1]Mutual citations and related applications
[2]This pplication claims the benefit of priority based on the date of May 25, 2017 Korea Patent Application No. 10-2017-0064830, and all information disclosed in the literature of the Korea patent application are included as part of the specification.[3][4]Art[5]The present invention relates to a process for producing a rechargeable lithium battery including the secondary battery, the positive electrode, the thus prepared secondary battery positive electrode and them.[6]BACKGROUND[7]
Recently there is increasing cellular phones, laptop computers, electric vehicles, etc. along with the rapid spread of electronic appliances that use a battery small and light, yet relatively rapidly, the demand for high-capacity rechargeable battery. In particular, lithium secondary batteries are lightweight and have a high energy density, it has been spotlighted as a driving power source of the mobile device. Accordingly, research and development efforts have been actively carried out to improve the performance of lithium secondary batteries. The lithium secondary battery is oxidized at the time of lithium ion in a state in which charging an organic electrolyte or polymer electrolyte between the positive electrode and the negative electrode made of a insert (intercalations) and the possible active desorption (deintercalation) of lithium ions to be inserted / desorbed from the positive electrode and the negative electrode and the electric energy is produced by a reduction reaction.[8]As a cathode active material of a lithium secondary battery is lithium cobalt oxide (LiCoO 2 ), lithium nickel oxide (LiNiO 2 ), lithium manganese oxide (LiMnO 2 lithium transition metal oxide and so on) is often used. And the negative electrode active material as is generally the softening degree of the large natural graphite or artificial crystalline carbon material such as graphite, or 1000 ~ 1500 ℃ by carbonizing the like hydrocarbon or polymer at a low temperature gave obtained in-graphite (pseudo-graphite) structure or the amorphous type (low crystalline) carbon material is used having a structure nancheung. Crystalline carbon material has a density (true density) is high, so advantageous for packing an active material, and potential flatness, initial capacity and charging and discharging, but the advantage of being reversible is excellent, the capacity is low in energy density per side gram unit volume or unit of active material there is a problem.
[9]Therefore, the electrode active material of the high-capacity capacitor that can be a replacement for small carbon material has been required. Exhibits a high charge and discharge capacity than the carbonaceous material for this purpose, lithium and electrochemically alloying is possible (semi) metal, for example, a study using the Si, Sn and so on as an electrode active material proceeds.
[10]Typically for configuring a lithium secondary battery charged to the anode in the first charging and discharging in order to improve energy efficiency and the amount of which can be time of discharging lithium, a negative electrode is filled with the same designing the amount of lithium that can be sent during a discharge, but the high-capacity negative electrode a negative electrode material comprising a material of the Si-based composite is a life characteristic deteriorates over time with a high initial efficiency charging and discharging efficiency is lower than the positive anode. The use of the high initial efficiency of the positive electrode is discharged, when the negative electrode potential increases, large shrinkage can result in electrical shorts. Therefore, the situation that the positive electrode to lower the initial efficiency without deterioration of the Si-based negative electrode upon applying, life characteristics and capacity characteristics and high-temperature storage characteristics required.[11]Detailed Description of the InventionSUMMARY[12]The present invention decreases the discharge capacity of the positive electrode, or to degrade the performance of the positive electrode active material, or without reducing the capacity density of the positive electrode even method of producing a positive electrode secondary battery to lower the initial efficiency and the thus prepared secondary battery positive electrode It intends to provide.[13]Problem solving means[14]The present invention provides a method for producing a positive electrode by forming a positive electrode active material layer on a positive electrode current collector, including a positive electrode active material, conductive material and a binder; The step of supporting the cathode in the sacrificial salt solution containing the sacrificial salt additive (Sacrificial salt additive); And to the positive electrode then dried supported on the sacrifice salt solution, the step of filling the sacrificial salt additive (Sacrificial salt additive) into the gap (pore) of the positive electrode active material layer, provides a method for preparing a secondary battery positive electrode including a.
