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`atent
`Enragdtaches
`European
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`wetontice
`Offles eurapden i
`dee keroyeds
`;
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`(42)
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`fit
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`EP 2 793 305 A‘
`
`EUROPEAN PATENT APPLICATION
`publishedin aecordance with Art 163(4) EPC
`
`(43) Date of publication:
`22.40.2044 Bulletin 2014/43
`
`(61) int ch:
`MOM TOMBS? 2082.04)
`
`HOTM 2fige Gacser
`
`{21} Application number: 12857544.6
`
`(22) Date of filing: 13.02.2072
`
`(86) International application number:
`PCTIKR2604 2/007 052
`
`(87) International subleation number
`WD 2073/089313 (20.06.2013. Gazette 2073/25}
`
`
`{84) Designated Contracting States:
`AL AT BE BG CH CY C2 DE DK EE ES FIFR GB
`GRHRHUIEISITLILT LULV MC MK MT NL ONO
`PL PT RO RS SE SISK SM TR
`
`(30) Prority: 19.42.2044 KR 20710133354
`
`(71) Appicant Kokam Co., Ltd.
`Gyeronggi-de 440-857 GR)
`
`KO, Sung-Tae
`Gyeryang-si
`Chungcheongnam-do 321-764 {KR}
`* HEO, Yoon-Jeong
`Syeryong-si
`Chungcheongnam-do 321-764 {KR}
`* KWON, Yoo-Jung
`Daajean 302-845 (KR)
`
`{
`
`(74) Representative: Schumacher & Willsau
`72) inventors:
`Patentanwaltsgeselischait rbH
`HONG, JiJun
`Nymphenburger Strasse 42
`$0335 Miinchen (DE}
`Gyeonggi-do 427. 060 {KR}
`
`(545
`HIGH HEAT RESISTANCE COMPOSITE SEPARATOR FOR LITHIUM SECONDARY BATTERY
`AND LITHIUM SECONDARY BATTERY INCLUDING SAME
`
`Disclosed js a high heat resistance composiie
`{87}
`separator including a porous substrate having a plurality
`of pores, an inarqanic costing layer formed on one sur-
`face of the porous substrate, the inorganic coating layer
`including a phurality of inorganic particles and a binder
`polymer disposed on a poriion ar all of surfaces of the
`
`inorganic particles to commect and bind the inorganic par-
`ticles, and a high heat resistance palymer coating layer
`formed on the other surface of the sorous substrate, the
`high heat resistance polymer coating layer Including a
`high heat resistance polymer and inorganic particles. cis-
`sersed in the high heal sesiatance polymer.
`
`
`
`Srindeed ty dung, Fue PaSic RY
`
`EP2793305A1
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`EP 2 793 205 Ad
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`Description
`
`TECHNICAL FIELD
`
`{8003} The present disclosure relates fo a high heal resistance composite sepanator for a Hhinm secondary battery
`and @ lithium secondary batfery Inchiding the same. More perficularly, the present disclosure relates to a carnpusite
`separator thal has superior shape stability at-high temoersture and a high mechanical strength as well aga shuldown
`function, and @ Whiun: secondary Battery including ihe same,
`{6002] The present application claims priority fo Korean Patent Appicatian No. 10-201 1-0139354 fied in the Republic
`of Korea on December 13, 2041, the disclosures of which are incergorated herein by reference.
`
`BACKGROUND ART
`
`[6003] With the rapid develooment of slectranic, communication and computer industries, motile electranin conmu-
`nication equipments, such as, for exarnpte, carncorders, mobile phones, laptop computers, and the ike, have been
`advancing remarkebly. Accardingly, the demand for lithium secondary batteries as a power source of mohle electronic
`
`communication equipments is increasing day by day. in particular, reoenlly, research and develupmendhas been achlively
`made all over the world including Japan, Europe, USA as well as Korea, in relaiion to the applications of Rthhumsecondary
`batteries mot anly as a power source of rnobile electronic equipments bul also as an envirarmnenttriendly power source
`of larger scate equipments, for example, electric vehictes, uninterruptible power supplies, slectromativetoals, satellites,
`and the ike.
