CN102903921B - A kind of take fluorocarbons as the water system battery of positive pole - Google Patents

Abstract

The invention discloses an aqueous battery with carbon fluoride as the positive electrode, relating to an aqueous battery. A positive electrode, a negative electrode and an electrolyte system are provided. The positive electrode uses a material containing fluorinated carbon as an active material, the negative electrode uses a metal or a modified or doped product of the metal, and the electrolyte system uses water as the main solvent. Electrolyte system, the diaphragm of the battery adopts a hydrophilic diaphragm. Using an electrolyte system with water as a solvent, using fluorinated carbon materials as the positive electrode active material of the battery, and using metal materials as the negative electrode of the battery, it has the characteristics of high discharge capacity, good rate performance, and good safety.

Description

An aqueous battery with carbon fluoride as the positive electrode

technical field

The invention relates to an aqueous battery, in particular to an aqueous battery with carbon fluoride as the positive electrode.

Background technique

Energy is the material basis for social and economic development. With the rapid development of my country's national economy, the demand for energy is growing rapidly. The energy problem has been paid more and more attention by people. The long-term fossil energy problem has restricted the sustainable development of the world and become the bottleneck of sustainable economic development. The research and development of new batteries and the development of new energy sources are the urgent requirements of today's energy age. Therefore, the research and development of new batteries and their key materials with high specific energy, high power and high safety has become the consensus of all countries in the world.

Solid fluorinated carbon materials are graphite intercalation compounds produced by the direct reaction of fluorine and carbon, and have a series of unique physical and chemical properties such as low surface energy and interlayer energy and high electrical activity. In the late 1960s, it was found that the interlayer energy of graphite fluoride was much smaller than that of graphite, so its solid lubricity was recognized, and it was widely used in solid lubricants. Since then, the research on fluorinated graphite as a solid lubricant and high-energy-density non-aqueous lithium primary battery cathode material has pushed the development and application of fluorinated graphite, a new type of functional material, to a climax, making it more and more widely used.

The application of solid fluorocarbon materials in primary batteries, from the existing literature and commercial product reports, only lithium/fluorocarbon (fluorinated graphite) non-aqueous (organic electrolyte) primary batteries, fluorocarbon theoretical mass specific energy About 2180Wh/kg, which is the highest in the solid positive electrode series, and the working voltage is about 2.5~2.7V. In small lithium primary batteries, the actual specific energy is 250Wh/kg and 635Wh/L; in large lithium primary batteries, its The actual specific energy is 590Wh/kg and 1050Wh/L.

Although Chinese patents CN101927981A, CN101486454A, and CN1887832A disclose several methods for making carbon fluoride materials, they do not involve the implementation of specific batteries. Chinese patent CN102361084A discloses the use of a mixture of fluorinated graphite and fluorinated carbon nanotubes as a lithium battery positive electrode material. This patent only describes its use as a lithium battery positive electrode material and a method for making the positive electrode. It is generally believed that fluorinated carbon (CF _x ) materials are hydrophobic and are not suitable for battery systems using water as a solvent. Therefore, there is no relevant report on metal (Metal)/fluorocarbon (CF _x ) batteries in which the electrolyte is aqueous.

Contents of the invention

The object of the present invention is to provide an aqueous battery using carbon fluoride as the positive electrode.

The invention is provided with a positive electrode, a negative electrode and an electrolyte system. The positive electrode uses a material containing carbon fluoride as an active material, the negative electrode uses a metal or a modified or doped product of the metal, and the electrolyte system uses water as a solvent. The electrolyte system of the main body and the diaphragm of the battery adopt a hydrophilic diaphragm.

The metal can be selected from one of zinc, aluminum, magnesium, lithium and the like.

The fluorinated carbon material can be selected from fluorinated carbon materials with different degrees of fluorination obtained by fluorinating carbon materials such as graphite, petroleum coke, carbon nanotubes, and carbon fibers, or fluorinated carbon materials prepared by other methods. The main body of the fluorinated carbon material is (CF _x ) _n , where x=0.1-1.1; in the active material, the content of the fluorinated carbon can be 20%-100% by mass.

