Secondary battery cathode and its manufacturing method
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,更具体地,涉及一种用于二次电池负极的二次电池用负极及其制造方法。根据本发明的一个实施方式,所述二次电池用负极包含：碳系活性材料；导电材料；和硅系活性材料-聚合物粘合剂复合物,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。(The present invention relates to a kind of secondary battery cathode and its manufacturing methods, more particularly, to a kind of secondary battery cathode and its manufacturing method for secondary battery negative pole.According to embodiment of the present invention, the secondary battery cathode includes: carbon system active material；Conductive material；With silicon systems active material-polymer adhesive compound, wherein the polymer adhesive for inhibiting silicon systems active material to expand is bound to the particle surface of the silicon systems active material.)
1. a kind of secondary battery cathode, the cathode includes:
Carbon system active material；
Conductive material；With
Silicon systems active material-polymer adhesive combination, comprising silicon systems active material and for inhibiting the silicon systems activity material The polymer adhesive of the expansion of material, the polymer adhesive are bound to the particle surface of the silicon systems active material.
2. secondary battery cathode as described in claim 1, wherein based on carbon system active material and the silicon systems is included The total weight of the active material of active material includes the silicon systems active material with the amount of 5~15 weight %.
3. secondary battery cathode as described in claim 1, wherein the weight based on the silicon systems active material, with 25~45 The amount of weight % includes the polymer adhesive.
4. secondary battery cathode as described in claim 1, wherein the polymer adhesive includes with hydroxyl (- OH) Hydrophilic polymer material.
5. secondary battery cathode as described in claim 1, wherein the polymer adhesive includes at least one in following Kind: polyacrylic acid (PAA), polyvinyl alcohol (PVA) and Sodium Polyacrylate (Na-PA).
6. secondary battery cathode as described in claim 1, the initial discharge capacity with 470mAh or more.
7. secondary battery cathode as described in claim 1, with 87% or more initial charge/discharging efficiency.
8. a kind of method for manufacturing secondary battery cathode, comprising:
Prepare the process of carbon system active material；
Pre-dispersed slurry is prepared by mixing silicon systems active material, conductive material and polymer adhesive in a dispersion medium Process；
The process for preparing negative electrode slurry by mixing the pre-dispersed slurry and carbon system active material；
The process negative electrode slurry of preparation being applied on current-collector；And
The process for forming cathode by removing moisture from the negative electrode slurry.
9. method according to claim 8, wherein the pre-dispersed slurry be by will wherein the silicon systems active material and Polymer adhesive silicon systems in conjunction with obtained by active material-polymer adhesive combination and conductive material dispersed and It is formed.
10. method according to claim 8, wherein the solid content of the pre-dispersed slurry is by the pre-dispersed slurry Viscosity control.
11. method as claimed in claim 10, wherein the solid content of the pre-dispersed slurry is controlled, so that described pre-dispersed Slurry has the viscosity of 3000~10000cp.
12. method according to claim 8, wherein the pre-dispersed slurry has consolidating for 15~25 weight % based on total weight Body content.
13. method according to claim 8, wherein the process for preparing negative electrode slurry includes:
The work of a negative electrode slurry is prepared by mixing a certain amount of pre-dispersed slurry and carbon system active material first Sequence；With
The work of secondary negative electrode slurry is prepared by further mixing a negative electrode slurry and remaining pre-dispersed slurry Sequence.
14. method according to claim 8, wherein the negative electrode slurry has the solid of 40~50 weight % based on total weight Content.
Technical field
This disclosure relates to secondary battery cathode and its manufacturing methods, more specifically it relates to be used for secondary battery cathode The secondary battery cathode and its manufacturing method of pole.
Background technique
Recently, the concern of energy storage technologies is increased.As application field extends to mobile phone, Portable image pickup Machine, laptop the energy even electric vehicle the energy, for electrochemical appliance research and development effort increasingly It embodies.In this respect, electrochemical appliance is at most paid close attention to, and the exploitation of especially rechargeable secondary batteries has become concern Focus.Recently, when developing such battery, the research and development for designing new electrode and new battery has been carried out, from And improve capacity density and specific energy.
