阅读说明：本技术 磷酸盐掺杂的金属磷化物及其制备方法和应用、金属磷化物复合材料及其制备方法和应用 (Phosphate-doped metal phosphide, preparation method and application thereof, metal phosphide composite material, preparation method and application thereof ) 是由 许冠南 季顺平 于 2021-07-28 设计创作，主要内容包括：本发明涉及电池材料技术领域,尤其涉及磷酸盐掺杂的金属磷化物及其制备方法和应用、金属磷化物复合材料及其制备方法和应用。本发明提供的磷酸盐掺杂的金属磷化物的制备方法,包括以下步骤：将金属氧化物和单质磷混合,进行球磨,得到所述磷酸盐掺杂的金属磷化物。本发明采用金属氧化物和单质磷作为原料,通过简单的球磨,可以实现金属氧化物和单质磷之间氧化还原反应的发生,并最终形成磷酸盐掺杂的金属磷化物材料。制备方法简单,成本低；同时由于磷酸盐的掺杂能够有效的改善充放电过程中巨大的体积变化,利于SEI膜的稳定,从而赋予电极材料更好的循环稳定性。(The invention relates to the technical field of battery materials, in particular to phosphate-doped metal phosphide, a preparation method and application thereof, a metal phosphide composite material, and a preparation method and application thereof. The preparation method of the phosphate-doped metal phosphide provided by the invention comprises the following steps: and mixing the metal oxide with simple substance phosphorus, and performing ball milling to obtain the phosphate-doped metal phosphide. The invention adopts metal oxide and simple substance phosphorus as raw materials, and can realize the oxidation-reduction reaction between the metal oxide and the simple substance phosphorus through simple ball milling, and finally form the phosphate-doped metal phosphide material. The preparation method is simple and low in cost; meanwhile, the doping of the phosphate can effectively improve the huge volume change in the charge and discharge process, and is beneficial to the stability of the SEI film, so that the electrode material is endowed with better cycle stability.)

1. A method for preparing a phosphate-doped metal phosphide, characterized by comprising the steps of:

and mixing the metal oxide with simple substance phosphorus, and performing ball milling to obtain the phosphate-doped metal phosphide.

2. The method of claim 1, wherein the metal oxide comprises V₂O₅、V₂O₄、V₂O₃、VO、CrO、Cr₂O₃、CrO₃、MnO、MnO₂、Mn₂O₃、Mn₃O₄、FeO、Fe₂O₃、Fe₃O₄、CoO、Co₂O₃、Co₃O₄、NiO、Ni₂O₃、Cu₂O, CuO and ZnO;

the average particle diameter of the metal oxide is 5 nm-1000 μm.

3. The preparation method of claim 1, wherein the elemental phosphorus comprises one or more of red phosphorus, white phosphorus, purple phosphorus, black phosphorus and yellow phosphorus;

the dimensionality of the simple substance phosphorus is 0-3 dimensionality;

the average particle size of the simple substance phosphorus is 1 nm-1000 mu m.

4. The method according to claim 1, wherein the molar ratio of the metal oxide to the elemental phosphorus is (0.05 to 20): 1.

5. the preparation method of claim 1, wherein the rotation speed of the ball mill is 200-1200 rpm, the time is 0.5-24 h, and the ball-to-material ratio is (5-80): 1.

6. The phosphate-doped metal phosphide prepared by the preparation method of any one of claims 1 to 5, wherein the phosphate-doped metal phosphide is characterized by comprising metal phosphide and phosphate doped in the metal phosphide.

7. Use of the phosphate doped metal phosphide of claim 6 in a potassium-ion battery.

8. A metal phosphide composite material comprising a blend of phosphate-doped metal phosphide and carbon;

the phosphate doped metal phosphide of claim 6.

9. The method of preparing a metal phosphide composite material as set forth in claim 8, characterized by comprising the steps of:

mixing metal oxide, elemental phosphorus and a carbon material, and carrying out first ball milling to obtain the metal phosphide composite material;

or mixing phosphate-doped metal phosphide and a carbon material, and carrying out second ball milling to obtain the metal phosphide composite material.

