CN105870433A - Negative electrode active material for secondary battery, and secondary battery arranged by use thereof - Google Patents
Negative electrode active material for secondary battery, and secondary battery arranged by use thereof Download PDFInfo
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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- Y02E60/10—Energy storage using batteries
Abstract
The invention provides a negative electrode active material for a lithium secondary battery which is small in volume change when charged and discharged, and hard to cause electrical insulation. The present invention provides a negative electrode active material for a secondary battery with an improved expansion coefficient. The negative electrode active material comprises: an alloy represented by SixTiyFezAlu (where "x", "y", "z" and "u" are represented in atom% and given as follows. x=1-(y+z+u), y is 0.09 to 0.14, z is 0.09 to 0.14, and u is over 0.01 to less than 0.2). The negative electrode active material is 70-150% in expansion coefficient after 50 cycles. The degree of amorphization of a matrix like region in the alloy is in a range of 25% or larger. The contents of Si, Ti, Fe and Al are represented in atom% (at%) as follows. Si is 60-70%; Ti is 9-14%; Fe is 9-14%; and Al is in a range between 1 and 20% exclusive.
Description
Technical field
The present invention relates to negative-electrode active material for secondary battery and make use of this secondary battery cathode
The secondary cell of active substance.
Background technology
In the past, use lithium metal was as the negative electrode active material of lithium battery, but was using lithium metal
Time, it may occur that the battery short circuit caused because forming dendrite (Dendrite), thus have blast
Danger, is therefore used mostly carbon system material and replaces lithium metal as negative electrode active material.
As above-mentioned carbon system active substance, there are graphite and Delanium such system of crystallization carbon and soft
Carbon (Soft Carbon) and hard carbon (Hard Carbon) such amorphous carbon.But, on
Although it is big to state amorphous carbon capacity, but there is the problem that irreversibility in charge and discharge process is big.As
System of crystallization carbon, uses graphite typically, and its theoretical limit capacity is 372mAh/g, and capacity is high
And it is used as negative electrode active material.
But, even if such graphite, carbon system active substance are it may be said that theoretical capacity is slightly higher, also only
It is but about 380mAh/g, cannot use above-mentioned negative when there is Future Development high-capacity lithium battery
The problem of pole.
In order to improve such problem, currently the material of actively research is between metal system or metal
The negative electrode active material of series of compounds.Such as, have studied utilization aluminum, germanium, silicon, stannum, zinc, lead
Deng metal or semimetal as the lithium battery of negative electrode active material.Such material is for high power capacity
There is high-energy-density simultaneously, can inhale compared with the negative electrode active material that make use of carbon-based material
Stay the more lithium ion of releasing, it is possible to manufacture the battery with high power capacity and high-energy-density.Example
As, it is known that pure silicon has the high theoretical capacity of 4017mAh/g.
But, when it being compared with carbon-based material, cycle characteristics decreases, still to practical
Constituting and hinder, this is the occlusion owing to will be directly used as lithium as the above-mentioned silicon etc. of negative electrode active material
Following phenomenon can be produced: cause due to the change of volume in charge and discharge process with when releasing material
Electric conductivity between active substance reduces or negative electrode active material is peeled off from negative electrode collector.That is,
The above-mentioned silicon contained in negative electrode active material etc. are occlusion lithium because of charging, and volumetric expansion is to about
300～the degree of 400%, during electric discharge, if releasing lithium, then inanimate matter particle shrinks.
If such charge and discharge cycles is repeated, then sometimes due to the splitting of negative electrode active material
Stricture of vagina and produce electric insulation, the life-span drastically reduces, therefore when for lithium battery have problems.It addition,
In order to improve such problem, carry out the following studies: use nano level particle as silicon particle,
Or make silicon have porous and there is the buffering effect to change in volume.
KR published patent the 2004-0063802nd relate to anode active material for lithium secondary battery,
Its manufacture method and lithium secondary battery, use other metals such as making silicon and nickel to make this gold after forming alloy
Belong to the method flowed out, it addition, KR published patent the 2004-0082876th relates to porous silicon
With the manufacture method of nano silicone particle and the application in negative electrode material for lithium secondary cell, public affairs
Open and alkali metal or the silicon precursor such as alkaline-earth metal and silicon dioxide of pulverulence are mixed and carry out
It is allowed to the technology flowed out with acid after heat treatment.
Above-mentioned patent etc. utilize the buffering effect that brought by cellular structure and may the raising initial stage
Capacity dimension holdup, but due to only use conductivity difference porous silicon particle, if so particle not
Be nano-scale, then when manufacturing electrode, interparticle electrical conductivity can reduce, and there is initial efficiency, appearance
Amount maintains the problem that characteristic reduces.
