A multiphase heterostructure sodium-ion battery metal oxide cathode material and its preparation method

Abstract

This invention belongs to the field of sodium-ion battery material technology, specifically relating to a multiphase heterostructure sodium-ion battery metal oxide cathode material and its preparation method. The metal oxide cathode material of this invention is composed of at least two crystal phases selected from monoclinic P′3, cubic, hexagonal P2, and hexagonal P3. The preparation process includes: dissolving Ni and Mn sources in deionized water, adding a precipitant and ethylene glycol, and obtaining a precursor through a hydrothermal reaction; mixing the precursor with Co, Cu, and Na sources, and calcining to obtain the metal oxide cathode material. The multiphase heterostructure prepared by this invention is highly controllable, the operation process is simple, and it is applicable to other synthesis methods, thus facilitating industrial production. The obtained cathode material can mitigate structural distortion caused by phase transitions during charging and discharging, and improve the Na+ efficiency. + Reaction kinetics, thereby achieving excellent rate performance and cycle stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sodium ion battery materials, and particularly relates to a multiphase heterostructure type sodium ion battery metal oxide positive electrode material and a preparation method thereof. BACKGROUND

[0002] With the large-scale application of lithium ion batteries in electric vehicles and hybrid electric vehicles, the production cost of lithium ion batteries is increasing due to the scarcity of lithium resources and uneven distribution in the earth's crust. Low-cost sodium ion batteries can replace traditional lead-acid batteries due to their high safety and wide temperature range performance, and are widely used in new energy vehicles and grid energy storage fields. However, the low specific energy density caused by low electrode potential and relatively high molar mass restricts the broad application prospect of sodium ion batteries (SIB). The research and development of metal oxide positive electrodes with high theoretical capacity and simple preparation process play a crucial role in realizing high-energy SIBs.

[0003] Metal oxide positive electrode (Na x TMO2, 0 < x < 1, TM = Mn, Ni, Co, Cu, Ti, Fe, Ru, etc.) has controllable multi-component and complex phase structure, which can provide adjustable microstructure, stress and strain, and electronic configuration, thereby affecting the structural stability and anion redox activity under continuous electrochemical behavior. However, rapid capacity decay and voltage hysteresis caused by phase transition, micro-cracks and irreversible oxygen release at high potential still exist universally. Studies have shown that the substitution and doping of heteroions such as Li + , Mg 2+ , Cu 2+ , Al 3+ , Ti 4 + and Co 2+ can effectively alleviate the structural instability, thereby enhancing the cycle performance of metal oxide electrodes at high voltage, but it is difficult to achieve excellent performance comprehensively due to the structural defects of single-phase positive electrodes.

[0004] At present, P2, O3 and P3 type metal oxide positive electrodes synthesized by adjusting the sodium content, solid phase temperature and component characteristics are particularly attractive. Among them, O and P represent Na ions located at octahedral or prism sites, and 2 and 3 represent the number of transition metal layers in the unit cell. Compared with O3 type positive electrodes, P2 type positive electrodes have a wider triangular Na +P2 structure materials are widely used for high rate and relatively stable electrode studies due to their migration channels and lower migration energy barrier. In addition, there are also a few reports on P'2 and O'3 induced by lattice structure distortion. However, the optimization and types of phase structures are relatively rare, and the research on the synthesis technology of P'3 or other space group structure layered positive electrode is also rare. Further, the synthesis of metal oxide positive electrodes of various space groups poses a great challenge to overcome the defects of single phase structure and build a multi-phase heterostructure in order to realize high capacity, high voltage and long life positive electrode. SUMMARY

[0005] To solve the above technical problems existing in the prior art, the present application provides a multi-phase heterostructure type sodium ion battery metal oxide positive electrode material and a preparation method thereof.

[0006] To achieve the above-mentioned purpose, the present application is realized by the following technical scheme:

[0007] In one aspect, the present application provides a preparation method of a multi-phase heterostructure type sodium ion battery metal oxide positive electrode material, which comprises the following steps:

[0008] Step 1: Dissolve a Ni source and a Mn source in deionized water, then add a precipitating agent and ethylene glycol, and obtain a precursor through a hydrothermal reaction;

[0009] Step 2: Mix the precursor with a Co source, a Cu source and a Na source, and obtain the multi-phase heterostructure type sodium ion battery metal oxide positive electrode material through calcination.

[0010] Preferably, the temperature of the hydrothermal reaction is 160℃, and the time is 10-24h.

