A Stable Quasi-Solid-State Sodium–Sulfur Battery

© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Ambient-temperature sodium–sulfur (Na–S) batteries are considered a promising energy storage system due to their high theoretical energy density and low costs. However, great challenges remain in achieving a high rechargeable capacity and long cycle life. Herein we report a stable quasi-solid-state Na-S battery enabled by a poly(S-pentaerythritol tetraacrylate (PETEA))-based cathode and a (PETEA-tris[2-(acryloyloxy)ethyl] isocyanurate (THEICTA))-based gel polymer electrolyte. The polymeric sulfur electrode strongly anchors sulfur through chemical binding and inhibits the shuttle effect. Meanwhile, the in situ formed polymer electrolyte with high ionic conductivity and enhanced safety successfully stabilizes the Na anode/electrolyte interface, and simultaneously immobilizes soluble Na polysulfides. The as-developed quasi-solid-state Na-S cells exhibit a high reversible capacity of 877 mA h g−1 at 0.1 C and an extended cycling stability

A room-temperature sodium–sulfur battery with high capacity and stable cycling performance

© 2018, The Author(s). High-temperature sodium–sulfur batteries operating at 300–350 °C have been commercially applied for large-scale energy storage and conversion. However, the safety concerns greatly inhibit their widespread adoption. Herein, we report a room-temperature sodium–sulfur battery with high electrochemical performances and enhanced safety by employing a “cocktail optimized” electrolyte system, containing propylene carbonate and fluoroethylene carbonate as co-solvents, highly concentrated sodium salt, and indium triiodide as an additive. As verified by first-principle calculation and experimental characterization, the fluoroethylene carbonate solvent and high salt concentration not only dramatically reduce the solubility of sodium polysulfides, but also construct a robust solid-electrolyte interface on the sodium anode upon cycling. Indium triiodide as redox mediator simultaneously increases the kinetic transformation of sodium sulfide on the cathode and forms a passivating indium layer on the anode to prevent it from polysulfide corrosion. The as-developed sodium–sulfur batteries deliver high capacity and long cycling stability

Immunizing lithium metal anodes against dendrite growth using protein molecules to achieve high energy batteries.

The practical applications of lithium metal anodes in high-energy-density lithium metal batteries have been hindered by their formation and growth of lithium dendrites. Herein, we discover that certain protein could efficiently prevent and eliminate the growth of wispy lithium dendrites, leading to long cycle life and high Coulombic efficiency of lithium metal anodes. We contend that the protein molecules function as a "self-defense" agent, mitigating the formation of lithium embryos, thus mimicking natural, pathological immunization mechanisms. When added into the electrolyte, protein molecules are automatically adsorbed on the surface of lithium metal anodes, particularly on the tips of lithium buds, through spatial conformation and secondary structure transformation from α-helix to β-sheets. This effectively changes the electric field distribution around the tips of lithium buds and results in homogeneous plating and stripping of lithium metal anodes. Furthermore, we develop a slow sustained-release strategy to overcome the limited dispersibility of protein in the ether-based electrolyte and achieve a remarkably enhanced cycling performance of more than 2000 cycles for lithium metal batteries

A versatile functionalized ionic liquid to boost the solution-mediated performances of lithium-oxygen batteries

© 2019, The Author(s). Due to the high theoretical specific energy, the lithium–oxygen battery has been heralded as a promising energy storage system for applications such as electric vehicles. However, its large over-potentials during discharge–charge cycling lead to the formation of side-products, and short cycle life. Herein, we report an ionic liquid bearing the redox active 2,2,6,6-tetramethyl-1-piperidinyloxy moiety, which serves multiple functions as redox mediator, oxygen shuttle, lithium anode protector, as well as electrolyte solvent. The additive contributes a 33-fold increase of the discharge capacity in comparison to a pure ether-based electrolyte and lowers the over-potential to an exceptionally low value of 0.9 V. Meanwhile, its molecule facilitates smooth lithium plating/stripping, and promotes the formation of a stable solid electrolyte interface to suppress side-reactions. Moreover, the proportion of ionic liquid in the electrolyte influences the reaction mechanism, and a high proportion leads to the formation of amorphous lithium peroxide and a long cycling life (> 200 cycles). In particular, it enables an outstanding electrochemical performance when operated in air

