Modification method of lithium-rich oxide positive electrode material
阅读说明：本技术 一种富锂氧化物正极材料的改性方法 (Modification method of lithium-rich oxide positive electrode material ) 是由 路积胜 于 2020-03-17 设计创作，主要内容包括：本发明涉及一种富锂氧化物正极材料的改性方法,属于新能源技术领域。使用加热通氩气的方法进行处理,具体包括三个步骤：碳酸盐前驱体的制备、富锂锰基正极材料的制备和氩气加热处理富锂锰基层状正极材料产生氧空位的制备。该方法能够改善富锂锰基层状正极材料的倍率性能、循环稳定性能,并且能够抑制富锂锰基层状正极材料中过渡金属离子的析出和电压衰减,同时可以减少氧气的析出。本发明方法合成工艺简单,生产效率高,适宜规模化生产。且本方法具有反应物所需原料易得,无毒且成本低廉,生产过程无需特殊防护,反应条件容易控制,所得到的产物具有产量大、结果重复性好等优点。(The invention relates to a modification method of a lithium-rich oxide cathode material, belonging to the technical field of new energy. The treatment is carried out by a method of heating and introducing argon, and specifically comprises the following three steps: preparing a carbonate precursor, preparing a lithium-rich manganese-based positive electrode material, and preparing oxygen vacancies generated by heating the lithium-rich manganese-based layered positive electrode material with argon. The method can improve the rate capability and the cycle stability of the lithium-rich manganese-based layered positive electrode material, can inhibit the precipitation of transition metal ions and voltage attenuation in the lithium-rich manganese-based layered positive electrode material, and can reduce the precipitation of oxygen. The method has the advantages of simple synthesis process and high production efficiency, and is suitable for large-scale production. The method has the advantages of easily obtained raw materials required by reactants, no toxicity, low cost, no need of special protection in the production process, easily controlled reaction conditions, high yield of obtained products, good result repeatability and the like.)
1. A method for modifying a lithium-rich oxide cathode material is characterized in that an oxygen vacancy is generated by adopting a direct heating argon method, and the method comprises the following steps:
s1, preparation of a carbonate precursor:
1) dissolving cobalt metal salt, nickel metal salt and manganese metal salt in pure water to obtain a metal ion mixed solution;
2) preparing a carbonate precipitant solution with the molar concentration of 1-3 mol/L, and adding the precipitant solution into the metal ion mixed solution under magnetic stirring to generate a coprecipitation product;
3) stirring the coprecipitation product for 6-18 hours, then carrying out centrifugal separation on the coprecipitation product, and respectively washing the precipitate with deionized water for three times and absolute ethyl alcohol for two times;
4) and (3) drying the precipitate in an oven at 80 ℃ for 24 hours to obtain a carbonate precursor, wherein the molecular formula of the carbonate precursor is as follows: (Mn)0.1～0.9Ni0.1～0.8Co0～0.5)1.25CO3·2H2O；
S2, preparing a lithium-rich manganese-based layered positive electrode material:
the carbonate precursor obtained in S1 was reacted with LiOH. H2O or Li2CO3Mixing according to the molar ratio of 1 (1-2), and fully grinding to ensure that the particle diameter is 0.5-5 um; uniformly mixing, placing in a muffle furnace, calcining at 700-1000 ℃ for 6-24 hours at a heating rate of 1-5 ℃/min, and naturally cooling to room temperature to obtain a lithium-rich manganese-based layered cathode material;
s3, preparing an oxygen vacancy lithium-rich manganese-based layered positive electrode material:
and (3) uniformly dispersing the lithium-rich manganese-based layered positive electrode material obtained in the step (S2) in a quartz boat, placing the quartz boat in a tube furnace, continuously introducing argon for 10-60 minutes before starting heating, then heating to 800 ℃ at the speed of 1-5 ℃/min, and preserving heat for 600 minutes to obtain the lithium-rich manganese-based layered positive electrode material containing oxygen vacancies.
