Zn-doped Cu2SnS3 sodium-ion battery anode material and preparation method thereof

Abstract

The application provides a Zn-doped Cu2SnS3 sodium ion battery negative electrode material and a preparation method thereof. Specifically, a precursor solution is transferred into a 50 mL polytetrafluoroethylene reaction kettle, and the temperature is kept at 200 DEG C for 36 hours, so that Zn-doped Cu2SnS3 particles with good crystallinity and uniform micron flower ball micro-morphology are obtained.

Description

TECHNICAL FIELD

[0001] The application relates to a sodium ion battery negative electrode material and a preparation method thereof, in particular to a Zn-doped Cu2SnS3 sodium ion battery negative electrode material and a preparation method thereof. BACKGROUND

[0002] Among the numerous sodium ion battery (SIBs) negative electrode materials, cuprous sulfide (Cu2S) is an extremely attractive negative electrode material, with a working voltage of less than 1.5 V (relative to Na / Na + ), a theoretical specific capacity of 337.1 mAh g -1 , and a conversion as the dominant reaction mechanism for deintercalating sodium ions. However, Cu2S as a SIBs battery negative electrode material has low capacity and poor rate performance due to poor ion conductivity inside the electrode material and slow sodium ion diffusion kinetics. The applicant has incorporated an electrochemically active metal into a copper-based sulfide to construct a new structure, which can act as an in-situ introduced buffer medium to stabilize the structure of the copper-based sulfide during repeated deintercalation of sodium ions, thereby enabling the copper-based sulfide to have excellent electrochemical performance.

[0003] Copper tin sulfide (Cu2SnS3) is an important ternary copper-based sulfide semiconductor material, with high abundance of constituent elements, low material and device preparation cost, high material and device stability, environmental friendliness and many other advantages, and has very important applications in the field of thin-film solar cells, and is more stable than the commonly used CdS semiconductor, and is a very potential clean energy material. However, it is difficult to control the generation of impurities such as Cu2S, SnS2 and ZnS during preparation. It is also challenging to synthesize Cu2SnS3 with uniform specific morphology. Therefore, a pure phase and a Cu2SnS3 crystal structure with a specific morphology facilitating Na + insertion and extraction must be obtained through a suitable preparation process.

[0004] The applicant has incorporated an electrochemically active metal into a copper-based sulfide to construct a new structure, which can act as an in-situ introduced buffer medium to stabilize the structure of the copper-based sulfide during repeated deintercalation of sodium ions, thereby enabling the copper-based sulfide to have excellent electrochemical performance. SUMMARY

[0005] To solve the above technical problems, the application provides a preparation method of a Zn-doped Cu2SnS3 sodium ion battery negative electrode material. The method comprises the following steps, as shown in Figure 1

[0006] 1) preparing a Zn-Cu2SnS3 precursor solution;

[0007] 2) performing a hydrothermal reaction on the Zn-Cu2SnS3 precursor solution; ​

[0008] 3) The Zn-Cu2SnS3 hydrothermal reaction product was centrifuged, washed, and then dried by forced air to obtain precursor powder;

[0009] 4) Anneal the precursor powder under the protection of an inert gas.

[0010] The Zn-Cu2SnS3 sodium-ion battery anode material prepared through the above steps is shown in the attached figure. Figure 2 As shown, the Zn-Cu2SnS3 particles have a uniform micron-sized flower-like morphology, with a uniform particle size of 2–4 μm. The Zn-Cu2SnS3 micron-sized flower-like particles contain nanochannels. The morphology, crystal structure, and particle size of the Zn-Cu2SnS3 particles directly limit their application and performance as a sodium-ion battery anode material. Zn-Cu2SnS3 sodium battery anodes within the 2–4 μm size range exhibit electrochemical activity, with high capacity retention and rate performance, making them promising for large-scale commercial production. Preferably, the Zn-Cu2SnS3 particle diameter is 2–4 μm. Size adjustment is achieved by changing the hydrothermal temperature, time, and annealing temperature and time. The hydrothermal reaction conditions are 200°C for 36 hours; the annealing is carried out under inert gas protection, preferably argon, at 450°C for 2 hours.

[0011] The Zn-Cu2SnS3 sodium-ion battery anode material prepared by the above steps is shown in the attached figure. Figure 3 As shown, the Zn-Cu2SnS3 particles are monoclinic, belonging to space group P-1, and have a lattice constant of . The Zn-doped Cu2SnS3 particles are obtained by partially incorporating Sn into Cu2S to form monoclinic Cu2SnS3 particles, and then partially replacing Sn atoms with Zn atoms to obtain Zn-doped Cu2SnS3.

