Effect of PAN oxidation on the electrochemical lithium insertion/deinsertion behavior of resultant carbons

The effect of polyacrylonitrile (pan) oxidation on the properties and electrochemical lithium insertion/deinsertion behavior of carbons produced in the temperature range of 1000-1150°c has been assessed. air-treatment at 220 and 240°c modifies essentially the carbonization behavior of polymer leading to materials with developed microporosity and enhanced oxygen content in contrast to practically nonporous pristine pan-based carbon. the extent of the modification increases with the oxidation depth and decreases with htt. galvanostatic charge/discharge reveals typical hard carbons characteristics of all the materials. pan-based carbon heat-treated at 1050°c represents most promising anodic performance. it gives reversible capacity (c rev) near 420 mah g-1 with a reasonable coulombic efficiency during cycling of 99% and a moderate low voltage capacity of 100 mah g-1. extensive oxidation enhances overall 1st discharge cycle capacity to 870 mah g-1 and c rev to 560 mah g-1; however,large irreversible capacity (c irr) and poor cycleability are serious drawbacks of all carbons from oxidized pan. pyrolytic carbon coating using methane cvd at 830°c is effective in suppressing c irr by about 30% but the cycleability remains nonacceptable. © 2015 aleksandra piotrowska et al.