CN113270577A

CN113270577A - Aqueous zinc ion battery and positive electrode material

Info

Publication number: CN113270577A
Application number: CN202110523226.XA
Authority: CN
Inventors: 邓雯雯; 王淑婵
Original assignee: Suzhou University of Science and Technology
Current assignee: Suzhou University of Science and Technology
Priority date: 2021-05-13
Filing date: 2021-05-13
Publication date: 2021-08-17
Anticipated expiration: 2041-05-13
Also published as: CN113270577B

Abstract

The invention discloses a water-based zinc ion battery and a positive electrode material, wherein the positive electrode material is a compound of tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane. The composite (TTF-TCNQ) of tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane is creatively prepared to be used as the positive electrode active material of the water-based zinc ion battery, so that the water-based zinc ion battery has good cycle performance and high specific capacity.

Description

Aqueous zinc ion battery and positive electrode material

Technical Field

The invention belongs to the technical field of new energy materials, and particularly relates to a water-based zinc ion battery and a positive electrode material.

Background

Currently, lithium ion batteries occupy a large portion of the market with their high energy density and long cycle life. However, in recent years, the high cost and safety of lithium ion batteries have been attracting attention. Therefore, the development of an electrochemical energy storage device to replace lithium ion batteries has become a hot spot of current research. The zinc metal has low cost and specific gravimetric capacity (820 mAhg) ^-1 ) Specific volume capacity (5855 mAhcm) ^-3 ) The cathode material has the advantages of proper potential (-0.76V), high conductivity, low toxicity and the like, and is an ideal cathode material. The aqueous electrolyte has ion conductivity as compared with the organic electrolyteHigh efficiency, high power density, simple production condition, low cost and the like. Therefore, aqueous batteries are considered to be a promising alternative. Under the efforts of researchers at home and abroad, the water-based battery has made many breakthroughs in recent years, especially the water-based zinc-based battery. The alkaline electrolyte is easy to generate zinc dendrite, passivate and corrode, and generate hydrogen evolution reaction. Therefore, an aqueous zinc ion battery using a neutral or weakly acidic aqueous electrolyte solution has been receiving attention from many researchers.

However, research on the cathode material of the water-based zinc ion battery mainly focuses on inorganic materials, mainly zinc-manganese batteries, zinc-nickel batteries and prussian blue analogues as cathode materials. They have extensive and cross Zn ²⁺ Migration pathway showing attractive properties. However, inorganic materials also have significant drawbacks, such as manganese dioxide undergoing significant phase changes during cycling (e.g., from an initial α -, β -, or γ -phase to a layered structure and subsequent structural collapse), resulting in very poor stability at high charge and discharge current densities, mn ²⁺ Dissolved in the electrolyte and irreversibly structurally transformed to have a low cycle life. The toxicity and cost of vanadium-based cathodes have hindered their further use in large-scale electrolytic processing. In addition, due to Zn ²⁺ Diffusion in a solid inorganic framework is slow and the capacity of the inorganic electrode material is limited, making it difficult to make a breakthrough in inorganic electrode materials. Compared with inorganic electrode materials, the application of organic electrode materials or inorganic-organic hybrid materials can obtain better electrochemical benefits and effectively promote the development of secondary batteries. And the organic molecular material enables the molecular reorientation to meet the requirement of soluble ions due to the inherent ductility and soft crystal lattice, thereby arousing the attention of people on the storage of divalent cations. Intercalation and weak intermolecular van der waals forces mask coulomb repulsion to slow solid state diffusion, resulting in high specific capacity, structural diversity and economy. These characteristics make organic molecules a sustainable alternative to traditional inorganic electrode materials.

Disclosure of Invention

In view of the above, an object of the present invention is to provide an aqueous zinc ion battery and a positive electrode material, which can increase the conductivity of an organic active material and provide the aqueous zinc ion battery with good cycle performance and high specific capacity.

In order to achieve the purpose, the invention provides the following technical scheme:

the invention discloses a water-based zinc ion battery anode material, which is a compound of tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane; the tetrathiafulvalene is a compound shown in a formula I, and the 7,7,8,8-tetracyanoquinodimethane is a compound shown in a formula II;

preferably, the mass ratio of the tetrathiafulvalene to the 7,7,8,8-tetracyanoquinodimethane is 1-5:1-5.