[0012] Specifically, step 1 involves uniformly dispersing 2 mmol of copper chloride dihydrate, 1 mmol of zinc acetate, 1 mmol of tin tetrachloride pentahydrate, and 4 mmol of thiourea in 35 mL of ethylene glycol to prepare a Zn-Cu2SnS3 precursor solution.

[0013] Specifically, step 2 involves subjecting the Zn-Cu2SnS3 precursor solution to a hydrothermal reaction, transferring the precursor solution obtained in step 1 to a 50mL polytetrafluoroethylene reactor, and then subjecting it to a hydrothermal reaction at 200°C for 36 hours.

[0014] Specifically, step 3 involves centrifuging the solution obtained in step 2 to obtain a precipitate, washing the precipitate several times alternately with deionized water and ethanol, and then drying it with a forced air for 12 hours.

[0015] Specifically, the powder obtained in step 3 is annealed at 450°C for 2 hours in an argon atmosphere.

[0016] This invention provides a Zn-Cu2SnS3 sodium-ion battery anode material, characterized in that, as shown in the appendix... Figure 2 As shown, the Zn-Cu₂SnS₃ particles exhibit a uniform micron-sized flower-shaped microstructure. The Zn-Cu₂SnS₃ particles have a uniform particle size, ranging from 2 to 4 μm in diameter. Each Zn-Cu₂SnS₃ micron-sized flower-shaped particle contains nanochannels. The Zn-Cu₂SnS₃ particles belong to the monoclinic crystal system, space group P-1, and have a lattice constant of [insert value here]. The Zn-doped Cu2SnS3 particles are obtained by partially incorporating Sn into Cu2S to form monoclinic Cu2SnS3 particles, and then partially replacing Sn atoms with Zn atoms to obtain Zn-doped Cu2SnS3.

[0017] The charging and discharging process of the sodium-ion battery of the present invention is as follows:

[0018] Embedded Na + Reaction process (charging):

[0019] (1) Insertion: Zn a Cu2Sn 1-a S3+(x)Na + +(x)e - →Na x -Zn a Cu2Sn 1-a S3

[0020] (2) Conversion: Na x -Zn a Cu2Sn 1-a S3+(6-x)Na + +(6-x)e - →3Na₂S + 2Cu + (a)Zn + (1-a)Sn

[0021] (3) Alloying: 13Zn + 4Sn + 16Na + +16e - →NaZn 13 +Na 15 Sn4

[0022] Get rid of Na + Reaction process (discharge):

[0023] (4) Dealloying: NaZn 13 +Na 15 Sn⁴→¹³Zn + 4Sn + ¹⁶Na + +16e -

[0024] (5) Conversion and desorption: 2Cu + (b)Zn + (1-b)Sn + 3Na2S → Na y -Zn b Cu2Sn 1-b S3+(6-y)Na + +(6-y)e -

[0025] Zn-Cu2SnS3 is a sodium-ion battery anode material, and the charging process is a step-by-step reaction process of "insertion, conversion, and alloying".

[0026] The beneficial effects of this invention are:

[0027] A method for preparing a sodium-ion battery anode material is provided. The obtained metal sulfide Zn-Cu2SnS3 has a uniform micron-sized flower-like morphology. The Zn-Cu2SnS3 particles obtained by the preparation method provided by this invention have good crystallinity, realizing its application as a sodium-ion battery anode material.

[0028] The Zn-Cu2SnS3 prepared by this invention exhibits a gradual Na intercalation / deintercalation process through insertion, conversion, and alloying as a sodium-ion battery anode material. + The mechanism ensures Na + The efficient insertion and extraction of Na greatly improves + The high mobility eliminates the need for adding carbon materials to improve conductivity; the introduction of tin and zinc enables Cu2S to form a stable monoclinic structure and generate a copper-based buffer layer in situ, which can enhance electrochemical kinetics, improve reversibility, and stabilize the microstructure during repeated sodium insertion / extraction processes.

