Glucose porous carbon silicon-carbon composite negative electrode material and preparation method and application thereof

Abstract

The invention belongs to the field of preparation of negative electrode materials, and particularly relates to a glucose porous carbon silicon-carbon composite negative electrode material as well as a preparation method and application thereof. The preparation method comprises the following steps: firstly, dissolving sodium carboxymethyl cellulose and glucose in deionized water, then freezing the solution, then transferring into a freeze-drying machine for freeze-drying, and finally performing high-temperature carbonization to obtain glucose porous carbon; the nano silicon-carbon composite negative electrode material containing the glucose porous carbon is prepared by the following method: firstly, adding sodium carboxymethyl cellulose into deionized water, stirring and dissolving, then adding nano silicon powder into a sodium carboxymethyl cellulose aqueous solution, performing ultrasonic dispersion, adding the glucose porous carbon into the dispersion liquid, performing ultrasonic stirring and uniform mixing, and performing drying to obtain the nano silicon-carbon composite negative electrode material containing the glucose porous carbon. And finally, carrying out drying treatment in a freeze drying manner to obtain a homogeneous precursor, and carrying out high-temperature carbonization after grinding and fusing to obtain the nano silicon-carbon composite negative electrode material containing glucose porous carbon.

Description

Technical Field

[0001] The present invention belongs to the field of negative electrode material preparation, and in particular relates to a glucose porous carbon silicon-carbon composite negative electrode material and a preparation method and application thereof. Background Art

[0002] Silicon anode materials, with their high capacity (3579mAh / g) and low potential (370mV vs), abundant natural reserves, and stable chemical properties, are the undisputed choice for next-generation high-energy-density anode materials. However, due to issues such as severe volume expansion during charge and discharge, low first-cycle Coulombic efficiency, and low intrinsic conductivity, they are unable to fully utilize their capacity, thus reducing cycle life and affecting their commercial application value. Currently, the current technical route mainly uses nano-silicon / graphite composite systems and carbon coating processes to improve the conductive network and buffer the volume effect. Specifically, nanosizing silicon particles to 50-200nm can shorten the lithium ion diffusion path; constructing a "core-shell" structure with graphite can control the overall expansion rate to 10% to 15%; and a carbon coating (3-5nm) can both enhance electronic conductivity and inhibit excessive SEI film growth. However, nanosilicon still experiences significant volume changes during lithium intercalation and deintercalation, generating significant stress and strain, which causes the surface carbon coating to fall off, resulting in the pulverization of the composite material and a loosening of the bond between the active material and the current collector. This, in turn, causes the silicon material to peel off from the surface of the graphite carrier, losing electrical contact and rapidly decaying the cycling capacity. After multiple expansion and contraction of silicon, the volume expansion of the particles causes the particles to squeeze each other, causing the electrode to crack and fall off, ultimately completely losing electrical contact with the current collector, leading to a sharp drop in capacity and poor cycling stability. Summary of the Invention

[0003] To solve the above problems, the present invention provides a glucose porous carbon silicon-carbon composite negative electrode material, comprising 72-70 wt.% of spherical nano-silicon powder, 3-5 wt.% of sodium carboxymethyl cellulose and 25 wt.% of glucose porous carbon.

[0004] 2. The present invention also provides a method for preparing the above-mentioned glucose porous carbon silicon-carbon composite negative electrode material, comprising the following steps:

[0005] (1) Glucose powder was dissolved in deionized water as a precursor for preparing porous carbon, the precursor was pre-frozen, then freeze-dried, and carbonized in a tube furnace under an argon atmosphere for 3 h to obtain glucose porous carbon;

[0006] (2) adding nano-silicon powder to deionized water and ultrasonically dispersing the nano-silicon powder to obtain a nano-silicon powder dispersion, and then adding sodium carboxymethyl cellulose and ultrasonically stirring and mixing to obtain a homogeneous dispersion;

[0007] (3) adding the glucose porous carbon obtained in step (1) to the homogeneous dispersion of step (2) to allow the precursor liquid to be evenly mixed;

[0008] (4) The homogeneous precursor liquid obtained in step (3) is dried using a freeze dryer. The sample is first placed in a culture dish for pre-freezing, and then transferred to a freeze dryer for freeze drying for 24 hours to remove water from the precursor to obtain a homogeneous precursor mixed with various components;

[0009] (5) The freeze-dried precursor material of step (4) is transferred into a tubular furnace in an argon atmosphere and carbonized at 800-1100° C. for 2-3 hours, and then ground and crushed to obtain a nano-silicon-carbon composite negative electrode material containing glucose porous carbon.

