Disclosure of Invention
The invention aims to solve the technical problems that the existing carbon fluoride anode active material for the lithium-carbon fluoride battery is difficult to give consideration to high specific capacity and high rate performance and improve voltage hysteresis, and provides a carbon fluoride composite anode active material for the lithium-carbon fluoride battery and a preparation method and application thereof.
In order to solve the technical problems, the technical solution provided by the invention is as follows:
the invention provides a carbon fluoride composite positive active material for a lithium-carbon fluoride battery, which is characterized in that:
is prepared by ball milling and mixing carbon fluoride and Ketjen black.
Further, the mixing mass ratio of the carbon fluoride to the ketjen black is 1: 0.01-1: 0.1.
The invention also provides application of the carbon fluoride composite positive electrode active material for the lithium-carbon fluoride battery in a positive electrode material of the lithium-carbon fluoride battery.
The invention also provides a preparation method of the carbon fluoride composite positive active material for the lithium-carbon fluoride battery, which is characterized by comprising the following steps of:
1) preparing carbon fluoride by adopting a gas phase fluorination method;
2) and (3) ball-milling and mixing the carbon fluoride and the Ketjen black to obtain the uniformly mixed carbon fluoride composite material mixed with the Ketjen black.
Further, in the step 2), the mixing mass ratio of the carbon fluoride to the ketjen black is 1: 0.01-1: 0.1;
the ball milling time is 8-48 h;
the rotating speed of the ball mill is 50-400 r/min during ball milling.
Further, 1.1) placing the graphitized carbon raw material in a closed container, and introducing a fluorination reagent into the closed container;
1.2) keeping the pressure in the closed container at 100 Kpa-300 Kpa, and heating and reacting for 5 h-12 h at the temperature of 300-600 ℃;
1.3) after the reaction is finished, taking out the product and drying the product in vacuum after the temperature in the closed container is reduced to room temperature to obtain the carbon fluoride.
Further, in the step 1.1), the graphitized carbon raw material is graphite or mesoporous carbon;
the fluoridizing reagent is fluoride gas or mixed gas of fluoride and diluent gas, and the volume fraction of the fluoride in the mixed gas is more than or equal to 60 percent;
the diluent gas is one or a mixture of nitrogen, argon, helium and carbon tetrafluoride.
Further, in the step 1.2), the material of the heated part of the closed container is pure nickel or monel, and the material of the rest parts is stainless steel.
Further, in the step 1.1), the volume fraction of the fluoride is 80-100%;
in the step 1.2), the pressure in the closed container is 100 Kpa-200 Kpa, the temperature is 400-600 ℃, and the heating reaction time is 8-12 h;
in the step 2), the mixing mass ratio of the carbon fluoride to the ketjen black is 1: 0.01-1: 0.05; the ball milling time is 12-48 h; the rotating speed of the ball mill is 100-300 r/min during ball milling.
Compared with the prior art, the invention has the following beneficial effects:
1. the carbon fluoride composite positive active material for the lithium-carbon fluoride battery and the preparation method and application thereof provided by the invention have the advantages that the carbon fluoride with higher specific capacity is prepared by a gas phase fluorination method, meanwhile, the carbon fluoride and the ketjen black are mixed by a ball milling mode in combination with the ketjen black with high conductivity for advantage complementation, so that the battery rate capability of the lithium-carbon fluoride battery is improved while the higher specific capacity is kept, the discharge rate of the carbon fluoride mixed by ball milling and the ketjen black reaches 6C, and in the discharge process, the internal resistance is reduced, the polarization phenomenon is reduced, and the voltage hysteresis phenomenon of the lithium-carbon fluoride battery at the initial discharge stage is improved.
2. The carbon fluoride composite positive active material for the lithium-carbon fluoride battery, the preparation method and the application thereof provided by the invention have the advantages that the graphitized carbon material is adopted, the carbon fluoride with higher specific capacity is prepared by a gas phase fluorination method, and compared with the carbon nano material adopted in the prior art, the graphitized carbon material has low production cost and is convenient for industrial production and large-scale market popularization.
3. According to the carbon fluoride composite positive electrode active material for the lithium-carbon fluoride battery, the existing Ketjen black is adopted, the Ketjen black is carbon black prepared by a special production process, and compared with common conductive carbon black, the Ketjen black can achieve high conductivity only by extremely low addition amount.
Detailed Description
The invention is further described below with reference to the figures and examples.
