CN103682326A - A high-capacity lithium cobaltate-based lithium-ion battery positive electrode material and preparation method thereof - Google Patents

Abstract

This invention discloses a high-capacity lithium cobalt oxide-based lithium-ion battery cathode material. The material is obtained by mixing modified lithium cobalt oxide particles of different sizes and then coating them to obtain the finished lithium cobalt oxide product. It contains a cobalt source material, a lithium source material, a dopant, and a coating material. The molar ratio of Li to Co is 0.95–1.2, the dopant dosage is 0.01–10 wt%, and the coating material dosage is 0.01–20 wt%. This invention improves the capacity of the lithium cobalt oxide material by mixing lithium cobalt oxide particles of different sizes, and enhances the material's stability, safety, and electrochemical performance, especially its high-temperature cycling performance, under high voltage conditions greater than 4.2V through doping and coating.

Description

A high-capacity lithium cobaltate-based lithium-ion battery positive electrode material and preparation method thereof

technical field

The invention relates to a lithium ion battery cathode material and its preparation, in particular to a high-capacity lithium cobaltate-based lithium ion battery cathode material and a preparation method thereof.

Background technique

With the rapid development of electronic technology and the continuous upgrading of electronic products, the requirements for the energy density of batteries are also getting higher and higher. At present, the charging voltage of the conventionally used small lithium-ion battery is 4.2V. The smart high-end electronic products represented by the American Apple Company and the South Korean Samsung Company have updated the batteries used in their own products to increase the battery voltage to 4.3V. , 4.35V or higher high-voltage batteries. Increasing the charging voltage of the battery can significantly increase the capacity of the battery without increasing the active material in the battery. It is one of the effective ways to increase the energy density of the battery, and it is of great significance to meet the high energy density and battery life requirements of high-end portable devices. Therefore, domestic battery materials are developing towards high voltage.

Lithium cobalt oxide is widely used due to its advantages of high working voltage, high energy density, easy synthesis and fast charge and discharge. However, lithium cobalt oxide itself has structural defects. When the charging cut-off voltage of the lithium-ion battery is higher than 4.2V, a large amount of Co ³⁺ in the lithium cobalt oxide structure will become Co ⁴⁺ , and the existence of Co ⁴⁺ will cause cobalt acid The formation of oxygen defects in the lithium crystal form weakens the binding force between the transition metal Co and oxygen, making Co ⁴⁺ dissolve in the electrolyte, destroying the crystal structure of the positive electrode material lithium cobalt oxide, and rapidly reducing the specific capacity of the battery. Cycle performance deteriorates. Therefore, it is first necessary to solve the structural stability of lithium cobalt oxide under high voltage.

There are other ways to increase the capacity of lithium-ion secondary batteries: (a) Chinese patent CN 1665052A increases the compaction density of the material by mixing lithium cobaltate with different particle sizes, thereby increasing the capacity per unit volume to achieve high capacity, Because of its small particle size, it brings safety hazards to the battery; (b) Chinese patent CN 101436666A proposes to prepare large-grained lithium cobaltate materials first, and then use cobalt carbonate and lithium carbonate on the surface of large lithium cobaltate particles. particles, so that small particles of lithium cobaltate particles adhere to the surface of large particles, thereby increasing the tap density and volume specific capacity of the positive electrode material, but the crystallinity of lithium cobaltate sintered once is not good, which will affect the cycle performance of the battery (c) Chinese patent CN 102779976A proposes to mix lithium cobalt oxides of different sizes, and then undergo doping, sintering, coating, sintering and other processes to improve compaction density and safety performance. But its process is complicated, which increases the production cost.

In view of this, it is necessary to develop a high-capacity lithium cobalt oxide material, which not only has a high working voltage and energy density, but also has high stability and safety when the charging cut-off voltage of the lithium-ion battery is higher than 4.2V. And excellent electrochemical performance, especially high-temperature cycle performance, so as to meet the current market demand.

Contents of the invention

Purpose of the invention: The purpose of the invention is to make up for the deficiencies of the prior art, and to provide a high-capacity lithium cobaltate-based lithium-ion battery positive electrode material with good safety performance and good electrochemical performance and a preparation method thereof.

