Ethylene Sulfite Research Articles

Influence of ethylene sulfite in lithium bis(trifluoromethane)sulfonimide-based electrolyte for dual carbon battery

Influence of ethylene sulfite in lithium bis(trifluoromethane)sulfonimide-based electrolyte for dual carbon battery

Asymmetric Solvents Regulated Crystallization-Limited Electrolytes for All-Climate Lithium Metal Batteries.

Electrolytes that can keep liquid state are one of the most important physical metrics to ensure the ions transfer with stable operation of rechargeable lithium-based batteries at a wide temperature window. It is generally accepted that strong polar solvents with high melting points favor the safe operation of batteries above room temperatures but are susceptible to crystallization at low temperatures (≤-40 °C). Here, a crystallization limitation strategy was proposed to handle this issue. We demonstrate that, although the high melting points of ethylene sulfite (ES, -17 °C) and fluoroethylene carbonate (FEC, ≈23 °C), their mixtures can avoid crystallization at low temperatures, which can be attributed to low intermolecular interactions and altered molecular motion dynamics. A suitable ES/FEC ratio (10 % FEC) can balance the bulk and interface transport of ions, enabling LiNi0.8 Mn0.1 Co0.1 O2 ||lithium (NCM811||Li) full cells to deliver excellent temperature resilience and cycling stability over a wide temperature range from -50 °C to +70 °C. More than 66 % of the capacity retention was achieved at -50 °C compared to room temperature. The NCM811||Li pouch cells exhibit high cycling stability under realistic conditions (electrolyte weight to cathode capacity ratio (E/C)≤3.5 g Ah-1 , negative to positive electrode capacity ratio (N/P)≤1.09) at different temperatures.

Asymmetric Solvents Regulated Crystallization‐Limited Electrolytes for All‐Climate Lithium Metal Batteries

AbstractElectrolytes that can keep liquid state are one of the most important physical metrics to ensure the ions transfer with stable operation of rechargeable lithium‐based batteries at a wide temperature window. It is generally accepted that strong polar solvents with high melting points favor the safe operation of batteries above room temperatures but are susceptible to crystallization at low temperatures (≤−40 °C). Here, a crystallization limitation strategy was proposed to handle this issue. We demonstrate that, although the high melting points of ethylene sulfite (ES, −17 °C) and fluoroethylene carbonate (FEC, ≈23 °C), their mixtures can avoid crystallization at low temperatures, which can be attributed to low intermolecular interactions and altered molecular motion dynamics. A suitable ES/FEC ratio (10 % FEC) can balance the bulk and interface transport of ions, enabling LiNi0.8Mn0.1Co0.1O2||lithium (NCM811||Li) full cells to deliver excellent temperature resilience and cycling stability over a wide temperature range from −50 °C to +70 °C. More than 66 % of the capacity retention was achieved at −50 °C compared to room temperature. The NCM811||Li pouch cells exhibit high cycling stability under realistic conditions (electrolyte weight to cathode capacity ratio (E/C)≤3.5 g Ah−1, negative to positive electrode capacity ratio (N/P)≤1.09) at different temperatures.

Unlocking the Potential of Lithium Metal Batteries With a Sulfite‐Based Electrolyte

AbstractLithium metal batteries (LMBs) have the potential to significantly increase the energy density of advanced batteries in the future. Nonetheless, the dendritic lithium structures and low Coulombic efficiency (CE) of LMBs currently impede their applied implementation. Herein, a sulfite‐based electrolyte (SBE/FEC), including 1.0 m lithium bis(fluorosulfonyl)imide in a blend of ethylene sulfite and diethyl sulfite, and 5 wt% fluoroethylene carbonate is proposed. SBE/FEC is a highly efficient inhibitor against the growth of lithium dendrites through the formation of robust solid electrolyte interphase (SEI) layer. Raman spectroscopy and theoretical calculation indicate that in SBE/FEC, a significant portion of FSI− exists in associated complexes, playing a vital role in the creation of LiF‐rich passivation. Besides, the sulfite solvents decompose and yield polysulfide complexes in the SEI layer. A direct correlation between the proportion of cation–anion complexes and the contact angle between electrolyte and separator is elucidated through molecular dynamics simulations. The SBE/FEC system exhibits high CEs (98.3%) with Li||Cu cells, along with a steady discharge capacity of ≈137 mA h g−1 in Li||LiFePO4 cell. This study presents an effective approach for enhancing LMBs with sulfite‐based electrolytes, which can lead to high‐energy‐density next‐generation rechargeable batteries.

