltage charge later on, by electric current 2.5mA; Shelved 10 minutes, and to 3.0V, measured the initial discharge capacity that obtains battery with the current discharge of 10mA.After shelving 10 minutes, repeat above step, make continuous charge-discharge test, obtain the discharge battery capacity after battery circulates for 50 times, calculate the discharge capacitance of 50 circulation back batteries according to following formula.
Discharge capacity/initial discharge capacity * 100% measurement result is as shown in table 1 for time circulation back, discharge capacitance=50.
(3) measure specific capacity, assay method be under 25 ℃ with battery with 1C electric current constant current charge to 3.8V, then change the constant voltage charging, cut-off current 0.05C; Then, again with battery with 1C electric current constant-current discharge to 2.0V, obtain the capacity of battery normal temperature 1C current discharge to 2.0V, with the ratio of the quality of this discharge capacity and negative electrode active material as specific capacity.
Measurement result is as shown in table 1.
Comparative example 1
This comparative example is used to prepare the carbon-silicon composite material B1 that only uses the preparation of micron silica flour.
Prepare carbon-silicon composite material B1 according to the mode identical with embodiment 1, difference is, adds 19 gram micron silica flours (particle size range is the 1-5 micron, available from Beijing Non-Fervoous Metal Inst.) in solvent; With the 1000 ℃ of following heat treatment 30 hours under argon shield of dried mixture, taking out in ball material weight ratio is 150: 1, and rotating speed is a ball milling 20 hours in 300 rev/mins the planetary ball mill, takes out the back and crosses 400 mesh sieves.
Comparative example 2
This comparative example is used to prepare the carbon-silicon composite material B2 that only uses the nano silica fume preparation.
Prepare carbon-silicon composite material B2 according to the mode identical with embodiment 1, difference is, in solvent, add the silica flour that 19 gram footpath scopes are the 20-40 nanometer (available from clear international); With the 1000 ℃ of following heat treatment 30 hours under argon shield of dried mixture, taking out in ball material weight ratio is 150: 1, and rotating speed is a ball milling 20 hours in 300 rev/mins the planetary ball mill, takes out the back and crosses 400 mesh sieves.
Comparative example 3-4
Comparative example 3-4 is used to prepare the carbon-silicon composite material with spherical nucleocapsid that provided by the comparative example 1-2 battery B3-4 as negative material, and measures first charge-discharge capacity and 50 circulation back capability retentions of battery B3-4.
Make battery B3-4 according to the method identical with embodiment 6-10, difference is the carbon-silicon composite material with spherical nucleocapsid of employed negative active core-shell material for being obtained by comparative example 1-2.
Measure the first charge-discharge capacity of battery B3-4, circulate for 50 times back capability retention and specific capacity according to the method identical with embodiment 6-10, measurement result is as shown in table 1.
Table 1
| Project |
First charge-discharge capacity (MAH) |
50 circulation back capability retentions |
Specific capacity (MAH/gram) |
| Embodiment 6 |
1190 |
88% |
690 |
| Embodiment 7 |
1200 |
84% |
760 |
| Embodiment 8 |
1220 |
85% |
670 |
| Embodiment 9 |
1160 |
91% |
650 |
| Embodiment 10 |
1180 |
86% |
710 |
| Comparative example 3 |
990 |
64% |
460 |
| Comparative example 4 |
1010 |
70% |
600 |
From the measurement result shown in the table 1 as can be seen, the first charge-discharge capacity of the battery A6-A10 that is made up of composite A 1-A5 among the embodiment 6-10 is apparently higher than the first charge-discharge capacity of the battery B3-4 of Comparative Examples 3-4, in addition, 50 the circulation back capability retentions of the battery A6-A10 that is made up of composite A 1-A5 and specific capacity are also apparently higher than 50 circulation back capability retentions and the specific capacities of the battery B3-4 of Comparative Examples 3-4, explanation has higher specific capacity by the used as negative electrode of Li-ion battery composite material of method preparation provided by the invention, and improves the first charge-discharge capacity and the cycle performance of lithium ion battery.