CN105870433B - Negative-electrode active material for secondary battery and the secondary cell for using the negative electrode active material - Google Patents
Negative-electrode active material for secondary battery and the secondary cell for using the negative electrode active material Download PDFInfo
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Abstract
The anode active material for lithium secondary battery with low uncertainty and being not likely to produce electrical isolation of volume when the present invention provides a kind of charge and discharge.The present invention provides a kind of improved negative-electrode active material for secondary battery of expansion rate, the negative-electrode active material for secondary battery is made of following formula, expansion rate after 50 circulations is 70~150%, the decrystallized degree of alloy endobasal-body shape has 25% or more range, has Si:60~70%, Ti:9~14%, Fe:9~14%, Al: greater than 1% and the range less than 20% in terms of atom % (at%).SixTiyFezAlu (wherein, x, y, z, u in terms of atom %, x:1- (y+z+u), y:0.09~0.14, z:0.09~0.14, u: greater than 0.01 and less than 0.2).
Description
Technical field
The present invention relates to negative-electrode active material for secondary battery and it is utilized the two of the negative-electrode active material for secondary battery
Primary cell.
Background technique
In the past, use lithium metal as the negative electrode active material of lithium battery, but when using lithium metal, it may occur that because of shape
At battery short circuit caused by dendrite (Dendrite), to there is the risk of explosion, therefore replaced mostly using carbon system substance
Lithium metal is as negative electrode active material.
As above-mentioned active carbon material, there are system of crystallization carbon as graphite and artificial graphite and soft carbon (Soft
) and amorphous carbon as hard carbon (Hard Carbon) Carbon.Although existing and filling however, above-mentioned amorphous carbon capacity is big
The big problem of irreversibility in discharge process.As system of crystallization carbon, graphite is typically used, theoretical limit capacity is
372mAh/g, capacity is high and is used as negative electrode active material.
However, even if such graphite, active carbon material it may be said that theoretical capacity is slightly higher, are also only 380mAh/g
Left and right, there are problems that not being available above-mentioned cathode when Future Development high-capacity lithium battery.
In order to improve such problems, the substance currently actively studied is the negative of metal system or intermetallic compound system
Pole active material.For example, having studied the lithium with the metals such as aluminium, germanium, silicon, tin, zinc, lead or semimetal as negative electrode active material
Battery.Such material has high-energy density while for high capacity, with the negative electrode active material that carbon-based material is utilized
More lithium ions are released compared to that can occlude, the battery with high capacity and high-energy density can be manufactured.For example, as it is known that
Pure silicon has the high theoretical capacity of 4017mAh/g.
However, by it compared with carbon-based material when, cycle characteristics decreases, still to functionization constitute hinder, this is
Due to the above-mentioned silicon etc. for being used as negative electrode active material is directly used as lithium occlusion and release substance when can generate following phenomenon:
Lead to due to the variation of volume that the electric conductivity between active material reduces or negative electrode active material is from negative in charge and discharge process
Electrode current collector removing.That is, the above-mentioned silicon etc. contained in negative electrode active material occludes lithium because of charging, volume expansion to about 300~
400% degree, when electric discharge, if releasing lithium, inanimate matter particle is shunk.
If such charge and discharge cycles are repeated, sometimes due to the crackle of negative electrode active material and generate it is electric absolutely
Edge, service life are sharply reduced, therefore there are problems when being used for lithium battery.In addition, having been carried out as follows to improve such problems
Research: nanoscale particle is used as silicon particle or makes silicon that there is with porosity the buffering effect to volume change.
KR published patent the 2004-0063802nd be related to anode active material for lithium secondary battery, its manufacturing method and
Lithium secondary battery, using making other metals such as silicon and nickel form the method for flowing out the metal after alloy, in addition, South Korea discloses specially
Benefit the 2004-0082876th is related to the manufacturing method of porosity silicon and nano silicone particle and in negative electrode for lithium secondary battery
Application in material discloses and mixes the silicon precursors such as the alkali or alkaline earth metal of pulverulence and silica and carry out heat
The technology flowed out is allowed to acid after processing.
Above-mentioned patent etc. may improve initial capacity sustainment rate using the buffering effect as brought by cellular structure, but
Since the porosity silicon particle of conductibility difference is used only, so if particle is not nano-scale, when manufacturing electrode between particle
Conductivity can reduce, there are problems that initial efficiency, capacity maintenance characteristics reduce.
Patent document
Patent document 1: KR published patent the 2004-0063802nd
Patent document 2: KR published patent the 2004-0082876th
Summary of the invention
Therefore, the present invention is to propose to solve the above-mentioned problems, volume when the purpose is to provide a kind of charge and discharge
Anode active material for lithium secondary battery that is with low uncertainty and being not likely to produce electrical isolation.
In addition, the lithium secondary battery excellent it is a further object of the present invention to provide a kind of initial efficiency and capacity maintenance characteristics
Use negative electrode active material.
Decrystallized degree is considered when designing battery and is optimized negative in addition, it is yet another object of the invention to provide a kind of
Pole active material.
To achieve the goals above, the embodiment of the present invention is characterized in that providing a kind of secondary battery cathode active matter
Matter, as the alloy being made of following chemical formula, the decrystallized degree in alloy endobasal-body shape fine crystal region is 25% or more.
