A phosphorus-based composite electrode material, a preparation method therefor, and an application thereof

Abstract

The application relates to the technical field of materials, and provides a phosphorus-based composite electrode material and a preparation method and application thereof. The phosphorus-based composite electrode material comprises tin phosphate and phosphorus, the mass ratio of the mass of the tin phosphate to the total mass of the phosphorus-based composite electrode material is 5-8:10, and the mass ratio of the mass of the phosphorus to the total mass of the phosphorus-based composite electrode material is 2:10-12. The phosphorus-based composite electrode material has the advantages of high capacity, high rate and high stability, can meet the requirements of devices on fast charging of lithium ion batteries, and can prolong the service life of the battery.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and in particular to a phosphorus-based composite electrode material, its preparation method, and its application. Background Technology

[0002] In existing technologies, graphite is generally used as the negative electrode material for lithium-ion batteries. However, graphite has a low specific capacity and slow kinetics, resulting in low energy density and poor fast-charging performance in lithium-ion batteries.

[0003] To improve the charging rate, energy density, and battery life of lithium-ion batteries, developing anode materials with high specific capacity, high rate capability, and high electrochemical stability is of great significance. Therefore, there is an urgent need to provide an anode material with high capacity, high rate capability, and high stability to meet the requirements of fast charging devices for lithium-ion batteries and extend battery life. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a phosphorus-based composite electrode material, its preparation method and application, and provide a phosphorus-based composite electrode material with high capacity, high rate capability and high stability, which can meet the requirements of devices for fast charging of lithium-ion batteries and can extend the service life of batteries.

[0005] A first aspect of the present invention provides a phosphorus-based composite electrode material, comprising:

[0006] Tin phosphate and phosphorus, wherein the mass ratio of tin phosphate to the total mass of the phosphorus-based composite electrode material is 5-8:10, and the mass ratio of phosphorus to the total mass of the phosphorus-based composite electrode material is 2:10-12.

[0007] The phosphorus-based composite electrode material provided in this invention uses tin phosphate as the main raw material. Tin phosphate has advantages such as a low voltage plateau (lithium insertion / deintercalation voltage plateau of approximately 0.8V), high specific capacity (800mAh / g), and good cycle stability. Adding phosphorus to tin phosphate results in a layered structure and good conductivity, along with an extremely high theoretical specific capacity (2596mAh / g). Lithium ions exhibit extremely high transport rates in phosphorus, making it suitable as a fast lithium-ion conductor. Adding phosphorus to tin phosphate and controlling the mass ratio of tin phosphate to phosphorus in the phosphorus-based composite electrode material can more effectively improve the theoretical capacity, rate performance, and cycle stability of the phosphorus-based composite electrode material. The phosphorus-based composite electrode material provided in this invention achieves an initial discharge capacity of 1100mAh / g and an initial coulombic efficiency of 70.1%. After 100 cycles at a current density of 5A / g, the capacity retention rate is 61%, significantly higher than that of pure tin phosphate electrode material, and it still exhibits rapid lithium storage characteristics at low temperatures. It is evident that phosphorus-based composite electrode materials prepared by using a specific ratio of tin phosphate and phosphorus have advantages such as high capacity, high rate capability, and high stability, which can meet the requirements of devices for fast charging of lithium-ion batteries and extend the battery's lifespan.

[0008] A second aspect of the present invention provides a method for preparing a phosphorus-based composite electrode material, comprising the following steps:

[0009] Prepare raw materials for phosphorus-based composite electrode materials, wherein the raw materials include at least tin phosphate and phosphorus;

[0010] The raw material is ball-milled to obtain the phosphorus-based composite electrode material.

[0011] The phosphorus-based composite electrode material prepared by the method provided in this embodiment of the invention has advantages such as high capacity, high rate capability, and high stability, which can meet the requirements of devices for fast charging and long life of lithium-ion batteries.

[0012] A third aspect of this invention provides an application of a phosphorus-based composite electrode material in batteries and supercapacitors. The phosphorus-based composite electrode material described in the first aspect was used in battery assembly and electrochemical performance testing, achieving stable long-term, high-rate charge-discharge cycling. Furthermore, the phosphorus-based composite electrode material provided by this invention retains its rapid lithium storage characteristics even at low temperatures. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention, 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, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is the X-ray diffraction pattern of the Sn2P2O7-P phosphorus-based composite electrode material prepared in Example 1 of this invention;

[0015] Figure 2 This is the first charge-discharge curve of the Sn2P2O7-P phosphorus-based composite electrode material prepared in Example 1 of this invention;

[0016] Figure 3 This is a cycle-capacity curve of the Sn2P2O7-P phosphorus-based composite electrode material prepared in Example 1 of this invention;

[0017] Figure 4 This is the X-ray diffraction pattern of the Sn2P2O7-P-Mo phosphorus-based composite electrode material prepared in Example 2 of this invention;

[0018] Figure 5 This is a scanning electron microscope image of the Sn2P2O7-P-Mo phosphorus-based composite electrode material prepared in Example 2 of this invention;

[0019] Figure 6 These are cycle-capacity curves of the Sn2P2O7-P-Mo phosphorus-based composite electrode materials prepared in Examples 2 and 3 of this invention;

[0020] Figure 7 The first charge-discharge curves are shown for the Sn2P2O7-P-Mo-C phosphorus-based composite materials prepared in Examples 4 and 5 of this invention and the pure Sn2P2O7 electrode material prepared in Comparative Example 1.

