CN100338795C - Negative electrode for lithium secondary battery, method for producing same, and lithium secondary battery using same - Google Patents
Negative electrode for lithium secondary battery, method for producing same, and lithium secondary battery using same Download PDFInfo
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- CN100338795C CN100338795C CNB2004800025412A CN200480002541A CN100338795C CN 100338795 C CN100338795 C CN 100338795C CN B2004800025412 A CNB2004800025412 A CN B2004800025412A CN 200480002541 A CN200480002541 A CN 200480002541A CN 100338795 C CN100338795 C CN 100338795C
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Abstract
A lithium secondary battery comprises a positive electrode (1), a negative electrode (2) and a nonaqueous electrolyte. The negative electrode (2) contains a negative electrode active material and a binder; and the negative electrode active material contains graphite (A) and graphite (B). Primary particles of the graphite (A) have a spherical or oval-spherical shape with an average particle diameter of 10-30 mum. The graphite (A) has a crystallite size along the c-axis of less than 100 nm, and a tap density of 1.0 g/cm<3> or more. Primary particles of the graphite (B) have a flat shape with an average particle diameter of 1-10 mum. The graphite (B) has a crystallite size along the c-axis of 100 nm or more. Consequently, the lithium secondary battery has a large capacity and excellent cycle characteristics.
Description
Technical field
The present invention relates to negative electrode for lithium secondary battery, relate to the negative electrode for lithium secondary battery of the cheapness of high power capacity and cycle characteristics excellence in more detail.
Background technology
In recent years,, and the care of environment and the aspect that economizes on resources considered that the necessity of the secondary cell of high power capacity that can repeated charge is also improving from the development of portable electronic machines such as mobile phone, subnotebook PC.Lithium secondary battery, because energy density height, in light weight and volume is little, and excellent charge, so, be widely used as power supply for these portable electronic machines, increase along with the power consumption of portable electronic machine requires further high capacity and cycle characteristics improvement technology.
In the lithium secondary battery,, use LiCoO as positive active material always
2, LiNiO
2, LiMn
2O
4Deng lithium-contained composite oxide,, use always and can carry out the insertion of lithium and the material with carbon element of deviating from as negative electrode active material.In addition, in recent years to the effort of high capacity, mainly be to carry out with the center that is developed as of carbon material used as anode.And there is the tendency of not using non-crystal material and using the high crystalline material with carbon element in material with carbon element in order to obtain higher energy density and high voltage.
In the existing material with carbon element, what have the highest crystallinity and discharge capacity is native graphite, in addition, carries out graphitization processing and this Delanium of carbonaceous mesophase spherules (MCMB) that obtains also has high crystalline and big discharge capacity about 3000 ℃.But these materials exist along with the charge and discharge cycles capacity significant problem that descends.
About the raising with the every characteristic headed by the cycle characteristics, known vapor deposition carbon fiber (VGCF) or the carbon black etc. of adding in negative electrode active material are effectively (for example to open flat 6-111818 communique (the 2nd～4 page, table 1), spy with reference to the spy and open that flat 10-149833 communique (the 2nd～6 page, table 1～3) spy opens flat 11-176442 communique (the 2nd～7 page, Fig. 2～7), the spy opens 2001-68110 communique (the 2nd～5 page, table 1)).But these heterogeneous carbon are generally compared with the graphite cathode active material, and little, the feasible high-energy-density as graphite cathode active material advantage of discharge capacity descends.In addition, the vapor deposition carbon fiber also becomes the high reason of cost.
In addition, known in native graphite, adding 10～50% Delanium, can improve fail safe (for example opening flat 5-290844 communique (the 2nd～4 page, Fig. 3)) with reference to the spy.But, investigation according to people of the present invention, can know, common Delanium is MCMB for example, because the average grain diameter of primary particle has 10～30 μ m big, even so be that the native graphite of 10～30 μ m mixes use with the average grain diameter of primary particle, interparticle contact point also less, cycle characteristics can't say fully.
And then, known to using the negative electrode active material of forming by by the graphite of armorphous graphite covering surfaces and other graphite, realize that the material (for example opening 2000-138061 communique (the 2nd～8 page, table 2,3) with reference to the spy) of high capacity and raising efficiency for charge-discharge and purpose are high capacity and at the material (for example opening 2001-185147 communique (the 2nd～7 page, table 1) with reference to the spy) of the good capacity sustainment rate of room temperature low temperature.In addition, the also known material of stipulating its Raman spectrum analysis result (for example open flat 4-368778 communique (the 2nd～5 page, Fig. 1,2), spy are opened flat 5-159771 communique (the 2nd～7 page, Fig. 2), the spy opens flat 9-171815 communique (the 2nd～4 page, Fig. 1,2)) with reference to the spy.But,, can know that these technology can not fully satisfy high capacity and cycle characteristics according to people's of the present invention investigation.
