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`Source IP, do solemnly and sincerely declare that the following is, to the best of my
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`knowledge and belief, a true and correct translation of the document(s) listed below in a
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`form that best reflects the intention and meaning of the original text.
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`these statements were made with the knowledge that willful false statements and the like
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`so made are punishable by fine or imprisonment, or both, under Section 1001 of Title 18
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`of the United States Code.
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`The document is designated as: #89467_JP7-122298-Yasunami
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`___________________
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`Frank McGee
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`May 17, 2023
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`244 Fifth Avenue, Suite R269, New York N.Y. 10001 | www.sourceip.com | info@sourceip.com
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`APPLE-1006
`
`1
`
`

`

`(19) [Issuing Country] Japan Patent Office (JP)
`(12) [Publication Name] Gazette of Unexamined Patent Applications (A)
`(11) [Publication Number] H07-122298
`(43) [Publication Date] May 12, 1995
`
`[ID Codes]
`
`(51) [Int.Cl.6]
`H01M 10/40
`4/58
`10/44
`[Examination Request] Not Yet Received
`[Number of Claims] 9
`[Application Format] Online (OL)
`[Total Number of Pages] 15
`
`[Internal Ref. Nos.] [FI]
`Z
`
` [Tech. Indicators]
`
`Z
`
`(21) [Application Number] H05-263696
`(22) [Filing Date] October 21, 1993
`(71) [Applicant]
`[Identification Number] 000005201
`[Name] FUJIFILM Corporation
`[Address] 210 Nakanuma, Minamiashigara-shi, Kanagawa-ken
`(72) [Inventor]
`[Name] Shoichiro YASUNAMI
`[Address] FUJIFILM Corporation, 210 Nakanuma, Minamiashigara-shi, Kanagawa-ken
`
`2
`
`

`

`JP H07-122298 A
`
`(54) [Title of the Invention]
`
`Method for Charging and Discharging Non-Aqueous Secondary Batteries
`
`(57) [Abstract]
`
`[Purpose]
`
`To provide a non-aqueous secondary battery having a large discharge capacity, a high
`discharge operating voltage, and good charge/discharge cycle characteristics, and to provide
`a charging and discharging method.
`
`[Constitution]
`
`A non-aqueous secondary battery having a negative electrode active material that is a
`lithium-containing transition metal oxide represented by LixMOj (where M represents at least
`one transition metal selected from Ti, V, Mn, Co, Fe, Ni, Nb, and Mo, x is in the range from
`0.17 to 11.25, and j is in the range from 1.6 to 4.1) and a positive electrode active material
`that is a lithium-containing transition metal oxide represented by LiyNOz (where N
`represents at least one transition metal selected from Co, Mn, Ni, V, and Fe, y is in the
`range from 0.2 to 1.2, and z is in the range from 1.4 to 3) and that is set to an end-of-
`charge voltage of 3.5 to 4.7 V, wherein the non-aqueous secondary battery incorporates a
`method of performing charging after the battery has been discharged to 0.5 to 1.5 V in the
`charge-discharge cycle.
`
`3
`
`