Patent documentation
Patent documentation 1: KR published patent the 2004-0063802nd
Patent documentation 2: KR published patent the 2004-0082876th
Summary of the invention
Therefore, the present invention proposes to solve the problems referred to above, its objective is to provide one to fill
Volume with low uncertainty during electric discharge and be not likely to produce the anode active material for lithium secondary battery of electric insulation.
It addition, it is a further object of the present invention to provide a kind of initial efficiency and capacity maintenance excellent
Anode active material for lithium secondary battery.
It addition, it is yet another object of the invention to provide a kind of consider decrystallized degree when designing battery and
The negative electrode active material being optimized.
To achieve these goals, embodiments of the invention are characterised by providing a kind of secondary cell
With negative electrode active material, it is as the alloy being made up of following chemical formula, and alloy endobasal-body shape is fine
The decrystallized degree of crystal region is more than 25%.
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: more than 0.01 and less than 0.2)
Expansion rate after the preferably 50 times circulations of above-mentioned negative-electrode active material for secondary battery is
70～the scope of 150%.
It addition, in above-mentioned negative-electrode active material for secondary battery, in terms of atom % (at%), Al
Preferably there is the scope of 5～19%.
It addition, in above-mentioned negative-electrode active material for secondary battery, in terms of atom % (at%), Al
Preferably there is the scope of 10～19%.
It addition, in above-mentioned negative-electrode active material for secondary battery, in terms of atom % (at%), Ti
The scope of 9～12.5% preferably it is respectively provided with Fe.
It addition, in above-mentioned negative-electrode active material for secondary battery, the ratio of Ti with Fe preferably has
The scope of 2:1～1:2.
It addition, in above-mentioned negative-electrode active material for secondary battery, the ratio of Ti with Fe preferably has
The scope of 1:1.
It addition, the discharge capacity after the preferably 50 times circulations of above-mentioned negative-electrode active material for secondary battery
It is more than 90% relative to initial stage discharge capacity.
It addition, the efficiency after the preferably 50 times circulations of above-mentioned negative-electrode active material for secondary battery is 98%
Above.
Additionally, according to another embodiment of the present invention, it is characterised in that a kind of secondary cell is provided,
Above-mentioned negative pole is made up of negative electrode active material, the expansion after 50 circulations of this negative electrode active material
Rate is 70～150%, is the alloy being made up of following chemical formula, alloy endobasal-body shape fine crystal district
The decrystallized degree in territory has the scope of more than 25%, in terms of atom % (at%), has
The scope of 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 it has been described above, according to embodiments of the invention, following effect can be played: can obtain charge and discharge
Volume with low uncertainty during electricity and infrequently produce electric insulation, initial efficiency and capacity and maintain excellent
Anode active material for lithium secondary battery.
It addition, according to embodiments of the invention, following effect can be played: follow for 50 times by measuring
Expansion rate after ring, using the teaching of the invention it is possible to provide the negative electrode active material being optimized in battery design decrystallized
Angle value.
It addition, according to embodiments of the invention, following effect can be played: can provide at design electricity
The negative electrode active material considering decrystallized degree during pond and be optimized.
Accompanying drawing explanation
Figure 1A is that the expansion after the negative electrode active material obtained in comparative example measures 50 circulations is special
Macrograph figure obtained by property.
Figure 1B is that the expansion after the negative electrode active material obtained in comparative example measures 50 circulations is special
Macrograph figure obtained by property.
Fig. 1 C is that the expansion after the negative electrode active material obtained in comparative example measures 50 circulations is special
Macrograph figure obtained by property.
Fig. 2 be the negative electrode active material that obtains in embodiments of the invention is measured 50 circulations after
Expansion characteristics obtained by macrograph figure.
Fig. 3 is that the decrystallized degree representing the negative electrode active material obtained in embodiments of the invention measures
Figure.
Detailed description of the invention
The details of other embodiments are comprised in detailed description of the invention and accompanying drawing.The present invention
As long as advantage and feature and realize their method referring to the drawings and the embodiment that is described in detail later
Clear and definite Deng getting final product.But, the present invention is not limited to embodiments disclosed below etc., and can be with
Mutually different various ways embodies, the feelings that a part in the following description and another part contact
Under condition, not only include situation about directly contacting, be also included within and contact via other medium in the middle of it
Situation.It addition, in order to make the explanation of the present invention clearly eliminate unrelated to the invention in accompanying drawing
Part, throughout the specification, imparts identical reference numeral to similar part.Hereinafter,
The present invention will be described referring to the drawings.
The secondary battery cathode that embodiments of the invention provide a kind of expansion rate to be improved is lived
Property material and containing the secondary cell of this negative-electrode active material for secondary battery.Particularly, by this
Inventive embodiment, it is possible to obtain alloy endobasal-body shape in negative-electrode active material for secondary battery fine
The negative electrode active material that decrystallized degree is more than 25% of crystal region.
