CN100466340C - Non-aqueous electrolyte rechargeable battery - Google Patents
Non-aqueous electrolyte rechargeable battery Download PDFInfo
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- CN100466340C CN100466340C CNB2006100937471A CN200610093747A CN100466340C CN 100466340 C CN100466340 C CN 100466340C CN B2006100937471 A CNB2006100937471 A CN B2006100937471A CN 200610093747 A CN200610093747 A CN 200610093747A CN 100466340 C CN100466340 C CN 100466340C
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Abstract
The present invention discloses a non-aqueous electrolyte secondary battery including: a positive electrode; a negative electrode, and a non-aqueous electrolyte. The negative electrode includes a negative electrode active material that includes at least Si. The non-aqueous electrolyte includes lithium hexafluorophosphate as a main supporting electrolyte and has an acid content of not less than 50 ppm and not more than 200 ppm. The negative electrode has a potential of not less than 0.6 V and not more than 1.5 V relative to a Li electrode at an end-of-discharge voltage of the battery. The battery is prevented from suffering degradation of storage characteristics caused by the dissolution reaction of Si from the negative electrode during charging and the precipitation reaction of the dissolved Si.
Description
Technical field
The present invention relates to rechargeable nonaqueous electrolytic battery, and especially relate to a kind of rechargeable nonaqueous electrolytic battery that comprises preferred negative pole and nonaqueous electrolyte.
Background technology
The lithium metal can be realized high voltage and high-energy-density, uses the lithium metal to obtain extensive studies and exploitation as the negative pole of rechargeable nonaqueous electrolytic battery.These research and development have caused using the commercialization of the lithium ion battery of graphite material in negative pole, graphite material is the absorption and desorption lithium reversibly, and has outstanding cycle life and fail safe.
Yet, use battery available capacity to be about 350mAh/g based on the graphite material negative pole, this value has been in close proximity to the theoretical capacity (372mAh/g) of graphite material.Therefore, as long as in negative pole, use graphite material, with regard to the unlikely capacity that increases substantially.Simultaneously, the function of mancarried device is just becoming and is becoming increasingly complex, and also requires correspondingly to improve as the capacity of the rechargeable nonaqueous electrolytic battery of this kind equipment energy source.Therefore, in order to obtain higher capacity, the taller negative material of Capacity Ratio graphite must be arranged.
As the material that high power capacity can be provided, the alloy material that contains silicon (Si) has obtained people's attention recently with the alloy material that contains tin.These metallic elements are the absorption and desorption lithium ion electrochemically, can carry out charge/discharge with the capacity more much higher than graphite.For example, the theoretical discharge capacity of known silicon is 4199mAh/g, and this is 11 times of theoretical discharge capacity of graphite.
Therefore, now studying and using siliceous negative active core-shell material, be used the battery of conventional lithium secondary battery element, these conventional lithium secondary battery elements such as lithium cobaltate cathode and the nonaqueous electrolyte of forming by the mixed solution of 1mol/L lithium hexafluoro phosphate and ethylene carbonate and methyl ethyl carbonate simultaneously.Yet if this class battery is stored in high temperature, especially under discharge condition, their are very easy to degenerate.Therefore, there is the problem that storage back battery functi on lost efficacy in this class battery.
For fear of this problem, preferably the negative discharge electromotive force is minimized.For example, Japan publication publication number Hei 11-233155 (patent documentation 1) suggestion is by using SiO as negative active core-shell material and will be controlled at 0.6V or lower with respect to the discharge off electromotive force of the negative pole of Li electrode, thereby will reduce to minimum because of the capacitance loss that charge/discharge cycle causes.
Yet, if limit discharge potential,, can only utilize the only about half of of the intrinsic capacity of SiO because SiO is 0.4V～0.5V with respect to the average discharge potential of Li electrode as patent documentation 1, therefore, sacrificed the intrinsic high capacity characteristics of SiO.
Summary of the invention
The purpose of this invention is to provide a kind of rechargeable nonaqueous electrolytic battery, this rechargeable nonaqueous electrolytic battery can make full use of based on the negative material of Si intrinsic high power capacity, and can not cause the reduction of storage characteristics and charge/discharge cycle characteristics.
The present invention relates to a kind of rechargeable nonaqueous electrolytic battery, this battery comprises: the electrochemically positive pole of absorption and desorption Li, the negative pole that comprises the negative active core-shell material that contains Si at least and nonaqueous electrolyte.
Nonaqueous electrolyte is included as the lithium hexafluoro phosphate as lithium salts of main supporting electrolyte, and the acid content of this nonaqueous electrolyte is not less than 50ppm and is not higher than 200ppm.Described negative pole is not less than 0.6V and is not higher than 1.5V with respect to the electromotive force of Li electrode under the battery discharge final voltage.
The present invention is that the basis is accomplished with following research.
Take the conventional batteries of the problems referred to above apart, measure negative pole with respect to Li electrode (Li/Li
+) electromotive force.Found that with respect to Li/Li
+Electromotive force be 1.8V.Simultaneously, calculate and be dissolved in electrolytical Si content, find that the contained Si of negative pole has 1/100 to be dissolved in the nonaqueous electrolyte approximately.In addition, analyze with nonaqueous electrolyte generation side reaction in the formed coated film in negative active core-shell material surface, measure a large amount of Si compounds that contain, contain the organic and inorganic compound of Li simultaneously in addition.
This reaction is scrutinized, is inferred following reaction has taken place when Si contained in the negative active core-shell material is dissolved in electrolyte:
Si+2HF+nh
+＝>SiF
2+2H
++(n-1)e
- (1)
(h
+The expression hole)
When battery is in when having HF in discharge condition (promptly when electronics leaves negative pole) and the nonaqueous electrolyte, Si has formed SiF by the reaction shown in the reaction equation (1)
2, and be dissolved in the nonaqueous electrolyte.SiF
2Be deposited in other position of negative terminal surface or battery by following chemical reaction as the compound of Si.
SiF
2+4HF＝>H
2SiF
6+H
2 (2)
When Si contained in the negative active core-shell material is dissolved in nonaqueous electrolyte and with the form of Si compound precipitation takes place, believe these reactions have taken place.Be dissolved in nonaqueous electrolyte and Si and be deposited in the surface of negative pole with the form of Si compound in order to suppress between charge period contained Si in the negative active core-shell material, the inventor finds that following condition is effective:
(1) nonaqueous electrolyte comprises lithium hexafluoro phosphate, is main lithium salts with it.
(2) acid content of nonaqueous electrolyte is not less than 50ppm and is not higher than 200ppm.
(3) under the battery discharge final voltage, promptly when cell voltage is in final discharging voltage or when battery is discharged to final discharging voltage, negative pole is not less than 0.6V and is not higher than 1.5V with respect to the electromotive force of Li electrode.
The preferred Si of negative active core-shell material, Si alloy or Si compound.
