Effect of Heteroatoms on Lithium Insertion into Carbons

Abstract

Electrochemical insertion of lithium into low temperature (below 1000°C) carbons such as cokes from various precursors and nanotubes has been correlated with their elemental composition, surface functionality and microtexture. The amount of heteroatoms (O, H, N) in the investigated carbons and especially the way of their bonding with the carbon matrix affects the reversible capacity of lithium storage which varies from 200 to 460 mAh/g. It has been found that heteroatoms, mainly oxygen, play more important role inbuilt in the carbon network as crosslinking element than present in the acidic surface functional groups. Essentially, the microtextural orientation of the pseudographitic layers and the kind of porosity at the nanometric scale determine the degree of reversible lithium insertion. The role of mesopores on irreversible capacity was also indicated.

Key Words:

• lithium insertion
• heteroatoms
• microtexture
• surface functionality
• hard carbon