The technical scheme adopted in the present invention:

A high-capacity lithium cobaltate-based lithium-ion battery positive electrode material, the high-capacity lithium cobaltate-based lithium-ion battery positive electrode material mixes large and small modified lithium cobaltate with different particle sizes, and then coats it to obtain cobalt Lithium acid finished product, the positive electrode material contains cobalt source material, lithium source material, dopant M, dopant M' and coating material N, wherein the molar ratio of Li:Co is 0.95-1.2, and the dopant M The dosage of dopant M' and dopant M' are both 0.01-10 wt%, and the dosage of cladding material N is 0.01-20 wt%.

A method for preparing a high-capacity lithium cobaltate-based lithium-ion battery cathode material according to the present invention specifically comprises the following steps:

(1) Prepare large particle size lithium cobalt oxide material A, D50 is 8-30 μm, the preparation method adopted is: mix cobalt source material, lithium source material and dopant M according to a certain ratio, and the mixing method is dry Mixing or wet mixing, wherein the molar ratio of Li and Co is 0.95 to 1.2, and the doping amount of the dopant M is 0.01 to 10 wt% (the mass percentage of the amount of material added in the present invention, unless otherwise specified, Both are relative to the quality of the lithium cobalt oxide substrate); the uniformly mixed materials are sintered, the main temperature of the sintering is controlled at 600 ° C ~ 1350 ° C, the sintering time of the main temperature zone is 5 ~ 40 h, the whole sintering process is in It is carried out in an air or oxygen atmosphere, and the ventilation rate is controlled within the range of 2 to 30 m ³ /h. The sintered materials are processed by crushing, crushing, grading, sieving and other processes to obtain the required semi-finished product A of lithium cobaltate.

(2) Prepare small particle size lithium cobalt oxide material B, D50 is 1-8 μm, the preparation method adopted is: mix cobalt source material, lithium source material and dopant M′ according to a certain proportion, and the mixing method is dry Formula mixing or wet mixing, wherein the molar ratio of Li and Co is 0.95-1.2, and the dosage of dopant M' is 0.01-10 wt%; the uniformly mixed materials are sintered, and the main temperature of sintering is controlled at 300°C-1000°C ℃, the sintering time in the main temperature zone is 4-35 h, the whole sintering process is carried out in air or oxygen atmosphere, the ventilation volume control range is 2-30 m ³ /h, and the sintered materials are crushed, pulverized, classified, Processes such as sieving are processed to obtain the required semi-finished product B of lithium cobaltate.

(3) Mix the two materials A and B according to a certain ratio. When the large particle size lithium cobaltate A is used as the main body, the dosage of the small particle size lithium cobaltate B is 0 to 50 wt%, and its mass is 100%. The component content is the mass percentage relative to the large particle size lithium cobaltate A. When the small particle size content is greater than 50%, the mass ratio of A:B is 1:2～2:1, and the materials C and D50 are obtained after mixing evenly 5-25 μm.

(4) The material C is coated, the coating material is N, and the amount of N is 0.01-20 wt%. The coating method used is wet coating, dry coating or co-precipitation method.

(5) The coated material C is sintered, the main temperature of sintering is controlled at 400-1250°C, and the sintering time of the main temperature is 4-36 h. The whole sintering process is carried out in an air or oxygen atmosphere. The ^sintered material is crushed, pulverized, classified, sieved, iron-removed and other processes to obtain the required lithium cobalt oxide finished product.

The cobalt source material involved in the step (1) and step (2) is selected from one or more mixtures of tricobalt tetroxide, cobalt oxyhydroxide, cobalt hydroxide, cobalt carbonate, cobalt oxalate and cobalt oxide, and the D50 is 0.2 ~30 μm.

The lithium source material involved in the step (1) and step (2) is selected from one or more of lithium hydroxide, lithium carbonate, and lithium oxalate.

The dopant M in the step (1) and the dopant M' in the step (2) are selected from the first transition elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu , Zn), second transition elements (Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd), alkaline earth elements (Be, Mg, Ca, Sr, Ba) and rare earth elements (La, Sm , Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) oxides, halides, hydroxides, metal organics, nitrates, sulfates, carbonates, oxalate phosphates, silicon One or more mixtures of acid salts, citrates, or composite oxides with other metal elements.

The cladding material N in the step (4) is selected from the first transition elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn), the second transition elements (Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd), alkaline earth elements (Be, Mg, Ca, Sr, Ba) and rare earth elements (La, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) oxides, halides, hydroxides, organometallics, nitrates, sulfates, carbonates, oxalate phosphates, silicates, citrates or composite oxidations with other metal elements One or more mixtures of substances.