In the secondary cell applied at present, lithium secondary battery better than conventional batteries such as use aqueous electrolyte N-MH, Ni-Cd and the advantages of sulfuric acid-lead 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 and deintercalate lithium ions either alloying and de- alloying lithium The material of ion is as cathode and anode, and organic bath or polymer dielectric are filled between cathode and anode to make Make lithium secondary battery.When lithium ion is from anode and cathode insertion and deintercalation, produced electricl energy by oxidation reaction and reduction reaction.
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 business 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, to have problems in that the silicon systems material for being difficult to use large scale 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.
(relevant technical literature)
Korean Patent Laid-Open the 2014-0117947th
Summary of the invention
Technical problem
The present invention relates to secondary battery cathode and its manufacturing methods, more specifically it relates to a kind of for inhibiting because of lithium The secondary battery cathode and its manufacturing method of negative electrode active material volume expansion caused by insertion and deintercalation.
Technical solution
The secondary battery cathode of embodiment includes according to the present invention: carbon system active material；Conductive material；It is living with silicon systems Property material-polymer adhesive combination, the expansion comprising silicon systems active material and for inhibiting the silicon systems active material Polymer adhesive, the polymer adhesive are bound to the particle surface of the silicon systems active material.
It, can be with 5~15 weights based on the total weight of the active material comprising carbon system active material and silicon systems active material The amount for measuring % includes the silicon systems active material.
It can include described polymer-bonded with the amount of 25~45 weight % based on the weight of the silicon systems active material Agent.
The polymer adhesive may include the hydrophilic polymer material with hydroxyl (- OH).
The polymer adhesive may include at least one of the following: polyacrylic acid (PAA), polyvinyl alcohol (PVA) With Sodium Polyacrylate (Na-PA).
The secondary battery cathode can have the initial discharge capacity of 470mAh or more.
The secondary battery cathode can have 87% or more initial charge/discharging efficiency.
In addition, the method for the manufacture secondary battery cathode of embodiment includes: to prepare carbon system activity material according to the present invention The process of material；It is pre-dispersed to prepare by mixing silicon systems active material, conductive material and polymer adhesive in a dispersion medium The process of slurry；The process for preparing negative electrode slurry by mixing the pre-dispersed slurry and carbon system active material；It will system Standby negative electrode slurry is applied to the process on current-collector；And cathode is formed by removing moisture from the negative electrode slurry Process.
The pre-dispersed slurry can be by will be obtained by wherein the silicon systems active material and polymer adhesive combine Silicon systems 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 3000~10000cp Viscosity.
The pre-dispersed slurry can have the solid content of 15~25 weight % based on total weight.
The process for preparing negative electrode slurry may include: by the way that a certain amount of pre-dispersed slurry and the carbon system is active The process that material is mixed first to prepare a negative electrode slurry；With by by a negative electrode slurry and remaining pre-dispersed slurry The process that material further mixes to prepare secondary negative electrode slurry.
The negative electrode slurry can have the solid content of 40~50 weight % based on total weight.
Beneficial effect
The secondary battery cathode and its manufacturing method that embodiment is related to according to the present invention, by using wherein for pressing down It is viscous that the polymer adhesive of silicon systems active material expansion processed is adsorbed to the active material of silicon systems obtained by silicon systems active material-polymer Mixture 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.
That is, restrained effectively the volume expansion of silicon systems active material, so as to improve the durable of secondary battery cathode 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 the figure for showing viscosity and changing with the solid content of pre-dispersed slurry.
Fig. 2 is the figure for showing settling height and changing with the solid content of pre-dispersed slurry.
Fig. 3 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. 4 is the figure shown using the charge/discharge result of the secondary cell of the cathode of embodiment according to the present invention.
Fig. 5 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, which provide, to be able to suppress the insertion due to lithium and takes off The technical characteristic of the volume expansion of negative electrode active material caused by embedding.