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`20
`
`{O004] Generally, a ithium secondary battery includes a cathode of fthiunrtransition metal camposite oxide, an anode
`capable of intercalating or disintercalaling thintons, a separator interposed between the cathode and the anode, and
`an electrotyle that helps the migration of ihium ions,
`{O005] The main functionof the separator is fo holding the electrolyte therein to provide high ion permeability as well
`as isolating the cathode fram the anade. Recently, a separator having a shul-clown funelion has been suggested, in
`which, for example, when a short circuit ocours in a battery, a part of the separator malts fo stop pores so as fo keep a
`large amount of elecbic current fram flowing info the batlery. Aisa, techniques have been suggested to prevent cathode
`and anode plates from coming into contact with each other by increasing an area of a separator larger than those of the
`cathode and anode plates, however, in this case, an additional function is required to keep an intemal short circul of a
`battery caused by the cantact of the two electrode plates fram occurring by preveriing a separator from shrinking due
`to ari increaseIn infemal famperature. in particular, lo keep up with the recent trand of a Hthium secondary battery toward
`higher cagacily art higher energy dereity, higher heat resislance and thermal stability han required for a coriventional
`separator is required because temperature in a battery rises wher a high rate charge/discharge state of the battery is
`continuously maintained.
`{G008]
`in the conventional separator, a porous membrane made in a form of a sheet using polyolefin-based palymer
`such as polyethylene (PE) or polypropytene (PP} has been widely used. A separator made from polyethylene having a
`melting temperature of 130°C of palyprooylene having a melting lernperalure of 170°C stops micropores to block (shut
`down) the movement of iors in response fo heal generated when an excessive amount of electric current flows into a
`battery by a short circuil ar an increase in the internal teraperature by the effect of a ceriain external factor, and along
`with this, thermally shrinks or melts to fulfl a separation function.
`{G007]
`In addifion te the shufxiown feature, shape stabiiiy is another impartant quality of the separater when the
`temiperature continues to increase even subsequent fo shut-dawn. When used in the melting temperature range of
`polyethylene or palyprogylena, if the temperature of the ballery continues fo increase by internalextemal factors even
`subsequent to shutdown, the separator melita and losesits shape, which causes a short circuit of electrodes, getting
`inte a dangerous situation.
`{G008] To solve tis problem, developrnent of a cornposile separalor for a Hthiura secondarybaltery has been reported.
`First, Korean Pistent Publication No. 10-2071-0011832 improves thermal stability by coating ceramic respansible for
`anhancing mechanical properties and konic golymer on polyolefin-baged resin.
`{G009] Also, Korean Patent Publication No. 10-2070-0729471 increases a mechanical strength and provides acid
`resistance by coating with Inorganie powder, thereby improving performance and life characteristics, However, this art
`involves coaling with an inorganic matier which increases in the ssparatar weight and consequently the overall batisry
`weight, causing a reduction in energy density. Also, because inorganic Hers vulnerable to reaction with a majorily of
`carbonaie are used, CO. gas and other gases are generated by decompasition of a carbonate-based salvent baing
`commany used, and when fe® unused for a long fine, a bulging phenomenon of a cell ia observed, hence there is a
`innilation in improving battery stability.
`fO0d0)
`PCTIEP 2003007163, which provides large inorganic. particles to the surface and inside, reduces a density
`increase of a hybrid separator and when it reaches a high temperature, brings about shut-down by oenetration of an
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`EP 2 785.305 Ad
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`organic matter info pores, bul improves safely due to having ne melling paint, However, this also has afactar hindering
`slabilily because gas is generated by a decomposition reaction of the used inarganic matter, that is, Sibesed, with an
`slecirolyte salntion.
`{OOt7?] Recently, many attempts have been made to coat and graff polyvinylidene fluoride (PVdF) onto 4 polyolafin-
`based porous membrane by a method of double-coating polymer. However, due to low heat resistance, polyolefin melts
`and nucropores disappear when an internal temperature of a battery exceeds 150°C, and thus, an ian blocking effect is
`superior but wher @ microporous polymer rrermbrane melis, a membrane area reduces due te a very high volume
`shrinkage rafio, as a consequence, an internal shor olrcutt ofa battery occurs, causing a problem with safelyof the battery.
