Transition Metal Sulfides Based on Graphene for Electrochemical Energy Storage

Metal sulfide hollow nanostructures (MSHNs) have received intensive attention as electrode materials for electrical energy storage (EES) systems due to their unique structural features and rich chemistry. Here, we summarize recent research progress in the rational design and synthesis of various metal sulfide hollow micro-/nanostructures with controlled shape, composition and structural complexity, and their applications to lithium ion batteries (LIBs) and hybrid supercapacitors (HSCs). The current understanding of hollow structure control, including single-shelled, yolk-shelled, multi-shelled MSHNs, and their hybrid micro-/nanostructures with carbon (amorphous carbon nanocoating, graphene and hollow carbon), is focused on. The importance of proper structural and compositional control on the enhanced electrochemical properties of MSHNs is emphasized. A relationship between structural and compositional engineering with improved electrochemical activity of MSHNs is sought, in order to shed some light on future electrode design trends for next-generation EES technologies.

Metal Sulfide Hollow Nanostructures for Electrochemical Energy Storage

Metal sulfides are promising anode materials for sodium-ion batteries due to their large specific capacities. The practical applications of metal sulfides in sodium-ion batteries, however, are still limited due to their large volume expansion, poor cycling stability, and sluggish electrode kinetics. In this work, a two-dimensional heterostructure of CoSx (CoS and Co9S8) quantum dots embedded N/S-doped carbon nanosheets (CoSx@NSC) is prepared by a sol–gel method. The CoSx quantum dots are in situ formed within ultrafine carbon nanosheets without further sulfidation, thus resulting in ultrafine CoSx particle size and embedded heterostructure. Meanwhile, enriched N and S codoping in the carbon nanosheets greatly enhances the electrical conductivity for the conductive matrix and creates more active sites for sodium storage. As a result, the hybrid CoSx@NSC electrode shows excellent rate capability (600 mAh g–1 at 0.2 A g–1 and 500 mAh g–1 at 10 A g–1) and outstanding cycling stability (87% capacity retention ...

Cobalt Sulfide Quantum Dot Embedded N/S-Doped Carbon Nanosheets with Superior Reversibility and Rate Capability for Sodium-Ion Batteries

Metal-organic frameworks (MOFs) have been intensively used as the templates/precursors to synthesize complex hollow structures for various energy-related applications. Herein we report a facile two-step diffusion-controlled strategy to generate novel MOFs derived hierarchical hollow prisms composed of Nanosized CoS2 bubble-like subunits. Uniform zeolitic imidazolate framework-67 (ZIF-67) hollow prisms assembled by interconnected nanopolyhedra are first synthesized via a transformation process. Afterwards, these ZIF-67 building blocks are converted into CoS2 bubble-like hollow particles to form the complex hollow prisms through a sulfidation reaction with an additional annealing treatment. When evaluated as an electrode material for lithium-ion batteries, the as-obtained CoS2 nanobubble hollow prisms show remarkable electrochemical performance with good rate capability and long cycle life.

Formation of CoS2 Nanobubble Hollow Prisms for Highly Reversible Lithium Storage

Energy storage and conversion technologies are vital to the efficient utilization of sustainable renewable energy sources. Rechargeable lithium-ion batteries (LIBs) and the emerging sodium-ion batteries (SIBs) are considered as two of the most promising energy storage devices, and electrocatalysis processes play critical roles in energy conversion techniques that achieve mutual transformation between renewable electricity and chemical energies. It has been demonstrated that nanostructured metal chalcogenides including metal sulfides and metal selenides show great potential for efficient energy storage and conversion due to their unique physicochemical properties. In this feature article, the recent research progress on nanostructured metal sulfides and metal selenides for application in SIBs/LIBs and hydrogen/oxygen electrocatalysis (hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction) is summarized and discussed. The corresponding electrochemical mechanisms, critical issues, and effective strategies towards performance improvement are presented. Finally, the remaining challenges and perspectives for the future development of metal chalcogenides in the energy research field are proposed.

Nanostructured Metal Chalcogenides for Energy Storage and Electrocatalysis

Hollow nanospheres of mesoporous Co9S8 as a high-capacity and long-life anode for advanced lithium ion batteries

A one-dimensional MWCNT@a-C@Co9S8 nanocomposite has been prepared via a facile solvothermal reaction followed by a calcination process. The amorphous carbon layer between Co9S8 and MWCNT acts as a linker to increase the loading of sulfides on MWCNT. When evaluated as anode materials for lithium ion batteries, the MWCNT@a-C@Co9S8 nanocomposite shows the advantages of high capacity and long life, superior to Co9S8 nanoparticles and MWCNT@Co9S8 nanocomposites. The reversible capacity could be retained at 662 mA h g−1 after 120 cycles at 1 A g−1. The efficient synthesis and excellent performances of this nanocomposite offer numerous opportunities for other sulfides as a new anode for lithium ion batteries.

Dong Yan

Papers

Hollow nanospheres of mesoporous Co9S8 as a high-capacity and long-life anode for advanced lithium ion batteries

Multiwalled carbon nanotube@a-C@Co9S8 nanocomposites: a high-capacity and long-life anode material for advanced lithium ion batteries