Phosphorus-based negative electrode material with solid electrolyte interface and preparation method and application thereof

Abstract

The application relates to the technical field of lithium / sodium ion battery negative electrode materials, in particular to a phosphorus-based negative electrode material with a solid electrolyte interface and a preparation method and application thereof, the method comprises the following steps: mixing phosphorus powder, a carbon material and a metal fluoride and performing ball milling to obtain a composite negative electrode material; and performing sieving treatment on the composite negative electrode material to obtain the phosphorus-based negative electrode material. According to the application, the metal fluoride is doped to in-situ construct a solid electrolyte interface with high strength and high lithium ion / electron transmission, so that the cycle stability and the rate performance of the battery are improved. When the lithium ion battery is discharged, the metal fluoride can in-situ construct a solid electrolyte interface rich in fluorinated lithium with high Young's modulus and lithium-metal alloy with high ion / electron conductivity on the surface of phosphorus-carbon particles prior to phosphorus-carbon lithium intercalation, the solid electrolyte interface can enhance the strength of the solid electrolyte interface by means of the fluorinated lithium with high Young's modulus, so as to inhibit the expansion of the phosphorus-carbon negative electrode, and the cycle stability is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery materials, in particular to a phosphorus-based negative electrode material with a solid electrolyte interface and a preparation method and application thereof. BACKGROUND

[0002] With the market's increasing demand for the energy density of batteries, developing negative electrode materials with high specific capacity is an effective means. Among them, phosphorus-carbon negative electrode has high specific capacity and excellent electronic conductivity, making it a current research hotspot and development direction. However, the volume expansion of phosphorus particles, the over-thickness of the electrode sheet, and the electrode pulverization risk will lead to the performance degradation of the battery.

[0003] In the prior art, in order to solve the volume expansion problem of phosphorus, the commonly used technical means is to be compounded with carbon materials such as graphite to form a phosphorus-carbon negative electrode, and a phosphorus-carbon bond is usually formed to inhibit the volume expansion of phosphorus during lithium storage. In addition, while being compounded with carbon materials, metal elements can also be doped to improve the conductivity, and at the same time help to form a large number of P-C bonds to improve the lithium storage performance and maintain the structural stability of phosphorus. Or by constructing a carbon skeleton to improve the volume expansion problem of phosphorus. However, these methods cannot well solve the interface problem of phosphorus, and the rate performance improvement is also limited. At present, new technical means are urgently needed to solve the volume expansion and rate performance of phosphorus-based materials. How to construct an electrolyte interface with excellent performance is the key to the excellent electrochemical performance of phosphorus-carbon materials. SUMMARY

[0004] The embodiments of the present application provide a phosphorus-based negative electrode material with a solid electrolyte interface and a preparation method and application thereof. In the ball milling process, metal fluoride particles, carbon materials and phosphorus are in-situ constructed to form a solid electrolyte interface with high strength and high lithium ion / electron transmission, thereby improving the cycle stability and rate performance of the battery. The lithium fluoride with high Young's modulus is used to enhance the strength of the solid electrolyte interface to inhibit the expansion of the phosphorus-carbon negative electrode, thereby improving the cycle stability.

[0005] In order to solve the above technical problems, in a first aspect, the embodiments of the present application provide a preparation method of a phosphorus-based negative electrode material with a solid electrolyte interface, comprising the following steps: first, mixing phosphorus powder, carbon materials and metal fluoride particles and ball milling to obtain a composite negative electrode material; then, screening the composite material to obtain a phosphorus-based composite material.

[0006] In some example embodiments, the metal fluoride includes a transition metal fluoride.

[0007] In some example embodiments, the metal fluoride includes one or more of antimony fluoride, bismuth fluoride, tin fluoride and indium fluoride.

[0008] In some example embodiments, the phosphorus material includes one or more of black phosphorus, red phosphorus, and purple phosphorus.

[0009] In some example embodiments, the carbon material includes one or more of graphite, carbon nanotube, graphene, and graphyne.

[0010] In some example embodiments, when the phosphorus powder, the carbon material, and the metal fluoride particles are mixed, the mass ratio of the phosphorus powder, the carbon material, and the metal fluoride is (80-50): (50-5): (20-2).

