First-Principles Study on the Elastic Mechanical Properties and Anisotropies of Gold–Copper Intermetallic Compounds

Carbonated Beverage Chemistry for High-Voltage Battery Cathodes

Advanced lithium-ion batteries utilize high upper cut-off voltages up to 4.8 V versus lithium metal to reach extraordinary energy densities. Such a harsh environment challenges the cathode stability and requires the construction of robust cathode electrolyte interphases at their electrochemical interface. Inspired by carbonated beverages with supersaturated CO2, here, a surface modification strategy that produces effective passivation layer of low modulus from the weakest link, is proposed CO2 bubbles preferentially nucleate and grow at rough surfaces, which in oxide cathodes, are also the local regions offering fast degradation pathway. Metal ion exchange on carbonated layer assists the construction of highly elastic interface under the guidance of packing factor. This method enables surface reconstruction at both primary and secondary particle levels for various cathodes exemplified by high-voltage LiNi0.8Co0.1Mn0.1O2 (NCM811) and LiCoO2 (LCO). Remarkably, with ultra-high upper cut-off voltage of 4.8 V versus Li+/Li, over 235 mAh g-1 discharge capacity, and over 900 W h kg-1 discharge energy at cathode level, ≈90% capacity retention can be obtained for LiNi0.8Co0.1Mn0.1O2 over 100 cycles at 0.5 C with commercial carbonate electrolytes. This carbonated beverage chemistry is promising for constructing high-quality surface passivation in many extreme-condition applications beyond battery cathodes.

Weakly Solvating Few-Layer-Carbon Interface toward High Initial Coulombic Efficiency and Cyclability Hard Carbon Anodes

The carbonaceous anodes in sodium ion batteries suffer from low initial Coulombic efficiency (ICE) and poor cyclability due to rampant solid electrolyte interface (SEI) growth. The concept of the weakly solvating electrolyte (WSE) has been popularized for SEI regulation on the anode by adjusting the cation solvation structure. Nevertheless, the effects on the solvation sheath from the electrode/electrolyte interface are ignored in most WSE applications. In this work, we extend the WSE from the bulk electrolyte to the electrolyte/carbon interface. By recycling asphalt wastes into sp2 C enriched few-layer carbon on hard carbon, a weakly solvating interface is fabricated with lower adsorption energy to electrolyte solvent molecules than a pristine anode (-0.89 vs -1.08 eV for Na/diglyme). Accordingly, more anionic groups are attracted into the solvent-weakened solvation sheath during sodiation (2.30 vs 1.96 coordination number for PF6-). The anion-mediated contact ion pairs facilitate a thin, inorganic-rich SEI layer with a homogeneous distribution, which confers a high ICE of 97.9% and a high capacity of 335.6 mA h g-1 at 1 C (89.5% retention, 1000 cycles). The full battery also manifests an energy density of 209 W h kg-1. This interfacial design is applicable in both ether- and ester-based electrolytes, which is promising in cost-effective modification for carbonaceous electrodes.

Development of a New AuCuZnGe Alloy and Determination of Its Corrosion Properties

In this paper, we present the idea and development of a new gold-copper-zinc-germanium (AuCuZnGe) alloy, which is related to the method of production and research of its key properties, so that the new Au alloy could be used for jewelry production and in dental technology. The research design was associated with the determination of appropriate chemical composition, manufacturing technology, and performing the characterization. Melting and casting technologies were used to cast the AuCuZnGe alloy while rolling was used to prepare the cylinders and cutting to make square plates with a = 10 mm and thickness of 1 mm. Such plates were provided for corrosion testing. Observation of the plate′s microstructure was performed with Scanning Electron Microscopy (SEM) equipped by Energy-Dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD). Corrosion testing involved performing the following measurements: Polarization, the open circuit potentials, and linear polarization resistance. Based on the SEM, EDS, XRD, and results of corrosion testing it can be concluded that the new AuCuZnGe alloy possesses high corrosion stability and can be classified as a high noble alloy.