Sulfur Speciation in Li-S Batteries Determined by Laboratory X-ray Emission Spectroscopy.

In this work, sulfur X-ray emission measurements on a Li-S battery cathode were performed using a laboratory setup as an alternative to more common synchrotron radiation based absorption studies. Photoexcitation by an X-ray tube was used. Valence-to-core Kβ X-ray emission spectra were recorded with a wavelength dispersive crystal spectrometer in von Hamos geometry, providing excellent energy resolution and good detection efficiency.

Protective Coating for Stable Cycling of Li-Metal Batteries Based on Cellulose and Single-Ion Conducting Polymer.

The thermodynamically unstable interface between metallic lithium and electrolyte poses a major problem for the massive commercialization of Li-metal batteries. In this study, we propose the use of a multicomponent protective coating based on cellulose modified with dimethylthexylsilyl group (TDMSC), single-ion conducting polymer P(LiMTFSI), and LiNO (TDMSC-P(LiMTFSI)-LiNO, namely PTL). The coating shows its positive effect by increasing the Coulombic efficiency in Li || Cu cells from 95.

Diffusion and thermodynamic properties of lithium polysulfides in different solvents: a molecular dynamics approach.

Li-S batteries are promising alternatives due to their proven increased gravimetric capacity compared to Li-ion batteries. However, their development is hindered by many technical issues, one of the most challenging being the dissolution and shuttle of polysulfide species, which causes irreversible loss of cathode material leading to rapid capacity fading. Among the possible strategies to mitigate this effect, the choice of suitable solvents is easy to implement and has large room for improvement.

Pivotal Role of Surface Terminations in MXene Thermodynamic Stability.

MXenes, i.e., two-dimensional transition metal carbides and nitrides, have been reported as promising materials for various applications, including energy storage, biomedicine, and electronics.

Design of Organic Cathode Material Based on Quinone and Pyrazine Motifs for Rechargeable Lithium and Zinc Batteries.

Despite the rapid expansion of the organic cathode materials field, we still face a shortage of materials obtained through simple synthesis that have stable cycling and high energy density. Herein, we report a two-step synthesis of a small organic molecule from commercially available precursors that can be used as a cathode material. Oxidized tetraquinoxalinecatechol (OTQC) was derived from tetraquinoxalinecatechol (TQC) by the introduction of additional quinone redox-active centers into the structure.

Organic Cathodes, a Path toward Future Sustainable Batteries: Mirage or Realistic Future?

Organic active materials are seen as next-generation battery materials that could circumvent the sustainability and cost limitations connected with the current Li-ion battery technology while at the same time enabling novel battery functionalities like a bioderived feedstock, biodegradability, and mechanical flexibility. Many promising research results have recently been published. However, the reproducibility and comparison of the literature results are somehow limited due to highly variable electrode formulations and electrochemical testing conditions.

A phenazine-based conjugated microporous polymer as a high performing cathode for aluminium-organic batteries.

One of the possible solutions to circumvent the sluggish kinetics, low capacity, and poor integrity of inorganic cathodes commonly used in rechargeable aluminium batteries (RABs) is the use of redox-active polymers as cathodes. They are not only sustainable materials characterised by their structure tunability, but also exhibit a unique ion coordination redox mechanism that makes them versatile ion hosts suitable for voluminous aluminium cation complexes, as demonstrated by the poly(quinoyl) family. Recently, phenazine-based compounds have been found to have high capacity, reversibility and fast redox kinetics in aqueous electrolytes because of the presence of a CN double bond.

A novel calcium fluorinated alkoxyaluminate salt as a next step towards Ca metal anode rechargeable batteries.

Ca metal anode rechargeable batteries are seen as a sustainable high-energy density and high-voltage alternative to the current Li-ion battery technology due to the low redox potential of Ca metal and abundance of Ca. Electrolytes are key enablers on the path towards next-generation battery systems. Within this work, we synthesize a new calcium tetrakis(hexafluoroisopropyloxy) aluminate salt, Ca[Al(hfip)], and benchmark it the state-of-the-art boron analogue Ca[B(hfip)].

On the nanoscale structural evolution of solid discharge products in lithium-sulfur batteries using operando scattering.

The inadequate understanding of the mechanisms that reversibly convert molecular sulfur (S) into lithium sulfide (LiS) via soluble polysulfides (PSs) formation impedes the development of high-performance lithium-sulfur (Li-S) batteries with non-aqueous electrolyte solutions. Here, we use operando small and wide angle X-ray scattering and operando small angle neutron scattering (SANS) measurements to track the nucleation, growth and dissolution of solid deposits from atomic to sub-micron scales during real-time Li-S cell operation. In particular, stochastic modelling based on the SANS data allows quantifying the nanoscale phase evolution during battery cycling.

Correlating Structural Properties with Electrochemical Behavior of Non-graphitizable Carbons in Na-Ion Batteries.

We report on a detailed structural versus electrochemical property investigation of the corncob-derived non-graphitizable carbons prepared at different carbonization temperatures using a combination of structural characterization methodology unique to this field. Non-graphitizable carbons are currently the most viable option for the negative electrode in sodium-ion batteries. However, many challenges arise from the strong dependence of the precursor's choice and carbonization parameters on the evolution of the carbon matrix and its resulting electrochemistry.