`

`JP H07-122298 A
`
`[Claims]
`
`[Claim 1]
`
`A method for charging and discharging a non-aqueous secondary battery including a
`positive electrode active material, a negative electrode active material, and a non-aqueous
`electrolyte containing a lithium salt, wherein the negative electrode active material is a
`lithium-containing transition metal oxide represented by LixMOj (where M represents at least
`one transition metal selected from Ti, V, Mn, Co, Fe, Ni, Nb, and Mo, x is in the range from
`0.17 to 11.25, and j is in the range from 1.6 to 4.1), and the positive electrode active
`material that is a lithium-containing transition metal oxide represented by LiyNOz (where N
`represents at least one transition metal selected from Co, Mn, Ni, V, and Fe, y is in the
`range from 0.2 to 1.2, and z is in the range from 1.4 to 3), and an end-of-charge voltage
`set from 3.5 to 4.7 V, the method comprising performing charging after the battery has
`been discharged to 0.5 to 1.5 V in the charge-discharge cycle.
`
`[Claim 2]
`
`The method for charging and discharging a non-aqueous secondary battery according to
`claim 1, wherein the end-of-discharge voltage used is 1.5 V or more and 3.0 V or less.
`
`[Claim 3]
`
`The method for charging and discharging a non-aqueous secondary battery according to
`claim 1, wherein the end-of-discharge voltage used is 0.5 V or more and 1.5 V or less.
`
`[Claim 4]
`
`The method for charging and discharging a non-aqueous secondary battery according to
`claim 1, wherein the negative electrode active material is a transition metal oxide in which
`the basic structure of the crystal is changed by inserting lithium ions, and the basic
`structure of the crystal after the change does not change due to charging and discharging.
`
`[Claim 5]
`
`The non-aqueous secondary battery according to claim 1, wherein the transition metal oxide
`before lithium ion insertion comprises a transition metal oxide represented by LipMOj (where
`M represents at least one transition metal selected from Ti, V, Mn, Co, Fe, Ni, Cr, Nb and Mo,
`p is in the range from 0 to 3.1, and j is in the range from 1.6 to 4.1).
`
`[Claim 6]
`
`The non-aqueous secondary battery according to claim 1 or claim 2, wherein the negative
`electrode active material is a transition metal oxide with electrochemically inserted lithium
`ions.
`
`[Claim 7]
`
`The method for charging and discharging a non-aqueous secondary battery according to
`claim 1, wherein the negative electrode active material is obtained by inserting lithium ions
`into a transition metal oxide produced by firing.
`
`[Claim 8]
`
`4
`
`

`

`JP H07-122298 A
`
`The method for charging and discharging a non-aqueous secondary battery according to
`claim 1, wherein the negative electrode active material comprises a lithium-containing
`transition metal oxide represented by LixMqV1-qOj (where M represents a transition metal, p
`is in a range from 0 to 3.1, x is in a range from 0.17 to 11.25, q is in a range from 0 to 0.7,
`and j is in a range from 1.3 to 4.1).
`
`[Claim 9]
`
`The method for charging and discharging a non-aqueous secondary battery according to
`claim 1, wherein the positive electrode active material comprises of a lithium-containing
`transition metal oxide represented by LiyCoO2, LiyNiO2, LiyCoaNi1-aO2, LiyCob V1-bO2, LiyCobFe1-
`bO2, LiyMn2O4, LiyMncCo2-cO4, LiyMncNi2-cO4, LiyMnc V2-cO4 and LiyMncFe2-cO4 (where y is in the
`range from 0.5 to 1.2, a is in the range from 0.1 to 0.9, b is in the range from 0.8 to 0.98, c
`is in the range from 1.6 to 1.96, and z is in the range from 2.01 to 2.3).
`
`[Detailed Description of the Invention]
`
`[0001]
`
`[Field of Industrial Applicability]
`
`The present invention relates to a charging and discharging method for a non-aqueous
`secondary battery that has improved charge/discharge cycle characteristics.
`
`[0002]
`
`[Prior Art]
`
`Lithium metal and lithium alloys are typically used as negative electrode active materials in
`non-aqueous secondary batteries. When they are used, lithium metal grows in dendrite
`form during charging and discharging, causing internal short circuits, and because the
`activity of dendritic metal is high, there is an increased risk of ignition. Meanwhile, fired
`carbonaceous materials capable of occluding and releasing lithium have recently come into
`use. These excellent carbonaceous materials have a relatively low risk of ignition and high
`charge/discharge capacities. However, because carbonaceous materials are conductive,
`lithium metal may be deposited on carbonaceous materials during overcharge or rapid
`charging, resulting in the deposition of dendritic metal. In order to avoid this problem,
`methods have been adopted to prevent overcharging by reconfiguring chargers and
`reducing the amount of positive electrode active material. The latter method reduces the
`amount of active material, and so places limits on the discharge capacity. Also, because
`carbonaceous materials have a relatively low density, the discharge capacity per volume is
`low. As a result, the discharge capacity is constrained by both the restrictions placed on the
`amount of active material used and the low capacity per volume.
`
`[0003]
`
`Negative electrode active materials other than lithium metal, lithium alloys, and
`carbonaceous materials that are known to be used include TiS2 and LiTiS2 which can occlude
`and release lithium ions (US 3983476 A), WO2 with a rutile structure (US 4198476 A),
`spinel compounds such as LixFe(Fe2)O4 (JP S58-220362 A), electrochemically synthesized
`lithium compounds of Fe2O3 (US 4464447 A), Lithium compounds of Fe2O3 (JP H03-112070
`
`5
`
`

