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A stable lithium‐metal electrode can enable the shift from the Li‐ion batteries to the next generation chemistries such as Li−S and Li−O2 with significant gains in the energy density and sustainability. This transition, however, is hindered by the dendrite formation, high chemical reactivity, and volume changes of the Li electrode. Although recent advancements in computational and experimental research have deepened our understanding of these issues, the primary obstacles to the commercialization of the lithium‐metal batteries (LMBs) still persist. To address these challenges, a synergistic approach that combines computational and experimental strategies shows great promise. In this regard, this paper reviews the current experimental and theoretical understanding of the lithium‐metal electrodes in view of the initiation and growth mechanisms of the lithium dendrites and interface instability. Leveraging the strengths of both approaches can offer a holistic insight into the LMB performance and guide the development of innovative designs for electrolytes and electrodes that can enhance the stability and performance of the LMBs. [ABSTRACT FROM AUTHOR]

This paper presents a composed lithium phosphate (LiPON) solid electrolyte interface (SEI) film which was coated on a lithium electrode via an electrodeposit method in a lithium–sulfur battery, and the structure of the product was characterized through infrared spectrum (IR) analysis, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), environment scanning electron microscope (ESEM), etc. Meanwhile, the electrochemical impedance spectrum and the interface stability of the lithium electrode with the LiPON film was analyzed, while the coulomb efficiency and the cycle life of the lithium electrode with the LiPON film in the lithium–sulfur battery were also studied. It was found that this kind of film can effectively inhibit the charge from transferring at the interface between the electrode and the solution, which can produce a more stable interface impedance on the electrode, thereby improving the interface contact with the electrolyte, and effectively improve the discharge performance, cycle life, and the coulomb efficiency of the lithium–sulfur battery. This is of great significance for the further development of solid electrolyte facial mask technology for lithium–sulfur batteries. [ABSTRACT FROM AUTHOR]

Abstract A stable lithium‐metal electrode can enable the shift from the Li‐ion batteries to the next generation chemistries such as Li−S and Li−O2 with significant gains in the energy density and sustainability. This transition, however, is hindered by the dendrite formation, high chemical reactivity, and volume changes of the Li electrode. Although recent advancements in computational and experimental research have deepened our understanding of these issues, the primary obstacles to the commercialization of the lithium‐metal batteries (LMBs) still persist. To address these challenges, a synergistic approach that combines computational and experimental strategies shows great promise. In this regard, this paper reviews the current experimental and theoretical understanding of the lithium‐metal electrodes in view of the initiation and growth mechanisms of the lithium dendrites and interface instability. Leveraging the strengths of both approaches can offer a holistic insight into the LMB performance and guide the development of innovative designs for electrolytes and electrodes that can enhance the stability and performance of the LMBs.

The possibility of analyzing the electrochemical impedance spectra of lithium–lithium cells using the Distribution of Relaxation Times (DRT) function is studied. A comparative analysis of the electrochemical impedance spectra of lithium–lithium cells obtained during long-term storage at a constant temperature and at different temperatures was performed using the method of either equivalent electrical circuits or the DRT function. The analysis of the impedance of lithium–lithium cells by the DRT function is shown to allow estimating the number of layers in the surface film on the lithium electrodes and evaluating their physical parameters—the resistance and capacitance. It has been established that with a long exposure of lithium–lithium cells at the temperature of 30°C, the number of layers in the surface film and its resistance decreased. With the increase in the temperature, the physical properties of the layers of the surface film are differentiated and its total resistance decreased. The analysis of the electrochemical impedance spectra of lithium–lithium cells by the DRT functions is more informative than the method of equivalent electrical circuits. [ABSTRACT FROM AUTHOR]

Rechargeable lithium metal batteries (RLMBs) have been extensively investigated as a next‐generation battery for electric vehicles because of their two times higher specific energy density than conventional lithium‐ion batteries. However, RLMBs have not been commercialized yet, because of the low coulombic efficiency (CE) of the lithium deposition and stripping process and lithium dendrite formation. CEs measured by a conventional method with a Li/electrolyte/Cu were considerably lower than those measured using full cells of Li/electrolyte/oxide cathode. The discrepancy is considered to be due to the non‐reversibility of the Cu electrode for the lithium deposition and stripping process. Here, we propose a new method to determine the CE of lithium deposition and stripping on lithium metal from the loss of electrolyte using a Li/electrolyte/Li cell with a limited amount of electrolyte. [ABSTRACT FROM AUTHOR]

