A wide-temperature-range lithium / sodium chloride secondary battery positive electrode material and a preparation method thereof

Abstract

The application provides a wide-temperature-range lithium / sodium chlorine secondary battery positive electrode material and a preparation method thereof. The positive electrode material is a composite of two-dimensional transition metal chalcogen compounds and a catalyst. The two-dimensional transition metal chalcogen compounds include one or more of MoS2, MoSe2, WS2, WSe2, ReS2 and ReSe2. The catalyst includes one or more of a metal, a metal oxide and a metal nitride. The application proposes that the two-dimensional transition metal chalcogen compound / catalyst composite material is used as a lithium / sodium chlorine positive electrode material, and the chlorine gas conversion can be accelerated and the chlorine gas overflow can be inhibited by stacking a catalytic mechanism on the basis of limited adsorption. The lithium chlorine battery kinetic difference and the gas shuttle problem can be solved, and the electrochemical performance of the battery in the super wide temperature range is improved.

Description

Technical Field

[0001] This invention relates to the field of new energy, and more specifically to the field of novel lithium / sodium chloride secondary batteries, and more specifically to a wide-temperature-range lithium / sodium chloride secondary battery cathode material and its preparation method. Background Technology

[0002] Energy storage technology plays a crucial role in applications such as new energy grid integration, grid peak shaving and efficiency improvement, and electric vehicles, and is a key link in implementing the energy revolution. However, my country has a vast territory with complex terrain and diverse climates, resulting in a wide variety of environments for new energy applications. Simultaneously, with the rapid development of my country's exploration technologies in deep sea, deep earth, deep space, and polar regions, and the need for national security, there is an urgent need to develop energy storage devices and technologies suitable for various extreme environments and conditions. Currently, lithium-ion batteries are the most mature technology in electrochemical energy storage, but their high energy density and long lifespan are achieved under normal temperature and environmental conditions. Under harsh environmental conditions such as high / low temperatures (high-altitude / high-temperature regions, military environments, etc.), their performance deteriorates drastically.

[0003] Based on the above issues, numerous scholars have researched and developed a series of high / low temperature resistant electrode materials and electrolytes, which have improved the high and low temperature performance (-20℃-45℃) of lithium-ion batteries to some extent. However, on the one hand, the design of lithium-ion battery electrodes and electrolytes often suffers from trade-offs when trying to balance high / low temperature performance (electrolyte chemical stability and ion transport capacity), high specific capacity (electrolyte electrochemical stability), long cycle life, and storage life (electrode-electrolyte interface stability); on the other hand, how to further achieve high performance and long storage in an ultra-wide temperature range to improve environmental adaptability remains a major challenge for traditional lithium-ion batteries.

[0004] Lithium thionyl chloride (LiChC) batteries are among the commercially available primary batteries with the highest energy density. They maintain excellent performance even at temperatures below -40°C, meeting the demands of harsh outdoor environments and long-term discharge. Therefore, they are widely used as special power sources in military and exploration fields, and are also commonly used in civilian applications such as water, electricity, and gas meters. Developing a secondary battery system based on LiChC (lithium / sodium chloride batteries) holds promise for achieving rechargeable secondary battery technology while retaining the advantages of traditional LiChC primary batteries in harsh environments. However, when faced with ultra-wide temperature ranges and actual battery parameters, the physical confinement and / or chemical adsorption of porous carbon cathodes have extremely limited effect on the sluggish kinetic behavior, and the material surface quickly becomes saturated and loses its function, failing to effectively improve the extreme environmental performance of LiChC secondary batteries. Therefore, constructing high-performance LiChC / sodium chloride battery cathode materials for extreme environments is crucial for improving the electrochemical performance of LiChC batteries over ultra-wide temperature ranges and further extending their storage life. Summary of the Invention

[0005] The two-dimensional transition metal chalcogenide / catalyst composite material as the lithium / sodium chlorine positive electrode material can accelerate the conversion of chlorine and inhibit the overflow of chlorine by superimposing the catalytic mechanism on the basis of confined adsorption.

[0006] A wide-temperature-range lithium / sodium chlorine secondary battery positive electrode material, the positive electrode material being a composite of a two-dimensional transition metal chalcogenide and a catalyst.

[0007] In an embodiment according to the application, the two-dimensional transition metal chalcogenide includes one or more of MoS2, MoSe2, WS2, WSe2, ReS2, and ReSe2.

[0008] In an embodiment according to the application, the catalyst includes one or more of a metal, a metal oxide, and a metal nitride.