`

`A), Nb2O5 (JP S62-059412 B2, JP H02-082447 A), iron oxide, FeO, Fe2O3, Fe3O4, cobalt
`oxide, CoO, Co2O3, and Co3O4 (JP H03-291862 A).
`
`[0004]
`
`JP H07-122298 A
`
`Known combinations of negative electrode active materials and positive electrode active
`materials that are metal chalcogenides include TiS2 and LiTiS2 (US 983476 A), chemically
`synthesized Li0.1 V2O5 and LiMn1-sMesO2 (where 0.1 < s < 1 and Me = transition metal; JP
`S63-210028 A), chemically synthesized Li0.1 V2O0.1 and LiCo1-SFesO2 (where s = 0.05 to 0.3;
`JP S63-211564 A), chemically synthesized Li0.1V2O5 and LiCo1-SNiSO2(where s = 0.5 to 0.9;
`JP H01-294364 A), V2O5 and Nb2O5 + lithium metal (JP H02-082447 A), V2O5, TiS2, and
`electrochemically synthesized LixFe2O3 (US 4464447 A; Journal of Power Sources, vol. 8, p.
`289, 1982), LiNixCo1-xO2 for the positive electrode active material and the negative electrode
`
`active material (0 (cid:3409)(cid:3)x < 1; JP H01-120765 A; the positive electrode active material and the
`
`negative electrode active material are mentioned as being the same compound in examples
`in the specification), LiCoO2 or LiMn2O4 and iron oxide, FeO, Fe2O3, Fe3O4, cobalt oxide, CoO,
`Co2O3 or Co3O4 (JP H03-291862 A).
`
`[0005]
`
`Among these examples, non-aqueous secondary batteries using a lithium-containing
`transition metal oxide as the negative electrode active material, which exhibits high safety,
`high discharge capacity, and a high battery voltage (3-V class), are promising, but these are
`impractical because of inferior cycle characteristics, so an improvement in cycle
`characteristics is strongly desired.
`
`[0006]
`
`[Problem to be Solved by the Invention]
`
`It is an object of the present invention to provide a non-aqueous secondary battery having a
`high battery voltage, high discharge capacity (high energy density), and long
`charge/discharge cycle life, and to provide a charge/discharge method for this non-aqueous
`secondary battery.
`
`[0007]
`
`[Means for Solving the Problem]
`
`This object is achieved when a non-aqueous secondary battery whose negative electrode
`active material is a lithium-containing transition metal oxide represented by LixMOj (where M
`represents at least one transition metal selected from Ti, V, Mn, Co, Fe, Ni, Nb, and Mo, x is
`in the range from 0.17 to 11.25, and j is in the range from 1.6 to 4.1), whose positive
`electrode active material is a lithium-containing transition metal oxide represented by LiyNOz
`(where N represents at least one transition metal selected from Co, Mn, Ni, V, and Fe, y is in
`the range from 0.2 to 1.2, and z is in the range from 1.4 to 3), and whose end-of-charge
`voltage is from 3.5 to 4.7 V is charged after the battery has been discharged to 0.5 to 1.5 V
`in the charge-discharge cycle.
`
`[0008]
`
`In the present invention, transition metals range from Sc with an element number of 21 to
`Zn with an element number of 30, from Y with an element number of 39 to Cd with an
`
`6
`
`

