Composite lithium metal electrode material and preparation method and application thereof

Abstract

The invention relates to a composite lithium metal electrode material and a preparation method and application thereof, in particular to the technical field of lithium batteries. The preparation method of the composite lithium metal electrode material specifically comprises the following steps: rolling a lithium metal sheet and carbon fibers for 1-3 times to obtain the composite lithium metal electrode material. The composite lithium metal electrode material disclosed by the invention can effectively inhibit volume expansion and dendritic crystal growth of lithium metal and improve the cycling stability and safety of a battery. The preparation method is simple in process, short in period, low in cost and easy to popularize and use.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a composite lithium metal electrode material and a preparation method and application thereof. Background Art

[0002] With the development of lithium battery technology, the demand for improved battery performance and safety is growing. Lithium metal (Li) is considered an ideal anode material for next-generation high-energy-density lithium secondary batteries due to its ultra-high theoretical specific capacity (3860 mAh / g), low density (0.53 g / cm), and lowest reduction potential (-3.04 V vs. standard hydrogen electrode). However, its application is limited by volume expansion, dendrite growth, safety, and short cycle life during charge and discharge. Carbon fiber, as a lightweight, high-strength conductive material, can serve as a carrier for lithium metal, improving its electrochemical performance and stability.

[0003] Therefore, how to load lithium metal sheets on carbon fibers to achieve low-cost, commercial-quality, and excellent cycle stability negative electrode materials is a challenge and one of the industry's technical difficulties. Summary of the Invention

[0004] To address the above technical problems, the present invention provides a composite lithium metal electrode material, its preparation method, and its application. The composite lithium metal electrode material of the present invention effectively inhibits the volume expansion and dendrite growth of lithium metal, improving the cycle stability and safety of the battery. The preparation method of the present invention is simple, has a short cycle time, is low in cost, and is easy to promote and use.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] The first object of the present invention is to provide a method for preparing a composite lithium metal electrode material, which is as follows: a lithium metal sheet and carbon fiber are rolled together for 1 to 3 times to obtain a composite lithium metal electrode material.

[0007] The beneficial effects of the present invention are as follows: the composite lithium metal electrode material prepared by rolling lithium metal sheets and carbon fibers together is prepared by the method of the present invention, which has a simple process, a short cycle, a low cost, and is easy to promote and use.

[0008] On the basis of the above technical solution, the present invention can also be improved as follows.

[0009] Furthermore, the length ratio of the lithium metal sheet to the carbon fiber is 1-2:1-2; the width ratio of the lithium metal sheet to the carbon fiber is 30-40:45-55.

[0010] Furthermore, the rolling environment is a dry environment, in which the relative humidity is 10% to 20% and the dew point temperature is -20°C to -45°C.

[0011] Furthermore, secondary processing is performed after the rolling.

[0012] Furthermore, the specific steps of the secondary treatment are as follows: heat-treating the composite lithium metal electrode material in an Ar atmosphere, then cooling it and rolling it again to obtain a composite lithium metal electrode material.

[0013] The beneficial effect of adopting the above further scheme is: in the secondary treatment of the present invention, micro-melting and rolling are used again, the purpose of which is to make the connection between the micro-melted lithium sheet and the carbon fiber matrix more complete, improve the close contact between the lithium metal sheet and the carbon fiber, improve the interface mechanical properties, and improve the battery cycle performance.

[0014] Furthermore, the heat treatment temperature is 170° C. to 190° C., the time is 0.5 h to 2 h, and the heating rate is 4° C. / min to 7° C. / min.

[0015] A second object of the present invention is to provide a composite lithium metal electrode material.

[0016] The beneficial effects of the present invention are: the composite lithium metal electrode material of the present invention can effectively inhibit the volume expansion and dendrite growth of lithium metal, and improve the cycle stability and safety of the battery.

[0017] Furthermore, the thickness of the composite lithium metal electrode material is 0.1 mm to 0.4 mm.

[0018] The third object of the present invention is to provide an application of a composite lithium metal electrode material, and to use the composite lithium metal electrode material in the preparation of a lithium metal battery.

[0019] Furthermore, the composite lithium metal electrode material is used as a negative electrode material in the preparation of a battery.

