Lithium cobalt oxide material

Abstract

LiCoO.sub.2 material comprises LiCoO.sub.2 particles obtainable by a process in which Co(OH).sub.2 particles comprising essentially octahedral shape particles, or Co.sub.3O.sub.4 particles obtained from Co(OH).sub.2 comprising essentially octahedral shape particles, or Co.sub.3O.sub.4 particles comprising essentially octahedral shape particles and lithium salt are heated. Also disclosed are Co(OH).sub.2 particles and the Co.sub.3O.sub.4 particles. The LiCoO.sub.2 material can be used especially as a cathode material in Li-ion batteries.

Claims

1. A method comprising: (a) reacting a reaction mixture comprising: (i) a cobalt solution containing chloride; (ii) a solution of ammonia hydroxide; and (iii) a solution of an alkaline hydroxide; wherein pH of the reaction mixture is maintained within the range of 10.0-12.5 and temperature of the reaction mixture is maintained within the range of 30-50 C.; (b) isolating cobalt particles comprising Co(OH).sub.2 particles from the reaction mixture comprising -Co(OH).sub.2 particles with an octahedral shape and a P3m1 space group in X-ray powder diffraction, wherein the isolated -Co(OH).sub.2 particles have a tap density (Tde) of in the range of 1.7-2.8 g/cm.sup.3; (c) preparing a mixture comprising: (i) the isolated cobalt particles of step (b); and (ii) lithium salt comprising Li.sub.2CO.sub.3, LiOH, or a mixture thereof, wherein the prepared mixture of cobalt particles and lithium salt has a Li/Co molar-ratio of 0.95-1.05; and (d) heating the mixture of cobalt particles and lithium salt at 800-1100 C. for 1-10 hours in air to prepare cobalt particles comprising LiCoO.sub.2 particles, wherein the LiCoO.sub.2 particles have the following properties: (i) free Li.sub.2CO.sub.3-% of the LiCoO.sub.2 particles is <0.05, (ii) the initial discharge capacity (mAh/g) of the LiCoO.sub.2 particles is >154.5, (iii) Tde (tap density, g/cm3) of the LiCoO2 particles is 2.7-3.1, (iv) a pH of a suspension of the LiCoO2 particles is below 10.1, and (v) the LiCoO.sub.2 particles consist essentially of LiCoO.sub.2 particles having an octahedral shape.

2. The method of claim 1, wherein the pH of the suspension of the LiCoO.sub.2 particles is below 9.7.

3. The method of claim 1, wherein the octahedral shape is a polyhedron with eight triangular-shaped faces and six vertexes.

4. The method of claim 1, wherein the reaction mixture is reacted by adding the cobalt solution to the solution of ammonia hydroxide and the solution of the alkaline hydroxide.

5. The method of claim 1, wherein the concentration of ammonia hydroxide in the solution of ammonia hydroxide is equivalent to the concentration of the alkaline hydroxide in the solution of the alkaline hydroxide and wherein the pH of the reaction mixture is maintained within the range of 10.0-12.5 by controlling feed rates of the solution of ammonia hydroxide and the solution of the alkaline hydroxide within a ratio range of 1-7.

6. The method of claim 1, wherein the average particle size D50 of the isolated -Co(OH).sub.2 particles is in the range of 3-40 m.

7. The method of claim 1, wherein the surface area (SA) of the isolated -Co(OH).sub.2 particles is in the range of 0.4-5 m.sup.2/g.

8. The method of claim 1, wherein the reaction mixture comprises 70-170 g/L cobalt.

9. The method of claim 1, wherein the alkaline hydroxide comprises sodium hydroxide.

10. The method of claim 1, wherein the reaction mixture further comprises a dopant selected from Mg, Ca, Sr, Ti, Zr, B, Al, F, and a mixture thereof.

11. The method of claim 10, wherein the mixture comprises the dopant at a concentration in the range of 0.05-5 mol% of Co.

12. The method of claim 1, wherein prior to heating the isolated -Co(OH).sub.2 particles, the isolated -Co(OH).sub.2 particles are mixed with a dopant selected from Mg, Ca, Sr, Ti, Zr, B, Al, F, and a mixture thereof.

13. The method of claim 12, wherein the mixture comprises the dopant at a concentration in the range of 0.05-5 mol% of Co.

14. A method comprising: (a) reacting a reaction mixture comprising: (i) a cobalt solution containing chloride; (ii) a solution of ammonia hydroxide; and (iii) a solution of an alkaline hydroxide; and wherein pH of the reaction mixture is maintained within the range of 10.0-12.5 and temperature of the reaction mixture is maintained within the range of 30-50 C.; (b) isolating cobalt particles comprising Co(OH).sub.2 particles from the reaction mixture consisting essentially of -Co(OH)2 particles with an octahedral shape and a P3m1 space group in X-ray powder diffraction, wherein the isolated -Co(OH).sub.2 particles have a tap density (Tde) of in the range of 1.7-2.8 g/cm.sup.3; (c) heating the isolated cobalt particles at 500-1200 C. for 0.5-10 hours in air to prepare cobalt particles comprising Co.sub.3O.sub.4 particles; and (d) preparing a mixture comprising: (i) the cobalt particles comprising Co(OH).sub.2 particles of step (b), the cobalt particles comprising Co.sub.3O.sub.4 particles of step (c), or a mixture thereof; and (ii) lithium salt comprising Li.sub.2CO.sub.3, LiOH, or a mixture thereof, wherein the prepared mixture of cobalt particles and lithium salt has a Li/Co molar-ratio of 0.95-1.05; and (e) heating the mixture of cobalt particles and lithium salt at 800-1100 C. for 1-10 hours in air to prepare cobalt particles comprising LiCoO.sub.2 particles, wherein the LiCoO.sub.2 particles have the following properties: (i) free Li.sub.2CO.sub.3-% of the LiCoO.sub.2 particles is <0.05, (ii) the initial discharge capacity (mAh/g) of the LiCoO2 particles is >154.5, (iii) Tde (tap density, g/cm.sup.3) of the LiCoO.sub.2 particles is 2.7-3.1, (iv) a pH of a suspension of the LiCoO.sub.2 particles is below 10.1, and (v) the LiCoO.sub.2 particles consist essentially of LiCoO.sub.2 particles having an octahedral shape.

15. The method of claim 14, wherein the pH of the suspension of the LiCoO.sub.2 particles is below 9.7.

16. The method of claim 14, wherein the octahedral shape is a polyhedron with eight triangular-shaped faces and six vertexes.

17. The method of claim 14, wherein the reaction mixture is reacted by adding the cobalt solution to the solution of ammonia hydroxide and the solution of the alkaline hydroxide.

18. The method of claim 14, wherein the concentration of ammonia hydroxide in the solution of ammonia hydroxide is equivalent to the concentration of the alkaline hydroxide in the solution of the alkaline hydroxide and wherein the pH of the reaction mixture is maintained within the range of 10.0-12.5 by controlling feed rates of the solution of ammonia hydroxide and the solution of the alkaline hydroxide within a ratio range of 1-7.