[0011] In some example embodiments, the phosphorus powder, the carbon material, and the metal fluoride are ball milled in a ball milling tank; wherein the ball-to-material mass ratio of the ball milling is (80-10):1, the self-rotation speed is 200 r / min-800 r / min, and the ball milling time is 12 h-48 h.

[0012] In some example embodiments, the particle size of the phosphorus-based negative electrode material is 200 mesh-1000 mesh.

[0013] In a second aspect, the embodiments of the present application also provide a phosphorus-based negative electrode material with a solid electrolyte interface, which is prepared by the preparation method of the phosphorus-based negative electrode material with a solid electrolyte interface described in the above embodiments; the phosphorus-based negative electrode material includes a phosphorus / carbon-based negative electrode material core and a metal fluoride-rich coating layer on the surface of the core.

[0014] In addition, the embodiments of the present application also provide an application of the phosphorus-based negative electrode material with a solid electrolyte interface described in the above embodiments in a lithium ion battery, a sodium ion battery, and a potassium ion battery.

[0015] The technical solutions provided by the embodiments of the present application have at least the following advantages:

[0016] The embodiments of the present application provide a phosphorus-based negative electrode material with a solid electrolyte interface, a preparation method thereof, and an application. The method includes the following steps: first, mixing and ball milling a phosphorus powder, a carbon material, and a metal fluoride to obtain a composite negative electrode material; and then, sieving the composite negative electrode material to obtain a phosphorus-based negative electrode material. The ball milling method is used to jointly prepare the composite negative electrode material from the phosphorus, the carbon, and the metal fluoride. Compared with the single phosphorus and carbon ball milling, the preparation method of the present application forms a metal fluoride on the surface of the phosphorus / carbon negative electrode. The composite material forms a solid electrolyte interface layer rich in fluoride and metal alloy on the surface during the cycle process. The in-situ interface layer has the following characteristics: high Young's modulus and low impedance. The interface layer is beneficial to improving the cycle stability and rate performance of the material. BRIEF DESCRIPTION OF DRAWINGS

[0017] One or more embodiments are illustrated by way of example in the drawings and figures that are not limiting of the embodiments, unless otherwise specifically noted, and the drawings and figures are not necessarily drawn to scale.

[0018] Figure 1 is a flow chart of a preparation method of a phosphorus-based negative electrode material with a solid electrolyte interface prepared in an embodiment of the present application.

[0019] Figure 2 is a preparation process schematic diagram of a phosphorus-carbon negative electrode material provided in an embodiment of the present application.

[0020] Figure 3 is a schematic diagram of a phosphorus-carbon negative electrode in which a solid electrolyte interface is constructed in situ during a cycle process provided in an embodiment of the present application.

[0021] Figure 4 is a SEM image of BP-G-CNT-SbF3 prepared in Embodiment 1 of the present application.

[0022] Figure 5 is a TEM image of the BP-G-CNT-SbF3 composite material in Embodiment 1 of the present application.

[0023] Figure 6 is an XRD comparison diagram of the BP-G-CNT-SbF3 and BP-G-CNT composite materials in Embodiment 1 and Comparative Example 1 of the present application.

[0024] Figure 7 is an EIS comparison diagram of the BP-G-CNT-SbF3 and BP-G-CNT composite materials in Embodiment 1 and Comparative Example 1 of the present application.

[0025] Figure 8 is a cycle comparison diagram of the BP-G-CNT-SbF3 and BP-G-CNT composite materials in Embodiment 1 and Comparative Example 1 of the present application.

[0026] Figure 9 is a rate comparison diagram of the BP-G-CNT-SbF3 and BP-G-CNT composite materials in Embodiment 1 and Comparative Example 1 of the present application.

[0027] Figure 10 is an interface comparison diagram of the BP-G-CNT-SbF3 and BP-G-CNT composite materials after 350 cycles in Embodiment 1 and Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0028] As known from the background art, carbon material and phosphorus are compounded, or metal particles are added, to form a phosphorus-carbon material to improve its electrochemical performance, but the volume expansion of the phosphorus-carbon material during the cycle process still exists, the interface is destroyed, and the capacity attenuation is serious in the later cycle.

