Additive-free hollow-structured Co3O4 nanoparticle Li-ion battery: the origins of irreversible capacity loss

Enhancing Electrochemical Performance of Co(OH)2 Anode Materials by Introducing Graphene for Next-Generation Li-ion Batteries

To satisfy the growing demand for high-performance batteries, diverse novel anode materials with high specific capacities have been developed to replace commercial graphite. Among them, cobalt hydroxides have received considerable attention as promising anode materials for lithium-ion batteries as they exhibit a high reversible capacity owing to the additional reaction of LiOH, followed by conversion reaction. In this study, we introduced graphene in the fabrication of Co(OH)2-based anode materials to further improve electrochemical performance. The resultant Co(OH)2/graphene composite exhibited a larger reversible capacity of ~1090 mAh g−1, compared with ~705 mAh g−1 for bare Co(OH)2. Synchrotron-based analyses were conducted to explore the beneficial effects of graphene on the composite material. The experimental results demonstrate that introducing graphene into Co(OH)2 facilitates both the conversion and reaction of the LiOH phase and provides additional lithium storage sites. In addition to insights into how the electrochemical performance of composite materials can be improved, this study also provides an effective strategy for designing composite materials.

Field-Assisted Formation of NH4CoF3 Mesocrystals toward Hierarchical Co3O4 Cuboids as Anode Materials for Lithium-Ion Batteries

Porous NH₄CoF₃ mesocrystalline cuboids with highly exposed {100} facets are grown by in situ reaction of products produced by high field anodization of cobalt metal foil, via a nonclassical crystallization process involving oriented particle aggregation. 3D nano-micro hierarchical Co₃O₄ cuboids are obtained by thermal annealing of NH₄CoF₃ mesocrystals. The microstructure and morphology of products are characterized by electron microscopy and X-ray diffraction. The combination of small nanoparticle subunits, micrometer-sized overall particles, and porous structure provides the obtained hierarchical Co₃O₄ cuboids with large electrolyte-electrode contact areas, channels for large lithium ion flux, pore accessibility, and structural stability, leading to excellent rate and cyclic performance as lithium-ion battery (LIB) anodes.

Unusual pseudocapacitive lithium-ion storage on defective Co3O4nanosheets

Secondary lithium-ion batteries are restricted in large-scale applications including power grids and long driving electric vehicles owing to the low specific capacity of conventional intercalation anodes possessing sluggish Li-ion diffusion kinetics. Herein, we demonstrate an unusual pseudocapacitive lithium-ion storage on defective Co₃O₄nanosheet anodes for high-performance rechargeable batteries. Cobalt-oxide nanosheets presented here composed of various defects including vacancies, dislocations and grain boundaries. Unique 2D holey microstructure enabled efficient charge transport as well as provided room for volume expansions associated with lithiation-delithiation process. These defective anodes exhibited outstanding pseudocapacitance (up to 87%), reversible capacities (1490 mAh g^-1@ 25 mA g^-1), rate capability (592 mAh g^-1@ 30 A g^-1), stable cycling (85% after 500 cycles @ 1 A g^-1) and columbic efficiency (∼100%). Exceptional Li-ion storage phenomena in defective Co₃O₄nanosheets is accredited to the pseudocapacitive nature of conversion reaction resulting from ultrafast Li-ion diffusion through various crystal defects. The demonstrated approach of defect-induced pseudocapacitance can also be protracted for various low-cost and/or eco-friendly transition metal-oxides for next-generation rechargeable batteries.

N,S co-doped Co3O4 core-shell nanospheres with high peroxidase activity for the fast colorimetric detection of catechol

It is necessary to develop nanoperoxidases with high activity to construct a fast and cheap sensing platform for real-time detection of some pollutants. In this study, the as-prepared N and S co-doped core-shell cobaltosic oxide nanospheres (N,S-Co₃O₄) exhibit excellent peroxidase-like activity. The oxidation reaction of the colorless chromogenic substrate TMB by H₂O₂ is used to evaluate the peroxidase-like behaviors of N,S-Co₃O₄. As expected, the N,S-Co₃O₄ nanospheres accelerated the oxidation of TMB accompanied by a blue shift only in 1 min. Thus, the N,S-Co₃O₄ nanoperoxidase exhibits high affinity towards TMB (K_m = 0.072 mM) and H₂O₂ (K_m = 3.78 mM). Moreover, as the catalytic process of N,S-Co₃O₄ can be inhibited in the presence of catechol, a fast inexpensive colorimetric sensor of catechol with high sensitivity and good selectivity was constructed. The enhanced catalytic activity of N,S-Co₃O₄ is attributed to some active species, including h⁺ and ˙O₂^-, owing to the more active sites on N,S-Co₃O₄. The colorimetric method has been validated by detecting catechol in real water samples for practical application.