`{60¢2]
`Japanese Patent Publication No. JP-P-2007-122026 manufactures and uses a laminated porous film by coating
`a@ molten thermoplastic resin in a fonvt of a non-waven fabric onfo a porous Hm, and this provides excellent thermal
`safety, bul the non-wovenfabric forn ts exposed to an internal short circuit hazard, and due to high porosity, a large
`aynount of electrolyte solutions needs fo be uses, resulting in a reduced anergy density,
`
`DISCLOSURE
`
`Technical Problem
`
`20
`
`{6043] Therefore an otyact of the present disclosure isto providing a high heal resistance composite separator having
`@ high mechanical strength, a shutdown function, leas heal shrinkage, heat resistance, high fanic conductivity, and
`superior adhesion with an electrade.
`{e0d4] Also, analher otject of Ihe oresenl disclosure is ta providing a thiura secondary ballery wilh such high heat
`resistance composile separator that improves safety and stability withoul deterioration in electracheamical properties of
`the ballery.
`
`Technical Solution
`
`{6075} To achieve the above objects, according to ane aspect of the present disclosure, there is provided a high heat
`resisianos composiie separator including a porous substrate having a pluradty of pores, an inorganic coating layer formed
`on one surface of the parous subsirate, ihe inorganic coating layer indluding a plurality of inorganic particles and a binder
`palymey disposed on a portion or all of surfaces of ihe inorganic particles to connect and bind the Inorganic particles,
`and a high heal resisiance polymer coating layer fonned on the other surface af the porous substrate, ihe high heal
`resistance polymer coating fever inchicding a high heat resistance polymer and inorganic garticles dispersed in the high
`reat resistance polymer.
`[0076] The porous substrate may be a polyolefin-based porous membrane of non-woven fabric.
`{O077] The porous substrale may be formed from any one selected from the group consiating of polyethylene, coly-
`propylene, polybuiviene, polypentene, poh meltylpentens, solyethyieneterephthalate, nofyhulleneterephihaiate, poly-
`ester, polyacetal, polyamide, polycarbonate, palyimide, polyatheretherkelone, polyethersulione, polyahenyleneaxite,
`oolyphenylenesulfide, polyethylenenaghthatene and their capalymers, or mixtures thereof.
`{8073} The inorganic particles may be selected fram the group consisting of inorganic particles having a dislectric
`constant greater than or equal to 4, inorganic particles capable of frangporting iRhiura jons, and mixtures thereat
`[6049] The inorganic particles having the dislectric constant greater than or equal to § may be any one selected fram
`the group consisting of BaliO,, Poigr,.Th,JO,
`(P2T, O<x<1}, Ph,be2ry pTLOSPLET,
`fixx<}, O<yet}, {1-
`UPit Mg pais5}O9-xPDTIOsPMN-PT, Gex< 1), hafnia (HIOs), SrTiOs, SrO., CaQs, MgO, NIO, Ca, 2, ZrO2, SDs,
`WoO, AlpDy, SIC and TO,, ar mixtures thereof
`{6020] The inorganic particles capable of transporting lithium ions may be any one selected frarn the group consisting
`of thium phosphate (Li,POQ,), lithium ttaniien phosphate (LETIfPOg)s, O< x < 2,0 <y < 3), lithium aluminum fitanium
`phosphate (LALTIAPOgs, Gex<2 Qayst 0<2<3}, (LIAITIP).O, based glass (0 <x <4. G < y < 13}, lithium lanthanum
`tianate (LidaTiOy, O< «x < 2,0 <y¥ <3), ithium germanium thiophosphate (Li,GePS. O<x<dOxy<t O<z<1 Oew<5),
`lihiumnitride (LiN,, 0 < x < 4,0 < y < 2), SiS, based glass (Li,Si,S,, O<x<3O«ye2 Ox<zs4} and PyS, based ghaas
`(Li,PSy, O<K<3Osy<d0<2<7), or mixtures thereof
`{027} The binder polymer may be any one selected from the group cansisting of polyvinylidene Muoride-co-hexafiuor-
`opropylens, polyvinyikiens Ruaride-co-trichlorasihviens, polymethyimethacrylats, polybutylacnate, polyacrylanitrile,
`polyvinyipyrralidone, palyvinylacetate, oolyethylene-co-viny! acetate, palyethylene oxide, polyarylate, cellulose acetate,
`cellulose acetate butyrate, cellulose acetate propionate, cyancethylpuliuian, cyanoethyipohvinylaicohal, oyancathyice-
`lulose, cyanoethyisucrose, pulludan and carboxyl methyl sefluiose, or mixtures thereof
`{G022] The high heal reststarice polymer may be any one selected from the group consisting of aromatic polyamide,
`aromaticpolyimide, aromatic polyamide-imide, aromatic potyimine, Teflon® (potytatrafluarcethylane), palybenzoxazole,
`polybengzimidazale, polyphenylsulfide and palyphenylene oxide, ar mixtures thereof
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`{G023] The aromatic polyarnide may be oora-lyoe aromatic polyamide, mela-lype aromatic polyamide, and thee mix-
`ture.
