CN117466343A - A kind of single crystal lithium nickel cobalt manganate precursor and preparation method - Google Patents

Abstract

The invention discloses a single crystal nickel cobalt lithium manganate precursor and a preparation method. The metal cation mixture and the sodium hydroxide solution are mixed evenly, ammonia water is added to adjust the pH value, and then a modifier and DMF are added to react. , add deionized water, let it stand and filter to remove the filtrate, and dry the substrate to prepare it. The diacetyl group and acetamide group on the strengthening agent can complex with metal cations, and the cage siloxane structure on the strengthening agent And the organic silicon molecular mesh molecular chain can play a role in making. After the precursor and lithium salt are compounded and sintered into the cathode material, the modifier in it is carbonized at high temperature, which can produce a good production of the cathode material. It effectively prevents the collapse of the electrode structure during the cycle, prevents the battery capacity from rapidly declining, and thereby increases the service life of the battery.

Description

A kind of single crystal lithium nickel cobalt manganate precursor and preparation method

Technical field

The invention relates to the technical field of new energy material preparation, and in particular to a single crystal lithium nickel cobalt manganate precursor and a preparation method.

Background technique

Lithium-ion battery is a new type of green energy and has long been a focus of attention from all walks of life. With the further development of science and technology, lithium-ion batteries are gradually being used in large-capacity battery fields such as power and energy storage. Recently, from the aspects of safety and battery cost, it is generally accepted internationally that lithium iron phosphate is the best cathode material for new high-energy power batteries, and is the most promising lithium-ion battery cathode material for application in high-power power batteries; However, the tap density of this material is small and the low-temperature performance is poor. The volume of the same capacity is significantly larger than that of other batteries. It has no advantage in the field of micro batteries. However, lithium nickel cobalt manganate combines the advantages of lithium nickel oxide and lithium cobalt oxide, and It is easy to synthesize, low in price, and can be used in small batteries and power batteries. Although its market share is limited, its development momentum is obvious. As an important component of the positive electrode of lithium batteries, the monocrystalline lithium nickel cobalt manganate precursor has a stable structure and has become the key to the service life of the battery.

Contents of the invention

The purpose of the present invention is to provide a single crystal nickel cobalt lithium manganate precursor and a preparation method, which solves the problem that the cathode material prepared from the single crystal nickel cobalt lithium manganate precursor is prone to collapse at the present stage.

The object of the present invention can be achieved through the following technical solutions:

A method for preparing a single crystal lithium nickel cobalt manganate precursor, specifically including the following steps:

Step A1: Use nickel nitrate hexahydrate, cobalt nitrate hexahydrate and manganese nitrate solution as raw materials, and dissolve them in deionized water in a ratio of nickel: cobalt: manganese = 1:1:1 according to the amount of cationic substances. Metal cation mixture;

Step A2: Mix the metal cation mixture and the sodium hydroxide solution evenly, add ammonia water to adjust the pH value to 10.5-11.5, add the strengthening agent and DMF at a rotation speed of 200-300r/min and a temperature of 70-80°C. , carry out the reaction for 20-24h, add deionized water, let it stand and filter to remove the filtrate, and dry the substrate at a temperature of 140-150°C for 20-25h to obtain a single crystal lithium nickel cobalt manganate precursor.

Further, the volume ratio of the metal cation mixture and the sodium hydroxide solution described in step A2 is 1:1, and the concentration of the sodium hydroxide solution is 2.2 mol/L.

Further, the reinforcing agent is made by the following steps:

Step B1: Mix diphenyldichlorosilane and deionized water, stir for 10-15 minutes at a rotation speed of 200-300r/min and a temperature of 60-70°C, then add concentrated sulfuric acid and 1,1,3, 3-Tetramethyldisiloxane, after reacting for 4-6 hours, adjust the pH to neutral to obtain hydrogen-terminated polysiloxane. Mix pentaerythritol, acrylic acid, p-toluenesulfonic acid and DMF evenly, and stir at a rotating speed Under the conditions of 150-200r/min and temperature 110-120℃, carry out the reaction for 6-8h to obtain the reinforced monomer;