[0020] Furthermore, the battery includes at least one of a lithium metal battery and a lithium metal structure energy storage composite structure battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a picture of the composite lithium metal electrode material prepared in Example 1 of the present invention;

[0022] Figure 2 Graphs showing the charge and discharge capacity of lithium metal button batteries according to Examples 7 and 8 of the present invention;

[0023] Figure 3 Graph showing capacity retention of lithium metal button batteries according to Examples 7 and 8 of the present invention;

[0024] Figure 4 This is a charge and discharge capacity curve diagram of the lithium metal structure energy storage composite structure battery of Examples 13 to 16 of the present invention. DETAILED DESCRIPTION

[0025] The principles and features of the present invention are described below. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this field or the product instructions are used. Where the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be purchased through regular channels.

[0026] Example 1: Preparation of composite lithium metal electrode material

[0027] A 1-meter-long, 35-cm-wide lithium metal sheet (Tianjin Zhongneng Lithium Industry Co., Ltd.) and a 1-meter-long, 50-cm-wide carbon fiber (T300-1K; Weihai Guangwei Composite Materials Co., Ltd.) were placed in a roller press for pressing at a pressure of 0.04 to 0.08 MPa. The materials were rolled twice in a drying room with a relative humidity of 10% to 20% and a dew point temperature of -20°C to -45°C to obtain a lithium metal sheet-loaded carbon fiber. The lithium metal sheet-loaded carbon fiber was placed in an atmosphere furnace and heat-treated at 180°C for 1 h in an Ar atmosphere at a heating rate of 5°C / min. After the heat treatment was completed, the materials were placed and cooled and then rolled twice again to obtain a composite lithium metal electrode material having a thickness of 0.2 mm. Figure 1 shown.

[0028] Example 2: Preparation of composite lithium metal electrode material II

[0029] A 1-meter-long, 35-cm-wide lithium metal sheet (Tianjin Zhongneng Lithium Industry Co., Ltd.) and a 1-meter-long, 50-cm-wide carbon fiber (T300-1K; Weihai Guangwei Composite Materials Co., Ltd.) were placed in a roller press and pressed. The materials were pressed once under a pressure of 0.04 to 0.08 MPa in a dry room maintained at a relative humidity of 10% to 20% and a dew point of -20°C to -45°C to obtain the lithium metal sheet-loaded carbon fiber. The carbon fiber was then heat-treated in an atmosphere furnace at 170°C for 2 hours under an Ar atmosphere at a heating rate of 7°C / min. After the heat treatment, the materials were allowed to cool and then rolled again twice to obtain a composite lithium metal electrode material with a thickness of 0.2 mm.

[0030] Example 3: Preparation of composite lithium metal electrode material

[0031] A 1-meter-long, 35-cm-wide lithium metal sheet (Tianjin Zhongneng Lithium Industry Co., Ltd.) and a 1-meter-long, 50-cm-wide carbon fiber (T300-1K; Weihai Guangwei Composite Materials Co., Ltd.) were placed in a roller press and pressed together. The materials were rolled three times at a pressure of 0.04 to 0.08 MPa in a dry room maintained at a relative humidity of 10% to 20% and a dew point of -20°C to -45°C to obtain the lithium metal sheet-loaded carbon fiber. The carbon fiber was then heat-treated in an atmosphere furnace at 190°C for 0.5 h under an Ar atmosphere at a heating rate of 4°C / min. After the heat treatment, the material was allowed to cool and then rolled again twice to obtain a composite lithium metal electrode material with a thickness of 0.2 mm.

[0032] Example 4: Preparation of composite lithium metal electrode material

[0033] A 1-meter-long, 35-cm-wide lithium metal sheet (Tianjin Zhongneng Lithium Industry Co., Ltd.) and a 1-meter-long, 50-cm-wide carbon fiber sheet (T300-1K; Weihai Guangwei Composite Materials Co., Ltd.) were placed in a roller press and pressed three times at a pressure of 0.04 to 0.08 MPa in a dry room maintained at a relative humidity of 10% to 20% and a dew point of -20°C to -45°C to produce a composite lithium metal electrode material with a thickness of 0.2 mm.

[0034] Example 5: Preparation of composite lithium metal electrode material

[0035] A 1-meter-long, 35-cm-wide lithium metal sheet (Tianjin Zhongneng Lithium Industry Co., Ltd.) and a 1-meter-long, 50-cm-wide carbon fiber sheet (T300-1K; Weihai Guangwei Composite Materials Co., Ltd.) were placed in a roller press and pressed twice at a pressure of 0.04 to 0.08 MPa in a dry room maintained at a relative humidity of 10% to 20% and a dew point of -20°C to -45°C to produce a composite lithium metal electrode material with a thickness of 0.2 mm.

