A positive electrode material precursor, a preparation method therefor, and use thereof

Abstract

The present disclosure provides a positive electrode material precursor, a preparation method thereof and use thereof, the preparation method mixes glycine buffer containing ethylene glycol with a metal source, and carries out a reaction to obtain a positive electrode material precursor. The present disclosure uses glycine buffer as a reaction base solution, adds a metal source to the reaction to keep the system pH stable, improve the uniformity and purity of metal elements, utilizes the synergistic effect of glycine and ethylene glycol to effectively adjust the interface energy of different crystal planes of the precursor particles, thereby adjusting the growth and arrangement mode of the precursor particles, and makes the precipitation particles grow along the (003) crystal plane in the first place, thereby obtaining a primary strip-shaped particle, which can provide a fast diffusion channel for lithium ions, reduce the Li + diffusion resistance, and improve the order of the crystal structure, thereby improving the rate performance and cycle stability of the positive electrode material.

Description

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

[0002] With the rapid development of new energy vehicles, the demand for lithium ion secondary batteries has increased dramatically, prompting a substantial increase in the demand for positive electrode materials. Due to the advantages of high energy density, wide working temperature and working voltage range, no memory effect, long cycle life, etc., nickel-cobalt-manganese or nickel-cobalt-aluminum ternary layered positive electrode materials have gradually become the positive electrode material with a larger demand in the current market, and are widely used in digital products and electric tools. Ternary materials are considered to be the ideal power source for the next generation of electric vehicles.

[0003] However, there are still some defects and problems in the application of the positive electrode material in power batteries, especially nickel-cobalt-manganese ternary positive electrode materials. For example, there is a cation mixing effect, resulting in low first charge-discharge efficiency (generally < 90%) and poor cycle performance. In addition, the diffusion coefficient and electronic conductivity of the nickel-cobalt-manganese ternary positive electrode material are low, which makes its rate performance not very ideal.

[0004] CN114804233A discloses a high-nickel ternary positive electrode material for lithium batteries. The preparation method comprises the following steps: ball-milling and refining nickel source, cobalt source and manganese source respectively, and putting them into a high-speed mixer for sufficient mixing to obtain a first precursor mixture; adding a conventional lithium source to the first precursor mixture and mixing thoroughly, and then moving to a ball mill tank for ball-milling and activation treatment to obtain a second precursor mixture; adding an oxidizing lithium source to the second precursor mixture and mixing uniformly, and then sintering the mixture in an oxygen atmosphere in stages to obtain the high-nickel ternary positive electrode material. The preparation method introduces a precursor preparation and ball-milling activation means, and at the same time, introduces an oxidizing lithium source, and sintering in an oxygen atmosphere in stages, which greatly reduces the Li + / Ni 2+ mixing degree, effectively inhibits the cation mixing effect, and to some extent, improves the performance of the material.

[0005] CN112701276A discloses a quaternary polycrystalline positive electrode material, which comprises a main body and a dopant, the dopant is uniformly doped into the main body, wherein the main body is quaternary nickel-cobalt-manganese-aluminum, and the dopant comprises selenium oxide and calcium oxide, Se / Ca is uniformly doped into the material main body, thereby enhancing the structural stability of the layered positive electrode material, reducing the Li + / Ni 2+ cation mixing effect, inhibiting the O 2- to O2 oxidation process, and to some extent, hindering the phase change of the material from delamination to spinel, 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, and therefore, developing new solutions has important significance for improving the performance of batteries containing ternary or quaternary positive electrode materials. SUMMARY

[0007] 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.

[0008] In view of the problems in the prior art, the purpose of the present disclosure is to provide a positive electrode material precursor and a preparation method and use thereof, wherein the preparation method mixes a glycine buffer containing ethylene glycol with a metal source, and performs a reaction to obtain a positive electrode material precursor. The present disclosure uses a glycine buffer as a reaction base solution, and adds a metal source to the reaction to maintain the stability of the system pH, improve the uniformity and purity of metal elements, and effectively adjust the interface energy of different crystal planes of the precursor particles through the synergistic effect of glycine and ethylene glycol, so as to adjust the growth and arrangement mode of the precursor particles, and make the precipitation particles grow along the (003) crystal plane in the first place, thereby obtaining a primary strip-shaped particle, which can provide a fast diffusion channel for lithium ions, reduce the Li + diffusion resistance, and improve the order of the crystal structure, thereby improving the rate performance and cycle stability of the positive electrode material.