Generally, in the case of research silicon system negative electrode active material, in chemical conversion (Formation)
After operation, electrode thickness when measuring the full charge of initial circulation (injects with initial stage electrode thickness
Electrode thickness before electrolyte) compare and with which kind of degree increase.That is measure 1 time circulation with
After expansion rate, but this refers in negative electrode active material the volume produced while occlusion lithium
Change.
But, in an embodiment of the present invention, measure 50 circulations of the most above-mentioned 1 circulation
Between thickness after charging and discharging repeatedly, after measuring 50 circulations compared with initial stage electrode thickness
Expansion rate.Measured by the expansion rate after such 50 circulations, it is possible to monitor by the suction of lithium
Stay, release the change in volume caused and cause at electricity because of the side reaction of active material surface generation
Solve SEI (solid electrolyte interface or mesophase: the Solid piled up while liquid decomposes
Electrolyte Interface or Interphase) the generation degree of layer.
When making the characteristic that coin-like half cells evaluates silicon system negative material, it is used as the lithium to electrode
Metal electrode generally can start deterioration after 50 circulations and impact result.Therefore, exist
In embodiments of the invention, by Coin-shaped battery being disintegrated after the evaluation of 50 cycle lives
Measure the change of electrode thickness, consider not only the initial stage pole plate caused by simple lithium occlusion swollen
It is swollen, it is also contemplated that the pole plate caused by the growth of the side reaction layer during afterwards 50 circulations expands,
And become the index of negative electrode active material performance evaluation.Therefore, in an embodiment of the present invention, send out
The change having showed the expansion rate after 50 circulations is the performance evaluation technically with suitable meaning
Index, hereby it is possible to derive optimal composition range.
Generally, in the case of for graphite, the formation charging stage produces highly stable SEI in the early stage
Layer, after the charging stage at initial stage, the change in volume of pole plate produces in 20% level below, therefore the initial stage
The SEI layer of charging stage does not changes significantly and shows the trend that maintains original state.So
And, for silicon system negative electrode active material, owing to the change in volume of pole plate is big, so working as active substance
During contraction, the SEI layer that the initial stage produces at active material surface separates, with stylish active matter
Matter surface exposes in the electrolytic solution, and produces new SEI layer on above-mentioned surface when next time expands,
This phenomenon persistently repeats, thus develops the thickest SEI layer i.e. side reaction layer.
The side reaction layer being deposited in active material surface plays the effect of resistive element in secondary cell
And the movement of lithium can be hindered, in order to form side reaction layer, electrolyte to be consumed, consequently, it is possible to cause
Shorten the such problem of battery life.It addition, the electrode thickness caused by the development of side reaction layer
Increase can make the jellyroll (jelly-roll) of battery that physical deformation occurs, and may produce electric current collection
In on the pole plate of area, make the phenomenon of battery rapid degradation.
In the case of for existing aluminosilicate alloy material, while repeatedly charging, discharging, living
Inside property material, matrix (Matrix) is kept intact and only silicon part shrinks, expands, because of
And between matrix and silicon, sometimes produce be full of cracks.Now, occur electrolyte to be full of cracks in infiltration and
The scattered phenomenon of active substance is made at the side reaction layer being internally generated electrolyte of active substance, this
Time observe the drastically expansion of electrode thickness after 50 circulations.
This phenomenon is the phenomenon not had during the electrode thickness mensuration after 1 circulation, and
Even suggesting the material of the initial stage expansion rate with excellence, when being actually used in battery, it is possible to
Can cause the various problems such as the resistance increase of inside battery and the exhaustion of electrolyte.Therefore, originally
It is to live when developing silicon system negative electrode active material that pole plate after 50 circulations that embodiment proposes expands
Evaluation index highly useful in the property expansion of material, contraction and the evaluation of side reaction phenomenon.
In an embodiment of the present invention, size based on the expansion rate after circulating 50 times is used for this
The composition of the negative electrode active material metallic compound of inventive embodiment and study, to derive
Go out the scope of the optimum expansion rate changed with composition.
On the other hand, in an embodiment of the present invention, the matrix of alloy exists fine crystal district
Territory and make lithium diffusion be easier to.And, the ratio that such fine crystal region exists can be by non-
Degree of crystallization represents, by forming non-crystalline areas with matrix shape, it is possible to suppression secondary cell is when charging
Volumetric expansion.
It is a feature of the present invention that the decrystallized degree in matrix shape fine crystal region is deposited with more than 25%
?.When forming decrystallized spending within the above range, the diffusion of lithium becomes very easy.And, when
When being in the range of such decrystallized degree, after 50 circulations, demonstrate the expansion of excellence too
Rate, during thus, it can be known that above-mentioned material is used as negative electrode active material, volumetric expansion during charging obtains
To suppression.