(wherein, x, y, z, u are in terms of atom %, x:1- (y+z+u), y:0.09~0.14, z:0.09 by SixTiyFezAlu
~0.14, u: greater than 0.01 and less than 0.2)
The range that expansion rate after above-mentioned negative-electrode active material for secondary battery preferably 50 times circulations is 70~150%.
In addition, in terms of atom % (at%), Al preferably has 5~19% in above-mentioned negative-electrode active material for secondary battery
Range.
In addition, in terms of atom % (at%), Al preferably has 10~19% in above-mentioned negative-electrode active material for secondary battery
Range.
In addition, in terms of atom % (at%), Ti and Fe are preferably respectively provided in above-mentioned negative-electrode active material for secondary battery
9~12.5% range.
In addition, the ratio of Ti and Fe preferably have the range of 2:1~1:2 in above-mentioned negative-electrode active material for secondary battery.
In addition, the ratio of Ti and Fe preferably have the range of 1:1 in above-mentioned negative-electrode active material for secondary battery.
In addition, the discharge capacity after above-mentioned negative-electrode active material for secondary battery preferably 50 times circulations is discharged relative to initial stage
Capacity is 90% or more.
In addition, the efficiency after above-mentioned negative-electrode active material for secondary battery preferably 50 times circulations is 98% or more.
In addition, according to another embodiment of the present invention, which is characterized in that provide a kind of secondary cell, above-mentioned cathode is by bearing
Pole active material is constituted, and it is by following chemical formula structure that the expansion rate after 50 circulations of the negative electrode active material, which is 70~150%,
At alloy, the decrystallized degree in alloy endobasal-body shape fine crystal region has 25% or more range, with atom % (at%)
Meter, the range with Si:60~70%, Ti:9~14%, Fe:9~14%, Al:5~19%.
SixTiyFezAlu (wherein, x, y, z, u in terms of atom % (at%), x:1- (y+z+u), y:0.09~0.14,
Z:0.09~0.14, u:0.05~0.19)
As described above, according to an embodiment of the invention, following effect can be played: the variation of volume when charge and discharge can be obtained
Electrical isolation, initial efficiency and the excellent anode active material for lithium secondary battery of capacity maintenance characteristics are generated less and infrequently.
In addition, according to an embodiment of the invention, following effect can be played: passing through the expansion rate after 50 circulations of measurement, energy
The decrystallized angle value for the negative electrode active material being optimized in battery design is enough provided.
In addition, according to an embodiment of the invention, following effect can be played: being capable of providing and consider amorphous when designing battery
Change degree and the negative electrode active material being optimized.
Detailed description of the invention
Figure 1A is tissue obtained by the expansion characteristics measured to negative electrode active material obtained in comparative example 50 times after recycling
Photo figure.
Figure 1B is tissue obtained by the expansion characteristics measured to negative electrode active material obtained in comparative example 50 times after recycling
Photo figure.
Fig. 1 C is tissue obtained by the expansion characteristics measured to negative electrode active material obtained in comparative example 50 times after recycling
Photo figure.
Fig. 2 is obtained to the expansion characteristics after 50 circulations of the measurement of negative electrode active material obtained in the embodiment of the present invention
Macrograph figure.
Fig. 3 is the figure for indicating the decrystallized degree measurement of negative electrode active material obtained in the embodiment of the present invention.
Specific embodiment
The details of other embodiments are comprised in detailed description of the invention and attached drawing.Advantages and features of the invention
And the method for realizing them can only be defined with the embodiment etc. being described in detail later with reference to the accompanying drawings.However, the present invention and unlimited
Due to embodiments disclosed below etc., and can be embodied with mutually different various ways, a part in the following description with
In the case that another part contacts, not only include the case where directly contacting, be also included among it via other media connection
Situation.In addition, part unrelated to the invention is omitted in order to keep explanation of the invention clear in attached drawing, in the whole instruction
In, identical reference numeral is imparted to similar part.Hereinafter, referring to attached drawing, the present invention will be described.
The embodiment of the present invention provides a kind of negative-electrode active material for secondary battery that expansion rate is improved and contains
The secondary cell of the negative-electrode active material for secondary battery.In particular, embodiment through the invention, can obtain secondary cell
The negative electrode active material for being 25% or more with the decrystallized degree in alloy endobasal-body shape fine crystal region in negative electrode active material.
In general, after chemical conversion (Formation) process, measurement is initial in the case where studying silicon systems negative electrode active material
Circulation full charge when electrode thickness compared with initial stage electrode thickness (injection electrolyte before electrode thickness) with which kind of journey
Degree increases.That is 1 later expansion rate of circulation is measured, but this refers to occlude the same of lithium in the negative active material
When the volume change that generates.
However, in an embodiment of the present invention, being charged and discharged repeatedly between 50 circulations of not above-mentioned 1 circulation of measurement
Thickness afterwards, the expansion rate after measuring 50 circulations compared with initial stage electrode thickness.It is swollen after 50 circulations in this way
The measurement of swollen rate, the side reaction that the volume change as caused by the occlusion of lithium, releasing can be monitored and occurred by active material surface
And cause SEI (solid electrolyte interface or the interphase: Solid Electrolyte accumulated while electrolyte decomposition
Interface or Interphase) layer generation degree.
