Abstract
Tungsten oxide, WO3·nH2O, is a unique layered oxide material that offers enhanced performance in electrochromic and energy storage applications. Herein, we report the formation of a new, never previously synthesized, Na-containing layered tungsten oxide phase, Na0.20WO3·0.81H2O, using a chemical preintercalation approach. The structure and composition of this novel phase were investigated via microscopy, spectroscopy, and diffraction methods. Electrochemical cycling of Na0.20WO3·0.81H2O electrodes revealed initial discharge capacities of 37.43 mAh g−1, 480.8 mAh g−1, and 253.2 mAh g−1 in aqueous H2SO4 cells (potential window of − 0.2–0.8 V vs. Ag/AgCl), non-aqueous Li-ion cells (potential window of 0.1–4.0 V vs. Li/Li+), and non-aqueous Na-ion cells (potential window of 0.1–4.0 V vs. Na/Na+), respectively. Additionally, a reversible, pressure-induced color change from pale yellow to dark brown/black was observed for the Na0.20WO3·0.81H2O sample when it was placed under pressures of 1000 psi or higher. Our results demonstrate the viability of chemical preintercalation synthesis approach to produce new oxide phases with interesting functional properties.
