Preparation method of tin dioxide negative electrode material

Abstract

The application relates to a preparation method of a tin dioxide negative material, and belongs to the technical field of lithium battery negative material synthesis. The application aims at solving the problems of the existing SnO2 negative material, such as large volume effect in the charging and discharging process, easy falling off on the current collector, complex preparation process of the SnO2 negative material and high cost. The preparation method comprises the following steps: S1, preparing a micro-arc oxidation electrolyte; S2, placing a titanium foil and the micro-arc oxidation electrolyte in a micro-arc oxidation electrolytic tank, taking the titanium foil as a positive electrode and a stainless steel plate as a negative electrode; and S3, micro-arc oxidation. The application is used for the preparation of the tin dioxide negative material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of synthesis of lithium battery negative electrode materials. BACKGROUND

[0002] SnO2 has high theoretical specific capacity, relatively low charge-discharge platform, low cost, environmental friendliness, high safety performance and other advantages, and replacing graphite negative electrode material with SnO2 negative electrode material is the most ideal. However, due to the volume change of SnO2 material up to 300% in the charge-discharge process, the electrode will be damaged in the battery charge-discharge process, which causes the specific capacity to decrease sharply and cannot meet people's daily needs. Moreover, the traditional preparation process of SnO2 negative electrode material is complex, the process is tedious, and the SnO2 negative electrode material is easy to fall off from the current collector, which causes the electrochemical performance of the lithium battery to be improved slowly. SUMMARY

[0003] The application aims to solve the problems of the existing SnO2 negative electrode material, such as large volume effect in the charge-discharge process, easy falling off from the current collector, complex preparation process of SnO2 negative electrode material and high cost, and further provides a preparation method of tin dioxide negative electrode material.

[0004] A preparation method of tin dioxide negative electrode material, which is carried out according to the following steps:

[0005] I. Na2SnO3, Na3PO4 and deionized water are stirred and dissolved to obtain a micro-arc oxidation electrolyte;

[0006] The concentration of Na2SnO3 in the micro-arc oxidation electrolyte is 1 g / L to 40 g / L; and the concentration of Na3PO4 in the micro-arc oxidation electrolyte is 0.5 g / L to 30 g / L;

[0007] II. The titanium foil and the micro-arc oxidation electrolyte are placed in a micro-arc oxidation electrolytic tank, the titanium foil is used as the positive electrode, the stainless steel plate is used as the negative electrode, and the micro-arc oxidation temperature is kept constant at 10℃ to 25℃;

[0008] III. Under the conditions of temperature 10℃ to 25℃, current density 0.1A·cm -2 -3A·cm -2 , duty cycle 3% to 40% and frequency 200Hz to 2000Hz, micro-arc oxidation is carried out for 30s to 60min to obtain the tin dioxide negative electrode material.

[0009] The application has the following beneficial effects:

[0010] The application simplifies the preparation steps, generates titanium dioxide and tin dioxide in situ at the same time, plays the high discharge specific capacity of tin dioxide, and limits the volume expansion of tin dioxide in the battery charge-discharge process by the structure-stable titanium dioxide. After 500 charge-discharge cycles, the capacity retention rate is 75.3%.

[0011] 1. The application generates SnO2 and anatase TiO2 at the same time, the anatase TiO2 has stable structure, and the TiO2 surrounds the SnO2, thereby limiting the volume expansion of the SnO2 and prolonging the service life of the battery.