[15]
[16]
Further, throughout the present invention, the positive electrode collector; And it is formed on the whole of the positive electrode current collector, a cathode active material, conductive material, binder and sacrificial salt additive (Sacrificial salt additive) the positive electrode active material layer comprising; includes the positive electrode active material layer is less than the porosity (porosity) of 20% It provides a secondary battery positive electrode.[17][18]The nvention also includes a separator interposed between the positive electrode, a negative electrode and the positive electrode and the negative electrode, there is provided a rechargeable lithium battery including the positive electrode.[19]Effects of the Invention
[20]In accordance with the present invention, lowering the discharge capacity of the positive electrode, or to degrade the performance of the positive electrode active material, or can be produced in the positive electrode without reducing the capacity density of the positive electrode even, to lower the initial efficiency.[21]Further, the thus prepared positive electrode may be used in combination with the Si-based negative electrode, the initial efficiency decreased but the capacity characteristics such as excellent implement a lithium secondary battery having a high capacity and excellent cycle life characteristics.[22]Best Mode for Carrying Out the Invention[23]Hereinafter, the present invention will be described to assist understanding of the present invention in more detail. In this case, the specification and are should not be construed as limited to the term general and dictionary meanings used in the claims, the inventor has properly define terms to describe his own invention in the best way on the basis of the principle that can be interpreted based on the meanings and concepts corresponding to technical aspects of the present invention.[24][25]Method of manufacturing a secondary battery anode of the present invention comprises the steps of preparing a positive electrode by forming a positive electrode active material layer on a positive electrode current collector, including a positive electrode active material, conductive material and a binder; The step of supporting the cathode in the sacrificial salt solution containing the sacrificial salt additive (Sacrificial salt additive); And by drying the positive electrode was carried on the sacrificial salt solution, the step of filling the sacrificial salt additive (Sacrificial salt additive) into the gap (pore) of the positive electrode active material layer, and a.[26][27]Conventionally, in order to reduce the initial efficiency of the positive electrode, the irreversible or the addition of a large active material, was used in the initial efficiency decreased so that the modification of the positive electrode active material. However, the problem of irreversible this has a problem that the discharge capacity decrease if adding a large active material, the use of modified positive electrode active material such that the initial efficiency decreased degradation as the positive electrode active material performance such as cycle life characteristics, capacity properties and high temperature storage properties there was. Thus, this approach to lower the initial efficiency was taken into account by addition of a sacrificial salt additive (Sacrificial salt additive) to the anode. Sacrificial salt additive (additive Sacrificial salt) means a non-reversible additive capable of increasing the initial charge capacity. For example, the sacrificial salt additive (Sacrificial salt additive) is lithium and N in the charge 2 , CO or CO 2 is decomposed into lithium is filled in a cathode, N 2 , CO or CO 2 is vaporized to remove through the gas providing step It means possible.
[28]
However, if the sacrificial salt additive (Sacrificial salt additive) blend with conventional cathode active material to prepare a positive electrode slurry, and uses it to produce a positive electrode, and the need for additional space for the sacrificial salt additive (Sacrificial salt additive), in addition, since the excessive rolling is impossible because of the limit rolling, there is a problem that the sacrificial salt additives capacity density of the positive electrode decreases due to the addition of (sacrificial salt additive) is inevitable.
[29]
Thus, the present invention is to solve the problems as described above, after first preparing a positive electrode comprising a cathode active material, this sacrificial salt additives and then supported on the sacrifice salt solution containing the (Sacrificial salt additive) drying the positive electrode active material layer of it was filled with the sacrificial salt additive (sacrificial salt additive) into the gap (pore). Through this, it can even reduce the initial efficiency without reducing the capacity density of the positive electrode.[30][31]When describing the present invention in more detail, to prepare a first positive electrode in the entire positive electrode collector to form a positive electrode active material layer containing a positive electrode active material, conductive material and binder.[32]The positive electrode may be produced according to the manufacturing method of the conventional anode. Specifically, after applying the positive electrode active material, conductive material and a composition for dissolving or forming a positive electrode active material layer is prepared by dispersing a binder in a solvent onto the cathode current collector, it can be prepared by drying and rolling.
[33]Further, as another method, the positive electrode may be manufactured by laminating a film obtained by peeling from the following, the support casting for forming the positive electrode coating composition on a separate support on the positive electrode collector.
[34][35]The cathode current collector is so long as it has suitable conductivity without causing chemical changes in the battery is not particularly limited, for example, stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum or stainless steel the surface of carbon, nickel, titanium , it can be used as such as to a surface treatment or the like. In addition, the cathode current collector is typically may have a thickness of from 3 to 500㎛, may improve the adhesion of the positive electrode active material to form fine irregularities on the current collector surface. For example, films, sheets, foils, nets, porous structures, foams and non-woven fabrics or the like can be used in various forms.
[36]
[37]
The positive electrode active material may typically be a lithium transition metal oxide is used as the positive electrode active material, lithium-containing and more preferably nickel (Ni), cobalt least one selected from the group consisting of (Co) and manganese (Mn) You can use the transition metal oxide. For example, lithium cobalt oxide (LiCoO 2 ), lithium nickel oxide (LiNiO 2 ) layered compounds or Formula Li, such as 1 + x1 Mn 2 - x1 O 4 (Im Here, x1 is 0 ~ 0.33), LiMnO 3 , LiMn 2 O 3 , LiMnO 2 , such as lithium manganese oxide, of the general formula LiNi 1 - x2 M 1 x2 O 2 (where, M 1= Co, Mn, Al, Cu, Fe, Mg, and B or Ga, x2 = 0.01 ~ 0.3 Im) Ni site type lithium nickel oxide, the formula LiMn expressed by 2 - x3 M 2 x3 O 2 (where, M 2 = Co, and Ni, Fe, Cr, Zn or Ta, x3 = 0.01 ~ 0.1 Im) or Li 2 Mn 3 M 3 O 8 (wherein, M 3 = Fe, Co, Ni, Cu or Zn), which is represented by the lithium manganese composite oxide, LiNi x4 Mn 2 - x4 O 4 (where, x4 = 0.01 ~ 1 Im) and the like, but a lithium-manganese composite oxide of a spinel structure represented by, but is not limited to these.