`
`{O024] The inorganic coating layer may inchide the binder polymer in a range of 0.1 to 50 paris by weight based on
`150 paris by weight of the Inorqanic particles.
`[8025] The high heat resisiance polymer coating layer may inniude the inorganic parlicias in a range of 0.7 fa 40 paris
`by weight based on 100 parts by weight of the high heat resistance polymer.
`[6026] Theseparater may heve poroaily in a range af 30to 70% and aly cermeatbilify ina range af 150 ta 400 eac/1Oame.
`{O027] Atleast one of the inorganic coating layer and the high heat resistance polymer cuating layer mayfurtherinclude
`any ane lithium secondary battery performance enhancing additive selectedfrom the graup cansiating ala solid electralyte
`interface forming additive, a batlery side-reaction suppressing addiive, a thermal stability enhancing additive and an
`overcharge inhibiting addifive, or mixtures thereof,
`{G028] The salid electratyte interface forming anditive may be any one selected fram the group cansiating of vinylene
`carbonate, virrdethylene carbonate, cyclic sulfite, saturated sulfone, unsaturated sullane, nor-cyclic sulfone ard their
`derivatives, or mixtures thereof.
`{9028} The balery side-reaciion suppressing addifive may be one selected from the gravp consisting of ethylenedi-
`aminetetraacetic acid, fetramethylethylenediaming, pyridine, dipyridy!, ethylbis (diphenylphosphing), butyronifrite, suc-
`ainanitile, indine, sumrnaniumnhalide and their derivatives, or rdxhures thereof,
`[6030] The thermal stability enhancing additive may be one selected fromthe groug consisting of hexamethyldisiloxane,
`hexamethoxyoyclotriphosphazene, hexamethyishosphoramide, cyciohexylbarzene, biphenyl, dimethylpyrrote, trimeth-
`yiphosphate and their derivatives, or mixtures therecf.
`{8034} The overcharge inhibiting addithve may be one selected from the groug consisting of n-butyiferrocene, halogen
`substituled berizene derivative, cyclohexybeanzene and biphenyl, or mixtures thereo!,
`[6032] A content of the thium secondary battery performance enhancing additive may be ina range of 6.4 fo 20 paris
`by weight based on 100 parts by weight of the Inorganic coaling layer and the high heat resistance palmercoating layer.
`{O033) According to another aspect of the present disclosure, there is provided a [Nhium aecondary batteryinchiding
`a@ cathode, an anode, and a separalor interposed befween the cathode and the anode, whersin the separator is the
`above-described high heat resistance composite separator.
`
`Advantageous Effects
`
`{OUS4] According to one aspect of the present disclosure, there is provided 4 high heat resisiance composite separator
`with superior safety, in which heal shrinkage af high temperature is suppressed dueta heat resistance characteristics
`and a high mechanical strength by ooaling inorganic particles on one surface of a porous substrate, and heat shrinkage
`at high temperature is suppressed and a shape change caused by external penetration is prevented by coating a high
`heat resistance polymer having no safely melting paint on the other surface of the porous substrate. and a Hehiurn
`secondary batiery inchicding the same.