`

`JP H07-122298 A
`
`element number of 48, and from La with an element number of 57 to Hg with an element
`number of 80.
`
`[0009]
`
`The non-aqueous secondary battery of the present invention has a basic configuration
`comprising a positive electrode active material, a negative electrode active material, and a
`non-aqueous electrolyte containing a lithium salt. The negative electrode active material is a
`transition metal oxide that may contain lithium, or can be obtained by inserting lithium ions
`into the transition metal oxide, preferably by inserting lithium ions (by electrochemical
`intercalation) into a lithium-containing transition metal oxide.
`
`[0010]
`
`The transition metal oxide prior to lithium ion insertion (the “negative electrode active
`material precursor” below) used in the present invention preferably is synthesized by mixing
`two or more transition metal compounds together at the desired ratio or synthesized by
`mixing a lithium compound and one or more transition metal compounds together at a
`lithium compound/total transition metal compound molar ratio of 3.1 or less. However, the
`transition metal contains at least one of Ti, V, Mn, Co, Ni, Fe, Cr, Nb, and Mo. Preferably, the
`negative electrode active material precursor is synthesized by mixing a lithium compound
`and a transition metal compound together at a lithium compound/total transition metal
`compound molar ratio from 0.2 to 3.1. Here, the transition metal contains at least one of Ti,
`V, Mn, Co, Ni, and Fe.
`
`[0011]
`
`At least one of the transition metal oxides serving as the negative electrode active material
`precursor of the present invention is represented by LipMOj (where M represents at least one
`transition metal, the at least one transition metal is selected from Ti, V, Mn, Co, Ni, Fe, Cr,
`Nb, and Mo, p is in the range from 0 to 3.1, and j is in the range from 1.6 to 4.1).
`
`[0012]
`
`In addition, the negative electrode active material precursor is preferably LipM1q1 M2q2 ...
`MnqnOj (where each of M1 M2 ... Mn represents a transition metal, at least one of these
`represents Ti, V, Mn, Co, Ni, or Fe, p is in the range from 0 to 3.1, q1 + q2 + ... + qn = 1, n
`is in the range from 1 to 10, and j is in the range 1.6 to 4.1). In this formula, p is preferably
`in the range from 0.2 to 3.1, n is in the range from 1 to 4, and j is in the range from 1.8 to
`4.1. In this formula, p is more preferably in the range from 0.2 to 3.1, n is in the range
`from 1 to 3, and j is in the range from 1.8 to 4.1.
`
`[0013]
`
`As mentioned above, the negative electrode active material precursor of the present
`invention contains one or more stable transition metals (for example, V, Cr, Nb, and Mo)
`having a valence of 5+ to 6+, which is useful for obtaining a high discharge capacity.
`
`[0014]
`
`A negative electrode active material precursor containing V is preferably Lip M1q1 M2q2 ...
`MnqnXqvOj (where M is a transition metal, X is V, Cr, Nb, or Mo, p is in the range from 0 to
`3.1, q1 + q2 + ... + qn + qv = 1, n is in the range from 1 to 9, and j in the range from 1.3
`
`7
`
`

