Preparation method and application of lithium ion battery positive electrode material manganese-titanium precursor

Abstract

The invention discloses a preparation method and application of a lithium ion battery positive electrode material manganese-titanium precursor. The preparation process of the manganese-titanium precursor comprises the following steps: adding a mixed metal salt solution prepared from a manganese-titanium mixed salt solution and a complexing agent and a precipitant solution into a reaction kettle in a parallel flow manner, and carrying out a co-precipitation reaction to prepare the manganese-titanium precursor with uniform manganese-titanium precipitation and uniform morphology. According to the invention, the manganese-titanium precursor with uniform manganese-titanium coprecipitation and uniform morphology can be prepared, the lithium ion battery prepared from the positive electrode material obtained by sintering the manganese-titanium precursor and the lithium source at high temperature has excellent electrochemical properties such as high capacity, high energy density and long cycle service life, and the preparation cost is relatively low.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion battery positive electrode material precursors, and in particular relates to a preparation method and application of a lithium ion battery positive electrode material manganese titanium precursor. Background Art

[0002] Lithium-ion battery positive electrode materials have high specific energy, long cycle life and good cycle stability. As the power source of new energy vehicles, they are an indispensable part of the entire battery field and are booming in the domestic and international battery markets.

[0003] At present, nickel-cobalt-manganese ternary positive electrode materials have been widely studied and applied because of their high energy density, relatively stable cycle performance and cycle life, and high rate performance; however, due to the continuous rise in the price of cobalt in recent years, the production cost of nickel-cobalt-manganese ternary positive electrode materials has increased day by day, and nickel-cobalt-manganese ternary positive electrode materials will not be able to meet the current market demand well. Manganese-titanium rock salt material is a new type of lithium-ion battery positive electrode material, which has higher capacity and energy density, and can also solve the shortage of nickel and cobalt caused by the surge in battery demand, significantly reducing costs. As a product similar to nickel-manganese binary materials, manganese-titanium products have not been extensively studied so far. At the same time, the common problem of manganese-titanium products and nickel-manganese binary materials is that the precursors produced have uneven manganese co-precipitation regardless of the primary particle size, and titanium also has problems such as difficulty in uniform precipitation and difficulty in forming uniform morphology. In addition, the precipitation rates of manganese and titanium do not match, which makes it difficult to synthesize products with uniform co-precipitation and uniform morphology.

[0004] Patent document CN101556996B discloses a method for preparing a spinel lithium manganese titanium oxide positive electrode material for a rechargeable lithium battery. The specific preparation process is: a lithium compound, a manganese salt and a titanium compound are mixed in ethanol according to a stoichiometric ratio, and a gel intermediate is obtained by drying after heating reaction. The heating reaction is carried out in a closed system at a temperature of 30-180°C. The obtained gel intermediate is then ball-milled and subjected to high-temperature heat treatment to obtain a spinel lithium manganese titanium oxide positive electrode material LiMn 2-x Ti x O4, 0.2≤x≤1. This patented technology uses a gel method to prepare a gel intermediate containing lithium manganese and titanium at the same time, and obtains a lithium manganese titanium oxide positive electrode material by high-temperature sintering. The preparation process does not involve the process of preparing a manganese titanium precursor by a manganese titanium coprecipitation reaction.

[0005] At present, there are relatively few studies on manganese-titanium co-precipitation. First, the traditional manganese-titanium precursor has the problem of uneven manganese-titanium co-precipitation. Secondly, a large amount of manganese and titanium oxides will adhere to the surface of the reaction product, which seriously affects the various performance indicators and morphology of the manganese-titanium precursor, and also affects the various electrochemical properties of the subsequent preparation of lithium-ion battery positive electrode materials, and even creates safety hazards. Based on the above technical problems, the present invention focuses on providing a method for preparing a manganese-titanium precursor for a lithium-ion battery positive electrode material that can effectively obtain uniform co-precipitation of manganese and titanium and uniform morphology, while effectively increasing the specific surface area of ​​the manganese-titanium precursor. Summary of the invention

[0006] The technical problem solved by the present invention is to provide a method for preparing a manganese-titanium precursor as a positive electrode material for a lithium-ion battery with a simple process and low cost. The method can produce a manganese-titanium precursor with uniform manganese-titanium co-precipitation and uniform morphology. The lithium-ion battery prepared by the positive electrode material obtained by high-temperature sintering the manganese-titanium precursor with a lithium source has excellent electrochemical properties such as high capacity, high energy density and long cycle life, and the preparation cost is relatively low.