`[6035] Also, the high haat resistance composite separator is capable of forming a large number of pores, which
`proves perfomance in holding ar: electrolyte solution, resulting in favorable movement of ions, thereby contributing
`to fabrication of a lithium secondary battery with high output and long Hfe cycle characteristics
`
`DESCRIPTION OF DRAWINGS
`
`(0036) The accompanying drawing ihistrates 3 preferred ambodiment of the present disclasure and together with the
`ipragoing disclosure, serves io provide further understanding of Ihe techainal spirii of the present disclosure. However,
`ihe present disclosure is nol construed as being limited ta the drawing.
`
`FG. Tis a schematic cross-sectional view Htustrating a high heat resistance composite separator according fo an
`exemplary enibadimiant and a scanning electron micrascopy (SEM) image of elements of the segaratar.
`FIG. 2 is a graph showing capacity during high rate discharging of idhium secondary batteries of Ernbadirnent
`example 2-1, Comparative example 1, and Comparative example 2.
`FEG. Sis a gragh showing capacity changes during a life leat for thtum secandary batleries af Embodiment example
`2-1, Comparative exanipie 1, and Comparative example 2.
`FIGS. 4a through 4c are graphs each showing battery vollage behaviors and surface lamperature changes during
`overcharging for ithiinn secondary batteries of Embodiment example 2-1, Comparative exaraple 1, and Comparative
`examola 2.
`FESS, Sa through Sd are graphs each showing ballery vollage behaviors and surface temperature changes derived
`from a nail penetration test for lithlum secondary batteries of Enibaciment example 2-1, Embodiment example 2-2,
`Camparative example 1, and Comparalive example 2.
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`FRGS, Ga through 6c are graphs each showing battery vollage behavicrs and surface temperature changes derived
`from a thermal shock test for lithium secondary batteries of Embodiment example 2-1, Comparative example T, and
`Comparative example 2.
`FiG. 7 is a draph showing vollage chariges during one month storage at high ternperature for ithhim secondary
`batierias of Embodiment example 2-4, Comparative example 1, and Gomparative example 2
`
`MODE FOR DISCLOSURE
`
`{6037] Hersinafer, the present disclosure will be described in detail. H should be understood drat the terms used Mn:
`the specification and the appended claimy shauld nal be coneirued as hmited ta general and dictionary meanings, but
`interpreted based on the meanings and concepts currespanding to technical aspects of the present disclasure on the
`basis of the principle that the Inveriioc is allowed to define terms appropriately for ihe best exlanatian.
`{GOS8] According fo one aspect of the present disclosure, disclosed is a high heat resistance composite separator
`including 8 porous subetrate having 4 plurality of pores, an inorganic coating layer formed on one surface of the porous
`substrate and inching a plurality of inorganic particles ard a binder palymer disposed on a portion or alt of surfaces of
`the inorgaric particles to connect and bind the inorganic particles, and a high heat resistance polymer coating layer
`formed on the cther surface of the porous substrate andincluding a high heat resistance polymer and inorganic pariiches
`dispersedin the high heal resistance pobymer.
`{G039]
`FiG. i Hustrates echematically a high heat resistance composite seocarater according fo an exemplary emibod-
`iment of the present disclosure. Referring fo FHS. 1, the separator according to an exemplary embodiment of the praesent
`Hisclosure has a composite parcus sheet structure in which a porous substrate is coated with Inorganic particles on an
`woper surface thereof and a high heat resistance polymer an a lawer surface thereof,
`{6040]
`In the high heat resistance composite separaioer according to an axemplary embodiment of the present discio-
`sure, for the porous substrate or: which the inorganic coating kryer is formed, any porous substraie commeanly employed
`a ithium secondary battery may be used, for exarpis, a polyolefin-based porous membrane or non-wovenfabric, but
`the poraue substrate is not particularly limites thereto.
`{G047] The polyofefin-based porous rnembrane may be, for example, membranes formed front polyethylene such as
`high density polyethylene, linear low density golyelhylene, iow densily polyethylene and uitea high molecular weight
`polyethyiens, palypropyisns, polybutylene, polypentens, polymethyipentene, and their copolymers, singularly or in com-
`bination,
`
`{O042] The non-woven fatiric ray Se, other than a potyolefin-based norewoven fabric, for examale, non-woven fabrics
`formed fran potyethyleneterephthalate, palybutyleneterephthalate, polyester, polyacetal, polyamide, polycarbonate,
`colyimide, polyetheretherketane, polyethersulfane, polyphenyleneoxide, palyohenylenesuifidre, polyethytenenaphiha-
`iene, and their copatymers, singularly or in cormbination. A structure of the non-woven fabric may be @ spunbond non-
`woven fabric made from jong fibers ar a metiblown sori-avovenfabric.