19. The method of claim 14, wherein the average particle size D50 of the isolated -Co(OH).sub.2 particles is in the range of 3-40 m.

20. The method of claim 14, wherein the surface area (SA) of the isolated -Co(OH).sub.2 particles is in the range of 0.4-5 m.sup.2/g.

21. The method of claim 14, wherein the reaction mixture comprises 70-170 g/L cobalt.

22. The method of claim 14, wherein the alkaline hydroxide comprises sodium hydroxide.

23. The method of claim 14, wherein the reaction mixture further comprises a dopant selected from Mg, Ca, Sr, Ti, Zr, B, Al, F, and a mixture thereof.

24. The method of claim 23, wherein the mixture comprises the dopant at a concentration in the range of 0.05-5 mol% of Co.

25. The method of claim 14, wherein prior to heating the isolated -Co(OH).sub.2 particles, the isolated -Co(OH).sub.2 particles are mixed with a dopant selected from Mg, Ca, Sr, Ti, Zr, B, Al, F, and a mixture thereof.

26. The method of claim 25, wherein the mixture comprises the dopant at a concentration in the range of 0.05-5 mol% of Co.

Description

DESCRIPTION OF THE DRAWINGS

(1) The enclosed drawings form a part of the written description of the invention. They relate to the examples given later and show properties of materials prepared in accordance with the examples.

(2) FIG. 1 provides an XRD pattern of Example 1 Co(OH).sub.2 particles.

(3) FIG. 2 provides an SEM figure of Example 1 Co(OH).sub.2 particles.

(4) FIG. 3 provides an SEM figure of Example 2 Co.sub.3O.sub.4 particles.

(5) FIG. 4 provides an SEM figure of Example 3 Co.sub.3O.sub.4 particles.

(6) FIG. 5 provides an XRD pattern of Example 4 LiCoO.sub.2 particles.

(7) FIG. 6 provides an SEM figure of Example 4 LiCoO.sub.2 particles.

(8) FIG. 7 provides an SEM figure of Example 5 LiCoO.sub.2 particles.

(9) FIG. 8 provides an SEM figure of Example 6 LiCoO.sub.2 particles.

(10) FIG. 9 provides an SEM figure of Example 7 LiCoO.sub.2 particles.

(11) FIG. 10 provides an SEM figure of Example 8 Zr doped LiCoO.sub.2 particles.

(12) FIG. 11 provides a Tde comparison of Example 8 doped LiCoO2 particles.

(13) FIG. 12 provides an XRD pattern of Comparative example 1 Co(OH).sub.2 particles.

(14) FIG. 13 provides an SEM figure of Comparative example 1 Co(OH).sub.2 particles.

(15) FIG. 14 provides an SEM figure of Comparative example 2 Co.sub.3O.sub.4 particles.

(16) FIG. 15 provides an SEM figure of Comparative example 3 LiCOO.sub.2 particles.

(17) FIG. 16 provides an SEM figure of Comparative example 4 LiCOO.sub.2 particles.

(18) FIG. 17 provides an SEM figure of Comparative example 5 LiCOO.sub.2 particles.

(19) FIG. 18 provides a Tde comparison of Comparative example 6 doped LiCOO.sub.2 particles.

DETAILED DESCRIPTION OF THE INVENTION

(20) The invention concerns a new type of lithium cobalt oxide (LiCoO.sub.2) material. The material comprises LiCoO.sub.2 particles obtainable by a process in which Co(OH).sub.2 particles comprising essentially octahedral shape particles, or Co.sub.3O.sub.4 particles obtainable from Co(OH).sub.2 comprising essentially octahedral shape particles, or Co.sub.3O.sub.4 particles comprising essentially octahedral shape particles, and lithium salt are heated. Preferably, the LiCoO.sub.2 particles comprise essentially octahedral shape particles, and more preferably essentially consist of essentially octahedral shape particles. The material can be used in Li-ion batteries especially as a cathode material.

(21) The invention also concerns cobalt oxide (CO.sub.3O.sub.4) particles obtainable from cobalt hydroxide (Co(OH).sub.2) particles comprising essentially octahedral shape particles. Preferably, the Co.sub.3O.sub.4 particles comprise essentially octahedral shape particles, and more preferably, essentially consist of essentially octahedral shape particles. The Co.sub.3O.sub.4 particles can be used as precursors in the preparation of the LiCoO.sub.2 particles.

(22) The invention also concerns Co(OH).sub.2 particles comprising essentially octahedral shape particles. Preferably, the particles essentially consist of essentially octahedral shape particles. The Co(OH).sub.2 particles can be used as precursors in the preparation of the Co.sub.3O.sub.4 particles or in the preparation of the LiCoO.sub.2 particles.

(23) The mentioned Co(OH).sub.2 particles with octahedral morphology can be prepared from a cobalt solution containing chloride, and having a cobalt concentration in the range of 20-300 g/l by reacting simultaneously with an ammonia containing chemical, for example ammonium hydroxide, and an alkaline hydroxide, for example sodium hydroxide, to precipitate the cobalt ions into a Co(OH).sub.2 precipitate. Preferably, the cobalt concentration is in the range of 70-170 g/l. Feed rates of the ammonia containing chemical and the alkaline hydroxide solution are controlled in order to control pH. A ratio of the feed rates between the alkaline hydroxide solution and the ammonia containing chemical with equivalent concentrations is in the range of 1-7. pH is controlled within the range of 10.0-14.0, preferably 10.0-12.5, to minimize the amount of non-precipitated cobalt ions. Temperature is kept essentially constant at selected, relatively low temperature in the range of 30-50 C. during the above reaction when preparing mentioned Co(OH).sub.2 particles with octahedral morphology. For a sufficient mixing, the reaction suspension is mixed by an impeller with a rotation speed monitoring. The precipitated particles are filtered, washed with hot ion exchanged water and dried at 100-150 C. in air.

(24) Co.sub.3O.sub.4 particles of the invention can be prepared by calcinating Co(OH).sub.2 particles produced by the method described above at 110-1200 C. for 0.5-20 h in air. Preferably, the particles are calcinated at 500-1000 C. for 1-10 h. The formed particles may be screened and/or milled after the calcination process.

(25) LiCoO.sub.2 particles of the invention can be prepared by mixing Co(OH).sub.2 particles as a precursor produced by the method described above with Li salt particles, preferably Li.sub.2CO.sub.3 or LiOH particles, with the Li/Co molar-ratio of 0.90-1.10, preferably 0.95-1.05. No excess of Li need be used, but the ratio can be selected optimally based of desired properties. According to another embodiment, LiCoO.sub.2 particles of the invention can be prepared by mixing Co.sub.3O.sub.4 particles as a precursor produced by the method described above with Li salt particles, preferably Li.sub.2CO.sub.3 or LiOH particles, with the Li/Co molar-ratio of 0.90-1.10, preferably 0.95-1.05, more preferably 1.00. The obtained mixture is calcinated at 800-1100 C. for 1-10 h in air or in other oxygen containing atmosphere. This calcination process is called as the lithiation process. The formed particles may be screened and/or milled after the lithiation process.