In an embodiment of the present invention, when the anglec of rotation 2 θ=20 that the XRD figure of alloy is composed
～during 100 scope, decrystallized degree is preferably more than 25%.In the range of above-mentioned decrystallized degree,
Volumetric expansion is inhibited and electric insulation can be made to produce well.
Being calculated as follows of the decrystallized degree used in the present invention is described, is shown in Fig. 3, thus may be used
Obtain 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 many, therefore, fills
Lithium ion is accumulated by cushioning effect in above-mentioned fine crystal region such that it is able to obtaining can during electricity
The effect of the expansion factor of suppression volume.
It addition, in an embodiment of the present invention, it is provided that the expansion rate after 50 circulations has
70～the scope of 150% and the negative-electrode active material for secondary battery that is made up of following formula.
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: more than 0.01 and less than 0.19)
In the present embodiment, above-mentioned Si has the scope of 60～70%, Ti in terms of atom % (at%)
With the scope that Fe has 9～14%.On the other hand, above-mentioned Al has more than 1% and less than 20%
Scope, preferably 5～the scope of 19%.
Ti, Fe of containing in alloy are bonded with Si and form Si2The such intermetallic compound of TiFe.
Therefore, if the content of Ti, Fe is respectively 14at%, then in order to form intermetallic compound and
Consume more than 28at% Si, occur every g active substance capacity reduce phenomenon, now, as
The capacity of fruit more than 1000mAh/g to be obtained, then the content of the Si put into must be the highest.
Generally, containing time in a large number as semimetallic Si, when occurring melted, the viscosity of motlten metal is high
And be quenched solidification operability be deteriorated trend, so as far as possible the content of Si is maintained 70% with
Interior scope, therefore the content of preferred Ti, Fe is less than 14%.In an embodiment of the present invention,
The content making Ti, Fe relevant to expansion rate and during optimal alloying component of deriving, push away
Deriving preferably makes the content of Ti, Fe be reduced to less than 14%.
It addition, Al can have the scope more than 1% and less than 20% in terms of at%.Containing 1%
Left and right Al time, can seriously cause 50 times circulation after expansion, it may appear that active substance disperse
Phenomenon, thus the most preferred.During it addition, Al is 20%, by Si: the change of matrix material mark
Guiding discharge capacity reduces, thus the most preferred.In an embodiment of the present invention, derive and work as Al
Have in terms of at% 5～19% scope time, can have the scope of most preferred expansion rate, it is known that
The minimizing of discharge capacity will not be caused within the range.Al is most preferably 10～19%, in this scope
The scope of most preferred 50 circulation expansion rates can be obtained, and do not produce the minimizing of discharge capacity.
It addition, the method manufacturing the negative electrode active material of the present invention is not particularly limited, such as can profit
By multiple attritive powder manufacture method well known in the art, (gas atomization, centrifugal gas are atomized
Method, plasma atomization, rotary electrode method, mechanical alloying method etc.).
In the present invention, such as can use single roller quenching freezing method to manufacture active substance, this list roller
Quenching freezing method is as follows: by the composition mixing of Si and composition matrix, use arc melting process etc. to make
After mixture is melted, above-mentioned fused mass is sprayed in the copper roller rotated.But, the present invention is used
Mode be not limited to aforesaid way, in addition to single roller quenching freezing method, as long as available enough
Quenching speed, it is possible to use above-mentioned attritive powder manufacture method (gas atomization, centrifugal gas
Body atomization, plasma atomization, rotary electrode method, mechanical alloying method etc.) manufacture.
It addition, the negative electrode active material obtained in available one embodiment of the present of invention manufactures two
Primary cell, in secondary cell can containing (Lithiated) intercalation compound of lithiumation as positive pole,
In addition it is also possible to use inorganic sulfur (S8, sulfur simple substance: Elemental Sulfur) and sulfur system
Compound (Sulfur Compound), as above-mentioned chalcogenide compound, can enumerate Li2Sn(n≥1)、
It is dissolved in the Li of catholyte (Catholyte)2Sn (n >=1), organosulfur compound or carbon-
Sulfur polymer ((C2Sf) n:f=2.5～50, n >=2) etc..
It addition, the kind of the electrolyte contained by the secondary cell of the present invention limits the most especially
Fixed, general means well known in the art can be used.In an example of the present invention, above-mentioned electricity
Solve liquid and can contain Non-aqueous Organic Solvents and lithium salts.Above-mentioned lithium salts is dissolved in organic solvent,
Play a role as the supply source of lithium ion in battery, it is possible to promote that lithium ion is at positive pole and negative pole
Between movement.As the example of lithium salts spendable 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 is natural number), LiCl, Lil and dioxalic acid Lithium biborate (Lithium Bis
Oxalate Borate) etc. in one kind or two or more as support (Supporting) electrolyte.
