Recent advances in Mn-based oxides as anode materials for lithium ion batteries

The Mn-based oxides including MnO, Mn₃O₄, Mn₂O₃, MnO₂, CoMn₂O₄, ZnMn₂O₄and their carbonaceous composite/oxide supports with different morphologies and compositions as anode materials are reviewed.

Fabrication of free-standing ZnMn2O4 mesoscale tubular arrays for lithium-ion anodes with highly reversible lithium storage properties

In this paper, ZnMn2O4 mesoscale tubular arrays on current collectors were successfully synthesized using a reactive template route combined with a postcalcination process through the shape-preserving conversion of ZnO nanorod arrays in aqueous solutions at room temperature. On the basis of the experimental analyses, including X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy, a plausible formation mechanism of ZnMn2O4 tubular arrays was proposed in which solid ZnO nanorods are gradually transformed to ZnMn2O4 tubules via a simple cation exchange process between Zn(2+) and Mn(2+), followed by a postannealing process. Moreover, the lithium storage properties of the as-prepared ZnMn2O4 tubular structures were investigated by applying the structures as an active electrode material without auxiliary additives. The ZnMn2O4 array electrodes showed an excellent discharge capacity of ca. 1198.3 mAh g(-1) on the first cycle and exhibited outstanding cycling durability, rate capability, and Coulombic efficiency. These results indicate that the free-standing tubular array architectures of ZnMn2O4 prepared directly on the current collector can be powerful candidates for a highly reversible lithium storage electrode platform.

Chemo-sensors development based on low-dimensional codoped Mn2O3-ZnO nanoparticles using flat-silver electrodes

BACKGROUND

Semiconductor doped nanostructure materials have attained considerable attention owing to their electronic, opto-electronic, para-magnetic, photo-catalysis, electro-chemical, mechanical behaviors and their potential applications in different research areas. Doped nanomaterials might be a promising owing to their high-specific surface-area, low-resistances, high-catalytic activity, attractive electro-chemical and optical properties. Nanomaterials are also scientifically significant transition metal-doped nanostructure materials owing to their extraordinary mechanical, optical, electrical, electronic, thermal, and magnetic characteristics. Recently, it has gained significant interest in manganese oxide doped-semiconductor materials in order to develop their physico-chemical behaviors and extend their efficient applications. It has not only investigated the basic of magnetism, but also has huge potential in scientific features such as magnetic materials, bio- & chemi-sensors, photo-catalysts, and absorbent nanomaterials.

RESULTS

The chemical sensor also displays the higher-sensitivity, reproducibility, long-term stability, and enhanced electrochemical responses. The calibration plot is linear (r2 = 0.977) over the 0.1 nM to 50.0 μM 4-nitrophenol concentration ranges. The sensitivity and detection limit is ~4.6667 μA cm-2 μM-1 and ~0.83 ± 0.2 nM (at a Signal-to-Noise-Ratio, SNR of 3) respectively. To best of our knowledge, this is the first report for detection of 4-nitrophenol chemical with doped Mn2O3-ZnO NPs using easy and reliable I-V technique in short response time.

CONCLUSIONS

As for the doped nanostructures, NPs are introduced a route to a new generation of toxic chemo-sensors, but a premeditate effort has to be applied for doped Mn2O3-ZnO NPs to be taken comprehensively for large-scale applications, and to achieve higher-potential density with accessible to individual chemo-sensors. In this report, it is also discussed the prospective utilization of Mn2O3-ZnO NPs on the basis of carcinogenic chemical sensing, which could also be applied for the detection of hazardous chemicals in ecological, environmental, and health care fields.

Facile synthesis of loaf-like ZnMn₂O₄ nanorods and their excellent performance in Li-ion batteries

Binary transition metal oxides have been attracting extensive attention as promising anode materials for lithium-ion batteries, due to their high theoretical specific capacity, superior rate performance and good cycling stability. Here, loaf-like ZnMn2O4 nanorods with diameters of 80-150 nm and lengths of several micrometers are successfully synthesized by annealing MnOOH nanorods and Zn(OH)2 powders at 700 °C for 2 h. The electrochemical properties of the loaf-like ZnMn2O4 nanorods as an anode material are investigated in terms of their reversible capacity, and cycling performance for lithium ion batteries. The loaf-like ZnMn2O4 nanorods exhibit a reversible capacity of 517 mA h g(-1) at a current density of 500 mA g(-1) after 100 cycles. The reversible capacity of the nanorods still could be kept at 457 mA h g(-1) even at 1000 mA g(-1). The improved electrochemical performance can be ascribed to the one-dimensional shape and the porous structure of the loaf-like ZnMn2O4 nanorods, which offers the electrode convenient electron transport pathways and sufficient void spaces to tolerate the volume change during the Li(+) intercalation. These results suggest the promising potential of the loaf-like ZnMn2O4 nanorods in lithium-ion batteries.

A facile route to synthesize multiporous MnCo2O4 and CoMn2O4 spinel quasi-hollow spheres with improved lithium storage properties

A facile and general way for the synthesis of porous and hollow complex oxides is highly desirable owing to their significant applications for energy storage and other fields. In this contribution, uniform Mn(0.33)Co(0.67)CO(3) and Co(0.33)Mn(0.67)CO(3) microspheres are firstly fabricated solvothermally just by tuning the molar ratio of Mn and Co. Subsequently, the growth of multiporous MnCo(2)O(4) and CoMn(2)O(4) quasi-hollow microspheres by topotactic chemical transformation from the corresponding precursors are realized through a non-equilibrium heat treatment process. Topotactic conversion further demonstrated that the much larger CoMn(2)O(4) pores than those of MnCo(2)O(4) are possibly due to the longer transfer distance of ions. When evaluated as anode materials for LIBs (lithium ion batteries), after 25 cycles at a current density of 200 mA g(-1), the resultant MnCo(2)O(4) and CoMn(2)O(4) quasi-hollow microspheres possessed reversible capacities of 755 and 706 mA h g(-1), respectively. In particular, the MnCo(2)O(4) samples could deliver a reversible capacity as high as 610 mA h g(-1) even at a higher current density of 400 mA g(-1) with excellent electrochemical stability after 100 cycles of testing, indicating its potential application in LIBs. We believe that such good performance results from the appropriate pore size and quasi-hollow nature of MnCo(2)O(4) microspheres, which can effectively buffer the large volume variation of anodes based on the conversion reaction during Li(+) insertion/extraction. The present strategy is simple but very effective, and due to its versatility, it can be extended to other binary, even ternary complex metal oxides with high-performance in LIBs.

Formation of ZnMn2O4 ball-in-ball hollow microspheres as a high-performance anode for lithium-ion batteries

Novel ZnMn(2)O(4) ball-in-ball hollow microspheres are fabricated by a facile two-step method involving the solution synthesis of ZnMn-glycolate hollow microspheres and subsequent thermal annealing in air. When evaluated as an anode material for lithium-ion batteries, these ZnMn(2)O(4) ball-in-ball hollow microspheres show significantly enhanced electrochemical performance with high capacity, excellent cycling stability and good rate capability.