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Efficiency and Quality Issues in the Production of Black Phosphorus by Mechanochemical Synthesis: A Multi-Technique Approach
摘要： Black phosphorus (BP) is a two-dimensional material potentially of great interest for applications in the fields of energy, sensing, and microelectronics. One of the most interesting methods to obtain BP is the conversion from red phosphorus (RP) by means of high-energy mechanochemical synthesis. To date, however, this synthesis process was not well characterized. In this work, starting from the mathematical model of energy transfer during the ball milling process, we investigate the effects on RP → BP conversion of three experimental parameters, the rotation speed, the milling time, and the weight ratio between the spheres and the milled material (BtPw ratio). The efficiency of the conversion process was verified by solid-state NMR, Raman spectroscopy, and X-ray diffraction. Whereas the first two parameters have a minor importance, the BtPw ratio plays a primary role in the RP → BP conversion. Yields approaching 100% can be obtained also with short milling times (15 min) and adequate rotation speed (e.g., 500 r.p.m.), provided that the BtPw ratio >40:1 is used. These results confirm the energy sustainability of the mechanochemical synthesis approach.
关键词： diffraction,solid-state NMR,anode,post-lithium ion batteries,Raman,mechanochemical synthesis
更新于2025-11-21 11:18:25
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Nanoparticle Emissions from Metal-Assisted Chemical Etching of Silicon Nanowires for Lithium Ion Batteries
摘要： As one of the most promising anode materials for high-capacity lithium ion batteries (LIBs), silicon nanowires (SiNWs) have been studied extensively. The metal-assisted chemical etching (MACE) is a low-cost and scalable method for SiNWs synthesis. Nanoparticle emissions from the MACE process, however, are of grave concerns due to their hazardous effects on both occupational and public health. In this study, both airborne and aqueous nanoparticle emissions from the MACE process for SiNWs with three sizes of 90 nm, 120 nm, and 140 nm are experimentally investigated. The prepared SiNWs are used as anodes of LIB coin cells, and the experimental results reveal that the initial discharge and charge capacities of LIB electrodes are 3636 and 2721 mAh g-1 with 90 nm SiNWs, 3779 and 2712 mAh g-1 with 120 nm SiNWs, and 3611 and 2539 mAh g-1 with 140 nm SiNWs. It is found that, for 1 kW h of LIB electrodes, the MACE process for 140 nm SiNWs produces a high concentration of airborne nanoparticle emissions of 2.48 × 109 particles/cm3; the process for 120 nm SiNWs produces a high mass concentration of aqueous particle emissions, with a value of 9.95 × 105 mg/L. The findings in this study can provide experimental data of nanoparticle emissions from the MACE process for SiNWs for LIB applications, and can help the environmental impact assessment and life cycle assessment of the technology in the future.
关键词： Lithium ion batteries (LIBs),Metal-assisted chemical etching (MACE),Nanoparticle emissions,Silicon nanowires (SiNWs)
更新于2025-09-23 15:23:52
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Easy preparation of nanoporous Ge/Cu3Ge composite and its high performances towards lithium storage
摘要： Nanoporous Ge/Cu3Ge composite is fabricated simply through selective dealloying of GeCuAl precursor alloy in dilute alkaline solution. The as-made Ge/Cu3Ge is characterized by three dimensional (3D) bicontinuous network nanostructure which comprises of substantial nanoscale pore voids and ligaments. Owing to the 3D porous architecture and the introduction of well-conductive Cu3Ge, the lithium storage performances of Ge are dramatically enhanced in terms of higher cycling stability and superior rate performance. Nanoporous Ge/Cu3Ge anode delivers steady capacities above 1000 mA h g-1 upon cycling for 70 loops at 400 mA g-1. In particular, after 300 cycles at the high rate of 3200 mA g-1 the capacity retention for Ge/Cu3Ge is able to reach a maximum of 99.3%. On the contrary, the pure nanoporous Ge encounters severe capacity decay. In view of the outstanding energy storage performances and easy preparation, nanoporous Ge/Cu3Ge exhibits great application potential as an advanced anode in lithium storage related technologies.