Like this, in technology in the past, simultaneous altitude that almost can not find high power capacity satisfies the lithium secondary battery of cycle characteristics.
Summary of the invention
In view of the foregoing, the present invention has improved the negative electrode active material of being made up of material with carbon element, and the lithium secondary battery of high power capacity and cycle characteristics excellence is provided.
The result of people's further investigation of the present invention, learn by and the negative electrode active material formed by material with carbon element with 2 kinds of graphite conducts with given shape, particle diameter and proterties, the coating that adds adhesive therein is coated with on collector body and drying is carried out press molding and handled, can obtain the negative electrode for lithium secondary battery of high power capacity and cycle characteristics excellence, finish the present invention.
Negative electrode for lithium secondary battery provided by the invention, it is the negative electrode for lithium secondary battery that contains negative electrode active material and adhesive, described negative electrode active material contains graphite A and graphite B, the shape of the primary particle of described graphite A is spherical or ellipticity, the average grain diameter of the primary particle of described graphite A is 10 μ m～30 μ m, and axial crystallite size of the c of described graphite A and tap density are respectively less than 100nm, more than or equal to 1.0g/cm
3, the shape of the primary particle of described graphite B is a flat, and the average grain diameter of the primary particle of described graphite B is 1 μ m～10 μ m, and the axial crystallite size of the c of described graphite B is more than or equal to 100nm.
In addition, the invention provides the manufacture method of negative electrode for lithium secondary battery, it comprises the shape of preparing primary particle is spherical or the average grain diameter of ellipticity, primary particle is that 10 μ m～30 μ m and the axial crystallite size of c and tap density are respectively less than 100nm, more than or equal to 1.0g/cm
3The operation of graphite A; The shape of preparing primary particle is that the average grain diameter of flat, primary particle is 1 μ m～10 μ m and the axial crystallite size of the c operation more than or equal to the graphite B of 100nm; In the presence of adhesive and solvent, mix described graphite A and described graphite B and prepare the operation of coating; After described coating of coating and drying on the collector body, implement the operation that press molding is handled.
In addition, the invention provides the lithium secondary battery that comprises positive pole, described negative electrode for lithium secondary battery, nonaqueous electrolyte.
Description of drawings
Fig. 1 is that the scanning electron microscope (SEM) of the graphite A of use among the embodiment 1 amplifies outside drawing.
Fig. 2 is that the SEM of the graphite B of use among the embodiment 1 amplifies outside drawing.
Fig. 3 is the part longitudinal section of the lithium secondary battery of pattern ground expression embodiment 1.
Fig. 4 is the vertical view of the lithium secondary battery of pattern ground expression embodiment 1.
Fig. 5 is the performance plot of the cycle characteristics of each lithium secondary battery in the time of 20 ℃ of expression embodiment 1,2,6 and comparative example 1,2.
Fig. 6 is that expression is to the performance plot of 20 ℃ capacity sustainment rate as each lithium secondary battery of embodiment 1,2 and comparative example 1,2 cycle characteristics 0 ℃ the time.
Embodiment
Below, embodiments of the present invention are described.
In the present embodiment, it is the spherical or elliptoid material of 10 μ m～30 μ m that graphite A can use the average grain diameter of primary particle.This be because, if spherical or elliptoid shape, compare with general flaky graphite, (when press molding is handled) particle just is difficult to orientation during extruding, favourable to high rate flash-over characteristic and low-temperature characteristics etc., specific area diminishes, and with the reactivity reduction of organic electrolyte, thereby cycle characteristics improves.
Wherein, even the primary particle of graphite A is not spherical completely or ellipticity, also can have near spherical or near elliptoid shape, also can be that the surface of using among the embodiment 1 as described later has concavo-convex particle (with reference to Fig. 1).In addition, graphite A also can contain spherical primary particle and elliptoid primary particle both sides.
The average grain diameter of primary particle fix on 10 μ m～30 μ m be because, if less than 10 μ m, uprise with the reactivity of organic electrolyte, cycle characteristics can descend, in addition, if greater than 30 μ m, then the dispersion stabilization of negative pole coating descends, productivity ratio descends, and generates concavo-convex and the damage dividing plate in negative terminal surface, becomes the reason of internal short-circuit.
In addition, graphite A is, the axial crystallite size of c must be less than 100nm, 60～90nm preferably.If the such crystallite of size, just can suppress the reaction with organic electrolyte, and the raising cycle characteristics.
