Query: solid electrolyte

title: Fluorinated hybrid solid electrolyte interphase for dendrite free lithium deposition
abstract: Lithium metal anodes have attracted extensive attention owing to their high theoretical specific capacity. However, the notorious reactivity of lithium prevents their practical applications, as evidenced by the undesired lithium dendrite growth and unstable solid electrolyte interphase formation. Here, we develop a facile, cost effective and one step approach to create an artificial lithium metal/electrolyte interphase by treating the lithium anode with a tin containing electrolyte. As a result, an artificial solid electrolyte interphase composed of lithium fluoride, tin, and the tin lithium alloy is formed, which not only ensures fast lithium ion diffusion and suppresses lithium dendrite growth but also brings a synergistic effect of storing lithium via a reversible tin lithium alloy formation and enabling lithium plating underneath it. With such an artificial solid electrolyte interphase, lithium symmetrical cells show outstanding plating/stripping cycles, and the full cell exhibits remarkably better cycling stability and capacity retention as well as capacity utilization at high rates compared to bare lithium.Here the authors report a simple method to create a solid electrolyte interphase that is tightly anchored onto the surface of lithium metal anode. This artificial structure suppresses dead and dendrite Li and stores Li via formation of alloys, enabling impressive battery performance.

title: Liquid phase therapy to solid electrolyte electrode interface in solid state Li metal batteries: A review
abstract: Solid state lithium (Li) metal batteries, employing solid electrolytes, with high energy density and enhanced safety are promising choices for next generation electrochemical energy storage devices. However, the large interfacial resistances seriously hinder their commercialization. To construct a conformal interface with acceptable resistances, introducing small amounts of additional liquid electrolytes is one of the most convenient and effective solutions. This review summarizes the fundamental understandings on the interfacial behaviors between liquid electrolytes, electrodes and solid state electrolytes. Afterwards, emerging strategies are discussed, involving interfacial wetting, in situ polymerization and interfacial reactions. Finally, current limitations and perspectives are presented for liquid phase therapy regarding the interfacial science and engineering.

title: Polymer inorganic solid electrolyte interphase for stable lithium metal batteries under lean electrolyte conditions
abstract: The solid electrolyte interphase (SEI) is pivotal in stabilizing lithium metal anodes for rechargeable batteries. However, the SEI is constantly reforming and consuming electrolyte with cycling. The rational design of a stable SEI is plagued by the failure to control its structure and stability. Here we report a molecular level SEI design using a reactive polymer composite, which effectively suppresses electrolyte consumption in the formation and maintenance of the SEI. The SEI layer consists of a polymeric lithium salt, lithium fluoride nanoparticles and graphene oxide sheets, as evidenced by cryo transmission electron microscopy, atomic force microscopy and surface sensitive spectroscopies. This structure is different from that of a conventional electrolyte derived SEI and has excellent passivation properties, homogeneity and mechanical strength. The use of the polymer inorganic SEI enables high efficiency Li deposition and stable cycling of 4 V Li|LiNi0.5Co0.2Mn0.3O2 cells under lean electrolyte, limited Li excess and high capacity conditions. The same approach was also applied to design stable SEI layers for sodium and zinc anodes.Solid electrolyte interphase is crucial for stabilizing lithium metal anodes for rechargeable batteries. A molecular level design using a reactive polymer composite is now shown to effectively construct a stable SEI layer and suppress electrolyte consumption upon cycling.

title: Enhancing interfacial contact in all solid state batteries with a cathode supported solid electrolyte membrane framework
abstract: To address the challenge of interfacial contact between the solid electrolyte and electrode with a cost efficient solution, we demonstrate a novel cathode supported solid electrolyte membrane framework for advanced all solid state Li ion batteries. The solid electrolyte is directly cast on the cathode layer to enhance the wetting ability of solid electrolyte onto the cathode and reinforce the interfacial adhesion. Results show that the as fabricated LiFePO4/Li solid state battery displays superior battery performances, e.g. an initial discharge capacity of 125 mA h g 1 at 0.1C at room temperature can be achieved. The proposed electrolyte framework represents a promising strategy for mass production of high performance all solid state batteries based on Li metal anodes.

