LiNi0.5Mn1.5O4 Thin Films Grown by Magnetron Sputtering under Inert Gas Flow Mixtures as High-Voltage Cathode Materials for Lithium-Ion Batteries

Delivering a commercial high-voltage spinel LiNi0.5Mn1.5O4 (LNMO) cathode electrode for Li-ion batteries would result in a significant step forward in terms of energy density. However, the structural ordering of the spinel and particle size have considerable effects on the cathode material's cyclability and rate capability, which are crucial challenges to address. Here, a novel mid-frequency alternating current dual magnetron sputtering method was presented, using different Ar-N-2 gas mixtures ratios for the process gas to prepare various LNMO thin films with highly controlled morphology and particle size; as determined from X-ray diffraction, Raman spectroscopy and electron microscopy. It resulted in enhanced cycling and rate performance. This processing method delivered N-containing LNMO thin film electrodes with up to 15 % increased discharge capacity at 1 C (120 mAh g(-1)) with respect to standard LNMO (grown under only Ar gas flow) thin film electrodes, along with outstanding rate performance up to 10 C (99 mAh g(-1)) in the operating voltage window 3.5-4.85 V vs. Li+/Li. Besides, electrochemical impedance spectroscopy results showed that the intricate phase transitions present in standard LNMO electrodes were almost suppressed in N-containing LNMO thin films grown under different Ar-N-2 gas flow mixtures

Determination of solvation descriptors for terpene hydrocarbons from chromatographic measurements

This article discusses the determination of solvation descriptors for terpene hydrocarbons from chromatographic measurements

Improvement of structural and electrochemical properties of NMC layered cathode material by combined doping and coating

Prospective cathode materials, pristine and Mg-/Zr-modified LiNi0.33Mn0.33Co0.33O2 (NMC333), are successfully synthesized through a synthetic method including a citric acid-assisted sol-gel processing followed by drying and calcination at different temperatures. The combined results from structural, chemical, and morphological investigations reveal that the modified NMC, where the modification is obtained by doping and a uniform coating layer with an optimal thickness, show a better-organized layered structure and improved interfacial properties compared to the pristine NMC. The modified NMC material shows a remarkable improvement in terms of capacity retention, especially when setting the charge cut-off voltage at 4.2 V, which results in improved cycling stability after more than 200 cycles with capacity retention of around 95%. In order to shed light on the kinetics of redox processes, and its impact on charge/discharge behavior, electrochemical impedance spectroscopy is carried out at different states of charge during oxidation and reduction for both pristine and modified NMC-based electrodes. The promising results obtained with this synthesis open possibilities for performance improvements of intercalating layered oxides by structure doping and surface enhancement

Improving high-voltage cycling performance of nickel-rich NMC layered oxide cathodes for rechargeable lithium–ion batteries by Mg and Zr co-doping

Regarding the cost and safety concerns arising together with the increasing demands on lithium–ion batteries, high energy density Ni-rich LiNi0.8Co0.1Mn0.1O2 (NMC811) materials are of substantial interest as cathode materials for the next-generation commercial lithium–ion batteries. However, their low cycling stability hinders their use in large-scale applications (Schipper et al., 2018). In this work, we report two NMC811 materials, pristine and Mg/Zr co-doped, both synthesized through a facile sol-gel method followed by a stepwise calcination process. The doped cathode presents enhanced structural stability and shows a specific capacity of 232 mAh/g, at 0.1C and high charge cut-off voltage of 4.8 V vs. Li+/Li, and significant good cycling stability after 100 cycles; better than pristine NMC811. To unravel the origin of the enhancement, we have investigated the ionic and electronic transport properties by means of electrochemical impedance spectroscopy measurements, as well as the behavior of the electrode–electrolyte interphase layer

From waste to resources: transforming olive leaves to hard carbon as sustainable and versatile electrode material for Li/Na-ion batteries and supercapacitors

Over the last few years, biomass-derived hard carbon materials are drawing more and more attention because of their high abundance, cost breakdown, high performance, and fast regeneration. In this context, the synthesis of hard carbon from olive leaves, a widely available by-product of table olive and olive oil industries, is here reported and its performance, as a sustainable electrode material for Li-ion batteries (LIBs), Na-ion batteries (NIBs), and supercapacitors (SCs), are evaluated. According to the in- formation acquired by structural characterization, a disordered structure is confirmed for the synthesized hard carbon. When tested as anode for LIBs and NIBs, electrodes based on Na-CMC green binder show discharge capacities of 331.0 mAh/g and 265.4 mAh/g at 1C (with minor irreversibility), respectively, with promising cycling stability. In SC application, the electrode delivers a high specific capacitance of 169.6 F/ g at 0.5 A/g and remarkable capacity retention of 96.7% after more than 20,000 cycles at 10 A/g. As a result, this work confirms the possibility to use olive leaves-derived hard carbon material for the low- cost, environmental-friendly fabrication of electrodes with high energy and power capabilities