Natural graphite modification method for lithium ion battery negative electrode material

Abstract

A natural graphite modification method for a lithium ion battery negative electrode material comprises the following steps: taking Ti(OC4H9)4 and CH3COOLi.2H2O according to mass proportions, carrying out low speed stirring for 10min, adding carbon-nanotube, carrying out ultrasonic dispersion for 10-60min to obtain an LTO nanosphere / carbon nanotube, adding natural graphite, carrying out low speed stirring for 10min, adding ethanol to form sol-gel at 50DEG C, continuously heating on the basis of 50DEG C until ethanol is completely evaporated in order to obtain brown solid powder, drying the brown solid powder at 150DEG C for 8h to obtain LTO precursor solid powder, heating the LTO precursor solid powder under the protection of nitrogen according to a heating rate of 10DEG C / min until the temperature rises 750DEG C, and sintering for 8h to obtain the LTO nanosphere / carbon nanotube coated natural graphite negative electrode material. The method improves the electric conductivity and the structure stability of a natural graphite coating layer.

Description

technical field [0001] The invention belongs to the technical field of preparation of lithium ion battery materials, in particular to a natural graphite modification method for negative electrode materials of lithium ion batteries. Background technique [0002] Natural graphite has the advantages of high capacity, flat charge-discharge curve, and low cost. It is an ideal anode material for lithium-ion batteries. However, natural graphite has disadvantages such as low initial charge-discharge efficiency, poor cycle performance, and high selectivity to electrolytes. Due to the structural characteristics of natural graphite with anisotropic layered structure and weak van der Waals force between layers, the anisotropic layered structure determines that the passivation SEI film formed by natural graphite during the first lithium intercalation process is not dense, lacks elasticity, It cannot prevent the co-intercalation of solvated lithium ions, thus reducing the initial charge-d...

AI Technical Summary

Problems solved by technology

[0004] 1) The platform voltage is too high, such as 1.55v ys Li+ / Li;

[0005] 2) The specific capacity is too low, the theoretical value is 175mAh / g

[0006] The above two shortcomings restrict the development of LTO in the field of lithium-ion batteries

[0007] The method of coating natural graphite with LTO / carbon nanotubes to make the prepared negative electrode material has high initial charge and discharge efficiency, high gram capacity and improved rate has not yet been reported.