[0007] The present invention adopts the following technical solution to solve the above technical problems, a method for preparing a manganese-titanium precursor of a lithium-ion battery positive electrode material, and the specific steps are: Step S1: dissolving a soluble manganese source and a soluble titanium source in deionized water to prepare a manganese-titanium mixed salt solution, and then adding a complexing agent to prepare a mixed metal salt solution, wherein the complexing agent is one or more of oxalic acid, sodium citrate, citric acid, ammonium acetate, polyvinyl alcohol or ethylenediaminetetraacetic acid; Step S2: adding deionized water and a dispersant as a reaction base liquid into a reaction kettle, wherein the dispersant is one or more of polyvinyl alcohol, carboxymethyl cellulose, polyvinyl pyrrolidone, ethanol, polyethylene glycol, hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate or lauric acid, and then adding the mixed metal salt solution and the precipitant solution obtained in step S1 into the reaction kettle in parallel, continuously introducing an inert gas, controlling the pH value of the reaction system to be 7-12, and performing a coprecipitation reaction at 40-80° C. for 2-20 hours to obtain a coprecipitation product; Step S3: The coprecipitated product is centrifugally washed, dried, and sieved to obtain a manganese-titanium precursor for a positive electrode material of a lithium-ion battery. The manganese-titanium precursor has an average particle size of 3 to 20 μm and a tap density greater than 1.4 g / cm 3 , with a specific surface area of ​​10~80m 2 / g.

[0008] It is further defined that the soluble manganese source in step S1 is one or more of manganese sulfate, manganese chloride, manganese nitrate or manganese acetate; the soluble titanium source is one or more of potassium titanium oxalate, titanium sulfate, titanyl sulfate, titanium citrate or ammonium titanyl oxalate.

[0009] It is further defined that the molar ratio of the complexing agent to the manganese-titanium metal in step S1 is 0.1-3:1.

[0010] It is further defined that the precipitant solution in step S2 is one or more of sodium carbonate solution, sodium hydroxide solution, potassium hydroxide solution, ammonium bicarbonate solution or ammonium carbonate solution.

[0011] It is further defined that the concentration of the dispersant in the reaction base liquid in step S2 is 0.01~0.1g / L, the total concentration of the mixed metal salt solution is 1~3mol / L, the flow rate of the mixed metal salt solution is 5~150mL / min, the total concentration of the precipitant solution is 0.5~8mol / L, and the flow rate of the precipitant solution is 2~200mL / min.

[0012] It is further defined that the rotation speed of the reactor in step S2 is 200-1000 rpm.

[0013] The application of the manganese-titanium precursor of the present invention in the preparation of a positive electrode material for a lithium-ion battery comprises the following specific steps: uniformly mixing a lithium source with the manganese-titanium precursor and sintering the mixture at 600-900° C. for 5-20 hours to obtain a positive electrode material for a lithium-ion battery.

[0014] It is further defined that the mass ratio of the lithium source to the manganese-titanium precursor is 1.0-1.6:1, and the lithium source is one or more of lithium carbonate, lithium hydroxide, lithium oxide, lithium oxalate or lithium acetate.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: the present invention adds a mixed metal salt solution prepared by a manganese-titanium mixed salt solution and a complexing agent and a precipitant solution to a reactor in parallel for a coprecipitation reaction, wherein the complexing agent can achieve matching of the precipitation rates of manganese and titanium, and finally synthesize a uniform coprecipitation product with uniform morphology, and the dispersant can prevent the material from agglomerating, improve the uniformity of manganese and titanium distribution, control the sample particle size and morphology, and thus affect the subsequent electrochemical properties such as the capacity of the positive electrode material. The present invention can achieve uniform precipitation of manganese and titanium elements, and the manganese and titanium in the prepared manganese-titanium precursor are uniformly coprecipitated and present a uniform morphology, and the specific surface area of ​​the prepared manganese-titanium precursor reaches 10~80m 2 / g, tap density greater than 1.4g / cm 3 The lithium-ion battery prepared by the positive electrode material obtained by high-temperature sintering of the manganese-titanium precursor and a lithium source has excellent electrochemical properties such as high capacity, high energy density and long cycle life. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the SEM image of the manganese-titanium precursor prepared in Example 1.

