Hierarchical porous carbon-embedded Sn composite material, and preparation method and application thereof
By preparing hierarchical porous carbon-intercalated Sn composite materials, the problems of low capacity and volume expansion of lithium-ion battery anode materials were solved, achieving efficient electrochemical reaction and stable energy storage performance.
Patent Information
- Application Number
- CN202311354840.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-19
- Publication Date
- 2026-02-06
- Estimated Expiration
- 2043-10-19
AI Technical Summary
The theoretical capacity of graphite, an existing lithium-ion battery anode material, is low. The volume expansion of Sn anode material during charge and discharge leads to a decrease in battery cycle life and electrochemical performance. Furthermore, the formation of SEI film and the generation of multi-level Sn-Li phases affect the material performance.
A hierarchical porous carbon-embedded Sn composite material was prepared by mixing high molecular organic matter and tin salt in N,N-dimethylformamide and heating and stirring to form a porous framework, followed by carbonization and reduction treatment to form a composite material with large, medium and micropore structures.
This improved the structural stability of the anode material, shortened the lithium-ion diffusion path, buffered the effects of volume expansion, increased the specific surface area, enhanced electrochemical reaction efficiency and coulombic efficiency, and ensured high-efficiency energy storage performance.
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Figure CN117361494B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of electrode material preparation, and particularly relates to a hierarchical porous carbon-embedded Sn composite material and a preparation method and application thereof. BACKGROUND
[0002] With the rapid development of society, the resources of traditional energy such as oil, natural gas and coal are decreasing, and the environmental pollution problems caused by the consumption of traditional energy are becoming increasingly serious. The development and utilization of new energy is an important way to realize sustainable development and protect the natural environment and natural resources on which human beings depend. The difficulty of new energy development and utilization lies in collection, storage and conversion, and the electrochemical energy storage and conversion technology (batteries, supercapacitors, etc.) can effectively solve these problems. Lithium ion batteries can effectively resolve the crisis caused by fossil energy due to their green and low-carbon, efficient energy storage, no memory effect and other characteristics, and have been developed and widely applied.
[0003] The negative electrode material plays a role in energy storage and release in the battery, and is an important component of the battery. The quality of the negative electrode material will directly affect the performance of the battery. The theoretical capacity of the mainstream negative electrode material graphite on the market is low (372 mAh g -1 ), which cannot meet the future rapid development and wide application of lithium ion batteries. Therefore, it is an important requirement for the development of lithium ion batteries to find and develop negative electrode materials with high energy density and high performance.
[0004] Metal Sn has the advantages of abundant crustal reserves, excellent electrical conductivity and high theoretical capacity (993 mAh g -1 ), and is considered to be one of the most promising candidate materials to replace commercial-grade graphite negative electrode materials. However, the lithium ion intercalation / deintercalation behavior occurring on the negative electrode during charging and discharging will cause severe volume expansion of Sn, which will cause the pulverization and shedding of the electrode material, resulting in the decline of the electrochemical performance such as the cycle life and capacity of the battery. This problem largely restricts the practical application of Sn as a negative electrode material of lithium ion batteries. In addition, the formation of SEI film and the generation of multi-stage Sn-Li phases will occur during the energy storage reaction of Sn negative electrode materials, which not only reduces the intrinsic electrical conductivity and reaction kinetics efficiency of the negative electrode material, but also causes serious irreversible capacity, ultimately resulting in a low first-cycle coulombic efficiency of the negative electrode material. At the same time, these problems will also cause a continuous decline in the reversible capacity of the negative electrode material during the energy storage process. SUMMARY
[0005] One of the purposes of the present application is to provide a preparation method of a hierarchical porous carbon-embedded Sn composite material, so as to improve the stability of the structure of the prepared negative electrode material, slow down the influence of the energy storage volume effect, and thus improve the energy storage performance.
[0006] To solve the above technical problems, the application adopts the following technical solutions: a preparation method of hierarchical porous carbon embedded Sn composite material, comprising the following steps:
[0007] (1) Constructing a precursor: high molecular organic matter and tin salt are dispersed and dissolved in N, N-dimethylformamide (DMF) in the order of sequence and continuously heated and stirred to form a mixed solution, the mixed solution is placed in deionized water, and a tin source precursor material with a high molecular hierarchical porous skeleton is obtained by filtration.
