CN106410186A - Preparation method and application of lithium-rich layered oxide cathode material - Google Patents

Abstract

A preparation method of a lithium-rich layered oxide positive electrode material, the chemical molecular formula of the lithium-rich layered oxide positive electrode material is Li[Li _(1-2x)/3 Ni _x-y M _2y Mn _{2/3-x /3-y} ]O ₂ , where: 0<x<0.5, 0<y<x, M is one or a mixture of two or more of Fe, Co, Al and Cr in any ratio; its preparation method is: First, the M-doped Li ₂ MnO ₃ material was prepared by a high-temperature solid-state method, then mixed with Li source, Ni source and Mn source material, and mixed and roasted at 700-950°C for 5-15h to obtain the target product. The material prepared by the invention has the advantages of stable structure, easy control of conditions, good batch stability, etc., and is suitable for large-scale production; the button battery assembled by using the prepared lithium-rich layered oxide positive electrode material has the advantages of first charge and discharge It has the advantages of high efficiency, small voltage attenuation, and good cycle performance.

Description

Preparation method and application of a lithium-rich layered oxide cathode material

technical field

The invention belongs to the technical field of positive electrode materials for lithium ion batteries, in particular to a preparation method and application of a lithium-rich layered oxide positive electrode material.

Background technique

With the popularity of portable electronic products, hybrid vehicles and pure electric vehicles, lithium-ion batteries have also been used more and more widely. In recent years, in order to develop lithium-ion batteries with high energy density, many positive electrode materials with high energy density have been developed. Among them, lithium-rich layered oxide cathode materials have attracted in-depth research because of their advantages such as high discharge capacity, wide voltage platform, and environmental protection. The expression of lithium-rich layered oxide material is Li(Li _1/3-2x/3 Ni _x Mn _2/3-x/3 )O ₂ (0<x<1/2), which can be regarded as Li ₂ MnO ₃ (layered material, which can be expressed as Li[Li _1/3 Mn _2/3 ]O ₂ ) material and LiNi _1/2 Mn _1/2 O ₂ material form a solid solution, therefore, lithium-rich layered oxide The expression of material Li(Li _1/3-2x/3 Ni _x Mn _2/3-x/3 )O ₂ can also be written as a[yLi ₂ MnO ₃ ·(1-y)LiNi _1/2 Mn _1/2 O ₂ ], where a=2(1+x)/3, y=(1-2x)/(1+x).

According to a large number of literature reports, metal ion doping of Li(Li _1/3-2x/3 Ni _x Mn _2/3-x/3 )O ₂ materials can effectively improve their electrochemical performance. The preparation methods of lithium-rich layered oxide cathode materials and lithium-rich layered oxide cathode materials modified by metal M ions mainly include coprecipitation method, sol-gel method, and combustion method. Co-precipitation method: Li et al. reported a method of co-precipitating Mn, Ni and Co acetate solutions with LiOH to prepare hydroxide precursors. After washing, drying and mixing with LiOH for uniform ball milling, Li (Li _0.2 Mn _0.56 Ni _0.16 Co _0.08 )O ₂ materials (Journal of Power Sources, 2011, 196, 4821). Sol-gel method: Zheng et al. first made a solution of Ni(NO ₃ ) ₂ 6H ₂ O, Co(NO ₃ ) ₂ 6H ₂ O and Mn(NO ₃ ) ₂ , then mixed LiNO ₃ with appropriate amount of citric acid The mixed solution of the above-mentioned transition metal is slowly added into the mixed solution of the transition metal, and then the pH value of the mixed solution of the above two solutions is adjusted to 7.0 to 8.0 with ammonia water. After evaporation to dryness, the designed Li (Li _0.20 Ni _0.13 Co _0.13 Mn _0.54 )O ₂ cathode material (Electrochimica Acta,2011,56,3071); Ma et al also prepared Li[Li _0.2 Ni _0.11 Co _0.11 Mn _0.54 Al _0.04 ]O ₂ material by a similar method ( Journal of Power Sources, 2015, 277, 393). 2. Combustion method: Hong et al. used the acetate and nitrate of Li, Ni and Mn as raw materials, prepared them into a solution according to the stoichiometric ratio, ignited the obtained xerogel after sufficient drying, and finally performed high-temperature heat treatment and quenching. That is, the desired Li(Li _0.2 Ni _0.2 Mn _0.6 )O ₂ and Li(Li _0.27 Co _0.20 Mn _0.53 )O ₂ materials are obtained (Solid State Ionics, 2005, 176, 1035).