[0009] The application further provides a method for preparing the wide-temperature-range lithium / sodium chlorine secondary battery positive electrode material mentioned above, and the specific preparation method is as follows:

[0010] S1, the two-dimensional transition metal chalcogenide and the catalyst are mixed by a ball mill at a ratio of 1:0.1 to 1:1, the ball mill rotation speed is 200-400 r / min, and the ball mill time is 3-5 h;

[0011] S2, the material after ball milling is placed in a beaker, deionized water is added and stirred, filtered, and then repeatedly cleaned with deionized water and ethanol, and then dried;

[0012] S3, the dried material is heated to 800 DEG C in an inert gas Ar atmosphere and kept for 2 h to obtain the positive electrode material.

[0013] In an embodiment according to the application, in S1, deionized water is further added to the ball mill to make the grinding more uniform.

[0014] In an embodiment according to the application, in S1, the ball mill is rotated forward at 400 r / min for 20 min, reversed at 400 r / min for 20 min, and the process is repeated for 5 cycles.

[0015] In an embodiment according to the application, in S3, the heating rate is kept at 5 DEG C / min.

[0016] In addition, the application further provides a wide-temperature-range lithium / sodium chlorine secondary battery positive electrode, which comprises the wide-temperature-range lithium / sodium chlorine secondary battery positive electrode material mentioned above.

[0017] On the basis of the battery positive electrode material and the positive electrode sheet mentioned above, the application further provides a wide-temperature-range lithium / sodium chlorine secondary battery, which comprises a diaphragm, an electrolyte and a negative electrode, wherein the positive electrode in the battery is the positive electrode mentioned above.

[0018] The application further provides a method for preparing the wide-temperature-range lithium / sodium chlorine secondary battery mentioned above.

[0019] The positive electrode sheet is placed upward in the middle of the battery positive electrode shell, 50 ul of electrolyte is added, the diaphragm is covered, 50 ul of electrolyte is added again, a lithium sheet, a gasket, a spring and a battery negative electrode shell are sequentially placed, and finally the battery is prepared in a battery packaging machine under the condition of 10 Mpa pressure and 10 s constant voltage.

[0020] The diaphragm is a glass fiber diaphragm, and the negative electrode material is metal lithium / sodium;

[0021] 4 mol / L AlCl3 is dissolved in SOCl2 and stirred until completely dissolved, then 0.2 wt% fluorine-containing lithium / sodium salt is dissolved in the above solution, and the solution is stirred for 20 min to obtain a color-uniform solution as an electrolyte.

[0022] The beneficial effects of the above technical solutions of the application are as follows:

[0023] (1) The application provides a novel wide-temperature-range lithium / sodium chlorine secondary battery, which realizes the application in the range of-40-60℃ by designing a positive electrode material.

[0024] (2) At the same time, two-dimensional transition metal chalcogen compounds have good adsorption effect on chlorine species, which can promote the nucleation and deposition of metal chlorides on the surface; and TiN can promote the conversion of insulating metal chlorides to chlorine gas due to its strong conductivity.

[0025] (3) The application combines the two types of materials with strong adsorption and conversion promotion through ball milling or hydrothermal method, which can improve the adsorption of the composite material on chlorine species and promote the reversible conversion of metal chlorides to chlorine gas. The polarization pressure difference between charging and discharging is reduced at room temperature, realizing more stable cycle performance. The strong adsorption and conversion promotion realize the feasibility of lithium / sodium chlorine battery in a wide temperature range. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1is an SEM diagram of the MoSe2 / TiN composite material in embodiment one of the present application;

[0027] Figure 2 is a charge-discharge curve of the MoSe2 / TiN composite material in embodiment one at room temperature 25℃;

[0028] Figure 3 is a charge-discharge curve of the MoSe2 / TiN composite material in embodiment one at high temperature 60℃;

[0029] Figure 4 is a charge-discharge curve of the MoSe2 / TiN composite material in embodiment one at low temperature minus 40℃;

[0030] Figure 5 is an impedance spectrum of the MoSe2 / TiN material in embodiment one at 30℃;

[0031] Figure 6 is an impedance spectrum of the MoSe2 / TiN composite material in embodiment one at minus 10℃. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and advantages to be solved by the present application more clear, specific embodiments will be described in detail below.

[0033] Embodiment one

[0034] The present embodiment first proposes a wide-temperature-range lithium / sodium chloride secondary battery positive electrode material, and the positive electrode material is a composite of a two-dimensional transition metal chalcogenide and a catalyst, wherein the two-dimensional transition metal chalcogenide is specifically selected as MoSe2, and the catalyst is selected as nano TiN.

