CN107863497A - Lithium ion battery silicon cathode material and its preparation method and application - Google Patents
Lithium ion battery silicon cathode material and its preparation method and application Download PDFInfo
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Abstract
The invention provides a kind of lithium ion battery silicon cathode material, including silicon-based anode active material, graphite cathode active material, conductive agent and binding agent, wherein, the conductive agent is made up of conductive agent A and conductive agent B, the conductive agent A is point-like conductive agent or planar conductive agent, and the conductive agent B is draw ratio ＞ 120 conductive material；The binding agent is made up of binding agent A and binding agent B, and the binding agent A is hydroxymethyl cellulose salt, and the binding agent B is the binding agent containing carboxyl functional group in molecular structure.
Description
Technical field
The invention belongs to field of lithium ion battery, more particularly to a kind of lithium ion battery silicon cathode material and preparation method thereof
And application.
Background technology
In recent years, with the extensive use and fast development of electric automobile, to the demand of dynamical system-electrokinetic cell drastically
Increase, lithium ion battery is with the excellent property such as its high power capacity, high voltage, high circulation stability, high-energy-density, non-environmental-pollution
It can gain great popularity.In order that lithium ion battery meets the demand of the development of electric automobile, its energy density needs lasting lifting.Lithium
Ion battery is the energy storage and conversion equipment commonly used in the modern life, and the development of regenerative resource and electric automobile is to next
Higher and higher requirement is proposed for the energy density of lithium ion battery.
In order to improve the energy density of lithium ion battery, it is necessary to develop high power capacity, the negative material of long-life, silicon (Si)
Theory storage lithium specific capacity be 4200mAh/g, it is all can alloying store up lithium element in, the specific capacity of silicon is highest.
At room temperature, each silicon atom can at most combine 3.75 lithium atoms, obtain Li15Si4Alloy phase, corresponding actual storage lithium specific capacity
10 times of up to 3579mAh/g, about graphite theoretical specific capacity (372mAh/g), it is the novel negative of most potential substitution graphite
Pole material.However, Si charge and discharge process is along with huge bulk effect, volumetric expansion has reached more than 300%, so huge
Big bulk effect can cause strong mechanical stress, cause the efflorescence of material granule and breaking for electrode interior conductive network
It is bad, cause to lose contacting between electrode active material and collector, cause the rapid decay of electrode reversible capacity, cycle life contracting
It is short.In recent years, a kind of emerging silica negative material SiOx(0<x<2) start to be used for lithium ion battery negative material, and show
Go out advantage：The introducing of oxygen can generate inert component in embedding lithium first, advantageously reduce absolute body of the silicon during removal lithium embedded
Product change.Meanwhile silica-base material nanosizing can be reduced to the Volumetric expansion of silica-base material to a certain extent, lift material
The cyclical stability of material.Above method, it can effectively improve the initial volume effect problem of silica-base material, but cyclic process
In, silicon crystal highly Li insertion extraction repeatedly, bulk effect is increasingly severe, while repeatedly nano silica-base material particle after circulation
Reunion can also occur between particle to be sticked together, silicon-based anode drastically expands after both collective effects cause circulation, so as to
Cause the destruction of electrode structure, cause the serious of electrode to drop off efflorescence, cause the long-term cycle performance of silicon-based anode to deteriorate rapidly.
In addition, being directed to the problem of mentioned above in recent years, vast researcher and battery practitioner substantially surrounds silicon substrate
Material does improvement optimization in itself, and few made from pole piece discusses how that Cycle Difference caused by reduction silicon-based anode expansion is asked up
The solution of topic.
Therefore, at present there is an urgent need to develop a kind of technology, it can be effectively improved the circulation expansion of silicon-based anode pole piece and ask
Topic, ensure, good combination property excellent using the long-term cycle life of lithium ion battery of the silicon-based anode pole piece.
The content of the invention
It is an object of the invention to provide a kind of lithium ion battery silicon cathode material and preparation method thereof, it is intended to solves existing
Lithium ion battery silicon base negative electrode active material cyclic process in volumetric expansion it is serious, the problem of influenceing long-term cycle performance.
Another object of the present invention is to provide a kind of lithium ion battery containing above-mentioned lithium ion battery silicon cathode material
Silicon-based anode piece and preparation method thereof.
Another object of the present invention is to provide a kind of lithium ion battery containing above-mentioned lithium ion battery silicon cathode material.
The present invention is achieved in that one aspect of the present invention provides a kind of lithium ion battery silicon cathode material, including silicon
Base negative electrode active material, graphite cathode active material, conductive agent and binding agent, wherein, the conductive agent is by conductive agent A and conduction
Agent B is formed, and the conductive agent A is point-like conductive agent or planar conductive agent, and the conductive agent B is draw ratio ＞ 120 conduction material
Material；The binding agent is made up of binding agent A and binding agent B, and the binding agent A is hydroxymethyl cellulose salt, and the binding agent B is
Binding agent containing carboxyl functional group in molecular structure.
Preferably, the conductive agent A is at least one of conductive black, Ketjen black, electrically conductive graphite, graphene.
Preferably, the conductive agent B is at least one of CNT, carbon nano-fiber.
Preferably, the binding agent A is at least one of sodium cellulose glycolate, hydroxymethyl cellulose potassium.
Preferably, the binding agent B is at least one of polyacrylic acid, alginic acid, polyacrylonitrile.
Preferably, the silicon-based anode active material is at least one in the sub- silicon of oxidation, nano-silicon, silicon/carbon composite
Kind.
Preferably, the graphite cathode active material is native graphite, Delanium, carbonaceous mesophase spherules, soft carbon, hard carbon
At least one of.
Preferably, the mass ratio of the silicon-based anode active material and graphite cathode active material is：1-30:70-99；Institute
The addition for stating conductive agent is the 1-2% of negative active core-shell material gross mass；The addition of the binding agent is negative active core-shell material
The 3-5% of gross mass.
