Mg batteries are a promising battery technology that could lead to safer and significantly less expensive non-aqueous batteries with energy densities comparable or even better than state-of-the-art Li-ion batteries. Although the first prototype Mg battery using stable Mo6S8 as cathode was introduced over fifteen years ago, major challenges remain to be solved. In particular, the design of high energy cathode materials and the development of non-corrosive electrolytes with high oxidative stability are issues that need to be tackled. Herein, we present a new, general, and robust approach towards achieving stable cycling of Mg batteries. The core of our approach is the use of stable polymer cathode and Mg powder anode coupled with non-nucleophilic electrolytes. Our systems exhibit an excellent rate capability and significant improvement in electrochemical stability.

Li-ion batteries are considered very promising energy-storage devices for a variety of applications including large-scale batteries.[1] Given the large quantities of energy to be stored in such applications, the amount of cathode materials will be in the order kilograms per battery unit. This will not only raise concerns about the finite quantity of some resources on the earth and its environmental intolerance but also about overall CO 2 management.[2] To overcome such problems efficiently, Armand, Chen, and co-workers [2][3][4] recently suggested a new class of sustainable lithium batteries based on organic compounds. The other available literature mainly reports on the use of polymers as possible electroactive materials in Liion batteries [5,6] or totally organic polymer based rechargeable batteries.[7] Indeed, certain redox active centers of organic molecules (and also polymers) offer almost unlimited combinations of atomic arrangements and many possibilities for substitutions; this allows for fine tuning of the desired properties. Herein, our primary focus is the use of "monomer" organic molecules as an active material for Li-ion batteries. The reversible capacity of certain organic compounds, such as Li x C 6 O 6 , can reach values as high as 580 mA h g À1 , [3] but their operating voltage is typically quite low (about 2 V vs. Li). However, the most critical problem associated with utilization of organic materials in batteries is the high solubility of many interesting organic molecules in the aprotic electrolytes commonly used in the Li-ion batteries. Although soluble molecules can act as a charge carrier, [8] the operation of a battery using such molecules is diffusionlimited. Besides that, the use of soluble organic molecules in a long-term cycling process may be questionable. Herein we propose, for the first time, that this problem can be overcome by grafting (anchoring) of soluble electroactive organic molecules onto the surface of an appropriate insoluble substrate. The essence of this approach is the strong attachment of organic molecules to a suitable substrate. This attachment not only makes the organic molecule stable during the electrochemical operation but also allows tuning of its electrochemical properties (e.g. its redox potential). Unlike in batteries, such an approach is commonly used in the related fields of sensors [9,10] and supercapacitors.[11]We demonstrate this concept by grafting a quinone derivative of calix[4]arene (CQ) onto the surface of two different substrates: 1) nanosized silica particles with a specific surface area close to 200 m 2 g À1 and 2) carbon black. The electronic wiring between the grafted CQ and the current collector is established by further addition of carbon black. Scheme 1 shows the hypothetical mechanism of grafting of one CQ on silica nanoparticle and the proposed electrochemical reaction. The proposed binding nature of CQ onto silica is supposed to result in excellent electrochemical stability of such organic-inorganic hybrid system. The choice of CQ was bas...

Organic materials are receiving an increasing amount of attention as electrode materials for future post lithium-ion batteries due to their versatility and sustainability. However, their electrochemical reaction mechanism has seldom been investigated. This is a direct consequence of a lack of straightforward and broadly available analytical techniques. Herein, a straightforward in operando attenuated total reflectance infrared spectroscopy method is developed that allows visualization of changes of all infrared active bands that occur as a consequence of reduction/oxidation processes. In operando infrared spectroscopy is applied to the analysis of three different organic polymer materials in lithium batteries. Moreover, this in operando method is further extended to investigation of redox reaction mechanism of poly(anthraquinonyl sulfide) in a magnesium battery, where a reduction of carbonyl bond is demonstrated as a mechanism of electrochemical activity. Conclusions done by the in operando results are complemented by synthesis of model compound and density functional theory calculation of infrared spectra.

The abundance of Ca, its low redox potential and high specific capacity make Ca metal batteries an attractive energy storage system for the future. A recent demonstration of room temperature calcium plating/stripping opened a new avenue of the development, but the performance of cathode materials is lagging far behind. Due to the nature of divalent cations, conversion and coordination electrochemical reactions show better performance compared to insertion. Herein, we demonstrate the use of the anthraquinone‐based polymer as a cathode material for the Ca metal‐organic battery. Electrochemical mechanism investigation confirms the reversible reduction of the carbonyl bond and coordination with Ca2+ cations in the discharged state, opening a pathway toward high energy density battery. Continued performance of a 2‐electrode cell is strongly hampered by the overpotential increase caused by the Ca stripping process on the Ca metal anode stating the need for further development of Ca electrolytes. Ca metal‐organic battery promises to achieve cells with gravimetric energy density on the practical level compared to the state‐of‐the‐art Li‐ion batteries.

By employing new electrolytes, the polysulfide shuttle phenomenon, one of the main problems of lithium–sulfur (Li–S) batteries, can be significantly reduced. Here we present excellent Coulombic efficiencies as well as adequate performance of high-energy Li–S cells by the use of a fluorinated ether (TFEE) based electrolyte at low electrolyte loading. The observed altered discharge profile was investigated both by electrochemical experiments and an especially tailored COSMO-RS computational approach, while the details of the discharge mechanism were elucidated by two operando techniques: XANES and UV–vis spectroscopy. A significant decrease of polysulfide solubility compared to tetraglyme is due to different Li+ solvation mode.