Manganese oxide/carbon yolk-shell nanorod anodes for high capacity lithium batteries

Yolk-Shell TiO2@C Nanocomposite as High-Performance Anode Material for Sodium-Ion Batteries

Yolk-shell TiO₂@C nanocomposites have been synthesized successfully through a simple self-catalyzing solvothermal method. The structural and morphological characterizations reveal that TiO₂@C nanocomposite has a yolk-shell microsphere morphology with diameters of 1-2 μm, and both yolk and shell are composed of TiO₂ nanoparticles (∼10 nm). The as-prepared yolk-shell TiO₂@C composites exhibit superior sodium storage properties, with a specific capacity of 210 mAh g^-1, an outstanding cycle life of 85% capacity retention of 2000 cycles and extraordinary rate performance at 40 C rate. All the results indicate that the yolk-shell TiO₂@C nanocomposite can be suggested as a promising anode material for high-performance sodium-ion batteries.

3D nitrogen-doped graphene foam with encapsulated germanium/nitrogen-doped graphene yolk-shell nanoarchitecture for high-performance flexible Li-ion battery

Flexible electrochemical energy storage devices have attracted extensive attention as promising power sources for the ever-growing field of flexible and wearable electronic products. However, the rational design of a novel electrode structure with a good flexibility, high capacity, fast charge–discharge rate and long cycling lifetimes remains a long-standing challenge for developing next-generation flexible energy-storage materials. Herein, we develop a facile and general approach to three-dimensional (3D) interconnected porous nitrogen-doped graphene foam with encapsulated Ge quantum dot/nitrogen-doped graphene yolk-shell nano architecture for high specific reversible capacity (1,220 mAh g⁻¹), long cycling capability (over 96% reversible capacity retention from the second to 1,000 cycles) and ultra-high rate performance (over 800 mAh g⁻¹ at 40 C). This work paves a way to develop the 3D interconnected graphene-based high-capacity electrode material systems, particularly those that suffer from huge volume expansion, for the future development of high-performance flexible energy storage systems.

The development of materials for energy storage hinges on the design of electrodes with large capacity, flexibility, fast charge–discharge rate and long cycling lifetime. Here, the authors develop electrodes based on nitrogen doped graphene with encapsulated Ge quantum dots with yolk-shell architecture.

Microplasma-assisted rapid, chemical oxidant-free and controllable polymerization of dopamine for surface modification

The microplasma cathode could trigger and dramatically accelerate the polymerization process of dopamine for fabricating polydopamine coating films on various substrates.

Facile, general and template-free construction of monodisperse yolk–shell metal@carbon nanospheres

A versatile, general and template-free strategy for the construction of well-defined yolk–shell metal@carbon nanostructures is described.

Interconnected LiCuVO4networks with in situ Cu generation as high-performance lithium-ion battery anode

Interconnected LiCuVO₄networks were synthesized through a facile surfactant-assisted approach.

NiO@MnO2 core–shell composite microtube arrays for high-performance lithium ion batteries

The NiO@MnO₂ core–shell microtube array electrode with excellent lithium storage performance is fabricated by self-corrosion and electrodeposition.

Controllable growth of MnOx dual-nanocrystals on N-doped graphene as lithium-ion battery anode

Nanocomposites containing Mn₃O₄ and MnOOH dual-nanocrystals on N-doped graphene sheets were prepared as LIBs anode using a solvothermal method.

Facile electrospinning formation of carbon-confined metal oxide cube-in-tube nanostructures for stable lithium storage

A smart design of cube-in-tube nanostructures was realized by a facile precursor-modified electrospinning method with subsequent pyrolysis, which exhibit excellent electrochemical performance in lithium batteries.

Significantly enhanced electrochemical performance of a ZnCo2O4 anode in a carbonate based electrolyte with fluoroethylene carbonate

A facile inexpensive and effective way to improve the performance of a Li/ZnCo₂O₄ cell by using fluoroethylene carbonate as an additive to the conventional carbonate-based electrolyte has been reported.

