Cr-doped MSe2 electrode material and preparation method thereof

Abstract

According to the CrxM1-xSe2 electrode material and the preparation method thereof provided by the invention, M powder, chromium powder and selenium powder are used as simple substance raw materials, a CrxM1-xSe2 precursor is prepared through solid phase sintering, then the precursor is subjected to chemical vapor transport to obtain a single crystal, the single crystal and zirconium beads are mixed and placed in a ball mill for ball milling to obtain fine powder, and the fine powder is prepared into the CrxM1-xSe2 electrode material. And finally, mixing, coating, drying and cutting to obtain the electrode plate. The CrxM1-xSe2 single crystal is successfully prepared in a mode of combining a solid-phase reaction method and a chemical vapor transport method, and is applied to the field of lithium batteries. The M site of MSe2 is partially substituted and doped by 3d metal Cr, so that the change and exploration of the transition metal chalcogenide in the electrochemical mechanism direction are facilitated, and excellent lithium primary battery performance is shown. According to the invention, the Cr-doped MSe2 electrode material is successfully prepared and assembled into the lithium button battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode material preparation, and particularly relates to a Cr-doped MSe2 electrode material and a preparation method thereof. Background Art

[0002] MSe2 (M = V, Nb, Ta) is composed of transition metal elements V, Nb, Ta and chalcogen element Se, belonging to transition metal chalcogenide compounds and being a two-dimensional van der Waals layered material. Compared with graphite and carbon fluoride which are also layered materials, transition metal chalcogenide compounds have advantages such as high layer spacing, high theoretical specific capacity, rich electronic structure and band gap. At present, M-site doping of transition metal chalcogenide compounds has changed many battery performances. As a magnetic atom, Cr has rich electronic valence states, and it is considered that doping Cr into typical transition metal chalcogenide compounds MSe2 (M = V, Nb, Ta) can achieve more interesting battery characteristics. For traditional transition metal chalcogenide compounds, their main battery reaction mechanism is the lithium insertion / extraction reaction mechanism, which refers to an electrochemical process in which lithium ions reversibly insert (embed) and extract in the positive and negative electrode materials of the battery, while the main crystal structure of the material remains basically unchanged. It has been found that partial substitution doping of transition metal chalcogenide compounds will present a new electrochemical process different from the lithium insertion / extraction reaction mechanism (such as the conversion reaction mechanism). Therefore, the research on M-site doping helps to change the electrochemical reaction mechanism and achieve more abundant battery performances. Summary of the Invention

[0003] Object of the Invention. To achieve the above object of the invention, the present invention provides a Cr x M 1-x Se2 (M = V, Nb, Ta) electrode material and the preparation of a Cr x M 1-x Se2 lithium battery, and provides a preparation method of a Cr x M 1-x Se2 (M = V, Nb, Ta) electrode material.

[0004] Technical Solution. To solve the above technical solution and achieve the above object of the invention, the present invention proposes a Cr-doped MSe2 electrode material, in which Cr partially replaces the M site of MSe2 to form a Cr x M 1-x Se2 electrode material, where 0 < x ≤ 0.45 and M is any one of vanadium, niobium, and tantalum.

[0005] The present invention proposes a preparation method of the above electrode material, and the method includes the following steps:

[0006] S1: Grind the elemental powders of M powder, chromium powder, and selenium powder to fully mix them to obtain an alloy powder mixture;

[0007] S2: Under argon protection, the alloy powder mixture is placed into the first quartz tube and sealed with the first quartz column;

[0008] S3: Vacuum seal the first quartz tube, and ensure that the water and oxygen content inside the first quartz tube is below a predetermined level, to obtain the first quartz tube to be heated;

[0009] S4: The first quartz tube to be heated is placed in a box furnace and heated to a first predetermined temperature, and held for a first predetermined time to obtain the first precursor;

[0010] S5: Place the first precursor powder into the second quartz tube and seal it with the second quartz column;

