All-nanowire based Li-ion full cells using homologous Mn2O3 and LiMn2O4

In Situ Electrophoretic Decorated Cactus-Type Metallic-Phase MoS2 on CaMn2O4 Nanofibers for Binder-Free Next-Generation LIBs

Ternary manganese-based oxides, such as CaMn2O4 (CMO) nanofibers fabricated via the electrospinning technique, have the potential to offer higher reversible capacity through conversion reactions in comparison to that of carbon-based anodes. However, its poor electrical conductivity hinders its usage in lithium-ion batteries (LIBs). Hence, to mitigate this issue, controlled single-step in situ decoration of highly conducting metallic-phase MoS2@CMO nanofibers has been achieved for the first time via the electrophoretic deposition (EPD) technique and utilized as a binder-free nanocomposite anode for LIBs. Further, the composition of MoS2@CMO nanofibers has also been optimized to attain better electronic and ionic conductivity. The morphological investigation revealed that the flakes of MoS2 nanoflowers are successfully and uniformly decorated over the CMO nanofibers' surface, forming a cactus-type morphology. As a binder-free nanocomposite LIB anode, CMOMS-7 (7 wt % MoS2@CMO) demonstrates a specific capacity of 674 mA h g-1 after 60 cycles at 50 mA g-1 and maintains a capacity of 454 mA h g-1 even after 300 cycles at 1000 mA g-1. Further, the good rate performance (102 mA h g-1 at 5000 mA g-1) of CMOMS-7 can be ascribed to the enhanced electrical conductivity provided by the metallic-phase MoS2. Moreover, the feasibility of CMOMS-7 is thoroughly investigated by using a full Li-ion cell incorporating a binder-free cathode of LiNi0.3Mn0.3Co0.3O2 (NMC). This configuration showcases an impressive energy density of 154 Wh kg-1. Thus, the hierarchical and aligned structure of CMO nanofibers combined with highly conductive MoS2 nanoflowers facilitates charge transportation within the composite electrodes. This synergistic effect significantly enhances the energy density of the conversion-based nanocomposites, making them highly promising anodes for advanced LIBs.

Improvements in the Electrochemical Performance of Sodium Manganese Oxides by Ti Doping for Aqueous Mg-Ion Batteries

In recent times, the research on cathode materials for aqueous rechargeable magnesium ion battery has gained significant attention. The focus is on enhancing high-rate performance and cycle stability, which has become the primary research goal. Manganese oxide and its derived Na-Mn-O system have been considered as one of the most promising electrode materials due to its low cost, non-toxicity and stable spatial structure. This work uses hydrothermal method to prepare titanium gradient doped nano sodium manganese oxides, and uses freeze-drying technology to prepare magnesium ion battery cathode materials with high tap density. At the initial current density of 50 mA g-1 , the NMTO-5 material exhibits a high reversible capacity of 231.0 mAh g-1 , even at a current density of 1000 mA g-1 , there is still 122.1 mAh g-1 . It is worth noting that after 180 cycles of charging and discharging at a gradually increasing current density such as 50-1000 mA g-1 , it can still return to the original level after returning to 50 mA g-1 . Excellent electrochemical performance and capacity stability show that NMTO-5 material is a promising electrode material.

Mesoporous polyvalent Ni-Mn-Co-O composite nanowire arrays towards integrated anodes boosting high-properties lithium storage

Ternary transition metal oxides (TMOs) are potentially promising anode materials for lithium storage with high power and energy density. Designing appropriate electrode structures is an effective strategy to sufficiently exhibit the advantages of TMOs for lithium storage. Here, we present the synthetic process and electrochemical properties of carbon-coated mesoporous Ni-Mn-Co-O (NMCO) nanowire arrays (NWAs) grown on Ni foam as an integrated electrode for lithium-ion batteries (LIBs). The electrochemical measurements show that the carbon-coated NMCO integrated electrode exhibits high capacity and cycling properties. In addition, we have also developed an all one-dimensional (1D) structural full cell using an LiMn₂O₄ nanorod cathode and an NMCO/Ni NWAs@C-550 anode, which exhibits relatively outstanding cycling properties.

