Interconnected MnO2 nanoflakes supported by 3D nanostructured stainless steel plates for lithium ion battery anodes

Flexible Graphene-Wrapped Carbon Nanotube/Graphene@MnO2 3D Multilevel Porous Film for High-Performance Lithium-Ion Batteries

The ingenious design of a freestanding flexible electrode brings the possibility for power sources in emerging wearable electronic devices. Here, reduced graphene oxide (rGO) wraps carbon nanotubes (CNTs) and rGO tightly surrounded by MnO₂ nanosheets, forming a 3D multilevel porous conductive structure via vacuum freeze-drying. The sandwich-like architecture possesses multiple functions as a flexible anode for lithium-ion batteries. Micrometer-sized pores among the continuously waved rGO layers could extraordinarily improve ion diffusion. Nano-sized pores among the MnO₂ nanosheets and CNT/rGO@MnO₂ particles could provide vast accessible active sites and alleviate volume change. The tight connection between MnO₂ and carbon skeleton could facilitate electron transportation and enhance structural stability. Due to the special structure, the rGO-wrapped CNT/rGO@MnO₂ porous film as an anode shows a high capacity, excellent rate performance, and superior cycling stability (1344.2 mAh g^-1 over 630 cycles at 2 A g^-1 , 608.5 mAh g^-1 over 1000 cycles at 7.5 A g^-1 ). Furthermore, the evolutions of microstructure and chemical valence occurring inside the electrode after cycling are investigated to illuminate the structural superiority for energy storage. The excellent electrochemical performance of this freestanding flexible electrode makes it an attractive candidate for practical application in flexible energy storage.

Graphene foam supported multilevel network-like NiCo2S4 nanoarchitectures for robust lithium storage and efficient ORR catalysis

Interconnected mesoporous ultrathin nanosheets are assembled to form NiCo₂S₄ nanowall arrays, which are grown on 3D graphene foams to fabricate multilevel network-like composites.

Recent Progress in Self-Supported Metal Oxide Nanoarray Electrodes for Advanced Lithium-Ion Batteries

The rational design and fabrication of electrode materials with desirable architectures and optimized properties has been demonstrated to be an effective approach towards high-performance lithium-ion batteries (LIBs). Although nanostructured metal oxide electrodes with high specific capacity have been regarded as the most promising alternatives for replacing commercial electrodes in LIBs, their further developments are still faced with several challenges such as poor cycling stability and unsatisfying rate performance. As a new class of binder-free electrodes for LIBs, self-supported metal oxide nanoarray electrodes have many advantageous features in terms of high specific surface area, fast electron transport, improved charge transfer efficiency, and free space for alleviating volume expansion and preventing severe aggregation, holding great potential to solve the mentioned problems. This review highlights the recent progress in the utilization of self-supported metal oxide nanoarrays grown on 2D planar and 3D porous substrates, such as 1D and 2D nanostructure arrays, hierarchical nanostructure arrays, and heterostructured nanoarrays, as anodes and cathodes for advanced LIBs. Furthermore, the potential applications of these binder-free nanoarray electrodes for practical LIBs in full-cell configuration are outlined. Finally, the future prospects of these self-supported nanoarray electrodes are discussed.

Fungal Biomineralization of Manganese as a Novel Source of Electrochemical Materials

Electrical energy storage systems such as rechargeable lithium-ion batteries (LiBs) and supercapacitors have shown great promise as sustainable energy storage systems [1-4]. However, LiBs have high specific energy density (energy stored per unit mass) and act as slow, steady suppliers for large energy demands. In contrast, supercapacitors possess high specific power (energy transferred per unit mass per unit time) and can charge and discharge quickly for low energy demands. In LiBs, graphite is the most common anode material, although high electrolyte sensitivity and low charge capacity can limit performance. Efforts have been made to improve LiB or supercapacitor performance using alternative electrode materials such as carbon nanotubes and manganese oxides (MnxOy) [3, 5-14]. Microorganisms play significant roles in metal and mineral biotransformations [15-22]. Fungi possess various biomineralization properties, as well as a filamentous mycelium, which may provide mechanical support for mineral deposition. Although some research has been carried out on the application of biological materials as carbon precursors [8, 9, 23], biomineralizing fungal systems have not been investigated. In this research, novel electrochemical materials have been synthesized using a fungal Mn biomineralization process based on urease-mediated Mn carbonate bioprecipitation [24]. The carbonized fungal biomass-mineral composite (MycMnOx/C) showed a high specific capacitance (>350 F g(-1)) in a supercapacitor and excellent cycling stability (>90% capacity was retained after 200 cycles) in LiBs. This is the first demonstration of the synthesis of electrode materials using a fungal biomineralization process, thus providing a novel strategy for the preparation of sustainable electrochemical materials.

Facile Synthesis of Coaxial CNTs/MnOx-Carbon Hybrid Nanofibers and Their Greatly Enhanced Lithium Storage Performance

Carbon nanotubes (CNTs)/MnO_x-Carbon hybrid nanofibers have been successfully synthesized by the combination of a liquid chemical redox reaction (LCRR) and a subsequent carbonization heat treatment. The nanostructures exhibit a unique one-dimensional core/shell architecture, with one-dimensional CNTs encapsulated inside and a MnO_x-carbon composite nanoparticle layer on the outside. The particular porous characteristics with many meso/micro holes/pores, the highly conductive one-dimensional CNT core, as well as the encapsulating carbon matrix on the outside of the MnO_x nanoparticles, lead to excellent electrochemical performance of the electrode. The CNTs/MnO_x-Carbon hybrid nanofibers exhibit a high initial reversible capacity of 762.9 mAhg⁻¹, a high reversible specific capacity of 560.5 mAhg⁻¹ after 100 cycles, and excellent cycling stability and rate capability, with specific capacity of 396.2 mAhg⁻¹ when cycled at the current density of 1000 mAg⁻¹, indicating that the CNTs/MnO_x-Carbon hybrid nanofibers are a promising anode candidate for Li-ion batteries.

Ultrasensitive electrochemiluminescence aptasensor based on a graphene/polyaniline composite film modified electrode and CdS quantum dot coated platinum nanostructured networks as labels

A simple electrochemiluminescence (ECL) aptasensor for adenosine triphosphate (ATP) based on graphene/polyaniline (GR/PANI) composite films modified glassy carbon electrode (GCE) was successfully fabricated.

Facile one pot synthesis and Li-cycling properties of MnO2

MnO₂ compounds prepared by a molten salt method (MSM) using three different Mn-salts and studied for its electrochemical properties.