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Metal-organic framework (MOF)-derived materials are attracting considerable attention because of the moldability in compositions and structures, enabling greater performances in diverse applications. However, the nanostructural control of multicomponent MOF-based complexes remains challenging due to the complexity of reaction mechanisms. Herein, we present a surface-induced self-nucleation-growth mechanism for the zeolitic imidazolate framework (ZIF) to prepare a new type of ZIF-8@SiO2 polyhedral nanoparticles. We discover that the Zn hydroxide moieties (Zn-OH) within ZIF-8 can trigger the hydrolysis of tetraethyl orthosilicate effectively on the ZIF-8 surface precisely, avoiding the formation of free orthosilicic acid (Si(OH)4) successfully. This is a pioneering work to elucidate the importance of MOF surface properties for preparing multicomponent materials. Then, a novel well-dispersed silicon hollow nanocage (H-Si@C) modified by the carbon was prepared after removal of the ZIF-8 and magnesiothermic reduction. The as-prepared H-Si@C demonstrates an overwhelmingly high lithium storage capability and extraordinary stability in lithium-ion batteries (LIBs), particularly the impressive performances when it was matched with the LiNi0.6Co0.2Mn0.2O2 cathode in a full cell. The MOF surface-induced self-nucleation-growth strategy is useful for preparing more multifunctional materials, while the study of lithium storage performances of the H-Si@C material is practical for LIB applications.

Lithium dendrite-free deposition is crucial to stabilizing lithium batteries, where the three-dimensional (3D) metal oxide nanoarrays demonstrate an impressive capability to suppress dendrite due to the spatial effect. Herein, we introduce a new insight into the ameliorated lithium plating process on 3D nanoarrays. As a paradigm, novel 3D Cu2O and Cu nanorod arrays were in situ designed on copper foil. We find that the dendrite and electrolyte decomposition can be mitigated effectively by Cu2O nanoarrays, while the battery failed fast when the Cu nanoarrays were used. We show that Li2O (i.e., formed in the lithiation of Cu2O) is critical to stabilizing the electrolyte; otherwise, the electrolyte would be decomposed seriously. Our viewpoint is further proved when we revisit the metal (oxide) nanoarrays reported before. Thus, we discovered the importance of electrolyte stability as a precondition for nanoarrays to suppress dendrite and/or achieve a reversible lithium plating/stripping for high-performance lithium batteries.

Creating new architectures combined with super diverse materials for achieving more excellent performances has attracted great attention recently. Herein, we introduce a novel dual metal (oxide) microsphere reinforced by vertically aligned carbon nanotubes (CNTs) and covered with a titanium oxide metal ion-transfer diffusion layer. The CNTs penetrate the oxide particles and buffer structural volume change while enhancing electrical conductivity. Meanwhile, the external TiO2-C shell serves as a transport pathway for mobile metal ions (e.g., Li+) and acts as a protective layer for the inner oxides by reducing the electrolyte/metal oxide interfacial area and minimizing side reactions. The proposed design is shown to significantly improve the stability and Coulombic efficiency (CE) of metal (oxide) anodes. For example, the as-prepared MnO-CNTs@TiO2-C microsphere demonstrates an extremely high capacity of 967 mA h g-1 after 200 cycles, where a CE as high as 99% is maintained. Even at a harsh rate of 5 A g-1 (ca. 5 C), a capacity of 389 mA h g-1 can be maintained for thousands of cycles. The proposed oxide anode design was combined with a nickel-rich cathode to make a full-cell battery that works at high voltage and exhibits impressive stability and life span.