`

`JP H07-122298 A
`
`to 4.1). A negative electrode active material precursor containing at least V is especially
`preferred from the standpoint of obtaining a high discharge capacity. The negative electrode
`active material precursor containing V is more preferably Lip Mq1 Mq2V1-(q1+q2) Oj (where
`M is a transition metal, p is in the range from 0.2 to 3.1, q1 + q2 is in the range from 0 to
`0.7, and j is in the range from 1.3 to 4.1). The negative electrode active material precursor
`containing V is even more preferably LipCoq V1-qOj or LipNiq V1-qOj (where p is in the
`range from 0.3 to 2.2, q is in the range from 0.02 to 0.7, and j is in the range from 1.5 to
`2.5).
`
`[0015]
`
`LipCoVO4 and LipNiVO4 (where p is in the range from 0.3 to 2.2) is an especially preferable
`negative electrode active material precursor for use in the present invention. The p-value is
`the value before the start of charging/discharging, and increases or decreases with charging
`or discharging. The negative electrode active material also has an increased amount of
`lithium in the precursor composition formula. In a general formula (for example, LipMOj)
`shown in the present invention, the total number of transition metals M is 1. Therefore,
`there may be more than one transition metal and they may be multiplied by an integer in
`the crystallographic composition formula.
`
`[0016]
`
`Specific examples of the most preferred negative electrode active material precursors in the
`present invention are listed below, but the present invention is not limited to these
`compounds. These include LiVO3.1, LiTiO2.3, CoVO3.7, LiCoVO4, LiCo0.5V0.5O2.1, LiNiVO4.0,
`Li0.75Ni0.5V0.5O2.1, Li1.75Ni0.5V0.5O2.4, LiTi0.5V0.5O2.9, LiMn0.5V0.5O2.5, LiFe0.5Mn0.5O2.1,
`LiCo0.25V0.75O2.8, LiNi0.25V0.75O2.8, LiNi0.05V0.95O3.1, LiFe0.05V0.95O3.1, LiMn0.05V0.95O3.0,
`LiCa0.05V0.95O3.2, LiCo0.75V0.25O1.9, LiMn0.25Ti0.5V0.25O2.6, LiCr0.05V0.95O3.2, LiNb0.05V0.95O3.1,
`LiMo0.05V0.95O3.0, Li0.8Na0.2Co0.5V0.5O2.1, Li0.95Rb0.05Ni0.5V0.5O2.2, Li0.9K0.2Co0.5V0.5O2.2,
`Li0.85Ba0.15Ni0.5V0.5O2.2, Li0.9Co0.4A10.1V0.5O2.1, LiCo0.45Ga0.05V0.5O2.2, Li0.9Ni0.2In0.3V0.5O2.3,
`Li1.05Co0.4T10.1V0.5O2.3, Li1.03Ge0.5V0.5O2.3, Li0.98Co0.25Pb0.25V0.5O2.1, LiCo0.5Bi0.05V0.45O2.1,
`Li0.96Ni0.25Zr0.25V0.5O2.2, LiCo0.2Ni0.3Ag0.05V0.45O2.1, LiCo0.4Zr0.1V0.5O2.0, Li1.01Co0.4La0.1V0.5O2.1,
`LiNi0.2Cd0.3V0.5O2.1, LiCo0.25Ce0.25V0.5O2.2, Li1.03Co0.2Sm0.3V0.5O2.1, and
`Li0.85Na0.15Co0.4Ge0.2V0.4O2.1. The oxygen number is obtained from the weight of the
`compound before firing and the weight after firing. Therefore, an error of -10% to 10%
`from the resulting value for the oxygen number has to be factored in due to the accuracy of
`the measurement method.
`
`[0017]
`
`A negative electrode active material of the present invention is obtained by inserting lithium
`ions into the negative electrode active material precursor. Therefore, Lip in a transition
`metal oxide that may contain lithium in the precursor of the negative electrode active
`material becomes Lix. In other words, x is generally in the range from 0.17 to 11.25 (the
`increase in lithium x-p due to lithium ion insertion is generally in the range from 0.17 to
`8.15). For example, a negative electrode active material used in the present invention
`obtained by inserting lithium ions into LipMOj, which is the preferred negative electrode
`active material precursor, contains at least one lithium-containing transition metal oxide
`represented by LixMOj (where M represents at least one transition metal, the at least one
`transition metal is selected from Ti, V, Mn, Co, Fe, Ni, Nb, and Mo, p is in the range from 0
`to 3.1, x is in the range from 0.17 to 11.25, and j is in the range from 1.6 to 4.1). Here, x is
`preferably in the range from 0.26 to 10.2, and more preferably in the range from 0.34 to
`9.3. A preferred negative electrode active material is composed of at least one transition
`
`8
`
`