It is usual as the metal lithium electrode to electrode when making characteristic of the coin-like half cells to evaluate silicon systems negative material
It can start to deteriorate and impact result after 50 circulations.Therefore, in an embodiment of the present invention, by being recycled at 50 times
The variation that Coin-shaped battery disintegration is measured to electrode thickness after the evaluation in service life considers not only and is caused by simple lithium occlusion
Initial stage pole plate expansion, it is also contemplated that as 50 times later circulation during side reaction layer growth caused by pole plate expand, form
For the index of negative electrode active material performance evaluation.Therefore, in an embodiment of the present invention, it was found that the expansion rate after 50 circulations
Variation be technically with suitable meaning Performance Evaluating Indexes, hereby it is possible to derive optimal composition range.
In general, the formation charging stage generates highly stable SEI layer, initial stage charging in the early stage for graphite
The volume change of pole plate is in 20% horizontal generation below after stage, therefore the SEI layer of charging stage at initial stage does not become significantly
Change and shows the trend for maintaining original state.However, for silicon systems negative electrode active material, due to the volume change of pole plate
Greatly, so initial stage separates in the SEI layer that active material surface generates, with stylish active matter when active material is shunk
The exposure of matter surface in the electrolytic solution, and generates new SEI layer on above-mentioned surface in expansion next time, the phenomenon continue repeatedly into
Row, to develop very thick SEI layer i.e. side reaction layer.
The side reaction layer for being deposited in active material surface plays the role of resistor body in secondary cell and can hinder lithium
It is mobile, in order to form side reaction layer, electrolyte is consumed, so as to cause to shorten battery life such problems.In addition, by
The increase of electrode thickness caused by the development of side reaction layer can make the jellyroll (jelly-roll) of battery that physical deformation occur, can
Current convergence can be generated the phenomenon that making battery rapid degradation on the pole plate of area.
For existing silicon alloy material, while charging, discharging repeatedly, inside active material, base
Body (Matrix) is kept intact and only silicon part shrinks, expands, thus generates cracking between matrix and silicon sometimes.This
When, there is electrolyte and is permeated into cracking and generate the side reaction layer of electrolyte in the inside of active material and make active material
The phenomenon that dispersion, observes the sharply expansion of electrode thickness after 50 circulations at this time.
The phenomenon that this phenomenon is not in when being the electrode thickness measurement after 1 circulation, even and suggesting
Substance with excellent initial stage expansion rate, when being actually used in battery, it is also possible to cause inside battery resistance increase with
And the various problems such as exhaustion of electrolyte.Therefore, the pole plate expansion after 50 circulations that the present embodiment proposes is in exploitation silicon systems
Evaluation index highly useful in the expansion, contraction with the evaluation of side reaction phenomenon of active material when negative electrode active material.
In an embodiment of the present invention, the size based on the expansion rate after recycling 50 times is used for the embodiment of the present invention
The composition of negative electrode active material metallic compound and studied, with derive with form change optimum expansion rate model
It encloses.
On the other hand, in an embodiment of the present invention, make the expansion of lithium there are fine crystal region on the matrix of alloy
It dissipates and is easier.Moreover, ratio existing for such fine crystal region can be indicated by decrystallized degree, it is non-by being formed with matrix shape
Crystalline region domain is able to suppress volume expansion of the secondary cell in charging.
It is a feature of the present invention that the decrystallized degree in matrix shape fine crystal region exists with 25% or more.In above-mentioned model
Enclose it is interior formed decrystallized when spending, the diffusion of lithium becomes very easy.Moreover, when in the range of such decrystallized degree,
Excellent expansion rate is similarly shown after 50 circulations, thus, it can be known that when above-mentioned material is used as negative electrode active material, charging
When volume expansion be inhibited.
In an embodiment of the present invention, when the rotation angle ゜ range of ゜~100 of 2 θ=20 of the XRD spectrum of alloy, amorphous
Change degree is preferably 25% or more.In the range of above-mentioned decrystallized degree, volume expansion is inhibited and can make electrical isolation well
It generates.
The calculating of decrystallized degree used in the present invention is as described below, is shown in Fig. 3, thus can find out decrystallized degree.
Decrystallized degree (%)=((entire area-crystallization area)) ÷ entire area)
In an embodiment of the present invention, decrystallized degree height refers to that fine crystal region is more, therefore, above-mentioned fine when charging
Lithium ion is accumulated by buffer function in crystal region, so as to obtain can inhibit volume expansion factor effect.
In addition, in an embodiment of the present invention, expansion rate after 50 circulations are provided with 70~150% range and by
The negative-electrode active material for secondary battery that following formulas is constituted.
SixTiyFezAlu(1)
(here, x, y, z, u in terms of atom % (at%), x:1- (y+z+u), y:0.09~0.14, z:0.09~0.14,
U: greater than 0.01 and less than 0.19)
In the present embodiment, above-mentioned Si has 60~70% range in terms of atom % (at%), and Ti and Fe have 9~14%
Range.On the other hand, above-mentioned Al, which has, is greater than 1% and the range less than 20%, preferably 5~19% range.
