0
`
`UNITED STATES DEPARTMENT OF COMMERCE
`United States Patent and Trademark Office
`
`November 25, 2014
`
`THIS IS TO CERTIFY THATANNEXED IS A TRUE COPY FROM THE
`RECORDS OF THIS OFFICE OF THE FILE WRAPPER AND CONTENTS
`OF:
`
`.
`
`APPLICATION NUMBER: 09/887,842
`FILING DATE: June 21, 2001
`PATENT NUMBER: 6,677,082
`ISSUE DATE: January 13,2004
`
`By Authority of the
`Under Secretary of Commerce for Intellectual Property
`and Director of the United States Patent and Trademark '-'U'."'"'
`
`JOHN A BURSON
`Certifying Officer
`
`SONY EXHIBIT 1004
`
`Page 1 of 493
`
`

`
`(M= e.g., Mn, Ni)
`
`(M'= e.g., Mn, Ti, Zr)
`
`•
`
`•
`
`LiM02
`
`electrochemical
`Path of initial
`
`./ ,.,_,;,.,.;..,..,.; __
`
`~~II&IIICI&I~II
`
`xli2M'03•(1-x)LiM02
`
`/
`
`\
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`' \
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`' \
`' \
`
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`Li2M'03
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`\ y Li \
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`'
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`xli2M'03•(1-x-y)LiMOf\
`M02
`
`Figure 1
`
`m
`
`Page 2 of 493
`
`Page 2 of 493
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`

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`Page 3 of 493
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`Page 3 of 493
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`Page 4 of 493
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`Page 4 of 493
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`Page 5 of 493
`
`Page 5 of 493
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`

`
`•
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`•
`
`100
`
`80
`
`60
`
`40
`
`20
`
`0
`
`Time {h)
`
`~-----------------------'
`
`-4.5 to2.0 V; 0.1 mA/an2; 1:1
`
`DEC:EC, 1 MLiPF6,@ RT
`
`136
`
`136
`
`137
`
`139
`
`141 mJ\h/g
`
`4.5
`
`5
`
`Figure 5
`
`0
`
`0.5
`
`1
`
`2
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`3
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`Page 6 of 493
`
`Page 6 of 493
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`30
`
`25
`
`20
`
`Time(h)
`15
`
`10
`
`5
`
`0
`
`0 ~----~------~------~----~------~------~~
`
`0.5 --------------------------------------------------------------------------------------------
`
`I-----------------------
`
`DEC:EC/ 1 MLiPF6/@ RT
`
`l ~----------------------------'
`
`U 1.5 r----------------------------1-4.5 to 2.0 V; 0.1 rnt\/an2; 1:1 ·-------------------------
`(])
`
`2 ------------------------------------------------------~--------------------------------------
`
`3
`
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`(])
`
`>
`0 2.5
`E
`
`4.5 ----------------------------------~---------------------------------------~-----------------
`
`5 ~--------------------------------------------~
`
`c, 3.5
`4
`
`Figure 6
`
`1!~
`
`Page 7 of 493
`
`Page 7 of 493
`
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`Page 8 of 493
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`Page 8 of 493
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`Page 9 of 493
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`Page 9 of 493
`
`

`
`•
`
`18
`
`•
`
`ABSTRACT OF THE INVENTION
`
`A lithium metal oxide positive electrode for a non-aqueous lithium cell is disclosed.
`
`The cell is prepared in its initial discharged state and has a general formula xliM02•(1-
`
`x)Li2M'03 in which O<x<1, and where M is one or more trivalent ion with at least one ion
`
`being Mn or Ni, and where M' is one or more tetravalent ion with at least one ion.
`
`Complete cells or batteries are disclosed with anode, cathode and electrolyte as are
`
`batteries of several cells connected in parallel or series or both.
`
`Page 10 of 493
`
`Page 10 of 493
`
`

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`-C -1 n
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`-~~c:
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`
`. 'OAUL L. BROWN
`~ (t..MES J. HILL
`HARRY M. LEVY
`ROBERT R. CALIRI
`THOMAS E. HILL
`JONATHAN J. KRIT
`
`'
`
`. ()(J' -~)-j- 0 }
`
`.EMRICH & DITHMAR.
