Search

Novel CoNi binary metal oxide superstructures assembled with cross-stacked nanosheets (Co3O4/NiO/NC) have been successfully prepared by two-step thermal annealing process with CoNi-based and cyano-bridged coordination polymer (CoNiCP). Ascribing to the super decussate structure and as-obtained three-dimensional carbon conductive network, the obtained material exhibited excellent lithium-ion storage capacity including superior cycling stability and rate performance through facilitating the easy electron/ion transport. For example, CoNi binary metal oxide superstructures exhibit an excellent rate capacity of 493 mA h g−1 at 5.0 A g−1 and a long-lifetime cycling performance of 1390 mA h g−1 after 100 cycles at 0.2 A g−1. This strategy may pave a way for designing and preparing binary metal oxide superstructures materials with excellent electrochemical performance for lithium-ion battery by using coordination polymers as the sacrificial template.

A appropriate size with three-dimension (3D) channels for lithium diffusion plays an important role in constructing high-performing LiNi0.5Mn1.5O4 (LNMO) cathode materials, as it can not only reduce the transport path of lithium ions and electrons, but also reduce the side effects and withstand the structural strain in the process of repetitive Li+ intercalation/deintercalation. In this work, an efficient method for designing the hollow LNMO microsphere with 3D channels structure by using polyethylene oxide (PEO) as soft template agent assisted solvothermal method is proposed. Experimental results indicate that PEO can make the reagents mingle evenly and nucleate slowly in the solvothermal process, thus obtaining a homogeneous distribution of carbonate precursors. In the final LNMO products, the hollow 3D channels structure obtained by the decomposition of PEO and carbonate precursor in the calcination can provide abundant electroactive zones and electron/ion transport paths during the charge/discharge process, which benefits to improve the cycling performance and rate capability. The LNMO prepared by adding 1 g PEO possesses the most outstanding electrochemical performance, which presented an excellent discharge capacity of 143.1 mAh g−1 at 0.1 C and with a capacity retention of 92.2% after 100 cycles at 1 C. The superior performance attributed to the 3D channels structure of hollow microspheres, which provide uninterrupted conductive systems and therefore achieve the stable transfer for electron/ion.

Molybdenum phosphide (MoP) has attracted extensive attention as promising anode candidates for lithium-ion batteries owing to its high specific capacity, low potential range and low polarization. However, severe volume changes and intrinsic low conductivity are major challenges for further application of MoP electrode materials. In this work, a coral-like MoP microsphere encapsulated by N-doped carbon (MoP@NDC) was successfully prepared through annealing the precursor derived from self-polymerization of dopamine with phosphomolybdic acid. The introduction of carbon framework not only serves as matrix to confine MoP nanocrystals from aggregations, but also improves the electrochemical conductivity and facilitates lithium ion or electron transport on the surface of MoP. Such hierarchical structure delivered high discharge capacity of 495 mAh g−1 after 300 cycles with 90.1% capacity retention, which could be attributed to the synergistic effects of MoP nanoparticles and conductive carbon network. This design strategy shows MoP@NDC electrode with applicable application as anode in lithium-ion battery.

Rhenium disulfide (ReS2) is a promising 2D-layered anode material for rechargeable batteries. However, this material suffers from severe agglomeration and volume expansion during ions insertion/extraction, leading to inferior battery performance. Building 3D hierarchical structure is an effective strategy to overcome these problems and simultaneously manifest synergistic effects. Herein, a one-pot hydrothermal method is introduced to construct N-doped carbon confined ReS2 ultrathin nanosheets anchored on few-layered Ti3C2Tx MXene substrate (MXene@ReS2@C). The MXene flakes can effectively reduce agglomeration of ReS2 nanosheets during charge/discharge process and generate chemical interaction with ReS2 nanosheets, thereby promoting charge transfer kinetic of hierarchical composite. Carbon incorporation not only stabilizes MXene from successive oxidation during hydrothermal procedure but also alleviates volume expansion of ReS2, ensuring cycling durability of electrode. When used as anode material of SIBs, this hierarchical MXene@ReS2@C hybrid with strong interfacial interactions demonstrates improved electrochemical performances with satisfying rate capability (138 mAh g-1 at 5.0 A g-1) and cycling stability (202 mAh g-1 at 2.0 A g-1 after 200 cycles). This work provides a new scope of synthesizing MXene-based transition metal sulfide composite for practical application in sodium ion batteries.

NaCl-type Ni-Co oxide solid solution is expected to be a promising alternative anode material for lithium-ion batteries. However, the synthesis of solid solutions with well-defined morphology and homogeneity is still challenging. Based on a novel NixCo1−x(OH)(OCH3)@polydopamine intermediate and its topotactic thermolysis, a unique synthetic route towards NixCo1−xO solid solution (0

In this paper, 1T’-ReS2@FeS2@NC heterostructure was successfully prepared by growing ReS2 nanosheet arrays on porous FeS2 nano-spindle by using metal-organic framework (MIL-88) as precursor. The heterostructure with external nanosheet array structure ensures sufficient contact between the electrolyte solution and the electrode material by shortening the ion transfer path. When 1T’-ReS2@FeS2@NC heterostructure was used as anode material of sodium ion battery, it delivered excellent rate performance and cycling stability, reaching a high specific capacity of 729 mAh g−1 at a current density of 0.1 A g−1. Meanwhile, the results of galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) tests can indicate that the heterostructure greatly enhances the Na+ diffusion kinetics through combining of three-dimensional porous FeS2 nano-spindle and two-dimensional nanosheet arrays. It is proved that 1T’-ReS2@FeS2@NC heterostructure is a promising anode material for sodium-ion batteries.

We establish a unique bottom-up route to fabricate well-defined two-dimensional (2D) carbon coated CoS2 (CoS2@C) nanoplatelets as anode materials for highly reversible lithium ion batteries (LIBs). A novel platelet-like Co(OH)(OCH3) precursor is firstly prepared with a solvothermal method, and subsequently immersed in dopamine aqueous solution to generate a Co(OH)(OCH3)/polydopamine composite. Finally, 2D CoS2@C nanoplatelets are obtained through the topotactic sulfurization of Co(OH)(OCH3) into CoS2 nanoplatelets and the simultaneous carbonization of polydopamine coating by thermal annealing at 450 °C. The 2D porous CoS2 nanoplatelet cores offer abundant active sites for Li storage and shorten transport lengths of lithium ions and electrons, while the amorphous carbon shells increase the electronic conductivity, retard the dissolution of intermediate reactants in the electrolyte, and accommodate volume change during the charge-discharge process. As a result, the hierarchical CoS2@C nanoplatelets deliver a high reversible specific capacity of 1100 mAh g−1 at 0.2 A g−1 and maintain 740 mAh g−1 after 400 cycles at 1.0 A g−1. Moreover, the rate capability is also significantly improved relative to the bare CoS2. This work offers a new strategy for the synthesis of 2D transition metal sulfide nanoplatelets and their rational design to achieve desirable electrochemical performances for LIBs.