[0029] The Zn-Cu₂SnS₃ metal sulfide anode material for sodium-ion batteries achieves effective performance transfer without the need for additional highly conductive carbon materials or complex microstructure design. It also solves the problem of low capacity associated with metal sulfides and exhibits low interfacial resistance. The introduction of tin and zinc imparts excellent pseudocapacitive behavior, high reversibility, and fast and stable kinetics to Zn-Cu₂SnS₃; the introduction of tin and zinc can promote Na₂SnS₃ absorption. + with Na x -Zn a Cu2Sn 1-a The stable deintercalation and intercalation reaction between S3 intermediates is a stepwise reaction process. Based on the synergistic effect of the stepwise reaction, the mechanical strain inside the Zn-Cu2SnS3 electrode can be alleviated. Attached Figure Description

[0030] The present invention will be further described below with reference to the accompanying drawings.

[0031] Appendix Figure 1This is a schematic diagram of the crystal structure of the present invention;

[0032] Appendix Figure 2 This is a SEM image of Zn-Cu2SnS3 of the present invention;

[0033] Appendix Figure 3 The XRD patterns of Cu2S, Cu2SnS3, and Zn-Cu2SnS3 of this invention are shown below.

[0034] Appendix Figure 4 The present invention relates to Cu2S, Cu2SnS3, and Zn-Cu2SnS3 at 500 mAg. -1 Cyclic characteristics at current density;

[0035] Appendix Figure 5 The present invention relates to Cu2S, Cu2SnS3, and Zn-Cu2SnS3 at 500 mAg. -1 -100 Ag -1 Rate capability at current density; Appendix Figure 6 Zn-Cu2SnS3 in an embodiment of the present invention at 200 Ag -1 Cycling curves after 80,000 cycles at current density; Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the following detailed description is provided through embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention, and the scope of the invention is not limited thereto.

[0037] [Example 1]

[0038] A Zn-Cu2SnS3 sodium-ion battery anode material comprises the following steps:

[0039] 1) Disperse 2 mmol copper chloride dihydrate, 1 mmol zinc acetate, 1 mmol tin tetrachloride pentahydrate, and 4 mmol thiourea evenly in 35 mL ethylene glycol;

[0040] 2) Transfer the precursor solution obtained in step 1 to a 50 mL polytetrafluoroethylene reactor and hydrothermally react at 200°C for 36 hours.

[0041] 3) Centrifuge the solution obtained in step 2 to obtain a precipitate. Wash the precipitate several times with deionized water and ethanol alternately, and then dry it with a forced air for 12 hours.

[0042] 4) Anneal the powder obtained in step 3 at 450°C for 2 hours in an Ar atmosphere to obtain Zn-Cu2SnS3 with a micron flower-shaped structure.

[0043] Specifically, the following steps are performed: the precursor solution obtained in step 1) is transferred to a 50 mL polytetrafluoroethylene reactor, and then hydrothermally reacted at 200 °C for 36 hours.

[0044] The Zn-Cu2SnS3 particles have a uniform particle size, such as Figure 2 The present invention relates to a Zn-Cu2SnS3 sodium-ion battery anode material, characterized in that, as shown in the figure... Figure 2 The Zn-Cu2SnS3 particles shown have a uniform micron-sized flower-like microstructure, and the Zn-Cu2SnS3 particles have a uniform particle size of 2–4 μm. Figure 3 As shown, the Zn-Cu2SnS3 micron flowers have nanochannels in the middle; the Zn-Cu2SnS3 particles are monoclinic, belonging to space group P-1, and have a lattice constant of . The Zn-doped Cu2SnS3 particles are obtained by partially incorporating Sn into Cu2S to form monoclinic Cu2SnS3 particles, and then partially replacing Sn atoms with Zn atoms to obtain Zn-doped Cu2SnS3.

[0045] Tests have shown that Zn-Cu2SnS3 exhibits excellent structural stability during charge and discharge processes.

[0046] like Figure 3 As shown, the Zn-Cu2SnS3 particles are monoclinic and belong to space group P-1.

[0047] After testing, such as Figure 4 As shown, the first-cycle discharge / charge capacity of the Zn-Cu2SnS3 sodium-ion battery anode material is 754.8 mAh g. -1 and 545.2mAh g -1 The coulombic efficiency in the first cycle was 72.2%. The significant irreversible capacity loss in the first cycle was due to the formation of an irreversible SEI film. Subsequently, due to material activation, the capacity increased, with the coulombic efficiency increasing to 98.5% in the second cycle and gradually increasing to 99.0% after 5 cycles. After 50 cycles, the reversible capacity of Zn-Cu2SnS3 remained as high as 501.6 mAh g⁻¹. -1 The capacity retention rate is as high as 92%.