[0008] (2) Carbonization and reduction treatment: the tin source precursor material is heat treated to carbonize the high molecular hierarchical porous skeleton in the tin source precursor material and reduce the tin salt to metal Sn, so that the hierarchical porous carbon embedded Sn composite material is obtained.
[0009] Preferably, in step (1), the high molecular organic matter is a thermoplastic high molecular organic matter, and is selected as one of polyvinylpyrrolidone (PVP) and polyacrylonitrile (PAN) or a combination of the two, and the content of N, N-dimethylformamide in the mixed solution is 80 wt%.
[0010] Preferably, the molecular weight of the polyvinylpyrrolidone is between 1 million and 1.5 million, and the molecular weight of the polyacrylonitrile is between 50 thousand and 100 thousand.
[0011] Preferably, the tin salt is an organic salt or an inorganic salt containing Sn element, such as SnCl4 or C4H6O4Sn or SnSO4.
[0012] More preferably, in step (1), after the mixed solution is formed, it is cooled to room temperature and then slowly added dropwise into deionized water to cause phase separation, filtration, and freeze-drying to shape the obtained tin source precursor material with a high molecular hierarchical porous skeleton, so as to avoid structural damage and destruction of the tin source precursor material in the subsequent preparation process. The specific method of phase separation is: first, the high molecular component (one of polyvinylpyrrolidone and polyacrylonitrile or a combination of the two) is added to DMF to form a mixed solution with certain viscosity, so as to ensure that the Sn salt added subsequently can be uniformly dispersed or dissolved in the mixed solution. When the mixed solution is dropped into deionized water, the strong solubility of DMF in water forces the low water-soluble precursor component to be separated out, forming a hierarchical porous structure.
[0013] More preferably, in step (1), the heating and stirring method is: heating and stirring at a water bath heating temperature of 80 ℃ for 40 min.
[0014] More preferably, in step (2), the atmosphere during carbonization and reduction treatment is a mixed gas of argon and hydrogen, the heat treatment temperature is 700 ℃, the heating rate is 3 ℃ / min, and the holding time is 4 hours.
[0015] In addition, the present invention also provides a hierarchical porous carbon-embedded Sn composite material, which is prepared by the above-described method for preparing hierarchical porous carbon-embedded Sn composite material.
[0016] Furthermore, the present invention also provides an application of the above-mentioned hierarchical porous carbon-intercalated Sn composite material. Specifically, the hierarchical porous carbon-intercalated Sn composite material can be applied to lithium-ion battery anode materials or sodium-ion battery anode materials.
[0017] The hierarchical porous carbon-intercalated Sn composite material provided by this invention can play a good role in lithium-ion battery systems. The macroporous structure can promote the diffusion of electrolyte in the electrode material and improve wettability; the mesoporous structure can shorten the diffusion distance of ions to the active sites on the electrode material; and the microporous structure can increase the active sites and ion adsorption capacity of the electrode material.
[0018] Compared with existing technologies, the metallic Sn in the hierarchical porous carbon-embedded Sn composite material of this invention possesses excellent electronic conductivity. The conductivity of the material is further enhanced after carbonization. Furthermore, its unique and well-developed pore structure not only shortens the Li... + The diffusion path of the composite material accelerates the rapid migration of ions and effectively buffers the volume expansion generated during the charging and discharging of the Sn anode material, mitigating the impact of the energy storage volume effect. Furthermore, the porous carbon component increases the specific surface area of the material, allowing for thorough electrolyte wetting and ensuring efficient electrochemical reactions, thereby enhancing the electrochemical performance of the Sn anode material. This composite material promotes efficient electrochemical reactions, playing a positive role in achieving high first-cycle coulombic efficiency and reversible capacity in the anode material. It enables efficient reaction kinetics, strengthens energy storage activity, and ultimately ensures the anode material possesses excellent energy storage performance. Attached Figure Description
[0019] Figure 1 The image shows the X-ray diffraction (XRD) phase analysis of the hierarchical porous carbon-embedded Sn composite material in the examples.
[0020] Figure 2 Images (a) and (b) are scanning electron microscope (SEM) images of the hierarchical porous carbon-embedded Sn composite material in the examples.
[0021] Figure 3 The graph shows the charge-discharge performance of the hierarchical porous carbon-embedded Sn composite material in the example at a current density of 100 mA / g.
