WO2015103920A1

WO2015103920A1 - Multi-stage micro-nano structural material and preparation method therefor, and battery containing same

Info

Publication number: WO2015103920A1
Application number: PCT/CN2014/093907
Authority: WO
Inventors: 孙晓明; 吴小超; 陆之毅
Original assignee: 北京化工大学
Priority date: 2014-01-09
Filing date: 2014-12-16
Publication date: 2015-07-16
Also published as: CN103746112A; CN103746112B

Abstract

Disclosed is a material with a multi-stage micro-nano structure on the surface. The material comprises: a porous conductive substrate; primary micron-rods or primary micron-piece arrays which grow perpendicular to the substrate on the porous conducting substrate; and a plurality of ferroferric oxide secondary nano-rods radially growing on each primary micron-rod or a plurality of ferroferric oxide secondary nano-rods growing perpendicular to each primary micron-piece on the primary micron-piece. The material can be used as a negative electrode material of a battery, in particular an alkaline battery, and the battery using the negative electrode material has unique advantages, such as excellent energy storage characteristics, a large specific capacity, high energy density, high power density and high cyclicity, which can be maintained very well under high and low current densities.

Description

Multi-stage nano-micro structure material, preparation method thereof and battery containing the same

Technical field

The invention belongs to the field of inorganic advanced nano material technology.

Background technique

Alkaline batteries are considered to be environmentally friendly and highly efficient batteries that can be recycled many times. Nickel-iron batteries are an important branch. The positive electrode active material of the ferronickel battery is mainly nickel oxyhydroxide, and the negative electrode active material is mainly iron, which is a light-weight, long-life and easy-maintaining alkaline storage battery [J. Power. Sources., 1984, 12, 177-192]. Compared with the currently widely used nickel-cadmium batteries, lead-acid batteries, the battery has a cycle life of more than 2,000 times and a service life of more than 20 years, so it has received extensive attention and vigorous development. However, the electrode materials for the preparation of ferronickel batteries generally have obvious defects. Some may require relatively high synthesis temperatures, some powder materials have poor crystallinity, are not in contact with the current collector, and have poor electron transport effects, and some have environmental effects. Obvious hazard.

In order to solve the above problems, the present invention has been proposed.

Summary of the invention

In a first aspect, the present invention is directed to a material having a multi-stage nano-micron structure on its surface, comprising:

Porous conductive substrate;

a primary microrod or primary microarray array grown perpendicular to the substrate on the porous electrically conductive substrate;

a plurality of galvanic iron secondary nanorods radially growing on each of said primary microrods, or a plurality of galvanic iron secondary nanorods grown perpendicular to said microplates on each of said primary microplates .

In a second aspect, the invention relates to a method of preparing a material having a multi-stage nano-micron structure on its surface, comprising the steps of:

a. The porous conductive substrate is placed obliquely in the first reaction vessel, and then the first aqueous solution containing soluble cobalt salt, ammonium fluoride and urea is added to the reaction vessel, and then the reaction vessel is sealed, heated and under autogenous pressure. Performing a first hydrothermal reaction to grow a cobalt hydroxide primary microrod or primary microchip array perpendicular to the substrate on the surface of the porous electrically conductive substrate;

b. taking out the porous conductive substrate, washing and drying;

c. The porous conductive substrate treated in step b is placed obliquely in the second reaction vessel, and a second aqueous solution containing soluble iron or ferrous salt, ammonium fluoride and urea is added to the reaction vessel to seal the reaction. The kettle is heated and subjected to a second hydrothermal reaction under autogenous pressure to radially grow a plurality of iron hydroxide secondary nanorods on each of said cobalt hydroxide primary microrods, or in each of said hydroxides a plurality of ferric hydroxide secondary nanorods grown on the cobalt primary microchip perpendicular to the microchip;

d. take out the porous conductive substrate again, wash and dry;

e. calcining the porous electrically conductive substrate under inert gas protection such that the cobalt hydroxide primary microrod or primary microsheet is converted to a triammonium trioxide primary microrod or primary microplate, and the iron hydroxide secondary nanorod is converted to triiron tetroxide Secondary nanorods.

