Silver Nanocoating of LiNi0.8Co0.1Mn0.1O2 Cathode Material for Lithium-Ion Batteries

Surface coating has become an effective approach to improve the electrochemical performance of Ni-rich cathode materials. In this study, we investigated the nature of an Ag coating layer and its effect on electrochemical properties of the LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode material, which was synthesized using 3 mol.% of silver nanoparticles by a facile, cost-effective, scalable and convenient method. We conducted structural analyses using X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy, which revealed that the Ag nanoparticle coating did not affect the layered structure of NCM811. The Ag-coated sample had less cation mixing compared to the pristine NMC811, which could be attributed to the surface protection of Ag coating from air contamination. The Ag-coated NCM811 exhibited better kinetics than the pristine one, which is attributed to the higher electronic conductivity and better layered structure provided by the Ag nanoparticle coating. The Ag-coated NCM811 delivered a discharge capacity of 185 mAh·g^-1 at the first cycle and 120 mAh·g^-1 at the 100th cycle, respectively, which is better than the pristine NMC811.

Effect of Cationic (Na+) and Anionic (F-) Co-Doping on the Structural and Electrochemical Properties of LiNi1/3Mn1/3Co1/3O2 Cathode Material for Lithium-Ion Batteries

Elemental doping for substituting lithium or oxygen sites has become a simple and effective technique to improve the electrochemical performance of layered cathode materials. Compared with single-element doping, this work presents an unprecedented contribution to the study of the effect of Na⁺/F⁻ co-doping on the structure and electrochemical performance of LiNi_1/3Mn_1/3Co_1/3O₂. The co-doped Li_1-zNa_zNi_1/3Mn_1/3Co_1/3O_2-zF_z (z = 0.025) and pristine LiNi_1/3Co_1/3Mn_1/3O₂ materials were synthesized via the sol–gel method using EDTA as a chelating agent. Structural analyses, carried out by X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy, revealed that the Na⁺ and F⁻ dopants were successfully incorporated into the Li and O sites, respectively. The co-doping resulted in larger Li-slab spacing, a lower degree of cation mixing, and the stabilization of the surface structure, which substantially enhanced the cycling stability and rate capability of the cathode material. The Na/F co-doped LiNi_1/3Mn_1/3Co_1/3O₂ electrode delivered an initial specific capacity of 142 mAh g⁻¹ at a 1C rate (178 mAh g⁻¹ at 0.1C), and it maintained 50% of its initial capacity after 1000 charge–discharge cycles at a 1C rate.

Silver/quartz nanocomposite as an adsorbent for removal of mercury (II) ions from aqueous solutions

Silver nanoparticles (AgNPs) and silver/quartz nanocomposite (Ag/Q)NPs)) were synthesized by sol-gel method using table sugar as chelating agent. The synthesized nanosized materials were used for mercury ions adsorption from aqueous solutions. The materials were characterized by X-ray diffraction (XRD), Transmission Electron microscope (TEM), and surface area (BET). Adsorption of Hg²⁺ (10 mg/l) is strongly dependent on time, initial metal concentration, dose of adsorbent and pH value. Silver/quartz nanocomposite ((Ag/Q)NPs)) shows better efficiency than individual silver nanoparticles (AgNPs). This composite removed mercury ions from the aqueous solution with efficiency of 96% at 60 min with 0.5g adsorbent dosage at pH 6. The adsorption process explained well by the pseudo-second-order kinetic model. In conclusion silver/quartz nanocomposite (Ag/Q)NPs)) shows higher removal efficiency for mercury ions from aqueous solutions than individual silver naoparticles (AgNPs) or quartz (Q).

Doped Nanoscale NMC333 as Cathode Materials for Li-Ion Batteries

A series of Li(Ni_1/3Mn_1/3Co_1/3)_1−xM_xO₂ (M = Al, Mg, Zn, and Fe, x = 0.06) was prepared via sol-gel method assisted by ethylene diamine tetra acetic acid as a chelating agent. A typical hexagonal α-NaFeO₂ structure (R-3m space group) was observed for parent and doped samples as revealed by X-ray diffraction patterns. For all samples, hexagonally shaped nanoparticles were observed by scanning electron microscopy and transmission electron microscopy. The local structure was characterized by infrared, Raman, and Mössbauer spectroscopy and ⁷Li nuclear magnetic resonance (Li-NMR). Cyclic voltammetry and galvanostatic charge-discharge tests showed that Mg and Al doping improved the electrochemical performance of LiNi_1/3Mn_1/3Co_1/3O₂ in terms of specific capacities and cyclability. In addition, while Al doping increases the initial capacity, Mg doping is the best choice as it improves cyclability for reasons discussed in this work.

Facile one step synthesis method of spinel LiMn2O4 cathode material for lithium batteries

This study succeeded to prepare three pure phases of Mn₂O₃, Mn₃O₄ beside one of the best cathode materials, spinel LiMn₂O₄. LiMn₂O₄ with high phase purity and crystallinity was synthesized by a facile, cost effective and one step synthesis method. The structure and morphology of the powders were studied in detail by means of X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM) and surface area. The X-ray diffraction shows that the post-annealing process reveals the formation of pure crystalline spinel LiMn₂O₄ with small particle size and lower lattice strain. The thermogravimetric analysis threw the light on the role of the evaporation technique in producing LiMn₂O₄ by following the different phases on the thermal performance of the precursor. The morphological characterization shows the clear appearance of the octahedral particles of LiMn₂O₄ calcined at high temperature with microporous nanosized structure. Electrochemical testing of the as prepared spinel at 900 °C showed promising results in terms of high initial capacity and good cycle stability. The as prepared spinel sample shows also good rate performance.