Structural design and/or carbon modification are the most important strategies to improve the performance of materials in many applications, where metal (oxide)-based anode design attracts great attention in metal ion batteries due to their high capacities. However, achieving these two goals within one-step remains challenging due to the lower cost and higher efficiency needed to satisfy the demand in practical application. Herein, we report a new approach for the crystal reconstruction of metal oxides by acetylene treatment, in which a hierarchical binary oxide decorated with carbon (i.e., Mn2Mo3O8@C) is introduced. The mechanism of constructing unique monocrystalline hexagonal nanoplates and uniform carbon coating is discussed in detail. Benefiting from the uniqueness of structure and composition, the Mn2Mo3O8@C demonstrates an extremely high lithium storage capacity of 890 mA h g-1 and good rate capacities at 20 A g-1 over 1000 cycles. In addition, the high rate capabilities and long cycle lifespan are further confirmed when the Mn2Mo3O8@C anode is matched with the nickel-rich layered oxide cathode. This study not only introduces a new binary oxide anode with high performances in lithium (ion) batteries but also presents a convenient methodology to design more advanced functional materials.

New hierarchical hollow SiO2 spheres (HHSs) decorated with metal nanoparticles (i.e., Co, Co–HHS) were designed using an in situ self-assembly approach. The Co nanoparticles were found to have a catalytic effect on (de-)lithiation of SiO2 and hence in storing lithium. Then, an extremely high capacity of 932 mA h g−1 and good cycling stability for more than 1000 cycles were demonstrated in the corresponding lithium battery. In addition, the lithium-ion full batteries of the Co–HHS versus lithium layered oxide cathode (e.g., LiNi1/3Co1/3Mn1/3O2, NCM333) were introduced and showed good performance, demonstrating the promising application of the Co–HHS, in particular for pursuing high-energy-density batteries.

A simple and low-cost polymer-aided sol–gel method was developed to prepare γ-Al2O3 protective layers for LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode materials. The selected polyvinyl alcohol polymer additive not only facilitates the formation of a uniform and thin γ-Al2O3 layer on the irregular and rough cathode particle surface to protect it from corrosion but also serves as a pore-forming agent to generate micropores in the film after sintering to allow fast transport of lithium ions, which guaranteed the excellent and stable battery performance at high working voltage. Detailed studies in the full battery mode showed that the leached corrosion species from the cathode had a more profound harmful effect to the graphite anode, which seemed to be the dominating factor that caused the battery performance decay.

Surface modification of a cathode (e.g., lithium layered oxide, NCM) has become ever more important in lithium-ion batteries, particularly for pursuing higher energy densities and safety at high voltage. This is because structural degradation of the cathode can be mitigated significantly. Herein, an organic complex is introduced for metal phosphate (e.g., AlPO4) modification through a new film-forming process in nonaqueous solution. This general strategy overcomes the challenge of nonuniform coating in current precipitation methods and then opens a new avenue toward ultrathin surface modification on a molecular scale. As one example, as-prepared AlPO4-coated NCM exhibits much improved structural and electrochemical stability; meanwhile, thermal runaway can be suppressed significantly in overcharged cells using the modified NCM, demonstrating higher and reliable safety features. The great improvements benefit from the uniform and ultrathin AlPO4 coating, which inhibits the collapse and conversion of the la...

Sulfurized polyacrylonitrile (SPAN) is the most promising cathode for next-generation lithium–sulfur (Li–S) batteries due to the much improved stability. However, the molecular structure and reaction mechanism have not yet been fully understood. Herein, we present a new take on the structure and mechanism to interpret the electrochemical behaviors. We find that the thiyl radical is generated after the cleavage of the S–S bond in molecules in the first cycle, and then a conjugative structure can be formed due to electron delocalization of the thiyl radical on the pyridine backbone. The conjugative structure can react with lithium ions through a lithium coupled electron transfer process and form an ion-coordination bond reversibly. This could be the real reason for the superior lithium storage capability, in which the lithium polysulfide may not be formed. This study refreshes current knowledge of SPAN in Li–S batteries. In addition, the structural analysis is applicable to analyze the current organic catho...

