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The utilization of lithium (Li) metal as an anode in batteries has drawn significant research interest. However, its widespread adoption has been hampered by the formation of Li dendrites and associated irreversible effects. In this study, we aim to develop a sulfur-rich inorganic solid electrolyte interphase (SEI) by incorporating Sodium 3,3′-dithiodipropane sulfonate (SPS) into a 1,3-dioxopentane/1,2-dimethoxyethane (DME/DOL) based electrolyte. The desolvation kinetics are accelerated by the unique solvation shell containing anions, as evidenced by both theoretical models and experimental data. Additionally, the combined effects of the additives lower the Li+ diffusion energy barrier significantly, promoting the deposition of compact and chunky Li, thereby facilitating the creation of an additive-derived sulfur enhanced inorganic-rich SEI. Consequently, the resultant SEI is enriched with lithium sulfide (Li 2 S), leading to enhanced coulombic efficiency, rate capability, and cyclic stability while reducing polarization potential. Symmetrical Li | Li cells subject to high current density and capacity (5.0 mA cm−2 and 15 mAh cm−2) demonstrate stable cycling for over 750 h. This technology demonstrates the potential to enhance the efficiency and reliability of batteries that use lithium metal anodes by reducing the formation of dendrites. • SPS creation of an additive-derived, enhanced sulfur-rich inorganic SEI. • The sulfur-rich SEI promotes the deposition of compact and chunky Li. • Li.| Li symmetrical cells display a stable cycle over 750 h at 5 mA/cm2. [ABSTRACT FROM AUTHOR]

Extensive research has focused on the lithium (Li) metal anode, but progress in developing this technology has been hindered by the formation of lithium dendrites and their irreversible effects. In this study, an inorganic LiF-Li 3 N-rich solid electrolyte interface (SEI) is established in ether electrolyte through the direct use of 2,3-difluoro-5-(trifluoromethyl)pyridine (DP) to enable uniform Li deposition and enhance interfacial properties for a stable Li metal anode. Theoretical calculations show that DP has a higher tendency to decompose on lithium metal. An alternative approach involving the inclusion of additional anions into the solvation sheath of Li+ ions using weakly solvating solvents is proposed. During Li plating, DP is reduced to form a LiF and Li 3 N-rich SEI, resulting in a heterogeneous SEI layer on the Li metal anode surface. This approach allows stable cycling of Li|Li cells for over 1800 h at current densities of 5 mA cm−2 and 15 mAh cm−2. The method presented here has potential significance in the identification of suitable electrolytes for future research on lithium metal anodes. [ABSTRACT FROM AUTHOR]

The forming of Li-Bi alloy can build a lithiophilic protective layer on the lithium anode, however, it is found that the lithium dendrites trend to grow on the surface of bismuth-rich solid electrolyte interphase (SEI) and there is an exfoliation of SEI from substrate caused by de-alloying process at a large current density. The failure cause of the bismuth-rich SEI is considered as the inadequate Li-ionic conductivity of the passivation layer, which cannot facilitate the lithium deposition on the substrate. Then the components with high Li-ionic conductivities such as Li 3 N, LiF and Li 2 S are introduced into the SEI to adjust the characteristic of the bismuth-rich layer by the addition of LiNO 3 , Bi 2 S 3 and FEC. All of them enhance the SEI's performances effectively and LiNO 3 presents the best. With the addition of LiNO 3 , the SEI thickness is decreased and Li-ionic conductivity is enhanced while Li 3 N became one of the major components of the layer. Utilizing the improved bismuth-rich protective layer the Li/Li symmetric cell presents an overpotential at ∼10 mV in a long cycle over ∼1700 h at 4 mA cm−2, and the LiFePO 4 /Li cell with the cathode loading of ∼10 mg cm−2 exhibits a capacity retention rate 72.1% in 400 cycles. This work provides a new SEI design strategy for lithium metal anode operating at high current density and an inspiration for improving other functional interfacial layers in lithium batteries. • Lithium bismuth alloy and dendrites trend to dealloy and grow on the SEI at high current density. • Additives enhancing Li-ionic conductivities are introduced to adjust the bismuth-rich layer's components. • Lithium nitrate addition make Li 3 N a major component of the layer and significantly enhances SEI electrochemical properties. [ABSTRACT FROM AUTHOR]

