This patent application claims priority based on the Korea Patent Application No. 10-2016-0109272, filed on August 26, 2016 date. The present invention for the separator for an electrochemical device, the separation membrane is for electrochemical device comprising a separator and this for the puncture strength, heat stability, and improved adhesion electrode electrochemical device.
[2]
BACKGROUND
[3]
And the demand of the secondary battery is repeatedly charged and discharged is increased rapidly as the energy source, as a portable electronic device is developed such as cellular phones and laptop computers. In recent years, the use of the secondary battery is realized as a power source for a hybrid electric vehicle (HEV), electric vehicles (EV). Thus, there is much research being done for a secondary battery which can meet a variety of requirements, in particular, the trend, the demand for lithium secondary batteries having a high energy density, high discharge voltage and a higher output.
[4]
[5]
One of the major research project of an electrochemical device such as this secondary battery is improved in the safety. For example, the electrochemical device is ignited, or may cause an explosion if overheating when overcharged beyond the internal short circuit or the allowed current and voltage lead to thermal runaway or severe. Imparting a shutdown function to a separator in order to prevent this, or in the case of a cylindrical battery and may use a PTC (Positive temperature coefficient) (Current interrupt device) element, a CID element. However, the shutdown function is exhibited across the board from the separator is the cathode and the anode or completely isolated, the time can be delayed until the PTC device / CID device is activated. Therefore, technology development is necessary with regard to improved safety for the overheating of the electrochemical device.
[6]
Detailed Description of the Invention
SUMMARY
[7]
Accordingly, an object of the present invention is to provide a heat-resistant stability and puncture strength is enhanced electrochemical device as a separator for to solve the above technical problem. Other objects and advantages of the other invention will be readily appreciated that this can be realized by the means as claimed and combinations thereof.
[8]
Problem solving means
[9]
The present invention provides a separator for an electrochemical device for solving the aforementioned technical problem. SUMMARY A first aspect of the present invention for the separation membrane, the separation membrane is a porous polymer substrate comprising a polymer resin; And a porous coating layer formed on at least one surface of both surfaces of the porous polymeric base material; wherein the said porous coating layer here is the up to the upper portion from the lower portion near the porous polymer substrate based on the direction of its thickness a) inorganic particles this stepwise or successively increased amount of, and the porous polymer from the bottom close to the base content of the inorganic particles to the b) from the upper portion decreases in a stepwise or sequentially. Here, the a) inorganic particles will the plate-shaped inorganic particles, b) inorganic particles is spherical inorganic particles. The method of claim wherein the first side of the second side is of the present invention, the porous coating layer is part of the to a thickness of 10% from the lower portion near the porous polymer substrate based on the thickness direction is high and the amount of b) of the inorganic particles, the porous coating layer portion of thickness up to 10% from the surface is to a high content of the inorganic particles a).
[10]
The third aspect of the first and second apparatus according to any one of the side portion of the porous coating layer to a thickness of 10% from the lower portion near the porous polymer substrate based on the direction of the thickness thereof of the present invention the inorganic particles a) and b a) total amount of contrast b) inorganic particles of not less than 100% by weight to 50% by weight.
[11]
The fourth side is the first and the third according to any one of the side portion of the porous coating layer to a thickness of 10% from the surface of the porous coating layer, which faces the electrode on the basis of the direction of the thickness thereof of the present invention the inorganic particles a) a and b) the content of inorganic particles compared to a total 100% by weight) of not less than 50% by weight.
[12]
A fifth aspect of the present invention according to any one of the first and fourth side faces, wherein a) plate-shaped inorganic particles is in the above 3 to 100 aspect ratio (aspect ratio).
[13]
A method according to any one of the sixth aspect of the first and fifth aspect of the invention, the a) plate-shaped inorganic particles is a boehmite.
[14]
A method according to any of the seventh aspect of the first and sixth aspect of the invention one, wherein b) the spherical inorganic particles is in the aspect ratio (aspect ratio) 1 to 3.
[15]
An eighth aspect of the present invention according to any one of the first and seventh aspects, wherein the porous coating includes: a) plate-shaped inorganic particles, b) comprises a mixture of spherical inorganic particles, and a binder resin, the binder of the porous coating layer to the content of the resin is 3 to 10% by weight.
[16]
A method according to any one of the ninth aspect has the first and eighth aspect of the invention, the membrane is greater than the perforation strength of 0.26kgf.
[17]
Further, the tenth aspect of the present invention includes a separator disposed between the as of the electrochemical device, the electrochemical device is a positive electrode, a negative electrode and the positive electrode and the negative electrode, wherein the negative electrode comprises lithium metal, the separation membrane is to a separation membrane according to any one of the above first aspect to ninth aspect.