[0012] 2. The application has simple process for preparing the SnO2 negative electrode material, and reduces the production cost and facilitates mass production. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 Rate performance curve of the tin dioxide negative electrode material prepared in Example One;

[0014] Figure 2 Scanning electron microscope image of the tin dioxide negative electrode material prepared in Example One;

[0015] Figure 3 Cycle performance curve of the tin dioxide negative electrode material prepared in Example Two;

[0016] Figure 4 Scanning electron microscope image of the tin dioxide negative electrode material prepared in Example Two;

[0017] Figure 5 Cycle performance curve of the tin dioxide negative electrode material prepared in Example Three;

[0018] Figure 6 Scanning electron microscope image of the tin dioxide negative electrode material prepared in Example Three;

[0019] Figure 7 Scanning electron microscope image of the tin dioxide negative electrode material prepared in Example One, a is a cross-section image of the scanning electron microscope image, b is an O energy spectrum image, c is a Ti energy spectrum image, and d is a Sn energy spectrum image. DETAILED DESCRIPTION

[0020] Specific embodiment one: a preparation method of the tin dioxide negative electrode material, which is performed according to the following steps:

[0021] I. Na2SnO3, Na3PO4 and deionized water are stirred and dissolved to obtain a micro-arc oxidation electrolyte;

[0022] The concentration of Na2SnO3 in the micro-arc oxidation electrolyte is 1 g / L to 40 g / L; and the concentration of Na3PO4 in the micro-arc oxidation electrolyte is 0.5 g / L to 30 g / L;

[0023] II. The titanium foil and the micro-arc oxidation electrolyte are placed in a micro-arc oxidation electrolytic tank, the titanium foil is used as the positive electrode, a stainless steel plate is used as the negative electrode, and the micro-arc oxidation temperature is kept constant at 10℃ to 25℃;

[0024] III. The temperature is 10-25℃, the current density is 0.1-3 A·cm -2 ~3A·cm -2 , the duty cycle is 3%-40%, and the frequency is 200-2000 Hz, and the micro-arc oxidation is performed for 30-60 min to obtain the SnO2 negative electrode material.

[0025] The beneficial effects of the present embodiment are:

[0026] The present embodiment simplifies the preparation steps, and generates TiO2 and SnO2 in situ. The stable structure of TiO2 can limit the volume expansion of SnO2 during the battery charging and discharging process, and the capacity retention rate is 75.3% after 500 charging and discharging cycles.

[0027] 1. The present embodiment generates SnO2 and anatase TiO2 at the same time. The anatase TiO2 has a stable structure, and the TiO2 surrounds the SnO2, limiting the volume expansion of SnO2 and prolonging the battery life.

[0028] 2. The process for preparing the SnO2 negative electrode material is simple, reducing production costs and facilitating mass production.

[0029] Specific embodiment two: The difference between the present embodiment and the first specific embodiment is that the thickness of the titanium foil in step two is 8 μm-2 mm. The others are the same as the first specific embodiment.

[0030] Specific embodiment three: The difference between the present embodiment and the first or second specific embodiment is that the titanium foil in step two is cleaned by ultrasonic cleaning with alcohol to remove surface impurities, and then dried in a blast drying oven. The others are the same as the first or second specific embodiment.

[0031] Specific embodiment four: The difference between the present embodiment and the first to third specific embodiments is that the concentration of Na2SnO3 in the micro-arc oxidation electrolyte in step one is 20-40 g / L, and the concentration of Na3PO4 in the micro-arc oxidation electrolyte is 20-30 g / L. The others are the same as the first to third specific embodiments.

[0032] Specific embodiment five: The difference between the present embodiment and the first to fourth specific embodiments is that the concentration of Na2SnO3 in the micro-arc oxidation electrolyte in step one is 30-40 g / L, and the concentration of Na3PO4 in the micro-arc oxidation electrolyte is 10-30 g / L. The others are the same as the first to fourth specific embodiments.

[0033] Sixth embodiment: the embodiment is different from one of the first to fifth embodiments in that the concentration of Na2SnO3 in the micro-arc oxidation electrolyte in step one is 10g / L-40g / L; the concentration of Na3PO4 in the micro-arc oxidation electrolyte is 30g / L. The others are the same as the first to fifth embodiments.

[0034] Seventh embodiment: the embodiment is different from one of the first to sixth embodiments in that in step three, the micro-arc oxidation is carried out at a temperature of 10℃-25℃, a current density of 0.5A·cm -2 -3A·cm -2 , a duty cycle of 15%-40% and a frequency of 800Hz-2000Hz for 2min-60min. The others are the same as the first to sixth embodiments.