[0009] To achieve this purpose, the present disclosure adopts the following technical solutions:

[0010] In a first aspect, the present disclosure provides a preparation method of a positive electrode material precursor, which comprises:

[0011] Mixing a glycine buffer containing ethylene glycol with a metal source, and performing a reaction to obtain a positive electrode material precursor.

[0012] Due to the layered structure characteristics of ternary or quaternary materials, the Li + insertion and extraction channels are perpendicular to the (010) crystal plane, and the Li + diffuses faster in the high-activity (100) and (010) crystal planes, and if the crystal grows along the (003) direction (i.e., the c-axis direction), the Li + diffusion distance can be shorter. Therefore, increasing the crystal plane area of (010) can effectively improve the Li + insertion and extraction probability, thereby being able to improve the Li +The conductivity is further improved, and the electrochemical performance of the nickel-cobalt-manganese or nickel-cobalt-aluminum or nickel-cobalt-manganese-aluminum layered positive electrode material is improved. Since there is a certain inheritance between the (010) crystal face area of the nickel-cobalt-manganese or nickel-cobalt-aluminum or nickel-cobalt-manganese-aluminum layered positive electrode material and the (010) crystal face area of the precursor thereof. Therefore, the nickel-cobalt-manganese or nickel-cobalt-aluminum or nickel-cobalt-manganese-aluminum layered positive electrode material precursor with a large (010) crystal face area is prepared, and the (010) crystal face area of the ternary or quaternary positive electrode material is improved.

[0013] Therefore, the present disclosure prepares glycine buffer solution first, and then co-precipitates the positive electrode precursor by adding a solution containing nickel, cobalt, manganese and the like. By this specific mixing order, that is, using the buffer solution as the precipitation reaction bottom solution instead of mixing all the related raw materials at the same time, the pH value of the solution system in the precipitation process can be kept stable, the formed precursor particles are relatively uniform, and the occurrence of side reactions caused by too large pH value change of the reaction system can be prevented, and the purity of the ternary or quaternary hydroxide precursor is improved.

[0014] Further, glycine has both acidic -COOH and basic functional groups -NH2, can be ionized in water, has strong hydrophilicity and chelation, can complex nickel ions, improve the stability of nickel ions in solution, and 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 growth advantage crystal face (101) of nickel hydroxide will be highlighted, and the hydrogen bonding and chelation of ethylene glycol can cover the (001) crystal face during the formation of the precursor, so that the (010) crystal face with higher activity is exposed. Therefore, the synergistic effect of glycine and ethylene glycol can effectively adjust the interfacial energy of different crystal faces of the precursor particles, so as to adjust the growth and arrangement mode of the precursor particles, so that the precipitation particles grow along the (003) crystal face in the first place. The primary long strip-shaped particles grown along the (003) crystal face can provide a rapid diffusion channel for lithium ions, reduce the Li + diffusion resistance, and improve 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 the particles, thereby achieving the purpose of refining the primary particles.

[0015] The following is an optional technical solution of the present disclosure, but is not a limitation of the technical solution provided by the present disclosure. Through the following technical solution, the technical purpose and beneficial effects of the present disclosure can be better achieved and realized.

[0016] As an optional technical solution of the present disclosure, the preparation method comprises: first preparing glycine buffer solution, then mixing with ethylene glycol, and then adding metal source.

[0017] Optionally, the method for preparing the glycine buffer solution includes mixing a glycine solution with an alkali metal hydroxide solution.

[0018] Optionally, the concentration of the glycine solution is 0.15–0.25 mol / L, such as 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, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0019] Optionally, the alkali metal hydroxide solution includes sodium hydroxide and / or potassium hydroxide.

[0020] Optionally, the concentration of the alkali metal hydroxide solution is 0.15–0.25 mol / L, such as 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, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0021] Optionally, the volume ratio of the glycine solution to the alkali metal hydroxide solution is 1:(1 to 1.6), such as 1:1, 1:15, 1:2, 1:25, 1:3, 1:35, 1:4, 1:45, 1:5, 1:55 or 1:6, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0022] Optionally, the pH of the glycine buffer solution 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 unlisted values ​​within the above range are also applicable.

[0023] As an optional technical solution of this disclosure, the metal source includes at least three metal elements.

