Preparation method and application of composite material of carbon material and layered oxide

Abstract

The invention discloses a preparation method and application of a composite material of a carbon material and a layered oxide. Wherein the carbon coating improves the conductivity of the electrode material and inhibits the occurrence of side reactions and the ginger-Taylor effect. The preparation method comprises the following steps: dissolving a polyphenol compound, fully mixing the dissolved polyphenol compound with the prepared Na (NiFeMn) 1 / 3O2 material, drying the mixture, and carrying out high-temperature carbonization to obtain the carbon-coated Na (NiFeMn) 1 / 3O2 material. According to the present invention, the initial specific capacity of the sodium ion battery assembled based on the synthesized carbon-coated Na (NiFeMn) 1 / 3O2 material as the positive electrode material is 108.6 mAh g <-1 > at the rate of 1 C, the capacity after 300 charge-discharge cycles is more than 80 mAh g <-1 >, the coulombic efficiency except the first cycle is maintained at 98% or more, the good cycle performance is provided, and the sodium ion battery can effectively work in the 70 DEG C environment.

Description

Technical Field

[0001] The invention relates to the preparation of sodium ion battery electrode materials, and in particular to a preparation method of a composite electrode material of carbon materials and layered oxides and its application field. Background Art

[0002] As people pursue sustainable development, electrochemical energy storage has been widely studied as a very important part of it and has an extremely important position. Lithium-ion batteries have become the most widely used secondary batteries in the world today due to their advantages such as high energy density and long cycle life. However, with the large-scale development of new energy, the demand for lithium resources is higher, but the reserves of lithium resources are low and unevenly distributed, and there is a risk of price fluctuations. In recent years, sodium-ion batteries (SIBs) have become one of the most promising supplementary options, and they have a high degree of similarity with lithium-ion batteries in terms of electrochemical principles, production processes and production equipment. In addition, sodium-ion batteries have the advantages of abundant sodium sources and low costs, and they have great development prospects in the energy storage market in the future.

[0003] Since the working voltage of sodium ion batteries is low and the radius of sodium ions is Compared with lithium ion The larger the size, the greater the difficulty in embedding and de-embedding. In order to be more competitive, sodium-ion batteries need to achieve high capacity and long cycle durability. As a very important part of sodium-ion batteries, positive electrode materials affect the capacity and long cycle durability of batteries. Layered oxides have higher theoretical capacity, high redox potential, and a two-dimensional layered structure that facilitates the diffusion of sodium ions. They have unique development advantages, among which O3 and P2 structures are the main ones. Na(NiFeMn) without Co 1 / 3 O 2 Due to its high capacity, low cost and environmental friendliness, it has become one of the most promising cathode material options, but it still has many problems, including poor structural stability, poor air stability, and poor rate performance.

[0004] In order to solve the above problems, a lot of work has been put into the research on the modification of positive electrode materials. For poor air stability and poor structural stability, many works combine layered oxides with surface coatings (such as oxides, phosphates, etc.), which can not only inhibit structural changes during charging and discharging, but also improve air stability. For example, using Al 2 O 3 、MgO、ZrO 2 The surface is modified by coatings such as conductive carbon and carbon nanotubes, but the conductivity of these inorganic materials is relatively low, and it is difficult to continuously and completely cover the surface of the particles with conductive carbon coatings. So far, conductive carbon coatings are an effective strategy for improving electrode materials, but there are relatively few studies combining conductive carbon coatings with layered oxides. Summary of the invention

[0005] Layered oxides, as a widely studied positive electrode material for sodium-ion batteries, have attracted widespread attention due to their unique two-dimensional interlayer structure, high theoretical capacity and good rate performance. However, their poor interfacial chemical stability and limited cycle life limit their practical applications. Carbon coating technology, as an effective surface modification method, can improve the electronic conductivity of the material by constructing a conductive network, while forming a physical barrier to inhibit the side reactions between the electrolyte and the material surface, thereby improving the cyclic stability of the material. The present invention aims to maximize performance through a reasonable coating process, and adopts a co-precipitation method, which is suitable for mass production, to prepare Na(NiFeMn) 1 / 3 O 2 The carbon-coated Na(NiFeMn) for sodium ion batteries developed by the present invention is a material that is surface-modified by a low-cost organic carbon source, and the carbon-coated composite material is used as a positive electrode material for sodium ion batteries for electrochemical performance testing. 1 / 3 O 2 The material does not require complex equipment, is low in cost, and is conducive to industrialization. The main purpose of the present invention is to provide a preparation method and application of a composite material of carbon material and layered oxide, effectively control the coating structure through a suitable coating process, and improve the stability of the material structure.