The preferred available SiO of Si compound
xThe oxide of expression, wherein 0＜x＜2.The preferred 1000ppm of the total content of the Fe that comprises in the Si alloy, Ni, Co, Cu and Cr or lower.
Negative pole preferably includes anode collector and the negative active core-shell material film that is deposited on the anode collector.
Nonaqueous electrolyte preferably contains two [1,2-oxalic acid (2-)-O, the O '] borate ions that are not higher than 5 weight %.
The present invention can make full use of based on the negative material of Si intrinsic high power capacity.Simultaneously, the present invention can address the above problem, and promptly can control Si and under the discharge condition solubilizing reaction and the caused film forming reaction of Si because of dissolving take place.Therefore, can provide a kind of rechargeable nonaqueous electrolytic battery with outstanding storage characteristics and outstanding charge.
Though in appending claims, proposed new feature of the present invention especially, but can be better from the detailed description of doing below in conjunction with accompanying drawing, no matter be from tissue or on content, understanding and cognition the present invention and relevant other purpose and feature thereof.
Description of drawings
Fig. 1 is the longitudinal profile schematic diagram of employed cylindric lithium rechargeable battery in the embodiment of the invention.
Detailed Description Of The Invention
Electrochemically the negative active core-shell material of absorption and desorption Li comprises Si according to the present invention. More clearly, negative active core-shell material is Si, Si alloy or Si compound.
The Si alloy preferably has the Si content greater than 50 % by weight. Particularly preferred Si alloy has 75 % by weight or above Si content. This class alloy can provide high capacity.
The impurity element that comprises in Si alloy, Si or the Si compound is preferably Ti, Zr or Sn. Further, also preferably include P or Sb. In addition, have Fe, Ni, Co, Cu or Cr if wherein comprise the unit that will have a negative impact, the total content of Fe, Ni, Co, Cu and Cr is 1000ppm or lower ideally.
Its reason is as follows: Ti, Zr, Sn, P or Sb, and just in time the same with Si, have 4 valencys or higher chemical valence. Therefore, when Ti, Zr, Sn, P or Sb and Si formation alloy, unlikely form the hole, but can produce free electron (carrier), thereby these elements can produce the favourable effect that increases electric conductivity. On the other hand, Fe, Ni, Co, Cu or Cr are 3 valencys or divalent when Si is combined. Therefore, when forming alloy with Si, can form the hole in the alloy, thereby between charge period, can impel the Si dissolving.
The Si compound is preferably SiOx, 0＜x＜2 wherein. Especially when 0＜x≤1, can obtain capacity height, long negative pole of life-span. The ratio of x value representation oxygen and whole negative active core-shell materials, for example, can be according to firing method by oxygen be quantized to be measured. This compound S iOxCan be formed by multiple partly, perhaps can be by forming fully uniformly. The examples of compounds of the previous case is SiO0.8, wherein outermost layer is SiO0.3, the intermediate layer is SiO0.7, the most the lower layer of is SiO0.9。
As mentioned above, the negative active core-shell material based on Si is preferably unbodied or low crystallization. As used herein " low crystallization " refer to that grain size is 50nm or following. By Schuler (Scherrer) equation, the half-breadth at the strongest peak can calculate grain size from X-ray diffraction pattern.
" unbodied " refers in the X-ray diffraction pattern to have wide peak in the scope of 2 θ=15～40 ° simultaneously, as used herein. For the negative active core-shell material of crystallization, when it expanded because inserting Li, the particle of negative active core-shell material or film can break or damage. Consequently, the response area of negative active core-shell material increases, and therefore with the contained hydrofluoric acid of nonaqueous electrolyte more touch opportunity has been arranged. Therefore, promoted the precipitation reaction of solubilizing reaction and the Si compound of Si. On the other hand, for the negative active core-shell material of amorphous or low crystallization, it can expand when inserting Li, but because it is cut apart by small crystal boundary (approximately from several nanometers to 50nm), swelling stress is disperseed by corresponding crystal boundary and weakens. Consequently, unlikely generation active material particles or film breaks or breakage.
In an optimal way that comprises based on the negative pole of the negative active core-shell material of Si, in anode collector electrode mixture layer and adhesive are arranged, this electrode mixture layer contains the negative active core-shell material particle at least. In another optimal way, on anode collector, provide negative active core-shell material with the deposited film that forms by physics or chemical method or the form of sintered membrane. At one particularly preferably in the mode, the deposited film of negative active core-shell material is formed on the anode collector by physical method.
The size of the negative active core-shell material particle that uses in the electrode mixture layer is preferably and is not less than 0.1 μ m and is not more than 50 μ m. Adhesive can be any material, as long as its can bond anode collector and negative active core-shell material, and in the battery operation potential range on electrochemistry torpescence. Suitable demonstration adhesive comprises styrene-butylene copolymer rubber, polyacrylic acid, polyethylene, polyurethane, polymethyl methacrylate, polyvinylidene fluoride, polytetrafluoroethylene (PTFE), carboxymethyl cellulose and methylcellulose etc. They can use separately, also use capable of being combined. For the amount of adhesive, amount is The more the better with regard to the structure that keeps the electrode mixture layer, but with regard to improve battery capacity, to improve with regard to the flash-over characteristic amount more few better. The electrode mixture layer further preferably contains the conductive agent that mainly is comprised of carbon such as graphite, carbon black or CNT. These conductive agents preferably contact with negative active core-shell material.
The preferred physical method that forms deposited film is sputter, vapor deposition, thermal spray and bead, and preferred chemical method is CVD and plating. Form in the method for deposited film at these, particularly preferably vapor deposition because vapor deposition can form at a high speed film, and is suitable for forming the deposited film that is not less than several microns and is not more than 50 μ m. Deposited film is flat or smooth film not necessarily, and the active material of deposition can be column or island. Sintered membrane contains the electrode mixture layer of negative active core-shell material ideally by formation, and it is carried out sintering processes provides by heating or isoionic method.
When the deposited film of negative active core-shell material or sintered membrane only were comprised of Si, preferred thickness was for being not less than 1 μ m and being not more than 20 μ m. When film was thinner than 1 μ m, current-collector was large with respect to the volume of battery, was difficult to produce battery capacious with this. On the other hand, if thickness in 20 μ m, the stress that expand to produce because of active material can obvious effect on whole current-collector or negative pole, thus can the wrinkle electrode or cause electrode finally to be ruined. Therefore, the thickness greater than 20 μ m is also improper. When the deposited film of negative active core-shell material or sintered membrane are comprised of Si alloy or Si compound since with same cause described above, the thickness of film preferably is not less than 3 μ m and is not more than 50 μ m.
Each film thickness mentioned above all refers to insert the thickness before the lithium, and is almost equal with the film thickness under the discharge condition (battery status when being discharged to final discharging voltage).