Realization of High Energy Density Sodium-Ion Hybrid Capacitors through Interface Engineering of Pseudocapacitive 3D-CoO-NrGO Hybrid Anodes

Sodium-ion hybrid capacitors (SHCs) have attracted great attention owing to the improved power density and cycling stability in comparison with sodium-ion batteries. Nevertheless, the energy density (<100 Wh·kg^-1) is usually limited by low specific capacity anodes (<150 mAh·g^-1) and "kinetics mismatch" between the electrodes. Hence, we report a high energy density (153 Wh·kg^-1) SHC based on a highly pseudocapacitive interface-engineered 3D-CoO-NrGO anode. This high-performance anode (445 mAh·g^-1 @0.025 A·g^-1, 135 mAh·g^-1 @5.0 A·g^-1) consists of CoO (∼6 nm) nanoparticles chemically bonded to the NrGO network through Co-O-C bonds. Exceptional pseudocapacitive charge storage (up to ∼81%) and capacity retention (∼80% after 5000 cycles) are also identified for this SHC. Excellent performance of the 3D-CoO-NrGO anode and SHC is owing to the synergistic effect of the CoO conversion reaction and pseudocapacitive sodium-ion storage induced by numerous Na₂O/Co/NrGO nanointerfaces. Co-O-C bonds and the 3D microstructure facilitating efficient strain relaxation and charge-transfer correspondingly are also identified as vital factors accountable for the excellent electrochemical performance. The interface-engineering strategy demonstrated provides opportunities to design high-performance transition metal oxide-based anodes for advanced SHCs.

Co3 O4 Polyhedron@MnO2 Nanotube Composite as Anode for High-Performance Lithium-Ion Batteries

In this work, a novel lollipop nanostructure of Co₃ O₄ @MnO₂ composite is prepared as anode material in lithium-ion batteries (LIBs). Cobalt metal-organic framework (ZIF-67) is grown on the open end of MnO₂ nanotubes via a self-assembly process. The obtained ZIF-67@MnO₂ is then converted to Co₃ O₄ @MnO₂ by a simple annealing treatment in air. Scanning electron microscopy, transmission electron microscopy, and X-ray diffraction characterizations indicate that the prepared Co₃ O₄ @MnO₂ takes a lollipop nanostructure with a stick of ≈100 nm in diameter, consisting of MnO₂ nanotube, and a head part of ≈1 µm, consisting of Co₃ O₄ nanoparticles. The charge-discharge tests illustrate that this unique novel configuration endows the resulting Co₃ O₄ @MnO₂ with excellent electrochemical performances, delivering a capacity of 1080 mAh g^-1 at 300 mA g^-1 after 160 cycles, and 696 mAh g^-1 at 1 A g^-1 after 210 cycles, compared with 404 mAh g^-1 and 590 for pure Co₃ O₄ polyhedrons and pure MnO₂ nanotubes at 300 mA g^-1 after 160 cycles, respectively. The lollipop configuration consisting of porous Co₃ O₄ polyhedron and MnO₂ nanotube shows excellent structural stability and facilitates lithium insertion/extraction, leading to excellent cyclic stability and rate capacity of Co₃ O₄ @MnO₂ -based LIBs.

