NiO x , long studied for its use in nickel-based secondary batteries, has been the subject of much recent interest due to its efficacy as an oxygen evolution catalyst. Despite extensive study over more than a century, however, many outstanding questions remain surrounding both the structure and the activity of NiO x . Further compounding this ambiguity is the recent finding that much of the previous experimental work on NiO x may have been influenced by incidental doping. Here, we report a computational study of the two simplest members of the NiO x family: β-Ni­(OH)2 and β-NiOOH. Using DFT+U calculations, we first identify a β-NiOOH structure with a staggered arrangement of intercalated protons that is more consistent with experimental crystal structures of β-NiOOH than previously proposed geometries. Next, by conducting a thorough study of various initial spin configurations of this β-NiOOH structure, we found that a low-spin d7 Ni3+ configuration is always favored, which suggests a Jahn–Teller distortion, rather than disproportionation, explains the different Ni–O bond distances found in experiment. G 0 W 0 calculations performed on β-Ni­(OH)2 and β-NiOOH reveal electronic structures consistent with previous experimental results. Lastly, calculations of various low-index surface energies of both β-Ni­(OH)2 and β-NiOOH demonstrate that the (001) surface is the most thermodynamically stable surface, in keeping with numerous experimental results but in contrast to recent computational models.

We present an entirely ab initio methodology, based on symmetry adapted perturbation theory (SAPT), for constructing force-fields to study CO 2 adsorption in nanoporous zeolitic imidazolate frameworks (ZIFs). Our approach utilizes the SAPT energy decomposition to generate physically motivated force fields for the CO 2 -ZIF interaction, with explicit terms representing exchange, electrostatic, induction and dispersion interactions. Each of these terms is fit to the corresponding term in the SAPT energy decomposition, yielding a force field entirely free of empirical parameters. This approach was utilized to construct force fields describing the CO 2 interaction with both ZIF-8 and ZIF-71. In conjunction with our existing CO 2 ÀCO 2 force field, parametrized in a consistent manner, we validate our force fields using grand canonical Monte Carlo simulations and obtain good agreement with the corresponding experimental CO 2 adsorption isotherms. Furthermore, the explicit correspondence between force field terms and fundamental interaction types (dispersion, electrostatics, and induction) allows for an analysis of the underlying physics controlling ZIF gas adsorption that is far more direct and well-defined than with the generic force fields that had been previously utilized to study these systems. As our force fields are free from empirical parameters, these results demonstrate the potential for computationally screening novel ZIFs for flue gas separation applications with near quantitative accuracy.

We use electronic structure calculations to examine the impact of trace flue gas contaminants (nitrogen oxides, sulfur oxides, and their hydrates) on two promising coordinatively unsaturated metal−organic framework (MOF) sorbents. Such MOFs have been the subject of recent intense study since their unsaturated "open metal" sites yield dramatically enhanced uptake of CO 2 at low partial pressures, ideal for flue gas separation applications. However, the impact of these contaminants on gas adsorption and separation has not been seriously considered. Our computational results suggest that the open metal sites are subject to poisoning by these trace flue gas contaminants. Thus, despite the low (postscrubbing) concentrations of these contaminants, their binding enthalpy is sufficient to outcompete CO 2 for binding sites under equilibrium adsorption conditions and (by some estimates) even putative regeneration conditions. This work thus provides guidelines for identifying relevant contaminant species and illustrates the practical concerns in utilizing MOFs in realistic flue gas separation applications.

Lithium‐metal batteries (LMBs) are considered as promising next‐generation batteries due to their high energy density. However, commercial carbonate electrolytes cannot be used in LMBs due to their poor compatibility with the lithium‐metal anode and detrimental hydrogen fluoride (HF) generation by lithium hexafluorophosphate decomposition. By introducing lithium nitrate additive and a small amount of tetramethylurea as a multifunctional cosolvent to a commercial carbonate electrolyte, NO3−, which is usually insoluble, can be introduced into the solvation structure of Li+ to form a conductive and stable solid electrolyte interface. At the same time, HF generation is suppressed by manipulating the solvation structure and a scavenging effect. As a result, the Coulombic efficiency (CE) of Li||Cu half cells using the designed carbonate electrolyte can reach 98.19% at room temperature and 96.14% at low temperature (−15 °C), and Li||LiFePO4 cells deliver a high capacity retention of 94.9% with a high CE of 99.6% after 550 cycles. This work provides a simple and effective way to extend the use of commercial carbonate electrolytes for next‐generation battery systems.