High-performance complementary electrochromic energy storage device based on tungsten trioxide and manganese dioxide films

In this work, we have selected a representative pseudocapacitive material of manganese dioxide (MnO2) film as the complementing electrode of tungsten trioxide (WO3) film to construct a smart electrochromic energy storage device (EESD), with the aim to simultaneously provide the optical modulation and energy storage performance. WO3 and MnO2 films have been respectively synthesized via simple hydrothermal and electrodeposition methods to achieve desirable matched performance. For the constructed EESD, an obvious optical contrast (38.63% at 633 nm), fast switching times (tb/tc = 9.37/5.19 s), high coloration efficiency (85.36 cm2·C−1), satisfactory specific capacitance (10.69 mF·cm−2 at the discharge current density of 0.1 mA·cm−2) as well as excellent cycle stability (initial capacitance retention rate of 95.90% after 1000 charge/discharge cycles) have been derived. After charging, the obtained EESD could light up an LED bulb or an LCD screen, showing high promising application prospect in energy storage.