Silica template assisted synthesis of ordered mesoporous β–MnO2 nanostructures and their performance evaluation as negative electrode in Li-ion batteries

Polymerization inspired synthesis of MnO@carbon nanowires with long cycling stability for lithium ion battery anodes: growth mechanism and electrochemical performance

Manganese-based transition metal oxides are regarded as one kind of high capacity and low cost anode material for Li-ion batteries. To overcome the challenges of poor electrical conductivity and large volumetric expansion during the charging-discharging process of MnO, we here synthesize MnO@carbon (MnO@C) nanowires via the polymerization inspired in situ growth of [Mn-NTA] (NTA = nitrilotriacetic acid) precursor nanowires with a subsequent heat treatment process. The growth mechanism of [Mn-NTA] precursor nanowires was studied. The morphology of the precursor nanowires depended largely on the molar ratio of MnCl2 to NTA reactants. At a molar ratio of 2, the length of the [Mn-NTA] nanowires reached up to more than 140 μm. Furthermore, the as-synthesized MnO@C nanowires were integrated with a very low content of reduced graphene oxide (rGO) to prepare a self-standing paper-like MnO@C/rGO anode for lithium ion batteries without a binder. The MnO@C/rGO anode showed a unique structure with one-dimensional porous MnO nanowires hierarchically encapsulated by a conductive carbon framework. As a result, the self-standing electrode achieved a high capacity of 1368 mA h g-1 after 100 cycles at a current density of 100 mA g-1 and prominent cycling stability with a capacity of 689.9 mA h g-1 even after 1700 cycles at 2000 mA g-1.

Supercapacitor behaviour of manganese dioxide decorated mesoporous silica synthesized by a rapid sol-gel inverse micelle method

A new type of mesoporous silica (MS) with high surface area and large pore volume has been synthesised by employing a rapid sol-gel based inverse micelle method and electrochemically active metal center, manganese, has been incorporated into it. The MnO2 decorated silica composites are obtained through the wet impregnation technique using KMnO4 followed by their reduction under neutral conditions. The structure and surface area of the samples have been characterised by powder X-ray diffraction (XRD), BET surface area and pore size analysis, transmission and scanning electron microscopy (TEM and FE-SEM), FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS). Electrochemical techniques, i.e. cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS), have been used to evaluate the electrochemical properties of the composites. The resultant composite MS/MnO2-3 with a significantly high surface area (453 m2 g-1) is found to exhibit a superior specific capacitance of 1158.50 F g-1 at a scan rate of 5 mV s-1 which is very close to the theoretical value and retains 87.8% of its capacitance up to 1000 cycles at 1 A g-1 current density. The outstanding electrochemical performance of the composite can be attributed to the high surface area and uniform pore size distribution of the novel silica host which simultaneously increases the electrochemically active centres, promotes electrolyte penetration and enhances electron transport. The simplicity of the synthesis process developed here is interesting for wide-scale production of MnO2-based electro-active materials.

MoS2 Nanoflower-Derived Interconnected CoMoO4 Nanoarchitectures as a Stable and High Rate Performing Anode for Lithium-Ion Battery Applications

In recent years, conversion-based mixed transition-metal oxides have emerged as a potential anode for the next generation lithium-ion batteries because of their high theoretical capacity and high rate performance. Herein, an interconnected cobalt molybdenum oxide (CoMoO₄) nanoarchitecture derived from molybdenum sulfide (MoS₂) nanoflowers is investigated as an anode for lithium-ion batteries. The interconnected CoMoO₄ displayed an excellent discharge capacity of 1100 mA h g^-1 over 100 cycles at a current rate of C/5. Moreover, the material exhibited an enhanced electrochemical stability, high rate performance, and delivered high discharge capacities of 600 and 220 mA h g^-1, respectively, at 5 C and 10 C after 500 cycles. The excellent cycling stability and high rate performance of interconnected CoMoO₄ are credited to its unique architecture and porous morphology. The above characteristics and the synergetic effect between the constituting metal ions not only provided a shorter diffusion path for the lithium-ion conduction but also improved the electronic conductivity and mechanical strength of the anode. The field-emission scanning electron microscopy analysis of the electrochemically cycled electrode revealed good structural integrity of the electrode. Further, the practical feasibility of interconnected CoMoO₄ in the full cell was analyzed by integrating it with the LiNi_0.8Mn_0.1Co_0.1O₂ cathode, which demonstrated excellent cycling stability and high rate performance.

A novel self-assembled-derived 1D MnO2@Co3O4 composite as a high-performance Li-ion storage anode material

Manganese dioxide (MnO₂) is a high-performance anodic material and applied widely in lithium-ion batteries (LIBs).