Co3O4 Nanosheets as Battery-Type Electrode for High-Energy Li-Ion Capacitors: A Sustained Li-Storage via Conversion Pathway

We report the excellent charge storage performance of high-energy Li-ion capacitors (LIC) fabricated from the mesoporous Co₃O₄ nanosheets as the conversion-type battery component and Jack fruit (Artocarpus heterophyllus) derived activated carbon as a supercapacitor electrode, especially at high temperatures (50 and 40 °C). Prior to the fabrication, the electrochemical prelithiation strategy was applied to Co₃O₄ to alleviate the irreversibility and enrich the Li-ions for electrochemical reactions (Co⁰ + Li₂O). The LIC delivered a maximum energy density of ∼118 Wh kg^-1 at a high temperature of 50 °C. The significant difference is observed at a high rate of 2.6 kW kg^-1 at 50 °C with excellent cycle stability up to 3000 cycles, with a retention of ∼87% compared with the LIC cycled at room temperature (∼74%). The magnificent electrochemical performance clearly demonstrates that the mesoporous structure and residual carbon synergistically facilitated the Li⁺/electron transport and hinder undesirable side reactions with electrolytes to realize high-energy density at high temperatures.

Recent Progress on Molybdenum Oxides for Rechargeable Batteries

Diminishing fossil-fuel resources and a rise in energy demands has required the pursuit of sustainable and rechargeable energy-storage materials, including batteries and supercapacitors, the electrochemical properties of which depend largely on the electrode materials. In recent decades, numerous electrode materials with excellent electrochemical energy-storage capabilities, long life spans, and environmentally acceptable qualities have been developed. Among existing materials, molybdenum oxides containing MoO₃ and MoO₂ , as well as their composites, are very fascinating contenders for competent energy-storage devices because of their exceptional physicochemical properties, such as thermal stability, high theoretical capability, and mechanical strength. This Minireview mainly focuses on the latest progress for the use of molybdenum oxides as electrode materials for lithium-ion batteries; sodium-ion batteries; and other novel batteries, such as lithium-sulfur batteries, lithium-oxygen batteries, and newly developed hydrogen-ion batteries, with a focus on studies of the reaction mechanism, design of the electrode structures, and improvement of the electrochemical properties.

Enhancing the Mechanical and Electrical Properties of Poly(Vinyl Chloride)-Based Conductive Nanocomposites by Zinc Oxide Nanorods

A simple approach to decorate multi-walled carbon nanotube (MWCNT)–reduced graphene oxide (RGO) hybrid nanoparticles with zinc oxide (ZnO) nanorods is developed to improve the electrical and mechanical properties of poly(vinyl chloride) (PVC)/MWCNT–RGO composites. The ZnO nanorods act as “joint” in three-dimensional (3D) MWCNT–RGO networks and the hybrid particles strongly interact with PVC chains via p-π stacking, hydrogen bonds, and electrostatic interactions, which we confirmed by scanning electron microscopy (SEM) and Raman analysis. By introducing the ZnO nanorods, the RGO–ZnO–MWCNT hybrid particles increased 160% in capacitance compared with MWCNT–RGO hybrids. Moreover, the addition of RGO–ZnO–MWCNT to PVC resulted in the mechanical properties of PVC being enhanced by 30.8% for tensile strength and 60.9% for Young’s modulus at the loadings of 2.0 weight percent (wt.%) and 1.0 wt.%, respectively. Meanwhile, the electrical conductivity of PVC increased by 11 orders of magnitude, from 1 × 10⁻¹⁵ S/m to 1 × 10⁻⁴ S/m for MWCNT–ZnO–RGO loading at 5.0 wt.%.

Pseudocapacitive behavior of the Fe2O3 anode and its contribution to high reversible capacity in lithium ion batteries

Pseudocapacitance, which is the storage of charge based on continuous and fast reversible redox reactions at the surface of electrode materials, is commonly observed for electrodes in lithium ion batteries, especially for transition metal oxide anodes. In this report, bare Fe2O3 of granular morphology (∼30 nm in diameter) with high purity and decent crystallinity as well as recommendable electrochemical performances is fabricated hydrothermally and employed as the subject to clarify pseudocapacitive behavior in transition metal oxide anodes. Electrochemical technologies such as galvanostatic charging/discharging, differential capacity analysis (dQ/dV) and the power law relationship (i = aνb), which can distinguish pseudocapacitive behaviors of an electrode reaction were employed to analyze the electrodes. Reversible capacities of ∼120 mA h g-1 (0.117 F cm-2) for Fe2O3 were found within particular electrochemical windows (2.3-3.0 V, 0.3-0.8 V for discharging and 2.2-3.0 V, 0.3-1.3 V for charging). A new direction of optimizing the capacities, rate and cycling performances for lithium ion batteries is pointed out with connections between the pseudocapacitive behavior and morphologies of surfaces as well as structures of the electrodes.