The cladding material N in the step (4) is a metal compound of element F or a mixture of a metal compound of element F and one or more substances mentioned in the dopant M mentioned above.

Beneficial effects: Compared with the prior art, the beneficial effects brought by the present invention are: the high-capacity lithium cobaltate-based lithium-ion battery positive electrode material and its preparation method described in the present invention are obtained by doping or coating lithium cobaltate Modification is carried out to ensure the stability of the structure when lithium cobalt oxide is excessively delithiated under high voltage; by mixing lithium cobalt oxide with large and small particle sizes, the volume capacity of the material is increased to achieve high capacity. The lithium cobalt oxide positive electrode material obtained by this method has the advantages of good Li ⁺ deintercalation performance, high capacity, good safety performance, good electrochemical performance, especially excellent high-temperature cycle performance, etc. under high voltage conditions greater than 4.2V. The preparation method is simple to operate and can successfully realize industrial production. According to the experimental test, the first discharge specific capacity can reach more than 190 mAh/g. Under the condition of high temperature of 45 ℃, the capacity retention rate after 100 cycles can reach more than 92%, the capacity retention rate of 60 ℃ can reach more than 88.5%, and the capacity retention rate of 70 ℃ The retention rate is above 83.6%.

Detailed ways

The present invention will be further described below in conjunction with specific embodiment:

Example 1:

(1) To prepare large particle size lithium cobalt oxide material A, mix cobalt carbonate (D50 is 16 μm), lithium carbonate, dopant magnesium oxide and zirconium oxide in a certain proportion, wherein the molar ratio of Li and Co is 1.10, The dosage of dopant magnesia was 1.5 wt%, and that of dopant zirconium oxide was 2.5 wt%. The main temperature of sintering was 1050℃, and the sintering time in the main temperature zone was 22 h. The whole sintering process was carried out under air atmosphere The air flow control range is 15 m ³ /h, and the sintered material is processed by crushing, crushing, grading, sieving and other processes to obtain large particle size lithium cobaltate A, with a D50 of 20 μm.

(2) Prepare small particle size lithium cobalt oxide material B, mix cobalt carbonate (D50 is 2 μm), lithium carbonate, dopant magnesia and zirconia according to a certain ratio, wherein the molar ratio of Li and Co is 1.10, The dosage of magnesium oxide as a dopant is 1.8 wt%. The main sintering temperature is 400°C, and the sintering time in the main temperature zone is ³⁰ h. The sintered material was processed by crushing, crushing, grading, sieving and other processes to obtain lithium cobaltate B with a small particle size, and the D50 was 3 μm.

(3) Mix the two materials A and B according to the weight ratio of A and B as A:B=5:1. After mixing evenly, material C is obtained, and the D50 is 17 μm.

(4) Coating material C, the coating material is cobalt oxide, the dosage is 2 wt%, and the coating method used is dry coating.

(5) Sinter the material C in step (4), the main temperature of sintering is controlled at 660°C, the sintering time of the main temperature is 15 h, the whole sintering process is carried out in air atmosphere, and the ventilation volume control range is 20 m ³ /h, the sintered material is processed by crushing, crushing, grading, sieving, iron removal and other processes to obtain the required lithium cobaltate.

Example 2:

(1) To prepare large particle size lithium cobalt oxide material A, mix cobalt carbonate (D50 is 20 μm), lithium carbonate, dopant magnesium oxide and zirconium oxide in a certain proportion, wherein the molar ratio of Li and Co is 1.10, The dosage of dopant magnesia was 1.5 wt%, and that of dopant zirconium oxide was 2.5 wt%. The main temperature of sintering was 1050℃, and the sintering time in the main temperature zone was 22 h. The whole sintering process was carried out under air atmosphere The air flow control range is 15 m ³ /h, and the sintered material is crushed, pulverized, classified, sieved and other processes to obtain large particle size lithium cobaltate A, with a D50 of 22 μm.

(2) Prepare small particle size lithium cobalt oxide material B, mix cobalt carbonate (D50 is 2 μm), lithium carbonate, dopant magnesia and zirconia according to a certain ratio, wherein the molar ratio of Li and Co is 1.10, The dosage of magnesium oxide as a dopant is 1.8 wt%. The main sintering temperature is 400°C, and the sintering time in the main temperature zone is ³⁰ h. The sintered material was processed by crushing, crushing, grading, sieving and other processes to obtain lithium cobaltate B with a small particle size, and the D50 was 3 μm.

