(12) United States Patent
`Kanai et al.
`
`USOO6872491 B2
`(10) Patent No.:
`US 6,872,491 B2
`(45) Date of Patent:
`Mar. 29, 2005
`
`(54) POSITIVE ELECTRODE ACTIVE MATERIAL (56)
`AND LITHIUM ION SECONDARY BATTERY
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`(75) Inventors: Hideyuki Kanai, Kawasaki (JP);
`Motoya Kanda, Yokohama (JP);
`Koichi Kubo, Yokohama (JP)
`
`6,037,095 A 3/2000 Miyasaka
`6,569,569 B1
`5/2003 Kweon et al.
`2001/OO16284 A1
`8/2001 Kweon et al. .............. 429/224
`2002/0055042 A1
`5/2002 Kweon et al.
`FOREIGN PATENT DOCUMENTS
`''':
`3.1.
`E.
`T-37617
`2/1995
`JP
`12/1998
`10-326621
`JP
`11-345615
`12/1999
`JP
`2001-23641
`1/2001
`JP
`2001-291518
`10/2001
`JP
`* cited by examiner
`Primary Examiner Jonathan Crepeau
`(74) Attorney, Agent, or Firm-Oblon, Spivak, McClelland,
`Maier & Neustadt, P.C.
`(57)
`ABSTRACT
`
`The present invention provides a positive electrode active
`material containing a composite oxide having a composition
`represented by a structural formula (1) given below:
`Li(NiMe1)(O
`A.
`i,(NiMe1)(OX)+
`19 Claims, 2 Drawing Sheets
`
`1.
`(1)
`
`(73) Assignee: Kabushiki Kaisha Toshiba, Tokyo (JP)
`(*) Notice:
`Subject to any disclaimer, the term of this
`past is S. alusted under 35
`
`a --
`
`y
`
`yS.
`
`(30)
`
`(21) Appl. No.: 10/050,926
`(22) Filed:
`Jan. 22, 2002
`(65)
`Prior Publication Data
`US 2002/0150820 A1 Oct. 17, 2002
`Foreign Application PrioritV Dat
`Oe
`CaO. O.
`gn App
`y
`(JP) ....................................... 2001-014891
`Jan. 23, 2001
`(51) Int. Cl. ............................ H01M 4/52; H01 M 4/58
`(52) U.S. Cl. .................... 429/223; 429/221; 429/231.1;
`429/231.3; 429/231.6
`(58) Field of Search ................................. 429/221, 223,
`429/231.1, 2312, 231.3, 231.6
`
`
`
`
`
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`S SS asser S s 2.
`s 63
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`N N S.
`. Yi" NNN
`N.
`N.E.
`WN,
`SN2
`NZ
`NSN
`S2NSA;
`2 Sg
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
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`Samsung Ex. 1020, Page 1 of 30
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`U.S. Patent
`
`Mar. 29, 2005
`
`Sheet 1 of 2
`
`US 6,872,491 B2
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`
`
`
`
`
`
`SZ2Z š,
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`2. Z ````````,
`
`WINNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNYY. //
`
`WUZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZW//
`
`KOESOE,CYSTARIST?STSTASTRO
`
`F. G. 1
`
`
`
`
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`
`
`?SK? K?TSTARTKIN KOEST, STS?TA S?
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`U.S. Patent
`
`Mar. 29, 2005
`
`Sheet 2 of 2
`
`US 6,872,491 B2
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`
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`
`AZZZZZZZ
`
`ZZZZZZ
`
`f7ZZZZZZZZZYZZYZZYZ
`SQ S S SSS
`SS
`YZ2/2ZZY/77ZZYZ
`
`
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`US 6,872,491 B2
`
`1
`POSITIVE ELECTRODE ACTIVE MATERIAL
`AND LITHIUM ION SECONDARY BATTERY
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`This application is based upon and claims the benefit of
`priority from prior Japanese Patent Application No. 2001
`014891, filed Jan. 23, 2001, the entire contents of which are
`incorporated herein by reference.
