Positive electrode material precursor, preparation method therefor, and use thereof

Abstract

Provided in the present disclosure are a positive electrode material precursor, a preparation method therefor, and the use thereof. The preparation method comprises: mixing a glycine buffer solution containing ethylene glycol with a metal source, and reacting same to obtain the positive electrode material precursor. The present disclosure uses the glycine buffer solution as a reaction substrate solution, and adds the metal source to same for reaction, thereby keeping the pH of the system stable, and improving the uniformity and purity of the metal element. In addition, by means of a synergistic effect between glycine and ethylene glycol, interfacial energy of different crystal planes of the precursor particles can be effectively regulated, thereby regulating the growth and arrangement modes of the precursor particles to enable precipitated particles to preferentially grow in the orientation of (003) crystal planes, so as to obtain elongated strip-shaped primary particles, which can provide a rapid diffusion channel for lithium ions, reduces the diffusion resistance of Li+ and improves the orderliness of the crystal structure, thereby improving the rate capability and the cycling stability of the positive electrode material.

Description

A positive electrode material precursor and its preparation method and use Technical Field

[0001] The present disclosure belongs to the field of batteries and relates to a positive electrode material precursor and a preparation method and use thereof. Background Art

[0002] With the rapid development of new energy vehicles, the demand for lithium-ion secondary batteries has increased dramatically, leading to a significant increase in the demand for cathode materials. Nickel-cobalt-manganese or nickel-cobalt-aluminum ternary layered cathode materials have become the most in-demand cathode materials in the market due to their high energy density, wide operating temperature and voltage ranges, no memory effect, and long cycle life. They are widely used in digital products and power tools, and are considered the ideal power source for the next generation of electric vehicles.

[0003] However, current applications of nickel-cobalt-manganese ternary cathode materials, particularly in power batteries, still present some drawbacks and issues. For example, the cation mixing effect results in low initial charge and discharge efficiency (generally <90%) and poor cycling performance. Furthermore, the low diffusion coefficient and electronic conductivity of nickel-cobalt-manganese ternary cathode materials make their rate performance less than ideal.

[0004] CN114804233A discloses a high-nickel ternary positive electrode material for lithium batteries. Its preparation method is to ball-mill and refine the nickel source, cobalt source and manganese source respectively, and put them into a high-speed mixer for thorough mixing to obtain a first precursor mixture; add a conventional lithium source to the first precursor mixture and mix them thoroughly, then transfer them to a ball mill for ball milling activation to obtain a second precursor mixture; add an oxidizing lithium source to the second precursor mixture, ball mill and mix them evenly, and sinter the mixture in an oxygen atmosphere in stages to obtain a high-nickel ternary positive electrode material. It introduces the means of precursor preparation and ball milling activation, and at the same time, introduces an oxidizing lithium source, and a staged sintering system in an oxygen atmosphere, which greatly reduces the material Li + / Ni 2+ The degree of mixing effectively inhibits the cation mixing effect, thereby improving the various properties of the material to a certain extent.

[0005] CN112701276A discloses a quaternary polycrystalline positive electrode material, the positive electrode material includes a main body and a dopant, the dopant is uniformly doped into the main body, wherein the main body is a quaternary nickel-cobalt-manganese-aluminum, the dopant includes selenium oxide and calcium oxide, and Se / Ca is uniformly doped into the material main body, thereby enhancing the structural stability of the layered positive electrode material and reducing Li + / Ni 2+ Cation mixing effect, inhibiting O 2-The oxidation process to O2 is inhibited and the phase transition of the material from delamination to spinel is hindered to a certain extent, thereby improving the electrochemical performance of the positive electrode material.

[0006] It can be seen that inhibiting or avoiding the cation mixing effect is an effective mechanism for optimizing ternary or quaternary positive electrode materials. Therefore, developing and researching new solutions is of great significance for improving the performance of batteries containing ternary or quaternary positive electrode materials.

[0007] Summary of the Invention

[0008] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0009] In view of the problems existing in the prior art, the purpose of the present disclosure is to provide a cathode material precursor and its preparation method and use. The preparation method mixes a glycine buffer solution containing ethylene glycol with a metal source and reacts to obtain a cathode material precursor. The present disclosure uses a glycine buffer solution as a reaction base liquid, adds a metal source thereto to react, so as to maintain the pH stability of the system and improve the uniformity and purity of the metal elements; utilizes the synergistic effect of glycine and ethylene glycol to effectively adjust the interfacial energy of different crystal faces of the precursor particles, thereby adjusting the growth and arrangement of the precursor particles, so that the precipitated particles preferentially grow along the (003) crystal plane orientation, thereby obtaining a long strip of particles, which can provide a rapid diffusion channel for lithium ions and reduce Li + diffusion resistance, and improve the orderliness of the crystal structure, thereby improving the rate performance and cycle stability of the positive electrode material.

