阅读说明：本技术 二次电池用负极及其制造方法 (Secondary battery cathode and its manufacturing method ) 是由 金荣宰 金帝映 于 2017-12-27 设计创作，主要内容包括：本发明涉及一种二次电池用负极及其制造方法,更特别地,涉及一种用于二次电池的负极的二次电池用负极以及其制造方法。根据本发明实施方式的二次电池用负极包含：碳系活性材料；导电材料；硅系活性材料-聚合物粘合剂结合体,其中用于抑制硅系活性材料膨胀的聚合物粘合剂结合至所述硅系活性材料的粒子表面；增稠剂；和水系粘合剂。(The present invention relates to a kind of secondary battery cathode and its manufacturing methods, more specifically it relates to the secondary battery cathode and its manufacturing method of a kind of cathode for secondary cell.The secondary battery cathode of embodiment includes according to the present invention: carbon system active material；Conductive material；Silicon systems active material-polymer adhesive combination, wherein the polymer adhesive for inhibiting silicon systems active material to expand is bound to the particle surface of the silicon systems active material；Thickener；And aqueous adhesive.)

1. a kind of secondary battery cathode, includes:

Carbon system active material；

Conductive material；

Silicon systems active material-polymer adhesive combination, comprising silicon systems active material and for inhibiting the silicon systems activity material Expect that the polymer adhesive of expansion, the polymer adhesive are bound to the particle surface of the silicon systems active material；With

Aqueous adhesive.

2. secondary battery cathode according to claim 1, wherein based on carbon system active material and the silicon is included It is the total weight of the active material of active material, the content of the silicon systems active material is 5 weight % to 25 weight %.

3. secondary battery cathode according to claim 1, wherein the weight based on the silicon systems active material, described poly- The content for closing object adhesive is 25 weight % to 45 weight %.

4. secondary battery cathode according to claim 1, wherein the polymer adhesive includes to have hydroxyl (- OH) Hydrophilic polymer material.

5. secondary battery cathode according to claim 1, wherein the polymer adhesive includes polyacrylic acid (PAA), at least one of polyvinyl alcohol (PVA) and Sodium Polyacrylate (Na-PA).

6. secondary battery cathode according to claim 1, wherein the weight based on the polymer adhesive, the water The content for being adhesive is 30 weight % to 40 weight %.

7. secondary battery cathode according to claim 1, wherein the aqueous adhesive includes rubber-based material.

8. secondary battery cathode according to claim 1, wherein the aqueous adhesive includes styrene butadiene rubber At least one of glue (SBR), acrylonitrile butadiene rubber, acrylic rubber, butyl rubber and fluorubber.

9. secondary battery cathode according to claim 1, until the 5th under conditions of 0.5C charging and 0.5C electric discharge Secondary circulation has 90% or more discharge capacitance.

10. a kind of method for manufacturing secondary battery cathode, comprising:

Prepare the process of carbon system active material；

Pre-dispersed slurry is prepared by a dispersion medium mixing silicon systems active material, conductive material and polymer adhesive Process；

The process that carbon system active material is mixed with the pre-dispersed slurry；

Negative electrode slurry is prepared by mixing aqueous adhesive with the mixture for being wherein mixed with carbon system active material Process；

The process prepared negative electrode slurry being applied on current-collector；With

The process for forming cathode by removing moisture from the negative electrode slurry.

11. according to the method described in claim 10, wherein the pre-dispersed slurry is by will the wherein silicon systems activity material Material and polymer adhesive silicon systems active material-polymer adhesive combination in conjunction with obtained by and the conduction material Material is dispersed and is formed.

12. according to the method described in claim 10, wherein the solid content of the pre-dispersed slurry is by described pre-dispersed The viscosity of slurry controls.

13. according to the method for claim 12, wherein the solid content of the pre-dispersed slurry is controlled, so that described pre- point Dissipate the viscosity that slurry has 3000cp to 10000cp.

14. according to the method described in claim 10, further include: it is mixed by carbon system active material and the pre-dispersed slurry After the process of conjunction, process that thickener is mixed with the mixture for being wherein mixed with carbon system active material.

15. according to the method described in claim 10, wherein by controlling the combined amount of the thickener, by the negative electrode slurry Control is the solid content that the total weight based on the negative electrode slurry has 40 weight % to 50 weight %.

Technical field

This disclosure relates to a kind of secondary battery cathode and its manufacturing methods, and more particularly, are related to a kind of use In the secondary battery cathode and its manufacturing method of the cathode of secondary cell.

Background technique

Recently, the concern of energy storage technology is increasingly increased.As application field extends to mobile phone, Portable image pickup Machine, the laptop even energy of electric vehicle increasingly embody the effort of the research and development of electrochemical appliance. In this respect, electrochemical appliance is at most paid close attention to, and particularly, the exploitation of rechargeable secondary batteries has become the coke of concern Point.Recently, when developing such battery, the research and development for designing new electrode and new battery has been carried out, for changing Kind capacity density and specific energy.

Among the secondary cell applied at present, lithium secondary battery such as uses the N- of aqueous electrolyte better than conventional batteries MH, Ni-Cd and the advantages of lead-sulphate battery, are that operating voltage is higher and its energy density is much bigger.