Abnormal electrode behavior of graphite anode operating with the electrolyte containing vinylene carbonate and ethylene sulfite additives

Supplementing additives into the electrolyte is a simple and effective approach to improve the electrode performance of lithium-ion batteries (LIBs). Although vinylene carbonate (VC) and ethylene sulfite (ES) additives have been studied to improve the performance of LIBs with graphite anode, the abnormal electrode behavior of graphite anodes operating with the electrolyte containing VC and ES additives has never been reported. In this paper, we report on the discovery and interpretation of the room-temperature capacity anomaly of graphite anodes operating with the VC-ES electrolyte at relatively high C rates (≥ 0.5 C). A dynamic evolution mechanism of SEI is proposed on the basis of electrochemical analysis and surface examination of graphite anodes at different charge/discharge states. The merit of the VC-ES electrolyte over the VC electrolyte is found for graphite anodes operating at 55 ºC. The VC-ES electrolyte provided here holds great potential for application in LIBs with graphite anode operating at high temperatures.

In-situ construction of high-mechanical-strength and fast-ion-conductivity interphase for anode-free Li battery

The solid electrolyte interphase (SEI) with strong mechanical strength and high ion conductivity is highly desired for Li metal batteries, especially for harsh anode-free batteries. Herein, we report a pragmatic approach to the in-situ construction of high-quality SEI by applying synergistic additives of LiNO3 and ethylene sulfite (ES) in the electrolyte. The obtained SEI exhibits a high average Young’s modulus (9.02 GPa) and exchanging current density (4.59 mA cm−2), which are 3.0 and 1.2 times as large as those using the sole additive of LiNO3, respectively. With this improved SEI, Li-dendrite growth and side reactions are effectively suppressed, leading to an ultra-high Coulombic efficiency (CE) of 99.7% for Li plating and stripping. When applying this improved electrolyte in full cells, it achieves a high capacity retention of 89.7% for over 150 cycles in a LiFePO4||Li battery (∼12 mg cm−2 cathode, 50 μm Li) and of 44.5% over 100 cycles in a LiFePO4||Cu anode-free battery.

Evaluating the roles of electrolyte components on the passivation of silicon anodes

A protocol was recently developed to compare calendar life using a constant potential while monitoring the electrical current required to maintain the potential. Here, this calendar life protocol is used with electrolyte formulations containing various mole fractions of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and LiPF6 to elucidate the role each component plays in passivation for high silicon anodes. Together, EC and LiPF6 lead to higher currents, and thus poorer passivation, whereas EMC acts as a spectator. The variation of the components’ mole fraction also changes the solid-electrolyte interphase (SEI) composition, as measured by x-ray photoelectron spectroscopy. Importantly, higher LiPF6 content leads to increased LiF as well as increased current, indicating that higher LiF content does not enhance the passivation of the silicon surface. Finding that EC did not yield a passivating SEI, instead ethylene sulfite, sulfolane, and propylene carbonate (PC) were used in place of EC. Using ethylene sulfite and sulfolane resulted in poorer passivation compared to EC, whereas PC resulted in superior passivation. The superior passivation may be related to more stable lithium-solvent complexes.

A structural and electrochemical study of lithium-ion battery electrolytes using an ethylene sulfite solvent: from dilute to concentrated solutions.