[0010] To achieve this goal, the present disclosure adopts the following technical solutions:

[0011] In a first aspect, the present disclosure provides a method for preparing a cathode material precursor, the preparation method comprising:

[0012] A glycine buffer solution containing ethylene glycol is mixed with a metal source and reacted to obtain a cathode material precursor.

[0013] Due to the layered structure characteristics of ternary or quaternary materials, Li + The embedding and extraction channels are perpendicular to the (010) crystal plane. + The diffusion is faster in the highly active (100) and (010) crystal planes. If the crystal is grown along the (003) direction (i.e., the c-axis direction), Li + The diffusion distance is shorter. Therefore, increasing the (010) crystal surface area can effectively increase the Li + The probability of embedding and ejecting can improve the Li +The conductivity of the nickel-cobalt-manganese or nickel-cobalt-aluminum or nickel-cobalt-manganese-aluminum layered cathode materials is improved, thereby improving the electrochemical performance of the nickel-cobalt-manganese or nickel-cobalt-aluminum or nickel-cobalt-manganese-aluminum layered cathode materials. Since there is a certain degree of inheritance between the (010) crystal plane area of ​​the nickel-cobalt-manganese or nickel-cobalt-aluminum or nickel-cobalt-manganese-aluminum layered cathode materials and the (010) crystal plane area of ​​their precursors, the nickel-cobalt-manganese or nickel-cobalt-aluminum or nickel-cobalt-manganese-aluminum layered cathode material precursors with large (010) crystal plane areas can be used to improve the (010) crystal plane area of ​​the ternary or quaternary cathode materials.

[0014] To this end, the present invention discloses preparing a positive electrode precursor by first preparing a glycine buffer solution and then adding a salt solution containing nickel, cobalt, manganese, etc. for co-precipitation. Through this specific mixing order, that is, using a buffer solution as the precipitation reaction base liquid instead of mixing all relevant raw materials at the same time, the pH value of the solution system during the precipitation process can be kept stable, the formed precursor particles can be made more uniform, and the pH value of the reaction system can be prevented from changing too drastically, resulting in the occurrence of side reactions, thereby improving the purity of the ternary or quaternary hydroxide precursor.

[0015] Furthermore, glycine has both acidic -COOH and basic functional groups -NH2, which can be ionized in water, have strong hydrophilicity and chelation, can complex nickel ions, and improve the stability of nickel ions in solution. The nickel ions complexed by glycine will repel water molecules, thereby promoting the desolvation process of hydrated nickel ions, reducing the nucleation energy barrier, and limiting the diffusion of nickel ions, preferentially forming nickel hydroxide, and then gradually adsorbing other metal elements, such as cobalt and manganese to form nickel-cobalt-manganese composite hydroxide. In this process, the hydroxide will be highlighted. The growth advantage crystal plane of nickel is (101), and the hydrogen bond and chelation of ethylene glycol can cover the (001) crystal plane during the formation of the precursor, thereby exposing the more active (010) crystal plane. Therefore, the synergistic effect of glycine and ethylene glycol can effectively regulate the interfacial energy of different crystal planes of the precursor particles, thereby regulating the growth and arrangement of the precursor particles, so that the precipitated particles grow preferentially along the (003) crystal plane orientation. The long strip particles grown along the (003) crystal plane orientation can provide a fast diffusion channel for lithium ions, reducing Li + Diffusion resistance, as well as improving the order of the crystal structure, thereby improving the rate performance and cycle stability of the material. In addition, the high viscosity of ethylene glycol can delay the nucleation of the precursor and prevent the agglomeration of particles, thereby achieving the purpose of refining primary particles.

[0016] The following are optional technical solutions of the present disclosure, but are not intended to limit the technical solutions provided by the present disclosure. Through the following technical solutions, the technical objectives and beneficial effects of the present disclosure can be better achieved and realized.