Hereinafter, embodiments of the present invention will be described in detail with reference to attached drawing.However, the present invention should not be construed To be limited to embodiments set forth herein, but can be realized with various forms different from each other.On the contrary, providing these embodiment party Formula is in order to enable the disclosure is deeply and comprehensive, and fully conveys the scope of the present invention to this field Technical staff.Identical appended drawing reference indicates identical element always.
The secondary battery cathode of embodiment includes according to the present invention: carbon system active material；Conductive material；It is living with silicon systems Property material-polymer adhesive combination, the expansion comprising silicon systems active material and for inhibiting the silicon systems active material Polymer adhesive, the polymer adhesive are bound to the particle surface of the silicon systems active material.
Conventional secondary battery cathode increases the load capacity of the negative electrode active material formed on current-collector, increases The stacking number of electrode in manufacturing process, or the winding number of electrode is increased to realize high capacity.However, such method due to The structure of electrode 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.
According to embodiment of the present invention, when a certain amount of negative using being replaced as the silicon systems material of high-capacity material The polymer adhesive when active material of pole, using wherein silicon systems active material and for inhibiting the silicon systems active material expansion The active material of the silicon systems in conjunction with obtained by-polymer adhesive combination.Such silicon systems active material-polymer adhesive combines Body can be formed by pre-dispersed aqueous solution, the pre-dispersed aqueous solution by by conductive material and silicon systems active material be adsorbed to On the particle surface of silicon systems active material but with low-down electrolyte wetability hydrophilic polymer carry out it is pre-dispersed and Preparation.Later reference according to the present invention embodiment manufacture secondary battery cathode method to such by pre-dispersed water-soluble The method of liquid manufacture cathode is described.
Carbon system active material is not particularly limited, as long as it can be embedded in and removal lithium embedded.For example, carbon system active material Can be the mixture selected from one of the group that is made up of material or two or more materials: graphite, easy graphitized carbon ( Referred to as soft carbon), difficult graphitized carbon (also referred to as hard carbon), carbon black, graphene and graphene oxide.
Silicon systems active material is used to replace a certain amount of carbon system active material, and can be selected from the group being made up of One of material or two or more materials mixture: Si, SiOx and Si alloy.Silicon systems active material is in the appearance for increasing cathode A certain amount of carbon system active material is replaced in the range of measuring while preventing it from excessively expanding, and is based on including carbon system active material Total weight content with the active material of silicon systems active material can be 5 weight % to 15 weight %.
Conductive material is not particularly limited, as long as its is conductive without causing and the other elements of secondary cell Side reaction.For example, the conductive material may include selected from one of the group being made up of material or two or more The mixture of material: graphite such as natural graphite, artificial graphite etc.；Carbon black class such as carbon black (super-p), acetylene black, Ketjen black, slot Method carbon black, furnace black, lampblack, summer are black etc.；Conductive fiber such as carbon fiber, carbon nano-fiber, metallic fiber etc.；Metal powder is as being fluorinated Carbon, aluminium, nickel by powder etc.；Conductive whiskers such as zinc oxide, potassium titanate etc.；Conductive metal oxide such as titanium oxide etc.；And conduction material Expect such as polyphenylene derivatives.
Conductive material can make secondary battery cathode keep electric conductivity in the range of by comprising.When living based on silicon systems Property material total weight with the amount of 5 weight % or more in use, charge/discharge efficiency increases sharply, and when with 10 weight % Above amount is in use, 95% or more charge/discharge efficiency can be obtained.It, can be with shape as the content of conductive material increases At effective conductive network.However, silicon systems active material can be based in order to control the solid concentration of generated negative electrode slurry Total weight by the content control be 20 weight % or less.
The polymer adhesive is adsorbed at least part surface of silicon systems active material, for inhibiting silicon systems living The expansion of property material.The polymer adhesive is adsorbed on the particle surface of silicon systems active material, but may include with non- The hydrophilic polymer of often low electrolyte wetability, and there are the hydrophilic polymer multiple hydrogen that are able to carry out to be bonded The hydroxyl (- OH) of (a kind of strong bonding), to be dispersed in water.As a result, polymer adhesive has rigidity, due to combining by force Power and it is high a possibility that be adsorbed in silicon systems surface of active material, and have due to strongly hydrophilic as organic solvent Not wetted characteristic in electrolyte.