In addition, the axial crystallite size of the c of graphite A is meant, according to (002) diffracted ray that the X-ray diffraction device " RAD-RC " that uses Rigaku Denki Co., Ltd to produce is measured, uses and learns the value that the method for shaking is calculated.
And then graphite A must be that tap density is more than or equal to 1.0g/cm
3, 1.1～1.3g/cm preferably
3If have such tap density, decline, the high-energy-densityization that just can suppress to be coated with film density can pay off.
Wherein, the tap density of graphite A is meant according to Japanese Industrial Standards (JIS K1469), at 150cm
3Graduated cylinder in add 100cm
3Sample is measured sample weight, highly rap graduated cylinder 30 times from 5cm after, measure the sample volume, from these measured values, with A=W/V (A: tap density, W: sample weight (g), V: the sample volume (cm after rapping
3)) value calculated.
Among such graphite A, preferably Biao Mian at least a portion is by the composite graphite of non-graphite carbon covering.Its reason is that it is high strength that non-graphite carbon is compared with graphite, is difficult for producing the warpage that causes because of extruding, also can keep described advantage after electrode processing.In addition, because non-graphite carbon, graphite can directly not contact with organic electrolyte, and the reaction of graphite surface and nonaqueous electrolytic solution is suppressed, and can also obtain the effect that cycle characteristics further improves.
As such graphite A, the R value (R=I of the Raman spectrum when preferably exciting with the argon laser of 5145
1350/ I
1580) (I
1350Be 1350cm
-1Neighbouring raman scattering intensity, I
1580Be 1580cm
-1Near raman scattering intensity) more than or equal to 0.4, especially preferably 0.5～3.0.If above-mentioned R value will be insufficient by the covering of non-graphite carbon less than 0.4, be easy to generate the warpage that causes because of extruding, and the reaction of graphite surface and organic electrolyte can not get suppressing, and is difficult to pay off in the improvement of cycle characteristics.
Wherein, above-mentioned R value is to use the raman spectroscopy of the argon laser of 5145 , mensuration 1580cm
-1Near peak intensity I
1580With 1350cm
-1Near peak intensity I
1350, from its strength ratio (I
1350/ I
1580) obtain.
In addition, graphite A is, the axial ratio (maximum gauge of primary particle is divided by the value of minimum diameter) of preferred primary particle is more than or equal to 1.2, and preferably smaller or equal to 3.The preferred axes ratio is because the contact between graphite particle will improve like this, follows the increase of the contact resistance of charge and discharge cycles to be inhibited more than or equal to 1.2.More preferably axial ratio is more than or equal to 1.5.In addition, if axial ratio is greater than 3, when preparation negative pole coating, graphite particle is destroyed easily, the new graphite particle surface that produces may cause the cycle characteristics variation with the reaction of organic electrolyte, for fear of this situation, preferred axes than smaller or equal to 3, be more preferably less than and equal 2.5.
In the present embodiment, the content of graphite A is, with respect to the total weight of graphite A and graphite B described later, and preferred 10 weight %～90 weight %, preferred especially 20 weight %～80 weight %.If less than 10 weight %, the effect of the raising cycle characteristics that is caused by mixing will diminish, and if greater than 90 weight %, then the manufacturing leeway of coating preparation condition and press molding treatment conditions will narrow down, the worry that has manufacturing cost to rise.
In the present embodiment, graphite B must be that the average grain diameter of primary particle is the graphite particle of the flat of 1 μ m～10 μ m, and preferably this primary particle is gathered or is combined into its oriented surface dispersion, forms the offspring of average grain diameter 10 μ m～30 μ m.Coating has the graphite B of such offspring structure and the compo of graphite A on collector body, the extruding of dry back, then, graphite B contacts owing to freely changing shape between the graphite A of primary particle, so can form the good electrical conductivity passage, become big with the contact area of the big graphite A of particle diameter, descend with the contact resistance of graphite A.Therefore, the large current characteristic at initial stage improves, and makes big contribution to improving active material utilization and cycle characteristics.
If the average grain diameter of the primary particle of graphite B diminishes, because graphite B self capacity diminishes, will diminish as the electrode capacity of battery, so the average grain diameter of the primary particle of graphite B is decided to be more than or equal to 1 μ m, be preferably greater than and equal on the 2 μ m, more preferably greater than equaling 4 μ m.In addition, if it is big that the average grain diameter of the primary particle of graphite B becomes, then be difficult to the negative pole densification, it is difficult that high capacity just becomes, in addition, owing to tail off with the contact point of graphite A, the effect that descends with the contact resistance of graphite A just diminishes, and the effect that causes cycle characteristics to improve reduces, so be decided to be smaller or equal to 10 μ m, preferably smaller or equal to 8 μ m, be more preferably less than and equal 7 μ m.