The invention also discloses a preparation method of the water system zinc ion battery anode material, which comprises the steps of fully dissolving tetrathiafulvalene in an organic solvent and then grinding; fully dissolving 7,7,8,8-tetracyanoquinodimethane in an organic solvent, and grinding; mixing the fully ground tetrathiafulvalene with 7,7,8,8-tetracyanoquinodimethane, and fully grinding; and (4) carrying out suction filtration and drying to obtain the compound of tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane.

The invention also discloses a water-based zinc ion battery, which comprises a positive electrode, a negative electrode, a diaphragm and electrolyte, wherein the active material of the positive electrode is a compound of tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane;

the tetrathiafulvalene is a compound shown in a formula I, and the 7,7,8,8-tetracyanoquinodimethane is a compound shown in a formula II;

Preferably, the positive electrode further includes a conductive agent and a binder.

As a preferable technical scheme, the negative electrode is one of a zinc sheet, a zinc foil and a zinc alloy.

As a preferred technical solution, the electrolyte comprises water and a soluble zinc salt.

The invention has the beneficial effects that:

the invention creatively prepares a compound (TTF-TCNQ) of tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane as a positive active material of a water-based zinc ion battery; the TTF charge transfer compound has very high conductivity (0.25S cm) ^-1 ). Orange TTF molecules have good plane conjugated systems; TCNQ is an organic semiconductor, and has very stable performance and low cost; the research of the invention finds that the cooperation of TTF and TCNQ can greatly enhance the conductivity of the TTF and TCNQ, particularly the TTF-TCNQ compound can suddenly increase the conductivity below room temperature and can reach 10 at 55K ^-4 S cm ^-1 。

Experiments prove that after the TTF-TCNQ composite is applied to a water system zinc ion battery, the water system zinc ion battery has good cycle performance and higher specific capacity.

Drawings

In order to make the object, technical scheme and beneficial effect of the invention more clear, the invention provides the following drawings for explanation:

FIG. 1 shows that the temperature is 0.05A g ^-1 A charge-discharge curve of the aqueous zinc-ion battery of example 1 at 25 ℃;

FIG. 2 shows a value of 0.05A g ^-1 A charge-discharge curve of the aqueous zinc ion battery of example 2 at 25 ℃;

FIG. 3 shows that the temperature is 0.05A g ^-1 Charge/discharge curves of the aqueous zinc ion battery of example 3 at 25 ℃Line drawing;

FIG. 4 shows the optical axis at 0.05A g ^-1 A charge-discharge curve of the aqueous zinc-ion battery of example 1 at 0 ℃;

FIG. 5 shows the optical axis at 0.05A g ^-1 A cycle performance chart of the aqueous zinc-ion battery of example 1 at 0 ℃;

FIG. 6 shows that the optical axis is at 0.05A g ^-1 A charge-discharge curve of the aqueous zinc ion battery of example 2 at 0 ℃;

FIG. 7 is a graph showing a cross-sectional area at 0.05A g ^-1 A cycle performance chart of the aqueous zinc ion battery of example 2 at 0 ℃;

FIG. 8 shows the optical axis at 0.05A g ^-1 A charge-discharge curve of the aqueous zinc-ion battery of example 3 at 0 ℃;

FIG. 9 is a graph of the value at 0.05A g ^-1 A cycle performance chart of the aqueous zinc ion battery of example 3 at 0 ℃;

FIG. 10 is a current-voltage (I-V) curve of the TTF-TCNQ complex of example 1.

Detailed Description

The present invention is further described with reference to the following drawings and specific examples so that those skilled in the art can better understand the present invention and can practice the present invention, but the examples are not intended to limit the present invention.

In the following examples and comparative examples, all starting materials were either commercially available or obtained by conventional methods in the art, unless otherwise specified.

The negative electrode is commercial zinc foil which is polished smooth by abrasive paper, and the diaphragm is a purchased glass fiber diaphragm.

Tetrathiafulvalene is a commercial product and has a structural formula as follows:

7,7,8,8-tetracyanoquinodimethane is a commercial product, and the structural formula of the product is as follows:

example 1

1. Preparation of TTF-TCNQ Complex:

weighing TTF and TCNQ according to the mass ratio of 1:1; respectively pouring the weighed TTF and TCNQ into different mortars, respectively dissolving the TTF and the TCNQ with proper amount of acetonitrile, fully grinding the TTF and the TCNQ by using the mortars, mixing the fully ground TTF and the fully ground TCNQ together, and fully grinding the TTF and the TCNQ; and (4) carrying out suction filtration by using a vacuum filtration device, and after the suction filtration is finished, drying the material on the filter paper in a vacuum drying oven at the temperature of 60 ℃ for 720min.

