Ion–water cluster free energy computer simulation using some of most popular ion–water and water–water pair interaction models

How Thick Aqueous Alkali Should be Better for Aluminum-Air Batteries at Sub-Zero Temperatures: A Critical Anti-Freezing Concentration

The application of portable aluminum-air batteries (AABs) in extreme environments is an inevitable demand for future development. Aqueous electrolyte freezing is a major challenge for low-temperature operations. Conventionally, enlightened by the organic system in metal ion batteries, blindly increasing the concentration is regarded as an efficient technique to reduce the freezing point (FP). However, the underlying contradiction between the adjusting mechanism of the FP and OH- transportation is ignored. Herein, the aqueous alkali solution of CsOH is researched as a prototype to disclose the intrinsic conductive behavior and related solvent structure evolution. Different from these inorganic electrolyte systems, the concept of a critical anti-freezing concentration (CFC) is proposed based on a specific temperature. The relationship between hydrogen bond reconstruction and de-solvation behavior is analyzed. A high conductivity is obtained at -30 °C, which is also a recorded value in an intrinsic aqueous AAB. The homogenous dissolution of the Al anode is also observed. As a general rule, the CFC concept is also applied in both the KOH and NaOH systems.

Can Aqueous Zinc-Air Batteries Work at Sub-Zero Temperatures?

Efficient energy storage at low temperatures starves for competent battery techniques. Herein, inherent advantages of zinc-air batteries on low-temperature electrochemical energy storage are discovered. The electrode reactions are resistive against low temperatures to render feasible working zinc-air batteries under sub-zero temperatures. The relatively reduced ionic conductivity of electrolyte is identified as the main limiting factor, which can be addressed by employing a CsOH-based electrolyte through regulating the solvation structures. Accordingly, 500 cycles with a stable voltage gap of 0.8 V at 5.0 mA cm^-2 is achieved at -10 °C. This work reveals the promising potential of zinc-air batteries for low-temperature electrochemical energy storage and inspires advanced battery systems under extreme working conditions.

Control of chemical effects in the separation process of a differential mobility mass spectrometer system

Differential mobility spectrometry (DMS) separates ions on the basis of the difference in their migration rates under high versus low electric fields. Several models describing the physical nature of this field mobility dependence have been proposed but emerging as a dominant effect is the clusterization model sometimes referred to as the dynamic cluster-decluster model. DMS resolution and peak capacity is strongly influenced by the addition of modifiers which results in the formation and dissociation of clusters. This process increases selectivity due to the unique chemical interactions that occur between an ion and neutral gas-phase molecules. It is thus imperative to bring the parameters influencing the chemical interactions under control and find ways to exploit them in order to improve the analytical utility of the device. In this paper, we describe three important areas that need consideration in order to stabilize and capitalize on the chemical processes that dominate a DMS separation. The first involves means of controlling the dynamic equilibrium of the clustering reactions with high concentrations of specific reagents. The second area involves a means to deal with the unwanted heterogeneous cluster ion populations emitted from the electrospray ionization process that degrade resolution and sensitivity. The third involves fine control of parameters that affect the fundamental collision processes, temperature and pressure.