`ATTORNEYS AND COUNSELORS
`
`SUITE3000
`
`300 SOUTH WACKER DRIVE
`
`CHICAGO, ILLINOIS 60606, USA
`
`TEL: 312-663-9800
`
`FAX: 312-663-9822
`
`June 21, 2001
`
`PATENTS, TRADEMARKS, COPYRIGHTS
`UNFAIR COMPETITION LAW
`AND RELATED LITIGATION 0 ~
`f-<
`--..-;
`A. =(cid:173)
`~:;;::::::::
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`:::::::::
`
`VIA EXPRESS MAIL NO. EL 846752635 US
`
`CERTIFICATE OF EXPRESS MAILING
`
`Assistant Commissioner for Patents
`Washington, D.C. 20231
`
`Attn: BOX NEW PATENT APPLICATION
`
`Re:
`
`Argonne National Laboratory/
`The University of Chicago
`Case No. 203
`Patent Application For:
`LITHIUM METAL-OXIDE ELECTRODES
`FOR LITHIUM CELLS AND BATTERIES
`Inventors: Michael M. Thackeray. et al.
`
`Sir:
`
`.•
`
`{f£
`
`Transmitted for filing herewith i:s the above-identified patent application including specification,
`eight (8) sheets of drawings; Declaration, Power of Attorney, Correspondence Address, Information
`Disclosure Statement and PTO FORM 1449.
`
`Applicant qualifies for small enHty status.
`
`Our check in the amount of$ 529.00 to cover the filing fee is enclosed, which fee was
`calculated as follows:
`
`For
`
`Total Claims
`
`Independent Claims
`
`Numb,er
`Filed
`
`Number
`Extra
`
`26
`
`7
`
`6
`
`4
`
`X
`
`X
`
`Total Filing Fee
`
`Rate
`
`$ 9
`
`$40
`
`(small entity)
`$355.00
`
`54.00
`
`120.00
`
`$529.00
`
`Please charge any additional fees or credit any overpayments incident to the filing of this
`patent application to Deposit Account No. 05-1060 A duplicate copy of this letter is enclosed.
`
`HML/bbs
`encls.
`
`Page 11 of 493
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`Page 11 of 493
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`

`
`•
`
`•
`
`ANL-IN-00-063
`
`IN THE UNITED STATES
`
`PATEN1r AND TRADEMARK OFFICE
`
`APPLICATION FOR U.S. LETTER PATENT CLAIMING
`THE BENEFIT UNDER TITLE 35, UNITED STATES
`CODE, §119(e) of U.S. PROVISIONAL APPLICATION
`SERIAL NO. 60/213,618, FILED June 22, 2000
`
`Title: LITHIUM METAL OXIDE ELECTRODES FOR LITHIUM
`CELLS AND BATTERIES
`
`lnventor(s): Michael M. Thackeray, Christopher S.
`Johnson, Khalil Amine and Jaekook Kim
`
`CERTIFICATE OF MAILING BY EXPRESS MAIL
`
`Express Mail Label Number t;: L "514? 7 5" ~ 3s-US
`
`ignature)
`
`!c.
`~!::;t 0/
`(Date OJ:Ieposit) 1
`
`Page 12 of 493
`
`Page 12 of 493
`
`

`
`•
`
`•
`
`CONTRACTUAL ORIGIN OF THE INVENTION
`
`The United States Government has rights in this invention pursuant to Contract
`
`No. W-31-109-ENG-38 between the U.S. Department of Energy (DOE) and The
`
`University of Chicago representing Argonne National Laboratory.
`
`RE:LATED APPLICATIONS
`
`This application claims priority under 35 U.S.C. § 1.78(a)(3) provisional
`
`application Serial No. 60/213,618 filed June 22, 2000, the entire contents of which are
`
`incorporated herein by reference.
`
`BACKGROUND OF THE INVENTION
`
`10
`
`This invention relates to lithium metal oxide positive electrodes for non-aqueous
`
`lithium cells and batteries. More specifically, it relates to lithium-metal-oxide electrode
`
`compositions and structures, having in their initial state in an electrochemical cell, a
`
`general formula xliM02•(1-x)Li2M'03 alternatively Li2_xMxM' 1_x0 3_x in which O<x<1 and
`
`where M is one or more trivalent ion with at least one ion being Mn, and where M is one
`
`or more tetravalent ions selected preferably from Mn, Ti and Zr; or, where M is one or
`
`more trivalent ion with at least one ion being Ni, and where M' is one or more
`
`tetravalent ion with at least one ion being Mn. In one embodiment of the invention, the
`
`Mn content should be as high as possible, such that the LiM02 component is essentially
`
`LiMn02 modified in accordance with this invention. In a further embodiment of the
`
`20
`
`invention, the transition metal ions and lithium ions may be partially replaced by minor
`
`Page 13 of 493
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`Page 13 of 493
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`

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`•
`
`2
`
`•
`
`concentrations of one or more mono- or multivalent cations such as H+ derived from the
`
`electrolyte by ion-exchange with u+ ions, and/or Mg2+ and A13+ to impart improved
`
`structural stability or electronic conductivity to the electrode during electrochemical
`
`cycling.
