Sub-micron plate-like tin phosphide lithium and sodium storage material and battery

Abstract

This invention provides a submicron-sized plate-shaped tin phosphide lithium-sodium storage material and battery. The invention utilizes a solvothermal chemical route to prepare Sn4P3 containing excess red phosphorus, followed by sublimation to remove the excess red phosphorus, yielding submicron-sized plate-shaped tin phosphide nanosheets. Detailed electrochemical characterization of the synthesized product revealed excellent performance in LIBs anodes, exhibiting high sodium / lithium reversibility. The thinner submicron sheets shorten the Na… + / e ‑ and Li + / e ‑ The transfer distance is increased, and the reaction kinetics of lithium and sodium storage are enhanced, thereby achieving excellent cycle stability. This method provides higher capacity and better cycle stability for lithium-ion and sodium-ion batteries. Compared with existing reports, the preparation method of this invention is simpler, less expensive, and easier to mass-produce. The submicron plate-shaped tin phosphide produced exhibits excellent cycle performance and rate performance in lithium-ion and sodium-ion batteries.

Description

Technical Field

[0001] This invention relates to the field of battery electrode materials technology, specifically to a submicron plate-shaped tin phosphide lithium and sodium storage material and a battery thereof. Background Technology

[0002] Submicron-sized, plate-like tin phosphide is ideal for advanced electronic, magnetic, optoelectronic, and sensing applications, as the performance of the particles largely depends on their phase, size, shape, and microstructure. Developing scalable and simple routes to produce synthesized materials with controllable size and microstructure is crucial. For lithium-ion batteries, tin phosphide offers a capacity of nearly 1130 mAh / g, significantly higher than the 372 mAh / g of conventional graphite anode materials. The underlying mechanism for this high capacity lies in the fact that the structure of tin phosphide allows for multi-stage insertion and release of lithium ions within its structure, thus providing excellent capacity and charge-discharge stability.

[0003] The main methods for preparing tin phosphide include ball milling, calcination, hydrothermal synthesis, and solvothermal methods, each with its unique advantages and limitations. Ball milling relies on the strong mechanical force of a high-energy ball mill to achieve powder mixing and particle size reduction; this method has extremely high equipment requirements and presents challenges in terms of crystallinity. Calcination involves exposing the precursor to phosphine gas for phosphating, producing high-purity tin phosphide. However, the high toxicity of phosphine and the need for precise control over the precursor limit its widespread application. Furthermore, the uncontrollable particle size and structure during calcination can lead to poor cycle stability and limited battery life in the prepared tin phosphide. Hydrothermal synthesis allows for lower temperatures, helping to maintain the structural integrity of the material. However, this method involves cumbersome synthesis steps and poor reproducibility, limiting its application in large-scale production. Qian et al. synthesized Sn4P3 / C anode material as a lithium storage material using ball milling with elemental tin, red phosphorus, and 30% carbon black as raw materials, achieving the following results at 100 mA g… -1 The capacity is 500mAh g after 150 charge-discharge cycles at the specified current density. -1 However, the particle size of this material is relatively large, and it cannot achieve ideal electrochemical performance (ACS Nano 2020, 14, 8826-8837); for example, Li et al. synthesized Sn4P3 / RGO composite material using tin dichloride, sodium borohydride and PVP as raw materials through a low-temperature solution chemistry method, as a sodium storage material, and achieved good performance at 100 mA g. -1 The capacity is 656 mAh g after 100 charge-discharge cycles at the specified current density. -1This material exhibits high capacity, but its low coulombic efficiency degrades its overall electrochemical performance (Adv. Energy Mater. 2016, 6, 1600376-1600386). For example, Qing et al. synthesized Sn4P3 / CNT material using tin dichloride, red phosphorus, and carbon nanotubes as raw materials via a one-step solvothermal method, which was used as a negative electrode material for LIBs, achieving a performance at 500 mA g / g. -1 After 300 charge-discharge cycles at a given current density, the capacity is 976.5 mAh g. -1 However, the material has a large particle size and cannot achieve ideal electrochemical performance (ChemElectroChem 2018, 15, 2150-2156).

