Graphite electrodes with tailored porosity for rechargeable ion-transfer batteries

Abstract

A correlation between porosity and electrochemical behavior of thin graphite electrodes has been found. To enlarge the electrode/electrolyte interface area and thus to enhance the maximum current density. LiCl and NH 4HCO 3 were used as pore-forming additives during the preparation of graphite electrodes. By adjusting the porosity, the electrochemical performance of graphite electrodes was improved. The porosity optimization led to ∼500 μm thick graphite electrodes. Up to 30 cycles at 1.5 mA/cm 2 (about 50 μA/mg C) have been performed on a number of these electrodes, confirming that a stable specific charge of > 300 Ah/kg (with respect to the graphite mass) can be achieved. Moreover, the irreversible charge loss in the first cycle was moderate, typically only ∼20% of the charge for lithium de-intercalation.