A lithium-ion battery negative electrode material and preparation method thereof

Abstract

The present invention provides a lithium ion battery negative electrode material and a preparation method thereof, which is composed of tin, titanium and carbon composites; by adding a carbon material to a deionized water solution and ultrasonicating for 30 to 60 minutes; then adding a tin precursor and a titanium precursor and stirring for 24 hours; using deionized water and ethanol to centrifuge and wash the original sample, followed by drying in an oven at 80 ° C for 12 hours; the dried material is annealed in a reducing gas environment at high temperature for 1 5 hours, and the final Sn / Ti@C material is obtained after rapid cooling. The present invention adds a small amount of tin precursor and titanium precursor to the solution dispersed by the carbon material, grows SnO2 and TiO2 nanoparticles on the surface of the carbon material by hydrolysis, and obtains the original sample; then SnO2 and TiO2 are reduced to Sn / Ti alloy by a high-temperature reduction method, so as to generate a titanium carbide compound at the contact interface between tin and the carbon material, and then obtains the final Sn / Ti@C composite material after rapid cooling.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, in particular to a lithium ion battery negative electrode material and a preparation method thereof. Background Art

[0002] Lithium-ion batteries have the advantages of high energy density, high operating voltage, long cycle life and low environmental pollution. They are used more and more widely as energy storage devices, ranging from small portable phones, laptops, and micro cameras to large electric vehicles, uninterruptible power supplies and solar power generation systems. There is a trend of further replacing traditional nickel-cadmium and lead-acid batteries as power and energy storage power sources, and have become a new type of green high-energy chemical power source with great development potential in the world today.

[0003] Lithium-ion negative electrodes have always attracted widespread attention as an important component of batteries. Traditional lithium-ion batteries use graphite as the negative electrode. Although it has the advantage of good cycle performance, its theoretical specific capacity is only 372mAh / g, which is difficult to meet the requirements of high energy density applications such as electric vehicles. In addition, lithium deposition is prone to occur under high current, which poses certain safety issues. Tin materials have a large theoretical specific capacity (theoretical specific capacity can reach 993mAh / g, and volume specific capacity is as high as 7313mAh / cm 3 ), abundant reserves and good conductivity, it has become one of the focuses of research on negative electrode materials for lithium-ion batteries.

[0004] However, tin electrode materials will produce a huge volume expansion effect (>260%) during multiple charge and discharge processes, causing the electrode material to pulverize and easily peel off from the conductive network, ultimately leading to a rapid decrease in battery capacity, limiting its commercial development.

[0005] To address the tin shedding problem, nano-tin and carbon materials are commonly used to form composite materials. Carbon materials inhibit tin aggregation and volume expansion during charge and discharge. However, the physical adsorption capacity of tin and carbon materials is weak. After multiple cycles, tin still easily detaches from the carbon material, losing its original composite state and causing irreversible capacity. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the present invention provides a lithium ion battery negative electrode material and a preparation method thereof.

[0007] The present invention provides a negative electrode material for a lithium-ion battery, wherein the negative electrode material is a composite of tin, titanium and carbon; and the weight ratio of the elements in the negative electrode material is:

[0008] Sn: 5-94.8%,

[0009] Ti: 0.2-10%,

[0010] C:5-94.8%.

[0011] Preferably, the Sn / C weight ratio is 5 to 20%.

[0012] As a preference, the Ti / Sn weight ratio is 0.1-10%.

[0013] The present invention also provides a method for preparing a negative electrode material for a lithium ion battery, which specifically comprises the following steps:

[0014] S1), adding the carbon material to a deionized water solution and ultrasonicating for 30 to 60 minutes;

[0015] S2), adding Sn precursor and Ti precursor to the sonicated solution and stirring for 24 h;

[0016] S3), washing the original sample obtained in S2) by centrifugation with deionized water and ethanol, and then drying in a vacuum drying oven at 80°C for 12 h;

[0017] S4), annealing the dried material at high temperature in a reducing gas environment for 1-5 hours, and then rapidly cooling the material to obtain the final Sn / Ti@C material.

[0018] Preferably, in step S1), the carbon material is carbon nanotubes, graphite or graphene.

[0019] Preferably, in step S2), the Sn precursor is K2SnO3·3H2O, or SnCl4, or stannous 2-ethylhexanoate, the Ti precursor is TiOSO4, or titanate, or TiCl4; and the carbon material is carbon nanotubes, graphite, or graphene.