[0011] S6: Vacuum seal the second quartz tube, and ensure that the water and oxygen content inside the second quartz tube is below a predetermined level to obtain the second quartz tube to be heated;

[0012] S7: Place the second double-layer quartz tube to be heated in a tube furnace, heat it to a second predetermined temperature in the high-temperature zone, heat it to a third predetermined temperature in the low-temperature zone, hold it for a second predetermined time, then reduce it to 300 ℃ at a rate of 0.05 ℃ / min, and then reduce it to room temperature to obtain Cr. x M 1-x Se2 single crystal, 0 <x≤0.45;

[0013] S8: Cr x M 1-x Se2-doped single crystals were mixed with alcohol and zirconium beads and placed in a ball mill. A first predetermined speed was set, and the mixture was maintained for a fourth predetermined time to obtain Cr. x M 1-x Se2 electrode material, wherein the Cr x M 1-x The ratio of Se2-doped single crystals to zirconium beads is 15:1.

[0014] Furthermore, in step S1, the molar ratio of M powder, chromium powder, and selenium powder is (0.55-0.96):(0.04-0.45):1; the grinding time is 0.5-1h; and the purity of M powder, chromium powder, and selenium powder is greater than 99.99%.

[0015] Furthermore, in S3 and S6, the predetermined content is less than 0.1 ppm.

[0016] Furthermore, in S4, the first predetermined temperature is 900°C, and the first predetermined time is 5 days.

[0017] Further, in S7, the second predetermined temperature is 900 °C, the third predetermined temperature is 800 °C, and the second predetermined time is 10 days.

[0018] Further, in S8, the first predetermined rotation speed is 3200 rpm, and the fourth predetermined time is 8 h.

[0019] The present invention also provides a method for preparing a Cr-doped MSe2 electrode sheet, and the method is as follows:

[0020] S81: Mix the Cr x M 1-x Se2 electrode material and the NMP solution of PVDF in a certain proportion, place it in a defoaming machine, maintain the second predetermined rotation speed, and maintain the fifth predetermined time to obtain the Cr x M 1-x Se2 electrode paste, where 0 < x ≤ 0.45, and M is any one of vanadium, niobium, and tantalum;

[0021] S82: Uniformly coat the Cr x M 1-x Se2 electrode paste on the copper foil, place the coated copper foil in an oven, maintain the sixth predetermined time, and cut it into a circular electrode sheet to obtain the Cr x M 1-x Se2 electrode sheet.

[0022] Further, the second predetermined rotation speed is 3000 rpm, and the fifth predetermined time is 0.5 h; the sixth predetermined time is 2.5 h. The mass ratio of the Cr x M 1-x Se2 electrode material to PVDF is 95:5, and the 10% PVDF NMP solution is used.

[0023] The present invention also provides a button battery, and the electrode sheet of the button battery is prepared by using the above method.

[0024] Beneficial effects: Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0025] The Cr-doped MSe2 electrode material and the preparation method provided by the present invention use M (vanadium, niobium, tantalum) powder, chromium powder, and selenium powder as elemental raw materials. First, the Cr x M 1-x Se2 precursor is prepared by solid-phase sintering, then the precursor is subjected to chemical vapor transport to obtain a single crystal, the single crystal is mixed with zirconium beads and placed in a ball mill for ball milling to obtain a fine powder, and finally, it is mixed, coated, dried, and cut to obtain an electrode sheet. The present invention combines the solid-phase reaction method and the chemical vapor transport method to successfully prepare the Cr x M 1-xSe2 (M=V, Nb, Ta) single crystals. Doping the M site of MSe2 with 3d metallic Cr facilitates the exploration of changes in the electrochemical mechanisms of this type of transition metal chalcogenide compound, demonstrating excellent lithium primary battery performance. This invention successfully prepared Cr-doped MSe2 electrode materials and assembled them into lithium coin half-cells. Attached Figure Description

[0026] Figure 1 This is the preparation of Cr in Example 1 of the present invention. 0.04 Ta 0.96 X-ray energy spectrum of Se2.

