LITHIUM COMPOSITE METAL OXIDE POWDER AND LITHIUM SECONDARY BATTERY POSITIVE ELECTRODE ACTIVE MATERIAL
A lithium composite metal oxide powder contains at least Li, Ni, an element X and an element M. The element X is at least one element selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga and V. The element M is at least one element selected from the group consisting of B, Si, S and P. A ratio M/(Ni+X) which indicates the amount of the element M relative to the total amount of Ni and the element X exceeds 0 mol % but is not more than 5 mol %. The lithium composite metal oxide powder contains core particles and a coating substance. The coating substance contains a compound produced by reaction of the element M and lithium. A weight reduction percentage 1 when a thermogravimetric measurement is conducted under specific measurement conditions 1 is not more than 0.15 wt %.
1 . A lithium composite metal oxide powder having a layered structure,
the lithium composite metal oxide powder containing at least Li, Ni, an element X and an element M, wherein
the element X is at least one element selected from the group consisting of Co, Mn, Fe, Cu, Ti, Mg, Al, W, Mo, Nb, Zn, Sn, Zr, Ga and V,
the element M is at least one element selected from the group consisting of B, Si, S and P,
a ratio M/(Ni+X) which indicates an amount of the element M relative to a total amount of Ni and the element X exceeds 0 mol % but is not more than 5 mol %,
the lithium composite metal oxide powder comprises core particles and a coating substance that coats surfaces of the core particles, wherein the coating substance contains a compound produced by reaction of the element M and lithium, and
a weight reduction percentage 1 when a thermogravimetric measurement is conducted under measurement conditions 1 described below is not more than 0.15 wt %.
(Measurement Conditions 1)
Sample: 10 mg of the lithium composite metal oxide powder
Measurement atmosphere: open air (gas flow rate: 220 mL/minute)
Measurement conditions: a temperature is raised from 40° C. to 600° C. at a rate of temperature increase of 10° C./minute, and a weight of the sample is measured when the temperature reaches 500° C., and then again when the temperature reaches 600° C.
Calculation method: Weight reduction percentage 1 (wt %)=[(weight (g) when the lithium composite metal oxide powder has been heated to 500° C.−weight (g) when the lithium composite metal oxide powder has been heated to 600° C.)/weight of the lithium composite metal oxide powder used in the thermogravimetric measurement]×100
2 . The lithium composite metal oxide powder according to claim 1 , which satisfies a compositional formula (I) shown below:
Li[Li m (Ni (1-n-p) X n M p ) 1-m ]O 2 (I)
wherein −0.1≤m≤0.2, 0<n≤0.8, 0<p≤0.05, and n+p<1.
3 . The lithium composite metal oxide powder according to claim 2 , wherein m in the compositional formula (I) satisfies 0<m≤0.2.
4 . The lithium composite metal oxide powder according to claim 1 , wherein a weight reduction percentage 2 when a thermogravimetric measurement is conducted under measurement conditions 2 described below is not more than 0.12 wt %.
(Measurement Conditions 2)
Sample: 10 mg of the lithium composite metal oxide powder
Measurement atmosphere: open air (gas flow rate: 220 mL/minute)
Measurement conditions: a temperature is raised from 40° C. to 400° C. at a rate of temperature increase of 10° C./minute, and a weight of the sample is measured when the temperature reaches 250° C., and then again when the temperature reaches 400° C.
Calculation method: Weight reduction percentage 2 (wt %)=[(weight (g) when the lithium composite metal oxide powder has been heated to 250° C.−weight (g) when the lithium composite metal oxide powder has been heated to 400° C.)/weight of the lithium composite metal oxide powder used in the thermogravimetric measurement]×100
5 . The lithium composite metal oxide powder according to claim 1 , having a BET specific surface area of at least 0.1 m 2 /g but not more than 3 m 2 /g.
6 . The lithium composite metal oxide powder according to claim 1 , having an average primary particle size of at least 0.1 μm but not more than 10 μm.
7 . The lithium composite metal oxide powder according to claim 1 , having a 50% cumulative volume particle size (D 50 ) determined by a particle size distribution measurement of at least 1 μm but not more than 10 μm.
8 . A lithium secondary battery positive electrode active material comprising the lithium composite metal oxide powder according to claim 1 .
9 . A lithium secondary battery positive electrode containing the lithium secondary battery positive electrode active material according to claim 8 .
10 . A lithium secondary battery having the lithium secondary battery positive electrode according to claim 9 .
11 . The lithium composite metal oxide powder according to claim 2 , wherein a weight reduction percentage 2 when a thermogravimetric measurement is conducted under measurement conditions 2 described below is not more than 0.12 wt %.
(Measurement Conditions 2)
Sample: 10 mg of the lithium composite metal oxide powder
Measurement atmosphere: open air (gas flow rate: 220 mL/minute)
Measurement conditions: a temperature is raised from 40° C. to 400° C. at a rate of temperature increase of 10° C./minute, and a weight of the sample is measured when the temperature reaches 250° C., and then again when the temperature reaches 400° C.
Calculation method: Weight reduction percentage 2 (wt %)=[(weight (g) when the lithium composite metal oxide powder has been heated to 250° C.−weight (g) when the lithium composite metal oxide powder has been heated to 400° C.)/weight of the lithium composite metal oxide powder used in the thermogravimetric measurement]×100
12 . The lithium composite metal oxide powder according to claim 2 , having a BET specific surface area of at least 0.1 m 2 /g but not more than 3 m 2 /g.
13 . The lithium composite metal oxide powder according to claim 2 , having an average primary particle size of at least 0.1 μm but not more than 10 μm.
14 . The lithium composite metal oxide powder according to claim 1 , having a 50% cumulative volume particle size (D 50 ) determined by a particle size distribution measurement of at least 1 μm but not more than 10 μm.
15 . A lithium secondary battery positive electrode active material comprising the lithium composite metal oxide powder according to claim 2 .
16 . A lithium secondary battery positive electrode containing the lithium secondary battery positive electrode active material according to claim 15 .
17 . A lithium secondary battery having the lithium secondary battery positive electrode according to claim 16 .
18 . A lithium secondary battery positive electrode active material comprising the lithium composite metal oxide powder according to claim 3 .
19 . A lithium secondary battery positive electrode containing the lithium secondary battery positive electrode active material according to claim 18 .
20 . A lithium secondary battery having the lithium secondary battery positive electrode according to claim 19 .