Sodium-phosphorus composite negative electrode material, preparation method thereof and solid-state sodium battery

Abstract

The application provides a sodium-phosphorus composite negative electrode material, a preparation method thereof and a solid-state sodium battery, and the preparation raw materials comprise metal sodium and phosphorus with a mass ratio of 100:1-5, and the phosphorus comprises red phosphorus (P) and / or black phosphorus (BP). + The sodium-phosphorus composite negative electrode material has excellent ionic conductivity; the sodium-phosphorus composite negative electrode material is well matched with NZSP, can well adjust Na + ion stripping / deposition behavior, limits the expansion of metal sodium and the growth of sodium dendrites while accelerating the interface charge transfer; and the assembled NVP / NZSP / Na3P@Na-3 full solid-state battery has excellent rate performance and cycle performance.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery technology, and particularly relates to a sodium-phosphorus composite anode material, its preparation method, and a solid-state sodium battery. Background Technology

[0002] Among candidate anodes for sodium-ion batteries, metallic sodium offers the lowest voltage and the highest theoretical specific capacity (1166 mAh g). -1 However, sodium metal anodes readily form sodium ion depletion regions at the interface. Simultaneously, uneven deposition tends to lead to sodium dendrite formation. The higher the current, the more pronounced the depletion effect, and the more severe the sodium dendrite growth, ultimately causing battery failure.

[0003] Sodium storage is primarily achieved through alloying reactions with high reduction potentials. Adding alkaline earth elements to the metallic sodium anode of sodium-ion batteries can form a corresponding alloy framework and increase the theoretical capacity. However, research on high-energy-density sodium-ion battery anode materials is relatively limited, and the significant volume change during sodium intercalation, particularly the substantial volume expansion during cycling, leads to electrode material breakage and collapse. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a sodium-phosphorus composite anode material, a method for preparing the same, and a solid-state sodium battery.

[0005] This invention provides a sodium-phosphorus composite anode material, the raw materials for which include metallic sodium and phosphorus in a mass ratio of 100:1 to 5, wherein the phosphorus includes red phosphorus (P) and / or black phosphorus (BP).

[0006] In this invention, the mass ratio of sodium to phosphorus is 100:1, 100:2, 100:3, 100:4, or 100:5, respectively denoted as Na3P@Na-1, Na3P@Na-2, Na3P@Na-3, Na3P@Na-4, and Na3P@Na-5.

[0007] The sodium-phosphorus composite anode material has high ionic conductivity; and with Na... 3.1 Zr 1.95 Mg 0.05 Si2PO 12 (NZSP) has good interface matching and can effectively regulate Na. + Ion exfoliation / deposition behavior, while accelerating interfacial charge transfer, limits the expansion of metallic sodium and the growth of sodium dendrites.

[0008] This invention utilizes abundant and inexpensive phosphorus reserves. The introduction of phosphorus significantly improves the interfacial wettability between the Na anode and the solid electrolyte, reduces the interfacial resistance between the anode and electrolyte, and eliminates the need for additional coating processes on the solid electrolyte or the positive / negative electrode surfaces. This simplifies the preparation process and greatly reduces manufacturing costs.

[0009] This invention provides a method for preparing the sodium-phosphorus composite anode material described in the above technical solution, comprising the following steps:

[0010] Under an argon atmosphere, molten sodium and phosphorus are mixed and stirred to obtain a sodium-phosphorus composite negative electrode;

[0011] The mass ratio of molten sodium to phosphorus is 100:1 to 5. Preferably, the metallic sodium is heated to 160°C until it is molten. Preferably, phosphorus is added to the molten sodium.

[0012] In this invention, the stirring time is 8 to 12 minutes.

[0013] This invention provides a solid sodium metal battery, comprising a positive electrode, a negative electrode, and a solid electrolyte;

[0014] The negative electrode is the sodium-phosphorus composite negative electrode material described in the above technical solution.

[0015] In this invention, the positive electrode is preferably Na3V2(PO4)3; the solid electrolyte is selected from Na 3.1 Zr 1.95 Mg 0.05 Si2PO 12 .