In addition, graphite B must be more than or equal to 100nm, 105～150nm preferably at the axial crystallite size of c.If the crystallite of such size, the negative electrode active material that has high power capacity owing to conduct is worked, so, can obtain high-capacity electrode.
Wherein, the axial crystallite size of the c of graphite B is meant, according to (002) diffracted ray that the X-ray diffraction device " RAD-RC " that uses Rigaku Denki Co., Ltd to produce is measured, uses and learns the value that the method for shaking is calculated.
In addition, the axial ratio of the preferred primary particle of graphite B (maximum gauge of plate face is divided by the value of thickness of slab) is more than or equal to 1.5, and preferably smaller or equal to 5.Be preferably greater than equal 1.5 be because, identical during with graphite A, the contact between graphite particle improves, and follows the increase of the contact resistance of circulation to be suppressed.In addition, be that graphite particle is destroyed and cause the cycle characteristics variation in order to prevent to prepare negative pole coating preferably smaller or equal to 5.
In the present embodiment, above-mentioned graphite A and graphite B, preferably one of them side is a native graphite, more preferably both sides are native graphite.Native graphite cheapness and capacity height can be made the high electrode of cost performance thus.
In the present embodiment, the an amount of cooperation has the spherical or elliptoid graphite A of above-mentioned specified particle diameter and proterties and the graphite B with flat of same specified particle diameter and proterties, in the presence of adhesive and suitable solvent such as water, they are mixed and prepare coating, after this coating of coating and drying on the suitable collector bodies such as Copper Foil, push (press molding processing) with roller etc., make negative electrode for lithium secondary battery.
In the present embodiment, the adhesive that uses during as the above-mentioned negative pole of manufacturing, the mixture of preferred water-base resin (resin) and rubber resin with the character of in water, dissolving or disperseing.Because water-base resin can help the dispersion of graphite, electrode expansion and contraction that rubber resin then has when preventing because of charge and discharge cycles cause the effect of filming and peeling off from collector body.
Water-base resin has for example celluosic resins such as polyvinylpyrrolidone, Hydrin, polyvinyl pyridine, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyethers resins such as polyethylene glycol oxide, polyethylene glycol.Rubber resin has for example latex, butyl rubber, fluorubber, styrene butadiene rubbers, ethylene-propylene-diene copolymer, polybutadiene, ethylene-propylene-diene copolymer (EPDM) etc.Prevailing is the combination of carboxymethyl cellulose and styrene butadiene ribber.
In the negative electrode for lithium secondary battery of making like this, because graphite A has high strength, so be difficult to take place because of pushing the change of shape of generation, graphite B is at when extruding changes shape and contacting between the primary particle of graphite A freely, so, it is high more that negative pole is coated with film density, can bring into play the mixed effect of graphite A and graphite B more more effectively.Negative pole after the extruding is coated with film density and is preferably greater than and equals 1.4g/cm
3, more preferably greater than equaling 1.5g/cm
3But if density is too high, even the combination of graphite A and graphite B, utilance also can descend, so preferably smaller or equal to 1.9g/cm
3, be more preferably less than and equal 1.8g/cm
3
In the present embodiment, use above-mentioned negative electrode for lithium secondary battery, across dividing plates such as microporous polyethylene films, this negative pole and use LiCoO pack in battery case
2, LiNiO
2, LiMn
2O
4At the positive pole of lithium-contained composite oxide, it is infused in the non-polar solvens such as ethylene carbonate or methyl ethyl carbonate and is dissolved with LiPF as positive active material
6Deng the aqueous nonaqueous electrolyte of solute, seal, thereby can make the lithium secondary battery of different shapes such as tubular, square, pancake, coin shape.
In the above-mentioned lithium secondary battery of the negative electrode for lithium secondary battery that uses present embodiment, if in nonaqueous electrolyte, add vinylene carbonate, can obtain more stable cycle characteristics, be preferred therefore.The addition of vinylene carbonate, with respect to nonaqueous electrolyte weight, be preferably greater than equal 0.5 weight %, more preferably greater than equaling 1 weight %, further be preferably greater than to equal 2 weight %.And, if too much, just have the tendency that storage characteristics descends, thus preferably smaller or equal to 6 weight %, be more preferably less than and equal 5 weight %, further preferably smaller or equal to 4 weight %.