[0035] Eighth embodiment: the embodiment is different from one of the first to seventh embodiments in that in step three, the micro-arc oxidation is carried out at a temperature of 10℃-25℃, a current density of 0.8A·cm -2 -3A·cm -2 , a duty cycle of 18%-40% and a frequency of 1000Hz-2000Hz for 5min-60min. The others are the same as the first to seventh embodiments.

[0036] Ninth embodiment: the embodiment is different from one of the first to eighth embodiments in that in step three, the micro-arc oxidation is carried out at a temperature of 10℃-25℃, a current density of 0.3A·cm -2 -3A·cm -2 , a duty cycle of 10%-40% and a frequency of 500Hz-2000Hz for 1min-60min. The others are the same as the first to eighth embodiments.

[0037] Tenth embodiment: the embodiment is different from one of the first to ninth embodiments in that in step three, the micro-arc oxidation is carried out at a temperature of 10℃-25℃, a current density of 0.5A·cm -2 , a duty cycle of 15% and a frequency of 800Hz for 2min. The others are the same as the first to ninth embodiments.

[0038] The beneficial effects of the present application are verified by the following examples:

[0039] Example one:

[0040] A preparation method of a tin dioxide negative electrode material is carried out by the following steps:

[0041] I. Na2SnO3, Na3PO4 and deionized water are stirred and dissolved to obtain a micro-arc oxidation electrolyte;

[0042] The concentration of Na2SnO3 in the micro-arc oxidation electrolyte is 20 g / L; the concentration of Na3PO4 in the micro-arc oxidation electrolyte is 20 g / L;

[0043] II. The titanium foil and the micro-arc oxidation electrolyte are placed in a micro-arc oxidation electrolytic tank, the titanium foil is used as the positive electrode, the stainless steel plate is used as the negative electrode, and the micro-arc oxidation temperature is kept constant at 10-25℃;

[0044] III. The micro-arc oxidation is carried out at a temperature of 10-25℃, a current density of 0.5 A·cm -2 , a duty cycle of 15% and a frequency of 800 Hz for 2 min, to obtain the tin dioxide negative electrode material.

[0045] The size of the titanium foil in step II is 10 μm x 50 mm x 60 mm.

[0046] The titanium foil in step II is cleaned by ultrasonic washing with alcohol for 10 min to remove surface impurities, and then dried in a blast drying oven.

[0047] Example II: The difference between this example and Example I is that: the concentration of Na2SnO3 in the micro-arc oxidation electrolyte in step I is 30 g / L; the concentration of Na3PO4 in the micro-arc oxidation electrolyte is 10 g / L; in step III, the micro-arc oxidation is carried out at a temperature of 10-25℃, a current density of 0.8 A·cm 2 , a duty cycle of 18% and a frequency of 1000 Hz for 5 min. The other conditions are the same as in Example I.

[0048] Example III: The difference between this example and Example I is that: the concentration of Na2SnO3 in the micro-arc oxidation electrolyte in step I is 10 g / L; the concentration of Na3PO4 in the micro-arc oxidation electrolyte is 30 g / L; in step III, the micro-arc oxidation is carried out at a temperature of 10-25℃, a current density of 0.3 A·cm -2 , a duty cycle of 10% and a frequency of 500 Hz for 1 min. The other conditions are the same as in Example I.

[0049] Comparative Experiment: The difference between this comparative experiment and Example I is that: the concentration of Na3PO4 in the micro-arc oxidation electrolyte is 0 g / L. The other conditions are the same as in Example I.

