Enhanced Rate Capability and Cycling Stability of Novel Ammonium Vanadate Materials Used in Aqueous Li-Ion Batteries

Abstract

Aqueous rechargeable lithium-ion batteries (ARLBs) are considered to be promising alternatives to traditional Li+-ion batteries. Since the advent of the development of ARLB technology, vanadium oxide has been widely used as an anode material because of its great potential. However, several key flaws require urgent attention, for example, low-rate performance and meager cyclic stability. In this paper, a strategy is proposed to augment the interlayer spacing of the vanadium-oxide structure to boost its electrochemical performance. This work aims at exploiting vanadium oxide by modifying its interlayer spacing by introducing a NH4+ molecule to achieve the pillar effect and the as-prepared NH4V4O10, which exhibits a higher interlayer spacing of 9.8 Å. The increased interlayer spacing allows more Li+ to accommodate in the host material and to facilitate their migration. The NH4V4O10 coupled with a commercial LiMn2O4 cathode is able to deliver a capacity of 61.5 mAhg–1 at a current density of 3 Ag–1 in saturated aqueous LiNO3 electrolyte. The decent cyclic capacity retention of 69.5% is attained for NHVO//LiNO3//LiMn2O4 following 300 cycles of deep charge–discharge at 3 Ag–1. On the basis of the communal findings, the incorporation of NH4+ molecules into the interlayer spacing offers great promise as a high-performance anode for ARLBs.