[0021] Figure 8 These are the cycle-capacity curves of the Sn2P2O7-P-Mo-C phosphorus-based composite electrode materials prepared in Examples 4 and 5 of this invention, and the pure Sn2P2O7 electrode material prepared in Comparative Example 1.

[0022] Figure 9 This is the capacity differential curve of the Sn2P2O7-P-Mo-C phosphorus-based composite electrode material prepared in Example 5 of this invention, corresponding to the first cycle.

[0023] Figure 10 This is a charge-discharge curve of the Sn2P2O7-P-Mo-C phosphorus-based composite electrode material prepared in Example 5 of the present invention under different current densities;

[0024] Figure 11 This is a coulombic efficiency curve of the Sn2P2O7-P-Mo-C composite material prepared in Example 5 of this invention;

[0025] Figure 12 This is a charge-discharge curve of the full battery prepared in Example 6 of the present invention at different temperatures;

[0026] Figure 13 This is a cycle-capacity curve of the LiCoO2||Sn2P2O7-P-Mo-C full cell prepared in Example 6 at different temperatures;

[0027] Figure 14 This is a comparison chart of the cycle-capacity curves of the Sn2P2O7-P-Mo-C composite electrode materials prepared in Example 5 of the present invention, the SnO2-P-Mo-C prepared in Comparative Example 2, and the Sn2P2O7-P-Co-C prepared in Comparative Example 3. Detailed Implementation

[0028] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but the implementation of the present invention is not limited thereto.

[0029] In a first aspect, this embodiment provides a phosphorus-based composite electrode material, comprising: tin phosphate and phosphorus, wherein the mass ratio of the tin phosphate to the total mass of the phosphorus-based composite electrode material is 5-8:10, and the mass ratio of the phosphorus to the total mass of the phosphorus-based composite electrode material is 2:10-12.

[0030] The phosphorus-based composite electrode material provided in this invention uses tin phosphate as the main raw material. Tin phosphate has advantages such as a low voltage plateau (lithium insertion / deintercalation voltage plateau of approximately 0.8V), high specific capacity (800mAh / g), and good cycle stability. Adding phosphorus to tin phosphate results in a layered structure and good conductivity, along with an extremely high theoretical specific capacity (2596mAh / g). Lithium ions exhibit extremely high transport rates in phosphorus, making it suitable as a fast lithium-ion conductor. Adding phosphorus to tin phosphate and controlling the mass ratio of tin phosphate to phosphorus in the phosphorus-based composite electrode material can more effectively improve the theoretical capacity, rate performance, and cycle stability of the phosphorus-based composite electrode material. The phosphorus-based composite electrode material provided in this invention achieves an initial discharge capacity of 1100mAh / g and an initial coulombic efficiency of 70.1%. After 100 cycles at a current density of 5A / g, the capacity retention rate is 61%, significantly higher than that of pure tin phosphate electrode material, and it still exhibits rapid lithium storage characteristics at low temperatures. It is evident that phosphorus-based composite electrode materials prepared by using a specific ratio of tin phosphate and phosphorus have advantages such as high capacity, high rate capability, and high stability, which can meet the requirements of devices for fast charging of lithium-ion batteries and extend the battery's lifespan.

[0031] Furthermore, the phosphorus-based composite electrode material further includes molybdenum; and / or, the phosphorus-based composite electrode material further includes carbon materials. In this embodiment, by adding molybdenum and / or carbon, the cycle stability and rate performance (charge / discharge rate) of the phosphorus-based composite electrode material can be further improved.

[0032] Furthermore, the phosphorus-based composite electrode material also includes molybdenum. Specifically, the mass ratio of molybdenum to the total mass of the phosphorus-based composite electrode material can be 2:10 to 12. For example, the mass ratio of molybdenum to the total mass of the phosphorus-based composite electrode material is 2:10, 2:11, 2:12, etc. In this embodiment, by adding a specific proportion of molybdenum to the phosphorus-based composite electrode material, the cycle stability and rate performance (charge / discharge rate) of the phosphorus-based composite electrode material can be improved.

[0033] Furthermore, the phosphorus-based composite electrode material also includes carbon material, and the mass ratio of the carbon material to the total mass of the phosphorus-based composite electrode material is 1-2:11-12. For example, the mass ratio of the carbon material to the total mass of the phosphorus-based composite electrode material is 1:11, 1:12, 2:11, 2:12, etc. In this embodiment, by adding a specific proportion of carbon material to the phosphorus-based composite electrode material, the cycle stability and rate performance (charge / discharge rate) of the phosphorus-based composite electrode material can be further improved. Preferably, the carbon material is natural graphite powder.

[0034] Furthermore, when the phosphorus-based composite electrode material comprises tin phosphate, phosphorus, molybdenum, and carbon, the mass ratio of tin phosphate to the total mass of the phosphorus-based composite electrode material is 6:11-12, the mass ratio of phosphorus to the total mass of the phosphorus-based composite electrode material is 2:11-12, the mass ratio of molybdenum to the total mass of the phosphorus-based composite electrode material is 2:11-12, and the mass ratio of carbon to the total mass of the phosphorus-based composite electrode material is 1-2:11-12. When the phosphorus-based composite electrode material is composed of tin phosphate, phosphorus, molybdenum, and carbon, its cycle performance and rate performance are effectively improved.