`{G0043] Because the porous substrate has a predetermined melting paint based an a specific material heing manufac-
`tured, when fermperature inside a lithiumsecondary battery increases up to the melting point of the porous substrate,
`the porous substrate starts fo melt and loses ite pore structure inside, and a3 @ resull, {he porous substrate performs a
`shut-down function to keep fons from moving. To Aull the shut-downfunction, the melting point af fhe porous substrate
`may be In a ninge of 770 to 160°C.
`[6044] Thickness of the porous substrate is not particularly Himited, but may be Ina range of 5 ta 50 am or ina range
`of 1G to 30 pin, and a pore size andporosity af ihe paraus substrate is also not particularly limibed, butmaybe in a range
`of 6.07 to 50 gm and in a range of 30 te 80%. respectively. Also. alr permneahility af the parous substrate may be in a
`range of 100to 300 seo/100m),and a breaking strength may be 1,000 kgfiom? or higherin vertical and horizontal directions.
`{6045] The inorganic particles are not particularly limited if they are electrachemically steble and may minimize a
`decomposition reaction with an alectrobyte solution. Thatis, the inorganic particles are not particularlylimited if they do
`not cause oxidation and/or reduction reactions in an ogerating vollage range {far example, fram 0 ta SVfor LILI} of an
`electrochemical device to be agpied. In particular, when inorganic panicles capable of transporting ions are used, ionic
`ponductivily within an electrochemical device may be Increased, coniributing to performance improvement, These inar-
`ganic particles may improve thermal and mechanical properties of the separator because they exhibit sirang mechanical
`graperies and excellent heat resistance af high lemperature.
`{8046} Also, wherinorganic particles having a high dislectric constant are used as the inorganic panicles, the degree
`of disseniation of an electrolyte sali, for example, a fthium sail, ina liquid electralyle may increase andionic sonductvily
`of the electrotyie solution may be improved.
`[6047]
`For these reasons, the inorganic pariicles may Include inerganic particies having a high dielectric constant
`greater {han or equal te & or greater than or equal fo 10, inerganic particles capable of transporting lithium fons, or a
`mixture theraaf,
`
`[6048] Non-limifing examples of the inorganic panicies having the dielectric canstani greater than or equalic & include
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`BaliOg, PRET, JO (PZT, O < x <1), Phyadr, TO, (PLAT, OxxetOeyet), (-xgPBC MaygNBogiQXPDTIO,
`(PMN-PT, 0 <x < 1), Bafnia (HfOs), SrTiOs, SnOs, Ces, MgO, NiO, CaO, ZnO. ZrOs, W205, Alps, SIC and TOs,
`singularly oy in combinvstice.
`f0049)
`Partiowarly, inorganic particlas such as BaTiQ,, Poi2nTi_JO4 (PET, O<x% <1), Pb, dager, TOs (PLZT, 0
`<x <di<y< 1}, (odPbiMg, githoJO..POTIO, (PMN-PT, @ <x < 1), and hafnia (HIO,} describedin the foregoing not
`ony exhibit high dielectric constant characteristics greater than or equal to 100 but giso have piezoelectricity to protect
`both electrodes fram Internal shart ciroudis when an external impact is agpled, ensuring improved safety of a ithiurni
`secondary battery, and here, plezoelectrivity is a phenamencn in which charges are created as a result of tension or
`compression under a cartain pressure to generate 4 solential difference between opposite sides. Aisa, the use af a
`mixture of the high dielectric constant inorganic garticles and the inonganic cariicles capable af transparting lithium ions
`can produce enhanced synengistic effects.
`{G050] The inorganic particles capable of transporting fihium jons cefer to an inorganic particte thal contain Hthiurs
`atoms and have a function of transferring a fithiumion without staring Hthiven, ard the inorganic particles capabis of
`transparting dihium ions can transfer and move a fithium ion due to a sart of defect present within Hs pariicie structure,
`thereby conductivily of tthium ions in a baltery may be irnproved, contributing to baflery performance improvement.
