Key points are not available for this paper at this time.
Abstract Ammonium ions (NH 4 + ), as non‐metallic charge carriers, are attracting attention in aqueous batteries due to its low molar mass, element sufficiency, and non‐toxicity. However, the host materials for NH 4 + storage are still limited. Herein, an oxygen defects‐rich manganese oxide (MnO 2–x ) for NH 4 + storage are reported. The oxygen defects can endow the MnO 2–x sample with improved electric conductivity and low interface activation energy. The electrochemical reaction mechanism is also verified by using ex situ X‐ray photoelectron spectroscopy (XPS) and fourier transform infrared spectroscopy (FT‐IR), demonstrating the insertion and extraction of NH 4 + in the MnO 2–x by formation/breaking of a hydrogen bond. As a result, MnO 2–x delivers a high capacity of 109.9 mAh g −1 at the current density of 0.5 A g −1 and retention of 24 mAh g −1 after 1000 cycles at the current density of 4 A g −1 , outperforming the pristine MnO 2 sample.
Lu et al. (Mon,) studied this question.