[0035] Furthermore, when the phosphorus-based composite electrode material comprises four substances—tin phosphate, phosphorus, molybdenum, and carbon—in a mass ratio of 3:1:1:1, tests show that the initial discharge capacity of this phosphorus-based composite electrode material reaches 1120 mAh / g, with an initial coulombic efficiency of 80.2%, and a capacity retention rate of 100% after 100 cycles at a current density of 5 A / g. Moreover, it retains its rapid lithium storage characteristics even at low temperatures.

[0036] Furthermore, the tin phosphate has a particle size distribution range of 1 μm to 3 μm, the molybdenum has a particle size distribution range of 1 μm to 3 μm, and the carbon material has a particle size distribution range of 10 μm to 30 μm. Specifically, the tin phosphate used has a particle size distribution range of 1 μm to 3 μm and a purity of 96%, the phosphorus powder used has a purity of 98.5%, the molybdenum powder used has a particle size distribution range of 1 μm to 3 μm and a purity of 99.9%, and the carbon material used is natural graphite powder with a particle size distribution of 10 μm to 30 μm and a purity of 99.9%.

[0037] Secondly, embodiments of the present invention also provide a method for preparing a phosphorus-based composite electrode material, comprising the following steps:

[0038] Step S10: Prepare the raw materials for the phosphorus-based composite electrode material, wherein the raw materials include at least tin phosphate and phosphorus;

[0039] Step S20: The raw material is ball-milled to obtain the phosphorus-based composite electrode material.

[0040] The phosphorus-based composite electrode material prepared by the method provided in this embodiment of the invention has advantages such as high capacity, high rate capability, and high stability, which can meet the requirements of devices for fast charging and long life of lithium-ion batteries.

[0041] Furthermore, in step S20 above, the ball milling method is high-energy oscillating ball milling, the grinding balls are made of bearing steel, the entire ball milling process is carried out under an argon atmosphere, the ball-to-material ratio is 25:1 to 50:1, the ball milling speed is 1000 rpm to 1200 rpm, and the ball milling time is 5 h to 10 h. When using the high-energy oscillating ball milling method, a one-step ball milling method is adopted, that is, the raw materials are stirred and mixed before ball milling. The phosphorus-based composite electrode material prepared by the high-energy oscillating ball milling method has a simple process, high repeatability, and is suitable for large-scale production, showing broad application prospects.

[0042] Thirdly, embodiments of the present invention also provide an application of a phosphorus-based composite electrode material in batteries and supercapacitors. The phosphorus-based composite electrode material described in the first aspect was used for battery assembly and electrochemical performance testing, achieving stable long-term, high-rate charge-discharge cycling. Furthermore, the phosphorus-based composite electrode material provided by the embodiments of the present invention still exhibits rapid lithium storage characteristics at low temperatures.

[0043] Specifically, in battery applications, the phosphorus-based composite electrode material described in the first aspect can be used as a negative electrode material in battery fabrication.

[0044] In one possible implementation, the negative electrode uses the phosphorus-based composite electrode material described in the first aspect, with lithium metal (purity 99.99%) as the counter electrode, and the electrolyte is a 1 mol / L ethylene carbonate (EC) / dimethyl carbonate (DMC) solution (volume ratio 2:1), assembled into a coin cell.

[0045] In another possible implementation, the negative electrode uses the phosphorus-based composite electrode material described in the first aspect, and the positive electrode uses lithium cobalt oxide, and the CR2016 type button cell is assembled in a glove box under a high-purity argon atmosphere.

[0046] This invention has undergone numerous experiments, and some of the experimental results are presented here for reference to further describe the invention in detail. The following is a detailed description in conjunction with specific embodiments.

[0047] Example 1

[0048] Preparation of Sn2P2O7-P (Stin Phosphate-Phosphate) Phosphate-Based Composite Electrode Material:

[0049] Step S10: Prepare tin phosphate with a particle size range of 1μm to 3μm and a purity of 99.9%, and phosphorus powder with a purity of 98.5%, wherein the mass ratio of tin phosphate to phosphorus is 8:2.

[0050] Step S20: After mixing tin phosphate and phosphorus powder, ball milling is performed using a vibratory ball milling method. The grinding balls are made of bearing steel, and the mass ratio of grinding balls to mixed powder is 25:1. The specific steps of the vibratory ball milling method are as follows:

[0051] (1) Load grinding balls and stirred tin phosphate and phosphorus powder into a ball mill jar;

[0052] (2) Evacuate the ball mill jar by using the swing vacuum valve, and then fill it with argon gas to make the pressure inside the ball mill jar reach 0.12 MPa;

[0053] (3) Turn on the ball mill power supply, set the ball mill speed to 1200 rpm, the unidirectional interval running time to 30 min, the timer to 30 min, and the number of restarts to 9. Fix the ball mill jar on the high-energy oscillating ball mill frame and perform high-energy oscillating ball milling for 5 h to obtain Sn2P2O7-P phosphorus-based composite electrode material.

[0054] Figure 1 The X-ray diffraction pattern of the Sn2P2O7-P phosphorus-based composite electrode material prepared in Example 1 of the present invention is shown.