[0011] Preferably, the precipitating agent is urea, hexamethylenetetramine or ammonium carbonate.

[0012] Preferably, the Ni source, the Mn source, the Co source, the Cu source and the Na source are acetate, nitrate, chloride or sulfate, and the Na source is carbonate, acetate, chloride or hydroxide.

[0013] Preferably, the molar ratio of the Ni source, the Mn source, the Co source, the Cu source and the Na source is 0-0.3:0.2-1:0-0.1:0-0.1:0.3-1.

[0014] Preferably, the calcination adopts programmed temperature rising, first rising to 300-600℃ at a temperature rising rate of 3-5℃ / min at room temperature, and then rising to 600-1000℃ at a temperature rising rate of 3-5℃ / min after heat preservation for 1-5h.

[0015] Another aspect of the present application provides the multiphase heterostructure type sodium ion battery metal oxide positive electrode material prepared by the aforementioned method, wherein the multiphase heterostructure type sodium ion battery metal oxide positive electrode material is composed of at least two crystal phase structures selected from the group consisting of monoclinic phase P'3 (C space group), cubic crystal phase (P123 space group), hexagonal crystal system P2 (P63 / mmc space group) and hexagonal crystal system P3 (R-3m space group).

[0016] Another aspect of the present application also provides the application of the aforementioned multiphase heterostructure type sodium ion battery metal oxide positive electrode material in the field of sodium ion battery materials.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] (1) The multiphase heterostructure type sodium ion battery metal oxide positive electrode material is prepared by the hydrothermal assisted solid phase calcination method, and the calcination process does not produce waste water and harmful gas, and the operation is simple. The synthesis of the positive electrode component has universality in the synthesis scheme, thereby facilitating industrial production.

[0019] (2) The multiphase structure heterostructure constructed in the sodium ion battery metal oxide positive electrode material can alleviate the volume effect caused by phase change during charging and discharging, improve the reaction kinetics of sodium ions, and thus realize excellent rate performance and cycle stability. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The XRD pattern of the positive electrode material prepared in Example 1.

[0021] Figure 2 The scanning electron microscope pattern of Example 1 at high and low magnifications.

[0022] Figure 3 The high-resolution transmission electron microscope pattern and selected area electron diffraction pattern of Example 1.

[0023] Figure 4 The rate performance of Example 1 at different current densities.

[0024] Figure 5 The cycle stability of Example 1 at high current density.

[0025] Figure 6 The XRD pattern of the positive electrode material prepared in Example 2.

[0026] Figure 7 The charge-discharge curve of the positive electrode material prepared in Example 2.

[0027] Figure 8 The XRD pattern of the positive electrode material prepared in Example 3.

[0028] Figure 9 XRD pattern of the positive electrode material prepared in Example 1. DETAILED DESCRIPTION

[0029] For the purpose of promoting an understanding of the principles of the application, a thorough and complete description of the application will be rendered. It is expressly submitted, however, that the application is capable of being practiced further with numerous alternatives to the embodiments described herein. In other words, it is contemplated that the application can be carried out in a variety of ways, all of which are intended to fall within the scope of the present application. Accordingly, it is submitted that the scope of the application should not be limited to the described embodiments.

[0030] Example 1

[0031] Step 1: 6.25 mmol manganese acetate tetrahydrate, 3.75 mmol nickel acetate tetrahydrate were added into 20 ml deionized water, stirred to completely dissolve, then 2.5 g methenamine was dissolved, 50 ml ethylene glycol was added, and continuously stirred for 2 h; the obtained transparent solution was poured into a hydrothermal reactor for hydrothermal reaction, the reaction temperature was 160℃, and the temperature was kept for 24 h, and then cooled to room temperature; the precipitate was washed with deionized water and ethanol for 3 times respectively, and then dried in an oven to obtain a precursor.

[0032] Step 2: 1.25 mmol copper nitrate, 1.25 mmol cobalt nitrate and 7.5 mmol sodium carbonate were added into the precursor, 100 ml deionized water was poured, stirred for 1 h, and then completely evaporated in a water bath at 100℃, and then the obtained material was put into a clean mortar and ground for 30 min to mix the material evenly; the ground material was loaded into a corundum boat, and then calcined in a tube furnace, first heated to 500℃ at a heating rate of 5℃ / min, kept for 5 h, then heated to 850℃ at a heating rate of 5℃ / min, kept for 10 h, and then naturally cooled to room temperature, and then taken out from the tube furnace to obtain a P2 / P'3 heterostructure type metal oxide positive electrode material.