[0027] Figure 2 This is the preparation of Cr in Example 2 of the present invention. 0.1 Ta 0.9 X-ray energy spectrum of Se2.

[0028] Figure 3 This is the preparation of Cr in Example 3 of the present invention. 0.3 Ta 0.7 X-ray energy spectrum of Se2.

[0029] Figure 4 This is the preparation of Cr in Example 4 of the present invention. 0.45 Ta 0.55 X-ray energy spectrum of Se2.

[0030] Figure 5 This is an example of the characterization of Cr in Embodiment 1 of the present invention. 0.04 Ta 0.96 Discharge specific capacity-voltage diagram of Se2 electrode material.

[0031] Figure 6 This is the characterization of Cr in Embodiment 2 of the present invention. 0.1 Ta 0.9 Discharge specific capacity-voltage diagram of Se2 electrode material.

[0032] Figure 7 This is the characterization of Cr in Example 4 of the present invention. 0.45 Ta 0.55 Discharge specific capacity-voltage diagram of Se2 electrode material.

[0033] Figure 8 This is the characterization of Cr in Example 5 of the present invention. 0.1 V 0.9 Discharge specific capacity-voltage diagram of Se2 electrode material.

[0034] Figure 9 This is the characterization of Cr in Example 6 of the present invention. 0.1 Nb 0.9 Discharge specific capacity-voltage diagram of Se2 electrode material. Detailed Implementation

[0035] The technical solutions and technical effects of the embodiments of the present invention will be further elaborated in detail below in conjunction with the accompanying drawings of the present invention.

[0036] The present invention provides a Cr-doped MSe2 electrode material, where Cr partially replaces the M site of MSe2 to form a Cr x M 1-x MSe2 electrode material, where 0 < x ≤ 0.45 and M is any one of vanadium, niobium, and tantalum.

[0037] The present invention provides a method for preparing the electrode material, and the method includes the following steps:

[0038] S1: Grind the elemental powders of M powder, chromium powder, and selenium powder to obtain an alloy powder mixture by fully mixing them.

[0039] S2: Under argon protection, put the alloy powder mixture into a first quartz tube and seal it with a first quartz column.

[0040] S3: Vacuum-seal the first quartz tube, and ensure that the water and oxygen content inside the first quartz tube is below a predetermined content to obtain a first quartz tube to be heated.

[0041] S4: Place the first quartz tube to be heated in a box furnace and heat it to a first predetermined temperature, and maintain the first predetermined time to obtain a first precursor.

[0042] S5: Put the first precursor powder into a second quartz tube and seal it with a second quartz column.

[0043] S6: Vacuum-seal the second quartz tube, and ensure that the water and oxygen content inside the second quartz tube is below a predetermined content to obtain a second quartz tube to be heated.

[0044] S7: Place the second quartz tube to be heated in a tube furnace, heat the high-temperature zone to a second predetermined temperature and the low-temperature zone to a third predetermined temperature, synchronously maintain the second predetermined time, then cool it to 300 °C at a rate of 0.05 °C / min, and then cool it to room temperature to obtain Cr x M 1-x Se2 single crystal, 0 < x ≤ 0.45;

[0045] S8: Mix the Cr x M 1-x Se2 doped single crystal with alcohol and zirconium beads, place them in a ball mill, set a first predetermined rotation speed, and maintain a fourth predetermined time to obtain a Cr x M 1-x Se2 electrode material, and the ratio of the Cr x M 1-x Se2 doped single crystal to zirconium beads is 15:1.

[0046] Further, in S1, the molar ratio of the M powder, chromium powder, and selenium powder is (0.55 - 0.96):(0.04 - 0.45):1; the grinding time is 0.5 - 1 h, and the purity of the M powder, chromium powder, and selenium powder is greater than 99.99%.

[0047] Further, in S3 and S6, the predetermined content is 0.1 ppm or less.

[0048] Further, in S4, the first predetermined temperature is 900 °C, and the first predetermined time is 5 days.