Ti, the Fe contained in alloy is bonded with Si and forms Si2Intermetallic compound as TiFe.Therefore, if Ti,
The content of Fe is respectively 14at%, then the Si of 28at% or more is consumed to form intermetallic compound, every g active matter occurs
The phenomenon that capacity of matter is reduced, at this point, the content of the Si put into must be non-if to obtain the capacity of 1000mAh/g or more
Chang Gao.
In general, the viscosity of molten metal is high when melting and quenching solidifies behaviour when containing being largely used as semimetallic Si
The trend that the property made is deteriorated, so the content of Si is maintained the range within 70% as far as possible, therefore the content of preferably Ti, Fe are not
More than 14%.In an embodiment of the present invention, related to expansion rate in the content for making Ti, Fe and derive optimal alloying component
In the process, deriving preferably makes the content of Ti, Fe be reduced to 14% or less.
In addition, Al can have the range greater than 1% and less than 20% in terms of at%.Containing 1% or so Al when, can be tight
Important place causes the expansion after 50 circulations, it may appear that the phenomenon that active material disperses, thus not preferred.In addition, when Al is 20%,
By Si: the variation guiding discharge capacity of matrix material score is reduced, thus not preferred.In an embodiment of the present invention, it derives
When Al has 5~19% range in terms of at%, there can be the range of most preferred expansion rate, it is known that in the range will not
Cause the reduction of discharge capacity.Al is most preferably 10~19%, can obtain most preferred 50 circulations expansion rate in the range
Range, and do not generate the reduction of discharge capacity.
In addition, the method for manufacturing negative electrode active material of the invention is not particularly limited, such as using public in the field
Know a variety of attritive powder manufacturing methods (gas atomization, centrifugal gas atomization, plasma atomization, rotary electrode method,
Mechanical alloying method etc.).
In the present invention, such as single roller quenching freezing method can be used to manufacture active material, which is quenched freezing method such as
Under: by Si and constitute matrix ingredient mix, using arc melting process etc. make mixture melt after, by above-mentioned fusant injection in
The copper roller of rotation.However, mode of the present invention is not limited to aforesaid way, in addition to single roller is quenched freezing method, only
Enough quenching speed can be obtained, above-mentioned attritive powder manufacturing method (gas atomization, centrifugal gas atomization can also be used
Method, plasma atomization, rotary electrode method, mechanical alloying method etc.) it is manufactured.
In addition, secondary cell can be manufactured using negative electrode active material obtained in one embodiment of the present of invention, it is secondary
(Lithiated) intercalation compound of lithiumation can be contained in battery as anode, in addition it is also possible to use inorganic sulfur (S8, sulphur
Simple substance: Elemental Sulfur) and chalcogenide compound (Sulfur Compound) can be enumerated as above-mentioned chalcogenide compound
Li2Sn (n >=1), the Li for being dissolved in catholyte (Catholyte)2Sn (n >=1), organosulfur compound or carbon-sulphur polymer
((C2Sf) n:f=2.5~50, n >=2) etc..
In addition, the type of the electrolyte contained by secondary cell of the invention is similarly not particularly limited, this can be used
Well known general means in field.In an example of the invention, above-mentioned electrolyte can containing Non-aqueous Organic Solvents and
Lithium salts.Above-mentioned lithium salts is dissolved in organic solvent, is played a role in battery as the supply source of lithium ion, can be promoted lithium
Movement of the ion between positive electrode and negative electrode.As the example of lithium salts workable in the present invention, can enumerate containing LiPF6、
LiBF4、LiSbF6、LiAsF6、LiCF3SO3、LiN(CF3SO2)3、Li(CF3SO2)2N、LiC4F9SO3、LiCl4, LiAlO4、
LiAlCl4、LiN(CxF2x+1SO2)(CyF2y+1SO2) (here, x and y be natural number), LiCl, Lil and dioxalic acid lithium borate
It is one kind or two or more as support (Supporting) electrolyte in (Lithium Bis oxalate Borate) etc..Electrolysis
The concentration of lithium salts in matter can change depending on the application, usually use in the range of 0.1M~2.0M.
In addition, above-mentioned organic solvent plays the work of the medium of the ion movement for the electrochemical reaction that can make to participate in battery
With therefore, as its example, benzene, toluene, fluorobenzene, 1,2- difluorobenzene, 1,3- difluorobenzene, Isosorbide-5-Nitrae-difluorobenzene, 1,2,3- can be enumerated
Trifluoro-benzene, 1,2,4- trifluoro-benzene, chlorobenzene, 1,2- dichloro-benzenes, 1,3- dichloro-benzenes, 1,4- dichloro-benzenes, 1,2,3- trichloro-benzenes, 1,2,4-
Trichloro-benzenes, iodobenzene (Iodobenzene), 1,2- diiodo-benzene, 1,3- diiodo-benzene, 1,4- diiodo-benzene, 1,2,3- triiodo-benzene, 1,2,4-
Triiodo-benzene, toluene fluoride, 1,2- difluoro toluene, 1,3- difluoro toluene, 1,4- difluoro toluene, 1,2,3- benzotrifluoride, 1,2,4- tri-
Toluene fluoride, chlorotoluene, 1,2- dichlorotoleune, 1,3- dichlorotoleune, 1,4- dichlorotoleune, 1,2,3- benzotrichloride, 1,2,4- tri-
Chlorotoluene, iodotoluene, bis- iodotoluene of 1,2-, bis- iodotoluene of 1,3-, bis- iodotoluene of 1,4-, tri- iodotoluene of 1,2,3-, 1,2,4- tri-
(here, R is the alkyl of straight-chain, branched or cyclic structure that carbon atom number is 2~50, and above-mentioned alkyl can by iodotoluene, R-CN
Containing double bond, aromatic ring or ehter bond etc.), dimethylformamide, dimethyl acetate, dimethylbenzene, thiacyclohexane, tetrahydrofuran,
2- methyltetrahydrofuran, cyclohexanone, ethyl alcohol, isopropanol, dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, carbonic acid first third
Ester, propylene carbonate, methyl propionate, ethyl propionate, methyl acetate, ethyl acetate, propyl acetate, dimethoxy-ethane, 1,3-
Dioxolane, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene carbonate, propylene carbonate, gamma-butyrolacton, ring fourth
One kind or two or more in sulfone, valerolactone, decalactone or valerolactone, but not limited to this.