(3) Mix the two materials A and B according to the weight ratio of A and B as A:B=6:1. After mixing evenly, material C is obtained, and the D50 is 19 μm.

(4) Coat material C, the coating material is aluminum fluoride and zirconia, the content of aluminum fluoride is 2 wt%, the content of zirconia is 1.5%, and the coating method used is dry coating cover.

(5) Sinter the material C in step (4), the main temperature of sintering is controlled at 660°C, the sintering time of the main temperature is 15 h, the whole sintering process is carried out in air atmosphere, and the ventilation volume control range is 20 m ³ /h, the sintered material is processed by crushing, crushing, grading, sieving, iron removal and other processes to obtain the required lithium cobaltate.

Example 3:

(1) To prepare large particle size lithium cobaltate material A, mix cobalt carbonate (D50 is 7 μm), lithium carbonate, and dopant magnesium oxide in a certain proportion, wherein the molar ratio of Li and Co is 0.95, and the dopant The dosage of magnesium oxide is 0.01 wt%, the main sintering temperature is controlled at 1350 °C, and the sintering time in the main temperature zone is ⁵ h. The final material is processed by crushing, crushing, grading, sieving and other processes to obtain the required semi-finished product A of lithium cobaltate, with a D50 of 10 μm.

(2) Coat material A, the coating material is alumina, the dosage is 0.01 wt%, and the coating method used is wet coating. The solvent used for wet coating is isopropanol.

(3) Sinter the lithium cobalt oxide semi-finished product obtained in step (4). The main temperature of the sintering is controlled at 400°C, and the sintering time of the main temperature is 36 h. 30 m ³ /h, the sintered material is processed by crushing, crushing, grading, sieving, iron removal and other processes to obtain the required lithium cobaltate finished product.

Example 4:

(1) Prepare large particle size lithium cobalt oxide material A, mix cobalt carbonate (D50 is 29 μm), lithium carbonate, and titanium dioxide as a dopant in a certain proportion, wherein the molar ratio of Li and Co is 1.2, and the dopant M The dosage is 10 wt%, the main sintering temperature is controlled at 600°C, the whole sintering process is carried out under an oxygen atmosphere, the air flow control range is 2 m ³ /h, and the sintered materials are crushed, pulverized, classified, passed Sieve and other processes to obtain the required lithium cobalt oxide semi-finished product A, D50 is 30 μm.

(2) Prepare small particle size lithium cobalt oxide material B, mix cobalt carbonate (D50 is 10 μm), lithium carbonate, and titanium dioxide as a dopant in a certain proportion, wherein the molar ratio of Li and Co is 1.2, and the dopant M The dosing amount is 10 wt%, the main sintering temperature is controlled at 300°C, and the sintering time in the main temperature zone is ^35h . After crushing, crushing, grading, sieving and other processes, the required semi-finished product B of lithium cobaltate is obtained, and the D50 is 10 μm.

(3) Mix the two materials A and B according to the weight ratio of A and B in the ratio of A:B=1:2, and obtain material C after mixing evenly, and the D50 is 25 μm.

(4) Coat material C, the coating material is manganese oxide, the dosage is 20 wt%, and the coating method used is dry coating.

(5) Sinter the material C in step (4), the sintering main temperature is controlled at 1250°C, the sintering time of the main temperature is 4 h, the whole sintering process is carried out in an oxygen atmosphere, and the air flow control range is 2 m ³ /h, the sintered material is processed by crushing, crushing, grading, sieving, iron removal and other processes to obtain the required lithium cobalt oxide finished product.

Claims (7)