In general, in the lithium secondary battery, use can be embedded in either being capable of alloying and de- alloy with deintercalate lithium ions Change the material of lithium ion as cathode and anode, and organic bath or polymer dielectric are filled between cathode and anode To manufacture lithium secondary battery.When lithium ion is from anode and cathode insertion and deintercalation, generated by oxidation reaction and reduction reaction Electric energy.

Currently, carbon-based material is mainly used as constituting the electrode active material of the cathode of lithium secondary battery.The graphite the case where Under, theoretical capacity is about 372mAh/g, and the actual capacity realization of commercial graphite has arrived about 350mAh/g extremely at present The degree of 360mAh/g.However, the capacity of the carbon-based material of such as graphite is not suitable for needing high capacity negative electrode active material Lithium secondary battery.

In order to meet such requirement, there is the example for wherein using silicon systems material as negative electrode active material, the silicon Based material shows charging/discharging capacity more higher than carbon-based material, and being can be with lithium electrochemical alloyed metal (AM).So And such silicon systems material has high capacity, but has very high electrode expansion rate compared with carbon-based material, and has non- Often low charge/discharge efficiency, therefore have problems in that the silicon systems material for being difficult to that large scale is used in cathode.In addition, Due to its charge/discharge characteristics, charging last very long under low-voltage, to significantly delay entirely filling for secondary cell Electricity/discharge time.

(existing technical literature)

Korean Patent Laid-Open the 2014-0117947th

Summary of the invention

Technical problem

The present invention relates to a kind of secondary battery cathode and its manufacturing methods, more particularly, are related to a kind of for inhibiting Due to being embedded in secondary battery cathode and its manufacturing method with the volume expansion of negative electrode active material caused by removal lithium embedded.

Technical solution

The secondary battery cathode of embodiment includes according to the present invention: carbon system active material；Conductive material；Silicon systems activity Material-polymer adhesive combination, the polymerization comprising silicon systems active material and for inhibiting the silicon systems active material expansion Object adhesive, the polymer adhesive are bound to the particle surface of the silicon systems active material；And aqueous adhesive.

Based on the total weight of the active material comprising carbon system active material and silicon systems active material, the silicon systems active material Content can be 5 weight % to 25 weight %.

Based on the weight of silicon systems active material, the content of the polymer adhesive can be 25 weight % to 45 weights Measure %.

The polymer adhesive may include the hydrophilic polymer material with hydroxyl (- OH).

The polymer adhesive may include polyacrylic acid (PAA), polyvinyl alcohol (PVA) and Sodium Polyacrylate (Na- At least one of PA).

Based on the weight of the polymer adhesive, the content of the aqueous adhesive can be 30 weight % to 40 weights Measure %.

The aqueous adhesive may include rubber-based material.

The aqueous adhesive may include styrene butadiene ribber (SBR), acrylonitrile butadiene rubber, acrylic acid series At least one of rubber, butyl rubber and fluorubber.

The secondary battery cathode of embodiment is under conditions of 0.5C charging and 0.5C electric discharge until the according to the present invention Five circulations can have 90% or more discharge capacitance.

In addition, the method for manufacturing secondary battery cathode of embodiment includes: to prepare carbon system to live according to the present invention The process of property material；It is prepared by a dispersion medium mixing silicon systems active material, conductive material and polymer adhesive The process of pre-dispersed slurry；Carbon system active material is mixed to the process into pre-dispersed slurry；By by aqueous adhesive and its In be mixed with the mixture mixing of carbon system active material the process for preparing negative electrode slurry；Prepared negative electrode slurry is applied The process being applied on current-collector；With the process for forming cathode by removing moisture from the negative electrode slurry.

The pre-dispersed slurry can be by will silicon systems obtained by wherein silicon systems active material and polymer adhesive combine Active material-polymer adhesive combination is dispersed with the conductive material and is formed.

The solid content of the pre-dispersed slurry can be controlled by the viscosity of the pre-dispersed slurry.

It can control the solid content of the pre-dispersed slurry, so that the pre-dispersed slurry has 3000cp extremely The viscosity of 10000cp.

The method for manufacturing secondary battery cathode of embodiment can also include: by the carbon according to the present invention It is to be mixed with thickener and wherein carbon system active material after the process that active material is mixed with the pre-dispersed slurry Mixture mixing process.

By controlling the combined amount of the thickener, the negative electrode slurry can be controlled as based on the negative electrode slurry Total weight has the solid content of 40 weight % to 50 weight %.

Beneficial effect

The secondary battery cathode and its manufacturing method of embodiment according to the present invention, by using wherein for inhibiting silicon It is that be adsorbed to silicon systems active material-obtained by silicon systems active material polymer-bonded for the polymer adhesive of active material expansion Agent combination can effectively inhibit the volume expansion of silicon systems active material.

In addition, the case where wherein using includes the negative electrode active material of both carbon system active material and silicon systems active material Under, pre-dispersed slurry is prepared by the way that silicon systems active material to be pre-dispersed in polymer adhesive, so that polymer adhesive It can be selectively adsorbed to strong adhesion strength on the surface of silicon systems active material.

In addition, the polymer adhesive with rigidity can be soft with the aqueous adhesive with high electrolyte wetability Change, so as to prevent cracking or the breakage of electrode.Furthermore, it is possible to improve the adhesion strength to current-collector, so as to improve durable Property, and the life characteristic of the electrochemical appliance manufactured by using it can be significantly improved.

Detailed description of the invention

Fig. 1 is to show the figure changed according to the charge/discharge efficiency of the content of polymer adhesive.