[18]
Further, an eleventh aspect of the invention, the porous polymer substrate comprises a polymer resin; And a porous coating layer formed on at least one surface of both surfaces of the porous polymeric base material; wherein the said porous coating layer here is a) plate-shaped inorganic particles and b) comprises a spherical inorganic particles, the porous coating layer is a direction thickness thereof portion of the to a thickness of 10% from the lower portion near the porous polymer substrate based on the inorganic particles a) often more the content of the prepared inorganic particles b), part of the thickness up to 10% from the surface of the porous coating layer to face the electrode inorganic particles a) with the will of the separator for an electrochemical device is at least 100% of the sum a) the content of inorganic particles and 50% by weight of b).
[19]
Further, the twelfth aspect of the present invention, a porous polymer substrate comprising a thermoplastic resin; And a porous coating layer formed on at least one surface of both surfaces of the porous polymer substrate; comprises, here, the porous coating layer comprising inorganic particles and a binder resin, and to the inorganic material particles with a binder resin as a medium that binder and / or surface will the binder is integrated, the porous coating layer a), but with an aspect ratio of 3 is more than 20 or less plate-shaped inorganic particles, and b) the aspect ratio comprises a spherical inorganic particles of from 1 to 3, wherein the porous coating layer is, based on the direction of the thickness thereof part of the inorganic particles a) often more the content of the prepared inorganic particles b), portions of up to a thickness of 10% from the surface of the porous coating layer facing the electrode from the bottom close to the porous polymeric substrate to a thickness of 10% of inorganic particles a) and b) compared to 100% by weight of the sum of a) is based on a content of the inorganic particles is 50 wt%, the aspect ratio [length of major axis / Would be defined in the axial direction perpendicular to the width direction], it is for a separator for an electrochemical device.
[20]
Effects of the Invention
[21]
The invention has an effect of inhibiting the growth of Den drive STE from the cathode it is of plate-shaped inorganic particles are distributed in a surface of the membrane is prevented by the perforated dendrites. In addition, since the spherical inorganic particle number distribution near the surface of the polymer film substrate it is improved interfacial adhesion of the polymer base film and a porous coating layer. The electrochemical device comprising the separator according to the invention is improved in accordance with the safety in use.
[22]
Brief Description of the Drawings
[23]
Following figures attached to this specification are intended to illustrate preferred embodiments of the present invention, the components which serve to further understand the teachings of the present invention with the content of the above-described invention, the invention is only to details set forth in those figures is limited shall not be interpreted.
[24]
Figure 1 illustrates a cross-section of the separation membrane according to the specific exemplary embodiments of the present invention.
[25]
Figure 2a and Figure 2b is a SEM image showing a cross-section of the separation membrane according to an embodiment of the invention.
[26]
2c is a SEM image showing the surface of a separation membrane according to an embodiment of the invention.
[27]
Figure 3 is a SEM photograph showing a cross-section of a separation membrane according to COMPARATIVE EXAMPLE 1 of the present invention.
[28]
Figures 4a and 4b is a SEM photograph showing a cross-section of a separation membrane according to Comparative Example 2 of the present invention.
[29]
Figures 5a and 5b is a SEM image showing the spherical particles used in the examples and comparative examples of the present invention.
[30]
Figures 6a and 6b is the SEM image showing the plate-shaped particles used in the Examples and Comparative Examples of the present invention.
[31]
Mode for the Invention
[32]
That the description and the terms used in the claims is general and not be construed as limited to the dictionary meanings are not, the inventor can adequately define terms to describe his own invention in the best way It interpreted based on the meanings and concepts corresponding to technical aspects of the present invention on the basis of the principle. Therefore, the configuration shown in the embodiments described herein are a variety of equivalents that in not intended to limit the scope of the present and only one embodiment the most preferred of this invention, it can be made thereto according to the present application point it should be understood that there may be an example water and modifications.
[33]
[34]
Throughout the present specification, when that any part is "connected" with another part, which includes some cases if it is "directly connected to", as well as sandwiched between the other element or intervening elements are "electrically connected" .
[35]
[36]
The present invention for the separator for an electrochemical device, the membrane comprises a porous substrate and a porous coating layer formed on at least one surface of both surfaces of the porous substrate. In the present invention, the porous coating comprises a) inorganic plate-shaped particles, b) a mixture of spherical inorganic particles, and a binder resin. In a specific exemplary embodiment of the present invention, the porous coating layer upper portion close to the electrode facing portion of the porous coating layer are inorganic particles of the plate-shaped inorganic particles are mainly distributed, and near lower layer and the porous substrate facing portion is mainly distributed spherical inorganic particles of the inorganic material particles do. In the present invention "mainly distribution" means means that accounts for more than 50% by weight.
[37]
Figure 1 illustrates a cross-section of the separation membrane according to the specific exemplary embodiments of the present invention. On this reference, a detailed description of the present invention.
