Lithium ion battery composite cathode material and preparation method

Abstract

The invention relates to a lithium ion battery composite cathode material and a preparation method. The cathode material comprises a hard carbon precursor material containing hetero atoms, and natural spherical graphite, wherein the hard carbon precursor material selects one or more than two of phenolic resin, polyfurfural, furan resin, polyvinyl alcohol, epoxide resin or polyacrylonitrile as raw materials, and accounts for 5 to 45 percent of the natural spherical graphite by mass; modifier of the hetero atoms is boron-containing modifier including boric acid and diboron trioxide, phosphor-containing modifier including phosphoric acid and phosphorus pentoxide, and nitrogen-containing modifier HNO3; and one of the modifiers accounts for 5 to 35 percent of the hard carbon precursor by mass. An analog battery formed by the cathode material which is prepared by the method has the capacity over 350 mAH / g and first coulomb efficiency up to 95.8 percent, and has good circulation performance. The preparation method has the advantages of low cost and simple process.

Description

technical field [0001] The invention relates to a lithium ion battery composite negative electrode material and a preparation method. Background technique [0002] Lithium-ion batteries have high energy density, high open circuit voltage, and good safety performance. Because lithium-ion batteries have these advantages, lithium-ion batteries have been widely concerned by people since they came out. The electrode materials of lithium-ion batteries that people are studying now include metal oxides and carbon materials. Among them, carbon materials have a low voltage platform, high specific capacity, and especially low cost. These advantages have expanded the application of carbon materials in lithium-ion battery electrodes. However, it has poor compatibility with the electrolyte, and it is easy for solvated molecules to enter the graphite layer during charging, causing the graphite layer to peel off, and the electrolyte and the graphite layer continue to react, resulting in p...

AI Technical Summary

Problems solved by technology

[0003] The usual method used at present is the carbon coating method. People such as Yu Shiang Wu reported on the 2006 Journal of Alloys and Compounds 426: 218-222 that the natural graphite was coated with the hard carbon of phenolic resin. They solved it very well. However, in their preparation process, no additives containing heteroatoms were added to the hard carbon, which led to the highest coulombic efficiency of the prepared composite material for the first time, which was also lower than 90%, which could not reach Commercial use, which limits the application of hard carbon-coated spherical natural graphite for lithium-ion batteries