[0016] This invention provides a sodium-phosphorus composite anode material, prepared by means of metallic sodium and phosphorus in a mass ratio of 100:1 to 5, wherein the phosphorus includes red phosphorus (P) and / or black phosphorus (BP). The sodium-phosphorus composite anode material provided by this invention exhibits excellent ionic conductivity; the sodium-phosphorus composite anode material has good interfacial matching with NZSP, and can effectively regulate Na+. + The ion exfoliation / deposition behavior accelerates interfacial charge transfer while limiting the expansion of metallic sodium and the growth of sodium dendrites; the assembled NVP / NZSP / Na3P@Na-3 all-solid-state battery exhibits excellent rate performance and cycle performance. Attached Figure Description

[0017] Figure 1 The XRD pattern of the sodium-phosphorus composite anode material (Na3P@Na-3);

[0018] Figure 2Optical photographs and SEM images of the surface contact between Na and NZSP, and optical photographs and SEM images of the cross-section of the sodium / phosphorus composite anode material Na3P@Na-3 in contact with the surface of NZSP.

[0019] Figure 3 EIS(a) and interface impedance comparison diagram(b) of a symmetrical cell assembled with sodium phosphorus (red phosphorus) composite negative electrode;

[0020] Figure 4 EIS spectrum of a symmetrical cell assembled with a composite negative electrode of sodium and black phosphorus (BP) in a mass ratio of 100:3;

[0021] Figure 5 A symmetrical cell assembled using Na3P@Na-3 as the negative electrode was tested at 0.1 mA cm⁻¹. -2 Time-voltage curves at current density;

[0022] Figure 6 A symmetrical cell assembled using Na3P@Na-5 as the negative electrode was tested at 0.1 mA cm⁻¹. -2 Time-voltage curves at current density;

[0023] Figure 7 A symmetrical cell assembled using Na3BP@Na-3 as the negative electrode was tested at 0.1 mA cm⁻¹. -2 Time-voltage curves at current density;

[0024] Figure 8 The electrochemical performance of the NVP / NZSP / Na3P@Na-3 full cell at room temperature is shown. Detailed Implementation

[0025] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, provides a sodium-phosphorus composite anode material, its preparation method, and a solid-state sodium battery provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0026] Example 1

[0027] In an argon (Ar)-filled glove box, a certain mass of sodium metal block was heated to a molten state at 160°C. Then, red phosphorus (P) was added to the molten sodium metal at a Na:P mass ratio of 100:1 and stirred for 10 min to obtain a sodium / phosphorus composite electrode material with a mass ratio of 100:1, denoted as Na3P@Na-1. Using the Na3P@Na-1 composite negative electrode, a 2032-type coin cell was assembled in an argon (Ar) atmosphere with H2O and O2 contents both below 0.1 ppm. The AC impedance spectroscopy of the coin cell was tested (e.g., ...). Figure 3 The study examined the symmetric cell's cycle life at room temperature and at 0.1 mA / cm².-2 Under the given current density, a significant short circuit occurred within 40 hours.

[0028] Example 2

[0029] In an argon (Ar)-filled glove box, a certain mass of sodium metal block was heated to a molten state at 160℃. Then, red phosphorus (P) was added to the molten Na at a Na:P mass ratio of 100:3 and stirred for 10 min to obtain a sodium / phosphorus composite electrode material with a mass ratio of 100:3, denoted as Na3P@Na-3. Using the Na3P@Na-3 composite negative electrode, a 2032-type coin cell was assembled in an argon (Ar) atmosphere with H2O and O2 contents both below 0.1 ppm. The AC impedance spectroscopy of the coin cell was tested. Figure 3 The study examined the symmetric cell's cycle life at room temperature and at 0.1 mA / cm². -2 It can stably cycle for more than 500 times at a current density, such as Figure 5 As shown. To evaluate the practicality of the Na3P@Na-3 composite sodium anode, an all-solid-state sodium battery, NVP / NZSP / Na3P@Na-3, coupled with a Na3V2(PO4)3(NVP) cathode, was assembled in a glove box. The electrochemical performance of the full cell was tested at room temperature, and it was found that the coulombic efficiency of the full cell was consistently greater than 96% at different rate operations. Figure 8 (a) Further examination of the long-cycle performance of the NVP / NZSP / Na3P@Na-3 all-solid-state battery at 1C rate (e.g., Figure 8 In the study (c), it was found that the full cell could cycle stably for more than 240 times at a 1.0C rate, with a capacity retention rate of up to 96.3%.