[0004] Patent CN110993913A discloses a method for synthesizing tin phosphide / expanded graphite anode sodium storage material using tin tetrachloride as raw material, sodium hypophosphite as phosphorus source, and expanded graphite prepared by chemical oxidation as a conductive agent. The material is then wet-milled in a ball mill jar to obtain a particle size of 80–200 nm and a carbon content of 16.7 wt%. The tin phosphide synthesized by this method has a smaller particle size than conventionally synthesized tin phosphide. Furthermore, the graphite sheets peeled from the expanded graphite successfully coat the tin phosphide, forming a spherical composite material with a coating thickness of approximately 5–6 nm. This spherical composite material is loaded onto the peeled graphite sheets, forming a conductive network. As an SIB anode material, after 100 cycles of constant current charge-discharge at 500 mA / g, the specific capacity remains at 409 mAh / g, demonstrating good cycle stability.

[0005] The invention patent CN111082034A discloses a method for preparing tin / tin phosphide / carbon composite materials by using sodium alginate as a raw material and cross-linking, carbonizing, and then phosphating it with tetravalent tin ions. When applied to the negative electrode of a lithium-ion battery, it exhibits an initial coulombic efficiency of 50% at a current density of 0.1 A / g, and a capacity of 665 mAh / g after 100 cycles. At a current density of 1 A / g, the initial discharge specific capacity is 1767 mAh / g, and after a period of capacity decay, it continues to increase, reaching a specific capacity of 920 mAh / g after 500 cycles, demonstrating excellent cycle performance and rate performance.

[0006] In summary, existing literature reports complex and time-consuming methods for preparing tin phosphide. Furthermore, both existing literature and practical experience with solvothermal tin phosphide synthesis indicate that an excess of red phosphorus is required for successful synthesis. Due to the low conductivity and high expansion properties of red phosphorus, it has a significant negative impact on battery capacity and lifespan. Composite carbon is needed to overcome these drawbacks of red phosphorus, thus highlighting the limitation of requiring composite carbon in tin phosphide synthesis. Synthesizing tin phosphide with controlled morphology, size, and chemical composition, and eliminating the requirement for composite carbon in solvothermal synthesis, is a crucial step towards the widespread industrial application of solvothermal tin phosphide synthesis. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings and deficiencies of the existing technology and to provide a submicron plate-shaped tin phosphide lithium and sodium storage material and battery.

[0008] The technical solution adopted by this invention is as follows: The first aspect of this invention is to provide a submicron plate-shaped tin phosphide lithium and sodium storage material, the preparation method of which includes the following steps:

[0009] S1: Take soluble tin-based material, red phosphorus, and polar amine solution, place them in a reaction vessel, mix and heat, centrifuge, wash and dry to obtain tin phosphide and excess red phosphorus;

[0010] S2: The tin phosphide obtained in step S1 and excess red phosphorus are heated in an inert atmosphere to sublimate the excess red phosphorus, resulting in submicron flake tin phosphide.

[0011] Preferably, in step S1, the molar ratio of the soluble tin-based material to red phosphorus is 1:160-200.

[0012] Preferably, the soluble tin-based material is tin and / or stannous chloride.

[0013] Preferably, the polar amine solution is ethanolamine and / or ethylenediamine.

[0014] Preferably, step S1 specifically includes the following steps:

[0015] S1.1: Add soluble tin-based material and red phosphorus to the lining of the reactor, and then add a polar amine solution;

[0016] S1.2: Place the inner liner of the reactor in an oil bath and heat and stir.

[0017] S1.3: After stirring, immediately transfer the inner liner of the reactor into the high-temperature reactor, and place the high-temperature reactor in a preheated oven for heating and heat preservation;

[0018] S1.4: Centrifuge, wash and dry the solution obtained in step S1.3 to obtain tin phosphide and excess red phosphorus.