[0006] The present invention realizes carbon-coated Na(NiFeMn) by controlling the organic carbon source addition content and mixing temperature. 1 / 3 O 2 The successful preparation of the material, due to the modification of the appropriate amount of carbon coating, makes the composite material have excellent electrochemical performance of sodium ion batteries, with high specific capacity and good cycle stability.

[0007] Carbon-coated Na(NiFeMn) prepared by the present invention 1 / 3 O 2 The material is used as a positive electrode material for sodium-ion batteries. In an electrochemical test at a test rate of 1C, the discharge capacity of the first charge and discharge cycle is 108.6 mAh g -1 After 300 cycles, the discharge capacity is still more than 80 mAh g -1 , and can still achieve 102.8mAh g at 1C test rate under 70℃ environment -1 The discharge capacity is high and the cycle stability is good.

[0008] The present invention also provides the carbon-coated Na(NiFeMn) for sodium ion battery electrode material. 1 / 3 O 2 The preparation method comprises the following steps:

[0009] 1) Weigh a certain amount of NiSO according to the molar ratio 4 6H 2 O, FeSO 4 7H 2 O and MnSO 4 ·H 2 O;

[0010] 2) Put the three raw materials into a beaker, add a certain amount of deionized water to fully dissolve them, and add a certain amount of NaOH solution and NH 4 OH solution;

[0011] 3) Heat the beaker in a water bath and stir thoroughly, wash the precipitate and dry it;

[0012] 4) The precipitate and a certain molar ratio of Na 2 CO 3 After mixing, sintering is performed to obtain Na(NiFeMn) 1 / 3 O 2 ;

[0013] 5) Weigh a certain amount of polyphenol compounds according to the mass ratio, add a certain amount of anhydrous ethanol and dissolve them in a beaker;

[0014] 6) Add a certain amount of Na(NiFeMn) 1 / 3 O 2 Add to beaker and heat with stirring;

[0015] 7) The mixture is dried and then carbonized to obtain carbon-coated Na(NiFeMn) 1 / 3 O 2 Material.

[0016] Furthermore, in step 1), NiSO 4 6H 2 O, FeSO 4 7H 2 O and MnSO 4 ·H 2 The molar ratio of O is 1:0.8-1.2:0.8-1.2, most preferably 1:1:1;

[0017] Furthermore, in step 2), 30% of deionized water, NaOH solution and NH 4 The amount of OH solution added is sufficient to maintain the solution pH at 10.5-11.5, most preferably 11.

[0018] Furthermore, in the step 3), the water bath heating temperature is 50-60°C, the stirring time is 10-14h, and most preferably, the water bath heating temperature is 55°C, the stirring time is 12h, and the washed precipitate is centrifuged with anhydrous ethanol, and the washed precipitate is dried in an oven at 55-65°C for 10-14h, and most preferably, dried in an oven at 60°C for 12h.

[0019] Further, in step 4), Na 2 CO 3 with NiSO 4 6H 2 The molar ratio of O is 3.15:2, the sintering temperature is 800-1000°C, the sintering time is 8-15h, and the heating rate is 1-10°C / min.

[0020] Further, the mass of the polyphenolic compound in step 5) is the mass of the Na(NiFeMn) added in step 6). 1 / 3 O 2 The filling amount of anhydrous ethanol is 1-10% of the mass.

[0021] Furthermore, in step 6), Na(NiFeMn) 1 / 3 O 2 The mass is 2 g, the heating and stirring temperature is 75-85° C., the heating and stirring time is 20-40 min, and most preferably, the heating temperature is 80° C. and the stirring time is 30 min.

[0022] Furthermore, in step 7), the carbonization treatment is carried out in an Ar atmosphere at a carbonization temperature of 500 to 1500° C., a carbonization time of 1 to 3 hours, and a heating rate of 1 to 10° C. / min.

