Silicon-oxygen negative electrode material and preparation method thereof, negative electrode plate and secondary battery

Abstract

The invention provides a silicon-oxygen negative electrode material and a preparation method thereof, a negative electrode plate and a secondary battery. The preparation method comprises the steps of S1, adding a silicon-oxygen material into an alkaline solution with the pH value of 8-9 for dispersion, adding dopamine hydrochloride for continuous dispersion, washing, centrifuging and drying to obtain silicon-oxygen dopamine nanoparticles, and sintering the silicon-oxygen dopamine nanoparticles to obtain silicon-oxygen carbon nanoparticles; S2, mixing and stirring the silicon-oxygen carbon nanoparticles and a titanium source, heating, cooling, washing, centrifuging and drying to obtain titanium-silicon-oxygen carbon nanoparticles; and S3, dissolving the titanium-silicon-oxygen carbon nanoparticles in water, carrying out ultrasonic dispersion, then adding dopamine hydrochloride, continuing to dissolve and disperse, then adding a strongly alkaline substance, stirring, washing, centrifuging, and drying to obtain the dopamine modified silicon-oxygen negative electrode material. Compared with the prior art, the obtained negative electrode material has the advantages that the problem of volume expansion of the current silicon material in the charge-discharge process is solved, the structural stability of the silicon material in the charge-discharge process is ensured, and various properties of the battery are improved.

Description

technical field [0001] The invention relates to the field of secondary batteries, in particular to a silicon-oxygen negative electrode material, a preparation method thereof, a negative electrode sheet and a secondary battery. Background technique [0002] Lithium-ion batteries have attracted much attention due to their advantages such as high energy density, long cycle life, environmental friendliness, and no memory effect. They are widely used in 3C digital, automotive and other fields. As a negative electrode material, graphite has a theoretical gram capacity of only 372 mAh / g, which is increasingly unable to meet people's needs for high-energy-density batteries, especially with the advent of the 5G era. [0003] Silicon material has higher theoretical gram capacity (~4200 mAh / g) and low discharge voltage (~0.5 V vs Li / Li + ), considered to be one of the most promising anode materials to replace graphite. However, the silicon material will produce a large volume change ...

AI Technical Summary

Problems solved by technology

However, the silicon material will produce a large volume change (up to 300%) during the charging and discharging process, which will cause SEI instability, lithium pulverization, and weakening of the contact between active materials and between active materials and conductive agents. A series of problems eventually lead to problems such as low first efficiency, short cycle life and poor safety performance of lithium batteries, which have become the biggest obstacle restricting the wide application of silicon materials in lithium batteries