The electrode mixture layer thickness that contains negative active core-shell material preferably is not less than 10 μ m and is not more than 100 μ m. If the electrode mixture bed thickness is in 100 μ m, nonaqueous electrolyte is difficult to be penetrated near the current-collector, and negative active core-shell material just can not be fully utilized like this. Simultaneously, when it is thinner than 10 μ m, too large with respect to the current-collector volume of electrode. Consequently, the battery capacity variation, and this is undesirable.
Nonaqueous electrolyte comprises nonaqueous solvents and is dissolved in the lithium hexafluoro phosphate of the conduct master supporting electrolyte of this nonaqueous solvents. As long as with the electrolyte of nonaqueous solvents as rechargeable nonaqueous electrolytic battery, any nonaqueous solvents can use and be not particularly limited. Normally used example has the solvent mixture of cyclic carbonate and linear carbonate, this cyclic carbonate such as ethylene carbonate or propylene carbonate, this linear carbonate such as methyl carbonate, ethyl carbonate or methyl ethyl carbonate. In addition, gamma-butyrolacton and dimethoxy-ethane etc. can also be mixed into nonaqueous solvents. The concentration of lithium hexafluoro phosphate is not less than ideally 0.5mol/L and is not higher than 2mol/L. Compare with using other lithium salts, use lithium hexafluoro phosphate can provide good battery behavior as the nonaqueous electrolyte of main supporting electrolyte. In addition, except lithium hexafluoro phosphate, can also add other a small amount of lithium salts, for example, LiBF4 or imino group lithium salts.
The total acid content of nonaqueous electrolyte is not less than 50ppm and is not higher than 200ppm. Negative pole can cause the solubilizing reaction of Si when as mentioned above, there was HF in interdischarge interval. In the present invention, by control acid content and negative pole electromotive force, the part surface of negative active core-shell material can be adjusted the charge/discharge reaction is carried out easily.
Outermost surface based on the negative active core-shell material of Si is coated with SiO usually2 Because this SiO2For Li torpescence and non-conductive, so it can disturb charge/discharge reaction on electrochemistry. Therefore, by dissolving SiO2Near layer and the part Si (refers to Si phase or SiO in Si element, the Si alloy at this Six(0＜x＜2) phase) response area of negative active core-shell material can be increased, electrochemical reaction can be promoted. If the acid content of nonaqueous electrolyte is lower than 50 ppm, SiO2Layer can not fully dissolve, and surface of active material is destroyed insufficiently, so just can not be effective. On the other hand, if acid content is higher than 200ppm, then negative active core-shell material Si meeting excessive dissolution is so also improper.
The contained main acid of nonaqueous electrolyte is hydrofluoric acid, but as long as total acid content also can contain other acid within above-mentioned scope. By reducing initial (during production) the contained water content of nonaqueous electrolyte, can reduce the acid content of nonaqueous electrolyte. In addition, also can effectively reduce acid content by the water content that reduces in positive pole, negative pole, barrier film and other battery component.
In addition, contained two [1,2-oxalic acid (2-)-O, O '] borate (after this being called BOB) ions of nonaqueous electrolyte preferably are not higher than 5 % by weight. The BOB ion is a kind of anion with following structural formula, can play neutralization to acid contained in the electrolyte. Therefore, the BOB ion can obviously weaken the active acid in the electrolyte, avoids the precipitation reaction of the Si of the excessive dissolution reaction of Si and dissolving with this.
In the present invention, when the battery discharge final voltage, the negative pole electromotive force is with respect to Li/Li+Be 0.6～1.5V. If discharge finishes being higher than under the electromotive force of this scope, even above-mentioned condition is met the Si dissolving might occur also. When the battery discharge final voltage, the negative pole electromotive force is with respect to Li/Li+Be particularly preferably 0.6～0.9V. As used herein " final discharging voltage " but refer to the minimum discharge voltage of safe-discharge. In the present invention, the scope that final discharging voltage is set is for being not less than 1.5V and not being higher than 3.0V, and preferred scope is 2.0V～2.5V. In addition, even at least in this voltage range, also should be preferably after battery be discharged to the charge/discharge cycle end fully, both existed reversible Li (can play the Li of electrochemical action) also to have irreversible Li (owing to the reason of side reaction etc. does not have the Li of electromotive force, such as the oxide of Li). In the case, if over-discharge occurs, reversible Li can discharge, and therefore can guarantee the safety of battery. For the content of reversible Li, will produce effect on a small quantity, but be not less than with respect to Li/Li ideally+Be in 0～3.0V scope discharge capacity (total discharge capacity) 3% and be not higher than 30%. Exhaust easily when over-discharge if the content of reversible Li is lower than 3%, Li, therefore be difficult to guarantee safety. On the other hand, if content surpasses 30%, the capacity of Li that is used for battery operated voltage range is little, therefore is difficult to obtain high power capacity.
In addition, the anticathode discharge potential is controlled like this, can bring about tangible results to suppressing the Si dissolving, especially when using the oxide of form of film Si particularly.Reason is probably as follows.At first, the oxide of Si has a SiO especially
2Layer.Secondly, little with the response area of the oxide of the Si of form of film, so the per unit response area has than the obvious high capacity of the oxide of particulate Si, therefore, cause side reaction easilier.
In order to make negative discharge stop electromotive force within above-mentioned scope and high capacity is provided, preferably add Li so that suitable negative pole irreversible capacity to be provided.The method that adds Li comprises a kind of method and a kind of method that forms the Li film by methods such as vapor depositions in negative terminal surface of sticking the Li metal forming in negative terminal surface.The amount that joins the Li on surface can take the circumstances into consideration to consider according to the irreversible capacity of negative pole self.
When negative pole of the present invention comprise current-collector that metal forming is made and each side of current-collector with the negative pole mixture layer time, current-collector is desirably Copper Foil or copper alloy foil.Copper alloy foil preferably has 90 weight % or higher copper content.With regard to the intensity and flexibility of improving current-collector, the Copper Foil or the copper alloy foil that contain such as P, Ag or Cr element are effective.
The thickness of current-collector preferably is not less than 6 μ m and is not more than 40 μ m.If being thinner than 6 μ m, current-collector can be difficult to handle.In addition, current-collector also can not have the intensity of requirement, thereby can break or wrinkling because of the electrode mixture layer expands and shrinks.On the other hand, if current-collector is thicker than 40 μ m, then current-collector is big with the volume of battery ratio, and therefore the kind according to battery is unfavorable for capacity.In addition, also can be difficult to processing if current-collector is thick, as be difficult to bending.
Rechargeable nonaqueous electrolytic battery of the present invention comprises above-mentioned negative pole, electrochemically positive pole and the nonaqueous electrolyte of absorption and desorption Li.
Positive pole can be to be used as anodal any electrode in the nonaqueous electrolyte secondary cell, does not have specific restriction.Positive pole can be produced with conventional method.For example, can be in liquid phase the blended anode active material, such as the conductive agent of carbon black with such as the binding agent shape pulping agent of polyvinylidene fluoride, this slurry agent is applied to the cathode collector of making as with Al, it is carried out drying, coiling, can obtain positive pole thus.