Example 1
1.1) placing 10.0g of pretreated graphite powder in a closed container, and introducing a fluorination reagent into the closed container, wherein the fluorination reagent is 100% NF3A gas; the material of the heated part of the closed container is pure nickel, and the material of the rest parts is stainless steel;
1.2) keeping the pressure in the closed container at 120Kpa and 500 ℃, and heating and reacting for 8 h;
1.3) after the reaction is finished, taking out a product when the temperature in the closed container is reduced to room temperature, and carrying out vacuum drying on the product at 200 ℃ for 6 hours to obtain carbon fluoride;
2) putting the carbon fluoride and the Ketjen black into a ball milling tank according to the mixing mass ratio of 1:0.02 for ball milling and mixing, wherein the ball milling time is 24 hours, and the rotating speed of the ball mill is 100 r/min, so as to obtain the uniformly mixed carbon fluoride composite material mixed with the Ketjen black.
Example 2
1.1) placing 10.0g of pretreated graphite powder in a closed container, and introducing a fluorination reagent into the closed container, wherein the fluorination reagent is 90% NF3A gas; the material of the heated part of the closed container is pure nickel, and the material of the rest parts is stainless steel;
1.2) keeping the pressure in the closed container at 140Kpa and 500 ℃, and heating and reacting for 10 h;
1.3) after the reaction is finished, taking out a product when the temperature in the closed container is reduced to room temperature, and carrying out vacuum drying on the product at 200 ℃ for 6 hours to obtain carbon fluoride;
2) putting the carbon fluoride and the Ketjen black into a ball milling tank according to the mixing mass ratio of 1:0.05 for ball milling and mixing, wherein the ball milling time is 12 hours, and the rotating speed of the ball mill is 300 r/min, so as to obtain the uniformly mixed carbon fluoride composite material mixed with the Ketjen black.
Example 3
1.1) placing 10.0g of pretreated graphite powder in a closed container, and introducing a fluorination reagent into the closed container, wherein the fluorination reagent is 80% NF3A gas; the material of the heated part of the closed container is pure nickel, and the material of the rest parts is stainless steel;
1.2) keeping the pressure in the closed container at 140Kpa and 500 ℃, and heating and reacting for 8 h;
1.3) after the reaction is finished, taking out a product when the temperature in the closed container is reduced to room temperature, and carrying out vacuum drying on the product at 200 ℃ for 6 hours to obtain carbon fluoride;
2) putting the carbon fluoride and the Ketjen black into a ball milling tank according to the mixing mass ratio of 1:0.03 for ball milling and mixing, wherein the ball milling time is 24 hours, and the rotating speed of the ball mill is 200 r/min, so as to obtain the uniformly mixed carbon fluoride composite material mixed with the Ketjen black.
Example 4
1.1) placing 10.0g of pretreated mesoporous carbon powder inIntroducing a fluorination reagent into the closed container, wherein the fluorination reagent is 100% NF3A gas; the material of the heated part of the closed container is Monel alloy, and the material of the rest parts is stainless steel;
1.2) keeping the pressure in the closed container at 140Kpa and 550 ℃, and heating and reacting for 10 h;
1.3) after the reaction is finished, taking out a product when the temperature in the closed container is reduced to room temperature, and carrying out vacuum drying on the product at 200 ℃ for 6 hours to obtain carbon fluoride;
2) putting the carbon fluoride and the Ketjen black into a ball milling tank according to the mixing mass ratio of 1:0.02 for ball milling and mixing, wherein the ball milling time is 24 hours, and the rotating speed of the ball mill is 400 r/min, so as to obtain the uniformly mixed carbon fluoride composite material mixed with the Ketjen black.
Example 5
1.1) placing 10.0g of pretreated mesoporous carbon powder in a closed container, and introducing a fluorination reagent into the closed container, wherein the fluorination reagent is 80% NF3A gas; the material of the heated part of the closed container is Monel alloy, and the material of the rest parts is stainless steel;
1.2) keeping the pressure in the closed container at 120Kpa and 500 ℃, and heating and reacting for 10 h;
1.3) after the reaction is finished, taking out a product when the temperature in the closed container is reduced to room temperature, and carrying out vacuum drying on the product at 200 ℃ for 6 hours to obtain carbon fluoride;
2) putting the carbon fluoride and the Ketjen black into a ball milling tank according to the mixing mass ratio of 1:0.05 for ball milling and mixing, wherein the ball milling time is 48 hours, and the rotating speed of the ball mill is 50 r/min, so as to obtain the uniformly mixed carbon fluoride composite material mixed with the Ketjen black.
Example 6
1.1) placing 10.0g of pretreated mesoporous carbon powder in a closed container, and introducing a fluorination reagent into the closed container, wherein the fluorination reagent is 60% NF3A gas; the material of the heated part of the closed container is Monel alloy, and the material of the rest parts is stainless steel;
1.2) keeping the pressure in the closed container at 100Kpa and 300 ℃, and heating and reacting for 5 h;
1.3) after the reaction is finished, taking out a product when the temperature in the closed container is reduced to room temperature, and carrying out vacuum drying on the product at 200 ℃ for 6 hours to obtain carbon fluoride;
2) putting the carbon fluoride and the Ketjen black into a ball milling tank according to the mixing mass ratio of 1:0.01 for ball milling and mixing, wherein the ball milling time is 8 hours, and the rotating speed of the ball mill is 100 r/min, so as to obtain the uniformly mixed carbon fluoride composite material mixed with the Ketjen black.
