LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) is a promising cathode material for long range electric vehicles. However, the material suffers severe chemo-mechanical degradation that can cause gradual capacity loss upon prolonged cycling. Surface passivation of NMC811 was demonstrated to help in retaining the structural integrity of the material upon extended cycling. Herein, we report the surface passivation of the NCM811 using Li 2 S and Na 2 S precursors via direct and simple wet chemical treatment, for the mitigation of parasitic reactions at the electrode electrolyte interphase. This phenomenon is accompanied by increase in the oxidation state of sulfur (from sulfide to sulfate) and partial reduction in the oxidation state of nickel. Electrochemical performance measurements show that the M 2 SO 4 (M: Li, Na) protection layer on NMC811 behaves as an artificial cathode electrolyte interphase (ACEI) that enhance the capacity retention by 25% during prolong cycling with respect to the untreated NMC811. Postmortem morphology studies reveal that the thin metal sulfates coatings remain on the cathode even after 100 cycles, while the untreated NCM811 shows severe morphological instabilities. Our study demonstrates that by simple chemical treatment of NMC811 can enhance its overall stability and cycling performance for the development of advanced high energy density Lithium-ion battery systems.

Page 1. 1 Intrinsic Ion Transport Properties of Block Copolymer Electrolytes Daniel Sharon,\S,$Δ$,‡ Peter Bennington,\S,‡ Moshe Dolejsi,\S Michael A. Webb,ǁ Ban Xuan Dong,\S Juan J. de Pablo\S,$Δ$ Paul F. Nealey,\S,$Δ$,* Shrayesh N. Patel\S,$Δ$ łdots}

The goal of limiting global warming to 1.5 °C requires a drastic reduction in CO2 emissions across many sectors of the world economy. Batteries are vital to this endeavor, whether used in electric vehicles, to store renewable electricity, or in aviation. Present lithium-ion technologies are preparing the public for this inevitable change, but their maximum theoretical specific capacity presents a limitation. Their high cost is another concern for commercial viability. Metal-air batteries have the highest theoretical energy density of all possible secondary battery technologies and could yield step changes in energy storage, if their practical difficulties could be overcome. The scope of this review is to provide an objective, comprehensive, and authoritative assessment of the intensive work invested in nonaqueous rechargeable metal-air batteries over the past few years, which identified the key problems and guides directions to solve them. We focus primarily on the challenges and outlook for Li-O2 cells but include Na-O2, K-O2, and Mg-O2 cells for comparison. Our review highlights the interdisciplinary nature of this field that involves a combination of materials chemistry, electrochemistry, computation, microscopy, spectroscopy, and surface science. The mechanisms of O2 reduction and evolution are considered in the light of recent findings, along with developments in positive and negative electrodes, electrolytes, electrocatalysis on surfaces and in solution, and the degradative effect of singlet oxygen, which is typically formed in Li-O2 cells. ©

Nanoscale interfacial zone limits ion transport properties of polymer electrolytes.

Using UV-vis spectroscopy in conjunction with various electrochemical techniques, we have developed a new effective operando methodology for investigating the oxygen reduction reactions (ORRs) and their mechanisms in nonaqueous solutions. We can follow the in situ formation and presence of superoxide moieties during ORR as a function of solvent, cations, anions, and additives in the solution. Thus, using operando UV-vis spectroscopy, we found evidence for the formation of superoxide radical anions during oxygen reduction in LiTFSI/diglyme electrolyte solutions. Nitro blue tetrazolium (NBT) was used to indicate the presence of superoxide moieties based on its unique spectral response. Indeed, the spectral response of NBT containing solutions undergoing ORR could provide a direct indication for the level of association of the Li cations with the electrolyte anions.

© 2017 American Chemical Society. In this study, we present a new aprotic solvent, 2,4-dimethoxy-2,4-dimethylpentan-3-one (DMDMP), which is designed to resist nucleophilic attack and hydrogen abstraction by reduced oxygen species. Li-O 2 cells using DMDMP solutions were successfully cycled. By various analytical measurements, we showed that even after prolonged cycling only a negligible amount of DMDMP was degraded. We suggest that the observed capacity fading of the Li-O 2 DMDMP-based cells was due to instability of the lithium anode during cycling. The stability toward oxygen species makes DMDMP an excellent solvent candidate for many kinds of electrochemical systems which involve oxygen reduction and assorted evaluation reactions.

