Simulations of γ-Valerolactone Solvents and Electrolytes for Lithium Batteries Using Polarizable Molecular Dynamics.

In this paper, we present a molecular dynamics study of the structural and dynamical properties of γ-valerolactone (GVL) both as a standalone solvent and in electrolyte formulations for electrochemistry applications. This study involves developing a new parameterization of a polarizable forcefield and applying it to simulate pure GVL and selected salt solutions. The forcefield was validated with experimental bulk data and quantum mechanical calculations, with excellent agreement obtained in both cases.

Formulation and Recycling of a Novel Electrolyte Based on Bio-Derived γ-Valerolactone and Lithium Bis(trifluoromethanesulfonyl)imide for Lithium-Ion Batteries.

This work introduces a novel electrolyte comprising lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt dissolved in bio-based γ-valerolactone (GVL) for lithium-ion batteries (LIBs). Moreover, a simple and sustainable aqueous-based recycling approach for recovering the imide-based lithium salt is proposed. Beyond the sustainable origin of the GVL solvent, this electrolyte exhibits reduced flammability risk, characterized by a flash point of 136 °C, along with favorable transport properties (conductivity of 6.

A Polarizable Forcefields for Glyoxal Acetals as Electrolyte Components for Lithium-Ion Batteries.

In this work we have derived the parameters of an AMOEBA-like polarizable forcefield for electrolytes based on tetramethoxy and tetraethoxy-glyoxal acetals, and propylene carbonate. The resulting forcefield has been validated using both ab-initio data and the experimental properties of the fluids. Using molecular dynamics simulations, we have investigated the structural features and the solvation properties of both the neat liquids and of the corresponding 1 M LiTFSI electrolytes at the molecular level.

Coordination and Diffusion in Glyoxal-Based Electrolytes for Potassium-Ion Batteries.

Glyoxal-based electrolytes have been identified as promising for potassium-ion batteries (PIBs). Here we investigate the properties of electrolytes containing potassium bis(fluorosulfonyl)imide (KFSI) in 1,1,2,2-tetra-ethoxy-ethane (tetra-ethyl-glyoxal, TEG) using density functional theory (DFT) calculations, Raman spectroscopy, and impedance spectroscopy. The coordination and configuration of the complexes possible to arise from coordination of the K ions by FSI and TEG were investigated both from an energetic point of view as well as qualitatively determined via comparing experimental and artificial Raman spectra.

Understanding the Role of Imide-Based Salts and Borate-Based Additives for Safe and High-Performance Glyoxal-Based Electrolytes in Ni-Rich NMC Cathodes for Li-Ion Batteries.

Herein, the design of novel and safe electrolyte formulations for high-voltage Ni-rich cathodes is reported. The solvent mixture comprising 1,1,2,2-tetraethoxyethane and propylene carbonate not only displays good transport properties, but also greatly enhances the overall safety of the cell thanks to its low flammability. The influence of the conducting salts, that is, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluorosulfonyl)imide (LiFSI), and of the additives lithium bis(oxalato)borate (LiBOB) and lithium difluoro(oxalato)borate (LiDFOB) is examined.

Fluorine-Free Lithium-Ion Capacitor with Enhanced Sustainability and Safety Based on Bio-Based ƴ-Valerolactone and Lithium Bis(Oxalato)Borate Electrolyte.

In this work, the properties of a novel electrolyte based on the combination of bio-based ƴ-valerolactone (GVL) solvent with lithium bis(oxalato)borate (LiBOB) salt and its use for lithium-ion capacitors (LICs) are presented. It is shown that the 1 m LiBOB in GVL electrolyte displays good transport properties, high thermal stability, and the ability to prevent anodic dissolution. Its impact on the performance of both battery-type and capacitive-type electrodes is evaluated.

The "In situ electrolyte" as a sustainable alternative for the realization of high-power devices.

The "in situ electrolyte" displays a concept for electric double-layer- as well as metal-ion capacitors in which the by-products formed during carbon synthesis serve directly as electrolyte salt to minimize waste. In this work, the concept is applied for lithium- and sodium-based systems realizing EDLCs containing aqueous, "Water in Salt" (up to 1.8 V) as well as organic (2.

Improving the performance of an anionic MOF by counter cation replacement as electrode material in a full cell setup of a potassium ion capacitor.

Potassium-based energy storage devices are attracting increasing attention as an alternative to lithium and sodium systems. In addition, metal-organic frameworks (MOFs) can be considered as promising electrode materials for this type of device due to their advantageous properties. Herein, the anionic MOF JUMP-1 and its analog with pre-loading of potassium cations, namely JUMP-1(K), were synthesized and characterized.

Glyoxylic-Acetal-Based Electrolytes for Sodium-Ion Batteries and Sodium-Ion Capacitors.