[0024] Optionally, the metal source is added dropwise to a glycine buffer solution containing ethylene glycol in the form of a salt solution for mixing.

[0025] Optionally, the dropping rate of the salt solution is 2 to 5 mL / min, such as 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, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0026] Optionally, the ratio of the total volume of the salt solution to the volume of the glycine buffer solution 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, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0027] 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.

[0028] Optionally, the soluble salt includes any one or a combination of at least two of sulfates, nitrates, or chlorides, with typical but non-limiting examples including combinations of sulfates and nitrates, sulfates and chlorides, or chlorides and nitrates.

[0029] Optionally, the salt solution is prepared according to a molar ratio of Ni:Co:Mn, Ni:Co:Al, or Ni:Co:(Mn+Al) of a:b:c, wherein a+b+c=1, a≥0.6, for example 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, 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., where 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 not limited to the listed values, other unlisted values ​​within the above range also apply.

[0030] Optionally, the total concentration of metal ions in the salt solution is 0.1 to 3 mol / L, such as 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; other unlisted values ​​within the above range are also applicable.

[0031] As an optional technical solution of this disclosure, the amount of ethylene glycol used is 1% to 5% of the mass of the salt solution, such as 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. Other unlisted values ​​within the above range are also applicable.

[0032] As an optional technical solution of this disclosure, the reaction temperature is 40 to 80°C, such as 40°C, 44°C, 48°C, 52°C, 56°C, 60°C, 64°C, 68°C, 72°C, 76°C or 80°C, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0033] Optionally, the stirring speed of the reaction is 300 to 900 rpm, such as 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. Other unlisted values ​​within the above range are also applicable.

[0034] Optionally, the reaction is carried out under the protection of an inert gas.

[0035] As an optional technical solution of this disclosure, after the reaction, the reaction product is successively aged, washed, filtered, dried and sieved to obtain a ternary precursor.

[0036] Optionally, the stirring speed during aging is lower than the stirring speed during the reaction.

[0037] Optionally, the stirring speed during aging is 100 to 500 rpm, such as 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm or 500 rpm, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0038] Optionally, the aging time is 4 to 48 hours, such as 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 unlisted values ​​within the above range are also applicable.

[0039] Optionally, the washing solution comprises an alkali metal hydroxide solution.

[0040] Optionally, the drying temperature is 60 to 150°C, such as 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0041] Secondly, this disclosure provides a cathode material precursor, obtained using the preparation method described in the first aspect.

[0042] Thirdly, this disclosure provides a method for manufacturing a cathode material, the method comprising:

[0043] The lithium source is mixed with the cathode material precursor described in the second aspect and sintered to obtain the cathode material.

[0044] As an optional technical solution of this disclosure, the ratio of the total molar amount of metal elements in the cathode material precursor to the molar amount of the lithium source is 1:(1.01~1.10), such as 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. Other unlisted values ​​within the above range are also applicable.

[0045] Optionally, the sintering is carried out in an oxygen-containing atmosphere.

[0046] Optionally, the sintering temperature is 750 to 950°C, such as 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 unlisted values ​​within the above range are also applicable.

[0047] 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 it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0048] Fourthly, this disclosure provides a cathode material obtained using the manufacturing method described in the third aspect.

[0049] Fifthly, this disclosure provides a battery comprising the positive electrode material described in the fourth aspect.

[0050] Compared with existing technical solutions, this disclosure has at least the following beneficial effects:

[0051] This disclosure utilizes a glycine buffer solution as the reaction substrate, adding a metal source to maintain pH stability and improve the uniformity and purity of the metal elements. The synergistic effect of glycine and ethylene glycol effectively regulates the interfacial energy of different crystal planes of the precursor particles, thereby adjusting the growth and arrangement of the precursor particles. This allows the precipitated particles to preferentially grow along the (003) crystal plane, resulting in primary elongated particles that provide a rapid diffusion channel for lithium ions, reducing the Li-ion diffusion rate. + Diffusion resistance and improved crystal structure order can enhance the rate performance and cycle stability of cathode materials.

[0052] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood. Attached Figure Description

[0053] The accompanying drawings are used to provide a further understanding of the technical solutions in this paper and form part of the specification. They are used together with the embodiments of this application to explain the technical solutions in this paper and do not constitute a limitation on the technical solutions in this paper.

