In the present work. our attention has been focused on the desired prevention of irreversible sulphation of negative test electrodes during cycling under simulated high-rate HEV duty. To this end, the negative active material was doped with carbon and, for comparison, with titanium dioxide as a nonconducting powdered additive, and the negative as well as positive electrodes were subjected to a defined pressure. Accelerated cycling revealed that electrodes doped with carbon in laboratory VRLA cells perform, in the first run, better than those doped with TiO2 since they reached about 30,000 cycles regardless of the applied pressure. However, the electrode performances were almost equalized in the second run. Mechanical pressure of 4 N cm(-2) has a pronounced favourable effect on the cycle life of negative electrodes with expanders. Higher pressures are not recommended. Electrodes doped with carbon but without standard expanders are capable of long-life cycling at elevated pressures around 6 N cm-2. Their cycle life is comparable to that of the electrodes with expanders. (C) 2012 Elsevier B.V. All rights reserved.