Limited Stability of Ether-Based Solvents in Lithium–Oxygen Batteries

Li–O₂ batteries offer the tantalizing promise of a specific energy much greater than current Li ion technologies; however, many challenges remain before the development of commercial energy storage applications based on the lithium–oxygen couple can be realized. One of the most apparent limitations is electrolyte stability. Without an electrolyte that is resistant to attack by reduced oxygen species, optimizing other aspects of the redox performance is challenging. Thus, identifying electrolyte decomposition processes that occur early in the redox process will accelerate the discovery process. In this study, ATR–FTIR was used to examine various reported Li–O₂ electrolytes taken directly from the cell separators of cycled electrochemical cells. Specifically, we examined, 1 M LiPF₆ in propylene carbonate (PC), 1 M LiCF₃SO₃ in tetraethyleneglycoldimethylether (TEGDME), and 1 M LiCF₃SO₃ in a siloxane ether (1NM3) and looked for soluble decomposition products. Each electrolyte was tested using a regular Li–O₂ cathode with no catalyst and either an O₂ atmosphere or an Ar atmosphere and a Li metal anode as well as in a Li–Li symmetric cell. The 1NM3 electrolyte was found to form soluble decomposition products under all cell conditions tested, and a decomposition pathway has been proposed. It was also found that 1NM3 and TEGDME were consumed as part of the charging process in a working Li–O₂ cell, even at moderate voltages in the absence of O<sub>2.</sub

Quantifying the Correlation between Coordination Chemistry, Interfacial Formation, and Electrochemical Performances for Mg Battery Electrolytes

The rise of magnesium batteries as promising post-Li-ion energy storage technologies has sparked considerable attention toward understanding the fundamental aspects of coordination chemistry concerning Mg cations in multivalent electrolytes. This exploration includes investigating how coordination influences crucial electrolyte properties like solubility, electroreduction stability, and the formation of the interphase, all of which are pivotal for practical battery applications. Despite recent progress in developing a few functional electrolytes, a comprehensive understanding of the solvation structure that can facilitate efficient Mg deposition performance and the formulation of general design rules based on the solvation structure is still lacking. In our study, we endeavor to establish a connection between solvent and anion interactions with Mg2+, interface formation, and cycling performance through a series of organic ether solvents (tetrahydrofuran, glyme, diglyme, and triglyme) and amine solvents (dimethylamine, 3-methoxypropylamine, and dimethoxyethylamine). Our findings reveal a distinct coordination trend for solvent/Mg2+ and (Mg-TFSI):solvent across various solvents, which dictates the extent of ion pairing for TFSI salts with increasing solvent molecule size and denticity. The solvated species in the bulk electrolyte across different solvents lead to diverse interfacial chemistries with varying decomposition components. We also explore the cycling efficiency as well as Mg deposition overpotentials for different solvents. A correlation analysis was conducted to assess the interplay between the structure and performance. Lastly, we apply the insights gained from these results to tailor the relative anion/Mg2+ coordination structures using cosolvent systems, aiming for improved cell performance

Conjugated Polymer Energy Level Shifts in Lithium-Ion Battery Electrolytes

The ionization potentials (IPs) and electron affinities (EAs) of widely used conjugated polymers are evaluated by cyclic voltammetry (CV) in conventional electrochemical and lithium-ion battery media, and also by ultraviolet photoelectron spectroscopy (UPS) in vacuo. By comparing the data obtained in the different systems, it is found that the IPs of the conjugated polymer films determined by conventional CV (IP_C) can be correlated with UPS-measured HOMO energy levels (<i>E</i>_H,UPS) by the relationship <i>E</i>_H,UPS = (1.14 ± 0.23) × <i>q</i>IP_C + (4.62 ± 0.10) eV, where <i>q</i> is the electron charge. It is also found that the EAs of the conjugated polymer films measured via CV in conventional (EA_C) and Li⁺ battery (EA_B) media can be linearly correlated by the relationship EA_B = (1.07 ± 0.13) × EA_C + (2.84 ± 0.22) V. The slopes and intercepts of these equations can be correlated with the dielectric constants of the polymer film environments and the redox potentials of the reference electrodes, as modified by the surrounding electrolyte, respectively

