CN108923042A - Sodium-ion battery stratiform manganese-based anode material and preparation method thereof - Google Patents

Abstract

The invention discloses a layered manganese-based positive electrode material for a sodium ion battery and a preparation method thereof. The general formula of the positive electrode material is Na _y Mn _3‑x M _x O ₇ , wherein M is Ti, V, Cr, Fe, Co, Ni, Mg, Zn, Zr, Nb, Ru, Ir or Cu, and 0.1≤x≤2, 0≤y≤4. The layered manganese-based material of the sodium ion battery of the present invention has a triclinic crystal structure, and has a structural characteristic of no phase change in a wide voltage range, which can effectively improve the structural stability and air exposure of the manganese-based layered positive electrode material during charge and discharge. The stability of the material can reduce the volume change of the material in the electrochemical process, thereby improving the performance of the battery; the shape and size of the material are uniform, and the particle size is 0.5-10 μm, so that the positive electrode material has both good environmental stability and excellent performance. Cycle life; it has the characteristics of high specific capacity, high discharge voltage and excellent battery performance; compared with the synthesis of traditional layered oxide materials, the present invention has a lower sintering temperature, which can reduce energy consumption and save costs.

Description

Layered manganese-based positive electrode material for sodium ion battery and preparation method thereof

technical field

The invention belongs to the technical field of electrochemistry, and relates to a battery material, in particular to a layered manganese-based cathode material for a sodium ion battery and a preparation method thereof.

Background technique

Na-ion batteries are characterized by abundant raw materials and low cost, and are considered to have great prospects in large-scale energy storage systems and smart grid applications. Among them, the development of high-efficiency cathode materials is the key link to promote the commercialization of sodium-ion batteries. Among many cathode materials, transition metal layered oxides have high theoretical specific capacity, diverse components and simple synthesis, and are considered to be one of the most promising cathode materials for commercialization. However, layered transition metal oxide cathode materials also have some problems, especially their poor electrochemical stability, and the structure of the material is easy to collapse, which seriously affects the cycle life of the battery. In the electrochemical process, the reversible deintercalation of sodium ions in the layered material often causes a series of phase transitions in the material, such as: phase transition from O3 phase to P3 phase or P2 phase to O2 phase, accompanied by a large Volume changes, which will greatly reduce the structural stability of the material, resulting in a decrease in the cycle life of the battery. Therefore, how to reduce the phase transition of positive electrode materials and ensure the stability of materials in the electrochemical process is considered to be one of the most important issues in the field of sodium-ion batteries. After the continuous efforts of scientists, one of the strategies is to stabilize the structure of the material by doping inactive metal ions. This strategy can inhibit part of the phase transition, but it is often accompanied by the loss of reversible specific capacity of the material. Another strategy is to force the material to charge and discharge only in the range without phase change by compressing the working voltage range of the battery. This strategy cannot fully utilize the characteristics of the material, so it often only provides a small reversible ratio Capacity, it is difficult to apply in practice. Therefore, only cathode materials designed to achieve no phase transition in a wide voltage range can provide high specific capacity and high cycle stability and exist practical cathode materials, but this is still a serious challenge.

Contents of the invention

Technical problem to be solved: In order to overcome the deficiencies of the prior art and obtain a positive electrode material capable of providing high specific capacity and high cycle stability and having practicability, the invention provides a layered manganese-based positive electrode material for a sodium ion battery and its Preparation.

Technical solution: layered manganese-based positive electrode material for sodium ion batteries, the general formula of the positive electrode material is Na _y Mn _3-x M _x O ₇ , where M is Ti, V, Cr, Fe, Co, Ni, Mg, Zn , Zr, Nb, Ru, Ir or Cu, and 0.1≤x≤2, 0≤y≤4.

Preferably, the positive electrode material has a triclinic crystal structure. And it has no phase change characteristics in a wide voltage range.

Preferably, the positive electrode material is in granular form with a particle size of 0.5-10 μm.

The preparation method of the layered manganese-based positive electrode material of any one of the above sodium ion batteries, the method is: mixing the sodium salt, manganese carbonate and metal oxide, pressing the tablet, and then calcining at 400-1100 ° C to obtain the sodium ion battery Layered manganese-based cathode materials.