`
`BACKGROUND OF THE INVENTION
`
`2
`temperatures So as to cause Mn to elute into the nonaqueous
`electrolyte, giving rise to the defect noted above.
`Particularly, a large lithium ion Secondary battery has been
`developed in recent years in various technical fields for use
`in an electric automobile or in road leveling. In the large
`lithium ion Secondary battery, the heat generation during the
`use of the Secondary battery is rendered non-negligible with
`enlargement in the size of the lithium ion Secondary battery,
`with the result that the temperature inside the battery tends
`to be rendered relatively high even if the ambient tempera
`ture is close to room temperature. Also, even when it come
`to a relatively Small battery used in, for example, a Small
`portable electronic appliance, it is possible for the battery to
`be used under a high temperature environment Such as
`within a room of a vehicle in the midsummer, with the result
`that it is possible for the temperature inside the battery to be
`rendered relatively high. Under the circumstances, it is very
`difficult to put a positive electrode active material using
`manganese as a raw material to practical use.
`Researches on the nickel composite oxides are being
`Vigorously carried out as post cobalt composite oxides. A
`nickel composite oxide, e.g., LiNiO, exhibits a theoretical
`capacity of 180 to 200 mAh/g, which is larger than that of
`each of the LiCoO series active material and the LiMnO,
`Series active material. In addition, LiNiO has an optimum
`discharge potential of about 3.6 V on the average and, thus,
`provides a highly hopeful positive electrode active material.
`However, the crystal Structure of LiNiO is unstable, giving
`rise to the problem that the initial discharge capacity is
`greatly lowered in the charge-discharge cycle test with
`increase in the number of the charge-discharge cycles, and
`to the additional problem in Safety that rupture and ignition
`are brought about in the nail Sticking test of the lithium ion
`Secondary battery prepared by using LiNiO.
`On the other hand, claim 1 of Japanese Patent Disclosure
`(Kokai) No. 10-326621 recites a secondary battery compris
`ing a positive electrode using a lithium-containing metal
`composite oxide as an active material, a negative electrode
`using a metal composite oxide having an amorphous
`Structure, and a nonaqueous electrolyte. Used as the active
`material of the positive electrode is a nickel-containing
`lithium composite oxide represented by Li, NiM,Os-Xa,
`where M represents at least one kind of an element Selected
`from the group consisting of the elements of Group 2, Group
`13, Group 14 of the Periodic Table and the transition metals,
`X represents a halogen atom, and x, y, Z and a are defined to
`be 0.2<Xs 1.2, Osys 0.5,0s Zs 1 and Osas 2Z.
`Also, the heading 0010) of the Japanese Patent document
`quoted above refers to the desirable concentrations of impu
`rities other than the elements Li, Ni, Co and M contained in
`the positive electrode active material represented by the
`Structural formula given above. Specifically, the Japanese
`Patent document quoted above teaches that it is desirable for
`the concentration of the impurity Fe to be not higher than
`0.01% by weight (not higher than 100 ppm), for the con
`centration of the impurity Cu to be not higher than 0.01% by
`weight (not higher than 100 ppm), and for the concentration
`of each of the impurities Ca, Na and Sulfate group (SO) to
`be not higher than 0.05% by weight (not higher than 500
`ppm). Also, the Japanese Patent document quoted above
`teaches that it is desirable for the concentration of the water
`(HO) to be not higher than 0.1% by weight.
`What should be noted is that the elements other than those
`Specified in the Structural formula, i.e., Fe, Cu, Na and
`Sulfate group SO, are impurities in the Japanese Patent
`document in question and, thus, should desirably be con
`tained in a Smaller amount.
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`1. Field of the Invention
`The present invention relates to a positive electrode active
`material containing a lithium-containing nickel oxide and to
`a lithium ion Secondary battery equipped with the positive
`electrode active material.
`2. Description of the Related Art
`In recent years, electronic appliances Such as portable
`personal computers and portable telephones are being min
`iaturized and made lightweight, and miniaturization and
`reduction of weight are being required for the Secondary
`batteries used as power Sources for these electronic appli
`CCS.