Mesoporous multi-valence manganese oxides composite nanotubes boosting long-life lithium-ion batteries

Multi-component nano-oxide composite materials may present special synergistic effects as anode materials for lithium-ion batteries. Mesoporous β-MnO₂/Mn₃O₄ composite nanotubes are built here via controlling the deoxidation process of carbon-coating to induce a partial phase transition of high valence manganese dioxides. Compared to single β-MnO₂ nanotubes or Mn₃O₄@C nanotubes, the mesoporous β-MnO₂/Mn₃O₄@C composite nanotubes exhibit superior electrochemical properties. 679 mA h g^-1 of reversible specific capacity and 86% of capacity retention after 1000 cycles at 1 A g^-1 current density are obtained. The excellent performance is attributed to the unique multiple phase transitions regulation phenomena of manganese oxide occurring in the β-MnO₂/Mn₃O₄ composite material during the electrochemical processes, which significantly extends the cycle life of the β-MnO₂/Mn₃O₄ composite material.

Recent Developments of Nanomaterials and Nanostructures for High-Rate Lithium Ion Batteries

Lithium ion batteries have been considered as a promising energy-storage solution, the performance of which depends on the electrochemical properties of each component, including cathode, anode, electrolyte and separator. Currently, fast charging is becoming an attractive research field due to the widespread application of batteries in electric vehicles, which are designated to replace conventional diesel automobiles in the future. In these batteries, rate capability, which is closely linked to the topology and morphology of electrode materials, is one of the determining parameters of interest. It has been revealed that nanotechnology is an exceptional tool in designing and preparing cathodes and anodes with outstanding electrochemical kinetics due to the well-known nanosizing effect. Nevertheless, the negative effects of applying nanomaterials in electrodes sometimes outweigh the benefits. To better understand the exact function of nanostructures in solid-state electrodes, herein, a comprehensive review is provided beginning with the fundamental theory of lithium ion transport in solids, which is then followed by a detailed analysis of several major factors affecting the migration of lithium ions in solid-state electrodes. The latest developments in characterisation techniques, based on either electrochemical or radiology methodologies, are covered as well. In addition, state-of-the-art research findings are provided to illustrate the effect of nanomaterials and nanostructures in promoting the rate performance of lithium ion batteries. Finally, several challenges and shortcomings of applying nanotechnology in fabricating high-rate lithium ion batteries are summarised.

Reduction of hexavalent chromium and degradation of tetracycline using a novel indium-doped Mn2O3 nanorod photocatalyst

This study investigates the photocatalytic reduction of hexavalent chromium (Cr(VI)) and degradation of tetracycline (TC) via visible-light-active In-doped Mn₂O₃ photocatalysis. Mn₂O₃ photocatalysts loaded with different In doses are prepared using a simple hydrothermal method, and the results indicate the formation of Mn₂O₃ nanorod-like structures with good crystallinity. The most significant photocatalytic parameters, namely the catalyst and substrate concentrations, pH, and co-existing ions for the Cr(VI) reduction and TC degradation reactions are systematically examined. Result demonstrates that the Cr(VI) reduction and TC mineralization efficiencies of 52% and 40%, respectively are achieved at the optimum pH of 7, undoped Mn₂O₃ (10 mg/L), and Cr(VI) or TC concentration of 50 mg/L. However, these efficiencies are remarkably increased to 95% and 93%, respectively, when 10 mg/L of 5% In-doped Mn₂O₃ is used as the photocatalyst under the same reaction conditions. Moreover, the co-existing HCO₃^- anions and Ca²⁺ and Mg²⁺ divalent cations considerably deteriorate the performance of the In-doped photocatalysts compared with the SO₄^2- and Cl^- anions and Na⁺ and K⁺ monovalent cations. Liquid chromatography-mass spectrometry analysis reveals that the photodegradation of TC is mainly driven by the elimination of the -CH₃ group followed by the subsequent cleavage of the primary -NHCH₃ group.