10. Use of the metal phosphide composite material as set forth in claim 8 or the metal phosphide composite material prepared by the preparation method as set forth in claim 9 in a potassium-ion battery.

Technical Field

The invention relates to the technical field of battery materials, in particular to phosphate-doped metal phosphide, a preparation method and application thereof, a metal phosphide composite material, and a preparation method and application thereof.

Background

Due to the unregulated development and use of traditional non-renewable fossil fuels (coal, oil and natural gas), not only are serious environmental pollution problems posed, but also the energy crisis is inevitable. There is an urgent need for new forms of renewable energy, particularly more environmentally friendly energy sources such as solar, wind, geothermal and tidal energy. However, most of these renewable energy sources have some common features, such as regional or intermittent. This requires the deployment of reliable energy storage devices to achieve a reasonable distribution of energy peaks and troughs. As for energy storage, compared with physical energy storage (such as flywheel energy storage, pumped storage, compressed air energy storage, etc.), chemical energy storage has higher conversion efficiency, and in particular, lithium ion batteries have been rapidly developed in recent years and are widely used in daily life of various portable electronic devices, energy automobiles, and the like. However, there are some problems to be solved in the large-scale application of lithium ion batteries as energy storage devices, the most direct of which is the cost problem, and the shortage and the uneven distribution of metal resources such as lithium, cobalt and the like cause serious uncertainties in the wide application of lithium ion batteries in energy storage.

Compared with Li, Na and K have higher natural abundance and are expected to reduce the cost. However, as the ionic radii of Na and K are larger, a larger volume expansion is caused during charge and discharge, resulting in poorer cycle performance of the material. For Na and K ion battery negative electrode materials, the traditional carbon-based material has lower energy density (the theoretical specific capacity is less than 300 mA.h.g)^-1) Sulfide negative electrode materials have a higher energy density than carbon-based materials, but have the problem of a higher discharge voltage plateau, typically above 1.0V (vs.k/K)⁺). Phosphorus and its metal phosphide materials have a low discharge plateau, generally around 0.5V (Vs.K/K)⁺) And heightThe energy density is one of ideal materials of the negative electrode material of the Na and K ion battery. At present, research on phosphorus and metal phosphide materials thereof for negative electrode materials of Na and K ion batteries has been reported in some documents, and phosphorus and metal phosphide materials thereof also face a problem of huge volume expansion during discharge, so that it is difficult to form a stable SEI (solid electrolyte interface) film on the surface thereof, resulting in poor cycle performance of the materials. In the half cell test for potassium metal, for conventional phosphide, 0.5A g^-1Under the multiplying power condition of (2), the severe capacity attenuation (the capacity is lower than 100 mA.h.g) appears after about 300 cycles^-1) The practical commercial value of such materials is severely hampered.

In view of the above problems, the current solutions mainly focus on several aspects: 1. reducing the size of the material to a nanometer level, 2, controlling the shape, such as forming a core-shell structure, a nanofiber, a nanosheet and the like, and 3, carrying out surface or bulk phase modification, such as coating, heteroatom doping and the like. However, the simple size reduction results in more reaction interfaces, the side reactions are increased, the process is complicated and complicated for controlling the morphology and modifying, and the cost and difficulty of commercialization are increased.

Disclosure of Invention

The invention aims to provide a phosphate-doped metal phosphide, a preparation method and application thereof, a metal phosphide composite material, a preparation method and application thereof.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of phosphate-doped metal phosphide, which comprises the following steps:

and mixing the metal oxide with simple substance phosphorus, and performing ball milling to obtain the phosphate-doped metal phosphide.

Preferably, the metal oxide comprises V₂O₅、V₂O₄、V₂O₃、VO、CrO、Cr₂O₃、CrO₃、MnO、MnO₂、Mn₂O₃、Mn₃O₄、FeO、Fe₂O₃、Fe₃O₄、CoO、Co₂O₃、Co₃O₄、NiO、Ni₂O₃、Cu₂O, CuO and ZnO;

the average particle diameter of the metal oxide is 5 nm-1000 μm.