On the Practical Applications of the Magnesium Fluorinated Alkoxyaluminate Electrolyte in Mg Battery Cells.

High-performance electrolytes are at the heart of magnesium battery development. Long-term stability along with the low potential difference between plating and stripping processes are needed to consider them for next-generation battery devices. Within this work, we perform an in-depth characterization of the novel Mg[Al(hfip)] salt in different glyme-based electrolytes.

Sulfur valence-to-core X-ray emission spectroscopy study of lithium sulfur batteries.

In this work, valence-to-core (VtC) Kβ sulfur X-ray emission spectroscopy (XES) was used to perform quantitative analysis of different sulfur compounds produced in a lithium sulfur (Li-S) battery during discharge. The analysis is based on the theoretical sulfur Kβ XES spectra obtained from ab initio quantum chemical calculations based on density functional theory. The emphasis is given to the Kβ sulfur XES spectra of the polysulfide molecules (Li2Sx, x = 2,,8) produced electrochemically within the Li-S battery.

Building Interface Pourbaix diagrams to Investigate Electrolyte Stability in the Electrochemical Double Layer: Application to Magnesium Batteries.

Insights into the electrochemical processes occurring at the electrode-electrolyte interface are a crucial step in most electrochemistry domains and in particular in the optimization of the battery technology. However, studying potential-dependent processes at the interface is one of the biggest challenges, both for theoreticians and experimentalists. The challenge is pushed further when stable species also depend on the concentration of specific ligands in the electrolyte, such as chlorides.

Electrolyte Reactivity in the Double Layer in Mg Batteries: An Interface Potential-Dependent DFT Study.

The electrochemical degradation of two solvent-based electrolytes for Mg-metal batteries is investigated through a grand canonical density functional theory (DFT) approach. Both electrolytes are highly reactive in the double layer region where the solvated species have no direct contact with the Mg-surface, hence emphasizing that surface reactions are not the only phenomena responsible for electrolyte degradation. Applied to dimethoxyethane (DME) and ethylene carbonate (EC), the present methodology shows that both solvents should thermodynamically decompose in the double layer prior to the Mg/Mg reduction, leading to electrochemically inactive reaction products.

Morphology evolution of magnesium facets: DFT and KMC simulations.

One of the crucial steps for the development of batteries is understanding the interface stability and morphological changes occurring during continuous stripping and deposition. In order to investigate the dependence of morphology evolution on surface orientation, we examine the energetics and growth mechanism on magnesium (0001), (101[combining macron]0), (101[combining macron]1), (112[combining macron]0) and (112[combining macron]1) surface orientations using density functional theory and kinetic Monte Carlo simulations. Workfunctions, surface, adsorption and interaction energies, diffusion barriers and k-rates for diffusion via hopping and exchange mechanisms are studied.

Opportunities and Challenges in the Development of Cathode Materials for Rechargeable Mg Batteries.

Recent years have seen an intense and renewed interest in the Mg battery research, naming Mg-S the ≫Holy Grail≪ battery, and expectations that Mg battery system will be able to compete and surpass Li-ion batteries in a matter of years. Considerable progress has been achieved in the field of Mg electrolytes, where several new electrolytes with improved electrochemical performance and favorable chemical properties (non-corrosive, non-nucleophilic) were synthesized. Development in the field of cathodes remains a bit more elusive, with inorganic, sulfur, and organic cathodes all showing their upsides and downsides.

Impact of Structural Polymorphism on Ionic Conductivity in Lithium Copper Pyroborate LiCuBO.

The search for high Li-ion conducting ceramics has regained tremendous interest triggered by the renaissance of the all-solid-state battery. Within this context we herein reveal the impact of structural polymorphism of lithium copper pyroborate LiCuBO on its ionic conductivity. Using combined in situ synchrotron X-ray and neutron powder diffraction, a structural and synthetic relationship between α- and β-LiCuBO could be established and its impact on ionic conductivity evolution was followed using electrochemical impedance spectroscopy.

Fluorinated reduced graphene oxide as a protective layer on the metallic lithium for application in the high energy batteries.

Metallic lithium is considered to be one of the most promising anode materials since it offers high volumetric and gravimetric energy densities when combined with high-voltage or high-capacity cathodes. However, the main impediment to the practical applications of metallic lithium is its unstable solid electrolyte interface (SEI), which results in constant lithium consumption for the formation of fresh SEI, together with lithium dendritic growth during electrochemical cycling. Here we present the electrochemical performance of a fluorinated reduced graphene oxide interlayer (FGI) on the metallic lithium surface, tested in lithium symmetrical cells and in combination with two different cathode materials.

Electrochemical behavior of BiBO towards lithium-reversible conversion reactions without nanosizing.

Conversion type materials, in particular metal fluorides, have emerged as attractive candidates for positive electrodes in next generation Li-ion batteries (LIBs). However, their practical use is being hindered by issues related to reversibility and large polarization. To minimize these issues, a few approaches enlisting the anionic network have been considered.

Reactivity and Diffusivity of Li Polysulfides: A Fundamental Study Using Impedance Spectroscopy.

Polysulfides are central compounds in lithium-sulfur battery cells. However, the fundamental redox and diffusion properties of polysulfides are still poorly understood. We try to fill this gap by performing an accurate impedance spectroscopy investigation using symmetrical cells consisting of two planar glassy carbon electrodes separated with catholyte-soaked separator.