Properties of synthetic graphite from boric acid-added pitch: performance as anode in lithium-ion batteries

Abstract

Synthetic graphite is produced by a heat treatment process using a carbon precursor (pitch, coke), but it is difficult to produce synthetic graphite of high quality due to the high-temperature process (minimum 3000 °C). Elements used as additive to lower temperature the graphitic process include boron, phosphorus, and nitrogen. Boron is known as a graphitization additive, because it accelerates the homogeneous continuous graphitization process of the entire carbon without any formation of specific carbon components such as graphite. In this study, various amounts of boron and PFO (pyrolysis fuel oil, carbon precursor) were used in an attempt to reveal the boron additive effect. Pitch was produced using a boric acid and pyrolysis fuel oil (PFO), and high-temperature carbonization was carried out at 2600 °C. As a result, synthetic graphite exhibiting high crystallinity at a relatively low temperature was produced. The electrochemical performance of several boron-doped and non-doped carbon materials with different structures as anodes in lithium-ion batteries was investigated by a structure analysis.