We report the structural and electrochemical characteristics of lithium (Li)-ion battery (LIB) electrolyte solutions using an ethylene sulfite (ES) solvent that is used as an electrolyte additive for LIBs. From dilute to highly concentrated ES solutions with lithium bis(fluorosulfonyl)amide (LiFSA), the formation of Li-ion complexes was investigated using a combined Raman and infrared spectroscopy study with the aid of density functional theory (DFT) calculations to quantitatively determine their solvation and ion-pair structures depending on the Li salt concentration (cLi). The results reveal that, in the dilute solutions (<1.0 mol dm-3), Li-ions are fully solvated with ES molecules to form a tetrahedral-like [Li(ES)4]+ complex; however, with the increasing cLi (up to 2.5 mol dm-3), the Li-ion complex changes in structure to form contact ion-pairs coordinated with both ES and FSA anions. It also reveals that further increasing cLi to approximately 3.0 mol dm-3 leads to the ionic aggregate formation, i.e., multiple Li-ion complexes linked via several FSA anions. LiFSA/ES electrolyte solutions exhibited a reversible Li-ion insertion/deinsertion reaction into/from the graphite anode irrespective of cLi. This is due to the high-grade ES-derived passivation films on the electrode as a result of the preferential reductive decomposition of the ES molecules trapped within the Li-ion coordination sphere. According to the charge-discharge test, the concentrated LiFSA/ES solutions exhibited the high C-rate performance, which is superior to the concentrated electrolyte solutions using conventional organic solvents.

In Ukrainian

The solution to the problem of negative impact on the ecology of fossil fuel consumption is the use of electrochemical energy sources. The special attractiveness has shown of lithium power sources is highlighted and the need to develop new cheap electrode materials and electrolytes with unique properties. The peculiarities of the behavior of lithium and the formation of a layer of reaction products on its surface upon contact with a liquid organic electrolyte have considered. The analysis of the main problems and ways of their solution at use of conversion electrodes of the II type for lithium-ion batteries has carried out. Emphasis is placed on the need to use in the development of new electrode materials of such parameters as capacity loading and accumulated irreversible capacity of the electrodes. The triad “electrode – solid electrolyte interphase – electrolyte” is considered as a basis of a systematic approach to the creation of new generations of lithium power sources. The optimal scenarios have proposed for the formation of an effective solid electrolyte interphase on the surface of the electrodes. The advantages of electrolytes based on fluoroethylene carbonate with synergistic acting additives of vinylene carbonate and ethylene sulfite are described. A new strategy for the use of “secondary” silicon nanomaterials to prevent direct contact of its surface with the electrolyte has considered. It has shown that the solid electrolyte interphase is a dynamic system that self-organizes from the unstable state into a stable one. The electrochemical behavior of electrodes with silicon nanocomposites with high capacity loading and low accumulated irreversible capacity has described.

Opportunities and Limitations of Ionic Liquid- and Organic Carbonate Solvent-Based Electrolytes for Mg-Ion-Based Dual-Ion Batteries.

Dual‐ion batteries (DIBs) offer a great alternative to state‐of‐the‐art lithium‐ion batteries, based on their high promises due to the absence of transition metals and the use of low‐cost materials, which could make them economically favorable targeting stationary energy storage applications. In addition, they are not limited by certain metal cations, and DIBs with a broad variety of utilized ions could be demonstrated over the last years. Herein, a systematic study of different electrolyte approaches for Mg‐ion‐based DIBs was conducted. A side‐by‐side comparison of Li‐ and Mg‐ion‐based electrolytes using activated carbon as negative electrode revealed the opportunities but also limitations of Mg‐ion‐based DIBs. Ethylene sulfite was successfully introduced as electrolyte additive and increased the specific discharge capacity significantly up to 93±2 mAh g−1 with coulombic efficiencies over 99 % and an excellent capacity retention of 88 % after 400 cycles. In addition, and for the first time, highly concentrated carbonate‐based electrolytes were employed for Mg‐ion‐based DIBs, showing adequate discharge capacities and high coulombic efficiencies.

