A method for stabilizing a lithium-ion battery manganese-based material

Abstract

The application provides a kind of stabilization treatment method of lithium ion battery manganese-based material, including the mixing of deionized water, hydrogen peroxide and acid to obtain a stabilization treatment aqueous solution, and adding the aqueous solution into a glass container;The manganese-based material to be stabilized is placed in the glass container, and after stirring, the aqueous solution is heated to 50-200℃, and the stabilization treatment is carried out;After stabilization treatment, stop heating, and after the glass container cools down, pour out the aqueous solution and manganese-based material and perform suction filtration to obtain manganese-based material powder;Dry and calcine the manganese-based material powder to obtain the stabilized manganese-based material.The application uses an aqueous solution with both acidity and oxidizing properties for pretreatment, and stabilizes the manganese-based material for lithium ion batteries, so that the manganese-based material has strong resistance to large current impact and cycle stability, and improves the adaptability of lithium ion battery systems based on manganese-based materials to complex working conditions and extreme environments.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energy materials, and particularly relates to a stabilization treatment method of a lithium ion battery manganese-based material. BACKGROUND

[0002] With the continuous improvement of the performance of lithium ion batteries and the rapid growth of the market, lithium ion batteries have been applied in the fields of electric vehicles and handheld electronic products. However, with the continuous expansion of the breadth and depth of application, it is urgent to improve the ability to cope with complex working conditions and harsh extreme environments in order to improve the safety and use efficiency of lithium ion batteries. Especially when lithium ion batteries are used as range extenders or power batteries of various electric loading platforms, the batteries are in high-frequency large-current charging and discharging or floating charging conditions for a long time, and the continuous discharge capacity in high-altitude and cold regions and the requirement for instantaneous large-current power supply put forward higher requirements for the low-temperature large-current discharge performance of the batteries. Manganese-based positive electrode materials, such as layered structure LiMnO2, spinel structure Li2Mn2O4 and layered lithium-rich manganese-based material xLi2MnO3(1-x)LiTMO2(TM-transition metal), all have high theoretical specific capacity, high safety and low cost advantages, and thus become a hot spot in the research of lithium ion battery positive electrode materials. However, due to the Jahn-Teller effect of Mn 3+ , the transformation between Mn 3+ / Mn 4+ during charging and discharging will cause the structure of manganese-based positive electrode materials to be unstable, thus leading to a short cycle life. Although manganese-based positive electrode materials are of great significance to the sustainable development and performance improvement of lithium ion batteries, the Jahn-Teller effect of Mn 3+ has become a bottleneck for improving the structural stability. This effect will lead to manganese dissolution, which will have the following effects: first, the dissolution of manganese in the positive electrode will lead to the collapse of the crystal structure of the material, which is not conducive to the maintenance of the cycle life; second, the dissolution of manganese will lead to a decrease in the positive active material, a decrease in the capacity of the material, and an acceleration of the attenuation of the battery life; third, the dissolution of manganese will enrich on the surface of the negative electrode material, affecting the conductivity of the negative electrode and occupying active sites, hindering the embedding of lithium, and thus inducing the formation of lithium dendrites on the surface of the negative electrode, piercing the separator and causing internal short circuit and thermal runaway. A large number of literature researches fully show that controlling the dissolution of manganese in the electrode material is extremely critical to the performance of the battery.

[0003] The Jahn-Teller effect, also known as Jahn-Teller distortion, was first proposed by H.A. Jahn and E. Teller in 1937, which describes that the asymmetric occupation of electrons in a degenerate orbital will cause the distortion of the geometric structure of the molecule, thereby reducing the symmetry of the molecule and the degeneracy of the orbital, and further lowering the energy of the system. A typical example is Mn 3+When the complex of the ion is in an octahedral configuration, the d orbitals split into t2g and eg groups, and the ground state is assumed to have the electronic configuration t2g6eg3. There is only one electron in the eg orbitals (including dz2 and dx2-y2 orbitals), which leads to the asymmetry of the electron distribution, and the electrons in the dz2 and dx2-y2 orbitals shield the Mn nucleus in different directions to different degrees. In order to stabilize the Mn 3+ ion, the two longitudinal Mn-O bonds will be elongated, and the four horizontal Mn-O bonds will be shortened. The differential charge density map clearly shows that the Mn 3+ and Mn 4+ ions form an MnO 6 octahedron. At present, many methods have been reported to suppress the Jahn-Teller effect, stabilize the structure of manganese-based layered oxides, and improve their performance. These methods include: (1) introducing manganese / oxygen vacancies to control the bond length and adjust the valence state of manganese to regulate the influence of the Jahn-Teller effect; (2) adjusting the composition and ratio in the material to adjust the valence state of manganese to regulate the influence of the Jahn-Teller effect; (3) using methods such as high-pressure synthesis to stabilize the metastable structure at normal pressure to obtain a LMLO material without the Jahn-Teller effect; (4) designing a local structure to effectively control the distortion of the material. Some researchers believe that in order to effectively suppress the cooperative Jahn-Teller effect, it is necessary to destroy the long-range order of the Jahn-Teller effect from the inside of the material particles, and to realize that the Jahn-Teller effect of manganese in the particles cannot be coordinated. Under the guidance of this concept, a new method is proposed to suppress the Jahn-Teller effect by regulating the interface orbital order of the layered and spinel structures. In the heterostructure of the layered and spinel structures, by changing the orientation relationship of the manganese dz2 orbital of the layered and spinel domains, the long-range order of the Jahn-Teller effect of the Mn 3+ in the particle can be effectively destroyed. Some researchers believe that, especially when the dz2 orbital of Mn 3+ at the interface presents a vertical interface orbital order, the suppression effect on the Jahn-Teller effect is the largest.