In order to achieve uniform mixing of metal ions, the above-mentioned preparation methods all adopt the method of adding metal ions Ni, Mn and M at the same time to form a uniform solution or mixing them uniformly. The lithium-rich layered oxide materials prepared by these methods have High discharge specific capacity, but it also has the instability of material structure, and the voltage drop and capacity fading caused by the transformation of part of the layered structure to the spinel structure during the cycle process restrict its application in lithium-ion batteries. practical application. The present invention modifies the Li _{2 MnO 3 phase with dopant M ions, and then mixes and roasts the modified Li 2 MnO 3 phase with} Li source, Ni source and Mn source materials to prepare lithium-rich layered oxides. A preparation method. By searching, for the doped lithium-rich layered oxide cathode material Li[Li _(1-2x)/3 Ni _xy M _2y Mn _2/3-x/3-y ]O ₂ (0<x<0.5, 0<y<x, M is one or more of Fe, Co, Al and Cr), no similar reports have been found.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art, and provide a preparation method and application of a lithium-rich layered oxide cathode material.

Technical scheme of the present invention:

A method for preparing a lithium-rich layered oxide positive electrode material, the chemical molecular formula of the lithium-rich layered oxide positive electrode material is Li[Li _(1-2x)/3 Ni _xy M _2y Mn _{2/3-x/3 -y} ]O ₂ , where: 0<x<0.5, 0<y<x, M is one of Fe, Co, Al and Cr or a mixture of two or more in any proportion;

Its preparation method steps are as follows:

1) Mix Li source, Mn source and M metal source evenly to obtain a mixture;

2) Calcining the above mixture at 400-750° C. for 5-80 hours to obtain M metal-doped Li ₂ MnO ₃ material;

3) fully mixing the above-mentioned M metal-doped Li ₂ MnO ₃ material with Li source, Ni source and Mn source to obtain a mixed material;

4) Calcining the above mixed material at 700-950°C for 5-15h;

5) cooling to room temperature to obtain the lithium-rich layered oxide cathode material Li[Li _(1-2x)/3 Ni _xy M _2y Mn _2/3-x/3-y ]O ₂ .

The Li source in the step 1) is lithium carbonate, lithium hydroxide, lithium nitrate and lithium acetate or a mixture of two or more in any proportion; the Mn source is manganese oxide (sub)manganese, manganese hydroxide (sub)manganese, A mixture of two or more of manganese oxyhydroxide, manganese carbonate, manganese nitrate and manganese acetate in any proportion; M metal source is one of M metal carbonate, hydroxide, nitrate and acetate or A mixture of two or more in any ratio; the molar ratio of Li source, Mn source and M metal source is (2-4x):(1-2x-3y):3y, where: 0<x<0.5, 0<y< x.

In said step 3), the Li source is lithium carbonate, lithium hydroxide, lithium nitrate and lithium acetate, or a mixture of two or more in arbitrary proportions; the Ni source is (sub)nickel oxide, (sub)nickel hydroxide, Nickel oxyhydroxide, nickel carbonate, nickel nitrate and nickel acetate or a mixture of two or more in any proportion; Mn source is manganese oxide (sub)manganese hydroxide, manganese oxyhydroxide, manganese carbonate, manganese nitrate and a mixture of two or more in arbitrary proportions in manganese acetate; the molar ratio of the M metal-doped Li ₂ MnO ₃ material to the added Li, Ni and Mn is (1-2x): 3x:(3x-3y )/2:(3x+3y)/2, where: 0<x<0.5, 0<y<x.