`
`SUMMARY OF THE INVENTION
`
`Lithium-metal oxide compounds of general formula LiM02 , where M is a trivalent
`
`transition metal cation Co, Ni, Mn, Ti, V, Fe, and with electrochemically inactive
`
`substituents such as AI are very well known and are of interest as positive electrodes for
`
`rechargeable lithium batteries. The best-known electrode material is LiCo02 , which has
`
`10 a layered-type structure and is n~latively expensive compared to the isostructural nickel
`
`and manganese-based compounds. Efforts are therefore being made to develop less
`
`costly electrodes, for example, by partially substituting the cobalt ions within LiCo02 by
`
`nickel, such as in LiNi0.8Co0_20 2 or by exploiting the manganese-based system LiMn02 .
`
`Such layered compounds are sometimes stabilized by partially replacing the transition
`
`metal cations within the layers by other metal cations, either alone or in combination. For
`
`example, Mg2
`
`+ ions may be introduced into the structure to improve the electronic
`
`conductivity of the electrode, or Al3+ or Ti4
`
`+ ions to improve the structural stability of the
`
`electrode at high
`
`levels of delithiation. Examples of such compounds are
`
`20
`
`A major problem of layere!d LiM02 compounds containing either Co or Ni (or both)
`
`is that the trivalent transition metal cations, M, are oxidized during charge of the cells to a
`
`metastable tetravalent oxidation state. Such compounds are highly oxidizing materials and
`
`can react with the electrolyte or rE~Iease oxygen. These electrode materials can, therefore,
`
`Page 14 of 493
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`Page 14 of 493
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`

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`•
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`3
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`•
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`suffer from structural instability in charged cells when, for example, more than 50% of the
`
`lithium is extracted from their structures; they require stabilization to combat such chemical
`
`degradation.
`
`Although the layered manganese compound LiMn02 has been successfully
`
`synthesized in the laboratory, it has been found that delithiation of the structure and
`
`subsequent cycling of the LixMn02 electrode in electrochemical cells causes a transition
`
`from the layered Mn02 configuration to the configuration of a spinel-type [Mn2]04 structure.
`
`This transformation changes the voltage profile of the Li/LixMn02 cell such that it delivers
`
`capacity over both a 4V and a 3V plateau; cycling over the 3V plateau is not fully
`
`10 reversible which leads to capacity fade of the cell over long-term cycling. Other types of
`
`LiMn02 structures exist, such as the orthorhombic-form, designated O-LiMn02 in which
`
`sheets of Mn06 octahedra are staggered in zig-zig fashion unlike their arrangement in
`
`layered LiMn02 . However, O-LiMin02 behaves in a similar way to layered LiMn02 in lithium
`
`cells; it also converts to a spinel-like structure on electrochemical cycling.
`
`Therefore, further improv13ments must be made to LiM02 electrodes, particularly
`
`LiMn02 ,
`
`to impart greater structural stability to these electrode materials during
`
`electrochemical cycling in lithium cells and batteries. This invention addresses the stability
`
`ofliM02 electrode structures, particularly LiMn02, and makes use of a Li2M'03 component
`
`to improve their stability.
`
`20
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The invention consists of certain novel features and a combination of parts
`
`hereinafter fully described, illustrated in the accompanying drawings, and particularly
`
`pointed out in the appended claims, it being understood that various changes in the details
`
`Page 15 of 493
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`Page 15 of 493
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`•
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`4
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`•
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`may be made without departing from the spirit, or sacrificing any of the advantages of the
`
`present invention.