Fig. 2 is to show the figure changed according to the charge/discharge efficiency of the content of conductive material.

Fig. 3 is the figure for showing the viscosity change of the solid content according to pre-dispersed slurry.

Fig. 4 is to show the figure changed according to the settling height of the solid content of pre-dispersed slurry.

Fig. 5 is the comparative analysis knot shown using the adhesion strength of the secondary cell of the cathode of embodiment according to the present invention The figure of fruit.

Fig. 6 is the figure shown using the discharge-rate of the secondary cell of the cathode of embodiment according to the present invention.

Fig. 7 is the figure shown using the charge/discharge result of the secondary cell of the cathode of embodiment according to the present invention.

Fig. 8 is the figure for showing the thickness of electrode variation using the secondary cell of the cathode of embodiment according to the present invention.

Specific embodiment

Secondary battery cathode according to the present invention and its manufacturing method provide the insertion and deintercalation being able to suppress due to lithium The technical characteristic of the volume expansion of caused negative electrode active material.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.It is limited however, the present invention should not be construed In embodiments set forth herein, but can be realized with various forms different from each other.On the contrary, providing these embodiments is In order to go deep into the disclosure and comprehensively, and fully convey the scope of the present invention to those skilled in the art Member.Identical appended drawing reference indicates identical element always.

The secondary battery cathode of embodiment includes carbon system active material according to the present invention；Conductive material；Silicon systems activity Material-polymer adhesive combination, the polymerization comprising silicon systems active material and for inhibiting the silicon systems active material expansion Object adhesive, the polymer adhesive are bound to the particle surface of the silicon systems active material；Thickener；It is bonded with water system Agent.

Conventional secondary battery cathode increases the load capacity of the negative electrode active material formed on current-collector, increases system The stacking number of electrode in process is made, or increases the winding number of electrode to realize high capacity.However, such method is due to electricity The structure of pole is upper with limitation in application.

In order to solve this problem, it provides a method, wherein by a certain amount of negative electrode active material using as high capacity The silicon systems material of material replaces.However, wherein including silicon systems active material to replace a certain amount of negative electrode active material In the case of, it since the large volume of the charging and discharging with lithium changes and generates and ruptures and be micronized, and using such negative The secondary cell of pole active material still has following problem: with the progress of charge/discharge cycle, capacity is reduced rapidly, And cycle life shortens.

Embodiment according to the present invention, when by a certain amount of negative electrode active material using the silicon systems material as high-capacity material Material replace when, using wherein silicon systems active material and for inhibit silicon systems active material expand polymer adhesive in conjunction with and obtain Silicon systems active material-polymer adhesive combination.Such silicon systems active material-polymer adhesive combination can be by Pre-dispersed aqueous solution is formed, and the pre-dispersed aqueous solution is by the way that conductive material and silicon systems active material are lived with silicon systems are adsorbed to Property material particle surface on but the hydrophilic polymer with low-down electrolyte wetability carry out it is pre-dispersed and prepare.

In addition, embodiment according to the present invention, the polymer on particle surface due to being adsorbed to silicon systems active material Adhesive has rigidity, the cracking of electrode or breakage and improves in order to prevent to the adhesion strength of current-collector, polymer is glued Mixture uses the aqueous adhesive with high electrolyte wetability to soften.Such method by pre-dispersed aqueous solution manufacture cathode It is described later with regard to the method for the manufacture secondary battery cathode of embodiment according to the present invention.

Carbon system active material is not particularly limited, as long as it can be embedded in and removal lithium embedded.For example, the carbon system is living Property material can be selected from by graphite, easy graphitized carbon (also referred to as soft carbon), difficult graphitized carbon (also referred to as hard carbon), carbon black, stone The mixture of one of the group of black alkene and graphene oxide composition material or two or more materials.

Silicon systems active material is used to replace a certain amount of carbon system active material, and can be selected from by Si, SiO_xAnd Si The mixture of one of group of composition of alloy material or two or more materials.Silicon systems active material is same in the capacity for increasing cathode When prevent it from excessively expanding in the range of replace a certain amount of carbon system active material, and based on including carbon system active material and silicon The total weight content for being the active material of active material can be 5 weight % to 25 weight %.

Polymer adhesive is adsorbed in at least part on the surface of silicon systems active material to be used, to inhibit silicon systems The expansion of active material.Polymer adhesive is adsorbed on the particle surface of silicon systems active material, but may include with very The hydrophilic polymer of low electrolyte wetability, and there are the hydrophilic polymer multiple hydrogen that are able to carry out to be bonded (one Kind strong bonding) hydroxyl (- OH), to be dispersed in water.As a result, polymer adhesive has rigidity, due to strong binding force And a possibility that being adsorbed in silicon systems surface of active material, is high, and has due to strongly hydrophilic in the electricity as organic solvent Solve characteristic not wetted in liquid.

As described above, polymer adhesive includes the polymer material with strongly hydrophilic.For example, described polymer-bonded Agent may include selected from by polyethylene oxide, polypropylene oxide, polyacrylic acid, polyvinyl alcohol, polyvinyl acetate base ester and poly- third The mixture of one of the group of olefin(e) acid sodium composition material or two or more materials.Preferably, the polymer adhesive can be with It is all these all to silicon comprising at least one of polyacrylic acid (PAA), polyvinyl alcohol (PVA) and Sodium Polyacrylate (Na-PA) It is that active material has excellent adsorption capacity.