Positive electrode active materials can be any material that is used as positive electrode active materials in the nonaqueous electrolyte secondary cell, does not have specific restriction.Yet, preferably contain the transistion metal compound of lithium.The example that contains the transistion metal compound of lithium includes but not limited to LiCoO
2, LiNiO
2, LiMn
2O
4And LiMnO
2Its transition metal also can preferably be used by this compounds that other element replaces.This class example comprises LiCo
1-xMg
xO
2, LiNi
1-yCo
yO
2, LiNi
1-y-zCo
yMn
zO
2, 0＜x＜1,0＜y＜1 wherein, z is an integer.
In order to prevent internal short-circuit between positive pole and negative pole, between two electrodes, provide a barrier film.Barrier material can be any material, as long as this material can make nonaqueous electrolyte rationally pass through, and can make and avoids contact between positive pole and the negative pole.The microporous barrier of manufacturing such as polyethylene, polypropylene is usually used in rechargeable nonaqueous electrolytic battery, and its thickness generally is not less than 10 μ m and is not more than 30 μ m.
The present invention is applicable to the rechargeable nonaqueous electrolytic battery of different shape, as cylindric, flat, coin and prism-shaped etc., the shape of battery is had no particular limits.The present invention is applicable to the battery of various packing forms, comprises such as electrification components such as electrode and electrolyte being packaged in battery in metal battery box or the laminate film box, and the packing forms of battery is not particularly limited.
After this mode by embodiment and comparative example is described in more detail the present invention.Yet following examples only are the explanation to optimal way of the present invention, should not be construed as any limitation of the invention.
Embodiment
Embodiment 1
In the present embodiment, produce negative pole and cylindrical battery in the following manner, and its cycle life and discharge capacity are estimated.
(1) production of negative pole
Negative pole (i)
The graphite crucible and the electron gun that will wherein be placed with Si metal (purity 99.999%, Furuuchi Chemical Corporation, ingot) are placed in the vapor deposition apparatus.To from roller, be sent to vapor deposition apparatus as the electrolytic copper foil (thickness 20 μ m can be from Furukawa Circuit Foil Co., and Ltd. obtains) of current-collector sheet material, so that make Si be deposited on the surface of Copper Foil with constant speed (5cm/min).It is 150mA for-8kV, electric current that sedimentary condition is set at accelerating voltage.Vacuum degree when carrying out following vapor deposition in the device is set at 3x10
-5Torr, unless otherwise prescribed.
After finishing the deposition of current-collector sheet material one side, carry out the vapor deposition of opposite side (not depositing side) in the same way, so that all form the active material film in every side.These films are through X-ray diffraction analysis, have one to be considered to the broad peak that amorphous Si causes when finding 2 θ=15～40 °.This result shows that active material Si is unbodied.The gross thickness of negative pole is about 30～36 μ m, and the film thickness of each side of current-collector is about 5 μ m.
Negative electrode plate is sent to vapor deposition apparatus once more, from metal target Li (can obtain) Li is deposited on the both sides of negative pole by the resistance heating method from Honjo Chemical Corporation.Can regulate the amount of deposition by changing the transporting velocity that negative electrode plate is sent to vapor deposition apparatus from roller.So just the Li of specified amount can be joined the surface of negative electrode plate.For example, in the described in the back battery 1 employed negative pole (i), the transporting velocity of negative electrode plate is 5cm/min, and the thickness of the Li of deposition is about 5 μ m.By changing the addition of Li, the irreversible capacity that can replenish negative pole is controlled with anticathode electromotive force when the discharge off.Similarly, negative pole described below (ii), negative pole (iii) (iv) also is supplemented with Li with negative pole.
After forming the Si film, 110 ℃ of following vacuumizes 15 hours, be room temperature preservation in-60 ℃ or the lower dry atmosphere at dew point then with negative pole (i).In addition, after replenishing Li, with negative pole (i) also dew point for room temperature preservation in-60 ℃ or the lower dry atmosphere with remove and control electrode in water content.
Negative pole (ii)
To Ti metal (purity 99.9%, 100～150 μ m, can be from Japan Pure ChemicalCo., Ltd. obtain) and Si metal (purity 99.99%, 100～150 μ m, can be from KantoChemical Co., Inc. obtains) weigh, carry out blend with the weight ratio of Ti:Si=9.2:90.8 then.
This mixture of powders of 3.5kg is put in the vibration milling (FV-20 can be from Chuo KakohkiIndustries, and Ltd. obtains), and (diameter 2cm) puts into wherein with the stainless steel metal ball, makes Metal Ball account for 70% of mill internal volume.After container was found time, injecting Ar (purity 99.999% can obtain from Nippon Sanso Corporation) to it provided 1 atmospheric pressure.The frequency setting of mill is 720Hz.With this understanding, carry out 80 hours Mechanical Method alloying.
The Ti-Si alloy that will obtain from aforesaid operations collects, and measures its particle size distribution.Found that its wide particle diameter with 0.5 μ m～80 μ m distributes.With sieve (10 μ m are following) this Ti-Si alloy is sieved, obtaining maximum particle diameter is that 8 μ m, average grain diameter are the alloy material (hereinafter referred to as alloy " a ") of 5 μ m.
With the impurity level of this alloy of ICP spectrophotometer " a ", find that Fe content is 500ppm, Ni is 30ppm, Cr is 60ppm.The content of other transition metal all is lower than the lower limit of measurement.The total content of these elements is 590ppm.
Alloy " a " is through X-ray diffraction analysis, and the result shows that this alloy is the crystallite shape.Simultaneously, calculate the size of crystal grain (crystallite) by the Schuler equation from the half width of highest peak, the discovery grain size is 18nm.Further, the observation from the peak of X-ray diffraction pattern and by transmission electron microscope(TEM) infers that alloy " a " has Si single-phase (A phase) and TiSi
2Phase (B phase).Suppose that alloy " a " has only this two phases, the single-phase and TiSi to Si
2The ratio of phase is calculated, and finds Si:TiSi
2=80:20 (weight ratio).
With transmission electron microscope(TEM) (TEM) alloy " a " is observed.Find that alloy " a " has an amorphous domain, it is single-phase and comprise that size is about the TiSi of the crystal grain of 15～20nm (crystallite) to comprise that size is about the Si of the crystal grain of 10nm (crystallite)
2Phase.
Alloy " a " carries out blend with graphite with the weight ratio of 25:75.This mixture with 100 weight portions mixes with the acetylene black of 2 weight portions and the polyacrylic acid of 8 weight portions again, acetylene black (trade (brand) name DENKA BLACK wherein, can obtain from Denki Kagaku Kogyo K.K.) as conductive agent, (molecular weight is about 150000 to polyacrylic acid, can be from Wako PureChemical Industries, Ltd. obtains) as bonding agent.While adding pure water this mixture is fully kneaded, obtained the agent of negative pole mixture slurry.The graphite that uses is the flake graphite (KS-44) of 20 μ m as average grain diameter, can obtain from Timcal Ltd..