[0020] Preferably, in step S4), the reducing gas is CO, H2 or a mixture thereof with inert gases Ar and N2.

[0021] Preferably, in step S4), the reducing gas is a mixture of Ar and H2 with a volume ratio of 9:1.

[0022] The beneficial effects of the present invention are:

[0023] 1. The present invention adds a small amount of titanium during the synthesis process to convert the mechanical bite force between tin and carbon materials into a binding force after chemical bonding, thereby improving the contact state between tin and carbon materials and reducing the contact angle of tin on the carbon surface. This solves the problem of tin easily falling off during charging and discharging, and achieves the purpose of stable circulation of the tin composite material as a negative electrode of the battery;

[0024] 2. The present invention can grow Sn / Ti alloy nanoparticles with a Ti mass fraction of 0.1 to 10% on the carbon material by regulating the amount of Ti precursor;

[0025] 3. The present invention adds a small amount of titanium to tin and carbon materials, so that SnO2 and TiO2 nanoparticles grow uniformly on the surface of the carbon material, and then reduces SnO2 and TiO2 to Sn / Ti alloy through a high-temperature reduction method to generate titanium carbide compounds at the contact interface of tin and carbon materials, and then quickly cools down to obtain the final Sn / Ti@C. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a performance curve of a half-cell made of Sn / Ti@MWCNT and lithium sheet prepared in Example 1 of the present invention;

[0027] Figure 2 Schematic diagram of the principle of contact angle reduction of the present invention; DETAILED DESCRIPTION

[0028] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0029] Example 1

[0030] The preparation of Sn / Ti@MWCNT material includes the following steps:

[0031] S1), adding 0.1 g of multi-walled carbon nanotubes (MWCNT) into 35 mL of deionized water and ultrasonicating for 30 to 60 minutes;

[0032] S2), 0.6g SnCl4 and 0.008g TiOSO4 were sealed and taken to a fume hood and slowly added dropwise to the solution in S1), and stirred for 24h;

[0033] S3), filtering and centrifuging the solution in S2) multiple times and then drying under vacuum at 80°;

[0034] S4), annealing the dried material at 900°C in a gas mixture of Ar and H2 for 1 hour, and then rapidly cooling for 1 hour to obtain the final Sn / Ti@MWCNT.

[0035] like Figure 1 As shown, the Sn / Ti@MWCNT of this embodiment is combined with a lithium sheet to make a half-cell. At a high current density of 200 mA / g, the battery has a first-cycle discharge capacity of 1255 mAh / g, a charge capacity of 875 mAh / g, and an initial coulombic efficiency of 69.7%. After 500 cycles, its power generation capacity is 694.8 mAh / g, demonstrating its excellent cycle performance.

[0036] The schematic diagram of the contact angle reduction principle of the present invention can be found in Figure 2 As shown in the figure, it can be seen that after adding a small amount of titanium, titanium carbide compound (TiC) can be generated at the contact interface between tin and carbon material, and tin can maintain a low contact angle state on the surface of the titanium carbide compound. By reducing the contact angle, the contact state between the tin-carbon composite phases is improved, and the adhesion ability of tin on the carbon surface is enhanced, thereby fundamentally solving the problem of tin falling off due to volume expansion, so that the battery has the advantages of high capacity and high cycle life.

[0037] Example 2

[0038] The preparation of Sn / Ti@MWCNT material includes the following steps:

[0039] S1), adding 0.035 g of multi-walled carbon nanotubes (MWCNT) into 35 mL of deionized water and ultrasonicating for 30 to 60 minutes;

[0040] S2), adding 0.2916 g K2SnO3·3H2O and 0.00391 g SnCl4 to the sonicated solution and stirring for 24 hours;

[0041] S3), filtering and centrifuging the solution in S2) multiple times and then drying under vacuum at 80° to obtain the original sample;

[0042] S4), annealing the dried material at 1200 ° C in a gas mixture of Ar and H2 for 1.5 hours, then reducing SnO2 and TiO2 to a molten Sn / Ti alloy by a high-temperature reduction method, and obtaining the final Sn / Ti@MWCNT material after rapid cooling.