Preferably, the elemental phosphorus comprises one or more of red phosphorus, white phosphorus, purple phosphorus, black phosphorus and yellow phosphorus;

the dimensionality of the simple substance phosphorus is 0-3 dimensionality;

the average particle size of the simple substance phosphorus is 1 nm-1000 mu m.

Preferably, the molar ratio of the metal oxide to the elemental phosphorus is (0.05-20): 1.

preferably, the rotation speed of the ball mill is 200-1200 rpm, the time is 0.5-24 h, and the ball-to-material ratio is (5-80): 1.

The invention also provides phosphate-doped metal phosphide prepared by the preparation method in the technical scheme, which comprises the metal phosphide and phosphate doped in the metal phosphide.

The invention also provides the application of the phosphate-doped metal phosphide in the technical scheme in a potassium ion battery.

The invention also provides a metal phosphide composite material, which comprises a phosphate-doped metal phosphide and carbon blend;

the phosphate-doped metal phosphide is the phosphate-doped metal phosphide in the technical scheme.

The invention also provides a preparation method of the metal phosphide composite material, which comprises the following steps:

mixing metal oxide, elemental phosphorus and a carbon material, and carrying out first ball milling to obtain the metal phosphide composite material;

or mixing phosphate-doped metal phosphide and a carbon material, and carrying out second ball milling to obtain the metal phosphide composite material.

The invention also provides the application of the metal phosphide composite material or the metal phosphide composite material prepared by the preparation method in the technical scheme in a potassium ion battery.

The invention provides a preparation method of phosphate-doped metal phosphide, which comprises the following steps: and mixing the metal oxide with simple substance phosphorus, and performing ball milling to obtain the phosphate-doped metal phosphide. The invention adopts metal oxide and simple substance phosphorus as raw materials, and can realize the oxidation-reduction reaction between the metal oxide and the simple substance phosphorus through simple ball milling, and finally form the phosphate-doped metal phosphide material. The preparation method is simple and low in cost; meanwhile, the doping of the phosphate can effectively improve the huge volume change in the charge-discharge process, which is beneficial to the stability of the SEI film, thereby endowing the electrode material with better cycle stability;

the invention also provides a metal phosphide composite material, which comprises phosphate-doped metal phosphide and carbon; the phosphate-doped metal phosphide is the phosphate-doped metal phosphide in the technical scheme. The addition of the carbon improves the conductivity of the material, improves the rate capability of the material, and makes up for the problem of conductivity reduction caused by the addition of phosphate to a certain extent.

Drawings

FIG. 1 is a schematic view of a process for preparing a metal phosphide composite material;

FIG. 2 is an XRD pattern of the phosphate doped metal phosphide described in example 1, example 5 and example 6 and the metal phosphide composite material described in example 8;

FIG. 3 is an SEM image of a metal phosphide composite material as described in example 8;

FIG. 4 is an energy spectrum of the metal phosphide composite material as set forth in example 8;

FIG. 5 is a graph showing the charge-discharge cycle of the metal phosphide composite material of example 8;

FIG. 6 is an IR spectrum of a metal phosphide composite material as set forth in example 8;

FIG. 7 is an XPS plot of a metal phosphide composite material as described in example 8;

FIG. 8 is a thermogravimetric plot of the phosphate doped metal phosphide described in example 7 in air;

FIG. 9 is a thermogravimetric plot of the metal phosphide composite material of example 8 in air;

FIG. 10 shows the IR spectra of the metal phosphide composites described in examples 1, 5 and 9;

FIG. 11 is an XRD pattern of the metal phosphide composite material of example 9;

FIG. 12 is a graph showing the charge and discharge cycles of the metal phosphide composite material according to example 9;

FIG. 13 is an XRD pattern of the phosphate doped metal phosphide described in example 2;

FIG. 14 is a graph showing the charge and discharge cycles of the metal phosphide composite material of example 2;

FIG. 15 shows an IR spectrum of a metal phosphide composite material as described in example 6.

Detailed Description

The invention provides a preparation method of phosphate-doped metal phosphide, which comprises the following steps:

and mixing the metal oxide with simple substance phosphorus, and performing ball milling to obtain the phosphate-doped metal phosphide.

In the present invention, all the starting materials for the preparation are commercially available products known to those skilled in the art unless otherwise specified.

