Li Sulfur Research Articles

Enhanced electrochemical stability and ion transfer rate: A polymer/ceramic composite electrolyte for high-performance all-solid-state lithium-sulfur batteries

All-solid-state (ASS) lithium-sulfur (LiS) batteries utilizing composite polymer electrolytes (CPEs) represent a promising avenue in the domain of electric vehicles and large-scale energy storage systems, leveraging the combined benefits of polymer electrolytes (PEs) and ceramic electrolytes (CEs). However, the inherent weak interface compatibility between PEs and CEs often leads to phase separation, thereby impeding the transposition of Li+. In this study, the trimethoxy-[3-(2-methoxyethoxy)propyl]silane (TM-MES) is introduced as a chemical agent to form bonds with polyethylene oxide (PEO) and Li10GeP2S12 (LGPS), resulting in the development of a novel composite polymer electrolyte (CPETM-MES). This innovative approach mitigates phase separation between PEs and CEs while concurrently enhancing the protective capabilities of LGPS against decomposition at the interfaces of both the Li anode and sulfur cathode. Moreover, the CPETM-MES exhibits superior mechanical toughness, an expanded electrochemical window, and elevated ionic conductivity. In the symmetric cell, it demonstrates an extended operational lifespan exceeding 1800 h, and the current density can reach up to 1.05 mA/cm2. Furthermore, the initial discharge capacity of ASS LiS batteries utilizing CPETM-MES attains 1227 mAh/g and maintains a capacity of 904 mAh/g after 100 cycles. Notably, a high-energy-density of 2454 Wh/kg is achieved based on the sulfur cathode.

Lithium–sulfur batteries beyond lithium-ion counterparts: reasonable substituting challenges, current research focus, binding critical role, and cathode designing

Abstract Despite concerns regarding safety, economics, and the environment, lithium-ion batteries (LIBs) are considerably utilized on account of their low energy density and capacity. Li–sulfur (Li–S) batteries have become a promising substitute for LIBs. Here, we first compared both systems in their cons and pros and analyzed the leading countries and companies in Li–S research are assessed through the utilization of an academic database. The scope of our research includes performance-enhancing design elements, cathode components, and binder materials. Synthetic and natural binders are trialed in an effort to enhance Li–S performance. Understanding the fundamental mechanisms enables the development of durable cathodes and binders. To overcome obstacles such as polysulfide adsorption, shuttle effect, and ion transport limitations, conducting polymers, metal/metal oxides, carbon-based compounds, MOFs, and Mxenes are investigated as potential cathode materials. In addition to pore characteristics and active polar sites, the efficacy of a battery is influenced by the anode surface geometry and heteroatom doping. Our review indicates that binders and sulfur/host composites must be meticulously chosen for Li–S battery cathode materials. This research advances energy storage technology by establishing the foundation for economically viable lithium–sulfur batteries with superior performance.

Operando Raman and in-Situ UV-Vis Spectroscopy Unveil the Impact of Solvent Donor and Acceptor Numbers on Gel Polymer Electrolytes in Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries boast a specific capacity five times greater than current Li-intercalation systems. Still, practical implementation faces challenges tied to liquid electrolytes, i.e., lithium metal dendrites formation, polysulfide redox-shuttle, and flammability [1]. Thus, we focus on developing biodegradable gel polymer electrolytes to overcome these issues, fostering eco-friendly, safer, and more effective energy storage solutions. Polycaprolactone (PCL) emerges as a promising GPE candidate due to its biodegradable nature and broad stability range (~5V vs Li0/Li+). Our current study investigates the influence of solvent selection, explicitly focusing on donor and acceptor numbers, in formulating gel polymer electrolytes for Lithium-Sulfur batteries. Leveraging operando Raman and in-situ UV-Vis spectroscopy, our research provides real-time insights into the dynamic interactions within the gel during battery operation, shedding light on the evolving electrochemical processes. Moreover, by systematically analyzing the impact of solvent properties on gel characteristics, we reveal a nuanced relationship, emphasizing the importance of tailored solvent selection for optimizing gel performance. Operando Raman spectroscopy enables the observation of bond formations and structural changes in the gel, while in-situ UV-Vis spectroscopy tracks the behavior of polysulfides, facilitating the identification of specific interactions and offering a comprehensive understanding of the gel's role in mitigating polysulfide shuttling. This work aims to advance our fundamental knowledge of gel polymer electrolytes and provide a pathway for optimizing battery performance and mitigating degradation mechanisms. Notably, our study introduces a novel dimension by employing a custom-built UV-Vis setup, enhancing the versatility and applicability of these spectroscopic techniques in probing the intricate interactions within gel polymer electrolytes.Reference1-Pervez, S. A.; Vinayan, B. P.; Cambaz, M. A.; Melinte, G.; Diemant, T.; Braun, T.; Karkera, G.; Behm, R. J.; Fichtner, M., Electrochemical and compositional characterization of solid interphase layers in an interface-modified solid-state Li–sulfur battery. Journal of Materials Chemistry A2020, 8 (32), 16451-16462.