Highly active 3-dimensional cobalt oxide nanostructures on the flexible carbon substrates for enzymeless glucose sensing

3-Dimensional cobalt oxide nanostructures on the flexible carbon substrates for enzymeless glucose sensing.

Freestanding graphene/MnO2 cathodes for Li-ion batteries

Different polymorphs of MnO₂ (α-, β-, and γ-) were produced by microwave hydrothermal synthesis, and graphene oxide (GO) nanosheets were prepared by oxidation of graphite using a modified Hummers' method. Freestanding graphene/MnO₂ cathodes were manufactured through a vacuum filtration process. The structure of the graphene/MnO₂ nanocomposites was characterized using X-ray diffraction (XRD) and Raman spectroscopy. The surface and cross-sectional morphologies of freestanding cathodes were investigated by scanning electron microcopy (SEM). The charge-discharge profile of the cathodes was tested between 1.5 V and 4.5 V at a constant current of 0.1 mA cm^-2 using CR2016 coin cells. The initial specific capacity of graphene/α-, β-, and γ-MnO₂ freestanding cathodes was found to be 321 mAhg^-1, 198 mAhg^-1, and 251 mAhg^-1, respectively. Finally, the graphene/α-MnO₂ cathode displayed the best cycling performance due to the low charge transfer resistance and higher electrochemical reaction behavior. Graphene/α-MnO₂ freestanding cathodes exhibited a specific capacity of 229 mAhg^-1 after 200 cycles with 72% capacity retention.

One-Pot Method for Multifunctional Yolk Structured Nanocomposites with N-doped Carbon Shell Using Polydopamine as Precursor

Herein, we reported a facile method to prepared uniform yolk like nanocomposites with well-defined N-doped carbon shell (C), in which the cores@SiO2@polydopamine (Pdop) were used as the sacrificed template. Typically, inherited from the functional Au core, the yolk particles presented excellent catalytic activities.

Electrochemical Fabrication of Monolithic Electrodes with Core/Shell Sandwiched Transition Metal Oxide/Oxyhydroxide for High-Performance Energy Storage

Transition metal oxides/oxyhydroxides (TMOs) are promising high-capacity materials for electrochemical energy storage. However, the low rate and poor cyclability hinder practical applications. In this work, we developed a general electrochemical route to fabricate monolithic core/shell sandwiched structures, which are able to significantly improve the electrochemical properties of TMO electrodes by electrically wiring the insulating active materials and alleviating the adverse effects caused by volume changes using engineered porous structures. As an example, a lithium ion battery anode of porous MnO sandwiched between CNT and carbon demonstrates a high capacity of 554 mAh g^-1 even after 1000 cycles at 2 A g^-1. An all-solid-state symmetric pseudocapacitor consisting of CNT@MnOOH@polypyrrole exhibits a high specific capacitance of 148 F g^-1 and excellent capacitance retention (92% after 10000 cycles at 2 A g^-1). Several other examples and applications have further confirmed the effectiveness of improving the electrochemical properties by core/shell sandwiched structures.

Yolk-Shell MnO@ZnMn2 O4 /N-C Nanorods Derived from α-MnO2 /ZIF-8 as Anode Materials for Lithium Ion Batteries

Manganese oxides (MnO_x ) are promising anode materials for lithium ion batteries, but they generally exhibit mediocre performances due to intrinsic low ionic conductivity, high polarization, and poor stability. Herein, yolk-shell nanorods comprising of nitrogen-doped carbon (N-C) coating on manganese monoxide (MnO) coupled with zinc manganate (ZnMn₂ O₄ ) nanoparticles are manufactured via one-step carbonization of α-MnO₂ /ZIF-8 precursors. When evaluated as anodes for lithium ion batteries, MnO@ZnMn₂ O₄ /N-C exhibits an reversible capacity of 803 mAh g^-1 at 50 mA g^-1 after 100 cycles, excellent cyclability with a capacity of 595 mAh g^-1 at 1000 mAg^-1 after 200 cycles, as well as better rate capability compared with those non-N-C shelled manganese oxides (MnO_x ). The outstanding electrochemical performance is attributed to the unique yolk-shell nanorod structure, the coating effect of N-C and nanoscale size.