In the present invention, the metal oxide preferably includes V₂O₅、V₂O₄、V₂O₃、VO、CrO、Cr₂O₃、CrO₃、MnO、MnO₂、Mn₂O₃、Mn₃O₄、FeO、Fe₂O₃、Fe₃O₄、CoO、Co₂O₃、Co₃O₄、NiO、Ni₂O₃、Cu₂O, CuO and ZnO; when the metal oxides are more than two of the above specific choices, the present invention does not have any special limitation on the proportion of the specific substances, and the specific substances can be mixed according to any proportion. In the present invention, the average particle diameter of the metal oxide is preferably 5nm to 1000. mu.m, more preferably 100nm to 100. mu.m, and most preferably 1 μm to 10 μm.

In the invention, the elementary phosphorus preferably comprises one or more of red phosphorus, white phosphorus, purple phosphorus, black phosphorus and yellow phosphorus; when the simple substance phosphorus is more than two of the specific choices, the invention has no special limitation on the proportion of the specific substances and can mix the substances according to any proportion. In the invention, the dimensionality of the simple substance phosphorus is preferably 0-3 dimensionality; the average particle size of the elemental phosphorus is preferably 1nm to 1000 μm, more preferably 100nm to 100m, and most preferably 1 μm to 10 μm.

In the invention, the molar ratio of the metal oxide to the elemental phosphorus is preferably (0.05-20): 1.

in the invention, the rotation speed of the ball mill is preferably 200-1200 rpm, more preferably 500-1200 rpm, and most preferably 800-1000 rpm; the time is preferably 0.5-24 h, more preferably 2-10 h, and most preferably 4-6 h; the ball-to-feed ratio is preferably (5-80): 1, more preferably (20-60): 1, and most preferably (20-40): 1. In the present invention, the ball milling is preferably performed in an argon atmosphere.

The invention also provides phosphate-doped metal phosphide prepared by the preparation method in the technical scheme, which comprises the metal phosphide and phosphate doped in the metal phosphide.

In the invention, the phosphate is formed in situ by oxidation-reduction reaction of oxide and simple phosphorus, so that the phosphate can be uniformly dispersed in the metal phosphide.

The invention also provides the application of the phosphate-doped metal phosphide in the technical scheme in a potassium ion battery. In the present invention, the phosphate-doped metal phosphide is preferably used as a negative electrode material of a potassium ion battery; the method of the present invention is not particularly limited, and the method may be performed by a method known to those skilled in the art.

The invention also provides a metal phosphide composite material, which comprises a phosphate-doped metal phosphide and carbon blend;

the phosphate-doped metal phosphide is the phosphate-doped metal phosphide in the technical scheme.

In the invention, the mass ratio of the phosphate-doped metal phosphide to carbon is preferably (1-10): 1, more preferably (2-6): 1, and most preferably (3-5): 1.

The invention also provides a preparation method of the metal phosphide composite material, which comprises the following steps:

mixing metal oxide, elemental phosphorus and a carbon material, and carrying out first ball milling to obtain the metal phosphide composite material;

or mixing phosphate-doped metal phosphide and a carbon material, and carrying out second ball milling to obtain the metal phosphide composite material.

The metal phosphide composite material is obtained by mixing metal oxide, elemental phosphorus and a carbon material and carrying out first ball milling.

In the present invention, the types and the amounts of the metal oxide and the elemental phosphorus are preferably defined in the above process for preparing the phosphate-doped metal phosphide, and are not described herein again.

In the invention, the carbon material preferably comprises one or more of graphite, graphene, carbon nanotubes, carbon nanofibers, carbon nanodots, carbon nanocones, coke, activated carbon, conductive carbon black and acetylene black; when the carbon material is two or more of the above specific choices, the present invention does not have any particular limitation on the ratio of the specific materials, and the specific materials may be mixed in any ratio. In the present invention, the carbon material preferably has an average particle diameter of 50nm to 100. mu.m, more preferably 50nm to 10 μm, and most preferably 100nm to 1 μm.