`{8054] Non-iimiting examples of the Inorganic particles capable of transporting Ithium jons include thium phosphate
`{LigPO.), lithiumttanium phosphate (LT{PO}, 0 < xe 2,0 <y <3). itbum aluminum itenium phosphate (LiALt
`LAPOy},, Osx<2Oeyst, OQ < z <3}, (LIAITIP).O, based glass (0 <x < 4,0 < y < 73) such as 14Lb0-9AL,0,-38THO,-
`S8P.O., Hihiuen lanthanum Stanate (bari, O< 5 < 2,0 < y < 3), Hthium germanium ihiophosphaie (LiGePS.
`OxxedQeys] G<ze) Oswe<5) such as Lisogbg a5Po7634. ithtunt nitride (LUN. Gxx<4 Q<ye2) such as LigN, SIS,based
`glass (L1,31,5,, Jex<3Oey<2O<z<4) such ag LigPOsLiS-SiS,, PoS, based glass { LIPS,, Gex<3,0<y<30c2<7}euch
`as LB-LiS-PaS., or mixtures thereof,
`[6052] An average pariicle size of the inorganic gariicles is not particularly limited, however, io mainiain @ proper
`corosity, the average particle size may be in a range of 2.01 to & um. or in a range of Of fo 4 wn. orin a range cf 0.2
`te 6.8 pm in this instance, when the average sarticle size of the inorganic particles satisfies this range, problems with
`deterioration it disgersibility of the inorganic particles, causing non-uniform coating, or battery performace degradation
`caused by the clogging of the pores of the porous substrate into which the inorganic particles penelrate when coating
`may be prevented.
`{8053}
`In the separator according to one aspect of the present disclosures, for the binder polymer used to form the
`inorganic opaling bayer, palyrner commonly used in the art lo form an inorganic coating layer may be used. Parlioularly,
`polymer having a glass iransition terperalure (Tg) in a range of ~200 fo ZO0%D may be used io improve the mechanical
`froperties of the resulling inorganic coating layer such as flexibility and elasticity, The binder polymerfaithfully serves
`as a binder to cormect and stably bind the inorganic particles, thereby preventing deterioration in mechanical properties
`of the separator with the inorganic coating layer.
`{O054] Also, the Ginder polymer does not necessarily need fo have anion conduction ability, but when pohyner having
`an ion conduction ability is used, performance of a Wihhura secondary battery may be further mproved. Accordingly, a
`binder polymer having a high dielectric constant as possible may be used, Actually, because a degree of dissociation
`of salts in act electrolyte solution relies on 4 dielectric constant of an electrolyte solvent, as ihe dielectric constant of the
`palymer increases. a degrees of dissaciation of salis in an electrolyte may be improved. An available dielectric constant
`of the binder polyrner may be in a range of 1.0 to 100 (measured al frequency of 1 KHz}, in particular, higher thart or
`equal to 1fb
`{G058]
`Inadditionto the above functions, the binder polymer may have a feature thal exhibits a high degree of awedling
`in aliquid electrolyie solution because the binder polymer is qelled when immersed inthe electrolyte sohiian. Accordingly,
`a solubility parameter of the binder polymeris in a range of 15 to 45 MPa", or in a range af 15 fo 25 MPal’®, or ina
`range of 30 to 45 MPa‘, Thus, rather than hydrophobic polymers such as polyolefins, hydrophilic polymers having
`more polar groups may be used. When the solubéity sarameter is lower than 18 MPall? and higher than 45 MPat,
`swelling ina cormman liquid electrolyle solution for a battery may be difficult,
`{O056] Non-limiting examples of the binder polymer may inchide polyvinyidanefluoride-co-hexafiuorapropyiane, pol-
`yitylidene Hucrkie-co-trichloroethylene, polymethyimethacniale, palybulylacrale, polyacrylanitcdle, polyyvinyloyrro-
`icone, palyvinylacetate, polyethwene-co-vinyl acetate, polyethylene oxide, polyarylate, cellulose acetate, cellulose ac-
`elate butyrate, cellulose acetate propionate, cyaroethylouludan, cyancethyipalyvinylaicohal, cyanoethyloeiuduse, cya-
`noethylsucrose, pullulan, carbaxyl methyl cellulase, and the like.