title: Lithium matrix composite anode protected by a solid electrolyte layer for stable lithium metal batteries
abstract: Lithium (Li) metal with an ultrahigh specific theoretical capacity and the lowest reduction potential is strongly considered as a promising anode for high energy density batteries. However, uncontrolled lithium dendrites and infinite volume change during repeated plating/stripping cycles hinder its practical applications immensely. Herein, a house like Li anode (housed Li) was designed to circumvent the above issues. The house matrix was composed of carbon fiber matrix and affords a stable structure to relieve the volume change. An artificial solid electrolyte layer was formed on composite Li metal, just like the roof of a house, which facilitates uniform Li ions diffusion and serves as a physical barrier against electrolyte corrosion. With the combination of solid electrolyte layer and matrix in the composite Li metal anode, both dendrite growth and volume expansion are remarkably inhibited. The housed Li LiFePO4 batteries exhibited over 95% capacity retention after 500 cycles at 1.0 C in coin cell and 85% capacity retention after 80 cycles at 0.5 C in pouch cell. The rationally combination of solid electrolyte layer protection and housed framework in one Li metal anode sheds fresh insights on the design principle of a safe and long lifespan Li metal anode for Li metal batteries.

title: Monolithic solid electrolyte interphases formed in fluorinated orthoformate based electrolytes minimize Li depletion and pulverization
abstract: Lithium (Li) pulverization and associated large volume expansion during cycling is one of the most critical barriers for the safe operation of Li metal batteries. Here, we report an approach to minimize the Li pulverization using an electrolyte based on a fluorinated orthoformate solvent. The solid electrolyte interphase (SEI) formed in this electrolyte clearly exhibits a monolithic feature, which is in sharp contrast with the widely reported mosaic or multilayer type SEIs that are not homogeneous and could lead to uneven Li stripping/plating and fast Li and electrolyte depletion over cycling. The highly homogeneous and amorphous SEI not only prevents dendritic Li formation, but also minimizes Li loss and volumetric expansion. Furthermore, this new electrolyte strongly suppresses the phase transformation of the LiNi0.8Co0.1Mn0.1O2 cathode (from layered structure to rock salt) and stabilizes its structure. Tests of high voltage Li||NMC811 cells show long term cycling stability and high rate capability, as well as reduced safety concerns. Parasitic reactions between Li metal and electrolytes need to be mitigated in Li metal batteries. Here, the authors report the use of a fluorinated orthoformate based electrolyte, leading to a monolithic solid electrolyte interphase and subsequently a high performance Li metal battery.

title: Zinc anode compatible in situ solid electrolyte interphase via cation solvation modulation
abstract: The surface chemistry of solid electrolyte interphase is one of the critical factors that govern the cycling life of rechargeable batteries. However, this chemistry is less explored for zinc anodes, owing to their relatively high redox potential and limited choices in electrolyte. Here, we report the observation of a zinc fluoride rich organic/inorganic hybrid solid electrolyte interphase on zinc anode, based on an acetamide Zn(TFSI)2 eutectic electrolyte. A combination of experimental and modeling investigations reveals that the presence of anion complexing zinc species with markedly lowered decomposition energies contributes to the in situ formation of an interphase. The as protected anode enables reversible ~100% Coulombic efficiency) and dendrite free zinc plating/stripping even at high areal capacities >2.5 mAh cm 2) endowed by the fast ion migration coupled with high mechanical strength of the protective interphase. With this interphasial design the assembled zinc batteries exhibit excellent cycling stability with negligible capacity loss at both low and high rates. Zinc chemistry is not favourable to the formation of a solid electrolyte interphase as a result of its high redox potential. In a break with the traditional wisdom, the present authors realise ZnF2 rich hybrid SEI on Zn anode via the modulation of cationic speciation in a eutectic electrolyte.