关键词： dealloying,anode,lithium ion batteries,nanoporous,germanium
更新于2025-09-23 15:23:52
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GeO <sub/>2</sub> Encapsulated Ge Nanostructure with Enhanced Lithium-Storage Properties
摘要： Germanium (Ge)-based nanostructures, especially those with germanium dioxide (GeO2), have drawn great interest for applications in lithium (Li)-ion batteries due to their ultrahigh theoretical Li+ storage capability (8.4 Li/Ge). However, GeO2 in conventional Ge(s)/GeO2(c) (where (c) means the core and (s) means the shell) composite anodes with Ge shell outside GeO2 undergoes an irreversible conversion reaction, which restricts the maximum capacity of such batteries to 1126 mAhg?1 (the equivalent of storing 4.4 Li+). In this work, a porous GeO2(s)/Ge(c) nanostructure with GeO2 shell outside Ge cores are successfully fabricated utilizing the Kirkendall effect and used as a lithium-ion battery anode, giving a substantially improved capacity of 1333.5 mAhg?1 at a current density of 0.1 Ag?1 after 30 cycles and a stable long-time cycle performance after 100 cycles at a current density of 0.5 A g?1. The enhanced battery performance is attributed to the improved reversibility of GeO2 lithiation/delithiation processes catalyzed by Ge in the properly structured porous GeO2(s)/Ge(c) nanostructure.
关键词： porous,Kirkendall effect,nanostructures,lithium ion batteries,GeO2(s)/Ge(c)
更新于2025-09-23 15:22:29
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One-pot Hydrothermal Synthesis of ZnO Microspheres/Graphene Hybrid and its Electrochemical Performance
摘要： In this paper, the ZnO microspheres/graphene hybrids were successfully prepared from zinc acetate and GO aqueous solution by a facile one-pot hydrothermal method without any surfactant. The as-synthesized samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), thermogravimetric (TGA) analysis, nitrogen adsorption/desorption isotherms and pore size distribution. When evaluated as anode material for lithium ion batteries, it delivered a high initial discharge capacity of 1150 mAh g-1 and exhibited excellent rate performance at different current densities.
关键词： anode materials,ZnO microspheres/graphene hybrid,one-pot hydrothermal,lithium ion batteries
更新于2025-09-23 15:21:01
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Controlled Engineering Nano-sized FeOOH@ZnO Hetero-Structures on Reduced Graphene Oxide for Lithium ion Storage and Photo-Fenton Reaction
摘要： In this work, a nano-sized goethite and zinc oxide hetero-structure (FeOOH@ZnO) dispersed on reduced graphene oxide (RGO) sheets to construct a ternary composite (FeOOH@ZnO/RGO) is first synthesized by a stepped graphene oxide (GO) deoxygenation process. Ferrous ion (Fe2+) and metal Zn were employed as reducing agents, which were transformed to corresponding FeOOH and ZnO nanoparticles to form a hetero-structure in the reaction. Particularly, the size of the nanoparticles can be controlled by limiting the growth kinetics in this work. As a result, porous RGO architecture is constructed with well-dispersed hetero-structured nanoparticles constituted by FeOOH and ZnO nano-crystals encapsulated. The FeOOH@ZnO/RGO composite exhibits unique lithium ion storage properties as anode for lithium ion batteries. And compared with the binary FeOOH/RGO and ZnO/RGO composites, the ternary FeOOH@ZnO/RGO composite shows the best battery performance as anode for lithium ion batteries and the best photo-Fenton degradation activity toward methylene blue (MB) degradation under simulated sunlight irradiation. The preparation route for FeOOH@ZnO/RGO composite is straightforward, effective and has great potential to be scaled-up.
关键词： zinc oxide,goethite,graphene,methylene blue degradation,photo-Fenton,lithium ion batteries
更新于2025-09-23 15:19:57
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Solvation Structure Analysis of Lithium Ion in Concentrated Lithium Salt Solutions Using Raman Spectroscopy; ラマン分光法によるリチウム塩濃厚電解液中のイオン溶媒和構造解析;
摘要： Electrolyte solutions are one of the key liquid materials in the development of high-performance lithium-ion batteries (LIBs). Recently, a new concept, “superconcentrated electrolyte”, i.e., solvent-in-salt in liquid state, was proposed and widely investigated in terms of not only electrochemistry, but also physical chemistry and/or solution chemistry. In this work, we report on a structural study of lithium-ion complexes in highly salt-concentrated electrolytes, lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) salt in N,N-dimethylpropionamide (DMPA), using Raman spectroscopy with the aid of density functional theory (DFT) calculations. In the range of the Li salt concentration, c Li = 0 – 3.2 mol dm–3, the individual solvation numbers of DMPA and TFSA species around Li ions [n (DMPA) and n (TFSA), respectively] were quantitatively determined and the relation between the Li ion complex structure and c Li was discussed at the molecular level.