[38]
[39]
Referring to Figure 1, the separator 100 according to one specific embodiment of the present invention comprises a porous substrate 110 and the porous coating (120) provided on at least one side of the porous substrate.
[40]
[41]
In the present invention, the porous substrate is not intended to be because it contains a thermoplastic resin having an electrically insulating and electrochemically stable, and so long as stable in the electrolytic solution to be described later particularly limited. In a specific embodiment of the present invention to the thermoplastic resin, for example, for example, polyolefins such as polyethylene (PE), polypropylene (PP), ethylene-propylene copolymers; Polyesters such as polyethylene terephthalate, co-polyester; And the like. Especially, the workability is also good in low-cost polyolefin materials are preferred. The volume of the thermoplastic resin in the entire composition of the porous base material is 50 vol% or more, or 70% by volume or more, or 90% by volume.
[42]
[43]
In a specific exemplary embodiment of the invention, the porous substrate may comprise a porous polymer film or a porous polymeric non-woven fabric. For example, it is a porous polymer film or a porous polymeric non-woven fabric comprising a polyolefin such as polyethylene, polypropylene. In the present invention, the polyolefin porous polymer film may be to, for example expressing the shutdown function at a temperature of 80 to 130 ℃.
[44]
At this time, polyolefin porous polymer film is a high density polyethylene, linear low density polyethylene, low density polyethylene, polyethylene such as ultra high molecular weight polyethylene, polypropylene, polybutylene, polymethyl pentene, such as the polyolefin-based polymers each alone or these mixed polymers of two or more It can be formed.
[45]
[46]
In addition, the porous polymer film may be made by molding into a film using a variety of polymers such as polyester in addition to the polyolefin. In addition, the porous polymer film may be formed of a stacked film layers at least two layers, each film layer may be formed of a mixture alone or in these polymers, such as the above-described polyolefins, polyesters of two or more polymers have.
[47]
[48]
In addition, the porous polymer film and a porous non-woven fabric is polyethylene terephthalate (polyethyleneterephthalate) in addition to the polyolefin described above, polybutylene terephthalate (polybutyleneterephthalate), polyester (polyester), polyacetal (polyacetal), polyamide (polyamide), a polycarbonate (polycarbonate), polyimide (polyimide), polyether ether ketone (polyetheretherketone), polyether sulfone (polyethersulfone), polyphenylene oxide (polyphenyleneoxide), polyphenylene sulfide (polyphenylenesulfide), polyethylene naphthalene (polyethylenenaphthalene), etc. each may be formed of a single polymer or a mixture thereof.
[49]
[50]
Next will be described a porous coating.
[51]
[52]
In a specific exemplary embodiment of the present invention, the porous coating includes a mixture of as being formed at least on one surface of the porous base material, inorganic particles and a binder resin. In the present invention, the content of the binder resin of the porous coating layer is from 1 to 10% by weight compared to 100% by weight of the porous coating layer. The content of the binder resin of the porous coating layer according to one preferred embodiment of the present invention is less than 1 wt%, or 2 wt%, or 5 wt%. The content of the binder resin of the porous coating layer according to one preferred embodiment of the present invention can be up to 5% by weight of 7 wt% or less. In the present invention, wherein the porous coating layer serves as a skeleton of the membrane if as to the porous coating is responsible for giving the heat resistance to the separator, for the example battery internal temperature is raised in a fear that the porous substrate shrinkage occurs there is thermal contraction of the porous coating layer can be suppressed.
[53]
[54]
In the present invention, the porous coating layer is porous the inorganic particles have the coating layer as a point binder and / or surface is the binding integrated layer with the binder resin, the medium is due to the interstitial volume (interstitial volume) between the inorganic particles It has the following structure. By forming such a porous coating layer is not only possible to achieve planarization of the electrode surface as it is possible to improve the heat resistance of the above-described porous base
[55]
[56]
In a specific exemplary embodiment of the invention, the inorganic particles as stable electrochemically, the operation voltage range of an electrochemical device to be applied (e. G., Li / Li + reference to 0 ~ 5 V) oxide and / or a reduction in it does not occur is preferred. In particular, as the inorganic particles, it is preferable to use inorganic particles with high dielectric constant in this case, because the electrolyte salt can contribute to the liquid electrolyte, such as increased dissociation of lithium salts to increase the ionic conductivity of the electrolyte. Further, the inorganic particles will have the heat resistance and electrical insulation is a heat-resistant temperature not less than 150 ℃, when applied to a cell is preferably stable with respect to solvent used in the manufacture of electrolyte or membrane. Heat-resistant temperature of more than 150 ℃ herein is to mean that you can not see the variation of softening, etc. In at least 150 ℃.