The pursuit of increased energy density and longer lifespan lithium-ion batteries (LIBs) is urgently needed to satisfy a dramatically increased demand in the energy market. Currently, metal-oxide-based anodes are being intensively studied due to their higher capacities over current graphite anodes. This work introduces a sustainable strategy to construct a metal-oxide-based anode with high capacity and an extremely long lifecycle, in which the features of bioinspired architectures and heteroatom doping can contribute greatly to increased performances. In detail, 1D tubelike metal oxide (e.g., MnO) coated on an N-doped carbon framework (i.e. MnO/N-C) has been designed by using the naturally abundant and renewable Metaplexis japonica fibers (MJFs) as the biotemplate and heteroatom source. Benefiting from the uniqueness of structure and compositions, as-prepared MnO/N-C demonstrates extremely high rate capacities of 951, 777, 497, and 435 mAh g-1 at the rates of 0.5, 2, 4, and 5 Ag-1 , respectively, with a good stability of more than 1000 cycles. It was found that the electrochemical performances are superior to most previous MnO-based anodes, in which the faster kinetics of conversion due to the advantage of the ion/electron transportation and morphological evolution has been verified. It is hoped that the concept of bioinspired architectures with heteroatom doping can be applied in wider applications for increased capability.

The high capacity of Li-rich layered cathode materials have attracted great attention for the greater energy density lithium ion (Li-ion) batteries, but the understanding of knowledge associated with electrochemical behaviours are still needed to improve their performances further. In this study, different amount of Co content is designed in Li-rich layered compounds (0.5Li2MnO3·0.5LiMn0.5-xNi0.5-xCo2xO2, 0 ≤ x ≤ 0.2), and the stepwise electrochemical activation process is applied to explore the features. We discover that the substitution of Co3+ ions can accelerate the electrochemical activation of Li2MnO3 component, and the Co-doped compound delivers much higher capacities even they suffer an apparent voltage decay comparing to the Co-free one. Besides, a fast metal ions migration exists (e.g., from the metastable tetrahedral site to the lower energy cubic site) in initial dozens of cycles (e.g., 30 cycles at 0.1C); thereafter, they likely return to the original octahedral site, as demonstrated in the voltage decay and hysteresis analysis.

Graphite anodes are not stable in most noncarbonate solvents (e.g., ether, sulfoxide, sulfone) upon Li ion intercalation, known as an urgent issue in present Li ions and next-generation Li–S and Li–O2 batteries for storage of Li ions within the anode for safety features. The solid electrolyte interphase (SEI) is commonly believed to be decisive for stabilizing the graphite anode. However, here we find that the solvation structure of the Li ions, determined by the electrolyte composition including lithium salts, solvents, and additives, plays a more dominant role than SEI in graphite anode stability. The Li ion intercalation desired for battery operation competes with the undesired Li+–solvent co-insertion, leading to graphite exfoliation. The increase in organic lithium salt LiN(SO2CF3)2 concentration or, more effectively, the addition of LiNO3 lowers the interaction strength between Li+ and solvents, suppressing the graphite exfoliation caused by Li+–solvent co-insertion. Our findings refresh the knowled...

The development of versatile strategies to create new structured materials via heteroatom doping has become a fascinating research topic owing to their fantastic properties, while the popular metal–organic framework opens promising avenues for the design of diverse architectures. Herein, an intriguing type of spherical N-doped porous carbon (i.e., N–C) particles containing numerous Co3O4 nanocrystals (i.e., Co3O4/N–C) is introduced, in which the Zn–Co based Prussian blue analogue acts as a sacrificial template and carbon source, while the volatilization of zinc and oxidation of Co produce rich pores and form highly active Co3O4 nanocrystals. The resultant Co3O4/N–C particles have an extremely high lithium storage capacity of 1255 mA h g−1 and excellent rate capability even at a current of 2000 mA g−1. Their long cycle life of over 500 cycles at 1000 mA g−1 with a high capacity of 798 mA h g−1 further demonstrates their prominent properties. Our kinetic analysis reveals that the high performances of Co3O4/N–C beyond the theoretical values mainly stem from the active Co3O4 nanocrystals, fast diffusion of lithium ions within its structure and its pseudocapacitive behaviors. Furthermore, the Co3O4/N–C particles also demonstrate impressive stability and rate capabilities in a lithium-ion battery versus a cathode of lithium layered oxide even at high voltage conditions.

