Fluoride-ion batteries: a comprehensive review.

Lithium‐ion batteries (LIBs) are promising candidates within the context of the development of novel battery concepts with high energy densities. Batteries with high operating potentials or high voltage (HV) LIBs (>4.2 V vs Li+/Li) can provide high energy densities and are therefore attractive in high‐performance LIBs. However, a variety of challenges (including solid electrolyte interface (SEI), lithium plating, etc.) and related safety issues (such as gas formation or thermal runaway effects) must be solved for the practical, widespread application of HV‐LIBs. Most of these challenges arise in the region between the electrodes: the electrolyte region. This review provides an overview of recent development and progress on the electrolyte region, including liquid electrolytes, ionic liquids, gel polymer electrolytes, separators, and solid electrolytes for HV‐LIBs applications. A focus on improving the safety of these systems, with some perspectives on their relative cost and environmental impact, is given. Overall, the new information is encouraging for the development of HV‐LIBs, and this review serves as a guide for potential strategies to improve their safety, allowing the development of HV‐LIBs, including solid‐state batteries, to be accelerated to practical relevance.

Batteries are the backbones of the sustainable energy transition for stationary off-grid, portable electronic devices, and plug-in electric vehicle applications. Both lithium-ion batteries (LIBs) and sodium-ion batteries (NIBs), most commonly rely on carbon-based anode materials and are usually derived from non-renewable sources such as fossil deposits. Biomass-derived carbon materials are extensively researched as efficient and sustainable anode candidates for LIBs and NIBs. The main purpose of this perspective is to brief the use of biomass residues for the preparation of carbon anodes for LIBs and NIBs annexed to the biomass-derived carbon physicochemical structures and their aligned electrochemical properties. In addition, an outlook and some challenges faced in this promising area of research is presented. This review enlightens the readers with valuable insights and a reasonable understanding of issues and challenges faced in the preparation, physicochemical properties, and application of biomass-derived carbon materials as anode candidates for LIBs and NIBs.

Calcium fluoride is widely investigate known to be a promising solid material for optics, electronics, and electrochemistry. In this work, we report the successful preparation of calcium fluoride with enhanced defect structure obtained by the application of vapor pressure followed by high-energy ball milling, creating CaF 2 nano-powder, achieving increased ionic conductivities in the order of 1.9 · 10 −5 S·cm −1 at room temperature relying on fluoride surface interstitial defect with an activation energy of 0.35 eV. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR), and electron paramagnetic resonance (EPR). It is revealed that the calcium fluoride electrolyte keeps in its basic cubic structure, becomes nano-powdered material with crystallite/ particle size of 12/30 nm. Surface defect structures are enhanced, which is visible with XPS, NMR, and EPR spectroscopy. The synthesized material provided considerable ionic conductivity enhancement introducing attraction for electrochemical testing for fluoride-ion batteries (FIB). KEYWORDSball milling, calcium fluoride, fluoride-ion battery, fluoride shuttle sensors, ionic conductivity, NMR, solid-state electrolyte

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