In a third aspect, the invention relates to a battery whose negative electrode comprises the material mentioned in the first aspect of the invention.

In a fourth aspect, the invention relates to the use of the material mentioned in the first aspect of the invention as a battery anode material.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the structure of a battery of the present invention, which also shows a schematic structural view of a material having a multi-stage nano-micron structure on the surface according to the first aspect of the present invention, and an enlarged view of the negative electrode material thereof, wherein the primary micron is shown. The structure is a micron rod.

Figure 2 is a scanning electron micrograph (SEM) of the material of the present invention, in which it is clearly shown that the tricobalt oxide primary microrod array grows perpendicular to the surface of the substrate, and each of the tricobalt oxide primary microrods grows radially into the galvanic trioxide secondary. Nano stave

Figure 3 is an X-ray diffraction pattern (XRD) of the material of the present invention. It can be discerned from the comparison of the standard spectrum that the primary microrod component on the material of the present invention is a cobalt tetraoxide crystal, and the secondary nanorod component is a ferroferric oxide crystal.

4 is a cyclic voltammogram of the material of the present invention.

Figure 5 is a graph showing the cycle stability of the material of the present invention.

Figure 6 is a scanning electron micrograph (SEM) of another embodiment of the material of the present invention, in which it is clearly shown that the array of primary particles of cobalt trioxide is grown perpendicular to the surface of the substrate, and each of the primary microplates of cobalt tetraoxide is perpendicular to the microchip. A plurality of ferroferric oxide secondary nanorods are grown on the surface.

Figure 7 is an X-ray diffraction pattern (XRD) of the material shown in Figure 6. Comparing with the standard spectrum, it can be discerned that the primary microchip component on the material of the present invention is a cobalt tetraoxide crystal, and the secondary nanorod component is a ferroferric oxide crystal.

Figure 8 is a cyclic voltammogram of the material of Figure 6 of the present invention.

Figure 9 is a cycle stability diagram of the material of Figure 6 of the present invention.

Figure 10 is an SEM image of a positive electrode material used in pair with a material of the present invention as a negative electrode of a battery, the figure showing that the array of primary aluminum sulphide rods is grown perpendicular to the surface of the substrate, and each of the cobalt trioxide primary microrods is radially grown in nickel oxide. Grade nanorods.

Figure 11 is an XRD pattern of a positive electrode material used in combination with the material of the present invention as a negative electrode of the battery. It can be discerned from the comparison with the standard spectrum that the primary microrod component on the positive electrode material is a cobalt tetraoxide crystal, and the secondary nanorod component is nickel oxide. Crystal.

Figure 12 is a cyclic voltammogram of a positive electrode material used in pair with a material of the present invention as a battery negative electrode.

Fig. 13 is a cycle stability diagram of a positive electrode material used in pair with a material of the present invention as a battery negative electrode.

Figure 14 is a scanning electron micrograph (SEM) of another embodiment of the material of the present invention, wherein it is clearly shown that the tricobalt oxide primary microarray array is grown perpendicular to the surface of the substrate, and each of the trittrium cobalt trioxide primary microsheets is perpendicular to the micron wafer. A plurality of ferroferric oxide secondary nanorods are grown on the surface.

Figure 15 is an X-ray diffraction pattern (XRD) of the material shown in Figure 14. It can be discerned from the comparison with the standard spectrum that the primary micro-sheet component on the material of the present invention is a cobalt tetraoxide crystal, and the secondary nanorod composition is a ferroferric oxide crystal.

Figure 16 is a cyclic voltammogram of the material of Figure 14 of the present invention.

Figure 17 is a cycle stability diagram of the material of Figure 14 of the present invention.

Figure 18 is a cyclic voltammogram of a battery assembled from the material of the present invention as a negative electrode and the positive electrode material shown in Figure 10.

Fig. 19 is a discharge graph of a battery assembled from the material of the present invention as a negative electrode and the positive electrode material shown in Fig. 10.