Another aspect of the present invention provides a kind of preparation method of lithium ion battery silicon cathode material, comprises the following steps：
Formula according to above-mentioned lithium ion battery silicon cathode material weighs each component；
Binding agent A is disperseed to form binding agent A glues, conductive agent A, conductive agent B are added in the binding agent A glues,
It is uniformly mixed so as to obtain conductive gelatin；
Silicon-based anode active material, graphite cathode active material are mixed and to form dry blend, in the dry blend successively
The conductive gelatin, binding agent B are added, lithium ion battery silicon cathode material is prepared.
Preferably, in the step of adding the conductive gelatin in the dry blend, the conductive gelatin is added in batches,
Method is as follows：
First adds 20-40% conductive gelatins, mixing processing；
Second batch adds 30-80% conductive gelatins, mixing processing；
3rd batch of addition 0-30% conductive gelatin, mixing processing.
Another aspect of the invention provides a kind of lithium ion battery silicon substrate negative plate, including negative current collector and is deposited on institute
The negative electrode material layer on negative current collector surface is stated, and the negative electrode material layer is made up of above-mentioned lithium ion battery silicon cathode material.
Further aspect of the present invention provides a kind of lithium ion battery, including negative plate, positive plate, barrier film, organic electrolyte
And shell, the negative plate includes collector and negative material, and the negative material is above-mentioned lithium ion battery silicium cathode material
Material.
Lithium ion battery silicon cathode material provided by the invention, using silicon-based anode active material as composite negative pole activity
Material, the specific capacity of lithium ion battery can be improved.But after the multiple charge and discharge electric expansion of silicon-based anode active material, can exist
Problems with：Contacted between the particle of negative active core-shell material and particle less, gap increasing, or even some depart from colelctor electrodes, cause
Electronics and the interrupted discontinuous phase of ion transmission path, turn into dead active material, can not participate in electrode reaction, therefore recycle
Life-span declines.
In view of this, the present invention is on the basis of using silicon-based anode active material, on the one hand, at the same it is conductive using point-like
Agent or planar conductive agent (conductive agent A), draw ratio ＞ 120 conductive material (conductive agent B) are used as conductive agent component.Wherein, institute
It is nanometer or micron-scale to state conductive agent A, can effectively be filled into after dilation in the intergranular gap of silica-base material, prevent
The efflorescence of material granule.And the conductive agent B has very big draw ratio, even if after silica-base material dilation, the conduction
Agent B is remained able in intergranular gap, is built bridge and connected by long-range, ensured the integrality of conductive structure, make electronics and ion
Transmission is uninterrupted.In addition, the conductive agent B can also increase the pliability of electrode, improve silicon-based anode active material and born with graphite
The gluing power between gluing power and negative material and collector between the active material of pole, will not acutely it fall because of circulation expansion
Powder.The present invention can cause the lithium ion using silicon-based anode active material by conductive agent A and conductive agent B synergy
Battery silicium cathode material (has higher specific capacity), even if more serious volumetric expansion be present, remains able to effectively
The efflorescence of material granule and the destruction of electrode interior conductive network are prevented, so as to improve the long-term cyclicity of lithium ion battery
Can so that lithium ion battery has excellent combination property.
On the other hand, binding agent of the present invention is made up of binding agent A and binding agent B, and the binding agent A is that methylol is fine
Plain salt is tieed up, the binding agent B is the binding agent containing carboxyl functional group in molecular structure.Wherein, the binding agent A can be effective
Disperse each material component, be uniformly dispersed, be not easy the cathode size that is layered；Carboxyl and silicon-based anode in the binding agent B
The hydroxyls dehydrate on active material particle surface is condensed to form covalent key connection, so as to ensure that each component in silicon-based anode electrode
Effectively closely bond, closely bonding has effectively fettered the expansion of silicon-based anode active material, helps to alleviate silicon-based anode
Capacity fading problem caused by the expansion of pole piece silicon-based anode active material.Further, since the binding agent A contains hydroxyl,
Dehydrating condensation can occur with the binding agent B, so as to promote binding agent A, binding agent B, silicon-based anode active material three jail
Gu crosslinking, has further fettered the expansion of silicon-based anode pole piece, has slowed down volumetric expansion.
Further, combined conductive agent (conductive agent A, conductive agent B) of the present invention and compound binding agent (binding agent A, glue
Knot agent B) between act synergistically.Specifically, the carboxyl of the binding agent B and the binding agent A hydroxyl, the silicon substrate are born
Dehydrating condensation effect occurs for the hydroxyl of pole active material, crosslinked together securely, so as to realize binding agent A and binding agent B associations
With the initial constraint effect to silicon based anode material.Further, on this basis, conductive agent A and conductive agent B are filled uniformly with
Arrive among silicon-based anode system, wherein, between conductive agent A is effectively filled between the particle of silicon based anode material and particle
In gap, the point-to-point or aspectant short distance electric action to silicon based anode material is realized；Conductive agent B long-ranges are built bridge and are connected to
In silicon based anode material, binding agent A, B system, the long range to circulating repeatedly the silicon based anode material after removal lithium embedded expands is realized
Electric action, meanwhile, conductive agent B draw ratios are big (i.e. length is longer), can preferably enwind silicon based anode material, binding agent body
System, ensure that silicon-based anode circulates repeatedly the structural stability of removal lithium embedded, reduce the circulation expansion rate of silicon-based anode.Thus, it is described
Combined conductive agent (conductive agent A, conductive agent B) and compound binding agent (binding agent A, binding agent B) synergy, form a stabilization
The filling network system, held onto the circulation expansion issues of silicon based anode material jointly.
The preparation method of lithium ion battery silicon cathode material provided by the invention, conductive agent A and conductive agent B is added first
In the binding agent A aqueous solution, uniform conductive agent dispersion is formed, is added followed by silicon-based anode active material and binding agent
Dehydrating condensation effect occurs for the hydroxyl of B, binding agent B carboxyl and binding agent A hydroxyl, silicon-based anode active material, securely
It is crosslinked together, while among conductive agent A and conductive agent B have filled uniformly with silicon-based anode system, conductive agent A is effectively filled out
Be charged in the gap between the particle of silicon based anode material and particle, conductive agent B long-ranges build bridge be connected to silicon based anode material,
In binding agent A, B system.This method technique is simple, workable, is adapted to heavy industrialization batch production.