[0017] As an optional technical solution of the present disclosure, the preparation method includes: first preparing a glycine buffer solution, then adding ethylene glycol and mixing, and then adding a metal source and mixing.

[0018] Optionally, the method for preparing the glycine buffer comprises mixing a glycine solution with an alkali metal hydroxide solution.

[0019] Optionally, the concentration of the glycine solution is 0.15 to 0.25 mol / L, for example, 0.15 mol / L, 0.16 mol / L, 0.17 mol / L, 0.18 mol / L, 0.19 mol / L, 0.2 mol / L, 0.21 mol / L, 0.22 mol / L, 0.23 mol / L, 0.24 mol / L or 0.25 mol / L, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0020] Optionally, the alkali metal hydroxide solution comprises sodium hydroxide and / or potassium hydroxide.

[0021] Optionally, the concentration of the alkali metal hydroxide solution is 0.15 to 0.25 mol / L, for example, 0.15 mol / L, 0.16 mol / L, 0.17 mol / L, 0.18 mol / L, 0.19 mol / L, 0.2 mol / L, 0.21 mol / L, 0.22 mol / L, 0.23 mol / L, 0.24 mol / L or 0.25 mol / L, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0022] Optionally, the volume ratio of the glycine solution to the alkali metal hydroxide solution is 1:(1-1.6), for example, 1:1, 1:15, 1:2, 1:25, 1:3, 1:35, 1:4, 1:45, 1:5, 1:55 or 1:6, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0023] Optionally, the pH of the glycine buffer is 10.8 to 12, such as 10.8, 11, 11.2, 11.4, 11.6, 11.8 or 12, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0024] As an optional technical solution of the present disclosure, the metal source includes at least three metal elements.

[0025] Optionally, the metal source is added dropwise in a salt solution into a glycine buffer solution containing ethylene glycol for mixing.

[0026] Optionally, the dripping speed of the saline solution is 2 to 5 mL / min, for example, 2 mL / min, 2.3 mL / min, 2.6 mL / min, 2.9 mL / min, 3.2 mL / min, 3.5 mL / min, 3.8 mL / min, 4.1 mL / min, 4.4 mL / min, 4.7 mL / min or 5 mL / min, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0027] Optionally, the ratio of the total volume of the salt solution to the volume of the glycine buffer containing ethylene glycol is 1:(20-40), for example, 1:20, 1:22, 1:24, 1:26, 1:28, 1:30, 1:32, 1:34, 1:36, 1:38 or 1:40, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0028] Optionally, the metal source includes soluble salts of Ni, Co and Mn, or soluble salts of Ni, Co and Al, or soluble salts of Ni, Co, Mn and Al.

[0029] Optionally, the soluble salt includes any one of sulfate, nitrate or chloride salts, or a combination of at least two of them. Typical but non-limiting examples of the combination include a combination of sulfate and nitrate, a combination of sulfate and chloride, or a combination of chloride and nitrate.

[0030] Optionally, the salt solution is prepared according to a molar ratio of Ni:Co:Mn or Ni:Co:Al or Ni:Co:(Mn+Al) of a:b:c, wherein a+b+c=1, a≥0.6, such as 0.6, 0.64, 0.68, 0.72, 0.76, 0.8, 0.84, 0.88, 0.92, 0.96 or 0.98, and b≤0.2, such as 0.2, 0.18, 0.16, 0.14, 0.12, 0.1, 0.08, 0.06, 0.04, 0.02 or 0.01, etc., c≤0.2, for example, 0.2, 0.18, 0.16, 0.14, 0.12, 0.1, 0.08, 0.06, 0.04, 0.02 or 0.01, etc., but are not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0031] Optionally, the total concentration of metal ions in the salt solution is 0.1 to 3 mol / L, for example, 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.8 mol / L, 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.6 mol / L, 2.8 mol / L or 3 mol / L, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0032] As an optional technical solution of the present invention, the amount of ethylene glycol used is 1% to 5% of the mass of the salt solution, for example, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, 3%, 3.2%, 3.4%, 3.6%, 3.8%, 4%, 4.2%, 4.4%, 4.6%, 4.8% or 5%, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are equally applicable.

[0033] As an optional technical solution of the present invention, the reaction temperature is 40-80°C, for example, 40°C, 44°C, 48°C, 52°C, 56°C, 60°C, 64°C, 68°C, 72°C, 76°C or 80°C, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0034] Optionally, the stirring speed of the reaction is 300 to 900 rpm, for example, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm or 900 rpm, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0035] Optionally, the reaction is carried out under the protection of an inert gas.