Abstract Rechargeable lithium metal batteries (RLMBs) have been extensively investigated as a next‐generation battery for electric vehicles because of their two times higher specific energy density than conventional lithium‐ion batteries. However, RLMBs have not been commercialized yet, because of the low coulombic efficiency (CE) of the lithium deposition and stripping process and lithium dendrite formation. CEs measured by a conventional method with a Li/electrolyte/Cu were considerably lower than those measured using full cells of Li/electrolyte/oxide cathode. The discrepancy is considered to be due to the non‐reversibility of the Cu electrode for the lithium deposition and stripping process. Here, we propose a new method to determine the CE of lithium deposition and stripping on lithium metal from the loss of electrolyte using a Li/electrolyte/Li cell with a limited amount of electrolyte.

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A stable solid electrolyte interphase (SEI) plays a vital role in the cyclic stability and Coulombic efficiency (CE) of high-performance lithium-sulfur (Li-S) batteries. It is recognized that the LiNO 3 additive can stabilize the SEI of the lithium electrode. However, the exact mechanism of the LiNO 3 additive on the SEI of the lithium electrode remains unclear. In this work, we first revealed the mediation mechanism of LiNO 3 additive on the dynamic evolution of the SEI on a lithium anode surface through in situ Fourier transform infrared (FTIR) spectroscopy and ab initio molecular dynamics (AIMD) methods. The FTIR and AIMD results directly proved that LiNO 3 can accelerate the reduction of lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) into small molecules rich in Li 2 O on lithium anode, thus forming a compact and stable SEI after immersing in the LiNO 3 -containing electrolyte. Moreover, the decomposition of LiTFSI and the solvent is hindered in the subsequent lithium deposition stripping process due to the stable SEI, thus leading to higher Coulombic efficiency and long-term cyclic stability. In addition, an ROSO 2 Li-like intermediate is also observed during the lithium deposition process while decomposing or diffusing away during the lithium stripping process, maintaining a dynamic formation/dissolution equilibrium of the SEI. This research provides a new insight into understanding the role of LiNO 3 in stabilizing lithium electrode. [ABSTRACT FROM AUTHOR]

Rechargeable lithium-air batteries have ultra-high theoretical capacities and energy densities, allowing them to be considered as one of the most promising power sources for next-generation electric vehicles. The technology has been honed in various ways over the years, but it still experiences critical issues that need to be addressed in order to make it commercially viable. For instance, its practical capacity, round-trip efficiency, and cycling life are among the factors that need to be improved. In this review, the developments of this type of battery are presented. In particular, the system levels of design that encompass the optimization of the battery’s electrolyte and electrodes are discussed. More importantly, this report provides perspectives on achieving the desired battery performance to meet the demands of commercial viability. [ABSTRACT FROM AUTHOR]

To evaluate ideal interfaces between Li metal and Li 2 S-P 2 S 5 solid electrolytes, bulk-type cells were fabricated using thin Li metal films prepared by vacuum-evaporation. The symmetric cell of Li/75Li 2 S·25P 2 S 5 /Li showed a high utilization of Li metal (about 40%), though abrupt decrease of the utilization was observed after 5 cycles. A high utilization of Li metal (about 25%) was retained for 5 cycles by inserting Au thin films at the interface between Li metal and Li 2 S-P 2 S 5 solid electrolytes. Morphology of Li metal after dissolution/deposition cycles for the cell with Au thin films became more uniform compared to the cell without Au thin films. [ABSTRACT FROM AUTHOR]

Abstract: The surface modified lithium electrode is prepared by coating an ionic conductive poly(vinylene carbonate-co-acrylonitrile) layer as a solid electrolyte interphase on lithium metal. The thin protective polymer layer with strong adhesion to the lithium electrode suppresses the corrosion of lithium metal and stabilizes the interface of lithium electrode in prolonged contact with organic electrolyte. Cycling performance of the Li/LiCoO2 cells can be improved by using the surface modified lithium electrode. SEM analysis of lithium electrodes after repeated cycling reveals that the use of a surface modified lithium electrode effectively suppresses dendrite growth during cycling, which results in stable cycling characteristics compared to that of the cell with an un-modified lithium electrode. [Copyright &y& Elsevier]