Ion Dynamics in Nanocrystalline Li2S‐LiI – on the Influence of Local Disorder on Short‐Range Hopping and Long‐Range Ion Transport

The enormous interest in developing powerful Li‐based batteries leads to a boost in materials research. Though Li–sulfur batteries offer very high energy densities, the nature of Li‐ion dynamics in the final discharge product has not been fully understood yet. While nanocrystalline shows enhanced ion dynamics compared to its coarse‐grained counterpart, the interaction of with another binary such as LiI seems to be rather unexplored. Herein, an equimolar mixture of and LiI is treated in a high‐energy ball mill, and both the overall and local structural changes are studied by X‐ray powder diffraction and nuclear magnetic resonance (NMR), respectively . Besides the formation of amorphous regions, evidences are found for the generation of anion‐mixed sites that give rise to facile Li exchange on the 2D exchange NMR timescale. Compared to a coarse‐grained reference sample, the overall (bulk) ionic conductivity of nanocrystalline ‐LiI increases by two orders of magnitude. Besides the anion‐mixing effect, this increase benefits from nanosize effects that include the formation of defect‐rich interfacial regions. NMR relaxation measurements fully support this result and reveal heterogeneous dynamics with lower activation energies for both the localized hopping processes and long‐range ion transport in nm‐sized ‐LiI.

Spatial Progression of Polysulfide Reactivity with Lithium Nitrate in Li–Sulfur Batteries

Spatial Progression of Polysulfide Reactivity with Lithium Nitrate in Li–Sulfur Batteries

Surface Adaptive Dual‐Layer Protection of Li‐metal Anode for Extending Cycle‐Life of Li–Sulfur Batteries with Lean Electrolyte

AbstractBuilding a lithium–sulfur (Li–S) battery with lean electrolytes is essential to far exceed the energy density of today's Li‐ion. However, earlier electrolyte depletion triggered by Li‐metal anodes (LMAs) causes sluggish Li–S redox kinetics and poor S utilization, resulting in a short cycle lifespan. To retard the electrolyte loss effectively, sustainable protection of LMAs is necessary against the dynamic interfacial evolution between LMA and protective layers (PLs). This study elucidates two critical parameters in securing the interfacial adaptivity of PLs upon local Li pitting: surface free energy (SFE) and Young's modulus through solid‐mechanic simulations and experiments using three different PL models. To alleviate the PL delamination at the early stage, a dual‐layer structured, adaptive protective layer (APL) is introduced to adapt the Li pitting‐driven structural evolution of the PL|LMA interfaces. The APL consists of a high‐ SFE polymer as an inner layer, reducing the interfacial energy in contact with LMA surface, and a highly stretchable polymer for outer shield, serving as a physical barrier for the electrolyte and Li polysulfides. APL‐coated LMA demonstrates stable cycling of Li–S cells, achieving a twofold extension of cycle‐life compared to unprotected LMA, even superior to other single‐layer PLs.

Influence of carbon structure/porosity on the electrochemical performance in Li–sulfur batteries

The porous structure of three different, commercially available porous carbonaceous materials is investigated by the αS-plot method and by the t-plot method. Subsequently, the electrochemical properties of sulfur-free porous carbon electrodes from inspected materials are studied by cyclic voltammetry. The comparison of double-layer capacitances with the corresponding adsorption isotherms of N2 reveals the role of micropores during the capacitive charging of carbons by Li+. The studied carbons are added to the sulfur cathodes and evaluated. The cyclic voltammograms show no contribution of micropores in the carbon structure to the electrochemical processes taking place in the lithium–sulfur coin cell. The highest specific capacity of 816 mAh/g is observed for material with the lowest content of micropores in the structure (14%). The partially mesoporous and partially microporous (65%) sample and the predominantly microporous one (87%), show specific capacities of 664 mAh/g and 560 mAh/g, respectively. The galvanostatic cycling of lithium–sulfur coin cells with carbonaceous additives reveals that the mesopores and macropores in the carbon structure increase the specific charge capacity of the lithium–sulfur batteries and that the micropores improve the cycling stability of these batteries.Graphical abstract

Solid-state electrolytes for inhibiting active species crossover in lithium metal batteries: a review

Solid-state electrolytes not only avoids volatility, flammability, and short-circuits, but also inhibits the crossover of active species in various lithium-metal batteries, such as Li–sulfur, Li–organic and Li–air batteries.