[0055] The Sn2P2O7-P phosphorus-based composite electrode material prepared in this embodiment was used as the working electrode and the following performance tests were performed:

[0056] The prepared Sn2P2O7-P phosphorus-based composite electrode material powder, conductive agent Super-P, and binder CMC (carboxymethyl cellulose) were mixed evenly at a mass ratio of 8:1:1. Using water as a solvent, the mixture was stirred for 15 minutes using a stirrer to prepare a slurry. This slurry was then coated onto copper foil to form an electrode sheet, which was vacuum dried at 80℃ for 12 hours. In an argon-atmosphere glove box, using lithium metal (99.99% purity) as the counter electrode and a 1 mol / L ethylene carbonate (EC) / dimethyl carbonate (DMC) solution (volume ratio 2:1) as the electrolyte, coin cells were assembled for testing. The test conditions were: test temperature 30℃, charge / discharge current density of 0.1 A / g and 5 A / g, and charge / discharge cutoff voltage of 0.01V-3.0V and 0.01V-2.0V (vs. Li / Li). + ).

[0057] Figure 2 The first charge-discharge curve of the Sn2P2O7-P phosphorus-based composite electrode material prepared in Example 1 of this invention is shown. Figure 2 It can be seen that the initial discharge capacity of the Sn2P2O7-P phosphorus-based composite electrode material prepared in this embodiment is 1100 mAh / g, and the initial coulombic efficiency is 70.1%.

[0058] Figure 3The cycle-capacity curve of the Sn2P2O7-P phosphorus-based composite electrode material prepared in Example 1 of this invention is shown. Figure 3 It can be seen that the Sn2P2O7-P phosphorus-based composite electrode material prepared in this embodiment retains 61% of its capacity after 100 cycles at 5 A / g.

[0059] Example 2

[0060] Preparation of Sn2P2O7-P-Mo (Stin Phosphate-Phosphorus-Molybdenum) Phosphate-Based Composite Electrode Material:

[0061] Step S10: Prepare tin phosphate with a particle size range of 1μm to 3μm and a purity of 99.9%, phosphorus powder with a purity of 98.5%, and molybdenum powder with a particle size range of 1μm to 3μm and a purity of 99.9%, wherein the mass ratio of tin phosphate, phosphorus and molybdenum is 5:3:2.

[0062] Step S20: After mixing the tin phosphate, phosphorus, and molybdenum powders, ball milling is performed using a vibratory ball milling method. The grinding balls are made of bearing steel, and the mass ratio of the grinding balls to the mixed powder is 50:1. The specific steps of the vibratory ball milling method are as follows:

[0063] (1) Load grinding balls and mixed tin phosphate, phosphorus and molybdenum powder into a ball mill jar;

[0064] (2) Evacuate the ball mill jar by using the swing vacuum valve, and then fill it with argon gas to make the pressure inside the ball mill jar reach 0.12 MPa;

[0065] (3) Turn on the ball mill power supply, set the ball mill speed to 1200 rpm, the unidirectional interval running time to 30 min, the timer to 30 min, and the number of restarts to 19. Fix the ball mill jar on the high-energy oscillating ball mill frame and perform high-energy oscillating ball milling for 10 h to obtain Sn2P2O7-P-Mo(5:3:2) phosphorus-based composite electrode material.

[0066] Figure 4 The X-ray diffraction pattern of the Sn2P2O7-P-Mo phosphorus-based composite electrode material prepared in Example 2 of the present invention is shown.

[0067] Figure 5 A scanning electron microscope image of the Sn2P2O7-P-Mo phosphorus-based composite electrode material prepared in Example 2 of the present invention is shown.

[0068] The Sn2P2O7-P-Mo phosphorus-based composite electrode material prepared in Example 2 was used as the working electrode and the following performance tests were performed:

[0069] The prepared Sn2P2O7-P-Mo phosphorus-based composite electrode material powder, conductive agent Super-P, and binder CMC were mixed evenly at a mass ratio of 8:1:1. Using water as a solvent, the mixture was stirred for 15 minutes using a stirrer to prepare a slurry. This slurry was coated onto copper foil to form an electrode sheet, which was then vacuum dried at 80℃ for 12 hours. In an argon-atmosphere glove box, using lithium metal (99.99% purity) as the counter electrode and a 1 mol / L ethylene carbonate (EC) / dimethyl carbonate (DMC) solution (volume ratio 2:1) as the electrolyte, a coin cell was assembled for testing. The test conditions were: test temperature 30℃, charge / discharge current density 5 A / g, and charge / discharge cutoff voltage 0.01V-2.0V (vs. Li / Li). + ).

[0070] Example 3

[0071] Preparation of Sn2P2O7-P-Mo (Stin Phosphate-Phosphorus-Molybdenum) Phosphate-Based Composite Electrode Material:

[0072] The Sn2P2O7-P-Mo phosphorus-based composite electrode material in this embodiment is basically the same as the phosphorus-based composite electrode material in Example 2 above, except that the mass ratio of tin phosphate, phosphorus and molybdenum is 6:2:2.