• It is a facile and inexpensive strategy employing g-C 3 N 4 layer to modified the Li metal. • The Li-GCN/sulfide solid electrolyte interfacial side reactions are revealed to be significantly inhibited. • The abundant nitrogen species within Li-GCN interphase homogenize the distribution of Li ions flux. • The all-solid-state Li-GCN/LPSC/SPAN battery delivers an excellent capacity retention of 88% after 150 cycles. Sulfide solid-state electrolytes (SSEs) are expected to fundamentally avoid the polysulfides shuttle and Li dendrites growth in the traditional liquid electrolyte lithium-sulfur (Li-S) batteries owing to its ultrahigh ionic conductivity, the high mechanical strength and favorable interfacial compatibility with sulfide-based cathodes. However, the sulfide SSEs are thermodynamically unstable to Li metal, and the parasitic reactions between the Li anode and sulfide SSEs results in intolerable interface deterioration. Herein, a graphitic carbon nitride (GCN, g-C 3 N 4)-dominated artificial interlayer was introduced to enhance the interfacial stability between Li metal and sulfide SSEs. The introduction of electrochemically inert GCN is revealed to effectively alleviate the formation of heterogenous resistance layers for long-term. Furthermore, the abundant nitrogen species within GCN layer homogenize the distribution of Li ions flux, which effectively smooths Li deposition and suppresses dendrites growth. Herein, the symmetric cells with the Li-GCN show a stable plating/stripping cycling for over 1100 h at 0.2 mA cm−2 and a capacity of 0.2 mAh cm−2. The all-solid-state Li-SPAN battery with g-C 3 N 4 interphase exhibits a highly reversible capacity of 579 mAh g−1 and a capacity retention of 88% at 0.2C after 150 cycles, as well as achieves an excellent rate performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • The anions rapidly decompose and some common products are observed. • The proton on the N atom readily detaches from the cations and generates LiOH. • Protic ionic liquids are capable of forming a stable SEI layer on Li metal. Interfacial structures and dissociation reactions of protic ionic liquids (PILs) comprising five protic cations with two common sulfonylimide anions on the Li(0 0 1) surface were investigated using first-principles calculations and ab initio molecular dynamics simulations. Both the anions rapidly decompose, yielding LiF, Li 2 O and Li 2 S species as well as large fragments, e.g. NSO 2 CF 3 and NSO 2. Particularly, the proton attached to the N atom generally segregates from the cations and generates LiOH with the O atom from the anions and the surface Li atom. In addition, detailed comparisons of reaction mechanisms between PIL-based and AIL-based systems were also made. [ABSTRACT FROM AUTHOR]

The realization of anode-free lithium metal batteries (AFMBs) is limited owing to low Coulombic efficiency derived from the formation of uneven lithium plating at the anode side. Here, we induce the uniform deposition of lithium by an Au predeposited three-dimensional (3D) anodic current collector with an ether-based electrolyte. At the modified anodic current collector, the over-potential generated during the initial deposition of lithium converged to 6 mV, and stable cycling was achieved with an extremely high Coulombic efficiency of 99 % over 100 cycles. Furthermore, when compared to two-dimensional (2D) bare copper foil (LiFePO 4 /2D Cu), AFMBs using LiFePO 4 cathode with Au predeposited 3D anodic current collector (LiFePO 4 /Au-3D Cu) show better rate performance and longer cycle life. This improvement in electrochemical performance is derived from the regulation of lithium deposition and inhibition of electrolyte decomposition due to the local current density through the predeposition of Au and 3D structure. This study provides a new path to realizing AFMBs. ● Lithiophilic Au reduce nucleation overpotential and induce uniform deposition of lithium. ● A regulated lithium plating and growth direction with dense morphology is obtained. ● Large surface area of 3D network suppress volume exchange. ● Low activation energy and high binding energy improve the electrochemical performance. [ABSTRACT FROM AUTHOR]

