Lithium secondary battery of improved low-temperature power property
View Patent ↗Provided is a lithium secondary battery which has excellent low-temperature power output characteristics by the inclusion of a given amount of a lithium metal oxide and/or a lithium metal sulfide in an anode mix for a lithium secondary battery containing a carbon-based anode active material and is thereby capable of being used as a power source for electric vehicles (EVs) and hybrid electric vehicles (HEVs) that must provide high-power output at low temperatures as well as at room temperature.
1. A lithium secondary battery comprising a cathode, an anode, a separator and a lithium salt-containing non-aqueous electrolyte,
wherein the cathode comprises a mixture of a lithium manganese oxide and a lithium nickel-manganese-cobalt composite oxide as a cathode active material; and
wherein the anode comprises an anode mix for a lithium secondary battery which comprises a carbon-based anode active material, in which the anode mix contains at least one compound selected from the group consisting of lithium metal oxides represented by Formula I and lithium metal sulfides represented by Formula II in an amount of 1 to 50% by weight, based on the total weight of the anode mix:
Li x M y O z (I)
wherein
M is Ti, Sn, Cu, Pb, Sb, Zn, Fe, In, Al or Zr; and
x, y and z are determined by an oxidation number of M.
Li x′ M y′ S z′ (II)
wherein
M is Ti, Sn, Cu, Pb, Sb, Zn, Fe, In, Al or Zr; and
x′, y′ and z′ are determined by an oxidation number of M.
2. The lithium secondary battery according to claim 1 , wherein the carbon-based active material is a mixture of crystalline carbon and amorphous carbon.
3. The lithium secondary battery according to claim 2 , wherein the mixture is a mixture of hard carbon and graphite.
4. The lithium secondary battery according to claim 1 , wherein the lithium metal oxide of Formula I is Li 4 Ti 5 O 12 , LiTi 2 O 4 or a mixture thereof.
5. The lithium secondary battery according to claim 1 , wherein the lithium metal sulfide of Formula II is LiTiS 2 .
6. The lithium secondary battery according to claim 1 , wherein the content of the compound is in the range of 5 to 30% by weight, based on the total weight of the anode mix.
7. The lithium secondary battery according to claim 1 , further comprising a conductive material and a binder, and a filler.
8. The battery according to claim 1 , wherein the battery is used as a power source for an electric vehicle (EV) or a hybrid electric vehicle (HEV), requiring low-temperature power output characteristics.