As described above, the polymer adhesive includes the polymer material with strongly hydrophilic.For example, 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 keep 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.
As described above, silicon systems active material-polymer adhesive combination is formed by pre-dispersed slurry, the pre-dispersed slurry Material is by by conductive material and silicon systems active material and the particle surface for being adsorbed to silicon systems active material but having low-down The hydrophilic polymer of electrolyte wetability is carried out pre-dispersed and is prepared.That is, holding to use with high charge/electric discharge The silicon systems active material of amount, it is important that inhibit the volume expansion of the silicon systems active material due to caused by charge/discharge, and The volume expansion of silicon systems active material is suppressed and being adsorbed to the polymer adhesive of silicon systems active material.
Then pre-dispersed slurry is mixed with carbon system active material to be prepared as negative electrode slurry.Include carbon system activity in use When the negative electrode active material of material and silicon systems active material prepares cathode, by only by silicon systems active material and conductive material and gathering It closes that object adhesive is pre-dispersed to prepare pre-dispersed slurry, can effectively inhibit the volume expansion of silicon systems active material.
That is, by the way that conductive material and polymer adhesive are being included carbon system active material and silicon systems activity material Dispersed in the negative electrode active material of material come in the case where preparing negative electrode slurry, when mixed polymer adhesive, polymer The absorption object of adhesive is not limited to silicon systems active material, but extends to carbon system active material.Therefore, polymer adhesive is inhaled The degree for being attached 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 of the manufacture secondary battery cathode of embodiment includes: to prepare the work of carbon system active material according to the present invention Sequence S100；Pre-dispersed slurry is prepared by mixing silicon systems active material, conductive material and polymer adhesive in a dispersion medium The process S200 of material；The process for preparing negative electrode slurry by mixing the pre-dispersed slurry and carbon system active material S300；The process S400 negative electrode slurry of preparation being applied on current-collector；And by removing water from the negative electrode slurry Divide to form the process S500 of cathode.
Herein, prepare the process S100 of carbon system active material and by mixing silicon systems active material in a dispersion medium, leading Electric material and polymer adhesive prepare the process S200 of pre-dispersed slurry each other not in the relationship of time sequencing.It can be The process S100 for implementing to prepare carbon system active material implements the process for preparing pre-dispersed slurry S200 later, or can implement The process S200 for preparing pre-dispersed slurry implements to prepare the process S100 of carbon system active material later.Prepare carbon system active material Process S100 and the process S200 for preparing pre-dispersed slurry can be carried out simultaneously.
In the process S100 for preparing carbon system active material, prepare the carbon system active material of pulverulence first.Herein, make For carbon system active material, the various carbon-based materials that can absorb and release lithium 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, the decentralized medium of such as water is added to the mixing In object and stir to prepare pre-dispersed slurry.Water is added into mixture and stirring can be by rotation speed as known in the art Spend saw blade formula mixer such as homogenizer, omnipotent blender, the clarifying mixer (clear more than 2000rpm to 2500rpm Mixer) and filling mixer (fill mixer) either executes mixing by filling the packing material of such as pearl thereto Equipment such as ball mill, 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 and polymer adhesive combine Combination and the conductive material are dispersed in the water as decentralized medium, form pre-dispersed slurry.
Herein, 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, viscosity is limited Range.Pre-dispersed slurry can have the viscosity of 3000cp to 10000cp.That is, the viscosity in pre-dispersed slurry is small In the case where 3000cp, the rate of settling of silicon systems active material increases, so that the particle of silicon systems active material is in pre-dispersed slurry The period of resting of material sinks rapidly, and the physical property of pre-dispersed slurry is caused to deteriorate.It is greater than in the viscosity of pre-dispersed slurry In the case where 10000cp, the dispersibility of pre-dispersed slurry is reduced, and the operability for executing process becomes very low.