[0036] As an optional technical solution of the present disclosure, after the reaction, the reaction product is aged, washed, filtered, dried and sieved in sequence to obtain a ternary precursor.

[0037] Optionally, the stirring speed of the aging is lower than the stirring speed of the reaction.

[0038] Optionally, the stirring speed of the aging is 100-500 rpm, for example, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm or 500 rpm, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0039] Optionally, the aging time is 4 to 48 hours, for example, 4 hours, 8 hours, 12 hours, 16 hours, 20 hours, 24 hours, 28 hours, 32 hours, 36 hours, 40 hours, 44 hours or 48 hours, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0040] Optionally, the washing liquid comprises an alkali metal hydroxide solution.

[0041] Optionally, the drying temperature is 60-150°C, for example, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0042] In a second aspect, the present disclosure provides a positive electrode material precursor obtained using the preparation method described in the first aspect.

[0043] In a third aspect, the present disclosure provides a method for manufacturing a positive electrode material, the manufacturing method comprising:

[0044] The lithium source is mixed with the cathode material precursor described in the second aspect, and sintered to obtain the cathode material.

[0045] As an optional technical solution disclosed in the present invention, the ratio of the total molar amount of the metal elements in the positive electrode material precursor to the molar amount of the lithium source is 1:(1.01~1.10), for example, 1:1.01, 1:1.02, 1:1.03, 1:1.04, 1:1.05, 1:1.06, 1:1.07, 1:1.08, 1:1.09 or 1:1.10, etc., but is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0046] Optionally, the sintering is performed in an oxygen-containing atmosphere.

[0047] Optionally, the sintering temperature is 750-950°C, for example, 750°C, 770°C, 790°C, 810°C, 830°C, 850°C, 870°C, 890°C, 910°C, 930°C or 950°C, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0048] Optionally, the sintering time is 8 to 15 hours, such as 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours or 15 hours, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0049] In a fourth aspect, the present disclosure provides a positive electrode material obtained using the manufacturing method described in the third aspect.

[0050] In a fifth aspect, the present disclosure provides a battery comprising the positive electrode material described in the fourth aspect.

[0051] Compared with the existing technical solutions, the present disclosure has at least the following beneficial effects:

[0052] The present invention uses glycine buffer as a reaction base liquid, and adds a metal source thereto to react, so as to maintain the pH stability of the system and improve the uniformity and purity of the metal elements; the synergistic effect of glycine and ethylene glycol can effectively adjust the interface energy of different crystal faces of the precursor particles, thereby adjusting the growth and arrangement of the precursor particles, so that the precipitated particles preferentially grow along the (003) crystal plane orientation, thereby obtaining a long strip of particles, which can provide a fast diffusion channel for lithium ions and reduce Li + diffusion resistance, and improve the orderliness of the crystal structure, thereby improving the rate performance and cycle stability of the positive electrode material.

[0053] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0055] FIG1 is a SEM image of the cathode material precursor obtained in Example 1;

[0056] FIG2 is a SEM image of the positive electrode material precursor obtained in Comparative Example 1. DETAILED DESCRIPTION

[0057] The technical solution of the present disclosure is further illustrated below through specific implementation methods.

[0058] It should be apparent to those skilled in the art that the embodiments are only intended to help understand the present disclosure and should not be considered as specific limitations of the present disclosure.

[0059] Example 1

[0060] This embodiment provides a method for manufacturing a positive electrode material, the manufacturing method comprising the following steps:

[0061] (1) Preparation of reaction base solution: Prepare 0.2 mol / L glycine solution and 0.2 mol / L sodium hydroxide solution, mix the glycine solution and the sodium hydroxide solution in a volume ratio of 1:1.3, control the pH to 11, and the resulting glycine-sodium hydroxide buffer solution is the reaction base solution;

[0062] (2) According to the molecular formula Ni 0.8 Co 0.1 Mn 0.1 (OH)2, that is, nickel sulfate, cobalt sulfate, and manganese sulfate are weighed and dissolved in deionized water in a molar ratio of 8:1:1 of the metal elements Ni, Co, and Mn to prepare a salt solution. The total concentration of nickel, cobalt, and manganese ions in the solution is 1.5 mol / L;