The concentration of the lithium salts in electrolyte can change according to purposes, generally in the scope of 0.1M～2.0M
Interior use.
It addition, the ion that above-mentioned organic solvent plays the electrochemical reaction that can make participation battery moves
The effect of medium, accordingly, as its example, can enumerate benzene, toluene, fluorobenzene, 1,2-difluoro
Benzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3-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-benzotrifluoride, chlorotoluene, 1,2-dichlorotoleune, 1,3-dichlorotoleune, 1,4-
Dichlorotoleune, 1,2,3-benzotrichloride, 1,2,4-benzotrichloride, iodotoluene, 1,2-bis-iodotoluene,
1,3-bis-iodotoluene, 1,4-bis-iodotoluene, 1,2,3-tri-iodotoluene, 1,2,4-tri-iodotoluene, R-CN
(here, R be carbon number be the alkyl of straight-chain, branched or the circulus of 2～50,
Above-mentioned alkyl can contain double bond, aromatic ring or ehter bond etc.), dimethylformamide, acetic acid two
Methyl ester, dimethylbenzene, thiacyclohexane, oxolane, 2-methyltetrahydrofuran, Ketohexamethylene, ethanol,
Isopropanol, dimethyl carbonate, Ethyl methyl carbonate, diethyl carbonate, methyl propyl carbonate, carbonic acid are sub-
Propyl ester, methyl propionate, ethyl propionate, methyl acetate, ethyl acetate, propyl acetate, dimethoxy
Base ethane, 1,3-dioxolane, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, carbonic acid Asia second
In ester, propylene carbonate, gamma-butyrolacton, sulfolane, valerolactone, decalactone or valerolactone 1
Plant or two or more, but be not limited to this.
In the secondary cell of the present invention in addition to containing above-mentioned important document, it is also possible to contain isolation further
The common important documents such as part, tank, battery container or packing ring, its concrete kind is too the most especially
Limit.It addition, the secondary cell of the present invention can contain important document as above and use this area
In usual manner and shape manufacture.It addition, can have as the secondary cell of the present invention
The example of shape, can enumerate cylindrical shape, square, coin-shaped or pouch-shaped etc., but be not limited to this.
[embodiment 1]
Hereinafter, with reference to embodiment, the present invention will be described in more detail.
In the present embodiment, above-mentioned Si has the scope of 60～70% in terms of atom % (at%),
Ti and Fe has the scope of 9～14%.On the other hand, above-mentioned Al has more than 1% and is less than
The scope of 20%, but preferably 5～the scope of 19%.Most preferably 10～the scope of 19%.
Table 1 below shows the compositing range of examples and comparative examples of the present invention.On the other hand,
Table 2 below relates to the evaluation of the negative electrode active material to composition based on above-mentioned table 1, specifically shown
The 1CY-discharge and recharge of embodiment and comparative example, 1CY-efficiency, 1CY-pole plate capacity, 50CY-
Discharge capacity, 50CY-efficiency, 50CY-capacity dimension holdup, 50CY-expansion rate, decrystallized degree (%).
Art-recognized meanings to table 2 projects, will carry out aftermentioned.
In an embodiment of the present invention, 50 discharge and recharge is repeated, measures projects.Above-mentioned
Lithium secondary electron active substance is filled by the mode of discharge and recharge according to known generally in the art
Discharge mode is carried out.
First, in embodiments of the invention 1～embodiment 5, it is calculated as 5～19% by Al with at%
In the range of composition carry out, comparative example 1 represents that the situation without Al, comparative example 2 represent
Add the situation of the Al of 1%.Comparative example 3 represents the situation of the Al adding 20%.
On the other hand, for Ti, Fe, it is bonded with Si and forms Si2The such metal of TiFe
Between compound.Therefore, during the content height of Ti, Fe, in order to form intermetallic compound with Si
Consume Si, the phenomenon that the capacity of every g active substance reduces occurs, now, if to obtain
More than 1000mAh/g, then the content of the Si put into must be the highest.Generally making containing a large amount of
During for semimetallic Si, time melted, the viscosity of motlten metal is high and occur that quenching solidification operability becomes
The trend of difference, maintains the scope within 70% by the content of Si the most as far as possible.Therefore,
Forming intermetallic compound in view of with Si, the content of Ti, Fe is preferably more than 14%.
According to table 1 below and table 2, in an embodiment of the present invention, make Ti, Fe with
Expansion rate is correlated with and during optimal alloying component of deriving, is derived and preferably make Ti, Fe
Content is reduced to less than 14%.