2. The method for modifying the lithium-rich oxide cathode material according to claim 1, wherein the specific ratio of the metal ion mixed solution is as follows: the metal salt of cobalt, the metal salt of nickel and the metal salt of manganese are as follows according to the molar ratio of metal ions: the metal salt of nickel, the metal salt of cobalt, the metal salt of manganese, (0.1-0.8), (0-0.4) and (0.1-0.9) are added so that the sum of the molar numbers of the three metal salts is less than or equal to 1 and the total molar concentration of metal ions is 1-3 mol/L.
3. The method for modifying a lithium-rich oxide cathode material according to claim 2, wherein the cobalt metal salt is CoSO4·7H2O、Co(NO3)2·6H2O、CoCl2·6H2O or Co (Ac)2·4H2O。
4. The method for modifying the lithium-rich oxide cathode material according to claim 1, wherein the molar ratio of the precipitant solution to the metal ion mixed solution in the step 2) is as follows: and (3) a precipitant solution, namely a metal ion mixed solution which is 1 (0.7-2).
5. The method for modifying a lithium-rich oxide cathode material as claimed in claim 1, wherein the metal salt of nickel is NiSO4·6H2O、Ni(NO3)2·6H2O、NiCl2·6H2O or Ni (Ac)2·4H2O。
6. The method for modifying a lithium-rich oxide cathode material as claimed in claim 1, wherein the metal salt of manganese is MnSO4·H2O、Mn(NO3)2·4H2O、MnCl2·4H2O or Mn (Ac)2·4H2O。
7. The method for modifying a lithium-rich oxide cathode material as claimed in claim 1, wherein the precipitant is NaOH or Na2CO3、NaHCO3、(NH4)2CO3Or NH4HCO3Any one of them.
Technical Field
The invention relates to the technical field of new energy, in particular to a method for modifying a lithium-rich oxide positive electrode material.
Background
The lithium-rich manganese-based layered cathode material has high specific capacity (>250mAh g-1) And high energy density (>1000wh kg-1) The positive electrode of the next generation of high specific energy power battery has received much attention in recent years. Until now, no fully mature lithium-rich manganese-based positive electrode material exists in the global market, mainly because of the problems of poor cycling stability and inability to meet stable capacity and power output in a long cycling state. Secondly, the voltage attenuation is serious in the circulation process, and the power density of the power battery in the use process is seriously reduced due to the voltage attenuation. Also, the low rate capability severely limits the realization of fast charging of the power battery. For these major problems, many fundamental mechanistic studies are currently being conductedMost of these problems are considered to be mainly related to the following points: firstly, the rich lithium battery is accompanied with the generation of oxygen in the process of high-voltage charge and discharge, and the oxygen can react with the electrolyte to accelerate the corrosion of the material and destroy the crystal structure of the material. Secondly, irreversible phase change is accompanied in the charging and discharging process, which causes irreversible change of the crystal structure, such as reduction of interlayer spacing and huge change of crystal stress to collapse the crystal structure. Finally, the transition metal ions react with the electrolyte in the circulating process and are reduced to be dissolved into the electrolyte to cause the damage of the crystal structure. Based on these related studies, many improved methods have been proposed to improve the related properties of lithium-rich manganese-based positive electrode materials, with the most studies being surface coating and bulk or surface metal element doping. These methods all improve the relevant properties of lithium rich materials to some extent. However, these methods are complicated, consume much energy, and have not significant economic benefits. Further improvements are needed on this basis. The surface defect engineering has very important development value, and can change the energy band structure, the electronic structure and the like of the material, which is proved in the catalytic material. Therefore, the introduction of surface defect engineering into the lithium-rich manganese-based cathode material is particularly important. This is mainly because the surface defects can suppress the precipitation of oxygen to some extent, stabilize the crystal structure and increase the interlayer spacing, thus improving the electrochemical performance of the battery. However, the research on the surface defects of the lithium-rich manganese-based cathode material is relatively few, and most preparation processes are relatively complex, so that the practical application is more challenging. Therefore, it is of great importance to develop a more efficient, inexpensive and simple to operate modification process. The lithium-rich cathode material is heated in an argon atmosphere, so that oxygen vacancies can be generated on the surface of the material. The dispensing operation is simple, and the relevant performance of the material can be greatly improved.