`

`JP H07-122298 A
`
`metal oxide represented by LixMqV1-qOj (where M represents a transition metal, p is in the
`range from 0 to 3.1, x is in the range from 0.17 to 8.15, q is in the range from 0 to 0.7, and
`j is in the range from 1.3 to 4.1). Here, x is preferably in the ranges set forth above.
`
`[0018]
`
`The negative electrode active material of the present invention is preferably obtained by
`inserting lithium ions into a negative electrode active material precursor of a transition
`metal oxide and/or a lithium-containing transition metal oxide. Preferred methods include
`conducting a reaction with lithium metal, a lithium alloy, or butyllithium, or
`electrochemically inserting lithium ions. In the present invention, electrochemically inserting
`lithium ions into the transition metal oxide serving as the negative electrode active material
`precursor is especially preferred. Using a lithium-containing transition metal oxide as the
`negative electrode active material precursor and electrochemically inserting lithium ions into
`this metal oxide is most preferred. Lithium ions can be electrochemically inserted by
`conducting a discharge in a redox system (such as an open system (electrolysis) or a closed
`system (battery)) using the desired lithium-containing transition metal oxide (the “negative
`electrode active material precursor” in the present invention) as the positive electrode
`active material, and a non-aqueous electrolyte containing lithium metal or a lithium salt as
`the negative electrode active material. Another preferred method is conducting charging in
`a redox system (such as an open system (electrolysis) or a closed system (battery)) using a
`lithium-containing transition metal oxide as the positive electrode active material, a
`negative electrode active material precursor with a composition formula different from that
`of the positive electrode active material as the negative electrode active material, and a
`non-aqueous electrolyte containing a lithium salt.
`
`[0019]
`
`There are no particular restrictions on the amount of lithium ions that can be inserted, but is
`preferably from 27 to 1340 mAh per gram of negative electrode active material precursor
`(corresponding to 1 to 50 mmol). From 40 to 1070 mAh (equivalent to 1.5 to 40 mmol) is
`more preferred. From 54 to 938 mAh (equivalent to 2 to 35 mmol) is even more preferred.
`There are no particular restrictions on the use ratio for the positive electrode active material
`and the negative electrode active material, but the ratio is preferably set so that the
`effective equivalents of each are equal (an effective equivalent is the equivalent that can
`substantially maintain cycle performance). At the time, either the positive electrode active
`material or the negative electrode active material is preferably increased.
`
`[0020]
`
`In the present invention, a lithium-containing transition metal oxide in which the basic
`crystal structure of the precursor has been changed is preferably used as the negative
`electrode active material, and the basic structure after the change preferably does not
`change further due to charging and discharging. In other words, the X-ray diffraction
`pattern of the negative electrode active material precursor of the present invention
`preferably changes due to the insertion of lithium ions, but then does not substantially
`change even after repeated charging and discharging.
`
`[0021]
`
`The positive electrode active material used in the present invention may be a transition
`metal oxide capable of reversibly occluding and releasing lithium ions, and is preferably a
`lithium-containing transition metal oxide. Preferred lithium-containing transition metal oxide
`
`9
`
`

