CN105261755A - Preparation method for nano-rod iron molybdate electrode material of lithium ion battery - Google Patents

Abstract

The invention provides a preparation method for a nano-rod iron molybdate electrode material of a lithium ion battery. The method comprises the following steps of taking ferric chloride and ammonium molybdate as raw materials and water as a solvent, adjusting a medium to be acidic with hydrochloric acid, and synthesizing an iron molybdate nano-rod by a one-step hydrothermal method; carrying out mechanical dispersion to prepare an electrode paste; and finally, carrying out vacuum drying to obtain the electrode material. According to electrochemical performance test, the novel nano structured electrode material can be known to have relatively high specific capacity and favorable lithium storage performance. Meanwhile, the raw materials involved in the preparation method are cheap and readily available, the preparation step is simple, and the obtained product has a certain application potential in the electrode material of the new energy lithium ion battery.

Description

A kind of preparation method of lithium ion battery electrode material of nano-rod iron molybdate

technical field

The invention relates to a simple one-step hydrothermal method for the preparation of iron molybdate lithium ion battery electrode materials. The preparation process includes a hydrothermal synthesis method and a mechanical dispersion method. Specifically, iron molybdate is synthesized by hydrothermal method, electrode material slurry is prepared by mechanical dispersion, and the electrode material of iron molybdate is obtained by drying in a vacuum oven. The invention belongs to the technical field of lithium ion battery material preparation and application.

Background technique

Secondary lithium-ion batteries, as the fastest growing energy storage system, have been widely used in portable electronic devices and hybrid electric vehicles. However, the performance of current commercial lithium-ion batteries falls short of the pursuit of high energy and power densities. And with the development of society, people's awareness of environmental protection is getting stronger and stronger, and it is of profound significance to seek an environmentally friendly and pollution-free lithium battery material with cheap and easy-to-obtain raw materials. Compared with commercial graphite, transition metal oxides have higher mass and volume specific capacities, for example, the theoretical specific capacities of Fe ₂ O ₃ and MoO ₃ are 1007 and 1116 mAh/g, respectively. However, almost all transition metal oxides exhibit defects of poor electrical conductivity and large volume change during the reaction with lithium, which seriously affect the cycle performance and rate capability of electrode materials. In order to limit this disadvantage, it is generally used to combine with carbon materials such as carbon nanotubes or graphene to prepare composite electrode materials, or to develop nanoscale electrode materials. Recently, ternary metal oxides have shown superior lithium storage performance than binary oxides, which incorporate two different metals into the same matrix. Because of its advantages in the diversity of metal elements and crystal structures, ternary metal oxides have more potential for development.

There are many studies on ternary metal oxides as anode materials for lithium-ion batteries. ChristieT.Cherian et al prepared a CoMoO ₄ submicron structure by pyrolyzing the polymer of the metal precursor solution collectively, and the monomer reached a reversible capacity of 990mAh/g at a current density of 100mA/g (ACS Appl. ). Similarly, Yao et al. prepared a composite structure in which CoMoO ₄ particles with a particle size of 3-5 nm were grown on reduced graphene oxide sheets by a hydrothermal method, and a high specific capacity of 920 mAh/g could be obtained at a current density of 74 mA/g. (ACS Appl. Mater. Interfaces 2014, 6, 20414? 20422.). JanHaetge et al. prepared mesoporous β-MgMoO ₄ thin film electrode materials with a uniform diameter of 19nm by using inorganic salt precursor polymer templates, and the reversible capacity was still stable at 162mAh/g after 100 cycles (Small.2013, 10.1002.). In addition, the output of molybdenum resources in my country ranks second in the world. Taking advantage of resources, developing and researching new molybdate materials and promoting their application in various industrial fields will have important economic and social values. Due to the advantages of low energy consumption, easy availability of raw materials, and less pollution, the hydrothermal method has been considered as an effective method for the synthesis of inorganic powder materials. In conclusion, finding an electrode material with a relatively high specific capacity and good lithium storage performance using an easy-to-operate method is the key to designing a lithium-ion battery.

Contents of the invention

The object of the present invention is to provide a preparation method of a lithium ion battery electrode material of nano-rod iron molybdate.

The invention uses ferric chloride and ammonium molybdate as raw materials, synthesizes nanorod-shaped iron molybdate crystals through a hydrothermal method; mechanically disperses to prepare electrode slurry; and finally obtains lithium ion battery electrode materials after vacuum drying. Electrochemical tests show that the new iron molybdate electrode material has a relatively high specific capacity and good lithium storage performance. In addition, the iron molybdate material has the advantages of cheap and easy-to-obtain synthetic raw materials, simple preparation method, environmental protection and pollution-free, unique and novel material, and has a certain potential for commercial practical application.

The present invention is achieved through the following technical solutions.

