Ionogel hybrid polymer electrolytes encompassing room-temperature ionic liquids for 4V-class Li-metal batteries operating at ambient temperature

In this study, we prepare ionogels composed of bisphenol A ethoxylate dimethacrylate, poly(ethylene glycol) methyl ether methacrylate, lithium bis(trifluoromethanesulfonyl)imide, and 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide or 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ionic liquids via rapid, scalable, solvent-free UV-induced polymerization.The various hybrid polymer electrolyte formulations are thoroughly characterized using acomprehensive set of physico-chemical and electrochemical methods, including gel content,FTIR, rheology, DTMA, TGA, SEM, cycling voltammetry, impedance spectroscopy, andgalvanostatic cycling in laboratory-scale Li-metal cells. We particularly focus on the influence ofusing two different ionic liquids as reaction medium on the properties of the resulting materialsand their electrochemical behaviors. Our results indicate that viscosity affects thepolymerization kinetics of the ionogels, which in turn might affect their thermal stability andgalvanostatic cycling behavior. In the purpose of promoting overall performance of solid-statebatteries, we also present the results of composite electrolytes obtained by introducingLi7La3Zr2O12(LLZO) into ionogels and followingin-situUV-polymerisation. The addition of LLZOceramic results in more porous solid networks, leading to enhanced charge/discharge stabilityat ambient temperature and higher C-rates featuring 4V-class NMC cathodes, enlightening thepromising prospects of the developed materials to be successfully implemented as stable,durable, and efficient electrolytes in next-generation Li-metal cells

Exceptional long-life performance of lithium-ion batteries using ionic liquid-based electrolytes

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Advanced ionic liquid-based electrolytes are herein characterized for application in high performance lithium-ion batteries. The electrolytes based on either N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (Pyr(14)TFSI), N-butyl-N-methylpyrrolidinium bis(fluoro-sulfonyl) imide (Pyr(14)FSI), N-methoxy-ethyl-N-methylpyrrolidinium bis(trifluoromethane-sulfonyl) imide (Pyr(12O1)TFSI) or N-N-diethyl-N-methyl-N-(2methoxyethyl) ammonium bis(trifluoromethanesulfonyl) imide (DEMETFSI) ionic liquids and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt are fully characterized in terms of ionic conductivity, viscosity, electrochemical properties and lithium-interphase stability. All IL-based electrolytes reveal suitable characteristics for application in batteries. Lithium half-cells, employing a LiFePO4 polyanionic cathode, show remarkable performance. In particular, relevant efficiency and rate-capability are observed for the Py14FSI-LiTFSI electrolyte, which is further characterized for application in a lithium-ion battery composed of the alloying Sn-C nanocomposite anode and LiFePO4 cathode. The IL-based full-cell delivers a maximum reversible capacity of about 160 mA h g(-1) (versus cathode weight) at a working voltage of about 3 V, corresponding to an estimated practical energy of about 160 W h kg(-1). The cell evidences outstanding electrochemical cycle life, i.e., extended over 2000 cycles without signs of decay, and satisfactory rate capability. This performance together with the high safety provided by the IL-electrolyte, olivine-structure cathode and Li-alloying anode, makes this cell chemistry well suited for application in new-generation electric and electronic devices

A Direct Real-Time Observation of Anion Intercalation in Graphite Process and Its Fully Reversibility by SAXS/WAXS Techniques

The process of anion intercalation in graphite and its reversibility plays a crucial role in the next generation energy-storage devices. Herein the reaction mechanism of the aluminum graphite dual ion cell by operando X-ray scattering from small angles to wide angles is investigated. The staging behavior of the graphite intercalation compound (GIC) formation, its phase transitions, and its reversible process are observed for the first time by directly measuring the repeated intercalation distance, along with the microporosity of the cathode graphite. The investigation demonstrates complete reversibility of the electrochemical intercalation process, alongside nano- and micro-structural reorganization of natural graphite induced by intercalation. This work represents a new insight into thermodynamic aspects taking place during intermediate phase transitions in the GIC formation

Highly Concentrated KTFSI : Glyme Electrolytes for K/Bilayered‐V₂O₅ Batteries

Highly concentrated glyme‐based electrolytes are friendly to a series of negative electrodes for potassium‐based batteries, including potassium metal. However, their compatibility with positive electrodes has been rarely explored. In this work, the influence of the molar fraction of potassium bis(trifluoromethanesulfonyl)imide dissolved in glyme on the cycling ability of K/bilayered‐V2O5 batteries has been investigated. At high salt concentration, the interaction between K+ ions with the glyme is strengthened, leading to a limited number of free glyme molecules. Therefore, the anodic decomposition of the electrolyte solvent, as well as the dissolution of the Al current collectors, is effectively suppressed, resulting in the improved cycling ability of the K/bilayered‐V2O5 cells. In these cells, the positive electrode active material exhibits reversible capacities of 93 and 57 mAh g−1 at specific current densities of 50 and 1000 mA g−1, respectively. After 200 charge‐discharge cycles at 500 mA g−1, the cell retains 94 % of the initial capacity. The promising rate performance and capacity retention demonstrate the importance of proper electrolyte engineering for the K/bilayered‐V2O5 batteries, and the good compatibility of highly concentrated glyme‐based electrolytes with positive electrode materials for potassium batteries