Fig. 1 is the figure for showing viscosity and changing with the solid content of pre-dispersed slurry.Fig. 2 is display settling height with pre- point The figure for dissipating the solid content of slurry and changing.In fig 1 and 2, it will be used as an example to wherein polymer adhesive to silicon systems activity The case where the ratio between material is 1:0.34 is described.
As shown in Figure 1, wherein polymer adhesive to the ratio between silicon systems active material be 1:0.34 in the case where, work as solid When total weight of the content based on pre-dispersed slurry is the value of 17.5~20.5 weight %, the viscosity of pre-dispersed slurry is 3000~ 10000cp.Therefore, wherein polymer adhesive to the ratio between silicon systems active material be 1:0.34 in the case where, pre-dispersed slurry Appropriate solid content be confirmed as the value of 17.5~20.5 weight %.
In Fig. 2, after preparing pre-dispersed slurry to the ratio between silicon systems active material with polymer adhesive for 1:0.34, By one quantitative collection in the bottle that can measure length, and measure the height of the bottom surface of pre-dispersed slurry.Thereafter, in room Post-processing 24 hours is carried out under temperature, 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 degree settled within a certain period of time in a manner of ratio. It here, is, when batch micro operations secondary battery cathode, to be provided and stopped according to process the reason of measurement sedimentation layer height after 24 hours Off period, and be usually 12 hours to 24 hours during resting.Therefore, the height of settled layer is measured after 24 hours.
As shown in Fig. 2, wherein polymer adhesive to the ratio between silicon systems active material is 1:0.34 in the case where, when pre- point When dissipating the solid content of slurry based on the value that the total weight of pre-dispersed slurry is 17.5~20.5 weight %, it can be seen that settled layer Ratio within 3%.It can be seen that wherein pre-dispersed slurry solid content be 17.5 weight % or more situation Under, pre-dispersed slurry has the viscosity of 3000~10000cp, allows to effectively realize silicon systems active material and polymer is viscous The sedimentation of mixture.
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 3000~10000cp.As noted previously, as the weight based on silicon systems active material can be with The amount of 25~45 weight % includes polymer adhesive, in order to make the viscosity of pre-dispersed slurry in the range met the above range Interior, pre-dispersed slurry can have the solid content of 15~25 weight % based on total weight.
In the process S300 for preparing negative electrode slurry, when preparing pre-dispersed slurry by above-mentioned operation, by that will divide in advance Slurry and the mixing of carbon system active material are dissipated to prepare negative electrode slurry.By preparing pre-dispersed slurry as described above, and by that will make Standby pre-dispersed slurry mixes to prepare negative electrode slurry with carbon system active material, so as to by polymer adhesive selectively It is adsorbed on the surface of silicon systems active material.That is, the surface of silicon systems active material usually has a hydrophily, and it is to be mixed poly- Closing object adhesive includes hydrophilic polymer material, to effectively be attached to silicon systems using strong hydrogen bond force and Van der Waals force The surface of active material allows to be formed silicon systems active material-polymer adhesive combination.
Herein, negative electrode slurry can have the solid content of 40~50 weight % based on total weight.Namely based on pre-dispersed slurry The total weight of material, pre-dispersed slurry has the solid content of 15~25 weight %, and passes through mixing carbon system active material, cathode Slurry can have the solid content of 40~50 weight % based on the total weight of negative electrode slurry.By the way that the solid of negative electrode slurry is contained Amount is kept within the above range, can improve operability while applying, while improving the drying that water is removed from negative electrode slurry Rate.
In the process S400 being applied to negative electrode slurry on current-collector, it will be made in the process S300 for preparing negative electrode slurry Standby negative electrode slurry is applied on current-collector.Herein, in general, the current-collector with a thickness of 3 μm~500 μm can be used, and do not have There is special limitation, as long as it is with high conductivity without causing chemical change in the secondary battery.For example, can make With: copper, stainless steel, aluminium, nickel, titanium, the processed aluminium of sintering carbon or surface carbon, nickel, titanium or silver etc. or stainless steel.