`A lithium ion Secondary battery using as a material of the
`negative electrode a Substance capable of absorbing
`deSorbing lithium ions Such as a carbon material has been
`developed as a Secondary battery meeting the requirement
`described above, and has been put to a practical use as a
`power Source for Small electronic appliances. The Secondary
`battery is Smaller and lighter, and has a higher energy
`density, than a conventional lead accumulator or nickel
`cadmium battery, and the demands for this particular Sec
`ondary battery is on the increase.
`A lithium-containing cobalt oxide (LiCoO), which per
`mits a high discharge potential and a high energy density to
`be obtained, has been put to a practical use as a positive
`electrode active material of the lithium ion Secondary bat
`tery. However, the amount of natural resources of cobalt
`used as the raw material of the complex compound is very
`Small, and the ore deposit that can be commercially utilized
`is unevenly distributed in a Small number of countries. AS a
`result, cobalt is costly and invites a large fluctuation in price.
`It follows that the cobalt supply in the future will be
`unstable.
`Under the circumstances, researches into positive elec
`trode active materials other than lithium-containing cobalt
`oxide have been Vigorously carried out in recent years. For
`example, various compounds are reported in respect of the
`composite oxides between lithium and manganese, which
`are Synthesized by various manganese raw materials and
`lithium raw material. To be more specific, lithium manga
`nese composite oxide represented by LiMnO, having a
`Spinel type crystal structure is allowed to exhibit 3 V of
`potential relative to lithium by electrochemical oxidation
`and has a theoretical charge-discharge capacity of 148
`mAh/g.
`However, the lithium ion Secondary battery using a man
`60
`ganese oxide or a lithium manganese composite oxide as the
`positive electrode active material gives rise to the defect
`that, when the Secondary battery is used under an environ
`ment not lower than room temperature, the deterioration in
`the capacity of the Secondary battery is markedly increased.
`It should be noted that the manganese oxide or the lithium
`manganese composite oxide is rendered unstable under high
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`US 6,872,491 B2
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`3
`BRIEF SUMMARY OF THE INVENTION
`An object of the present invention is to provide a positive
`electrode active material capable of eliminating rupture and
`ignition in the nail Sticking test and also capable of improv
`ing the large discharge characteristics (discharge rate
`characteristics) and to provide a lithium ion Secondary
`battery equipped with the particular positive electrode active
`material.
`According to a first aspect of the present invention, there
`is provided a lithium ion Secondary battery, comprising:
`a positive electrode comprising an active material con
`taining a composite oxide;
`a negative electrode, and
`a nonaqueous electrolyte,
`the composite oxide having a composition represented by
`a structural formula (1) given below:
`(1)
`Li,(NiMe1)(OX)+A
`where Me1 is at least one kind of an element selected
`from the group consisting of B, Mg, Al, Sc., Ti, V, Cr, Mn,
`Co, Cu, Zn, Ga, Y, Zr, Nb, Mo, Tc, Ru, Sn, La, Hf, Ta, W.
`Re, Pb, and Bi, X is at least one kind of a halogen element
`Selected from the group consisting of F, Cl, Br and I, the
`molar ratios x, y, z are 0.02sXs 1.3, 0.005 sys 0.5, and
`0.01s Zs0.5, A contains at least one element selected from
`the group consisting of Na, K and S, and each of the Na
`content, the K content and the S content of the composite
`oxide falls within a range of between 600 ppm and 3,000
`ppm.
`According to a Second aspect of the present invention,
`there is provided a lithium ion Secondary battery, compris
`Ing:
`a positive electrode comprising an active material con
`taining a composite oxide;
`a negative electrode, and
`a nonaqueous electrolyte,
`the composite oxide having a composition represented by
`a structural formula (2) given below:
`
`where Me1 is at least one kind of an element selected
`from the group consisting of B, Mg, Al, Sc., Ti, V, Cr, Mn,
`Co, Cu, Zn, Ga, Y, Zr, Nb, Mo, Tc, Ru, Sn, La, Hf, Ta, W.
