Ammonium‐Ion Storage Using Electrodeposited Manganese Oxides

Abstract

NH4+ ions as charge carriers show potential for aqueous rechargeable batteries. Studied here for the first time is the NH4+‐storage chemistry using electrodeposited manganese oxide (MnOx). MnOx experiences morphology and phase transformations during charge/discharge in dilute ammonium acetate (NH4Ac) electrolyte. The NH4Ac concentration plays an important role in NH4+ storage for MnOx. The transformed MnOx with a layered structure delivers a high specific capacity (176 mAh g−1) at a current density of 0.5 A g−1, and exhibits good cycling stability over 10 000 cycles in 0.5 M NH4Ac, outperforming the state‐of‐the‐art NH4+ hosting materials. Experimental results suggest a solid‐solution behavior associated with NH4+ migration in layered MnOx. Spectroscopy studies and theoretical calculations show that the reversible NH4+ insertion/deinsertion is accompanied by hydrogen‐bond formation/breaking between NH4+ and the MnOx layers. These findings provide a new prototype (i.e., layered MnOx) for NH4+‐based energy storage and contributes to the fundamental understanding of the NH4+‐storage mechanism for metal oxides.

Facile fabrication of carbon microtube arrays from waste wood for use as self-supporting supercapacitor electrodes

“…When b = 0.5, the diffusion-controlled process dominates. 35 The b values are 0.820 and 0.915 at À0.835 v peak and À1.000 v peak during the charge and discharge processes (Fig. 7a), which indicates that the kinetics is dominated by the capacitive-controlled process.…”

Electrodeposition of the MnO2 on the Ag/Au Core–Shell Nanowire and Its Application to the Flexible Supercapacitor

“…The measured CV currents (at 0.4 V) and voltage scan rates were fit with the relationship of i = av b , and the result was presented in Figure S9b. The b value was calculated to 0.82, indicating a mixed charge-storage mechanism including both capacitive and diffusion-controlled behaviors [27]. Subsequently, the charge and discharge experiments were performed at various current densities with a 2 min MnO 2 coating sample, and the results are presented in Figure 5c.…”

Hierarchical3Dmicro‐nanostructures based on in situ deposited bimetallic metal‐organic structures on carbon fabric for supercapacitor applications

“…Among the various electrode materials, metal oxides including Ni(OH) 2 , 7 NiO, 8 ZnO, 9 V 2 O 5 , 10,11 and MnO 2 , 12 metal‐organic frameworks (MOFs) 13‐15 and MOF‐derived metal oxides 16 and other heterostructure based materials have received much attention due to its higher theoretical capacity and abundant redox responses. Especially, MOF has emerged as one of the most advantageous materials due to many important properties such as high porosity, ease of manufacture, environmental affability, and low cost 17‐20 . But the poor stability and electrical conductivity of MOF materials limit the rate capability for high power handling and cause the actual experimental specific capacitance to be much lower than the theoretical value.…”

“…Especially, MOF has emerged as one of the most advantageous materials due to many important properties such as high porosity, ease of manufacture, environmental affability, and low cost. [17][18][19][20] But the poor stability and electrical conductivity of MOF materials limit the rate capability for high power handling and cause the actual experimental specific capacitance to be much lower than the theoretical value. Therefore, it is crucial and essential to further improve the electrochemical activity of MOFs.…”