[0029] To solve the above technical problems, the application provides a phosphorus-based negative electrode material with a solid electrolyte interface and a preparation method and application thereof. The method comprises the following steps: firstly, mixing phosphorus powder, carbon material and metal fluoride and performing ball milling to obtain a composite negative electrode material; and then, performing sieving treatment on the composite negative electrode material to obtain the phosphorus-based negative electrode material. The application needs to construct a phosphorus-carbon negative electrode through a grinding method, form metal fluoride on the surface of the phosphorus-carbon negative electrode, and form a solid electrolyte with high Young's modulus and low impedance characteristics in the cycle process to protect the inner phosphorus-carbon negative electrode, so that the patent has excellent cycle stability and rate performance.

[0030] The embodiments of the application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art can understand that in the embodiments of the application, many technical details are proposed in order to enable the reader to better understand the application. However, the technical solutions claimed by the application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0031] Reference Figure 1 , the application provides a preparation method of a phosphorus-based negative electrode material with a solid electrolyte interface, comprising the following steps:

[0032] Step S1, mixing phosphorus powder, carbon material and metal fluoride particles and performing ball milling to obtain a composite negative electrode material.

[0033] Step S2, sieving treatment on the composite material to obtain a phosphorus-based composite material.

[0034] In some embodiments, when the phosphorus powder, carbon material and metal fluoride particles are mixed, the mass ratio of the phosphorus powder, carbon material and metal fluoride is (80% to 50%):(50% to 5%):(20% to 2%).

[0035] The preparation method of the application is economical, simple, efficient and easy to operate. The application obtains a phosphorus / carbon / metal composite negative electrode material by adding metal fluoride and phosphorus, carbon material under ball milling, and obtains the optimal hybridization range of phosphorus, carbon and metal fluoride (80% to 50%):(50% to 10%):(20% to 2%). At a current density of 1 A / g, the capacity of 1006.88 mAh g -1 can still be provided after 350 cycles, and the capacity retention rate reaches 66.23%. At the same time, the composite material can still provide a specific capacity of 893.84 mAh g -1 at a large current of 15 A g -1 . The preparation process is easy to control, and the battery performance is excellent, which is conducive to industrial production and application.

[0036] The application builds a solid electrolyte interface with high strength and high lithium ion / electron transmission in situ by incorporating metal fluoride, thereby improving the cycle stability and rate performance of the battery. When the lithium ion battery is discharged, the fluorinated metal can build a solid electrolyte interface rich in fluorinated lithium with high Young's modulus and lithium-metal alloy with high ion / electron conductivity on the surface of the phosphorus-carbon particles in situ prior to the phosphorus-carbon lithium intercalation. It can enhance the strength of the solid electrolyte interface by means of the fluorinated lithium with high Young's modulus to inhibit the expansion of the phosphorus-carbon negative electrode, thereby improving the cycle stability. At the same time, by means of the lithium-metal alloy with high ion / electron conductivity, the impedance of the solid electrolyte interface is reduced, thereby improving the rate performance.

[0037] In some embodiments, the metal fluoride includes a transition metal fluoride.

[0038] In some embodiments, the metal fluoride includes one or more of antimony fluoride, bismuth fluoride, tin fluoride and indium fluoride.

[0039] In some embodiments, the phosphorus material includes one or more of black phosphorus, red phosphorus, and purple phosphorus.

[0040] In some embodiments, the carbon material includes one or more of graphite, carbon nanotube, graphene, and graphyne.

[0041] In some embodiments, the phosphorus powder, the carbon material and the metal fluoride are ball milled in a ball milling jar; wherein the ball-to-material mass ratio of the ball milling is (80-10):1, the self-rotation speed is 200r / min-800r / min, and the ball milling time is 12h-48h.

[0042] In some embodiments, the particle size of the phosphorus-based negative electrode material is 200-1000 mesh.

