Preparation method of NiCoMn microsphere energy storage material containing amorphous-nanocrystalline double-phase structure

Abstract

The invention discloses a preparation method of a NiCoMn microsphere energy storage material containing an amorphous-nanocrystalline double-phase structure. The NiCoMn microspheres are grown on the foamed nickel by adopting a solvothermal method. Through Mn doping modulation, a mixed crystal NiCoMn structure containing amorphous and quantum size nanocrystals is prepared. The preparation method comprises the following specific preparation processes: mixing Ni (NO3) 2.6 H2O, Co (NO3) 2.6 H2O, MnCl2. 4H2O, isopropanol, glycerol and foamed nickel, stirring for 1 hour, adding into a polytetrafluoroethylene lining, and carrying out hydrothermal reaction; and taking out the foamed nickel sheet, cleaning the foamed nickel sheet with water and ethanol, and drying the foamed nickel sheet at 60 DEG C for 12 hours to obtain the NiCoMn anode material. The maximum specific capacity of the NiCoMn anode material is as high as 5750 F g < 1 > at 1 A g < 1 > and is still as high as 5300 F g < 1 > at 10 A g < 1 >, which is far higher than 1367 F g < 1 > (1 A g < 1 >) and 1133 F g < 1 > (10 A g < 1 >) of NiCo, and both the 1367 F g < 1 > (1 A g < 1 >) and the 1133 F g < 1 > (10 A g < 1 >) exceed four times. And after 5000 cycles under a large charging current of 10A g < 1 >, a retention rate of 83.5% can be obtained, and excellent sustainability is shown. The device can be applied to power supply charging occasions requiring high stability, high magnification and high energy density.

Description

Technical Field

[0001] The invention belongs to the technical field of nano material preparation, and specifically relates to a preparation method of a NiCoMn microsphere energy storage material containing an amorphous-nanocrystalline dual-phase structure and an application of the material in electrochemical energy storage. Technical Background

[0002] New energy materials are constantly emerging in my country. Supercapacitors (SCs) have attracted much attention due to their excellent power density and diverse energy storage devices, especially in the fields of emergency power supplies and new energy vehicles. However, their low energy density and sustainability are the main problems currently faced. In order to further improve the energy density of SCs, one of the key factors is the interfacial electrochemical reaction between the electrode and the electrolyte, including adsorption / desorption, surface redox reaction, and ion diffusion. This depends largely on the inherent properties of the electrode material. The recently developed NiCo-based layered compounds can obtain special hydroxyl redox anode materials through multi-component design and adjustable embedding reactions, showing excellent supercapacitor performance. Due to the multivalent characteristics of the Mn element, it is considered to be one of the most valuable elements in SC.

[0003] The purpose of the present invention is to prepare a NiCoMn microsphere containing an amorphous-nanocrystalline dual-phase structure as an anode electrode, and use the amorphous-nanocrystalline dual-phase structure to improve the problem of decreased cycle stability caused by volume expansion during the electrochemical cycle of the material. Mn element doping is used to obtain the dual-phase structure, and its multivalent state characteristics are used to improve the electrochemical reaction activity to further improve the specific capacitance, thereby obtaining a high energy density. Due to its spherical structure, fast charging and discharging characteristics are achieved under high current density charging. It has the characteristics of fast charging and discharging, good stability and high energy density. Summary of the invention

[0004] The present invention provides a one-step synthesis method of NiCoMn LDH microspheres containing an amorphous-nanocrystalline dual-phase structure, which enables the microspheres to obtain high energy density, fast charge and discharge characteristics and good durability to meet the needs of future microelectronics for fast energy storage.

[0005] The objective of the present invention is achieved through the following technical solutions: A method for preparing NiCoMn microspheres containing an amorphous-nanocrystalline dual-phase structure, comprising the following steps: Weigh the chemicals nickel acetate hexahydrate, cobalt acetate hexahydrate, and manganese chloride tetrahydrate according to a certain Ni:Co:Mn atomic ratio.