Peapod-Like Carbon-Encapsulated Cobalt Chalcogenide Nanowires as Cycle-Stable and High-Rate Materials for Sodium-Ion Anodes

Peapod-like carbon-encapsulated cobalt chalcogenide nanowires are designed and synthesized by a facile method. The nanowires show excellent electrochemical performance for sodium storage, suggesting that chalcogenides, especially selenides, have potential as advanced anodes for sodium-ion batteries.

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.

Hierarchical core-shell NiCo2O4@NiMoO4 nanowires grown on carbon cloth as integrated electrode for high-performance supercapacitors

Hierarchical core-shell NiCo₂O₄@NiMoO₄ nanowires were grown on carbon cloth (CC@NiCo₂O₄@NiMoO₄) by a two-step hydrothermal route to fabricate a flexible binder-free electrode. The prepared CC@NiCo₂O₄@NiMoO₄ integrated electrode was directly used as an electrode for faradaic supercapacitor. It shows a high areal capacitance of 2.917 F cm⁻² at 2 mA cm⁻² and excellent cycling stability with 90.6% retention over 2000 cycles at a high current density of 20 mA cm⁻². The superior specific capacitance, rate and cycling performance can be ascribed to the fast transferring path for electrons and ions, synergic effect and the stability of the hierarchical core-shell structure.

Constructing Hierarchically Hollow Core-Shell MnO2 /C Hybrid Spheres for High-Performance Lithium Storage

Hierarchical MnO2 /C hybrid spheres (MCS@MnO2 ), consisting of numerous hollow core-shell MnO2 @C nanospheres, are developed via a facile deposition process. The well-defined inner voids and robust carbon framework endow MCS@MnO2 with excellent mechanical stability, efficient utilization of MnO2 , and enhanced reaction kinetics for Li-ion batteries, therefore leading to large specific capacities, superior rate capability, and long-term cycling stability.

Highly Flexible Graphene/Mn3O4 Nanocomposite Membrane as Advanced Anodes for Li-Ion Batteries

Advanced electrode design is crucial in the rapid development of flexible energy storage devices for emerging flexible electronics. Herein, we report a rational synthesis of graphene/Mn3O4 nanocomposite membranes with excellent mechanical flexibility and Li-ion storage properties. The strong interaction between the large-area graphene nanosheets and long Mn3O4 nanowires not only enables the membrane to endure various mechanical deformations but also produces a strong synergistic effect of enhanced reaction kinetics by providing enlarged electrode/electrolyte contact area and reduced electron/ion transport resistance. The mechanically robust membrane is explored as a freestanding anode for Li-ion batteries, which delivers a high specific capacity of ∼800 mAh g(-1) based on the total electrode mass, along with superior high-rate capability and excellent cycling stability. A flexible full Li-ion battery is fabricated with excellent electrochemical properties and high flexibility, demonstrating its great potential for high-performance flexible energy storage devices.

High Anodic Performance of Co 1,3,5-Benzenetricarboxylate Coordination Polymers for Li-Ion Battery

We report the designed synthesis of Co 1,3,5-benzenetricarboxylate coordination polymers (CPs) via a straightforward hydrothermal method, in which three kinds of reaction solvents are selected to form CPs with various morphologies and dimensions. When tested as anode materials in Li-ion battery, the cycling stabilities of the three CoBTC CPs at a current density of 100 mA g(-1) have not evident difference; however, the reversible capacities are widely divergent when the current density is increased to 2 A g(-1). The optimized product CoBTC-EtOH maintains a reversible capacity of 473 mAh g(-1) at a rate of 2 A g(-1) after 500 galvanostatic charging/discharging cycles while retaining a nearly 100% Coulombic efficiency. The hollow microspherical morphology, accessible specific area, and the absence of coordination solvent of CoBTC-EtOH might be responsible for such difference. Furthermore, the ex situ soft X-ray absorption spectroscopy studies of CoBTC-EtOH under different states-of-charge suggest that the Co ions remain in the Co(2+) state during the charging/discharging process. Therefore, Li ions are inserted to the organic moiety (including the carboxylate groups and the benzene ring) of CoBTC without the direct engagement of Co ions during electrochemical cycling.