Abstract A 500 mAh Li–Air battery is assembled using cell components and a structure that enable the construction of a high specific energy battery. Carbon nanotubes are used in the cathode so that the pore volume can be adjusted to reduce the amount of electrolyte while a high specific capacity of the cathode is maintained. Polymer ionic liquid is used in the electrolyte layer, and the weight of the cathode and electrolyte layer is 5.5 mg cm−2. The cell structure, which is prepared by folding a three-layer assembly of Li metal/electrolyte layer/cathode, reduces the weight contribution of the sealing and manifold materials. By folding the three-layer assembly ten times, a 500 mAh Li–Air battery with dimensions of 7 cm × 1 cm × 0.23 cm is prepared. The battery yields an areal capacity of 3.6 mAh cm−2 and a specific capacity of 4400 mAh g carbon −1, and the resulting specific energy and energy density are 1230 Wh kg−1 and 880 Wh L−1, respectively. The battery is able to cycle seven times at 500 Wh kg−1 before an abrupt decrease in its capacity is noted. Graphical abstract Image 1 Highlights • Design of Li–Air battery with specific energy over 1000 Wh kg−1 is presented. • Fold cell structure reduces weight of sealing and manifold materials. • A cell with dimension of 7 cm × 1 cm × 0.23 cm produces 500 mAh. • The battery could be cycled 7 times at the specific energy of 500 Wh kg−1. [ABSTRACT FROM AUTHOR]

Abstract Lithium (Li) metal is considered to be one of the most promising anode materials for rechargeable batteries in the future. Unfortunately, the unavoidable Li dendrites are the biggest obstacle to realize the commercial application of Li metal. Herein, we employ a lithium-aluminum (Li-Al) alloy and lithium nitride (Li 3 N) composite coating layer to achieve the dendrite-free for the Li metal anode. This alloy/Li 3 N layer is acquired by the reaction of a nanosized nitride material (aluminum nitride; AlN) and Li metal in a tetrahydrofuran (THF) solution. This stable composite layer provides a fast ion migration channel and an electronic insulation passivating layer for the surface of Li metal. As a result, the modified Li anode maintains uniform and stable electrodeposition without the formation of dendrites for 200 h at 5 mA cm−2. More importantly, when, the dendrite-free Li anodes are fabricated by spraying the AlN solution onto the large Li foil and the NCM-alloy/Li 3 N-Li pouch cells show significantly improved cycle performance against the NCM-Li cells. This strategy may offer a great possibility for the commercial application of Li metal anode. [ABSTRACT FROM AUTHOR]

Abstract The potential for safe, high energy-density Li-ion batteries has motivated the development of the solid electrolyte Li 7 La 3 Zr 2 O 12 (LLZO) to physically stabilize the Li-electrolyte interface. Although dense LLZO is a relatively hard ceramic, it has been observed that above a certain critical current density (CCD), Li metal can still propagate through both polycrystalline and single crystalline LLZO. However, reported values of CCD are still well below the current density regimes relevant to applications like electric vehicles (≥3 mA cm−2). The relationship between CCD and temperature was studied using recently developed methods for achieving consistently low interfacial impedances without interfacial coatings that can complicate the analysis of what controls interface stability. By analyzing the flux of Li+ ions at the Li-electrolyte interface, it is hypothesized here that solid-state diffusivity of Li in the Li electrode may be a governing mechanism that controls the CCD. These results demonstrate an improvement for dendrite-free cycling in LLZO up to ∼1 mA cm−2 at room temperature and ∼7 mA cm−2 at 100 °C without the need for coatings to achieve low interface resistances (∼10 Ω cm2). Furthermore, the presented analysis may provide additional insight on the role of Li diffusivity in Li propagation through ceramic electrolytes. [ABSTRACT FROM AUTHOR]