[0006] Add (1) to the mixed solution of isopropanol and glycerol, put in nickel foam, and stir for 1 h.

[0007] The solution in step (2) is transferred to a high pressure reactor and reacted at 150-200 degrees for 2-10 hours.

[0008] (4) The nickel foam sheet in step (3) was taken out, washed with water and ethanol, and dried at 60 °C for 12 hours.

[0009] The beneficial effects of the present invention are as follows: the present invention obtains a NiCoMn microsphere anode electrode material containing an amorphous-nanocrystalline dual-phase structure through a simple one-step hydrothermal method. The material can be applied to the field of electrochemical energy storage. In terms of morphology, NiCoMn microspheres are grown on nickel foam after hydrothermal action. This structure, on the one hand, can increase the effective contact between the electrolyte and the active material, improve its electrochemical active specific surface area, and promote the electrochemical reaction rate to achieve fast charge and discharge characteristics; on the other hand, the doping of the Mn element not only increases the electrochemical reaction active groups and greatly improves the specific capacitance, but also obtains an amorphous-nanocrystalline dual-phase structure, slows down the volume expansion of the electrochemical reaction, and improves the durability of the electrode material. In terms of the synthesis process, the one-step hydrothermal method is adopted, which has low energy consumption and high efficiency, thus being conducive to industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Attached Figure 1 XRD spectra of Ni1Co1Mn0 and Ni1Co1Mn2 samples in Example 1.

[0011] Attached Figure 2 SEM image of the Ni1Co1Mn0 sample in Example 1.

[0012] Attached Figure 3 SEM magnified image of the Ni1Co1Mn0 sample in Example 1.

[0013] Attached Figure 4 SEM image of the Ni1Co1Mn2 sample in Example 1.

[0014] Attached Figure 5 SEM magnified image of the Ni1Co1Mn2 sample in Example 1.

[0015] Attached Figure 6 Charge and discharge curves of Ni1Co1Mn0 and Ni1Co1Mn2 samples in Example 1.

[0016] Attached Figure 7 In Example 2, Ni1Co1Mn 1.5 SEM image of the sample.

[0017] Attached Figure 8 In Example 2, Ni1Co1Mn 1.5 SEM magnified image of the sample.

[0018] Attached Fig. 9 In Example 2, Ni1Co1Mn 1.5 TEM image of the sample.

[0019] Attached Fig.10 In Example 2, Ni1Co1Mn0 and Ni1Co1Mn 1.5 Charge and discharge curves of the samples.

[0020] Attached Fig.11 In Example 2, Ni1Co1Mn 1.5 Cycling stability of samples.

[0021] Attached Fig.12 In Example 2, Ni1Co1Mn 1.5 Charge and discharge curves of the samples at different charging current densities.

[0022] Attached Fig.13 In Example 2, Ni1Co1Mn 1.5 Cycling stability of asymmetric capacitors assembled with sample as positive electrode and activated carbon AC as negative electrode.

[0023] Attached Fig.14 In Example 3, Ni1Co1Mn0 and Ni1Co1Mn 0.5 Charge and discharge curves of the samples. DETAILED DESCRIPTION

[0024] The present invention is further described below through specific embodiments in conjunction with the accompanying drawings. The following description is only for explaining the advantages and technical solutions of the present invention, and does not limit the present invention. Embodiment 1

[0025] (1) Weigh nickel acetate hexahydrate, cobalt acetate hexahydrate, and manganese chloride tetrahydrate in an atomic ratio of Ni:Co:Mn of 1:1:2.

[0026] (2) Add (1) to a mixed solution of isopropanol and glycerol in a volume ratio of 1:3, add nickel foam, and stir for 1 h.

[0027] (3) The solution from step (2) was transferred to a high pressure reactor and reacted at 180°C for 7 h.

[0028] (4) The nickel foam sheet in step (3) was taken out, washed with water and ethanol, and dried at 60 °C for 12 hours.