(26) Co(OH).sub.2 particles produced by the method described above were analyzed for various physical and chemical characteristics including the particle size distribution (including average particle size D50), the tap density (Tde), the surface area (SA), the impurity levels (for example alkali metal, such as sodium, and one or more anions from sulphur, chloride, and nitride), and the overall particle morphology. The average particle size D50, as measured by laser diffraction, was determined to be controllable typically in the range of 3-40 m, especially in the range of 5-20 m. The tap density was controllable typically in the range of 1.7-2.8 g/cm.sup.3, especially in the range of 1.9-2.3 g/cm.sup.3. The surface area was determined to be typically in the range of 0.4-5 m.sup.2/g, especially in the range of 1.0-2.0 m.sup.2/g. The alkali metal, for example sodium, level was controllable typically to less than 400 ppm, typically to less than 200 ppm, and each of the anions sulphur, chloride, and nitride typically to less than 0.15%, especially to less than 0.07%. Other impurities may be controlled based on the feed solutions used during the precipitation method. The Co(OH).sub.2 particles were determined from scanning electron microscope (SEM) figures to comprise essentially octahedral shape particles. The crystal structure and chemical composition of Co(OH).sub.2 particles were determined by X-ray powder diffraction (XRD) and the potentiometric titration method. Typical XRD shows a pure -Co(OH).sub.2 phase with the P3m1 space group. Potentiometric titration gives Co-% values typically close to the theoretical value of 63.4%.

(27) Co.sub.3O.sub.4 particles produced by the methods described above were analyzed for various physical characteristics including the particle size distribution (including average particle size D50), the tap density, the surface area, the impurity levels (for example alkali metal, such as sodium, and one or more anions from sulphur, chloride, and nitride) and the overall particle morphology. The average particle size D50, as measured by laser diffraction, was determined to be controllable typically in the range of 3-30 m, especially in the range of 5-20 m. The tap density was controllable typically in the range of 1.8-3.0 g/cm.sup.3, especially in the range of 2.1-2.6 g/cm.sup.3. The surface area was determined to be typically in the range of 0.2-20 m.sup.2/g, especially in the range of 0.3-2.0 m.sup.2/g. The alkali metal, such as sodium, level was controllable typically to less than 400 ppm, especially to less than 200 ppm, and each anion from sulphur, chloride, and nitride typically to less than 0.10%, especially to less than 0.03%. Other impurities may be controlled based on the feed solutions used during the precipitation method of Co(OH).sub.2. A risk of a contamination during a possible milling step is low since the need for a milling is reduced due to a typically formed soft cake in the calcination. In one embodiment, the Co.sub.3O.sub.4 particles were determined from the SEM figures to comprise essentially octahedral shape particles. In another embodiment, the Co.sub.3O.sub.4 particles were determined from the SEM figures to comprise irregular shape particles without essentially octahedral shape particles. The crystal structure and chemical composition of Co.sub.3O.sub.4 particles were determined by X-ray powder diffraction (XRD) and potentiometric titration method. Typical XRD shows a pure Co.sub.3O.sub.4 phase with the spinel crystal structure with the Fd3m space group. Potentiometric titration gives Co-% values typically close to the theoretical value of 73.4%.

(28) LiCoO.sub.2 particles produced by the methods described above were analyzed for various physical characteristics including the particle size distribution (including average particle size D50), the tap density, the surface area, the impurity levels (for example alkali metal, such as sodium, and one or more anions from sulphur, chloride, and nitride) and the overall particle morphology. The average particle size D50, as measured by laser diffraction, was determined to be controllable typically in the range of 3-30 m, especially in the range of 5-20 m. The tap density was controllable typically in the range of 1.9-3.3 g/cm.sup.3, especially in the range of 2.7-3.1 g/cm.sup.3. The surface area was determined to be typically in the range of 0.1-0.6 m.sup.2/g, especially in the range of 0.2-0.5 m.sup.2/g. The alkali metal, such as sodium, level was controllable typically to less than 400 ppm, especially to less than 200 ppm, and each anion from sulphur, chloride, and nitride typically to less than 0.10%, especially to less than 0.02%. Other impurities may be controlled based on the feed solutions used during the precipitation method of Co(OH).sub.2. A risk of a contamination during a possible milling step is low since the need for a milling is reduced due to a typically formed soft cake in the calcination. In one embodiment, the LiCoO.sub.2 particles were determined from the SEM figures to comprise essentially octahedral shape particles In another embodiment, the LiCoO.sub.2 particles were determined from the SEM figures to comprise irregular shape particles without essentially octahedral shape particles. The crystal structure and chemical composition of LiCoO.sub.2 particles were determined by X-ray powder diffraction (XRD) and potentiometric titration method and atomic absorption spectroscopy (AAS). Typical XRD shows a pure LiCoO.sub.2 phase with the layered crystal structure with the R3m space group. Potentiometric titration gives Co-% values typically close to the theoretical value of 60.2%. AAS gives the Li-% values typically close to the theoretical value of 7.1%.

(29) pH and free Li.sub.2CO.sub.3 of LiCoO.sub.2 particles were determined. pH was determined from a suspension containing 1 g of LiCoO.sub.2 sample in 100 ml of deionized water. Free Li.sub.2CO.sub.3 was determined by mixing 20 g of LiCoO.sub.2 sample in 100 ml of deionized water followed by filtration. The filtered water solution was then titrated by a HCl solution in two steps. In the first, HCl was added until a phenolphthalein indicator changed colour at neutral conditions. In the second step, methyl orange was used as an indicator. The free Li.sub.2CO.sub.3-% can be obtained with the aid of the second step when methyl orange change colour at acidic conditions. pH gives indication about the free hydroxide phases, for example LiOH, in LiCoO.sub.2 particles. Both pH and free Li.sub.2CO.sub.3 give indication of the level of gaseous components in the cell comprising of the LiCoO.sub.2 cathode material. LiOH and Li.sub.2CO.sub.3 can be decomposed electrochemically at cell voltages, generating for example oxygen and carbon dioxide gases. These predominantly gaseous products can lead to pressure buildup in the cell and further generate a safety issue. By minimization of the formation of LiOH and Li.sub.2CO.sub.3 in the preparation method of LiCoO.sub.2 particles, the pressure buildup and the safety issue can be eliminated from the cell. Typically, pH was less than 10.1, especially less than 9.7, and free Li.sub.2CO.sub.3 was less than 0.1%, especially less than 0.03%.