[0054] Figure 1 This is a SEM image of the cathode material precursor obtained in Example 1;

[0055] Figure 2 This is a SEM image of the cathode material precursor obtained in Comparative Example 1. Detailed Implementation

[0056] The technical solution of this disclosure will be further illustrated below through specific implementation methods.

[0057] Those skilled in the art will understand that the embodiments described are merely illustrative of this disclosure and should not be construed as specific limitations thereof.

[0058] Example 1

[0059] This embodiment provides a method for manufacturing a cathode material, the method comprising the following steps:

[0060] (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 at a volume ratio of 1:1.3 and control the pH to 11. The resulting glycine-sodium hydroxide buffer solution is the reaction base solution.

[0061] (2) According to the molecular formula Ni 0.8 Co 0.1 Mn 0.1 (OH)2, that is, according to the molar ratio of metal elements Ni, Co, and Mn of 8:1:1, nickel sulfate, cobalt sulfate, and manganese sulfate are weighed and dissolved in deionized water to prepare a salt solution, and the total concentration of nickel, cobalt, and manganese ions in the solution is 1.5 mol / L;

[0062] The reaction substrate is placed in a reaction vessel, and ethylene glycol is added, with the amount of ethylene glycol controlled to be 2.6% of the mass of the salt solution;

[0063] (3) Nitrogen gas was introduced into the reactor, and stirring was started at a speed of 600 r / min. Then, a salt solution containing nickel, cobalt, and manganese was added to the reactor at a feed rate of 3 mL / min, and the reaction was carried out at a temperature of 60℃ for 10 h. The volume ratio of the salt solution containing nickel, cobalt, and manganese to the reaction base liquid was controlled to be 1:30 at the end of the reaction.

[0064] (4) After the reaction is completed, stop feeding and age at 300 r / min for 8 h. After aging, wash with 1 mol / L sodium hydroxide solution and dry at 100℃ for 24 h to obtain the cathode material precursor.

[0065] (5) Based on a ratio of the total molar number of Ni, Co, and Mn in the cathode material precursor to the molar number of Li in the lithium salt of 1:1.05, weigh out the corresponding amount of cathode material precursor and mix it evenly with lithium carbonate. Then, sinter the mixture at 850℃ for 12 h in an oxygen atmosphere to obtain LiNi. 0.8 Co 0.1 Mn 0.1 O2 ternary cathode material.

[0066] Example 2

[0067] This embodiment provides a method for manufacturing a cathode material, the method comprising the following steps:

[0068] (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 at 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.

[0069] (2) According to the molecular formula Ni 0.8 Co 0.1 Mn 0.1 (OH)2, that is, according to the molar ratio of metal elements Ni, Co, and Mn of 8:1:1, nickel sulfate, cobalt sulfate, and manganese sulfate are weighed and dissolved in deionized water to prepare a salt solution, and the total concentration of nickel, cobalt, and manganese ions in the solution is 3 mol / L;

[0070] Place the reaction base liquid into the reaction vessel, add ethylene glycol, and control the amount of ethylene glycol to be 1% of the mass of the salt solution;

[0071] (3) Nitrogen gas was introduced into the reactor, and stirring was started at a speed of 300 r / min. Then, a salt solution containing nickel, cobalt, and manganese was added to the reactor at a feed rate of 2 mL / min, and the reaction was carried out at a temperature of 40℃ for 15 h. The volume ratio of the salt solution containing nickel, cobalt, and manganese to the reaction base liquid was controlled to be 1:20 at the end of the reaction.

[0072] (4) After the reaction is complete, stop feeding and age at 100 r / min for 4 h. After aging, wash with 1 mol / L sodium hydroxide solution and dry at 60℃ for 24 h to obtain the cathode material precursor.

[0073] (5) Based on a ratio of the total molar number of Ni, Co, and Mn in the cathode material precursor to the molar number of Li in the lithium salt of 1:1.01, weigh out the corresponding amount of cathode material precursor and mix it evenly with lithium carbonate. Then, sinter the mixture at 750℃ for 15 h in an oxygen atmosphere to obtain LiNi. 0.8 Co 0.1 Mn 0.1 O2 ternary cathode material.

[0074] Example 3

[0075] This embodiment provides a method for manufacturing a cathode material, the method comprising the following steps:

[0076] (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 at a volume ratio of 1:1.6 and control the pH to 12. The resulting glycine-sodium hydroxide buffer solution is the reaction base solution.