[0029] The Mn-doped sample (denoted as Ni1Co1Mn2) was prepared by XRD analysis. Figure 1Compared with the sample without Mn addition (Ni1Co1Mn0), the Ni1Co1Mn2 sample has a new (110) diffraction peak due to the addition of Mn. Comparing the scanning electron microscope (SEM) images of Ni1Co1Mn0 and Ni1Co1Mn2 samples, it can be seen that Ni1Co1Mn0 (with Figure 2 and 3 ) shows that micron-sized spheres with a size of 830 nm have grown on the surface of nickel foam, while the Ni1Co1Mn2 sample (attached Figure 4 and 5 ) surface also grew micron-sized spheres with wrinkles on the surface and a size of 2420 nm. In 2 M KOH electrolyte solution, 10 A g -1 The charge and discharge curves are shown in the attached figure. Figure 6 The calculated specific capacitance of Ni1Co1Mn2 is 3420 F g −1 The corresponding specific capacitance of Ni1Co1Mn0 sample is 1133 F g −1 . Embodiment 2

[0030] (1) Weigh nickel acetate hexahydrate, cobalt acetate hexahydrate, and manganese chloride tetrahydrate in an atomic ratio of Ni:Co:Mn of 1:1:1.5.

[0031] (2) Add (1) to a mixed solution of isopropanol and glycerol in a volume ratio of 1:1, add nickel foam, and stir for 1 h.

[0032] (3) The solution from step (2) was transferred to a high pressure reactor and reacted at 180°C for 7 h.

[0033] (4) The nickel foam sheet in step (3) was taken out, washed with water and ethanol, and dried at 60 °C for 12 hours.

[0034] Ni1Co1Mn 1.5 The SEM of the sample shows Figure 7 and attached Figure 8 ) Micron-sized spheres with a size of 3160 nm and microcracks on the surface of nickel foam have grown on the surface. Its TEM structure is shown in the attached Fig. 9 , nanocrystals are embedded in the amorphous matrix, with a size of 2-7nm, which is at the quantum dot level. In 2 M KOH electrolyte solution, 10 A g -1 The charge and discharge curves are shown in the attached figure. Fig.10 The calculated specific capacitance is 5300 F g −1 Under this condition, after 5000 charge and discharge cycles, 83.5% of the capacitance is still maintained (see Appendix Fig.11 ). In particular, Ni1Co1Mn1.5 Sample at 30 A g -1 At a high charge current density of 3796 F g −1 , see attached Fig.12 , indicating that it has fast charge and discharge characteristics. 1.5 The sample was used as the positive electrode and commercial activated carbon (AC) was used as the negative electrode to assemble an asymmetric capacitor with a capacity of 10 A g -1 At the current density of 1.5 2.0 MW, the specific capacitance increased from 193 F g to 2.5 2.0 MW after 8000 charge and discharge cycles. −1 Reduced to 153 F g −1 , specific capacitance retention rate 79%, see attached Fig.13 . Embodiment 3

[0035] (1) Weigh nickel acetate hexahydrate, cobalt acetate hexahydrate, and manganese chloride tetrahydrate in an atomic ratio of Ni:Co:Mn of 1:1:0.5.

[0036] (2) Add (1) to a mixed solution of isopropanol and glycerol in a volume ratio of 1:2, add nickel foam, and stir for 1 h.

[0037] (3) The solution from step (2) was transferred to a high pressure reactor and reacted at 200°C for 7 h.

[0038] (4) The nickel foam sheet in step (3) was taken out, washed with water and ethanol, and dried at 60 °C for 12 hours.

[0039] Ni1Co1Mn 0.5 The sample grew spherical particles with a size of 990 nm. In 2 M KOH electrolyte solution, 10 Ag -1 The charge and discharge curves are shown in the attached figure. Fig.13 Calculated Ni1Co1Mn 0.5 Specific capacitance is 2200 F g −1 . Embodiment 4

[0040] (1) Weigh nickel acetate hexahydrate, cobalt acetate hexahydrate, and manganese chloride tetrahydrate in a Ni:Co atomic ratio of 1:2:0.5.

[0041] (2) Add (1) to isopropanol solution, add nickel foam, and stir for 1 h.