Like this, in the present embodiment, be used as the negative electrode active material formed by material with carbon element by the graphite B that is used in combination spherical or elliptoid graphite A and has a flat of same specified particle diameter and proterties, can provide the negative electrode for lithium secondary battery of high power capacity and cycle characteristics excellence and use its lithium secondary battery with specified particle diameter and proterties.
Below, as embodiments of the invention, record embodiment 1～6, record simultaneously is used for and its comparative example 1～3 relatively, more specifically describes the present invention.But the present invention has more than and is limited to these embodiment.
(embodiment 1)
As graphite A, using the axial crystallite size of c is the face interval d of 88.5nm, (002) face
002=0.3357nm, be that the R value of 17 μ m, Raman spectrum is 1.670, tap density is 1.19g/cm by the average grain diameter of the primary particle of SEM
3, specific area is 3.12m
2/ g, in its surface coverage the graphite A1 of the non-graphite carbon that form by sintering pitch of 3～4 weight %.Fig. 1 represents the outward appearance of this graphite A1 by SEM.As shown in Figure 1, graphite A1 contains at least near elliptoid primary particle.
As graphite B, using the axial crystallite size of c is the face interval d of 116nm, (002) face
002=0.3362nm, be that the average grain diameter of the primary particle of 19 μ m, flat is that 1～9 μ m, tap density are 0.59g/cm by the average grain diameter of the offspring of SEM
3, specific area is 4.40m
2The graphite of/g.Fig. 2 represents the outward appearance of this graphite B by SEM.As shown in Figure 2, graphite B is the primary particle set of flat and formed offspring.
With the material of the mixed of 30 this graphite of weight % A1,70 weight % graphite B as negative electrode active material.The negative electrode active material 98 weight % of 2 kinds of graphite of this mixing, as carboxymethyl cellulose (CMC) the 1 weight % and styrene butadiene ribber (SBR) the 1 weight % of adhesive, mix with water, prepare negative pole coating.(thickness: behind this negative pole coating of two sided coatings 10 μ m), dry water as solvent pushes with roller being used as the Copper Foil of negative electrode collector.Being coated with film density is 1.50g/cm
3Then, severing, body is drawn in welding, makes banded negative pole.
In addition, at the LiCoO of 90 weight % as positive active material
2, in the carbon black and the Kynoar of 5 weight % of 5 weight % as conductive agent, mix N-N-methyl-2-2-pyrrolidone N-(NMP) as solvent as adhesive, prepare positive electrode coating.
(thickness: behind this positive electrode coating of two sided coatings 15 μ m), dry NMP as solvent pushes with roller at the aluminium foil as positive electrode collector.Then, body is drawn in severing, welding, makes strip-shaped positive electrode.
Then, above-mentioned strip-shaped positive electrode and banded negative pole, across microporosity polyethylene film as the thick 20 μ m of dividing plate, be wound into swirl shape, form the electrode coiling body, this coiling body be filled to wide 34.0mm as battery case, the aluminum of thick 4.0mm, high 50.0mm has in the outer tinning of bottom tube-like.The anodal collector plate of above-mentioned anodal process is welded in positive terminal, and above-mentioned negative pole is welded in negative terminal through the negative pole collector plate.
In addition, as aqueous nonaqueous electrolyte, prepare in mixed solvent, with 1.2 moles/dm with 1: 2 mixed ethylene carbonate (EC) of volume ratio and methyl ethyl carbonate (MEC)
3Ratio dissolving LiPF
6, and then interpolation is the vinylene carbonate (VC) of 3.0 weight % with respect to nonaqueous electrolyte weight.Then, outside above-mentioned, inject this aqueous nonaqueous electrolyte in the tinning, nonaqueous electrolyte is fully soaked into after, seal, make square lithium secondary battery.
Fig. 3 and Fig. 4 represent the lithium secondary battery that this is square, and Fig. 3 is that part longitudinal section, Fig. 4 of above-mentioned battery is vertical view.
Among two figure, the 1st, positive pole, the 2nd, negative pole, the 3rd, dividing plate, the 4th, battery case, the 5th, insulator, the 6th, electrode coiling body, the 7th, positive pole draw body, the 8th, and negative pole draws body, the 9th, cover plate, the 10th, insulating package, the 11st, terminal, the 12nd, insulator, the 13rd, corbel back slab.