title: Direct electrosynthesis of pure aqueous H2O2 solutions up to 20% by weight using a solid electrolyte
abstract: A direct route to pure peroxide Despite the widespread use of hydrogen peroxide as an oxidant and disinfectant, its commercial synthesis still requires inefficient concentration and purification steps. Xia et al. now report an electrochemical approach to synthesizing pure peroxide solutions straight from hydrogen and oxygen. Using a solid state electrolyte, they avoid contamination of the product solution by extraneous ions. Varying the flow rate of water through the electrochemical cell tunes the final concentration over a range from 0.3% to 20% by weight. Science, this issue p. 226 A solid electrolyte enables hydrogen peroxide synthesis straight from hydrogen and oxygen, with no purification required. Hydrogen peroxide (H2O2) synthesis generally requires substantial postreaction purification. Here, we report a direct electrosynthesis strategy that delivers separate hydrogen (H2) and oxygen (O2) streams to an anode and cathode separated by a porous solid electrolyte, wherein the electrochemically generated H+ and HO2 recombine to form pure aqueous H2O2 solutions. By optimizing a functionalized carbon black catalyst for two electron oxygen reduction, we achieved >90% selectivity for pure H2O2 at current densities up to 200 milliamperes per square centimeter, which represents an H2O2 productivity of 3.4 millimoles per square centimeter per hour (3660 moles per kilogram of catalyst per hour) A wide range of concentrations of pure H2O2 solutions up to 20 weight could be obtained by tuning the water flow rate through the solid electrolyte, and the catalyst retained activity and selectivity for 100 hours.

title: Toward a Fundamental Understanding of the Lithium Metal Anode in Solid State Batteries An Electrochemo Mechanical Study on the Garnet Type Solid Electrolyte Li6.25Al0.25La3Zr2O12.
abstract: For the development of next generation lithium batteries, major research effort is made to enable a reversible lithium metal anode by the use of solid electrolytes. However, the fundamentals of the solid solid interface and especially the processes that take place under current load are still not well characterized. By measuring pressure dependent electrode kinetics, we explore the electrochemo mechanical behavior of the lithium metal anode on the garnet electrolyte Li6.25Al0.25La3Zr2O12. Because of the stability against reduction in contact with the lithium metal, this serves as an optimal model system for kinetic studies without electrolyte degradation. We show that the interfacial resistance becomes negligibly small and converges to practically 0 O*cm2 at high external pressures of several 100 MPa. To the best of our knowledge, this is the smallest reported interfacial resistance in the literature without the need for any interlayer. We interpret this observation by the concept of constriction resistance and show that the contact geometry in combination with the ionic transport in the solid electrolyte dominates the interfacial contributions for a clean interface in equilibrium. Furthermore, we show that under anodic operating conditions the vacancy diffusion limitation in the lithium metal restricts the rate capability of the lithium metal anode because of contact loss caused by vacancy accumulation and the resulting pore formation near the interface. Results of a kinetic model show that the interface remains morphologically stable only when the anodic load does not exceed a critical value of approximately 100 mA*cm 2, which is not high enough for practical cell setups employing a planar geometry. We highlight that future research on lithium metal anodes on solid electrolytes needs to focus on the transport within and the morphological instability of the metal electrode. Overall, the results help to develop a deeper understanding of the lithium metal anode on solid electrolytes, and the major conclusions are not limited to the Li|Li6.25Al0.25La3Zr2O12 interface.

title: Generation and Evolution of the Solid Electrolyte Interphase of Lithium Ion Batteries
abstract: A solid electrolyte interphase (SEI) is generated on the anode of lithium ion batteries during the first few charging cycles. The SEI provides a passivation layer on the anode surface, which inhibits further electrolyte decomposition and affords the long calendar life required for many applications. However, the SEI remains poorly understood. Recent investigations of the structure of the initial SEI, along with changes which occur to the SEI upon aging, have been conducted. The investigations provide significant new insight into the structure and evolution of the anode SEI. The initial reduction products of ethylene carbonate (EC) are lithium ethylene dicarbonate (LEDC) and ethylene. However, the instability of LEDC generates an intricate mixture of compounds, which greatly complicates the composition of the SEI. Mechanisms for the generation of the complicated mixture of products are presented along with the differences in the SEI structure in the presence of electrolyte additives.