Controllable Fabrication and Li Storage Kinetics of 1 D Spinel LiMn2 O4 Positive Materials for Li-ion Batteries: An Exploration of Critical Diameter

The morphology and size of nanoelectrode materials determine their properties. Compared to the bulk structure electrodes, 1 D electrode materials for Li-ion batteries have been intensively studied owing to their excellent Li⁺ diffusion kinetics. It is generally accepted that smaller-sized electrode materials lead to better Li storage kinetics. In this study, this is found to not be the case in 1 D LiMn₂ O₄ positive materials. A facile strategy of manipulating the KMnO₄ concentration is introduced to precisely fabricate 1 D LiMn₂ O₄ nanorods with four distinct diameter gradients from 30 to 170 nm. The role of 1 D crystal size in effecting interface chemical species and electrochemical performance is elucidated by comparative characterization methods. X-ray photoelectron spectroscopy (XPS) Ar-ion etching technology shows that the Mn²⁺ is electrochemically inactive on the surface of the sample, which explains the adverse effects observed on LiMn₂ O₄ nanorods with the minimum diameter of 30-40 nm, such as decreased discharge capacity. The LiMn₂ O₄ nanorod with a critical diameter of approximately 70-80 nm displays the highest discharge capacity and promising cycling performance. This work clarifies an important property that has previously been neglected and deepens the understanding for design of Mn-based positive materials.

A mini-review: emerging all-solid-state energy storage electrode materials for flexible devices

New technologies for future electronics such as personal healthcare devices and foldable smartphones require emerging developments in flexible energy storage devices as power sources. Besides the energy and power densities of energy devices, more attention should be paid to safety, reliability, and compatibility within highly integrated systems because they are almost in 24-hour real-time operation close to the human body. Thereupon, all-solid-state energy devices become the most promising candidates to meet these requirements. In this mini-review, the most recent research progress in all-solid-state flexible supercapacitors and batteries will be covered. The main focus of this mini-review is to summarize new materials development for all-solid-state flexible energy devices. The potential issues and perspectives regarding all-solid-state flexible energy device technologies will be highlighted.

Effect of Different Composition on Voltage Attenuation of Li-Rich Cathode Material for Lithium-Ion Batteries

Li-rich layered oxide cathode materials have become one of the most promising cathode materials for high specific energy lithium-ion batteries owning to its high theoretical specific capacity, low cost, high operating voltage and environmental friendliness. Yet they suffer from severe capacity and voltage attenuation during prolong cycling, which blocks their commercial application. To clarify these causes, we synthesize Li_1.5Mn_0.55Ni_0.4Co_0.05O_2.5 (Li_1.2Mn_0.44Ni_0.32Co_0.04O₂) with high-nickel-content cathode material by a solid-sate complexation method, and it manifests a lot slower capacity and voltage attenuation during prolong cycling compared to Li_1.5Mn_0.66Ni_0.17Co_0.17O_2.5 (Li_1.2Mn_0.54Ni_0.13Co_0.13O₂) and Li_1.5Mn_0.65Ni_0.25Co_0.1O_2.5 (Li_1.2Mn_0.52Ni_0.2Co_0.08O₂) cathode materials. The capacity retention at 1 C after 100 cycles reaches to 87.5% and the voltage attenuation after 100 cycles is only 0.460 V. Combining X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM), it indicates that increasing the nickel content not only stabilizes the structure but also alleviates the attenuation of capacity and voltage. Therefore, it provides a new idea for designing of Li-rich layered oxide cathode materials that suppress voltage and capacity attenuation.

A new nanowire-based lithium hexaoxotungstate anode for lithium-ion batteries

This study reports one dimensional lithium hexaoxotungstate (Li₆WO₆), with a diameter in the range of 200-500 nm, as a novel anode material for lithium-ion batteries. The electrochemical performance of lithium hexaoxotungstate was investigated and a discharge capacity of 705 mA h g^-1 was achieved after 50 cycles, along with an excellent rate capability. The 1D morphology of the material is believed to provide excellent transport properties, resulting in a high rate capability. The remarkable electrochemical performance of the Li₆WO₆ nanowires indicates that this new class of anode holds a lot of promise for future deployment in energy storage devices.