Carbon modification is one of the most important strategies to boost the performance of the material in many applications, where the carbon modified metal (oxide) anode gains great attention in metal-ion batteries due to their high capacity and improved stability. However, a close-knit carbon coating through an efficient and cost-effective approach remains challenging for satisfying the demand in practical application. Herein, a new in-situ self-catalytic approach by acetylene treatment is presented, in which a tunable graphitized carbon layer can be knitted on the metal (oxide) directly to produce many kinds of core-shell structured metal (oxide)@C hybrid materials. The in-situ triggering mechanism of forming graphitized carbon is discussed in detail using the model of MnO. Then, we find that the as-prepared MnO@C exhibits an extremely high lithium storage capacity of 1077 mAh g−1 and good rate capacities at 10 A g−1 over 500 cycles. In addition, a new full battery of MnO@C || LiNi0.8Co0.1Mn0.1O2 is constructed, where the high capacity retention of 73.1% at 0.5C over 250 cycles is well confirmed. This study not only opens a new avenue to prepare more carbon decorated functional materials but also explores the potential applications of metal (oxide)-based materials for high-performance rechargeable batteries.

In this study, highly dispersive spherical Li-rich solid solution (Li1.2Mn0.54Ni0.13Co0.13O2) particles are successfully synthesized by a co-precipitation method. Then these particles are treated with aluminum nitrates ethanol solution at 80 degrees C. The treatment can extract lithium (Li2O) from the Li2MnO3 component in the composite of Li1.2Mn0.54Ni0.13Co0.13O2. Simultaneously, a thin layer of Al2O3 can be precipitated on the surface of the electrode particles via direct thermal decomposition of aluminum nitrates. After treatment, the first-cycle coulombic efficiency of the electrode increases from 72.1% to 93.6%, meanwhile it shows a superior cycling stability at 100 mAg(-1) with a discharge capacity of around 220 mAh g(-1) and retention of 92.5% after 100 cycles, which is much higher than that of the pristine electrode (83.2%). Even at a high current density of 2 A g(-1) (10 C), the discharge capacity could still achieve and well maintain as high as 140 mAh g(-1). (C) 2013 Elsevier Ltd. All rights reserved.

In this work, we have developed a new method to grow NiO nanomaterials on the surface of graphene nanosheets (GNSs). The morphologies of NiO nanomaterials grown on GNSs could be tailored by trace amounts of water introduced into the mixed solvents of CO2-expanded ethanol (CE). Small and uniform Ni-salt nanoparticles (Ni-salt-NPs) were grown on the surface of graphene oxide (GO) through the decomposition of nickel nitrate directly in CE. However, when trace amounts of water were introduced into the mixed solvents, Ni-salt nanoflakes arrays (Ni-salt-NFAs) were grown on the surface of GO with almost perpendicular direction. After thermal treatment in N2 atmosphere, these Ni-salt @GO composites were converted to NiO@GNSs composites. The forming mechanisms of the NiO-NPs@GNSs and NiO-NFAs@GNSs were discussed by series comparative experiments. The presence of the trace amounts of water affected the chemical composition and structure of the precursors formed in CE and the growth behaviors on the surface of GNSs. When used as anode materials for lithium-ion batteries, the NiO-NPs@GNSs composite exhibited better cycle and rate performance compared with the NiO-NFAs@GNSs.

