Core-Shell Lithium Transition Metal Oxides
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Abstract
A lithium transition metal oxide powder for use in a rechargeable battery is disclosed, where the surface of the primary particles of said powder is coated with a LiF layer, where this layer consists of a reaction product of a fluorine-containing polymer and the primary particle surface. The lithium of the LiF originates from the primary particles surface. Examples of the fluorine-containing polymer are either one of PVDF, PVDF-HFP or PTFE. Examples of the lithium transition metal oxide are either one of —LiCodMeO2, wherein M is either one of both of Mg and Ti, with e<0.02 and d+e=1; —Li1+aM′1−aO2±bM1kSm with −0.03<a<0.06, b<0.02, M′ being a transition metal compound, consisting of at least 95% of either one or more elements of the group Ni, Mn, Co and Ti; M1 consisting of either one or more elements of the group Ca, Sr, Y, La, Ce and Zr, with 0≦k≦0.1 in wt %; and 0<m<0.6, m being expressed in mol %; and —LiaNixCOyM″zO2±eAf, with 0.9<a′<1.1, 0.5≦x≦0.9, 0<y≦0.4, 0<z≦0.35, e<0.02, 0≦f≦0.05 and 0.9<(x+y+z+f)<1.1; M″ consisting of either one or more elements from the group Al, Mg, and Ti; A consisting of either one or both of S and C.
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Citations
33 Claims
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1-14. -14. (canceled)
- 15. A lithium transition metal oxide powder for use in a rechargeable battery, the powder comprising primary particles having a surface coated with a LiF coating layer, wherein the soluble base content of the lithium transition metal oxide powder, determined by pH titration, is less than 60% of the soluble base content of a lithium transition metal oxide powder having uncoated primary particles, wherein said LiF coating layer has a thickness of at least 0.5 nm.
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23. A method for covering a lithium transition metal oxide powder with a LiF coating, the method comprising:
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providing a transition metal precursor prepared from the co-precipitation of transition metal sulphates with a base providing a lithium precursor comprising one of LiOH*H2O or LiNO3, both containing a carbonate impurity, or Li2CO3, reacting the transition metal precursor and the lithium precursor at a temperature above 600°
C., thereby obtaining a lithium transition metal oxide powder carrying a Li2CO3 impurity,mixing the lithium transition metal oxide powder carrying a Li2CO3 impurity with a fluorine-containing polymer to form a powder-polymer mixture, and heating the powder-polymer mixture at a temperature of between 140°
C. and 300°
C. above the melting temperature of the fluorine-containing polymer,wherein a LiF coating layer having a thickness of at least 0.5 nm is formed. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
Li1+aM′
1−
aO2±
bM1kSm with −
0.03<
a<
0.06, b<
0.02, wherein M′
is a transition metal compound, wherein at least 95% of M′
comprises one or more elements selected from the group consisting of Ni, Mn, Co, Mg and Ti;
M1 comprises one or more elements selected from the group consisting of Ca, Sr, Y, La, Ce and Zr, with 0≦
k≦
0.1 in wt %; and
0≦
m≦
0.6, m being expressed in mol %; andLia″
NixCoyM″
zO2±
eAf, with 0.9<
a′
<
1.1, 0.5≦
x≦
0.9, 0<
y≦
0.4, 0<
z≦
0.35, e<
0.02, 0≦
f≦
0.05 and 0.9<
(x+y+z+f)<
1.1;
wherein M″
comprises one or more elements selected from the group consisting of Al, Mg, and Ti; and
A comprises one or both of S and C.
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30. The method of claim 29, wherein M′
- =Nia″
Mnb″
Coc″
, with a″
>
0, b″
>
0, c″
>
0 and a″
+b″
+c″
=1; and
a″
/b″
>
1.
- =Nia″
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31. The method of claim 29, wherein 0.5≦
- a″
≦
0.7, 0.1<
c″
<
0.35, and a″
+b″
+c″
=1.
- a″
-
32. The method of claim 23, wherein the LiF coating layer has a thickness of at least 0.8 nm.
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33. The method of claim 32, wherein the LiF coating layer has a thickness of at least 1 nm.
Specification