Conversion Reaction-Based Oxide Nanomaterials for Lithium Ion Battery Anodes

Developing high-energy-density electrodes for lithium ion batteries (LIBs) is of primary importance to meet the challenges in electronics and automobile industries in the near future. Conversion reaction-based transition metal oxides are attractive candidates for LIB anodes because of their high theoretical capacities. This review summarizes recent advances on the development of nanostructured transition metal oxides for use in lithium ion battery anodes based on conversion reactions. The oxide materials covered in this review include oxides of iron, manganese, cobalt, copper, nickel, molybdenum, zinc, ruthenium, chromium, and tungsten, and mixed metal oxides. Various kinds of nanostructured materials including nanowires, nanosheets, hollow structures, porous structures, and oxide/carbon nanocomposites are discussed in terms of their LIB anode applications.

K2 Mn4 O8 /Reduced Graphene Oxide Nanocomposites for Excellent Lithium Storage and Adsorption of Lead Ions

Ion diffusion efficiency at the solid-liquid interface is an important factor for energy storage and adsorption from aqueous solution. Although K₂ Mn₄ O₈ (KMO) exhibits efficient ion diffusion and ion-exchange capacities, due to its high interlayer space of 0.70 nm, how to enhance its mass transfer performance is still an issue. Herein, novel layered KMO/reduced graphene oxide (RGO) nanocomposites are fabricated through the anchoring of KMO nanoplates on RGO with a mild solution process. The face-to-face structure facilitates fast transfer of lithium and lead ions; thus leading to excellent lithium storage and lead ion adsorption. The anchoring of KMO on RGO not only increases electrical conductivity of the layered nanocomposites, but also effectively prevents aggregation of KMO nanoplates. The KMO/RGO nanocomposite with an optimal RGO content exhibits a first cycle charge capacity of 739 mA h g^-1 , which is much higher than that of KMO (326 mA h g^-1 ). After 100 charge-discharge cycles, it still retains a charge capacity of 664 mA h g^-1 . For the adsorption of lead ions, the KMO/RGO nanocomposite exhibits a capacity of 341 mg g^-1 , which is higher than those of KMO (305 mg g^-1 ) and RGO (63 mg g^-1 ) alone.

One-dimensional metal oxide-carbon hybrid nanostructures for electrochemical energy storage

Numerous metal oxides (MOs) have been considered as promising electrode materials for electrochemical energy storage devices, including lithium-ion batteries (LIBs) and electrochemical capacitors (ECs), because of their outstanding features such as high capacity/capacitance, low cost, as well as environmental friendliness. However, one major challenge for MO-based electrodes is the poor cycling stability derived from the large volume variation and intense mechanic strain, which are inevitably generated during repeated charge/discharge processes. Nanostructure engineering has proven to be one of the most effective strategies to improve the electrochemical performance of MO-based electrode materials. Among various nanostructures, one-dimensional (1D) metal oxide-carbon hybrid nanostructures might offer some solution for the challenging issues involved in bulk MO-based electrode materials for energy storage devices. Herein, we give an overview of the rational design, synthesis strategies and electrochemical properties of such 1D MO-carbon structures and highlight some of the latest advances in this niche area. It starts with a brief introduction to the development of nanostructured MO-based electrodes. We will then focus on the advanced synthesis and improved electrochemical performance of 1D MO-carbon nanostructures with different configurations, including MO-carbon composite nanowires, core-shell nanowires and hierarchical nanostructures. Lastly, we give some perspective on the current challenges and possible future research directions in this area.