It addition, Al preferably has greater than 1% in terms of at% and is less than the scope of 20%.Containing 1%
Left and right Al time, can seriously cause 50 times circulation after expansion, active substance quilt now occurs
Scattered phenomenon, thus the most preferred.During it addition, Al is 20%, because of Si: matrix material mark
Change and guiding discharge capacity drastically reduces, thus the most preferred.
In an embodiment of the present invention, derive in terms of atom % (at%), have 5～19%
There is the scope of most preferred expansion rate, it is known that discharge capacity will not be caused within the range during scope
Minimizing.Al is most preferably 10～19%, can get most preferred 50 circulations in this scope swollen
The scope of swollen rate, and then the minimizing of discharge capacity will not be produced.
According to table 2 below and embodiments of the invention 1～embodiment 5, can confirm that by adding Al
And the performance of active substance can be improved.Particularly, it is known that when adding Al, can significantly improve and put
Capacitance, can reverse efficiency, expansion characteristics.On the other hand, for being not added with the comparative example 1 of Al
For, 50 times circulation expansion characteristics shows the value more than 200%.It addition, for comparative example 2
Speech, as during the Al that with the addition of 1%, 50 circulation expansion characteristics are more than 200%.The opposing party
Face, for the addition of the comparative example 3 of Al of 20%, 50 circulations are expanded to 40.2%,
The lowest, but now discharge capacity writes minimizing, therefore there is the property of secondary battery negative pole active substance
The problem that effect reduces on the contrary can be improved.
Therefore, in an embodiment of the present invention, according to following Tables 1 and 2, it is known that by
In negative electrode active material add Al, can significantly improve discharge capacity, can reverse efficiency, expansion characteristics.
It is calculated as at least above 1% and less than 20% it addition, understand the addition making Al now with at%
Scope, reflect optimal performance.It addition, for comparative example 1,2, it is known that non-
Degree of crystallization (%) is less than 25%, therefore, it is known that in an embodiment of the present invention, at the one-tenth of Al
In the range of Fen, preferred decrystallized degree is at least more than 25%.
Figure 1A, Figure 1B, Fig. 1 C and Fig. 2 namely for representing comparative example 2, embodiment 5 relates to
And 50 circulations after the macrograph figure of expansion rate characteristic.At Figure 1A, Figure 1B, Fig. 1 C
In, can confirm that the part of the shape of particle forming light tone is matrix, dark-coloured background parts is Si,
Initial stage before life test, the shape for matrix well assembled similar to Fig. 1 C, but repeatedly
After carrying out the discharge and recharge of 50 circulations, the volume of Si part becomes larger, and constitutes the light tone of matrix
Particle constantly disperses.
In fig. 1 c, although be the situation of 50 circulations equally, but the contraction of matrix and silicon,
Expand unrelated, the most mutually disperse and assemble well.The scattered phenomenon of active substance matrix brings 50
Sharply increasing of expansion numerical value after secondary circulation.Less than 1% is added as comparative example 1,2
During Al, after 50 circulations, it is expanded to more than 200%, shows very serious, conversely, for
For not observing the embodiment 5 of active substance dispersion phenomenon, it is known that the expansion after 50 circulations
Rate is about 78%, the most excellent, and life characteristic is the most excellent.
Table 1
[table 1]
| Distinguish | 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
First, the active substance evaluation in embodiments of the invention is the pole by making following composition
Plate is carried out.Silicon alloy active substance is to make conductivity additive (white carbon black series): bonding
The pole plate of the composition that ratio is 86.6%:3.4%:10% of agent (organic system, PAI binding agent) and
It is evaluated, makes the slurry being scattered in nmp solvent, use scraper mode by this slurry
After being coated on Copper Foil collector body, it is dried in the baking oven of 110 DEG C Celsius, when 210 DEG C,
Ar atmosphere carries out 1 hour heat treatment, makes binding agent solidify.
Use the pole plate using said method to make and using lithium metal as electrode being made coin
Type battery, carries out formation process under the following conditions.
Charging (insertion lithium): 0.1C, 0.005V, 0.05C cut-off
Electric discharge (releasing lithium): 0.1C, 1.5V cut-off
After formation process, it is circulated test 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 substance,
It is after assembling Coin-shaped battery, measures as the charging rank in the formation process of the 1st charging stage
The quantity of electric charge of section, by it divided by obtained by the weight of the active substance contained by Coin-shaped battery pole plate
Value.
1CY-electric discharge (mAh/g) is the chemical conversion discharge capacity of every g active substance, is to assemble firmly
After coin type battery, measure as the quantity of electric charge of discharge regime in the formation process of the 1st discharge regime also
It is worth divided by obtained by the weight of the active substance contained by Coin-shaped battery pole plate.The present embodiment
In the capacity of every g refer to that the i.e. 0.1C of discharge capacity now recorded is melted into discharge capacity.