[38]
Or, for as a positive electrode active material may include a lithium transition metal oxide represented by the general formula (1).
[39]
Formula 1
[40]
1 + a [Ni 1-xyz Co x Mn y M z ] 1-a O 2
[41]
Wherein, M is any one or more elements selected from the group consisting of Al, Zr, Ti, Mg, Ta, Nb, Mo and Cr, 0≤a≤0.5, 0≤x≤0.5, 0≤y≤0.5, 0≤z≤0.1, a 0≤x + y + z≤0.7.
[42]
[43]
The positive electrode active material is 80 to 99% by weight based on the total weight of the positive electrode active material layer, and more specifically, may be included in hyamryang 85 to 98% by weight. When included in the above content range it can exhibit excellent capacity characteristics.
[44]
[45]
As being used to impart conductivity to the conductive electrode material, in the constituted battery, it can be used without particular limitation as long as it does not cause a chemical change with the electronic conductivity. Specific examples include graphite such as natural or artificial graphite; Carbon-based material of carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon nanotubes (CNT), carbon fibers; Copper, nickel, aluminum, silver metal powder or metal fiber and the like; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Or polyphenylene may be made of conductive polymers such as alkylene derivative, a singly or as mixtures of two or more thereof may be used of these. The conductive material is a cathode active material layer may be included in a total of 1 to 30% by weight relative to the weight.
[46]
[47]
The binder serves to improve the adhesion of the entire positive electrode active material and attached to and between the positive electrode active material particles and the home. Specific examples thereof include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile (polyacrylonitrile), woods (CMC as carboxymethylcellulose ), starch, hydroxypropylcellulose with a Woods, reproduced cellulose cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated -EPDM, styrene-butadiene rubber (SBR), and a fluorine rubber, or the like of these various copolymers, a singly or in combination of two or more thereof may be used of these. The binder may comprise from 1 to 30% by weight relative to the total weight of the positive electrode active material layer.
[48]
[49]
The solvent may be a day for one commonly used in the art, and dimethyl cell width side (dimethyl sulfoxide, DMSO), isopropyl alcohol (isopropyl alcohol), N- methylpyrrolidone (NMP), acetone (acetone) or water, etc., and there is a singly or as mixtures of two or more thereof may be used of these. The amount of the solvent is in about in consideration of the coating thickness of the slurry, the production yield by dissolving or dispersing the positive electrode active material, conductive material and a binder, so as to have a subsequent viscosity that can indicate the excellent thickness uniformity upon coating for the positive electrode produced sufficient Do.
[50]
[51]
When rolling was applied to forming the positive electrode active material layer composition, if the over-the rolling elongation of positive electrode current collector becomes large, and the electrode disconnection can take place, due to damage of the positive electrode active material may be a problem of reduced capacity . Therefore, it is necessary to rolling at a level of not occur damage to the electrode disconnection and the positive electrode active material, whereby a positive electrode active material layer of the positive electrode prepared in accordance with is generally a void (pore) caused by a certain level. For example, the positive electrode active material layer porosity (porosity) of the cathode prepared as described above may be 15 to 35%, more preferably 15 to 30%, most preferably 17 to 28%.
[52]
[53]
Next, the prepared positive electrode to carry the sacrifice salt solution containing the sacrificial salt additive (Sacrificial salt additive).
[54]
The sacrificial salt solution can be prepared by dissolving the sacrificial salt additive (Sacrificial salt additive) in a solvent. The solvent to dissolve the sacrificial salt additive (Sacrificial salt additive) and, if possible subsequent drying is not particularly limited, and for example, can be used, such as water. In addition, the sacrificial salt additive (Sacrificial salt additive) solubility increased by heating the solvent to the sacrificial salt preferably from 40 to 70 ℃, the most preferred solvent for from 50 to 70 ℃ than 40 to 80 ℃, the additive ( Sacrificial the salt additive) it can be dissolved.
[55]
The sacrificial salt additive (Sacrificial salt additive) is lithium and N during charging as irreversible additives 2 , CO or CO 2 is decomposed into lithium is filled in a cathode, N 2 , CO or CO 2 is vaporized to remove through the gas providing step It is as long as possible can be used, and, more preferably, lithium azide (lithium azide), lithium-oxo-carbonyl (lithium oxocarbon), dicarboxylic acid lithium (dicarboxylic lihtium) and lithium hydrazide selected from the group consisting of (lithium hydrazide) It may be more than one. More specifically, the sacrificial salt additive (Sacrificial salt additive) is LiN 3 lithium azide (lithium azide) in, Li 2 C 3 O 3 , Li 2 C 4 O 4 , Li 2 C 5 O 5 or Li 2 C 6 O 6 such as a lithium-oxo-carbonyl (lithium oxocarbon), Li of 2 C 2 O 4 , Li 2 C 3 O 5 or Li 2 C 4 O 6 dicarboxylic lithium (dicarboxylic lihtium) such as, Li 2 C 2 O 2 N 4 may be a lithium hydrazide (lithium hydrazide) of, most preferably, LiN 3 may be a lithium azide (lithium azide) in the.