[0030] Example 3

[0031] In an argon (Ar)-filled glove box, a certain mass of sodium metal block was heated to a molten state at 160°C. Then, red phosphorus (P) was added to the molten Na at a Na:P mass ratio of 100:5 and stirred for 10 min to obtain a sodium / phosphorus composite electrode material with a mass ratio of 100:5, denoted as Na3P@Na-5. Using the Na3P@Na-5 composite negative electrode, a 2032-type coin cell was assembled in an argon (Ar) atmosphere with H2O and O2 contents both below 0.1 ppm. The AC impedance spectroscopy of the coin cell was tested (e.g., ...). Figure 3 The study examined the symmetric cell's cycle life at room temperature and at 0.1 mA cm⁻¹. -2 Cycling at current density for more than 200 hours, such as Figure 6 As shown.

[0032] Example 4

[0033] In an argon (Ar)-filled glove box, a certain mass of sodium metal block was heated to a molten state at 160°C. Black phosphorus (BP) was then added to the molten Na at a Na:BP mass ratio of 100:3 and stirred for 10 min to obtain a sodium / black phosphorus composite electrode material with a mass ratio of 100:3, denoted as Na3BP@Na-3. Using the Na3BP@Na-3 composite negative electrode, a 2032-type coin cell was assembled in an argon (Ar) atmosphere with H2O and O2 contents both below 0.1 ppm. The AC impedance spectroscopy of the coin cell was tested (e.g., ...). Figure 4 The study also examined the cycle life and found that the interfacial impedance of this symmetrical cell was further reduced to 66.3 Ωcm. 2 And at room temperature and 0.1 mAcm -2 Stable cycling for 500 hours at a current density, such as Figure 7 As shown.

[0034] This invention combines sodium / phosphorus composite anode materials (Na / NZSP, Na3P@Na-1, Na3P@Na-3, Na3P@Na-5, and Na3BP@Na-3) with Na... 3.1 Zr 1.95 Mg 0.05 Si2PO 12 (NZSP) electrolyte matching revealed that the addition of phosphorus significantly improved the interfacial wettability between the sodium anode and the solid electrolyte, such as... Figure 3 As shown, the resistance of the display interface has been significantly reduced; Figure 2 (a) Optical photograph of the surface contact between Na and NZSP and (b) and (c) SEM images of its cross-section: low magnification (b) and high magnification (c); (d) Optical photograph of the surface contact between the sodium / phosphorus composite anode material Na3P@Na-3 and NZSP and SEM images of its cross-section: low magnification (e) and high magnification (f). Pure sodium has poor wettability to solid electrolytes. Figure 2 In (a), sodium / phosphorus composite anode materials exhibit good wettability to solid electrolytes. Figure 2 (d) shows that the sodium-phosphorus composite negative electrode constructed by adding an appropriate amount of phosphorus to molten sodium can significantly improve the contact between metallic sodium and solid electrolyte. Figure 2 In the middle (b) and (c), the images are magnified scanning electron microscope images of (a). Figure 2 In the middle, (e) and (f) are magnified scanning electron microscope images of (d).

[0035] This invention describes the electrochemical impedance spectroscopy (EIS) testing of symmetrical batteries assembled with NZSP solid electrolytes using composite anode materials of different compositions. Figure 3 As shown in (b), it was found that with the introduction of red phosphorus (P), the impedance of the symmetrical cell decreased from 1774 Ωcm. 2Reduced to 77.4 Ωcm 2 This significantly reduces the interfacial impedance between the anode material and the solid electrolyte, indicating that the composite anode material can significantly improve the interface problem of solid sodium metal batteries.

[0036] Figure 4 The EIS spectrum of a symmetrical cell assembled using a composite negative electrode with a sodium to black phosphorus mass ratio of 100:3 shows that the addition of black phosphorus further reduces the interfacial impedance of the symmetrical cell (66.3 Ωcm). 2 ).