1CY-efficiency is as follows: be denoted as in the formation process of the 1st discharge and recharge operation putting with percent
Capacitance is worth divided by obtained by charging capacity.Generally, graphite has the high initial efficiency of 94%, silicon
Alloy has the initial efficiency of 80～90%, and silicon oxide (SiOx) maximum has at the beginning of 70% level
Phase efficiency value.
The initial efficiency of any material respectively less than 100% is owing to creating following phenomenon: chemical conversion work
The lithium initially put into during charging in sequence is irreversibly captured or because of side reactions such as SEI formation
It is consumed, when efficiency is low in the early stage, it may occur that negative electrode active must be put into due to this fractional additional
Material and the loss of positive active material, therefore when designing battery, it is important that initial efficiency is high.
The silicon alloy used in embodiments of the invention has the initial efficiency value of 85%, due to conduction
Property additive and binding agent the most irreversibly consume lithium, so the active substance of reality itself
Initial efficiency value be about 90%.
50CY-electric discharge is the discharge capacity of every g active substance in 50 circulations, is at the 50th time
The quantity of electric charge measured during electric discharge in circulation is worth divided by obtained by active substance weight, the 50th time
Formation process in the loop test that circulation is carried out with 0.5C after including formation process.If it is active
Material deteriorates in loop test is carried out, then by the numeric representation lower than initial stage discharge capacity, if
Almost without deterioration, then by the numeric representation similar with initial stage discharge capacity.
50CY-efficiency is to represent that in 50 circulations, discharge capacity is relative to the ratio of charge volume with %
Value.50CY-efficiency is the highest, it is meant that the lithium that the side reaction in this circulation and other deterioration cause
Lose the fewest.Generally, when 50CY-efficiency is more than 99.5%, it is determined that for the best value,
Owing to the distribution that Coin-shaped battery assembles in laboratory environments cannot be ignored, so being more than 98%
Time be also judged as good value.
It is in addition to the circulation in time carrying out formation process that 50CY-maintains, and followed by 0.5C follows
During ring, on the basis of the discharge capacity of the 1st circulation, represent putting when circulating the 50th time with %
It is worth obtained by the ratio of capacitance.
It can be found that 50CY-maintain ratio the highest, the gradient of battery life closer to level,
When the ratio that 50CY-maintains is less than 90%, it is meant that circulation carries out middle generation and deteriorates and appearance of discharging
Amount reduces.The ratio that have also appeared 50CY-maintenance in section Example is higher than the situation of 100%,
But judge that this is owing to the underway life-span deteriorates hardly, demonstrate the most additionally by
The silicon particle of activation.
It is to represent the thickness relative to initial stage pole plate of the thickness after 50 circulations with % that 50CY-expands
It is worth obtained by value added.The assay method that 50CY-expands following detailed description.
First, the thickness of initial stage collector body is measured.Thereafter cut in order to be assembled into Coin-shaped battery
Cut after the pole plate of conglobate state utilizes micrometer to measure its thickness, deduct collector body thickness and
Calculate the thickness of only active substance.
Then, after 50 loop tests terminate, from hothouse, Coin-shaped battery is disintegrated,
After only isolating negative plates, DEC solution is utilized to clean the electrolyte residuing in pole plate, dry
Utilize micrometer to measure thickness after dry, deduct the thickness of collector body and calculate the active substance after circulation
Thickness.That is, after circulating 50 times, the thickness of active substance is relative to the thickness of initial activity material
Degree value added divided by initial activity material thickness and with percent represent obtained by value be
50CY-expands.
[embodiment 2]
Following table 3 and table 4 show this to the experiment of the proportion for confirming Ti Yu Fe
The 1CY-discharge and recharge of inventive embodiment and comparative example, 1CY-efficiency, 1CY-pole plate capacity,
50CY-discharge capacity, 50CY-efficiency, 50CY-capacity dimension holdup.The technology of projects of table 4
Implication is described above.
Table 3 is in order to confirm the proportion of Ti Yu Fe, it is shown that embodiments of the invention and comparing
The compositing range of example.The at% of other material etc. in addition to Ti, Fe is fixed and carries out, and
Only the ratio of Ti with Fe is changed and tested.
According to Table 3 below, the ratio of Ti Yu Fe is preferably the scope of 2:1～1:2, further preferably
Ratio for 1:1.Maintain the embodiment that ratio is 2:1～1:2 scope 6～8 display of Ti Yu Fe
Going out capacity dimension holdup all up to more than 90%, the embodiment 7 as the ratio of 1:1 is 96.4%,
Demonstrate the highest capacity dimension holdup.On the other hand, for the ratio of Ti Yu Fe departing from
For comparative example 4 that the scope of 2:1～1:2 is formed and comparative example 5, capacity dimension holdup is 51.2%,
81.3%, relatively low.Therefore, in an embodiment of the present invention, in order to make battery performance maximize,
The ratio of Ti Yu Fe is maintained in the range of 2:1～1:2, most preferably controls the ratio at 1:1.