Implement to be formed the process S500 of cathode 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>
It is respectively 90 weight % and 10 weight % with the total weight based on negative electrode active material as negative electrode active material Amount uses carbon system active material and silicon systems active material.
By as the carbon black dispersion of conductive material in the water as decentralized medium, and as a whole by negative electrode active material It is mixed into wherein.It then, will be as the carboxymethyl cellulose of thickener (CMC) and as the styrene-butadiene rubber of adhesive Glue (SBR) is successively mixed to prepare negative electrode slurry, and negative electrode slurry is applied on current-collector and is dried secondary to be formed Negative electrode battery.
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.
Herein, the load capacity of the secondary battery cathode of comparative example 1 is 204mg/25cm2, and its porosity is 33.9%.
<comparative example 2>
It is respectively 90 weight % and 10 weight % with the total weight based on negative electrode active material as negative electrode active material Amount uses carbon system active material and silicon systems active material.
By as the carbon black dispersion of conductive material in the water as decentralized medium, and as a whole by negative electrode active material It is mixed into wherein.Then, polymer adhesive is added to it to prepare negative electrode slurry, and negative electrode slurry is applied on current-collector And it is dry to form secondary battery cathode.
The secondary battery cathode is by the negative electrode active material of 95.6 weight %, the conductive material and 3.4 of 1.0 weight % The polymer adhesive of weight % is formed.
Herein, the load capacity of the secondary battery cathode of comparative example 2 is 203mg/25cm2, and its porosity is 34.1%.
<embodiment 1>
It is respectively 90 weight % and 10 weight % with the total weight based on negative electrode active material as negative electrode active material Amount uses carbon system active material and silicon systems active material.
It will be pre-dispersed in as the carbon black of conductive material, silicon systems active material and polymer adhesive as decentralized medium To prepare pre-dispersed slurry in water, and carbon system active material is mixed to prepare negative electrode slurry.Thereafter, negative electrode slurry is applied It is applied on current-collector and dry to form secondary battery cathode.It herein, first will be based on the pre- of 26.4 weight % of total weight Dispersed paste is mixed with carbon system active material to prepare a negative electrode slurry, then by a negative electrode slurry of preparation and remaining The pre-dispersed slurry of 73.6 weight % is further mixed to prepare secondary negative electrode slurry.Secondary negative electrode slurry is used as final bear Pole slurry.
The secondary battery cathode is by the negative electrode active material of 95.6 weight %, the conductive material and 3.4 of 1.0 weight % The polymer adhesive of weight % is formed.
Herein, the load capacity of the secondary battery cathode of embodiment 1 is 200mg/25cm2, and its porosity is 34.8%.
<embodiment 2>
It is respectively 90 weight % and 10 weight % with the total weight based on negative electrode active material as negative electrode active material Amount uses carbon system active material and silicon systems active material.
It will be pre-dispersed in as the carbon black of conductive material, silicon systems active material and polymer adhesive as decentralized medium To prepare pre-dispersed slurry in water, and carbon system active material is mixed to prepare negative electrode slurry.Thereafter, negative electrode slurry is applied It is applied on current-collector and dry to form secondary battery cathode.Herein, using pre-dispersed slurry and carbon system active material as whole Body mixing, for use as final negative electrode slurry.
The secondary battery cathode is by the negative electrode active material of 95.6 weight %, the conductive material and 3.4 of 1.0 weight % The polymer adhesive of weight % is formed.
Herein, the load capacity of the secondary battery cathode of embodiment 2 is 205mg/25cm2, and its porosity is 34.2%.
Fig. 3 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 3, being higher than 1 He of embodiment to the adhesion strength of current-collector in the case where comparative example 1 and comparative example 2 Embodiment 2.However, comparative example 1, comparative example 2, embodiment 1 and embodiment 2 are confirmed as the adhesion strength with certain level.
[table 1]
Table 1 shows that initial charge and electric discharge by implementing 0.05C/0.05C are recycled twice to confirm that charge/discharge holds The result of amount and charge/discharge efficiency.