(embodiment 2)
Except with the material of the mixed of 70 weight % graphite A1,30 weight % graphite B as the negative electrode active material, carry out similarly to Example 1, make square lithium secondary battery.The density that negative pole is filmed is 1.50g/cm
3
(embodiment 3)
Except with the material of the mixed of 50 weight % graphite A1,50 weight % graphite B as the negative electrode active material, carry out similarly to Example 1, make square lithium secondary battery.The density that negative pole is filmed is 1.51g/cm
3
(embodiment 4)
Except with the material of the mixed of 90 weight % graphite A1,10 weight % graphite B as the negative electrode active material, carry out similarly to Example 1, make square lithium secondary battery.The density that negative pole is filmed is 1.52g/cm
3
(embodiment 5)
Except with the material of the mixed of 10 weight % graphite A1,90 weight % graphite B as the negative electrode active material, carry out similarly to Example 1, make square lithium secondary battery.The density that negative pole is filmed is 1.48g/cm
3
(comparative example 1)
Except only using graphite B as the negative electrode active material, carry out similarly to Example 1, make square lithium secondary battery.The density that negative pole is filmed is 1.50g/cm
3
(comparative example 2)
Except only using graphite A1 as the negative electrode active material, carry out similarly to Example 1, make square lithium secondary battery.The density that negative pole is filmed is 1.50g/cm
3
(embodiment 6)
As graphite A, using the axial crystallite size of c is the face interval d of 88.5nm, (002) face
002=0.3357nm, be that the R value of 17 μ m, Raman spectrum is 0.112, tap density is 1.20g/cm by the average grain diameter of the primary particle of SEM
3, specific area is 3.45m
2/ g, sintering pitch does not cover the graphite A2 of non-graphite carbon on its surface.Except with the material of the mixed of 30 this graphite of weight % A2,70 weight % graphite B as the negative electrode active material, carry out similarly to Example 1, make square lithium secondary battery.The density that negative pole is filmed is 1.50g/cm
3
(comparative example 3)
Except only using graphite A2 as the negative electrode active material, carry out similarly to Example 6, make square lithium secondary battery.The density that negative pole is filmed is 1.51g/cm
3
Performance for each lithium secondary battery of investigating the foregoing description 1～6 and comparative example 1～3,20 ℃, with constant current discharge, the final discharging voltage 3.0V of the constant-current constant-voltage of 800mA4.2V charging 2.5 hours, 800mA, carry out cyclic test in this condition.And, the discharge capacity after 400 circulations divided by the value of discharge capacity of the 1st circulation as the capacity sustainment rate.These results are as shown in table 1.And then, about the battery of embodiment 1,2,6 and comparative example 1,2, represent the result of above-mentioned cyclic test at Fig. 5.
In addition, particularly, also carry out and above-mentioned same cyclic test at 0 ℃ to each lithium secondary battery of embodiment 1,2 and comparative example 1,2, each discharge capacity in the time of 0 ℃ during divided by 20 ℃ each discharge capacity and obtain the capacity sustainment rate.These results as shown in Figure 6.
Table 1
| The discharge capacity (mAh) of 1 circulation | The discharge capacity (mAh) of 400 circulations | Capacity sustainment rate (%) | |
| Embodiment 1 | 791 | 696 | 87.99 |
| | 796 | 689 | 86.56 |
| Embodiment 3 | 789 | 691 | 87.58 |
| | 795 | 685 | 86.16 |
| | 791 | 687 | 86.85 |
| Comparative example 1 | 797 | 681 | 85.45 |
| Comparative example 2 | 790 | - | - |
| | 782 | 671 | 85.80 |
| Comparative example 3 | 775 | - | - |
From the result of above-mentioned table 1 and Fig. 5 as can be known, drop to 50% discharge capacity of the 1st circulation and end test at 30 circulation times with respect to the lithium secondary battery of the comparative example 2 that only uses graphite A1, each lithium secondary battery of embodiment 1～5 that use has mixed the negative pole of graphite A1 and graphite B is, even after 400 circulations, also keep the discharge capacity more than 85% of the 1st circulation, cycle characteristics obtains tremendous raising.And, compare with the lithium secondary battery of the comparative example 1 that only uses graphite B, also can know to access the above cycle characteristics of equal extent.
In addition, even use the lithium secondary battery of the embodiment 6 of the negative pole mixed the graphite A2 that do not cover non-graphite carbon and graphite B, also same as described above, compare with the lithium secondary battery of the comparative example 3 that only uses graphite A2, cycle characteristics improves greatly, can see significant effect.In addition, can know also with the contrast of embodiment 1 that by covering with non-graphite carbon, it is big that the discharge capacity of the 1st circulation becomes by this embodiment 6.
Then, from the result of above-mentioned Fig. 6 as can be known, use has mixed the lithium secondary battery of embodiment 1,2 of the negative pole of graphite A1 and graphite B, compare with the lithium secondary battery of the comparative example 1 that only uses graphite B, the tremendous raising of cycle characteristics in the time of 0 ℃, compare with the lithium secondary battery of the comparative example 2 that only uses graphite A1, also can obtain the cycle characteristics of equal extent.