`

`JP H07-122298 A
`
`positive electrode active materials include lithium-containing oxides that also contain Ti, V,
`Cr, Mn, Fe, Co, Ni, Cu, Mo and/or W. The positive electrode active material and the negative
`electrode active material preferably have different composition formulas.
`
`[0022]
`
`A lithium-containing transition metal oxide serving as the positive electrode active material
`of the present invention is preferably obtained by mixing a lithium compound and one or
`more transition metal compounds together at a lithium compound/total transition metal
`compound molar ratio from 0.3 to 2.2 (where the transition metal is at least one selected
`from Ti, V, Cr, Mn, Fe, Co, Ni, Mo, and W). The transition metal is preferably at least one
`selected from V, Cr, Mn, Fe, Co and Ni.
`
`[0023]
`
`The lithium-containing transition metal oxide serving as the positive electrode active
`material in the present invention is represented by LiyNOz (where M is a transition metal
`including at least one selected from Co, Mn, Ni, V, and Fe, y is in the range from 0.3 to 1.2,
`and z is in the range from 1.4 to 3).
`
`[0024]
`
`Preferred examples of lithium-containing metal oxide positive electrode active materials in
`the present invention include LiyCoO2, LiyNiO2, LiyCoaNi1-aO2, LiyCobV1-bOz, LiyCobFe1-
`bO2, LiyMn2O4, LiyMncCo2-cO4, LiyMncNi2-cO4, LiyMnc V2-cO4, and LiyMncFe2-cO4, as well as
`a mixture of LiyMn2O4 and MnO2, a mixture of Li2yMn2O3 and MnO2, and a mixture of
`LiyMn2O4, Li2yMn2O3 and MnO2 (where y is in the range from 0.5 to 1.2, a is in the range
`from 0.1 to 0.9, b is in the range from 0.8 to 0.98, c is in the range from 1.6 to 1.96, and
`Oz is in the range from 2.01 to 5).
`
`[0025]
`
`More preferred examples of lithium-containing metal oxide positive electrode active
`materials in the present invention include LiyCoO2, LiyNiO2, LiyCoaNi1-aO2, LiyCob V1-bOz,
`LiyCobFe1-bO2, LiyMn2O4, LiyMncCo2-cO4, LiyMncNi2-cO4, LiyMnc V2-cO4, and LiyMncFe2-cO4
`(where y is in the range from 0.7 to 1.04, a is in the range from 0.1 to 0.9, b is in the range
`from 0.8 to 0.98, c is in the range from 1.6 to 1.96, and z is in the range from 2.01 to 2.3).
`
`[0026]
`
`Even more preferred examples of lithium-containing metal oxides in the present invention
`include LiyCoO2, LiyNiO2, LiyCoaNi1-aO2, LiyMn2O4, and LiyCob V1-bOz (where y is in the
`range from 0.7 to 1.1, a is in the range from 0.1 to 0.9, b is in the range from 0.9 to 0.98,
`and z is in the range from 2.01 to 2.3). Preferably, y is in the range from 0.7 to 1.04, a is in
`the range from 0.1 to 0.9, b is in the range from 0.9 to 0.98, and z is in the range from
`2.02 to 2.3. Here, the y value is the value before the start of charging and discharging, and
`increases or decreases due to charging or discharging.
`
`[0027]
`
`Examples of especially preferred compounds for use in the present invention are listed
`below, but the present invention is not limited to these. These include LiCoO2, LiNiO2,
`LiCo0.5Ni0.5O2, LiCo0.95 V0.05O2.05, LiMnO2, and LiMn2O4. The oxide in the positive electrode
`
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`JP H07-122298 A
`
`active material used in the present invention may be crystalline or amorphous, but
`crystalline compounds are preferred.
`
`[0028]
`
`In the present invention, "the positive electrode active material and the negative electrode
`active material have different composition formulas" means (1) different combinations of
`metal elements or (2) the values for y and x, b and q, and z and j are not equal at the same
`time in examples of positive electrode active material such as LiyCobV1-bOz and in
`examples of negative electrode active materials such as LixCoqV1-qOj. It especially means
`that b and q and that z and j are not equal at the same time. The positive electrode active
`material and the negative electrode active material used in the present invention are
`preferably combinations of compounds with different standard oxidation-reduction
`potentials.
`
`[0029]
`
`The positive electrode active material in the present invention can be synthesized by
`chemically inserting lithium ions into a transition metal oxide, electrochemically inserting
`lithium ions into a transition metal oxide, or mixing a lithium compound and a transition
`metal compound together and firing the mixture.
`
`[0030]
`
`When synthesizing a positive electrode active material in the present invention, the method
`of inserting lithium ions into the transition metal oxide is preferably synthesizing a
`compound by reacting lithium metal, a lithium alloy, or butyllithium with a transition metal
`oxide. More preferably, the positive electrode active material used in the present invention is
`synthesized by mixing a lithium compound and a transition metal compound and then firing
`the mixture.
`
`[0031]
`
`The firing temperature for a negative electrode active material or its precursor used in the
`present invention may be a temperature at which some of the mixed compounds used in the
`present invention decompose and melt, and is preferably from 250 to 2,000°C, and more
`preferably from 300 to 1,500°C. Alternatively, it may be synthesized using a pattern in
`which the temperature is increased or decreased in two or more stages. There are no
