Active material, nonaqueous electrolyte battery, battery pack and battery module
In general, according to one embodiment, there is provided an active material. The active material contains active material primary particles of a monoclinic niobium-titanium composite oxide. The monoclinic niobium-titanium composite oxide contains at least one element selected from the group consisting of Mo, V, and W. A content of the at least one element in the monoclinic niobium-titanium composite oxide is within a range of 0.01 atm % or more and 2 atm % or less. Each of the active material primary particles has an aspect ratio within a range of 1 or more and less than 4 of a primary particle and a crystallite size within a range of 5 nm or more and 90 nm or less.
1. An active material comprising active material primary particles of a monoclinic niobium-titanium composite oxide comprising at least one element selected from the group consisting of Mo, V, and W, wherein:
a content of the at least one element in the monoclinic niobium-titanium composite oxide is within a range of 0.01 atm % or more and 2 atm % or less; and
each of the active material primary particles has an aspect ratio within a range of 1 or more and less than 4 and a crystallite size within a range of 5 nm or more and 90 nm or less.
2. The active material according to claim 1 , wherein each of the active material primary particles has the aspect ratio within a range of 1 or more and 3 or less.
3. The active material according to claim 1 , wherein each of the active material primary particles has a crystallite size within a range of 10 nm or more and 70 nm or less.
4. The active material according to claim 1 , wherein the content of the at least one element in the monoclinic niobium-titanium composite oxide is within a range of 0.01 atm % or more and 0.3 atm % or less.
5. The active material according to claim 1 , wherein the monoclinic niobium-titanium composite oxide further comprises at least one element selected from the group consisting of Ta, Fe, Bi, Sb, As, P, Cr, B, Na, Mg, Al, and Si.
6. The active material according to claim 1 , wherein the monoclinic niobium-titanium composite oxide is represented by the general formula of Ti 1-a-c M1 a M3 c Nb 2-b-d M2 b M4 d O 7 :
wherein:
0≤a<1, 0≤b<1, and 0<c+d<1;
M1 and M2 are at least one element selected from the group consisting of Nb, Ta, Fe, Ti, Bi, Sb, As, P, Cr, B, Na, Mg, Al, and Si, and M1 and M2 may be the same or different from each other; and
M3 and M4 are at least one element selected from V, Mo, and W, and M3 and M4 may be the same or different from each other.
7. The active material according to claim 1 , further comprising a carbon-containing layer which covers at least a part of surfaces of the active material primary particles.
8. The active material according to claim 1 , which comprises secondary particles formed by an aggregation of the active material primary particles.
9. The active material according to claim 1 , which comprises secondary particles of the monoclinic niobium-titanium composite oxide.
10. A nonaqueous electrolyte battery comprising:
a negative electrode containing the active material according to claim 1 ;
a positive electrode; and
a nonaqueous electrolyte.
11. A battery pack comprising the nonaqueous electrolyte battery according to claim 10 .
12. A battery module comprising nonaqueous electrolyte batteries, each of which comprises
a negative electrode comprising the active material according to claim 1 ;
a positive electrode; and
a nonaqueous electrolyte,
wherein the nonaqueous electrolyte batteries are electrically connected in series and/or in parallel.
13. A battery pack comprising the battery module according to claim 12 .