Tungsten oxide nanorod architectures as 3D anodes in binder-free lithium-ion batteries

Tungsten oxide nanorods were synthesized using a template assisted process. A polycarbonate membrane (pore diameter 100 nm) was vacuum infiltrated by an aqueous solution of ammonium paratungstate ((NH4)10H2W12O42·xH2O) and yielded crystalline 3D oriented WO3 nanorod arrays after template etching and calcination. By coating the nanorod arrays with carbon, a binder-free 3D WO3/C composite electrode could be fabricated, allowing capacities up to 1149, 811, 699, 559 and 253 mA h g-1 for cycles 1, 2, 20, 50 and 200 as well as a coulombic efficiency of around 99%. Moreover, as prepared WO3 nanorod structures without that specific type of carbon coating deliver capacities in a range of 200-250 mA h g-1 after 20 cycles. Finally, a full cell lithium ion battery system is fabricated. It consists of LiCoO2 nanoparticles as cathode and binder-free carbon coated 3D WO3 composite material as anode. Pre-lithiation of this 3D WO3/C composite material as pre-conditioning before full cell assembly leads to a cell capacity of almost twice of that without pre-lithiation. Discharge capacities of 111, 91, 41 and 23 mA h g-1 can be obtained for cycles 2, 20, 100 and 200 with a coulombic efficiency of around 99% in the case of the pre-lithiated 3D WO3/C composite anode.

A Porous and Conductive Graphite Nanonetwork Forming on the Surface of KCu7S4 for Energy Storage

A flexible all-solid-state supercapacitor is fabricated by building a layer of porous and conductive nanonetwork on the surface of KCu₇S₄ nanowires supported on the carbon fiber fabric, where the porous and conductive nanonetwork is assembled by graphite nanoparticles. This porous graphite layer plays a key role in providing ion diffusion channels to access the KCu₇S₄ through the pores for electrochemical reactions and forming electron transport pathways from the graphite network to the electronic collector of the carbon fiber fabric. This flexible supercapacitor exhibits excellent electrochemical performance with high specific capacitance of 408 F g^-1 at a current density of 0.5 A g^-1 and high energy density of 36 Wh kg^-1 at a power density of 201 W kg^-1. Moreover, it is cost-effective, easy to scale up and environmentally friendly with high flexibility. Our investigation demonstrates that such a porous and conductive nanonetwork could be used to improve the charge storage efficiency for a wide range of electrode materials.

Recent Advances in Nanowire-Based, Flexible, Freestanding Electrodes for Energy Storage

The rational design of flexible electrodes is essential for achieving high performance in flexible and wearable energy-storage devices, which are highly desired with fast-growing demands for flexible electronics. Owing to the one-dimensional structure, nanowires with continuous electron conduction, ion diffusion channels, and good mechanical properties are particularly favorable for obtaining flexible freestanding electrodes that can realize high energy/power density, while retaining long-term cycling stability under various mechanical deformations. This Minireview focuses on recent advances in the design, fabrication, and application of nanowire-based flexible freestanding electrodes with diverse compositions, while highlighting the rational design of nanowire-based materials for high-performance flexible electrodes. Existing challenges and future opportunities towards a deeper fundamental understanding and practical applications are also presented.

Self-Activating, Capacitive Anion Intercalation Enables High-Power Graphite Cathodes

Developing high-power cathodes is crucial to construct next-generation quick-charge batteries for electric transportation and grid applications. However, this mainly relies on nanoengineering strategies at the expense of low scalability and high battery cost. Another option is provided herein to build high-power cathodes by exploiting inexpensive bulk graphite as the active electrode material, where anion intercalation is involved. With the assistance of a strong alginate binder, the disintegration problem of graphite cathodes due to the large volume variation of >130% is well suppressed, making it possible to investigate the intrinsic electrochemical behavior and to elucidate the charge storage kinetics of graphite cathodes. Ultrahigh power capability up to 42.9 kW kg^-1 at the energy density of >300 Wh kg^-1 (based on graphite mass) and long cycling life over 10 000 cycles are achieved, much higher than those of conventional cathode materials for Li-ion batteries. A self-activating and capacitive anion intercalation into graphite is discovered for the first time, making graphite a new intrinsic intercalation-pseudocapacitance cathode material. The finding highlights the kinetical difference of anion intercalation (as cathode) from cation intercalation (as anode) into graphitic carbon materials, and new high-power energy storage devices will be inspired.