`
`FIGURE 1 depicts a schematic representation of a Li2M'03-M02-LiM02 phase
`
`diagram, in which M is a trivalent ion (or ions) and M is a tetravalent ion (or ions);
`
`FIGURE 2 depicts the X-ray diffraction pattern of a xli2Mn03•(1-x)LiNi0_8Co0_20 2
`
`electrode composition;
`
`FIGURE 3 depicts the X-ray diffraction pattern of a xli2Mn 1_x Tix03•( 1-x)LiNi0_8Co0_20 2
`
`electrode composition;
`
`FIGURE 4 depicts the X-ray diffraction pattern of a xli2Ti03•(1-x)LiMn02 electrode
`
`10 composition;
`w
`
`FIGURE 5 depicts the electrochemical profile of a Li/xli2Mn03•(1-x)LiNi0_8Co0_20 2
`
`electrochemical cell;
`
`FIGURE 6 depicts the electrochemical profile of a Li/xli2Ti03•(1-x)LiMn02
`
`electrochemical cell;
`
`FIGURE 7 depicts a schematic representation of an electrochemical cell; and
`
`FIGURE 8 depicts a schematic representation of a battery consisting of a plurality
`
`of cells connected electrically in series and in parallel.
`
`DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
`
`This invention relates to stabilized LiM02 electrodes whereby an electrochemically
`
`2 o inert rocksalt phase Li2M03 is introduced as a component to the overall electrode structure
`
`as defined, in its initial state, by the general formula xliM02•(1-x)Li2M'03 alternatively Li2_
`
`xMxM' 1_x03_x in which O<x<1, preferably 0.8:;;:x<1, and more preferably 0.9:;;:x<1, and where
`
`Page 16 of 493
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`Page 16 of 493
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`•
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`5
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`•
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`M is one or more trivalent ions having at least one ion selected from Mn and where
`
`M' is one or more tetravalent ion selected preferably from Mn, Ti and Zr, or alternatively,
`
`where M is one or more trivalent ions having at least one ion selected from Ni and where
`
`M' one or more tetravalent ions having at least one ion selected from Mn. These
`
`compounds can be visualized as lying on the LiM02 - Li2M'03 tie-line of the Li2M'03-M02
`
`-
`
`LiM02 phase diagram shown schematically in Fig. 1.
`
`The rocksalt phase Li2Mn03 has a layered-type structure in which discrete layers
`
`of lithium ions alternate with layers containing Mn and Li ions (in a 2:1 ratio) between the
`
`close-packed oxygen sheets. Note that, in this respect, the formula Li2Mn03 can be written
`
`10
`
`in layered notation as Li(Mn2,3L:i 113)02, in which the Li and Mn within round brackets
`
`represent the ions in one layer. A difference between Li2Mn03 and the layered LiM0 2
`
`compounds is that the Mn ions in Li2Mn03 are tetravalent and cannot be easily
`
`electrochemically oxidized by lithium extraction, whereas in the LiM02 compounds the
`
`transition metal cations Mare trivalent and can be electrochemically oxidized. Because
`
`Li2Mn03 has a rocksalt phase, there is no energetically favorable interstitial space for
`
`additional lithium; therefore, Li2Mn03 cannot operate as an insertion electrode and cannot
`
`be electrochemically reduced. The xliM02•(1-x)Li2M'03 structure can be regarded
`
`essentially as a compound with a common oxygen array for both the LiM02 and Li2Mn03
`
`components, but in which the cation distribution can vary such that domains of the two
`
`2 o components exist side by side. Such a domain structure does not rule out the possibility
`
`of cation mixing and structural disorder, particularly at domain or grain boundaries. In a
`
`generalized xliM02•(1-x)Li2M'0~1 layered structure, one layer contains M, M' and Li ions
`
`between sheets of close-packed oxygen ions, whereas the alternate layers are occupied
`
`Page 17 of 493
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`Page 17 of 493
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`

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`•
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`6
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`•
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`essentially by lithium ions alone. By analogy, in a xliM02•(1-x)Li2M'03 structure that
`
`contains monoclinic LiMn02 as the LiM02 component, it is believed that the tetravalent M'
`
`ions can partially occupy the M positions in the monoclinic layered LiMn02 structure,
`
`thereby providing increased stability to the overall structure.
`
`Thus in the electrodes of the present invention, theM and M' ions can be disordered
`
`in the electrode structure.
`
`It is preferable that the Mn content should be as high as
`
`possible, such that the LiM02 component is essentially LiMn02 • In a further embodiment
`
`of the invention, the transition metal ions and lithium ions may be partially replaced by
`
`minor concentrations (typically less than 1 0 atom percent) of other mono- or multivalent
`
`~~ho cations such as Al 3
`
`+ or Mg2
`
`+ to impart improved structural stability or electronic conductivity
`
`to the electrode during electrochemical cycling.