High capacity lithium ion batteries composed of cobalt oxide nanoparticle anodes and Raman spectroscopic analysis of nanoparticle strain dynamics in batteries

Cobalt nanoparticle thin films were electrophoretically deposited on copper current collectors and were annealed into thin films of hollow Co₃O₄ nanoparticles. These thin films were directly used as the anodes of lithium ion batteries (LIBs) without the addition of conducting carbons and bonding agents. LIBs thus fabricated show high gravimetric capacities and long cycle lives. For ≈1.0 μm thick Co₃O₄ nanoparticle films the gravimetric capacities of the batteries were more than 800 mAh g^-1 at a current rate of C/15, which is about 90% of the theoretical maximum. Additionally, the batteries were able to undergo 200 charge/discharge cycles at a relatively fast rate of C/5 and maintain 50% of the initial capacity. In order to understand the electrochemistry of lithiation in the context of nanoparticles, Raman spectra were collected at different stages of the electrode cycles to determine the chemical and structural changes in the nanomaterials. Our results indicate that initially the electrode nanoparticles were under significant strain and as the battery underwent many cycles of charging/discharging the nanoparticles experienced progressive strain relaxation.

Cobalt Nanoparticles Chemically Bonded to Porous Carbon Nanosheets: A Stable High-Capacity Anode for Fast-Charging Lithium-Ion Batteries

A two-dimensional electrode architecture of ∼25 nm sized Co nanoparticles chemically bonded to ∼100 nm thick amorphous porous carbon nanosheets (Co@PCNS) through interfacial Co-C bonds is reported for the first time. This unique 2D hybrid architecture incorporating multiple Li-ion storage mechanisms exhibited outstanding specific capacity, rate performance, and cycling stabilities compared to nanostructured Co₃O₄ electrodes and Co-based composites reported earlier. A high discharge capacity of 900 mAh/g is achieved at a charge-discharge rate of 0.1C (50 mA/g). Even at high rates of 8C (4 A/g) and 16C (8 A/g), Co@PCNS demonstrated specific capacities of 620 and 510 mAh/g, respectively. Integrity of interfacial Co-C bonds, Co nanoparticles, and 90% of the initial capacity are preserved after 1000 charge-discharge cycles. Implementation of Co nanoparticles instead of Co₃O₄ restricted Li₂O formation during the charge-discharge process. In situ formed Co-C bonds during the pyrolysis steps improve interfacial charge transfer, and eliminate particle agglomeration, identified as the key factors responsible for the exceptional electrochemical performance of Co@PCNS. Moreover, the nanoporous microstructure and 2D morphology of carbon nanosheets facilitate superior contact with the electrolyte solution and improved strain relaxation. This study summarizes design principles for fabricating high-performance transition-metal-based Li-ion battery hybrid anodes.

Preparation of 3D hierarchical porous Co3O4 nanostructures with enhanced performance in lithium-ion batteries

Three-dimensional hierarchical Co₃O₄ microspheres assembled by well-aligned 1D porous nanorods were successfully fabricated. The sample exhibited excellent electrochemical properties as anode materials for LIBs.

In Situ Self-Assembly-Generated 3D Hierarchical Co3O4 Micro/Nanomaterial Series: Selective Synthesis, Morphological Control, and Energy Applications

A simple in situ self-assembly selective synthetic strategy for one-step controllable formation of various three-dimensional (3D) hierarchical Co₃O₄ micro/nanomaterials with peculiar morphologies, uniform size, and high quality is successfully developed. The morphological control and related impact factors are investigated and clarified in detail. The results further clarify the corresponding mechanisms on the reaction process, product generation, and calcining process as well as the formation of specific morphologies. Furthermore, the superior catalytic properties of these materials are confirmed by two typical Co-based energy applications on the decomposition of an important solid rocket propellant, ammonium perchlorate (AP), and dye-sensitized solar cells (DSSCs). The addition of Co₃O₄ materials to AP obviously decreases the decomposition temperatures by about 118-140 °C and increases the exothermic heat to a great extent. As the substituted counter electrodes of DSSCs, the 3D hierarchical Co₃O₄ materials exhibit attractive photovoltaic performances. These findings provide a facile and effective way for designing new types of 3D hierarchical materials toward high catalytic activity for energy devices.

