A new high-performance rechargeable alkaline Zn battery based on mesoporous nitrogen-doped oxygen-deficient hematite

Highly efficient, environmentally friendly, and inexpensive cathode materials have been regarded as the core elements in a wide range of rechargeable alkaline zinc batteries (RAZBs). Herein, a three-dimensional ordered mesoporous nitrogen-doped oxygen-deficient iron trioxide nanoarray (denoted as N-Fe2O3−x) has been developed as a new kind of cathode material for RAZBs, with great promise. The N-Fe2O3−x nanoarray is prepared via a unique high-isostatic pressure-assisted nanocasting process and N2 plasma activation, which endow the N-Fe2O3−x material with highly effective areas, abundant active sites, fast electrolyte diffusion channels, and shortened charge transport pathways. Consequently, a high capacity of 288 mA h g−1 (at 1.0 A g−1) and an excellent energy density of 135 W h kg−1 (based on the weights of N-Fe2O3−x) are achieved for the Zn battery composed of N-Fe2O3−x//Zn by using the optimized N-Fe2O3−x material as the cathode and Zn metal as the anode. Moreover, the rechargeable Zn battery possesses excellent stability; at 10 A g−1, the battery retains 73% capacitance after 1000 cycles. The excellent electrochemical performance of the N-Fe2O3−x//Zn battery is much higher than those of the current Zn batteries based on iron oxides and hydroxides. This is the first example of using iron trioxide as a cathode for RAZBs, which may be of intense interest to later researchers.