Lithium (Li) metal anode has attracted extensive research interest, while lithium dendrites and the resulting irreversible effects have restricted its development. In this study, a thin and dense solid electrolyte interface is constructed by introducing 3-(1-pyridinio)-1-propane sulfonate (PPS), a pyridine functional groups additive in DME/DOL based electrolyte to inhibit the lithium dendrite growth. The preferential decomposition of PPS has resulted in a reduction of gas generation. Subsequently, this process leads to forming of an N-rich solid electrolyte interface, which has been found to cause a decrease in polarization potential and change the behavior of lithium deposition from dendrites to a more cellular Li metal surface. As a result, our proposed electrolyte provides multiple functionalities, including remarkable rate capability, cyclic stability, and coulombic efficiency. Significantly, Li | Li symmetrical cells exhibited a stable cycle over 1200 h at a high current density and capacity of 5 mA cm−2/15 mAh cm−2. We are optimistic that our proposed method can be employed in future research to identify electrolytes appropriate for use in lithium metal anodes. A thin and dense solid electrolyte interface was grown by introducing a pyridine functional groups electrolyte additive, exhibiting an excellent cycling performance for lithium metal batteries. [Display omitted] • PPS reduces gas production resulting in thin and dense N-rich SEI film. • The N-rich SEI alters the deposition behavior of lithium. • Li.| Li symmetrical cells display a stable cycle over 1200h at 5 mA/cm2. [ABSTRACT FROM AUTHOR]

A new asymmetrical anion, trifluoromethanesulfonyl- N -cyanoamide (TFSAM − ), was paired with N -butyl- N -methyl pyrrolidinium (PYR 14 + ) to prepare PYR 14 TFSAM. It has been investigated for Li-ion battery application and compared to its PYR 14 + analogs paired with either the dicyanamide anion (DCA − ) or other anions ( i.e. bis(trifluoromethanesulfonyl) imide (TFSI − ), bis(fluorosulfonly)imide (FSI − ), trifluoromethanesulfonyl-fluorosulfonyl imide (FTFSI − )). The conductivity of PYR 14 TFSAM is not only higher than that of PYR 14 TFSI, but also higher than that of PYR 14 FTFSI with 3.8 mS cm −1 at 20 °C and 12.6 mS cm −1 at 60 °C. In addition, the ionic liquid does not crystallize and exhibits a viscosity similar to that of PYR 14 FSI (and even lower above 30 °C, which also results in a higher conductivity at high temperature). Compared to PYR 14 DCA, PYR 14 TFSAM has a higher anodic stability, more compatible with state-of-the-art cathodes such as NCM, even though the PYR 14 DCA electrolyte also allowed surprisingly good cycling results of NCM cathode considering its low anodic stability. PYR 14 TFSAM also allows Li + (de-)/insertion into graphite, using vinylene carbonate as additive. When used in conventional Li-ion electrolyte solvents, it leads to moderate conductivity (as compared with LiFSI or LiTFSI), although much higher than LiDCA. Additionally, it is shown that, even in EC/DMC-based electrolyte, LiTFSAM does not induce Al corrosion at 4.2 V. [ABSTRACT FROM AUTHOR]