[0019] Preferably, in step S1.2, the heating temperature is 80-100℃ and the heating time is 30-60 minutes.

[0020] Preferably, in step S1.3, the heating temperature is 180℃-220℃, and the temperature holding time is 10-24h.

[0021] Preferably, in step S2, the inert gas is nitrogen or argon, the sublimation temperature is 370-420℃, and the sublimation time is 1-40h.

[0022] A second aspect of the present invention is to provide a battery, which is a lithium-ion battery or a sodium-ion battery, wherein the submicron plate-shaped tin phosphide lithium-sodium storage material as described above is used as the negative electrode material.

[0023] Preferably, the preparation method includes the following steps:

[0024] (A) Weigh out submicron plate-shaped tin phosphide lithium and sodium storage material, acetylene black and sodium alginate, add a certain amount of distilled water, mix evenly, grind and stir into a paste, and coat it onto copper foil.

[0025] (B) The coated copper foil is dried, sliced, assembled, and pressed to obtain the lithium-ion battery or sodium-ion battery.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention utilizes a solvothermal chemical route to prepare a product containing excess red phosphorus and Sn4P3. Excess red phosphorus is then removed by sublimation, yielding submicron-sized plate-like tin phosphide nanosheets. Detailed electrochemical characterization of the synthesized product revealed excellent performance in LIB anodes, exhibiting high sodium / lithium reversibility. The thinner submicron sheets shorten the Na… + / e - and Li + / e - The transfer distance is increased, and the reaction kinetics of lithium and sodium storage are enhanced, thereby achieving excellent cycle stability. This method provides higher capacity and better cycle stability for lithium-ion and sodium-ion batteries. Compared with existing reports, the preparation method of this invention is simpler, less expensive, and easier to mass-produce. The submicron plate-shaped tin phosphide produced exhibits excellent cycle performance and rate performance in lithium-ion and sodium-ion batteries.

[0028] In one embodiment of the present invention, a submicron plate-shaped tin phosphide material was prepared and used as a LIB anode. After 100 cycles at a current density of 100 mA / g, the lithium storage capacity reached 662 mAh / g, and the capacity gradually increased with the number of cycles, stabilizing at approximately 1720 mAh / g after 100 cycles. As a SIB anode, the submicron plate-shaped tin phosphide material maintained a capacity as high as 310 mA / g after 60 cycles at a current of 50 mA / g, significantly exceeding the results of previously published articles. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0030] Figure 1 Scanning electron microscope (SEM) image (de) of sublimed submicron plate-shaped tin phosphide prepared in Example 1; Scanning electron microscope (SEM) image (ac) of tin phosphide before sublimation prepared in Comparative Example 1;

[0031] Figure 2 X-ray diffraction (XRD) patterns of sublimed submicron plate-shaped tin phosphide prepared in Example 1 and tin phosphide before sublimation prepared in Comparative Example 1 (b, a);

[0032] Figure 3 The sublimated submicron plate-shaped tin phosphide material prepared in Example 1 was used as a negative electrode for a lithium-ion battery at 100 mA g. -1 Cyclic stability test graphs (ad) at different current densities;

[0033] Figure 4 The sublimated submicron plate-shaped tin phosphide material prepared in Example 1 was used as the anode of a sodium-ion battery at 20 mA g. -1 50mA g -1 200mA g -1 500mA g -1 1000mA g -1 Cyclic stability test graphs (ad) at different current densities; Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] Example 1:

[0036] A method for preparing submicron plate-shaped tin phosphide lithium and sodium storage materials, comprising the following steps:

[0037] S1: 0.4 g of stannous chloride dihydrate (SnCl2·2H2O) and 1.2 g of red phosphorus (P) were added to the liner of a polytetrafluoroethylene reactor. Subsequently, 20 ml of ethanolamine solution was injected.