`particular restrictions on the gas atmosphere for firing used in the present invention, but the
`positive electrode active material is preferably fired in the air or in a gas containing a large
`amount of oxygen (for example, 30% or more). The negative electrode active material or its
`precursor is preferably fired in air, in a gas with a low oxygen content (for example, 10% or
`less), in a gas with a high oxygen content (for example, 30% or more), or in an inert gas
`(such as nitrogen gas or argon gas). The negative electrode active material or its precursor
`used in the present invention may be synthesized by mixing starting materials together at
`the same time and then firing the mixture, or by mixing the components together and firing
`the mixtures in two or more stages. For example, when synthesizing LiCoVO4 to serve as
`the negative electrode active material precursor, the material may be obtained by mixing
`together the raw material Li compound, Co compound, and V compound and then firing the
`mixture in one stage, followed by synthesizing Co2V207 from the Co compound and the V
`compound by firing, and mixing in the Li compound before firing the mixture again.
`
`[0032]
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`JP H07-122298 A
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`The ratio of the positive electrode active material to the negative electrode active material
`in a non-aqueous secondary battery of the present invention depends on the types of active
`materials to be combined.
`
`[0033]
`
`A non-aqueous secondary battery of the present invention is discharged to a battery voltage
`of 0.5 to 1.5 V during the charge/discharge cycle, and the following two methods can be
`used.
`
`(1) The end-of-discharge voltage range to be used is set to 1.5 V or more and 3.0 V or less,
`and the battery is discharged to 0.5 to 1.5 V before charging, followed by the discharge in
`the next cycle. In this case, the battery may be discharged to this voltage during each
`charge/discharge cycle, or discharged to 0.5 to 1.5 V after repeating the cycle several
`times. In the latter case, the battery is preferably discharged to 0.5 to 1.5 V once about
`every 20 cycles, taking into account the decrease in battery capacity as cycles are repeated.
`
`(2) The range of end-of-discharge voltage to be used is set to 0.5 V or more and 1.5 V or
`less. For a discharge from 0.5 to 1.5 V, a discharge from 0.7 to 1.5 V is preferred, and a
`discharge from 0.8 to 1.4 V is more preferred. If the end-of-discharge voltage is lower than
`0.5 V, the current collector may dissolve, and if it is higher than 1.5 V, the cycle
`characteristics may deteriorate.
`
`[0034]
`
`The end-of-charge voltage is preferably in the range from 3.5 to 4.7 V, more preferably from
`3.7 to 4.5 V, and even more preferably from 3.8 to 4.4 V to realize a 3-V class battery
`voltage. If it is lower than 3.5 V, the battery voltage will be low, and if it is higher than 4.7
`V, the positive electrode active material and the electrolyte may decompose.
`
`[0035]
`
`The negative electrode active material or its precursor and the positive electrode active
`material in the present invention are preferably synthesized by firing a mixture of a lithium
`compound and a transition metal compound listed below. Lithium compounds include
`oxygen compounds, oxysalts and halides. The transition metal compound can be a
`monovalent to hexavalent transition metal oxide, transition metal salt, or transition metal
`complex salt.
`
`[0036]
`
`Lithium compounds that can be used in the present invention include lithium oxide, lithium
`hydroxide, lithium carbonate, lithium nitrate, lithium sulfate, lithium sulfite, lithium
`phosphate, lithium tetraborate, lithium chlorate, lithium perchlorate, lithium thiocyanate,
`lithium formate, lithium acetate, Lithium oxalate, lithium citrate, lithium lactate, lithium
`tartrate, lithium pyruvate, lithium trifluoromethanesulfonate, lithium tetraborate, lithium
`hexafluorophosphate, lithium fluoride, lithium chloride, lithium bromide, and lithium iodide.
`
`[0037]
`
`Preferred examples of transition metal compounds that can be used in the present invention
`include TiO2, lithium titanate, acetylacetonatotitanyl, titanium tetrachloride, titanium
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`JP H07-122298 A
`
`tetraiodide, ammonium titanyl oxalate, VOd (compounds with d = 2 to 2.5; d = 2.5 is
`vanadium pentoxide), VOd lithium compounds, vanadium hydroxide ammonium
`metavanadate, ammonium orthovanadate, ammonium pyrovanadate, vanadium oxosulfate,
`vanadium oxytrichloride, vanadium tetrachloride, lithium chromate, ammonium chromate,
`cobalt chromate, chromium acetylacetonate, MnO2, Mn2O3, manganese hydroxide,
`manganese carbonate, manganese nitrate, manganese sulfate, manganese ammonium
`sulfate, manganese sulfite, manganese phosphate, manganese borate, manganese chlorate,
`manganese perchlorate, manganese thiocyanate, manganese formate, manganese acetate,
`manganese oxalate, manganese citrate, manganese lactate, manganese tartrate,
`manganese stearate, manganese fluoride, chloride manganese, manganese bromide,
`manganese iodide, manganese acetylacetonate, iron oxide (divalent, trivalent), iron oxide
`tetraoxide, iron hydroxide (divalent, trival