[0010] Furthermore, the freeze-drying time in step (1) is 24 to 48 hours.

[0011] The present invention also provides application of the glucose porous carbon silicon-carbon composite negative electrode material in battery materials.

[0012] The present invention has the following beneficial effects:

[0013] The present invention proposes a silicon-carbon composite negative electrode material of glucose porous carbon and a preparation method thereof. The porous material is prepared by glucose and then compounded with nano-silicon to prepare a porous silicon / carbon composite material. On the one hand, the nano-silicon material can be well implanted into the pores and layer gaps of the porous carbon to adapt to the volume change of the nano-silicon material. On the other hand, the porous carbon can form a stable conductive channel in the nano-silicon, preventing the nano-silicon from falling off during repeated volume changes and being unable to participate in charging and discharging, and being unable to exert its capacity, thereby obtaining a longer cycle life. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 The SEM photos of the glucose porous carbon prepared by the present invention and the nano-silicon-carbon composite negative electrode material prepared using the glucose porous carbon;

[0016] Figure 2 The cycle life curves of the silicon-carbon composite material prepared in Example 1 of the present invention, the pure silicon in Comparative Example 1, and Comparative Example 2 are shown. By introducing porous carbon, the cycle performance of the material is significantly improved. DETAILED DESCRIPTION

[0017] Various exemplary embodiments of the present invention are now described in detail. Unless otherwise specified, the methods in the examples are conventional methods. Unless otherwise specified, the reagents used are conventional commercially available reagents or reagents prepared using conventional methods. This detailed description should not be considered a limitation of the present invention, but rather should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0018] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0019] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0020] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0021] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0022] Example 1

[0023] 1) Weighing 60 g of glucose powder and 9 g of ethyl cellulose, adding them to 600 g of deionized water and stirring and dissolving them to obtain an aqueous solution with a solid content of 10 wt.%, then freeze-drying the sample using a freeze dryer. The freeze-dried sample was transferred to a tube furnace and carbonized at 800°C for 3 h under an argon atmosphere to obtain a porous glucose carbon;

[0024] 2) Weighing 20 g of sodium carboxymethyl cellulose and adding it to 1980 g of deionized water with stirring to dissolve, then weighing 60 g of nano-silicon powder and adding it to the carboxymethyl cellulose aqueous solution and ultrasonically dispersing it to obtain a 3 wt.% nano-silicon powder dispersion, then adding 30 g of the glucose porous carbon prepared in step 1) to the nano-silicon powder dispersion with ultrasonic stirring to mix evenly to obtain a homogeneous dispersion;

[0025] 3) The homogeneous precursor prepared in step 2) is placed in a refrigerator for pre-freezing. After the pre-freezing is completed, the sample is transferred to a freeze dryer and freeze-dried at -60°C for 24 hours to remove water from the precursor to obtain a homogeneous precursor mixed with all components;

[0026] 4) Grinding the homogeneous precursor from step 3) for 20 minutes to enhance the mechanical bonding strength of the components;

[0027] 5) The precursor material after fusion in step 4) was transferred into a vacuum carbonization furnace for carbonization treatment at 1100° C. under argon atmosphere for 3 h, and then ground and crushed to obtain a nano-silicon-carbon composite negative electrode material of glucose porous carbon.

[0028] The nano-silicon-graphite composite negative electrode material prepared in this embodiment was prepared into a negative electrode sheet and assembled into a 2032 button battery to test the cycle life. The material performance data are shown in Table 1, and the cycle life curve is shown in Figure 2 The battery cycle performance test method is as follows: first discharge to 0.005V at current densities of 100mA / g, 200mA / g, 500mA / g, 800mA / g, and 1000mA / g, let it rest for 3 minutes, then charge to 1.5V at the corresponding current density to test the rate performance, and then perform the cycle performance test at a current density of 200mA / g.