`
`In addition, the xliM02·{1-x)Li2M'03
`
`structures of the invention may include H+ ions, for example, resulting from the removal
`
`acidic H+ species from the electrolyte by ion-exchange with u+ ions. It stands to reason,
`
`therefore, and the present invention includes where to put that because of the introduction
`
`of mono- or divalent cations into the structure, the electrodes of the invention may depart
`
`slightly from the ideal stoichiometry as defined by the formula xliM02•(1-x)Li2M'03.
`
`It has been shown in the past that Li2Mn03 (and isostructural Li2Mn 1_xZrx0 3) which
`
`is electrochemically inactive, can be used as a precursor material to form an
`
`electrochemically active charged xMn02•(1-x)Li2Mn03 electrode structure in which xis
`
`20 approximately equal to 0.91; this value of x translates to a composition of the layered
`
`structure LiuMn0.90 2. These charged xMn02•{1-x)Li2Mn03 compounds have been
`
`prepared by leaching Li20 from the Li2Mn03 (Li20·Mn02) structure with acid such as
`
`sulphuric acid (U.S. patent no. 5,153,081 ). However, the acid treatment causes a shear
`
`Page 18 of 493
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`Page 18 of 493
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`•
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`•
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`7
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`of the oxygen array, such thatthe resulting xMn02•{1-x)Li2Mn03 structures are no longer
`
`close-packed but have an oxy~1en arrangement that provides octahedral and trigonal
`
`prismatic sites in alternate layers. During relithiation, for example with Lil in acetonitrile,
`
`it has been demonstrated that the oxygen sheets shear back to close-packing and that the
`
`phase transformation yields a xliMn02•(1-x)Li2Mn03-type structure. However, such phase
`
`transformations are undesirable~ in rechargeable battery systems, because they can
`
`adversely affect the efficiency and rechargeability of the electrode. Thus, a major
`
`advantage of this invention is that this phase transformation can be avoided by starting
`
`0
`
`directly with a discharged xUMn02•(1-x)Li2Mn03 electrode in the cell because the non(cid:173)
`
`t.iJ 10 aqueous removal of lithium does not appear to cause the phase transition to yield the
`
`structure generated by acid leaching of Li2Mn03 (non close-packed).
`
`Furthermore, it is important to note that even though the relithiation of a xMn02•(1-
`
`x)Li2Mn03 electrode of the prior art in an electrochemical cell yields the same formulation
`
`as the electrodes of the present invention, i.e., xliMn02•{1-x)Li2Mn03, the applicants
`
`believe that the structures of the electrode materials of the present invention are
`
`significantly different from those of the prior art and will be unequivocally distinguished from
`
`one another by high-resolution transmission electron microscopy, i.e., differences will be
`
`evident in the microstructural fE3atures of the xliMn02•{1-x)Li2Mn03 electrodes of the
`
`present invention and those of the prior art. For example, because the lithiated
`
`20 xliMn02•(1-x)Li2Mn03 electrode structures of the prior art are derived from a non-close(cid:173)
`
`packed xMn02•(1-x)Li2Mn03 structure, which is obtained by the acid leaching of, and Li20
`
`removal from, a Li2Mn03 precursor as described above, the microstructures of the prior art
`
`electrode materials will be characterized by high concentrations of defects and stacking
`
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`faults, as is evident by the broad peaks in their X-ray diffraction patterns, in contrast to the
`
`electrode materials of the present invention that are more crystalline and ordered as
`
`reflected by the relatively sharp and well-resolved peaks in their X-ray diffraction patterns
`
`(Figs. 2,3 and 4 ).
`
`Another disadvantage of the acid-treated compounds of the prior art ('081 patent)
`
`xMn02•{1-x)Li2Mn03 , is that they represent charged positive electrodes, whereas lithium(cid:173)
`
`ion batteries require positive electrodes in the discharged state, for example, LiM02
`
`electrodes (M=Co, Ni, Mn). Moreover, the charged xMn02•1-x)Li2Mn03 electrodes of the
`
`prior art require dehydration before use so that they can be used effectively in lithium cells.
`
`By contrast, the xliMn02•(1-x)Li2Mn03 electrodes of this invention are prepared in the
`
`discharged state and are essentially anhydrous materials and are more stable to heat(cid:173)
`
`treatment and long-term storage in air compared to the xMn02•(1-x)Li2Mn03 materials of
`
`the prior art, which are known to transform on storage to a gamma-Mn02-type structure as
`
`reported by Johnson et al in J. PowerSource 81-82, 491 (1999).
