Composite nanoflower rich in Cu4SnS4 as well as preparation method and application of composite nanoflower

Abstract

The invention discloses a preparation method of composite nanoflowers rich in Cu4SnS4, which comprises the following steps: 1) dissolving copper salt in a proper amount of ethanol to obtain a copper salt solution; 2) adding tin salt into the copper salt solution, and stirring until the tin salt is completely dissolved; 3) dissolving thiourea in a proper amount of ethanol to obtain a thiourea solution; (4) mixing the solution in the step (2) and the solution in the step (3), and stirring to form gel; 5) performing ultrasonic treatment on the gel at a certain temperature and stirring to form a dispersed emulsion; 6) transferring the dispersed emulsion into a hydrothermal reaction kettle for solvothermal reaction; 7) performing centrifugation or suction filtration on the reaction product, and drying; and 8) carrying out heat treatment on the dried product in an inert atmosphere to obtain the CTS material with high content of Cu4SnS4 and compounded with a small amount of Cu7.2 S4. The long cycle and capacity of the prepared CTS material are remarkably superior to those of existing similar Cu-Sn-S composite materials, and the CTS material is suitable for further popularization and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials and specifically relates to a Cu-rich 4 S N 4 Composite nanoflowers and their preparation method and application. Background Art

[0002] As a hybrid lithium storage electrode material that combines conversion and alloy reaction mechanisms, CTS electrode materials take into account the advantages of high specific capacity and moderate volume change rate of both. However, most of the CTS electrode materials reported so far are Cu 2 S N 3 Nanoparticles have characteristics such as large volume changes and poor reversibility of conversion reactions during the cycle, resulting in poor electrochemical performance.

[0003] According to the calculation results of density functional theory (DFT), the volume expansion rate, lithium insertion and extraction potential and alloy formation enthalpy of different CTS phases are different. 4 S N 4 It exhibits higher capacity and smaller volume expansion during the lithiation process, which means that the material can maintain better structural stability during charge and discharge cycles, thereby significantly improving the cycle life. In addition, there is a relatively large interplanar spacing in its crystal structure, which provides a larger effective channel for the embedding of lithium ions. In addition, the gap between its oxidation and reduction peak potentials is generally small, which indicates that it has higher reversibility in electrochemical reactions. These characteristics help to increase the charge and discharge rate of the battery, making it more suitable for high-rate and long-cycle applications.

[0004] Although Cu 4 S N 4 Although it has shown many advantages in electrochemical performance, its practical application still faces some challenges. First, the synthesis of high-purity Cu 4 S N 4 It is still difficult, and inappropriate reaction temperature and time may produce other CTS phases (such as Cu 2 S N 3 and Cu 3 S N 4 etc.), which may affect the reversible capacity and cycle stability of the battery. Secondly, improving the reversibility of the conversion reaction has always been a difficult problem associated with CTS electrodes. Therefore, developing new synthetic strategies to regulate the phase composition and thus improve the reversibility of the conversion reaction has become an important research direction. Summary of the invention

[0005] In order to overcome the above problems, the present invention aims to provide a Cu-rich 4 S N 4 Composite nanoflowers and their preparation method and application.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] The present invention provides a Cu-rich 4 S N 4 The preparation method of the composite nanoflower comprises the following steps:

[0008] 1) dissolving copper salt in an appropriate amount of ethanol to obtain a copper salt solution;

[0009] 2) adding tin salt to the copper salt solution and stirring until completely dissolved;

[0010] 3) dissolving thiourea in an appropriate amount of ethanol to obtain a thiourea solution;

[0011] 4) mixing the solution in step 2) and step 3) and forming a gel by stirring;

[0012] 5) subjecting the gel to ultrasonic treatment and stirring at a certain temperature to form a dispersed emulsion;

[0013] 6) transferring the dispersed emulsion to a hydrothermal reactor for solvent thermal reaction;

[0014] 7) drying the reaction product after centrifugation or suction filtration;

[0015] 8) The dried product is heat treated in an inert atmosphere to obtain a high-content Cu 4 S N 4 And compound a small amount of Cu 7.2 S 4 CTS materials.

[0016] As a possible implementation, further, in step 1), the amount of the copper salt is 2 to 4 mmol, and the concentration of the copper salt solution is 0.05 to 0.15 mol / L;

[0017] The copper salt is selected from any one or more of copper chloride, copper carbonate, copper sulfate and copper acetate.