The application of a lithium-rich layered oxide positive electrode material is used to prepare the positive electrode material of a lithium-ion battery with a high specific capacity.

The beneficial effects of the present invention are:

The lithium-rich layered oxide cathode material prepared by this method is doped with modified M ions into the Li ₂ MnO ₃ phase, which effectively stabilizes the structure of the material, and then based on the modified Li ₂ MnO ₃ material, the preparation The lithium-rich layered oxide cathode material inhibits the structural transformation of the prepared lithium-rich layered oxide cathode material during the cycle, thus effectively reducing the oxygen evolution of the material during the first charging process and improving the material's durability. The first charge and discharge efficiency reduces the voltage drop of the material during the cycle and improves the cycle capacity retention rate of the material; the preparation process of the material is well controllable, the cost of large-scale manufacturing is low, the process repeatability is high, and the batch stability is good , suitable for large-scale production, and can meet the market demand for high-voltage, high-specific-capacity lithium-ion battery cathode materials.

Description of drawings

1 is an SEM image of the lithium-rich layered oxide cathode material Li[Li _0.28 Ni _0.06 Fe _0.04 Mn _0.62 ]O ₂ (x=1/12, M=Fe, y=0.02) prepared in Example 1.

Fig. 2 is a cycle performance diagram of the lithium-rich layered oxide cathode material Li[Li _0.28 Ni _0.06 Fe _0.04 Mn _0.62 ]O ₂ (x=1/12, M=Fe, y=0.02) prepared in Example 1.

3 is an SEM image of the lithium-rich layered oxide cathode material Li[Li _0.2 Ni _0.1 Co _0.2 Mn _0.5 ]O ₂ (x=1/5, M=Co, y=0.1) prepared in Example 2.

Fig. 4 is a cycle performance diagram of the lithium-rich layered oxide cathode material Li[Li _0.2 Ni _0.1 Co _0.2 Mn _0.5 ]O ₂ (x=1/5, M=Co, y=0.1) prepared in Example 2.

5 is an SEM image of the lithium-rich layered oxide cathode material Li[Li _0.11 Ni _0.28 Al _0.1 Mn _0.51 ]O ₂ (x=1/3, M=Al, y=0.05) prepared in Example 3.

Fig. 6 is a cycle performance diagram of the lithium-rich layered oxide cathode material Li[Li _0.11 Ni _0.28 Al _0.1 Mn _0.51 ]O ₂ (x=1/3, M=Al, y=0.05) prepared in Example 3.

7 is an SEM image of the lithium-rich layered oxide cathode material Li[Li _0.03 Ni _0.43 Cr _0.04 Mn _0.50 ]O ₂ (x=9/20, M=Cr, y=0.02) prepared in Example 4.

Fig. 8 is a cycle performance graph of the lithium-rich layered oxide cathode material Li[Li _0.03 Ni _0.43 Cr _0.04 Mn _0.50 ]O ₂ (x=9/20, M=Cr, y=0.02) prepared in Example 4.

detailed description

The following describes the detailed process of the present invention through the examples, and the examples are provided for the convenience of understanding rather than limiting the present invention.

Example 1:

A method for preparing a lithium-rich layered oxide cathode material, the chemical formula of the lithium-rich layered oxide cathode material is Li[Li _0.28 Ni _0.06 Fe _0.04 Mn _0.62 ]O ₂ (x=1/12, M= Fe, y=0.02), its preparation method step is as follows:

1) Weigh 87.14g MnSO ₄ ·H ₂ O and 16.16g Fe(NO ₃ ) ₃ ·9H ₂ O to prepare a solution with a metal ion concentration of 1mol/L;