[0077] (2) According to the molecular formula Ni 0.8 Co0.1 Mn 0.1 (OH)2, that is, according to the molar ratio of metal elements Ni, Co, and Mn of 8:1:1, nickel sulfate, cobalt sulfate, and manganese sulfate are weighed and dissolved in deionized water to prepare a salt solution, and the total concentration of nickel, cobalt, and manganese ions in the solution is 0.1 mol / L;

[0078] Place the reaction base liquid into the reaction vessel, add ethylene glycol, and control the amount of ethylene glycol to be 5% of the mass of the salt solution;

[0079] (3) Nitrogen gas was introduced into the reactor, and stirring was started at a speed of 900 r / min. Then, a salt solution containing nickel, cobalt, and manganese was added to the reactor at a feed rate of 5 mL / min and the reaction was carried out at a temperature of 80℃ for 5 h. The volume ratio of the salt solution containing nickel, cobalt, and manganese to the reaction base liquid was controlled to be 1:40 at the end of the reaction.

[0080] (4) After the reaction is completed, stop feeding and age at 500 r / min for 48 h. After aging, wash with 1 mol / L sodium hydroxide solution and dry at 150℃ for 24 h to obtain the cathode material precursor.

[0081] (5) Based on a ratio of the total molar number of Ni, Co, and Mn in the cathode material precursor to the molar number of Li in the lithium salt of 1:1.01, weigh out the corresponding amount of cathode material precursor and mix it evenly with lithium carbonate. Then, sinter the mixture at 950℃ for 8 hours under an oxygen atmosphere to obtain LiNi. 0.8 Co 0.1 Mn 0.1 O2 ternary cathode material.

[0082] Example 4

[0083] This embodiment provides a method for manufacturing a positive electrode material. In step (1), the amount of sodium hydroxide solution is adjusted so that the pH of the reaction substrate is adjusted from 11 to 10. Apart from this, the other conditions are exactly the same as in Example 1.

[0084] Example 5

[0085] This embodiment provides a method for manufacturing a positive electrode material. In step (1), the amount of sodium hydroxide solution is adjusted so that the pH of the reaction substrate is adjusted from 11 to 10.8. Apart from this, the other conditions are exactly the same as in Example 1.

[0086] Example 6

[0087] This embodiment provides a method for manufacturing a positive electrode material. In step (1), the amount of sodium hydroxide solution is adjusted so that the pH of the reaction substrate is adjusted from 11 to 12. Apart from this, the other conditions are exactly the same as in Example 1.

[0088] Example 7

[0089] This embodiment provides a method for manufacturing a positive electrode material. In step (1), the amount of sodium hydroxide solution is adjusted so that the pH of the reaction substrate is adjusted from 11 to 12.8. Apart from this, the other conditions are exactly the same as in Example 1.

[0090] Example 8

[0091] This embodiment provides a method for manufacturing a positive electrode material. In step (1), the concentration of glycine is adjusted from 0.2 mol / L to 0.1 mol / L. Otherwise, the other conditions are exactly the same as in Example 1.

[0092] Example 9

[0093] This embodiment provides a method for manufacturing a positive electrode material. In step (1), the concentration of glycine is adjusted from 0.2 mol / L to 0.15 mol / L. Otherwise, the other conditions are exactly the same as in Example 1.

[0094] Example 10

[0095] This embodiment provides a method for manufacturing a positive electrode material. In step (1), the concentration of glycine is adjusted from 0.2 mol / L to 0.25 mol / L. Otherwise, the other conditions are exactly the same as in Example 1.

[0096] Example 11

[0097] This embodiment provides a method for manufacturing a positive electrode material. In step (1), the concentration of glycine is adjusted from 0.2 mol / L to 0.3 mol / L. Otherwise, the other conditions are exactly the same as in Example 1.

[0098] Example 12

[0099] This embodiment provides a method for manufacturing a cathode material. In step (2), the amount of ethylene glycol is adjusted from 2.6% to 0.5%. Otherwise, the other conditions are exactly the same as in Example 1.

[0100] Example 13

[0101] This embodiment provides a method for manufacturing a cathode material. In step (2), the amount of ethylene glycol is adjusted from 2.6% to 1%. Otherwise, the other conditions are exactly the same as in Example 1.