[0018] As a possible implementation mode, further, in step 2), the amount of tin salt added is 1 mmol;

[0019] The tin salt can be selected from any one or more of tin tetrachloride, tin sulfate, and tin acetate.

[0020] As a possible implementation manner, further, in step 3), the amount of thiourea used is 4 mmol, and the concentration of the thiourea solution is 0.08-0.2 mol / L.

[0021] As a possible implementation manner, further, in step 5), the temperature is 20-50° C., and the ultrasonic power is 50-100W.

[0022] As a possible implementation manner, further, in step 6), the dispersed emulsion is transferred to a hydrothermal reactor and heated at 100 to 200° C. for 2 to 20 hours.

[0023] As a possible implementation, further, in step 7), the dried product is heat treated in argon at 500°C for 4 hours to obtain a high-content Cu 4 S N 4 And compound a small amount of Cu 7.2 S 4 CTS materials.

[0024] As a possible implementation, further, the Cu in the CTS material 4 S N 4 Cu accounts for 75.98%; 7.2 S 4 Accounting for 24.02%.

[0025] Based on the above, the present invention also provides a Cu-rich 4 S N 4 The composite nanoflower is prepared by the above preparation method.

[0026] The above Cu-rich 4 S N 4 Composite nanoflowers can be used in lithium batteries.

[0027] The beneficial effects of the present invention are as follows:

[0028] The present invention can effectively reduce other CTS phases (such as Cu 2 S N 3 and Cu 3 S N 4 The production of high-content Cu 4 S N 4 And compound a small amount of Cu 7.2 S 4 The CTS material can effectively improve the reversibility of the conversion reaction, alleviate the impact of volume change on battery performance, greatly improve the lithiation performance, and improve the stability of lithium battery cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0030] Figure 1 The precursor [Cu(CSN 2 H 4 ) 2 ]SEM image of Cl;

[0031] Figure 2 The SEM and XRD diagrams of the CTS material prepared in Example 1; (Figure a represents the SEM diagram of the CTS material; Figure b represents the XRD diagram of the CTS material)

[0032] Figure 3 The charge-discharge curve and long cycle performance diagram of the button lithium battery assembled using the CTS material prepared in Example 1; (Figure a shows the charge-discharge curve of the button lithium battery; Figure b shows the long cycle performance of the button lithium battery)

[0033] Figure 4 This is a performance comparison chart of the CTS material prepared in the present invention and the existing similar Cu-Sn-S material. (Thiswork in the figure corresponds to the CTS material prepared in Example 1, and the numeric superscript in the upper right corner of each material indicates the source of the material, for example: Cu 4 S N 4 [1] Indicates that Cu 4 S N 4 The material disclosed in reference [1]) DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] The present invention provides a Cu-rich 4 S N 4 The preparation method of the composite nanoflower comprises the following steps:

[0036] 1) Dissolve 2-4 mmol of copper salt in an appropriate amount of ethanol to obtain a 0.05-0.15 mol / L copper salt solution; the copper salt can be copper chloride, copper carbonate, copper sulfate, copper acetate, etc.

[0037] 2) adding 1 mmol of tin salt to the copper salt solution and stirring until completely dissolved; the tin salt may be tin tetrachloride, tin sulfate, tin acetate, etc.;

[0038] 3) Dissolve 4 mmol of thiourea in an appropriate amount of ethanol to obtain a 0.08-0.2 mol / L thiourea solution;

[0039] 4) mixing the solution in step 2) and step 3) and forming a gel by stirring;

[0040] 5) ultrasonically treating the gel at 20-50° C. (ultrasonication power is 50-100 W) and stirring to form a dispersed emulsion;

[0041] 6) Transfer the dispersed emulsion to a hydrothermal reactor and heat at 100-200°C for 2-20 hours;

[0042] 7) drying the reaction product after centrifugation or suction filtration;

[0043] 8) The dried product was heat treated at 500°C for 4 h in an argon atmosphere to obtain a high-content Cu 4 S N 4 And compound a small amount of Cu 7.2 S 4 CTS materials.

[0044] Example 1

[0045] In this embodiment, high Cu 4 S N 4 The preparation method of copper tin sulfur (CTS) composite nanoflowers with high content is as follows:

[0046] 1) Dissolve 4 mmol of copper salt in an appropriate amount of ethanol to obtain a 0.13 mol / L copper salt solution; in this embodiment, the copper salt is CuCl 2 ·2H 2 O.

