Application by using carbon nanotube/urea formaldehyde resin carbon-coated spherical microcrystalline graphite as negative electrode material of lithium ion battery

Abstract

The invention relates to application by using carbon nanotube / urea formaldehyde resin carbon-coated spherical microcrystalline graphite as negative electrode material of a lithium ion battery. Spherical microcrystalline graphite material is adopted as the lithium ion negative-electrode material to prepare the lithium ion battery, wherein the weight ratio of the negative electrode material, SBR (50% of solid content), CMC to Super-p is 97.5: 1.5: 2: 1, then moderate deionized water is added to mix to be syrup-like liquid, copper foil is coated with the liquid and dried in a vacuum drying oven for 12 h to prepare a negative electrode plate, an electrolyte of the lithium ion battery adopts 1MLiPF6 / EC+DEC+DMC=1: 1: 1, a separator is microporous polypropylene membrane, a counter electrode is alithium tablet, and the battery is assembled in a glove box with an airtight argon atmosphere. When the lithium ion battery is charged and discharged at the ratio of 0.1 C, a first charging and discharging cycle charging capacity is 390 mAh / g, and when the lithium ion battery is charged and discharged at the ratio of 5 C, after 500 times of cycles, the capacity retention ratio is 97.2%.

Description

technical field [0001] The invention relates to the field of lithium-ion batteries, and more specifically relates to the application of a carbon nanotube / urea-formaldehyde resin carbon-coated spherical microcrystalline graphite as a lithium-ion battery negative electrode material. Background technique [0002] Lithium-ion battery is a pollution-free green battery successfully developed at the end of the 20th century. Compared with traditional batteries, it has the advantages of high average discharge voltage, relatively large volume capacity and mass capacity, long discharge time, and light weight. Lithium-ion secondary batteries are rapidly marketed under the impetus of carbon materials as negative electrodes. However, while lithium-ion batteries are rapidly being marketed, there are also some problems. Some important indicators such as the discharge capacity, capacity retention rate and cycle life of the battery will drop sharply due to the phenomenon of lithium precipitat...

AI Technical Summary

Problems solved by technology

In addition, in the cycle process, it is inevitable that electrolyte solvents will be co-embedded between graphite layers. Due to the reduction of organic solvents, gas expansion will occur under high current, resulting in the exfoliation of graphite sheets, resulting in irreversible loss of active materials and solid electrolyte interface film (SEI Membrane) is continuously destroyed and regenerated, resulting in poor cycle life

However, graphite also has problems such as low specific capacity, low initial charge and discharge efficiency, and slow diffusion rate of lithium ions in graphite. Carbon nanotubes, etc.) mechanical compounding, surface oxidation treatment and other means to modify graphite, so that the electrochemical performance of graphite has been effectively improved, but its first reversible specific capacity and cycle stability at high rates still need to be improved.