This negative pole mixture is starched the both sides that agent is applied to current-collector, it is carried out drying, coiling, wherein said current-collector is made by the thick electrolytic copper foil of 10 μ m (can be from Furukawa Circuit FoilCo., Ltd. obtains).The result has obtained negative electrode plate, this sheet material comprise current-collector and each face thereof with the negative pole mixture layer.The density of negative pole mixture layer is 1.3g/cm
3, the porosity of negative pole mixture layer is 40%.Negative electrode plate 190 ℃ of following vacuumizes 12 hours, is preserved in-60 ℃ or the lower dry atmosphere at dew point then.
Next, the Li metal forming (thickness is 50 μ m, can obtain from HonjoChemical Corporation) of specified size is attached to the surface of negative electrode plate, replenishes irreversible capacity with an amount of Li.For example, described afterwards battery 7 employed negative poles (ii) in, the Li that is pasted has covered about 1/4 negative pole zone.
After replenishing Li, negative electrode plate is similarly preserved in-60 ℃ or the lower dry atmosphere at dew point, with remove and control electrode in water content.
Negative pole (iii)
Use SiO (maximum particle diameter 45 μ m can obtain from Sumitomo Titanium Corporation for purity 99.9%, average grain diameter 20 μ m) as negative active core-shell material.With SiO and graphite and acetylene black with SiO: the ratio of graphite: acetylene black=45:52:3 (weight ratio) is mixed, with the low electric conductivity of compensation SiO.The polyvinylidene fluoride (can be from Kureha Chemical Industry Co., Ltd. obtains) of this mixture and 5 weight portions is mixed, fully knead with the N-N-methyl-2-2-pyrrolidone N-then, obtain the agent of negative pole mixture slurry.The graphite that uses is the graphite (KS4) of 3 μ m as average grain diameter, can obtain from Timcal Ltd..
With with negative pole (ii) in identical method, this negative pole mixture slurry agent is applied to the both sides of current-collector, it is carried out drying, coiling, and wherein said current-collector is made by the thick electrolytic copper foil of 10 μ m (can be from Furukawa Circuit Foil Co., Ltd. obtains).The result has obtained negative electrode plate, this sheet material comprise current-collector and every side thereof with the negative pole mixture layer.The density of negative pole mixture layer is 1.0g/cm
3, the porosity of negative pole mixture layer is 55%.
Negative electrode plate 80 ℃ of following vacuumizes 24 hours, is preserved in-60 ℃ or the lower dry atmosphere at dew point then.
With with negative pole (ii) in identical method, the Li metal forming (thickness is 50 μ m, can obtain from Honjo Chemical Corporation) of specified size is attached on this negative pole, to replenish an amount of Li.For example, described afterwards battery 13 employed negative poles (iii) in, the Li that is pasted has covered about 1/2 negative pole zone.
The negative electrode plate that replenished Li is room temperature preservation in-60 ℃ or the lower dry atmosphere at dew point, with remove and control electrode in water content.
Negative pole (iv)
With with negative pole (i) in identical method, will comprise that the current-collector sheet material of electrolytic copper foil is sent in the vapor deposition apparatus, this deposition apparatus is furnished with graphite crucible and the electron gun that wherein is placed with the Si metal, Si is deposited on the surface of sheet material.Yet in the present embodiment, the current-collector sheet material surface supply purity in deposition apparatus is 99.7% oxygen (deriving from Nippon SansoCorporation).Flow velocity with 80sccm provides oxygen by mass flow controller and gas line from oxygen cylinder, gas line is furnished with nozzle at one that enters vapor deposition apparatus.It is that 150mA, vacuum degree are 1.5x10 for-8kV, electric current that sedimentary condition is set at accelerating voltage
-3Torr.
Like this, the active material film is formed on each side of current-collector sheet material.The gross thickness of negative pole is that the gross thickness of the film on current-collector sheet material and the both sides thereof is about 42～45 μ m, and every side film thickness is about 10～12 μ m.Oxygen content in the film is measured by firing method, is found to be SiO
0.4In addition, film also carries out X-ray diffraction analysis.The result observes one and is considered to the peak crystallization that Cu causes in the current-collector sheet material, and film has a broad peak during in 2 θ=15～40 °.This result shows that active material is unbodied.
The negative electrode plate of producing like this is sent in the vapor deposition apparatus once more, Li is deposited on the both sides of negative pole by metal target Li is heated.For example, when the transporting velocity of negative pole was made as 3cm/min, the Li thickness that is deposited on each side was about 8 μ m.
(2) Zheng Ji preparation
With Li
2CO
3And CoCO
3With predetermined mol ratio blend, this mixture adds the LiCoO of thermal synthesis as positive electrode active materials under 950 ℃
2This positive electrode active materials sieves 45 μ m or following.This positive electrode active materials of 100 weight portions is mixed as the polyvinylidene fluoride of bonding agent and an amount of N-N-methyl-2-2-pyrrolidone N-as decentralized medium with acetylene black, 4 weight portions of 5 weight portions as conductive agent, and this mixture is fully kneaded forms the agent of cathode mix slurry.
This cathode mix is starched the both sides that agent is applied to current-collector, it is carried out drying, coiling, wherein said current-collector comprises the thick aluminium foil of 15 μ m (can obtain from Showa Denko K.K.).The result has obtained anodal sheet material, this sheet material comprise current-collector and every side thereof with positive-electrode mixture layer.
Is-60 ℃ or room temperature preservation in the dry atmosphere under the low temperature more with this positive pole sheet material at dew point, before the battery assembling that is close to the following stated, 80 ℃ of following vacuumizes electrode is dewatered.
(3) assembling of cylindrical battery
Anodal sheet material and negative electrode plate are cut into predetermined shape, to produce cylindric lithium rechargeable battery as shown in Figure 1.
One end of aluminium positive wire 14 links to each other with the current-collector of positive pole 11.One end of nickel negative wire 15 links to each other with the current-collector of negative pole 12.Anodal 11, the negative pole 12 and barrier film 13 that these two electrodes insulate twined spirally make electrode body.The thick microporous barrier of 20 μ m that barrier film 13 is made for polyvinyl resin, all wideer than positive pole and negative pole.The outside of electrode body is covered in the end of the barrier film that twines side end part fully.This electrode body in the dry atmosphere of-60 ℃ (dew points) 60 ℃ of following vacuumizes 10 hours, to evaporate the water content in the electrode body.Barrier film 13 and other battery component be bone dry in advance, so that reduce to the water that may comprise in the battery minimum.