Design and Synthesis of Spherical Multicomponent Aggregates Composed of Core-Shell, Yolk-Shell, and Hollow Nanospheres and Their Lithium-Ion Storage Performances

Micrometer-sized spherical aggregates of Sn and Co components containing core-shell, yolk-shell, hollow nanospheres are synthesized by applying nanoscale Kirkendall diffusion in the large-scale spray drying process. The Sn₂ Co₃ -Co₃ SnC_0.7 -C composite microspheres uniformly dispersed with Sn₂ Co₃ -Co₃ SnC_0.7 mixed nanocrystals are formed by the first-step reduction of spray-dried precursor powders at 900 °C. The second-step oxidation process transforms the Sn₂ Co₃ -Co₃ SnC_0.7 -C composite into the porous microsphere composed of Sn-Sn₂ Co₃ @CoSnO₃ -Co₃ O₄ core-shell, Sn-Sn₂ Co₃ @CoSnO₃ -Co₃ O₄ yolk-shell, and CoSnO₃ -Co₃ O₄ hollow nanospheres at 300, 400, and 500 °C, respectively. The discharge capacity of the microspheres with Sn-Sn₂ Co₃ @CoSnO₃ -Co₃ O₄ core-shell, Sn-Sn₂ Co₃ @CoSnO₃ -Co₃ O₄ yolk-shell, and CoSnO₃ -Co₃ O₄ hollow nanospheres for the 200^th cycle at a current density of 1 A g^-1 is 1265, 987, and 569 mA h g^-1 , respectively. The ultrafine primary nanoparticles with a core-shell structure improve the structural stability of the porous-structured microspheres during repeated lithium insertion and desertion processes. The porous Sn-Sn₂ Co₃ @CoSnO₃ -Co₃ O₄ microspheres with core-shell primary nanoparticles show excellent cycling and rate performances as anode materials for lithium-ion batteries.

Hierarchically Nanostructured Transition Metal Oxides for Lithium-Ion Batteries

Lithium-ion batteries (LIBs) have been widely used in the field of portable electric devices because of their high energy density and long cycling life. To further improve the performance of LIBs, it is of great importance to develop new electrode materials. Various transition metal oxides (TMOs) have been extensively investigated as electrode materials for LIBs. According to the reaction mechanism, there are mainly two kinds of TMOs, one is based on conversion reaction and the other is based on intercalation/deintercalation reaction. Recently, hierarchically nanostructured TMOs have become a hot research area in the field of LIBs. Hierarchical architecture can provide numerous accessible electroactive sites for redox reactions, shorten the diffusion distance of Li-ion during the reaction, and accommodate volume expansion during cycling. With rapid research progress in this field, a timely account of this advanced technology is highly necessary. Here, the research progress on the synthesis methods, morphological characteristics, and electrochemical performances of hierarchically nanostructured TMOs for LIBs is summarized and discussed. Some relevant prospects are also proposed.

Synthesis and Electrochemical Property of LiMn2O4 Porous Hollow Nanofiber as Cathode for Lithium-Ion Batteries

The LiMn2O4 hollow nanofibers with a porous structure have been synthesized by modified electrospinning techniques and subsequent thermal treatment. The precursors were electrospun directly onto the fluorine-doped tin oxide (FTO) glass. The heating rate and FTO as substrate play key roles on preparing porous hollow nanofiber. As cathode materials for lithium-ion batteries (LIBs), LiMn2O4 hollow nanofibers showed the high specific capacity of 125.9 mAh/g at 0.1 C and a stable cycling performance, 105.2 mAh/g after 400 cycles. This unique structure could relieve the structure expansion effectively and provide more reaction sites as well as shorten the diffusion path for Li+ for improving electrochemical performance for LIBs.