[0023] Furthermore, the carbon-coated Na(NiFeMn) synthesized by the present invention 1 / 3 O 2 The material is used in sodium ion batteries. Appropriate carbon coating can effectively improve the structural stability and air stability, improve the electronic conductivity of the sodium ion battery system, and thus improve the performance and cycle life of the sodium ion battery. Carbon coated Na(NiFeMn) 1 / 3 O 2 The preparation of materials can effectively improve the cycle stability and high temperature performance.

[0024] The beneficial results of the present invention are:

[0025] 1) The present invention aims to successfully prepare carbon-coated Na(NiFeMn) by a reasonable coating process design and a simple and low-cost experimental method. 1 / 3 O 2The material is used as a positive electrode material for sodium ion batteries. The present invention realizes carbon-coated Na(NiFeMn) by controlling the addition content of organic carbon source and the mixing temperature. 1 / 3 O 2 The successful preparation of the material and the appropriate amount of carbon coating can improve the structural stability, giving it excellent electrochemical performance in sodium ion batteries, showing high specific capacity and good cycle stability.

[0026] 2) Carbon-coated Na(NiFeMn) prepared by the present invention 1 / 3 O 2 The material was used as a cathode material in sodium ion batteries and showed excellent electrochemical performance in electrochemical tests. In the electrochemical test with a test rate of 1C, the discharge capacity of the first charge and discharge cycle was 108.6 mAh g -1 After 300 cycles, the discharge capacity is still more than 80 mAh g -1 , and can still achieve 102.8mAh g at 1C test rate under 70℃ environment -1 The discharge capacity is high and the cycle stability is good.

[0027] 3) The experimental operation of the present invention is simple, does not require any complex equipment, has low cost, and can achieve carbon-coated Na(NiFeMn) 1 / 3 O 2 The material was prepared and applied as a cathode material in sodium ion batteries for electrochemical testing, showing excellent electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Carbon-coated Na(NiFeMn) prepared in Example 1 1 / 3 O 2 Scanning electron microscope (SEM) image of the material.

[0029] Figure 2 Carbon-coated Na(NiFeMn) prepared in Example 1 1 / 3 O 2 XRD phase diagram of the material.

[0030] Figure 3 Carbon-coated Na(NiFeMn) prepared in Example 1 1 / 3 O 2 Element distribution map of the material.

[0031] Figure 4 Carbon-coated Na(NiFeMn) prepared in Example 1 1 / 3 O 2 The discharge specific capacity diagram of the sodium-ion battery assembled with the material after 300 charge and discharge cycles at a 1C rate.

[0032] Figure 5 Carbon-coated Na(NiFeMn) prepared in Example 1 1 / 3 O 2 The discharge specific capacity and coulombic efficiency of the sodium-ion battery assembled with the material after 300 charge and discharge cycles at 70°C and 1C rate. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with specific embodiments.

[0034] Example 1

[0035] According to the molar ratio (Ni:Fe:Mn=1:1:1), weigh a certain amount of NiSO 4 6H 2 O, FeSO 4 7H 2 O and MnSO 4 ·H 2 O, put the three raw materials into a 50ml beaker, add a certain amount of deionized water to ensure that the filling volume is 30%. Add a certain amount of NaOH solution and NH 4 OH solution, keeping the solution pH at 11, heating the beaker at 55°C in a water bath and stirring for 12 hours, washing the precipitate with anhydrous ethanol by centrifugation and drying it in an oven at 60°C for 12 hours. 2 CO 3 :NiSO 4 6H 2 O=3.15:2), weigh a certain amount of Na 2 CO 3 , after being fully mixed with the precipitate, the sintering temperature is 800℃, the sintering time is 8h, and the heating rate is 2℃ / min. According to the mass ratio, 2% (0.04g) of polyphenol compounds are weighed into a beaker, and 30% of the filling amount of anhydrous ethanol is added to dissolve; 2g Na(NiFeMn) 1 / 3 O 2 Add to a beaker and heat and stir at 80°C for 30 min; dry the mixture and then carbonize it in an Ar atmosphere at a carbonization temperature of 500°C for 1 h at a heating rate of 2°C / min to obtain carbon-coated Na(NiFeMn) 1 / 3 O 2 Material.