[0047] 2) Add 1 mmol of tin salt to the copper salt solution and stir until completely dissolved; in this embodiment, the tin salt is SnCl 4 ·5H 2 O 。

[0048] 3) Dissolve 4 mmol of thiourea in an appropriate amount of ethanol to obtain a 0.13 mol / L thiourea solution;

[0049] 4) mixing the solution in step 2) with the solution in step 3) and forming a white gel by stirring;

[0050] 5) The white gel is ultrasonicated at 20-50°C (ultrasonicator power is 50-100W) and stirred to form a dispersed emulsion, i.e., the precursor [Cu(CSN 2 H 4 ) 2 ]Cl (as attached Figure 1 shown).

[0051] 6) Transfer the dispersed emulsion to a hydrothermal reactor and heat at 160°C for 16 hours;

[0052] 7) drying the reaction product after centrifugation or suction filtration;

[0053] 8) The dried product was heat treated at 500°C for 4 h in an argon atmosphere to obtain a high-content Cu 4 S N 4 (75.98%) and a small amount of Cu 7.2 S 4 (24.02%) CTS material; the SEM image and XRD spectrum of the obtained CTS material are shown in the attached Figure 2 shown.

[0054] The CTS material prepared in this example was used to assemble a button lithium battery for performance testing.

[0055] Among them, the button lithium battery uses the composite of the CTS material prepared in this embodiment and Super P, sodium carboxymethyl cellulose (CMC) as the positive electrode (the ratio of CTS / Super P / CMC is 8:1:1wt%), metal lithium as the negative electrode, Celgard 2400 as the separator to assemble the button battery (CR2025), and the electrolyte usage of each battery is 45μL.

[0056] After testing, the battery showed a capacity of 595 mAh g at a charging rate of 0.2C after 500 charge and discharge cycles. -1 Capacity (if attached) Figure 3 ), demonstrating the effectiveness of this material in improving the cycle stability of lithium batteries and its practical application potential.

[0057] See attached Figure 4 As shown, compared with the reported CTS or CTS composite electrodes (see the following references), most electrodes show limited capacity within 200 cycles, while the CTS electrode prepared in this embodiment has a longer cycle life and a higher capacity, and its long cycle life and capacity are significantly better than the existing similar Cu-Sn-S composite materials.

[0058] References are as follows:

[0059] [1]Shang,C.;Hu,L.;Fu,L.;Huang,L.;Xue,B.;Wang,X.;Shui,L.;Zhou,G.Improving lithium storage capability of ternary Sn-based sulfides byenhancing inactive / active element ratio.Solid State Ionics 2019,337,47-55.DOI:10.1016 / j.ssi.2019.04.008.

[0060] [2]Foley,S.;Geaney,H.;Bree,G.;Mukherjee,S.;Zaworotko,M.J.;Ryan,K.M.Layered Bimetallic Metal-Organic Material Derived Cu2SnS3 / SnS2 / CCompositefor Anode Applications in Lithium-Ion Batteries.

[0061] ChemElectroChem 2018,5(23),3764-3770.DOI:10.1002 / celc.201800989.

[0062] [3]Wan,H.;Cai,L.;Han,F.;Mwizerwa,J.P.;Wang,C.;Yao,X.Constructionof 3DElectronic / Ionic Conduction Networks for All-Solid-StateLithiumBatteries.Small 2019,15(50),e1905849.DOI:10.1002 / smll.201905849.

[0063] [4]Qu,B.;Zhang,M.;Lei,D.;Zeng,Y.;Chen,Y.;Chen,L.;Li,Q.;Wang,Y.;Wang,T.Facile solvothermal synthesis of mesoporous Cu(2)SnS(3)spheres andtheirapplication in lithium-ion batteries.Nanoscale 2011,3(9),3646-3651.DOI:10.1039 / c1nr10401b.

[0064] [5]Qu,B.;Li,H.;Zhang,M.;Mei,L.;Chen,L.;Wang,Y.;Li,Q.;Wang,T.TernaryCu(2)SnS(3)cabbage-like nanostructures:large-scale synthesis andtheirapplication in Li-ion batteries with superior reversiblecapacity.Nanoscale2011,3(10),4389-4393.DOI:10.1039 / c1nr10784d.