Sulfur‐containing compounds as electrolyte additives for lithium‐ion batteries

AbstractOriginating from “rocking‐chair concept”, lithium‐ion batteries (LIBs) have become one of the most important electrochemical energy storage technologies, which have largely impacted our daily life. The utilization of electrolyte additives in small quantities (≤5% by wt or vol) has been long viewed as an economical and efficient approach to regulate the properties of electrolyte and electrode–electrolyte interphases and consequently improve the cycling performance of LIBs. Among all the kinds of electrolyte additives, sulfur‐containing compounds have gained significant attention due to their unique features in building stable electrode–electrolyte interphases and protect battery cells from overcharging. In this work, advances and progresses of sulfur‐containing additives used in LIBs are overviewed, with special attention paid to the working mechanisms of these electrolyte additives. Particularly, four representative sulfur‐containing compounds (i.e., 1,3‐propane sultone, prop‐1‐ene‐1,3‐sultone, 1,3,2‐dioxathiolane‐2,2‐dioxide, and ethylene sulfite) are comparatively discussed concerning their impact on electrode–electrolyte interphases and cell performances. Future work on the development of sulfur‐containing compounds as functional electrolyte additives is also provided. The present review is anticipated to be not only a base document to access the status quo in this research domain but also a guideline to select specialized additives and electrolytes for practical applications.image

Silicon micropillar electrodes of lithiumion batteries used for characterizing electrolyte additives* *Project supported by the National Key R&D Program of China (Grant Nos. 2016YFB0100500 and 2016YFB0100100) and the National Natural Science Foundation of China (Grant Nos. 11674387, 11574385, 22005332, 115674368, and 62065005).

The 〈 100 〉 crystal-oriented silicon micropillar array platforms were prepared by microfabrication processes for the purpose of electrolyte additive identification. The silicon micropillar array platform was used for the study of fluorinated vinyl carbonate (FEC), vinyl ethylene carbonate (VEC), ethylene sulfite (ES), and vinyl carbonate (VC) electrolyte additives in the LiPF6 dissolved in a mixture of ethylene carbonate and diethyl carbonate electrolyte system using charge/discharge cycles, electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy, and x-ray photoelectron spectroscopy. The results show that the silicon pillar morphology displays cross-shaped expansion after lithiation/delithiation, the inorganic lithium salt keeps the silicon pillar morphology intact, and the organic lithium salt content promotes a rougher silicon pillar surface. The presence of poly-(VC) components on the surface of FEC and VC electrodes allows the silicon pillar to accommodate greater volume expansion while remaining intact. This work provides a standard, fast, and effective test method for the performance analysis of electrolyte additives and provides guidance for the development of new electrolyte additives.

In Ukrainian

Even partial replacement of graphite in the anode of lithium-ion batteries with silicon can significantly increase their specific energy. But the issue is the insufficient life cycle of such batteries due to the accelerated degradation of the liquid organic electrolyte with traditional lithium hexafluorophosphate, especially at elevated temperatures. The subject of discussions and further research are the processes involving a natural oxide layer on the surface of silicon in the manufacture and electrochemical litiation–delitiation of Si-containing electrodes. Among the most promising areas for solving the issues of practical application of silicon are new additives to the electrolyte and polymeric binders for electrode masses. This paper demonstrates the capability of trimethylsilylisocyanate (with aminosilane and isocyanate functional groups) as an additive to a liquid organic electrolyte (LiPF6 / fluoroethylene carbonate + ethyl methyl carbonate + vinylene carbonate + ethylene sulfite) to scavenge the reactive HF and PF5 species that alleviates the thermal decomposition of fluoroethylene carbonate at elevated temperatures. This makes it possible to increase the electrochemical parameters of half-cells with a hybrid graphite–nanosilicon working electrode when using water-based binders – carboxymethylcellulose and styrene-butadiene rubber. The addition of trimethylsilylisocyanate in the electrolyte significantly improves the reversible capacity of hybrid electrodes and reduces the accumulated irreversible capacity during prolonged cycling at normal temperature and after exposure at 50 °C, therefore to be effective for use in high-energy lithium-ion batteries.