`Re, Pb, and Bi, X is at least one kind of a halogen element
`Selected from the group consisting of F, Cl, Br and I, the
`molar ratios x, y, z are 0.02sXs 1.3, 0.005 sys 0.5, and
`0.01s Zs0.5, A contains at least one element selected from
`the group consisting of Na, K and S, and each of the Na
`content, the K content and the S content of the composite
`oxide falls within a range of between 600 ppm and 3,000
`ppm, B contains at least one element Selected from the group
`consisting of Si and Fe, and the content b of the element B
`in the composite oxide falls within a range of between 20
`ppm and 500 ppm.
`According to a third aspect of the present invention, there
`is provided a lithium ion Secondary battery, comprising:
`a positive electrode comprising an active material con
`taining a composite oxide;
`a negative electrode, and
`a nonaqueous electrolyte,
`the composite oxide having a composition represented by
`a structural formula (3) given below:
`(3)
`Li(NiCo, Me2)(OX)+A
`where Me2 is at least one kind of an element selected
`from the group consisting of B, Mg, Al, Sc., Ti, V, Cr, Mn,
`
`4
`Cu, Zn, Ga, Y, Zr, Nb, Mo, Tc, Ru, Sn, La, Hf, Ta, W, Re,
`Pb, and Bi, X is at least one kind of a halogen element
`Selected from the group and Z are 0.02 SXS 1.3,
`0.005 s vs 0.5, consisting of F, Cl, Brand L, the molar ratios
`X, v, S and Z are 0.02s Xs 1.3, 0.005s vs 0.5,0.005ssis 0.5
`and 0.01s ZSO.5. A contains at least one element Selected
`from the group consisting of Na, K and S, and each of the
`Na content, the K content and the S content of the composite
`oxide falls within a range of between 600 ppm and 3,000
`ppm.
`According to a fourth aspect of the present invention,
`there is provided a lithium ion Secondary battery, compris
`Ing:
`a positive electrode comprising an active material con
`taining a composite oxide;
`a negative electrode; and
`a nonaqueous electrolyte,
`the composite oxide having a composition represented by
`a structural formula (4) given below:
`(4)
`Li(NiCo, Me2)(OX)+A+bB
`where Me2 is at least one kind of an element selected
`from the group consisting of B, Mg, Al, Sc., Ti, V, Cr, Mn,
`Cu, Zn, Ga, Y, Zr, Nb, Mo, Tc, Ru, Sn, La, Hf, Ta, W, Re,
`Pb, and Bi, X is at least one kind of a halogen element
`Selected from the group consisting of F, Cl, Br and I, the
`molar ratioS X, V, S and Z are 0.02s Xs 1.3, 0.005s vs 0.5,
`0.005ssis 0.5 and 0.01s Zs0.5, A contains at least one
`element Selected from the group consisting of Na, K and S,
`each of the Na content, the K content and the S content of
`the composite oxide falls within a range of between 600 ppm
`and 3,000 ppm, B contains at least one element Selected
`from the group consisting of Si and Fe, and the content b of
`the element B in the composite oxide falls within a range of
`between 20 ppm and 500 ppm.
`According to a fifth aspect of the present invention, there
`is provided a positive electrode active material containing a
`composite oxide having a composition represented by a
`structural formula (1) given below:
`(1)
`Li,(NiMe1)(OX)+A
`where Me1 is at least one kind of an element selected
`from the group consisting of B, Mg, Al, Sc., Ti, V, Cr, Mn,
`Co, Cu, Zn, Ga, Y, Zr, Nb, Mo, Tc, Ru, Sn, La, Hf, Ta, W.
`Re, Pb, and Bi, X is at least one kind of a halogen element
`Selected from the group consisting of F, Cl, Br and I, the
`molar ratios x, y, z are 0.02sXs 1.3, 0.005 sys 0.5, and
`0.01s Zs0.5, A contains at least one element selected from
`the group consisting of Na, K and S, and each of the Na
`content, the K content and the S content of the composite
`oxide falls within a range of between 600 ppm and 3,000
`ppm.