[0065] [6]Zhang,Z.;Zhou,C.;Jia,M.;Fu,Y.;Li,J.;Lai,Y.Synthesis of coppertinsulfide / reduced graphene oxide composites and their electrochemicalpropertiesfor lithium ion batteries.Electrochimica Acta 2014,143,305-311.DOI:10.1016 / j.electacta.2014.07.159.

[0066] [7]Zhang,Z.;Fu,Y.;Zhou,C.;Li,J.;Lai,Y.EDTA-Na2-assistedhydrothermalsynthesis of Cu2SnS3 hollow microspheres and their lithium ionstorageperformances.Solid State Ionics 2015,269,62-66.DOI:10.1016 / j.ssi.2014.11.022.

[0067] [8]Nie,L.;Zhang,Y.;Ye,K.;Han,J.;Wang,Y.;Rakesh,G.;Li,Y.;Xu,R.;Yan,Q.;Zhang,Q.Acrystalline Cu-Sn-S framework for high-performancelithiumstorage.Journal of Materials Chemistry A 2015,3(38),19410-19416.DOI:10.1039 / c5ta04699h.

[0068] [9]Tao,H.-C.;Zhu,S.-C.;Yang,X.-L.;Zhang,L.-L.;Ni,S.-B.Reducedgraphene oxide decorated ternary Cu2SnS3 as anode materials for lithium ionbatteries.Journal of Electroanalytical Chemistry 2016,760,127-134.DOI:10.1016 / j.jelechem.2015.11.025.

[0069]

[10] Chen, 2020,842,155619.DOI:10.1016 / j.jallcom.2020.155619.

[0070]

[11] Peng, X.; Wen, C.; Zhang, Q.; Min, H.; Xiang, Y.; Hu, X.; Zhang, 2021,16(1),17.DOI:10.1186 / s11671-021-03482-6.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing Cu4SnS4-rich composite nanoflowers, characterized in that: The steps include: 1) dissolving copper salt in an appropriate amount of ethanol to obtain a copper salt solution; 2) adding tin salt to the copper salt solution and stirring until completely dissolved; 3) dissolving thiourea in an appropriate amount of ethanol to obtain a thiourea solution; 4) mixing the solution in step 2) and step 3) and forming a gel by stirring; 5) subjecting the gel to ultrasonic treatment and stirring at a certain temperature to form a dispersed emulsion; 6) transferring the dispersed emulsion to a hydrothermal reactor for solvothermal reaction; 7) drying the reaction product after centrifugation or suction filtration; 8) The dried product is heat treated in an inert atmosphere to obtain a high-content Cu4SnS4 and a small amount of Cu 7.2 CTS material for S4.

2. The method for preparing Cu4SnS4-rich composite nanoflowers according to claim 1, characterized in that: In step 1), the amount of copper salt used is 2-4 mmol, and the concentration of the copper salt solution is 0.05-0.15 mol / L; The copper salt is selected from any one or more of copper chloride, copper carbonate, copper sulfate and copper acetate.

3. The method for preparing Cu4SnS4-rich composite nanoflowers according to claim 1, characterized in that: In step 2), the amount of tin salt added is 1 mmol; The tin salt can be selected from any one or more of tin tetrachloride, tin sulfate, and tin acetate.

4. The method for preparing Cu4SnS4-rich composite nanoflowers according to claim 1, characterized in that: The amount of thiourea used in step 3) is 4 mmol, and the concentration of the thiourea solution is 0.08-0.2 mol / L.

5. The method for preparing Cu4SnS4-rich composite nanoflowers according to claim 1, characterized in that: In step 5), the temperature is 20-50° C. and the ultrasonic power is 50-100W.

6. The method for preparing Cu4SnS4-rich composite nanoflowers according to claim 1, characterized in that: In step 6), the dispersed emulsion is transferred to a hydrothermal reactor and heated at 100-200° C. for 2-20 hours.

7. The method for preparing Cu4SnS4-rich composite nanoflowers according to claim 1, characterized in that: In step 7), the dried product is heat treated at 500°C for 4 h in argon to obtain a high-content Cu4SnS4 and a small amount of Cu 7.2 CTS material for S4.

8. The method for preparing Cu4SnS4-rich composite nanoflowers according to claim 7, characterized in that: The CTS material contains 75.98% Cu4SnS4; 7.2 S4 accounts for 24.02%.

9. A Cu4SnS4-rich composite nanoflower, characterized in that: The method is prepared according to any one of claims 1 to 8.

10. Application of the Cu4SnS4-rich composite nanoflowers as claimed in claim 9 in lithium batteries.

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