Two-Dimensional Holey Co3O4 Nanosheets for High-Rate Alkali-Ion Batteries: From Rational Synthesis to in Situ Probing

A general template-directed strategy is developed for the controlled synthesis of two-dimensional (2D) assembly of Co₃O₄ nanoparticles (ACN) with unique holey architecture and tunable hole sizes that enable greatly improved alkali-ion storage properties (demonstrated for both Li and Na ion storage). The as-synthesized holey ACN with 10 nm holes exhibit excellent reversible capacities of 1324 mAh/g at 0.4 A/g and 566 mAh/g at 0.1 A/g for Li and Na ion storage, respectively. The improved alkali-ion storage properties are attributed to the unique interconnected holey framework that enables efficient charge/mass transport as well as accommodates volume expansion. In situ TEM characterization is employed to depict the structural evolution and further understand the structural stability of 2D holey ACN during the sodiation process. The results show that 2D holey ACN maintained the holey morphology at different sodiation stages because Co₃O₄ are converted to extremely small interconnected Co nanoparticles and these Co nanoparticles could be well dispersed in a Na₂O matrix. These extremely small Co nanoparticles are interconnected to provide good electron pathway. In addition, 2D holey Co₃O₄ exhibits small volume expansion (∼6%) compared to the conventional Co₃O₄ particles. The 2D holey nanoarchitecture represents a promising structural platform to address the restacking and accommodate the volume expansion of 2D nanosheets for superior alkali-ion storage.

High-rate-capability asymmetric supercapacitor device based on lily-like Co3O4 nanostructures assembled using nanowires

In this paper, high-rate-capability asymmetric supercapacitor device assembled by lily-like Co₃O₄ nanostructures and active carbon was presented.

Achieving Fully Reversible Conversion in MoO3 for Lithium Ion Batteries by Rational Introduction of CoMoO4

Electrode materials based on conversion reactions with lithium ions generally show much higher energy density. One of the main challenges in the design of these electrode materials is to improve initial Coulombic efficiency and alleviate the volume changes during the lithiation-delithiation processes. Here, we achieve fully reversible conversion in MoO₃ as an anode for lithium ion batteries by the hybridization of CoMoO₄. The porous MoO₃-CoMoO₄ microspheres are constructed by homogeneously dispersed MoO₃ and CoMoO₄ subunits and their lithiation/delithiation processes were studied by ex situ TEM to reveal the mechanism of the reversible conversion reaction. Co nanoparticles are in situ formed from CoMoO₄ during the lithiation process, which then act as the catalyst to guarantee the reversible decomposition of Li₂O, thus effectively improving the reversible specific capacity and initial Coulombic efficiency. Moreover, the pores in MoO₃-CoMoO₄ microspheres also greatly enhance their mechanical strength and provide enough cavity to alleviate volume changes during repeated cycling. Such a design concept makes MoO₃ to be a potential promising anode in practical applications. The full cell (LiFePO₄ cathode/MoO₃-CoMoO₄ anode) displays a high capacity up to 155.7 mAh g^-1 at 0.1 C and an initial Coulombic efficiency as high as 97.35%. This work provides impetus for further development in electrochemical charge storage devices.

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.

Metal Organic Frameworks Derived Hierarchical Hollow NiO/Ni/Graphene Composites for Lithium and Sodium Storage

Ni-based metal organic frameworks (Ni-MOFs) with unique hierarchical hollow ball-in-ball nanostructure were synthesized by solvothermal reactions. After successive carbonization and oxidation treatments, hierarchical NiO/Ni nanocrystals covered with a graphene shell were obtained with the hollow ball-in-ball nanostructure intact. The resulting materials exhibited superior performance as the anode in lithium ion batteries (LIBs): they provide high reversible specific capacity (1144 mAh/g), excellent cyclability (nearly no capacity loss after 1000 cycles) and rate performance (805 mAh/g at 15 A/g). In addition, the hierarchical NiO/Ni/Graphene composites demonstrated promising performance as anode materials for sodium-ion batteries (SIBs). Such a superior lithium and sodium storage performance is derived from the well-designed hierarchical hollow ball-in-ball structure of NiO/Ni/Graphene composites, which not only mitigates the volume expansion of NiO during the cycles but also provides a continuous highly conductive graphene matrix to facilitate the fast charge transfer and form a stable SEI layer.

