Evolution of Reduced Graphene Oxide-SnS2 Hybrid Nanoparticle Electrodes in Li-Ion Batteries

Synthesis and Applications of Dimensional SnS2 and SnS2/Carbon Nanomaterials

Dimensional nanomaterials can offer enhanced application properties benefiting from their sizes and morphological orientations. Tin disulfide (SnS₂) and carbon are typical sources of dimensional nanomaterials. SnS₂ is a semiconductor with visible light adsorption properties and has shown high energy density and long cycle life in energy storage processes. The integration of SnS₂ and carbon materials has shown enhanced visible light absorption and electron transmission efficiency. This helps to alleviate the volume expansion of SnS₂ which is a limitation during energy storage processes and provides a favorable bandgap in photocatalytic degradation. Several innovative approaches have been geared toward controlling the size, shape, and hybridization of SnS₂/Carbon composite nanostructures. However, dimensional nanomaterials of SnS₂ and SnS₂/Carbon have rarely been discussed. This review summarizes the synthesis methods of zero-, one-, two-, and three-dimensional SnS₂ and SnS₂/Carbon composite nanomaterials through wet and solid-state synthesis strategies. Moreover, the unique properties that promote their advances in photocatalysis and energy conversion and storage are discussed. Finally, some remarks and perspectives on the challenges and opportunities for exploring advanced SnS₂/Carbon nanomaterials are presented.

Sheet-Like Stacking SnS2/rGO Heterostructures as Ultrastable Anodes for Lithium-Ion Batteries

SnS₂-based materials have attracted considerable attention in energy storage and conversion owing to their high lithium activity and theoretical capacity. However, the practical application is severely limited by the low coulombic efficiency and short cycle life due to irreversible side reactions, low conductivity, and serious pulverization in the discharge/charge process. In this study, sheet-like stacking SnS₂/reduced graphene oxide (rGO) heterostructures were developed using a facile solvothermal method. It was found that the composites between SnS₂ nanoplates and rGO nanosheets are closely coupled through van der Waals interactions, providing efficient electron/ion paths to ensure high electrical conductivity and sufficient buffer space to alleviate volume expansion. Therefore, the SnS₂/rGO heterostructure anode can obtain a high capacity of 840 mA h g^-1 after 120 cycles at a current density of 200 mA g^-1 and maintain a capacity of 450 mA h g^-1 after 1000 cycles at 1000 mA g^-1. In situ X-ray diffraction tests showed that SnS₂/rGO undergoes typical initial intercalation, conversion, and subsequent alloying reactions during the first discharge, and most of the reactions are dealloying/alloying in the subsequent cycles. The galvanostatic intermittent titration technique showed that the diffusion of lithium ions in the SnS₂/rGO heterostructures is faster in the intercalation and conversion reactions than in the alloying reactions. These observations help to clarify the reaction mechanism and ion diffusion behavior in the SnS₂ anode materials, thus providing valuable insights for improving the energy efficiency of lithium-ion batteries.

Anisotropic Carbon Nanotube Structures with High Aspect Ratio Nanopores for Li-Ion Battery Anodes

Technological advances in membrane technology, catalysis, and electrochemical energy storage require the fabrication of controlled pore structures at ever smaller length scales. It is therefore important to develop processes allowing for the fabrication of materials with controlled submicron porous structures. We propose a combination of colloidal lithography and chemical vapor deposition of carbon nanotubes to create continuous straight pores with diameters down to 100 nm in structures with thicknesses of more than 300 μm. These structures offer unique features, including continuous and parallel pores with aspect ratios in excess of 3000, a low pore tortuosity, good electrical conductivity, and electrochemical stability. We demonstrate that these structures can be used in Li-ion batteries by coating the carbon nanotubes with Si as an active anode material.

A Review on Applications of Layered Phosphorus in Energy Storage

Phosphorus in energy storage has received widespread attention in recent years. Both the high specific capacity and ion mobility of phosphorus may lead to a breakthrough in energy storage materials. Black phosphorus, an allotrope of phosphorus, has a sheet-like structure similar to graphite. In this review, we describe the structure and properties of black phosphorus and characteristics of the conductive electrode material, including theoretical calculation and analysis. The research progress in various ion batteries, including lithium-sulfur batteries, lithium–air batteries, and supercapacitors, is summarized according to the introduction of black phosphorus materials in different electrochemical applications. Among them, with the introduction of black phosphorus in lithium-ion batteries and sodium-ion batteries, the research on the properties of black phosphorus and carbon composite is introduced. Based on the summary, the future development trend and potential of black phosphorus materials in the field of electrochemistry are analyzed.

Hydrothermal Coating of Patterned Carbon Nanotube Forest for Structured Lithium-Ion Battery Electrodes

Controlling the arrangement and interface of nanoparticles is essential to achieve good transfer of charge, heat, or mechanical load. This is particularly challenging in systems requiring hybrid nanoparticle mixtures such as combinations of organic and inorganic materials. This work presents a process to coat vertically aligned carbon nanotube (CNT) forests with metal oxide nanoparticles using microwave-assisted hydrothermal synthesis. Hydrothermal processes normally damage delicate CNT forests, which is addressed here by a combination of lithographic patterning, transfer printing, and reduction of the synthesis time. This process is applied for the fabrication of structured Li-ion battery (LIB) electrodes where the aligned CNTs provide a straight electron transport path through the electrode and the hydrothermal coating process is used to coat the CNTs with conversion anode materials for LIBs. These nanoparticles are anchored on the surface of the CNTs and batteries fabricated following this process show a fourfold longer cyclability. Finally, this process is used to create thick electrodes (350 µm) with a gravimetric capacity of over 900 mAh g^-1 .

In situ carbon encapsulation of vertical MoS2 arrays with SnO2 for durable high rate lithium storage: dominant pseudocapacitive behavior

Improving the conductivity and charge transfer kinetics is favourable for innovation of sustainable energy devices such as metal oxide/sulfide-based electrodes. Herein, with an intercalation pseudocapacitance effect, an in situ polymerization-carbonization process for novel carbon-sealed vertical MoS₂-SnO₂ anchored on graphene aerogel (C@MoS₂-SnO₂@Gr) has enabled excellent rate performance and durability of the anode of lithium ion batteries to be achieved. The integrated carbon layer and graphene matrix provide a bicontinuous conductive network for efficient electron/ion diffusion pathways. The charge transfer kinetics could be enhanced by the synergistic effects between vertical MoS₂ nanosheets and well-dispersed SnO₂ particles. Based on the crystal surface matching, the ameliorated electric contact between MoS₂ and SnO₂ can promote the extraction of Li⁺ from Li₂O and restrain the serious aggregation of Li_xSn. As a result, the improved reversibility leads to a higher initial coulombic efficiency (ICE) of 80% (0.1 A g^-1 current density) compared to that of other materials. In particular, with the dominating surface capacitive process, the C@MoS₂-SnO₂@Gr electrode delivers a stable capacity of 680 mA h g^-1 at 2.5 A g^-1 for 2000 cycles. Quantitative insight into the origin of the boosted kinetics demonstrated the high pseudocapacitance contribution (above 90%) which leads to the durable high rate Li ion storage.

Hierarchical MoO3/SnS2 core–shell nanowires with enhanced electrochemical performance for lithium-ion batteries

The formation of hierarchical MoO₃/SnS₂ core–shell nanowires can effectively suppress the rapid dissociation of SnS₂ nanosheets via interfacial interactions, which is responsible for the improved electrochemical performance.