[0049] Further, in S7, the second predetermined temperature is 900 °C, the third predetermined temperature is 800 °C, and the second predetermined time is 10 days.

[0050] Further, in S8, the first predetermined rotation speed is 3200 rpm, and the fourth predetermined time is 8 h.

[0051] The present invention also provides a method for preparing a Cr-doped MSe2 electrode plate, and the method is as follows:

[0052] S81: Mix the Cr x M 1-x Se2 electrode material and the NMP solution of PVDF in a certain proportion, place them in a defoaming machine, maintain the second predetermined rotation speed, and maintain the fifth predetermined time to obtain the Cr x M 1-x Se2 electrode paste, where 0 < x ≤ 0.45, and M is any one of vanadium, niobium, and tantalum;

[0053] S82: Uniformly coat the Cr x M 1-x Se2 electrode paste on the copper foil, place the coated copper foil in an oven, maintain the sixth predetermined time, and cut it into a circular electrode plate to obtain the Cr x M 1-x Se2 electrode plate.

[0054] Further, the second predetermined rotation speed is 3000 rpm, and the fifth predetermined time is 0.5 h; the sixth predetermined time is 2.5 h, and the mass ratio of the Cr x M 1-x Se2 electrode material to PVDF is 95:5, and a 10% PVDF NMP solution is used.

[0055] The present invention also provides a button battery, and the electrode plate of the button battery is prepared by using the above method.

[0056] The devices used in the following examples and comparative examples are as follows:

[0057] The glove box was purchased from Mikrouna; the hydrogen-oxygen tube sealing machine was purchased from BALAB, model MRVS-1003; the box furnace model was KSL-1200X; the tube furnace model was OTF-1200X; and the high-performance ball mill was also used.

[0058] Example 1

[0059] Weigh out the Cr preparation in an argon-filled glove box. 0.04 Ta 0.96 The alloy powder of Se2, with raw materials of tantalum, chromium and selenium weighing 0.0139 g, 1.1581 g and 1.0529 g respectively, was placed in a pre-cleaned agate mortar and ground for 0.5 to 1 hour.

[0060] The ground powder raw materials were placed in small quartz tubes that had been ultrasonically cleaned and dried with deionized water. The small quartz tubes had an inner diameter of 17 mm and a length of 150 mm. They were sealed with a quartz column with a diameter of 16 mm and a height of 10 mm. The above operation process was maintained with H2O and O2 < 0.1 ppm.

[0061] The apparatus containing the reaction powder was sealed with a vacuum valve to ensure that the powder was not exposed to air. It was then removed from the glove box and vacuum-sealed using a hydrogen-oxygen tube sealing machine. This process involved purging the quartz tube three times to ensure adequate vacuum. Finally, it underwent heat treatment in a box furnace, heating to 900 °C and holding for 5 days. After the holding period, it was allowed to cool to room temperature before being removed to obtain the prepared Cr. 0.04 Ta 0.96 Se2 precursor powder.

[0062] Cr 0.04 Ta 0.96 Se2 precursor powder was removed and placed into a tubular quartz tube. The medium-sized quartz tube had an inner diameter of 21 mm and a length of 300 mm. It was sealed with a quartz column with a diameter of 20 mm and a height of 10 mm. Throughout the process, H2O and O2 levels were maintained below 0.1 ppm. The tube was then sealed with a vacuum valve to prevent exposure to air. It was removed from the glove box and vacuum-sealed using an oxyhydrogen sealing machine. This process required three gas purgings of the quartz tube to ensure adequate vacuum. The sealed tube containing Cr... 0.04 Ta 0.96 Se2 powder was placed in a quartz tube and heat-treated in a tube furnace. The high-temperature zone was set at 900℃ and the low-temperature zone at 800℃. The temperature was simultaneously raised to the specified temperature and held for 10 days. After cooling to room temperature, the Cr electrode material was obtained. 0.04 Ta 0.96 Se2 single crystal.