关键词： raman spectroscopy,ion solvation,lithium-ion batteries,salt-concentrated electrolytes
更新于2025-09-19 17:15:36
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In Situ Raman Spectroscopy on Silicon Nanowire Anodes Integrated in Lithium Ion Batteries
摘要： Rapid decay of silicon anodes during lithiation poses a significant challenge in application of silicon as an anode material in lithium ion batteries. In situ Raman spectroscopy is a powerful method to study the relationship between structural and electrochemical data during electrode cycling and to allow the observation of amorphous as well as liquid and transient species in a battery cell. Herein, we present in situ Raman spectroscopy on high capacity electrode using uncoated and carbon-coated silicon nanowires during first lithiation and delithiation cycle in an optimized lithium ion battery setup and complement the results with operando X-ray reflection diffraction measurements. During lithiation, we were able to detect a new Raman signal at 1859 cm?1 especially on uncoated silicon nanowires. The detailed in situ Raman measurement of the first lithiation/delithiation cycle allowed to differentiate between morphology changes of the electrode as well as interphase formation from electrolyte components.
关键词： silicon nanowires,lithium ion batteries,in situ Raman spectroscopy,operando XRD,solid electrolyte interphase
更新于2025-09-19 17:15:36
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On the Decomposition of Carbonate-Based Lithium-Ion Battery Electrolytes Studied Using Operando Infrared Spectroscopy
摘要： A novel infrared diagnostic for operando measurements of electrolyte decomposition is reported. The diagnostic was used to study the decomposition of LiPF6/EC/DEC electrolyte in LCO/graphite Li-ion cells. During formative cycles spectra revealed electrochemical reduction of the EC carbonyl group, which corresponded to simultaneous SEI formation on the graphite anode. This observation supplements current theories of EC decomposition during SEI formation. Operating LCO half-cells at voltages above 4.2 V caused permanent battery capacity loss but no observable electrolyte degradation, indicating the LCO electrode is degraded at high voltage. Infrared thermometry was used to measure the temperature of the electrolyte during heated tests. Operating cells at temperatures above 70°C resulted in SEI and electrolyte decomposition. Operando spectra collected during heating revealed EC ring-opening as the mechanism of thermal degradation, which resulted in permanent capacity loss. EC thermal decomposition was identical in all cells tested, indicating a homogeneous decomposition reaction independent of electrode material or potential. Thermal stability decreased with increased salt concentration indicating that decomposition is likely catalyzed by LiPF6 decomposition products. Thus, thermal decomposition is not caused by continued reduction reactions on the anode due to SEI failure, as EC reduction and EC thermal decomposition have different mechanisms.
关键词： SEI formation,operando infrared spectroscopy,thermal stability,lithium-ion batteries,electrolyte decomposition
更新于2025-09-19 17:15:36
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Femtosecond Laser Processing of Thick Film Cathodes and Its Impact on Lithium-Ion Diffusion Kinetics
摘要： Quantitative experiments of lithiation/delithiation rates were considered for a better understanding of electrochemical intercalation/deintercalation processes in laser structured thick film cathodes. Besides galvanostatic cycling for evaluation of specific discharge capacities, a suitable quantitative approach for determining the rate of Li-ion insertion in the active material and the rate of Li-ion transport in the electrolyte is expressed by chemical diffusion coefficient values. For this purpose, the galvanostatic intermittent titration technique has been involved. It could be shown that laser structured electrodes provide an enhanced chemical diffusion coefficient and an improved capacity retention at high charging and discharging rates.
关键词： diffusion coefficient,LiCoO2,lithium-ion batteries,3D battery,laser ablation
更新于2025-09-19 17:13:59