[56]
The sacrificial salt solution may comprise sacrificial salt additive may comprise 5-50% by weight of the (Sacrificial salt additive), more preferably 10 to 45 wt%, most preferably 20 to 40% by weight. In addition, the time of supporting the positive electrode on the sacrificial salt solution can be 10 to 300 minutes, from 30 to 250 minutes and more preferably, and most preferably from 60 to 200 minutes.
[57]
[58]
Next, by drying the positive electrode which had supported on the sacrifice salt solution, so that a pore sacrificial salt additive (Sacrificial salt additive) to (pore) of the positive electrode active material layer filled.
[59]
The drying may be performed at 80 to 200 ℃, more preferably from 100 to 180 ℃, most preferably from 110 to 150 ℃ for 150 to 500 minutes.
[60]
Thus after loading the sacrificial salt solution it was dried positive electrode because the sacrificial salt additive (Sacrificial salt additive) filled in the gap (pore) of the positive electrode active material layer, without being reduced in capacity density of the positive electrode, the sacrificial salt additive (Sacrificial salt on the other hand additive) to increase the initial charge capacity, and because the discharge capacity is maintained without being lowered due to the addition of the sacrificial salt additive (sacrificial salt additive), it is possible to lower the initial efficiency of the positive electrode.
[61]
Wherein in order to increase the content of the positive electrode active material layer void (pore) Sacrifice salt additive (Sacrificial salt additive) to be filled in the, then supported on the sacrifice salt solution may be repeated twice or three times through the process of drying.
[62]
An anode on which the sacrificial salt additive (Sacrificial salt additive) filled is, the positive electrode active material, 100 parts of 0.2 to 10, the sacrificial salt additive (Sacrificial salt additive) with respect to the weight of parts by weight, more preferably 0.5 to 7 parts by weight, and most preferably it may contain 1 to 5 parts by weight. The sacrificial salt additive (Sacrificial salt additive) will appear largely the effect of the initial effective reduction in the cathode being contained in 0.2 to 10 parts by weight, it is possible to prevent the contact between the electrodes due to the gas generation decreases during charging, the charge and discharge to facilitate the charging and discharging can be further secured by an air gap is required.
[63]
Thus a cage or an anode of the sacrificial salt additive (Sacrificial salt additive) has porosity (porosity) this is reduced compared to before the positive electrode active material for supporting the sacrifice salt solution layer, and more preferably is the sacrificial salt additive (Sacrificial salt additive) void ratio (porosity) of the filled positive electrode active material layer may be 20% or less, and most preferably from 10 to 20%.
[64]
[65]
On the other hand, the present invention provides a secondary battery, the positive electrode prepared in accordance with one embodiment of the present invention. The positive electrode of the present invention is a positive electrode collector; And the positive electrode collector is formed on the entire image, the positive electrode active material, conductive material, binder and sacrificial salt additive (Sacrificial salt additive) the positive electrode active material layer comprising; includes the positive electrode active material layer has a porosity (porosity) is less than 20% to be. More preferably a porosity (porosity) of the cathode active material layer may be 10 to 20%.
[66]
There is the above to described considering the damage to the bar as an electrode disconnection, and the positive electrode active material the positive electrode active material layer of the positive electrode prepared by general rolling is a void (pore) of a level typically occurs, for example, of 17 to 28% It may have a void ratio (porosity). However, it is the case of the present invention by filling a sacrifice salt additive (Sacrificial salt additive) into the gap (pore) of the positive electrode active material layer, the void ratio (porosity) of 20% or less, more preferably 10 to 20%.
[67]
The anode according to one embodiment of the present invention, because filling the sacrificial salt additive (Sacrificial salt additive) into the gap (pore), without increasing the volume of the positive electrode due to the addition of the sacrificial salt additive (Sacrificial salt additive), the capacity density can not be reduced.
[68]
It may be an average thickness of from 10 to 100㎛ of the positive electrode active material layer, and may be more preferably 20 to 90㎛, and most preferably from 30 to 80㎛.
[69]
[70]
In addition to the same as the type and amount of the positive electrode active material, conductive material, binder and sacrificial salt additive (Sacrificial salt additive) it is described above.
[71]
[72]
According to another example of the present invention, an electrochemical device comprising the anode are provided. The electrochemical device is specifically battery, capacitor and the like, may be more particularly to a lithium secondary battery.