[0063] sintered Cr 0.04 Ta0.96 Se2 single crystals were extracted and fed into a ball mill with zirconium beads at a ball-to-material ratio of 15:1. Alcohol was added as a dispersion medium. The mill was set to 3200 rpm and milled for 8 hours to pulverize the active material, maintaining uniform particle size. Smaller particle size increases surface area and active sites, allowing for greater lithium ion absorption and further separation of zirconium beads from Cr. 0.04 Ta 0.96 Se2, yields Cr 0.04 Ta 0.96 Se2 electrode material, ball-milled Cr 0.04 Ta 0.96 0.0345 g of Se2 electrode material was taken, along with 73 μL of a 10% PVDF (polyvinylidene fluoride) NMP solution, where PVDF served as a binder and NMP (N-methylpyrrolidone) as a solvent. Further dilution with additional NMP was possible to obtain electrode sheets of varying thicknesses. The mixture was thoroughly mixed using a defoamer at 3000 rpm for 0.5 h to obtain Cr... 0.04 Ta 0.96 Se2 electrode paste was uniformly coated onto copper foil and placed in an oven at 70℃ for 2.5 hours. The dried copper foil was then removed and cut into circular electrode sheets, ultimately yielding Cr. 0.04 Ta 0.96 Se2 electrode sheet.

[0064] The glove box, subsequently assembled under an argon atmosphere, is as follows: positive electrode shell, Cr... 0.04 Ta 0.96 A lithium button cell is obtained by combining a Se2 electrode sheet, 32μL of lithium-ion battery electrolyte, a single-layer separator, 32μL of lithium-ion battery electrolyte, a lithium sheet, a gasket, a spring sheet, and a negative electrode shell.

[0065] Example 2

[0066] Weigh out the Cr preparation in an argon-filled glove box. 0.1 Ta 0.9 The alloy powder of Se2, with raw materials of chromium, tantalum, and selenium in quantities of 0.0347 g, 1.0857 g, and 1.0529 g respectively; other steps are the same as in Example 1, finally yielding Cr 0.04 Ta 0.96 Se2 electrode sheet.

[0067] Example 3

[0068] Weigh out the Cr preparation in an argon-filled glove box. 0.3 Ta 0.7The alloy powder raw materials for Se2, chromium, tantalum, and selenium, were prepared in quantities of 0.1041 g, 0.8444 g, and 1.0529 g, respectively. Other steps were the same as in Example 1, ultimately yielding Cr. 0.04 Ta 0.96 Se2 electrode sheet.

[0069] Example 4

[0070] Weigh out the Cr preparation in an argon-filled glove box. 0.45 Ta 0.55 The alloy powder raw materials for Se2, chromium, tantalum, and selenium, were prepared in quantities of 0.1561 g, 0.6635 g, and 1.0529 g, respectively. Other steps were the same as in Example 1, ultimately yielding Cr. 0.04 Ta 0.96 Se2 electrode sheet.

[0071] Example 5

[0072] Weigh out the Cr preparation in an argon-filled glove box. 0.1 V 0.9 The alloy powder raw materials for Se2, containing 0.0347 g of chromium, 0.3056 g of vanadium, and 1.0529 g of selenium, were used. Other steps were the same as in Example 1, ultimately yielding Cr. 0.1 V 0.9 Se2 electrode sheet.

[0073] Example 6

[0074] Weigh out the Cr preparation in an argon-filled glove box. 0.1 Nb 0.9 The alloy powder raw materials for Se2, containing 0.0347 g of chromium, 0.5575 g of niobium, and 1.0529 g of selenium, were used. Other steps were the same as in Example 1, ultimately yielding Cr. 0.1 Nb 0.9 Se2 electrode sheet.

[0075] Figure 1-4 These are X-ray energy dispersive X-ray spectra of the four electrode materials prepared in Examples 1-4. The peaks of the three elements of the target product can be observed in the figures, proving that the obtained sample is the target product. Figure 5-9 The five discharge specific capacity-voltage diagrams characterized by Examples 1, 2, and 4-6 show that Cr doping makes the electrode material exhibit good discharge specific capacity.