Building Honeycomb-Like Hollow Microsphere Architecture in a Bubble Template Reaction for High-Performance Lithium-Rich Layered Oxide Cathode Materials

In the family of high-performance cathode materials for lithium-ion batteries, lithium-rich layered oxides come out in front because of a high reversible capacity exceeding 250 mAh g^-1. However, the long-term energy retention and high energy densities for lithium-rich layered oxide cathode materials require a stable structure with large surface areas. Here we propose a "bubble template" reaction to build "honeycomb-like" hollow microsphere architecture for a Li_1.2Mn_0.52Ni_0.2Co_0.08O₂ cathode material. Our material is designed with ca. 8-μm-sized secondary particles with hollow and highly exposed porous structures that promise a large flexible volume to achieve superior structure stability and high rate capability. Our preliminary electrochemical experiments show a high capacity of 287 mAh g^-1 at 0.1 C and a capacity retention of 96% after 100 cycles at 1.0 C. Furthermore, the rate capability is superior without any other modifications, reaching 197 mAh g^-1 at 3.0 C with a capacity retention of 94% after 100 cycles. This approach may shed light on a new material engineering for high-performance cathode materials.

Practical Li-Ion Battery Assembly with One-Dimensional Active Materials

Research activities on the development of one-dimensional (1D) nanostructures and their successful implementation in the fabrication of high-performance practical Li-ion batteries (LIBs) are described. Although numerous 1D-structured materials have been explored for use in LIBs as anodes, cathodes, and separator-cum-electrolytes, only a very limited number of studies report the practical assembly of LIBs using these components. As a result, the salient features of using 1D materials in charge-storage devices have not been realized from an application perspective. Exceptional battery performance is reported when all-1D-based electro-active materials are used to fabricate LIBs. Using all-1D nanostructures not only provides high power capability, energy density, and durability, it also opens up new avenues for developing high-performance next-generation Li-ion power packs.

Turning Carbon Black to Hollow Carbon Nanospheres for Enhancing Charge Storage Capacities of LiMn2O4, LiCoO2, LiNiMnCoO2, and LiFePO4 Lithium-Ion Batteries

Carbon black nanospheres were turned to hollow carbon nanospheres (HCNs) and were used as the conductive additive in the cathodes of Li-ion batteries (LIBs). The results show that 10 wt % HCN added to the LIB cathodes, such as LiMn₂O₄, LiCoO₂, LiNiMnCoO₂, and LiFePO₄, can provide significantly higher specific capacity than those using spherical carbon black. For example, a specific capacity of the LiMn₂O₄/HCN/PVDF cathode at 80:10:10 wt % with a bulk electrical conductivity of 1.07 Ω cm^-2 is 125 mA h g^-1 at 0.1 C from 3.0 to 4.3 V versus Li⁺/Li, which is 3.85-fold higher than that using Super P. The stability tested at 1 C remains over 95% after 800 charge/discharge cycles with 100% Coulombic efficiency. Replacing the present carbon black conductive additive with HCN in this work may be one of the best choices to increase the charge storage performance of LIBs rather than only focusing on the development of active cathode materials.

Facile synthesis of ultrathin Ni-MOF nanobelts for high-efficiency determination of glucose in human serum

Ultrathin Ni-MOF nanobelts, [Ni₂₀(C₅H₆O₄)₂₀(H₂O)₈]·40H₂O(Ni-MIL-77 NBs), were synthesized by a facile one-pot solution process and can be used as an efficient catalyst electrode for glucose oxidation under alkaline conditions. Electrochemical measurements demonstrate that the NB/GCE, when used as a non-enzymatic glucose sensor, offers superior analytical performances with a wide linear range (from 1 μM to 500 μM), a low detection limit (0.25 μM, signal-to-noise = 3), and a response sensitivity of 1.542 μA mM^-1 cm^-2. Moreover, it can also be applied for glucose detection in human blood serum with the relative standard deviation (RSD) of 7.41%, showing the high precision of the sensor in measuring real samples.