A comprehensive study on the properties and implementation of glyoxylic-acetals in sodium-ion energy storage systems is presented. Electrolytes containing 1,1,2,2-tetramethoxyethane (tetramethoxyglyoxal, TMG), 1,1,2,2-tetraethoxyethane (tetraethoxyglyoxal, TEG) and a mixture of the latter with propylene carbonate (PC) exhibit increased thermal stabilities and higher flash points compared to classical electrolytes based on carbonates as solvents. Due to its favorable properties, 1 m NaTFSI in TEG/PC (3 : 7), has been selected and used for sodium-ion energy storage systems based on a Prussian Blue (PB) positive electrode and a hard carbon (HC) negative electrode.

γ-Valerolactone as Sustainable and Low-Toxic Solvent for Electrical Double Layer Capacitors.

In this work, γ-valerolactone (GVL), a green solvent based on largely available biomass (carbohydrates), highly biodegradable, and with low eco-toxicological profile, was used as electrolyte component in energy storage devices. This solvent allowed the realization of electrolytes with good transport properties and high thermal stability, which could be successfully applied in electrical double layer capacitors (EDLCs). GVL-based EDLCs could operate at 2.

Enhancing Capacity and Stability of Anionic MOFs as Electrode Material by Cation Exchange.

In this study we report on the characterization and use of the anionic metal-organic framework (MOF) JUMP-1, [(MeNH)[Co(ntb)(bdc)]] , alongside with its alkali-metal ion-exchanged analogs JUMP-1(Li) and JUMP-1(Na), as electrode materials for lithium and sodium batteries. Composite electrodes containing these anionic-MOFs were prepared and tested in 1 M lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) in propylene carbonate (PC) and/or 1 M sodium TFSI (NaTFSI) in PC. We showed that the ion-exchanged materials JUMP-1(Li) and JUMP-1(Na) display higher capacities in comparison with the original as-prepared compound JUMP-1 (490 mA∙h∙g vs.

Hybrid Polyethylene Glycol/Sodium Metaphosphate Composites Prepared via Coacervation.

We report on the fabrication and characterization of homogeneous, monophasic sodium metaphosphate and polyethylene glycol hybrid composites achieved via coacervation in aqueous solution. After separation and drying, an amorphous plastic solid is formed, composed mostly of hydrated sodium phosphate moieties amalgamated with polyethylene glycol chains. These composites are largely X-ray amorphous and can contain up to 8 weight percent of polymer.

New Diglyme-based Gel Polymer Electrolytes for Na-based Energy Storage Devices.

This work presents for the first time a new diglyme-based gel polymer (DOBn-GPE) suitable for Na-based energy storage devices. The DOBn-GPE, which contains a methacrylate-based polymer, exhibited an excellent high ionic conductivity (2.3 mS cm at 20 °C), broad electrochemical stability (>5.

Water in Protic Ionic Liquid Electrolytes: From Solvent Separated Ion Pairs to Water Clusters.

The large electrochemical and cycling stability of "water-in-salt" systems have rendered promising prospective electrolytes for batteries. The impact of addition of water on the properties of ionic liquids has already been addressed in several publications. In this contribution, we focus on the changes in the state of water.

Emulsion Polymerizations for a Sustainable Preparation of Efficient TEMPO-based Electrodes.

Organic polymer-based batteries represent a promising alternative to present-day metal-based systems and a valuable step toward printable and customizable energy storage devices. However, most scientific work is focussed on the development of new redox-active organic materials, while straightforward manufacturing and sustainable materials and production will be a necessary key for the transformation to mass market applications. Here, a new synthetic approach for 2,2,6,6-tetramethyl-4-piperinidyl-N-oxyl (TEMPO)-based polymer particles by emulsion polymerization and their electrochemical investigation are reported.

Silica based ionogels: interface effects with aprotic and protic ionic liquids with lithium.

In the frame of the development of solid ionogel electrolytes with enhanced ion transport properties, this paper investigates ionogel systems constituted by ∼80 wt% of ionic liquids (ILs) confined in meso-/macroporous silica monolith materials. The anion-cation coordination for two closely related ILs, either aprotic (AIL) butylmethylpyrrolidinium or protic (PIL) butylpyrrolidinium, both with bis(trifluoromethylsulfonyl)imide (TFSI) anions, with and without lithium cations, is studied in depth. The ILs are confined within silica with well-defined mesoporosities (8 to 16 nm).

Polyimide@Ketjenblack Composite: A Porous Organic Cathode for Fast Rechargeable Potassium-Ion Batteries.