`According to a sixth aspect of the present invention, there
`is provided a positive electrode active material containing a
`composite oxide having a composition represented by a
`structural formula (2) given below:
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`where Me1 is at least one kind of an element selected
`from the group consisting of B, Mg, Al, Sc., Ti, V, Cr, Mn,
`Co, Cu, Zn, Ga, Y, Zr, Nb, Mo, Tc, Ru, Sn, La, Hf, Ta, W.
`Re, Pb, and Bi, X is at least one kind of a halogen element
`Selected from the group consisting of F, Cl, Br and I, the
`molar ratios x, y, z are 0.02sXs 1.3, 0.005 sys 0.5, and
`0.01s Zs0.5, A contains at least one element selected from
`the group consisting of Na, K and S, and each of the Na
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`S
`content, the K content and the S content of the composite
`oxide falls within a range of between 600 ppm and 3,000
`ppm, B contains at least one element Selected from the group
`consisting of Si and Fe, and the content b of the element B
`in the composite oxide falls within a range of between 20
`ppm and 500 ppm.
`According to a Seventh aspect of the present invention,
`there is provided a positive electrode active material con
`taining a composite oxide having a composition represented
`by a structural formula (3) given below:
`(3)
`Li(NiCo, Me2)(OX)+A
`where Me2 is at least one kind of an element selected
`from the group consisting of B, Mg, Al, Sc., Ti, V, Cr, Mn,
`Cu, Zn, Ga, Y, Zr, Nb, Mo, Tc, Ru, Sn, La, Hf, Ta, W. Re,
`Pb, and Bi, X is at least one kind of a halogen element
`Selected from the group consisting of F, Cl, Br and I, the
`molar ratioS X, V, S and Z are 0.02s Xs 1.3, 0.005s vs 0.5,
`0.005ssis 0.5 and 0.01s Zs0.5, A contains at least one
`element Selected from the group consisting of Na, K and S,
`and each of the Na content, the K content and the S content
`of the composite oxide falls within a range of between 600
`ppm and 3,000 ppm.
`According to an eighth aspect of the present invention,
`there is provided a positive electrode active material con
`taining a composite oxide having a composition represented
`by a structural formula (4) given below:
`(4)
`Li(NiCo, Me2)(OX)+A+bB
`where Me2 is at least one kind of an element selected
`from the group consisting of B, Mg, Al, Sc., Ti, V, Cr, Mn,
`Cu, Zn, Ga, Y, Zr, Nb, Mo, Tc, Ru, Sn, La, Hf, Ta, W, Re,
`Pb, and Bi, X is at least one kind of a halogen element
`Selected from the group consisting of F, Cl, Br and I, the
`molar ratioS X, V, S and Z are 0.02s Xs 1.3, 0.005s vs 0.5,
`0.005ssis 0.5 and 0.01s Zs0.5, A contains at least one
`element Selected from the group consisting of Na, K and S,
`each of the Na content, the K content and the S content of
`the composite oxide falls within a range of between 600 ppm
`and 3,000 ppm, B contains at least one element Selected
`from the group consisting of Si and Fe, and the content b of
`the element B in the composite oxide falls within a range of
`between 20 ppm and 500 ppm.
`BRIEF DESCRIPTION OF THE SEVERAL
`DRAWINGS
`FIG. 1 is an oblique View, partly broken away, showing a
`cylindrical lithium ion Secondary battery as an example of a
`lithium ion Secondary battery according to one embodiment
`of the present invention;
`FIG. 2 is a croSS-Sectional view showing a thin lithium ion
`Secondary battery as an example of a lithium ion Secondary
`battery according to another embodiment of the present
`invention;
`FIG. 3 is a cross-sectional view showing in a magnified
`fashion a portion A shown in FIG. 2; and
`FIG. 4 schematically shows the crystal structure of a
`lithium-containing composite oxide, which is contained in
`the lithium ion secondary battery for Example 1 of the
`present invention.
`DETAILED DESCRIPTION OF THE
`INVENTION
`The lithium ion Secondary battery according to one
`embodiment of the present invention comprises a positive
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`US 6,872,491 B2
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`6
`electrode containing an active material, a negative electrode,
`and a nonaqueous electrolyte. The active material noted
`above includes at least one kind of the positive electrode
`active material Selected from the group consisting of first to
`Sixth positive electrode active materials described herein
`later.