High Areal Capacity Si/LiCoO2 Batteries from Electrospun Composite Fiber Mats

Freestanding nanofiber mat Li-ion battery anodes containing Si nanoparticles, carbon black, and poly(acrylic acid) (Si/C/PAA) are prepared using electrospinning. The mats are compacted to a high fiber volume fraction (≈0.85), and interfiber contacts are welded by exposing the mat to methanol vapor. A compacted+welded fiber mat anode containing 40 wt % Si exhibits high capacities of 1484 mA h g^-1 (3500 mA h g-1Si ) at 0.1 C and 489 mA h g^-1 at 1 C and good cycling stability (e.g., 73 % capacity retention over 50 cycles). Post-mortem analysis of the fiber mats shows that the overall electrode structure is preserved during cycling. Whereas many nanostructured Si anodes are hindered by their low active material loadings and densities, thick, densely packed Si/C/PAA fiber mat anodes reported here have high areal and volumetric capacities (e.g., 4.5 mA h cm^-2 and 750 mA h cm^-3 , respectively). A full cell containing an electrospun Si/C/PAA anode and electrospun LiCoO₂ -based cathode has a high specific energy density of 270 Wh kg^-1 . The excellent performance of the electrospun Si/C/PAA fiber mat anodes is attributed to the: i) PAA binder, which interacts with the SiO_x surface of Si nanoparticles and ii) high material loading, high fiber volume fraction, and welded interfiber contacts of the electrospun mats.

Significant improvement in Mn2O3 transition metal oxide electrical conductivity via high pressure

Highly efficient energy storage is in high demand for next-generation clean energy applications. As a promising energy storage material, the application of Mn₂O₃ is limited due to its poor electrical conductivity. Here, high-pressure techniques enhanced the electrical conductivity of Mn₂O₃ significantly. In situ synchrotron micro X-Ray diffraction, Raman spectroscopy and resistivity measurement revealed that resistivity decreased with pressure and dramatically dropped near the phase transition. At the highest pressure, resistivity reduced by five orders of magnitude and the sample showed metal-like behavior. More importantly, resistivity remained much lower than its original value, even when the pressure was fully released. This work provides a new method to enhance the electronic properties of Mn₂O₃ using high-pressure treatment, benefiting its applications in energy-related fields.

Metal-Organic Framework-Derived NiSb Alloy Embedded in Carbon Hollow Spheres as Superior Lithium-Ion Battery Anodes

The MOFs (metal-organic frameworks) have been extensively used for electrode materials due to their high surface area, permanent porosity, and hollow structure, but the role of antimony on the MOFs is unclear. In this work, we design the hollow spheres Ni-MOFs with SbCl₃ to synthesize NiSb⊂CHSs (NiSb-embedded carbon hollow spheres) via simple annealing and galvanic replacement reactions. The NiSb⊂CHSs inherited the advantages of Ni-MOFs with hollow structure, high surface area, and permanent porosity, and the NiSb nanoparticles are coated by the formed carbon particles which could effectively solve the problem of vigorous volume changes during the Li⁺ insertion/extraction process. The porous and network structure could well provide an extremely reduced pathway for fast Li⁺ diffusion and electron transport and provide extra free space for alleviating the structural strain. The NiSb⊂CHSs with these features were used as Li-ion batteries for the first time and exhibited excellent cycling performance, high specific capacity, and great rate capability. When coupled with a nanostructure LiMn₂O₄ cathode, the NiSb⊂CHSs//LiMn₂O₄ full cell also characterized a high voltage operation of ≈3.5 V, high rate capability (210 mA h g^-1 at a current density of 2000 mA g^-1), and high Coulombic efficiency of approximate 99%, meeting the requirement for the increasing demand for improved energy devices.

Facile synthesis of porous manganese oxide/carbon composite nanowires for energy storage

We proposed a facile in situ fabrication strategy for preparing porous MnO/C composite nanowires by one-step carbonization of manganese-based coordination polymer nanowires precursor.

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.