In secondary cell of the invention other than containing above-mentioned important document, it can also further contain separator, tank, battery case
The common important document such as body or washer, specific type are similarly not particularly limited.In addition, secondary cell of the invention can be with
Containing important document as described above and usual manner and shape in this field is used to be manufactured.In addition, as of the invention two
The example for the shape that primary cell can have can enumerate cylinder-shaped, rectangular, coin-shaped or pouch-shaped etc., and but not limited to this.
[embodiment 1]
Hereinafter, referring to embodiment, the present invention will be described in more detail.
In the present embodiment, above-mentioned Si in terms of atom % (at%) with 60~70% range, Ti and Fe have 9~
14% range.On the other hand, above-mentioned Al, which has, is greater than 1% and the range less than 20%, but preferably 5~19% range.
Most preferably 10~19% range.
The compositing range of examples and comparative examples of the present invention is shown in following table 1.On the other hand, following table 2 is related to
Evaluation to the negative electrode active material of the composition based on above-mentioned table 1 particularly illustrates the 1CY- charge and discharge of embodiment and comparative example
Amount, 1CY- efficiency, 1CY- pole plate capacity, 50CY- discharge capacity, 50CY- efficiency, 50CY- capacity maintenance rate, 50CY- expansion rate,
Decrystallized degree (%).To the art-recognized meanings of 2 projects of table, will carry out aftermentioned.
In an embodiment of the present invention, 50 charge and discharge are repeated, measure projects.The mode of above-mentioned charge and discharge according to
It is well known generally in the art that the charge and discharge system of lithium secondary electron active material is carried out.
Firstly, in 1~embodiment of the embodiment of the present invention 5, forming in the range of being calculated as 5~19% by Al with at%
It carries out, comparative example 1 indicates the case where not adding Al, and comparative example 2 indicates the case where adding 1% Al.Comparative example 3 indicates addition
The case where 20% Al.
On the other hand, it for Ti, Fe, is bonded with Si and forms Si2Intermetallic compound as TiFe.Therefore,
When the content of Ti, Fe are high, Si is consumed in order to form intermetallic compound with Si, the capacity reduction of every g active material occurs
Phenomenon, at this point, the content of the Si put into must be very high if to obtain 1000mAh/g or more.Usually make containing a large amount of
When for semimetallic Si, the viscosity of molten metal is high and the trend that quenching solidification operability is deteriorated occur when melting, therefore best
The content of Si is maintained to the range within 70% as far as possible.Accordingly, it is considered to intermetallic compound is formed to Si, Ti, Fe's
Content is preferably more than 14%.
According to following table 1 and table 2 it is found that in an embodiment of the present invention, derive most keeping Ti, Fe related to expansion rate
During good alloying component, deriving preferably makes the content of Ti, Fe be reduced to 14% or less.
In addition, Al preferably has greater than 1% and the range less than 20% in terms of at%.Containing 1% or so Al when, can be tight
Important place causes the expansion after 50 circulations, occurs the scattered phenomenon of active material at this time, thus not preferred.In addition, Al is
When 20%, because of Si: guiding discharge capacity is sharply reduced due to the variation of matrix material score, thus not preferred.
In an embodiment of the present invention, deriving when in terms of atom % (at%) with 5~19% range has most
The range of preferred expansion rate, it is known that the reduction of discharge capacity will not be caused in the range.Al is most preferably 10~19%,
The range of most preferred 50 circulations expansion rate can be obtained in the range, and then will not generate the reduction of discharge capacity.
According to following table 2 and 1~embodiment of the embodiment of the present invention 5, addition Al can be identified through and activity can be improved
The performance of substance.In particular, when knowing addition Al discharge capacity can be significantly improved, can reverse efficiency, expansion characteristics.On the other hand,
For the comparative example 1 for being not added with Al, 50 times circulation expansion characteristics show the value greater than 200%.In addition, for comparative example 2
For, same as when being added to 1% Al, 50 times circulation expansion characteristics are greater than 200%.On the other hand, for being added to 20%
Al comparative example 3 for, 50 times circulation is expanded to 40.2%, very low, but discharge capacity writes and reduces at this time, therefore there are two
The problem of performance improvement effect of primary cell negative electrode active material reduces instead.