The polymer adhesive can prevent conductive network from disconnecting and maximize the charge/discharge efficiency of secondary cell In the range of by comprising, and when the total weight based on silicon systems active material with the amount of 25 weight % or more in use, can be with Promptly increase and maintain the charge/discharge efficiency of secondary cell.However, if the content of polymer adhesive is excessively increased, Then the viscosity of pre-dispersed slurry increases, thus dispersibility deterioration and the operability reduction in the manufacturing process of cathode.Therefore, base In the total weight of silicon systems active material, content can be controlled is 45 weight % or less.

Fig. 1 is to show the figure changed according to the charge/discharge efficiency of the content of polymer adhesive.

In Fig. 1, it is fixed as using above-mentioned silicon systems active material, and by the weight percent of conductive material based on pre- The total weight of dispersed paste be 1 weight % after, increase polymer adhesive content while confirmation according to charging and The charge/discharge efficiency of electric discharge.Here, charge/discharge efficiency is the result confirmed in first time circulation and second of circulation. The reason of confirming initial charge/discharging efficiency is, due to the characteristic of the silicon systems material as high-capacity material, in initial charge The disconnection of period conductive network as caused by volume expansion has biggest impact to the reduction of charge/discharge efficiency, uses polymerization Object adhesive can inhibit such case.

As shown in Figure 1, the weight percent in wherein polymer adhesive compares the weight percent of silicon systems active materials In the case that ratio is 25.3% or more, it can be seen that charge/discharge efficiency increases, and especially in second of circulation, It can be seen that charge/discharge efficiency increases sharply.It, can be in the case where wherein further increasing the content of polymer adhesive Find out that charge/discharge efficiency is maintained at similar level.Therefore, when using silicon systems active material, when based on silicon systems activity material The total weight of material can improve charge/discharge efficiency when the content of polymer adhesive is 25 weight % or more.

Conductive material is not particularly limited, as long as its conductive other elements without causing with secondary cell Side reaction.For example, the conductive material may include selected from one of the group that is made up of material or two kinds with The mixture of upper material: graphite, natural graphite, artificial graphite etc.；Carbon black class, such as carbon black (super-p), acetylene black, Ketjen black, channel black, furnace black, lampblack, summer are black etc.；Conductive fiber, carbon fiber, carbon nano-fiber, metallic fiber etc.；Gold Belong to powder, fluorocarbons, aluminium, nickel by powder etc.；Conductive whiskers, zinc oxide, potassium titanate etc.；Conductive metal oxide, it is all Such as titanium oxide；And conductive material, polyphenylene derivatives etc..

Conductive material can make secondary battery cathode keep electric conductivity in the range of by comprising.When to be based on silicon systems The amount of the 5 weight % of total weight or more of active material is in use, charge/discharge efficiency increases sharply, and works as with 10 weights The amount of % or more is measured in use, 95% or more charge/discharge efficiency can be obtained.It, can as the content of conductive material increases To form effective conductive network.However, in order to control the solid concentration of generated negative electrode slurry, it can be by the content control It is made as the 20 weight % of total weight or less based on silicon systems active material.

Fig. 2 is to show the figure changed according to the charge/discharge efficiency of the content of conductive material.

In Fig. 2, using above-mentioned silicon systems active material, and the weight percent of silicon systems active material is being compared into polymer The ratio of the weight percent of adhesive is fixed on after 25%, while increasing the content of polymer adhesive, confirms root According to the charge/discharge efficiency of charging and charging.Here, charge/discharge efficiency is as shown in Figure 1 in first time circulation and second The result confirmed in circulation.

As shown in Fig. 2, the ratio of the weight percent in the weight percent comparison silicon systems active material of wherein conductive material In the case where 5.3% or more, it can be seen that charge/discharge efficiency increases sharply.As the content of conductive material increases, fill Electricity/discharging efficiency continues to increase.Therefore, the weight based on silicon systems active material, the content of conductive material can for 5 weight % with On.

In addition, required leads when the charge/discharge efficiency for determining 95% or more is the maximal efficiency of silicon systems active material Electric material content is calculated as 10 weight % or more based on the weight of silicon systems active material, and is 15 weight % or more in the content In the case where, much better performance improvement may be implemented.

It can be optionally comprising thickener to determine the solid content for manufacturing the negative electrode slurry of cathode.That is, Addition thickener is when needed with by the control of the solid content of negative electrode slurry, in suitable range, and the thickener can be with It is the mixture selected from one of following material or two or more materials: cellulose-based material, such as carboxymethyl cellulose (CMC), methylcellulose, hydroxypropyl cellulose etc..The content of thickener is determined according to the solid content of negative electrode slurry, and base The content of the total weight of solid content in negative electrode slurry, thickener can be 0 weight % to 5 weight %, so that cathode is starched Expect the solid content that 40 weight % to 50 weight % are had based on total weight.

Aqueous adhesive is added with the flexibility of auxiliary electrode (i.e. cathode) and the adhesion strength of electrode.Aqueous adhesive can With comprising rubber-based material, and can be selected from by styrene butadiene ribber (SBR), acrylonitrile butadiene rubber, propylene The mixture of one of the group of acid system rubber, butyl rubber and fluorubber composition material or two or more materials.