From the result of above Fig. 5, Fig. 6 and table 1 as can be known,, constitute negative pole, can obtain the negative electrode for lithium secondary battery of cycle characteristics, low-temperature characteristics excellence by admixed graphite A and graphite B according to the present invention.
The reason that can access above-mentioned excellent effect according to the present invention is inferred to be, because the graphite B that uses distortion when extruding, make between the graphite A, the conductivity of graphite A and graphite B and active material and Copper Foil improves, and then based on being covered by non-graphite carbon, the reaction of graphite surface and nonaqueous electrolyte is suppressed.
The possibility of utilizing on the industry
Like this, lithium secondary battery of the present invention, as the cheap battery of high power capacity and cycle characteristics excellence, can be used as portable electronic machines such as mobile phone and subnotebook PC etc. can repeated charge the secondary cell of high power capacity.
Claims (12)
1. negative electrode for lithium secondary battery, it is the negative electrode for lithium secondary battery that contains negative electrode active material and adhesive, it is characterized by, described adhesive is made up of water-base resin and rubber resin, described negative electrode active material contains graphite A and graphite B, the shape of the primary particle of described graphite A is spherical or ellipticity, the average grain diameter of the primary particle of described graphite A is 10 μ m～30 μ m, and axial crystallite size of the c of described graphite A and tap density are respectively less than 100nm, more than or equal to 1.0g/cm
3The shape of the primary particle of described graphite B is a flat, the average grain diameter of the primary particle of described graphite B is 1 μ m～10 μ m, the axial crystallite size of the c of described graphite B is more than or equal to 100nm, and at least a portion on the surface of described graphite A is further covered by non-graphite carbon, and the R value of the Raman spectrum of the described graphite A when exciting with the argon laser of wavelength 5145 is more than or equal to 0.4, and described R value is R=I
1350/ I
1580, I in the formula
1350Be 1350cm
-1Neighbouring raman scattering intensity, I
1580Be 1580cm
-1Near raman scattering intensity.
2. negative electrode for lithium secondary battery as claimed in claim 1, the set of the primary particle of described graphite B or in conjunction with and form offspring, the average grain diameter of described offspring is 10 μ m～30 μ m.
3. negative electrode for lithium secondary battery as claimed in claim 1, the part by weight of described graphite A is a benchmark with the total weight of described graphite A and described graphite B, is 10 weight %～90 weight %.
4. negative electrode for lithium secondary battery as claimed in claim 1, described negative electrode for lithium secondary battery be coated with film density more than or equal to 1.5g/cm
3
5. the manufacture method of a negative electrode for lithium secondary battery, to comprise the shape of preparing primary particle be spherical or the average grain diameter of ellipticity, primary particle is that 10 μ m～30 μ m and the axial crystallite size of c and tap density are respectively less than 100nm, more than or equal to 1.0g/cm
3The operation of graphite A; The shape of preparing primary particle is that the average grain diameter of flat, primary particle is 1 μ m～10 μ m and the axial crystallite size of the c operation more than or equal to the graphite B of 100nm; In the presence of the adhesive of forming by water-base resin and rubber resin and solvent, mix described graphite A and described graphite B, prepare the operation of coating; After described coating of coating and drying on the collector body, implement the operation that press molding is handled, and at least a portion on the surface of described graphite A is further covered by non-graphite carbon, and the R value of the Raman spectrum of the described graphite A when exciting with the argon laser of wavelength 5145 is more than or equal to 0.4, and described R value is R=I
1350/ I
1580, I in the formula
1350Be 1350cm
-1Neighbouring raman scattering intensity, I
1580Be 1580cm
-1Near raman scattering intensity.
6. the manufacture method of negative electrode for lithium secondary battery as claimed in claim 5, the primary particle set of described graphite B or in conjunction with and form offspring, the average grain diameter of described offspring is 10 μ m～30 μ m.
7. the manufacture method of negative electrode for lithium secondary battery as claimed in claim 5, the part by weight of described graphite A is a benchmark with the total weight of described graphite A and described graphite B, is 10 weight %～90 weight %.