Lithium ion battery silicon substrate negative plate provided by the invention, the circulation expansion that can effectively improve silicon based electrode are asked
Topic, ensure the cycle life of lithium ion battery length that the silicon-based anode pole piece is applied, good combination property, when meeting that electrokinetic cell is long
Between application demand, be advantageous to improve cell production companies product market application foreground, be of great practical significance.
Lithium ion battery provided by the invention, negative plate contain above-mentioned lithium ion battery silicon cathode material, the circulating battery
Long lifespan, good combination property, there are wide market prospects.
Brief description of the drawings
Fig. 1 is the adhesion test result figure of embodiment 1,2 provided by the invention and comparative example 1,3,4；
Fig. 2 be embodiment 2 provided by the invention from the lithium ion battery prepared by comparative example 1,3,4 under different SOC states
Test carries out DC internal resistance test result figure；
Fig. 3 is the lithium ion battery normal temperature circulation test result figure of embodiment 2 provided by the invention and comparative example 1,4；
Fig. 4 is the expansion rate comparison diagram of battery core before and after embodiment 2 provided by the invention circulates with comparative example 1,4.
Embodiment
In order that technical problems, technical solutions and advantageous effects to be solved by the present invention are more clearly understood, below in conjunction with
Embodiment, the present invention will be described in further detail.It should be appreciated that specific embodiment described herein is only explaining
The present invention, it is not intended to limit the present invention.
The embodiments of the invention provide a kind of lithium ion battery silicon cathode material, including silicon-based anode active material, graphite
Negative active core-shell material, conductive agent and binding agent, wherein, the conductive agent is made up of conductive agent A and conductive agent B, the conductive agent A
For point-like conductive agent or planar conductive agent, the conductive agent B is draw ratio ＞ 120 conductive material；The binding agent is by bonding
Agent A and binding agent B compositions, the binding agent A are hydroxymethyl cellulose salt, and the binding agent B is to contain carboxyl in molecular structure
The binding agent of functional group.
Lithium ion battery silicon cathode material provided in an embodiment of the present invention, using silicon-based anode active material as Compound Negative
Pole active material, the specific capacity of lithium ion battery can be improved.But after the multiple charge and discharge electric expansion of silicon-based anode active material,
There can be problems with：Contacted between the particle of negative active core-shell material and particle less, gap increasing, or even some depart from current collections
Pole, cause electronics and the interrupted discontinuous phase of ion transmission path, turn into dead active material, electrode reaction can not be participated in, therefore
Service life cycle declines.
In view of this, the embodiment of the present invention is on the basis of using silicon-based anode active material, on the one hand, while use point
Shape conductive agent or planar conductive agent (conductive agent A), draw ratio ＞ 120 conductive material (conductive agent B) are used as conductive agent component.Its
In, the conductive agent A is nanometer or micron-scale, can effectively be filled into the intergranular gap of silica-base material after dilation
In, prevent the efflorescence of material granule.And the conductive agent B has very big draw ratio, even if after silica-base material dilation, institute
State conductive agent B to remain able in intergranular gap, built bridge and connected by long-range, ensured the integrality of conductive structure, make electronics
It is uninterrupted with ion transmission.In addition, the conductive agent B can also increase the pliability of electrode, improve silicon-based anode active material with
The gluing power between gluing power and negative material and collector between graphite cathode active material, will not because circulation expansion and
Violent dry linting.The embodiment of the present invention can be caused using silicon-based anode activity by conductive agent A and conductive agent B synergy
The lithium ion battery silicon cathode material (there is higher specific capacity) of material, even if more serious volumetric expansion be present,
Remain able to effectively prevent the efflorescence of material granule and the destruction of electrode interior conductive network, so as to improve lithium ion battery
Long-term cycle performance so that lithium ion battery has excellent combination property.
On the other hand, binding agent described in the embodiment of the present invention is made up of binding agent A and binding agent B, and the binding agent A is hydroxyl
Methylcellulose salt, the binding agent B are the binding agent containing carboxyl functional group in molecular structure.Wherein, the binding agent A energy
It is enough effectively to disperse each material component, it is uniformly dispersed, is not easy the cathode size that is layered；Carboxyl and silicon in the binding agent B
The hydroxyls dehydrate of base negative electrode active material particle surface is condensed to form covalent key connection, each in silicon-based anode electrode so as to ensure that
Component effectively closely bonds, and closely bonding has effectively fettered the expansion of silicon-based anode pole piece, contributes to alleviation silicon substrate to bear
Capacity fading problem caused by the pole piece silica-base material expansion of pole.Further, since the binding agent A contains hydroxyl, Neng Gouyu
Dehydrating condensation occurs for the binding agent B, so as to promote binding agent A, binding agent B, silicon-based anode active material three to be firmly crosslinked,
The expansion of silicon-based anode pole piece has further been fettered, has slowed down volumetric expansion.
Further, combined conductive agent described in the embodiment of the present invention (conductive agent A, conductive agent B) and compound binding agent (bond
Agent A, binding agent B) between act synergistically.Specifically, the carboxyl of the binding agent B and the binding agent A hydroxyl, described
Dehydrating condensation effect occurs for the hydroxyl of silicon-based anode active material, crosslinked together securely, so as to realize binding agent A and bonding
Initial constraint effect of the agent B collaborations to silicon based anode material.Further, on this basis, conductive agent A and conductive agent B are uniform
Ground has been filled among silicon-based anode system, wherein, conductive agent A be effectively filled into the particle of silicon based anode material and particle it
Between gap in, realize the point-to-point or aspectant short distance electric action to silicon based anode material；Conductive agent B long-ranges are built bridge
It is connected in silicon based anode material, binding agent A, B system, realizes to circulating repeatedly the silicon based anode material after removal lithium embedded expands
Long range electric action, meanwhile, conductive agent B draw ratios are big (i.e. length is longer), can preferably enwind silicon based anode material, glue
Agent system is tied, ensures that silicon-based anode circulates repeatedly the structural stability of removal lithium embedded, reduces the circulation expansion rate of silicon-based anode.By
This, the combined conductive agent (conductive agent A, conductive agent B) and compound binding agent (binding agent A, binding agent B) synergy, forms
One stable filling network system, has held onto the circulation expansion issues of silicon based anode material jointly.