Abstract: The solid electrolyte interphase on the lithium electrode cycled with an electrolyte solution with polysulfides is investigated by a series of measurement within symmetrical cells. Both discharge–charge curves and EIS (electrochemical impedance spectroscopy) data show that polysulfides in the electrolyte solution play an important role for the stability of the interface on the lithium electrode. These results combined with SEM (scanning electron microscope) images show that the decomposition of the lithium salt (LiTFSI) on the lithium electrode can be prevented by a surface film formed with polysulfides. As shown by XPS (X-ray photoelectron spectroscopy) spectra and depth profiling, the surface film on the lithium anode cycled in the electrolyte solution with polysulfides can be assumed to be composed of two layers. The top layer is composed of the products of the decomposition of LiTFSI and the bottom layer is composed of lithium sulfide produced by the reaction between lithium metal and the polysulfides in the electrolyte solution. We suggest that the bottom layer efficiently prevents the decomposition of the lithium salt on the lithium anode in lithium–sulfur batteries, thereby increasing the stability and cyclability. [Copyright &y& Elsevier]

Abstract: We have incorporated polymer additives such as poly(ethylene glycol) dimethyl ether (PEGDME) and tetra(ethylene glycol) dimethyl ether (TEGDME) into N-methyl-N-butylpyrrolidinium bis(trifluoromethane sulfonyl)imide (PYR14TFSI)–LiTFSI mixtures. The resulting PYR14TFSI+LiTFSI+polymer additive ternary electrolyte exhibited relatively high ionic conductivity as well as remarkably low viscosity over a wide temperature range compared to the PYR14TFSI+LiTFSI binary electrolytes. The charge/discharge cyclability of Li/LiFePO4 cells containing the ternary electrolytes was investigated. We found that Li/PYR14TFSI+LiTFSI+PEGDME (or TEGDME)/LiFePO4 cells containing the two different polymer additives showed very similar discharge capacity behavior, with very stable cyclability at room temperature (RT). Li/PYR14TFSI+LiTFSI+TEGDME/LiFePO4 cells can deliver about 127mAh/g of LiFePO4 (74.7% of theoretical capacity) at 0.054mA/cm2 (0.2C rate) at RT and about 108mAh/g of LiFePO4 (63.4% of theoretical capacity) at 0.023mA/cm2 (0.1C rate) at −1°C for the first discharge. The cell exhibited a capacity fading rate of approximately 0.09–0.15% per cycle over 50 cycles at RT. Consequently, the PYR14TFSI+LiTFSI+polymer additive ternary mixture is a promising electrolyte for cells using lithium metal electrodes such as the Li/LiFePO4 cell reported here. These cells showed the capability of operating over a significant temperature range (∼0–∼30°C). [Copyright &y& Elsevier]

Electrospun membranes of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)/multiwall carbon nanotube (MWCNT) composite are prepared and loaded with lithium salts from electrolyte solution. Field emission transmission electron microscopy provides evidence for the uniform distribution of MWCNTs into the matrix of PVdF-HFP. The interconnected morphology as evident from field emission scanning electron micrograph forms the path for the lithium ion conduction. Results from electrochemical impedance spectroscopy inform that the presence of MWCNTs in PVdF-HFP matrix improves interfacial stability between lithium electrode and membrane and augment conduction path in the polymer electrolyte membrane. Further results from impedance measurement reveal the contribution of MWCNTs toward conductivity. A prototype cell is fabricated with PVdF-HFP/MWCNT as polymer electrolyte. The electrospun PVdF-HFP electrolyte membrane with 2% MWCNTs content shows an ionic conductivity of about 5.85 mSmiddotcm-1 at 25 degC. Also, PVdF-HFP/MWCNT electrolyte membrane exhibits good electrochemical and interfacial stability and can be potentially suitable as electrolyte in lithium ion secondary battery [ABSTRACT FROM PUBLISHER]