[0063] The reaction base liquid was placed in a reaction kettle, and ethylene glycol was added, and the amount of ethylene glycol was controlled to be 2.6% of the mass of the salt solution;

[0064] (3) nitrogen was introduced into the reactor, stirring was started at 600 r / min, and then the salt solution containing nickel, cobalt, and manganese was added to the reactor at a feed rate of 3 mL / min and reacted at 60°C for 10 h. The volume ratio of the salt solution containing nickel, cobalt, and manganese to the reaction base solution was controlled to be 1:30 at the reaction endpoint;

[0065] (4) After the reaction is completed, the feed is stopped and the mixture is aged at a speed of 300 r / min for 8 h. After the aging is completed, the mixture is washed with a 1 mol / L sodium hydroxide solution and dried at a temperature of 100° C. for 24 h to obtain a positive electrode material precursor;

[0066] (5) According to the total molar ratio of Ni, Co, and Mn in the positive electrode material precursor to the molar ratio of Li in the lithium salt being 1:1.05, the corresponding amount of positive electrode material precursor was weighed and mixed evenly with lithium carbonate, and then the mixture was sintered at 850 ° C for 12 h in an oxygen atmosphere to obtain LiNi 0.8 Co 0.1 Mn 0.1 O2 ternary positive electrode material.

[0067] Example 2

[0068] This embodiment provides a method for manufacturing a positive electrode material, the manufacturing method comprising the following steps:

[0069] (1) Preparation of reaction base solution: Prepare 0.2 mol / L glycine solution and 0.2 mol / L sodium hydroxide solution, mix the glycine solution and sodium hydroxide solution in a volume ratio of 1:1, and control the pH to 10.8. The resulting glycine-sodium hydroxide buffer solution is the reaction base solution;

[0070] (2) According to the molecular formula Ni 0.8 Co 0.1 Mn 0.1 (OH)2, that is, nickel sulfate, cobalt sulfate, and manganese sulfate are weighed and dissolved in deionized water in a molar ratio of 8:1:1 of the metal elements Ni, Co, and Mn to prepare a salt solution. The total concentration of nickel, cobalt, and manganese ions in the solution is 3 mol / L;

[0071] The reaction base liquid is placed in a reaction kettle, and ethylene glycol is added, and the amount of ethylene glycol is controlled to be 1% of the mass of the salt solution;

[0072] (3) nitrogen was introduced into the reactor, stirring was started at 300 r / min, and then the salt solution containing nickel, cobalt, and manganese was added to the reactor at a feed rate of 2 mL / min and reacted at 40°C for 15 h. The volume ratio of the salt solution containing nickel, cobalt, and manganese to the reaction base solution was controlled to be 1:20 at the reaction endpoint;

[0073] (4) After the reaction is completed, the feed is stopped and the mixture is aged at a speed of 100 r / min for 4 h. After the aging is completed, the mixture is washed with a 1 mol / L sodium hydroxide solution and dried at a temperature of 60° C. for 24 h to obtain a positive electrode material precursor;

[0074] (5) According to the total molar ratio of Ni, Co, and Mn in the positive electrode material precursor to the molar ratio of Li in the lithium salt being 1:1.01, the corresponding amount of positive electrode material precursor was weighed and mixed evenly with lithium carbonate, and then the mixture was sintered at 750 ° C for 15 h in an oxygen atmosphere to obtain LiNi 0.8 Co 0.1 Mn 0.1 O2 ternary positive electrode material.

[0075] Example 3

[0076] This embodiment provides a method for manufacturing a positive electrode material, the manufacturing method comprising the following steps:

[0077] (1) Preparation of reaction base solution: Prepare 0.2 mol / L glycine solution and 0.2 mol / L sodium hydroxide solution, mix the glycine solution and the sodium hydroxide solution in a volume ratio of 1:1.6, control the pH to 12, and the resulting glycine-sodium hydroxide buffer solution is the reaction base solution;

[0078] (2) According to the molecular formula Ni 0.8 Co 0.1 Mn 0.1 (OH)2, that is, nickel sulfate, cobalt sulfate, and manganese sulfate are weighed and dissolved in deionized water in a molar ratio of 8:1:1 of the metal elements Ni, Co, and Mn to prepare a salt solution. The total concentration of nickel, cobalt, and manganese ions in the solution is 0.1 mol / L;

[0079] The reaction base liquid is placed in a reaction kettle, and ethylene glycol is added, and the amount of ethylene glycol is controlled to be 5% of the mass of the salt solution;