During the last two decades, we have observed a dramatic increase in the electrification of many technologies. What has enabled this transition to take place was the com-mercialization of Li-ion batteries in the early nineties. Mobile technologies such as cellular phones, laptops, and medical devices make these batteries crucial for our contemporary life-style. Like any other electrochemical cell, the Li-ion batteries are restricted to the thermodynamic limitations of the mate-rials. It might be that the energy density of the most advance Li-ion battery is still too low for demanding technologies such as a full electric vehicle. To really convince future customers to switch from the internal combustion engine, new batteries and chemistry need to be developed. Non-aqueous metal-ox-ygen batteries—such as lithium–oxygen, sodium–oxygen, magnesium–oxygen, and potassium–oxygen—offer high ca-pacity and high operation voltages. Also, by using suitable polar aprotic solvents, the oxygen reduction process that oc-curs during discharge can be reversed by applying an external potential during the charge process. Thus, in theory, these batteries could be electrically recharged a number of times. However, there are many scientific and technical challenges that need to be addressed. The current review highlights recent scientific insights related to these promising batteries. Nevertheless, the reader will note that many conclusions are applicable in other kinds of batteries as well.

Chemically prepared manganese dioxide (CMD), which is traditionally used as a cathode material for Li-ion batteries, was tested and characterized for the first time as a positive electrode material for hybrid supercapacitors with two different aqueous electrolyte solutions (6 M KOH and 0.5 M K2SO4). The CMD electrodes exhibit distinct electrochemical characteristics that depend on the electrolyte solution used. The CMD electrodes show higher specific capacitance in the basic electrolyte solution, 137 F/g, at a current density of 0.1 A/g. Asymmetric supercapacitors comprising CMD positive electrodes and activated carbon negative electrodes were fabricated and tested within an electrochemical window wider than the thermodynamic voltage limitation for aqueous solutions. The asymmetric supercapacitors based on KOH and K2SO4 showed very good electrochemical stability during more than 7000 charge-discharge cycles and reasonable energy and power density. The electrochemical performance of CMD/AC asymmetric supercapacitors, their easy assembly, and their low cost make these super capacitors promising as practical energy-storage devices.

Diglyme (G2) is the highly preferred solvent choice over other types of glymes for achieving longer cycling performance of Li–O 2 cells.

In this paper we present a comprehensive structural, chemical and electrochemical characterization of monoclinic Li0.33MnO2as a positive electrode material for aqueous high-voltage hybrid supercapacitors. The monoclinic Li0.33MnO2, which is traditionally used as cathode material for lithium ion batteries, was synthesized through a simple thermal solid-state synthesis. The monoclinic Li0.33MnO2electrode exhibits a wide operational potential window ranging between −1.25 and 1.25 V vs SCE, which enables it to serve as either a negative or a positive electrode. In addition, this electrode material exhibits a high specific capacity of 140 mAh g−1at a low current density of 0.1 A g−1, and 76 mAh g−1at high current density of 1 A g−1in this range of potentials. Hybrid supercapacitors composed of Li0.33MnO2positive electrode and activated carbon (AC) negative electrode were fabricated. They exhibit outstanding electrochemical performance in terms of operational potential window, cycleability, and energy and power density. The Li0.33MnO2/AC hybrid capacitor has an energy density of 13.5 Wh kg−1at power density of 100 W kg−1, which is twice than that of MnO2/AC and AC/AC supercapacitors, and an energy density of 7 Wh kg−1at 1000 W kg−1, which is seven times higher than that of AC/AC capacitors at this power density. Furthermore, this hybrid capacitor presents an excellent cycle life with 80% specific capacitance retention after 12,000 cycles to 2 V. The electrochemical charge storage mechanism of the monoclinic Li0.33MnO2was investigated by cyclic voltammetry and X-ray diffraction.

Improved efficiency and cyclability of cells containing LiBr demonstrate that the appropriate choice of electrolyte solution is the key to a successful Li–O 2 battery.

This work deals with core issues of Li–oxygen battery systems; intrinsic stability of polyether electrolyte solutions and the role of important redox mediators such as LiI/I 2 .