In the embodiment of the present invention, the active material of lithium ion battery silicon cathode material includes the high silicon-based anode of specific capacity and lived
Property material, but because the expansion of silicon-based anode active material volume is obvious, and the particle diameter of silicon-based anode active material is meticulous, individually adopts
During by the use of silicon-based anode active material as negative active core-shell material, serious volumetric expansion problem can be not only produced, and obtain
Cathode size is easily settled, is layered, and is unfavorable for negative material uniform deposition on negative current collector.In view of this, the present invention is real
Example is applied to live as composite anode active material, the graphite cathode using silicon-based anode active material, graphite cathode active material
Property material addition, the volumetric expansion in charge and discharge process can be reduced to a certain degree, on the other hand, due to graphite cathode activity
The particle diameter of material is big compared with silicon-based anode active material particle diameter, therefore, after dispersion mixing, is advantageous to obtain uniform negative pole material
Slurry material.
Specifically, the silicon-based anode active material includes but is not limited to aoxidize sub- silicon, nano-silicon, silicon/carbon composite
At least one of.The graphite cathode active material include but is not limited to native graphite, Delanium, carbonaceous mesophase spherules,
At least one of soft carbon, hard carbon.
Further, counted using the gross mass of the negative active core-shell material as 100%, the matter of the silicon-based anode active material
Amount percentage composition is 1-30%, and the weight/mass percentage composition of the graphite cathode active material is 70-99%, i.e.,：The silicon substrate is born
The mass ratio of pole active material and graphite cathode active material is：1-30:70-99.Suitable ratio, discharge and recharge can be reduced
Volumetric expansion in journey, and obtain uniform negative material slurry.
The embodiment of the present invention is drawn simultaneously in order to solve the problems, such as the volumetric expansion in silicon-based anode active material charge and discharge process
NEW TYPE OF COMPOSITE conductive agent and NEW TYPE OF COMPOSITE binding agent are entered.
Preferably, the conductive agent A is at least one of conductive black, Ketjen black, electrically conductive graphite, graphene.It is preferred that
Conductive agent A, not only electric conductivity is preferable, and because the conductive black, Ketjen black are nanometer or micron conductive particle, institute
It is nano-dotted or micron flakes conductive material to state electrically conductive graphite, and the graphene is nano-sheet conductive material, is advantageous to fill out
It is charged to after dilation in the intergranular gap of silica-base material, prevents the efflorescence of material granule.It is specific preferable, the conductive charcoal
Model ECP Ketjen black may be selected in black optional model SP conductive black, the Ketjen black, and the electrically conductive graphite is optional
Model KS-6 electrically conductive graphite is selected, but is not limited to this.
Preferably, the conductive agent B is at least one of CNT, carbon nano-fiber.Preferable conductive agent B, leads to
Cross long-range bridge company to connect, ensure the integrality of conductive structure, even if after silica-base material expands contraction, remain able to ensure
Electronics and the continuity of ion transmission.In addition, the conductive agent B and conductive agent A is used in combination, conductive agent A can be filled in and lead
In the conductive network that electric agent B is formed, the stability of conductive system is further increased, is advantageous to improve the electric conductivity of negative material
And stability.It is further preferred that the caliber ＜ 30nm of the conductive agent B, so as to ensure conductive structure integrality
Under the premise of, reduce the dosage of conductive agent.
Further, the addition of the conductive agent is the 1-2% of negative active core-shell material gross mass.Preferably, it is described to lead
Electric agent A and the conductive agent B ratio meet：The quality dosage of the conductive agent B is preferably the 1/20~1/ of the conductive agent A
8.Due to the conductive material such as carbon nano-tube material that the conductive agent B is draw ratio ＞ 120, there is good electric conductivity (its
Conductive capability is about 100 times of conductive agent A such as conductive agent SP), dosage without that can reach good conductive agent effect too much；Together
When, the conductive agent B is nano material, and its specific surface area is very big (for 3~10 times of conductive agent SP), from absorption and keeps electricity
Solve in terms of liquid, its dosage is without too many.If on the contrary, conductive agent B such as carbon nanometers in lithium ion battery silicon cathode size
The addition of pipe conductive agent is excessive, and its specific surface area is excessive, can increase the dispersed difficulty of slurry on the contrary, and then too greatly increase
The specific surface area of final negative pole is added, has caused to reduce using the discharge capacity first of the battery of the silicon-based anode and high-temperature behavior can
Deterioration can occur, and (the ratio surface because of negative material is excessive, negative plate and electrolyte under the side reaction of initial charge film forming and high temperature
Side reaction increase).
Binding agent of embodiment of the present invention A and binding agent B must be used simultaneously, could on the premise of machinability is ensured,
Effectively alleviate Capacity fading problem caused by the expansion of silicon-based anode active material in silicon-based anode pole piece.Further, institute
The addition for stating binding agent is the 3-5% of negative active core-shell material gross mass.
Preferably, the binding agent A be sodium cellulose glycolate, hydroxymethyl cellulose potassium CMC-Na, CMC-K) in extremely
Few one kind.Preferable binding agent A contributes to the silicon-based anode active material, graphite cathode active material, conductive agent A, conduction
Agent B, binding agent it is dispersed, so as to beneficial to obtain uniform deposition collection liquid surface negative electrode material layer.But light uses viscous
Agent A lithium ion battery silicon cathode material is tied, adhesive property is inadequate, it is impossible to effectively fetter silicon-based anode active material, slow down body
Product expansion.
Preferably, the binding agent B is at least one of polyacrylic acid, alginic acid, polyacrylonitrile.Preferable binding agent
B, preferable reactivity is respectively provided with the silicon-based anode active material, the binding agent A, is advantageous to by dehydrating condensation shape
Into firm cross-linking agent, mitigate the volumetric expansion of silicon-based anode active material in charge and discharge process.
Preferably, the binding agent A and binding agent B quality usage ratio is 1:(0.8-1.2), more preferably 1：1.Such as
Fruit binding agent A is excessively that binding agent B is very few, then the adhesion of silicon-based anode piece can be affected, it is impossible to ensures silicon-based anode electricity
Extremely middle each component effectively closely bonds；If the very few i.e. binding agent B of binding agent A are excessive, silicon-based anode slurry is difficult to uniformly
Scattered, slurry is also easy to produce lamination.Lithium ion battery silicon cathode material provided in an embodiment of the present invention, following sides can be passed through
Method prepares.