[0080] (3) nitrogen was introduced into the reactor, stirring was started at 900 r / min, and then the salt solution containing nickel, cobalt, and manganese was added to the reactor at a feed rate of 5 mL / min and reacted at 80°C for 5 h. The volume ratio of the salt solution containing nickel, cobalt, and manganese to the reaction base solution was controlled to be 1:40 at the reaction endpoint;

[0081] (4) After the reaction is completed, the feed is stopped and the mixture is aged at a speed of 500 r / min for 48 h. After the aging is completed, the mixture is washed with a 1 mol / L sodium hydroxide solution and dried at a temperature of 150° C. for 24 h to obtain a positive electrode material precursor;

[0082] (5) According to the total molar ratio of Ni, Co, and Mn in the positive electrode material precursor to the molar ratio of Li in the lithium salt being 1:1.01, the corresponding amount of positive electrode material precursor was weighed and mixed evenly with lithium carbonate, and then the mixture was sintered at 950 ° C for 8 h in an oxygen atmosphere to obtain LiNi 0.8 Co 0.1 Mn 0.1 O2 ternary positive electrode material.

[0083] Example 4

[0084] This embodiment provides a method for manufacturing a positive electrode material. In the manufacturing method, in step (1), the amount of sodium hydroxide solution is adjusted so that the pH of the reaction base solution is adjusted from 11 to 10. Other than that, the other conditions are exactly the same as those in Example 1.

[0085] Example 5

[0086] This embodiment provides a method for manufacturing a positive electrode material. In the manufacturing method, in step (1), the amount of sodium hydroxide solution is adjusted so that the pH of the reaction base solution is adjusted from 11 to 10.8. Apart from this, other conditions are exactly the same as those in Example 1.

[0087] Example 6

[0088] This embodiment provides a method for manufacturing a positive electrode material. In the manufacturing method, in step (1), the amount of sodium hydroxide solution is adjusted so that the pH of the reaction base solution is adjusted from 11 to 12. Other than that, the other conditions are exactly the same as those in Example 1.

[0089] Example 7

[0090] This embodiment provides a method for manufacturing a positive electrode material. In the manufacturing method, in step (1), the amount of sodium hydroxide solution is adjusted so that the pH of the reaction base solution is adjusted from 11 to 12.8. Other than that, the other conditions are exactly the same as those in Example 1.

[0091] Example 8

[0092] This embodiment provides a method for manufacturing a positive electrode material. In the manufacturing method, in step (1), the concentration of glycine is adjusted from 0.2 mol / L to 0.1 mol / L. Other conditions are exactly the same as those in Example 1.

[0093] Example 9

[0094] This embodiment provides a method for manufacturing a positive electrode material. In the manufacturing method, in step (1), the concentration of glycine is adjusted from 0.2 mol / L to 0.15 mol / L. Other conditions are exactly the same as those in Example 1.

[0095] Example 10

[0096] This embodiment provides a method for manufacturing a positive electrode material. In the manufacturing method, in step (1), the concentration of glycine is adjusted from 0.2 mol / L to 0.25 mol / L. Other than that, the other conditions are exactly the same as those in Example 1.

[0097] Example 11

[0098] This embodiment provides a method for manufacturing a positive electrode material. In the manufacturing method, in step (1), the concentration of glycine is adjusted from 0.2 mol / L to 0.3 mol / L. Apart from this, other conditions are exactly the same as those in Example 1.

[0099] Example 12

[0100] This embodiment provides a method for manufacturing a positive electrode material. In the manufacturing method, in step (2), the amount of ethylene glycol is adjusted from 2.6% to 0.5%. Apart from this, other conditions are exactly the same as those in Example 1.

[0101] Example 13

[0102] This embodiment provides a method for manufacturing a positive electrode material. In the manufacturing method, in step (2), the amount of ethylene glycol is adjusted from 2.6% to 1%. Other than that, the other conditions are exactly the same as those in Example 1.

[0103] Example 14

[0104] This embodiment provides a method for manufacturing a positive electrode material. In the manufacturing method, in step (2), the amount of ethylene glycol is adjusted from 2.6% to 5%. Other conditions are exactly the same as those in Example 1.

[0105] Example 15

[0106] This embodiment provides a method for manufacturing a positive electrode material. In the manufacturing method, in step (2), the amount of ethylene glycol is adjusted from 2.6% to 5.5%. Other than that, the other conditions are exactly the same as those in Example 1.