Preferably, the sodium salt is at least one of sodium nitrate and sodium chloride.

Preferably, the metal oxide is TiO ₂ , V ₂ O ₅ , Cr ₂ O ₃ , Fe ₂ O ₃ , CoO, NiO, MgO, ZnO, ZrO ₂ , Nb ₂ O ₅ , RuO ₂ , IrO ₂ , CuO at least one of the

Preferably, the molar ratio of sodium element, manganese element and other metal elements is 0.1-4:2.9-1:0.1-2.

Preferably, the method adopts ball milling method for mixing, the ball milling speed is 100-300r/min, and the ball milling time is 0.5-50h. The ball milling method can fully mix the precursors of sodium salt, manganese carbonate and other metal oxides, which is convenient for subsequent reactions and can be carried out fully and evenly.

Preferably, the pressure condition for tableting is 1-50 MPa. Tabletting under this pressure can press the precursor mixture more tightly, and the distance between the precursor particles is closer, so that the reaction between the precursors is more uniform and sufficient during the subsequent calcination.

Preferably, the calcination atmosphere is oxygen or air, the calcination time is 1-48h, and the temperature rise rate is 1-30°C/min.

The invention adopts a solid-phase sintering method, and can form a layered oxide with a triclinic crystal structure by controlling the reaction conditions, and has the structural characteristic of no phase transition in a wide voltage range. The precursor substances of the sample diffused each other at high temperature, so that the microscopic discrete particles gradually formed a continuous solid-state layered structure, thereby obtaining a stable sodium-containing triclinic layered oxide material.

The preparation principle of the layered manganese-based positive electrode material for the sodium ion battery of the present invention is that the positive electrode material is composed of two or more metal ions, has a triclinic layered crystal structure, and has no phase transition in a wide voltage range. Characteristic, in the cathode material of the present invention, Mn element content is higher, and object is to can reduce material price and improve battery capacity. The layered positive electrode material of the sodium ion battery of the present invention has a layered crystal structure of the triclinic system, and the material shows a structural characteristic of no phase change in a wide voltage range, so that the material has a better electrochemical process. The small volume change makes the assembled battery have a long stable cycle life. The layered positive electrode material of the sodium ion battery of the present invention has a triclinic crystal structure in its crystal structure, and this material has a structural characteristic of no phase change in a wide voltage range, reduces the volume change of the material, and effectively improves the manganese-based layered positive electrode. The structural stability of the material during charge and discharge as well as its stability when exposed to air improves battery performance.

Beneficial effects: (1) The layered manganese-based material of the sodium ion battery of the present invention has a triclinic crystal structure, and has a structural characteristic of no phase transition in a wide voltage range, which can effectively improve the performance of the manganese-based layered positive electrode material in the charging and discharging process. Structural stability and stability when exposed to air, reducing the volume change of the material in the electrochemical process, thereby improving battery performance; (2) The positive electrode material prepared by the present invention has uniform shape and size, and a particle size of 0.5-10 μm. The voltage range has no phase transition structural characteristics, so that the positive electrode material has both good environmental stability and excellent cycle life; (3) when the positive electrode material prepared by the present invention is used as the positive electrode of a sodium ion battery, the charge and discharge process is highly It is reversible, has the characteristics of high specific capacity, high discharge voltage, and excellent battery performance. It has a triclinic crystal structure and has no phase change in a wide voltage range. It has broad application prospects; (4) Compared with the synthesis of traditional layered oxide materials, the present invention has a lower sintering temperature, which can reduce energy consumption and save costs.

Description of drawings

Fig. 1 is the X-ray powder diffraction spectrogram of the layered manganese-based positive electrode material of sodium ion battery prepared in Example 1 of the present invention;

2 is a scanning electron microscope image of the layered manganese-based positive electrode material for a sodium ion battery prepared in Example 1 of the present invention;

Fig. 3 is the transmission electron micrograph of the layered manganese-based positive electrode material of the sodium ion battery prepared in Example 1 of the present invention;

Fig. 4 is the charge-discharge curve and in-situ X-ray powder diffraction spectrum of the layered manganese-based positive electrode material for sodium ion battery prepared in Example 1 of the present invention;

Fig. 5 is the typical charge-discharge curve of the layered manganese-based positive electrode material for sodium-ion battery prepared in Example 1 of the present invention;