An Attempt to Formulate Non‐Carbonate Electrolytes for Sodium‐Ion Batteries

AbstractNon‐aqueous carbonate solvents have been the main choice for the development of lithium‐ion batteries, and similarly most research on sodium‐ion batteries have been performed using carbonate‐based solvents. However, the differences between sodium and lithium batteries – in term chemistry/electrochemistry properties as well as electrode materials used – open up opportunities to have a new look at solvents that have attracted little attention as electrolyte solvent. This work investigates properties of a wide range of different solvent classes in the context of sodium‐ion battery electrolytes and compares them to the performance of propylene carbonate. The thirteen solvents studied here include one or several members of glymes, carbonates, lactones, esters, pyrrolidones, sulfones, and alkyl phosphates. Out of those, five outperforming solvents of γ‐butyrolactone (GBL), γ‐valerolactone (GVL), N‐methyl‐2‐pyrrolidone (NMP), propylene carbonate (PC), and trimethyl phosphate (TMP) were further investigated using additives of ethylene sulfite (ES), vinylene carbonate (VC), fluoroethylene carbonate (FEC), prop‐1‐ene‐1,3‐sultone (PES), sulfolane (TMS), tris(trimethylsilyl) phosphite (TTSPI), and sodium bis(oxalato)borate (NaBOB). The solvents TMS and tetraethylene glycol dimethyl ether (TEGDME) were tested in 1 : 1 mixtures by volume with the co‐solvents; NMP, dimethoxyethane (DME), and TMP. All electrolytes used NaPF6 as the salt. Primary evaluation relied on electrochemical cycling of full‐cell sodium‐ion batteries consisting of Prussian white cathodes and hard‐carbon anodes. Galvanostatic cycling was performed using both two‐ and three‐electrode cells, in addition, cyclic and linear sweep voltammetry was used to further evaluate the electrolyte formulations. Moreover, the resistance was measured on the anode and cathode, using Intermittent current interruption (ICI) technique.

DFT study of solvation of Li+/Na+ in fluoroethylene carbonate/vinylene carbonate/ethylene sulfite solvents for lithium/sodium-based battery* *Project supported by the International Science & Technology Cooperation of China (Grant No. 2016YFE0102200), the National Natural Science Foundation of China (Grant No. 51902024), the Fundamental Research Funds for the Central Universities, China, the National Postdoctoral Program for Innovative Talents of China (Grant No. BX20180038),

Choosing suitable solvent is the key technology for the electrochemical performance of energy storage device. Among them, vinylene carbonate (VC), fluoroethylene carbonate (FEC), and ethylene sulfite (ES) are the potential organic electrolyte solvents for lithium/sodium battery. However, the quantitative relation and the specific mechanism of these solvents are currently unclear. In this work, density functional theory (DFT) method is employed to study the lithium/sodium ion solvation in solvents of VC, ES, and FEC. We first find that 4VC-Li+, 4VC-Na+, 4ES-Li+, 4ES-Na+, 4FEC-Li+, and 4FEC-Na+ are the maximum thermodynamic stable solvation complexes. Besides, it is indicated that the innermost solvation shells are consisted of 5VC-Li+/Na+, 5ES-Li+/Na+, and 5FEC-Li+/Na+. It is also indicated that the Li+ solvation complexes are more stable than Na+ complexes. Moreover, infrared and Raman spectrum analysis indicates that the stretching vibration of O = C peak evidently shifts to high frequency with the Li+/Na+ concentration reducing in nVC-Li+/Na+ and nFEC-Li+/Na+ solvation complexes, and the O = C vibration peak frequency in Na+ solvation complexes is higher than that of Li+ complexes. The S = O stretching vibration in nES-Li+/Na+ solvation complexes moves to high frequency with the decrease of the Li+/Na+ concentration, the S = O vibration in nES-Na+ is higher than that in nES-Li+. The study is meaningful for the design of new-type Li/Na battery electrolytes.