[0038] S2: Place the inner liner of the reactor and the solution in an oil bath, add a magnetic stir bar, adjust the temperature to 90°C, and maintain this temperature while stirring for 60 minutes.

[0039] S3: After stirring, immediately transfer the inner liner of the reactor into the stainless steel high-temperature reactor. After ensuring the reactor is securely fastened, place it in a preheated oven at 180°C and maintain this temperature for 15 hours.

[0040] S4: Centrifuge the solution obtained in step S3 to obtain a solid product. Wash the solid product with water and ethanol, and dry it to obtain tin phosphide product and excess red phosphorus.

[0041] S5: The product obtained in step S4 is heated in an inert atmosphere to sublimate the red phosphorus and obtain submicron flake tin phosphide.

[0042] S6: Submicron flake tin phosphide material, acetylene black and sodium alginate are mixed evenly in a mass ratio of 8:1:1, an appropriate amount of ultrapure water is added, and the mixture is stirred continuously to form a paste, which is then coated onto copper foil; the coated copper foil is dried, pressed, and the battery is assembled.

[0043] Comparative Example 1:

[0044] The preparation process of this comparative example is roughly the same as that of Example 1, except that step S5 is not included.

[0045] Microscopic characterization

[0046] The tin phosphide materials prepared in Example 1 and Comparative Example 1 were characterized by different microscopic methods:

[0047] Figure 1 The images show SEM images (cd) of the submicron plate-shaped tin phosphide synthesized in Example 1 and (ac) of the unsublimated red phosphorus in Comparative Example 1. The SEM images show that the submicron plate-shaped tin phosphide synthesized in Example 1 has a thickness of less than 1 μm, and its morphology is irregular, large-scale, thin, and uniformly distributed. The unsublimated red phosphorus in Comparative Example 1 is a blocky structure of tens of micrometers.

[0048] Figure 2The XRD pattern (b) of submicron plate-shaped tin phosphide in Example 1 and the XRD pattern (a) of unsublimated red phosphorus in Comparative Example 1 can be seen; it can be seen that the sublimation of red phosphorus will have a slight phase transition effect on Sn4P3.

[0049] Electrochemical performance characterization

[0050] Figure 3 The submicron plate-shaped tin phosphide in Example 1 and the non-sublimated red phosphorus in Comparative Example 1 were used as negative electrodes in lithium-ion batteries at 100 mA g. -1 Figure (a) and Figure (b) show the cycling stability test results at different current densities; submicron plate-shaped tin phosphide at 1000 mA g -1 Cyclic stability test results at current density (d) and 100mA g -1 The charge-discharge curves at current density are shown in Figure (c). A comparison of the cycle stability performance diagrams shows that the submicron plate-shaped tin phosphide lithium storage anode material of Example 1 exhibits good performance at 100 mA g⁻¹. -1 At current density, the capacity remains at 662 mAh g after 100 cycles. -1 Furthermore, as the number of cycles gradually increases, the capacity reaches 1723 mA g after 1000 cycles. -1 It demonstrates good lifespan and capacity; at different rates, the current density returns to 100 mA g after 60 cycles. -1 Under these conditions, the capacity can be restored to 677mAh g. -1 And at 100, 200, 500 and 1000, 2000 mA g respectively -1 After 120 cycles at high current density, the capacity remained at 757, 665, 591, 543, and 494 mAh g, respectively. -1 Comparative Example 1: The capacity of the non-sublimated red phosphorus lithium-ion anode material did not exceed 50 mAh g after 5 cycles at various rate limits. -1 This demonstrates that submicron plate-shaped tin phosphide high-performance lithium and sodium storage materials, when used as anodes in lithium-ion batteries, exhibit high reversibility in lithium storage.