Fig. 6 is the magnification diagram of the layered manganese-based positive electrode material of the sodium ion battery prepared in Example 1 of the present invention under different current densities;

Fig. 7 is the long cycle performance curve under the current density of 50mA/g of the layered manganese-based positive electrode material for sodium ion battery prepared in Example 1 of the present invention;

Fig. 8 is the long cycle performance curve under the current density of 2000mA/g of the layered manganese-based cathode material for sodium ion battery prepared in Example 1 of the present invention;

Fig. 9 is an X-ray powder diffraction spectrum of the layered manganese-based cathode material for a sodium ion battery prepared in Comparative Example 1 of the present invention exposed to air for 60 days, soaked in water for 5 days and the original material.

Fig. 10 is the electrochemical charge and discharge curves of the layered manganese-based positive electrode material of the sodium ion battery prepared in Comparative Example 1 of the present invention exposed to the air for 60 days, soaked in water for 5 days and the original material.

Detailed ways

The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the spirit and essence of the present invention, the modifications and substitutions made to the methods, steps or conditions of the present invention all belong to the scope of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

Example 1

(1) Accurately weigh NaNO ₃ , MnCO ₃ and CuO of the corresponding mass according to the molar ratio of 4:2:1, add them to the ball mill jar, and then add ball mill balls to it, and ball mill for 5 hours under the condition of 300r/min. The above precursors are mixed evenly.

(2) Press the ball-milled mixture into a disc with a diameter of 16 mm under a pressure of 4 MPa.

(3) Place the flake sample obtained in step (2) in a tube furnace, heat up to 600°C at 5°C/min in an oxygen atmosphere, and calcinate for 4 hours; cool to room temperature with the furnace, and then wash it with ethanol to remove The remaining impurities can be used to obtain the manganese-based positive electrode material for the sodium ion battery, the molecular formula of which is Na ₂ Mn ₂ CuO ₇ , and the material is in the form of powder particles with a particle size of 0.5-10 μm.

The manganese-based positive electrode material of the sodium-ion battery prepared above was characterized, and the results are shown in Figures 1-4. Figure 1 presents a characteristic curve of a triclinic layered oxide, indicating that the sample has a triclinic layered structure. Figure 2 shows that the material has a layered granular structure with a particle size of 0.5-10 μm. Figure 3 shows that the material has a lamellar morphology. It can be seen from Figure 4 that as the charge and discharge progress, the X-ray powder diffraction spectrum of the material has no new peaks, indicating that the material has a structure evolution mechanism without phase transition in a wide voltage range.

Electrochemical performance tests were performed on the triclinic layered manganese-based positive electrode material for sodium-ion batteries prepared above, and the results are shown in Figures 5-8. It can be seen from Figure 5 that the first discharge specific capacity of the material is 106.6mAh g ^-1 under the conditions of 10mA g ^-1 and 2.1-4.05V voltage. The charge and discharge curves of the material are basically coincident after 3 charge and discharge tests. It shows that the charging and discharging process of this material is highly reversible. Figure 6 shows the rate of the material at different current densities, and its specific capacity is still 57.2mAh g ^{-1 at 5000mA g -1 .} In Figure 7, the upper curve represents the charge-discharge Coulomb efficiency, and the lower curve represents the specific capacity of the material. Figure 7 shows that the specific capacity of the battery is still 99.1% of the original after 100 cycles of long-term charge-discharge cycles, and the battery is here The coulombic efficiency of the battery remains above 98% in long charge and discharge cycles. Figure 8 shows that after 1000 cycles of ultra-long charge and discharge cycles, the specific capacity retention rate of the battery is still 95.8%. These results show that the layered material with triclinic crystal structure and no phase transition prepared in Example 1 can indeed optimize the cycle stability of the battery.