(30) Electrochemical properties of the LiCoO.sub.2 particles were determined with coin cell tests. The coin cell testing conditions were as follow: Coin cell: CR2016; Anode: Lithium; Cathode: Active material 95%, acetylene black 2%, PVdF 3%; Coating thickness 100 m on 20 m; Al foil, pressing by 6 t/cm.sup.2 pressure; Cathode size 1 cm.sup.2; Electrolyte: 1 M LiPF.sub.6 (EC/DMC=1/2); Separator: Glass filter; Charging: 0.2 mA/cm.sup.2 (about 0.15 C) up to 4.30 V (vs. Li/Li.sup.+); 1.sup.st discharge: 0.2 mA/cm.sup.2 to 3.00 V (vs. Li/Li.sup.+); 2.sup.nd discharge: 2.0 mA/cm.sup.2 to 3.00 V (vs. Li/Li.sup.+); 3.sup.rd discharge: 4.0 mA/cm.sup.2 to 3.00 V (vs. Li/Li.sup.+); 4.sup.th discharge: 8.0 mA/cm.sup.2 to 3.00 V (vs. Li/Li.sup.+); 5.sup.th discharge60.sup.th discharge 4.0 mA/cm.sup.2 to 3.00 V (vs. Li/Li.sup.+). Rate capability is determined as 8.0 mA/cm.sup.2/0.2 mA/cm.sup.2. Typically, the initial charge capacity was more than 154 mAh/g, especially more than 155 mAh/g, the rate capability was more than 85%, especially more than 95%, and the cyclability (5-30) was more than 70%, especially more than 90%.

(31) Octahedral shape means a shape of a polyhedron with eight faces and six vertexes. All the faces have shape of a triangle. Height, length and depth of the octahedron are determined with the distance between three pair of opposite vertexes. In a regular octahedron, the ratio of height:length:depth is 1:1:1. In this case, such distortion is allowed that any of the previous ratios can be in the range of 0.3-3. Such distortion is also allowed that faces can contain voids and nodules and triangle edges are not necessarily straight lines but can contain curves. In accordance with the invention, preferably more than 20%, more preferably more than 50% of the Co(OH).sub.2 particles have essentially octahedral shape. Most preferably essentially all particles have essentially octahedral shape.

(32) In accordance with the invention, LiCoO.sub.2 particles with a high density and a good electrochemical quality could be obtained when a low Li/Co ratio was used in the lithiation. Typically, when a low Li/Co ratio has been used in the lithiation, the density of the formed particles has become low, which is not desirable for a good quality cathode material. Further in accordance with the invention, LiCoO.sub.2 particles with a high density and a good electrochemical quality as well as a low risk of a pressure buildup in a cell were obtained when a low Li/Co ratio was used in the lithiation. Typically, the density of the formed particles in the lithiation has been increased with the aid of using a high Li/Co-ratio. Usually this has lead to deterioration of the electrochemical quality and to an increased risk of pressure buildup in a cell. In addition, a high Li/Co ratio can lead to difficulties to control a particle size distribution and morphology of the formed particles in the lithiation as well as an increased contamination risk during milling due to a typically formed hard cake in the lithiation. In accordance with the invention, the morphology of the formed LiCoO.sub.2 particles in the lithiation could be remained essentially the same compared to that of the cobalt precursor particles. Preferably more than 20%, more preferably more than 50%, most preferably essentially all of the LiCoO.sub.2 particles have the same morphology than those of cobalt precursor particles.

(33) In accordance with the invention, Co(OH).sub.2 particles could be formed whose morphology remained essentially the same after the lithiation. Further, in accordance with the invention, Co(OH).sub.2 particles could be formed that can be used as a precursor to obtain LiCoO.sub.2 particles with a high density and good electrochemical quality. Further, in accordance with the invention, Co(OH).sub.2 particles could be formed that can be used as a precursor to obtain LiCoO.sub.2 particles with a high density and good electrochemical quality, and with a low risk of a pressure buildup in a cell.

(34) In accordance with the invention, Co.sub.3O.sub.4 particles could be formed whose morphology remained essentially the same after the lithiation. Further, in accordance with the invention, Co.sub.3O.sub.4 particles could be formed that can be used as a precursor to obtain LiCoO.sub.2 particles with a high density and good electrochemical quality. Further, in accordance with the invention, Co.sub.3O.sub.4 particles could be formed that can be used as a precursor to obtain LiCoO.sub.2 particles with a high density and good electrochemical quality, and with a low risk of a pressure buildup in a cell.

(35) One or more dopants from the group of Mg, Ca, Sr, Ti, Zr, B, Al, and F can be added in the LiCoO.sub.2 particles. The dopants can be added in one or more steps including the precipitation step, the calcination step, the lithiation step and a separate step after or prior the lithiation. These steps comprise following: Precipitation step: dopants are precipitated with Co(OH).sub.2 into or on the particles to form doped Co(OH).sub.2. Calcination step: dopants mixed with Co(OH).sub.2 and calcinated to form doped Co.sub.3O.sub.4. Lithiation step: dopants mixed with Li-source and/or Co-source and calcinated all together to form doped LiCoO.sub.2. Separate step: dopants added prior or after lithiation. Prior lithiation step: dopants are mixed with Co-source including some heat treatment. After lithiation step: dopants are mixed with LiCoO.sub.2 including some heat treatment.

(36) Adding dopants into LiCoO.sub.2 have been illustrated these steps are illustrated In the example 8 and reference example dopants have been added in lithiation step.

(37) The concentration of the dopants is preferably in the range of 0.05-5 mol-% from Co. In general, dopants are important for the performance of a cathode material in LIB. Dopants are added for example to improve thermal and high voltage stability as well as to minimize the capacity fade of the cathode material. Usually, physical properties, for example tap density, of the cathode materials are deteriorated when dopants are added. In one embodiment of the invention, the tap density of the doped LiCoO.sub.2 particles was decreased by maximum of 5% compared to that of the non-doped particles.

EXAMPLES

(38) The following examples illustrate the preparation and the properties of the Co(OH).sub.2 particles, Co.sub.3O.sub.4 particles and LiCoO.sub.2 particles in accordance with the invention, but these examples are not considered to be limiting the scope of this invention.

Example 1

Preparation of Co(OH)2 Particles Comprising Essentially Octahedral Shape Particles

(39) Co(OH).sub.2 particles were precipitated in a 150 liter reactor by pumping cobalt chloride solution (80 g/l), ammonium hydroxide solution (220 g/l) and sodium hydroxide solution (220 g/l) into it. Feed rates of sodium hydroxide and ammonium hydroxide solutions were controlled in order to keep pH in the level of 10.0-12.5 to precipitate all cobalt ions from the solution. A ratio of the feed rates between sodium hydroxide and ammonium hydroxide was in the range of 2-4. Temperature was kept constant at 40 C. Mixing in the reactor was controlled (80 rpm). The precipitated particles were collected sequentially as an overflow. The precipitated particles were filtered, washed with hot ion exchanged water and dried at 110 C. in air.

(40) Well crystallized -Co(OH).sub.2 phase with the P3m1 space group was observed by X-ray powder diffraction (XRD) (FIG. 1). Impurity phases were not observed. Co-% of 62.9%, determined by a potentiometric titration method, gave further proof about the formation of the pure Co(OH).sub.2 without impurities. The SEM figure shows that the formed Co(OH).sub.2 particles were dense with smooth surface structure and the particles were comprising essentially octahedral shape particles (FIG. 2). The average particle size of the formed Co(OH).sub.2 particles D50 was 15.7 m with D10 and D90 values of 5.7 m and 31.7 m, respectively. Tap density (Tde) of the formed Co(OH).sub.2 particles was high 2.29 g/cm.sup.3 and surface area (SA) low 1.5 m.sup.2/g. The particles formed in this example are used as a precursor in the latter examples.