Last dead ring 16 and following dead ring 17 be separately fixed at the top of electrode body with below, and then electrode body is placed in the battery case 18.Subsequently, nonaqueous electrolyte is injected into impregnated electrode body in the battery case.With the other end of positive wire 14 with and logical conductive components 21 welding of positive terminal 20 electricity, conductive component 21 is fixed on the sealing plate 19 that electric insulation resin makes.The inboard welding of the other end and battery case 18 bases with negative wire 15.At last, the opening part of battery case 18 seals with sealing plate 19.So just finished a cylindric lithium rechargeable battery.The diameter of this battery is 18mm, highly is 65mm that design capacity is 2000mAh.
Further, electrode 22 in the present embodiment, as the reference electrode of measuring the negative pole electromotive force, are installed in the central authorities of electrode body.Electrode 22 comprises Ni wire 23 (diameter of silk is 0.5mm), and outside wiry is wrapped up by Li metal forming 24 (thickness is 50 μ m).Nickel wire 23 passes conductive component 21 and positive terminal 20, by dielectric film 25 and conductive component 21 electric insulations that cover the nickel wire surface.Positive terminal 20 is by liner 26 and nickel wire 23 insulation.
Is in the non-aqueous solvent mixture of 1:1 with lithium hexafluoro phosphate with the volume ratio that the concentration of 1mol/L is dissolved in ethylene carbonate and diethyl carbonate, the nonaqueous electrolyte that preparation is used.This nonaqueous electrolyte is carried out quantitatively and its acid content and sour component are measured in qualitative analysis.Found that its main component is HF, total content is 18ppm.
Use wherein add negative pole (i) that specified amount Li is arranged, negative pole (ii), negative pole (iii) with negative pole (iv), correspondingly make battery 1～6, battery 7～12, battery 13～18 and battery " a "～" f ".Table 1 has provided the Li content in the negative pole that joins respective battery.
(4) cell evaluation
＜i〉discharge capacity
In temperature was set at 20 ℃ constant temperature oven, each battery in these batteries was all with 400mA (0.2C; 1C is speed per hour electric current (hour-rate current)) constant current charge to cell voltage reach 4.05V, under the constant voltage of 4.05V, charge to current value then and drop to 20mA (0.01C).After this, each battery all is discharged to cell voltage with the constant current of 0.2C and drops to 2.0V.Table 1 has provided discharge capacity.
＜ii〉the discharge storage test
After recording discharge capacity, battery carries out following operation in temperature is set at 20 ℃ constant temperature oven.At first, every battery all reaches 4.05V with constant current charge to the cell voltage of 0.2C, charges to current value then under the constant voltage of 4.05V and reaches 0.01C.Then, battery is discharged to cell voltage with the constant current of 0.2C and drops to 2.0V (final discharging voltage).After 1 hour, record the electromotive force of negative pole with respect to electrode 22.This electromotive force is expressed as " memory period negative pole electromotive force " in following each table.Then, every battery is all stored 3 days in 85 ℃ constant temperature oven.After the storage, with above-described the same terms under it is charged and discharges, to obtain discharge capacity.Like this, the capacity restoration rate after can obtaining storing ((discharge capacity after the storage) * 100/ (capacity before storing)) (%).
＜iii〉cycle life
After recording discharge capacity, in temperature is set at 20 ℃ constant temperature oven, battery is carried out following charging and discharge operation repeatedly.At first, every battery all reaches 4.05V with constant current charge to the cell voltage of 1C, charges to current value then under the constant voltage of 4.05V and reaches 0.05C.Then, battery is discharged to cell voltage with the constant current of 1C and drops to 2.5V.Carry out these operations repeatedly.The discharge capacity of the 100th circulation time is defined as capability retention (%) with respect to the percentage of the discharge capacity of the 2nd circulation time.Table 1 has provided the result.Capability retention is the closer to 100%, and cycle life is good more.
[table 1]
| Negative pole | The Li addition | Discharge capacity (mAh) | (V is with respect to Li/Li for storage period negative pole electromotive force +) | Electrolytical acid content (ppm) | Recovery rate (%) | Capability retention (%) after 100 circulations | |
| Battery 1 | Negative pole (i) | Deposit thickness 6 μ m | 1320 | 0.38 | 64 | 96 | 92 |
| Battery 2 | Negative pole (i) | Deposit thickness 4 μ m | 1780 | 0.59 | 63 | 95 | 91 |
| Battery 3 | Negative pole (i) | Deposit thickness 3 μ m | 1930 | 0.90 | 68 | 92 | 91 |
| Battery 4 | Negative pole (i) | Deposit thickness 2 μ m | 2010 | 1.18 | 71 | 89 | 86 |
| Battery 5 | Negative pole (i) | Deposit thickness 1 μ m | 2060 | 1.48 | 70 | 85 | 82 |
| Battery 6 | Negative pole (i) | Do not deposit | 2100 | 1.76 | 71 | 58 | 43 |
| Battery 7 | Negative pole (ii) | Paste 1/4 zone | 1290 | 0.40 | 85 | 97 | 95 |
| Battery 8 | Negative pole (ii) | Paste 1/6 zone | 1760 | 0.61 | 87 | 94 | 93 |
| Battery 9 | Negative pole (ii) | Paste 1/8 zone | 1900 | 0.88 | 90 | 93 | 92 |
| Battery 10 | Negative pole (ii) | Paste 1/10 zone | 1970 | 1.13 | 83 | 90 | 88 |
| Battery 11 | Negative pole (ii) | Paste 1/15 zone | 2030 | 1.50 | 91 | 83 | 78 |
| Battery 12 | Negative pole (ii) | Do not paste | 2060 | 1.69 | 89 | 63 | 33 |
| Battery 13 | Negative pole (iii) | Paste 1/2 zone | 1280 | 0.39 | 78 | 97 | 95 |
| Battery 14 | Negative pole (iii) | Paste 1/3 zone | 1750 | 0.61 | 79 | 94 | 94 |
| Battery 15 | Negative pole (iii) | Paste 1/4 zone | 1930 | 0.92 | 76 | 92 | 94 |
| Battery 16 | Negative pole (iii) | Paste 1/6 zone | 1990 | 1.08 | 75 | 89 | 89 |
| Battery 17 | Negative pole (iii) | Paste 1/8 zone | 1860 | 1.49 | 81 | 84 | 85 |
| Battery 18 | Negative pole (iii) | Do not paste | 1100 | 1.56 | 80 | 65 | 64 |
| Battery 19 | Graphite | Do not add | 1250 | 0.31 | 90 | 99 | 95 |
| Battery a | Negative pole (iv) | Deposit thickness 15 μ m | 1450 | 0.41 | 65 | 98 | 98 |
| Battery b | Negative pole (iv) | Deposit thickness 12 μ m | 1860 | 0.73 | 70 | 99 | 98 |
| Battery c | Negative pole (iv) | Deposit thickness 10 μ m | 1980 | 0.98 | 71 | 99 | 98 |
| Battery d | Negative pole (iv) | Deposit thickness 8 μ m | 2050 | 1.10 | 73 | 99 | 99 |
| Battery e | Negative pole (iv) | Deposit thickness 4 μ m | 1860 | 1.45 | 74 | 98 | 87 |
| Battery f | Negative pole (iv) | Do not deposit | 1330 | 1.83 | 72 | 64 | 60 |
The manufacture method of battery 19 and battery 6 identical relatively in the table 1 is except wherein having used the negative pole for preparing by the following method.With the graphite of 100 weight portions and the mixture and the water mixing pulping agent of the bonding agent (polyacrylic acid) of 6 weight portions, should starch agent and be applied on the current-collector, carry out drying and coiling, make negative pole.