Accordingly, the embodiments of the invention provide a kind of preparation method of lithium ion battery silicon cathode material, including it is following
Step：
S01. each component is weighed according to the formula of above-mentioned lithium ion battery silicon cathode material；
S02. binding agent A is disperseed to form binding agent A glues, conductive agent A, conduction is added in the binding agent A glues
Agent B, is uniformly mixed so as to obtain conductive gelatin；
S03. silicon-based anode active material, graphite cathode active material are mixed and forms dry blend, in the dry blend
The conductive gelatin, binding agent B are sequentially added, lithium ion battery silicon cathode material is prepared.
The preparation method of lithium ion battery silicon cathode material provided in an embodiment of the present invention, method technique is simple, operable
Property it is strong, be adapted to heavy industrialization batch production.
Specifically, in above-mentioned steps S01, the formula of lithium ion battery silicon cathode material is formed as described above, in order to save
Length, here is omitted.
In above-mentioned steps S02, binding agent A is disperseed to form binding agent A glues, specifically, deionized water conduct can be used
Decentralized medium, it is preferred that the binding agent A glues solid content be 1.4~5%, be advantageous to conductive agent A, conductive agent B addition and
It is scattered.Binding agent A can be uniformly dispersed by the embodiment of the present invention by stir process, it is preferred that and stirring condition is preferably 300~
1200rpm mixing speed stirs 3~12 hours.
The embodiment of the present invention adds conductive agent A, conductive agent B in the binding agent A glues, can become the addition of stirring side,
It can also be dispersed with stirring after addition terminates.Preferably, stirring condition is to be stirred under 1200~3800rpm mixing speed
Mix 0.5~3 hour.
In above-mentioned steps S03, it is preferred that in the step of adding the conductive gelatin in the dry blend, add in batches
Enter the conductive gelatin, method is as follows：
First adds 20-40% conductive gelatins, mixing processing；
Second batch adds 30-80% conductive gelatins, mixing processing；
3rd batch of addition 0-30% conductive gelatin, mixing processing.
Conductive gelatin is added by two to three steps, and rationally controls the amount of the conductive gelatin of addition, is advantageous to improve slurry
Dispersing uniformity, be advantageous to layout and form stable conductive network.Specifically, mixing processing is preferably realized using stirring, tool
Body is preferable, and after first adds conductive gelatin, mixing processing is carried out with 200~1200rpm mixing speed；Second batch adds
After conductive gelatin, mixing processing is carried out with 1200~3000rpm mixing speed；After 3rd batch adds conductive gelatin, with 2400
~4000rpm mixing speed carries out mixing processing.
The embodiment of the present invention adds binding agent B and stirred, can add deionized water simultaneously after conductive gelatin has been added
It is adjusted, stirring condition is preferably that 800~1200rpm is stirred 0.5~1 hour.Finally adjust slurry solid content to 40~
55%, slurry is filtered with 100~200 eye mesh screens, except obtaining lithium ion battery silicon substrate cathode size after magnetic.
Present invention also offers a kind of lithium ion battery silicon substrate negative plate, including negative current collector and it is deposited on the negative pole
The negative electrode material layer of collection liquid surface, and the negative electrode material layer is made up of above-mentioned lithium ion battery silicon cathode material.
Lithium ion battery silicon substrate negative plate provided in an embodiment of the present invention, the circulation that can effectively improve silicon based electrode are swollen
Swollen problem, ensure the cycle life of lithium ion battery length that the silicon-based anode pole piece is applied, good combination property, meet electrokinetic cell
Long-time application demand, be advantageous to improve the market application foreground of cell production companies product, there are great production practices to anticipate
Justice.
Wherein, it is preferred that the negative current collector is the copper foil that copper foil or surface have conductive carbon coating, by copper
Conductive carbon coating is set on paper tinsel, is advantageous to improve the electric conductivity of negative plate.Specifically, the thickness of the negative current collector can be
5~18 μm, the conductive carbon coating that the copper foil surface has can be at least one using conductive black, electrically conductive graphite, but
Not limited to this.
The preparation method of lithium ion battery silicon substrate negative plate described in the embodiment of the present invention, the lithium that the above method can be prepared
Ion battery silicon-based anode slurry, negative current collector surface is coated on, then after drying water removal, roll-in, obtains lithium ion battery
Silicon-based anode piece.Specific preferable, coated face density is 10~30mg/cm2, coating baking drying temperature can be 60~110
DEG C, pole piece roll-in compacted density can be 1.2~1.8g/cm3。
The embodiment of the present invention additionally provides a kind of lithium ion battery, including negative plate, positive plate, barrier film, organic electrolyte
And shell, the negative plate includes collector and negative material, and the negative material is above-mentioned lithium ion battery silicium cathode material
Material.
Lithium ion battery provided in an embodiment of the present invention, negative plate contain above-mentioned lithium ion battery silicon cathode material, the electricity
Pond has extended cycle life, good combination property, has wide market prospects.
Specifically, the electrolyte can be the polyesters solution containing lithium salts, or other nonaqueous electrolytic solutions.Its
In, the polyesters can be dimethyl carbonate (DMC), and the lithium salts can be lithium hexafluoro phosphate (LiPF6)。
The anode pole piece includes plus plate current-collecting body and the positive electrode being coated on the plus plate current-collecting body (containing just
Pole active material).Wherein, the plus plate current-collecting body can be aluminium foil, and the thickness of the plus plate current-collecting body can be that 12-15 is micro-
Rice；The positive electrode can be in nickel-cobalt-manganese ternary material, nickel cobalt aluminium ternary material, cobalt acid lithium, LiFePO4, LiMn2O4
It is one or more of.
The barrier film can be PE films, PP films or PP/PE/PE films.
Illustrated with reference to specific embodiment.