Example 2

Preparation of Co3O4 Particles Comprising Essentially Octahedral Shape Particles

(41) Co.sub.3O.sub.4 particles were prepared by the method presented in the Example 1, but further calcinating the formed Co(OH).sub.2 particles comprising essentially octahedral shape particles at 700 C. for 2 h in air. This example shows that morphology and physical properties of the Co(OH).sub.2 particles comprising essentially octahedral shape particles can strongly affect on the morphology and physical properties of the Co.sub.3O.sub.4 particles formed by the calcination process.

(42) Co.sub.3O.sub.4 particles with the spinel crystal structure (Fd3m space group) were formed by the calcination process. Co-% of 74.2% gave further proof about the transformation of the Co(OH).sub.2 phase to the Co.sub.3O.sub.4 phase. Insignificant sintration of the particles occurred during the calcination, since the morphology and the physical properties of the particles remained essentially the same after the calcination. This can be observed from the following data. The SEM figure shows that the Co.sub.3O.sub.4 particles were comprising essentially octahedral shape particles (FIG. 3). The D50, D10 and D90 values were 15.5 m, 5.4 m and 31.1 m, respectively. Tde was 2.26 g/cm.sup.3 and SA 1.6 m.sup.2/g. The above values are essentially the same as those of the Example 1 values (Table 1). The particles formed in this example are used as a precursor in the latter examples.

Example 3

Preparation of Co3O4 Particles with Modified Morphology from Co(OH)2 Particles Comprising Essentially Octahedral Shape Particles

(43) Co.sub.3O.sub.4 particles were prepared by the method presented in the Example 1, but further calcinating formed Co(OH).sub.2 particles comprising essentially octahedral shape particles at 900 C. for 2 h in air. This example shows that morphology and physical properties of Co.sub.3O.sub.4 particles formed by the calcination process can be modified by the process conditions.

(44) Co.sub.3O.sub.4 particles with the spinel crystal structure (Fd3m space group) were formed by the calcination process. Co-% of 74.2% gave further proof about the transformation of the Co(OH).sub.2 phase to the Co.sub.3O.sub.4 phase. Sintration of the particles occurred during the calcination, since the particles morphology and physical properties were changed by the calcination process. This can be observed from the following data. The SEM figure shows that the Co.sub.3O.sub.4 particles were comprising irregular shape particles without essentially octahedral shape particles (FIG. 4). The D50, D10 and D90 values were 14.4 m, 6.4 m and 26.0 m, respectively. Tde was 2.56 g/cm.sup.3 and SA 0.55 m.sup.2/g. The particle size distribution is narrower, Tde higher and SA lower compared to those of the Example 1 and Example 2 values (Table 1). The particles formed in this example are used as a precursor in the latter examples.

Example 4

Preparation of LiCoO2 Particles Comprising Essentially Octahedral Shape Particles from Example 1 Co(OH)2 Particles

(45) Co(OH).sub.2 particles, prepared by the method presented in the Example 1, were intimately mixed with Li.sub.2CO.sub.3 particles with the Li/Co molar-ratio of 1.00. The obtained mixture was further calcinated at 1000 C. for 5 h in air. This calcination process is called as a lithiation process. This example shows that morphology and physical properties of the Co(OH).sub.2 particles comprising essentially octahedral shape particles can strongly affect on the morphology and physical properties of the LiCoO.sub.2 particles formed by the lithiation process.

(46) LiCoO.sub.2 particles with the layered crystal structure (R3m space group) were formed by the lithiation process (FIG. 5). No traces of Co(OH).sub.2 or Co.sub.3O.sub.4 were observed. Co-% and Li-% (Li determined by atomic absorption spectroscopy) were 59.7% and 7.0%, respectively, that further proves the formation of the LiCoO.sub.2 particles. The morphology of the particles remained essentially the same after the lithiation. The physical properties of the particles were slightly modified by the lithiation process. These can be observed from the following data. The SEM figure shows that the formed LiCoO.sub.2 particles were comprising essentially octahedral shape particles (FIG. 6). The D50, D10 and D90 values were 13.8 m, 5.9 m and 25.9 m, respectively. Tde was 2.88 g/cm.sup.3 and SA 0.41 m.sup.2/g. The above results show the narrowed particle size distribution and densification of the particles due to the lithiation when compared to those of Example 1 values (Table 1).

(47) pH and free Li.sub.2CO.sub.3 were determined as described in the description of the invention. Both of pH and free Li.sub.2CO.sub.3 give indication about the amount of gaseous components in the cell. pH and free Li.sub.2CO.sub.3 of formed LiCoO.sub.2 particles were 9.66 and 0.017%. Both of the values are low indicating a low risk of pressure buildup in the cell comprised of the LiCoO.sub.2 particles containing essentially octahedral shape particles.

(48) The coin cell testing was performed as described in the description of the invention. The coin-cell test showed the high initial charge capacity (155.0 mAh/g), good rate capability (96.5%) and good cyclability (90.1%, 5-30; 74.6%, 5-60). These results indicate that LiCoO.sub.2 particles comprising essentially octahedral shape particles have a good electrochemical quality as a cathode material for LIB.

Example 5

Preparation of LiCoO2 Particles with Modified Morphology from Example 1 Co(OH)2 Particles

(49) Co(OH).sub.2 particles, prepared by the method presented in the Example 1, were intimately mixed with Li.sub.2CO.sub.3 particles with the Li/Co molar-ratio of 1.04. The obtained mixture was further calcinated at 1050 C. for 5 h in air. This example shows that morphology and physical properties of LiCoO.sub.2 particles formed by the lithiation process can be modified by the process conditions, but the formed particles have still good performance as a cathode material.

(50) LiCoO.sub.2 particles with the layered crystal structure (R3m space group) were formed by the lithiation process. No traces of Co(OH).sub.2 or Co.sub.3O.sub.4 were observed. Co-% and Li-% were 59.3% and 7.3%, respectively, that further proves the formation of the LiCoO.sub.2 particles. The morphology and physical properties of the particles were modified by the lithiation process. This can be observed from the following data. The SEM figure shows that the LiCoO.sub.2 particles were comprising irregular shape particles without essentially octahedral shape particles (FIG. 7). The D50, D10 and D90 values were 14.7 m, 8.4 m and 26.6 m, respectively. Tde was 2.78 g/cm.sup.3 and SA 0.16 m.sup.2/g. The above results show the narrowed particle size distribution and densification of the particles when compared to those of the Example 1 hydroxide values, but increased particle size with less dense particles when compared to those of the Example 4 LiCoO.sub.2 values (Table 1).

(51) pH and free Li.sub.2CO.sub.3 were 9.63 and 0.024%, respectively. Both of the values are low indicating a low risk of pressure buildup in the cell. The coin cell testing was performed as described in the description of the invention. The coin-cell test showed the high initial charge capacity (157.8 mAh/g) and moderate rate capability (89.5%). These results indicate that LiCoO.sub.2 particles prepared from Co(OH).sub.2 particles comprising essentially octahedral shape particles have a good electrochemical quality as a cathode material for LIB.