Step B2: Mix hydrogen-terminated polysiloxane, reinforcing monomer and DMF evenly, stir and add chloroplatinic acid at a rotation speed of 150-200r/min and a temperature of 50-60°C, and react for 10-15 hours. Finally, add KH570 and continue the reaction for 8-10h to obtain the modified monomer. Mix the modified monomer, KH560, tetramethylammonium hydroxide aqueous solution and DMF evenly at a rotating speed of 200-300r/min and a temperature of 25 Under the condition of -30℃, stir for 20-24h, raise the temperature to 60-70℃, react for 4-6h, then age for 7 days, filter and remove the filtrate to prepare the modifier;

Step B3: Dissolve the modifier in DMF, add polyvinyl alcohol and sodium hydroxide, react at a rotation speed of 150-200r/min and a temperature of 25-30°C for 6-8 hours, and adjust the pH value to 1 -2, raise the temperature to 85-90°C, add methyl acetoacetate, react for 4-6 hours, distill away DMF, add deionized water to filter to remove the filtrate, and dry the substrate to prepare the enhancer.

Further, the usage ratio of diphenyldichlorosilane, deionized water and 1,1,3,3-tetramethyldisiloxane described in step B1 is 1mmol:20mL:2mmol, and the usage ratio of concentrated sulfuric acid is diphenyldichlorosilane. 1-3% of the mass sum of chlorosilane and 1,1,3,3-tetramethyldisiloxane, the molar ratio of pentaerythritol and acrylic acid is 1:4, and the amount of p-toluenesulfonic acid is the mass of pentaerythritol and acrylic acid and 3%.

Further, the molar ratio of hydrogen-terminated polysiloxane, reinforcing monomer and KH570 described in step B2 is 4:1:4, and the molar ratio of chloroplatinic acid in hydrogen-terminated polysiloxane, reinforcing monomer, DMF, chloroplatinic acid and KH570 The concentration in the mixed system is 15-20ppm, the dosage ratio of modified monomer, KH560 and tetramethylammonium hydroxide aqueous solution is 10mmol:100mmol:40mL, and the mass fraction of tetramethylammonium hydroxide aqueous solution is 25%.

Further, the usage ratio of the modifier, polyvinyl alcohol and methyl acetoacetate described in step B3 is 0.2g:5g:12.5mL, and the molecular weight of polyvinyl alcohol is 16000-20000.

Beneficial effects of the present invention: A single crystal lithium nickel cobalt manganate precursor prepared by the present invention is evenly mixed with a metal cation mixture and a sodium hydroxide solution, ammonia is added to adjust the pH to alkaline, and then modifiers and DMF are added. After the reaction, add deionized water, let it stand and filter to remove the filtrate, and dry the substrate to obtain it. The modifier is hydrolyzed with diphenyldichlorosilane as the raw material, and then mixed with 1,1,3,3-tetramethyldisilane. Polymerize oxane to form hydrogen-terminated polysiloxane, esterify pentaerythritol with acrylic acid to obtain reinforced monomer, and combine hydrogen-terminated polysiloxane and reinforced monomer with chloroplatinic acid to form hydrogen-terminated polysiloxane. The Si-H bond on the alkane reacts with the double bond on the strengthening monomer, and then the remaining Si-H bond of KH570 is used to react to obtain the modified monomer. The modified monomer and KH560 are hydrolyzed and polymerized. The ends of the body form a cage structure and contain epoxy groups to prepare a modifier. The modifier is reacted with polyvinyl alcohol so that the epoxy groups on the modifier react with part of the hydroxyl groups on the polyvinyl alcohol, and then It is transesterified with methyl acetoacetate and then introduces diacetyl groups to prepare a strengthening agent. The diacetyl group and acetamide group on the strengthening agent can complex with metal cations, and at the same time, the cage siloxane on the strengthening agent The structure and the mesh-like molecular chain of organic silicon molecules can play a role in manufacturing. After the precursor and lithium salt are compounded and sintered into the cathode material, the modifier in it is carbonized at high temperature, which can produce good manufacturing results for the cathode material. , effectively prevent the collapse of the electrode structure during the cycle, prevent the rapid decline of battery capacity, and thereby increase the service life of the battery.