The diaphragm can be a diaphragm prepared mainly from regenerated cellulose, vinyl polymers, and polyolefin compounds, and the diaphragm can also be a liquid-absorbent paper-based diaphragm.

When zinc is used as the negative electrode, alkaline aqueous solution and the like can be used as the electrolyte.

When magnesium or magnesium alloy is used for the negative electrode, the electrolyte solution can be a magnesium salt solution, and the magnesium salt solution can be selected from magnesium perchlorate solution and the like.

When aluminum is used for the negative electrode, the electrolyte can be an aluminum salt solution, and the aluminum salt solution can be selected from aluminum chloride solution or chromium chloride solution.

When lithium is used as the negative electrode, the electrolyte can be composed of lithium salt as the electrolyte and water as the solvent. The lithium salt can be selected from lithium hydroxide or lithium chloride, etc.; the separator can be regenerated fiber Diaphragms made mainly of cellulose, vinyl polymers, and polyolefin compounds, or liquid-absorbent paper-based diaphragms, or PP diaphragms, PE diaphragms, and PP/PE/PP composite films that have undergone hydrophilic treatment.

The present invention uses commercial fluorinated carbons, including fluorinated graphite, fluorinated carbon fibers, fluorinated carbon nanotubes, fluorinated petroleum coke, etc., as the main body of the metal (Metal)/fluorocarbon (CF _x ) water-based battery Active material; metal zinc, metal magnesium, metal aluminum, or specially treated metal lithium as the negative electrode; and the corresponding water system electrolyte and diaphragm to form the primary battery system.

Using the fluorinated carbon material positive electrode material in the water system battery of the present invention, the specific capacity can reach more than 500mAh/g when the current is discharged at 800mA/g. The battery system produced by the invention has the characteristics of high discharge capacity, good rate performance and good battery safety.

Since the metal (Metal)/carbon fluoride (CF _x ) battery of the present invention adopts an electrolyte system with water as a solvent, carbon fluoride material is used as the positive electrode active material of the battery, and metal materials (including metal zinc, metal aluminum, Metal magnesium, metal lithium, etc.) are used as the negative electrode of the battery, so the battery system of the present invention has the characteristics of high discharge capacity, good rate performance, and good safety.

Description of drawings

Fig. 1 is that the present invention adopts fluorinated carbon fiber as positive electrode material, 1mol/L LiOH aqueous solution is used as electrolyte, adopts the current step method to continuously test the discharge curve of fluorinated carbon fiber positive electrode material. In Fig. 1, the abscissa is the test time Testtime/s, and the ordinate is the potential Potential/V (vs Zn ²⁺ /Zn).

Fig. 2 is the discharge curve at the current density of 100mAh/cm ² using fluorinated carbon fiber as the positive electrode material and 1mol/L LiOH aqueous solution as the electrolyte in the present invention. In Fig. 2, the abscissa is Specific capacity/mAh g ^-1 , and the ordinate is Potential/V (vs Zn ²⁺ /Zn).

Fig. 3 is a graph showing discharge curves at different current densities using fluorinated carbon fiber as the positive electrode material and 1mol/L LiOH aqueous solution as the electrolyte in the present invention. In FIG. 3 , the abscissa is Specific capacity/mAh g ^-1 , and the ordinate is Potential/V (vs Li ⁺ /Li).

Figure 4 is the discharge curves of the present invention using fluorinated carbon nanotubes as the positive electrode material and 1mol/L LiOH aqueous solution as the electrolyte at different current densities (the ordinate uses Zn ²⁺ /Zn as the relative electrode potential). In Fig. 4, the abscissa is Specific capacity/mAh g ^-1 , and the ordinate is Potential/V (vs Zn ²⁺ /Zn).