Fig. 20 is a graph showing the rate characteristic of a battery in which the material of the present invention is used as a negative electrode and the positive electrode material shown in Fig. 10 is assembled.

Fig. 21 is a capacity cycle stability diagram of a battery assembled from the material of the present invention as a negative electrode and the positive electrode material shown in Fig. 10.

Figure 22 is a cyclic voltammogram of a battery assembled from a material grown on a foamed nickel substrate of the present invention as a negative electrode and a positive electrode material shown in Figure 10.

Figure 23 is a graph showing the discharge of a battery grown on a foamed nickel substrate of the present invention as a negative electrode and a battery assembled from the positive electrode material shown in Figure 10.

Fig. 24 is a graph showing the rate characteristic of a battery in which the material grown on the foamed nickel substrate of the present invention is used as a negative electrode and a battery assembled from the positive electrode material shown in Fig. 10.

Figure 25 is a negative electrode and a material grown on a foamed nickel substrate of the present invention Capacity cycle stability diagram of battery assembled from the positive electrode material shown in FIG.

Figure 26 is a schematic view showing the structure of a material having a multi-stage nano-micron structure on the surface according to the first aspect, wherein the primary micro-structure is a micro-chip.

Detailed description of the invention

Various aspects of the invention are now described in detail.

A first aspect of the invention relates to a material having a multi-stage nano-micron structure. The porous conductive substrate as used herein refers to a conductive substrate having a porous structure, which may be metal or carbon in material, and may be referred to as a metal foam or a porous carbon fiber felt, respectively. The metal may be selected from any suitable metal, such as copper foam when the metal is copper, and foamed nickel when the metal is nickel. For a more detailed description and preparation of foam metal or porous carbon fiber mat, reference can be made to the existing patent literature. Such foamed metal or porous carbon fiber mats are also commercially available or can be made in accordance with the relevant literature.

A plurality of gallium tetraoxide primary microrods or microchip arrays are grown in an array perpendicular to the surface of the substrate on the surface of the substrate.

A plurality of ferroferric oxide secondary nanorods are radially grown on each of the primary cobalt trioxide rods. Alternatively, a plurality of ferroferric oxide secondary nanorods are grown perpendicular to the microplate on each of the primary particles of cobalt tetraoxide.

In shape, the base is similar to the earth, the primary microarray array is similar to the plant stem that grows on the ground, and the secondary nanorods are similar to the leaves that grow in all directions on the main stem of the plant; or, the base is similar to the earth The primary microchip array is similar to a wood panel array that is vertical on the ground, while the secondary nanorods are similar to the nails nailed to the wood. The present invention refers to such a structure as a "multi-stage nano-micron structure", i.e., a micro-structure and a nano-structure arrangement having multiple levels.

Such a multi-stage nano-micron structure undoubtedly greatly increases the surface area of the material of the present invention and improves its electrical contact efficiency. The inventors have found that the material of the present invention is not It is often suitable as a battery negative material, but it is not excluded that the materials of the present invention will find other uses in the future.

The positive electrode material also has a "multi-stage nano-micron structure", but on the positive electrode material, the composition of the primary micro-array is tricobalt tetroxide, and the composition of the secondary nano-rod is nickel oxide.

A second aspect of the invention relates to a method of preparing a material having a multi-stage nano-micron structure on its surface, the steps of which are detailed below:

Step a. The porous conductive substrate is placed obliquely in the first reaction vessel, and then the first aqueous solution containing soluble cobalt salt, ammonium fluoride and urea is added to the reaction vessel, and then the reaction vessel is sealed, heated and under autogenous pressure. A first hydrothermal reaction is carried out to grow a cobalt hydroxide primary microrod or microchip array perpendicular to the substrate on the surface of the porous electrically conductive substrate. Preferably, the porous electrically conductive substrate is previously cleaned to remove dirt and impurities from the surface. Such washing may be ultrasonically washed in concentrated hydrochloric acid, then transferred to a solvent such as deionized water and ethanol, and ultrasonically washed again. In the first aqueous solution, the concentration of each substance can be adjusted as needed. For example, in a preferred embodiment, the soluble cobalt salt concentration is 0.025-0.1 mol/liter, and the ammonium fluoride concentration is 0.1-0.4 mol/ The urea concentration is from 0.1 to 0.5 mol/l. Of course, other concentration ranges can also be used. The conditions of the first hydrothermal reaction can also be adjusted as needed. For example, a preferred condition is a temperature of 80 to 110 ° C and a reaction time of 7 to 12 hours. The arrangement density, growth height, and the like of the primary micro-array on the substrate can be adjusted by changing the concentration of each substance or changing the conditions of the first hydrothermal reaction. In addition, adjusting the first hydrothermal reaction conditions, it is also possible to control the morphology of the micro-array, for example, the temperature in the first hydrothermal reaction is 80-100 ° C, and the reaction time is 6-8 hours, the reaction generates hydrogen. The primary micron structure of cobalt oxide; at a temperature of 100-120 ° C, and a reaction time of 8-12 hours, the reaction produces a cobalt hydroxide primary microrod structure. Wherein the soluble cobalt salt is selected from the group consisting of cobalt nitrate, cobalt sulfate or cobalt chloride, or any of their hydrates with water of crystallization. After the first hydrothermal reaction is completed, The first reactor was cooled to room temperature and then opened.

Step b. The porous conductive substrate is taken out, washed and dried. There is no limitation on the specific washing and drying method. For example, the washing may be carried out by any suitable solvent such as water, ethanol or the like, or by ultrasonic cleaning, and the drying may be carried out in an oven.

Step c. The porous conductive substrate treated in step b is placed obliquely in the second reaction vessel, and a second aqueous solution containing soluble iron or ferrous salt, ammonium fluoride and urea is added to the reaction vessel, and the sealing is sealed. The reactor is heated, and subjected to a second hydrothermal reaction under autogenous pressure to radially grow a plurality of iron hydroxide secondary nanorods on each of the cobalt hydroxide primary microrods, or in each of the hydrogens A plurality of iron hydroxide secondary nanorods grown on the primary micron sheet of the cobalt oxide perpendicular to the microchip. In the second aqueous solution, the concentration of each substance may be adjusted as needed. For example, in a preferred embodiment, the soluble iron salt or ferrous salt concentration is 0.0125-0.075 mol/liter, and the ammonium fluoride concentration is 0.1- 0.4 mol/L, urea concentration is 0.1-0.5 mol/L; the conditions of the second hydrothermal reaction can also be adjusted as needed, for example, a preferred condition is: temperature is 80-120 ° C, reaction time is 2- 10 hours. The soluble iron or ferrous salt is selected from the group consisting of iron nitrate, iron sulfate, iron chloride, ferrous sulfate or ferrous chloride, or any of their hydrates with water of crystallization. Whether using soluble iron salts or soluble ferrous salts, dissolved oxygen in water has a certain oxidation effect, and after hydrothermal reaction, iron hydroxide secondary nanorods are finally formed. After the second hydrothermal reaction was completed, the second reactor was cooled to room temperature and then opened.

Step d. The porous conductive substrate was taken out again, washed and dried. There is no limitation on the specific washing and drying method. For example, the washing may be carried out by any suitable solvent such as water, ethanol or the like, or by ultrasonic cleaning, and the drying may be carried out in an oven.

Step e. calcining the porous conductive substrate under inert gas protection to convert the cobalt hydroxide primary microrod or micron array into a cobalt trioxide primary microrod or micro The rice array is arrayed and the iron hydroxide secondary nanorods are converted into ferric oxide secondary nanorods. The inert gas is, for example, nitrogen. The calcination temperature, calcination time, and atmosphere are adjusted to ensure conversion of cobalt hydroxide to tri-cobalt oxide after calcination, and conversion of ferric hydroxide to triiron tetroxide. The inventors have found in experiments that when calcined under a nitrogen atmosphere, iron hydroxide produces the triiron tetroxide we need; the cobalt hydroxide will only produce tricobalt tetraoxide when calcined at the temperature shown herein. . For example, a preferred set of calcination conditions are: a calcination temperature of 450 to 550 ° C and a calcination time of 2 to 4 hours.

