Unlocking the Potential of Disordered Rocksalts for Aqueous Zinc-Ion Batteries.

ABSTRACT

Owing to the intense charge repulsion of multivalent ions and intrinsic slugggish kenetics, vast and fast storage of zinc ions into electrode materials has remained unattainable. Here, an efficient strategy to unlock the electrochemical activity of rocksalt vanadium oxynitride is developed via the substitution of low-valent oxygen for high-valent nitrogen, forming disordered rocksalt with abundant vacancies/defects due to the charge-compensating function. Unexpectedly, the disordered rocksalt not only provides plentiful active sites for zinc ions but is also beneficial for the rapid diffusion of zinc ions, owing to the large presence of vacancies/defects in the matrix. Hence, a very high reversible capacity (603 mAh g-1 , 0.2C) and high rate capability (124 mAh g-1 at 600C) are achieved for zinc storage. This should open a new and efficient avenue for the design of electrode materials with both high energy and power densities for aqueous zinc-ion batteries.