[0048] like Figure 5 As shown, the Zn-Cu2SnS3 sodium-ion battery anode material exhibits high reversible capacity at 0.5, 1, 2, 5, 10, 20, 50, and 100 A g. -1 At different current densities, the reversible capacities were 467.5, 459.5, 455.8, 436.5, 423.5, 408.8, 357.2, and 284.5 mAh g, respectively. -1 When the current density is from 100Ag -1decreased to 0.5 Ag -1 The reversible capacity of Zn-Cu2SnS3increased to 414.8 mAh g -1 .

[0049] As shown in Figure 6 Zn-Cu2SnS3sodium-ion battery anode material, the capacity retention rate is 100% after 80000 cycles at a current density of 200 Ag -1 .

Claims

1. A method for preparing a Zn-doped Cu2SnS3 sodium-ion battery anode material, characterized in that, The preparation method comprises the following steps: Step 1), preparing a Zn-doped Cu2SnS3 precursor solution; Step 2), performing a hydrothermal reaction on the Zn-doped Cu2SnS3 precursor solution; Step 3), performing centrifugation and cleaning on the Zn-doped Cu2SnS3 hydrothermal reaction product, and then drying the product in a blast drying oven for several hours to obtain a Zn-doped Cu2SnS3 precursor powder; Step 4), performing an annealing treatment on the precursor powder under the protection of argon to obtain Zn-doped Cu2SnS3 particles with uniform micron-flower spherical micro-morphology, wherein the Zn-doped Cu2SnS3 particles are uniform in particle size and have a diameter of 2-4 microns, the micron-flower has a nanochannel in the middle, the Zn-doped Cu2SnS3 particles are monoclinic and belong to the P-1 space group, the lattice constants are a = 6.653 Å, b = 11.537 Å and c = 6.665 Å, the introduction of tin and zinc makes Cu2S form a stable monoclinic structure, in-situ generates a copper-based buffer layer, and enhances the electrochemical kinetic performance, improves the reversibility and stabilizes the microstructure in the repeated sodium extraction and insertion process.

2. The method for preparing Zn-doped Cu2SnS3 sodium-ion battery anode material according to claim 1, characterized in that, Step 1) is to uniformly disperse copper chloride dihydrate, zinc acetate, tin tetrachloride pentahydrate and thiourea in ethylene glycol to prepare a Zn-doped Cu2SnS3 precursor solution.

3. The method of producing a Zn-doped Cu2SnS3 sodium-ion battery anode material according to claim 2, wherein, Step 2) is to transfer the precursor solution obtained in step 1) into a 50 mL polytetrafluoroethylene reaction kettle and perform a hydrothermal reaction.

4. The method of producing a Zn-doped Cu2SnS3 sodium-ion battery anode material according to claim 3, wherein, The precursor solution obtained in step 1) is transferred into a 50 mL polytetrafluoroethylene reaction kettle, and a hydrothermal reaction is performed at 200°C for 36 hours.

5. The method of producing a Zn-doped Cu2SnS3 sodium-ion battery anode material according to claim 4, wherein, Step 3) is to centrifugally separate the solution obtained in step 2) to obtain a precipitate, wash the precipitate with deionized water and ethanol alternately for several times, and then perform blast drying to obtain a powder.

6. The method of producing a Zn-doped Cu2SnS3 sodium-ion battery anode material according to claim 5, wherein, Step 4) is to anneal the powder obtained in step 3) at 450°C for 2 hours.

7. The method of producing a Zn-doped Cu2SnS3 sodium-ion battery anode material as claimed in claim 1, wherein, The Zn-doped Cu2SnS3 particles are monoclinic Cu2SnS3 particles obtained by incorporating part of Sn into Cu2S, and are Zn-doped Cu2SnS3 obtained by partially replacing Sn atoms with Zn atoms.

8. A Zn-doped Cu2SnS3 sodium-ion battery anode material, characterized in that, The Zn-doped Cu2SnS3 particles have uniform micron-flower spherical micro-morphology, have a nanochannel in the middle of the micron-flower, are monoclinic and belong to the P-1 space group, the lattice constants are a = 6.653 Å, b = 11.537 Å and c = 6.665 Å, the introduction of tin and zinc makes Cu2S form a stable monoclinic structure, in-situ generates a copper-based buffer layer, and enhances the electrochemical kinetic performance, improves the reversibility and stabilizes the microstructure in the repeated sodium extraction and insertion process.

9. The Zn-doped Cu2SnS3 sodium-ion battery anode material of claim 8, wherein, The Zn-doped Cu2SnS3 particles are uniform in particle size and have a diameter of 2-4 microns.

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