[0036] Example 2

[0037] According to the molar ratio (Ni:Fe:Mn=1:1:1), weigh a certain amount of NiSO 4 6H 2 O, FeSO 4 7H 2O and MnSO 4 ·H 2 O, put the three raw materials into a 50ml beaker, add a certain amount of deionized water to ensure that the filling volume is 30%. Add a certain amount of NaOH solution and NH 4 OH solution, keeping the solution pH at 11, heating the beaker at 55°C in a water bath and stirring for 12 hours, washing the precipitate with anhydrous ethanol by centrifugation and drying it in an oven at 60°C for 12 hours. 2 CO 3 :NiSO 4 6H 2 O=3.15:2), weigh a certain amount of Na 2 CO 3 , after being fully mixed with the precipitate, the sintering temperature is 900℃, the sintering time is 8h, and the heating rate is 5℃ / min. Weigh 5% of the polyphenol compound according to the mass ratio in a beaker, add 30% of the filling amount of anhydrous ethanol to dissolve; 2g Na(NiFeMn) 1 / 3 O 2 Add to a beaker and heat and stir at 80°C for 30 min; dry the mixture and then carbonize it in an Ar atmosphere at a carbonization temperature of 700°C for 2 h at a heating rate of 5°C / min to obtain carbon-coated Na(NiFeMn) 1 / 3 O 2 Material.

[0038] Example 3

[0039] According to the molar ratio (Ni:Fe:Mn=1:1:1), weigh a certain amount of NiSO 4 6H 2 O, FeSO 4 7H 2 O and MnSO 4 ·H 2 O, put the three raw materials into a 50ml beaker, add a certain amount of deionized water to ensure that the filling volume is 30%. Add a certain amount of NaOH solution and NH 4 OH solution, keeping the solution pH at 11, heating the beaker at 55°C in a water bath and stirring for 12 hours, washing the precipitate with anhydrous ethanol by centrifugation and drying it in an oven at 60°C for 12 hours. 2 CO 3 :NiSO 4 6H 2 O=3.15:2), weigh a certain amount of Na 2 CO 3, after being fully mixed with the precipitate, the sintering temperature is 1000℃, the sintering time is 8h, and the heating rate is 10℃ / min. According to the mass ratio, 10% of the polyphenol compound is weighed into a beaker, and 30% of the filling amount of anhydrous ethanol is added to dissolve; 2g Na(NiFeMn) 1 / 3 O 2 Add to a beaker and heat and stir at 80°C for 30 min; dry the mixture and then carbonize it in an Ar atmosphere at a carbonization temperature of 900°C for 3 h at a heating rate of 10°C / min to obtain carbon-coated Na(NiFeMn) 1 / 3 O 2 Material.

[0040] The chemical raw material NiSO used in the above examples 4 6H 2 O, FeSO 4 7H 2 O、MnSO 4 ·H 2 O and Na 2 CO 3 All were analytically pure.

[0041] Performance Testing:

[0042] 1) SEM test: The carbon-coated Na(NiFeMn) 1 / 3 O 2 The materials were observed under a scanning electron microscope. Figure 1 As shown, from Figure 1 It can be clearly seen that carbon-coated Na(NiFeMn) 1 / 3 O 2 It is a three-dimensional spherical particle with a particle size of about 4μm, and the particle is composed of a nano-sheet structure with a thickness of tens of nanometers.

[0043] 2) XRD test: The carbon-coated Na(NiFeMn) prepared in Example 1 1 / 3 O 2 The material was subjected to XRD test, such as Figure 2 As shown. XRD diffraction peaks and standard spectrum peaks hexagonal O3 type NaNi 0.5 Mn 0.5 O 2 The positions of 16.577°, 33.566°, 35.544°, 36.894°, 41.914°, 45.373°, 53.753°, 58.552°, 62.93°, 65.586°, 69.223°, 70.59°, 73.256°, 74.421°, 75.221° and 78.515° are consistent, indicating that the sintering process is consistent with the original process.

[0044] During the long process, Na(NiFeMn) with R3m space group was successfully prepared. 1 / 3 O 2 Materials, at the same time, the coating of an appropriate amount of organic carbon source does not affect the crystal structure of the layered oxide.

