On the irreversible capacities of disordered carbons in lithium-ion rechargeable batteries

The irreversible capacity of disordered carbons, used as anodes of lithium- ion batteries, is known to result from their generally large surface area ( leading to large volume of passivating layer) and from the presence of surf ace functional groups and of heteroatoms left from the precursor, which can react irreversibly with lithium. In this paper, we show that the irreversi ble capacity of disordered carbons can result from an additional mechanism: lithium trapping in the internal porosity. A series of carbon samples with low specific surface area and low heteroatom content has been investigated by X-ray diffraction, helium pycnometry, complex impedance spectroscopy an d galvanostatic cycling. A clear correlation has been found between the irr eversible capacity and the internal pore volume. (C) 2000 Elsevier Science Ltd. All rights reserved.