Molecular polysulfide-scavenging sulfurized–triazine polymer enable high energy density Li-S battery under lean electrolyte

Lean electrolyte with low electrolyte/sulfur (E/S) ratio is a crucial step for the advancement of high energy density lithium-sulfur (Li-S) batteries. However, the low E/S introduces serious kinetics issues where the cell can only last for a few cycles. Here, aiming to overcome the operational constraints, we rationally design covalently grafted sulfurized–triazine polymeric (STP) cathodes housing > 60% sulfur capable of cycling under lean electrolyte. As-developed STP cathodes at lean E/S: 4, 6, and 8 µL mgs–1 show improved sulfur reactivity and cycle-life, delivering 522, 574, and 601 mAh gs–1 at the 200th cycle. Further, at sulfur loading 5 mg cm–2 with E/S: 6 µL mgs–1, the Li-S cell exhibits 588 mAh gs–1 capacity with 93% Coulombic efficiency. Experimental and modeling tools reveal that the triazine cathode support allows covalent grafting and good wettability beneficial for facile Li ion and sulfur reactivity. As a result, the generated polysulfide is concurrently regulated in a molecularly fashion via bulk-immobilization involving abundant pyridinic–N and pyrrolic–N to confine within the electrode. Extending to construct a practical lean Li-S pouch cell with sulfur, lithium, and electrolyte accounting 53.7% cell's mass delivers an energy density of 371 Wh kg–1 that is par to the predicted values under lean electrolyte. Our study provides an invaluable resource in a potential way and future directions for developing practical high energy Li-S batteries.

Influence of dry‐ and wet‐milled LLZTO particles on the sintered pellets

AbstractA Ta‐doped Li7La3Zr2O12 (LLZTO) solid electrolyte is a promising candidate for all‐solid‐state lithium battery due to its high ionic conductivity and stability against lithium metal. In this work, physicochemical properties of both dry‐ and wet‐milled LLZTO particles were investigated. Based on X‐ray diffraction, Fourier transform–infrared, thermogravimetric analysis, and scanning electron microscopy results, it was confirmed that highly reactive LLZTO powder prepared in dry milling conditions exhibited faster size reduction, rougher surface morphology, fewer surface impurities, and less agglomerated particles, in contrast to those in wet milling conditions. Sintering these dry‐milled powders at 1320°C for 10 min in the air via solid‐state reaction produced dense ceramic pellets with a relative density of 97.4%. The room‐temperature ionic conductivity for LLZTO pellet via the dry milling was determined to be 6.94 × 10−4 S cm−1. Li–sulfur batteries based on the pellets showed an initial discharge capacity of 1301 mA h g−1 and a coulombic efficiency of 99.82% when cycled at room temperature. The effect of the milled powder on the sintered pellets was discussed in terms of boundary mobility, pore mobility, and morphology.

Fluorinating the Solid Electrolyte Interphase by Rational Molecular Design for Practical Lithium‐Metal Batteries

AbstractThe lifespan of practical lithium (Li)‐metal batteries is severely hindered by the instability of Li‐metal anodes. Fluorinated solid electrolyte interphase (SEI) emerges as a promising strategy to improve the stability of Li‐metal anodes. The rational design of fluorinated molecules is pivotal to construct fluorinated SEI. Herein, design principles of fluorinated molecules are proposed. Fluoroalkyl (−CF2CF2−) is selected as an enriched F reservoir and the defluorination of the C−F bond is driven by leaving groups on β‐sites. An activated fluoroalkyl molecule (AFA), 2,2,3,3‐tetrafluorobutane‐1,4‐diol dinitrate is unprecedentedly proposed to render fast and complete defluorination and generate uniform fluorinated SEI on Li‐metal anodes. In Li–sulfur (Li−S) batteries under practical conditions, the fluorinated SEI constructed by AFA undergoes 183 cycles, which is three times the SEI formed by LiNO3. Furthermore, a Li−S pouch cell of 360 Wh kg−1 delivers 25 cycles with AFA. This work demonstrates rational molecular design principles of fluorinated molecules to construct fluorinated SEI for practical Li‐metal batteries.