[0029] Table 1: Performance test results

[0030]

[0031] Comparative Example 1

[0032] 1) Weighing 20 g of sodium carboxymethyl cellulose and adding it to 2000 g of deionized water, stirring and dissolving it, then weighing 60 g of nano-silicon powder and adding it to the carboxymethyl cellulose aqueous solution and ultrasonically dispersing it to obtain a nano-silicon powder dispersion;

[0033] 2) The homogeneous precursor prepared in step 1) is placed in a refrigerator for pre-freezing. After the pre-freezing is completed, the sample is transferred to a freeze dryer and freeze-dried at -60°C for 24 hours to remove water from the precursor to obtain a homogeneous precursor mixed with all components;

[0034] 3) The precursor material obtained in step 2) was transferred into a vacuum carbonization furnace and carbonized at 1000° C. for 3 h under argon atmosphere, and then ground and crushed to obtain a nano-silicon-carbon composite negative electrode material of glucose porous carbon.

[0035] The nano-silicon material without glucose porous carbon in Comparative Example 1 was assembled into a 2032 button battery to test the cycle life. The material performance data are shown in Table 1, and the cycle life curve is shown in Figure 2 shown.

[0036] Comparative Example 2

[0037] 1) Weigh 60 g of glucose powder and 9 g of ethyl cellulose and add them to 600 g of deionized water, stir and dissolve them, then freeze-dry the sample using a freeze dryer. Transfer the freeze-dried sample to a tube furnace and carbonize it at 800°C for 3 h under an argon atmosphere to obtain glucose porous carbon;

[0038] The glucose porous carbon material in Comparative Example 2 was assembled into a 2032 button battery to test the cycle life. The material performance data are shown in Table 1, and the cycle life curve is shown in Figure 2 shown.

[0039] Example 2

[0040] 1) Weighing 90 g of glucose powder and 9 g of ethyl cellulose, adding them to 600 g of deionized water and stirring and dissolving them to obtain an aqueous solution with a solid content of 15 wt.%, then freeze-drying the sample using a freeze dryer. The freeze-dried sample was transferred to a tube furnace and carbonized at 800°C for 3 h under an argon atmosphere to obtain a porous glucose carbon;

[0041] 2) Weighing 20 g of sodium carboxymethyl cellulose and adding it to 1180 g of deionized water with stirring to dissolve, then weighing 60 nanometers of silicon powder and adding it to the carboxymethyl cellulose aqueous solution and ultrasonically dispersing it to obtain a 5 wt.% nano-silicon powder dispersion, then adding 30 g of the glucose porous carbon prepared in step 1) to the nano-silicon powder dispersion with ultrasonic stirring to mix evenly to obtain a homogeneous dispersion;

[0042] 3) The homogeneous precursor prepared in step 2) is placed in a refrigerator for pre-freezing. After the pre-freezing is completed, the sample is transferred to a freeze dryer and freeze-dried at -60°C for 48 hours to remove water from the precursor to obtain a homogeneous precursor containing all components;

[0043] 4) Grinding the homogeneous precursor from step 3) for 20 minutes to enhance the mechanical bonding strength of the components;

[0044] 5) The precursor material after fusion in step 4) is transferred into a vacuum carbonization furnace for carbonization treatment at 1000° C. under argon atmosphere for 3 hours, and then ground and crushed to obtain a nano-silicon-carbon composite negative electrode material of glucose porous carbon.

[0045] Example 3

[0046] 1) Weighing 60 g of glucose powder and 6 g of ethyl cellulose, adding them to 594 g of deionized water and stirring and dissolving them to obtain an aqueous solution with a solid content of 10 wt.%, then freeze-drying the sample using a freeze dryer. The freeze-dried sample was transferred to a tube furnace and carbonized at 800°C for 3 h under an argon atmosphere to obtain a porous glucose carbon;

[0047] 2) Weighing 15 g of sodium carboxymethyl cellulose and adding it to 1485 g of deionized water with stirring to dissolve, then weighing 60 nanometers of silicon powder and adding it to the carboxymethyl cellulose aqueous solution and ultrasonically dispersing it to obtain a 4 wt.% nano-silicon powder dispersion, then adding 30 g of the porous glucose carbon prepared in step 1) to the nano-silicon powder dispersion with ultrasonic stirring to mix evenly to obtain a homogeneous dispersion;

