Tin cobalt alloy/ graphene composite material and preparation method thereof

Abstract

The invention discloses a tin cobalt alloy / graphene composite material and a preparation method of the tin cobalt alloy / graphene composite material. The preparation method of the tin cobalt alloy / graphene composite material includes the following steps that firstly, graphene oxide is dispersed into methyl alcohol or ethylalcohol or ethylene glycol or diethylene glycol, and then suspension liquid is prepared; secondly, cobalt salt and tin slat of which the mass ratio of the sum of mass to the mass of graphene oxide ranges from 60:1 to 30:1 dissolve in the suspension liquid prepared through the first step, wherein the molar ratio of a cobalt element to a tin element ranges from 1: 0.66 to 1:3; thirdly, a sodium borohydride alcoholic solution of which the concentration ranges from 1 mol / L to 2.5 mol / L is prepared, alcohol used in the first step is used in this step, the sodium borohydride alcoholic solution is mixed with the suspension liquid obtained through the second step, nitrogen is injected, and after 10 minutes of bubbling, solvent heat treatment is conducted, wherein solvent heat treatment refers to the process that a mixture reacts for 6 h to 12 h at the temperature of 100 DEG C to 160 DEG C in a closed reaction kettle and then is cooled to the room temperature, and the molar ratio of the cobalt element in sodium borohydride to the cobalt element in the cobalt salt is 6-13 to 1; fourthly, a sample obtained in the third step is repeatedly washed centrifugally in ethyl alcohol and deionized water, and a product is obtained after vacuum drying.

Description

technical field [0001] The invention relates to the technical field of negative electrode materials for lithium batteries, in particular to a tin-cobalt alloy / graphene composite material and a preparation method thereof. Background technique [0002] At present, the negative electrode material of lithium ion battery is mainly graphitized carbon material, but the theoretical specific capacity of graphite is only 372mAh / g, and when it is charged at a high rate, it is easy to form lithium dendrites on the surface and there is a problem of poor safety, which limits scope of its use. [0003] Existing studies have shown that compared with carbon materials, certain transition metal oxides have higher theoretical capacity, such as Co 3 o 4 It can be used as a negative electrode material for lithium-ion batteries, and its theoretical specific capacity is 890mAh / g, which is about 2 to 2.5 times that of graphitized carbon materials. However, during the charging and discharging proc...

AI Technical Summary

Problems solved by technology

This is due to the expansion and contraction of the volume of tin during the charge-discharge cycle, causing the grains to break and the structure to collapse, leading to the destruction of the electrode, reducing the cycle life of the electrode, and it is easy to "agglomerate" during the lithium-deintercalation reaction. , resulting in an increase in the initial irreversible capacity and eventually a decrease in the capacity

At present, tin-based materials are generally prepared by high-temperature reduction method. The equipment is expensive, the process is complicated, and the requirements for raw materials are high, which makes the preparation cost high.

In addition, due to the large volume change of the tin-based alloy during charging and discharging, and the particle size distribution of the material prepared by this method is not uniform, and the size is difficult to control, the electrochemical stability of the obtained tin-based alloy material is poor.