[0073] The Sn2P2O7-P-Mo(6:2:2) phosphorus-based composite electrode material prepared in this embodiment was used as the working electrode and the following performance tests were performed:

[0074] The prepared Sn2P2O7-P-Mo phosphorus-based composite electrode material powder, conductive agent Super-P, and binder CMC were mixed evenly at a mass ratio of 8:1:1. Using water as a solvent, the mixture was stirred for 15 minutes using a stirrer to prepare a slurry. This slurry was coated onto copper foil to form an electrode sheet, which was then vacuum dried at 80℃ for 12 hours. In an argon-atmosphere glove box, using lithium metal as the counter electrode and a 1 mol / L ethylene carbonate (EC) / dimethyl carbonate (DMC) solution (volume ratio 2:1) as the electrolyte, a coin cell was assembled for testing. The test conditions were: test temperature 30℃, charge / discharge current density 5 A / g, and charge / discharge cutoff voltage 0.01V-2.0V.

[0075] Figure 6 Cycle-capacity curves of the Sn2P2O7-P-Mo phosphorus-based composite electrode materials prepared in Examples 2 and 3 of this invention are shown. Figure 6It can be seen that the Sn2P2O7-P-Mo phosphorus-based composite electrode material prepared in Example 2 achieved an initial charge capacity of 535 mAh / g at 5 A / g and a capacity retention of 69.5% after 100 cycles. The Sn2P2O7-P-Mo phosphorus-based composite electrode material obtained in Example 2 has better cycle performance than the Sn2P2O7-P phosphorus-based composite electrode material obtained in Example 1. The Sn2P2O7-P-Mo (6:2:2) phosphorus-based composite electrode material prepared in Example 3 achieved an initial charge capacity of 609 mAh / g at 5 A / g and a capacity retention of 81.2% after 100 cycles. The Sn2P2O7-P-Mo (6:2:2) phosphorus-based composite electrode material obtained in Example 3 has better cycle performance than the Sn2P2O7-P-Mo (5:3:2) composite electrode material obtained in Example 2.

[0076] Example 4

[0077] Preparation of Sn2P2O7-P-Mo-C (Stin phosphate-phosphorus-molybdenum-carbon) phosphorus-based composite electrode material:

[0078] Step S10: Prepare tin phosphate with a particle size range of 1μm to 3μm and a purity of 99.9%; phosphorus powder with a purity of 98.5%; molybdenum powder with a particle size range of 1μm to 3μm and a purity of 99.9%; and natural graphite powder with a particle size distribution of 10μm to 30μm and a purity of 99.9%. The mass ratio of tin phosphate, phosphorus, molybdenum, and carbon is 6:2:2:1.

[0079] Step S20: After mixing tin phosphate, phosphorus, molybdenum, and carbon powder, the mixture is ball-milled using a vibrating ball mill. The grinding balls are made of bearing steel, and the mass ratio of the grinding balls to the mixed powder is 50:1. The specific steps of the vibrating ball milling method are as follows:

[0080] (1) Load grinding balls and a mixture of tin phosphate, phosphorus, molybdenum and carbon powder into a ball mill jar;

[0081] (2) Evacuate the ball mill jar by using the swing vacuum valve, and then fill it with argon gas to make the pressure inside the ball mill jar reach 0.12 MPa;

[0082] (3) Turn on the ball mill power supply, set the ball mill speed to 1200 rpm, the unidirectional interval running time to 30 min, the timer to 30 min, and the number of restarts to 19. Fix the ball mill jar on the high-energy oscillating ball mill frame and perform high-energy oscillating ball milling for 10 h to obtain Sn2P2O7-P-Mo-C(6:2:2:1) phosphorus-based composite electrode material.

[0083] The Sn2P2O7-P-Mo-C phosphorus-based composite powder material obtained in this embodiment was used as a working electrode for the following performance tests:

[0084] The prepared Sn2P2O7-P-Mo-C phosphorus-based composite electrode material powder, conductive agent Super-P, and binder CMC were mixed evenly at a mass ratio of 8:1:1. The mixture was then stirred for 15 minutes using a stirrer with water as the solvent to prepare a slurry. This slurry was coated onto copper foil to form an electrode sheet, which was then vacuum dried at 80℃ for 12 hours. In an argon-atmosphere glove box, using lithium metal (99.99% purity) as the counter electrode and a 1 mol / L ethylene carbonate (EC) / dimethyl carbonate (DMC) solution (volume ratio 2:1) as the electrolyte, coin cells were assembled for testing. The test conditions were: test temperature 30℃, charge / discharge current density of 0.1 A / g and 5 A / g, and charge / discharge cutoff voltage of 0.01V-3.0V and 0.01V-2.0V (vs. Li / Li). + ).

[0085] Example 5

[0086] Preparation of Sn2P2O7-P-Mo-C (Stin phosphate-phosphorus-molybdenum-carbon) phosphorus-based composite electrode material:

[0087] The Sn2P2O7-P-Mo-C phosphorus-based composite electrode material in this embodiment is basically the same as the phosphorus-based composite electrode material in Example 4 above, except that the mass ratio of tin phosphate, phosphorus, molybdenum and carbon is 6:2:2:2.