[0043] Example 3

[0044] The preparation of Sn / Ti@MWCNT material includes the following steps:

[0045] S1), adding 0.035 g of multi-walled carbon nanotubes (MWCNT) into 35 mL of deionized water and ultrasonicating for 30 to 60 minutes;

[0046] S2), add 0.1g K2SnO3·3H2O and 0.0063g TiOSO4 to the ultrasonicated solution and stir for 24 hours;

[0047] S3), filtering and centrifuging the solution in S2) multiple times and then drying under vacuum at 80° to obtain the original sample;

[0048] S4), annealing the dried material at 800 ° C in a gas mixture of Ar and H2 for 3 hours, then reducing SnO2 and TiO2 to a molten Sn / Ti alloy by a high-temperature reduction method, and obtaining the final Sn / Ti@MWCNT material after rapid cooling.

[0049] Example 4

[0050] The preparation of Sn / Ti@Graphite includes the following steps:

[0051] S1), adding 0.035 g of graphite into 35 mL of deionized water and ultrasonicating for 30 to 60 minutes;

[0052] S2), adding 0.2916 g of stannous 2-ethylhexanoate and 0.01933 g of TiOSO4 to the sonicated solution and stirring for 1 hour;

[0053] S3), filtering and centrifuging the solution in S2) multiple times and then drying under vacuum at 80° to obtain the original sample;

[0054] S4) annealing the dried material at 1000°C in a gas mixture of Ar and H2 for 2.5 hours, then reducing SnO2 and TiO2 to a molten Sn / Ti alloy by a high-temperature reduction method, and obtaining the final Sn / Ti@Graphite after rapid cooling.

[0055] Example 5

[0056] The preparation of Sn / Ti@Graphite includes the following steps:

[0057] S1), adding 0.035 g of graphite into 35 mL of deionized water and ultrasonicating for 30 to 60 minutes;

[0058] S2), adding 0.2916 g SnCl4 and 0.00391 g TiOSO4 to the sonicated solution and stirring for 24 hours;

[0059] S3), filtering and centrifuging the solution in S2) multiple times and then drying under vacuum at 80° to obtain the original sample;

[0060] S4) annealing the dried material at 1000°C in a gas mixture of Ar and H2 for 2.5 hours, then reducing SnO2 and TiO2 to a molten Sn / Ti alloy by a high-temperature reduction method, and obtaining the final Sn / Ti@Graphite after rapid cooling.

[0061] Example 6

[0062] The preparation of Sn / Ti@Graphene includes the following steps:

[0063] S1), adding 0.035 g of graphene to 35 mL of deionized water and ultrasonicating for 30 to 60 minutes;

[0064] S2), add 0.2916g K2SnO3·3H2O and 0.01933g TiOSO4 to the sonicated solution and stir for 1 hour;

[0065] S3), filtering and centrifuging the solution in S2) multiple times and then drying under vacuum at 80° to obtain the original sample;

[0066] S4) annealing the dried material at 1200°C in a gas mixture of Ar and H2 for 5 hours, then reducing SnO2 and TiO2 to a molten Sn / Ti alloy by a high-temperature reduction method, and obtaining the final Sn / Ti@Graphene after rapid cooling.

[0067] The above embodiments and descriptions are only for explaining the principles and best embodiments of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, which shall fall within the scope of the invention to be protected.

Claims

1. A negative electrode material for a lithium-ion battery, characterized in that: The negative electrode material is a composite of tin, titanium and carbon; the weight ratios of the elements in the negative electrode material are: Sn: 5-94.8%, Ti: 0.2-10%, C：5-94.8％； The method for preparing a negative electrode material for a lithium ion battery specifically comprises the following steps: S1), adding a carbon material to a deionized water solution and ultrasonicating for 30 to 60 minutes; the carbon material is carbon nanotubes, graphite or graphene; S2), adding Sn precursor and Ti precursor to the ultrasonicated solution and stirring for 24 hours; the Sn precursor is K2SnO3·3H2O, or SnCl4, or stannous 2-ethylhexanoate, and the Ti precursor is TiOSO4, titanate, or TiCl4; S3), washing the original sample obtained in S2) by centrifugation with deionized water and ethanol, and then drying in a vacuum drying oven at 80°C for 12 h; S4), annealing the dried material at high temperature in a reducing gas environment for 1-5 hours, and then rapidly cooling it to obtain the final Sn / Ti@C material.

2. A lithium ion battery negative electrode material according to claim 1, characterized in that: In step S4), the high temperature annealing temperature is between 250-2000°C.

3. A lithium ion battery negative electrode material according to claim 1, characterized in that: In step S4), the reducing gas is CO, H2 or a mixture thereof with inert gases Ar and N2.

4. A lithium-ion battery negative electrode material according to claim 1, characterized in that: In step S4), the rapid cooling time is between 1 min and 10 h.

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