[57]
[58]
In the present invention, the porous coating layer is included as the inorganic particles a) a plate-shaped inorganic particles, and b) a spherical inorganic particles. The porous coating layer according to specific exemplary embodiments of the present invention is above the a) is increased in steps or in gradually the content of the inorganic particles, based on down to the thickness direction of the porous coating layer from the porous substrate near the bottom. Further, ranging from close to the porous substrate underlying the upper b) the content of the inorganic particles decreases stepwise or gradually.
[59]
In a specific exemplary embodiment of the present invention, the porous coating layer may be a double-layer structure of upper and lower layers. At this time, the upper layer may be a plate-shaped inorganic particles are inorganic particles 100 weight% of 50 wt% or more, 60% or more by weight and 70% by weight or more, 80% or more, or at least 90%, or 99.9% by weight. Further, the lower layer may be a spherical inorganic particles are inorganic particles 100 weight% of 50 wt% or more, 60% or more by weight and 70% by weight or more, 80% or more, or at least 90%, or 99.9% by weight.
[60]
That is, the porous coating layer according to the present invention, and spherical inorganic particles of the inorganic material particle side facing portion of the porous substrate is a number distribution, to the surface of the porous coating layer, i.e., the electrode facing portion side plate-shaped manner that the inorganic particles have a number distribution of the inorganic particles are distributed and it characterized in that.
[61]
[62]
Upper (上方) relative to the thickness from the side facing the porous substrate (porous substrate facing portion) of the porous coating layer to technology effective for the constructive features of the separators 50%, 30%, 20% or 10% or less according to the invention the part that refers bottoms. Further, the surface portion of the porous coating layer, i.e., the lower side (下方) portion is at least 50%, 30%, 20% or 10%, based on the thickness from the negative electrode face to face the electrodes are referred to as upper part. Also a portion a portion represented by reference numeral 122-1 is displayed in the upper part, and reference numeral 121 denotes a lower layer portion.
[63]
[64]
In the present invention, according to a further preferred embodiment the porous coating layer is the upper part is high, the amount of the spherical inorganic particles b) of the inorganic material particles, the lower layer has a high content of the inorganic particles a) plate-shaped inorganic particles. According to one specific embodiment of the invention, the lower layer are inorganic particles a) a plate-shaped inorganic particles and b) the content of the spherical inorganic particles 100% by weight of the sum of the spherical inorganic particles compared to b) is at least 50% by weight. Further, the upper layer is the inorganic particles a) a plate-shaped inorganic particles with b) 100% by weight of the sum of the spherical inorganic particles compared to a) the content of the plate-shaped inorganic particles is less than 50% by weight.
[65]
[66]
In a specific exemplary embodiment of the invention, the plate-shaped inorganic particles is less than or equal to 20 aspect ratio (aspect ratio) of 3 or less than 100, or greater than 50 3 or less, or more than three. In the present invention, the aspect ratio (aspect ratio) can be expressed by [width in a direction perpendicular to the length / long axis of the major axis direction. In the syntax of an embodiment of the invention, the plate-shaped inorganic particles include, but are not particularly limited, which satisfy the aforementioned conditions, for example, boehmite (AlOOH) and / or magnesium hydroxide (Mg (OH) 2 ) in it is desirable. The aspect ratio, length, and width in the major axis direction, for example, can obtain the images taken by the scanning electron microscope (SEM) by image analysis. Furthermore, in the specific exemplary embodiment of the invention, the plate-shaped inorganic particles have a particle size on the basis of the long axis (D 50 is a) 0.5㎛ to 10㎛, or 0.5㎛ to 5㎛, or 0.5㎛ to 2㎛ will be.
[67]
[68]
(A) the plate-shaped inorganic particles in the porous coating layer, particularly flat surface is desirable for the surface of the porous substrate having an average angle of 30 ° or less than 0 ° in the lower layer portion. (A) may exist in the form of plate-shaped inorganic particles can prevent internal short circuit that could be caused by lithium dendrite or the projection of the active material of the electrode surface to deposit on the electrode surface, by orienting the particles so that the state such as an electric more effectively. On the other hand, the presence in the form of a porous coating layer (a) plate-shaped inorganic particles can be grasped by observing the cross section of the separator by the SEM.
[69]
[70]
In the present invention, (b) a spherical inorganic material particle is the aspect ratio (aspect ratio) 1 to 3. In the present invention, spherical particles is in the form of a spherical or similar sphere. Similar as spherical to herein includes all forms of particles such as the cross-sectional area of the particles round, oval, rectangular or In the form as having a three-dimensional volume having the shape of a closed curve not specifically amorphous equivalent. The spherical inorganic particles (b) above according to the present invention ruthless examples BaTiO 3 , hafnia (HfO 2 ), SrTiO 3 , SnO 2 , CeO 2 , MgO, NiO, CaO, ZnO, ZrO 2 , SiO 2 , Y 2 O 3 , Al 2 O 3 , SiC, and TiO 2 may be one or two or more kinds of mixtures selected from the group consisting of. In addition, the spherical inorganic particles, particle diameter (D 50) Is not less than 0.01μm or more, based on the long axis of the particles, at least 0.05μm, 0.1μm or more, or more than 0.3 μm, or 0.5μm. If the particle diameter of the spherical inorganic particles falls short significantly in the above range, the pore size of the porous coating layer can be made small lower the air permeability. On the other hand, is a fear that the diameter of the spherical inorganic particles is too large, the heat resistance improvement effect of the porous coating decreases's particle size of the spherical particles (D 50 is not more than) is 15μm or less, 5μm or less, or 1μm or 2μm.