Embodiment 1
A kind of lithium ion battery silicon substrate negative plate, including negative current collector and the lithium that is deposited on the negative current collector from
Sub- battery silicium cathode material, the lithium ion battery silicon cathode material includes 350g silicon-based anodes active material, 2150g graphite is born
Pole active material, 37.5g conductive agents and 70g binding agents, wherein, the conductive agent is made up of conductive agent A and conductive agent B, described
Conductive agent A is conductive black SP, and the conductive agent B is draw ratio ＞ 120 CNT；The binding agent by binding agent A and
Binding agent B is formed, and the binding agent A is sodium cellulose glycolate (CMC-Na), and the binding agent B bonds for polyacrylate
Agent.
The preparation method of the lithium ion battery silicon substrate negative plate, comprises the following steps：
35g sodium cellulose glycolates powder is added in ionized water, it is 1.4% to be formulated to glue content, with stirring for 1000rpm
Mix speed to stir 3 hours, obtain CMC glues；25g conductive black SP and 12.5g CNTs are added in CMC glues again,
It is stirred under 3000rpm mixing speed 2 hours, obtains conductive gelatin.
350g silica-base materials are aoxidized into sub- silicon and the dry-mixed stirring of 2150g graphite material Delanium physics, with 80rpm speed
Degree stirring 1 hour；After well mixed, point three steps add above-mentioned conductive gelatin thereto：The first step adds 30% conductive gelatin, adds
Stirred 1 hour with 800rpm mixing speed after entering, second step adds 40% conductive gelatin, with 2400rpm stirring after addition
Speed stirs 1 hour, and the 3rd step adds 30% conductive gelatin, is stirred 2 hours with 3500rpm after addition.It is subsequently added into 35g poly- third
Olefin(e) acid ester binding agent and 250g deionized waters stir, and are stirred 1 hour with 800rpm mixing speed；Finally, gained is starched
Material is filtered with 150 eye mesh screens, except obtaining the lithium ion battery silicon substrate cathode size after magnetic.
The silicon-based anode slurry is coated on 8 μm of copper foil surfaces of negative current collector, then after drying water removal, roll-in, obtained
Obtain lithium ion battery silicon substrate cathode pole piece.Wherein, it is 21mg/cm to be coated with two-sided surface density2, coating 80 DEG C of drying temperature of baking,
Pole piece roll-in compacted density 1.65g/cm3。
A kind of preparation method of lithium ion battery, comprises the following steps：
(1) above-mentioned silicon-based anode pole piece is cut and tab welding, cuts the bar shaped pole piece for 59mm width.
(2) nickel cobalt aluminium tertiary cathode material, conductive black, binding agent PVDF are mixed to join n-methlpyrrolidone
In, it is dispersed with stirring and uniformly prepares anode sizing agent；Gained anode sizing agent is coated on 15 μm of aluminium foil surfaces of plus plate current-collecting body, then through dry
After water removal, roll-in, cutting and soldering polar ear, lithium ion anode pole piece is obtained.Wherein, it is 50mg/cm to be coated with two-sided surface density2,
Coating 110 DEG C of drying temperature of baking, pole piece roll-in compacted density 3.5g/cm3, pole piece cutting width is 58mm.
(3) positive plate of the negative plate of above-mentioned (1) step and (2) step is separated with polyethylene diagrams PE films, with circle
Volume pin is wound, and last winding pole group is put into 18650 box hats, is assembled (negative electrode lug foot, slot rolling, welding cap cap), dry
Electrolyte 5.6g is injected in dry case, is then sealed, 18650 lithium ion batteries are made.
(4) battery is finally subjected to usual manner chemical conversion, aging, partial volume, that is, obtains lithium ion battery.
Embodiment 2
A kind of lithium ion battery silicon substrate negative plate, including negative current collector and the lithium that is deposited on the negative current collector from
It is artificial that sub- battery silicium cathode material, the lithium ion battery silicon cathode material, including 350g silica-base materials aoxidize sub- silicon, 2150g
Graphite, 37.5g conductive agents and 70g binding agents, wherein, the conductive agent is made up of conductive agent A and conductive agent B, the conductive agent A
For conductive black SP and graphene, the conductive agent B is draw ratio ＞ 120 CNT；The binding agent by binding agent A and
Binding agent B is formed, and the binding agent A is sodium cellulose glycolate, and the binding agent B is polyacrylate binder.
The preparation method of the lithium ion battery silicon substrate negative plate, comprises the following steps：
35g sodium cellulose glycolates powder is added in ionized water, it is 1.4% to be formulated to glue content, with stirring for 1000rpm
Mix speed to stir 3 hours, obtain CMC glues；Again by 25g conductive blacks SP and, 5g graphenes and 7.5g CNTs be added to
In CMC glues, it is stirred under 3000rpm mixing speed 3 hours, obtains conductive gelatin.
350g silica-base materials are aoxidized into sub- silicon and the dry-mixed stirring of 2150g graphite material Delanium physics, with 80rpm speed
Degree stirring 1 hour；After well mixed, point three steps add above-mentioned conductive gelatin thereto：The first step adds 35% conductive gelatin, adds
Stirred 1 hour with 800rpm mixing speed after entering, second step adds 35% conductive gelatin, with 2400rpm stirring after addition
Speed stirs 1 hour, and the 3rd step adds 30% conductive gelatin, is stirred 2 hours with 3500rpm after addition.It is subsequently added into 35g poly- third
Olefin(e) acid ester binding agent and 250g deionized waters stir, and are stirred 1 hour with 800rpm mixing speed；Finally, gained is starched
Material is filtered with 150 eye mesh screens, except obtaining the lithium ion battery silicon substrate cathode size after magnetic.
The silicon-based anode slurry is coated on 8 μm of copper foil surfaces of negative current collector, then after drying water removal, roll-in, obtained
Obtain lithium ion battery silicon substrate cathode pole piece.Wherein, it is 21mg/cm to be coated with two-sided surface density2, coating 80 DEG C of drying temperature of baking,
Pole piece roll-in compacted density 1.65g/cm3。
A kind of preparation method of lithium ion battery, comprises the following steps：
(1) above-mentioned silicon-based anode pole piece is cut and tab welding, cuts the bar shaped pole piece for 59mm width.