`
`In one embodiment, this invention extends to include xliM02•(1-x)Li2M'03
`
`electrodes stabilized by isostructural rocksalt Li2M' 3 compounds other than M'= Mn, Ti, Zr
`
`as described in the preceding sections. Examples of such compounds are Li2Ru03 ,
`
`Li2Re03, Li21r03 , and Li2Pt03 which may contribute a portion of the electrochemical
`
`capacity of the electrode.
`
`20
`
`One of the difficulties that has been encountered in synthesizing xliM02•(1-
`
`x)Li2M'03 electrodes, in which M is Mn, has been to keep the valency of the manganese
`
`ions equal, or close to its trivalent state. This has been successfully accomplished by the
`
`inventors with a hydrothermal method or process under basic conditions using LiOH and/or
`
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`9
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`KOH. This invention, therefore, extends to include a hydrothermal process or method for
`
`synthesizing xliM02•(1-x)Li2M'03 compounds in which M is one or more trivalent ion with
`
`at least one ion being Mn, and in which M'is a tetravalent ion. Such methods of synthesis
`
`are undertaken in a pressurized autoclave, preferably between 5 and 35 atmospheres and
`
`at temperatures ranging between 100 and 250°C and most preferably at 10-20 atm and
`
`temperatures between 180 and 230°C for about 6 to 12 hours or more if necessary. For
`
`example, 0.15LiMn02•85Li2 Ti03 electrodes have been successfully prepared by this
`
`process from precursor materials consisting of manganese oxide (Mn20 3),
`
`lithium
`
`~li
`
`hydroxide (LiOH•H 20) and titanium isopropoxide (Ti[OCH(CH3) 2] 4)
`
`in a potassium
`
`10 hydroxide (KOH) solution at 220°C and at 15 atmospheres pressure.
`
`It has been recently demonstrated that layered lithium-chromium-manganese-oxide
`
`and lithium-cobalt-manganese-oxide electrodes of general formula xliCr02•( 1-x)Li2Mn03
`
`and xliCo0 2•(1-x)Li2Mn03 provide electrochemical stability when cycled between 4.5 and
`
`2.0 V in electrochemical lithium cells.
`In particular, a Li(Cr0.4Mn0.4Li0_2)02 electrode
`(alternatively, 0.4LiCr02•0.4Li2Mn03) delivers approximately 150 mAh/g at 25 oc and 200
`mAh/g at 55 oc at an average cell voltage of 3.5 V vs. Li. However, because the Li2Mn03
`
`component is electrochemically inactive, the electrochemical capacity derived from the cell
`
`is due to the oxidation of Cr+ to erG+ during the electrochemical charging of the cells. This
`
`system has an immediate disadvantage because it is known that the high oxidation states
`
`20 of chromium such as those found in Cr30 8 are dangerous and are a major health hazard
`
`whereas the electrodes of the present invention operate predominantly off a M3+/M4+
`
`couple, notably a Mn3+/4+ coupiEL For the cobalt compound, xliCo02•(1-x)Li2Mn03, no
`
`significant advantage is gained in overcoming the cost limitations ofthe electrode because
`
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`the cobalt ions, not the manganese ions, provide all the electrochemical capacity of the
`
`electrode.
`
`The following examples of stabilized xliMn02•(1-x)Li2Mn03 electrodes containing
`
`either manganese and/or nickel describe the principles of the invention as contemplated
`
`by the inventors, but they are not to be construed as limiting examples.
`
`EXAMPLE 1
`
`The material 0.2Li2Mn03•0.8LiNi0_8Co0_20 2 that can be written, alternatively, as
`
`LiOH in the required stoichiometric amounts at 800°C in air or oxygen for about 16 hours.
`
`~J 10 The powder X-ray diffraction pattern of this compound indicates an essentially single-
`
`~j
`
`phase product with a layered-type structure (Fig. 2).
`
`EXAMPLE 2
`
`alternatively, as Li(Ni0.58Mn0.09 Ti0.09Co0.15Li0_09)02 was prepared by the reaction of Ni(N03) 2,
`
`Co(N03) 2 , Mn02, Ti02 (anatase) and LiOH in the required stoichiometric amounts at 800°C
`
`in air or oxygen for about 16 hours. The powder X-ray diffraction pattern of this compound
`
`indicates an essentially single-phase product with a layered-type structure (Fig. 3).