[0033] Figure 1 The XRD pattern of the metal oxide positive electrode material prepared in Example 1 shows that the heterostructure type metal oxide positive electrode material prepared in Example 1 is composed of P2 and P'3 two-phase heterostructure. According to the inductively coupled plasma measurement results in Table 1, it is shown that P2 / P'3-Na 0.71 Ni 0.2 2Mn 0.60 Co 0.10 Cu 0.08 O2.

[0034]

[0035] Table 1: Inductively coupled plasma measurement results of the metal oxide positive electrode material prepared in Example 1

[0036] Figure 2The SEM images show that the P2 / P′3 heterostructure metal oxide cathode material prepared in Example 1 of the present invention is composed of a three-dimensional sphere formed by assembling two-dimensional thick sheets grown in a guided manner.

[0037] Figure 3 High-resolution transmission electron microscopy and selected area electron diffraction also showed that the heterogeneous metal oxide cathode material prepared in Example 1 is composed of a two-phase heterostructure of P2 and P′3.

[0038] Figure 4 The rate performance at different current densities shows that the P2 / P′3 heterostructure metal oxide cathode material prepared in Example 1 exhibits good rate performance at a current density of 20C (3000 mAg). -1 The discharge capacity is 84.08 mAh g. –1 It demonstrates excellent rate performance.

[0039] Figure 5 The charge-discharge curves show that the P2 / P′3 heterostructure metal oxide cathode material prepared in Example 1 has a capacity retention rate of up to 73.8% after 1000 cycles at a current density of 10C, indicating that the preparation method of the present invention can produce long-life metal oxide cathode materials.

[0040] Example 2

[0041] The preparation process of the P2 / P3 heterostructure metal oxide sodium-ion battery cathode material is basically the same as in Example 1, except that the amount of sodium carbonate is replaced with 6.25 mmol.

[0042] Depend on Figure 6 The XRD pattern shows that the heterogeneous metal oxide cathode material prepared in Example 2 of the present invention is composed of a two-phase heterostructure of P2 and P3.

[0043] Figure 7 The charge-discharge curves show that the P2 / P3 heterostructure metal oxide cathode material prepared in Example 2 has a capacity retention rate of up to 64.83% after 100 cycles at a current density of 0.5C, indicating that the preparation method of the present invention can produce metal oxide cathode materials with stable electrochemical performance.

[0044] Example 3

[0045] The preparation process of the P2 / P′3 / cubic heterostructure metal oxide sodium-ion battery cathode material is basically the same as in Example 1, except that the amount of sodium carbonate is replaced with 8.75 mmol.

[0046] Depend on Figure 8 The XRD pattern shows that the heterogeneous metal oxide cathode material prepared in Example 3 of the present invention is composed of a three-phase heterostructure of P2, P′3 and cubic phase.

[0047] Example 4

[0048] The preparation process of the P2 / cubic phase heterostructure type metal oxide sodium ion battery positive electrode material is basically the same as that in Example 1, except that no Co source and Cu source are doped, and 6 mmol of sodium carbonate is replaced by the amount of substance.

[0049] The XRD pattern of Figure 9 The XRD pattern of

[0050] Example 5

[0051] The preparation process of the P2 / P'3 heterostructure type metal oxide sodium ion battery positive electrode material is basically the same as that in Example 1, except that in step 1, 6.25 mmol of manganese acetate tetrahydrate is replaced by 6.25 mmol of manganese nitrate, 3.75 mmol of nickel acetate tetrahydrate is replaced by 3.75 mmol of nickel nitrate, and 2.5 g of hexamethylenetetramine is replaced by 2.5 g of urea; in step 2, 1.25 mmol of copper nitrate is replaced by 1.25 mmol of copper acetate, 1.25 mmol of cobalt nitrate is replaced by 1.25 mmol of cobalt acetate, and 7.5 mmol of sodium carbonate is replaced by 15 mmol of sodium chloride.