[0043] The preparation method of the phosphorus-based negative electrode material with a solid electrolyte interface provided by the application is as follows:

[0044] (1) The black phosphorus, the carbon material and the fluorinated metal are weighed in a certain mass ratio in an argon atmosphere glove box and loaded into a 100mL zirconia jar.

[0045] (2) The zirconia jar is provided with 1:2:4 mass ratio of 15mm:8mm:5mm zirconia balls.

[0046] (3) A planetary ball mill is used to ball mill the materials at a certain speed for a period of time to obtain a uniform material product.

[0047] (4) The ball milling product is introduced into a 200 mesh screen for sieving, and the final fluorinated metal fluoride / phosphorus / carbon composite material is sieved out.

[0048] Example 1

[0049] (1) Black phosphorus, graphite, carbon nanotube, antimony fluoride were weighed into a 100 mL zirconia jar in the glove box in the argon atmosphere according to the mass ratio of 65:20:10:5.

[0050] (2) The zirconia jar was filled with 1:2:4 mass ratio of 15 mm:8 mm:5 mm zirconia balls, 42.85 g, 85.71 g, 171.43 g respectively.

[0051] (3) The planetary ball mill was used to mill for 24 hours at 350 rpm.

[0052] (4) The ball-milled product was introduced into a 200-mesh sieve for sieving, and the final antimony fluoride-doped black phosphorus / graphite / carbon nanotube composite material was screened out. The morphology and transmission electron microscopy (TEM) image (including element distribution map) of the prepared material are shown in Figure 4 and Figure 5 .

[0053] Comparative Example 1

[0054] The difference between this comparative example 1 and example 1 is that no antimony fluoride is added. That is, the proportions of black phosphorus, graphite, and carbon nanotube are added according to the mass ratio of 70:20:10. The crystal structure of the comparison between example 1 and comparative example 1 is shown in Figure 6 .

[0055] Comparative Example 2

[0056] The difference between this comparative example 2 and example 1 is that the phosphorus raw material is selected as red phosphorus material.

[0057] Comparative Example 3

[0058] The difference between this comparative example 3 and example 1 is that the carbon material is selected as single graphite material.

[0059] Comparative Example 4

[0060] The difference between this comparative example 4 and example 1 is that the metal fluoride is selected as bismuth fluoride.

[0061] Comparative Example 5

[0062] The difference between this comparative example 5 and example 1 is that the metal fluoride is selected as tin fluoride.

[0063] Comparative Example 6

[0064] The difference between this comparative example 6 and example 1 is that the content of black phosphorus is 80%. That is, the proportions of black phosphorus, graphite, and carbon nanotube are added according to the mass ratio of 80:20:10:5.

[0065] Comparative Example 7

[0066] The difference between Comparative Example 7 and Example 1 is that the content of black phosphorus is 50%. That is, the ratio of black phosphorus, graphite, carbon nanotube is added according to the mass ratio of 50:20:10:5.

[0067] Comparative Example 8

[0068] The difference between Comparative Example 8 and Example 1 is that the content of carbon is changed. That is, the ratio of black phosphorus, graphite, carbon nanotube is added according to the mass ratio of 65:14:6:5.

[0069] Comparative Example 9

[0070] The difference between Comparative Example 9 and Example 1 is that the content of fluoride metal material is changed. That is, the ratio of black phosphorus, graphite, carbon nanotube is added according to the mass ratio of 65:20:10:2.

[0071] Comparative Example 10

[0072] The difference between Comparative Example 10 and Example 1 is that the content of fluoride metal material is changed. That is, the ratio of black phosphorus, graphite, carbon nanotube is added according to the mass ratio of 65:20:10:20.