The potential to enable unprecedented performance, durability, and safety has created the impetus to develop bulk-scale all-solid-state batteries employing metallic Li as the negative electrode. Owing to its low density, low electronegativity and high specific capacity, Li metal is the most attractive negative electrode. However, failure caused by the formation of dendrites has limited the widespread use of rechargeable batteries using metallic Li negative electrodes coupled with liquid electrolytes. One approach to mitigate the formation of dendrites involves the use of a solid electrolyte to physically stabilize the Li–electrolyte interface while allowing the facile transport of Li-ions. Though in principle this approach should work, it has been observed that at high Li deposition rates Li metal can propagate through relatively hard ceramic electrolytes and Li dendrite formation causing short circuit has been reported. Why this occurs is poorly understood, emphasizing the need to close the knowledge gap and facilitate the development of advanced batteries employing solid electrolytes. Here, through precise microstructural control, striking electron microscopy, and high-resolution surface spectroscopy, we directly observed for the first time the propagation of Li metal through a promising polycrystalline solid electrolyte based on the garnet mineral structure (Li 6.25 Al 0.25 La 3 Zr 2 O 12 ). Moreover, we observed that Li preferentially deposits along grain boundaries (intergranularly). These results offer insight into the electrochemical-mechanical phenomena that govern the stability of the metallic Li–polycrystalline solid electrolyte interface and are essential to the maturation of solid-state batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • The SEI with rich organic and inorganic components exhibits high Li+ conductivity and mechanical strength. • The organic-inorganic interlayer prevents the serious reaction between Li metal and PVDF-HFP which maintains as the compact coating layer. • The organic-inorganic interlayer favor the stable Li+ plating/stripping in long-term. • The PVDF-HFP assisted by organic-inorganic interlayer enable high performance of Li-oxygen battery. PVDF-HFP layer has been used in lithium (Li) metal-based batteries for its high Li-ion conductivity, excellent mechanical strength and water-proof property. Moreover, the layer reacts with Li metal and improves the performance of solid electrolyte interphase (SEI) by introducing the additional component of LiF. Herein, we further allow an organic molecular (11-mercaptoundecanoic acid, MUA) to involve in the reaction between the PVDF-HFP layer and Li metal, which results in an organic–inorganic SEI interlayer consisting of Li 2 S, LiF, lithium alkyl carbonate (RCOOLi), and MUA-Li etc. This interlayer shows the high Li+ transfer number (0.62) and Young's modulus (6.17 GPa), which also serves to increase the adhesion between PVDF-HFP and Li metal. By using the organic–inorganic interlayer enhanced PVDF-HFP coated Li metal, the Li/Li symmetric cells can run for at least 2190 h steadily, and the Li-oxygen batteries can operate for 214 cycles, demonstrating the improved protection and ionic conductivity of Li metal anodes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Track-etched polyimide separator with vertically-aligned nanochannels is designed. • Vertically-aligned nanochannels of the separator allow a fast Li+ migration. • Hydrophilic polyvinylpyrrolidone can regulate Li+ flux uniformly during cycling. The practical application of Li metal is hampered by critical obstacles, such as the indiscriminate dendritic growth of metallic Li and severe dimensional changes during cycling. Effective surface engineering is necessary to stabilize the interfacial reactions of Li metal to resolve these technical issues. Many strategies have been proposed to mitigate this inherent limitation of Li metal. The interfacial stabilization using an electrolyte additive or polymer coating is the most common approach to enable the uniform distribution of Li+ on the surface of Li metal. In parallel, the development of functional separators is also considered a promising alternative strategy for effective suppression of the fatal growth of Li dendrites because it promotes Li+ transfer at the interfaces. The synergistic effect of regulating Li+ flux and promoting Li+ transfer is expected to effectively prohibit the dendritic growth of metallic Li. Herein, we report a track-etched polyimide (TEPI) separator with vertically aligned nanochannels decorated with polyvinylpyrrolidone (PVP) that enables a self-assembled robust protective layer on the surface. From a structural viewpoint, the vertically aligned nanochannels of the TEPI separator allow for fast Li+ migration. Additionally, hydrophilic PVP can regulate Li+ flux uniformly through the nanochannels by forming a stable Li 3 N-dominant solid electrolyte interphase (SEI) layer, thereby enhancing interfacial kinetics and suppressing the Li dendrite growth during cycling. We demonstrate that the TEPI separator decorated with PVP is effective in securing high reversibility and the improved cycle performance of Li-metal batteries (LMBs). [ABSTRACT FROM AUTHOR]

The recent impressive growth of Li-ion batteries (LIBs) production infrastructures is related to the surge of electric automotive industry. However, the current performance of LIBs is limited by the intrinsic capacity of graphite anodes, the use of organic solvents and by the limited wettability of the separator. In this review, we aim at demonstrating the grade of advance that can be expected for the performances of Li-ion batteries in the short term (roughly, 5–10 years) thanks to introduction of smart materials and interfaces. This temporal limit reflects the need of maintaining the current production chain of LIBs and optimizing the relative investments. In particular, we analyze and discuss the most recent scientific findings on: (i) the solvent, focusing our attention on deep eutectic solvents and ionic liquids (ILs) as an alternative to the currently adopted organic solvents; (ii) tuning the wettability of the separator, thanks to the optimization of the material, its porosity and its surface features; (iii) the anodic materials, according to the different proposed mechanism for Li storage and classifying them into different categories (i.e. carbon-based, Si, perovskites). Finally, we must recognize that, among the so-called "post LIBs" batteries, Li metal batteries can also play a key role in the near future: this type of battery is currently under production for primary cells but requires a smart cathode|electrolyte interface to avoid Li dendrite growth during charge/discharge cycles in their future as secondary systems. [ABSTRACT FROM AUTHOR]