[73]
The lithium secondary battery is specifically positive electrode, a negative electrode for the anode and for facing position, comprising a separator and an electrolyte interposed between the positive electrode and the negative electrode, the positive electrode is the same as the above. Further, the lithium secondary battery may optionally further include a sealing member for sealing the battery container and the battery container housing the electrode assembly of the cathode, anode, separator.
[74]
[75]
In the above lithium secondary battery, the negative electrode comprises a negative electrode active material layer on the negative electrode current collector and the anode current collector.
[76]
On the surface of the negative electrode current collector without causing chemical changes in the battery if it has suitable conductivity not particularly limited, for example, copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper or stainless steel surface-treated with carbon, nickel, titanium or silver, and aluminum-cadmium alloys. In addition, the anode current collector is typically may have a thickness of 3㎛ to 500㎛, may be Similar to the cathode current collector, enhance the bonding strength between the negative electrode active material to form fine irregularities on the current collector surface. For example, films, sheets, foils, nets, porous structures, foams and non-woven fabrics or the like can be used in various forms.
[77]
[78]
The negative electrode active material layer optionally comprises a binder and a conductive material with the negative electrode active material.
[79]
The cathode active material has a reversible intercalation and de-intercalation of lithium can be used a compound. Carbonaceous material such as concrete examples of artificial graphite, natural graphite, graphitized carbon fibers, amorphous carbon; Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn-alloy, or Al alloy, a lithium alloy and a metal compound to be; SiO β (0 <β <2), SnO 2And vanadium oxide, which can dope and de-dope a lithium metal oxide such as lithium vanadium oxide; Or as Si-C composite or a Sn-C bokhapchegwa may be made of composites such as containing a metallic compound and a carbonaceous material, there is any one or a mixture of two or more of them may be used. It is also a lithium metal thin film used as the cathode active material. The carbon material may be used including all of the low-crystalline carbon and high crystalline carbon. A low-crystalline carbon is soft carbon (soft carbon) and curing carbon (hard carbon) is representative, and the high crystalline carbon include amorphous, plate, scaly, spherical or fibrous natural graphite or artificial graphite, Kish graphite (Kish graphite), pyrolytic carbon (pyrolytic carbon), liquid crystal pitch based carbon fibers (mesophase pitch based carbon fiber), carbon microspheres (meso-carbon microbeads), a liquid crystal pitch of (mesophase pitches), and the oil and coal cokes (petroleum or coal tar pitch the high temperature firing carbon such as derived cokes) are typical. And more preferably it may use a Si-based negative active material for high capacity implementation.
[80]
As the negative electrode active material when using a negative electrode comprising a Si-based compound, by using the positive electrode of the present invention is the filled sacrificial salt additive (Sacrificial salt additive) into the gap (pore), lower the initial efficiency of the positive electrode, to improve cycle life characteristics can.
[81]
[82]
Furthermore, it can be the same described above, a binder, and conductive material before the anode.
[83]
[84]
The negative electrode active material layer for the negative electrode active material on a negative electrode current collector by way of example, and, optionally, a binder, and dissolution or dispersion was applied to forming a negative active material layer composition a conductive material in a solvent and drying, or to form the anode active material layer casting the composition on a separate support may be prepared and then, peeled off from the support by laminating a film obtained on the negative electrode collector.
[85]
[86]
On the other hand, in the lithium secondary battery, the separator is that of separating the cathode and the anode, and provides a movement passage of lithium ions, so long as it is used as a separator in ordinary lithium secondary batteries can be used without particular limitation, and, in particular, ion mobility of the electrolyte while a low resistance against the electrolyte is preferably excellent humidification ability. Specifically, the porous polymer film, such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymers and ethylene / methacrylate, the porous polymer made of a polyolefin-based polymer such as copolymer film thereof the two or more layers of the multilayer structure may be used. In addition there is a porous non-woven fabric in a conventional, such as high melting point glass of the fiber, polyethylene terephthalate fiber, such as non-woven fabric may be used. Further, the separator may have a coating containing a ceramic component or a high molecular material used for the heat resistance or mechanical strength secured, may optionally be used in a single layer or multi-layer structure.
[87]
[88]
In addition, the electrolyte used in the present invention may be made of a lithium secondary battery manufacturing usable organic liquid electrolyte, an inorganic liquid electrolytes, solid polymer electrolytes, gel polymer electrolytes, solid inorganic electrolytes, molten-type inorganic electrolyte, such as, limited to it is not.
[89]
Specifically, the electrolyte may comprise an organic solvent and a lithium salt.