`The nonaqueous electrolyte used in the present invention
`includes, for example, a liquid nonaqueous electrolyte pre
`pared by, for example, dissolving a Solute in a nonaqueous
`Solvent, a polymer gel-like nonaqueous electrolyte in which
`a nonaqueous Solvent and a Solute are held by a polymer
`material, a polymer Solid electrolyte containing a Solute as
`a main component, and an inorganic Solid nonaqueous
`electrolyte having a lithium ionic conductivity. Incidentally,
`what is described in conjunction with the liquid nonaqueous
`electrolyte described herein later can be used as the non
`aqueous Solvent and the Solute contained in each of the
`nonaqueous electrolytes.
`The polymer material contained in the gel-like nonaque
`ous electrolyte noted above includes, for example,
`polyacrylonitrile, polyacrylate, polyvinylidene fluoride
`(PVdF), polyethylene oxide (PEO), and polymers contain
`ing acrylonitrile, acrylate, Vinylidene fluoride or ethylene
`oxide as the monomer unit. The polymer material contained
`in the polymer Solid electrolyte noted above includes, for
`example, polyacrylonitrile, polyvinylidene fluoride (PVdF),
`polyethylene oxide and polymers containing acrylonitrile,
`Vinylidene fluoride or ethylene oxide as a monomer unit. On
`the other hand, the inorganic Solid nonaqueous electrolyte
`noted above includes, for example, a lithium-containing
`ceramic material. To be more specific, LiN, Li-PO
`LiS-SiS glass, etc., can be used as the inorganic Solid
`nonaqueous electrolyte.
`An example of a lithium ion Secondary battery according
`to the present invention will now be described.
`The lithium ion secondary battery of the present invention
`comprises a positive electrode containing at least one kind of
`a positive electrode active material Selected from the group
`consisting of first, Second, third, fourth, fifth, and Sixth
`positive electrode active materials, a negative electrode, a
`Separator arranged between the positive electrode and the
`negative electrode, and a liquid nonaqueous electrolyte
`impregnated in at least the Separator.
`Each of the positive electrode, the Separator, the negative
`electrode and the liquid nonaqueous electrolyte will now be
`described in detail.
`1) Positive Electrode
`The positive electrode includes a current collector and a
`positive electrode layer Supported by the current collector
`and containing at least one kind of a positive electrode active
`material Selected from the group consisting of first, Second,
`third, fourth, fifth and sixth positive electrode active mate
`rials given below:
`(First Positive Electrode Active Material)
`The first positive electrode active material contains a
`composite oxide having a composition represented by
`chemical formula (1) given below:
`(1)
`Li(NiMe1)(OX)+A
`where Me1 is at least one kind of an element selected
`from the group consisting of B, Mg, Al, Sc., Ti, V, Cr, Mn,
`Co, Cu, Zn, Ga, Y, Zr, Nb, Mo, Tc, Ru, Sn, La, Hf, Ta, W.
`Re, Pb, and Bi, X is at least one kind of a halogen element
`Selected from the group consisting of F, Cl, Br and I, the
`molar ratios x, y, z are 0.02sXs 1.3, 0.005 sys 0.5, and
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`0.01s Zs0.5, A contains at least one element selected from
`the group consisting of Na, K and S, and each of the Na
`content, the K content and the S content of the composite
`oxide falls within a range of between 600 ppm and 3,000
`ppm.
`If the molar ratio X of lithium is less than 0.02, the crystal
`Structure of the composite oxide is rendered highly unstable,
`with the result that the cycle characteristics of the Secondary
`battery are degraded and the safety is lowered. On the other
`hand, if the molar ratio X of lithium exceeds 1.3, the
`discharge capacity and the Safety of the Secondary battery
`are lowered. It is more desirable for the molar ratio X of
`lithium to fall within a range of between 0.05 and 1.2.