Fig. 5 is a graph of discharge curves at different current densities using fluorinated carbon nanotubes as the positive electrode material and 1mol/L LiOH aqueous solution as the electrolyte in the present invention (the ordinate uses Li ⁺ /Li as the relative electrode potential). In FIG. 5 , the abscissa is Specific capacity/mAh g ^-1 , and the ordinate is Potential/V (vs Li ⁺ /Li).

FIG. 6 shows a schematic structural diagram of an aqueous battery using carbon fluoride as the positive electrode active material according to the present invention. In FIG. 6 , each mark is: 1—positive electrode; 2—positive active material; 3—battery shell; 4—electrolyte; 5—diaphragm; 6—negative active material; 7—negative electrode.

Detailed ways

The present invention will be further described below in conjunction with embodiment.

Example 1

The electrochemical performance of the carbon fluoride material of the metal (Metal)/carbon fluoride (CF _x ) aqueous battery of the present invention was tested by using a three-electrode system. Nickel foam is used as the counter electrode (negative electrode), zinc foil is used as the reference electrode, the research electrode (positive electrode) is made of fluorinated carbon fiber CF _x , and the material ratio to the conductive agent and binder: 80:10:10 (mass ratio) , the current collector is nickel foam, and the electrode is prepared by the slurry method, vacuum-dried at 120 ° C, and pressed at 10 MPa. The electrode area is 1 cm×1 cm, and the thickness is 160 μm. Electrolyte: 1mol/L LiOH.

The current step method is used for continuous testing. Test and study the OCP (open circuit potential) of the electrode under high temperature conditions (electrode temperature 65~70°C), test for 30s; discharge with a current of 40mA/cm ² for 90s; discharge with a current of 60mA/cm ² for 90s; then discharge with a current of 80mA/cm ² Current discharge for 90s; then 100mA/cm ² current discharge for 90s; test the voltage change during constant current discharge. The test results are shown in Figure 1. The measured open circuit voltage was 1.48V. Experiments prove that the battery system has high power performance.

Example 2

Using the same electrode material as in Example 1, the research electrode was fabricated in the same way. A three-electrode system (nickel foam as the counter electrode, zinc foil as the reference electrode), electrolyte: 1mol/L LiOH. Discharge was performed at a current of 100 mAh/cm ² . The high-current discharge performance of the metal (Metal)/fluorocarbon (CF _x ) aqueous battery was tested, and the results are shown in FIG. 2 .

Example 3

Using the same electrode material as in Example 1, multiple research electrodes were fabricated in the same way. A three-electrode system (nickel foam as the counter electrode, zinc foil as the reference electrode), electrolyte: 1mol/L LiOH. Discharge at different currents of 800mAh/g, 4000mA/g, and 8000mA/g to study the discharge performance of metal (Metal)/fluorocarbon (CF _x ) aqueous batteries. The results are shown in Figure 3, the ordinate in the figure is Li ⁺ /Li as the relative electrode potential, indicating that the positive electrode material of the present invention can be used in an aqueous battery system with protected metal lithium as the negative electrode. The results show that the battery manufactured by the method of the invention can achieve very high specific capacity under the condition of large current discharge.

Example 4

Using fluorinated carbon nanotubes CFx ( _x =0.8~0.9) as the positive electrode material, the same method as in Example 1 was used to fabricate research electrodes. Two-electrode system (metal zinc sheet as the negative electrode), electrolyte: 1mol/L LiOH. Discharge at currents of 80mAh/g, 800mA/g, and 4000mA/g to study the discharge performance of metal (Metal)/fluorocarbon (CF _x ) aqueous batteries. The results show (as shown in FIG. 4 ), the battery manufactured by the method of the present invention can achieve a very high specific capacity under the condition of high current discharge. Fig. 5 is the discharge curve of the same electrode, and the ordinate is Li ⁺ /Li as the relative electrode potential, indicating that the positive electrode material of the present invention can be used in an aqueous battery system with protected metal lithium as the negative electrode.