[0036] Example 6: Preparation of composite lithium metal electrode material

[0037] A 1-meter-long, 35-cm-wide lithium metal sheet (Tianjin Zhongneng Lithium Industry Co., Ltd.) and a 1-meter-long, 50-cm-wide carbon fiber sheet (T300-1K; Weihai Guangwei Composite Materials Co., Ltd.) were placed in a roller press and pressed. The press was applied at a pressure of 0.04 to 0.08 MPa in a dry environment with a relative humidity of 10% to 20% and a dew point of -20°C to -45°C. The resulting composite lithium metal electrode material had a thickness of 0.2 mm.

[0038] Example 7: Preparation of lithium metal battery

[0039] (1) The electrode material (positive electrode active material, binder and conductive agent in a mass ratio of 8:1:1) is added to the N-methylpyrrolidone solvent, wherein the weight ratio of N-methylpyrrolidone to the electrode material is 2.6:1. The slurry is then coated on the carbon fiber using a blade coating method at a thickness of 40 μm and dried at 90°C until the solvent is completely evaporated. Finally, a tablet press is used to cut into 12 mm discs to obtain positive electrode discs. Similarly, lithium metal-loaded carbon fiber is used as the negative electrode and cut into 12 mm discs to obtain negative electrode discs.

[0040] (2) Finally, assemble the lithium metal button battery according to the form of the positive electrode, separator, and negative electrode. The specific operation is to place the negative electrode shell with the convexity downward, place the negative electrode disc (coating slurry upward), add 30uL of lithium ion secondary electrolyte (LB 266) in the middle of the negative electrode disc, then place a Whatman separator with a size of 16mm, add 30uL of lithium ion secondary electrolyte (LB 266) in the middle of the separator disc, place the positive electrode disc (coating slurry downward), and add 30uL of lithium ion secondary electrolyte (LB 266) in the middle of the disc; place the gasket, place the spring (convexity upward), and place the positive electrode shell. Place the negative electrode shell upward in the middle, in the lock position, press the hydraulic press to 1000. Unlock and decompress, take out to obtain the lithium metal button battery.

[0041] Example 8: Preparation of lithium metal button battery II

[0042] The preparation method of this embodiment is the same as that of Example 7, the only difference being that the composite lithium metal electrode material used is the composite lithium metal electrode material prepared in Example 2.

[0043] Example 9: Preparation of lithium metal button battery III

[0044] The preparation method of this embodiment is the same as that of Example 7, the only difference being that the composite lithium metal electrode material used is the composite lithium metal electrode material prepared in Example 3.

[0045] Example 10: Preparation of lithium metal button battery IV

[0046] The preparation method of this embodiment is the same as that of Example 7, the only difference being that the composite lithium metal electrode material used is the composite lithium metal electrode material prepared in Example 4.

[0047] Example 11: Preparation of lithium metal button battery

[0048] The preparation method of this embodiment is the same as that of Example 7, the only difference being that the composite lithium metal electrode material used is the composite lithium metal electrode material prepared in Example 5.

[0049] Example 12: Preparation of lithium metal button cell

[0050] The preparation method of this embodiment is the same as that of Example 7, the only difference being that the composite lithium metal electrode material used is the composite lithium metal electrode material prepared in Example 6.

[0051] Example 13: Preparation of lithium metal structure energy storage composite structure battery

[0052] (1) The positive electrode active material (lithium iron phosphate), binder (polyvinylidene fluoride, PVDF) and conductive agent (conductive carbon black, SuperP Li) purchased from Aladdin were added to N-methylpyrrolidone solvent in a mass ratio of 8:1:1, wherein the weight ratio of N-methylpyrrolidone to electrode material (active material, binder and conductive agent) was 2-3:1. The stirred slurry was then coated on carbon fiber by blade coating at a thickness of 30-40 μm, dried at 90°C until the solvent was completely evaporated, and cut to the required size. Similarly, the lithium metal-loaded carbon fiber prepared in Example 1 was cut into the required size as the negative electrode. Then, a structural battery cell was prepared in the order of structural negative electrode, separator, and structural positive electrode.