[0035] The specific preparation method of the above positive electrode material is as follows:

[0036] The MoSe2 material and the nano TiN are mixed in a ball mill at a mass ratio of 1:0.5, 5ml of deionized water is added to make the grinding more uniform. The ball mill is set to forward rotation at 400r / min for 20min, and reverse rotation at 400r / min for 20min, and the above process is repeated for 5 cycles. After ball milling, the material is placed in a beaker and 100ml of deionized water is added and stirred for 2h, filtered, and washed with deionized water and ethanol for three times, and then dried in an 80℃ vacuum oven overnight. Finally, the dried material is heated to 800℃ at a rate of 5℃ / min in an inert gas Ar atmosphere, and kept for 2h, and finally the MoSe2 / TiN composite material is obtained.

[0037] The composite material prepared above is used as a positive electrode material, and is mixed with conductive carbon black and PVDF in a mass ratio of 8:1:1 to form a slurry. A certain amount of the slurry is dropped onto a stainless steel sheet, which is dried in a vacuum oven at 120°C to obtain a positive electrode. The specific steps are as follows:

[0038] Take 16 mg of MoSe2 / TiN composite material, 2 mg of conductive carbon black, and 2 mg of PVDF and add them to a maroon mortar. Add 160 ul of NMP solvent and grind and mix them thoroughly for 30 minutes to obtain a slurry. Divide 160 ul of the slurry into 8 equal parts and drop them onto 8 stainless steel sheets, respectively. Place the sheets in a vacuum oven at 120°C and dry them for 12 hours to obtain a positive electrode material. The MoSe2 / TiN material loading of each electrode sheet is about 1.9-2 mg.

[0039] The example also proposes to use the above-mentioned positive electrode to prepare a lithium / sodium chloride secondary battery. The specific preparation steps are as follows:

[0040] A lithium / sodium chloride secondary battery is assembled using glass fiber as a separator and metal lithium / sodium as a negative electrode material, and 70-100 ul of electrolyte is added. The electrolyte is AlCl3, lithium / sodium salt, and SOCl2. 4 mol / L of AlCl3 is dissolved in SOCl2 and stirred until completely dissolved. Then, 0.2 wt% of fluorine-containing lithium / sodium salt is added to the solution and stirred for 20 minutes to obtain a color-uniform solution as the electrolyte. The battery is assembled in a button cell manner. The MoSe2 / TiN active electrode sheet is placed upward in the middle of the button cell positive electrode shell. 50 ul of the above-mentioned electrolyte is added to cover a glass fiber separator with a diameter of 19 mm. Another 50 ul of electrolyte is added. A lithium sheet, a gasket, a spring, and a battery negative electrode shell are placed in sequence. Finally, the MoSe2 / TiN-based lithium chloride secondary battery is obtained by pressing it in a battery packaging machine at a pressure of 10 Mpa for 10 seconds.

[0041] Example Two

[0042] The example first proposes a wide-temperature-range lithium / sodium chloride secondary battery positive electrode material. The positive electrode material is a composite of two-dimensional transition metal chalcogenide and catalyst. The two-dimensional transition metal chalcogenide is specifically MoS2, and the catalyst is nano-TiN.

[0043] The specific preparation method of the above-mentioned positive electrode material is as follows:

[0044] The MoS2 material and nano-TiN are mixed in a ball mill at a mass ratio of 1:0.1, 5 ml of deionized water is added to make the grinding more uniform. The ball mill is set to rotate forward at 400 r / min for 30 min, and reverse at 400 r / min for 30 min, and the process is repeated for 4 cycles. After ball milling, the material is placed in a beaker and 100 ml of deionized water is added and stirred for 2 h, filtered, and washed with deionized water and ethanol three times, and then dried in an 80°C vacuum oven overnight. Finally, the dried material is heated in an inert gas Ar atmosphere, from 5°C / min to 800°C for 2 h, and finally a MoS2 / TiN composite material is obtained.

[0045] The composite material prepared above is used as the positive electrode material, and conductive carbon black, PVDF are ground and mixed at a mass ratio of 8:1:1 as a slurry, and a certain amount of slurry is added to a stainless steel sheet, and vacuum dried at 120°C as a positive electrode. The specific steps are as follows:

[0046] Take 16 mg of MoS2 / TiN composite material, 2 mg of conductive carbon black, and 2 mg of PVDF and add them to a maroon mortar, add 160 ul of NMP solvent, and grind and mix thoroughly for 30 min to obtain a slurry. Divide 160 ul of the slurry into 8 equal parts and place them on 8 stainless steel sheets, and place them in a 120°C vacuum oven for 12 h to obtain a positive electrode material. The MoS2 / TiN material loading of each electrode piece is about 1.9-2 mg.