[0017] Figure 2 This is the SEM image of the manganese-titanium precursor prepared in Example 2.

[0018] Figure 3 This is the SEM image of the manganese-titanium precursor prepared in Comparative Example 1. DETAILED DESCRIPTION

[0019] The above contents of the present invention are further described in detail below through examples, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies implemented based on the above contents of the present invention belong to the scope of the present invention. Example 1

[0020] 1) preparing a manganese-titanium mixed salt solution with a total concentration of 2.5 mol / L using manganese sulfate and anhydrous titanium sulfate, and adding a certain amount of polyvinyl alcohol, wherein the molar ratio of polyvinyl alcohol to manganese-titanium metal is 1:1; preparing a sodium carbonate solution with a concentration of 1.5 mol / L using sodium carbonate as a precipitant solution; 2) A mixture of polyethylene glycol and pure water with a concentration of 0.1 g / L was prepared as a reaction base solution, and the manganese-titanium mixed salt solution and the precipitant solution obtained in step S1 were respectively introduced into the reactor at a flow rate of 80 mL / min and 150 mL / min for co-precipitation reaction, and the pH value of the reaction system was controlled to be 9±0.05, the reaction temperature was 55° C., the speed of the reactor was 700 rpm, the N2 introduction rate was 8 L / min, and the reaction time was 2 h to obtain a manganese-titanium precursor slurry; 3) After the reaction is completed, the prepared manganese-titanium precursor slurry is centrifugally washed, dried, and sieved to obtain a manganese-titanium precursor; the molar ratio of manganese to titanium in the prepared manganese-titanium precursor is 0.5:0.5, the particle size D50 of the manganese-titanium precursor is 5.0 μm, the primary particles are cubic, and the tap density is 1.42 g / cm 3 , the specific surface area is 25.82m 2 / g; Lithium carbonate was used as a lithium source, and was evenly mixed with the prepared manganese-titanium precursor in a weight ratio of 1.05:1 and sintered at 750°C for 6 hours to obtain a lithium-ion battery positive electrode material. The capacity of the lithium-ion battery prepared with the positive electrode material was 305.21 mAh / g. Example 2

[0021] 1) preparing a manganese-titanium mixed salt solution with a total concentration of 2.0 mol / L using manganese sulfate and titanyl sulfate and adding a certain amount of ammonium acetate, wherein the molar ratio of ammonium acetate to manganese-titanium metal is 0.5:1; preparing a precipitant solution with a total concentration of 2.0 mol / L using sodium carbonate and sodium hydroxide; 2) preparing a mixed solution of polyvinyl pyrrolidone and pure water with a concentration of 0.02 g / L as a reaction base solution, and introducing the manganese-titanium mixed salt solution and the precipitant solution obtained in step S1 into the reactor at a flow rate of 40 mL / min and 30 mL / min, respectively, to carry out a co-precipitation reaction, controlling the pH value of the reaction system to be 11±0.05, the reaction temperature to be 70°C, the speed of the reactor to be 500 rpm, the N2 introduction rate to be 8 L / min, the reaction time to be 5 h, and obtaining a manganese-titanium precursor slurry; 3) After the reaction is completed, the prepared manganese-titanium precursor slurry is centrifugally washed, dried, and sieved to obtain a manganese-titanium precursor; the molar ratio of manganese to titanium in the prepared manganese-titanium precursor is 0.7:0.3, the particle size D50 of the manganese-titanium precursor is 7.0 μm, and its tap density is 1.62 g / cm 3 , the specific surface area is 12.82m 2 / g; Lithium carbonate was used as a lithium source and was evenly mixed with the prepared manganese-titanium precursor in a weight ratio of 1.02:1 and sintered at 650° C. for 10 h to obtain a lithium-ion battery positive electrode material. The capacity of the lithium-ion battery prepared with the positive electrode material was 302.34 mAh / g.