Example 6

Preparation of LiCoO2 Particles with Modified Morphology from Example 2 Co3O4 Particles

(52) Co.sub.3O.sub.4 particles, prepared by the method presented in the Example 2, were intimately mixed with Li.sub.2CO.sub.3 particles with the Li/Co molar-ratio of 1.00. The obtained mixture was further calcinated at 1000 C. for 5 h in air. This example shows that morphology and physical properties of LiCoO.sub.2 particles formed by the lithiation process can be modified by the process conditions, but the formed particles have still good performance as a cathode material.

(53) LiCoO.sub.2 particles with the layered crystal structure (R3m space group) were formed by the lithiation process. No traces of Co.sub.3O.sub.4 were observed. Co-% and Li-% were 59.7% and 7.0%, respectively, that further proves the formation of the LiCoO.sub.2 particles. The morphology and physical properties of the particles were modified by the lithiation process. This can be observed from the following data. The SEM figure shows that the LiCoO.sub.2 particles were comprising irregular shape particles without essentially octahedral shape particles (FIG. 8). The D50, D10 and D90 values were 18.5 m, 7.5 m and 38.1 m, respectively. Tde was 3.01 g/cm.sup.3 and SA 0.21 m.sup.2/g. The above results show the increased particle size and densification of the particles when compared to those of the Example 2 oxide values as well as to those of the Example 4 LiCoO.sub.2 values (Table 1).

(54) pH and free Li.sub.2CO.sub.3 were 9.83 and 0.046%, respectively. The values are higher than those of the Example 4 values, but still low indicating a low risk of pressure buildup in the cell. The coin cell testing was performed as described in the description of the invention. The coin-cell test showed the high initial charge capacity (156.8 mAh/g) and moderate rate capability (88.2%). These results indicate that LiCoO.sub.2 particles prepared from Co.sub.3O.sub.4 particles comprising essentially octahedral shape particles have a good electrochemical quality as a cathode material for LIB.

Example 7

Preparation of LiCoO2 Particles with Modified Morphology from Example 3 Co3O4 Particles

(55) Co.sub.3O.sub.4 particles, prepared by the method presented in the Example 3, were intimately mixed with Li.sub.2CO.sub.3 particles with the Li/Co molar-ratio of 0.98. The obtained mixture was further calcinated at 1000 C. for 5 h in air. This example shows that morphology and physical properties of LiCoO.sub.2 particles formed by the lithiation process can be modified by the process conditions, but have still good performance as a cathode material.

(56) LiCoO.sub.2 particles with the layered crystal structure (R3m space group) were formed by the lithiation process. No traces of Co.sub.3O.sub.4 were observed. Co-% and Li-% were 60.0% and 6.9%, respectively, that further proves the formation of the LiCoO.sub.2 particles. The morphology and physical properties of the particles were modified by the lithiation process. This can be observed from the following data. The SEM figure shows that the LiCoO.sub.2 particles were comprising irregular shape particles without essentially octahedral shape particles (FIG. 9). The D50, D10 and D90 values were 17.7 m, 7.7 m and 32.7 m, respectively. Tde was 2.94 g/cm.sup.3 and SA 0.27 m.sup.2/g. The above results show the increased particle size and densification of the particles when compared to those of the Example 3 oxide values as well as those of the Example 4 LiCoO.sub.2 values (Table 1).

(57) pH and free Li.sub.2CO.sub.3 were 9.90 and 0.061%, respectively. The values are higher than those of the Example 4 values, but still low indicating a low risk of pressure buildup in the cell. The coin cell testing was performed described in the description of the invention. The coin-cell test showed the high initial charge capacity (154.9 mAh/g) and moderate rate capability (87.4%). These results indicate that LiCoO.sub.2 particles whose preparation method includes Co(OH).sub.2 particles comprising essentially octahedral shape particles have a good electrochemical quality as a cathode material for LIB.

Example 8

Preparation of Doped LiCoO2 Particles Comprising Essentially Octahedral Shape Particles from Example 1 Co(OH)2

(58) Doped LiCoO.sub.2 particles were prepared by the method presented in the Example 4, but 0.2 mol-% of dopants (Mg, Al, Ti, Zr, B, Al+Ti, Mg+Al, Al+Zr, F, Ca, Sr) were intimately mixed with Co(OH).sub.2 particles prior the mixing with Li.sub.2CO.sub.3. The dopants were added as oxides except F as LiF and Ca as well as Sr as hydroxides. This example shows that morphology and physical properties of the LiCoO.sub.2 particles comprising essentially octahedral shape particles remain essentially the same even if the dopants are added.

(59) Doped LiCoO.sub.2 particles with the layered crystal structure (R3m space group) were formed by the lithiation process. No traces of Co(OH).sub.2 or Co.sub.3O.sub.4 were observed. The SEM figure shows that the LiCoO.sub.2 particles were comprising essentially octahedral shape particles (FIG. 10). Density of the doped LiCoO.sub.2 particles was only slightly lower than that of the Example 4 non-doped LiCoO.sub.2 particles. Tde of the doped particles was decreased by maximum of 5% compared to that of the non-doped particles (FIG. 11). These results indicate that one or more dopants can be easily added to LiCoO.sub.2 particles comprising essentially octahedral shape particles.

(60) The following comparative examples show the preparation and properties of typical prior art products.

Comparative Example 1

Preparation of Comparative Co(OH)2 Particles without Octahedral Shape Particles

(61) Co(OH).sub.2 particles were precipitated in 150 liter reactor by pumping cobalt sulphate solution (80 g/l), ammonium hydroxide solution (220 g/l) and sodium hydroxide solution (220 g/l) into it. Feed rates of sodium hydroxide and ammonium hydroxide solutions were controlled in order to keep pH in the level of 10.0-12.5 to precipitate all cobalt ions from the solution. A ratio of the feed rates between sodium hydroxide and ammonium hydroxide was in the range of 3-5. Temperature was kept constant at 65 C. Mixing in the reactor was controlled (240 rpm). The precipitated particles were collected sequentially as an overflow. The precipitated particles were filtered, washed with hot ion exchanged water and dried at 110 C. in air. This comparative example shows Co(OH).sub.2 particles that can be considered as typical particles in the field.

(62) Well crystallized -Co(OH).sub.2 phase with the P3m1 space group was observed by X-ray powder diffraction (XRD) (FIG. 12). Impurity phases were not observed. Co-% was 62.7% giving further proof about the formation of the pure Co(OH).sub.2 without impurities. Morphology and the physical properties of the formed Co(OH).sub.2 particles were clearly different compared to those of the Example 1 ones. The SEM figure shows that the formed Co(OH).sub.2 particles were not dense, had voids in the surface, and the particles were comprising irregular particles without octahedral shape particles (FIG. 13). The D50, D10 and D90 values were 11.0 m, 1.1 m and 20.5 m, respectively. Tde was 1.53 g/cm.sup.3 and SA 2.4 m.sup.2/g. The particle size of the formed particles is smaller, Tde is lower and SA is higher compared to those of the Example 1 values (Table 1). These results indicate that the properties of the Co(OH).sub.2 particles are superior when the essentially octahedral shape particles are formed as described in the Example 1. Benefits are further shown in the examples, where LiCoO.sub.2 particles are prepared from the Co(OH).sub.2 particles.