2) under continuous stirring condition, slowly add the mixed solution of ammoniacal liquor and sodium carbonate in above-mentioned solution, ammoniacal liquor concentration is 0.2mol/L in the mixed solution, and sodium carbonate concentration is 2mol/L, to control reaction solution pH value is 10, Precipitation reaction is carried out, the precipitate is filtered, washed and dried to obtain Fe _- doped MnCO3 material;

3) Weigh 41.05g Li ₂ CO ₃ , and mix it evenly with the Fe-doped MnCO ₃ material obtained in step 2), place it in a muffle furnace for calcination, the calcination temperature is 400°C, and the calcination time is 80h, Fe-doped Li ₂ MnO ₃ material is obtained;

4) Mix 17.00gCH ₃ COOLi·2H ₂ O, 18.42g Ni(NO ₃ ) ₂ ·6H ₂ O and 25.33g Mn(CH ₃ COO) ₂ ·4H ₂ O to obtain a mixed solution with a total metal ion concentration of 2mol /L, the Fe-doped Li ₂ MnO ₃ material obtained in step 3) is put into the mixed solution to obtain a suspension, and the suspension is evaporated to dryness under stirring conditions to obtain a precursor material;

5) Put the precursor material obtained in step 4) into a muffle furnace for calcination, the calcination temperature is 950°C, and the calcination time is 5h, and 80.70g of lithium-rich layered oxide cathode material Li[Li _0.28 Ni _0.08 Mn _0.64 ]O ₂ .

FIG. 1 is an SEM image of the lithium-rich layered oxide cathode material Li[Li _0.28 Ni _0.06 Fe _0.04 Mn _0.62 ]O ₂ prepared in Example 1.

The prepared lithium-rich layered oxide positive electrode material is used to prepare positive electrode materials for high specific capacity lithium ion batteries.

Fig. 2 is a cycle performance diagram of the lithium-rich layered oxide cathode material Li[Li _0.28 Ni _0.06 Fe _0.04 Mn _0.62 ]O ₂ prepared in Example 1 assembled into a button battery. The figure shows that the Li[Li _0.28 Ni _0.06 Fe _0.04 Mn _0.62 ]O ₂ material prepared by this method has high discharge specific capacity and good cycle performance.

Example 2:

A method for preparing a lithium-rich layered oxide cathode material, the chemical formula of the lithium-rich layered oxide cathode material is Li[Li _0.2 Ni _0.1 Co _0.2 Mn _0.5 ]O ₂ (x=1/5, M= Co, y=0.1), its preparation method step is as follows:

1) Weigh 27.58g LiNO ₃ ·H ₂ O, 22.99g MnCO ₃ and 16.05g Co ₃ O ₄ respectively, mix well;

2) The mixture obtained in step 1) is placed in a muffle furnace for calcination, the calcination temperature is 750°C, and the calcination time is 5h, to obtain a Co-doped Li ₂ MnO ₃ material;

3) Prepare a mixed solution of 42.78g NiCl·6H ₂ O and 50.71g MnSO ₄ ·4H ₂ O, the total concentration of metal ions is 2.5mol/L;

4) under continuous stirring condition, slowly add the mixed solution of ammoniacal liquor and sodium hydroxide in the solution of step 3) gained, in the mixed solution, the concentration of ammoniacal liquor is 0.3mol/L, and the concentration of sodium carbonate is 4mol/L, to control the reaction solution The pH value is 10, and a precipitation reaction is carried out to obtain a mixed precipitate of nickel hydroxide and manganese hydroxide, which is filtered, washed and dried;

5) Mix the Co-doped Li ₂ MnO ₃ material obtained in step 2), the mixed precipitate obtained in step 4), and 27.58g LiNO3, and place them in a muffle furnace for calcination. The calcination temperature is 850°C, and the calcination time is After 10 hours, 85.45 g of lithium-rich layered oxide cathode material Li[Li _0.2 Ni _0.1 Co _0.2 Mn _0.5 ]O ₂ was obtained.

FIG. 3 is an SEM image of the lithium-rich layered oxide cathode material Li[Li _0.2 Ni _0.1 Co _0.2 Mn _0.5 ]O ₂ prepared in Example 2.