This article shows that reflection electron energy loss spectroscopy can be used to identify Li compounds with comparable accuracy as X-ray absorption near edge structure by optimizing the energy and energy width of the irradiated electron beam. This method was applied to analyzing the solid–electrolyte interface of Li metal, and the chemical state of Li could be examined directly without being affected by surface contamination. • Li K-edge reflection EELS for lithium compounds with the same accuracy with XANES. • Irradiated electron energy and energy width are key points. • Li K-edge reflection EELS applicable to solid–electrolyte interface analysis. [ABSTRACT FROM AUTHOR]

The employment of localized high concentration electrolytes (LHCEs) has been demonstrated as an effective strategy for the fabrication of next-generation high-energy-density lithium metal batteries. However, the low ionic conductivity of LHCEs and their parasitic side reactions with lithium metal anodes severely hinder the cycling stability of lithium metal batteries. Herein, a partially fluorinated ether of bis (2,2-difluoroethyl) ether (BDE) is proposed as a bifunctional co-solvent to form novel LHCEs for realizing dendrite-free and long-term lithium metal batteries. The BDE co-solvent serves as a diluent to improve the ionic conductivity up to 6.4 mS/cm by dissociating lithium salt via weak interaction and decreasing the electrolyte viscosity. In addition, the BDE co-solvent could promote the formation of uniform lithium fluoride (LiF)-rich solid electrolyte interphase (SEI) to suppress the dendrite deposition by regulating the solvation shell structure, resulting in high Coulombic efficiency of 99.6%. As a result, the assembled full cell exhibits outstanding cycling stability (97% capacity retention after 200 cycles @0.5 C) with high areal capacity (2 mAh/cm2) and high rate capability (2 C) under practical conditions (50 µm Li, lean electrolyte: 3 g/Ah). We also demonstrate the real application of electrolyte with a commercial cathode in 320-mAh-level pouch cells. [Display omitted] • A partially fluorinated ether was prepared as a bifunctional electrolyte co-solvent. • Dendrite-free and long-term lithium metal batteries were developed. • Li plating/stripping Coulombic efficiency was high up to 99.6%. • Outstanding cycling stability of a 320-mAh-level pouch cell was achieved. [ABSTRACT FROM AUTHOR]

• Dual interlayers are constructed in situ on both sides of the LAGP. • Janus LAGP is compatible with both Li metal and high-voltage cathodes. • The critical current density can be significantly increased to 5.4 mA cm−2. • The solid-state NCM811/Li battery exhibits excellent rate and cycling performance. The application of Li 1.5 Al 0.5 Ge 1.5 (PO 4) 3 (LAGP) is hindered by chemical instability with lithium (Li) metal and poor interfacial compatibility with high-voltage cathodes. Herein, an in-situ Janus LAGP is fabricated to solve the above two issues simultaneously. On the cathodic side, a succinonitrile-based interlayer with good oxidation stability is applied to facilitate ion transport at the interface and inside the cathode. On the anodic side, Fluoroethylene carbonate (FEC)-based polymer interlayer is chosen to ameliorate side reactions on LAGP/Li interface and inhibit the dendrite growth. Consequently, the Li symmetric cell with the Janus LAGP possesses a high critical current density of 5.4 mA cm−2 and operates stably for over 500 h at a high current density of 1.0 mA cm−2. Moreover, the Janus LAGP exhibits excellent ionic conductivity (4.76 × 10−4 S cm−1), wide electrochemical window (0–5.2 V vs. Li+/Li) and stable interfacial compatibility with high-voltage cathodes. The solid-state lithium battery (LiNi 0.8 Co 0.1 Mn 0.1 O 2 /Li) delivers a maximum discharge capacity of 178 mAh g−1 with a retention of 85.7% after 100 cycles at 0.5C. Notably, when the mass loading is increased to 10.0 mg cm−2, the battery delivers a maximum discharge capacity of 134.1 mAh g−1 (1.52 mAh) at 0.5C, and the capacity remains 76.1% after 100 cycles. [ABSTRACT FROM AUTHOR]