Abstract: We show that the polymeric binder of the composite electrode may have an important role on the lithium trivanadate Li1.2V3O8 electrode performance. We describe a new tailored polymeric binder combination with controlled polymer–filler (carbon black) interactions that allows the preparation of new and more efficient electrode architecture. Using this polymeric binder, composite electrodes based on Li1.2V3O8 display a room temperature cycling capacity of 280mAhg−1 (C/5 rate, 3.3–2V) instead of 150mAhg−1 using a standard-type (poly(vinylidene fluoride)–hexafluoropropylene (PVdF–HFP) binder) composite electrode. We have coupled scanning electron microscopy (SEM) observations, galvanostatic cycling and electrochemical impedance spectroscopy in order to define and understand the impact of the microstructure of the composite electrode on its electrochemical performance. Derived from these studies, the main key factors that provide efficient charge carrier collection within the composite electrode complex medium are discussed. [Copyright &y& Elsevier]

The processes occurring in aprotic electrolyte on a lithium electrode in the steady state conditions and under polarization are studied using the method of electrochemical noise characterization. The evidence of the electro-chemical noise measurements on polarized lithium electrodes indicates that the discharge of lithium ions under cathodic polarization, as well as lithium anodic dissolution, is localized under the passive film rather than on its surface. An increase in the polarizing current results in local breakdown of the film; in this case, the electrochemical process emerges on the electrode surface affecting the character of potential fluctuations. The intensity of electrochemical noise significantly increases in the course of cathodic polarization with high currents. The reason is that lithium metal crystals, which are formed under the passive film, perforate the film, and dendrites grow on its surface. The method shows the dependence of electrochemical noise intensity on the nature of the electrolyte and establishes the correlation between the stability of the lithium electrode in the course of cycling and the intensity of fluctuations. This offers an opportunity of using the method of electrochemical noise for screening organic electrolytes for lithium batteries. [ABSTRACT FROM AUTHOR]

High-molecular-weight comb-shaped polyethers, poly(ethylene oxide-co-2-(2-methoxyethoxy) ethyl glycidyl ether-co-allyl glycidyl ether) (P(EO/EM/AGE)) and poly(ethylene oxide-co-2-(2-methoxyethoxy)ethyl glycidyl ether) (P(EO/EM)), were synthesized and used for the preparation of the all solid polymer electrolyte and the composite polymer electrolyte combined with a plasticizer Star-EO-OMe, pentaerythritol tetrakis(2-methoxyethyl ether), which shows low vapor pressure, respectively. Some electrochemical properties of the polymer electrolytes and performances of the cell consisting of lithium/polymer electrolyte/LiCoO2 were studied. The addition of Star-EO-OMe to polymer electrolyte brought about a large increase in ionic conductivity. The composite electrolyte containing 50 wt.% of Star-EO-OMe complexed with LiTFSI, lithium bis(trifluoromethylsulfonyl)imide, exhibited high ionic conductivity in the order of 10-4 S cm-1 at 10 °C and approximately 10-5 S cm-1 at -20 °C. The cell performance was also improved by the addition of Star-EO-OMe. [Copyright &y& Elsevier]

Although a lithium metal anode has a high energy density compared with a carbon insertion anode, the poor rechargeability prevents the practical use of anode materials. A lithium electrode coated with Li2CO3 was prepared as a negative electrode to enhance cycleability through the control of the solid electrolyte interface (SEI) layer formation in Li secondary batteries. The electrochemical characteristics of the SEI layer were examined using chronopotentiometry (CP) and impedance spectroscopy. The Li2CO3–SEI layer prevents electrolyte decomposition reaction and has low interface resistance. In addition, the lithium ion diffusion in the SEI layer of the uncoated and the Li2CO3-coated electrode was evaluated using chronoamperometry (CA). [Copyright &y& Elsevier]