Disclosure of Invention
The invention aims to: in order to solve the problems in the background art, a modification method of a lithium-rich oxide cathode material is provided.
In order to achieve the purpose, the invention adopts the following technical scheme:
a modification method of a lithium-rich oxide cathode material adopts a direct heating argon method to generate oxygen vacancies, and comprises the following steps:
s1, preparation of a carbonate precursor:
1) dissolving cobalt metal salt, nickel metal salt and manganese metal salt in pure water to obtain a metal ion mixed solution;
2) preparing a carbonate precipitant solution with the molar concentration of 1-3 mol/L, and adding the precipitant solution into the metal ion mixed solution under magnetic stirring to generate a coprecipitation product;
3) stirring the coprecipitation product for 6-18 hours, then carrying out centrifugal separation on the coprecipitation product, and respectively washing the precipitate with deionized water for three times and absolute ethyl alcohol for two times;
4) and (3) drying the precipitate in an oven at 80 ℃ for 24 hours to obtain a carbonate precursor, wherein the molecular formula of the carbonate precursor is as follows: (Mn)0.1～0.9Ni0.1～0.8Co0～0.5)1.25CO3·2H2O；
S2, preparing a lithium-rich manganese-based layered positive electrode material:
the carbonate precursor obtained in S1 was reacted with LiOH. H2O or Li2CO3Mixing according to the molar ratio of 1 (1-2), and fully grinding to ensure that the particle diameter is 0.5-5 um; uniformly mixing, placing in a muffle furnace, calcining at 700-1000 ℃ for 6-24 hours at a heating rate of 1-5 ℃/min, and naturally cooling to room temperature to obtain a lithium-rich manganese-based layered cathode material;
s3, preparing an oxygen vacancy lithium-rich manganese-based layered positive electrode material:
and (3) uniformly dispersing the lithium-rich manganese-based layered positive electrode material obtained in the step (S2) in a quartz boat, placing the quartz boat in a tube furnace, continuously introducing argon for 10-60 minutes before starting heating, then heating to 800 ℃ at the speed of 1-5 ℃/min, and preserving heat for 600 minutes to obtain the lithium-rich manganese-based layered positive electrode material containing oxygen vacancies.
As a further description of the above technical solution:
the metal ion mixed solution comprises the following specific mixture ratio: the metal salt of cobalt, the metal salt of nickel and the metal salt of manganese are as follows according to the molar ratio of metal ions: the metal salt of nickel, the metal salt of cobalt, the metal salt of manganese, (0.1-0.8), (0-0.4) and (0.1-0.9) are added so that the sum of the molar numbers of the three metal salts is less than or equal to 1 and the total molar concentration of metal ions is 1-3 mol/L.
As a further description of the above technical solution:
the metal salt of cobalt is CoSO4·7H2O、Co(NO3)2·6H2O、CoCl2·6H2O or Co (Ac)2·4H2O。
As a further description of the above technical solution:
the molar ratio of the precipitant solution to the metal ion mixed solution in the step 2) is as follows: and (3) a precipitant solution, namely a metal ion mixed solution which is 1 (0.7-2).
As a further description of the above technical solution:
the metal salt of nickel is NiSO4·6H2O、Ni(NO3)2·6H2O、NiCl2·6H2O or Ni (Ac)2·4H2O。
As a further description of the above technical solution:
the metal salt of manganese is MnSO4·H2O、Mn(NO3)2·4H2O、MnCl2·4H2O or Mn (Ac)2·4H2O。
As a further description of the above technical solution:
the precipitant is NaOH or Na2CO3、NaHCO3、(NH4)2CO3Or NH4HCO3Any one of them.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
1. in the method for preparing the oxygen vacancy lithium-rich manganese-based layered anode material by argon treatment, series materials with different oxygen vacancy concentrations are prepared by a direct heating method, namely argon and the lithium-rich manganese-based layered anode material are directly heated, and oxygen vacancies with different concentrations are successfully generated on the surface of the lithium-rich manganese-based layered anode material by changing the proportion of argon to raw materials, the heating time and the like.