Therefore, in an embodiment of the present invention, according to following Tables 1 and 2s, it is known that by adding in the negative active material
Add Al, discharge capacity can be significantly improved, can reverse efficiency, expansion characteristics.In addition, knowing to make the additive amount of Al at this time in terms of at%
For the range at least more than 1% and less than 20%, optimal performance is reflected.In addition, for Comparative Examples 1 and 2, it is known that
Decrystallized degree (%) is less than 25%, therefore, it is known that in an embodiment of the present invention, preferred decrystallized in the composition range of Al
Degree is at least 25% or more.
Figure 1A, Figure 1B, Fig. 1 C and Fig. 2 are swollen namely for showing comparative example 2, after 50 circulations that embodiment 5 is related to
The macrograph figure of swollen rate characteristic.In Figure 1A, Figure 1B, Fig. 1 C, it can confirm that form the part of the shape of particle of light tone is matrix,
Dark-coloured background parts are Si, and at the initial stage before life test, similar to Fig. 1 C is the shape that matrix is assembled well, but repeatedly
After the charge and discharge for carrying out 50 circulations, the volume of the part Si is become larger, and the light-colored particles for constituting matrix constantly disperse.
In fig. 1 c, although be equally 50 circulations, matrix is unrelated with the contraction of silicon, expansion, not mutually
Disperse and assembles well.The phenomenon that active material matrix disperses brings sharply increasing for the expansion numerical value after 50 circulations.Picture
When Comparative Examples 1 and 2 adds 1% Al below like that, it is expanded to 200% or more after 50 circulations, shows very serious, phase
Instead, for the embodiment 5 for not observing active material dispersion phenomenon, it is known that the expansion rate after 50 circulations is about 78%,
Very excellent, life characteristic is also very excellent.
Table 1
[table 1]
| It distinguishes | Si (at%) | Ti (at%) | Fe (at%) | Al (at%) |
| Comparative example 1 | 70 | 15 | 15 | 0 |
| Comparative example 2 | 70 | 14.5 | 14.5 | 1 |
| Embodiment 1 | 70 | 12.5 | 12.5 | 5 |
| Embodiment 2 | 70 | 11.5 | 11.5 | 7 |
| Embodiment 3 | 70 | 10 | 10 | 10 |
| Embodiment 4 | 68 | 9 | 9 | 14 |
| Embodiment 5 | 65 | 10 | 10 | 15 |
| Comparative example 3 | 60 | 10 | 10 | 20 |
Table 2
Firstly, the active material evaluation in the embodiment of the present invention is carried out by making the pole plate of following compositions.
Silicon alloy active material is production conductivity additive (carbon black series): the ratio of binder (organic system, PAI binder) is
The pole plate of the composition of 86.6%:3.4%:10% and evaluated, the slurry being scattered in nmp solvent is made, using scraper
It is dry in 110 DEG C of baking oven Celsius after the slurry is coated on copper foil collector by mode, at 210 DEG C, in an ar atmosphere
Be heat-treated within 1 hour, solidifies binder.
Use pole plate made by the above method and make Coin-shaped battery using lithium metal as to electrode, following
Under the conditions of carry out formation process.
Charging (insertion lithium): 0.1C, 0.005V, 0.05C cut-off
Electric discharge (releases lithium): 0.1C, 1.5V cut-off
After formation process, loop test is carried out under the following conditions.
Charging: 0.5C, 0.01V, 0.05C cut-off
Electric discharge: 0.5C, 1.0V cut-off
In above-mentioned table 2,1CY- charging (mAh/g) is the formation charging capacity of every g active material, is in assembling Coin shape electricity
Chi Hou measures the quantity of electric charge as the charging stage in the formation process of the 1st charging stage, by it divided by Coin-shaped battery pole plate
It is worth obtained by the weight of contained active material.
1CY- electric discharge (mAh/g) is the chemical conversion discharge capacity of every g active material, is the measurement after assembling Coin-shaped battery
As discharge regime in the formation process of the 1st discharge regime the quantity of electric charge and by its divided by Coin-shaped battery pole plate contained by work
Property substance weight obtained by be worth.The capacity of every g in the present embodiment refers to that the discharge capacity measured at this time i.e. 0.1C chemical conversion is put
Capacitance.
1CY- efficiency is as follows: percentage being used to indicate as discharge capacity in the formation process of the 1st charging and discharging processes divided by filling
It is worth obtained by capacitance.In general, graphite has 94% high initial efficiency, silicon alloy has 80~90% initial efficiency, oxygen
SiClx (SiOx) is maximum to have 70% horizontal initial efficiency value.
It is due to producing following phenomenon that the initial efficiency of any substance, which is respectively less than 100%: when charging in formation process most
The lithium just put into is irreversibly captured or is consumed due to the side reactions such as SEI is formed, in the early stage when low efficiency, it may occur that by
The loss of negative electrode active material and positive active material must be put into this fractional additional, therefore when designing battery, it is important
Be initial efficiency height.
Silicon alloy used in the embodiment of the present invention has 85% initial efficiency value, due to conductivity additive and glues
Knot agent also irreversibly consumes lithium in the early stage, so the initial efficiency value of actual active material itself is about 90%.