Example 5

Using fluorinated carbon material as the main active material of the positive electrode, the positive electrode is made in the same way as in Example 1, the negative electrode is zinc paste (Zn content greater than 50%), the electrolyte: 35%~60% KOH aqueous solution, and the diaphragm material is regenerated fiber Separators based on cellulose, vinyl polymers, and polyolefin compounds. Metal zinc (Zn)/carbon fluoride (CF _x ) aqueous batteries were fabricated according to the battery structure shown in Figure 6 . In FIG. 6 , each mark is: 1—positive electrode; 2—positive active material; 3—battery shell; 4—electrolyte; 5—diaphragm; 6—negative active material; 7—negative electrode.

Example 6

Using fluorinated carbon material as the main active material of the positive electrode, the positive electrode is made in the same way as in Example 1, and the negative electrode is a magnesium alloy based on high-purity magnesium (magnesium content is greater than 50%), electrolyte: perchloric acid containing lithium chromate Magnesium aqueous solution, the diaphragm material is methyl fiber and carboxymethyl fiber in equal weight ratio. Metal magnesium (Mg)/carbon fluoride (CF _x ) aqueous batteries were fabricated according to the battery structure shown in FIG. 6 .

Example 7

Using fluorinated carbon material as the main active material of the positive electrode, the positive electrode is made in the same way as in Example 1, the negative electrode is an aluminum alloy with high-purity aluminum as the matrix (the aluminum content is greater than 50%), the electrolyte is an aqueous aluminum chloride solution, and the diaphragm material is Separators made mainly of regenerated cellulose, vinyl polymers, and polyolefin compounds. Metal aluminum (Al)/fluorocarbon (CF _x ) aqueous batteries were fabricated according to the battery structure shown in FIG. 6 .

Example 8

Using fluorinated carbon material as the main active material of the positive electrode, the positive electrode was made in the same way as in Example 1, the negative electrode was specially treated metal lithium, the electrolyte was lithium hydroxide aqueous solution, and the diaphragm was PP diaphragm after hydrophilic treatment. The battery structure given in 6 is used to make lithium metal (Li)/carbon fluoride (CF _x ) aqueous battery.

Claims (5)

1. one kind take fluorocarbons as the water system battery of positive pole, it is characterized in that being provided with positive pole, negative pole and electrolyte system, described positive pole adopts containing fluorinated carbon material as active material, described negative pole adopts the one in described negative pole employing aluminium, magnesium, magnesium alloy, described electrolyte system employing take water as the electrolyte system of solvent main body, and the barrier film of battery adopts hydrophily barrier film;

Described fluorinated carbon material is selected from the fluorinated carbon material that material with carbon element obtains after fluoridizing;

The main body of described fluorinated carbon material is (CF _x) _n, x=0.1 ~ 1.1;

In described active material, the content of fluorocarbons is 20% ~ 100% by mass percentage;

When described negative pole adopts magnesium or magnesium alloy, described electrolyte adopts magnesium salt solution, and described magnesium salt solution is selected from the magnesium perchlorate aqueous solution.

2. a kind of as claimed in claim 1 take fluorocarbons as the water system battery of positive pole, it is characterized in that described material with carbon element is selected from the one in graphite, petroleum coke, carbon nano-tube, carbon fiber.

3. a kind of as claimed in claim 1 take fluorocarbons as the water system battery of positive pole, it is characterized in that described barrier film adopts regenerated cellulose, polyvinyl, TPO compound to be barrier film prepared by main body, or adopts the paper substrate barrier film of absorbency.

4. a kind of as claimed in claim 1 take fluorocarbons as the water system battery of positive pole, it is characterized in that described electrolyte adopts liquor alumini chloridi or chromium chloride solution when described negative pole adopts aluminium.

5. a kind of as claimed in claim 1 take fluorocarbons as the water system battery of positive pole, it is characterized in that described barrier film adopts regenerated cellulose, polyvinyl, TPO compound to be barrier film prepared by main body, or the paper substrate barrier film of absorbency, or through PP barrier film, PE barrier film, the PP/PE/PP composite membrane of hydrophilic treated.