In the present invention, the mass ratio of the total mass of the metal oxide and elemental phosphorus to the carbon material is preferably 100: (3-90), more preferably 100: (5-60), most preferably 100: (10-30).

In the present invention, the process of the first ball milling preferably refers to the limitation of the ball milling in the process of preparing the phosphate-doped metal phosphide, and is not described herein again.

Or mixing phosphate-doped metal phosphide and a carbon material, and carrying out second ball milling to obtain the metal phosphide composite material.

In the present invention, the kind and the amount of the carbon material are preferably determined by referring to the above technical solution, and are not described herein again; the process of the second ball milling preferably refers to the limitation of the ball milling in the process of preparing the phosphate-doped metal phosphide, and the detailed description is omitted.

The invention also provides the application of the metal phosphide composite material or the metal phosphide composite material prepared by the preparation method in the technical scheme in a potassium ion battery. In the invention, the metal phosphide composite material is preferably used as a negative electrode material of a potassium ion battery; the method of the present invention is not particularly limited, and the method may be performed by a method known to those skilled in the art.

The phosphate-doped metal phosphide, the preparation method and application thereof, the metal phosphide composite material, the preparation method and application thereof provided by the invention are described in detail in the following with reference to the examples, but they should not be construed as limiting the scope of the invention.

Example 1

Fe with an average particle size of 10 μm in a molar ratio of 1:6₂O₃Mixing with red phosphorus with the average particle size of 20 microns, and carrying out ball milling in an argon atmosphere, wherein the ball-to-material ratio of the ball milling is 20:1, the rotating speed is 800rpm, and the time is 4 hours, so as to obtain phosphate-doped metal phosphide (the molar ratio of the phosphate to the metal phosphide is 3: 7);

XRD measurement of the phosphate-doped metal phosphideTest results are shown in fig. 2, and it can be seen from fig. 2 that the example successfully synthesizes the metal phosphide, and the metal phosphide is FeP₂But XRD does not show it due to the small grain size of the phosphate;

to verify the presence of phosphate, the phosphate-doped metal phosphide was subjected to infrared spectroscopy and the results are shown in figure 10, with a distinct phosphate absorption peak.

Example 2

With reference to the solution of example 1, with the only difference that the molar ratio is 1:3, the phosphate-doped metal phosphide is obtained (the molar ratio of the phosphate to the metal phosphide is 3: 7); the XRD test result of the phosphate doped metal phosphide is shown in fig. 13, which is that the metal phosphide in the phosphate doped metal phosphide is FeP.

Example 3

With reference to the solution of example 1, with the only difference that a molar ratio of 1:10 results in a phosphate doped metal phosphide (molar ratio of phosphate to metal phosphide of 3: 7); the XRD test result of the phosphate doped metal phosphide shows that the metal phosphide in the phosphate doped metal phosphide is FeP₂。

Example 4

With reference to the solution of example 1, with the only difference that a molar ratio of 1:12 results in a phosphate doped metal phosphide (molar ratio of phosphate to metal phosphide of 3: 7); the XRD test result of the phosphate doped metal phosphide shows that the metal phosphide in the phosphate doped metal phosphide is FeP₂And FeP₄。

Example 5

Referring to the technical solution of example 1, the difference is that the metal oxide is CuO with an average particle size of 1 micrometer, and the elemental phosphorus is black scale with an average particle size of 1 micrometer; the molar ratio of the metal oxide to the black scale is 1:2, the rotation speed of ball milling is 500rpm, the time is 8 hours, and the obtained phosphate-doped metal phosphide (the molar ratio of the phosphate to the metal phosphide is 1:5) is obtained; the phosphate-doped goldThe XRD test results of the phosphide are shown in figure 2. As can be seen from FIG. 2, the metal phosphide in the phosphate-doped metal phosphide is CuP₂But XRD does not show it due to the small grain size of the phosphate;

to verify the presence of phosphate, the phosphate-doped metal phosphide was subjected to infrared spectroscopy and the results are shown in figure 10, with a distinct phosphate absorption peak.