[71]
[72]
Particle diameter (D of the particles according to the invention 50 ) is a common particle size by a distribution system to measure the particle size distribution of the particles after classification, a particle size of 50% accumulated value from small diameter side is calculated on the basis of the measurement result (D50 ) it means. The particle size distribution may be measured by the intensity of the diffraction patterns and scattering of light is generated by abutting a particle, such particle size distribution to Step is illustrated for example the micro-track or 9220FRA Microtrac HRA of nitki Sosa claim.
[73]
[74]
On the other hand according to a specific exemplary embodiment of the present invention, the inorganic particles in the porous coating layer may have all or at least a secondary particle structure in which some of the primary particles are aggregated. This the more excellent short circuit prevention effect can be obtained from, and also has an effect of preventing the adhesion of the particles to some extent by maintaining a high level of ion permeability of the porous coating layer can maintain it suitably the pores of the particles.
[75]
[76]
In the present invention, the binder resin so that the inorganic particles to the binder and between the binder particles and the porous substrate. In addition, it is possible to contribute to the interfacial adhesion of the membrane and the electrode. According to a specific exemplary embodiment of the invention, the binder resin is polyvinylidene fluoride-hexafluoropropylene (polyvinylidene fluoride-cohexafluoropropylene), polyvinylidene fluoride-trichlorethylene (polyvinylidene fluoride-cotrichloroethylene), poly methylmethacrylate methacrylate (polymethylmethacrylate), polyethyl acrylate, polymethyl acrylate, polybutyl acrylate (polybutylacrylate), polyacrylonitrile (polyacrylonitrile), polyvinylpyrrolidone (polyvinylpyrrolidone), polyvinyl acetate (polyvinylacetate), ethylene vinyl acetate copolymers (polyethylene-co-vinyl acetate), polyethylene oxide (polyethylene oxide), polyarylate (polyarylate), cellulose acetate (cellulose acetate), cellulose acetate butyrate (cellulose acetate butyrate), cellulose acetate propionate (cellulose acetat epropionate), cyanoethyl pullulan (cyanoethylpullulan), cyanoethyl polyvinyl alcohol (cyanoethylpolyvinylalcohol), cyanoethyl cellulose (cyanoethylcellulose), cyanoethyl sucrose (cyanoethylsucrose),
[77]
Separation membrane according to the present invention can be heat-resistant in use safety characteristics from the configuration described above. That is, the spherical inorganic particles, so that the surface coated by a uniform distribution such that on a surface portion of the porous base material is excellent in interfacial adhesion between the porous substrate features. In addition, the upper part of the electrode facing portion so that it is configured plate-shaped particles are distributed and Den deurayideu growth is suppressed, and the effect the piercing strength of the dendrite is improved. Separation membrane according to the present invention is a puncture strength by being a plate-shaped inorganic particles in the surface distribution is ensured by at least about 0.26kgf. As used herein, the puncture strength (puncture strength) is risk from the exterior, for example, the resistance of the separator for the penetration of a foreign object. A counter unit uses gf or kgf, it can be used interchangeably as the penetration strength or penetration strength. The higher the value is typically a low internal short-circuit defective rate of the separator. This penetration test is for example given by the vertical through a needle having a diameter at a predetermined speed against a membrane measured by applying a force binary case.
[78]
[79]
The present invention also provides a method for producing a separator having the features described above. Separation membrane production process according to the present invention may be described as follows.
[80]
[81]
First, prepare a porous substrate. Next, in preparing the second slurry and the third slurry for the first slurry, the upper part for the lower layer. The first slurry (for a lower layer) comprises inorganic particles and a binder resin, not less than the inorganic particles, or both spherical inorganic particles, spherical inorganic particles, or a contrast of 50% by weight of the total amount of inorganic particles. The second slurry (for upper layers) includes inorganic particles and a binder resin, wherein the inorganic particles is not less than all, or plate-shaped inorganic particles, or plate-shaped inorganic particles is 50% by weight compared to the total amount of inorganic particles. The third slurry (the intermediate position of the upper layer and lower layer) is as used to form the intermediate layer between the upper layer and the lower layer includes inorganic particles and a binder resin. In the intermediate layer the inorganic particles can be contained the same amount the plate-shaped inorganic particles and the spherical inorganic particles, or contain large amount of one or the other. Each of the slurry is a solvent for dispersing the inorganic particles and a binder is further contained. Further, the slurry may further contain a suitable additive as needed, thickeners, dispersants and the like.