[0050] Electrochemical performance characterization: The prepared tin dioxide negative electrode material was taken out, and a titanium foil was used as a current collector and SnO2 as an active material. Graphene and PVDF were added to N-methyl pyrrolidone (NMP) at a mass ratio of 8:1, and the mass ratio of graphene to N-methyl pyrrolidone was 0.2:1. A magnetic stirrer was used for stirring until uniform, and then the mixture was applied to the tin dioxide negative electrode material to a thickness of 10 microns. Then, vacuum drying was performed at a temperature of 120°C for 5 hours. After being taken out, the negative electrode material was cut into a Φ14mm disc, and the disc was used as a lithium battery negative electrode. In a glove box, lithium batteries were assembled in the order of positive electrode shell → electrode piece → electrolyte → separator → lithium sheet → gasket → spring piece → negative electrode shell (LIR2025 button cell). Finally, the performance of the batteries was detected using a battery detection system.

[0051] Figure 1 Rate performance curve of the tin dioxide negative electrode material prepared in Example One; as can be seen from the figure, the lithium battery made of the tin dioxide negative electrode material prepared in Example One had a discharge specific capacity of 456.7mAh / g after 500 cycles of charge and discharge at a current of 1C, and the capacity retention rate was 75.3%, indicating that the SnO2 negative electrode material prepared by this method had good cycle life.

[0052] Figure 2 Scanning electron microscope image of the tin dioxide negative electrode material prepared in Example One; as can be seen from the figure, the generated tin dioxide was uniformly distributed.

[0053] Figure 3 Cycle performance curve of the tin dioxide negative electrode material prepared in Example Two; as can be seen from the figure, the lithium battery made of the tin dioxide negative electrode material prepared in Example Two had a discharge specific capacity of 320.7mAh / g after 500 cycles of charge and discharge at a current of 1C, and the capacity retention rate was 59.1%.

[0054] Figure 4 Scanning electron microscope image of the tin dioxide negative electrode material prepared in Example Two; as can be seen from the figure, the generated tin dioxide had increased in size and partially agglomerated.

[0055] Figure 5 Cycle performance curve of the tin dioxide negative electrode material prepared in Example Three; as can be seen from the figure, the lithium battery made of the tin dioxide negative electrode material prepared in Example Three had a discharge specific capacity of 345.6mAh / g after 500 cycles of charge and discharge at a current of 1C, and the capacity retention rate was 61.9%.

[0056] Figure 6 Scanning electron microscope image of the tin dioxide negative electrode material prepared in Example Three; as can be seen from the figure, the generated tin dioxide was relatively uniformly distributed.

[0057] Figure 7The scanning electron microscope photos of the tin dioxide negative material prepared in Example 1, a is the cross-section photo of the scanning electron microscope, b is the O energy spectrum photo, c is the Ti energy spectrum photo, and d is the Sn energy spectrum photo; from the photos, it can be seen that a dense TiO2 layer is first formed on the Ti foil matrix, and then the SnO2 is embedded on the TiO2.

Claims

1. A method for preparing a tin dioxide anode material, characterized in that... It is done in the following steps:

1. Dissolve Na2SnO3, Na3PO4 and deionized water by stirring to obtain micro-arc oxidation electrolyte; The concentration of Na2SnO3 in the micro-arc oxidation electrolyte is 20 g / L; the concentration of Na3PO4 in the micro-arc oxidation electrolyte is 20 g / L.

2. Place the titanium foil and micro-arc oxidation electrolyte in a micro-arc oxidation electrolytic cell, with the titanium foil as the positive electrode and the stainless steel plate as the negative electrode, and keep the micro-arc oxidation temperature constant at 10℃~25℃. III. At a temperature of 10℃~25℃ and a current density of 0.5A·cm -2 Under the conditions of a duty cycle of 15% and a frequency of 800Hz, micro-arc oxidation for 2 minutes yields tin dioxide anode material. The titanium foil mentioned in step two has dimensions of 10μm × 50mm × 60mm; The titanium foil mentioned in step two is ultrasonically cleaned with alcohol for 10 minutes to remove surface impurities, and then dried in a forced-air drying oven. The lithium battery prepared using the aforementioned tin dioxide anode material has a discharge specific capacity of 456.7 mAh / g and a capacity retention rate of 75.3% after 500 charge-discharge cycles at 1C.

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