Detailed ways

The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

Example 1

A method for preparing a single crystal lithium nickel cobalt manganate precursor, specifically including the following steps:

Step A1: Use nickel nitrate hexahydrate, cobalt nitrate hexahydrate and manganese nitrate solution as raw materials, and dissolve them in deionized water in a ratio of nickel: cobalt: manganese = 1:1:1 according to the amount of cationic substances. Metal cation mixture;

Step A2: Mix the metal cation mixture and the sodium hydroxide solution evenly, add ammonia water to adjust the pH value to 10.5, add the enhancer and DMF at a rotation speed of 200r/min and a temperature of 70°C, react for 20h, and add deionized water, let it stand and filter to remove the filtrate, and dry the substrate at a temperature of 140°C for 20 hours to prepare a single crystal lithium nickel cobalt manganate precursor.

The volume ratio of the metal cation mixture and the sodium hydroxide solution described in step A2 is 1:1, and the concentration of the sodium hydroxide solution is 2.2 mol/L.

The strengthening agent is made by the following steps:

Step B1: Mix diphenyldichlorosilane and deionized water, stir for 10 minutes at a rotation speed of 200 r/min and a temperature of 60°C, then add concentrated sulfuric acid and 1,1,3,3-tetramethylbis Silicone, after reacting for 4 hours, adjust the pH to neutral to obtain hydrogen-terminated polysiloxane. Mix pentaerythritol, acrylic acid, p-toluenesulfonic acid and DMF evenly at a speed of 150r/min and a temperature of 110 Under the conditions of ℃, the reaction is carried out for 6 hours to obtain the reinforced monomer;

Step B2: Mix hydrogen-terminated polysiloxane, reinforcing monomer and DMF evenly, stir and add chloroplatinic acid at a rotation speed of 150r/min and a temperature of 50°C. After reacting for 10 hours, add KH570 and continue. React for 8 hours to obtain the modified monomer. Mix the modified monomer, KH560, tetramethylammonium hydroxide aqueous solution and DMF evenly, stir for 20 hours at a rotation speed of 200 r/min and a temperature of 25°C, and raise the temperature to 60°C, react for 4 hours, age for another 7 days, filter and remove the filtrate to prepare the modifier;

Step B3: Dissolve the modifier in DMF, add polyvinyl alcohol and sodium hydroxide, react for 6 hours at a rotation speed of 150 r/min and a temperature of 25°C, adjust the pH value to 1, and raise the temperature to 85°C. Add methyl acetoacetate and react for 4 hours. DMF is removed by distillation. Deionized water is added to filter to remove the filtrate. The substrate is dried to prepare the enhancer.

The usage ratio of diphenyldichlorosilane, deionized water and 1,1,3,3-tetramethyldisiloxane described in step B1 is 1mmol:20mL:2mmol, and the usage ratio of concentrated sulfuric acid is diphenyldichlorosilane. and 1% of the mass sum of 1,1,3,3-tetramethyldisiloxane, the molar ratio of pentaerythritol and acrylic acid is 1:4, and the amount of p-toluenesulfonic acid is 3% of the mass sum of pentaerythritol and acrylic acid .

The molar ratio of hydrogen-terminated polysiloxane, reinforcing monomer and KH570 described in step B2 is 4:1:4, and chloroplatinic acid is in the mixed system of hydrogen-terminated polysiloxane, reinforcing monomer, DMF, chloroplatinic acid and KH570 The concentration in is 15ppm, the dosage ratio of modified monomer, KH560 and tetramethylammonium hydroxide aqueous solution is 10mmol:100mmol:40mL, and the mass fraction of tetramethylammonium hydroxide aqueous solution is 25%.

The usage ratio of the modifier, polyvinyl alcohol and methyl acetoacetate described in step B3 is 0.2g:5g:12.5mL, and the molecular weight of polyvinyl alcohol is 16,000.

Example 2

A method for preparing a single crystal lithium nickel cobalt manganate precursor, specifically including the following steps:

Step A1: Use nickel nitrate hexahydrate, cobalt nitrate hexahydrate and manganese nitrate solution as raw materials, and dissolve them in deionized water in a ratio of nickel: cobalt: manganese = 1:1:1 according to the amount of cationic substances. Metal cation mixture;

Step A2: Mix the metal cation mixture and the sodium hydroxide solution evenly, add ammonia water to adjust the pH value to 11, add the enhancer and DMF at a rotation speed of 200r/min and a temperature of 75°C, react for 22h, and add deionized water, let it stand and filter to remove the filtrate, and dry the substrate at a temperature of 145°C for 23 hours to prepare a single crystal lithium nickel cobalt manganate precursor.