Example 6

Referring to the technical scheme of example 1, the only difference is that the metal oxide is ZnO with an average particle size of 30 nm; the molar ratio of the metal oxide to the black scale is 2:3, the rotation speed of ball milling is 1000rpm, the time is 4 hours, and the obtained phosphate-doped metal phosphide (the molar ratio of the phosphate to the metal phosphide is 1:5) is obtained; the XRD test results of the phosphate doped metal phosphide are shown in fig. 2. As can be seen from FIG. 2, the metal phosphide in the phosphate-doped metal phosphide is ZnP₂But XRD does not show it due to the small grain size of the phosphate;

to verify the presence of phosphate, the phosphate-doped metal phosphide was subjected to infrared spectroscopy and the results are shown in figure 15, with a distinct phosphate absorption peak.

Example 7

Mixing 2g of ZnO with the average particle size of 30nm and 1.5g of red phosphorus with the average particle size of 20 microns (the molar ratio of zinc oxide to red phosphorus is 1:2), and carrying out ball milling under an argon atmosphere, wherein the ball-to-material ratio of the ball milling is 20:1, the rotating speed is 1000rpm, and the time is 4 hours, so as to obtain a phosphate-doped metal phosphide (the molar ratio of the phosphate to the metal phosphide is 1: 5);

FIG. 8 shows the thermogravimetric curve of the phosphate-doped metal phosphide in air, and it can be seen from FIG. 8 that all the phosphorus is changed into P when the metal phosphide is heated in air₂O₅And zinc is completely generated into zinc oxide, so the thermogravimetric residual mass is increased, and the calculated mass fractions of the phosphate and phosphide are 34.7 and 65.3 respectively.

Example 8

Preparation according to FIG. 1Mixing 2g of ZnO with the average particle size of 30nm, 1.5g of red phosphorus with the average particle size of 20 microns (the molar ratio of zinc oxide to red phosphorus is 1:2) and 1.5g of conductive carbon black (which is 30 percent of the total mass of zinc oxide and red phosphorus), and carrying out ball milling in an argon atmosphere, wherein the ball-to-material ratio of the ball milling is 20:1, the rotating speed is 1000rpm, and the time is 4 hours, so as to obtain the metal phosphide composite material (the molar ratio of phosphate to metal phosphide is 1:5, and the mass ratio of the total mass of phosphate to the metal phosphide to the conductive carbon black is 7: 3); the XRD test results of the metal phosphide composite material are shown in fig. 2. As can be seen from FIG. 2, the metal phosphide in the metal phosphide composite material is ZnP₂But XRD does not show it due to the small grain size of the phosphate;

in order to verify the existence of phosphate, the metal phosphide composite material is subjected to infrared spectrum test, and the test result is shown in figure 6, wherein a distinct phosphate absorption peak exists.

The metal phosphide composite material is subjected to SEM test, the test result is shown in figure 3, and as can be seen from figure 3, the particle size of the metal phosphide composite material is different from dozens of nanometers to dozens of micrometers;

performing energy spectrum analysis on the metal phosphide composite material, wherein the test result is shown in fig. 4, and as can be seen from fig. 4, Zn, P, O and C are uniformly dispersed in the metal phosphide composite material;

FIG. 6 is an infrared spectrum of the metal phosphide composite material, and v is shown in FIG. 6₁(554cm^-1) Belongs to the bending vibration of O ═ P-O, v₂(637cm^-1) Belongs to O-P-O bending vibration, v₃(736cm^-1) Belongs to P-O-P symmetric stretching vibration, v₄(918cm^-1) Belongs to P-O-P asymmetric stretching vibration, v₅(1001cm^-1) Is (PO)₃)^2-Stretching vibration, v₆(1102cm^-1) Is (PO)₄)^3-Asymmetric stretching vibration, v₇(1192cm^-1) Is (PO)₂)^-The peak of vibration of (1). All these vibrational peaks, fully account for the presence of phosphate;

FIG. 7 is an XPS spectrum of the metal phosphide composite material, and as can be seen from FIG. 7, the existence of Zn-P bonds and P-O bonds can be observed in the XPS spectrum, which indicates the existence of phosphate;

fig. 9 is a thermogravimetric curve of the metal phosphide composite material in air, and it can be seen from fig. 9 that the mass fraction of conductive carbon in the metal phosphide composite material is 32.8%, which is very close to the actual addition of 30%.