[90]
As the organic solvent so long as it can be a medium that can serve to move the ions involved in the electrochemical reaction of the cell, it may be used without any particular limitation. Specifically, the organic solvent is methyl acetate (methyl acetate), ethyl acetate (ethyl acetate), γ- -butyrolactone (γ-butyrolactone), ε- caprolactone (ε-caprolactone) ester based solvents such as; Dibutyl ether (dibutyl ether) or tetrahydrofuran (tetrahydrofuran) solvent include ether solvents such as; Cyclohexanone (cyclohexanone) ketone-based solvents, and the like; Benzene (benzene), benzene (fluorobenzene) an aromatic hydrocarbon-based solvents such as fluoro; Dimethyl carbonate (dimethylcarbonate, DMC), diethyl carbonate (diethylcarbonate, DEC), methyl ethyl carbonate (methylethylcarbonate, MEC), ethylmethyl carbonate (ethylmethylcarbonate, EMC), ethylene carbonate (ethylene carbonate, EC), fluorinated ethylene carbonate (fluoro- ethylene cawrbonate, FEC), carbonate solvents such as propylene carbonate (propylene carbonate, PC); Alcohol-based solvents such as ethyl alcohol, isopropyl alcohol; Nitriles such as R-CN (R may include a straight, branched, or a hydrocarbon group of a cyclic structure, an aromatic ring or a double bond, ether bond, having 2 to 20 carbon atoms); Amides such as dimethylformamide; Dioxolane acids such as 1,3-dioxolane; Or it can be used, such as sulfolane (sulfolane) flow. Of these, and the carbonate-based solvent, Cyclic carbonate having a high ionic conductivity and a high dielectric constant to increase the charge-discharge performance of the battery (for example, ethylene carbonate or propylene carbonate, and the like), a linear carbonate-based compound of low viscosity (for example, ethyl methyl carbonate, dimethyl mixtures of carbonate, diethyl carbonate, and the like) is more preferable. In this case, cyclic carbonate and chain carbonate is about 1: there may be used a mixture in a volume ratio of 9 to better performance of the electrolyte: 1 to about 1.
[91]
[92]
The lithium salt is a compound capable of providing lithium ions used in the lithium secondary battery may be used without any particular limitation. Specifically, the lithium salt, LiPF 6 , LiClO 4 , LiAsF 6 , LiBF 4 , LiSbF 6 , LiAl0 4 , LiAlCl 4 , LiCF 3 SO 3 , LiC 4 F 9 SO 3 , LiN (C 2 F 5 SO 3 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , LiN (CF 3 SO 2 ) 2 . LiCl, LiI, or LiB (C 2 O 4 ) 2 and the like can be used. The concentration of the lithium salt is preferably used within the range 0.1 to 2.0M. When the concentration of the lithium salt is within the above range, since the electrolyte have an appropriate conductivity and viscosity, and can exhibit excellent performance, the electrolyte, the lithium ions can move efficiently.
[93]
[94]
The electrolyte improves life characteristics of the battery in addition to the electrolyte composition, the battery capacity is decreased inhibition, for the purpose of improving the discharge capacity of the battery, for example, difluoromethyl halo alkylene carbonate compound, a pyridine such as ethylene carbonate, tri ethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n- glyme (glyme), hexamethyl phosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N- substituted oxazolidinone, N, N- substituted already Jolly Dean, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethanol, or more than one type of additive, such as aluminum trichloride may be further included. In this case, the additive may comprise from 0.1 to 5% by weight relative to the total weight of electrolyte.
[95]
[96]
Because a lithium secondary battery comprising a positive electrode active material according to the invention as described above find stable indicated by the excellent discharge capacity and output characteristics and capacity retention rate, portable devices such as cellular phones, notebook computers, digital cameras, and hybrid electric vehicles ( it is useful, for example, an electric vehicle sector, such as hybrid electric vehicle, HEV).
[97]
Thus, according to another aspect of the invention, the battery pack including the battery module, and it comprises a unit cell, the lithium secondary battery is provided.
[98]
The battery module or battery pack, the power tool (Power Tool); Electric Vehicles (Electric Vehicle, EV), hybrid electric vehicles, electric vehicles and plug-in hybrid electric vehicle comprising a (Plug-in Hybrid Electric Vehicle, PHEV); Or the power storage may be used as any one or more of the middle- or large-sized devices for the power supply of the system.
[99]
The outer shape of the lithium secondary battery of the present invention Although there is no particular limitation, may be a cylindrical shape using a can, prismatic, pouch (pouch) type or a coin (coin) type.
[100]
The lithium secondary battery according to the present invention can also be preferably used as not only can it be used in a battery cell used as a power source for small devices, in the middle- or large-sized battery module including a plurality of battery cell unit cells.
[101]
Mode for the Invention
[102]
Will be described in detail below, embodiments of the present to the invention can easily be made self-of ordinary skill in the art to practice invention belongs. However, the invention is not to be implemented in many different forms and limited to the embodiments set forth herein.
[103]
[104]
Example 1
[105]
LiCoO 2 , carbon black, a binder PVDF at a weight ratio of N- methylpyrrolidone solvent in the money 95: then mixed in a ratio of 2.5 to prepare a composition for forming a positive electrode active material layer, and applying it to one surface of aluminum current collector, 2.5 after drying at 130 ℃, by rolling the rolling density 3.53g / cc to prepare a positive electrode. At this time, the positive electrode active material layer formed on the collector is 3.53g / cc, thickness 61㎛, void ratio (porosity) was 25%.
