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Developing electrolytes for Li-metal batteries capable of operating under extreme conditions is a significant challenge and is often hindered by the absence of systematic solvent screening studies. In this study, 190 binary mixtures comprising 20 solvents were assessed by calculating the density functional theory (DFT) and conductor-like screening model for realistic solvents (COSMO-RS) to identify electrolytes with a wide liquid temperature range and high LiTFSI solubility. Tetramethylene sulfone (TMS) has emerged as a promising candidate because of its high boiling point and low enthalpy of fusion, which increase the bubble point and reduce the eutectic temperature in mixtures. Utilizing a machine learning model with seven σ-descriptors, Li- and TFSI-ion binding energies were accurately predicted. These binding energies were primarily influenced by strong electrostatic and van der Waals interactions. This integrated approach highlights the effectiveness of the combined DFT, COSMO-RS, and machine learning techniques for guiding electrolyte design. [ABSTRACT FROM AUTHOR]

A limiting factor for solid polymer electrolyte (SPE)-based Li-batteries is the functionality of the electrolyte decomposition layer that is spontaneously formed at the Li metal anode. A deeper understanding of this layer will facilitate its improvement. This study investigates three SPEs – polyethylene oxide:lithium tetrafluoroborate (PEO:LiBF4), polyethylene oxide:lithium bis(oxalate)borate (PEO:LiBOB), and polyethylene oxide:lithium difluoro(oxalato)borate (PEO:LiDFOB) – using a combination of electrochemical impedance spectroscopy (EIS), galvanostatic cycling, in situ Li deposition photoelectron spectroscopy (PES), and ab initio molecular dynamics (AIMD) simulations. Through this combination, the cell performance of PEO:LiDFOB can be connected to the initial SPE decomposition at the anode interface. It is found that PEO:LiDFOB had the highest capacity retention, which is correlated to having the least decomposition at the interface. This indicates that the lower SPE decomposition at the interface still creates a more effective decomposition layer, which is capable of preventing further electrolyte decomposition. Moreover, the PES results indicate formation of polyethylene in the SEI in cells based on PEO electrolytes. This is supported by AIMD that shows a polyethylene formation pathway through free-radical polymerization of ethylene. [ABSTRACT FROM AUTHOR]

To develop high energy density Li batteries, Li metal anodes and in situ plated Li anodes (i.e., the so-called anode-free approach) have been extensively studied. However, the high reactivity of the Li metal surface can lead to chemical reactions with electrolyte components upon contact. Consequently, the so-called native solid electrolyte interphase (SEI) species are formed spontaneously when the Li anode is in contact with the electrolyte. This study illustrates the formation chemistry of native SEI over a Li metal surface using lithium bis(trifluoromethanesulfonyl)imide in tetramethylene sulfone and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (LiTFSI/TMS-TTE) electrolyte with and without lithium polysulfide (PS) additive. All electrolyte components were found to decompose over the Li surface based on diffuse reflectance infrared Fourier-transformed spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), and ab initio molecular dynamics (AIMD) simulation. The degradation mechanism and the evolved SEI species of each electrolyte component were carefully evaluated. The PS additive can significantly influence the composition of native SEI via its decomposition prior to all other electrolyte components, which can consequently suppress the degradation of the other electrolyte components, namely, TTE, TMS, and LiTFSI. The results indicate the importance of proper selection of electrolyte components, which can lead to the possibility of tuning such native SEI species to stabilize the Li surface in subsequent electrochemical cycling. [ABSTRACT FROM AUTHOR]

The development of energy-efficient materials is highly desirable for CO2 capture to diminish CO2 emissions from fossil fuel combustion. Herein, we explore the mechanism of CO2 capture in mmen-Mg2(dobpdc), combining the use of density functional theory (DFT) calculations with microkinetic simulations. Our results demonstrate that CO2 capture in mmen-Mg2(dobpdc) via outer-amine binding and inner-amine binding is feasible, and CO2 adsorption on the outer amine of the mmen molecule is kinetically more favorable than that on the inner amine. In addition, we have considered that CO2 molecules continuously adsorb on the outer and inner amine sites simultaneously. We found that the activation barrier of CO2 carboxylation varied from 1.29 to 1.52 eV via dual-amine binding modes, providing a reasonable explanation for the experimental observation of Mg-coordinated ammonium carbonate and outer carbamic acid species in mmen-Mg2(dobpdc). Moreover, we found that CO2 desorption from the outer and inner ammonium carbonate complexes occurred at 128 and 142 °C, respectively, which is consistent with previous experimental results. Furthermore, our results demonstrate that the CO2 adsorption barriers can be effectively reduced by considering the deprotonated mmen molecules in an alkaline environment. This study provides detailed insights and the actual mechanism of CO2 adsorption in mmen-Mg2(dobpdc). We hope that this work could shed new light on the understanding and development of diamine-functionalized metal–organic frameworks for efficient CO2 capture. [ABSTRACT FROM AUTHOR]