[0073] Example 1 and Comparative Examples 1-10 are assembled into lithium ion batteries, respectively numbered as Battery 0, Batteries A-J. Among them, the battery structure: the battery structure of this experiment is a half battery also called a button cell. The working electrode is the electrode current collector and the active material layer (metal fluoride / phosphorus / carbon material) on the surface thereof, the counter electrode is a lithium metal sheet, and the middle is a separator, and the steel shell is filled with electrolyte. The electrode current collector is a copper foil with a thickness of 10 μm, the separator is a PE-based film with a thickness of 5 μm, and the surface is coated with a PVDF oil-based separator with a thickness of 1 μm; the composition of the electrolyte: a mixture of EC, DEC, LiPF6, FEC and LiOFB with a mass ratio of 40:40:12:5:3; the preparation method of the working electrode includes: electrode material slurry containing phosphorus-based material, binder (PVDF) and conductive agent (acetylene black), coating the slurry on the surface of the electrode current collector to obtain the working electrode, wherein the mass density of the electrode material coating is 1.5 mg / cm 2 , the thickness of the electrode coating is 100 μm; the mass ratio of phosphorus-based material, binder (PVDF) and conductive agent (acetylene black) is 8:1:1.

[0074] The electrochemical performance was tested, and the cycle test method included: constant current charge and discharge on a blue electric test system: 350 cycles at a current density of 1 A / g in the voltage range of 0-2.5 V. Table 1 is the cycle performance and interface data of the phosphorus-based negative electrode materials in Example 1 and Comparative Examples 1-10 of the present application. The test results are shown in Table 1 as follows, in which the interface impedance, cycle performance, rate performance and interface performance after cycling of black phosphorus / carbon nanotube / graphite metal fluoride in Example 1 and black phosphorus / carbon nanotube / graphite in Comparative Example 1 are shown in Figure 7 、 Figure 8 、 Figure 9 and Figure 10 These show that BP-G-CNT-SbF3 has lower interface impedance (as shown in Figure 7 ). The specific discharge capacity of Example 1 (BP-G-CNT-SbF3) after 350 cycles is still 1006 mAh g -1 , and the capacity retention rate is 66.2%, while the capacity retention rate of Comparative Example BP-G-CNT is 13.7% (as shown in Figure 8 ). Example 1 has better rate performance (as shown in Figure 9 ), and has a more complete cycle interface after cycling.

[0075] Table 1 Electrochemical performance results of phosphorus-based negative electrodes obtained by different preparation processes

[0076]

[0077]

[0078] From Example 1 and Comparative Example 1, it can be seen that without the addition of metal fluoride, battery A cannot form a LiF interface layer with high mechanical strength during the cycle process, which cannot effectively ensure the integrity of the electrode material. At the same time, the capacity is low.

[0079] By comparing Example 1 and Comparative Example 2, the performance of battery B is worse than 0, which is due to the cycle performance of red phosphorus and black phosphorus. Black phosphorus has excellent electrochemical performance and conductivity, while red phosphorus has low conductivity.

[0080] Example 1 and Comparative Example 2 show that when the single carbon material is only graphite, the capacity retention rate is found to be low, because carbon nanotubes have excellent conductivity and flexibility, which can ensure the stability of the electrode structure, so as to improve the cycle stability.

[0081] As can be seen from Example 1 and Comparative Examples 4-5, the capacity development and capacity retention of batteries D and E are both low, because during the cycle process, bismuth fluoride can be embedded in lithium before phosphorus carbon, forming lithium bismuth alloy to increase the conductivity of lithium ions, but the de-lithiation is earlier than phosphorus carbon, which cannot play a significant role. The reaction potential of tin is about 0.2-0.3V, which is later than the embedding of lithium in phosphorus carbon, and the formed alloy cannot improve the conductivity when lithium is embedded in phosphorus carbon.

[0082] As can be seen from Comparative Example 1 and Comparative Examples 6 and 7, the initial capacity of batteries F and G is related to the content of black phosphorus, and the higher the content of black phosphorus, the higher the first cycle capacity. However, too high black phosphorus will lead to a decrease in cycle stability, and too low black phosphorus will lead to a low capacity.

[0083] As compared with Example 1, Comparative Example 8 reduces the carbon content, resulting in an increase in initial capacity but a decrease in carbon layer coating effect, leading to a decrease in cycle stability.

[0084] As can be seen from Example 1 and Comparative Examples 9 and 10, when the metal fluoride is reduced and cannot form an effective solid electrolyte layer, the cycle stability is poor. When the metal fluoride is increased, the capacity development is reduced, and the cycle stability is slightly increased.