`
`EXAMPLE 3
`
`The material 0.15Li2Ti03•0.85LiMn02 that can be written, alternatively, as
`
`20 Li(Ti0_14Mn0_79Li0_07)02 was prepaned by the hydrothermal reaction ofMn20 3, Ti02 (anatase)
`
`and LiOH in the required stoichiometric amounts at 220oc and 15 atmospheres pressure
`
`for about 10 hours. The powder X-ray diffraction pattern of this compound indicates an
`
`essentially single-phase produc1t with a layered-type structure (Fig. 4 ).
`
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`EXAMPLE 4
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`•
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`11
`
`The xliM02•(1-x)Li2M'03 electrode materials were evaluated in coin cells (size
`
`2032) 20 mm diameter and 3.2 mm high against a counter lithium electrode. The cells had
`
`the configuration: Li/1 M LiPF6 in ethylene carbonate (EC), diethyl carbonate (DEC)
`
`(1 :1 )electrolyte/xliM02•(1-x)Li2M'03, in which thexliM02•(1-x)Li2M'03 electrode consisted
`
`of 0.2Li2Mn03·0.8LiNi0.8Co0.20 2 or 0.15Li2 Ti03·0.85LiMn02• Other electrolytes well known
`
`in the art may be used. Laminated electrodes were made containing approximately 7 to
`
`10 mg of the xliM02•(1-x)Li2M'03 powder, i.e., approximately 82% by weight of the
`
`laminate electrode, intimately mixed with approximately 10% by weight of a polyvinylidene
`
`10 difluoride (Kynar PVDF polymer binder) and approximately 8% by weight of a suitable
`
`carbon (i.e. graphite, such as Timcal SFG-6, or acetylene black, such as Chevron XC-72)
`
`in 1-methyl-2-pyrrolidinone (NMP). Other binders are well known in the art and may be
`
`substituted here. The slurries were coated with a doctor blade onto an aluminum foil
`
`substrate current collector. The coatings were dried in vacuum at temperatures from 70°C
`
`for about 12 hours, and punched out as electrode laminates. Metallic lithium foil was used
`
`as the counter electrode. Li/xliiM02•(1-x)Li2M'03 cells were discharged and charged at
`
`constant current (typically 0.1 mA/cm2
`
`) within the voltage range 4.5 to 2.0 V.
`
`Typical electrochemical data for Li/xliM02•(1-x)Li2M '03 cells are provided in various
`
`plots, as shown in Figure 5, a Li/0.2Li2Mn03•0.8LiNi0.8Co0.20 2 cell; and Figure 6, a
`
`2 o Li/0.15Li2 Ti03•0.85LiMn02 cell. For example, the electrode of Example 1, namely
`
`0.2Li2Mn03•0.8LiNi0.8Co0.20 2 has a theoretical electrochemical capacity of 212 mAh/g.
`
`The electrochemical data in Fig. 5 indicate that an initial capacity of approximately 208
`
`mAh/g can be achieved from this electrode during the 'break-in' process on the initial
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`charge of the cell and, thereafter, a steady rechargeable discharge capacity of
`
`approximately 136 mAh/g. For the stabilized 0.15Li2Ti03•0.85LiMn02 electrode of
`
`Example 3, as seen in Fig. 6, a capacity of 179 mAh/g was achieved during the 'break-in'
`
`process on the initial charge of the cell, and thereafter a rechargeable capacity of 108
`
`mAh/g was achieved.
`
`The data in the examples provided above indicate that the principle of this invention
`
`can be used to stabilize LiM02 compounds with a Li2M'03 component, and specifically
`
`those containing M = Ni and/or Mn that are of major significance and interest to the lithium
`
`battery industry for replacing the lithium-cobalt-oxide, LiCo02 , as the electrode of choice,
`
`~f,ho thereby reducing cost. The performance and effectiveness of the xliM02•(1-x)Li2M03
`
`electrodes (O<x< 1) of this invention depend on the concentration of the trivalent transition
`
`..
`
`metal ions, M, in the structure, that is the value of"x" which preferably is equal to or greater
`
`than 0.8 and less than 1. A major advantage of the compounds of this invention is that
`
`the concentration of the trivalent M ions, the concentration of stabilizing tetravalent M' ions
`
`and concentration of monovalent lithium ions can be tailored in such a way to extend and
`
`optimize both the capacity of the electrode as well as the stabilizing effect of the Li2M'03
`
`component in the structure.
`
`For example, an electrode with the composition
`
`0.9LiMn0.9Ni0.10 2•0.1 Li2Ti03 (alternatively Li 1_2Mn0_72 Ni0.08Ti0_20 22) has a theoretical capacity
`
`of 252 mAh/g, which is only 8% less than that of LiCo02 used in state-of-the-art lithium
`
`20 cells.