Example 7
1.1) placing 10.0g of pretreated graphite powder in a closed container, and introducing a fluorination reagent into the closed container, wherein the fluorination reagent is 100% NF3A gas; the material of the heated part of the closed container is pure nickel, and the material of the rest parts is stainless steel;
1.2) keeping the pressure in the closed container at 300Kpa and 600 ℃, and heating and reacting for 12 h;
1.3) after the reaction is finished, taking out a product when the temperature in the closed container is reduced to room temperature, and carrying out vacuum drying on the product at 200 ℃ for 6 hours to obtain carbon fluoride;
2) putting the carbon fluoride and the Ketjen black into a ball milling tank according to the mixing mass ratio of 1:0.1, and carrying out ball milling mixing for 48 hours at the ball milling speed of 300 r/min to obtain the uniformly mixed carbon fluoride composite material mixed with the Ketjen black.
Comparative example
1.1) placing 10.0g of pretreated graphite powder in a closed container, and introducing a fluorination reagent into the closed container, wherein the fluorination reagent is 80% NF3A gas; the material of the heated part of the closed container is pure nickel, and the material of the rest parts is stainless steel;
1.2) keeping the pressure in the closed container at 140Kpa and 500 ℃, and heating and reacting for 8 h;
1.3) after the reaction is finished, taking out the product when the temperature in the closed container is reduced to room temperature, and drying the product in vacuum at 200 ℃ for 6h to obtain the carbon fluoride.
The products of examples 1-5 and comparative example are used as positive active materials of lithium-carbon fluoride batteries to assemble button batteries, and the mass ratio of the working electrode (namely the negative electrode) in bulk phase is 8: 1: 1, a composite anode active material containing carbon fluoride, acetylene black and polyvinylidene fluoride mixed material; the counter electrode (i.e. the positive electrode) is a lithium metal sheet; the electrolyte is a 1M lithium tetrafluoroborate solution dissolved in ethylene carbonate and dimethyl carbonate (volume ratio is 1: 1);
carrying out electrochemical performance test:
1. and (3) testing the electrochemical performance with the discharge cut-off voltage of 1.5V. For example, fig. 1 is a comparison graph of initial discharge voltage hysteresis at 2C discharge rate in electrochemical performance tests of examples 1, 2, and 3 and comparative products, and test results show that the initial discharge voltage hysteresis is significantly improved after the carbon fluoride composite positive electrode active material of the present invention is used; fig. 2 is a graph comparing the discharge curve performance of the products of example 1, example 2, and example 3 with that of the comparative example under the 2C discharge rate in the electrochemical performance test, and the test result shows that the discharge performance is significantly improved after the carbon fluoride composite cathode active material of the present invention is adopted;
2. and (4) testing the electrochemical performance with the discharge multiplying power of 0.01C, 1C, 2C and 6C. For example, fig. 3 is a discharge curve performance diagram of the product of example 1 at discharge rates of 0.01C, 1C, 2C, and 6C in an electrochemical performance test, and a test result shows that after the carbon fluoride composite positive electrode active material of the present invention is adopted, the discharge rate can reach 6C, and compared with the existing carbon fluoride positive electrode active material, the discharge rate is only 1C in a normal state, and it is more reluctant to reach a higher discharge rate, and the discharge rate of the present invention is significantly improved.
Table 1 is a table of the performance of the products of examples 1-5 and comparative example as lithium-fluorocarbon cell positive active materials assembled into button cells at 2C discharge rate and 1.5V cutoff:
sample (I)
|
Discharge rate
|
Cut-off voltage (V)
|
Specific capacity (mAh/g)
|
Specific energy (Wh/kg)
|
Example 1
|
2C
|
1.5
|
737.4
|
1558.3
|
Example 2
|
2C
|
1.5
|
716.8
|
1492.1
|
Example 3
|
2C
|
1.5
|
677.5
|
1433.7
|
Example 4
|
2C
|
1.5
|
744.5
|
1573.4
|
Example 5
|
2C
|
1.5
|
710.9
|
1477.7
|
Comparative example
|
2C
|
1.5
|
642.3
|
1195.8 |
Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same, and it is obvious for a person skilled in the art to modify the specific technical solutions described in the foregoing embodiments or to substitute part of the technical features, and these modifications or substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions protected by the present invention.