As shown in table 1, all use the battery of present embodiment negative pole all to compare than battery 19 and show higher capacity.Yet battery 1, battery 7, battery 13, battery " a " and battery " f " only show high slightly capacity than battery 19 frequently, and this shows that they do not make full use of the characteristic of negative pole of the present invention.Further, battery 18 shows low slightly capacity than battery 19 frequently because anodal lithium since the irreversible capacity of negative pole be consumed.To battery " f " also is same situation.In addition, for the storage characteristics after the discharge, observe battery 6, battery 12, battery 18 and battery " f " and have low especially recovery rate.To finding behind these battery scrutinies, nonaqueous electrolyte contains the Si that is dissolved in a large number wherein and has formed the coated film that contains Si on the surface of negative pole.In addition, to finding after other battery inspection, negative pole electromotive force (storage period negative pole electromotive force in the table 1) was low more when discharge finished, the Si that is dissolved in nonaqueous electrolyte more less and the amount of dissolving be lower than the lower limit of measurement, particularly when the negative pole electromotive force with respect to Li/Li
+For 0.9V or when lower.
In these batteries, the acid content of nonaqueous electrolyte is 63～91ppm.In the battery 1～6 that uses negative pole (i), acid content is minimum, is 63～71ppm.In using negative pole battery 7～12 (ii), acid content is higher, is 83～91ppm.Reason is probably as follows.Negative pole (ii) in, use polyacrylic acid as bonding agent, polyacrylic acid has formed hydrate on electrode.Partially hydrated thing can not evaporate between 190 ℃ of following dry periods, contained water and the LiPF in the nonaqueous electrolyte in the hydrate
6Formation hydrofluoric acid reacts.Negative pole (iii) in, acid content is 75～81ppm.Table 1 has provided these values.
In addition, for the capability retention after 100 circulations, battery 6, battery 12 and battery 18 are not as other battery.This may be because of the increase along with charge/discharge cycle, and discharge repeatedly can cause taking place the solubilizing reaction of Si and the precipitation reaction of dissolving Si, has therefore hindered the charge/discharge reaction.
Embodiment 2
In the present embodiment, the acid content of research nonaqueous electrolyte.Use the negative pole of battery 9, produce cylindric lithium rechargeable battery in the mode identical with embodiment 1.More particularly, as shown in table 2ly produce battery 20～25 by changing (ii) drying condition of negative pole (190 ℃ following vacuumize 12 hours).Table 2 has provided the electrolyte acid content that records and the characteristic of battery.
[table 2]
| Negative pole | Drying condition | Electrolytical acid content (ppm) | Discharge capacity (mAh) | (V is with respect to Li/Li for storage period negative pole electromotive force +) | Recovery rate (%) | Capability retention (%) after 100 | |
| Battery | |||||||
| 20 | Negative pole (ii) | Dew point is to preserve 24 hours at 20 ℃ in-60 ℃ or the lower dry atmosphere | 231 | 1820 | 0.85 | 42 | 31 |
| |
Negative pole (ii) | Dry 10 hours of 60 ℃ of hot-airs | 189 | 1880 | 0.89 | 70 | 66 |
| |
Negative pole (ii) | Dry 10 hours of 190 ℃ of hot-airs | 145 | 1890 | 0.88 | 75 | 78 |
| |
Negative pole (ii) | 60 ℃ of vacuumize 10 hours | 102 | 1910 | 0.91 | 82 | 81 |
| |
Negative pole (ii) | 190 ℃ of |
56 | 1910 | 0.9 | 80 | 80 |
| |
Negative pole (ii) | 190 ℃ of vacuumize 48 hours | 44 | 1820 | 0.88 | 81 | 61 |
Clearly show as table 2, stop discharge potential with respect to Li/Li even work as negative pole
+For 1.5V or when lower, if the acid content of nonaqueous electrolyte greater than 200ppm, recovery rate and the capability retention behind the storage is all low under the discharge condition, as the situation of battery 20.This may be because near a large amount of hydrofluoric acid the negative pole are tending towards making the reaction of reaction equation (1) to carry out to the right, has promoted the solubilizing reaction of Si and relevant therewith film to form reaction thus.
The negative active core-shell material surface of battery 25 has recorded through X ray Photoelectric Spectrometer (XPS) and has ascribed SiO to
2Binding energy.This result shows, when acid content after a little while, the SiO of outermost surface
2Can not be dissolved.Further, because the conversion zone of negative active core-shell material is little, so electrochemical reaction can not be carried out smoothly.May be owing to this reason, the cycle characteristics of battery 25 (that is: electrochemical reaction repeats the characteristic that the back obtains) descends.
Embodiment 3
In the present embodiment, the influence of research negative pole impurities.Identical in (ii) of the preparation method of employed negative active core-shell material and negative pole in the present embodiment, except employed ball in the Mechanical Method alloying is made with S45C steel (Fe-0.45%C steel), rather than use stainless steel, will increase to the operating time 80 hours, 100 hours or 150 hours.The wide particle diameter that the alloy that obtains has 0.5 μ m～80 μ m distributes.With sieve (10 μ m are following) they are sieved, obtaining maximum particle diameter is that 8 μ m, average grain diameter are the alloy material of 5 μ m.The alloy powder that obtains like this is called alloy " b ", alloy " c " and alloy " d ".
With the impurity of these alloys of ICP spectrophotometer " b "～" d ", find that the transition metal except that Fe is lower than the lower limit of measurement.Fe content is 680ppm in alloy " b ", is 980ppm in alloy " c ", is 1320ppm in alloy " d ".
Alloy " b "～" d " is through X-ray diffraction analysis, and their XRD distribution is similar with alloy " a ".All these alloys all are the crystallite shape, and to calculate crystal grain (crystallite) size by the Schuler equation from the half-breadth of highest peak be 11～18nm.The particle of inferring alloy " b "～" d " has Si single-phase (A phase) and TiSi
2Phase (B phase).In addition, with transmission electron microscope(TEM) (TEM) these alloys " b "～" d " observed, find that they have an amorphous domain, to comprise that size is about the Si of the crystal grain of 10nm (crystallite) single-phase and comprise that size is about the TiSi of the crystal grain of 10～20nm (crystallite)
2Phase.
Use these alloys,, form the negative pole mixture layer, and the Li paper tinsel is attached to the surface of negative pole mixture layer, to cover 1/8 negative pole zone in the every side of current-collector sheet material in the mode (ii) identical with negative pole.