[0102] Example 14

[0103] This embodiment provides a method for manufacturing a cathode material. In step (2), the amount of ethylene glycol is adjusted from 2.6% to 5%. Otherwise, the other conditions are exactly the same as in Example 1.

[0104] Example 15

[0105] This embodiment provides a method for manufacturing a cathode material. In step (2), the amount of ethylene glycol is adjusted from 2.6% to 5.5%. Otherwise, the other conditions are exactly the same as in Example 1.

[0106] Comparative Example 1

[0107] This comparative example provides a method for manufacturing a cathode material, the method comprising the following steps:

[0108] (1) Prepare a 2 mol / L sodium hydroxide solution as a precipitant and a 2 mol / L ammonia solution as a complexing agent;

[0109] (2) According to the molecular formula Ni 0.8 Co 0.1 Mn 0.1 (OH)2, that is, according to the molar ratio of metal elements Ni, Co, and Mn of 8:1:1, nickel sulfate, cobalt sulfate, and manganese sulfate are weighed and dissolved in deionized water to prepare a salt solution;

[0110] (3) Nitrogen gas is introduced into the reactor. Sodium hydroxide solution, ammonia water and salt solution containing nickel, cobalt and manganese are continuously introduced into the reactor in parallel flow. The feed rate of salt solution containing nickel, cobalt and manganese and ammonia water is 3 mL / min. The feed rate of sodium hydroxide solution is controlled to stabilize the pH value at 11. The reaction is carried out at a temperature of 60℃ and a stirring speed of 600 r / min for 10 h.

[0111] (4) After the reaction is complete, stop feeding and age at 300 r / min for 8 h. After aging, wash with 1 mol / L sodium hydroxide solution and dry at 100℃ for 24 h to obtain the cathode material precursor.

[0112] (5) Weigh out the corresponding amount of precursor according to the ratio of the total molar number of Ni, Co, and Mn in the cathode material precursor to the molar number of Li in the lithium salt of 1:1.05, mix it evenly with lithium carbonate, and then sinter the mixture at 850℃ for 12h in an oxygen atmosphere to obtain LiNi. 0.8 Co 0.1 Mn 0.1 O2 ternary cathode material.

[0113] Comparative Example 2

[0114] This comparative example provides a method for manufacturing a positive electrode material, wherein in step (2), ammonia is used instead of ethylene glycol, and all other conditions are exactly the same as in Example 1.

[0115] Comparative Example 3

[0116] This comparative example provides a method for manufacturing a positive electrode material. In step (1), glycine is not used; only a 0.2 mol / L sodium hydroxide solution is used as the reaction substrate. Apart from this, the other conditions are exactly the same as in Example 1.

[0117] Comparative Example 4

[0118] 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 constant. All raw materials are mixed at the same time, and the mixture is stirred in a reactor at a stirring speed of 600 r / min. The reaction is carried out at a temperature of 60°C for 10 h, and then steps (4) and (5) are performed. Other than this, the conditions are exactly the same as in Example 1.

[0119] Performance testing:

[0120] The morphology of the cathode material precursors prepared in Example 1 and Comparative Example 1 was analyzed using scanning electron microscopy (SEM). Figure 1 As shown, the precursor Ni obtained in Example 1 0.8 Co 0.1 Mn 0.1 The primary particles of (OH)₂ are thick with a large (010) crystal plane area. The secondary particles are well-dispersed, uniform, and internally dense spherical. The precursor particle size is about 5.0 μm, and the length of the primary particles is 200–300 nm. However, as... Figure 2 As shown, the precursor structure obtained in Comparative Example 1 is relatively loose and exhibits severe aggregation.

[0121] 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 uniformly coated onto aluminum foil to prepare a cathode sheet. A high-purity lithium sheet was used as the anode, and a Celgard 2400 polypropylene membrane was used as the separator. The electrolyte was 1 mol / L LiPF6 dissolved in a mixed solvent of EC and DMC (volume ratio 1:1). The cells were assembled into CR2032 coin cells in a vacuum glove box, and then electrochemical tests were performed. Charge-discharge tests were conducted using a LAND-2001 LAND test system, with a charge-discharge range of 3.0–4.3 V and a temperature of 25°C. The test results are shown in Table 1.