Li(Mn 1/3 Ni 1/3 Co 1/3 )O 2 cathode materials were fabricated by a hydroxide precursor method. Al 2 O 3 was coated on the surface of the Li(Mn 1/3 Ni 1/3 Co 1/3 )O 2 through a simple and effective one-step electrostatic self-assembly method. In the coating process, a NHCO 3 -H 2 CO 3 buffer was formed spontaneously when CO 2 was introduced into the NaAlO 2 solution. Compared with bare Li(Mn 1/3 M 1/3 Co 1/3 )O 2 , the surface-modified samples exhibited better cycling performance, rate capability and rate capability retention. The Al 2 O 3 -coated Li(Mn 1/3 Ni 1/3 Co 1/3 )O 2 electrodes delivered a discharge capacity of about 115 mAh·g −1 at 2 A·g −1 , but only 84 mAh·g −1 for the bare one. The capacity retention of the Al 2 O 3 -coated Li(Mn 1/3 Ni 1/3 Co 1/3 )O 2 was 90.7% after 50 cycles, about 30% higher than that of the pristine one.

In this work, we report a facile method for the synthesis of a Co3O4–functionalized carbon nanotube (Co3O4–f-CNT) composite via the growth of Co3O4 nanoparticles on the surface of functionalized carbon nanotubes (f-CNTs) by thermal decomposition of cobalt nitrate hexahydrate in ethanol. The composite consists of 13% carbon nanotubes and 87% Co3O4 nanoparticles by weight, and all the Co3O4 particles grew compactly along the carbon nanotube axis with a highly uniform dispersion. When used as an anode material for rechargeable lithium ion batteries, the composite manifested high capacities and excellent cycling performance at high and low current rates. The discharge capacity was 719 mA h g−1 at the 2nd cycle and 776 mA h g−1 at the 100th cycle. Even at a current density of 1 A g−1, the specific capacity still remained at about 600 mA h g−1. This superior electrochemical performance was attributed to the unique nanostructure of the composite. Because almost all of the Co3O4 nanoparticles were immobilized on the surface of f-CNTs, physical aggregation of nanoparticles was avoided during the charge–discharge processes. Furthermore, the good mechanical flexibility of f-CNTs can readily alleviate the massive volume expansion/shrinkage associated with a conversion reaction electrode. Finally, f-CNTs are highly conductive matrices for electrons due to their high conductivity, which can shorten the diffusion path for electrons.

New dense hollow porous (DHP) metal oxide nanoparticles that are smaller than 100 nm and composed of Co3O4, FeOx, NiO and MnOx were prepared by densely assembling metal oxide nanocrystals based on the hard-template method using a carbon colloid as a sacrificial core. These nanoparticles are quite different from the traditional particles as their hollow interior originates from the stacking of nanocrystals rather than a spherical shell. The DHP nanoparticles preserve the intriguing properties of nanocrystals and possess desirable surface area and pore volume that enhance the active surface, which ultimately benefits applications such as lithium-ion batteries. The DHP Co3O4 nanoparticles demonstrated an enhanced capacity of 1168 mA h g(-1) at 100 mA g(-1)vs. 590 mA h g(-1) of powders and stable cycling performance greater than 250 cycles when used as an anode material. Most importantly, the electrochemical performance of DHP Co3O4 nanoparticles in a lithium-O2 battery was also investigated for the first time. A low charge potential of ∼4.0 V, a high discharge voltage near 2.74 V and a long cycle ability greater than 100 cycles at a delivered capacity of 2000 mA h g(-1) (current density, 200 mA g(-1)) were observed. The performances were considerably improved compared to recent results of mesoporous Co3O4, Co3O4 nanoparticles and a composite of Co3O4/RGO and Co3O4/Pd. Therefore, it would be promising to investigate such properties of DHP nanoparticles or other hollow metal (oxide) particles for the popular lithium-air battery.

SnS2/graphene nanosheets (SnS2/GNS) composites were synthesized by a one-step hydrothermal method. The composites exhibit remarkably improved Li-storage ability with a good cycling life and high capability superior to that of the pure SnS2 counterpart due to a synergic effect between the graphene and SnS2 nanosheets.