50CY- electric discharge is the discharge capacity of every g active material in 50 circulations, survey when being the electric discharge in the 50th circulation
The fixed quantity of electric charge divided by obtained by active material weight be worth, the 50th time circulation include formation process after with 0.5C carry out circulation
Formation process in test.If active material deteriorates in loop test progress, by the numerical value lower than initial stage discharge capacity
It indicates, if indicated almost without deterioration by the numerical value similar with initial stage discharge capacity.
50CY- efficiency is to indicate value of the discharge capacity relative to the ratio of charge volume in 50 circulations with %.50CY- efficiency is got over
It is high, it is meant that the loss of lithium caused by the side reaction and other deteriorations in the circulation is fewer.In general, 50CY- efficiency is 99.5%
When above, it is determined as very good value, since the distribution of Coin-shaped battery assembling in laboratory environments can not be ignored, so
Also it is judged as good value when being 98% or more.
50CY- maintenance is other than circulation when carrying out formation process, when followed by 0.5C circulation, with the 1st time
On the basis of the discharge capacity of circulation, value obtained by the ratio of discharge capacity when indicating to recycle for the 50th time with %.
It can be found that the ratio that 50CY- is maintained is higher, the gradient of battery life is closer to ratio horizontal, that 50CY- is maintained
When being 90% or less, it is meant that occur to deteriorate and discharge capacity reduction in circulation progress.50CY- is had also appeared in section Example
The ratio of maintenance be higher than 100% the case where, but judge this is because the underway service life hardly happen deterioration, simultaneously addition
Ground shows the silicon particle being activated.
50CY- expansion is obtained by value added of the thickness relative to the thickness of initial stage pole plate after indicating 50 circulations with %
Value.The measuring method of 50CY- expansion as described in detail below.
Firstly, the thickness of measurement initial stage collector.Thereafter to being cut into circular shape in order to be assembled into Coin-shaped battery
After the pole plate of state measures its thickness using micrometer, subtracts the thickness of collector and calculate the thickness of only active material.
Then, after 50 loop tests, Coin-shaped battery is disintegrated from hothouse, only isolates negative plates
Afterwards, the electrolyte for remaining on pole plate is cleaned using DEC solution, is utilized micrometer to measure thickness after dry, is subtracted collector
Thickness and calculate circulation after active material thickness.That is, by the thickness of active material after 50 circulations relative to initial activity
Value obtained by the value added of the thickness of substance is indicated divided by the thickness of initial activity substance and with percentage is 50CY- expansion.
[embodiment 2]
Following tables 3 and table 4 to the experiment for confirming the proportional region of Ti and Fe show the embodiment of the present invention and
The 1CY- discharge and recharge of comparative example, 1CY- efficiency, 1CY- pole plate capacity, 50CY- discharge capacity, 50CY- efficiency, 50CY- capacity
Sustainment rate.The art-recognized meanings of projects of table 4 are as described above.
Table 3 shows the compositing range of examples and comparative examples of the present invention to confirm the proportional region of Ti and Fe.It will
The at% of other materials in addition to Ti, Fe etc. is fixed and is carried out, and is only changed and tested to the ratio of Ti and Fe.
According to following Table 3, the ratio of Ti and Fe are preferably the range of 2:1~1:2, further preferably the ratio of 1:1.Dimension
It holds the ratio of Ti and Fe and shows that capacity maintenance rate is up to 90% or more for the embodiment 6~8 of 2:1~1:2 range, as 1:
The embodiment 7 of 1 ratio is 96.4%, shows highest capacity maintenance rate.On the other hand, for de- with the ratio of Ti and Fe
For comparative example 4 and comparative example 5 that range from 2:1~1:2 is formed, capacity maintenance rate 51.2%, 81.3% is lower.
Therefore, in an embodiment of the present invention, in order to maximize battery performance, the ratio of Ti and Fe is maintained to the model of 2:1~1:2
In enclosing, the ratio in 1:1 is most preferably controlled.
Table 3
[table 3]
| It distinguishes | Si | Ti | Fe | Al |
| Comparative example 4 | It is fixed | 15 | 7 | 5 |
| Comparative example 5 | It is fixed | 7 | 15 | 5 |
| Embodiment 6 | It is fixed | 13 | 9 | 5 |
| Embodiment 7 | It is fixed | 11 | 11 | 5 |
| Embodiment 8 | It is fixed | 9 | 13 5 |
Table 4
Even if as described above, have the present invention belonging to technical field in Conventional wisdom people it will be appreciated that the present invention not
Changing its technical idea, necessary feature can also be implemented with other concrete modes.It is therefore understood that above-mentioned implementation
Example it is equal in terms of all from the point of view of be illustrative, and it is non-limiting.In addition, the scope of the present invention is by aftermentioned claim
What book indicated, rather than indicated by above-mentioned detailed description, it should be construed as the meaning and scope of claims and by it
Equivalents are derived have altered or modification after mode be all contained in the scope of the present invention.
Claims (9)
1. a kind of negative-electrode active material for secondary battery, which is characterized in that be the alloy being made of following chemical formula, base in alloy
The decrystallized degree in body shape fine crystal region is 29.2% to 45.5%, wherein the decrystallized degree is defined by following equation
:
Decrystallized degree (%)=((entire area-crystallization area) ÷ entire area),
The wherein range that the expansion rate after 50 circulations of the negative-electrode active material for secondary battery is 70~150%,
Wherein in the negative-electrode active material for secondary battery Ti and Fe atomic ratio have 2:1~1:2 range,
SixTiyFezAlu, wherein x, y, z, u in terms of atom %, x:1- (y+z+u), y:0.09~0.14, z:0.09~
0.14, u: greater than 0.01 and less than 0.2.