[0122] Table 1

[0123]

[0124] As shown in Table 1, this disclosure effectively improves the purity and crystal orientation of the precursor by using a glycine-sodium hydroxide buffer solution as the reaction substrate and adding ethylene glycol to synergistically regulate the crystal orientation of the precursor. Simultaneously, it inhibits the growth of primary particles and improves the Li... + Diffusion ultimately improves the actual specific capacity, rate capability, and cycle performance of the cathode material, resulting in excellent electrochemical performance when applied to lithium-ion batteries.

Claims

1. A method for preparing a cathode material precursor, the method comprising the following steps: a buffer solution of glycine is prepared, then ethylene glycol is added, and then a metal source is added, wherein the metal source is added dropwise to the glycine buffer solution containing ethylene glycol in the form of a salt solution, the amount of ethylene glycol is 1%-5% of the mass of the salt solution, and a reaction is performed to obtain a cathode material precursor.

2. The production method according to claim 1, wherein, The method for preparing the glycine buffer solution comprises mixing a glycine solution and an alkali hydroxide solution.

3. The production method according to claim 2, wherein, The concentration of the glycine solution is 0.15-0.25 mol / L.

4. The production method according to claim 2, wherein, The alkali hydroxide solution comprises sodium hydroxide and / or potassium hydroxide.

5. The production method according to claim 2, wherein, The concentration of the alkali hydroxide solution is 0.15-0.25 mol / L.

6. The production method according to claim 2, wherein, The volume ratio of the glycine solution to the alkali hydroxide solution is 1:(1-1.6).

7. The production method according to claim 2, wherein The pH of the glycine buffer solution is 10.8-12.

8. The production method according to claim 1, wherein The metal source comprises at least three metal elements.

9. The production method according to claim 1, wherein The dropwise adding speed of the salt solution is 2-5 mL / min.

10. The production method according to claim 1, wherein, The ratio of the total volume of the salt solution to the volume of the glycine buffer solution containing ethylene glycol is 1:(20-40).

11. The method of producing according to claim 1, wherein, The metal source comprises soluble salts of Ni, Co and Mn, or soluble salts of Ni, Co and Al, or soluble salts of Ni, Co, Mn and Al.

12. The method of making according to claim 11, wherein, The soluble salts comprise any one or a combination of at least two of sulfate, nitrate or chloride.

13. The method of making according to claim 11, wherein, The salt solution is prepared according to the molar ratio of Ni:Co:Mn or Ni:Co:Al or Ni:Co:(Mn+Al) being a:b:c, wherein a+b+c=1, a≥0.6, b≤0.2, and c≤0.

2.

14. The method of producing according to claim 1, wherein, The total concentration of metal ions in the salt solution is 0.1-3 mol / L.

15. The method of producing according to claim 1, wherein, The temperature of the reaction is 40-80℃.

16. The method of producing according to claim 1, wherein, The stirring speed of the reaction is 300-900 rpm.

17. The method of producing according to claim 1, wherein, The reaction is performed under the protection of an inert gas.

18. The method of producing according to claim 1, wherein, After the reaction, the reaction product is sequentially subjected to aging, washing, filtering, drying and sieving to obtain a ternary precursor.

19. The method of making according to claim 18, wherein, The stirring speed of the aging is lower than the stirring speed of the reaction.

20. The method of making according to claim 18, wherein, The stirring speed of the aging is 100-500 rpm.

21. The method of making according to claim 18, wherein, The aging time is 4-48 h.

22. The method of making according to claim 18, wherein, The washing liquid for the washing comprises an alkali hydroxide solution.

23. The method of making according to claim 18, wherein, The temperature of the drying is 60-150℃. 24.A cathode material precursor, which is obtained by the method according to any one of claims 1-23. 25.A method for manufacturing a cathode material, the method comprising: mixing a lithium source with the cathode material precursor according to claim 24, and sintering to obtain a cathode material.

26. The method of producing a cathode material according to claim 25, wherein The ratio of the total molar amount of metal elements in the cathode material precursor to the molar amount of the lithium source is 1:(1.01-1.10).

27. The method of producing a cathode material according to claim 25, wherein The sintering is performed in an oxygen-containing atmosphere.

28. The method of producing a cathode material according to claim 25, wherein The temperature of the sintering is 750-950℃.

29. The method of producing a cathode material according to claim 25, wherein The sintering time is 8-15 h. 30.A cathode material, which is obtained by the method according to any one of claims 25-29.

31. A battery comprising the positive electrode material of claim 30.

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