[0088] The Sn2P2O7-P-Mo-C(6:2:2:2) phosphorus-based composite powder material obtained in this embodiment was used as the working electrode and the following performance tests were performed:

[0089] The prepared Sn2P2O7-P-Mo-C phosphorus-based composite electrode material powder, conductive agent Super-P, and binder CMC were mixed evenly at a mass ratio of 8:1:1. The mixture was then stirred for 15 minutes using a stirrer with water as the solvent to form a slurry. This slurry was coated onto copper foil to form an electrode sheet, which was then vacuum dried at 80℃ for 12 hours. In an argon-atmosphere glove box, using lithium metal (99.99% purity) as the counter electrode and a 1 mol / L ethylene carbonate (EC) / dimethyl carbonate (DMC) solution (volume ratio 2:1) as the electrolyte, coin cells were assembled for testing. The test conditions were: test temperature 30℃, charge / discharge current densities of 0.1 A / g, 1 A / g, and 5 A / g, and charge / discharge cutoff voltages of 0.01V-3.0V and 0.01V-2.0V (vs. Li / Li). + ).

[0090] Figure 7The first charge-discharge curves of the Sn₂P₂O₇-P-Mo-C phosphorus-based composite materials prepared in Examples 4 and 5 of this invention, and the pure Sn₂P₂O₇ electrode material prepared in Comparative Example 1, are shown. Figure 7 As can be seen, the Sn2P2O7-P-Mo-C (6:2:2:1) phosphorus-based composite electrode material prepared in Example 4 achieved an initial discharge capacity of 1133 mAh / g and a high initial coulombic efficiency of 80.1%. The Sn2P2O7-P-Mo-C (6:2:2:2) phosphorus-based composite electrode material prepared in Example 5 achieved an initial discharge capacity of approximately 1120 mAh / g and a high initial coulombic efficiency of 80.2%.

[0091] Figure 8 Cycle-capacity curves are shown for the Sn₂P₂O₇-P-Mo-C phosphorus-based composite electrode materials prepared in Examples 4 and 5 of this invention, and for the pure Sn₂P₂O₇ electrode material prepared in Comparative Example 1. Figure 8 It can be seen that the Sn2P2O7-P-Mo-C (6:2:2:1) phosphorus-based composite electrode material prepared in Example 4 exhibited good cycling stability, with a capacity retention of 96.1% after 100 cycles at 5 A / g. The Sn2P2O7-P-Mo-C (6:2:2:1) phosphorus-based composite material prepared in Example 4 also exhibited high initial coulombic efficiency and high capacity retention. The Sn2P2O7-P-Mo (6:2:2:2) phosphorus-based composite electrode material prepared in Example 5 exhibited good cycling stability, with a capacity retention of up to 100% after 100 cycles at 5 A / g.

[0092] Figure 9 The diagram shows the capacity differential curve corresponding to the first cycle of the Sn2P2O7-P-Mo-C phosphorus-based composite electrode material prepared in Example 5 of this invention. Figure 9 It can be seen that the Sn2P2O7-P-Mo-C(6:2:2:2) phosphorus-based composite electrode material prepared in Example 5 of the present invention has obvious lithium insertion / delithiation characteristic peaks of tin phosphate and phosphorus.

[0093] Figure 10 The charge-discharge curves of the Sn2P2O7-P-Mo-C phosphorus-based composite electrode material prepared in Example 5 of this invention are shown at different current densities. Figure 10 It can be seen that the Sn2P2O7-P-Mo-C(6:2:2:2) phosphorus-based composite electrode material exhibits obvious lithium insertion / delithiation platforms of tin phosphate and phosphorus at different current densities.

[0094] Figure 11 The coulombic efficiency curve of the Sn2P2O7-P-Mo-C composite material prepared in Example 5 of this invention is shown. Figure 11It can be seen that the Sn2P2O7-P-Mo-C (6:2:2:2) composite electrode material exhibits an ultra-high average coulombic efficiency of 99.9% within 100 cycles. Compared to the Sn2P2O7-P-Mo-C (6:2:2:1) composite electrode material obtained in Example 4, the Sn2P2O7-P-Mo-C (6:2:2:1) composite electrode material prepared in Example 5 demonstrates higher initial coulombic efficiency and greater cycling stability at high current densities.

[0095] Example 6

[0096] Preparation of LiCoO2||Sn2P2O7-P-Mo-C full cells:

[0097] The Sn2P2O7-P-Mo-C(6:2:2:2) phosphorus-based composite electrode material obtained in Example 5 above was subjected to full-cell electrochemical performance testing. The specific steps for the full-cell electrochemical performance testing are as follows:

[0098] The negative electrode sheet uses the Sn2P2O7-P-Mo-C (6:2:2:2) phosphorus-based composite electrode material obtained in Example 5 above, and the positive electrode sheet uses commercially available LiCoO2. The main preparation steps of the positive electrode sheet are as follows: Commercially available positive electrode powder, conductive agent Super-P, and binder PVDF (polyvinylidene fluoride) are mixed in a mass ratio of 8:1:1, and stirred for 15 minutes using a stirrer with NMP (N-methylpyrrolidone) as solvent to form a slurry. The obtained positive electrode slurry is coated using an automatic coating machine, with aluminum foil as the current collector. The coated electrode sheet is then dried in a vacuum drying oven at 100°C for 12 hours for later use. The prepared electrode sheet is cut into circular pieces of different diameters using a slicing machine to achieve different positive and negative electrode capacity ratios. The Sn2P2O7-P-Mo-C (6:2:2:2) composite electrode material prepared in this example is used as the negative electrode material and the LiCoO2 positive electrode material. In an argon-atmosphere glove box, a LiCoO₂||Sn₂P₂O₇-P-Mo-C full cell was assembled using a 1 mol / L ethylene carbonate (EC) / dimethyl carbonate (DMC) solution (volume ratio 2:1) as the electrolyte for testing. The test conditions were: test temperatures of 30℃ and -10℃, charge / discharge current densities of 0.1 A / g and 5 A / g, and charge / discharge cutoff voltages of 1.95 V–4.3 V (vs. Li / Li + ).