The volume ratio of the metal cation mixture and the sodium hydroxide solution described in step A2 is 1:1, and the concentration of the sodium hydroxide solution is 2.2 mol/L.

The strengthening agent is made by the following steps:

Step B1: Mix diphenyldichlorosilane and deionized water, stir for 13 minutes at a rotation speed of 200 r/min and a temperature of 65°C, then add concentrated sulfuric acid and 1,1,3,3-tetramethylbis Silicone, after reacting for 5 hours, adjust the pH to neutral to obtain hydrogen-terminated polysiloxane. Mix pentaerythritol, acrylic acid, p-toluenesulfonic acid and DMF evenly at a speed of 150r/min and a temperature of 115 Under the conditions of ℃, the reaction is carried out for 7 hours to obtain the reinforced monomer;

Step B2: Mix hydrogen-terminated polysiloxane, reinforcing monomer and DMF evenly, stir and add chloroplatinic acid at a rotation speed of 150r/min and a temperature of 55°C. After reacting for 10-15h, add KH570 , continue the reaction for 9 hours to obtain the modified monomer. Mix the modified monomer, KH560, tetramethylammonium hydroxide aqueous solution and DMF evenly. Stir for 22 hours at a rotation speed of 200 r/min and a temperature of 28°C. Raise the temperature to 65°C, react for 5 hours, age for another 7 days, filter and remove the filtrate to prepare the modifier;

Step B3: Dissolve the modifier in DMF, add polyvinyl alcohol and sodium hydroxide, react for 7 hours at a rotation speed of 150 r/min and a temperature of 28°C, adjust the pH value to 2, and raise the temperature to 88°C. Add methyl acetoacetate and react for 5 hours. DMF is removed by distillation. Deionized water is added to filter to remove the filtrate. The substrate is dried to prepare the enhancer.

The usage ratio of diphenyldichlorosilane, deionized water and 1,1,3,3-tetramethyldisiloxane described in step B1 is 1mmol:20mL:2mmol, and the usage ratio of concentrated sulfuric acid is diphenyldichlorosilane. and 2% of the mass sum of 1,1,3,3-tetramethyldisiloxane, the molar ratio of pentaerythritol and acrylic acid is 1:4, and the amount of p-toluenesulfonic acid is 3% of the mass sum of pentaerythritol and acrylic acid .

The molar ratio of hydrogen-terminated polysiloxane, reinforcing monomer and KH570 described in step B2 is 4:1:4, and chloroplatinic acid is in the mixed system of hydrogen-terminated polysiloxane, reinforcing monomer, DMF, chloroplatinic acid and KH570 The concentration in is 18ppm, the dosage ratio of modified monomer, KH560 and tetramethylammonium hydroxide aqueous solution is 10mmol:100mmol:40mL, and the mass fraction of tetramethylammonium hydroxide aqueous solution is 25%.

The usage ratio of the modifier, polyvinyl alcohol and methyl acetoacetate described in step B3 is 0.2g:5g:12.5mL, and the molecular weight of polyvinyl alcohol is 18,000.

Example 3

A method for preparing a single crystal lithium nickel cobalt manganate precursor, specifically including the following steps:

Step A1: Use nickel nitrate hexahydrate, cobalt nitrate hexahydrate and manganese nitrate solution as raw materials, and dissolve them in deionized water in a ratio of nickel: cobalt: manganese = 1:1:1 according to the amount of cationic substances. Metal cation mixture;

Step A2: Mix the metal cation mixture and the sodium hydroxide solution evenly, add ammonia water to adjust the pH value to 11.5, add the enhancer and DMF at a rotation speed of 300r/min and a temperature of 80°C, react for 24 hours, and add deionized water, let it stand and filter to remove the filtrate, and dry the substrate at a temperature of 150°C for 25 hours to prepare a single crystal lithium nickel cobalt manganate precursor.

The volume ratio of the metal cation mixture and the sodium hydroxide solution described in step A2 is 1:1, and the concentration of the sodium hydroxide solution is 2.2 mol/L.