[0085] The application also provides a phosphorus-based negative electrode material with a solid electrolyte interface, which is prepared by the preparation method of the phosphorus-based negative electrode material with a solid electrolyte interface. Figure 2 As shown in the figure, the phosphorus-based negative electrode material includes a phosphorus / carbon-based negative electrode material core and a metal fluoride-rich coating layer on the surface of the core.

[0086] In addition, the application also provides an application of the phosphorus-based negative electrode material with a solid electrolyte interface in a lithium ion battery, a sodium ion battery, a potassium ion battery or other secondary batteries.

[0087] The application provides a phosphorus-based negative electrode material with a solid electrolyte interface, a preparation method and an application thereof. The method comprises the following steps: firstly, mixing phosphorus powder, carbon material and metal fluoride and performing ball milling to obtain a composite negative electrode material; and then, performing sieving treatment on the composite negative electrode material to obtain a phosphorus-based negative electrode material. In the application, the ball milling method is used to prepare the composite negative electrode material by taking phosphorus, carbon and metal fluoride as raw materials. Compared with the ball milling of single phosphorus and carbon, the preparation method of the application forms metal fluoride on the surface of the phosphorus / carbon negative electrode. The composite material forms a layer rich in fluoride metal on the surface during the cycle process, and is easy to form a solid electrolyte interface layer rich in fluoride and metal alloy during the cycle process. The in-situ interface layer has the following characteristics: high Young's modulus and low impedance. The interface layer is beneficial to improving the cycle stability and rate performance of the material.

[0088] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for realizing the present application, and in actual applications, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make respective changes and modifications without departing from the spirit and scope of the present application, and therefore the protection scope of the present application should be limited by the scope defined by the claims.

Claims

1. A method for preparing a phosphorus-based anode material with a solid electrolyte interface, characterized in that, Includes the following steps: Phosphorus powder, carbon materials and metal fluoride particles are mixed and ball-milled to obtain a composite anode material; The composite anode material is sieved to obtain a phosphorus-based composite material.

2. The method for preparing a phosphorus-based anode material with a solid electrolyte interface according to claim 1, characterized in that, The metal fluorides include transition metal fluorides.

3. The method for preparing a phosphorus-based anode material with a solid electrolyte interface according to claim 1, characterized in that, The metal fluoride includes one or more of antimony fluoride, bismuth fluoride, tin fluoride, and indium fluoride.

4. The method for preparing a phosphorus-based anode material with a solid electrolyte interface according to claim 1, characterized in that, The phosphorus powder includes one or more of black phosphorus, red phosphorus, and purple phosphorus.

5. The method for preparing a phosphorus-based anode material with a solid electrolyte interface according to claim 1, characterized in that, The carbon material includes one or more of graphite, carbon nanotubes, graphene, and graphyne.

6. The method for preparing a phosphorus-based anode material with a solid electrolyte interface according to claim 1, characterized in that, When phosphorus powder, carbon materials and metal fluoride particles are mixed, the mass ratio of phosphorus powder, carbon materials and metal fluoride is (80%~50%): (50%~5%): (20%~2%).

7. The method for preparing a phosphorus-based anode material with a solid electrolyte interface according to claim 1, characterized in that, Phosphorus powder, carbon materials, and metal fluorides are ball-milled in a ball mill jar; wherein the ball-to-material mass ratio is (80-10):1, the rotation speed is 200-800 r / min, and the ball milling time is 12-48 h.

8. The method for preparing a phosphorus-based anode material with a solid electrolyte interface according to claim 1, characterized in that, The particle size of the phosphorus-based anode material is 200 mesh to 1000 mesh.

9. A phosphorus-based anode material having a solid electrolyte interface, characterized in that, The phosphorus-based anode material with a solid electrolyte interface is prepared by any one of claims 1 to 8; the phosphorus-based anode material includes a phosphorus / carbon-based anode material core and a metal fluoride-rich coating layer located on the surface of the core.

10. The application of a phosphorus-based anode material with a solid electrolyte interface as described in claim 9 in lithium-ion batteries, sodium-ion batteries, and potassium-ion batteries.

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