[0053] (2) The tetrafunctional epoxy resin and pore-forming agent PEG200 purchased from Aladdin were fully stirred at a mass ratio of 1:3 for 20 minutes, and then the curing agent PACM purchased from Aladdin (the mass ratio of resin to curing agent was 100:57.5) was added and stirred again for 20 minutes. After filtering to remove bubbles, the mixture was introduced into a vacuum bag containing a structural battery cell by vacuum infusion and cured in two steps: first, the temperature was raised to 130°C and maintained for 60 minutes, and then the temperature was raised to 180°C and maintained for 30 minutes, with the heating rate being 5°C / min each time, and then naturally cooled to room temperature to obtain a cured battery cell. The cured battery cell was removed and soaked in a ketone or chlorinated hydrocarbon solvent for 24 hours (the same solvent was changed every 5 hours), and vacuum dried at 60-80°C for 12 hours. Finally, the electrolyte was injected, sealed, and allowed to stand for 24 hours to obtain a lithium metal structure energy storage composite structure battery.

[0054] Example 14: Preparation of lithium metal structure energy storage composite structure battery II

[0055] (1) First, cut four pieces of carbon fiber fabric (6 cm × 6 cm) and impregnate them with epoxy resin (4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester (TDE-85): diethylenetriamine (DETA) weight ratio of 80:13) for packaging. Cut two pieces of glass fiber fabric (7 cm × 7 cm), cut a 4 cm × 4 cm square in the middle, and impregnate them with epoxy resin. Cut one Whatman separator (4 cm × 4 cm) and soak it in a Petri dish containing 1M LiTFSI liquid electrolyte for 8 hours.

[0056] (2) Take a clean steel plate, first place two pieces of carbon fiber fabrics soaked in resin, then place the final current collector with a size of 4*4cm, a tab length of 3cm, and a width of 1cm. LFP / CFWF structure positive electrode, add 0.1mL 1M LiTFSI electrolyte (the solvent is 1,3-dioxolane and 1,2-dimethoxyethane, the volume ratio is 1:1, and lithium nitrate with a mass of 1wt% of the total weight is added, and finally stirred at room temperature for 4h to fully dissolve) to moisten, place two cut glass fibers, place a soaked Whatman separator, place a current collector with a size of 4*4cm, a tab length of 3cm, and a width of 1cm. The lithium metal loaded carbon fiber structure negative electrode prepared in Example 1 is placed, and finally two pieces of carbon fiber soaked in resin are placed;

[0057] (3) A composite structure battery was prepared by vacuum bag pressing process, and the battery was placed at a pressure of 0.1 MPa for 24 hours. The concentration of oxygen and water in the glove box was less than 0.1 ppm, and a lithium metal structure energy storage composite structure battery was prepared.

[0058] Example 15: Preparation of lithium metal structure energy storage composite structure battery III

[0059] (1) First, cut 4 pieces of carbon fiber fabric (6 cm × 6 cm) and impregnate them with epoxy resin (4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester (TDE-85): diethylenetriamine (DETA) weight ratio is 80:13) for packaging; cut 2 pieces of glass fiber fabric (7 cm × 7 cm), cut a 4 cm × 4 cm square in the middle, and impregnate them with epoxy resin (4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester (TDE-85): diethylenetriamine (DETA) weight ratio is 80:13); cut 1 piece of Whatman membrane (4 cm × 4 cm) and soak it in a culture dish containing 1M LiTFSI liquid electrolyte for 8 hours;

[0060] (2) Take a clean steel plate, first place two pieces of carbon fiber soaked in resin, then place the final current collector with a size of 4*4cm, a tab length of 3cm, and a width of 1cm. The LFP / CFWF structure positive electrode is added on it with 0.1mL of 1M LiTFSI electrolyte (the solvent is 1,3-dioxolane and 1,2-dimethoxyethane with a volume ratio of 1:1, and lithium nitrate with a mass of 1wt% of the total weight is added. Finally, stir at room temperature for 4h to fully dissolve) to wet it, place two cut glass fibers, place a soaked Whatman separator, place a current collector with a size of 4*4cm, a tab length of 3cm, and a width of 1cm. The lithium metal loaded carbon fiber structure negative electrode prepared in Example 2 is placed, and finally two pieces of carbon fiber soaked in resin are placed;

[0061] (3) The composite structure battery was prepared by vacuum bag pressing process, and was placed at a pressure of 0.1 MPa for 24 hours. The concentration of oxygen and water in the glove box was less than 0.1 ppm, and the lithium metal structure energy storage composite structure battery was obtained.