[0042] (3) The solution from step (2) was transferred to a high pressure reactor and reacted at 150°C for 10 h.

[0043] (4) The nickel foam sheet in step (3) was taken out, washed with water and ethanol, and dried at 60 °C for 12 hours.

[0044] Ni1Co2Mn synthesized under this process 0.5 The sample grew spherical particles with a size of 1000 nm. In 2 M KOH electrolyte solution, 10 A g -1 At the current density, the specific capacitance is 2220 F g −1 . Embodiment 5

[0045] (1) Weigh nickel acetate hexahydrate, cobalt acetate hexahydrate, and manganese chloride tetrahydrate in an atomic ratio of Ni:Co:Mn of 1:2:2.

[0046] (2) Add (1) to the glycerol mixed solution, add nickel foam, and stir for 1 h.

[0047] (3) The solution from step (2) was transferred to a high pressure reactor and reacted at 200°C for 2 h.

[0048] (4) The nickel foam sheet in step (3) was taken out, washed with water and ethanol, and dried at 60 °C for 12 hours.

[0049] The spherical particles of Ni1Co2Mn2 synthesized by this process have a size of 3920 nm. -1 At the current density, the specific capacitance is 3910 F g −1 . Embodiment 6

[0050] (1) Weigh nickel acetate hexahydrate, cobalt acetate hexahydrate, and manganese chloride tetrahydrate in an atomic ratio of Ni:Co:Mn of 1:1.5:1.5.

[0051] (2) Add (1) to a mixed solution of isopropanol and glycerol in a volume ratio of 1:1, add nickel foam, and stir for 1 h.

[0052] (3) The solution from step (2) was transferred to a high pressure reactor and reacted at 200°C for 5 h.

[0053] (4) The nickel foam sheet in step (3) was taken out, washed with water and ethanol, and dried at 60 °C for 12 hours.

[0054] Ni1Co synthesized by this process 1.5 Mn 1.5 The size of the spherical particles grown by the sample is 2770 nm. In 2 M KOH electrolyte solution, 10 A g -1 At the current density, the specific capacitance is 5010 F g −1 At 10 A g -1At the current density, after 5000 charge and discharge cycles, 80.1% of the capacitance is still maintained.

[0055] The above content is only a basic description of the concept of the present invention, and any equivalent changes made according to the technical solution of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for preparing a NiCoMn microsphere energy storage material containing an amorphous-nanocrystalline dual-phase structure, characterized in that: The following steps are involved: (1) Mix Ni(NO3)2·6H2O, Co(NO3)2·6H2O, MnCl2·4H2O, isopropanol, glycerol and nickel foam, stir for 1 h, and add to the polytetrafluoroethylene liner; (2) subjecting the mixed solution to a hydrothermal reaction; (3) Take out the nickel foam sheet, wash it with water and ethanol, and dry it at 60 °C for 12 hours.

2. In step (1), the atomic ratio of Ni:Co in the Ni(NO3)2·6H2O and Co(NO3)2·6H2O precursor solutions is 1:1-2.

3. In step (1), the atomic ratio of Ni:Mn in the Ni(NO3)2·6H2O and MnCl2·4H2O precursor solutions is 1:0.5-2.

4. In step (1), the atomic ratio of Co:Mn in the Co(NO3)2·6H2O and MnCl2·4H2O precursor solutions is 1:0.5-2.

5. In step (1), the solvent can be one of isopropanol and glycerol or both of them can be added simultaneously.

6. When the solvents isopropanol and glycerol are added simultaneously in step (5), the volume ratio of isopropanol to glycerol is 1:1-3.

7. When isopropanol is used as the solvent in step (2), the hydrothermal reaction is carried out at 150-180 °C.

8. When glycerol is used as solvent in step (2), the hydrothermal reaction is carried out at 180-200 °C.

9. In step (2), when isopropanol and glycerol are used as solvents, the hydrothermal reaction is carried out at 180-200 °C.

10. The hydrothermal reaction time in step (2) is 2-10 h.

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