The strengthening agent is made by the following steps:

Step B1: Mix diphenyldichlorosilane and deionized water, stir for 15 minutes at a rotation speed of 300 r/min and a temperature of 70°C, then add concentrated sulfuric acid and 1,1,3,3-tetramethyldihydrogen. Silicone, after reacting for 6 hours, adjust the pH to neutral to obtain hydrogen-terminated polysiloxane. Mix pentaerythritol, acrylic acid, p-toluenesulfonic acid and DMF evenly at a speed of 200r/min and a temperature of 120 Under the conditions of ℃, carry out the reaction for 8 hours to obtain the reinforced monomer;

Step B2: Mix hydrogen-terminated polysiloxane, reinforcing monomer and DMF evenly. Stir and add chloroplatinic acid at a rotation speed of 200 r/min and a temperature of 60°C. After the reaction for 15 hours, add KH570 and continue. React for 10 hours to obtain the modified monomer. Mix the modified monomer, KH560, tetramethylammonium hydroxide aqueous solution and DMF evenly, stir for 24 hours at a rotation speed of 300 r/min and a temperature of 30°C, and raise the temperature to 70°C, react for 6 hours, age for another 7 days, filter and remove the filtrate to prepare the modifier;

Step B3: Dissolve the modifier in DMF, add polyvinyl alcohol and sodium hydroxide, react for 8 hours at a rotation speed of 200 r/min and a temperature of 30°C, adjust the pH value to 2, and raise the temperature to 90°C. Add methyl acetoacetate and react for 6 hours. DMF is removed by distillation. Deionized water is added to filter to remove the filtrate. The substrate is dried to prepare the enhancer.

The usage ratio of diphenyldichlorosilane, deionized water and 1,1,3,3-tetramethyldisiloxane described in step B1 is 1mmol:20mL:2mmol, and the usage ratio of concentrated sulfuric acid is diphenyldichlorosilane. and 3% of the mass sum of 1,1,3,3-tetramethyldisiloxane, the molar ratio of pentaerythritol and acrylic acid is 1:4, and the amount of p-toluenesulfonic acid is 3% of the mass sum of pentaerythritol and acrylic acid .

The molar ratio of hydrogen-terminated polysiloxane, reinforcing monomer and KH570 described in step B2 is 4:1:4, and chloroplatinic acid is in the mixed system of hydrogen-terminated polysiloxane, reinforcing monomer, DMF, chloroplatinic acid and KH570 The concentration in is 20ppm, the dosage ratio of modified monomer, KH560 and tetramethylammonium hydroxide aqueous solution is 10mmol:100mmol:40mL, and the mass fraction of tetramethylammonium hydroxide aqueous solution is 25%.

The usage ratio of the modifier, polyvinyl alcohol and methyl acetoacetate described in step B3 is 0.2g:5g:12.5mL, and the molecular weight of polyvinyl alcohol is 20,000.

Comparative example 1

Compared with Example 1, no strengthening agent was added in this comparative example, and the remaining steps were the same.

Comparative example 2

Compared with Example 1, this comparative example uses a modifier instead of a strengthening agent, and the remaining steps are the same.

Comparative example 3

Compared with Example 1, this comparative example is used to add reinforcing monomer, and the remaining steps are the same.

The precursor prepared in Example 1-3 and Comparative Example 1-3 was used as the battery positive electrode, acetylene black was used as the conductive agent, and the polytetrafluoroethylene emulsion was used as the adhesive in a mass ratio of 86:11:8, and then pressed The positive electrode sheet was made from the sheet, and the metallic lithium was used as the battery negative electrode sheet. The separator was a lithium battery separator produced by Chongqing Yuntianhua Niumi Technology Co., Ltd., with a concentration of 1.2 mol/L LiPF ₆ /EC+DMC (EC, DMC). A simple battery was made from a solution with a volume ratio of 1:1), and the constant current charge and discharge test was carried out at room temperature with a rate of 0.2 C (32 mA/g) in the voltage range of 2.8 to 4.3 V, and the cycle was 30 and 50 times. and 100 times to observe whether the structure of the cathode material collapses. The test results are shown in the table below.