`
`This invention, therefore, relates to a lithium-metal-oxide positive electrode for a
`
`non-aqueous electrochemical lithium cell as shown schematically in Figure 7, the cell
`
`represented by the numeral 1 0 having a negative electrode 12 separated from a positive
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`13
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`electrode 16 by an electrolyte 14, all contained in an insulating housing 18 with suitable
`
`terminals (not shown) being provided in electronic contact with the negative electrode 12
`
`and the positive electrode 16. Binders and other materials normally associated with both
`
`the electrolyte and the negative and positive electrodes are well known in the art and are
`
`not described herein, but are included as is understood by those of ordinary skill in this art.
`
`Figure 8 shows a schematic illustration of one example of a battery in which two strings of
`
`electrochemical lithium cells, described above, are arranged in parallel, each string
`
`comprising three cells arranged in series.
`
`While particular embodiments of the present invention have been shown and
`
`10 described, it will be appreciated by those skilled in the art that changes and modifications
`
`may be made without departing from the invention in its broader aspects. Therefore, the
`
`aim in the appended claims is to cover all such changes and modifications as fall within the
`
`true spirit and scope of the invention.
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`14
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`The embodiments of the invention in which an exclusive property or privilege is
`
`claimed are defined as follows:
`
`1.
`
`A lithium metal oxide positive electrode for a non-aqueous lithium cell
`
`prepared in its initial discharged state having a general formula xliM02•(1-x)Li2M'03 in
`
`which O<x<1, and where M is one~ or more trivalent ion with at least one ion being Mn, and
`
`where M' is one or more tetravalent ion.
`
`2.
`
`A lithium metal oxide positive electrode according to claim 1 in which
`
`0.8:s;x<1.
`
`3.
`
`A lithium metal oxide positive electrode according to claim 1 in which
`
`10 0.9:s;x<1.
`
`4.
`
`A lithium metal oxide positive electrode according to claim 1 in which M and
`
`!?"
`;:;F,
`~11
`
`M' are disordered in the electrode structure.
`
`5.
`
`A lithium metal oxide positive electrode according to claim 1 in which M' is
`
`selected from Mn, Ti and Zr.
`
`6.
`
`A lithium metal oxide positive electrode according to claim 1 in which M is Mn
`
`and M' is selected from at least one of Mn, Ti and Zr.
`
`7.
`
`A lithium metal oxide positive electrode according to claim 6 in which M, Mn,
`
`and M' is Ti.
`
`8.
`
`A lithium metal oxide positive electrode according to claim 1 in which M, and
`
`20 M' ions are partially replaced by mono- or multivalent cations.
`
`9.
`
`A lithium metal oxide positive electrode according to claim 8 in which M, and
`
`
`
`M' ions are partially replaced by Mg2+ or Al3
`
`+ ions.
`
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`15
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`10.
`
`A lithium metal oxide positive electrode according to claim 1 in which the
`
`lithium ions are partially replaced by H+ cations.
`
`11.
`
`A hydrothermal method for synthesizing a lithium metal oxide positive
`
`electrode xliM0 2•(1-x)Li2M'03 in which O<x<1, and where M is one or more trivalent ion
`
`with at least one ion being Mn, and where M' is one or more tetravalent ion, in which the
`
`synthesis occurs in an autoclave, at a pressure between 5 and 35 atmospheres and at a
`
`temperature between 100 and 2~;0 °C.
`
`12.
`
`A method accordin~J to claim 11 in which the pressure is between 10 and 20
`
`atmospheres and the temperature is between 180 and 230°C.
`
`10
`
`13.
`
`A method accordin!~ to claim 11 in which M is Mn and M' is Ti.
`
`14.
`
`A lithium metal oxide positive electrode for a non-aqueous lithium cell
`
`prepared in its initial discharged state having a general formula xliM02•(1-x)Li2M'03 in
`
`which O<x<1, and where M is on'~ or more trivalent ion with at least one ion being Ni, and
`
`where M' is one or more tetravalent ion with at least one ion being Mn.
`
`15.
`
`A lithium metal oxide positive electrode according to claim 14 in which
`
`0.8::;;x<1.
`
`16.
`
`A lithium metal oxide positive electrode according to claim 14 in which
`
`0.9::;;x<1.
`
`17.
`
`A lithium metal oxide positive electrode according to claim 14 in which M and
`
`20 M' are disordered in the electrode structure.
`
`18.
`
`A