[82]
[83]
When thus the porous substrate and each slurry is applied to thereby prepare a first slurry and the third slurry and the second slurry from the surface of the porous substrate in order and dried. The application of the slurry can be coated with a top layer slurry after drying a slurry of the lower layer. Or the coating of the slurry can be applied at the same time after the drying process is performed by wet on wet manner.
[84]
The third slurry as a random element, without applying the slurry In a third after the first slurry is applied to a specific one embodiment, it can be directly applied to the second slurry.
[85]
In a specific exemplary embodiment of the invention the coating method of the slurry dip coating, doctor coating may be used a known method such as blade coating, for example as shown in Figure 3 it is also possible simultaneously applied using a multi-slot die. However, the coating method and the coating method is not particularly limited.
[86]
[87]
In addition, the present invention provides an electrode assembly including a separator for the electrochemical device according to the invention. The electrode assembly according to the present invention comprises a separator interposed between the positive electrode, a negative electrode and the positive electrode and the negative electrode, the separator is in accordance with the present invention. If there is a porous coating is formed having the aforementioned features only one side of the porous base in the separator has the porous coating layer in the electrode assembly it is characterized in that it faces the negative electrode.
[88]
[89]
In a specific exemplary embodiment of the present invention, the positive electrode, for example, the general formula Li 1 + x Mn 2-x O 4 (where, x is from 0 to 0.33), LiMnO 3 , LiMn 2 O 3 , LiMnO 2 , etc. lithium manganese oxide; Formula LiNi 1 - x M x O 2 (where, the M = Mn, x = 0.01 ~ 0.3 Im) Ni site type lithium nickel oxide which is represented by; Formula LiMn 2 - x M x O 2　(where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li 2 Mn 3 MO 8　Lithium manganese composite oxide expressed by (where, M = Fe, Co, Ni , Cu or Zn); A portion of Li is substituted with alkaline earth metal ions formula LiMn 2 O 4 ; LiNi x Mn 2 - x O 4 and the like (0.01 ≤ x ≤ 0.6) may include a positive electrode active material.
[90]
[91]
Furthermore, in the specific exemplary embodiment of the present invention, the cathode has a cathode active material such as lithium metal, natural graphite, artificial graphite, expanded graphite, carbon fiber, I-graphitizable carbon, carbon black, carbon nanotube, fullerene carbon and graphite materials such as activated carbon; Compound including lithium and a metal such as alloys capable of Al, Si, Sn, Ag, Bi, Mg, Zn, In, Ge, Pb, Pd, Pt, Ti, and these elements; Metals and their compounds and composites of carbon and graphite materials; It includes lithium-containing nitrides and the like. Among them, it is preferable to include a lithium metal.
[92]
[93]
Further, in addition to the battery device is not described herein, for example, there are conventional elements used in the cell, particularly in a lithium secondary battery field may be used for such a conductive material, a binder resin, a liquid electrolyte.
[94]
[95]
It will now be described in more detail by way of example to the present invention. The following examples are provided for the purpose of eager to improve the understanding of the configuration of the present invention is not limited to the embodiment to the scope of the present invention.
[96]
[97]
1. Preparation of Membrane
[98]
[99]
Example 1
[100]
First, it was prepared a polyethylene porous polymeric base material (polyethylene, 7㎛ thickness, porosity 32%). Next, to prepare the first and second slurries. The first slurry is a solvent (distilled water: ethanol 95: 5 weight ratio mixture) alumina (Al 2 O 3 , D 50 : 0.5㎛) particles, polyacrylate (polyacrylate), and thickening agents to the CMC (carboxymethyl cellulose) 98: 1: It is mixed in a ratio of 1: 1. The aspect ratio of the alumina particles was used from 1 to 1.5. In addition, the second slurry in the solvent Mg (OH) 2 (D 50 : 1.1㎛,) is mixed in a ratio of 1: a, a polyacrylate thickener and a CMC 98: 1. The Mg (OH) 2 aspect ratio was used to be about 3.1 to 5. The content of the solid content in each slurry was 5%. The first and second slurries to prevent the agglomeration of inorganic particles, was added to the inorganic particles and the same amount of beads, wetting agents (wetting agent for reducing the contact angle of the bead, and a solvent, anionic compound, sodium sulfate <1% ) and using a paint shaker equipment was mixed two times 50 minutes each.
[101]
Doctors were using a blade coating device to the first slurry on the polymer substrate and dried using a dryer to prevent wall thickness disparity liquid by the surface tension of the solvent at room temperature. And it dried in the coating and the same method of the second slurry. In the obtained separation membrane was a lower layer and a thickness of about 3.8㎛ spherical particles are mainly distributed. Further, the upper layer was mainly the plate-like particle distribution and a thickness of about 3.0㎛.