`The molar ratio y of the element Me 1 should fall within
`a range of between 0.005 and 0.5. If the molar ratio y is
`lower than 0.005, it is difficult to improve the safety of the
`secondary battery. On the other hand, if the molar ratio y
`exceeds 0.5, the discharge capacity of the Secondary battery
`is markedly decreased. It is more desirable for the molar
`ratio y of the element Me 1 to fall within a range of between
`0.01 and 0.35. Among the elements represented by Me 1, it
`is desirable to use Al, Ti, Mn, Nb or Ta.
`The molar ratio Z of the halogen element X should fall
`within a range of between 0.01 and 0.5. If the molar ratio z
`is less than 0.01, it is difficult to improve the cycle charac
`teristics and the safety of the secondary battery. On the other
`hand, if the molar ratio Z exceeds 0.5, the discharge capacity
`of the Secondary battery is markedly decreased. It is more
`desirable for the molar ratio Z of the halogen element X to
`fall within a range of between 0.02 and 0.3. Also, among the
`halogen elements X, it is desirable to use F.
`In one of the desired compositions of the composite oxide
`used in the present invention, the halogen element X con
`tains F, the molar ratio x falls within a range of between 0.05
`and 1.2, the molar ratio y falls within a range of between
`0.01 and 0.35, and the molar ratio Z falls within a range of
`between 0.02 and 0.3.
`The composite oxide used in the present invention con
`tains an element A. The composite oxide containing the
`element A is capable of Suppressing a rapid increase in the
`battery temperature when a large current flows through the
`Secondary battery by, for example, a short circuit So as to
`improve the Safety of the Secondary battery.
`Where Na is contained in the composite oxide, the Na
`content should fall within a range of between 600 ppm and
`45
`3,000 ppm. If the Na content is lower than 600 ppm, it is
`impossible to obtain a high discharge capacity when the
`Secondary battery is discharged at a high rate. On the other
`hand, if the Na content exceeds 3,000 ppm, the charge
`discharge cycle characteristics of the Secondary battery are
`degraded. It is more desirable for the Na content to fall
`within a range of between 1,000 ppm and 2,500 ppm. Where
`the Na content falls within a range of between 1,000 ppm
`and 2,500 ppm, it is possible to SuppreSS the reduction in the
`capacity when the charge-discharge cycle in which the
`discharge is performed at a high rate is repeated.
`Where K is contained in the composite oxide, the K
`content should fall within a range of between 600 ppm and
`3,000 ppm. If the K content of the composite oxide is lower
`than 600 ppm, it is impossible to obtain a high discharge
`capacity when the Secondary battery is discharged at a high
`rate. On the other hand, if the K content exceeds 3,000 ppm,
`the charge-discharge cycle characteristics of the Secondary
`battery are degraded. It is more desirable for the K content
`to fall within a range of between 1,000 ppm and 2,500 ppm.
`If the K content is set to fall within a range of between 1,000
`ppm and 2,500 ppm, it is possible to Suppress the reduction
`
`50
`
`55
`
`60
`
`65
`
`8
`of the capacity when the charge-discharge cycle in which the
`discharge is performed at a high rate is repeated.
`Where S is contained in the composite oxide, the S
`content should fall within a range of between 600 ppm and
`3,000 ppm. If the S content of the composite oxide is lower
`than 600 ppm, it is impossible to obtain a high discharge
`capacity when the Secondary battery is discharged at a high
`rate. On the other hand, if the S content exceeds 3,000 ppm,
`the charge-discharge cycle characteristics of the Secondary
`battery are degraded. It is more desirable for the S content
`to fall within a range of between 1,000 ppm and 2,500 ppm.
`If the S content is set to fall within a range of between 1,000
`ppm and 2,500 ppm, it is possible to Suppress the reduction
`of the capacity when the charge-discharge cycle in which the
`discharge is performed at a high rate is repeated.