As shown in table 1, the charging/discharging capacity in comparative example 1 and charge/discharge efficiency are minimum.Embodiment 1 the case where Under, it is 470mAh or more that the 1st circulation, which is initial discharge capacity, and in the case where embodiment 2, charge/discharge efficiency is 87% or more.Compared with comparative example 2, embodiment 1 has the discharge capacity being more dominant, and confirmed that embodiment 2 has highest Charge/discharge efficiency.
[table 2]
Table 2 shows that the discharge capacity confirmation of discharge capacity and 0.1C based on 0.5C, 1.0C, 2.0C, 3.0C, 4.0C is each The result of the discharge rate (discharge rate) of a discharge capacity.
As shown in table 2, comparative example 1 shows low discharge rate performance in a manner of identical with above-mentioned table 1.
That is, in the carboxymethyl cellulose (CMC) used as thickener and as the SBR styrene butadiene rubbers of adhesive (SBR) it in the case where, clearly illustrates, the volume expansion of silicon systems active material and the breakage of conductive network cannot be prevented.
Fig. 4 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 figure 4, when carrying out life assessment by the charging and discharging for carrying out 50 circulations at 0.5C/0.5C When, it can be seen that the service life of comparative example 1 is low, this is because volume expansion is absolutely not suppressed.In contrast, when using poly- When closing object adhesive, there are advantages for life characteristic.Particularly, it is able to confirm that, compared with comparative example 1 and comparative example 2, uses pre- point The embodiment 1 and embodiment 2 for dissipating slurry show high life characteristic.
Fig. 5 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 5, in the case of comparative example 1, the original depth of electrode and fully charged thickness are respectively 56.3 μm With 81.0 μm, and the fully charged thickness change of electrode is measured as 43.9%.In addition, in the case where comparative example 2, electrode Original depth and fully charged thickness be respectively 56.5 μm and 83.6 μm, and the fully charged thickness change measurement of electrode It is 48.0%.
On the other hand, in the case of example 1, the original depth of electrode and fully charged thickness be respectively 56.2 μm and 84.3 μm, and the fully charged thickness change of electrode is measured as 50.0%.In addition, in the case where embodiment 2, electrode Original depth and fully charged thickness are respectively 57.1 μm and 81.3 μm, and the fully charged thickness change of electrode is measured as 42.4%.
Herein, when confirming fully charged thickness change after 50 circulations are evaluated, comparative example 1 shows low thickness Spend expansion rate.However, in the case of comparative example 1, the low-down service life is gone out due to above-mentioned life assessment as the result is shown, it cannot Find out that the performance of silicon systems active material is shown.On the other hand, embodiment 1 shows the thickness of level similar with comparative example 2 Expansion rate, and in the case where embodiment 2, it is able to confirm that it shows low-down thickness swelling.
From the result, it can be seen that when compared with comparative example 1 and comparative example 2, in 2 the two of embodiment 1 and embodiment The life characteristic of secondary cell is all improved, and when preparing negative electrode slurry, passes through a negative electrode slurry and two wherein In the case that secondary negative electrode slurry prepares the embodiment 1 of final negative electrode slurry, the adhesion strength to current-collector can be improved.Wherein It, can in the case where preparing the embodiment 2 of negative electrode slurry by mixing pre-dispersed slurry with carbon system active material as a whole To be effectively reduced thickness swelling.
That is, embodiment is related to according to the present invention secondary battery cathode and its manufacturing method, by using wherein using The active material of silicon systems obtained by silicon systems active material-polymerization is adsorbed in the polymer adhesive for inhibiting silicon systems active material to expand Object adhesive combination, can effectively inhibit the volume expansion of silicon systems active material.
In addition, in the case where negative electrode active material of the use comprising both carbon system active material and silicon systems active material, Pre-dispersed slurry is prepared by the way that silicon systems active material to be pre-dispersed in polymer adhesive, so that polymer adhesive can be with It is selectively adsorbed to strong adhesion strength on the surface of silicon systems active material.
That is, restrained effectively the volume expansion of silicon systems active material, so as to improve the durable of secondary battery cathode Property, and the life characteristic of the electrochemical appliance by using cathode 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.