2. Preparation of positive electrode (TTF-TCNQ: SP: PTFE =6:

weighing 30mg of TTF-TCNQ, and pouring into a mortar; then 15mg of SP (conductive carbon black) was weighed out, poured into a mortar, mixed with TTF-TCNQ using a mortar pestle, ground for about 20min, 60% PTFE to about 8.33mg was added to the mortar using a 10. Mu.l pipette, and the ground powder was covered substantially completely with isopropanol using a 100. Mu.l pipette; pressing the material with a flat portion of a small key; then rolling the mixture into slices; and finally, drying in a vacuum drying oven at 60 ℃ for 720min.

3. Electrolyte preparation (3M zinc chloride):

taking 1mL as an example, firstly, the used small-volume bottle is cleaned and dried, 408mg of zinc chloride is weighed and placed into the small-volume bottle, 1mL of deionized water is taken by a 1mL pipette and poured into the small-volume bottle, and the ultrasonic treatment is carried out to obtain the zinc chloride.

4. Preparing a water-based zinc ion battery:

a 2032 battery case is selected and assembled in the order of negative electrode case, negative electrode (polished zinc sheet), glass fiber diaphragm, electrolyte (5 drops of electrolyte are transferred by a 10 microliter liquid transfer gun and added into the middle of the diaphragm), positive electrode and positive electrode case.

Example 2

Example 2 differs from example 1 in that: TTF and TCNQ were weighed in a mass ratio of 5:1.

Example 3

Example 3 differs from example 1 in that: TTF and TCNQ were weighed in a mass ratio of 1:5.

At 0.05A g ^-1 The results of the charge and discharge tests performed on the aqueous zinc ion batteries of examples 1 to 3 at 25 ℃ are shown in fig. 1 to 3, and the results show that: the aqueous zinc ion batteries of examples 1 to 3 all had a higher specific capacity at room temperature.

At 0.05A g ^-1 The charge and discharge test and the cycle performance test were performed on the aqueous zinc ion batteries of examples 1 to 3 at 0 ℃, respectively, and the results are shown in fig. 4 to 9, which indicate that:

the aqueous zinc-ion battery of example 1 had good cycle performance and a high specific capacity at low temperature of 0 ℃.

The cycle performance and specific capacity of the aqueous zinc ion batteries of examples 2 and 3 were inferior to those of example 1 under the low temperature condition of 0 ℃.

The electronic conductance of TTF-TCNQ was calculated to be 1.9 x 10 according to the I-V curve of fig. 10 ^-4 S cm ^-1 Belonging to organic semiconductors.

The above-mentioned embodiments are merely preferred embodiments for fully illustrating the present invention, and the scope of the present invention is not limited thereto. The equivalent substitution or change made by the technical personnel in the technical field on the basis of the invention is all within the protection scope of the invention. The protection scope of the invention is subject to the claims.

Claims

1. A positive electrode material for a water-based zinc-ion battery, characterized in that: the anode material is a compound of tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane; the tetrathiafulvalene is a compound shown in a formula I, and the 7,7,8,8-tetracyanoquinodimethane is a compound shown in a formula II;

2. the aqueous zinc-ion battery positive electrode material according to claim 1, characterized in that: the mass ratio of the tetrathiafulvalene to the 7,7,8,8-tetracyanoquinodimethane is 1-5:1-5.

3. The method for producing a positive electrode material for an aqueous zinc-ion battery according to claim 1 or 2, characterized in that: fully dissolving tetrathiafulvalene in an organic solvent, and grinding; fully dissolving 7,7,8,8-tetracyanoquinodimethane in an organic solvent, and grinding; mixing the fully ground tetrathiafulvalene with 7,7,8,8-tetracyanoquinodimethane, and fully grinding; and (4) carrying out suction filtration and drying to obtain the compound of tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane.

4. An aqueous zinc-ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte solution, characterized in that: the active material of the positive electrode is a compound of tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane;

5. the aqueous zinc-ion battery according to claim 4, characterized in that: the mass ratio of the tetrathiafulvalene to the 7,7,8,8-tetracyanoquinodimethane is 1-5:1-5.

6. The aqueous zinc-ion battery according to claim 4, characterized in that: the positive electrode further includes a conductive agent and a binder.

7. The aqueous zinc-ion battery according to claim 4, characterized in that: the negative electrode is one of a zinc sheet, a zinc foil and a zinc alloy.

8. The aqueous zinc-ion battery according to claim 4, characterized in that: the electrolyte includes water and a soluble zinc salt.