Soft-template construction of three-dimensionally ordered inverse opal structure from Li2FeSiO4/C composite nanofibers for high-rate lithium-ion batteries

Exploring a new method to fabricate small-sized nanofibers is essential to achieve superior performances for energy conversion and storage devices. Here, a novel soft-template strategy is developed to synthesize a three-dimensionally ordered macroporous (3DOM) architecture constructed from small-sized nanofibers. The effectiveness of a nanofiber-assembled three-dimensional inverse opal material as an electrode for high-rate lithium-ion batteries is demonstrated. The small-sized Li2FeSiO4/C composite nanofibers with a diameter of 20-30 nm are grown by employing a tri-block copolymer P123 as a structure directing agent. Accordingly, the macro-mesoporous hierarchical 3DOM architecture constructed from Li2FeSiO4/C nanofibers is further templated from P123 for the nanofibers and a polystyrene colloidal crystal array for the 3DOM architecture. We find that the thermal stability of the nanofiber morphology depends on the self-limited growth of Li2FeSiO4 nanocrystals in a crystalline-amorphous hybrid. As a cathode for a lithium-ion battery, the 3D hierarchical macro-mesoporous cathodes exhibit outstanding high-rate and ultralong-life performances with a capacity retention of 84% after 1500 cycles at 5 C in the voltage window of 1.5-4.5 V, which is greatly improved compared with a simple 3DOM Li2FeSiO4/C nanocomposite.

Low-Temperature Selective Catalytic Reduction of NO with NH₃ over Mn₂O₃-Doped Fe₂O₃ Hexagonal Microsheets

Mn2O3-doped Fe2O3 hexagonal microsheets were prepared for the low-temperature selective catalytic reduction (SCR) of NO with NH3. These hexagonal microsheets were characterized by SEM, TEM, XRD, BET, XPS, NH3-TPD, H2-TPR, and in situ DRIFT and were shown to exhibit a considerable uniform hexagonal microsheet structure and excellent low temperature SCR efficiency. When doped with different Mn molar ratios, Mn2O3 was detected in the Fe2O3 hexagonal microsheets based on the XRD results without the presence of other MnOX species. In addition, the hexagonal microsheets with a Mn/Fe molar ratio of 0.2 showed the best SCR removal performance among the materials, where a 98% NO conversion ratio at 200 °C at a space velocity of 30,000 h(-1) was obtained. Meanwhile, excellent tolerances to H2O and SO2, as well as high thermal stability, were obtained in Mn2O3-doped Fe2O3 hexagonal microsheets. Moreover, on the basis of the XPS and in situ DRIFT results, it can be suggested that coupled Mn2O3 nanocrystals played a key role at low temperatures and produced a possible redox reaction mechanism in the SCR process.

Reconstruction of Mini-Hollow Polyhedron Mn2O3 Derived from MOFs as a High-Performance Lithium Anode Material

A mini-hollow polyhedron Mn2O3is used as the anode material for lithium-ion batteries. Benefiting from the small interior cavity and intrinsic nanosize effect, a stable reconstructed hierarchical nanostructure is formed. It has excellent energy storage properties, exhibiting a capacity of 760 mAh g-1 at 2 A g-1 after 1000 cycles. This finding offers a new perspective for the design of electrodes with large energy storage.

A High-Rate V2 O5 Hollow Microclew Cathode for an All-Vanadium-Based Lithium-Ion Full Cell

V2O5 hollow microclews (V2O5-HMs) have been fabricated through a facile solvothermal method with subsequent calcination. The synthesized V2O5-HMs exhibit a 3D hierarchical structure constructed by intertangled nanowires, which could realize superior ion transport, good structural stability, and significantly improved tap density. When used as the cathodes for lithium-ion batteries (LIBs), the V2O5-HMs deliver a high capacity (145.3 mAh g(-1)) and a superior rate capability (94.8 mAh g(-1) at 65 C). When coupled with a lithiated Li3VO4 anode, the all-vanadium-based lithium-ion full cell exhibits remarkable cycling stability with a capacity retention of 71.7% over 1500 cycles at 6.7 C. The excellent electrochemical performance demonstrates that the V2O5-HM is a promising candidate for LIBs. The insight obtained from this work also provides a novel strategy for assembling 1D materials into hierarchical microarchitectures with anti-pulverization ability, excellent electrochemical kinetics, and enhanced tap density.

FeMnO3: a high-performance Li-ion battery anode material

FeMnO₃particles were synthesized and evaluated as a Li-ion battery anode, exhibiting a high capacity and long-term cycling stability.