Polymer adhesive be characterized by having it is multiple be able to carry out hydrogen bonding (usually strong bonding) hydroxyl (- OH), to be dispersed in water.As a result, polymer adhesive has stone rigidity, it is living to be adsorbed to silicon systems with strong adhesion strength Property material particle surface on a possibility that it is high, and there is very strong hydrophily, to have not by as organic solvent Electrolyte wetting characteristic.

Here, polymer adhesive has strong adhesion strength, and therefore, the rigidity of polymer adhesive itself is very high, from And it may there is a phenomenon where the cracking of electrode or breakages.Therefore, it is necessary to add aqueous adhesive.

Poidometer based on polymer adhesive, the content of aqueous adhesive can be 30 weight % to 40 weight %.When When the content is less than 30 weight %, it may occur however that the problem of such as shortage adhesion strength and electrode crack.When the content is big When 40 weight %, the aqueous adhesive with good electrolyte wetability may soak in the electrolytic solution, to excessively drop The rigidity of low polymer adhesive, so that the effect of the volume expansion of silicon systems active material be inhibited to deteriorate.

As described above, silicon systems active material-polymer adhesive combination is formed by pre-dispersed slurry, the pre-dispersed slurry Material be by by conductive material and silicon systems active material be adsorbed to silicon systems active material particle surface on but have very low Electrolyte wetability hydrophilic polymer carry out it is pre-dispersed and prepare.That is, in order to use with high charge/put The silicon systems active material of capacitance, it is important that inhibit the volume due to silicon systems active material caused by being charged and discharged swollen It is swollen, and the volume expansion of silicon systems active material is suppressed by the polymer adhesive being adsorbed on silicon systems active material.

Then pre-dispersed slurry is mixed with carbon system active material, and thereto addition aqueous adhesive to prepare cathode slurry Material.When preparing cathode using the negative electrode active material comprising carbon system active material and silicon systems active material, by only by silicon systems Active material and conductive material and polymer adhesive is pre-dispersed prepares pre-dispersed slurry, can effectively inhibit silicon systems activity The volume expansion of material.

That is, by by conductive material and polymer adhesive and including carbon system active material and silicon systems activity material The negative electrode active material of material is dispersed come in the case where preparing negative electrode slurry, when mixed polymer adhesive, polymer is viscous The absorption object of mixture is not limited to silicon systems active material, but extends to carbon system active material.Therefore, polymer adhesive adsorbs Degree to silicon systems active material reduces, so as to be unable to fully inhibit the volume expansion of silicon systems active material.

On the other hand, when by the way that silicon systems active material and conductive material and polymer adhesive are carried out pre-dispersed prepare When pre-dispersed slurry, polymer adhesive can be selectively adsorbed on the surface of silicon systems active material.That is, silicon systems The surface of active material usually has hydrophily, and polymer adhesive to be mixed includes hydrophilic polymer material.Cause Polymer adhesive, can be by being effectively attached to the surface of silicon systems active material with strong hydrogen bonding power and Van der Waals force by this On, to form silicon systems active material-polymer adhesive combination.

Hereinafter, it will be described in the method for manufacturing secondary battery cathode of embodiment according to the present invention.

The method for manufacturing secondary battery cathode of embodiment includes: to prepare carbon system active material according to the present invention Process S100；Silicon systems active material, conductive material and polymer adhesive are mixed by a dispersion medium pre- to prepare The process S200 of dispersed paste；The process S300 that carbon system active material is mixed with pre-dispersed slurry；By by aqueous adhesive It is mixed with the mixture for being wherein mixed with carbon system active material to prepare the process S500 of negative electrode slurry；Prepared cathode is starched Expect the process S600 being applied on current-collector；With the process S700 for forming cathode by removing moisture from negative electrode slurry.

Here, prepare the process S100 of carbon system active material and by a dispersion medium by silicon systems active material, conduction Material and polymer adhesive mix to prepare the process S200 of pre-dispersed slurry each other not in the relationship of time sequencing.It can be with It is executed after performing the process S100 for preparing carbon system active material and prepares the process S200 of pre-dispersed slurry, or can be Perform the process S100 for preparing the process S200 carbon system active material of execution preparation later of pre-dispersed slurry.Prepare carbon system activity The process S100 of material and the process S200 for preparing pre-dispersed slurry may be performed simultaneously.

In the process S100 for preparing carbon system active material, prepare the carbon system active material of pulverulence first.Here, make For carbon system active material, the various carbon-based materials that can be embedded in removal lithium embedded can be used as described above.

In the process S200 for preparing pre-dispersed slurry, first by by the silicon systems active material of pulverulence, conduction material Material and polymer adhesive mixing are to form pre-dispersed mixture.Then, decentralized medium such as water is added in mixture simultaneously Stirring is to prepare pre-dispersed slurry.Adding water into mixture and stirring can be more than by rotation speed as known in the art It the saw blade formula mixer of 2000rpm to 2500rpm such as homogenizer, omnipotent blender, clarifying mixer (clearmixer) and fills out It fills mixer (fill mixer) or executes the equipment such as pearl of mixing by filling the packing material of such as pearl thereto Grinding machine, ball mill, basket grinding machine, grater etc. carry out.

The feelings of pre-dispersed mixture are being formed by mixing silicon systems active material, conductive material and polymer adhesive Under condition, by will silicon systems active material-polymer adhesive obtained by wherein silicon systems active material is in conjunction with polymer adhesive Combination and the conductive material, which are dispersed in the water as decentralized medium, forms pre-dispersed slurry.

