WO2018032980A1

WO2018032980A1 - Manufacturing method of positive-electrode material for sodium-ion battery

Info

Publication number: WO2018032980A1
Application number: PCT/CN2017/095859
Authority: WO
Inventors: 许志
Original assignee: 福建新峰二维材料科技有限公司
Priority date: 2016-08-15
Filing date: 2017-08-03
Publication date: 2018-02-22
Also published as: CN107768668B; CN107768668A

Abstract

A manufacturing method of a positive-electrode material for a sodium-ion battery. The method comprises the following steps: preparing a GO suspension in anhydrous ethanol; dissolving iodine in the GO suspension in anhydrous ethanol to prepare a GO/iodine suspension; and performing vacuum filtration on the GO/iodine suspension to form an iodine quantum dot-composited graphite oxide (IQDs@GO) film; washing and drying the IQDs@GO film; performing an acid treatment on the washed and dried IQDs@GO film to obtain, by means chemical reduction, a free-standing iodine quantum dot-modified reduced graphene oxide (IQDs@RGO) film; and washing and oven drying the IQDs@RGO film. The manufacturing method of the present invention has a simple process and low cost, and a sodium-ion battery manufactured with the method exhibits excellent electrochemical properties, and has a high capacity, superior cycling stability, and good rate performance.

Description

Preparation method of sodium ion battery cathode material

Technical field

The invention relates to the technical field of sodium ion batteries, in particular to a method for preparing a cathode material of a sodium ion battery.

Background technique

In today's energy era, it is important to develop energy storage devices with high energy density. Lithium-ion batteries (LIBs) are widely used in portable electronic products and network storage due to their relatively high discharge voltage, energy density, and good power performance. However, because of its high cost and lack of raw material lithium, new types of alternative products have emerged, such as aluminum-ion batteries and sodium-ion batteries (SIBs). Sodium and lithium belong to the same main group and have similar physical and chemical properties. Sodium ion batteries (SIBs) have similar principles to lithium ion batteries (LIBs), and the principle of battery charge and discharge is basically the same. Compared with lithium-ion batteries, sodium-ion batteries have the following characteristics: sodium resources are abundant, accounting for 2.64% of the crust element reserves, and the price is low and widely distributed. The sodium-ion batteries (SIBs) have low cost advantages, so they are stored in large-scale energy. It has broad application prospects.

Sodium ion batteries (SIBs) have been known for decades, but its commercial development has not been smooth. The main reason is that no positive electrode materials have been found which are simple to prepare and low in cost. So far, research on SIBs has focused on exploring more ideal cathode materials that can be embedded in Na ⁺ such as Na _x CoO ₂ , NaCrO ₂ , Na ₂ Ni ₂ TeO ₆ , Na ₃ V ₂ O _2x (PO ₄ ). ₂ F _3-2 , Na ₂ FePO ₄ F, Na ₄ Fe ₃ (PO ₄ ) ₂ (P ₂ O ₇ ), Na ₂ MnFe(CN) ₆ , NaNi _1/3 Mn _1/3 Fe _1/3 O ₂ Wait. However, these materials are complicated in preparation process, and the cost of using them as battery materials is not low, so there is an urgent need to find another low-cost alternative material as a positive electrode material for SIBs.

Summary of the invention

In view of the above problems, the present invention provides a method for preparing a positive electrode material for a sodium ion battery.

In order to solve the problem that the conventional cathode material manufacturing process for sodium ion batteries is complicated and costly, the technical solution adopted by the present invention is: a method for preparing a cathode material of a sodium ion battery, the method comprising the following steps:

Preparing an anhydrous ethanol suspension of GO;

Preparing a suspension of GO/iodine by adding iodine to the anhydrous ethanol suspension of GO;

The GO/iodine suspension is subjected to vacuum filtration treatment to form an iodine quantum dot composite graphene oxide (IQDs@GO) film;

Washing and drying the IQDs@GO film;

The IQDs@GO film after water washing and drying treatment is subjected to acid treatment, and chemical reduction is performed to obtain a reduced graphene oxide (IQDs@RGO) film modified without supporting iodine quantum dots;

The IQDs@RGO film is washed and dried.

Further, the anhydrous ethanol suspension of GO is prepared by dissolving 50 mg of GO in 40 mL of absolute ethanol and ultrasonically shaking for 2 hours.