[0047] This example also proposes to use the above positive electrode to prepare a lithium / sodium chloride secondary battery, and the specific preparation steps are as follows:

[0048] A glass fiber is used as a separator, and lithium / sodium metal is used as a negative electrode material, and 70-100 ul of electrolyte is added to assemble a lithium / sodium chloride secondary battery. The electrolyte is AlCl3, lithium / sodium salt, SOCl2, 4 mol / L AlCl3 is dissolved in SOCl2 and stirred until completely dissolved, then 0.2 wt% fluorine-containing lithium / sodium salt is added to the above solution and stirred for 20 min to obtain a color-uniform solution as the electrolyte. The battery is assembled in a button cell manner, the MoS2 / TiN active electrode piece is placed upward in the middle of the button cell positive electrode shell, 50 ul of the above electrolyte is added, a glass fiber separator with a diameter of 19 mm is covered, and 50 ul of the electrolyte is added again. Place the lithium sheet, gasket, spring, and battery negative electrode shell in order, and finally press in a battery packaging machine at a pressure of 10 Mpa for 10 s to obtain a MoS2 / TiN-based lithium chloride secondary battery.

[0049] Example Three

[0050] The embodiment first proposes a wide-temperature-range lithium / sodium chloride secondary battery positive electrode material. The positive electrode material is a composite of two-dimensional transition metal chalcogenide and catalyst. The two-dimensional transition metal chalcogenide is specifically MoSe2, and the catalyst is specifically nano-TiN.

[0051] The specific preparation method of the positive electrode material is as follows:

[0052] The MoSe2 material and nano-TiN are mixed in a ball mill at a mass ratio of 1:1, 5ml of deionized water is added to make the grinding more uniform. The ball mill is set to forward rotation at 400r / min for 30min, and reverse rotation at 400r / min for 30min. Repeat this process for 3 cycles. After ball milling, the material is placed in a beaker and 100ml of deionized water is added and stirred for 2h. Filter and wash with deionized water and ethanol for three times. Then dry in an 80℃ vacuum oven overnight. Finally, dry the material in an inert gas Ar atmosphere, heat from 5℃ / min to 800℃ and keep for 2h. Finally, MoSe2 / TiN composite material is obtained.

[0053] The composite material prepared above is used as the positive electrode material, and conductive carbon black and PVDF are ground and mixed at a mass ratio of 8:1:1 as a slurry. A certain amount of slurry is added to a stainless steel sheet, and vacuum dried at 120℃ as a positive electrode. The specific steps are as follows:

[0054] Take 16mg MoSe2 / TiN composite material, 2mg conductive carbon black, and 2mg PVDF and add them to a maroon mortar. Add 160ul of NMP solvent and grind and mix for 30min to obtain a slurry. Divide 160ul of the slurry into 8 equal parts and add them to 8 stainless steel sheets. Place them in a 120℃ vacuum oven for 12h to obtain a positive electrode material. The MoSe2 / TiN material loading of each electrode piece is about 1.9-2mg.

[0055] The embodiment also proposes to use the above positive electrode to prepare a lithium / sodium chloride secondary battery. The specific preparation steps are as follows:

[0056] The lithium / sodium chloride secondary battery is assembled by using glass fiber as a diaphragm, metal lithium / sodium as a negative electrode material, and dropping 70-100 ul of electrolyte, wherein the electrolyte is AlCl3, lithium salt / sodium salt, and SOCl2, 4 mol / L of AlCl3 is dissolved in SOCl2 and stirred until completely dissolved, then 0.2 wt% of fluorine-containing lithium / sodium salt is dissolved in the above solution, and the solution is stirred for 20 min to obtain a color-uniform solution as the electrolyte. The battery is assembled in a button cell mode, the MoSe2 / TiN active electrode sheet is placed upward in the middle of the button cell positive shell, 50 ul of the above electrolyte is dropped, the glass fiber diaphragm with a diameter of 19 mm is covered, 50 ul of electrolyte is dropped again, the lithium sheet, gasket, spring, and battery negative shell are placed in turn, and finally the MoSe2 / TiN-based lithium chloride secondary battery is obtained by pressing at a pressure of 10 Mpa for 10 s in a battery packaging machine.

[0057] The battery prepared in Example 1 is also tested for performance in a temperature range of-40-60℃, and the specific tests are as follows:

[0058] (1) The MoSe2 / TiN-based lithium chloride secondary battery is tested by CV using a gamry electrochemical workstation, the scan rate is 0.2-1 mV / s, the voltage window is 2-4.2 V, and each scan is three cycles.