Comparative Example 2

Preparation of Comparative Co3O4 Particles without Octahedral Shape Particles

(63) Co.sub.3O.sub.4 particles were prepared by the method presented in the Comparative example 1, but further calcinating formed Co(OH).sub.2 particles at 900 C. for 2 h in air. This comparative example shows Co.sub.3O.sub.4 particles that can be considered as typical particles in the field.

(64) Co.sub.3O.sub.4 particles with the spinel crystal structure (Fd3m space group) were formed. Co-% of 73.2% gave further proof about the transformation of the Co(OH).sub.2 phase to the Co.sub.3O.sub.4 phase. Insignificant sintration of the particles occurred during the calcination, since the morphology and the physical properties of the particles remained essentially the same after the calcination. This can be observed from the following data. The SEM figure shows that the formed Co.sub.3O.sub.4 particles were not dense, had voids in the surface, and the particles were comprising irregular particles without octahedral shape particles (FIG. 14). The D50, D10 and D90 values were 11.9 m, 2.3 m and 20.7 m, respectively. Tde was 1.64 g/cm.sup.3 and SA 2.2 m.sup.2/g. The above values are essentially the same as those of the Comparative example 1 values, but the formed particles are smaller, Tde is lower and SA is higher compared to those of the Example 2 and Example 3 values (Table 1). These results indicate that the properties of the Co.sub.3O.sub.4 particles are superior when the essentially octahedral shape particles are formed as described in the Examples 2 and 3. Benefits are further shown in the examples, where LiCoO.sub.2 particles are prepared from the Co.sub.3O.sub.4 particles.

Comparative Example 3

Preparation of Comparative LiCoO2 Particles without Octahedral Shape Particles from Comparative Example 1 Co(OH)2 Particles

(65) Co(OH).sub.2 particles, prepared by the method presented in the Comparative example 1, were intimately mixed with Li.sub.2CO.sub.3 particles with the Li/Co molar-ratio of 1.00. The obtained mixture was further calcinated at 1000 C. for 5 h in air. This comparative example shows LiCoO.sub.2 particles prepared using the same Li/Co ratio and same temperature as in the Example 4, but from Co(OH).sub.2 particles without octahedral shape particles.

(66) LiCoO.sub.2 particles with the layered crystal structure (R3m space group) were formed by the lithiation process. No traces of Co(OH).sub.2 or Co.sub.3O.sub.4 were observed. Co-% and Li-% were 59.7% and 7.1%, respectively, that further proves the formation of the LiCoO.sub.2 particles. The morphology and physical properties of the particles were modified by the lithiation process. These can be observed from the following data. The SEM figure shows that the LiCoO.sub.2 particles were comprising irregular shape particles without essentially octahedral shape particles (FIG. 15). The D50, D10 and D90 values were 12.3 m, 3.6 m and 21.5 m, respectively. Tde was 2.53 g/cm.sup.3 and SA 0.57 m.sup.2/g. The above results show the increased particle size and densification of the particles when compared to those of the Comparative Example 1 Co(OH).sub.2 values, but particles are clearly less dense when compared to those of the Examples 4-7 LiCoO.sub.2 values (Table 1). The latter is clear indication of the benefit of LiCoO.sub.2 particles comprising essentially octahedral shape particles as well as LiCoO.sub.2 particles whose preparation method includes Co(OH).sub.2 particles comprising essentially octahedral shape particles.

(67) pH and free Li.sub.2CO.sub.3 were 9.77 and 0.028%, respectively. The values are higher than those of the Example 4 values, but still low indicating a low risk of pressure buildup in the cell. The coin-cell test showed the moderate initial charge capacity (154.1 mAh/g), good rate capability (96.6%) and moderate cyclability (88.9%, 5-30; 75.8%, 5-60). These values are slightly lower than those of the Example 4 values indicating good but slightly decreased electrochemical quality.

(68) This comparative example together with Examples 4-7 showed that electrochemically good quality LiCoO.sub.2 particles without octahedral shape particles can be prepared with the low Li/Co metal ratio, but the density of the particles is remaining at very low level. LiCoO.sub.2 particles comprising essentially octahedral shape particles as well as LiCoO.sub.2 particles whose preparation method includes Co(OH).sub.2 particles comprising essentially octahedral shape particles offer the option of having both properties, high density and electrochemically good quality, in the particles.

Comparative Example 4

Preparation of Comparative LiCoO2 Particles without Octahedral Shape Particles from Comparative Example 2 Co3O4 Particles

(69) Co.sub.3O.sub.4 particles, prepared by the method presented in the Comparative example 2, were intimately mixed with Li.sub.2CO.sub.3 particles with the Li/Co molar-ratio of 1.00. The obtained mixture was further calcinated at 1000 C. for 5 h in air. This comparative example shows LiCoO.sub.2 particles prepared using the same Li/Co ratio and same temperature as in the Example 4, but from Co.sub.3O.sub.4 particles without octahedral shape particles.

(70) LiCoO.sub.2 particles with the layered crystal structure (R3m space group) were formed by the lithiation process. No traces of Co.sub.3O.sub.4 were observed. Co-% and Li-% were 59.8% and 7.0%, respectively, that further proves the formation of the LiCoO.sub.2 particles. The morphology and physical properties of the particles were modified by the lithiation process. This can be observed from the following data. The SEM figure shows that the LiCoO.sub.2 particles were comprising irregular shape particles without essentially octahedral shape particles (FIG. 16). The D50, D10 and D90 values were 12.1 m, 4.8 m and 21.3 m, respectively. Tde was 2.61 g/cm.sup.3 and SA 0.32 m.sup.2/g. The above results show the increased particle size and densification of the particles when compared to those of the Comparative example 2 Co.sub.3O.sub.4 values, but particles are clearly less dense when compared to those of the Examples 4-7 LiCoO.sub.2 values (Table 1). The latter is clear indication of the benefit of LiCoO.sub.2 particles comprising essentially octahedral shape particles as well as LiCoO.sub.2 particles whose preparation method includes Co(OH).sub.2 particles comprising essentially octahedral shape particles.

(71) pH and free Li.sub.2CO.sub.3 were 9.56 and 0.013%, respectively. The values are lower when compared to those of the Example 4-7 values indicating a low risk of pressure buildup in the cell. The coin-cell test showed the moderate initial charge capacity (154.1 mAh/g), good rate capability (97.5%) and moderate cyclability (88.7%, 5-30). These values are slightly lower than those of the Example 4 values indicating good but slightly decreased electrochemical quality.

