Some Attributes of Mn3+ Sites in Nickel-Based Layered Double Hydroxides during Methanol Electro-oxidation in Alkaline Media

An active Ni(OH)2/MnCO3 catalyst with efficient synergism for alkaline methanol oxidation

A novel Ni(OH)2/MnCO3 hybrid catalyst was developed for high-performing alkaline methanol electro-oxidation, which could well overcome the shortages of inactive MnCO3 and low intrinsic Ni(OH)2 due to the good synergistic catalysis effect from the Jahn-Teller distortion effect.

Jahn-Teller distortions boost the ultrahigh areal capacity and cycling robustness of holey NiMn-hydroxide nanosheets for flexible energy storage devices

Flexible energy storage devices with ultrahigh areal capacity and excellent cycling stability are highly desired for portable and wearable electronics. Bimetal hydroxides with low crystallinity are preferred as electrode materials due to their advantageous features of high electrochemical performance, rapid ion diffusion and high structure stability enabled by lattice disorder. Herein, holey NiMn-hydroxide (NiMn-OH) nanosheets with abundant lattice disorder induced by Jahn-Teller distortion are grown vertically on carbon cloth and their loading level reaches as high as 3.27 mg cm-2. The obtained NiMn-OH nanosheets demonstrate a superior capacity of 881 μAh cm-2 at 3 mA cm-2 and outstanding rate capability (66.4% capacity retained at 30 mA cm-2). The flexible all-solid hybrid device (NiMn-OH//Fe2O3) delivers a high energy density of 573.8 μW h cm-2 at a power density of 2.4 mW cm-2 and more importantly exhibits good cycling stability with 90.1% retained after 10 000 cycles and mechanical robustness. This proof-of-principle investigation is opening up a viable way to develop high performance electrodes for flexible energy storage devices.

Research Progress of NiMn Layered Double Hydroxides for Supercapacitors: A Review

The research on supercapacitors has been attractive due to their large power density, fast charge/discharge speed and long lifespan. The electrode materials for supercapacitors are thus intensively investigated to improve the electrochemical performances. Various transition metal layered double hydroxides (LDHs) with a hydrotalcite-like structure have been developed to be promising electrode materials. Earth-abundant metal hydroxides are very suitable electrode materials due to the low cost and high specific capacity. This is a review paper on NiMn LDHs for supercapacitor application. We focus particularly on the recent published papers using NiMn LDHs as electrode materials for supercapacitors. The preparation methods for NiMn LDHs are introduced first. Then, the structural design and chemical modification of NiMn LDH materials, as well as the composites and films derived from NiMn LDHs are discussed. These approaches are proven to be effective to enhance the performance of supercapacitor. Finally, the reports related to NiMn LDH-based asymmetric supercapacitors are summarized. A brief discussion of the future development of NiMn LDHs is also provided.