One-step solvothermal synthesis of Sn nanoparticles dispersed in ternary manganese-nickel-cobalt carbonate as superior anode materials for lithium ion batteries

Synthesis of Li4 Ti5 O12 with Tunable Morphology Using l-Cysteine and Its Enhanced Lithium Storage Properties

Nitrogen and sulfur co-doped carbon-coated Li₄ Ti₅ O₁₂ (denoted as LTO/NSC) was developed to enhance the electrochemical performance of LTO material. l-Cysteine served as both the carbon source and the heteroatom doping source. The morphology of LTO was tuned by Ti-C bond formation during carbonation process, accompanied by a change in the original orientation growth of the LTO lattice plane. Consequently, LTO transformed from nanosheets to nanoparticles. SEM data proved that the structure of LTO/NSC nanoparticles was more stable than that of LTO nanosheets after hundreds of charge/discharge process. The N,S co-doped carbon layer can moderate particle aggregation and may help to shorten the electron transport length and enhance lithium storage capacity. The structural superiority and the N,S co-doped carbon layer endows LTO/NSC particles with high reversible specific capacity (183 mA h g^-1 at 0.1 C), significantly enhanced rate capability (122 mA h g^-1 at 10 C) and excellent cycling stability (capacity retention of 96.3 % after 200 cycles) relative to these features of LTO nanosheets. Thus, LTO/NSC is a promising anode material for high-performance lithium ion batteries.

Sn-encapsulated N-doped porous carbon fibers for enhancing lithium-ion battery performance

Tin (Sn) has wide prospects in applications as an anode electrode material for Li-ion batteries, due to its high theoretical specific capacity. However, the large volume expansion of Sn during the charge-discharge process causes a performance reduction of lithium-ion batteries (LIBs). Here, Sn encapsulated N-doped porous carbon fibers (Sn/NPCFs) were synthesized through an electrospinning method with a pyrolysis process. This structure was beneficial for the lithium ion/electron diffusion and buffered the large volume change. By adjusting the amount of Sn, the hybrid carbon fibers with different Sn/carbon ratios could be prepared, and the morphology, composition and properties of the Sn/NPCFs were characterized systematically. The results indicated that the Sn/NPCFs with a Sn-precursor/polymer weight ratio at 0.5 : 1 showed the best cycling stability and specific capacity, preserving the specific capacity of 400 mA h g-1 at the current density of 500 mA g-1 even after 100 cycles.

Hierarchical Sandwich-Like Structure of Ultrafine N-Rich Porous Carbon Nanospheres Grown on Graphene Sheets as Superior Lithium-Ion Battery Anodes

A sandwich-like, graphene-based porous nitrogen-doped carbon (PNCs@Gr) has been prepared through facile pyrolysis of zeolitic imidazolate framework nanoparticles in situ grown on graphene oxide (GO) (ZIF-8@GO). Such sandwich-like nanostructure can be used as anode material in lithium ion batteries, exhibiting remarkable capacities, outstanding rate capability, and cycling performances that are some of the best results among carbonaceous electrode materials and exceed most metal oxide-based anode materials derived from metal orgainc frameworks (MOFs). Apart from a high initial capacity of 1378 mAh g(-1) at 100 mA g(-1), this PNCs@Gr electrode can be cycled at high specific currents of 500 and 1000 mA g(-1) with very stable reversible capacities of 1070 and 948 mAh g(-1) to 100 and 200 cycles, respectively. At a higher specific current of 5000 mA g(-1), the electrode still delivers a reversible capacity of over 530 mAh g(-1) after 400 cycles, showing a capacity retention of as high as 84.4%. Such an impressive electrochemical performance is ascribed to the ideal combination of hierarchically porous structure, a highly conductive graphene platform, and high-level nitrogen doping in the sandwich-like PNCs@Gr electrode obtained via in situ synthesis.

Unveiling the adsorption mechanism of zeolitic imidazolate framework-8 with high efficiency for removal of copper ions from aqueous solutions

Here we experimentally unveil the adsorption mechanism of Cu²⁺ by using zeolitic imidazolate framework-8 (ZIF-8) for its application in heavy metal wastewater treatment.

Hierarchical Graphene-Encapsulated Hollow SnO2@SnS2 Nanostructures with Enhanced Lithium Storage Capability

Complex hierarchical structures have received tremendous attention due to their superior properties over their constitute components. In this study, hierarchical graphene-encapsulated hollow SnO2@SnS2 nanostructures are successfully prepared by in situ sulfuration on the backbones of hollow SnO2 spheres via a simple hydrothermal method followed by a solvothermal surface modification. The as-prepared hierarchical SnO2@SnS2@rGO nanocomposite can be used as anode material in lithium ion batteries, exhibiting excellent cyclability with a capacity of 583 mAh/g after 100 electrochemical cycles at a specific current of 200 mA/g. This material shows a very low capacity fading of only 0.273% per cycle from the second to the 100th cycle, lower than the capacity degradation of bare SnO2 hollow spheres (0.830%) and single SnS2 nanosheets (0.393%). Even after being cycled at a range of specific currents varied from 100 mA/g to 2000 mA/g, hierarchical SnO2@SnS2@rGO nanocomposites maintain a reversible capacity of 664 mAh/g, which is much higher than single SnS2 nanosheets (374 mAh/g) and bare SnO2 hollow spheres (177 mAh/g). Such significantly improved electrochemical performance can be attributed to the unique hierarchical hollow structure, which not only effectively alleviates the stress resulting from the lithiation/delithiation process and maintaining structural stability during cycling but also reduces aggregation and facilitates ion transport. This work thus demonstrates the great potential of hierarchical SnO2@SnS2@rGO nanocomposites for applications as a high-performance anode material in next-generation lithium ion battery technology.