Tin Nanoparticles Encapsulated Carbon Nanoboxes as High-Performance Anode for Lithium-Ion Batteries

Interfacial Modulation of a Self-Sacrificial Synthesized SnO2@Sn Core-Shell Heterostructure Anode toward High-Capacity Reversible Li+ Storage

Sn-based anodes are promising high-capacity anode materials for low-cost lithium ion batteries. Unfortunately, their development is generally restricted by rapid capacity fading resulting from large volume expansion and the corresponding structural failure of the solid electrolyte interphase (SEI) during the lithiation/delithiation process. Herein, heterostructural core-shell SnO2-layer-wrapped Sn nanoparticles embedded in a porous conductive nitrogen-doped carbon (SOWSH@PCNC) are proposed. In this design, the self-sacrificial Zn template from the precursors is used as the pore former, and the LiF-Li3N-rich SEI modulation layer is motivated to average uniform Li+ flux against local excessive lithiation. Meanwhile, both the chemically active nitrogen sites and the heterojunction interfaces within SnO2@Sn are implanted as electronic/ionic promoters to facilitate fast reaction kinetics. Consequently, the as-converted SOWSH@PCNC electrodes demonstrate a significantly boosted Li+ capacity of 961 mA h g-1 at 200 mA g-1 and excellent cycling stability with a low capacity decaying rate of 0.071% after 400 cycles at 500 mA g-1, suggesting their great promise as an anode material in high-performance lithium ion batteries.

MnSn2and MnSn2-TiO2nanostructured anode materials for lithium-ion batteries

The high theoretical lithium storage capacity of Sn makes it an enticing anode material for Li-ion batteries (LIBs); however, its large volumetric expansion during Li-Sn alloying must be addressed. Combining Sn with metals that are electrochemically inactive to lithium leads to intermetallics that can alleviate volumetric expansion issues and still enable high capacity. Here, we present the cycling behavior of a nanostructured MnSn₂intermetallic used in LIBs. Nanostructured MnSn₂is synthesized by reducing Sn and Mn salts using a hot injection method. The resulting MnSn₂is characterized by x-ray diffraction and transmission electron microscopy and then is investigated as an anode for LIBs. The MnSn₂electrode delivers a stable capacity of 514 mAh g^-1after 100 cycles at a C/10 current rate with a Coulombic efficiency >99%. Unlike other Sn-intermetallic anodes, an activation overpotential peak near 0.9 V versus Li is present from the second lithiation and in subsequent cycles. We hypothesize that this effect is likely due to electrolyte reactions with segregated Mn from MnSn₂. To prevent these undesirable Mn reactions with the electrolyte, a 5 nm TiO₂protection layer is applied onto the MnSn₂electrode surface via atomic layer deposition. The TiO₂-coated MnSn₂electrodes do not exhibit the activation overpotential peak. The protection layer also increases the capacity to 612 mAh g^-1after 100 cycles at a C/10 current rate with a Coulombic efficiency >99%. This higher capacity is achieved by suppressing the parasitic reaction of Mn with the electrolyte, as is supported by x-ray photoelectron spectroscopy analysis.

Structural Engineering of SnS2 Encapsulated in Carbon Nanoboxes for High-Performance Sodium/Potassium-Ion Batteries Anodes

Conversion-alloying type anode materials like metal sulfides draw great attention due to their considerable theoretical capacity for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). However, poor conductivity, severe volume change, and harmful aggregation of the material during charge/discharge lead to unsatisfying electrochemical performance. Herein, a facile and green strategy for yolk-shell structure based on the principle of metal evaporation is proposed. SnS₂ nanoparticle is encapsulated in nitrogen-doped hollow carbon nanobox (SnS₂ @C). The carbon nanoboxes accommodate the volume change and aggregation of SnS₂ during cycling, and form 3D continuous conductive carbon matrix by close contact. The well-designed structure benefits greatly in conductivity and structural stability of the material. As expected, SnS₂ @C exhibits considerable capacity, superior cycling stability, and excellent rate capability in both SIBs and PIBs. Additionally, in situ Raman technology is unprecedentedly conducted to investigate the phase evolution of polysulfides. This work provides an avenue for facilely constructing stable and high-capacity metal dichalcogenide based anodes materials with optimized structure engineering. The proposed in-depth electrochemical measurements coupled with in situ and ex situ characterizations will provide fundamental understandings for the storage mechanism of metal dichalcogenides.

Cytotoxicity, mutagenicity, oxidative stress and mitochondrial impairment in human hepatoma (HepG2) cells exposed to copper oxide, copper-iron oxide and carbon nanoparticles

The increasing application of nanomaterials in various fields such as drug delivery, cosmetics, disease detection, cancer treatment, food preservation etc. has resulted in high levels of engineered nanoparticles in the environment, thus leading to higher possibility of direct or indirect interactions between these particles and biological systems. In this study, the toxic effects of three commercially available nanomaterials; copper oxide nanoparticles, copper-iron oxide nanopowders and carbon nanopowders were determined in the human hepatoma HepG2 cells using various toxicological assays which are indicative of cytotoxicity (MTT and neutral red assays), mutagenicity (cytokinesis-block micronucleus assay), oxidative stress (total reactive oxygen species and superoxide anion production) and mitochondrial impairment (cellular oxygen consumption). There was increased cytotoxicity, mutagenicity, and mitochondrial impairment in the cells treated with higher concentrations of the nanomaterials, especially the copper oxide nanoparticles. The fold production of reactive oxygen species was similar at the concentrations tested in this study but longer exposure duration resulted in production of more superoxide anions. The results of this study showed that copper oxide nanoparticles are highly toxic to the human HepG2 cells, thus implying that the liver is a target organ in human for copper oxide nanoparticles toxicity.

Investigation of the photocatalytic potential enhancement of silica monolith decorated tin oxide nanoparticles through experimental and theoretical studies

Photodegradation of organic pollutants is considered to be the most suitable and cheaper technique to counter decontamination issues.