[0004] In view of the above problems, considering that through conventional synthesis methods, as long as there is Mn 3+ , the effect can only be simulated and cannot be completely eliminated, in order to obtain high-stability manganese-based materials for lithium-ion batteries, in recent years, many scholars have explored more convenient and effective preparation methods, but most of them are in the synthesis process, such as the above-mentioned doping, coating and other treatments, and there is still no report on a simple method for batch and continuous stabilization of manganese-based materials, especially a manganese-based material stabilization method that can ensure the consistency of the material to meet the needs of battery processing. Based on the above considerations,

[0005] The present application is based on the surface structure and element composition characteristics of manganese-based materials, and innovatively proposes a method of pre-treatment by using an aqueous solution with both acidity and oxidizing property, to stabilize the manganese-based materials for lithium ion batteries while maintaining the structure and electrochemical properties of the manganese-based materials as much as possible, so that the manganese-based materials have strong resistance to large current impact and cycle stability, and the adaptability of the lithium ion battery system based on the manganese-based materials to complex working conditions and extreme environments is improved. SUMMARY

[0006] (I) Technical problems to be solved

[0007] The present application proposes a stabilization treatment method for manganese-based materials of lithium ion batteries to solve the technical problem of how to stabilize the manganese-based materials for lithium ion batteries so that the manganese-based materials have strong resistance to large current impact and cycle stability.

[0008] (II) Technical solutions

[0009] In order to solve the above technical problems, the present application proposes a stabilization treatment method for manganese-based materials of lithium ion batteries, which comprises the following steps:

[0010] S1. Mix hydrogen peroxide, acid and deionized water to obtain a stabilization treatment aqueous solution, and add the aqueous solution to a glass container;

[0011] S2. Place the manganese-based material to be stabilized in the glass container, stir the aqueous solution and heat it to 50-200℃, and then perform stabilization treatment;

[0012] S3. After stabilization treatment, stop heating, and after the glass container cools down, pour out the aqueous solution and the manganese-based material and perform suction filtration to obtain a manganese-based material powder;

[0013] S4. Dry and calcine the manganese-based material powder to obtain a stabilized manganese-based material.

[0014] Further, in step S1, the mass ratio of hydrogen peroxide to acid is 1:(100-0.01), and the mass ratio of the total mass of hydrogen peroxide and acid to the mass of deionized water is 1:(100-0.01).

[0015] Further, the manganese-based material is one or more of lithium manganate, nickel lithium manganate, nickel cobalt lithium manganate, nickel aluminum lithium manganate, cobalt lithium manganate, lithium manganese phosphate, and lithium manganese iron phosphate.

[0016] Further, the acid is one or more of nitric acid, acetic acid, hydrochloric acid, oxalic acid, hypochlorous acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, sulfurous acid, hydrogen sulfonic acid, citric acid, almond acid, and tartaric acid.

[0017] Further, in step S2, the time for the stabilization treatment is 0.5-24 hours.

[0018] Further, in step S4, the manganese-based material is dried in a blast oven at 120℃ for 24 hours, and then calcined in a muffle furnace at 300-750℃ for 0.5-24 hours to obtain the manganese-based material after the stabilization treatment.

[0019] Further, in step S1, a magnetic stirrer is placed in the glass container; and in step S2, the glass container is placed on a magnetic heating stirrer, and the magnetic stirrer is kept rotating at a constant speed to ensure that the manganese-based material is in sufficient contact with the aqueous solution.

[0020] Further, in step S2, the rotating speed of the magnetic stirrer is 100-3000 rpm.