`It is desirable for the element A to include Ca in addition
`to at least one kind of the element Selected from the group
`consisting of Na, Kand S. It is desirable for the Ca content
`of the composite oxide to be not higher than 500 ppm. The
`Ca content of the composite oxide exceeding 500 ppm tends
`to promote the deterioration in any of the charge-discharge
`cycle characteristics, the large current discharge character
`istics and the high rate charge-discharge characteristics. It is
`more desirable for the Ca content to fall within a range of
`between 20 ppm and 500 ppm. If the Ca content is set to fall
`within a range of between 20 ppm and 500 ppm, it is
`possible to improve markedly the large current discharge
`characteristics (discharge rate characteristics) or the high
`rate charge-discharge characteristics. It is furthermore desir
`able for the Ca content to fall within a range of between 50
`ppm and 500 ppm.
`It is possible to improve sufficiently the safety of the
`Secondary battery even if the elements A are added Singly.
`However, it is possible to further improve the safety of the
`Secondary battery by adding a plurality of kinds of the
`elements A in combination. The desirable combinations of
`the elements A include a combination of Na and S, a
`combination of Ca, Na and S, a combination of Na and Ca,
`and a combination of S and Ca.
`It is desirable for the total content “a” of the elements. A
`in the composite oxide to fall within a range of between 600
`ppm and 7000 ppm. If the total content “a” of the elements
`A is lower than 600 ppm, it is difficult to improve the large
`current discharge characteristics of the Secondary battery.
`On the other hand, if the total content “a” of the elements. A
`exceeds 7000 ppm, the charge-discharge cycle characteris
`tics of the Secondary battery tends to be degraded. It is more
`desirable for the total content “a” of the elements. A to fall
`within a range of between 1000 ppm and 5000 ppm.
`In the composite oxide represented by the chemical
`formula (1), it is desirable for at least a part of the element
`A contains at least one element Selected from the group
`consisting of Na, K, S and Cato be Segregated. Particularly,
`it is desirable for at least a part of the element A to be
`precipitated in triple points present in grain boundaries of
`the composite oxide. If the crystal Structure of the composite
`oxide is constructed to meet the particular requirement, it is
`possible to further improve both the safety and the cycle
`characteristics of the Secondary battery.
`The composite oxide used in the present invention can be
`manufactured by, for example, a Solid State reaction process,
`a coprecipitation process, or hydrothermal Synthesis.
`Particularly, it is desirable to obtain the composite oxide
`having a composition represented by chemical formula (1)
`by firing a powdery mixture of the compounds of each
`element at 450 to 550° C. for 2 to 20 hours with an oxygen
`gas flow, followed by further firing the mixture at 630 to
`
`Samsung Ex. 1020, Page 7 of 30
`Samsung Electronics Co., Ltd. v. RJ Technology, LLC
`IPR2023-01183
`
`

`

`US 6,872,491 B2
`
`15
`
`9
`730 C. for 2 to 50 hours with an oxygen gas flow. If the heat
`treating temperature in the first stage exceeds 550° C. or if
`the heat treating temperature in the Second Stage exceeds
`730 C., the element A melts so as to be attached to the
`Surface of the particle. As a result, the et absorption
`desorption of lithium is inhibited so as to make it difficult to
`further improve the Safety and the cycle characteristics of
`the Secondary battery. By applying the two Stage heat
`treatment in which the firing temperature and the firing time
`are defined to fall within the ranges noted above, it is
`possible to arrange regularly the Structure of the oxygen
`layer-Li layer-oxygen layer-(Ni+Me 1) layer-oxygen layer
`Lilayer and to permit the precipitation of the element A in
`triple points present in boundaries of the crystal grains. AS
`a result, it is possible to further improve the Safety and the
`charge-discharge cycle characteristics of the Secondary bat
`tery.
`As described above, the lithium ion secondary battery of
`the present invention comprising a positive electrode con
`taining the first positive electrode active material permits
`Suppressing a rapid elevation of the battery temperature
`when a large current flows therethrough under the State of a
`Short circuit as in the nail Sticking test, making it possible to
`prevent in advance rupture and ignition. It follows that the
`Safety of the Secondary battery can be improved. It is
`25
`considered reasonable to understand that the element A
`containing at least one element Selected from the group
`consisting of Na, K, Ca and S serves to lower the Seri