[0062] Example 16: Preparation of lithium metal structure energy storage composite structure battery IV

[0063] (1) First, cut 4 pieces of carbon fiber fabric (6cm×6cm) and impregnate them with epoxy resin (4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester (TDE-85): diethylenetriamine (DETA) weight ratio of 80:13) for packaging. Cut 2 pieces of glass fiber fabric (7cm×7cm), cut a 4cm×4cm square in the middle, and impregnate it with epoxy resin (4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester (TDE-85): diethylenetriamine (DETA) weight ratio of 80:13). Cut 1 piece of Whatman separator (4cm×4cm) and soak it in a Petri dish containing 1M LiTFSI liquid electrolyte for 8 hours;

[0064] (2) Take a clean steel plate, first place two pieces of carbon fiber soaked in resin, then place the final current collector with a size of 4*4cm, a tab length of 3cm, and a width of 1cm LFP / CFWF structure positive electrode, drip 0.1mL 1M LiTFSI electrolyte on it to wet it, place two cut glass fibers, place a soaked Whatman separator, place the current collector with a size of 4*4cm, a tab length of 3cm, and a width of 1cm prepared in Example 2. The lithium metal loaded carbon fiber structure negative electrode, finally place two more pieces of carbon fiber soaked in resin;

[0065] (3) The composite structure battery was prepared by vacuum bag pressing process, and was placed at a pressure of 0.1 MPa for 24 hours. The concentration of oxygen and water in the glove box was less than 0.1 ppm, and the lithium metal structure energy storage composite structure battery was obtained.

[0066] Test example:

[0067] The lithium metal button batteries prepared in Examples 7 to 8 and the lithium metal structure energy storage composite structure batteries prepared in Examples 13 to 16 were placed in a blue battery test system for 12 hours and then electrochemically tested. The discharge capacity, coulomb efficiency, and capacity after 100 cycles of each group of batteries were tested at a current density of 0.1C. The test was repeated three times. The results are shown in Tables 1 to 2. Figures 2-4 shown.

[0068] Table 1

[0069]

[0070] Table 2

[0071]

[0072] Depend on Figures 2-4 , Tables 1 and 2 show:

[0073] It can be seen from Examples 7 to 8 and Examples 13 to 16 that the composite lithium metal electrode material prepared in the present invention can be used as a negative electrode material in a battery to effectively improve the discharge capacity and cycle performance of the battery.

[0074] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a composite lithium metal electrode material, characterized in that: The preparation method is specifically as follows: a lithium metal sheet and carbon fiber are rolled together for 1 to 3 times to obtain a composite lithium metal electrode material.

2. The method for preparing a composite lithium metal electrode material according to claim 1, wherein: The rolling environment is a dry environment, wherein the relative humidity in the dry environment is 10% to 20% and the dew point temperature is -20°C to -45°C.

3. The method for preparing a composite lithium metal electrode material according to any one of claims 1 to 2, characterized in that: The roller pressing is followed by a secondary treatment.

4. The method for preparing a composite lithium metal electrode material according to any one of claims 3, wherein: The specific steps of the secondary treatment are as follows: heat-treating the composite lithium metal electrode material in an Ar atmosphere, then cooling it and rolling it again to obtain the composite lithium metal electrode material.

5. The method for preparing a composite lithium metal electrode material according to claim 4, characterized in that: The heat treatment temperature is 170° C. to 190° C., the time is 0.5 h to 2 h, and the heating rate is 4° C. / min to 7° C. / min.

6. A composite lithium metal electrode material, characterized in that Prepared by the preparation method according to any one of claims 1 to 5.

7. A composite lithium metal electrode material according to claim 6, characterized in that: The thickness of the composite lithium metal electrode material is 0.1 mm to 0.4 mm.

8. An application of a composite lithium metal electrode material, characterized in that: The composite lithium metal electrode material according to any one of claims 6 to 7 is used in the preparation of a battery.

9. The use of a composite lithium metal electrode material according to claim 8, characterized in that: The composite lithium metal electrode material is used as a negative electrode material in the preparation of a battery.

10. The use of a composite lithium metal electrode material according to claim 9, characterized in that: The battery includes at least one of a lithium metal battery and a lithium metal structure energy storage composite structure battery.

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