(2) nickel cobalt aluminium tertiary cathode material, conductive black, binding agent PVDF are mixed to join n-methlpyrrolidone
In, it is dispersed with stirring and uniformly prepares anode sizing agent；Gained anode sizing agent is coated on 15 μm of aluminium foil surfaces of plus plate current-collecting body, then through dry
After water removal, roll-in, cutting and soldering polar ear, lithium ion anode pole piece is obtained.Wherein, it is 50mg/cm to be coated with two-sided surface density2,
Coating 110 DEG C of drying temperature of baking, pole piece roll-in compacted density 3.5g/cm3, pole piece cutting width is 58mm.
(3) positive plate of the negative plate of above-mentioned (1) step and (2) step is separated with polyethylene diagrams PE films, with circle
Volume pin is wound, and last winding pole group is put into 18650 box hats, is assembled (negative electrode lug foot, slot rolling, welding cap cap), dry
Electrolyte 5.6g is injected in dry case, is then sealed, 18650 lithium ion batteries are made.
(4) battery is finally subjected to usual manner chemical conversion, aging, partial volume, that is, obtains lithium ion battery.
Comparative example 1
A kind of lithium ion battery, it is with the difference of embodiment 1：Conductive agent is only 37.5g conductive blacks SP；Bond
Agent B is styrene butadiene rubber sbr.
Comparative example 2
A kind of lithium ion battery, it is with the difference of embodiment 1：Conductive agent is only 37.5g conductive blacks SP；Bond
Agent is only styrene butadiene rubber sbr.
Comparative example 3
A kind of lithium ion battery, it is with the difference of embodiment 1：Conductive agent is only 37.5g conductive blacks SP.
Comparative example 4
A kind of lithium ion battery, it is with the difference of embodiment 1：Binding agent B is styrene butadiene rubber sbr.
Comparative example 5
A kind of lithium ion battery, it is with the difference of embodiment 1：Binding agent is only styrene butadiene rubber sbr.
Interpretation of result：
Comparative example 2 and comparative example 5, because binding agent is only styrene butadiene rubber sbr, no sodium cellulose glycolate binding agent, hydroxyl
Sodium carboxymethylcellulose pyce binding agent has each material component of dispersed paste, is uniformly dispersed, is not easy the work of cathode size that is layered
With, and comparative example 2,5 can not prepare the not stratified cathode size stablized, can not incite somebody to action without without sodium cellulose glycolate binding agent
Material is coated, and final comparative example 2,5 can not obtain corresponding silicon-based anode piece.
The silicon-based anode piece and lithium ion battery that embodiment 1,2, comparative example 1,3,4 are obtained carry out performance test, test
Index and test result are as follows：(1) pole piece adhesion contrasts
By the silicon-based anode pole piece before embodiment 1 and the roll-in of comparative example 1,3,4, the roomy small pole pieces of 15cm length × 2cm are cut into,
Test adhesion, test result, as shown in Figure 1.(2) battery DC internal resistance contrasts
Embodiment 2 is tested from the lithium ion battery prepared by comparative example 1,3,4 under different SOC states and carries out DC internal resistance
Test, test result as shown in Fig. 2 be followed successively by the inner walkway result of embodiment 2,1,3,4 from left to right.Test condition, no
With under SOC states, 1C discharges 30 seconds.DC internal resistance calculates, DC internal resistance=(voltage before cell voltage-electric discharge in the 30th second)/1C electricity
Flow valuve, voltage unit V, current unit A.
(3) normal temperature circulation is tested
By battery 0.5C constant-current charges to 4.2V, 4.2V constant-voltage charges to cut-off current 0.01C, then constant current 1C are discharged to
2.5V, loop test 800 times or capability retention are less than 80%, and test is completed.Fig. 3 be embodiment 2 and comparative example 1,4 lithium from
Sub- battery normal temperature circulation test result.
(4) the full electric expansion rate test of silicon-based anode pole piece
By application different silicon-based anode pole pieces lithium ion battery it is fully charged after disassemble, with screw micrometer test silicon substrate bear
Pole pole piece thickness, using the thickness after silicon-based anode pole piece roll-in as initial silicon substrate cathode pole piece thickness, calculate silicon-based anode pole piece
Full electric expansion rate.Fig. 4 is that embodiment 2 and battery core after the fresh battery core (battery core after partial volume) and loop test of comparative example 1,4 are (above-mentioned
Battery core after Fig. 3 loop tests) it is fully charged after, disassemble battery, the full electric expansion rate contrast of different battery core silicon-based anode pole pieces of test
Figure.The fully charged condition of battery core, by battery 0.5C constant-current charges to 4.2V, 4.2V constant-voltage charges to cut-off current 0.01C.
As seen from Figure 1, silicon-based anode piece piece adhesion (embodiment 1,2) more conventional silicon that the embodiment of the present invention makes
Base negative plate (comparative example 1,3,4) adhesion has a distinct increment, and embodiment 1 lifts nearly 2 times compared with comparative example 1, and this mainly benefits
At 2 points：First, the big carbon nanotube conducting agent of the draw ratio used in present example can enwind silica-base material well
With graphite material, material is allowed to be completely embedded with storeroom；Second, the polyacrylate binder used in present example, is bonded
When the carboxyl (- COOH) on agent surface and the hydroxyl (- OH) on silica-base material surface are homogenized, occur dehydration condensation, binding agent with
Silica-base material covalent effect is bridged together, the bonding force between silicon based anode material is enhanced well, so as to improve silicon
The adhesion of base cathode pole piece.
As seen from Figure 2, the lithium ion battery (battery of embodiment 2) made using silica cathode pole piece of the present invention is not
It is low than comparative example (comparative example 1,3,4) with the DC internal resistance of SOC states.This is primarily due to, and the silicon substrate that the present invention makes is born
Pole piece adhesion is higher so that the silica-base material between pole piece contacts, expansion rate is low, and being contacted between the silica-base material in pole piece makes
Lithium ion transmits that resistance is small, speed is fast in pole piece when must discharge, and battery DC internal resistance effectively reduces.