Here, the solid content of pre-dispersed slurry is controlled by the viscosity of pre-dispersed slurry.

In detail, the viscosity of the pre-dispersed slurry prepared by identical mixed processes is living to silicon systems by polymer adhesive Property material ratio determine.That is, the content with polymer adhesive increases, the viscosity of pre-dispersed slurry increases, and In the case where silicon systems active material, density of solid 2.1g/cm³To 2.35g/cm³.Therefore, in order to prepare pre-dispersed slurry The sedimentation for inhibiting silicon systems active material after material, needs a certain range of viscosity.

Here, in order to improve operability while farthest inhibiting the sedimentation of silicon systems active material, to viscosity Range is limited.Pre-dispersed slurry can have the viscosity of 3000cp to 10000cp.That is, pre-dispersed slurry wherein In the case that the viscosity of material is less than 3000cp, the rate of settling of silicon systems active material increases, so that the particle of silicon systems active material Sink rapidly in the period of resting of pre-dispersed slurry, the physical property of pre-dispersed slurry is caused to deteriorate.Pre-dispersed slurry wherein Viscosity be greater than 10000cp in the case where, the dispersibility of pre-dispersed slurry reduces, and the operability for executing process becomes very It is low.

Fig. 3 is the figure for showing the viscosity change of the solid content according to pre-dispersed slurry.Fig. 4 is display according to pre-dispersed slurry The figure of the settling height variation of the solid content of material.In figs. 3 and 4, it will be used as an example to wherein polymer adhesive to silicon The case where ratio for being active material is 1:0.24 is described.

As shown in figure 3, wherein polymer adhesive to the ratio of silicon systems active material is 1:0.24 in the case where, when being based on When the total weight solid content of pre-dispersed slurry has the value of 22 weight % to 25 weight %, pre-dispersed slurry has 3000cp To the viscosity of 10000cp.Therefore, in the case where ratio of the wherein polymer adhesive to silicon systems active material is 1:0.24, in advance The appropriate solid content of dispersed paste is confirmed as the value of 22 weight % to 25 weight %.

In Fig. 4, after preparing pre-dispersed slurry with ratio of the polymer adhesive to silicon systems active material for 1:0.24, By one quantitative collection in the bottle that can measure length, and measure the height of the bottom surface of pre-dispersed slurry.Hereafter, in room Temperature is lower to execute post-processing 24 hours, and the bottom surface of pre-dispersed slurry then will be measured again in the stick insertion bottle with certain length Height.

In the case where pre-dispersed slurry, the rate of settling is determined according to certain viscosity ratio, and the silicon systems activity settled Material and polymer adhesive accumulate on bottom surface.By that, by the height of the stick measurement of insertion, can be measured final after 24 hours It is deposited in the height of the settled layer on bottle bottom, and confirms the journey settled during certain period of time in a manner of ratio Degree.It here, is, when producing secondary battery cathode in batches, to be given according to process the reason of measurement sedimentation layer height after 24 hours During resting out, and it is described rest during be usually 12 hours to 24 hours.Therefore, the height of settled layer is measured after 24 hours Degree.

As shown in figure 4, wherein polymer adhesive to the ratio of silicon systems active material is 1:0.24 in the case where, when being based on When the solid content of the pre-dispersed slurry of the total weight of pre-dispersed slurry has the value of 22 weight % to 25 weight %, it can be seen that The ratio of settled layer is in 3%.It can thus be seen that wherein pre-dispersed slurry solid content be 22 weight % or more feelings Under condition, pre-dispersed slurry has the viscosity of 3000cp to 10000cp, so as to effectively realize silicon systems active material and polymerization The sedimentation of object adhesive.

Therefore, in the process S200 for preparing pre-dispersed slurry, it can control the solid content of pre-dispersed slurry, so that in advance Dispersed paste can have the viscosity of 3000cp to 10000cp.As noted previously, as the poidometer based on silicon systems active material, The content of polymer adhesive can be 25 weight % to 45 weight %, in order to make the viscosity of pre-dispersed slurry meet above-mentioned model In the range of enclosing, pre-dispersed slurry can have the solid content of 15 weight % to 25 weight % based on total weight.

Mixing carbon system active material process S300 in, when preparing pre-dispersed slurry by above-mentioned operation, pass through by Pre-dispersed slurry mixes to prepare negative electrode slurry with carbon system active material.By preparing pre-dispersed slurry as described above, and by carbon It is that active material is mixed with pre-dispersed slurry, polymer adhesive can be selectively adsorbed to the surface of silicon systems active material On.That is, the surface of silicon systems active material usually has hydrophily, and polymer adhesive to be mixed includes hydrophilic Property polymer material, so that the surface of silicon systems active material is effectively attached to using strong hydrogen bonding power and Van der Waals force, so that Silicon systems active material-polymer adhesive combination can be formed.

Hereafter, according to the present invention the method for the manufacture secondary battery cathode of embodiment can also include by thickener with Wherein it is mixed with the process S400 of the mixture mixing of carbon system active material.Thickener is optionally included in mixture with true The solid content for manufacturing the negative electrode slurry of cathode is determined, and by the control of its content in suitable range, to control thereafter The solid content of the negative electrode slurry of preparation.15 weight % consolidating to 25 weight % is had based on total weight in wherein negative electrode slurry In the case where body content, operability can be improved while applying, while improving the drying for removing water from negative electrode slurry Rate.Therefore, the total weight based on solid content in negative electrode slurry, the content of thickener can be 0 weight % to 5 weight %, So that negative electrode slurry has above-mentioned solid content.