[102]
[103]
Comparative Example 1
[104]
First, it was prepared a polyethylene porous polymeric base material (polyethylene, 7㎛ thickness, porosity 32%). Next, to prepare the first and second slurries. The first slurry is a solvent (distilled water: ethanol 95: 5 weight ratio mixture) alumina (Al 2 O 3 , D 50 : 0.5㎛) particles, polyacrylate (polyacrylate), and thickening agents to the CMC (carboxymethyl cellulose) 98: 1: It is mixed in a ratio of 1: 1. The aspect ratio of the alumina particles was used from 1 to 1.5. In addition, the second slurry in the solvent Mg (OH) 2 (D50: 1.1㎛) is mixed in a ratio of 1: a, a polyacrylate thickener and a CMC 98: 1. The content of the solid content in each slurry was 5%. On the other hand, the Mg (OH) 2 aspect ratio was used to be about 3.1 to 5.
[105]
The first and second slurries to prevent the agglomeration of inorganic particles, was added to the inorganic particles and the same amount of beads, wetting agents (wetting agent for reducing the contact angle of the bead, and a solvent, anionic compound, sodium sulfate <1% ) and using a paint shaker equipment was mixed two times 50 minutes each.
[106]
Doctor blade was used to equipment applying the second slurry on a polymer substrate and dried using a dryer to prevent wall thickness disparity liquid by the surface tension of the solvent at room temperature. And it dried in the coating and the same method the first slurry. The obtained separation membrane was in the lower layer is a plate-like particle and mainly distributed about 3.0㎛ thick. Further, the upper layer was about 3.2㎛ and the thickness of the spherical particles is mainly distributed.
[107]
[108]
Comparative Example 2
[109]
It was prepared a polyethylene porous polymeric base material (polyethylene, 7㎛ thickness, porosity 32%). The following were prepared for the porous coating. The slurry of alumina to solvent (acetone) (Al 2 O 3, D 50 were mixed in a ratio of 2:: 0.5㎛) particles, PVDF-HFP, and cyano binder to 9 (cyanoethylated poly [vinyl alcohol] ) in the series: 1 . The aspect ratio of the alumina particles was used from 1 to 1.5. Was the amount of solid content in the slurry was 18%. The slurry, in order to prevent the agglomeration of inorganic particles, the inorganic particles added with the same amount of beads and using a paint shaker equipment was mixed two times 50 minutes each. By impregnating the polymer base material to the slurry to obtain a separator having a porous coating layer formed by the method of dip coating.
[110]
[111]
2. The membrane characterization
[112]
1) the puncture strength test
[113]
Puncture strength was measured in the maximum load value when reoteul stuck to each of Examples and Comparative Examples membrane the speed 120mm / min by using a needle having a diameter of 1 mm (0.5 mmR). Example, Comparative Examples 1 and 2 was carried out the separation membrane perforation for different three parts for each, and showed the average value thereof.
[114]
[115]
TABLE 1
Up to sting strength (kgf) Example Comparative Example 1 Comparative Example 2
#1 0.2969 0.2766 0.2568
#2 0.2707 0.2719 0.2634
#3 0.2740 0.2759 0.2620
Average 0.2739 0.2748 0.2607

[116]
[117]
The experiment The results were confirmed to exhibit excellent puncture strength compared to Comparative Examples 1 and 2 for the separation membrane according to the embodiment. In particular, the separation membrane according to an embodiment was found to be improved about a puncture strength of about 5.1% compared to the membrane according to Comparative Example 2.
[118]
[119]
2) Heat resistance test
[120]
Embodiment, were prepared in Comparative Example 1 and Comparative Example 2, each sample (four-way 10cm) from the obtained separation membrane through 3 each. This was allowed to stand for 30 minutes in an oven of 150 ℃. The specimen was taken out from the oven and then determine the dimension, in comparison with the dimension of the first separator was confirmed that the shrinkage ratio of each of the separation membrane. The results are shown in Table 2 below.
[121]
[122]
TABLE 2
Area Reduction (%) Example Comparative Example 1 Comparative Example 2
Area reduction rate (&) Horizontal / vertical length of shrinkage (%) Area reduction rate (&) Horizontal / vertical length of shrinkage (%) Area reduction rate (&) Horizontal / vertical length of shrinkage (%)
Psalm 1 3.96 2 2 7.84 4 4 14.46 9 6
Psalm 2 3.96 2 2 10.7 5 6 14.46 9 6
Psalm 3 6.88 3 4 7.85 5 3 14.46 9 6
Average 4.93 2.33 2.67 8.80 4.67 4.33 14.46 9 6

[123]
[124]
The significantly higher heat resistance property in the separation membrane according to the embodiment, as can be seen from the above was found.