Example 9

Mixing NiO with the average particle size of 100nm and red phosphorus with the average particle size of 20 microns according to the molar ratio of 1:4, and carrying out ball milling in an argon atmosphere, wherein the ball-material ratio of the ball milling is 20:1, the rotating speed is 800rpm, and the time is 4h, so as to obtain phosphate-doped metal phosphide (the molar ratio of the phosphate to the metal phosphide is 1: 5);

XRD test is carried out on the phosphate doped metal phosphide, the test result is shown in figure 11, and as can be seen from figure 11, the metal phosphide is successfully synthesized in the embodiment, and the metal phosphide is NiP₃But XRD does not show it due to the small grain size of the phosphate;

to verify the presence of phosphate, the phosphate-doped metal phosphide was subjected to an infrared test, as shown in fig. 10, which indicated the presence of a distinct phosphate absorption peak.

Test example

The metal phosphide composite material of example 2 was used as an active material, CMC (sodium carboxymethylcellulose) and SBR (styrene butadiene rubber) were used as binders, and acetylene black was used as a conductive agent; the mass ratio of the active material to the binder to the conductive agent is 7:1.5: 1.5; a copper foil is used as a current collector, potassium metal is used as a counter electrode, an electrolyte is KFSI (potassium trifluoromethanesulfonimide) (EC/DEC with the volume ratio of 1:1) with the concentration of 1.0mol/L, a half cell is assembled, and the half cell is subjected to a cycle stability test under the following test conditions: constant current charging and discharging with current density of 0.1 A.g^-1And voltage interval: 0.01-3.0V, and 600 cycles after the multiplying power test; the test results are shown in FIG. 14. from FIG. 14, it can be seen that the metal phosphide composite material of example 2 was 0.1A g^-1Initial under current density conditionsThe initial specific capacity is 274 mA.h.g^-1After the multiplying power test and 600 cycles, the specific capacity is 283 mA.h.g^-1The capacity retention rate is 100%, i.e., better cycle stability.

The metal phosphide composite material of example 8 was used as an active material, CMC (sodium carboxymethylcellulose) and SBR (styrene butadiene rubber) were used as binders, and acetylene black was used as a conductive agent; the mass ratio of the active material to the binder to the conductive agent is 7:1.5: 1.5; a copper foil is used as a current collector, potassium metal is used as a counter electrode, an electrolyte is KFSI (potassium trifluoromethanesulfonimide) (EC/DEC with the volume ratio of 1:1) with the concentration of 1.0mol/L, a half cell is assembled, and the half cell is subjected to a cycle stability test under the following test conditions: constant current charging and discharging with current density of 0.5 A.g^-1And voltage interval: 0.01-3.0V, and 500 cycles; as shown in FIG. 5, it can be seen from FIG. 5 that the initial specific capacity of the metal phosphide composite material described in example 8 was 350mA · h · g^-1After 500 cycles, the specific capacity is 300 mA.h.g^-1And the method has higher capacity retention rate, namely better cycling stability.

The metal phosphide composite material of example 9 was used as an active material, CMC (sodium carboxymethylcellulose) and SBR (styrene butadiene rubber) were used as binders, and acetylene black was used as a conductive agent; the mass ratio of the active material to the binder to the conductive agent is 7:1.5: 1.5; a copper foil is used as a current collector, potassium metal is used as a counter electrode, an electrolyte is KFSI (potassium trifluoromethanesulfonimide) (EC/DEC with the volume ratio of 1:1) with the concentration of 1.0mol/L, a half cell is assembled, and the half cell is subjected to a cycle stability test under the following test conditions: constant current charging and discharging with current density of 0.1 A.g^-1And voltage interval: 0.01-3.0V, and circulating for 350 times after the multiplying power test; as shown in FIG. 12, it can be seen from FIG. 12 that the current density of the metal phosphide composite material of example 9 was 0.1A · g^-1The initial specific capacity of (A) is 300mA · h · g^-1After circulating for 350 circles, the specific capacity is 265 mA.h.g^-1And the method has higher capacity retention rate, namely better cycling stability.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.