Further, the GO/iodine suspension is prepared by dissolving 0.5 g of iodine in the anhydrous ethanol suspension of the GO, and after all the iodine is dissolved, a uniform suspension is obtained, and then 30 mL of deionized water is obtained ( DIW) The suspension obtained above was poured, and the above anhydrous ethanol/DIW suspension containing GO and iodine was continuously stirred for 12 hours.

Further, the vacuum filtration treatment is a vacuum filtration of a suspension of GO/iodine by a filter, the filter being of a PVDF material, and the filter is given a certain positive pressure during the filtration process.

Further, the water washing and drying treatment is to first wash the IQDs@GO film with deionized water, then freeze-dry overnight, and then peel off from the filter.

Further, the acid treatment is to immerse the obtained IQDs@GO film in a 55% HI acid solution, and the IQDs@GO film is chemically reduced to obtain an IQDs@RGO film which does not require support.

Further, the water washing and drying process is to clean the IQDs@RGO film with deionized water, and then dry in a vacuum oven at 60 ° C for 24 hours.

From the above description of the structure of the present invention, the present invention has the following advantages over the prior art:

The invention provides a preparation method of an IQDs@RGO film as a positive electrode material of a sodium ion battery (SIB), the material preparation process is simple and the cost is low, and other battery positive electrode materials are synthesized by a chemical method, and the cost is high, in comparison. The IQDs@RGO film has a significant cost advantage as a positive electrode material for sodium ion batteries (SIB).

1. The RGO in the IQDs@RGO film of the present invention has a porous structure and can provide a conductive network. IQDs can smoothly embed Na+ ions and shorten the Na+ diffusion transport distance. At high current density, the positive electrode material does not cause irreversible changes. Moreover, graphene has strong adsorption, can inhibit the dissolution of iodine, and achieve high utilization of the electrode material, so that the sodium ion (SIB) battery has excellent cycle stability and has an extremely long life.

2. Compared with other conventional electrode materials for sodium ion batteries (SIB), the present invention has good flexibility, and can not maintain fracture even under strong bending conditions, and can maintain structural integrity. The material can be directly applied to the positive electrode material of sodium ion battery (SIB) or flexible sodium ion battery (SIB) without binder and conductive agent.

3. The sodium ion battery (SIB) prepared by the invention exhibits excellent electrochemical performance, high capacity, excellent cycle stability and good rate performance.

DRAWINGS

The accompanying drawings, which are incorporated in the claims In the drawing:

1 is a flow chart of a method for preparing a positive electrode material for a sodium ion battery according to the present invention;

2 is a schematic diagram of a process of synthesizing IQDs provided by the present invention.

Figure 3 is a cyclic voltammogram of the IQDs@RGO cathode material.

Figure 4 is a graph showing the relationship between the thickness of the IQDs@RGO positive electrode and the battery capacity.

Figure 5 shows the capacity performance of pure RGO at different current densities.

detailed description

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example

Referring to Figure 1, a method of preparing a positive electrode material for a sodium ion battery, the method comprising the steps of:

S101, preparing an anhydrous ethanol suspension of GO, dissolving 50 mg of GO in 40 mL of absolute ethanol, and ultrasonically shaking for 2 hours to obtain a suspension of anhydrous ethanol of GO;

S102, preparing a suspension of GO/iodine, dissolving 0.5 g of iodine in the GO/anhydrous ethanol suspension, and after all the iodine is dissolved, obtaining a uniform suspension; then pouring 30 mL of deionized water (DIW) into the solution The suspension obtained above, the above anhydrous ethanol / DIW suspension containing GO and iodine was continuously stirred for 12 h;

S103. Vacuum-filtering the suspension of GO/iodine, and vacuum-filtering the obtained suspension with a filter. The filter is made of PVDF material, and the filter gives a certain positive pressure during the filtration process to form an iodine quantum dot composite. Graphene oxide (IQDs@GO) film;

S104, the IQDs@GO film is washed and dried, and the IQDs@GO film is first washed with deionized water, then freeze-dried overnight, and then peeled off from the filter;

S105. Acid-treating the IQDs@GO film after washing and drying, and immersing the obtained IQDs@GO film in a 55% HI acid solution, wherein the IQDs@GO film is chemically reduced to obtain IQDs@RGO without support. film;

S106. The IQDs@RGO film is washed and dried, and the IQDs@RGO film is washed with deionized water, and then dried in a vacuum oven at 60 ° C for 24 hours.