2. negative-electrode active material for secondary battery according to claim 1, which is characterized in that the secondary battery cathode
In active material, in terms of atom %, that is, at%, Al be 5~19% range.
3. negative-electrode active material for secondary battery according to claim 2, which is characterized in that the secondary battery cathode
In active material, in terms of atom %, that is, at%, Al be 10~19% range.
4. negative-electrode active material for secondary battery according to claim 1, which is characterized in that the secondary battery cathode
In active material, in terms of atom %, that is, at%, Ti and Fe are respectively provided with 9~12.5% range.
5. negative-electrode active material for secondary battery according to claim 1, which is characterized in that the secondary battery cathode
The atomic ratio of Ti and Fe is 1:1 in active material.
6. negative-electrode active material for secondary battery according to claim 1, which is characterized in that the secondary battery cathode
Discharge capacity after 50 times of active material circulations is 90% or more relative to initial stage discharge capacity.
7. negative-electrode active material for secondary battery according to claim 1, which is characterized in that the secondary battery cathode
Efficiency after 50 circulations of active material is 98% or more.
8. a kind of secondary cell, which is characterized in that containing cathode, anode and electrolyte, the cathode contain claim 1~
Negative electrode active material described in any one of 7.
9. secondary cell according to claim 8, which is characterized in that the cathode is by following negative electrode active material texture
At:
Expansion rate after 50 circulations is 70~150%,
For the alloy being made of following chemical formula, the decrystallized degree in alloy endobasal-body shape fine crystal region have 29.2% to
45.5% range, wherein the decrystallized degree is defined by following equation:
Decrystallized degree (%)=((entire area-crystallization area) ÷ entire area),
In terms of atom %, that is, at%, the range with Si:60~70%, Ti:9~14%, Fe:9~14%, Al:5~19%,
Wherein in the cathode Ti and Fe atomic ratio have 2:1~1:2 range
SixTiyFezAlu, wherein x, y, z, u are in terms of atom %, that is, at%, x:1- (y+z+u), y:0.09~0.14, z:
0.09~0.14, u:0.05~0.19.
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| EP3142174B1 (en) * | 2015-09-14 | 2021-02-17 | Toyota Jidosha Kabushiki Kaisha | All-solid-state battery system and method of manufacturing the same |
| JP6705302B2 (en) * | 2016-06-16 | 2020-06-03 | 日産自動車株式会社 | Negative electrode active material for electric device and electric device using the same |
| KR20180072484A (en) | 2016-12-21 | 2018-06-29 | 일진전기 주식회사 | Negative active material for secondary battery and second battery using the same |
| JP6860125B2 (en) * | 2017-01-06 | 2021-04-14 | 学校法人早稲田大学 | Secondary battery |
| JP7006545B2 (en) * | 2018-09-07 | 2022-01-24 | トヨタ自動車株式会社 | Solid state battery |
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| KR20050090220A (en) * | 2004-03-08 | 2005-09-13 | 삼성에스디아이 주식회사 | Negative active material for lithium secondary battery, method of preparing the same, and lithium secondary battery comprising the same |
| CN103098266A (en) * | 2010-06-10 | 2013-05-08 | 株式会社Lg化学 | Cathode active material for lithium secondary battery and lithium secondary battery provided with same |
| CN103107316A (en) * | 2011-11-15 | 2013-05-15 | 信越化学工业株式会社 | Negative electrode material for lithium ion batteries |
| KR20140080580A (en) * | 2012-12-12 | 2014-07-01 | 일진전기 주식회사 | Alloy method of complex metal for negative active material |
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| US20110183209A1 (en) * | 2010-01-27 | 2011-07-28 | 3M Innovative Properties Company | High capacity lithium-ion electrochemical cells |
| KR101749187B1 (en) * | 2013-11-19 | 2017-06-20 | 삼성에스디아이 주식회사 | Negative active material and negative electrode and lithium battery containing the material, and method for manufacturing the material |
| JPWO2015132856A1 (en) * | 2014-03-03 | 2017-03-30 | 日立オートモティブシステムズ株式会社 | Lithium ion secondary battery |
| JP2016018654A (en) * | 2014-07-08 | 2016-02-01 | 株式会社日立製作所 | Lithium ion secondary battery |
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| KR20050090220A (en) * | 2004-03-08 | 2005-09-13 | 삼성에스디아이 주식회사 | Negative active material for lithium secondary battery, method of preparing the same, and lithium secondary battery comprising the same |
| CN103098266A (en) * | 2010-06-10 | 2013-05-08 | 株式会社Lg化学 | Cathode active material for lithium secondary battery and lithium secondary battery provided with same |
| CN103107316A (en) * | 2011-11-15 | 2013-05-15 | 信越化学工业株式会社 | Negative electrode material for lithium ion batteries |
| KR20140080580A (en) * | 2012-12-12 | 2014-07-01 | 일진전기 주식회사 | Alloy method of complex metal for negative active material |
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