[0107] Comparative Example 1

[0108] This comparative example provides a method for manufacturing a positive electrode material, which comprises the following steps:

[0109] (1) Prepare 2 mol / L sodium hydroxide solution as a precipitant and 2 mol / L ammonia water as a complexing agent;

[0110] (2) According to the molecular formula Ni 0.8 Co 0.1 Mn 0.1 (OH)2, that is, nickel sulfate, cobalt sulfate, and manganese sulfate are weighed and dissolved in deionized water in a molar ratio of 8:1:1 among the metal elements Ni, Co, and Mn to prepare a salt solution;

[0111] (3) nitrogen was introduced into the reactor, and sodium hydroxide solution, ammonia water, and a salt solution containing nickel, cobalt, and manganese were continuously introduced into the reactor in parallel. The feeding rate of the salt solution containing nickel, cobalt, and manganese and the ammonia water was 3 mL / min. The feeding rate of the sodium hydroxide solution was controlled to stabilize the pH value at 11. The reaction was carried out at a temperature of 60° C. and a stirring speed of 600 r / min for 10 h.

[0112] (4) After the reaction is completed, the feed is stopped and the mixture is aged at a speed of 300 r / min for 8 h. After the aging is completed, the mixture is washed with a 1 mol / L sodium hydroxide solution and dried at a temperature of 100° C. for 24 h to obtain a positive electrode material precursor;

[0113] (5) According to the total molar ratio of Ni, Co, and Mn in the positive electrode material precursor to the molar ratio of Li in the lithium salt of 1:1.05, the corresponding amount of precursor was weighed and mixed with lithium carbonate, and then the mixture was sintered at 850 ° C in an oxygen atmosphere for 12 hours to obtain LiNi 0.8 Co 0.1 Mn 0.1 O2 ternary positive electrode material.

[0114] Comparative Example 2

[0115] This comparative example provides a method for manufacturing a positive electrode material. In the manufacturing method, in step (2), ammonia water is used instead of ethylene glycol. Other than that, the other conditions are exactly the same as those in Example 1.

[0116] Comparative Example 3

[0117] This comparative example provides a method for manufacturing a positive electrode material. In step (1), glycine is not used, and only 0.2 mol / L sodium hydroxide solution is used as the reaction base liquid. Apart from this, other conditions are exactly the same as those in Example 1.

[0118] Comparative Example 4

[0119] This comparative example provides a method for manufacturing a positive electrode material. The manufacturing method keeps the amounts of glycine solution, sodium hydroxide solution, nickel sulfate, cobalt sulfate, manganese sulfate and ethylene glycol unchanged. After all the raw materials are mixed at the same time, stirring is started in a reactor at a stirring speed of 600 r / min, and the reaction is carried out at a temperature of 60°C for 10 hours, and then steps (4) and (5) are carried out. Other than this, the other conditions are exactly the same as those in Example 1.

[0120] Performance testing:

[0121] Scanning electron microscopy was used to analyze the morphology of the cathode material precursors obtained in Example 1 and Comparative Example 1. As shown in FIG1 , the precursor Ni obtained in Example 1 0.8 Co 0.1 Mn 0.1 The (OH)2 primary particles are thick and have a large (010) crystal plane area. The secondary particles are spherical with good dispersion, uniform particle size, and a dense interior. The precursor particle size is approximately 5.0 μm, and the primary particle length is 200-300 nm. As shown in Figure 2, the precursor obtained in Comparative Example 1 has a loose structure and exhibits severe agglomeration.

[0122] The ternary cathode materials obtained in Examples 1-13 and Comparative Examples 1-4 were mixed with the conductive active material SuperP and the binder PVDF in a ratio of 90:5:5 to form a slurry, which was then evenly coated on aluminum foil to prepare a positive electrode sheet. A high-purity lithium sheet was selected as the negative electrode, and the separator was a Celgard 2400 polypropylene separator. The electrolyte was 1 mol / L LiPF6 dissolved in a mixed solvent of EC and DMC (volume ratio of 1:1). CR2032 button cells were assembled in a vacuum glove box and then electrochemically tested. Charge and discharge tests were performed using a LAND-2001 blue electric test system with a charge and discharge range of 3.0 to 4.3 V and a temperature of 25°C. The test results are shown in Table 1.