[0022] Figure 4 The following are rate performance diagrams of the graded porous carbon-embedded Sn composite material and commercial Sn anode at different current densities in the examples.
[0023] Figure 5 The cycling performance graphs of the hierarchical porous carbon-embedded Sn composite material and the commercial Sn negative electrode material in the examples at a constant current density of 1000 mA / g. DETAILED DESCRIPTION
[0024] For the convenience of understanding of those skilled in the art, the present application is further described below in conjunction with the examples and the accompanying drawings, and the content mentioned in the examples is not a limitation on the present application.
[0025] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and the values are approximate values and should be understood as including values approximately near these ranges and values within these ranges. For ranges of values, the endpoints of the ranges are included in the ranges, and the endpoints and the individual points within the ranges are combinable to create new ranges of values that are not specifically disclosed.
[0026] A preparation method of a hierarchical porous carbon-embedded Sn composite material, comprising the following steps:
[0027] (1) Constructing a tin source precursor by phase separation: 0.5 g of PVP, 0.5 g of PAN, 1 g of SnCl4, and 10 ml of DMF are mixed, heated in a water bath at 80°C, and stirred for 40 min to obtain a mixed solution. The mixed solution is slowly added dropwise into deionized water after being cooled to room temperature to undergo phase separation, filtered, and freeze-dried to shape to obtain a micron-structured tin source precursor material with a high-molecular hierarchical porous framework. The content of DMF in the mixed solution is 80 wt%.
[0028] (2) Carbonization and reduction treatment: the tin source precursor material is subjected to heat treatment so that the high-molecular hierarchical porous framework in the tin source precursor material is carbonized, and SnCl4 is reduced to Sn to obtain a hierarchical porous carbon-embedded Sn composite material (denoted as Sn / C in this example). The temperature of the heat treatment is 700°C, the heating rate is 3°C / min, and the holding time is 4 hours.
[0029] The porous characteristics and structure of the hierarchical porous carbon-embedded Sn composite material prepared in this example are shown in Figure 1 and Figure 2 , wherein Figure 1 is an X-ray diffraction (XRD) phase analysis graph of the hierarchical porous carbon-embedded Sn composite material, Figure 2 , wherein (a) and (b) are scanning electron microscope (SEM) graphs of the hierarchical porous carbon-embedded Sn composite material.
[0030] The hierarchical porous carbon-embedded Sn composite material prepared in the above example is applied to a negative electrode sheet material, and its performance is tested through experiments.
[0031] Experimental Example
[0032] The hierarchical porous carbon-embedded Sn composite (Sn / C) prepared in the above embodiment was mixed with a conductive agent (acetylene black) and a binder (polyvinylidene fluoride PVDF) at a ratio of 7:2:1 to form an active material slurry, which was coated on a copper foil and dried (vacuum drying conditions: temperature 90 °C, time 12 h) to obtain a negative electrode sheet material.
[0033] The negative electrode sheet was cut, and a lithium metal sheet was used as the counter electrode. A separator, electrolyte, and a button cell packaging shell (CR2032) were used to assemble a button cell in a glove box. Comparative Example
[0034] The only difference between the present comparative example and the experimental example is that the hierarchical porous carbon-embedded Sn composite was replaced with a commercial Sn (denoted as Sn). The method for preparing the negative electrode sheet material and assembling the battery was the same as that of the experimental example.
[0035] Experimental Test
[0036] The negative electrode materials of the examples and the comparative example were subjected to electrochemical performance testing using a Neware test system. The testing method included:
[0037] 1) The cycle performance of the Sn / C negative electrode material was measured at a current density of 100 mA / g.
[0038] 2) The rate performance of the Sn / C negative electrode and Sn negative electrode materials was measured at current densities of 200, 400, 600, 1000, and 200 mA / g.
[0039] 3) The cycle performance of the Sn / C negative electrode and Sn negative electrode materials was measured at a current density of 1000 mA / g.
[0040] Figure 3 The cycle performance of Sn / C applied to a lithium ion battery at a current density of 100 mA / g is shown in the graph. As can be seen from the graph, the first cycle of Sn / C exhibited a high specific capacity of 1121.15 mAh / g, and exhibited an ultra-high coulombic efficiency of 97.39%. After 60 charge-discharge cycles, it still maintained 798.12 mA h / g, proving that the material has excellent lithium storage performance and outstanding structural stability.