Fluorinating the Solid Electrolyte Interphase by Rational Molecular Design for Practical Lithium-Metal Batteries.

The lifespan of practical lithium (Li)-metal batteries is severely hindered by the instability of Li-metal anodes. Fluorinated solid electrolyte interphase (SEI) emerges as a promising strategy to improve the stability of Li-metal anodes. The rational design of fluorinated molecules is pivotal to construct fluorinated SEI. Herein, design principles of fluorinated molecules are proposed. Fluoroalkyl (-CF2 CF2 -) is selected as an enriched F reservoir and the defluorination of the C-F bond is driven by leaving groups on β-sites. An activated fluoroalkyl molecule (AFA), 2,2,3,3-tetrafluorobutane-1,4-diol dinitrate is unprecedentedly proposed to render fast and complete defluorination and generate uniform fluorinated SEI on Li-metal anodes. In Li-sulfur (Li-S) batteries under practical conditions, the fluorinated SEI constructed by AFA undergoes 183 cycles, which is three times the SEI formed by LiNO3 . Furthermore, a Li-S pouch cell of 360 Wh kg-1 delivers 25 cycles with AFA. This work demonstrates rational molecular design principles of fluorinated molecules to construct fluorinated SEI for practical Li-metal batteries.

Catalysing the performance of Li–sulfur batteries with two-dimensional conductive metal organic frameworks

The performance of two-dimensional (2D) conductive metal–organic frameworks (MOFs) to be suitable cathode hosts for Li–S batteries is investigated based on the catalytic triangle, and Co3(THT)2 is observed to be the optimum host.

In Situ Imaging Comparison of Lithium Electrodeposits By Neutron and X-Ray (Synchrotron and Laboratory) Tomography

Most of the post-Lithium-ion (Li-ion) devices, such as Li–sulfur, Li–O2, or all-solid-state Li batteries, have in common an negative electrode made of metallic Li.1 The main failure mode of Li based batteries is the inhomogeneity of the Li electrodeposits onto the Li metal negative electrode during charge steps, leading to dendrite growth and low Coulombic efficiency.2 Tomography and radiography imaging techniques are now vastly employed for battery materials analysis thanks to the possibility to perform noninvasive in situ and operando experiments.3 X-ray tomography is a powerful tool for studying dendrites as it provides useful information about their locations, dynamics, and microstructures. However, the use of neutron tomography is scarcely reported for Li electrodeposit analysis due to the difficulty to reach sufficient image resolution to capture the deposit microstructure, that is, typically below 10 to 20 µm. Furthermore, the different interactions of X-rays and neutrons with Li, which has significantly different opacity in the two cases, make the two techniques highly complementary.4 Notably, the capacity of neutrons to discern different Li isotopes is pivotal to get insight into the composition of Li deposits, by distinguishing between Li originating from an electrode (6Li in this study) and Li originating from the Li salt electrolyte (mainly in 7Li here). Indeed, the theoretical linear neutron attenuation coefficient of 6Li is about 15 and 2,000 times larger than that of natural Li and 7Li, respectively.In this study, we report as a proof of concept, an in situ neutron tomography imaging of Li electrodeposits in a cycled Li symmetric cell (see Figure 1).5 The electrochemical cell comprises a natural Li electrode, a 6Li electrode, and a deuterated liquid electrolyte. The neutron tomography is compared with X-ray tomography images of the same electrochemical cell acquired both at an X-ray synchrotron beamline and at a laboratory X-ray tomograph. Neutron tomography is shown to be compatible with in situ analysis and capable of capturing the overall morphology of the Li deposits in good accordance with X-ray tomography analyses. References M. S. Whittingham, Lithium batteries and cathode materials. Chem. Rev. 104 (2004) 4271.Z. Li et al., A review of Li deposition in Li-ion and Li metal secondary batteries. J. Power Sources 254 (2014) 168.K. Harry et al., Detection of subsurface structures underneath dendrites formed on cycled Li metal electrodes, Nat. Mater. 13 (2014) 69.M. Strobl et al., Advances in neutron radiography and tomography. J. Phys. D: Appl. Phys. 42 (2009) 243001.L. Magnier et al., Tomography imaging of Li electrodeposits using Neutron, synchrotron X-ray, and laboratory X-ray sources: A comparison. Front. Energy Res., 9 (2021) 657712. Figure 1