Not Your Normal Power Box

Representing the Center for Electrical Energy Storage (CEES), this document is one of the entries in the Ten Hundred and One Word Challenge and was awarded "Best Science Lesson." As part of the challenge, the 46 Energy Frontier Research Centers were invited to represent their science in images, cartoons, photos, words and original paintings, but any descriptions or words could only use the 1000 most commonly used words in the English language, with the addition of one word important to each of the EFRCs and the mission of DOE: energy. The mission of the CEES is to acquire a fundamental understanding of interfacial phenomena controlling electrochemical processes that will enable dramatic improvements in the properties and performance of energy storage devices, notably Li ion batteries

Energy storage emerging: A perspective from the Joint Center for Energy Storage Research.

Energy storage is an integral part of modern society. A contemporary example is the lithium (Li)-ion battery, which enabled the launch of the personal electronics revolution in 1991 and the first commercial electric vehicles in 2010. Most recently, Li-ion batteries have expanded into the electricity grid to firm variable renewable generation, increasing the efficiency and effectiveness of transmission and distribution. Important applications continue to emerge including decarbonization of heavy-duty vehicles, rail, maritime shipping, and aviation and the growth of renewable electricity and storage on the grid. This perspective compares energy storage needs and priorities in 2010 with those now and those emerging over the next few decades. The diversity of demands for energy storage requires a diversity of purpose-built batteries designed to meet disparate applications. Advances in the frontier of battery research to achieve transformative performance spanning energy and power density, capacity, charge/discharge times, cost, lifetime, and safety are highlighted, along with strategic research refinements made by the Joint Center for Energy Storage Research (JCESR) and the broader community to accommodate the changing storage needs and priorities. Innovative experimental tools with higher spatial and temporal resolution, in situ and operando characterization, first-principles simulation, high throughput computation, machine learning, and artificial intelligence work collectively to reveal the origins of the electrochemical phenomena that enable new means of energy storage. This knowledge allows a constructionist approach to materials, chemistries, and architectures, where each atom or molecule plays a prescribed role in realizing batteries with unique performance profiles suitable for emergent demands

Energy storage emerging: A perspective from the Joint Center for Energy Storage Research.

Energy storage is an integral part of modern society. A contemporary example is the lithium (Li)-ion battery, which enabled the launch of the personal electronics revolution in 1991 and the first commercial electric vehicles in 2010. Most recently, Li-ion batteries have expanded into the electricity grid to firm variable renewable generation, increasing the efficiency and effectiveness of transmission and distribution. Important applications continue to emerge including decarbonization of heavy-duty vehicles, rail, maritime shipping, and aviation and the growth of renewable electricity and storage on the grid. This perspective compares energy storage needs and priorities in 2010 with those now and those emerging over the next few decades. The diversity of demands for energy storage requires a diversity of purpose-built batteries designed to meet disparate applications. Advances in the frontier of battery research to achieve transformative performance spanning energy and power density, capacity, charge/discharge times, cost, lifetime, and safety are highlighted, along with strategic research refinements made by the Joint Center for Energy Storage Research (JCESR) and the broader community to accommodate the changing storage needs and priorities. Innovative experimental tools with higher spatial and temporal resolution, in situ and operando characterization, first-principles simulation, high throughput computation, machine learning, and artificial intelligence work collectively to reveal the origins of the electrochemical phenomena that enable new means of energy storage. This knowledge allows a constructionist approach to materials, chemistries, and architectures, where each atom or molecule plays a prescribed role in realizing batteries with unique performance profiles suitable for emergent demands