Lithium secondary battery of improved low-temperature power property

Abstract

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 . An anode mix for a lithium secondary battery comprising a carbon-based anode active material, wherein the anode mix contains at least one compound of lithium metal oxides and/or lithium metal sulfides which form a potential of from 0 volt to less than 2 volts relative to a lithium metal reference electrode in an amount of 1 to 50% by weight, based on the total weight of the anode mix. 
     
     
         2 . The anode mix according to  claim 1 , wherein the compound serves to cause intercalation and deintercalation of lithium ions into/from these materials to thereby achieve instantaneous power output at a low temperature. 
     
     
         3 . The anode mix according to  claim 1 , wherein the compound is one or more selected from the group consisting of lithium metal oxides represented by Formula I and lithium metal sulfides represented by Formula II:
   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.   
     
     
         4 . The anode mix according to  claim 1 , wherein the carbon-based active material is a mixture of crystalline carbon and amorphous carbon. 
     
     
         5 . The anode mix according to  claim 4 , wherein the mixture is a mixture of hard carbon and graphite. 
     
     
         6 . The anode mix according to  claim 3 , wherein the lithium metal oxide of Formula I is Li 4 Ti 5 O 12 , LiTi 2 O 4  or a mixture thereof. 
     
     
         7 . The anode mix according to  claim 3 , wherein the lithium metal sulfide of Formula II is LiTiS 2 . 
     
     
         8 . The anode mix 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. 
     
     
         9 . The anode mix according to  claim 1 , further comprising a conductive material and a binder, and optionally a filler. 
     
     
         10 . A lithium secondary battery comprising an anode fabricated with the anode mix of  claim 1 , a cathode, a separator and a lithium salt-containing non-aqueous electrolyte. 
     
     
         11 . The battery according to  claim 10 , wherein the cathode comprises a mixture of a lithium manganese oxide and a lithium nickel-manganese-cobalt composite oxide as a cathode active material. 
     
     
         12 . The battery according to  claim 10 , 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.