[0022] Comparative Example 1 1) Prepare a manganese-titanium mixed salt solution with a total concentration of 2.0 mol / L using manganese sulfate and titanyl sulfate; prepare a precipitant solution with a total concentration of 2.0 mol / L using sodium carbonate and sodium hydroxide; 2) Prepare a mixture of polyvinyl pyrrolidone and pure water with a concentration of 0.02 g / L as the reaction base liquid, and flow the manganese-titanium mixed salt solution and the precipitant solution into the reactor at a flow rate of 40 mL / min and 30 mL / min respectively for co-precipitation reaction, control the pH value of the reaction system to 11±0.05, the reaction temperature to 70°C, the speed of the reactor to 500 rpm, the N2 introduction rate to 8 L / min, the reaction time to 5 h, and obtain a manganese-titanium precursor slurry; 3) After the reaction is completed, the prepared manganese-titanium precursor slurry is centrifugally washed, dried, and sieved to obtain a manganese-titanium precursor; the molar ratio of manganese to titanium in the prepared manganese-titanium precursor is 0.7:0.3, the particle size D50 of the manganese-titanium precursor is 4.2 μm, and its tap density is 0.71 g / cm 3 , the specific surface area is 110.01m 2 / g, the residual Na content is high, which is 15650ppm; Lithium carbonate was used as a lithium source and was evenly mixed with the prepared manganese-titanium precursor in a weight ratio of 1.02:1 and sintered at 650°C for 10 hours to obtain a lithium-ion battery positive electrode material. The capacity of the lithium-ion battery prepared with the positive electrode material was 230.32 mAh / g.

[0023] Comparative Example 2 1) preparing a manganese-titanium mixed salt solution with a total concentration of 2.0 mol / L using manganese sulfate and titanyl sulfate and adding a certain amount of ammonium acetate, wherein the molar ratio of ammonium acetate to manganese-titanium metal is 0.5:1; preparing a precipitant solution with a total concentration of 2.0 mol / L using sodium carbonate and sodium hydroxide; 2) using a certain amount of pure water as the reaction base liquid, the manganese-titanium mixed salt solution and the precipitant solution obtained in step S1 are respectively introduced into the reactor at flow rates of 40 mL / min and 30 mL / min to carry out a co-precipitation reaction, the pH value of the reaction system is controlled to be 11±0.05, the reaction temperature is 70°C, the speed of the reactor is 500 rpm, the N2 introduction rate is 8 L / min, the reaction time is 5 h, and a manganese-titanium precursor slurry is obtained; 3) After the reaction is completed, the prepared manganese-titanium precursor slurry is centrifugally washed, dried, and sieved to obtain a manganese-titanium precursor; the molar ratio of manganese to titanium in the prepared manganese-titanium precursor is 0.7:0.3, the particle size D50 of the manganese-titanium precursor is 12.6 μm, and its tap density is 0.92 g / cm 3 , with a specific surface area of ​​98.79m 2 / g, the residual Na content is high, at 22583ppm; Lithium carbonate was used as a lithium source and was evenly mixed with the prepared manganese-titanium precursor in a weight ratio of 1.02:1 and sintered at 650°C for 10 hours to obtain a lithium-ion battery positive electrode material. The capacity of the lithium-ion battery prepared with the positive electrode material was 273.56 mAh / g.

[0024] Comparative Example 3 1) Prepare a manganese-titanium mixed salt solution with a total concentration of 2.0 mol / L using manganese sulfate and titanyl sulfate; prepare a precipitant solution with a total concentration of 2.0 mol / L using sodium carbonate and sodium hydroxide; 2) using a certain amount of pure water as the reaction base liquid, the manganese-titanium mixed salt solution and the precipitant solution obtained in step S1 are respectively introduced into the reactor at flow rates of 40 mL / min and 30 mL / min to carry out a co-precipitation reaction, the pH value of the reaction system is controlled to be 11±0.05, the reaction temperature is 70°C, the speed of the reactor is 500 rpm, the N2 introduction rate is 8 L / min, the reaction time is 5 h, and a manganese-titanium precursor slurry is obtained; 3) After the reaction is completed, the prepared manganese-titanium precursor slurry is centrifugally washed, dried, and sieved to obtain a manganese-titanium precursor; the molar ratio of manganese to titanium in the prepared manganese-titanium precursor is 0.7:0.3, the particle size D50 of the manganese-titanium precursor is 22.8 μm, and its tap density is 0.63 g / cm 3 , the specific surface area is 183.55m 2 / g, the residual Na content is high, 33290ppm; Lithium carbonate was used as a lithium source and was evenly mixed with the prepared manganese-titanium precursor in a weight ratio of 1.02:1 and sintered at 650° C. for 10 h to obtain a lithium-ion battery positive electrode material. The capacity of the lithium-ion battery prepared with the positive electrode material was 200.19 mAh / g.

