Nonaqueous secondary battery and method of using the same
View Patent ↗A nonaqueous secondary battery having a positive electrode having a positive electrode mixture layer, a negative electrode, and a nonaqueous electrolyte, in which the positive electrode contains, as an active material, a lithium-containing transition metal oxide containing a metal element selected from the group consisting of Mg, Ti, Zr, Ge, Nb, Al and Sn, the positive electrode mixture layer has a density of 3.5 g/cm 3 or larger, and the nonaqueous electrolyte contains a compound having two or more nitrile groups in the molecule.
1. A nonaqueous secondary battery comprising: a positive electrode having a positive electrode mixture layer, a negative electrode, and a nonaqueous electrolyte, wherein
the positive electrode contains, as an active material, at least two lithium-containing transition metal oxides having different average particle sizes,
said lithium-containing transition metal oxide having the smallest average particle size is a lithium-containing transition metal oxide represented by the formula (1):
Li x M 1 y M 2 z M 3 v O 2 (1)
wherein M 1 represents at least one transition metal element selected from Co, Ni and Mn, M 2 represents Mg, or Mg and at least one metal element selected from the group consisting of Ti, Zr, Ge, Nb, Al and Sn, M 3 represents an element other than Li, M 1 and M 2 , and x, y, z and v are numbers satisfying the equations respectively: 0.97≦x<1.02, 0.8≦y<1.02, 0.002≦z≦0.05, and 0≦v≦0.05;
a content of Mg in the formula (1) is from 0.15% by mole to less than 2% by mole based on an amount of the metal element M 1 ;
the positive electrode mixture layer has a density of at least 3.5 g/cm 3 ; and the nonaqueous electrode mixture contains a compound having at least two nitrile groups in the molecule.
2. The nonaqueous secondary battery according to claim 1 , wherein a lithium-containing transition metal oxide other than the lithium-containing transition metal oxide having the smallest average particle size is a lithium-containing transition metal oxide represented by the formula (2):
Li a M 4 b M 5 c M 6 d O 2 (2)
wherein M 4 represents at least one transition metal element selected from Co, Ni and Mn, M 5 represents at least one metal element selected from the group consisting of Mg, Ti, Zr, Ge, Nb, Al and Sn, M 6 represents an element other than Li, M 4 and M 5 , and a, b, c and d are numbers satisfying the equations respectively: 0.97≦a<1.02, 0.8≦b<1.02, 0≦c≦0.02, and 0≦d≦0.02.
3. The nonaqueous secondary battery according to claim 1 , wherein said at least two lithium-containing transition metal oxides having different average particle sizes have different compositions of elements between them.
4. The nonaqueous secondary battery according to claim 2 , wherein a composition of elements of the lithium-containing transition metal oxide represented by the formula (2) is different from that of the lithium-containing transition metal oxide represented by the formula (1).
5. The nonaqueous secondary battery according to claim 1 , wherein M 2 in the formula (1) represents Mg and at least one metal element selected from the group consisting of Ti, Zr, Ge, Nb, Al and Sn.