On the Capacities of Freestanding Vanadium Pentoxide–Carbon Nanotube–Nanocellulose Paper Electrodes for Charge Storage Applications

Abstract

Herein, a one-step protocol for synthesizing freestanding 20 μm thick cellulose paper electrodes composed of V2O5 ⋅ H2O nanosheets (VOx), carbon nanotubes (CNTs), and Cladophora cellulose (CC) is reported. In 1.0 m Na2SO4, the VOx–CNT–CC electrodes deliver capacities of about 200 and 50 C g−1 at scan rates of 20 and 500 mV s−1, respectively. The obtained capacities are compared with the theoretical capacities and are discussed based on the electrochemical reactions and the mass loadings of the electrodes. It is shown that the capacities are diffusion rate limited and, consequently, depend on the distribution and thickness of the V2O5 ⋅ H2O nanosheets, whereas the long-term cycling stabilities depend on vanadium species dissolving in the electrolyte. The electrodes feature high mass loadings (2 mg cm−2), good rate performances (25% capacity retention at 500 mV s−1), and capacity retentions of 85% after 8000 cycles. A symmetric VOx–CNT–CC energy storage device with a potential window of about 1 V exhibits a capacity of 40 C g−1 at a scan rate of 2 mV s−1.