[0037] A 2032-type coin cell was assembled in a glove box under an argon (Ar) atmosphere with H2O and O2 contents both below 0.1 ppm. The AC impedance spectrum and cycle life of the coin cell were tested. Constant current charge-discharge tests were conducted at room temperature on coin cells using composite sodium electrode materials with different component contents. Figure 5 , Figure 6 and Figure 7 As shown, the test results indicate that the symmetric cell using Na3P@Na-3 as the electrode has the longest cycle life, exceeding 500 hours, proving that the addition of phosphorus significantly improves the cycle life of the cell. Conversely, the Na3P@Na-1 symmetric cell exhibits the worst cycle performance, failing at 0.1 mA cm⁻¹ at room temperature. -2 Under the given current density, a significant short circuit occurred within 40 hours.

[0038] To evaluate the practicality of the Na3P@Na-3 composite sodium anode, an all-solid-state sodium battery, NVP / NZSP / Na3P@Na-3, coupled with a Na3V2(PO4)3 (NVP) cathode, was assembled in a glove box under an argon (Ar) atmosphere with H2O and O2 contents both below 0.1 ppm. The electrochemical performance of the NVP / NZSP / Na3P@Na-3 all-solid-state battery was tested at room temperature. (See attached table). Figure 8 (a) Specific capacity and coulombic efficiency variation curves of NVP / NZSP / Na3P@Na-3 under different rate conditions and (b) charge-discharge curves at different rates; (c) Specific capacity and coulombic efficiency variation curves of NVP / NZSP / Na3P@Na-3 at 1.0C rate and (d) charge-discharge curves with different cycle numbers. Figure 8 In the middle (a), the discharge specific capacity and coulombic efficiency of the NVP / NZSP / Na3P@Na-3 all-solid-state battery at rates of 0.1C, 0.2C, 0.5C, 1.0C and 0.1C are shown. It can be seen that the coulombic efficiency of the all-solid-state battery is always greater than 96% at different rates. Figure 8 (b) shows an all-solid-state battery with an active material loading of 1.27 mg cm⁻¹ at a rate of 0.1–1.0 C and a voltage window of 2.5–4.0 V. -2The static charge / discharge curves show that the full cell did not exhibit significant capacity decay with increasing rate, indicating that the NVP / NZSP / Na3P@Na-3 all-solid-state battery possesses desirable rate performance. Further testing of the long-cycle performance of the NVP / NZSP / Na3P@Na-3 all-solid-state battery at 1C rate (e.g., ...) Figure 8 In the middle (c)), the full cell can stably cycle more than 240 times at a 1.0C rate, with a capacity retention rate of up to 96.3%; Figure 8 In the middle (d), the charge-discharge curves of the NVP / NZSP / Na3P@Na-3 all-solid-state battery at a rate of 1.0C with different number of cycles are shown. After 100 cycles, no significant decrease in specific capacity was observed with the increase of the number of cycles, indicating that the NVP / NZSP / Na3P@Na-3 all-solid-state battery has good cycle performance.

[0039] As can be seen from the above embodiments, the sodium-phosphorus composite anode material provided by the present invention has excellent ionic conductivity; the sodium-phosphorus composite anode material has good interface matching with NZSP, which can effectively regulate Na + The ion exfoliation / deposition behavior accelerates interfacial charge transfer while limiting the expansion of metallic sodium and the growth of sodium dendrites; an NVP / NZSP / Na3P@Na-3 all-solid-state battery was assembled, which exhibits excellent rate performance and cycle performance.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A solid-state sodium metal battery, comprising a positive electrode, a negative electrode, and a solid electrolyte; The positive electrode is Na3V2(PO4)3; The solid electrolyte is Na. 3.1 Zr 1.95 Mg 0.05 Si2PO 12 ; The negative electrode is a sodium-phosphorus composite negative electrode material; The sodium-phosphorus composite anode material is prepared by means of metallic sodium and phosphorus in a mass ratio of 100:1 to 5, wherein the phosphorus includes red phosphorus (P) and / or black phosphorus (BP). The preparation method of the sodium-phosphorus composite anode material includes the following steps: Under an argon atmosphere, molten sodium and phosphorus are mixed and stirred to obtain a sodium-phosphorus composite negative electrode.

2. The solid-state sodium metal battery according to claim 1, characterized in that, The mass ratio of sodium to phosphorus is 100:1, 100:2, 100:3, 100:4, or 100:

5.

3. The solid-state sodium metal battery according to claim 1, characterized in that, The stirring time is 8-12 minutes.

4. The solid-state sodium metal battery according to claim 1, characterized in that, Phosphorus is added to molten sodium.

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