Use these negative poles, produce cylindric lithium rechargeable battery 26～28, estimate in mode same as the previously described embodiments in the mode identical with battery 9.The acid content that table 3 has provided the result and recorded from these batteries.
[table 3]
| Negative active core-shell material | Impurity content (ppm) | Discharge capacity (mAh) | (V is with respect to Li/Li for storage period negative pole electromotive force +) | Electrolytical acid content (ppm) | Recovery rate (%) | Capability retention (%) after 100 | |
| Battery | |||||||
| 26 | Alloy b | 680 | 1890 | 0.88 | 81 | 91 | 90 |
| Battery 27 | Alloy c | 980 | 1870 | 0.85 | 83 | 73 | 83 |
| Battery 28 | Alloy d | 1320 | 1870 | 0.91 | 85 | 32 | 55 |
These results show that when impurity content had surpassed 1000ppm, recovery rate after having stored under the discharge condition and capability retention be step-down all.
Embodiment 4
Battery 29,30 and 31 production method be identical with battery 3,9 and 15 respectively, contains two [1,2-oxalic acid (2-)-O, O '] lithium borate (after this being called LiBOB) of 3 weight % except employed nonaqueous electrolyte.In addition, battery 32,33 and 34 contains the LiBOB of 5 weight % also with same method production except employed nonaqueous electrolyte.Further, battery 35,36 and 37 contains the LiBOB of 8 weight % also with same method production except employed nonaqueous electrolyte.These batteries are estimated in mode same as the previously described embodiments.The acid content that table 4 has provided the result and recorded from these batteries.
[table 4]
| Negative pole | The addition of LiBO (weight %) | Discharge capacity (mAh) | (V is with respect to Li/Li for storage period negative pole electromotive force +) | Electrolytical acid content (ppm) | Recovery rate (%) | Capability retention (%) after 100 circulations | |
| Battery 29 | Negative pole (i) | 3 | 1950 | 0.85 | 75 | 94 | 95 |
| Battery 30 | Negative pole (ii) | 3 | 1930 | 0.86 | 77 | 96 | 96 |
| Battery 31 | Negative pole (iii) | 3 | 1940 | 0.89 | 79 | 95 | 97 |
| Battery 32 | Negative pole (i) | 5 | 1930 | 0.91 | 80 | 95 | 91 |
| Battery 33 | Negative pole (ii) | 5 | 1910 | 0.94 | 79 | 97 | 92 |
| Battery 34 | Negative pole (iii) | 5 | 1910 | 0.92 | 80 | 96 | 94 |
| Battery 35 | Negative pole (i) | 8 | 1860 | 0.90 | 83 | 94 | 85 |
| Battery 36 | Negative pole (ii) | 8 | 1830 | 0.89 | 83 | 95 | 81 |
| Battery 37 | Negative pole (iii) | 8 | 1810 | 0.88 | 85 | 95 | 83 |
These results show, add LiBOB that concentration is not higher than 5 weight % in the nonaqueous electrolyte and can improve the recovery rate behind the storage and the capability retention after the charge/discharge cycle under the discharge condition.This may be because LiBOB has captured hydrofluoric acid, has suppressed its reaction, has suppressed the dissolving of Si thus, and battery behavior is improved.When the addition of LiBOB surpasses 5 weight %, the capability retention after the charge/discharge cycle is tending towards descending.This may be because excessive LiBOB has improved the viscosity of nonaqueous electrolyte, has hindered moving of lithium ion thus.These results show that the upper limit of LiBOB amount is preferably 5 weight %.
Can provide the rechargeable nonaqueous electrolytic battery that not only has high power capacity but also have good charge/discharge cycle characteristics according to the negative pole of rechargeable nonaqueous electrolytic battery of the present invention.The present invention can be applicable to various rechargeable nonaqueous electrolytic batteries.For example, the present invention not only can be applicable to as the cylindrical battery among the embodiment, can also be applied to the battery, electrode body structure of coin, prism-shaped and the flat battery as curl shape or stratiform.Rechargeable nonaqueous electrolytic battery according to the present invention can be used as the main power source of device for mobile communication, portable electric appts etc.
Although the present invention is described with the form of present preferred embodiment, should understand that this class disclosure can not be interpreted as certain qualification.After reading above-mentioned disclosure, various variants and modification are conspicuous beyond doubt for the technical staff in field related to the present invention.Therefore, appending claims should be considered as having covered all variants and the change that falls into spirit of the present invention and scope.
Claims (6)
1. rechargeable nonaqueous electrolytic battery, it comprises: the positive pole of absorption and desorption Li electrochemically, negative pole and nonaqueous electrolyte,
Wherein said negative pole comprises the negative active core-shell material that contains Si at least,
Described nonaqueous electrolyte comprises the lithium hexafluoro phosphate as main supporting electrolyte, and have the acid content that is not less than 50ppm and is not higher than 200ppm and
Described negative pole has the electromotive force that is not less than 0.6V and is not higher than 1.5V with respect to the Li electrode under the final discharging voltage of described battery.
2. according to the rechargeable nonaqueous electrolytic battery of claim 1, wherein said negative active core-shell material is Si, Si alloy or Si compound.
3. according to the rechargeable nonaqueous electrolytic battery of claim 2, wherein said Si compound is the oxide of representing with SiOx, wherein 0＜x＜2.
4. according to the rechargeable nonaqueous electrolytic battery of claim 2, wherein said negative pole comprises anode collector and the negative active core-shell material film that is deposited on the described anode collector.
5. according to the rechargeable nonaqueous electrolytic battery of claim 2, the total content of Fe, Ni, Co, Cu and Cr is 1000ppm or lower in the wherein said Si alloy.
6. according to the rechargeable nonaqueous electrolytic battery of claim 1, wherein said nonaqueous electrolyte contains two [1,2-oxalic acid (2-)-O, the O '] borate ions that are not higher than 5 weight %.
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| JP5448295B2 (en) * | 2006-12-19 | 2014-03-19 | 三星エスディアイ株式会社 | Lithium secondary battery and manufacturing method thereof |
| JP5448002B2 (en) * | 2009-08-04 | 2014-03-19 | トヨタ自動車株式会社 | Non-aqueous electrolyte type lithium ion secondary battery |
| US8911906B2 (en) | 2009-08-04 | 2014-12-16 | Toyota Jidosha Kabushiki Kaisha | Non-aqueous electrolyte type lithium ion secondary cell |
| JP5727352B2 (en) * | 2011-11-15 | 2015-06-03 | 信越化学工業株式会社 | Nonaqueous electrolyte secondary battery |
| JP5621868B2 (en) | 2012-03-27 | 2014-11-12 | Tdk株式会社 | Lithium ion secondary battery |
| WO2024000366A1 (en) * | 2022-06-30 | 2024-01-04 | 宁德时代新能源科技股份有限公司 | Battery cell, battery, and electric device |
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