`{@G87] The inorganic coating layer includes, for examole, the binder polymer in a range of 0.17 to 50 parts by weight,
`of ini a range of T ta 40 parts by weight, or in a range of 5 to 30 parts by weight, based an 100 paris by weight of the
`inorganic partiches,
`{G058] When the content of the Inorganic particles and ihe binder polymerin the inorganic coating layer satisfies this
`range, heat resistance and mechanical properties may be Improved by the coating with the inarganic panticies, and
`adhesion befween the porous substrate and the inorganic partiches may be maintained and a pest-off phenomenon may
`
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`ao
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`‘oh
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`EP 2 785.305 Ad
`
`be prevented.
`{0059}
`In the inorganic ceating layer, the binder polymer binds the inorganic particles together fa maintain @ state in
`which the inargaric particles are adhered to each alher (hat is, the binder palymer connects and binds the inarganic
`particles}, and the Incrqanic coaling layer maintains a bound state with the porous substrate byihe binder polymer. The
`inorganic particles of the inorganic cating layer are present in a closest cacked structure in a substantial contact state
`with each other, and interstitial volumes created in the contact state of the inorganic particles become pares of the
`inorganic coating layer.
`{OUGO] The high heat resistance composite separalor according ta one aspectof the oresent disclosure inchides the
`high heat resistarice polymer coating tayer formed on the ather surfase of the parous substrate, and the high heat
`resistance polymer coating layer inchides the high healresistance colymer and the inorganic particles dispersed in the
`high heat resistance polymer.
`{G064] The high heat resistance polymer represeriis oolymer having a glase transilion temperature (Tq) higher than
`or equal te 150°C or higher than or equal fa 200°C, and among this polymer, particularly, ari aromatic condensation~
`based heat resistance polymer may be primarily used.
`{8062} Accordingly, when the battery fernperalure increases, even if the separatar substrale made fram pofyethylene
`having a melling point in a range of 120 to 130°C or polyorapylene having a melting point in a range of 740 to TOC
`melts, the high heal resistance polymer does not melt, leading fo maintenance of a frame of the separator, a3 a result,
`a shorn circuit inside the battery may be prevented.
`{G063] Asa cor-diniling examole, the high heatresistarnce polymer may be any ane selected fram the graup congisting
`of aromatic palyamide, ararnatic polyimide, aromatic palyamide-imide, aromatic nolyimine, Tefion® {polytetrafluoroeth-
`ylene), polybenzexazale, pohybenzimidazals, palyphenytsulfide and polyphenylene oxide, or mixtures thereof, Also, the
`high heat resistance polymer may include copolymers with other polyrner componenis, far example, of fess than 56
`mole%.
`
`{[G064] As the high heat resistance polymer, particularly, aromatic palyamide ie preferrad, Aramatic polyamide refers
`to a synthetic polymer in which aromatic fags finked by an amide bond (4>ONH-), thal is, an amide bord attached
`directly bebveen two aromatic rings is higher thar or equal io 80 mole%. The aramatic pohwamideis classified inla mela-
`type aramatec polyamide having a flexible molecule chain.and para-type aromatic polyamide having a rgid molecule
`chain, based one molecular slructure.
`{8065}
`Specifically, the aromatic polyamide may have atleast one repeating unit represented by the follawing chemical
`formulae } ard 2:
`
`20
`
`[Chemical Formula1]
`
`—\— Ar —N—C— Ar.-C—
`HO)
`oR OO (1)
`
`[Chemical Formula 2]
`
`—N— Ats-G—
`
`ape
`
`In the above formulme, Ar,, Ars, and Ary may be a divalent aromatic groug selected among groups of the
`{6066}
`following chemical farmulae 3a through Sc:
`
`ao
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`iChernical Fornada 3a]
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`EP 2 785.305 Ad
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`[Chemical Formula 3b]
`
`4+)
`
`{Chemical Formula 30]
`
`XO)*Oy
`
`{Chemical Formula 3d}
`
`Ba
`
`ao
`
`‘oh
`
`{9067}