Table 3
[table 3]
| Distinguish | Si | Ti | Fe | Al |
| Comparative example 4 | Fixing | 15 | 7 | 5 |
| Comparative example 5 | Fixing | 7 | 15 | 5 |
| Embodiment 6 | Fixing | 13 | 9 | 5 |
| Embodiment 7 | Fixing | 11 | 11 | 5 |
| Embodiment 8 | Fixing | 9 | 13 5 |
Table 4
As it has been described above, the people of the Conventional wisdom having in the technical field belonging to the present invention it will be appreciated that
Even if the present invention does not change its technological thought, necessary feature also is able to enter in other concrete mode
Row is implemented.It is therefore understood that above-described embodiment etc. in terms of all from the point of view of be exemplary, and
Indefiniteness.It addition, the scope of the present invention is represented by claims described later, and not
Represented by above-mentioned detailed description, it should be construed to the implication of claims and scope and by
Mode after all changes of its equivalents derivation or modification is all contained in the scope of the present invention.
Claims (12)
1. a negative-electrode active material for secondary battery, it is characterised in that as by following chemistry
The alloy that formula is constituted, the decrystallized degree in alloy endobasal-body shape fine crystal region is more than 25%,
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: more than 0.01 and less than 0.2.
Negative-electrode active material for secondary battery the most according to claim 1, it is characterised in that
Expansion rate after 50 circulations of described negative electrode active material is in the range of 70～150%.
Negative-electrode active material for secondary battery the most according to claim 1, it is characterised in that
In described negative-electrode active material for secondary battery, in terms of atom % i.e. at%, Al is 5～19%
Scope.
Negative-electrode active material for secondary battery the most according to claim 3, it is characterised in that
In described negative-electrode active material for secondary battery, in terms of atom % i.e. at%, Al is 10～19%
Scope.
Negative-electrode active material for secondary battery the most according to claim 1, it is characterised in that
In described negative-electrode active material for secondary battery, in terms of atom % i.e. at%, Ti and Fe has respectively
There is the scope of 9～12.5%.
Negative-electrode active material for secondary battery the most according to claim 1, it is characterised in that
In described negative-electrode active material for secondary battery, the ratio of Ti Yu Fe has the scope of 2:1～1:2.
Negative-electrode active material for secondary battery the most according to claim 6, it is characterised in that
In described negative-electrode active material for secondary battery, the ratio of Ti Yu Fe is 1:1.
Negative-electrode active material for secondary battery the most according to claim 1, it is characterised in that
Discharge capacity after 50 circulations of described negative-electrode active material for secondary battery was put relative to the initial stage
Capacitance is more than 90%.
Negative-electrode active material for secondary battery the most according to claim 1, it is characterised in that
Efficiency after 50 circulations of described negative-electrode active material for secondary battery is more than 98%.
10. a secondary cell, it is characterised in that containing negative pole, positive pole and electrolyte, institute
State negative pole and contain the negative electrode active material according to any one of claim 1～9.
11. secondary cells according to claim 10, it is characterised in that described negative pole is by such as
Under negative electrode active material constitute:
Expansion rate after 50 circulations is 70～150%,
For the alloy being made up of following chemical formula, alloy endobasal-body shape fine crystal region decrystallized
Degree has the scope of more than 25%,
In terms of atom % i.e. at%, have Si:60～70%, Ti:9～14%, Fe:9～14%,
The scope of Al:5～19%,
SixTiyFezAlu, wherein, x, y, z, u in terms of atom % i.e. at%, x:1-(y+
Z+u), y:0.09～0.14, z:0.09～0.14, u:0.05～0.19.
12. secondary cells according to claim 11, it is characterised in that containing described Ti
There is the negative pole of the scope of 2:1～1:2 with the ratio of Fe.
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| KR1020140165114A KR20160062774A (en) | 2014-11-25 | 2014-11-25 | Negative active material for secondary battery and the secondary battery comprising the same |
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| CN110121802A (en) * | 2016-12-21 | 2019-08-13 | 日进电气有限公司 | Negative electrode active material for secondary cell and the secondary cell including the material |
| CN110199427A (en) * | 2017-01-06 | 2019-09-03 | 学校法人早稻田大学 | Secondary cell |
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| KR102323025B1 (en) | 2015-02-26 | 2021-11-10 | 일진전기 주식회사 | Negative electrode plate for secondary battery and secondary battery comprising the same |
| EP3293802B1 (en) * | 2015-09-14 | 2020-10-21 | Toyota Jidosha Kabushiki Kaisha | Method of manufacturing an all-solid-state battery system |
| 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 |
| 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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| 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 |
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| 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 |
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