Abstract: The electrodeposition process of Li metal in 1.0M LiTFSI–ionic liquid (N-methoxymethyl-N-methylpyrrolidinium) bis(trifluoromethane-sulfonyl) imide was observed in situ by optical microscope. Morphological variations of electrodeposited Li dendrite and its growth rate were examined and the ionic mass transfer rate in the vicinity of the electrode surface was discussed. Once the dendrite starts to grow, its length is proportional to the square root of time. This indicates that the Li+ mass transfer rate affects its growth. Dendrite growth process can be classified into two regions depending on its growth rate: the initiation period and the growing period with swinging behavior probably caused by residual stress. [Copyright &y& Elsevier]

Abstract: Using a micro-patterned Si plate, a Li secondary cell was assembled and tested for its electrochemical properties. A micro-patterned Si plate was made by photolithography. This was followed by Pt coating and Li deposition. With a non-lithiated LiV3O8 cathode, a Li-deposited micro-patterned Si anode was assembled as a secondary cell. The cell exhibited an initial charge/discharge capacity of about 220mAhg−1 at a current density of 0.1 C-rate and it continued for more than 100cycles without failure. The morphologies of Li deposition/dissolution in the anode were observed via scanning electron microscopy (SEM). Dendrite behavior of the Li metal was not observed on the anode during the cyclic process. [ABSTRACT FROM AUTHOR]

• The Co/PCNF-PMS multifunctional bilayer structure was designed for Li-S batteries. • The synergistic function of the bilayer can effectively restrain the polysulfides shuttle and Li dendrite growth. • The electrocatalytic Co nanoparticles can significantly enhance the reaction kinetics of active sulfur species. • The Li-S battery delivered a high areal capacity under high sulfur loading and lean electrolyte condition. A novel Co/PCNF-PMS multifunctional bilayer have been successfully constructed for Li-S battery which can effectively alleviate the shuttling effect of polysulfides and enhance their redox reaction kinetics. [Display omitted] Lithium-sulfur (Li-S) battery is considered as one of the most promising alternatives for next-generation electrochemical energy storage systems due to its high energy density and low cost. Unfortunately, several issues of Li-S battery, such as sluggish reaction kinetics, severe polysulfides shuttle effect and volume expansion, still hinder the commercialization of Li-S battery. Herein, a synergistic strategy is proposed, which comprises polyethyleneimine (PEI)-multi-walled carbon nanotube-Super P (PMS) coating modified on PP separator and uniformly distributed cobalt nanocrystals in N-doped porous carbon nanofiber (Co/PCNF) as a freestanding interlayer in the cathodic side of Li-S battery. Benefiting from abundant amino/imine groups of protonated PEI and catalytic Co active sites in conductive porous carbon skeleton, the Co/PCNF-PMS bilayer architecture can not only intensely anchor the negatively charged polysulfides via electrostatic interaction but also fast electrocatalyze the sulfur redox reaction. The synergistic effect of the Co/PCNF-PMS bilayer enable the Li-S battery with a high initial capacity of 1537 mAh g−1 at 200 mA g−1, extended cycling stability of only 0.06% per cycle capacity fade over 300 cycles at 2000 mA g−1 and outstanding performance under high raised sulfur loading up to 6 mg cm−2. [ABSTRACT FROM AUTHOR]