[0048] 3) The homogeneous precursor prepared in step 2) is placed in a refrigerator for pre-freezing. After the pre-freezing is completed, the sample is transferred to a freeze dryer and freeze-dried at -60°C for 24 hours to remove water from the precursor to obtain a homogeneous precursor mixed with all components;

[0049] 4) Grinding the homogeneous precursor from step 3) for 20 minutes to enhance the mechanical bonding strength of the components;

[0050] 5) The precursor material after fusion in step 4) is transferred into a vacuum carbonization furnace and carbonized at 900° C. for 3 h under argon atmosphere, and then ground and crushed to obtain a nano-silicon-carbon composite negative electrode material of glucose porous carbon.

[0051] Example 4

[0052] 1) Weighing 80 g of glucose powder and 8 g of ethyl cellulose, adding them to 526 g of deionized water and stirring and dissolving them to obtain an aqueous solution with a solid content of 15 wt.%, then freeze-drying the sample using a freeze dryer. The freeze-dried sample was transferred to a tube furnace and carbonized at 800°C for 3 h under an argon atmosphere to obtain a porous glucose carbon;

[0053] 2) Weighing 20 g of sodium carboxymethyl cellulose and adding it to 2000 g of deionized water with stirring to dissolve, then weighing 60 nanometers of silicon powder and adding it to the carboxymethyl cellulose aqueous solution and ultrasonically dispersing it to obtain a 3 wt.% nano-silicon powder dispersion, then adding 30 g of the porous glucose carbon prepared in step 1) to the nano-silicon powder dispersion with ultrasonic stirring to mix evenly to obtain a homogeneous dispersion;

[0054] 3) The homogeneous precursor prepared in step 2) is placed in a refrigerator for pre-freezing. After the pre-freezing is completed, the sample is transferred to a freeze dryer and freeze-dried at -60°C for 36 hours to remove water from the precursor to obtain a homogeneous precursor mixed with all components;

[0055] 4) Grinding the homogeneous precursor from step 3) for 20 minutes to enhance the mechanical bonding strength of the components;

[0056] 5) The precursor material after fusion in step 4) is transferred into a vacuum carbonization furnace and carbonized at 800° C. for 3 h under argon atmosphere, and then ground and crushed to obtain a nano-silicon-carbon composite negative electrode material of glucose porous carbon.

[0057] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A glucose porous carbon silicon-carbon composite negative electrode material, characterized in that: The invention comprises 72-70 wt.% of spherical nano silicon powder, 3-5 wt.% of sodium carboxymethyl cellulose and 25 wt.% of glucose porous carbon.

2. The method for preparing the glucose porous carbon silicon-carbon composite negative electrode material according to claim 1, wherein: The following steps are involved: (1) Glucose powder was dissolved in deionized water as a precursor for preparing porous carbon, the precursor was pre-frozen, then freeze-dried, and carbonized in a tube furnace under an argon atmosphere for 3 h to obtain glucose porous carbon; (2) adding nano-silicon powder to deionized water and ultrasonically dispersing the nano-silicon powder to obtain a nano-silicon powder dispersion, and then adding sodium carboxymethyl cellulose and ultrasonically stirring and mixing to obtain a homogeneous dispersion; (3) adding the glucose porous carbon obtained in step (1) to the homogeneous dispersion of step (2) to allow the precursor liquid to be evenly mixed; (4) The homogeneous precursor liquid obtained in step (3) is dried using a freeze dryer. The sample is first placed in a culture dish for pre-freezing, and then transferred to a freeze dryer for freeze drying for 24 hours to remove water from the precursor to obtain a homogeneous precursor mixed with various components; (5) The freeze-dried precursor material of step (4) is transferred into a tubular furnace in an argon atmosphere and carbonized at 800-1100° C. for 2-3 hours, and then ground and crushed to obtain a nano-silicon-carbon composite negative electrode material containing glucose porous carbon.

3. The method according to claim 2, characterized in that The freeze-drying time in step (1) is 24 to 48 hours.

4. Use of the glucose porous carbon silicon-carbon composite negative electrode material as claimed in claim 1 in battery materials.

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