Nonaqueous secondary battery comprising at least two lithium-containing transition metal oxides of different average particle sizes
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, a lithium-containing transition metal oxide having the smallest average particle size among said at least two lithium-containing transition metal oxides having different average particle sizes is a lithium-containing transition metal oxide represented by the formula (I):
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, provided that a proportion of Co in the transition metal element M 1 is 65% by mole or more, M 2 represents 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, the positive electrode mixture layer has a density of at least 3.5 g/cm 3 , and the nonaqueous electrolyte contains succinonitrile.
2. The nonaqueous secondary battery according to claim 1 , wherein said nonaqueous electrolyte contains succinonitrile in an amount of 0.005 to 1% by weight based on the whole weight of the nonaqueous electrolyte.
3. The nonaqueous secondary battery according to claim 1 or 2 , wherein, among said at least two lithium-containing transition metal oxides having different average particle sizes, a lithium-containing transition metal oxide or lithium-containing transition metal oxides 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 1′ b M 2′ c M 3′ d O 2 (2)
wherein M 1′ represents at least one transition metal element selected from Co, Ni and Mn, M 2′ represents 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 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.
4. The nonaqueous secondary battery according to claim 3 , wherein, among said at least two lithium-containing transition metal oxides having different average particle sizes, a lithium-containing transition metal oxide or lithium-containing transition metal oxides other than the lithium-containing transition metal oxide having the smallest average particle size has an average particle size of 5 to 25 μm.
5. The nonaqueous secondary battery according to claim 1 or 2 , wherein, among said at least two lithium-containing transition metal oxides having different average particle sizes, the lithium-containing transition metal oxide having the smallest average particle size has an average particle size of 2 to 10 um.
6. The nonaqueous secondary battery according to claim 1 or 2 , wherein said nonaqueous electrolyte further contains vinylene carbonate.
7. The nonaqueous secondary battery according to claim 3 , wherein z in the formula (I) is larger than c in the formula (2).