[0059] (2) The MoSe2 / TiN-based lithium chloride secondary battery is tested for impedance under different charge and discharge states using a gamry electrochemical workstation, and the frequency range is 0.01-100000 Hz.

[0060] (3) The MoSe2 / TiN-based lithium chloride secondary battery is tested for charge and discharge, rate, cycle, constant current intermittent titration, etc. using a blue electric, the charge and discharge and rate test current density is 100-2000 mA / g, the cycle test current density is 500 and 2000 mA / g, and the constant current intermittent titration current density is 50 mA / g, and the relaxation time is 20 min.

[0061] The above tests obtain the charge and discharge curve graphs and impedance spectra of Figure 2 to Figure 6 , Figure 2 The charge and discharge platform and specific capacity of the MoSe2 / TiN composite material at room temperature (25℃) are obtained, and the MoSe2 / TiN composite material exhibits a charge and discharge voltage difference of 0.21 V and a high specific capacity of 1350 mAh / g at room temperature. Figure 3The charge-discharge platform and the charge-discharge specific capacity of the MoSe2 / TiN composite material at 60 DEG C high temperature condition, the MoSe2 / TiN composite material exhibits 0.42V charge-discharge voltage difference and 1000mAh / g high specific capacity, even at 60 DEG C high temperature, excellent electrochemical performance is also exhibited. Figure 4 The MoSe 2 / The charge-discharge platform and the charge-discharge specific capacity of the TiN composite material at-40 DEG C extreme low temperature condition, the MoSe2 / TiN composite material exhibits 1.66V charge-discharge voltage difference and 500mAh / g specific capacity at extreme condition, thanks to the excellent kinetic performance of the MoSe2 / TiN material, making the lithium-chlorine secondary battery still feasible at extreme condition. Figure 5 The MoSe2 / TiN material impedance spectrum at 30 DEG C is shown, at 30 DEG C condition, the MoSe2 / TiN material exhibits smaller internal resistance and charge transfer resistance, showing the excellent kinetic performance of the MoSe2 / TiN material, while Figure 6 It can be concluded that when the temperature drops by 40 DEG C, the charge transfer resistance only increases to 175ohm, further verifying the excellent application prospect of the MoSe2 / TiN material at low temperature condition.

[0062] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A lithium / sodium chloride secondary battery having a wide temperature range, comprising a separator, an electrolyte, and a negative electrode, characterized in that, The positive electrode is also included, and the positive electrode material is a composite of a two-dimensional transition metal chalcogenide and a catalyst, wherein the catalyst is selected from nano-TiN, and is used to promote the conversion of insulating metal chloride into chlorine gas; the wide temperature range is -40℃ to 60℃; The preparation method is as follows: S1, the two-dimensional transition metal chalcogenide and the catalyst are mixed by a ball mill at a ratio of 1:0.1-1:1, the ball mill rotation speed is 200-400r / min, the ball milling time is 3-5h, and deionized water is added to the ball mill to form a uniform slurry; S2, the material after ball milling is placed in a beaker and stirred with deionized water, filtered, and washed repeatedly with deionized water and ethanol, and then dried; S3, the dried material is heated to 800℃ at a heating rate of 5℃ / min in an inert gas Ar atmosphere and kept for 2h to obtain the positive electrode material.

2. The wide temperature range lithium / sodium chloride secondary battery according to claim 1, wherein the cathode is a lithium / sodium chloride secondary battery. The two-dimensional transition metal chalcogenide includes one or more of MoS2, MoSe2, WS2, WSe2, ReS2, and ReSe2.

3. The wide temperature range lithium / sodium chloride secondary battery of claim 1, wherein, In S1, the ball mill is rotated forward at 400r / min for 20min, and then reversed at 400r / min for 20min, and the process is repeated for 5 cycles.

4. The wide temperature range lithium / sodium chloride secondary battery as claimed in claim 1, wherein, The method is as follows: The positive electrode sheet is placed upward in the middle of the positive electrode shell, 50ul of electrolyte is added, the separator is covered, 50ul of electrolyte is added again, the lithium sheet, gasket, spring and negative electrode shell are placed in turn, and finally the battery is packaged in a battery packaging machine at a pressure of 10Mpa for 10s to obtain the battery; The separator is selected from a glass fiber separator, and the negative electrode material is metal lithium / sodium; 4mol / L AlCl3 is dissolved in SOCl2 and stirred until completely dissolved, then 0.2wt% fluorine-containing lithium / sodium salt is added to the obtained solution, stirred for 20min to obtain a color uniform solution as the electrolyte.

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