In the process S500 for preparing negative electrode slurry, in the mixture or thickener for being wherein mixed with carbon system active material In the case where being comprised in pre-dispersed slurry, by the way that aqueous adhesive is divided with wherein carbon system active material and thickener and in advance The mixture that scattered slurry is obtained by mixing mixes to prepare negative electrode slurry.

As described above, polymer adhesive has stone rigidity, silicon systems activity material is adsorbed to strong adhesion strength A possibility that on the particle surface of material, is high, and has very strong hydrophily, to have not by the electricity as organic solvent Solve the characteristic of liquid wetting.By adding aqueous adhesive, moisten being used with the polymer adhesive of rigidity with high electrolyte Moist aqueous adhesive softening, so as to prevent electrode from cracking or breakage, and improves the adhesion strength to current-collector.

Here, negative electrode slurry can have the solid content of 40 weight % to 50 weight % based on total weight.Namely It says, pre-dispersed slurry has the solid content of 15 weight % to 25 weight % based on the total weight of pre-dispersed slurry, and leads to Mixing carbon system's active material and aqueous adhesive are crossed, or by as needed further mixing it with thickener, negative electrode slurry There can be the solid content of 40 weight % to 50 weight % based on the total weight of negative electrode slurry.Pass through consolidating negative electrode slurry Body content is kept within the above range, can improve operability while applying, while improving and removing water from negative electrode slurry Rate of drying.

In the process S600 being applied to negative electrode slurry on current-collector, by what is prepared in the process S500 for preparing cathode Negative electrode slurry is applied on current-collector.Here, in general, the current-collector with a thickness of 3 μm to 500 μm can be used, and without spy It does not limit, as long as it is with high conductivity without causing chemical change in the secondary battery.It is, for example, possible to use copper, Stainless steel, aluminium, nickel, titanium, the processed aluminium of sintering carbon or surface carbon, nickel, titanium or silver etc. or stainless steel.

The process S700 to form cathode is executed by removing water from negative electrode slurry.It include that water in negative electrode slurry can The common of cathode is used to form to remove, and can be used by the way that the negative electrode slurry being applied on current-collector is dried Method.

Hereinafter, description embodiment party according to the present invention will be compared to the experimental result of each comparative example and embodiment The result of formula.Herein, following embodiment is provided to illustrate the present invention, and the scope of the present invention is not limited by experiment condition.

<comparative example 1>

As negative electrode active material, the total weight based on negative electrode active material, carbon system active material and silicon systems active material Dosage be respectively 90 weight % and 10 weight %.

By conductive material carbon black dispersion in the water as decentralized medium, and negative electrode active material is mixed into as a whole Wherein.It then, will be as the carboxymethyl cellulose of thickener (CMC) and as the styrene butadiene ribber (SBR) of adhesive It is successively mixed to prepare negative electrode slurry, and negative electrode slurry is applied on current-collector and is dried is negative to form secondary cell use Pole.

The secondary battery cathode is by the negative electrode active material of 95.6 weight %, the conductive material of 1.0 weight %, 1.1 The adhesive of the thickener of weight % and 2.3 weight % are formed.

Here, the load capacity of the secondary battery cathode of comparative example 1 is 204mg/25cm², and its porosity is 33.9%.

<embodiment 1>

As negative electrode active material, the total weight based on negative electrode active material, carbon system active material and silicon systems active material Dosage be respectively 90 weight % and 10 weight %.

By conductive material carbon black, silicon systems active material and polymer adhesive be pre-dispersed in the water as decentralized medium with Pre-dispersed slurry is prepared, and carbon system active material is mixed.In addition, by as the carboxymethyl cellulose of thickener (CMC) It is mixed with the mixture for being mixed with carbon system active material, and successively by the styrene butadiene ribber as aqueous adhesive (SBR) mixed to prepare negative electrode slurry.Then, negative electrode slurry is applied on current-collector and is dried, form secondary cell Use cathode.Here, it is added first based on the polymer adhesive that polymer adhesive total weight is 9.5 weight % to prepare one Secondary pre-dispersed slurry, then by the polymer adhesive of prepared primary pre-dispersed slurry and remaining 90.5 weight % into one Step mixing is to prepare secondary pre-dispersed slurry.Thickener and aqueous adhesive are successively mixed with secondary pre-dispersed slurry to prepare Negative electrode slurry.

Secondary battery cathode is by the negative electrode active material of 95.6 weight %, the polymer adhesive of 2.4 weight %, 1.0 The aqueous adhesive of the conductive material of weight %, the thickener of 0.15 weight % and 0.85 weight % is formed.

Here, the load capacity of the secondary battery cathode of embodiment 2 is 205mg/25cm², and its porosity is 35.4%.

<embodiment 2>

As negative electrode active material, the total weight based on negative electrode active material, carbon system active material and silicon systems active material Dosage be respectively 90 weight % and 10 weight %.