Potassium-ion batteries (PIBs) configurated by organic electrodes have been identified as a promising alternative to lithium-ion batteries. Here, a porous organic Polyimide@Ketjenblack is demonstrated in PIBs as a cathode, which exhibits excellent performance with a large reversible capacity (143 mAh g at 100 mA g ), high rate capability (125 and 105 mAh g at 1000 and 5000 mA g ), and long cycling stability (76% capacity retention at 2000 mA g over 1000 cycles). The domination of fast capacitive-like reaction kinetics is verified, which benefits from the porous structure synthesized using in situ polymerization.

A Comparative Review of Electrolytes for Organic-Material-Based Energy-Storage Devices Employing Solid Electrodes and Redox Fluids.

Electrolyte chemistry is critical for any energy-storage device. Low-cost and sustainable rechargeable batteries based on organic redox-active materials are of great interest to tackle resource and performance limitations of current batteries with metal-based active materials. Organic active materials can be used not only as solid electrodes in the classic lithium-ion battery (LIB) setup, but also as redox fluids in redox-flow batteries (RFBs).

Water in Protic Ionic Liquids: Properties and Use of a New Class of Electrolytes for Energy-Storage Devices.

In this work, the properties of "water-in-PIL" (PIL=protic ionic liquid) electrolytes are reported based on 1-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr TFSI). Taking advantage of experimental and theoretical investigations, it is shown that the amount of water inside the electrolyte has a dramatic effect on the viscosity, conductivity, density, cation-anion interplay, and electrochemical stability of Pyr TFSI. The impact of water on the properties of this ionic liquid also affects its use as an electrolyte for electrochemical double-layer capacitors (EDLCs).

The impact of carbonate solvents on the self-discharge, thermal stability and performance retention of high voltage electrochemical double layer capacitors.

Advanced electrolytes for supercapacitors with high electrochemical stability are necessary to improve the suitability of supercapacitors for many applications. In this work we investigated electrolytes based on the solvent propylene carbonate (PC) and butylene carbonate (BC). A comparison of different solvent-salt combinations shows that 1 M N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI) in BC is superior to conventionally used PC-based electrolytes examined in this work in terms of voltage window and capacitance.

Molecular Dynamics Simulations of Lithium-Doped Ionic-Liquid Electrolytes.

Lithium bis(trifluoromethanesulfonyl)imide (LiNTf) doped ionic liquids (ILs) are investigated herein, as potential electrolytes for lithium-ion batteries, via scaled-charge molecular dynamics simulations. Four model ILs based on the [NTf] anion and heterocyclic ammonium cations were studied with varying concentrations, ranging from 0 to 1 M solutions, of the dissolved lithium salt. The pyrrolidinium ([pyrHH]), piperidinium ([pipHH]), N-butyl-pyrrolidinium ([pyrH4]), and N-butyl- N-methyl-pyrrolidinium ([pyr14]) cations were considered to evaluate the combined effects of increased ring size, as well as the introduction of apolar groups on the nitrogen atom of the cations, on the liquid structure properties of the electrolytes.

Preface to Special Issue of ChemSusChem on Interfacing Experiment and Theory in the Development of Energy Storage and Devices.

This Editorial discusses the importance of scientists currently working in separate fields-experimental characterization of novel materials and theoretical investigations of electrochemical processes-joining forces to advance the field of energy-storage materials and devices. Some of these efforts are published in this Special Issue by ChemSusChem.

Glyoxal-Based Solvents for Electrochemical Energy-Storage Devices.

In this work an investigation about the use of the solvents 1,1,2,2-tetramethoxyethane, also called tetramethoxy glyoxal (TMG), and 1,1,2,2-tetraethoxyethane [also called tetraethoxy glyoxal (TEG)], which belong to the chemical family of carbonyl derivatives, as electrolyte components for electrical double layer capacitors (EDLCs) and lithium-ion batteries (LIBs) is reported for the first time. TEG and TMG are commercial solvents displaying a good set of properties, a low toxicity, and a low price. Although for EDLCs the use of these solvents does appear particularly appealing, their use in LIBs is certainly interesting.

Anodic Dissolution of Al Current Collectors in Unconventional Solvents for High Voltage Electrochemical Double-Layer Capacitors.

This study investigated the anodic dissolution of Al current collectors in unconventional electrolytes for high voltage electrochemical double-layer capacitors (EDLCs) containing adiponitrile (ADN), 3-cyanopropionic acid methyl ester (CPAME), 2-methyl-glutaronitrile (2-MGN) as solvent, and tetraethylammonium tetrafluoroborate (Et NBF ) and tetraethylammonium bis(trifluoromethanesulfonyl)imide (Et NTFSI) as conductive salts. To have a comparison with the state-of-the-art electrolytes, the same salts were also used in combination with acetonitrile (ACN). The chemical-physical properties of the electrolytes were investigated.