A kind of preparation method of the lithium ion battery electrode material of the present invention is characterized in that having following process and step:

a. Synthesis of nanorod-shaped ferric molybdate crystals by hydrothermal method: Weigh 0.05-0.1g ferric chloride solid into 12.5-25mL deionized water, stir for 0.5-1h; then add 0.05-0.1g ammonium molybdate and continue stirring for 0.5-1h ; Add 10-20 drops of dilute hydrochloric acid dropwise to adjust the pH to acidity; transfer the mixture to a hydrothermal kettle, and react at 150-180°C for 6-12h; centrifuge, wash with water until neutral, and dry overnight to obtain the product;

b. Preparation of ferric molybdate/conductive carbon slurry: Weigh 0.01g of the above-mentioned ferric molybdate product and 0.00125g conductive carbon acetylene black into plastic centrifuge tubes respectively; add 0.05g of adhesive polyvinylidene fluoride, and use A high-speed internal rotary beater disperses the slurry, repeating 5-10 times per minute to obtain a uniform black colloidal slurry of iron molybdate/conductive carbon; the ratio of electrode material to adhesive is 8:1-9 :1;

c. Preparation of electrode materials for lithium iron molybdate batteries: evenly coat the above slurry on the pre-treated metal copper current collector, and dry in a vacuum oven. The temperature setting range is 60-80°C, and the drying time is 20-24h; the lithium ion battery electrode material of iron molybdate is finally obtained.

Description of drawings

Fig. 1 is the X-ray diffraction (XRD) pattern of the iron molybdate crystal of the present invention.

Fig. 2 is a scanning electron microscope (SEM) photo of the iron molybdate crystal of the present invention.

Fig. 3 is a cycle performance diagram of the charge and discharge of the iron molybdate crystal at a low current (0.1C) of the present invention.

detailed description

Specific embodiments of the present invention are described below.

Example 1

Weigh 0.05g ferric chloride solid and disperse in 12.5mL deionized water, stir for 0.5h; then add 0.05g ammonium molybdate and continue stirring for 0.5h; add 10 drops of dilute hydrochloric acid to adjust the pH to 1.5; transfer the mixture to a hydrothermal kettle in 180°C for 6 h; naturally cooled to room temperature, washed with deionized water to neutrality, and dried overnight to obtain the product.

Weigh 0.01g of the above-mentioned ferric molybdate product and 0.00125g of conductive carbon acetylene black into plastic centrifuge tubes; add 0.05g of adhesive polyvinylidene fluoride, and disperse the slurry with a high-speed internal rotary beater for one minute each time Repeat 6 times to obtain uniform black colloidal slurry of iron molybdate/conductive carbon.

The above slurry is uniformly coated on the pre-treated metal copper current collector, and dried in a vacuum oven with the temperature set at 80°C and the drying time is 20 hours; finally, the lithium ion battery electrode material of iron molybdate is obtained.

Battery assembly and testing

Put the prepared electrode to be tested above into a self-made stainless steel battery mold for testing. With the high-purity lithium sheet as the positive electrode, the electrode material of the present invention as the negative electrode, the polypropylene porous membrane (Celgard2400) as the diaphragm, the electrolyte solution is 1mol/L lithium hexafluorophosphate LiPF ₆ and ethylene carbonate (EC)/dimethyl carbonate (DMC ) (weight ratio 1:1) mixed solution. Cell assembly was performed in a glove box filled with high-purity argon. The test current density is 0.1C, where 1C is equal to 1000mA/g, and the test voltage range is 0.005-3V.

Shown in accompanying drawing 1: after analysis, it is known that the product is an iron molybdate material with higher crystallinity, and the obtained diffraction peak matches iron molybdate (PDF31-0642). Accompanying drawing 2 is its SEM picture: It can be seen that iron molybdate presents the shape of uniformly distributed nanorods. It can be seen from Figure 3 that the specific capacity of the battery is in the range of ~400-1200mAh/g within 50 cycles of low current charge and discharge. It can be seen that this material has a high lithium storage capacity, and if the cycle performance is improved by carbon loading, it has a certain potential for commercialization.

Claims (1)

1. a preparation method for the lithium ion battery electrode material of nano bar-shape iron molybdate, is characterized in that having following process and step:

A. water heat transfer nano bar-shape iron molybdate crystal: take 0.05-0.1g iron chloride solid in 12.5-25mL deionized water, stirs 0.5-1h; Add 0.05-0.1g ammonium molybdate again to continue to stir 0.5-1h; Be added dropwise to 10-20 and drip watery hydrochloric acid adjustment pH to acid; Mixture is transferred in water heating kettle, at 150-180 DEG C, reacts 6-12h; Centrifugal water is washed till neutrality, and dried overnight obtains product;

B. the preparation of iron molybdate/conductive carbon pastes: take the above-mentioned iron molybdate product of 0.01g, 0.00125g conductive carbon acetylene black respectively in plastic centrifuge tube; Add the adhesive Kynoar of 0.05g; With high speed inner-rotary type beater dispersion slurries, each one minute, repeat 5-10 time, obtain the gluey slurry of black of homogeneous iron molybdate/conductive carbon; Wherein the ratio of electrode material and adhesive is 8:1-9:1;

C. the preparation of iron molybdate lithium ion battery electrode material: above-mentioned slurry is coated on the metallic copper collector handled well in advance uniformly, be placed in vacuum drying oven dry, it is 60-80 DEG C that temperature arranges scope, drying time 20-24h; Finally obtain the lithium ion battery electrode material of iron molybdate.