[0123] Table 1

[0124] As can be seen from Table 1, the present disclosure uses glycine-sodium hydroxide buffer solution as the reaction base solution and adds ethylene glycol to coordinately regulate the crystal plane orientation of the precursor, thereby effectively improving the purity and crystal orientation of the precursor, while inhibiting the growth of primary particles and improving the Li + Diffusion ultimately improves the actual specific capacity, rate and cycle performance of the positive electrode material, and it has excellent electrochemical properties when applied to lithium-ion batteries.

Claims

1. A method for preparing a positive electrode material precursor, the preparation method comprising: The glycine buffer solution containing ethylene glycol is mixed with a metal source and reacted to obtain a positive electrode material precursor.

2. The preparation method according to claim 1, wherein The preparation method comprises: first preparing a glycine buffer solution, then adding ethylene glycol to mix, and then adding a metal source to mix.

3. The preparation method according to claim 1 or 2, wherein The method for preparing the glycine buffer comprises mixing a glycine solution with an alkali metal hydroxide solution. Optionally, the concentration of the glycine solution is 0.15 to 0.25 mol / L; Optionally, the alkali metal hydroxide solution comprises sodium hydroxide and / or potassium hydroxide; Optionally, the concentration of the alkali metal hydroxide solution is 0.15 to 0.25 mol / L; Optionally, the volume ratio of the glycine solution to the alkali metal hydroxide solution is 1:(1-1.6); Optionally, the pH of the glycine buffer is 10.8-12.

4. The preparation method according to any one of claims 1 to 3, wherein: The metal source includes at least three metal elements.

5. The preparation method according to any one of claims 1 to 4, wherein: The metal source is added dropwise into the glycine buffer solution containing ethylene glycol in the form of a salt solution for mixing.

6. The preparation method according to claim 5, wherein: The dropping speed of the salt solution is 2-5 mL / min; Optionally, the ratio of the total volume of the salt solution to the volume of the glycine buffer containing ethylene glycol is 1:(20-40).

7. The preparation method according to any one of claims 1 to 6, wherein: The metal source includes soluble salts of Ni, Co and Mn, or soluble salts of Ni, Co and Al, or soluble salts of Ni, Co, Mn and Al.

8. The preparation method according to claim 7, wherein: The soluble salt includes any one of sulfate, nitrate or chloride, or a combination of at least two of them; Optionally, the salt solution is prepared according to a molar ratio of Ni:Co:Mn or Ni:Co:Al or Ni:Co:(Mn+Al) of a:b:c, wherein a+b+c=1, a≥0.6, b≤0.2, c≤0.

2.

9. The preparation method according to any one of claims 5 to 8, wherein: The total concentration of metal ions in the salt solution is 0.1-3 mol / L.

10. The preparation method according to any one of claims 1 to 9, wherein: The amount of ethylene glycol used is 1% to 5% of the mass of the salt solution.

11. The preparation method according to any one of claims 1 to 10, wherein: The reaction temperature is 40-80°C; Optionally, the stirring speed of the reaction is 300 to 900 rpm; Optionally, the reaction is carried out under the protection of an inert gas.

12. The preparation method according to any one of claims 1 to 11, wherein: After the reaction, the reaction product is aged, washed, filtered, dried and sieved in sequence to obtain a ternary precursor; Optionally, the stirring speed of the aging is lower than the stirring speed of the reaction; Optionally, the stirring speed of the aging is 100 to 500 rpm; Optionally, the aging time is 4 to 48 hours; Optionally, the washing liquid of the washing comprises an alkali metal hydroxide solution; Optionally, the drying temperature is 60-150°C.

13. A positive electrode material precursor, wherein the positive electrode material precursor is obtained using the preparation method according to any one of claims 1 to 12.

14. A method for manufacturing a positive electrode material, the method comprising: Mixing a lithium source with the positive electrode material precursor according to claim 13, and sintering to obtain a positive electrode material; Optionally, the ratio of the total molar amount of the metal element in the positive electrode material precursor to the molar amount of the lithium source is 1:(1.01-1.10); Optionally, the sintering is performed in an oxygen-containing atmosphere; Optionally, the sintering temperature is 750-950°C; Optionally, the sintering time is 8 to 15 hours. 15 . A positive electrode material, the positive electrode material being obtained using the manufacturing method according to claim 14 . 16 . A battery comprising the positive electrode material according to claim 15 .

Images