1. A high-capacity cobaltate lithium-based lithium ion battery positive electrode material, characterized in that: the high-capacity cobaltate lithium-based lithium ion battery positive electrode material mixes large and small modified cobaltate lithium with different particle sizes, and then The finished product of lithium cobalt oxide is obtained after coating. The positive electrode material contains cobalt source material, lithium source material, dopant M, dopant M' and coating material N, wherein the molar ratio of Li:Co is 0.95～ 1.2, the dosage of dopant M and dopant M' are both 0.01-10 wt%, and the dosage of coating material N is 0.01-20 wt%. 2. the preparation method of a kind of high-capacity lithium cobaltate-based lithium ion battery cathode material according to claim 1, is characterized in that: described preparation method specifically comprises the following steps: (1) Preparation of large particle size lithium cobalt oxide material A, D50 is 8-30 μm, the preparation method adopted is: mix cobalt source material, lithium source material and dopant M according to a certain proportion, and the mixing method is dry Mixing or wet mixing, wherein the molar ratio of Li and Co is 0.95~1.2, and the doping amount of dopant M is 0.01~10 wt%. The uniformly mixed materials are sintered, and the main temperature of sintering is controlled at 600~1350℃. The sintering time in the temperature zone is 5 to 40 hours. The whole sintering process is carried out in an air or oxygen atmosphere. The air flow control range is 2 to 30 m ³ /h. The sintered materials are crushed, pulverized, classified, screened, etc. process to obtain the required lithium cobalt oxide semi-finished product A; (2) Prepare small particle size lithium cobalt oxide material B, D50 is 1-8 μm, the preparation method adopted is: mix cobalt source material, lithium source material and dopant M′ according to a certain proportion, and the mixing method is dry Formula mixing or wet mixing, wherein the molar ratio of Li and Co is 0.95-1.2, and the dosage of dopant M' is 0.01-10 wt%; the uniformly mixed materials are sintered, and the main temperature of sintering is controlled at 300-1000°C , the sintering time in the main temperature zone is 4-35 h, the whole sintering process is carried out under air or oxygen atmosphere, the ventilation volume control range is 2-30 m ³ /h, and the sintered materials are crushed, pulverized, classified, passed Screening and other processes to obtain the required semi-finished product B of lithium cobaltate; (3) Mix the two materials A and B according to a certain ratio. When the large particle size lithium cobaltate A is used as the main body, the dosing amount of the small particle size lithium cobaltate B is 0 to 50 wt%, and its mass is 100%. The component content is the mass percentage relative to the large particle size lithium cobaltate A. When the small particle size content is greater than 50%, the mass ratio of A:B is 1:2～2:1, and the materials C and D50 are obtained after mixing evenly 5-25 μm; (4) Coating material C, the coating material is N, and the amount of N is 0.01-20 wt%, and the coating method used is wet coating, dry coating or co-precipitation method; (5) Sinter the coated material C. The main temperature of the sintering is controlled at 400-1250°C, and the sintering time of the main temperature is 4-36 hours. The whole sintering process is carried out in an air or oxygen atmosphere. The ^sintered material is crushed, pulverized, classified, sieved, iron-removed and other processes to obtain the required lithium cobalt oxide finished product. 3. The preparation method of a high-capacity lithium cobaltate-based lithium-ion battery positive electrode material according to claim 2, characterized in that: the cobalt source material involved in the step (1) and step (2) is selected from A mixture of one or more of cobalt tetraoxide, cobalt oxyhydroxide, cobalt hydroxide, cobalt carbonate, cobalt oxalate and cobalt oxide, with D50 between 0.2 and 30 μm. 4. The preparation method of a high-capacity lithium cobaltate-based lithium-ion battery cathode material according to claim 2, characterized in that: the lithium source material involved in the step (1) and step (2) is selected from It is a mixture of one or more of lithium hydroxide, lithium carbonate, and lithium oxalate. 5. The preparation method of a high-capacity lithium cobaltate-based lithium ion battery positive electrode material according to claim 2, characterized in that: the dopant M in the step (1) and the dopant M in the step (2) The dopant M' is selected from the first transition elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn), the second transition elements (Y, Zr, Nb, Mo, Tc, Ru , Rh, Pd, Ag, Cd), alkaline earth elements (Be, Mg, Ca, Sr, Ba) and rare earth elements (La, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) One of oxides, halides, hydroxides, metal organics, nitrates, sulfates, carbonates, oxalates, phosphates, silicates, citrates, or composite oxides with other metal elements Various mixtures. 6. The preparation method of a high-capacity lithium cobaltate-based lithium-ion battery positive electrode material according to claim 2, characterized in that: the coating material N in the step (4) is selected from the first transition element ( Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn), second transition elements (Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd), alkaline earth elements ( Be, Mg, Ca, Sr, Ba) and rare earth elements (La, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) oxides, halides, hydroxides, metal organics, nitric acid Salt, sulfate, carbonate, oxalate, phosphate, silicate, citrate, or a mixture of one or more composite oxides with other metal elements. 7. The preparation method of a high-capacity lithium cobaltate-based lithium-ion battery positive electrode material according to claim 2, characterized in that: the coating material N in the step (4) is a metal compound of F element or F A mixture of a metal compound of an element and one or more of the substances mentioned for the dopant M above.