As shown in Fig. 2, the synthesis process of the IQDs@RGO film is shown in the figure. The volume ratio of the mixture in the bottle from left to right in the order of alcohol and deionized water is 1:0, 4:3 and 1:2, respectively. Soluble in the mixture. Obviously, no GO was added to the mixture, so the IQDs precipitate was clearly visible and the mixture appeared black. The material is prepared by a two-step process by concentration gradient principle. The iodine is first dissolved in an anhydrous ethanol suspension of graphene oxide, and the suspension is diluted with deionized water to make the solubility of iodine in deionized water lower. Promote iodine crystallization. When the volume ratio of ethanol to deionized water is 4:3, iodine molecules are combined to form iodine quantum dots (IQDs). When vacuum filtration, IQDs are adsorbed on GO nanosheets to form IQDs@RGO film. The material has simple preparation process and low cost, and has great cost advantage as a positive electrode material for sodium ion battery (SIB). Among them, RGO has a porous structure and can provide a conductive network, and IQDs can be smoothly embedded. Into Na+ ions, and shortening the Na+ diffusion transport distance, the positive electrode material does not cause irreversible changes at high current density. In addition, graphene has strong adsorption, can inhibit the dissolution of iodine, and achieve high utilization of electrode materials. The material has good flexibility, can not be broken even under strong bending conditions, can maintain the structural integrity, in addition, the material can be directly applied to sodium ion battery (SIB) without binder and conductive agent. Or a positive electrode material for a flexible sodium ion battery (SIB).

Referring to Figures 3 to 5, the sodium ion battery (SIB) prepared by the present invention exhibits excellent electrochemical performance, high capacity, excellent cycle stability, and good rate performance. As shown in Fig. 3, it is the cyclic voltammogram of the IQDs@RGO cathode material. It can be seen from the figure that the reversible performance of IQDs@RGO is good during the sodium-de-sodium filling process; as shown in Fig. 4, it is IQDs@RGO. The relationship between the thickness of the positive electrode and the battery capacity can be seen from the figure. The effect of thickness variation on the battery capacity is very small and negligible; Figure 5 shows the capacity performance of pure RGO at different current densities.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

A method for preparing a cathode material for a sodium ion battery, characterized in that the method comprises the steps of: preparing a suspension of anhydrous ethanol of GO;

Preparing a suspension of GO/iodine by adding iodine to the anhydrous ethanol suspension of GO;

The GO/iodine suspension is subjected to vacuum filtration treatment to form an iodine quantum dot composite graphene oxide (IQDs@GO) film;

Washing and drying the IQDs@GO film;

The IQDs@GO film after water washing and drying treatment is subjected to acid treatment, and chemical reduction is performed to obtain a reduced graphene oxide (IQDs@RGO) film modified without supporting iodine quantum dots;

The IQDs@RGO film is washed and dried.
The method for preparing a positive electrode material for a sodium ion battery according to claim 1, wherein the anhydrous ethanol suspension of the GO is prepared by dissolving 50 mg of GO in 40 mL of absolute ethanol and ultrasonically shaking for 2 hours.
The method for preparing a positive electrode material for a sodium ion battery according to claim 1, wherein the suspension of the GO/iodine is prepared by dissolving 0.5 g of iodine in an anhydrous ethanol suspension of the GO. After all the iodine was dissolved, a uniform suspension was obtained, and then 30 mL of deionized water (DIW) was poured into the suspension obtained above, and the above anhydrous ethanol/DIW suspension containing GO and iodine was continuously stirred for 12 hours.
The method for preparing a positive electrode material for a sodium ion battery according to claim 1, wherein the vacuum filtration treatment is a vacuum filtration of a suspension of GO/iodine by a filter, the filter is a PVDF material, and the filter is filtered. The filter gives a certain positive pressure during the process.
The method for preparing a positive electrode material for a sodium ion battery according to claim 1, wherein the water washing and drying process is to first wash the IQDs@GO film with deionized water, then freeze-dry overnight, and then from the filter. Stripped down.
The method for preparing a cathode material for a sodium ion battery according to claim 1, wherein the acid treatment is performed by immersing the obtained IQDs@GO film in a 55% HI acid solution, and the IQDs@GO film is chemically. The reduction results in an IQDs@RGO film that does not require support.
The method for preparing a positive electrode material for a sodium ion battery according to claim 1, wherein the water washing and drying process is to clean the IQDs@RGO film with deionized water, and then dry it in a vacuum drying oven at 60 ° C. 24h.