The use of surface-patterned lithium (Li) metal has been proposed as a promising strategy for inhibiting the formation of Li dendrites during repeated Li plating/stripping processes. Nevertheless, the conventional Li metal patterning process is complex, expensive, incompatible with mass production, and incapable of producing finely controlled patterns on the Li metal surface. A large, flexible patterning stamp capable of large-area patterns is developed using a silicon (Si) wafer-based chemical etching process, and its effect on the electrochemical performance of a Li metal anode is investigated. The newly developed stamps have 5,000% larger patterning area compared to the conventional stainless-steel stamps. Furthermore, when compared to conventional surface-patterned Li metal fabricated with conventional stainless-steel stamps (SP-LM), the surface-patterned Li metal fabricated with large and flexible patterning stamps (LAP-LM) demonstrates improved electrochemical performance and stable morphological properties. As a result, the LAP-LM is able to retain up to 85.2% of its initial discharge capacity (85.9 mAh g−1) after 200 cycles at 3C (3.96 mA cm−2), while the SP-LM shows a severe capacity decay after 150 cycles (94.0 mAh g−1 and 13.0 mAh g−1 at the 150th cycle and 200th cycle, respectively). [Display omitted] • A large, flexible patterning stamp capable of large-area patterns was developed. • The newly developed stamps achieved 5,000% larger patterning area for Li metal. • The new large-area stamp produced stable morphological properties for Li metal. • The new large-area stamp showed significantly improved electrochemical properties. [ABSTRACT FROM AUTHOR]

Abstract: Li metal was galvanostatically electrodeposited on a horizontally positioned, downward-facing Li metal cathode in 0.5M LiClO4-PC electrolyte. The refractive index profile corresponding to the transient Li+ ion concentration profile formed in the electrolyte solution upon applying a current step was measured in-situ by holographic interferometry. The configuration of the electrolytic cell was such that mass transfer was governed only by transient diffusion and migration, in the absence of convection. Between the moment of closing the current circuit and the time at which the interference fringes started to shift, an incubation period was observed. Such an incubation period had earlier been observed in lithium electrodeposition at a vertical planar Li metal cathode. The incubation period for the horizontal Li cathode was roughly half that for a vertical one. To study the effect of the electrode material on the incubation period, interferometry measurements were also made at an electrodeposited Ni–Sn alloy electrode. The concentration profile formed near the Ni–Sn alloy electrode during lithiation (alloying or intercalation of Li+ into the electrode) agrees well with predictions made by means of the one-dimensional diffusion equation. Only very short incubation period was detected, but the magnitude was negligibly smaller than that of Li metal electrodeposition. The incubation period therefore appears to be characteristic for Li metal electrode only. [Copyright &y& Elsevier]

Abstract: The thermal stability of different electrolytes—LiPF6, LiPF3(C2F5)3 (LiFAP), LiFAP solutions containing 5% vinylene carbonate, and LiFAP solutions containing 1% Li bisalicylato borate—in a mixture of (2:1:2 v/v/v) EC, DEC and DMC is investigated. The results of a comprehensive study of the thermal behavior of these solutions in contact with Li metal and lithiated graphite electrodes (synthetic flakes) using both accelerating rate (ARC) and differential scanning (DSC) calorimetry, are reported herein. The surface films formed at room temperature on Li and lithiated graphite surfaces in all the solutions studied are not stable at elevated temperatures. The main exothermic reactions of the solution thermal decomposition in contact with Li metal occur at temperatures lower than the Li melting point (180 °C). The highest onset (at 165 °C) for the thermal decomposition in the presence of Li, was observed for solutions containing both LiFAP and VC. LiPF6 solutions showed the lowest onset for thermal reaction (at 132 °C). [Copyright &y& Elsevier]

• The Li–Zn alloy layer could facilitate fast charge transfer at the interface. • The modified Li electrode can realize deposition of Li with a smooth morphology. • The modified Li electrode can cycle stably at higher current density and capacity. The lithium metal anode is one of the most attractive candidates for high-energy lithium rechargeable batteries because it has an ultrahigh theoretical specific capacity and the lowest electrode potential. Unfortunately, uncontrollable growth of dendritic Li leads to problems such as safety hazards and low cycling reversibility, which greatly hinder its commercial application. Here, a Li–Zn alloy layer is constructed in situ on Li metal foil by a simple chemical reaction of zinc trifluoromethanesulfonate with Li metal. The modified Li metal anode forms an interface with fast charge transfer kinetics and high chemical resistance to the electrolyte, which enables deposition of Li with a smooth, dense morphology without the growth of dendritic Li. In symmetrical cells, the Li metal anode with the Li–Zn alloy layer can reach a cycling lifetime of more than 500 h under a current density of 2 mA cm−2. This work provides a simple and effective strategy to suppress the formation of Li dendrites. [ABSTRACT FROM AUTHOR]