Highly Reversible and Ultrafast Sodium Storage in NaTi2(PO4)3 Nanoparticles Embedded in Nanocarbon Networks

Sodium ion batteries (NIBs) have been considered as an alternative for Li ion batteries (LIBs). NaTi2(PO4)3 (denoted as NTP) is a superior anode material for NIBs. However, the poor electrochemical performance of NTP resulting from the low electronic conductivity prevents its application. Here, NTP nanoparticles embedded in carbon network (denoted as NTP/C) were fabricated using a simple soft-template method. This anode material exhibits superior electrochemical performance when used as anode electrodes for NIBs, including highly reversible capacity (108 mAh g(-1) at 100 C) for excellent rate performance and long cycle life (83 mAh g(-1) at 50 C after 6000 cycles). The excellent sodium storage property can be resulted from the synergistic effects of nanosized NTP, thinner carbon shell and the interconnected carbon network, leading to the low charge transfer resistance, the large surface area for electrolyte to soak in and enough void to buffer the volume variation during the repeated cycle.

Hollow-Cuboid Li3VO4/C as High-Performance Anodes for Lithium-Ion Batteries

Li3VO4 has been demonstrated to be a promising anode material for lithium-ion batteries with a low, safe voltage and large capacity. However, its poor electronic conductivity hinders its practical application particularly at a high rate. This work reports that Li3VO4 coated with carbon was synthesized by a one-pot, two-step method with F127 ((PEO)100-(PPO)65-(PEO)100) as both template and carbon source, yielding a microcuboid structure. The resulting Li3VO4/C cuboid shows a stable capacity of 415 mAh g(-1) at 0.5 C and excellent capacity stability at high rates (e.g., 92% capacity retention after 1000 cycles at 10 C = 4 A g(-1)). The lithiation/delithiation process of Li3VO4/C was studied by ex situ X-ray diffraction and Raman spectroscopy, which confirmed that Li3VO4/C underwent a reversible intercalation reaction during discharge/charge processes. The excellent electrochemical performance is attributed largely to the unique microhollow structure. The voids inside hollow structure can not only provide more space to accommodate volume change during discharge/charge processes but also allow the lithium ions insertion and extraction from both outside and inside the hollow structure with a much larger surface area or more reaction sites and shorten the lithium ions diffusion distance, which leads to smaller overpotential and faster reaction kinetics. Carbon derived from F127 through pyrolysis coats Li3VO4 conformably and thus offers good electrical conduction. The results in this work provide convincing evidence that the significant potential of hollow-cuboid Li3VO4/C for high-power batteries.

Pyrolyzed carbon with embedded NiO/Ni nanospheres for applications in microelectrodes

Photoresist, a frequently used material in existing microfabrication processes, can be utilized in carbon micro electro mechanical system (C-MEMS) since the patterned carbon micro/nano structures can be formed by pyrolysis of a patterned photoresist.

Electrochemical construction of three-dimensional porous Mn3O4 nanosheet arrays as an anode for the lithium ion battery

The architectures of 3D pores, self-supported structure and nanosheet arrays synergistically improve the electrochemical performance of Mn₃O₄.

Microwave-assisted synthesis of porous Mn2O3 nanoballs as bifunctional electrocatalyst for oxygen reduction and evolution reaction

A facile and effective microwave-assisted route has been developed to synthesize electrochemically active pure and transition metal-doped manganese oxide nanoballs for fuel cell applications.

Facile synthesis of the Basolite F300-like nanoscale Fe-BTC framework and its lithium storage properties

Direct synthesis of a Basolite F300-like nanoscale Fe-BTC framework and its superior electrochemical performance towards lithium storage.

Crystal structure, microstructure and electrochemical properties of hydrothermally synthesised LiMn2O4

Hydrothermal synthesis offers an environmentally benign method for synthesis of LiMn₂O₄ anode material, but characterization is challenging due to structurally related impurity phases such as Li_xMn_yO₂ and Mn₃O₄, whose presence may explain the inconsistent properties in published literature.

N-doped carbon/MoS2 composites as an excellent battery anode

N-doped carbon/MoS₂ composites manifested high specific capacity of 611 mA h g⁻¹ and excellent cycling performance than bare MoS₂ and N-doped carbon.