The prepared lithium-rich layered oxide positive electrode material is used to prepare positive electrode materials for high specific capacity lithium ion batteries.

Fig. 4 is a cycle performance graph of the lithium-rich layered oxide cathode material Li[Li _0.2 Ni _0.1 Co _0.2 Mn _0.5 ]O 2 prepared in Example ₂ assembled into a button battery. The figure shows that the Li[Li _0.2 Ni _0.1 Co _0.2 Mn _0.5 ]O ₂ material prepared by this method has high discharge specific capacity and good cycle performance.

Example 3:

A method for preparing a lithium-rich layered oxide cathode material, the chemical formula of the lithium-rich layered oxide cathode material is Li[Li _0.11 Ni _0.28 Al _0.1 Mn _0.51 ]O ₂ (x=1/3, M= Al, y=0.05), its preparation method step is as follows:

1) Weigh 9.32g LiOH, 10.87gMn(OH) ₂ and 37.51gAl(NO ₃ ) ₃ 9H ₂ O respectively, and mix well;

2) The mixture obtained in step 1) is placed in a muffle furnace for calcination, the calcination temperature is 550°C, and the calcination time is 55h, to obtain an Al-doped Li ₂ MnO ₃ material;

3) The Al-doped Li ₂ MnO ₃ material obtained in step 2) was mixed uniformly with 24.63g Li ₂ CO ₃ , 10.21gNiO and 44.06gMnCO3 to obtain a mixture;

4) The mixture obtained in step 3) was placed in a muffle furnace for calcination, the calcination temperature was 700° C., and the calcination time was 15 hours to obtain 86.85 g of lithium-rich layered oxide cathode material Li[Li _0.11 Ni _0.28 Al _0.1 Mn _0.51 ]O ₂ .

5 is an SEM image of the lithium-rich layered oxide cathode material Li[Li _0.11 Ni _0.28 Al _0.1 Mn _0.51 ]O ₂ prepared in Example 2.

The prepared lithium-rich layered oxide positive electrode material is used to prepare positive electrode materials for high specific capacity lithium ion batteries.

Fig. 6 is a diagram of the cycle performance of the lithium-rich layered oxide cathode material Li[Li _0.11 Ni _0.28 Al _0.1 Mn _0.51 ]O 2 prepared in Example ₂ assembled into a button battery. The figure shows that the Li[Li _0.11 Ni _0.28 Al _0.1 Mn _0.51 ]O ₂ material prepared by this method has high discharge specific capacity and good cycle performance.

Example 4:

A method for preparing a lithium-rich layered oxide cathode material, the chemical formula of the lithium-rich layered oxide cathode material is Li[Li _0.03 Ni _0.43 Cr _0.04 Mn _0.50 ]O ₂ (x=9/20, M= Cr, y=0.02), its preparation method step is as follows:

1) Weigh 4.93g Li ₂ CO ₃ , 3.07g MnCO ₃ and 16.01g Cr(NO ₃ ) ₃ 9H ₂ O respectively, and mix well;

2) The mixed material obtained in step 1) is placed in a muffle furnace for calcination, the calcination temperature is 650°C, and the calcination time is 25h, to obtain a Cr-doped Li ₂ MnO ₃ material;

3) Mix the Cr-doped Li ₂ MnO ₃ material obtained in step 2) with 37.76g LiOH, 51.04g NiCO ₃ and 54.03g MnCO ₃ evenly, and place it in a muffle furnace for calcination at a temperature of 800°C and a calcination time of After 12 hours, 93.94 g of lithium-rich layered oxide cathode material Li[Li _0.03 Ni _0.43 Cr _0.04 Mn _0.50 ]O ₂ was obtained.

7 is an SEM image of the lithium-rich layered oxide cathode material Li[Li _0.03 Ni _0.43 Cr _0.04 Mn _0.50 ]O ₂ prepared in Example 4.