[0076] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A Cr-doped MSe2 electrode material, characterized in that, The M site of MSe2 is partially substituted by Cr to form Cr x M 1-x Se2 electrode material, where 0 < x ≤ 0.45 and M is any one of vanadium, niobium, and tantalum.

2. A method for preparing the electrode material as described in claim 1, characterized in that, The method includes the following steps: S1: Grind the elemental powders of M powder, chromium powder, and selenium powder to fully mix them to obtain an alloy powder mixture; S2: Under argon protection, the alloy powder mixture is placed into the first quartz tube and sealed with the first quartz column; S3: Vacuum seal the first quartz tube, and ensure that the water and oxygen content inside the first quartz tube is below a predetermined level, to obtain the first quartz tube to be heated; S4: The first quartz tube to be heated is placed in a box furnace and heated to a first predetermined temperature, and held for a first predetermined time to obtain the first precursor; S5: Place the first precursor powder into the second quartz tube and seal it with the second quartz column; S6: Vacuum seal the second quartz tube, and ensure that the water and oxygen content inside the second quartz tube is below a predetermined level to obtain the second quartz tube to be heated; S7: Place the second double-layer quartz tube to be heated in a tube furnace, heat it to a second predetermined temperature in the high-temperature zone, heat it to a third predetermined temperature in the low-temperature zone, hold it for a second predetermined time, then reduce it to 300 ℃ at a rate of 0.05 ℃ / min, and then reduce it to room temperature to obtain Cr. x M 1-x Se2 single crystal, 0 <x≤0.45; S8: Cr x M 1-x Se2-doped single crystals were mixed with alcohol and zirconium beads and placed in a ball mill. A first predetermined rotation speed was set, and the mixture was maintained for a fourth predetermined time to obtain Cr. x M 1-x Se2 electrode material, wherein the Cr x M 1-x The ratio of Se2-doped single crystals to zirconium beads is 15:

1.

3. The method for preparing electrode material according to claim 2, characterized in that, In step S1, the molar ratio of M powder, chromium powder, and selenium powder is (0.55-0.96):(0.04-0.45):1; the grinding time is 0.5-1h; and the purity of M powder, chromium powder, and selenium powder is greater than 99.99%.

4. The method for preparing electrode material according to claim 2, characterized in that, In S3 and S6, the predetermined content is less than 0.1 ppm.

5. The method for preparing electrode material according to claim 2, characterized in that, In S4, the first predetermined temperature is 900°C and the first predetermined time is 5 days.

6. The method for preparing electrode material according to claim 2, characterized in that, In S7, the second predetermined temperature is 900 ℃, the third predetermined temperature is 800 ℃, and the second predetermined time is 10 days.

7. The method for preparing electrode material according to claim 2, characterized in that, In S8, the first predetermined speed is 3200 rpm and the fourth predetermined time is 8 hours.

8. A method for preparing a Cr-doped MSe2 electrode sheet, characterized in that, The method is as follows: S81: Put Cr x M 1-x Se2 electrode material and NMP solution of PVDF are mixed in a certain proportion and placed in a defoamer, maintaining the second predetermined rotation speed and the fifth predetermined time to obtain Cr x M 1-x Se2 electrode paste, where 0 < x ≤ 0.45, and M is any one of vanadium, niobium, and tantalum; S82: Cr x M 1-x Se2 electrode paste is uniformly coated onto copper foil. The coated copper foil is then placed in an oven and kept for a predetermined time. The foil is then cut into circular electrode sheets to obtain Cr. x M 1-x Se2 electrode sheet.

9. The method according to claim 8, characterized in that, The second predetermined speed is 3000 rpm, the fifth predetermined time is 0.5 h; the sixth predetermined time is 2.5 h, Cr x M 1-x The mass ratio of Se2 electrode material to PVDF is 95:5, and an NMP solution of 10% PVDF is used.

10. A button battery, characterized in that, The button cell electrode sheet is prepared using the method of claim 8 or claim 9.

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