[0041] Figure 4The Sn / C and Sn negative electrode applied to the lithium ion battery rate performance graph is shown. As can be seen from the graph, the Sn / C of the application is applied to the lithium ion battery at a current density of 200 mA / g, 400 mA / g, 600 mA / g, and 1000 mA / g, respectively, to provide a stable specific capacity of 861.21 mAh / g, 749.63 mAh / g, 714.26 mAh / g, and 660.22 mAh / g. When the current density is restored to a small current of 200 mA / g after discharging at a large current, the specific capacity of the sample still remains at 760.88 mAh / g, confirming that the material has excellent rate performance. As can be seen from the graph, the specific capacity of the commercial Sn electrode is only 545.27 mAh / g even at a small current density of 200 mA / g, and the specific capacity rapidly decays to 80.01 mAh / g after 5 cycles. After large current cycling, when the current density returns to a small current density of 200 mA / g, the specific capacity has a very obvious downward trend, proving that the structural stability of the material is destroyed when subjected to large current cycling, thereby exhibiting poor rate performance.
[0042] Figure 5 The Sn / C and commercial Sn applied to the lithium ion battery cycle performance comparison graph is shown. As can be seen from the graph, the Sn / C composite material of the application applied to the lithium ion battery exhibits excellent cycle stability. At a current density of 1000 mA / g, the initial discharge specific capacity can reach 670.15 mAh / g, the first cycle coulombic efficiency is 91.2%, and the first cycle coulombic efficiency is better. The reversible capacity of 500 mAh / g is maintained for more than 250 cycles, the capacity retention rate is 90.82%, and the coulombic efficiency is almost close to 100%; as a comparative object, the Sn negative electrode material applied to the lithium ion battery has a first discharge specific capacity of only 218.75 mAh / g, and after 50 cycles, the capacity retention rate is only 6.54%, and the reversible capacity is far less than that of the Sn / C negative electrode.
[0043] As can be seen from the above experimental tests, the hierarchical porous carbon embedded Sn composite material provided by the application can obtain good electrochemical performance and realize efficient electrochemical reaction. When applied to the negative electrode material, it can improve the stability of the structure of the negative electrode material, slow down the influence of the energy storage volume effect, play a positive role in realizing the high first cycle coulombic efficiency and reversible capacity of the negative electrode material, and ensure that the negative electrode material has good energy storage performance. It has good application prospects in the field of lithium ion battery and sodium ion battery negative electrode materials.
[0044] In order to make the ordinary skilled in the art more convenient to understand the improvement of the present application relative to the prior art, some drawings and descriptions of the present application have been simplified, and the above examples are the preferred implementation of the present application, in addition to which, the present application can be implemented in other ways, and any obvious replacement within the concept of the present technical solution does not deviate from the protection scope of the present application.
Claims
1. A method for producing a hierarchically porous carbon-embedded Sn composite material, characterized by, Comprise the following steps: (1) Constructing precursor: 0.5 g PVP, 0.5 g PAN, 1 g SnCl4 and 10 ml DMF are mixed, heated with 80 DEG C water bath, stirred for 40 min, the mixed solution is cooled to room temperature, then slowly dropwise added into deionized water to occur phase separation, filtration, freeze-drying shaping to obtain micron structure of tin source precursor material with high molecular hierarchical porous framework; wherein the content of DMF in the mixed solution is 80 wt%; (2) Carbonization and reduction treatment: the tin source precursor material is heat treated, so that the high molecular hierarchical porous framework in the tin source precursor material is carbonized, and SnCl4 is reduced to Sn, to obtain hierarchical porous carbon embedded Sn composite material; wherein the temperature of heat treatment is 700 DEG C, the heating rate is 3 DEG C / min, and the holding time is 4 hours.
2. The method of claim 1, wherein: The molecular weight of the polyvinylpyrrolidone is between 1 million and 1.5 million; the molecular weight of the polyacrylonitrile is between 50 thousand and 100 thousand.
3. A hierarchically porous carbon-embedded Sn composite material, characterized by: The hierarchical porous carbon embedded Sn composite material is prepared by the preparation method of any one of claims 1-2.
4. Use of the hierarchically porous carbon-embedded Sn composite material of claim 3, characterized in that: The hierarchical porous carbon embedded Sn composite material is applied to lithium ion battery negative material or sodium ion battery negative material.