The materials prepared by the present invention were exposed to air for 60 days and soaked in water for 5 days, and XRD tests were carried out on them. Fig. 9 is the XRD contrast graph before and after the material of the triclinic layered manganese-based positive electrode material of the sodium-ion battery prepared in Example 1 is exposed to the air for 3 days, and it can be seen from Fig. 9 that the three curves have no obvious change, It shows that the phase of the material in Example 1 does not change after being exposed to the air for 60 days and soaking in water for 5 days, which further illustrates that the material has good stability in the air environment. After the material prepared by the present invention was exposed to the air for 60 days and soaked in water for 5 days, it was collected and dried and then subjected to electrochemical performance test results as shown in Figure 10. As can be seen from Figure 10, the material was exposed to the air for 60 days and soaked After 5 days in water, the electrochemical performance has only slight changes. These two results show that the layered material with triclinic crystal structure and no phase transition prepared in Example 1 can effectively improve the air stability of the material.

Example 2

Change the molar ratio of each substance, according to the molar ratio of 2:1:2, accurately weigh the corresponding mass of NaNO ₃ , MnCO ₃ and CuO, according to the method of steps (1)-(3) in Example 1, prepare sodium The triclinic layered manganese-based positive electrode material for ion batteries has a molecular formula of Na ₂ MnCu ₂ O ₇ .

Example 3

Change the molar ratio of each substance, according to the molar ratio of 2:2.9:0.1, accurately weigh the corresponding mass of NaNO ₃ , MnCO ₃ and CuO, according to the method of steps (1)-(3) in Example 1, prepare sodium Manganese-based cathode material for ion batteries, its molecular formula is Na ₂ Mn _2.9 Cu _0.1 O ₇ .

Example 4

The CuO in Example 1 is replaced by NiO of equimolar amount, according to the method for step (1)-(3) in Example 1, the manganese-based cathode material of sodium-ion battery is prepared, and its molecular formula is Na ₂ Mn ₂ NiO ₇ .

Example 5

The CuO in Example 1 is replaced by CoO of equimolar amount, according to the method of step (1)-(3) in Example 1, the manganese-based cathode material of sodium-ion battery is prepared, and its molecular formula is Na ₂ Mn ₂ CoO ₇ .

Example 6

The CuO in Example 1 is replaced by TiO ₂ in an equimolar amount, and the manganese-based positive electrode material for a sodium-ion battery is prepared according to the method of steps (1)-(3) in Example 1, and its molecular formula is Na ₂ Mn ₂ TiO ₇ .

Example 7

Replace the CuO in Example 1 with 0.5 molar amount of Cr ₂ O ₃ , according to the method of steps (1)-(3) in Example 1, prepare the manganese-based positive electrode material for sodium-ion batteries, and its molecular formula is Na ₂ Mn ₂ CrO ₇ .

Example 8

Replace the CuO in Example 1 with 0.5 molar Fe ₂ O ₃ , according to the method of steps (1)-(3) in Example 1, prepare the manganese-based positive electrode material of the sodium ion battery, and its molecular formula is Na ₂ Mn ₂ FeO ₇ .

Example 9

The CuO in Example 1 is replaced by MgO of equimolar amount, according to the method for step (1)-(3) in Example 1, the manganese-based cathode material of sodium-ion battery is prepared, and its molecular formula is Na ₂ Mn ₂ MgO ₇ .

Example 10

The CuO in Example 1 is replaced by ZnO ₂ in an equimolar amount, and the manganese-based positive electrode material for a sodium ion battery is prepared according to the method of steps (1)-(3) in Example 1, and its molecular formula is Na ₂ Mn ₂ ZnO ₇ .

Example 11

Replace the CuO in Example 1 with 0.5 molar amount of V ₂ O ₅ , according to the method of steps (1)-(3) in Example 1, prepare a manganese-based positive electrode material for a sodium ion battery, and its molecular formula is Na ₂ Mn ₂ VO ₇ .

Example 12

Replace the CuO in Example 1 with 0.5 molar amount of Nb ₂ O ₅ , according to the method of steps (1)-(3) in Example 1, prepare a manganese-based positive electrode material for a sodium ion battery, and its molecular formula is Na ₂ Mn ₂ NbO ₇ .

Example 13

Replace the CuO in Example 1 with ZrO ₂ in an equimolar amount, and prepare the manganese-based positive electrode material for a sodium-ion battery according to the method of steps (1)-(3) in Example 1, and its molecular formula is Na ₂ Mn ₂ ZrO ₇ .

Example 14

Replace the CuO in Example 1 with RuO ₂ in an equimolar amount, and prepare the manganese-based positive electrode material for a sodium-ion battery according to the method of steps (1)-(3) in Example 1, and its molecular formula is Na ₂ Mn ₂ RuO ₇ .