2. Compared with the same oxygen-free vacancy-containing material, the oxygen-vacancy-containing lithium-rich manganese-based layered cathode material prepared by the method has the advantages that the battery performance such as the battery cycling stability, the multiplying power and the like is greatly improved, and the precipitation of surface oxygen and the voltage attenuation are simultaneously inhibited.
3. According to the preparation method, the oxygen vacancy lithium-rich manganese-based anode material is prepared through a simple heating method, the used argon is easy to obtain, the raw materials required by reactants are easy to obtain and low in cost, special protection is not needed in the production process, the reaction conditions are easy to control, and the obtained product has the advantages of high yield, good result repeatability and the like. The method has the advantages of simple synthesis process, high production efficiency and lower production cost, and is suitable for large-scale production.
Drawings
FIG. 1 shows that oxygen vacancy-containing lithium-rich manganese-based layered cathode material obtained by heating the anode material for 5 hours after the anode material is heated to 400 ℃ under the condition of argon flow of 30mL/min and the heating rate of 1 ℃/min is 0.1C,0.2C,0.5C,1℃,2C, 5C and 10C (1℃ is 250 mAg)-1) A discharge specific capacity cycle comparison graph under current density;
FIG. 2 shows that the oxygen vacancy-containing lithium-rich manganese-based layered positive electrode material obtained by heating the mixture for 5 hours after the temperature rise speed of 1 ℃/min is increased to 400 ℃ in an argon flow of 30mL/min and the untreated lithium-rich manganese-based layered positive electrode material is at 0.2C (1℃: 250 mAg)-1) A discharge specific capacity cycle comparison graph under current density;
FIG. 3 shows that the oxygen vacancy-containing lithium-rich manganese-based layered positive electrode material obtained by heating the anode material at 30mL/min argon flow and a heating rate of 1 ℃/min to 400 ℃ for 5 hours and the untreated lithium-rich manganese-based layered positive electrode material are at 0.2C (1℃: 250 mAg)-1) Voltage decay versus cycle plot at current density.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a modification method of a lithium-rich oxide cathode material, which directly heats a lithium-rich manganese-based cathode material under an argon atmosphere to generate oxygen vacancies, and comprises the following steps:
(1) preparing a carbonate precursor:
dissolving cobalt metal salt, nickel metal salt and manganese metal salt in pure water, wherein the cobalt metal salt, the nickel metal salt and the manganese metal salt are prepared according to the molar ratio of metal ions: a metal salt of nickel, a metal salt of cobalt, a metal salt of manganese, (0.1-0.8), (0-0.4) and (0.1-0.9), wherein the sum of the molar numbers of the three metal salts is less than or equal to 1, and the total molar concentration of metal ions is 1-3 mol/L to obtain a metal ion mixed solution; preparing a carbonate precipitant solution with the molar concentration of 1-3 mol/L, and adding the precipitant solution into the metal ion mixed solution under magnetic stirring, wherein the molar ratio of the added solution is as follows: and (3) a precipitant solution, namely (0.7-2) a metal ion mixed solution, generating a coprecipitation product, stirring for 6-18 hours, performing centrifugal separation on the coprecipitation product, respectively washing the precipitate with deionized water for three times and absolute ethyl alcohol for two times, and drying the precipitate in an oven at 80 ℃ for 24 hours to obtain a carbonate precursor, wherein the molecular formula of the carbonate precursor is as follows: (Mn)0.1～ 0.9Ni0.1～0.8Co0～0.5)1.25CO3·2H2O；
(2) Preparing a lithium-rich manganese-based layered cathode material:
mixing the carbonate precursor obtained in the step (1) with LiOH & H2O or Li2CO3Mixing according to the molar ratio of 1 (1-2), fully grinding to ensure that the particle diameter is 0.5-5 um, uniformly mixing, placing in a muffle furnace, and heating at the rate of 1-5 ℃/min to 700-10%Calcining for 6-24 hours at 00 ℃, and naturally cooling to room temperature to obtain the lithium-rich manganese-based layered cathode material;
(3) preparing an oxygen vacancy lithium-rich manganese-based layered cathode material:
and (3) uniformly dispersing the lithium-rich manganese-based layered positive electrode material obtained in the step (2) in a quartz boat, and placing the quartz boat in a tube furnace. Argon is continuously introduced for 10-60 minutes before the heating is started, then the temperature is raised to 800 ℃ at the speed of 1-5 ℃/min, and the temperature is maintained for 600 minutes. And obtaining the lithium-rich manganese-based layered cathode material containing oxygen vacancies.