High-performance lithium storage of Ti3+-doped anatase TiO2@C composite spheres

Ti³⁺-Doped anatase TiO₂@C composite spheres as the anode materials for lithium ion batteries.

Tuning the morphology of Co3O4 on Ni foam for supercapacitor application

NH₄F was used as a vital additive to control the morphology of Co₃O₄ precursors through hydrothermal reaction, some novel growth mechanisms are proposed. Co₃O₄ materials were obtained via thermal decomposition for supercapacitor application.

Facile synthesis and performance of Na-doped porous lithium-rich cathodes for lithium ion batteries

Na-doped porous lithium-rich (Li-rich) cathode microspheres (∼1 μm) were firstly prepared via the solvothermal method and subsequently a high-temperature calcination process.

Hollow Fluffy Co3O4 Cages as Efficient Electroactive Materials for Supercapacitors and Oxygen Evolution Reaction

Nano-/micrometer multiscale hierarchical structures not only provide large surface areas for surface redox reactions but also ensure efficient charge conductivity, which is of benefit for utilization in areas of electrochemical energy conversion and storage. Herein, hollow fluffy cages (HFC) of Co3O4, constructed of ultrathin nanosheets, were synthesized by the formation of Co(OH)2 hollow cages and subsequent calcination at 250 °C. The large surface area (245.5 m2 g(-1)) of HFC Co3O4 annealed at 250 °C ensures the efficient interaction between electrolytes and electroactive components and provides more active sites for the surface redox reactions. The hierarchical structures minimize amount of the grain boundaries and facilitate the charge transfer process. Thin thickness of nanosheets (2-3 nm) ensures the highly active sites for the surface redox reactions. As a consequence, HFC Co3O4 as the supercapacitor electrode exhibits a superior rate capability, shows an excellent cycliability of 10,000 cycles at 10 A g(-1), and delivers large specific capacitances of 948.9 and 536.8 F g(-1) at 1 and 40 A g(-1), respectively. Catalytic studies of HFC Co3O4 for oxygen evolution reaction display a much higher turnover frequency of 1.67×10(-2) s(-1) in pH 14.0 KOH electrolyte at 400 mV overpotential and a lower Tafel slope of 70 mV dec(-1). HFC Co3O4 with the efficient electrochemical activity and good stability can remain a promising candidate for the electrochemical energy conversion and storage.

Facile Synthesis of Ultrasmall CoS2 Nanoparticles within Thin N-Doped Porous Carbon Shell for High Performance Lithium-Ion Batteries

Cobalt sulfide (CoS2) is considered one of the most promising alternative anode materials for high-performance lithium-ion batteries (LIBs) by virtue of its remarkable electrical conductivity, high theoretical capacity, and low cost. However, it suffers from a poor cycling stability and low rate capability because of its volume expansion and dissolution of the polysulfide intermediates in the organic electrolytes during the battery charge/discharge process. In this study, a novel porous carbon/CoS2 composite is prepared by using nano metal-organic framework (MOF) templates for high-preformance LIBs. The as-made ultrasmall CoS2 (15 nm) nanoparticles in N-rich carbon exhibit promising lithium storage properties with negligible loss of capacity at high charge/discharge rate. At a current density of 100 mA g(-1), a capacity of 560 mA h g(-1) is maintained after 50 cycles. Even at a current density as high as 2500 mA g(-1), a reversible capacity of 410 mA h g(-1) is obtained. The excellent and highly stable battery performance should be attributed to the synergism of the ultrasmall CoS2 particles and the thin N-rich porous carbon shells derieved from nanosized MOF precusors.