[0052] Example 6

[0053] The preparation process of the P2 / P'3 / cubic phase heterostructure type metal oxide sodium ion battery positive electrode material is basically the same as that in Example 1, except that in step 1, 6.25 mmol of manganese acetate tetrahydrate is replaced by 6.25 mmol of manganese nitrate, 3.75 mmol of nickel acetate tetrahydrate is replaced by 3.75 mmol of nickel nitrate, and 2.5 g of hexamethylenetetramine is replaced by 2.5 g of urea; in step 2, 1.25 mmol of copper nitrate is replaced by 1.25 mmol of copper acetate, 1.25 mmol of cobalt nitrate is replaced by 1.25 mmol of cobalt acetate, and 7.5 mmol of sodium carbonate is replaced by 15 mmol of sodium chloride; first, the temperature is increased to 500℃ at a heating rate of 3℃ / min, and then the temperature is increased to 800℃ at a heating rate of 5℃ / min, and the temperature is kept for 10 h.

[0054] Example 7

[0055] The preparation process of the P2 / P'3 heterostructure type metal oxide sodium ion battery positive electrode material is basically the same as that in Embodiment 5, except that in step 1, 6.25 mmol of manganese acetate tetrahydrate is replaced by 6.25 mmol of manganese nitrate, 3.75 mmol of nickel acetate tetrahydrate is replaced by 3.75 mmol of nickel nitrate, and 2.5 g of hexamethylenetetramine is replaced by 2.5 g of urea; in step 2, 7.5 mmol of sodium carbonate is replaced by 15 mmol of sodium chloride.

[0056] Embodiment 8

[0057] The preparation process of the P2 / P'3 / cubic heterostructure type metal oxide sodium ion battery positive electrode material is basically the same as that in Embodiment 1, except that in step 1, 6.25 mmol of manganese acetate tetrahydrate is replaced by 6.25 mmol of manganese nitrate, 3.75 mmol of nickel acetate tetrahydrate is replaced by 3.75 mmol of nickel nitrate, and 2.5 g of hexamethylenetetramine is replaced by 2.5 g of urea; in step 2, 7.5 mmol of sodium carbonate is replaced by 18.75 mmol of sodium chloride; first, the temperature is raised to 500°C at a temperature rise rate of 3°C / min, and then the temperature is kept for 5 h, and then the temperature is raised to 900°C at a temperature rise rate of 5°C / min, and then the temperature is kept for 10 h.

[0058] Any combination of the technical features of the above-described embodiments can be made, and in order to make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the description.

[0059] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of variations and improvements can be made, which are within the scope of protection of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.

Claims

1. A method for preparing a multiphase heterostructure type sodium-ion battery metal oxide cathode material, characterized in that, The method comprises the following steps: Step 1: dissolving a Ni source, a Mn source, a Co source, a Cu source and a Na source in deionized water, adding a precipitant and ethylene glycol, and obtaining a precursor through a hydrothermal reaction; Step 2: mixing the precursor with a Co source, a Cu source and a Na source, and obtaining the multiphase heterostructure type sodium ion battery metal oxide positive electrode material through calcination; The molar ratio of the Ni source, the Mn source, the Co source, the Cu source and the Na source is 0-0.3:0.2-1:0-0.1:0-0.1:0.3-1. The calcination adopts programmed temperature rising, first rising to 300-600 DEG C at a temperature rising rate of 3-5 DEG C / min at room temperature, and then rising to 600-1000 DEG C at a temperature rising rate of 3-5 DEG C / min, and the temperature is kept for 8-16 h.

2. The method of claim 1, wherein the metal oxide cathode material is a sodium ion battery metal oxide cathode material having a multiphase heterostructure. The temperature of the hydrothermal reaction is 160 DEG C, and the time is 10-24 h.

3. The method of claim 1, wherein the metal oxide cathode material is a multiphase heterostructure type sodium-ion battery metal oxide cathode material. The precipitant is urea, hexamethylenetetramine or ammonium carbonate.

4. The method of claim 1, wherein the metal oxide cathode material is a multiphase heterostructure type sodium-ion battery metal oxide cathode material. The Ni source, the Mn source, the Co source and the Cu source are acetate, nitrate, chloride or sulfate, and the Na source is carbonate, acetate, chloride or hydroxide.

5. The multiphase heterostructured sodium-ion battery metal oxide cathode material prepared by the method of any one of claims 1-4, characterized in that, The multiphase heterostructure type sodium ion battery metal oxide positive electrode material is composed of at least two crystal phase structures of monoclinic P'3, cubic crystal phase, hexagonal P2 and hexagonal P3.

6. Application of the multiphase heterostructure type sodium ion battery metal oxide positive electrode material in the field of sodium ion battery materials.

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