Example 15

The CuO in Example 1 is replaced by IrO ₂ in an equimolar amount, and the manganese-based positive electrode material for a sodium-ion battery is prepared according to the method of steps (1)-(3) in Example 1, and its molecular formula is Na ₂ Mn ₂ IrO ₇ .

Example 16

NaNO in Example ₁ is replaced by NaCl of equimolar amount, according to the method of step (1)-(3) in Example 1, the manganese-based cathode material of sodium-ion battery is prepared, and its molecular formula is Na ₂ Mn ₂ CuO ₇ .

Example 17

The calcination temperature in Example 1 was changed from 600°C to 400°C, and the manganese-based positive electrode material for sodium ion batteries was prepared according to the method of steps (1)-(3) in Example 1, and its molecular formula was Na ₂ Mn ₂ CuO ₇ .

Example 18

The calcination temperature in Example 1 was changed from 600°C to 1100°C, and the manganese-based positive electrode material for sodium ion batteries was prepared according to the method of steps (1)-(3) in Example 1, and its molecular formula was Na ₂ Mn ₂ CuO ₇ .

Example 19

The oxygen in the calcination atmosphere in Example 1 was replaced with air, and the manganese-based positive electrode material for sodium ion batteries was prepared according to the method of steps (1)-(3) in Example 1, and its molecular formula was Na ₂ Mn ₂ CuO ₇ .

In summary, the preparation method of the material of the present invention is simple, the raw material is abundant, the price is low, and the degree of practicality is high. It has good stability in wet air and organic electrolyte. Moreover, when this material is assembled into a sodium-ion battery, the structural stability of the material during charging and discharging can be greatly improved, and the positive electrode material shows excellent cycle stability and rate performance. This method has good performance in optimizing the performance of sodium-ion battery energy storage devices. application prospects.

Claims (10)

1. sodium-ion battery stratiform manganese-based anode material, which is characterized in that the general formula of the positive electrode is Na_yMn_3-xM_xO₇, Middle M is Ti, V, Cr, Fe, Co, Ni, Mg, Zn, Zr, Nb, Ru, Ir or Cu, and 0.1≤x≤2,0≤y≤4.

2. sodium-ion battery stratiform manganese-based anode material according to claim 1, which is characterized in that the positive electrode tool There is anorthic crystal structure.

3. sodium-ion battery stratiform manganese-based anode material according to claim 1, which is characterized in that the positive electrode is in Graininess, partial size are 0.5-10 μm.

4. the preparation method of any sodium-ion battery stratiform manganese-based anode material of claim 1-3, which is characterized in that described Method is：Tabletting after sodium salt, manganese carbonate and metal oxide are mixed, then 400-1100 DEG C of calcining, obtains sodium-ion battery Stratiform manganese-based anode material.

5. the preparation method of sodium-ion battery stratiform manganese-based anode material according to claim 4, which is characterized in that described Sodium salt is at least one of sodium nitrate and sodium chloride.

6. the preparation method of sodium-ion battery stratiform manganese-based anode material according to claim 4, which is characterized in that described Metal oxide is TiO₂、V₂O₅、Cr₂O₃、Fe₂O₃、CoO、NiO、MgO、ZnO、ZrO₂、Nb₂O₅、RuO₂、IrO₂, in CuO extremely Few one kind.

7. the preparation method of sodium-ion battery stratiform manganese-based anode material according to claim 4, which is characterized in that sodium member The molar ratio of element, manganese element and other metallic elements is 0.1-4:2.9-1:0.1-2.

8. the preparation method of sodium-ion battery stratiform manganese-based anode material according to claim 4, which is characterized in that described Method is mixed using ball-milling method, ball milling speed 100-300r/min, Ball-milling Time 0.5-50h.

9. the preparation method of sodium-ion battery stratiform manganese-based anode material according to claim 4, which is characterized in that tabletting Pressure condition be 1-50MPa.

10. the preparation method of sodium-ion battery stratiform manganese-based anode material according to claim 4, which is characterized in that forge The atmosphere of burning is oxygen or air, and calcination time 1-48h, heating rate is 1-30 DEG C/min.