A better understanding of the irreversible lithium insertion mechanisms in disordered carbons

It is now well established that high lithium storage capacities can be received from disordered carbons. However, compared to graphite, they generally demonstrate high hysteresis and irreversibility, and sometimes a poor cycleability, which strongly limit their practical application. Our work is an attempt for better understanding the phenomena occurring during the first reduction (discharge) of nanostructured carbons, with the expectation that this could give rise to future improvement of the electrochemical performance. The irreversible capacity is generally supposed to be related with the specific surface area, but many deviations to this law are observed. We found that a better linear relationship exists considering the active surface area (ASA). Furthermore, deactivating the surface by a pyrolytic carbon deposit allows the irreversible capacity to be noticeably reduced. The electrochemical properties of this new C/C composite are investigated by galvanostatic cycling. (C) 2003 Elsevier Ltd. All rights reserved.