[0051] Figure 4 The submicron plate-shaped tin phosphide in Example 1 and the non-sublimated red phosphorus in Comparative Example 1 were used as anodes in sodium-ion batteries at 20 mA g. -1 Figure (a), 50mA g -1 Figure (b) and Figure (c) show the cycle stability test results at different current densities; in Example 1, submicron plate-shaped tin phosphide was tested at 100 mA g. -1 The charge-discharge curves at current density (d) show that, through comparison with the cycle stability graphs, the submicron plate-shaped tin phosphide sodium storage anode material synthesized by surfactant adsorption in Example 1 exhibits good performance at 50 mA g⁻¹. -1At current density, after 60 cycles, the capacity still has 310mAh g. -1 At 500mA g -1 At the current density, the capacity is 209 mAh g after 60 cycles. -1 At different magnifications, the current density returns to 20 mA after 60 cycles. -1 Under these conditions, the capacity can be restored to 670mAh g. -1 Comparative Example 1: The capacity of the non-sublimated red phosphorus lithium-ion anode material did not exceed 50 mAh g after 5 cycles at various rate limits. -1 This demonstrates that submicron plate-shaped tin phosphide high-performance lithium and sodium storage materials, when used as anodes in sodium-ion batteries, exhibit high sodium storage reversibility.

[0052] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A sub-micron plate-like tin phosphide lithium and sodium storage material, characterized in that, The preparation method comprises the following steps: S1: taking the soluble tin-based material, red phosphorus and polar amine solution into a reaction container, mixing and heating, centrifuging, washing and drying to obtain tin phosphide and excess red phosphorus; S2: placing the tin phosphide and excess red phosphorus obtained in step S1 in an inert atmosphere and heating to sublimate the excess red phosphorus to obtain submicron plate-like tin phosphide. 2.The sub-micron plate-like tin phosphide lithium / sodium storage material of claim 1, characterized in that: In step S1, the molar ratio of the soluble tin-based material to red phosphorus is 1:160-200.

3. The submicron plate-shaped tin phosphide lithium and sodium storage material according to claim 1, characterized in that: The soluble tin-based material is tin and / or stannous chloride.

4. The sub-micron plate-like tin phosphide lithium / sodium storage material according to claim 1, characterized in that: The polar amine solution is ethanolamine and / or ethylenediamine.

5. The sub-micron plate-like tin phosphide lithium / sodium storage material according to claim 1, characterized in that, Step S1 specifically comprises the following steps: S1.1: taking the soluble tin-based material and red phosphorus into the inner liner of the reaction kettle, and then adding the polar amine solution; S1.2: placing the inner liner of the reaction kettle in an oil bath and heating and stirring; S1.3: immediately after stirring, placing the inner liner of the reaction kettle into a high-temperature reaction kettle, and heating and keeping the high-temperature reaction kettle in a preheated oven; S1.4: centrifuging, washing and drying the solution obtained in step S1.3 to obtain tin phosphide and excess red phosphorus.

6. The sub-micron plate-like tin phosphide lithium / sodium storage material according to claim 4, characterized in that: In step S1.2, the heating temperature is 80-100℃, and the heating time is 30-60 minutes.

7. The sub-micron plate-like tin phosphide lithium / sodium storage material according to claim 4, characterized in that: In step S1.3, the heating temperature is 180℃-220℃, and the temperature keeping time is 10-24h.

8. The sub-micron plate-like tin phosphide lithium / sodium storage material according to claim 1, characterized in that: In step S2, the inert gas is nitrogen or argon, the sublimation temperature is 370-420℃, and the sublimation time is 1-40h.

9. A battery, which is a lithium-ion battery or a sodium-ion battery, characterized by: The lithium ion battery or sodium ion battery comprises a cathode, an anode and an electrolyte.

10. The battery of claim 9, wherein the electrolyte is a mixture of LiPF6 and LiBF4. The preparation method comprises the following steps: (A) taking submicron plate-like tin phosphide lithium / sodium storage material, acetylene black and sodium alginate, adding a certain amount of distilled water, mixing uniformly, grinding and stirring into a paste, and coating on a copper foil; (B) drying, slicing, assembling and pressing the coated copper foil to obtain the lithium ion battery or sodium ion battery.

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