[106]
In addition, lithium azide (LiN 3 ) After evaporation of the water of 20% by weight aqueous solution, kept at 60 ℃ prepare a sacrificial salt solution of 30% by weight. The positive electrode prepared in the sacrificial salt solution was taken out and then loading for 60 min and dried at 130 ℃ for 200 minutes.
[107]
The porosity at this time was decreased by 18%, and lithium azide (LiN 3 ) is LiCoO 2 : LiN 3 was confirmed included in a weight ratio of 2: = 98.
[108]
[109]
Example 2
[110]
After carrying the sacrificial anode to the salt solution to prepare a positive electrode is carried out in the same manner as in Example 1 except that the process was repeated three times to dry.
[111]
The porosity of this time is decreased to 13% and lithium azide (LiN 3 ) is LiCoO 2 : LiN 3 was confirmed included in a weight ratio of 3.5 = 96.5.
[112]
[113]
Comparative Example 1
[114]
A positive electrode and is conducted in the same manner as in Example 1 except for not performing the process of loading the sacrificial salt solution and dried to manufacture.
[115]
[116]
Comparative Example 2
[117]
Example 1 composition in LiCoO for the positive electrode active material to form 2 : LiN 3 wherein the weight ratio of 98: lithium azide (LiN such that 2 3 after the mixing), applying it onto one surface of aluminum current collector, and then dried at 130 ℃ , a positive electrode was prepared by rolling the electrode density of 3.53g / cc.
[118]
[119]
Comparative Example 3
[120]
Example 1 LiCoO the positive electrode active material forming composition of the 2 : LiN 3 wherein the weight ratio of 98: 2 so that the lithium azide (LiN 3 ) were mixed, and then rolled to a drying at 130 ℃, the electrode density of 3.6g / cc to anode It was prepared.
[121]
[122]
[: Measuring the positive electrode density, (porosity) thickness and porosity of Experimental Example 1]
[123]
Examples 1, 2 and Comparative Example 1 to measure the density of the positive electrode active material of the prepared positive electrode layer, the thickness and void ratio (porosity) 3 The results are shown in Table 1.
[124]
Specifically, by measuring the thickness and weight of the positive electrode active material layer, the electrode density was calculated as = weight / volume, volume = thickness × surface area, the porosity was calculated using the true density, and electrode density with this construction material.
[125]
Void ratio = {(true density-electrode density) / true density} × 100%
[126]
[127]
TABLE 1
Electrode density (g / cc) Thickness (㎛) Porosity (%)
Example 1 3.60 61 18
Example 2 3.66 61 13
Comparative Example 1 3.53 61 25
Comparative Example 2 3.53 63 21
Comparative Example 3 3.60 61 18
[128]
In the case of the table when one reference to embodiments which filled the sacrificial sacrificial salt additive (Sacrificial salt additive) to a salt cavity (pore) of the positive electrode was dried and then impregnated with the positive electrode in a solution in Examples 1 and 2, without addition of the sacrificial salt Comparative than the positive electrode of example 1 was reduced to a porosity below 20%, the electrode density is sacrificed salt additive (sacrificial salt additive) added was increased due to the thickness is the sacrificial salt additive (sacrificial salt into the gap (pore) that already exist in the It is not increased because the filling additive), was equivalent level. On the other hand, the sacrificial salt additive (Sacrificial salt additive) for a positive electrode was prepared by mixing the positive electrode active material, compared to the density of the positive electrode active material layer rolled to a density equivalent before addition of the sacrificial salt additive (Sacrificial salt additive) to 3.53g / cc example 2 because of the need for additional space for the sacrificial salt additive (sacrificial salt additive) the thickness of the positive electrode active material layer was increased to 63㎛. In addition, the sacrificial salt additive (Sacrificial salt additive) the positive electrode active material and a positive electrode was prepared by mixing, increased in the case of a rolled comparison to 3.60g / cc for the capacity density increased thickness Example 3 although larger, due to excessive rolling the positive electrode active material is corrupt, there is a problem of reduced capacity.
[129]
[130]
Experimental Example 2: Evaluation charge-discharge capacity and initial efficiency;
[131]
Examples 1, 2 and Comparative Example 1 using the positive electrode prepared in 1-3 proceeds the coin half cell charge-discharge test was measured 0.1C capacity and efficiency, the results are shown in Table 2 below.
