High-Performance Layered CaV4O9-MXene Composite Cathodes for Aqueous Zinc Ion Batteries

Abstract

Due to their reliability, affordability and high safety, rechargeable aqueous zinc ion batteries (ZIBs) have garnered a lot of attention. Nevertheless, undesirable long-term cycle performance and the inadequate energy density of cathode materials impede the development of ZIBs. Herein, we report a layered CaV4O9-MXene (Ti3C2Tx) composite assembled using CaV4O9 nanosheets on Ti3C2Tx and investigate its electrochemical performance as a new cathode for ZIBs, where CaV4O9 nanosheets attached on the surface of MXene and interlamination create a layered 2D structure, efficiently improving the electrical conductivity of CaV4O9 and avoiding the stacking of MXene nanosheets. The structure also enables fast ion and electron transport. Further discussion is conducted on the effects of adding MXene in various amounts on the morphology and electrochemical properties. The composite shows an improved reversible capacity of 274.3 mA h g−1 at 0.1 A g−1, superior rate capabilities at 7 A g−1, and a high specific capacity of 107.6 mA h g−1 can be delivered after 2000 cycles at a current density of 1 A g−1. The improvement of the electrochemical performance is due to its unique layered structure, high electrical conductivity, and pseudo capacitance behavior.

Unveiling the Ultrahigh-Voltage Platform of Hydrated V3O7 in Carbon Network for Enhancing Aqueous Zinc-Ion Batteries Performance

“…The equivalent circuit models for before and after 100 cycles of Nyquist plots are shown in Figure b, c, respectively. The corresponding fitted values for the given equivalent circuit models are shown in Tables S1 and S2. − In addition to the Warburg impedance with the Z ′ (real part) being fitted linearly for the hydrated V 3 O 7 @C layered nanosheets, it exhibits a small slope, which clearly indicates that the Warburg coefficient is low while the metal ion diffusion coefficient is fast . Depending on the Warburg coefficient the diffusion coefficient of Zn 2+ ions ( D ) can be estimated using eqs and ): D Zn 2 + = R 2 T 2 2 A 2 n 4 F 4 C 2 σ 2 Z ′ = R c t + R s + σ ω − 0.5 In eq R is the gas constant, T represents the absolute temperature, A is the electrode’s surface area, n corresponds to the number of electrons, F represents Faraday constant, C is the concentration of zinc ions, and σ represents the Warburg factor which is obtained from Figure S5 .…”