[0025] In summary, in the preparation of the manganese-titanium precursor, Examples 1 and 2 prepared a manganese-titanium precursor with uniform coprecipitation and uniform morphology, and its tap density was greater than 1.4 g / cm 3 , with a specific surface area of ​​10-80m 2 / g, the lithium-ion battery positive electrode material obtained based on the manganese-titanium precursor can obtain excellent cycle charge and discharge performance, cycle stability and safety performance.

[0026] The above embodiments describe the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the scope of the principles of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a manganese-titanium precursor for a lithium-ion battery positive electrode material, characterized in that The specific steps are: Step S1: dissolving a soluble manganese source and a soluble titanium source in deionized water to prepare a manganese-titanium mixed salt solution, and then adding a complexing agent to prepare a mixed metal salt solution, wherein the complexing agent is one or more of oxalic acid, sodium citrate, citric acid, ammonium acetate, polyvinyl alcohol or ethylenediaminetetraacetic acid; Step S2: adding deionized water and a dispersant as a reaction base liquid into a reaction kettle, wherein the dispersant is one or more of polyvinyl alcohol, carboxymethyl cellulose, polyvinyl pyrrolidone, ethanol, polyethylene glycol, hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate or lauric acid, and then adding the mixed metal salt solution and the precipitant solution obtained in step S1 into the reaction kettle in parallel, continuously introducing an inert gas, controlling the pH value of the reaction system to be 7-12, and performing a coprecipitation reaction at 40-80° C. for 2-20 hours to obtain a coprecipitation product; Step S3: The coprecipitated product is centrifugally washed, dried, and sieved to obtain a manganese-titanium precursor for a positive electrode material of a lithium-ion battery. The manganese-titanium precursor has an average particle size of 3 to 20 μm and a tap density greater than 1.4 g / cm 3 , with a specific surface area of ​​10~80m 2 / g.

2. The method for preparing a manganese-titanium precursor for a lithium-ion battery positive electrode material according to claim 1, characterized in that: In step S1, the soluble manganese source is one or more of manganese sulfate, manganese chloride, manganese nitrate or manganese acetate; the soluble titanium source is one or more of potassium titanium oxalate, titanium sulfate, titanyl sulfate, titanium citrate or ammonium titanyl oxalate.

3. The method for preparing a manganese-titanium precursor for a lithium-ion battery positive electrode material according to claim 1, characterized in that: The molar ratio of the complexing agent to the manganese-titanium metal in step S1 is 0.1-3:

1.

4. The method for preparing a manganese-titanium precursor for a lithium-ion battery cathode material according to claim 1, characterized in that: The precipitant solution in step S2 is one or more of sodium carbonate solution, sodium hydroxide solution, potassium hydroxide solution, ammonium bicarbonate solution or ammonium carbonate solution.

5. The method for preparing a manganese-titanium precursor for a lithium-ion battery positive electrode material according to claim 1, characterized in that: The concentration of the dispersant in the reaction base liquid in step S2 is 0.01~0.1g / L, the total concentration of the mixed metal salt solution is 1~3mol / L, the flow rate of the mixed metal salt solution is 5~150mL / min, the total concentration of the precipitant solution is 0.5~8mol / L, and the flow rate of the precipitant solution is 2~200mL / min.

6. The method for preparing a manganese-titanium precursor for a lithium-ion battery positive electrode material according to claim 1, characterized in that: The rotation speed of the reactor in step S2 is 200-1000 rpm.

7. Use of the manganese-titanium precursor prepared by the method according to claims 1 to 6 in preparing positive electrode materials for lithium-ion batteries.

8. The use according to claim 7, characterized in that The specific process is: the lithium source is evenly mixed with the above-mentioned manganese-titanium precursor, and then sintered at 600-900° C. for 5-20 hours to obtain the positive electrode material for the lithium-ion battery.

9. The use according to claim 8, characterized in that: The mass ratio of the lithium source to the manganese-titanium precursor is 1.0-1.6:1, and the lithium source is one or more of lithium carbonate, lithium hydroxide, lithium oxide, lithium oxalate or lithium acetate.

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