Vertical 2-dimensional heterostructure SnS-SnS2 with built-in electric field on rGO to accelerate charge transfer and improve the shuttle effect of polysulfides

Traditional carbon materials as sulfur hosts of Li-sulfur(Li-S) cathodes have slightly physical constraint for polysulfides, due to their no-polar property. Therefore, it is necessary to further enhance the affinity between sulfur hosts and polysulfides, and relieve the shuttle effects in the Li- S batteries. Herein, we report a novel vertical 2-dimensional (2D) p-SnS/n-SnS2 heterostructure sheets which grown on the surface of rGO. The excellent electrochemical properties of SnS-SnS2@rGO as Li-S cathode are ascribed to the stronger absorption effect of metal sulphides for polysulfides and the smooth trapping-diffusion-conversion effect of p-SnS/n-SnS2 heterostructure for polysulfides. As a conductive carrier for the growth of vertical 2D p-SnS/n-SnS2 heterostructure nanosheets, rGO can protect the steadiness and enhance the cycle stability of electrode, compared with heterostructure without rGO. In addition, the built-in electric field in the 2D p-SnS/n-SnS2 heterostructure during the discharge/charge processes can effectively accelerate charge transfer, and the charge transfer mechanism in SnS-SnS2 heterostructure during cycling has been investigated. At a rate capability of 2C, the designed SnS-SnS2@rGO as Li-S cathode delivers high specific capacities of 907 mAh g−1 and 571 mAh g−1 after the first cycle and 500 cycles, respectively, which shown excellent cycling ability.

Oxygen-Enriched α-MoO3– nanobelts suppress lithium dendrite formation in stable lithium-metal batteries

In this study, MoO 3 nanobelts (MNBs) are passivated on lithium (Li) metal anodes to suppress Li dendrite formation and, thereby improve the stability in Li-metal batteries. MoO 3 powder is ground into MNBs using a commercially viable mechanical grinding technique. The MNBs are then coated on Li metal using a simple spray-coating technique. The MNBs on top of the pristine Li mitigates the formation of Li dendrites by generating a uniform Li + ion flux and providing shorter diffusion pathways. This facile passivation strategy prevents the growth of undesirable dendrites on pristine Li surfaces. A live transparent Li–Li symmetrical cell having MoO 3 -coated Li anode (MNB-Li) does not form any Li dendrites and undergoes minimal surface degradation relative to that of the corresponding pristine Li cell. The Li–Li symmetrical cells featuring the MoO 3 -coated surface operate with a low overpotential of approximately 18 mV for an extremely long period of time (ca. 2500 h) at a current density of 1 mA cm −2 . A Li–sulfur battery featuring the MNB-Li at 0.5 C significantly improves stability, with an initial capacity of 1127 mAh g −1 , a capacity of 820 mAh g −1 for up to 200 cycles, and an excellent coulombic efficiency of 98.12 %. • Passivation layer of MoO 3 nanobelts (MNBs) suppress the Li dendrites on Li anode. • Shorter diffusion pathways by MNBs allow the easy migration of Li + ions. • The O 2 vacancies in MNBs boost carrier concentration and act like shallow donors. • This facile strategy demonstrates a stable anode and better cycling performance.

Tomography Imaging of Lithium Electrodeposits Using Neutron, Synchrotron X-Ray, and Laboratory X-Ray Sources: A Comparison

