Discovering high-performance energy storage materials is indispensable for renewable energy, electric vehicle performance, and mobile computing. Owing to the open atomic framework and good room temperature conductivity, bronze-phase vanadium dioxide [VO2(B)] has been regarded as a highly promising electrode material for Li ion batteries. However, previous attempts were unsuccessful to show the desired cycling performance and capacity without chemical modification. Here, we show with epitaxial VO2(B) films that one can accomplish the theoretical limit for capacity with persistent charging-discharging cyclability owing to the high structural stability and unique open pathways for Li ion conduction. Atomic-scale characterization by scanning transmission electron microscopy and density functional theory calculations also reveal that the unique open pathways in VO2(B) provide the most stable sites for Li adsorption and diffusion. Thus, this work ultimately demonstrates that VO2(B) is a highly promising energy storage material and has no intrinsic hindrance in achieving superior cyclability with a very high power and capacity in a Li-ion conductor.
Keywords: Li ion battery; VO2(B); electrode; energy storage; epitaxy.