Synchronously promoting the electron and ion transport in high-loading Mn2.5V10O24∙5.9H2O cathodes for practical aqueous zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (ZIBs) are suitable candidates for stationary energy storage systems because of their inherent safety and affordability. However, the development of high-performance and high-loading ZIB cathode facing actual requirements is still a great challenge. Herein, we report Mn2.5V10O24∙5.9H2O (MVOH) as a high-loading cathode for aqueous ZIB. Combined experimental data and material simulations reveal that the inserted Mn2+ ions can regulate the electronic structure and defective state of the MVOH cathode, leading to high electric conductivity, reduced Zn2+ ion diffusion barrier, and good structural stability. Benefited from the synergistically enhanced electron and Zn2+ ion transport properties, the high-loading (11.7 mg cm−2) MVOH cathode obtains a high areal specific capacity of 3.74 mAh cm−2 and an outstanding capacity retaining rate of 91.4 % for 850 cycles at 0.5 A g−1. Noteworthy, a maximum areal capacity of 7.2 mAh cm−2 is reached at the active material mass loading of as high as 19.9 mg cm−2, exceeding most of the literature-reported results. The reversible Zn2+ ion storage behavior is also demonstrated by various ex-situ characterizations and pouch-type full cell evaluations. This work might deepen the Zn2+ ion storage knowledge of the high-loading vanadium-based cathodes and further promote the practical competitiveness of aqueous ZIBs.