X-ray and neutron imaging are widely employed for battery materials, thanks to the possibility to perform noninvasive in situ and in operando analyses. X-ray tomography can be performed either in synchrotron or in laboratory facilities and is particularly well-suited to analyze bulk materials and electrode/electrolyte interfaces. Several post-lithium-ion (Li-ion) devices, such as Li–sulfur, Li–O2, or all-solid-state Li batteries, have an anode made of metallic Li in common. The main failure mode of Li batteries is the inhomogeneity of the Li electrodeposits onto the Li anode during charge steps, leading to dendrite growth and low Coulombic efficiency. X-ray tomography is a powerful tool for studying dendrites as it provides useful information about their locations, dynamics, and microstructures. So far, the use of neutron tomography is scarcely reported for Li deposit analysis due to the difficulty in reaching sufficient image resolution to capture the deposit microstructure, that is, typically below 10–20 µm. The very different interactions of X-rays and neutrons with Li, which has significantly different opacity in the two cases, make the two techniques highly complementary. Notably, the capacity of neutrons to discern different Li isotopes is pivotal to getting an insight into the composition of Li deposits by distinguishing between Li originating from an electrode (6Li in this study) and Li originating from the Li salt electrolyte (mainly in 7Li here). Indeed, the theoretical linear neutron attenuation coefficient of 6Li is about 15 and 2,000 times larger than that of natural Li and 7Li, respectively. Therefore, a high imaging contrast difference is obtained between 6Li (high attenuation) and natural Li and 7Li (lower attenuations), which could allow a better understanding of the origin of the Li comprising the electrodeposits. In this work, we report, as a proof of concept, an in situ neutron tomography imaging of Li electrodeposits in a cycled Li symmetric cell. The electrochemical cell comprises a natural Li electrode, a 6Li electrode, and a deuterated liquid electrolyte. The neutron tomographies are compared with X-ray tomography images of the same electrochemical cell acquired both at an X-ray synchrotron beamline and at a laboratory X-ray tomograph. Neutron tomography is shown to be compatible with in situ analysis and capable of capturing the overall morphology of the Li deposits in good accordance with X-ray tomography analyses.

Reliability of Silicon Battery Technology and Power Electronics Based Energy Conversion

Continuous improvements in battery technology has paved the way for adoption in growing number of applications. However, the state-of-the-art graphite anodes remain sensitive to heat dissipation during fast charging or short circuits, and possibly causing inflammation of the battery. This is a limitation for safety critical applications and prevents ultra-high charging rates. In addition, power electronics is required for preventing hazardous and inefficient operating conditions, maximizing, for example, the lifetime of the battery system. Batteries with silicon anodes overcome the limitations of today?s battery technology and enable charging rates of multiple Cs, while operating up to 100 °C and being non-flammable. Nevertheless, this does not reduce requirements for the battery management system (BMS) to control the performance of the battery. The BMS needs to maximize the charging rate, limit mechanical stress of the battery electrodes, which is associated to high charging rates. Thus, obtaining high charging efficiency, while equalizing useful remaining lifetime for all battery stacks. This manuscript is a conceptional review of how silicon anodes could be used in future Lithium-ion (Li-ion) or Li sulfur batteries providing high energy densities, offering the possibility to charge batteries with higher current densities and faster charging times. BMS and the required power electronic converters for integrating battery storage are introduced and their application for the next generation of ultra-fast charging battery system is presented.

Enhanced Capacity of Lithium Secondary Batteries Using a Li-Powder Anode

Li–graphite and Li–O2 cells were investigated to increase their capacity, similar to that reported for other Li-powder anode-based cells such as Li–V2O5, Li–LiV3O8, and Li–sulfur batteries. When a ...

Nonfluorinated Ionic Liquid Electrolytes for Lithium Metal Batteries: Ionic Conduction, Electrochemistry, and Interphase Formation

AbstractCyano‐based ionic liquids (ILs) are prime candidates for the manufacturing of cheaper and safer batteries due to their inherently low‐volatility and absence of expensive fluorinated species. In this work, N‐methyl‐N‐butylpyrrolidinium (Pyr14)‐based ILs featuring two different cyano‐based anions, i.e., dicyanamide (DCA) and tricyanomethanide (TCM), and their mixture with the respective Li salts (1:9 salt:IL mole ratio), alongside their combination (DCA–TCM), are evaluated as potential electrolytes for lithium metal batteries (LMBs). The electrolytes display significant ionic conductivity at room temperature (5 mS cm−1) alongside an electrochemical stability window up to 4 V, suitable for low‐voltage LMBs such as Li–sulfur, as well as promising cycling stability. In addition to the detailed physicochemical (viscosity, conductivity) and electrochemical (electrochemical stability window, stripping/plating, and impedance test in symmetrical Li cells) characterization, the solid electrolyte interphase (SEI) formed in this class of ionic liquids is studied for the first time. X‐ray photoelectron spectroscopy (XPS) provides evidence for an SEI dominated by a polymer‐rich layer including carbon–nitrogen single, double, and triple bonds, which provides high ionic conductivity and mechanical stability, leading to the aforementioned cycling stability. Finally, a molecular insight is achieved by density functional theory (DFT) and classic molecular dynamics simulations both supporting the experimental evidence.