(72) This comparative example together with Examples 4-7 showed that electrochemically good quality LiCoO.sub.2 particles without octahedral shape particles can be prepared with the low Li/Co metal ratio of 1.00, but the density of the particles is remaining at very low level. LiCoO.sub.2 particles comprising essentially octahedral shape particles as well as LiCoO.sub.2 particles whose preparation method includes Co(OH).sub.2 particles comprising essentially octahedral shape particles offer the option of having both properties, high density and electrochemically good quality, in the particles.

Comparative Example 5

Preparation of Comparative LiCoO2 Particles without Octahedral Shape Particles from Comparative Example 2 Co3O4 Particles Via Milling Step

(73) Co.sub.3O.sub.4 particles, prepared by the method presented in the Comparative example 2, were milled by a jet mill to obtain D50 of 1.4 m. The milled Co.sub.3O.sub.4 particles were intimately mixed with Li.sub.2CO.sub.3 particles with the Li/Co molar-ratio of 1.05. The obtained mixture was further calcinated at 1000 C. for 5 h in air. This comparative example shows LiCoO.sub.2 particles prepared by the method where LiCoO.sub.2 particles are grown with the aid of excess amount of Li and small particle size Co.sub.3O.sub.4.

(74) LiCoO.sub.2 particles with the layered crystal structure (R3m space group) were formed by the lithiation process. No traces of Co.sub.3O.sub.4 were observed. Co-% and Li-% were 58.2% and 7.0%, respectively, that further proves the formation of the LiCoO.sub.2 particles. The morphology and physical properties of the particles were modified by the lithiation process. This can be observed from the following data. The SEM figure shows that the LiCoO.sub.2 particles were comprising irregular shape particles without essentially octahedral shape particles (FIG. 17). The D50, D10 and D90 values were 9.9 m, 5.2 m and 18.5 m, respectively. Tde was 2.86 g/cm.sup.3 and SA 0.33 m.sup.2/g. The above results show that particles are smaller, but only slightly less dense when compared to those of the Examples 4-7 LiCoO.sub.2 values (Table 1).

(75) pH and free Li.sub.2CO.sub.3 were 9.96 and 0.063%, respectively. The values are higher when compared to those of the Example 4-7 values, indicating an increased risk of pressure buildup in the cell. The coin-cell test showed the moderate initial charge capacity (153.6 mAh/g), moderate rate capability (90.8%) and moderate cyclability (88.3%, 5-30; 57.4%, 5-60). These values are lower than those of the Example 4 values indicating moderate electrochemical quality.

(76) This comparative example together with Examples 4-7 showed that high density LiCoO.sub.2 particles without octahedral shape particles can be prepared with the high Li/Co metal ratio, but the electrochemically quality of the particles is deteriorated and risk of pressure buildup in the cell is increased. LiCoO.sub.2 particles comprising essentially octahedral shape particles as well as LiCoO.sub.2 particles whose preparation method includes Co(OH).sub.2 particles comprising essentially octahedral shape particles offer the option of having all properties, high density and electrochemically good quality in the particles as well as low risk of pressure buildup in the cell.

Comparative Example 6

Preparation of Doped LiCoO2 Particles without Essentially Octahedral Shape Particles

(77) Doped LiCoO.sub.2 particles were prepared by the method presented in the Comparative example 4, but 0.2 mol-% of dopants (Mg, Al, Ti, Zr, B, Al+Ti) were intimately mixed with Co.sub.3O.sub.4 particles prior the mixing with Li.sub.2CO.sub.3. The dopants were added as oxides. This example shows that physical properties of the LiCoO.sub.2 particles without essentially octahedral shape particles are deteriorated when the dopants are added.

(78) Doped LiCoO.sub.2 particles with the layered crystal structure (R3m space group) were formed by the lithiation process. No traces of Co.sub.3O.sub.4 were observed. Density of the doped LiCoO.sub.2 particles was clearly lower than that of the Comparative example 4 non-doped LiCoO.sub.2 particles. Tde of the doped particles was decreased by more than 5% compared to that of the non-doped particles (FIG. 18) that is much more dramatic drop than in FIG. 11 where LiCoO.sub.2 particles are comprising essentially octahedral shape particles. This comparative example together with Example 8 indicate that one or more dopants can be added more easily to LiCoO.sub.2 particles comprising essentially octahedral shape particles compared to those of LiCoO.sub.2 particles without essentially octahedral shape particles. This is one more benefit for LiCoO.sub.2 particles comprising essentially octahedral shape particles.

(79) TABLE-US-00001 TABLE 1 Summary of data presented in examples. Initial discharge Rate Cyclability Free capacity capability (5-30, 5-60) Material D10/m D50/m D90/m Tde/g/cm.sup.3 SA/m.sup.2/g Co-% Li-% pH Li.sub.2CO.sub.3-% mAh/g % % Ex. 1 5.7 15.7 31.7 2.29 1.5 62.9 Ex. 2 5.4 15.5 31.1 2.26 1.6 74.2 Ex. 3 6.4 14.4 26.0 2.56 0.55 73.3 Co. ex. 1 1.1 11.0 20.5 1.53 2.4 62.7 Co. ex. 2 2.3 11.9 20.7 1.64 2.2 73.2 Ex. 4 5.9 13.8 25.9 2.88 0.41 59.7 7.0 9.66 0.017 155.0 96.5 90.1, 74.6 Ex. 5 8.4 14.7 26.6 2.78 0.16 59.3 7.3 9.63 0.024 157.8 89.5 Ex. 6 7.5 18.5 38.1 3.01 0.21 59.7 7.0 9.83 0.046 156.8 88.2 Ex. 7 7.7 17.7 32.7 2.94 0.27 60.0 6.9 9.90 0.061 154.9 87.4 Co. ex. 3 3.6 12.3 21.5 2.53 0.57 59.7 7.1 9.77 0.028 154.1 96.6 88.9, 75.8 Co. ex. 4 4.8 12.1 21.3 2.61 0.32 59.8 7.0 9.56 0.013 154.1 97.5 88.7, Co. ex. 5 5.2 9.9 18.5 2.86 0.33 58.2 7.0 9.96 0.063 153.6 90.8 88.3, 57.4
Based on table 1, which illustrates the properties of LiCoO.sub.2 material prepared using prior art processes (Comparison examples 1-6), and LiCoO.sub.2 prepared according to the method of the present invention (examples 1-7), the following can be surmised:
It is important that LiCoO.sub.2 material of the invention have at least two properties selected from the following three properties (i)-(iii): (i) free Li.sub.2CO.sub.3% of the LiCoO.sub.2 material is <0.05, (ii) the initial discharge capacity (mAh/g) of the LiCoO.sub.2 material is >154.5 and (iii) Tde (high density, g/cm.sup.3) of the LiCoO.sub.2 material is >2.7.

DISCLAIMER

(80) Based upon the foregoing disclosure, it should now be apparent that the Co(OH).sub.2 particles, the Co.sub.3O.sub.4 particles and the LiCoO.sub.2 particles and the preparation such particles as described herein will carry out the embodiments set forth hereinabove. It is, therefore, to be understood that any variations evident fall within the scope of the claimed invention and thus, the selection of specific component elements can be determined without departing from the spirit of the invention herein disclosed and described.