The above preparation method is synthesized under simple hydrothermal reaction conditions, the method is simple, the cost is low, and the repeatability is good; no organic solvent and surfactant are used, and the environment is very friendly; the obtained product structure is uniform and orderly arranged. More importantly, this is a monolithic material. The active material of this material is directly connected to the current collector. It is produced without adding a binder, and has a novel structure and good electrical properties. In addition, it controls the cobalt salt in the solution. The type and concentration of nickel salt, iron salt or ferrous salt can synthesize multi-level nano-micron structures with different sizes and degrees of density, and the morphology of the material can be controlled. The negative electrode material can be assembled into a water-based high-power alkaline battery with a plurality of positive electrode materials having a similar structure, and the surface of the positive electrode material also has a multi-stage nano-micron array structure. After testing, the positive and negative poles have stable capacitance and capacity matching, and the assembled battery has good electrical contact and excellent performance. At a current density of 0.33 A/g, the capacity is 170.8 mAh/g; when the power density is 200 W/kg, the energy density is 102.5 Wh/kg. After 500 cycles of constant current charge and discharge, its capacity attenuation is less than 22%. . This alkaline battery has a good prospect in practical applications.

A third aspect of the invention relates to a battery whose negative electrode comprises the material of the first aspect of the invention described above. When the material is used as a negative electrode of a battery, it can be oxidized with various conventional positive electrode materials such as nickel oxide nanorods, nickel hydroxide nanowalls, cobalt tetraoxide nanowires coated with cobalt trioxide microplates, nickel oxide nanowires coated with cobalt trioxide microplates, and oxidized. Nickel nanowires were coated with cobalt tetraoxide micron wires for matching.

In a preferred embodiment of the third aspect of the present invention, when the material of the present invention is used as a negative electrode material for a battery, the surface of the positive electrode material matched thereto also has a multi-stage nano-micron structure, and the positive electrode material comprises:

a porous electrically conductive substrate that is the same as or different from the porous electrically conductive substrate in the negative electrode material;

An array of tricobalt oxide primary microrods or microchips grown perpendicular to the substrate on the porous electrically conductive substrate;

A plurality of nickel oxide secondary nanorods radially growing on each of said trittrium cobalt primary microrods or a plurality of nickel oxide secondary nanorods grown perpendicular to said microplates on each of said primary microchips.

The positive electrode material having a multi-stage nano-micron structure on the surface may be prepared in a similar manner to the material of the present invention except that the soluble iron salt or ferrous salt is replaced with a soluble nickel salt, and the substances in the second aqueous solution are appropriately adjusted. The concentration and the second hydrothermal reaction conditions, and the calcination in step e can be carried out without the protection of an inert gas.

The electrolytic solution in the battery of the third aspect of the invention is an aqueous solution of an alkali metal hydroxide, and its concentration is preferably 1 mol/liter.

Since the surface of the present invention having a multi-stage nano-micron structure is used as the negative electrode material, the battery involved in the third aspect of the present invention has unique advantages such as excellent energy storage characteristics, large specific capacity, high energy density, and power. High density, good cycleability, and good retention at high and low current densities. This can be verified from electrical performance test data such as the cyclic voltammetry curve, discharge curve, rate characteristic map, and capacity cycle stability map of the battery.

detailed description

The invention is further illustrated by the following examples. The examples are merely illustrative and not limiting.