8. lithium secondary battery, it is the lithium secondary battery that contains positive pole, negative pole, nonaqueous electrolyte, it is characterized by, described negative pole contains negative electrode active material and adhesive, described adhesive is made up of water-base resin and rubber resin, described negative electrode active material contains graphite A and graphite B, the shape of the primary particle of described graphite A is spherical or ellipticity, the average grain diameter of the primary particle of described graphite A is 10 μ m～30 μ m, and axial crystallite size of the c of described graphite A and tap density are respectively less than 100nm, more than or equal to 1.0g/cm
3The shape of the primary particle of described graphite B is a flat, the average grain diameter of the primary particle of described graphite B is 1 μ m～10 μ m, the axial crystallite size of the c of described graphite B is more than or equal to 100nm, and at least a portion on the surface of described graphite A is further covered by non-graphite carbon, and the R value of the Raman spectrum of the described graphite A when exciting with the argon laser of wavelength 5145 is more than or equal to 0.4, and described R value is R=I
1350/ I
1580, I in the formula
1350Be 1350cm
-1Neighbouring raman scattering intensity, I
1580Be 1580cm
-1Near raman scattering intensity.
9. lithium secondary battery as claimed in claim 8, the set of the primary particle of described graphite B or in conjunction with and form offspring, the average grain diameter of described offspring is 10 μ m～30 μ m.
10. lithium secondary battery as claimed in claim 8, the part by weight of described graphite A is a benchmark with the total weight of described graphite A and described graphite B, is 10 weight %～90 weight %.
11. lithium secondary battery as claimed in claim 8, described negative pole be coated with film density more than or equal to 1.5g/cm
3
12. lithium secondary battery as claimed in claim 8, described nonaqueous electrolyte contains vinylene carbonate.
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| JP013117/2003 | 2003-01-22 | ||
| JP2003013117 | 2003-01-22 | ||
| JP191909/2003 | 2003-07-04 | ||
| JP002649/2004 | 2004-01-08 |
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| CN101417794B (en) * | 2007-10-26 | 2011-06-22 | 顾向宏 | Production manufacturing method of high rate lithium ionic cell cathode F series material |
| WO2010007898A1 (en) * | 2008-07-17 | 2010-01-21 | 住友金属工業株式会社 | Mixed carbon material and negative electrode for nonaqueous rechargeable battery |
| CN103081191B (en) * | 2010-08-05 | 2015-05-20 | 昭和电工株式会社 | Anode active material for lithium secondary battery |
| WO2013098962A1 (en) * | 2011-12-27 | 2013-07-04 | 株式会社日立製作所 | Nonaqueous secondary battery |
| WO2014157010A1 (en) * | 2013-03-29 | 2014-10-02 | 株式会社Uacj | Collector, electrode structure, nonaqueous electrolyte battery, and electricity storage component |
| EP3131140B1 (en) | 2014-03-25 | 2020-06-17 | Tosoh Corporation | Negative electrode active material for lithium ion secondary battery, and method for producing same |
| KR102088491B1 (en) * | 2015-12-23 | 2020-03-13 | 주식회사 엘지화학 | Negative electrode active material for lithium secondary battery and negative electrode for lithium secondary battery comprising the same |
| KR102095008B1 (en) * | 2016-09-13 | 2020-03-30 | 주식회사 엘지화학 | Negative electrode, secondary battery, battery module and battery pack comprising the same |
| WO2021190650A1 (en) * | 2020-03-27 | 2021-09-30 | 宁德时代新能源科技股份有限公司 | Secondary battery, battery module comprising same, battery pack, and device |
| EP4180394A4 (en) * | 2021-09-22 | 2023-08-30 | Contemporary Amperex Technology Co., Limited | Composite artificial graphite and preparation method therefor, secondary battery containing composite artificial graphite, and power-consuming apparatus |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10241683A (en) * | 1997-02-26 | 1998-09-11 | Mitsubishi Cable Ind Ltd | Negative electrode active material for lithium secondary battery |
| JP2001135304A (en) * | 1999-11-09 | 2001-05-18 | Kyushu Electric Power Co Inc | Negative electrode of lithium ion secondary battery and lithium ion secondary battery |
| JP2002313323A (en) * | 2001-04-13 | 2002-10-25 | Toyota Central Res & Dev Lab Inc | Negative electrode for use in lithium secondary battery and lithium secondary battery using it |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10241683A (en) * | 1997-02-26 | 1998-09-11 | Mitsubishi Cable Ind Ltd | Negative electrode active material for lithium secondary battery |
| JP2001135304A (en) * | 1999-11-09 | 2001-05-18 | Kyushu Electric Power Co Inc | Negative electrode of lithium ion secondary battery and lithium ion secondary battery |
| JP2002313323A (en) * | 2001-04-13 | 2002-10-25 | Toyota Central Res & Dev Lab Inc | Negative electrode for use in lithium secondary battery and lithium secondary battery using it |
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