[125]
[126]
As described above, it has been described by, although exemplary embodiments of the invention, the invention is not limited thereto, the substrate under the technical scope of the present invention by one of ordinary skill in the art various modifications and variations within the equivalent scope of the claims to be possible as a matter of course.

WE Claims

Porous polymer substrate comprises a polymer resin; And a porous coating layer formed on at least one surface of both surfaces of the porous polymeric base material; wherein the said porous coating layer here is the up to the upper portion from the lower portion near the porous polymer substrate based on the direction of its thickness a) inorganic particles this stepwise or sequentially increased amount of, and, from the porous polymeric base material and near the bottom to the top b) a content of the inorganic particles stepwise or decreases sequentially, the here a) inorganic particles will the plate-shaped inorganic particles , b) inorganic particles, spherical inorganic particles would the electrochemical device for separating membrane.
[Claim 2]
The method of claim 1, wherein the portion of the porous coating layer to a portion of the to a thickness of 10% from the lower portion near the porous polymer substrate based on the thickness direction is high and the amount of b) of the inorganic particles, thickness 10% from the surface of the porous coating layer It is an electrochemical device for the separation membrane to the high content of the inorganic particles a).
[Claim 3]
3. A method according to claim 1 or 2 wherein the porous coating layer is part of the to a thickness from a lower portion close to the porous polymer substrate based on the direction of the thickness thereof of 10% is the inorganic particles a) and b) b 100% compared to the weight sum of the) inorganic the electrochemical device separator for the content of particles of not less than 50% by weight.
[Claim 4]
The method of claim 1 or claim 2 wherein the porous coating layer is part of the to a thickness of 10% from the surface of the porous coating layer, which faces the electrode on the basis of the direction of the thickness thereof are inorganic particles a) and b) total 100 percent by weight of a a ) of an electrochemical device for the separation membrane to the amount of the inorganic particles it is 50% or more by weight.
[Claim 5]
2. The method of claim 1, wherein a) plate-shaped inorganic particles, an aspect ratio (aspect ratio) is greater than 3 to 100 would The electrochemical device for separating membrane.
[Claim 6]
The method of claim 5, wherein a) is a plate-shaped inorganic particles of boehmite to the, membrane for an electrochemical device.
[Claim 7]
2. The method of claim 1, wherein b) the spherical inorganic particles, an aspect ratio (aspect ratio) of 1 to 3 or to a membrane for an electrochemical device.
[Claim 8]
The method of claim 1 wherein the porous coating includes: a) plate-shaped inorganic particles, b) which comprises a mixture of spherical inorganic particles, and a binder resin, and the content of the binder resin of the porous coating layer is 3 to 10% by weight, the electrical separation membranes for chemical elements.
[Claim 9]
The method of claim 1, wherein the membrane is in electrochemical device separator for not less than a puncture strength 0.26kgf.
[Claim 10]
In the electrochemical device comprising a separator interposed between the positive electrode, a negative electrode and the positive electrode and the negative electrode, the negative electrode is a lithium metal, wherein the separation membrane is a separation membrane according to any one of claims 1 to 9, wherein the electrochemical membrane for the device.
[Claim 11]
Porous polymer substrate comprises a polymer resin; And a porous coating layer formed on at least one surface of both surfaces of the porous polymeric base material; wherein the said porous coating layer here is a) plate-shaped inorganic particles and b) comprises a spherical inorganic particles, the porous coating layer is a direction thickness thereof portion of the to a thickness of 10% from the lower portion near the porous polymer substrate based on the inorganic particles a) often more the content of the prepared inorganic particles b), part of the thickness up to 10% from the surface of the porous coating layer to face the electrode inorganic particles a) and b) a separator for an electrochemical device is at least 100% of the sum a) the content of inorganic particles and 50% by weight of.
[Claim 12]
A porous polymer substrate comprising a thermoplastic resin; And a porous coating layer formed on at least one surface of both surfaces of the porous polymer substrate; comprises, here, the porous coating layer comprising inorganic particles and a binder resin, and to the inorganic material particles with a binder resin as a medium that binder and / or surface will the binder is integrated, the porous coating layer a), but with an aspect ratio of 3 is more than 20 or less plate-shaped inorganic particles, and b) the aspect ratio comprises a spherical inorganic particles of from 1 to 3, wherein the porous coating layer is, based on the direction of the thickness thereof part of the inorganic particles a) often more the content of the prepared inorganic particles b), portions of up to a thickness of 10% from the surface of the porous coating layer facing the electrode from the bottom close to the porous polymeric substrate to a thickness of 10% of inorganic particles a) and b) compared to 100% by weight of the sum of a) is based on a content of the inorganic particles is 50 wt%, the aspect ratio [length of major axis / Would be defined in the axial direction perpendicular to the width direction], a separator for an electrochemical device.