The metal salt of cobalt is CoSO4·7H2O、Co(NO3)2·6H2O、CoCl2·6H2O or Co (Ac)2·4H2O。
The metal salt of nickel is NiSO4·6H2O、Ni(NO3)2·6H2O、NiCl2·6H2O or Ni (Ac)2·4H2O。
The metal salt of manganese is MnSO4·H2O、Mn(NO3)2·4H2O、MnCl2·4H2O or Mn (Ac)2·4H2O。
The precipitant is NaOH or Na2CO3、NaHCO3、(NH4)2CO3Or NH4HCO3Any of the above.
An embodiment of the method of the invention is described below:
the first embodiment is as follows:
(1) the metal salt of cobalt, CoSO4·7H2Metal salts of O and Ni NiSO4·6H2MnSO metal salt of O and Mn4·H2Dissolving O in 100mL of water according to a molar ratio of 0.13:0.13:0.54 to ensure that the total molar concentration of metal ions is 2mol/L to obtain a metal ion mixed solution; preparing Na with the molar concentration of 2mol/L2CO3Adding 50mL of solution of the precipitant into the mixed solution of the metal ions under magnetic stirring to generate precipitates, stirring for 12 hours, performing centrifugal separation, and respectively using deionized water and deionized waterWashing the precipitate with water and ethanol for 2 times, and drying the precipitate in an oven at 80 ℃ for 12 hours to obtain a carbonate precursor, wherein the molecular formula of the carbonate precursor is as follows: (Ni)0.13Co0.13Mn0.54)1.25CO3·2H2O。
(2) Mixing the carbonate precursor obtained in the step (1) with LiOH & H2O or Li2CO3Fully grinding and uniformly mixing the materials according to the molar ratio of 1:1.08, placing the materials in a muffle furnace, calcining the materials at 900 ℃ for 12 hours at the heating rate of 3-5 ℃/min, and naturally cooling the materials to room temperature to obtain the corresponding lithium-rich manganese-based layered cathode material of the lithium ion battery.
(3) And (3) uniformly dispersing 1-6g of the lithium-rich manganese-based layered positive electrode material obtained in the step (2) in a quartz boat, and placing the quartz boat in a tube furnace. Argon is continuously introduced for 10-60 minutes before heating is started, then the temperature is raised to 300 ℃ at the speed of 1-5 ℃/min, and the temperature is preserved for 300 minutes. And obtaining the lithium-rich manganese-based layered cathode material containing oxygen vacancies.
Example two:
(1) the metal salt NiCl of nickel2·6H2Metal salts of O and Mn, MnCl2·4H2Dissolving O in 100mL of water according to a molar ratio of 0.2:0.6 to ensure that the total molar concentration of metal ions is 2mol/L to obtain a metal ion mixed solution; preparing 50mL of NaOH solution with the molar concentration of 2mol/L, adding the precipitant solution into the metal ion mixed solution under magnetic stirring to generate a precipitate, stirring for 8 hours, performing centrifugal separation, respectively washing the precipitate with deionized water and absolute ethyl alcohol for 2 times, and drying the precipitate in an oven at 80 ℃ for 12 hours to obtain a hydroxide precursor, wherein the molecular formula of the hydroxide precursor is as follows: ni0.2Mn0.6(OH)1.6·2H2O。
(2) The hydroxide precursor obtained in the step (1) and LiOH & H2O or Li2CO3Fully grinding and uniformly mixing the materials according to the molar ratio of 1:1.05, placing the materials in a muffle furnace, calcining the materials at 900 ℃ for 12 hours at the heating rate of 3-5 ℃/min, and naturally cooling the materials to room temperature to obtain the corresponding lithium-rich manganese-based layered cathode material of the lithium ion battery.