Example 1

a. The copper foam substrate was placed obliquely in the first reaction vessel, and then the first reactor containing 0.05 mol/liter of cobalt nitrate, 0.2 mol/liter of ammonium fluoride and 0.25 mol/liter of urea was added to the reactor. An aqueous solution, then sealed the reactor, heated to 120 ° C and maintained at autogenous pressure for 12 hours for the first hydrothermal reaction to grow the cobalt hydroxide primary microrod array perpendicular to the substrate on the surface of the copper foam substrate;

b. taking out the foamed copper substrate, washing and drying;

c. The copper foam substrate treated in the step b is placed obliquely in the second reaction vessel, and then the iron nitrate containing 0.075 mol/liter, 0.2 mol/liter ammonium fluoride and 0.25 mol/liter is added to the reactor. a second aqueous solution of urea, sealing the reaction vessel, raising the temperature to 100 ° C and maintaining a second hydrothermal reaction under autogenous pressure for 6 hours to radially grow a plurality of each of the cobalt hydroxide primary microrods Ferric hydroxide secondary nanorods;

d. remove the foamed copper substrate again, wash and dry;

e. Calcining the copper foam substrate under nitrogen protection at 450 ° C for 3 hours to convert the cobalt hydroxide primary microrod into a cobalt trioxide primary microrod and converting the ferric hydroxide secondary nanorod into a ferroferric oxide secondary nanorod.

See Figure 2 for the scanning electron micrograph, Figure 3 for the XRD spectrum, Figure 4 for the cyclic voltammogram, and Figure 5 for the cycle stability diagram.

Example 2

Referring to the method of Example 1, the temperature in step a of Example 1 was changed to 100 ° C, and the time was changed to 6 hours.

See Figure 6 for the scanning electron micrograph, Figure 7 for the XRD spectrum, Figure 8 for the cyclic voltammogram, and Figure 9 for the cycle stability diagram.

Example 3

Referring to the method of Example 1, the copper foam substrate was replaced with a foamed nickel substrate.

Example 4

Referring to the method of Example 1, the copper foam substrate was replaced with a porous carbon fiber felt substrate.

Example 5

Referring to the method in Example 1, the copper foam substrate was replaced with a foamed nickel substrate, and the inclusion of the second aqueous solution in the step c of Example 1 was changed to 0.075 mol/L of nickel nitrate and 0.25 mol/L of urea. The temperature in step e of Example 1 was changed to 250 ° C without nitrogen protection.

See Figure 10 for its scanning electron micrograph, Figure 11 for the XRD spectrum, Figure 12 for the cyclic voltammogram, and Figure 13 for the cycle stability diagram.

Example 6

Referring to the method of Example 1, the copper foam substrate was replaced with a foamed nickel substrate, and the ferric nitrate in the second aqueous solution in the step c of Example 1 was replaced with ferrous sulfate.

See Figure 14 for its scanning electron micrograph, Figure 15 for the XRD spectrum, Figure 16 for the cyclic voltammogram, and Figure 17 for the cycle stability diagram.

Example 7

The material obtained in Example 1 was a negative electrode, and the material obtained in Example 5 was a positive electrode, and a battery was assembled using a 1 mol/L potassium hydroxide aqueous solution as an electrolytic solution.

See Figure 18 for the cyclic voltammogram, Figure 19 for the discharge curve, Figure 20 for the rate characteristic diagram, and Figure 21 for the capacity cycle stability diagram.

Example 8

The material obtained in Example 2 was a negative electrode, and the material obtained in Example 5 was a positive electrode, and a battery was assembled using a 1 mol/L potassium hydroxide aqueous solution as an electrolytic solution.

See Figure 22 for the cyclic voltammogram, Figure 23 for the discharge curve, Figure 24 for the rate characteristic diagram, and Figure 25 for the capacity cycle stability diagram.

Claims

A material having a multi-stage nano-micron structure on the surface, comprising:

Porous conductive substrate;

a primary microrod or primary microarray array grown perpendicular to the substrate on the porous electrically conductive substrate;

a plurality of galvanic iron secondary nanorods radially growing on each of said primary microrods, or a plurality of galvanic iron secondary nanorods grown perpendicular to said microplates on each of said primary microplates .
The material of claim 1 wherein said porous electrically conductive substrate is selected from the group consisting of copper foam, nickel foam or porous carbon fiber mat.
The material of claim 1 wherein said primary microrod or primary microplate is a tricobalt trioxide rod or a cobalt trioxide microplate.
The material of claim 1 wherein said tri-cobalt trioxide primary microrod has a size of about 10 microns in length and a diameter of about 300 nanometers; said tri-cobalt trioxide primary micro-sheet having a size of about 10 microns in length and a thickness of about 800 nanometers; The size of the secondary ferrite oxide nanorods is about 200 nanometers in length and about 30 nanometers in diameter.
A method of preparing a material having a multi-stage nano-micron structure on the surface, comprising the steps of:

a. The porous conductive substrate is placed obliquely in the first reaction vessel, and then the first aqueous solution containing soluble cobalt salt, ammonium fluoride and urea is added to the reaction vessel, and then sealed The reaction vessel is heated and subjected to a first hydrothermal reaction under autogenous pressure to grow a cobalt hydroxide primary microrod or primary microchip array perpendicular to the substrate on the surface of the porous electrically conductive substrate;

b. taking out the porous conductive substrate, washing and drying;

c. The porous conductive substrate treated in step b is placed obliquely in the second reaction vessel, and a second aqueous solution containing soluble iron or ferrous salt, ammonium fluoride and urea is added to the reaction vessel to seal the reaction. The kettle is heated and subjected to a second hydrothermal reaction under autogenous pressure to radially grow a plurality of iron hydroxide secondary nanorods on each of said cobalt hydroxide primary microrods, or in each of said hydroxides a plurality of ferric hydroxide secondary nanorods grown on the cobalt primary microchip perpendicular to the microchip;

d. take out the porous conductive substrate again, wash and dry;

e. calcining the porous electrically conductive substrate under inert gas protection such that the cobalt hydroxide primary microrod or primary microsheet is converted to a triammonium trioxide primary microrod or primary microplate, and the iron hydroxide secondary nanorod is converted to triiron tetroxide Secondary nanorods.
The method of claim 5, wherein said first aqueous solution has a concentration of said soluble cobalt salt of from 0.025 to 0.1 mol/liter, an ammonium fluoride concentration of from 0.1 to 0.4 mol/liter, and a urea concentration of from 0.1 to 0.5 mol/liter. To form a primary structure of cobalt hydroxide; the concentration of the soluble iron or ferrous salt in the second aqueous solution is 0.0125-0.075 mol/liter, the concentration of ammonium fluoride is 0.1-0.4 mol/L, and the concentration of urea is 0.1-0.5 mol. / liter; the conditions of the first hydrothermal reaction are: temperature of 80-100 ° C, reaction time of 6-8 hours The reaction forms a primary micro-micron structure of cobalt hydroxide; the temperature is 100-120 ° C, and the reaction time is 8-12 hours to form a cobalt hydroxide primary micro-rod structure; the second hydrothermal reaction condition is: temperature 80 -120 ° C, the reaction time is 2-10 hours; in the step e, the calcination temperature is 450-550 ° C, the calcination time is 2-4 hours; wherein the soluble cobalt salt is selected from cobalt nitrate, cobalt sulfate or chlorination Cobalt; the soluble iron or ferrous salt is selected from the group consisting of ferric nitrate, ferric sulfate, ferric chloride, ferrous sulfate or ferrous chloride.
A battery, the negative electrode comprising the material of claim 1, preferably an alkaline rechargeable battery.
The battery of claim 7 wherein the surface of the positive electrode material also has a nano-micron array structure, the positive electrode material comprising:

a porous electrically conductive substrate that is the same as or different from the porous electrically conductive substrate in the negative electrode material;

a gallium trioxide primary microrod or primary microchip array grown perpendicular to the substrate on the porous electrically conductive substrate;

A plurality of nickel oxide secondary nanorods radially growing on each of said trittrium cobalt primary microrods or a plurality of nickel oxide secondary nanorods grown perpendicular to said microplates on each of said primary microchips.
The battery of claim 8 wherein the electrolyte is an aqueous solution of an alkali metal hydroxide.
Use of the material of claim 1 as a negative electrode material for a battery negative electrode material, particularly an alkaline rechargeable battery.