The lithium ion battery of the embodiment of the present invention 2 shows preferable cycle performance, loop test as seen from Figure 3
Battery capacity conservation rate still has 81.5% after 800 weeks, and the cycle performance of comparative example is poor, and comparative example 1, which circulates 280 weeks capacity, protects
Holdup is just less than 80%, and comparative example 4 circulates 410 weeks capability retentions and is just less than 80%.
The silicon-based anode pole piece (embodiment 2) that as seen from Figure 4 prepared by the present invention is born than silicon substrate prepared by conventional method
Pole piece (comparative example 1,4) shows relatively low full electric expansion rate.Silicon-based anode piece prepared by the embodiment of the present invention 2, circulation 800
5% is just added relative to its fresh battery core expansion rate not circulated after week, expansion rate increases smaller.And the silicon substrate of comparative example 1
Negative plate, circulation 280 weeks add 12% relative to fresh battery core expansion rate of its no circulation, the silicon-based anode piece of comparative example 4,
Circulation adds 11% in 410 weeks relative to its fresh battery core expansion rate not circulated, and comparative example silicon-based anode piece expansion rate increases
It is very big.In addition, the full electric expansion rate contrast of the silicon-based anode piece of fresh battery core, it is also seen that the silicon of the embodiment of the present invention 2
Silicon-based anode piece prepared by the full more conventional method of electric expansion rate of base cathode pole piece is low, low compared with comparative example 4 compared with comparative example 1 low 12%
7%.
To sum up, as shown in loop test result figure 3, using the lithium ion of silicon based anode material of embodiment of the present invention making
Battery has extraordinary cycle performance.This is primarily due to the silicon-based anode pole piece that makes of the present invention, after multiple loop test
Pole piece expansion rate is also relatively low, and low expansion rate illustrates that the circulation expansion issues of the silica-base material in silicon-based anode pole piece are had
The solution of effect.In general, on the one hand, the CNT long-range conductive agent applied in silicon-based anode pole piece of the invention,
Gap caused by the dilation of silica-base material in cyclic process, can be built bridge connection by the big long-range conductive agent of draw ratio, ion
It will not be interrupted with electric transmission, while long-range (draw ratio is big) carbon pipe conduction agent material, add the flexibility of electrode so that
Gluing power between silicon based anode material and graphite material and the gluing power between collector are stronger, will not be violent because of circulation expansion
Dry linting.On the other hand, the hydroxyl of carboxyl and silicon based anode material particle surface in the polyacrylate binder that the present invention uses
Base, dehydrating condensation occurs and acts on forming covalent bond, is effectively guaranteed the close connection of each component in silicon based electrode, closely connects
The expansion for effectively having fettered pole piece is connect, therefore efficiently solves Capacity fading problem caused by silicon-based anode expansion.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, all essences in the present invention
All any modification, equivalent and improvement made within refreshing and principle etc., should be included in the scope of the protection.
Claims (10)
1. a kind of lithium ion battery silicon cathode material, it is characterised in that including silicon-based anode active material, graphite cathode activity material
Material, conductive agent and binding agent, wherein, the conductive agent is made up of conductive agent A and conductive agent B, and the conductive agent A is nanometer or micro-
The point-like conductive agent or planar conductive agent of meter ruler cun, the conductive agent B are draw ratio ＞ 120 conductive material；The binding agent
It is made up of binding agent A and binding agent B, the binding agent A is hydroxymethyl cellulose salt, and the binding agent B is to contain in molecular structure
There is the binding agent of carboxyl functional group.
2. lithium ion battery silicon cathode material as claimed in claim 1, it is characterised in that the conductive agent A be conductive black,
At least one of Ketjen black, electrically conductive graphite, graphene；And/or
The conductive agent B is at least one of CNT, carbon nano-fiber.
3. lithium ion battery silicon cathode material as claimed in claim 1, it is characterised in that the binding agent A is that methylol is fine
Tie up at least one of plain sodium, hydroxymethyl cellulose potassium；And/or
The binding agent B is at least one of polyacrylic acid, alginic acid, polyacrylonitrile.
4. the lithium ion battery silicon cathode material as described in claim any one of 1-3, it is characterised in that the silicon-based anode is lived
Property material to aoxidize at least one of sub- silicon, nano-silicon, silicon/carbon composite.
5. the lithium ion battery silicon cathode material as described in claim any one of 1-3, it is characterised in that the graphite cathode is lived
Property material be native graphite, Delanium, carbonaceous mesophase spherules, soft carbon, at least one of hard carbon.
6. the lithium ion battery silicon cathode material as described in claim any one of 1-3, it is characterised in that the silicon-based anode is lived
The mass ratio of property material and graphite cathode active material is：1-30:70-99；The addition of the conductive agent is negative electrode active material
Expect the 1-2% of gross mass；The addition of the binding agent is the 3-5% of negative active core-shell material gross mass.
7. a kind of preparation method of lithium ion battery silicon cathode material, it is characterised in that comprise the following steps：
Formula according to any one of the claim 1-6 lithium ion battery silicon cathode materials weighs each component；
Binding agent A is disperseed to form binding agent A glues, conductive agent A, conductive agent B are added in the binding agent A glues, is mixed
Obtain conductive gelatin；
Silicon-based anode active material, graphite cathode active material are mixed and to form dry blend, is sequentially added in the dry blend
The conductive gelatin, binding agent B, are prepared lithium ion battery silicon cathode material.
8. the preparation method of lithium ion battery silicon cathode material as claimed in claim 7, it is characterised in that in the dry blend
In the step of middle addition conductive gelatin, the conductive gelatin is added in batches, method is as follows：
First adds 20-40% conductive gelatins, mixing processing；
Second batch adds 30-80% conductive gelatins, mixing processing；
3rd batch of addition 0-30% conductive gelatin, mixing processing.
9. a kind of lithium ion battery silicon substrate negative plate, it is characterised in that including negative current collector and be deposited on the negative pole currect collecting
The negative electrode material layer in body surface face, and the negative electrode material layer is by any one of the claim 1-6 lithium ion battery silicium cathode materials
Material is made.
10. a kind of lithium ion battery, including negative plate, positive plate, barrier film, organic electrolyte and shell, it is characterised in that described
Negative plate includes collector and negative material, and the negative material is any one of the claim 1-6 lithium ion battery silicon
Negative material.
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