Highly concentrated KTFSI: Glyme electrolytes for K/bilayered-V2O5 batteries

Highly concentrated glyme-based electrolytes are friendly to a series of negative electrodes for potassium-based batteries, including potassium metal. However, their compatibility with positive electrodes has been rarely explored. In this work, the influence of the molar fraction of potassium bis(trifluoromethanesulfonyl)imide dissolved in glyme on the cycling ability of K/bilayered-V2O5 batteries has been investigated. At high salt concentration, the interaction between K+ ions with the glyme is strengthened, leading to a limited number of free glyme molecules. Therefore, the anodic decomposition of the electrolyte solvent, as well as the dissolution of the Al current collectors, is effectively suppressed, resulting in the improved cycling ability of the K/bilayered-V2O5 cells. In these cells, the positive electrode active material exhibits reversible capacities of 93 and 57 mAh g−1 at specific current densities of 50 and 1000 mA g−1, respectively. After 200 charge-discharge cycles at 500 mA g−1, the cell retains 94 % of the initial capacity. The promising rate performance and capacity retention demonstrate the importance of proper electrolyte engineering for the K/bilayered-V2O5 batteries, and the good compatibility of highly concentrated glyme-based electrolytes with positive electrode materials for potassium batteries. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA

Sustainable conversion of vine shoots and pig manure into high-performance anode materials for sodium-ion batteries

Sodium-ion batteries (SIBs) are considered promising candidates for future grid energy storage, with hard carbons emerging as key commercial anode materials. This study presents a novel approach to synthesize N-doped hard carbons via co-hydrothermal treatment of vine shoots and pig manure and subsequent thermal annealing of the resulting hydrochar. This method enhances the development of micro- and ultra-microporosity in the synthesized hard carbons, with nitrogen, and to a lesser extent phosphorus and sulfur, introduced as doping elements. Furthermore, the incorporation of hydrochloric acid during the hydrothermal step promotes biomass hydrolysis, leading to increased mesoporosity and the formation of microsphere clusters. In the realm of electrochemical performance, an investigation into various ester- and ether-based electrolytes has revealed NaPF 6 in diglyme as the best formulation, thanks to its thinner and more stable solid electrolyte interface (SEI). Using this electrolyte, the best-performing electrode showed an initial Coulombic efficiency (ICE) of 73 %, with reversible capacities of 239, 180, 86, and 57 mAh g-1 at 0.1, 1, 5, and 10 A g-1 , respectively. In addition, the electrode exhibited a remarkable capacity retention of 88 % after 250 cycles as well as a compatible behavior when paired with a NVPF-based cathode

Operando pH Measurements Decipher H⁺/Zn²⁺ Intercalation Chemistry in High-Performance Aqueous Zn/δ-V₂O₅ Batteries

Vanadium oxides have been recognized to be among the most promising positive electrode materials for aqueous zinc metal batteries (AZMBs). However, their underlying intercalation mechanisms are still vigorously debated. To shed light on the intercalation mechanisms, high-performance δ-V2O5 is investigated as a model compound. Its structural and electrochemical behaviors in the designed cells with three different electrolytes, i.e., 3 m Zn(CF3SO3)2/water, 0.01 M H2SO4/water, and 1 M Zn(CF3SO3)2/acetonitrile, demonstrate that the conventional structural and elemental characterization methods cannot adequately clarify the separate roles of H+ and Zn2+ intercalations in the Zn(CF3SO3)2/water electrolyte. Thus, an operando pH determination method is developed and used toward Zn/δ-V2O5 AZMBs. This method indicates the intercalation of both H+ and Zn2+ into δ-V2O5 and uncovers an unusual H+/Zn2+-exchange intercalation–deintercalation mechanism. Density functional theory calculations further reveal that the H+/Zn2+ intercalation chemistry is a consequence of the variation of the electrochemical potential of Zn2+ and H+ during the electrochemical intercalation/release

The Behavior of the Intercalant AlCl_4 Anion during the Formation of Graphite Intercalation Compound: An X-ray Absorption Fine Structure Study

This work aims to study the insertion of AlCl_4^- anion in the crystalline structure of oriented pyrolytic graphite (PG) at the point of view of the anion itself. The electronic and atomic structures of the anion at different intercalation stages are studied. In particular double-edge (bicolor) X-ray absorption spectroscopy at the Al and Cl K-edges is carried out, highlighting a contraction of the anion bonding at the highest intercalation degree obtained electrochemically (stage 3), while the electronic population changes for both the edges upon cycle

Nanostructured tin-carbon/ LiNi0.5Mn1.5O4 lithium-ion battery operating at low temperature

An advanced lithium ion battery using nanostructured tinecarbon lithium alloying anode and a high voltage LiNi0.5Mn1.5O4 spinel-type cathode is studied, with particular focus to the low temperature range. The stable behavior of the battery is assured by the use of an electrolyte media based on a LiPF6 salt dissolved in EC-DEC-DMC, i.e. a mixture particularly suitable for the low temperature application. Cycling tests, both in half cells and in full lithium ion battery using the SneC anode and the LiNi0.5Mn1.5O4 cathode, performed in a temperature range extending from room temperature to "30 C, indicate that the electrode/electrolyte configuration here adopted may be suitable for effective application in the lithium ion battery field. The full cell, cycled at -5 °C, shows stable capacity of about 105 mAh g-1 over more than 200 chargee-discharge cycles that is considered a relevant performance considering the low temperature region