[0099] Figure 12 The diagram shows the charge-discharge curves of the full battery prepared in Example 6 of this invention at different temperatures. Figure 12It can be seen that, at a current density of 0.1 A / g, compared with the Sn2P2O7-P-Mo-C (6:2:2:2) electrode material obtained in Example 5, the LiCoO2||Sn2P2O7-P-Mo-C full cell obtained in Example 6 exhibited a completely equivalent reversible specific capacity in the range of 1.95 V-4.3 V, which was comparable to the capacity of the Sn2P2O7-P-Mo-C (6:2:2:2) electrode material obtained in Example 5 in the range of 0.01-2.0 V.

[0100] Figure 13 The cycle-capacity curves of the LiCoO2||Sn2P2O7-P-Mo-C full cell prepared in Example 6 are shown at different temperatures. At a high rate current density of 5 A / g, the capacity retention after 50 cycles is 86.4% at a test temperature of 30°C, and 76.2% at a test temperature of -10°C, demonstrating excellent cycle stability. It is evident that the LiCoO2||Sn2P2O7-P-Mo-C full cell provided in this example still exhibits rapid lithium storage characteristics at low temperatures.

[0101] Comparative Example 1

[0102] The preparation steps of the pure Sn2P2O7 (tin phosphate) electrode material prepared in Comparative Example 1 are as follows:

[0103] Step S10: Prepare tin phosphate with a particle size range of 1μm to 3μm and a purity of 99.9%.

[0104] Step S20: The tin phosphate is ball-milled using a vibratory ball milling method. The grinding balls are made of bearing steel, and the mass ratio of the grinding balls to the mixed powder is 50:1. The specific steps of the vibratory ball milling method are as follows:

[0105] (1) Load grinding balls and tin phosphate powder into a ball mill jar;

[0106] (2) Evacuate the ball mill jar by using the swing vacuum valve, and then fill it with argon gas to make the pressure inside the ball mill jar reach 0.12 MPa;

[0107] (3) Turn on the ball mill power supply, set the ball mill speed to 1200 rpm, the unidirectional interval running time to 30 min, the timer to 30 min, and the number of restarts to 19. Fix the ball mill jar on the high-energy oscillating ball mill frame and perform high-energy oscillating ball milling for 10 h to obtain Sn2P2O7 electrode material.

[0108] The Sn2P2O7 electrode material prepared in Comparative Example 1 was used as the working electrode and the following performance tests were conducted:

[0109] The prepared Sn2P2O7 electrode material powder, conductive agent Super-P, and binder CMC were mixed evenly at a mass ratio of 8:1:1. The mixture was then stirred for 15 minutes using a stirrer with water as the solvent to form a slurry. This slurry was coated onto copper foil to form an electrode sheet, which was then vacuum-dried at 80℃ for 12 hours. In an argon-atmosphere glove box, using lithium metal (99.99% purity) as the counter electrode and a 1 mol / L ethylene carbonate (EC) / dimethyl carbonate (DMC) solution (volume ratio 2:1) as the electrolyte, coin cells were assembled for testing. The test conditions were: test temperature 30℃, charge / discharge current density of 0.1 A / g and 5 A / g, and charge / discharge cutoff voltage of 0.01V-3.0V and 0.01V-2.0V (vs. Li / Li). + ).

[0110] Please see Figure 7 ,Depend on Figure 7 As can be seen, the Sn₂P₂O₇ electrode material prepared in Comparative Example 1 achieved an initial discharge capacity of 850 mAh / g and an initial coulombic efficiency of 63.5%. In contrast, the Sn₂P₂O₇-P-Mo-C (6:2:2:2) phosphorus-based composite electrode material prepared in Example 5 achieved an initial discharge capacity of 1120 mAh / g and a high initial coulombic efficiency of 80.2%. Therefore, the initial discharge capacity and initial coulombic efficiency of the Sn₂P₂O₇-P-Mo-C (6:2:2:2) phosphorus-based composite electrode material prepared in Example 5 are significantly higher than those of the Sn₂P₂O₇ electrode material prepared in Comparative Example 1. Please refer to [link / reference]. Figure 8 ,Depend on Figure 8 As can be seen, the cycling stability of the Sn2P2O7-P-Mo-C(6:2:2:2) phosphorus-based composite electrode material prepared in Example 5 is much higher than that of the pure Sn2P2O7 electrode material prepared in Comparative Example 1.

[0111] A comparison of Example 5 and Comparative Example 1 shows that adding phosphorus to tin phosphate can increase the capacity and rate performance of the phosphorus-based composite material, while adding molybdenum and carbon materials can increase the cycle stability of the phosphorus-based composite material. The Sn2P2O7-P-Mo-C phosphorus-based composite electrode material prepared in Example 5 of this invention has advantages such as high initial efficiency, high rate capability, and high cycle stability.

