Composite cathode active material, cathode and lithium battery containing the material and method of preparing the same

Patent metadata

Field	Value
Publication number	US-8936879-B2
Application number	US-201313801838-A
Country	US
Kind code	B2
Filing date	Mar 13, 2013
Priority date	Aug 22, 2012
Publication date	Jan 20, 2015
Grant date	Jan 20, 2015

Abstract

A composite cathode active material, a cathode including the composite cathode active material, and a lithium battery including the cathode. The composite cathode active material includes: a lithium transition metal oxide; and a lithium-containing impurity on a surface of the lithium transition metal oxide. The lithium-containing impurity includes free lithium in an amount of about 0.050 wt % or less based on a total weight of the composite cathode active material, and LiOH and Li 2 CO 3 in a mole ratio of LiOH to Li 2 CO 3 of about 0.50 or less.

First claim

What is claimed is:

1. A composite cathode active material comprising:
a lithium transition metal oxide; and
a lithium-containing impurity on a surface of the lithium transition metal oxide,
wherein:
the lithium-containing impurity comprises free lithium in an amount of about 0.050 wt % or less based on a total weight of the composite cathode active material, and
the lithium-containing impurity comprises LiOH and Li 2 CO 3 , and a mole ratio of LiOH to Li 2 CO 3 is about 0.50 or less.

2. The composite cathode active material of claim 1 , wherein the lithium-containing impurity comprises the free lithium in an amount of about 0.045 wt % or less based on the total weight of the composite cathode active material.

3. The composite cathode active material of claim 1 , wherein the mole ratio of LiOH to Li 2 CO 3 is about 0.480 or less.

4. The composite cathode active material of claim 1 , wherein an amount of LiOH is about 0.07 wt % or less based on the total weight of the composite cathode active material.

5. The composite cathode active material of claim 1 , wherein an amount of LiOH is about 0.065 wt % or less based on the total weight of the composite cathode active material.

6. The composite cathode active material of claim 1 , wherein the lithium transition metal oxide comprises at least one compound represented by Formulae 1 to 5 below:
Li x Co 1-y M y O 2-α X α   <Formula 1>

Li x CO 1-y-z Ni y M z O 2-α X α   <Formula 2>

Li x Mn 2-y M y O 4-α X α   <Formula 3>

Li x Co 2-y M y O 4-α X α   <Formula 4>

Li x Me y M z PO 4α X α   <Formula 5>

wherein, in Formulae 1 to 5, 0.90≦x≦1.1, 0≦y≦0.99, 0≦z≦0.5, 1-y-z>0, and 0≦α≦2;
Me is at least one metal selected from the group consisting of titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), aluminum (Al), magnesium (Mg), zirconium (Zr), and boron (B);
M is at least one element selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), zirconium (Zr), niobium (Nb), molybdenum (Mo), tungsten (W), zinc (Zn), aluminum (Al), silicon (Si), nickel (Ni), manganese (Mn), chromium (Cr), iron (Fe), vanadium (V), and a rare earth element; and
X is an element selected from the group consisting of oxygen (O), fluorine (F), sulfur (S), and phosphorous (P).

7. The composite cathode active material of claim 6 , wherein 0.4≦y≦0.99.

8. The composite cathode active material of claim 1 , wherein the lithium transition metal oxide comprises a compound represented by Formula 6 below:
Li[Li x Me y ]O 2+d   <Formula 6>

wherein, in Formula 6 above, x+y=1, 0≦x<1, and 0≦d≦0.1, and
Me is at least one metal selected form the group consisting of manganese (Mn), vanadium (V), chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), zirconium (Zr), rhenium (Re), aluminum (Al), boron (B), germanium (Ge), ruthenium (Ru), tin (Sn), titanium (Ti), niobium (Nb), molybdenum (Mo), and platinum (Pt).

9. The composite cathode active material of claim 1 , wherein the lithium transition metal oxide comprises a compound represented by Formula 7 below:
Li[Li x Ni a Co b Mn c ]O 2+d   <Formula 7>

wherein, in Formula 7, x+a+b+c=1; 0≦x<1, 0.4≦a<1, 0<b<1, 0<c<1; and 0≦d≦0.1.

10. The composite cathode active material of claim 1 , wherein the lithium transition metal oxide comprises a compound represented by Formula 8 below:
( p )Li 2 MO 3 -(1- p )LiMeO 2   <Formula 8>

wherein, in Formula 8, 0<p<1;
M is at least one metal selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), zirconium (Zr), niobium (Nb), molybdenum (Mo), tungsten (W), zinc (Zn), aluminum (Al), silicon (Si), nickel (Ni), manganese (Mn), chromium (Cr), iron (Fe), vanadium (V), and a rare earth element; and
Me is at least one metal selected from the group consisting of titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), aluminum (Al), magnesium (Mg), zirconium (Zr), and boron (B).

11. The composite cathode active material of claim 1 , wherein the lithium transition metal oxide comprises a compound represented by Formula 9 below:
p Li 2 MnO 3 -(1- p )LiNi a Co b Mn c O 2   <Formula 9>

wherein, in Formula 9, 0<p<1, 0<a<1, 0<b<1, 0<c<1, and a+b+c=1.

12. A cathode comprising the composite cathode active material of claim 1 .

13. The cathode of claim 12 , wherein the cathode comprises a current collector and a cathode active material layer on the current collector, and
a surface area of the cathode active material layer with protrusions is smaller than a surface area of the cathode active material layer without protrusions.

14. A lithium battery comprising the cathode of claim 13 .

15. A method of preparing a composite cathode active material, the method comprising:
mixing precursors of a lithium transition metal oxide together to prepare a mixture; and
calcining the mixture in an oxygen atmosphere at a temperature of about 950° C. or higher to obtain a calcined product; and
preparing the composite cathode active material from the calcined product, the prepared composite cathode active material comprising a lithium-containing impurity,
the lithium-containing impurity comprising free lithium in an amount of about 0.050 wt % or less based on a total weight of the composite cathode active material, and
the lithium-containing impurity comprising LiOH and Li 2 CO 3 and a mole ratio of LiOH to Li 2 CO 3 is about 0.50 or less.

16. The method of claim 15 , wherein the calcining is performed for about 5 hours or longer.

17. The method of claim 15 , wherein a mole ratio of Li to metals other than lithium (Me) in the mixture is about 1.05 or less.

18. The method of claim 15 , further comprising cooling the calcined product to room temperature.

19. The method of claim 18 , wherein the cooling is performed in an oxygen atmosphere.

20. The method of claim 18 , wherein the cooling of the calcined product from about 950° C. or higher to room temperature is performed for about 5 hours or longer.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Bae Myung-Hun
• Hase Naoyuki

Classifications

• H01M2010/4292

  Aspects relating to capacity ratio of electrodes/electrolyte or anode/cathode · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• Y02E60/122

  Cross-Sectional Technologies · mapped topic

• H01M10/4235

  Safety or regulating additives or arrangements in electrodes, separators or electrolyte (H01M10/4242 takes precedence) · CPC title

• H01M4/485 Primary

  of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence) · CPC title