A general method of fabricating flexible spinel-type oxide/reduced graphene oxide nanocomposite aerogels as advanced anodes for lithium-ion batteries

High-capacity anode materials for lithium ion batteries (LIBs), such as spinel-type metal oxides, generally suffer from poor Li(+) and e(-) conductivities. Their drastic crystal structure and volume changes, as a result of the conversion reaction mechanism with Li, severely impede the high-rate and cyclability performance toward their practical application. In this article, we present a general and facile approach to fabricate flexible spinel-type oxide/reduced graphene oxide (rGO) composite aerogels as binder-free anodes where the spinel nanoparticles (NPs) are integrated in an interconnected rGO network. Benefiting from the hierarchical porosity, conductive network and mechanical stability constructed by interpenetrated rGO layers, and from the pillar effect of NPs in between rGO sheets, the hybrid system synergistically enhances the intrinsic properties of each component, yet is robust and flexible. Consequently, the spinel/rGO composite aerogels demonstrate greatly enhanced rate capability and long-term stability without obvious capacity fading for 1000 cycles at high rates of up to 4.5 A g(-1) in the case of CoFe2O4. This electrode design can successfully be applied to several other spinel ferrites such as MnFe2O4, Fe3O4, NiFe2O4 or Co3O4, all of which lead to excellent electrochemical performances.

Orderly packed anodes for high-power lithium-ion batteries with super-long cycle life: rational design of MnCO3/large-area graphene composites

MnCO3 particles uniformly distributed on large-area graphene form 2D composites whose large-area character enables them to self-assemble face-to-face into orderly packed electrodes. Such regular structures form continuous and efficient transport networks, leading to outstanding lithium storage with high capacity, ultralong cycle life, and excellent rate capability--all characteristics that are required for high-power lithium-ion batteries.

Cobalt oxide-carbon nanosheet nanoarchitecture as an anode for high-performance lithium-ion battery

To improve the electrochemical performance of cobalt oxide owing to its inherent poor electrical conductivity and large volume expansion/contraction, Co3O4-carbon nanosheet hybrid nanoarchitectures were synthesized by a facile and scalable chemical process. However, it is still a challenge to control the size of Co3O4 particles down to ∼5 nm. Herein, we created nanosized cobalt oxide anchored 3D arrays of carbon nanosheets by the control of calcination condition. The uniformly dispersed Co3O4 nanocrystals on carbon nanosheets held a diameter down to ∼5 nm. When tested as anode materials for lithium-ion batteries, high lithium storage over 1200 mAh g(-1) is achieved, whereas high rate capability with capacity of about 390 mAh g(-1) at 10 A g(-1) is maintained through nanoscale diffusion distances and interconnected porous structure. After 500 cycles, the cobalt oxide-carbon nansheets hybrid display a reversible capacity of about 970 mAh g(-1) at 1 A g(-1). The synergistic effect between nanosized cobalt oxide and sheetlike interconnected carbon nanosheets lead to the greatly improved specific capacity and the initial Coulombic efficiency of the hybrids.

In situ incorporation of a S, N doped carbon/sulfur composite for lithium sulfur batteries

A novel sulfur–nitrogen co-doped carbon material (SNC), which is obtained by taking polyaniline as the nitrogen-containing carbon precursor and then incorporating sulfur atomsin situas the matrix material for lithium sulfur batteries, is investigated.

Iron triad (Fe, Co, Ni) nanomaterials: structural design, functionalization and their applications

Synthetic strategies and the functionalization of iron triad nanomaterials are summarized, applied mainly in the fields of energy and the environment.

A facile synthetic approach for SiO2@Co3O4 core–shell nanorattles with enhanced peroxidase-like activity

SiO₂@Co₃O₄ core–shell nanorattles have been successfully synthesized through a novel self-template route by the calcination of SiO₂@α-Co(OH)₂ at 500 °C and the nanorattles exhibit enhanced peroxidase-like activity.

Electrode Nanostructures in Lithium-Based Batteries

Lithium-based batteries possessing energy densities much higher than those of the conventional batteries belong to the most promising class of future energy devices. However, there are some fundamental issues related to their electrodes which are big roadblocks in their applications to electric vehicles (EVs). Nanochemistry has advantageous roles to overcome these problems by defining new nanostructures of electrode materials. This review article will highlight the challenges associated with these chemistries both to bring high performance and longevity upon considering the working principles of the various types of lithium-based (Li-ion, Li-air and Li-S) batteries. Further, the review discusses the advantages and challenges of nanomaterials in nanostructured electrodes of lithium-based batteries, concerns with lithium metal anode and the recent advancement in electrode nanostructures.