A protected lithium electrode was prepared by forming a protection layer on the surface of lithium metal. The protection layer was formed by ultraviolet (UV) radiation-curing of a mixture of crosslinking agent (1,6-hexanediol diacrylate), liquid electrolyte (ethylene carbonate (EC)/propylene carbonate (PC)/1 M LiClO4), and photoinitiator (methyl benzoylformate). The interfacial properties of a symmetric lithium cell containing the protected lithium electrode was better than those of the cell using a bare lithium electrode with storage. The performance of unit cells was also enhanced by the introduction of the protection layer on the surface of the lithium anode. The morphology of the solid electrolyte interphase (SEI) layer developed on the protected lithium anode during the charge–discharge runs at 1C rate was smoother at the surface and less porous. [Copyright &y& Elsevier]

The photoelectrochemical performance of lithium in a propylene carbonate solution of LiClO4 and in a mixture of propylene carbonate with dimethoxyethane, as well as in a LiAlCl4 solution in thionyl chloride, has been investigated. It has been established that when illuminating the electrodes under study, electronic photoemission takes place from the metal into a passivating film permanently existing on the lithium surface. The measurements were in part carried out with the Li electrode coated specially with a Li2O or Li2CO3 protecting film. Photoemission spectroscopy has been used as a tool for exploring the processes of both formation and change in the composition and properties of the passivating layers on the lithium electrodes. The results for the photoelectrochemistry of lithium have been compared with the analogous data obtained with electrodes made of gold and SnCd alloy in a propylene carbonate solution of LiClO4. In the two last cases, electronic photoemission from the metal into solution has been revealed. [ABSTRACT FROM AUTHOR]

Electrochemical impedance analysis, in-situ dilatometry, in-situ electrochemical calorimetry and ex-situ SEM have been shown to be effective diagnostics for studying formation of lithium dendrites in cells. Effect of lithium polysulfides present in the electrolyte in a Li–S cell, on the suppression of fine-dispersed heterogenous non-planar lithium dendrite precipitations during cycling of lithium symmetric cells was studied in accelerated DC cycling tests by a combination of the above techniques. It is shown that deliberate incorporation of lithium polysulfides in electrolyte solutions leads to decreasing rate of accumulation of fine-dispersed lithium (dendrite precipitations) on the surface of a lithium electrode which results in increasing the cycle life of lithium symmetric cells by 200–250% in accelerated tests, thus enhancing safety. It is demonstrated that electrochemical dilatometry and EC calorimetry are sensitive to changes on the surface of lithium electrode and can be used for early identification of dendrite formation during cycling of lithium electrodes. In-situ electrochemical dilatometry can not only identify formation of Li dendrites at early stages but also quantify the growth rate. The presence of high surface area lithium is more corrosive towards the electrolyte and can be monitored by the use of in-situ EC calorimetry for heat generation by corrosion during a cycle. Cycle life is limited by evenness/continuity of electrolyte solution in cell, which must essentially fill internal volume of the cell (all the pores without leaving any "dry area"). Image 1 • Electrochemical dilatometry is used to quantify growth rate of Li dendrites. • Addition of Li 2 S n to electrolyte reduces accumulation of lithium dendrites. • Li 2 S n addition to electrolyte improves Li cycling by 200–250% in accelerated tests. • Cycle life is limited by evenness/continuity of electrolyte solution in cell. • EC calorimetry can identify at early stages formation of fine-dispersed lithium. [ABSTRACT FROM AUTHOR]

The specifics of magnetron sputtering of lithium from a liquid-phase target are discussed. It is noted that sputtering by direct or pulse current was accompanied by rotation of liquid lithium in the target due to magnetohydrodynamic effect, thus favouring a permanent renewal of the target surface. The energy balance of thermal evaporation and magnetron sputtering processes in the overall process of emission of lithium atoms from the liquid-phase target is studied. The energy efficiency of the emission of lithium atoms is estimated. Lithium deposits obtained by magnetron sputtering method on stainless steel substrates have a polycrystalline surface structure. The interphase film formed upon contact of the lithium electrode obtained by magnetron sputtering with electrolyte solutions has lower resistance than the similar film formed on the surface of the electrode made of foil. • Magnetron sputtering of lithium from a liquid-phase target is studied. • Magnetohydrodynamic rotation of lithium renews the surface of a liquid-phase target. • Thick Li layers with polycrystalline structures are obtained by magnetron sputtering. • Interphase films resistance on magnetrone Li is initially 2 times smaller than foil. [ABSTRACT FROM AUTHOR]