[0045] 3) EDS test: Carbon-coated Na(NiFeMn) obtained in Example 1 1 / 3 O 2 Energy spectrum analysis of materials, such as Figure 3 As shown, the O, Na elements and Ni, Fe, Mn, and C elements in the material are evenly distributed, indicating that the C element is evenly distributed in the material and the thickness of the coating is uniform.

[0046] 4) Electrochemical test: The carbon-coated Na(NiFeMn) prepared in Example 1 was 1 / 3 O 2 After the material is made into electrodes, it is assembled into sodium ion button batteries for constant current charge and discharge tests.

[0047] As attached Figure 4 Carbon-coated Na(NiFeMn) prepared in Example 1 1 / 3 O 2 The discharge capacity of the material after 300 charge and discharge cycles at 1C rate. The discharge capacity of the first cycle is 108.6 mAh g -1 After 300 cycles, the discharge capacity is still more than 80 mAh g -1 The capacity decay per cycle is 0.088%, and the coulombic efficiency remains above 98%, which shows that the carbon-coated Na(NiFeMn) 1 / 3 O 2 The sodium-ion batteries assembled with these materials have excellent cycle performance.

[0048] Figure 5 Carbon-coated Na(NiFeMn) prepared in Example 1 1 / 3 O 2 The discharge capacity and coulomb efficiency of the sodium ion battery assembled with the material after 300 cycles of charge and discharge at 70°C and 1C rate. Its initial discharge capacity is 102.8 mAh g -1 The battery can work for more than 300 cycles in a high temperature environment of 70°C and has good cycle stability.

Claims

1. A method for preparing a composite material of a carbon material and a layered oxide, characterized in that: The steps include: 1) Weigh NiSO4·6H2O, FeSO4·7H2O and MnSO4·H2O according to the molar ratio; 2) Put the three raw materials into a container, add deionized water to fully dissolve them, and then add NaOH solution and NH4OH solution; 3) heating the container in a water bath and stirring sufficiently, washing the precipitate and drying it to obtain a precipitate; 4) Mix the precipitate with Na2CO3 and sinter to obtain Na(NiFeMn) 1 / 3 O2; 5) Weighing polyphenol compounds according to the mass ratio, adding anhydrous ethanol and dissolving them in a reactor; 6) Na(NiFeMn) 1 / 3 O2 is added into the reactor and heated and stirred to obtain a mixture; 7) drying the mixture and then carbonizing it to obtain a composite material of carbon material and layered oxide, i.e., carbon-coated Na(NiFeMn) 1 / 3 O2 material.

2. The preparation method according to claim 1, characterized in that: In step 1), the molar ratio of NiSO4·6H2O, FeSO4·7H2O and MnSO4·H2O is 1:0.8~1.2:0.8~1.

2.

3. The preparation method according to claim 1, characterized in that: In step 2), the pH value after the addition of NaOH solution and NH4OH solution is 10.5-11.

5.

4. The preparation method according to claim 1, characterized in that: In step 3), the water bath heating temperature is 50-60° C., and the stirring time is 10-14 h.

5. The preparation method according to claim 1, characterized in that: In step 3), the drying conditions are: drying in an oven at 55 to 65° C. for 10 to 14 hours.

6. The preparation method according to claim 1, characterized in that: In step 4), the sintering temperature is 800-1000° C. and the sintering time is 8-15 hours.

7. The preparation method according to claim 1, characterized in that: The mass of the polyphenolic compound in step 5) is the Na(NiFeMn) added in step 6). 1 / 3 1-10% of the mass of O2.

8. The preparation method according to claim 1, characterized in that: In step 6), the temperature of heating and stirring is 75 to 85° C., and the time of heating and stirring is 20 to 40 minutes.

9. The preparation method according to claim 1, characterized in that: In step 7), the carbonization treatment is carried out in an Ar atmosphere at a carbonization temperature of 500 to 1500° C. and a carbonization time of 1 to 3 hours.

10. Use of the composite material of carbon material and layered oxide prepared by the preparation method according to any one of claims 1 to 9 as a positive electrode material for sodium ion batteries.

Images