[132]
Charging conditions: 0.1C, CC / CV (4.4V, 0.05C cut-off)
[133]
Discharge conditions: 0.1C, CC (3.0V cut-off)
[134]
[135]
TABLE 2
Charge capacity (mAh / g) Discharging capacity (mAh / g) The initial efficiency (%) Capacity density (mAh / cc)
Example 1 189 172 91.5 607
Example 2 197 172 87.3 607
Comparative Example 1 177 172 97.5 607
Comparative Example 2 187 171 91.4 584
Comparative Example 3 181 167 92.1 590
[136]
In the case of Table 2 If the reference to the embodiment which filled the sacrificial salt additive (Sacrificial salt additive) into the gap (pore) of the dried positive electrode after carrying the positive electrode on the sacrificial salt solution in Examples 1 and 2, without addition of the sacrificial salt compared to Comparative example 1, the anode of the discharge capacity to the same level or charge capacity was increased, the initial efficiency is lowered, the discharge capacity density is not decreased. On the other hand, Comparative Example 2, the discharge capacity density was significantly reduced for the case of Comparative Example 3 is damaged due to excessive rolling the positive electrode active material was significantly reduced in capacity and discharge capacity density

WE CLAIMS

[Claim 1]
Throughout the positive electrode current collector, to prepare a positive electrode by forming a positive electrode active material layer containing a positive electrode active material, conductive material and a binder; The step of supporting the cathode in the sacrificial salt solution containing the sacrificial salt additive (Sacrificial salt additive); And the step of filling with the positive electrode then dried supported on the sacrifice salt solution, the sacrificial salt additive (Sacrificial salt additive) into the gap (pore) of the positive electrode active material layer; Method of producing a secondary battery positive electrode including a.
[Claim 2]
The method of claim 1, wherein the sacrificial salt additive (Sacrificial salt additive), lithium azide (lithium azide), lithium-oxo-carbonyl (lithium oxocarbon), dicarboxylic acid lithium (dicarboxylic lihtium) and lithium hydrazide (lithium hydrazide) the method of any one or more selected from the group consisting of a secondary battery positive electrode.
[Claim 3]
The method of claim 1, wherein the sacrificial salt solution method for manufacturing a secondary battery, the positive electrode which is prepared by dissolving the sacrificial salt additive (Sacrificial salt additive) in a solvent of 40 to 80 ℃.
[Claim 4]
The method of claim 1, wherein the sacrificial salt solution process for producing a secondary battery comprising a positive electrode 5 to 50% by weight of the sacrificial salt additive (Sacrificial salt additive).
[Claim 5]
The method of claim 1, wherein the method for manufacturing a secondary battery, a positive electrode and drying process repeated two or three times after which the supported on the sacrifice salt solution.
[Claim 6]
The method of claim 1, wherein the sacrificial anode active material layer prior to salt solution is carried to the void ratio (porosity) of from 17 to 28% The method of producing a secondary battery positive electrode.
[Claim 7]
The method of claim 1, wherein the sacrificial salt additive is the filled positive electrode active material layer (Sacrificial salt additive) has porosity (porosity) of 10 to 20% The method of producing a secondary battery positive electrode.
[Claim 8]
The method of claim 1, wherein the positive electrode active material is nickel (Ni), cobalt (Co) and manganese process for producing a (Mn) of a secondary battery positive electrode of lithium-transition metal oxide comprising at least one selected from the group consisting of.
[Claim 9]
The method of claim 1, wherein the sacrificial salt additive is the filled anode (Sacrificial salt additive), the manufacturing method of the positive electrode secondary battery comprising the positive electrode active material, 100 parts by weight of the sacrificial salt additive (Sacrificial salt additive) with respect to the unit of 0.2 to 10 parts by weight .
[Claim 10]
The anode current collector; And it is formed on the whole of the positive electrode current collector, a cathode active material, conductive material, binder and sacrificial salt additive (Sacrificial salt additive) the positive electrode active material layer comprising; includes the positive electrode active material layer is less than the porosity (porosity) of 20% secondary battery positive electrode.
[Claim 11]
11. The method of claim 10, wherein the secondary battery anode porosity (porosity) is from 10 to 20% of the positive electrode active material layer.
[Claim 12]
11. The method of claim 10, with the sacrificial salt additive (Sacrificial salt additive), lithium azide (lithium azide), lithium-oxo-carbonyl (lithium oxocarbon), dicarboxylic acid lithium (dicarboxylic lihtium) and lithium hydrazide (lithium hydrazide) any one or more selected from the group consisting of a secondary battery positive electrode.
[Claim 13]
The method of claim 10, wherein the secondary battery cathode including the cathode active material of 100 parts by weight sacrificial salt additive (Sacrificial salt additive) with respect to the unit of 0.2 to 10 parts by weight.
[Claim 14]
11. The method of claim 10, wherein the positive electrode active material is nickel (Ni), cobalt (Co) and manganese in a secondary battery positive electrode of lithium-transition metal oxide comprising at least one selected from the group consisting of (Mn).
[Claim 15]
Positive electrode, a negative electrode and a separator interposed between the anode and the cathode, the anode of claim 10 to claim 14 wherein any one of the secondary battery, the positive electrode of the lithium secondary battery of.
[Claim 16]
The method of claim 15, wherein the negative electrode is a lithium secondary battery including the Si based anode active material.