Surface and charge ratios between the two electrodes of an electrochromic cell have been shown to be variables that affect their optical and electrochemical performance. By changing the charge ratio, at fixed applied potentials, one of the electrodes decreases its oxidation state variation, therefore lowering its electrochromic response. If the ratio is increased to high enough values the electrode will act as an ion storage layer. Surface ratio also varies the charge ratio, but offers the possibility to use increasingly transparent ion storage layers, which in turn translate into better contrast of the corresponding device. The results obtained suggest a new configuration for electrochromic devices, in which optoelectrochemical performance can be optimized without the use of complementary materials. (C) 2011 Elsevier B.V. All rights reserved.