Polymer Electrolytes for Lithium-Based Batteries: Advances and Prospects

© 2019 Elsevier Inc. Polymer electrolytes have attracted great interest for next-generation lithium (Li)-based batteries in terms of high energy density and safety. In this review, we summarize the ion-transport mechanisms, fundamental properties, and preparation techniques of various classes of polymer electrolytes, such as solvent-free polymer electrolytes (SPEs), gel polymer electrolytes (GPEs), and composite polymer electrolytes (CPEs). We also introduce the recent advances of non-aqueous Li-based battery systems, in which their performances can be intrinsically enhanced by polymer electrolytes. Those include high-voltage Li-ion batteries, flexible Li-ion batteries, Li-metal batteries, lithium-sulfur (Li-S) batteries, lithium-oxygen (Li-O2) batteries, and smart Li-ion batteries. Especially, the advantages of polymer electrolytes beyond safety improvement are highlighted. Finally, the remaining challenges and future perspectives are outlined to provide strategies to develop novel polymer electrolytes for high-performance Li-based batteries. The progress of lithium (Li)-based batteries has been greatly hindered by the safety issues originating from traditional non-aqueous liquid electrolytes. As alternatives of liquid electrolytes, polymer electrolytes have attracted great attention because of their merits such as low flammability, flexible processability, and more tolerance to vibration, shock, and mechanical deformation. Recently, the applications of polymer electrolytes in fields such as high-voltage Li-ion batteries, flexible Li-ion batteries, Li-metal batteries, Li-sulfur batteries, Li-oxygen batteries, and smart Li-ion batteries have inspired new research enthusiasm in both electrochemistry and material science communities. This review presents a survey of emerging polymer electrolytes, including solvent-free polymer electrolytes, gel polymer electrolytes, and composite polymer electrolytes, and highlights their recent developments in Li-based battery applications

Electrochemical studies on LiFe<inf>1-x</inf>Co<inf>x</inf>PO<inf>4</inf>/carbon composite cathode materials synthesized by citrate gel technique for lithium-ion batteries

LiFePO4/carbon and LiFe1-xCoxPO4/carbon (x = 0.02, 0.04, 0.08 and 0.1) composite cathode materials were synthesized by citrate gel technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to study the phase and morphology of un-doped and Co doped lithium iron phosphate/carbon composites. The SEM images revealed that the particles were agglomerated and the particle sizes were almost homogeneously distributed. The particle size was found to be between 200 and 300 nm from transmission electron microscopy. Cyclic voltammetric studies were taken to investigate the electrochemical performance of the prepared composite materials. The high intensity of the anodic and cathodic peaks indicates that Li-ions and electrons were participating actively in redox reactions due to the carbon coating. Charge/discharge studies carried out on a CR2032 coin cell revealed that the carbon coated LiFePO4/carbon composite exhibited an improved discharge capacity of 157 mAh/g at low rates. We found that cobalt doping does not have a favourable effect on the electrochemical performance of lithium iron phosphate cathode materials. © 2008 Elsevier B.V. All rights reserved

Synthesis and characterization of SrBi<inf>4</inf>Ti<inf>4</inf>O <inf>15</inf> ferroelectric filler based composite polymer electrolytes for lithium ion batteries

Composite polymer electrolytes (CPEs) based on poly (ethylene oxide) (PEO) (Mol.Wt ∼ 6×105) complexed with LiN(CF3SO 2)2 lithium salt and SrBi4Ti4O 15 ferroelectric ceramic filler have been prepared as films. Citrate gel technique and conventional solid state technique were employed for the synthesis of the ferroelectric fillers in order to study the effect of particle size of the filler on ionic conductivity of the polymer electrolyte. Characterization techniques such as X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM) and temperature dependant DC conductivity studies were taken for the prepared polymer composite electrolytes. The broadening of DTA endotherms on addition of ceramic fillers to the polymer salt complex indicated the reduction in crystallinity. An enhancement in conductivity was observed with the addition of SrBi 4Ti4O15 as filler to the (PEO) 8-LiN(CF3SO2)2 polymer salt complexes. Among the investigated samples (PEO)8-LiN(CF 3SO2)2 +10 wt% SrBi4Ti 4O15 (citrate gel) polymer composite exhibits a maximum conductivity. © 2007 Springer-Verlag

Ionic conductivity and electrochemical stability of poly(methylmethacrylate)-poly(ethylene oxide) blend-ceramic fillers composites

The role of inorganic ceramic fillers namely nanosized Al2O3 (15-25 nm) and TiO2 (10-14 nm) and ferroelectric filler SrBi4Ti4O15 (SBT CIT) (0.5 μm) synthesized by citrate gel technique (CIT) on the ionic conductivity and electrochemical properties of polymer blend 15 wt% PMMA+PEO8:LiClO4+2 wt% EC/PC electrolytes were investigated. Enhancement in conductivity was obtained with a maximum of 0.72×10-5 S cm-1 at 21 °C for 2 wt% of SrBi4Ti4O15 (SBT CIT) composite polymer electrolyte. The lithium-ion transport number and the electrochemical stability of the composite polymer electrolytes at ambient temperature were analyzed. An enhancement in electrochemical stability was observed for polymer composites containing 2 wt% of SrBi4Ti4O15 (SBT CIT) as fillers. © 2007 Elsevier Ltd. All rights reserved

Electrode Materials for Sodium-Ion Batteries: Considerations on Crystal Structures and Sodium Storage Mechanisms

Abstract: Sodium-ion batteries have been emerging as attractive technologies for large-scale electrical energy storage and conversion, owing to the natural abundance and low cost of sodium resources. However, the development of sodium-ion batteries faces tremendous challenges, which is mainly due to the difficulty to identify appropriate cathode materials and anode materials. In this review, the research progresses on cathode and anode materials for sodium-ion batteries are comprehensively reviewed. We focus on the structural considerations for cathode materials and sodium storage mechanisms for anode materials. With the worldwide effort, high-performance sodium-ion batteries will be fully developed for practical applications. Graphical Abstract: [Figure not available: see fulltext.