The prepared lithium-rich layered oxide positive electrode material is used to prepare positive electrode materials for high specific capacity lithium ion batteries.

Fig. 8 is a cycle performance chart of the lithium-rich layered oxide cathode material Li[Li _0.03 Ni _0.43 Cr _0.04 Mn _0.50 ]O ₂ prepared in Example 4 assembled into a button battery. The figure shows that the prepared Li[Li _0.03 Ni _0.43 Cr _0.04 Mn _0.50 ]O ₂ material has high discharge specific capacity and good cycle performance.

In summary, the lithium-rich layered oxide prepared by this method reduces the voltage decay of the material and improves the cycle performance of the material. Therefore, the lithium-rich layered oxide cathode material prepared by this method is expected to meet the market demand for high specific capacity and wide voltage window cathode materials for high-performance lithium-ion batteries.

Although the above-mentioned application examples have described the present invention, the present invention is not limited to the above-mentioned specific embodiments, and the above-mentioned specific embodiments are only illustrative, rather than restrictive. Under the inspiration, many modifications can be made without departing from the gist of the present invention, and these all belong to the protection of the present invention.

Claims (4)

1. A method for preparing a lithium-rich layered oxide positive electrode material, characterized in that: the chemical molecular formula of the lithium-rich layered oxide positive electrode material is Li[Li _(1-2x)/3 Ni _xy M _2y Mn _{2 /3-x/3-y} ]O ₂ , where: 0<x<0.5, 0<y<x, M is one of Fe, Co, Al and Cr or a mixture of two or more in any proportion; Its preparation method steps are as follows: 1) Mix Li source, Mn source and M metal source evenly to obtain a mixture; 2) Calcining the above mixture at 400-750° C. for 5-80 hours to obtain M metal-doped Li ₂ MnO ₃ material; 3) fully mixing the above-mentioned M metal-doped Li ₂ MnO ₃ material with Li source, Ni source and Mn source to obtain a mixed material; 4) Calcining the above mixed material at 700-950°C for 5-15h; 5) cooling to room temperature to obtain the lithium-rich layered oxide cathode material Li[Li _(1-2x)/3 Ni _xy M _2y Mn _2/3-x/3-y ]O ₂ . 2. according to the preparation method of the described lithium-rich layered oxide cathode material of claim 1, it is characterized in that: Li source is lithium carbonate, lithium hydroxide, lithium nitrate and lithium acetate in described step 1) or A mixture of two or more in any proportion; Mn source is a mixture of two or more in any proportion of manganese oxide (sub)manganese hydroxide, manganese oxyhydroxide, manganese carbonate, manganese nitrate and manganese acetate; M metal The source is one of carbonate, hydroxide, nitrate and acetate of M metal or a mixture of two or more in any proportion; the molar ratio of Li source, Mn source and M metal source is (2-4x) :(1-2x-3y):3y, where: 0<x<0.5, 0<y<x. 3. according to the preparation method of the described lithium-rich layered oxide cathode material of claim 1, it is characterized in that: Li source is lithium carbonate, lithium hydroxide, lithium nitrate and lithium acetate in described step 3) or A mixture of two or more in arbitrary proportions; the Ni source is one of (sub)nickel oxide, (sub)nickel hydroxide, nickel oxyhydroxide, nickel carbonate, nickel nitrate and nickel acetate or a mixture of two or more in any proportion; Mn The source is a mixture of two or more in arbitrary proportions among manganese oxide (sub)manganese hydroxide, manganese oxyhydroxide, manganese carbonate, manganese nitrate and manganese acetate; M metal-doped Li ₂ MnO ₃ material and The molar ratio of Li, Ni and Mn added is (1-2x): 3x:(3x-3y)/2:(3x+3y)/2, where: 0<x<0.5, 0<y<x . 4. An application of the lithium-rich layered oxide positive electrode material as claimed in claim 1, characterized in that: it is used to prepare the positive electrode material for high specific capacity lithium ion batteries.