(3) And (3) uniformly dispersing 1-6g of the lithium-rich manganese-based layered positive electrode material obtained in the step (2) in a quartz boat, and placing the quartz boat in a tube furnace. Argon is continuously introduced for 10-60 minutes before heating is started, then the temperature is raised to 400 ℃ at the speed of 1-5 ℃/min, and the temperature is preserved for 300 minutes. And obtaining the lithium-rich manganese-based layered cathode material containing oxygen vacancies.
Example three:
(1) metal salt of nickel Ni (NO)3)2·6H2Metal salts of O and manganese, Mn (NO)3)2·4H2Dissolving O in 100mL of water according to a molar ratio of 0.2:0.6 to ensure that the total molar concentration of metal ions is 2mol/L to obtain a metal ion mixed solution; preparing NaHCO with the molar concentration of 2mol/L3Adding the precipitant solution into the metal ion mixed solution under magnetic stirring to generate a precipitate, stirring for 8 hours, performing centrifugal separation, respectively washing the precipitate with deionized water and absolute ethyl alcohol for 2 times, and drying the precipitate in an oven at 80 ℃ for 12 hours to obtain a bicarbonate precursor, wherein the molecular formula of the bicarbonate precursor is as follows: ni0.2Mn0.6(HCO3)1.6·2H2O。
(2) Reacting the bicarbonate precursor obtained in the step (1) with LiOH & H2O or Li2CO3Fully grinding and uniformly mixing the materials according to the molar ratio of 1:1.05, placing the materials in a muffle furnace, calcining the materials at 900 ℃ for 12 hours at the heating rate of 3-5 ℃/min, and naturally cooling the materials to room temperature to obtain the corresponding lithium-rich manganese-based layered cathode material of the lithium ion battery.
(3) And (3) uniformly dispersing 1-6g of the lithium-rich manganese-based layered positive electrode material obtained in the step (2) in a quartz boat, and placing the quartz boat in a tube furnace. Argon is continuously introduced for 10-60 minutes before heating is started, then the temperature is raised to 600 ℃ at the speed of 1-5 ℃/min, and the temperature is preserved for 200 minutes. And obtaining the lithium-rich manganese-based layered cathode material containing oxygen vacancies.
Example four:
(1) a metal salt of nickel Ni (Ac)2·4H2Metal salts of O and manganese Mn (Ac)2·4H2O in a molar ratio of 0.2:0.6Dissolving the mixture into 100mL of water in proportion to ensure that the total molar concentration of metal ions is 2mol/L to obtain a metal ion mixed solution; preparing (NH) with the molar concentration of 2mol/L4)2CO3Adding the precipitant solution into the metal ion mixed solution under magnetic stirring to generate a precipitate, stirring for 8 hours, performing centrifugal separation, respectively washing the precipitate with deionized water and absolute ethyl alcohol for 2 times, and drying the precipitate in an oven at 80 ℃ for 12 hours to obtain an acetate precursor, wherein the molecular formula of the acetate precursor is as follows: (Ni)0.2Mn0.6)1.25CO3·2H2O。
(2) Mixing the acetate precursor obtained in the step (1) with LiOH & H2O or Li2CO3Fully grinding and uniformly mixing the materials according to the molar ratio of 1:1.05, placing the materials in a muffle furnace, calcining the materials at 900 ℃ for 12 hours at the heating rate of 3-5 ℃/min, and naturally cooling the materials to room temperature to obtain the corresponding lithium-rich manganese-based layered cathode material of the lithium ion battery.
(3) And (3) uniformly dispersing 1-6g of the lithium-rich manganese-based layered positive electrode material obtained in the step (2) in a quartz boat, and placing the quartz boat in a tube furnace. Argon is continuously introduced for 10-60 minutes before heating is started, then the temperature is raised to 600 ℃ at the speed of 1-5 ℃/min, and the temperature is preserved for 300 minutes. And obtaining the lithium-rich manganese-based layered cathode material containing oxygen vacancies.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.