It can be seen from the above table that the present application has the effect of protecting the positive electrode material from collapse.

The above contents are only examples and explanations of the concept of the invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or substitute them in similar ways, as long as they do not deviate from the concept of the invention. or beyond the scope defined by the claims, shall belong to the protection scope of the present invention.

Claims (7)

1. A preparation method of a monocrystal nickel cobalt lithium manganate precursor is characterized by comprising the following steps of: the method specifically comprises the following steps:

step A1: taking nickel nitrate hexahydrate, cobalt nitrate hexahydrate and manganese nitrate solution as raw materials, and dissolving the raw materials in deionized water according to the mass ratio of positive ions of nickel to cobalt to manganese=1:1:1 to prepare a metal positive ion mixed solution;

step A2: and uniformly mixing the metal cation mixed solution with a sodium hydroxide solution, adding ammonia water to adjust the pH value to be alkaline, adding an enhancer and DMF (dimethyl formamide), reacting, adding deionized water, standing, filtering to remove filtrate, and drying a substrate to obtain the monocrystal nickel cobalt lithium manganate precursor.

2. The method for preparing a monocrystal nickel cobalt lithium manganate precursor according to claim 1, which is characterized in that: the volume ratio of the metal cation mixed solution to the sodium hydroxide solution in the step A2 is 1:1.

3. The method for preparing a monocrystal nickel cobalt lithium manganate precursor according to claim 1, which is characterized in that: the reinforcing agent is prepared by the following steps:

step B1: after mixing and stirring diphenyl dichlorosilane and deionized water, adding concentrated sulfuric acid and 1, 3-tetramethyl disiloxane, reacting, adjusting pH to be neutral to obtain hydrogen-terminated polysiloxane, and mixing pentaerythritol, acrylic acid, p-toluenesulfonic acid and DMF for reacting to obtain a reinforced monomer;

step B2: mixing and stirring hydrogen-terminated polysiloxane, a reinforcing monomer and DMF, adding chloroplatinic acid, reacting, adding KH570, continuing to react to obtain a modified monomer, mixing and stirring the modified monomer, KH560, an aqueous solution of tetramethylammonium hydroxide and DMF, heating to continue the reaction, aging, filtering to remove filtrate, and obtaining the modifier;

step B3: dissolving the modifier in DMF, adding polyvinyl alcohol and sodium hydroxide for reaction, adjusting pH to be acidic, heating, adding methyl acetoacetate for reaction, distilling to remove DMF, adding deionized water for filtration to remove filtrate, and drying a substrate to obtain the enhancer.

4. A method for preparing a single crystal lithium nickel cobalt manganate precursor according to claim 3, wherein: the dosage ratio of the diphenyldichlorosilane to the deionized water to the 1, 3-tetramethyl disiloxane in the step B1 is 1mmol to 20mL to 2mmol, the dosage of the concentrated sulfuric acid is 1-3% of the sum of the mass of the diphenyldichlorosilane and the mass of the 1, 3-tetramethyl disiloxane, the molar ratio of the pentaerythritol to the acrylic acid is 1:4, and the dosage of the p-toluenesulfonic acid is 3% of the sum of the mass of the pentaerythritol and the mass of the acrylic acid.

5. A method for preparing a single crystal lithium nickel cobalt manganate precursor according to claim 3, wherein: the molar ratio of the hydrogen-terminated polysiloxane to the reinforcing monomer to the KH570 in the step B2 is 4:1:4, the concentration of chloroplatinic acid in the mixed system of the hydrogen-terminated polysiloxane, the reinforcing monomer, DMF, chloroplatinic acid and KH570 is 15-20ppm, and the dosage ratio of the modifying monomer to the aqueous solution of KH560 to the aqueous solution of tetramethylammonium hydroxide is 10mmol to 100mmol to 40mL.

6. A method for preparing a single crystal lithium nickel cobalt manganate precursor according to claim 3, wherein: the dosage ratio of the modifier to the polyvinyl alcohol to the methyl acetoacetate in the step B3 is 0.2g to 5g to 12.5mL, and the molecular weight of the polyvinyl alcohol is 16000-20000.

7. A single crystal nickel cobalt lithium manganate precursor characterized by: the preparation method according to any one of claims 1-6.