[0112] Comparative Example 2

[0113] Preparation of SnO2-P-Mo-C (tin dioxide-phosphorus-molybdenum-carbon) composite electrode materials:

[0114] The preparation method of the SnO2-P-Mo-C composite electrode material in Comparative Example 2 is basically the same as that of the Sn2P2O7-P-Mo-C (6:2:2:2) phosphorus-based composite electrode material in Example 5 above. The difference is that Sn2P2O7 powder is replaced with SnO2 powder, wherein the mass ratio of tin dioxide, phosphorus, molybdenum and carbon is 6:2:2:2.

[0115] Comparative Example 3

[0116] Preparation of Sn2P2O7-P-Co-C (Stin phosphate-phosphorus-cobalt-carbon) composite electrode material:

[0117] The preparation method of the Sn2P2O7-P-Co-C composite electrode material of Comparative Example 3 is basically the same as that of the Sn2P2O7-P-Mo-C (6:2:2:2) phosphorus-based composite electrode material of Example 5 above. The difference is that the Mo powder is replaced with Co powder, and the mass ratio of tin dioxide, phosphorus, cobalt and carbon is 6:2:2:2.

[0118] Figure 14 The diagram shows a comparison of the cycle-capacity curves of the Sn₂P₂O₇-P-Mo-C composite electrode materials prepared in Example 5 of the present invention, as well as the SnO₂-P-Mo-C prepared in Comparative Example 2 and the Sn₂P₂O₇-P-Co-C prepared in Comparative Example 3. Figure 14 It can be seen that Sn2P2O7-P-Mo-C exhibits higher capacity and cycling stability at 5 A / g than SnO2-P-Mo-C in Comparative Example 2 and Sn2P2O7-P-Co-C in Comparative Example 3. Therefore, the phosphorus-based composite material prepared from tin phosphate, phosphorus, molybdenum, and carbon materials in Example 5 of this invention demonstrates superior capacity and cycling stability compared to the composite electrode material prepared from tin dioxide, phosphorus, molybdenum, and carbon materials in Comparative Example 2, or the composite electrode material prepared from tin phosphate, phosphorus, cobalt, and carbon materials in Comparative Example 3.

[0119] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A phosphorus-based composite electrode material, characterized in that, include: The material contains stannous pyrophosphate and phosphorus, wherein the mass ratio of stannous pyrophosphate to the total mass of the phosphorus-based composite electrode material is 5-8:10, and the mass ratio of phosphorus to the total mass of the phosphorus-based composite electrode material is 2:10-12.

2. The phosphorus-based composite electrode material according to claim 1, characterized in that, The phosphorus-based composite electrode material also includes molybdenum; And / or, the phosphorus-based composite electrode material further includes carbon materials.

3. The phosphorus-based composite electrode material according to claim 2, characterized in that, When the phosphorus-based composite electrode material further includes molybdenum, the mass ratio of the molybdenum to the total mass of the phosphorus-based composite electrode material is 2:10~12.

4. The phosphorus-based composite electrode material according to claim 2, characterized in that, When the phosphorus-based composite electrode material further includes carbon material, the mass ratio of the carbon material to the total mass of the phosphorus-based composite electrode material is 1~2:11~12.

5. The phosphorus-based composite electrode material according to claim 2, characterized in that, When the phosphorus-based composite electrode material includes stannous pyrophosphate, phosphorus, molybdenum, and carbon, the mass ratio of the stannous pyrophosphate to the total mass of the phosphorus-based composite electrode material is 6:11~12, the mass ratio of the phosphorus to the total mass of the phosphorus-based composite electrode material is 2:11~12, the mass ratio of the molybdenum to the total mass of the phosphorus-based composite electrode material is 2:11~12, and the mass ratio of the carbon to the total mass of the phosphorus-based composite electrode material is 1~2:11~12.

6. The phosphorus-based composite electrode material according to claim 5, characterized in that, When the phosphorus-based composite electrode material includes stannous pyrophosphate, phosphorus, molybdenum and carbon materials, the mass ratio of stannous pyrophosphate, phosphorus, molybdenum and carbon materials is 3:1:1:

1.

7. The phosphorus-based composite electrode material according to any one of claims 2, characterized in that, The particle size distribution range of the stannous pyrophosphate is 1μm to 3μm, the particle size distribution of the molybdenum is 1μm to 3μm, and the particle size distribution range of the carbon material is 10μm to 30μm.

8. The method for preparing the phosphorus-based composite electrode material according to any one of claims 1 to 7, characterized in that, The steps include the following: Prepare raw materials for phosphorus-based composite electrode materials, wherein the raw materials include at least stannous pyrophosphate and phosphorus; The raw material is ball-milled to obtain the phosphorus-based composite electrode material.

9. The method for preparing the phosphorus-based composite electrode material according to claim 8, characterized in that, In the step of ball milling the raw material to obtain the phosphorus-based composite electrode material The ball milling method is high-energy oscillating ball milling, the grinding balls are made of bearing steel, the ball milling process is carried out in an argon atmosphere, the ball-to-material ratio is 25:1~50:1, the ball milling speed is 1000rpm~1200rpm, and the ball milling time is 5h~10h.

10. The application of the phosphorus-based composite electrode material according to any one of claims 1 to 7 in batteries and supercapacitors.

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