[0021] (III) Beneficial Effects

[0022] The present application provides a method for stabilization treatment of a manganese-based material for lithium ion batteries, which comprises mixing deionized water, hydrogen peroxide and acid to obtain a stabilization treatment aqueous solution, and adding the aqueous solution into a glass container; placing the manganese-based material to be stabilized into the glass container, and after stirring, heating the aqueous solution to 50-200℃ to perform the stabilization treatment; after the stabilization treatment, stopping the heating, and after the glass container is cooled, pouring out the aqueous solution and the manganese-based material and performing suction filtration to obtain a manganese-based material powder; and drying and calcining the manganese-based material powder to obtain the manganese-based material after the stabilization treatment. The present application uses an aqueous solution with both acidity and oxidizing property for pretreatment, and on the basis of maintaining the structure and electrochemical properties of the manganese-based material as much as possible, the manganese-based material for lithium ion batteries is subjected to the stabilization treatment, so that the manganese-based material has strong resistance to large current impact and cycle stability, and the adaptability of the lithium ion battery system based on the manganese-based material to complex working conditions and extreme environments is improved, and the present application has good application prospect in the field of batteries.

[0023] The beneficial effects and innovative points of the present application specifically include:

[0024] 1. The present application combines the solubility of acid ions in the aqueous solution and the strong oxidizing property of hydrogen peroxide to remove unstable manganese ions on the surface and corners of the manganese-based material, and the reaction is a solid-liquid two-phase reaction, the separation of the manganese-based material after the treatment is simple to implement, and the sustainable progress of the stabilization treatment reaction can be ensured.

[0025] 2. Considering that the types of manganese-based materials are different, their surface structures and components are different, the concentrations and combination ratios of the acid and hydrogen peroxide in the aqueous solution involved in the present application can be adjusted, and the reaction time and temperature can be flexibly controlled, so that different degrees or selective regulation of the surface stabilization treatment of the manganese-based material can be realized, and customized scheme design can be facilitated.

[0026] 3. Unlike the traditional element doping, coating and other processing methods, the present application performs a stabilization treatment on the material prepared by the conventional method, especially on the manganese-based material without doping and coating modification, and also has a stabilization treatment effect, thus, unlike the traditional doping and coating treatment method, slight fluctuation of the process condition will affect the consistency of the material, the manganese-based material after the stabilization treatment of the present application method will not affect the consistency, thereby facilitating the subsequent corresponding cell distribution and group design.

[0027] 4. The present application method has simple operation requirements, low scale difficulty, high safety and efficiency, no waste discharge, green environmental protection, high economic efficiency, can simplify the stabilization treatment process of manganese-based material, does not damage the intrinsic structure and electrochemical performance of manganese-based material, can strengthen the application efficiency in lithium ion battery, and has good application prospect in the fields of material processing and battery. BRIEF DESCRIPTION OF DRAWINGS

[0028] Fig. 1 SEM picture of the untreated LiMn2O4 material in Example 1;

[0029] The scale in the figure is 5000nm;

[0030] Fig. 2 XRD picture of the untreated LiMn2O4 material in Example 1;

[0031] The horizontal coordinate in the figure is 2θ angle, and the vertical coordinate is any intensity without unit;

[0032] Fig. 3 TEM picture of the untreated LiMn2O4 material in Example 1;

[0033] The scale in the figure is 100nm;

[0034] Fig. 4 SEM picture of the LiMn2O4 material after stabilization treatment in Example 1;

[0035] The scale in the figure is 2000nm;

[0036] Fig. 5 XRD picture of the LiMn2O4 material after stabilization treatment in Example 1;

[0037] The horizontal coordinate in the figure is 2θ angle, and the vertical coordinate is any intensity without unit;

[0038] Fig. 6 TEM picture of the LiMn2O4 material after stabilization treatment in Example 1;

[0039] The scale in the figure is 100nm;

[0040] Fig. 7 Comparison of high current cycling performance of LiMn2O4 materials without treatment and after stabilization treatment in Example 1;

[0041] In the figure, the vertical axis is mAh / g; the horizontal axis is the number of cycles. DETAILED DESCRIPTION

[0042] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below with reference to the accompanying drawings and examples.

[0043] Example 1

[0044] 10 g of hydrogen peroxide, 5 g of nitric acid, and 200 g of deionized water were added to a glass container, and a magnetic stirrer was placed in the glass container. 15 g of LiMn2O4 to be cleaned (SEM, XRD, and TEM of LiMn2O4 were as follows: Figs. 1-3 The aqueous solution was heated to 75°C and stabilized for 8 hours, then the heating was stopped. After the glass container was cooled, the aqueous solution and the LiMn2O4 material in the glass container were poured out and filtered to obtain LiMn2O4 material powder. The LiMn2O4 was placed in a blast oven at 120°C for 24 hours and then calcined in a muffle furnace at 500°C for 2 hours to obtain a stabilized LiMn2O4 material. The SEM, XRD and TEM of the stabilized LiMn2O4 were shown as follows: Figs. 4-6 As shown in the figure, from the comparison of SEM and TEM images of LiMn2O4 materials before and after treatment, the surface of the treated LiMn2O4 material is smoother and rounder. Based on the comparison of XRD patterns, it can be confirmed that the crystal phase of the LiMn2O4 material remains unchanged. The electrochemical performance of the LiMn2O4 material before and after stabilization treatment was evaluated using 2032 button cells, as shown in the figure. Fig. 7 As shown, it can be seen that the high current (5C) cycling stability of the LiMn2O4 material after stabilization treatment is significantly better than that of the LiMn2O4 material without stabilization treatment.