By conductive material carbon black, silicon systems active material and polymer adhesive be pre-dispersed in the water as decentralized medium with Pre-dispersed slurry is prepared, and carbon system active material is mixed.In addition, by as the carboxymethyl cellulose of thickener (CMC) It is mixed with the mixture for being mixed with carbon system active material, and successively by the styrene butadiene ribber as aqueous adhesive (SBR) mixed to prepare negative electrode slurry.Then, negative electrode slurry is applied on current-collector and is dried, form secondary cell Use cathode.In this case, polymer adhesive is mixed as a whole with silicon systems active material and conductive material to prepare Pre-dispersed slurry.

Secondary battery cathode is by the negative electrode active material of 95.6 weight %, the polymer adhesive of 2.4 weight %, 1.0 The aqueous adhesive of the conductive material of weight %, the thickener of 0.15 weight % and 0.85 weight % is formed.

Here, the load capacity of the secondary battery cathode of embodiment 2 is 205mg/25cm², and its porosity is 35.4%.

Fig. 5 is the comparative analysis knot shown using the adhesion strength of the secondary cell of the cathode of embodiment according to the present invention The figure of fruit.

As shown in figure 5, in the case of comparative example 1, embodiment 1 and embodiment 2 are higher than to the adhesion strength of current-collector Adhesion strength.However, the difference is inappreciable.Comparative example 1, embodiment 1 and embodiment 2 are confirmed as with certain level Adhesion strength.

Fig. 6 is the figure shown using the discharge-rate of the secondary cell of the cathode of embodiment according to the present invention.

In Fig. 6, the discharge capacity based on 0.1C confirmed the discharge-rate of 0.5C, 1.0C, 2.0C, 3.0C and 4.0C. As shown in fig. 6, when compared with comparative example 1, discharge-rate characteristic is very in the case where embodiment 1 and embodiment 2 It is high.This is that polymer adhesive is adsorbed in silicon systems surface of active material as a result, and can be seen that polymer adhesive is logical It crosses using its strong adhesion strength and restrained effectively the volume expansion due to caused by the charge/discharge of silicon systems active material.

Fig. 7 is the figure shown using the charge/discharge result of the secondary cell of the cathode of embodiment according to the present invention.

As shown in fig. 7, when by executing 30 charging and discharging circulation at 0.5C/0.5C to carry out life assessment, As can be seen that comparative example 1 has low discharge capacitance since volume expansion is absolutely not suppressed.In contrast, when When using polymer adhesive, there are advantages for life characteristic.Particularly, embodiment 1 and embodiment 2 are until the 5th time recycles all With 90% or more discharge capacitance, therefore, it can be confirmed that restrained effectively silicon systems by polymer adhesive lives The volume expansion of property material.

Fig. 8 is the figure for showing the thickness of electrode variation using the secondary cell of the cathode of embodiment according to the present invention.

As shown in figure 8, in the case of comparative example 1, the fully charged thickness change of electrode is measured as 43.9%.It is another Aspect, in the case of example 1, the fully charged thickness change of electrode are measured as 48.4%, and in the feelings of embodiment 2 Under condition, the fully charged thickness change of electrode is measured as 41.4%.

Here, when confirming fully charged thickness change after 30 circulations are evaluated, comparative example 1, which is shown, compares embodiment 1 low thickness swelling.However, in the case of comparative example 1, going out the low-down longevity as the result is shown due to above-mentioned life assessment Life, therefore cannot make out the performance for showing silicon systems active material.On the other hand, can be confirmed embodiment 2 show frequently compared with The low thickness swelling of example 1.

It can be seen that when compared with comparative example 1 from the result, secondary cell in 2 the two of embodiment 1 and embodiment Life characteristic is improved, and when preparing pre-dispersed slurry, wherein by primary pre-dispersed slurry and pre- point secondary In the case of the embodiment 1 for dissipating the final pre-dispersed slurry of slurry preparation, the adhesion strength to current-collector can be improved.Lead to wherein It crosses and mixes polymer adhesive with silicon systems active material and conductive material as a whole to prepare the embodiment 2 of pre-dispersed slurry In the case of, thickness swelling can be effectively reduced.

That is, embodiment is related to according to the present invention secondary battery cathode and its manufacturing method, by using Wherein the polymer adhesive for inhibiting silicon systems active material to expand is adsorbed to the activity of silicon systems obtained by silicon systems active material Material-polymer adhesive combination, can effectively inhibit the volume expansion of silicon systems active material.

In addition, the case where wherein using includes the negative electrode active material of both carbon system active material and silicon systems active material Under, pre-dispersed slurry is prepared by the way that silicon systems active material to be pre-dispersed in polymer adhesive, so that polymer adhesive It can be selectively adsorbed to strong binding force on the surface of silicon systems active material.

In addition, the polymer adhesive with rigidity can be soft with the aqueous adhesive with high electrolyte wetability Change, so as to prevent cracking or the breakage of electrode.Furthermore, it is possible to improve the adhesion strength to current-collector, so as to improve durable Property, and the life characteristic of the electrochemical appliance by using its manufacture can be significantly improved.

Hereinbefore, although being described and illustrated the preferred embodiment of the present invention using specific term, this The term of sample is only used for illustrating the purpose of the present invention.It should be appreciated that in the feelings for the spirit and scope for not departing from appended claims Under condition, various changes and amendment can be carried out to embodiments of the present invention and described term.It should not be from master of the invention Purport and range individually understand the embodiment of these modifications, but should be considered as these embodiments in right of the invention In the range of it is required that.