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DESCRIPTION (COMPLETE) OCR NOT PREPARE
DUE TO PRINT PROBLEM
We Claim:
1. A method for regulating terminal voltage of a cathode for a lithium secondary battery when electric potential difference (voltage) between a cathode and an anode is OV during over discharge, which comprises forming a cathode by adding to a cathode active material containing a first lithium transition metal oxide as herein before described capable of lithium ion intercalation/deintercalation, a second lithium transition metal oxide as herein before described of which an irreversible capacity in the first charge/discharge cycle is greater than that of the first lithium transition metal oxide, as an additive.
2. The method as claimed in claim 1, wherein the additive is added to the extent of providing irreversibly lithium ions at least in such an amount as to compensate for an irreversible lithium-consuming reaction in an anode caused by the SEI film formation on the surface of an anode during the first charge.
3. The method as claimed in claim 1, wherein the additive is a lithium nickel oxide represented by the following formula 1, or a lithium nickel oxide represented by the following formula 1 that is surface-coated with an oxide other than lithium nickel oxides:
[Formula 1]
(Formula Removed)
wherein, x is a number satisfying -0.5
4. The method as claimed in claim 3, wherein the oxide
other than lithium nickel oxides is an oxide or composite oxide
of at least one element selected from the group consisting of Al,
Mg, Si, P, C, Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Mo, Zr and Nb.
5. A lithium secondary battery comprising a cathode (3) containing cathode active material containing a lithium transition metal oxide capable of lithium ion intercalation/ deintercalation, an anode (4), a separator (7) and a non-aqueous electrolyte (9) containing a lithium salt such as herein described and an electrolyte compound, such as herein described wherein the cathode comprises a cathode active material such as herein described.
6. The lithium secondary battery as claimed in claim 5, wherein the lithium salt is at least one selected from the group consisting of LiC1O4, LiCFsSO3, LiPF6, LiBF4, LiAsFe and LiN (CF3SO2) 2, and the electrolyte compound is at least one carbonate selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), gamma-butyrolactone (GBL), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC) and methylpropyl carbonate (MFC).
7. The lithium secondary battery as claimed in claim 5-6,
wherein the cathode active material contains a lithium transition
metal oxide capable of lithium ion intercalation /
deintercalation and a lithium nickel oxide represented by the
following formula 1 in which nickel is partially substituted with
other elements (with the proviso that y is not 0) , or a lithium
nickel oxide represented by the following formula 1 that is
surface-coated with an oxide other than lithium nickel oxides, as
an additive:
[Formula 1]
(Formula Removed)
wherein, x is a number satisfying -0.5
8. The lithium secondary battery as claimed in claim 5,
wherein the oxide other than lithium nickel oxides is an oxide or
composite oxide of at least one element selected from the group consisting of Al, Mg, Si, P, C, So, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Mo, Zr and Nb.
9. The lithium secondary battery as claimed in claim 5-7,
wherein the compound represented by formula 1 forms a tetra-
coordinated planar structure, (Ni,M)04 and two tetra-coordinated
planar structures facing to each other share one side formed by
0-0 so as to form a primary chain.
10. The lithium secondary battery as claimed in claim 5-7, wherein the compound represented by formula 1 has the following lattice constants: a=3.7±0.5 3, b=2.8+0.5 D, c=9.2±0.5 D, α= 90°, ß= 90°and Y= 90.
11. The lithium secondary battery as claimed in claim 5-7, wherein the lithium transition metal oxide is at least one selected from the group consisting of LiCoOa, LiNiOa, LiMnOa, LiMnaO4, Li (NiaCobMnc) O2, LiNi1-d COdO2, LiCO1-dMndO2, LiNi1-d MndO2, Li
(NixCOyMnz) O4, LiMn2-nNinO4, LiMn2-nCOnO4, LiCoPO4 and LiFePO4, wherein 0
12. The lithium secondary battery as claimed in claim 5-7,
which comprises the additive for a cathode active material in an
amount of 0.1 to 10 parts by weight based on 100 parts by weight
of the cathode active material.
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