[0045] Example 2

[0046] Add 10g hydrogen peroxide, 5g nitric acid and 200g deionized water into a glass container, and place a magnetic stirrer in the glass container. 1.5 Mn 0.5O4 was placed in a glass container, and the glass container was placed on a magnetic heating stirrer. The magnetic stirrer kept rotating at a constant speed of 500 rpm to prevent boiling. The aqueous solution was heated to 75 ° C. After stabilization for 8 hours, the heating was stopped. After the glass container cooled, the aqueous solution in the glass container and LiNi 1.5 Mn 0.5 The O4 material was poured out and filtered to obtain LiNi 1.5 Mn 0.5 O4 material powder, LiNi 1.5 Mn 0.5 O4 was dried in a blast oven at 120°C for 24 hours, and then calcined in a muffle furnace at 500°C for 2 hours to obtain stabilized LiNi 1.5 Mn 0.5 O4 material, LiNi after stabilization treatment 1.5 Mn 0.5 The surface of the O4 material is smoother and rounder, and the crystal phase of the material remains unchanged. 2032 button cells were used to evaluate the LiNi before and after stabilization treatment. 1.5 Mn 0.5 Electrochemical properties of O4 materials, LiNi after stabilization treatment 1.5 Mn 0.5 The high current (3C) cycling stability of O4 material is significantly better than that of unstabilized LiNi 1.5 Mn 0.5 O4 material.

[0047] Example 3

[0048] 1g nitric acid, 3g hydrogen peroxide, and 200g deionized water were added to a glass container, and a magnetic stirrer was placed in the glass container. 15g LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 was placed in a glass container, and the glass container was placed on a magnetic heating stirrer. The magnetic stirrer kept rotating at a constant speed of 500 rpm to prevent boiling. The aqueous solution was heated to 75 ° C. After stabilization for 8 hours, the heating was stopped. After the glass container cooled, the aqueous solution in the glass container and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 The O2 material was poured out and filtered to obtain LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 material powder, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 is placed in a blast oven at 120 ° C for 24 hours, and then placed in a muffle furnace for calcination at 500 ° C for 4 hours to obtain stabilized LiNi 1 / 3Co 1 / 3 Mn 1 / 3 O2 material, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 material surface is smoother and rounder, and the crystal phase of the material remains unchanged. The electrochemical performance of LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 material before and after the stabilization treatment, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 material is significantly better than LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 material.

[0049] Through the above examples, the method of the present application can improve the electrochemical performance of the manganese-based material by using the water-soluble stabilization treatment method with both acidity and oxidation, which is much better than the traditional doping and coating method, and will have good popularization and use prospect in the field of material processing and battery.

[0050] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the technical principles of the present application, several improvements and modifications can be made, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A method for stabilizing manganese-based materials for lithium-ion batteries, characterized in that: The stabilization treatment method comprises the following steps: S1. A stabilized aqueous solution was obtained by mixing hydrogen peroxide, nitric acid, and deionized water, and the aqueous solution was added to a glass container, and a magnetic stirrer was placed in the glass container; the mass ratio of hydrogen peroxide and nitric acid was 1:(100-0.01), and the mass ratio of the total mass of hydrogen peroxide and nitric acid to deionized water was 1:(100-0.01); S2. The manganese-based material to be stabilized is placed in a glass container, the glass container is placed on a magnetic heating stirrer, the magnetic stirring bar is kept rotating at a constant speed to ensure that the manganese-based material is in full contact with the aqueous solution, the rotation speed of the magnetic stirring bar is 100 to 3000 rpm; After stirring, the aqueous solution is heated to 50-200° C. and stabilized for 0.5-24 hours; the manganese-based material is one or more of lithium manganate, lithium nickel manganate, lithium nickel cobalt manganate, lithium nickel aluminum manganate, lithium cobalt manganate, lithium manganese phosphate, and lithium iron manganese phosphate; S3. After stabilization, heating was stopped, and after the glass container was cooled, the aqueous solution and the manganese-based material were poured out and filtered to obtain a manganese-based material powder; S4. The manganese-based material is placed in a blast oven at 120° C. and dried for 24 hours, and then placed in a muffle furnace and calcined at 300-750° C. for 0.5-24 hours to obtain a stabilized manganese-based material.

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