Cathode-Electrolyte Interphase in Lithium Batteries Revealed by Cryogenic Electron Microscopy

Summary Cathode electrolyte interphase (CEI), the intimate coating layer formed on the positive electrode, has been thought to be critical. However, many aspects of CEI remain unclear. This originates from the lack of effective tools to characterize structural and chemical properties of these sensitive interphases at nanoscale. Here, we develop a protocol to preserve the native state and directly visualize the interface on the positive electrode using cryogenic electron microscopy. We find that under normal operation conditions, there does not exist an intimate coating layer at the single-particle level in carbonate-based electrolyte. However, upon brief external electrical shorting, a solid-electrolyte interphase, which usually forms on anodes, could form on cathodes and be electrochemically converted into a stable, conformal CEI in situ. The conformal CEI helps improve Coulombic efficiency and overall capacity retention of the battery. This generates a different perspective of CEI in commercial carbonate-based electrolytes than previously understood.

Propylene carbonate-nitrile solvent blends for thermally stable gel polymer lithium ion battery electrolytes

Gel polymer electrolytes (GPEs) based on poly (vinylidene difluoride-co-hexafluoropropylene) (PVdF-HFP) containing propylene carbonate (PC), isobutyronitrile (IBN) and trimethyl acetonitrile (TMAN) solvent blend electrolytes were developed to enhance high temperature electrochemical performance and to improve safety of LiNi3/5Mn1/5Co1/5O2 (NMC622)‖graphite lithium ion battery (LIB) cells. These liquid electrolytes (LE) consist of lithium bis(trifluoro-methane)sulfonimide (LiTFSI) as conducting lithium salt and PC/nitrile (1:1, v/v) solvent blends. Ethylene sulfite (ES) and vinylene carbonate (VC) were used as solid electrolyte interphase (SEI) forming additives and contributing to an excellent cycling stability of electrolytes comprising nitrile solvents in NMC622‖graphite cells. Electrochemical impedance spectroscopy (EIS), pulsed field gradient nuclear magnetic resonance spectroscopy (PFG NMR) and relative permittivity determination reveal remarkable ion conducting properties of IBN and TMAN solvents. Since their electrolytes are incompatible with lithium metal electrodes, their electrochemical stability window (ESW) was determined using lithiated lithium titanate (Li7Ti5O12) (LTO) as counter and reference electrodes and the obtained values were confirmed by quantum mechanical computation. Differential scanning calorimetry (DSC) and accelerating rate calorimetry (ARC) confirmed significantly improved safety of IBN and TMAN containing electrolytes. Therefore, PVdF-HFP-based GPEs containing PC/nitrile solvent blends are a promising alternative to SOTA electrolyte for battery cycling at elevated temperature (60 °C) in NMC622‖graphite cells.

Solvent Molecule Cooperation Enhancing Lithium Metal Battery Performance at Both Electrodes

AbstractDeveloping electrolytes compatible with efficient and reversible cycling of electrodes is critical to the success of rechargeable Li metal batteries (LMBs). The Coulombic efficiencies and cycle lives of LMBs with ethylene carbonate (EC), dimethyl carbonate, ethylene sulfite (ES), and their combinations as electrolyte solvents show that in a binary‐solvent electrolyte the extent of electrolyte decomposition on the electrode surface is dependent on the solvent component that dominates the solvation sheath of Li+. This knowledge led to the development of an EC‐ES electrolyte exhibiting high performance for Li||LiFePO4 batteries. Carbonate molecules occupy the solvation sheath and improve the Coulombic efficiencies of both the anode and cathode. Sulfite molecules lead to desirable morphology and composition of the solid electrolyte interphase and extend the cycle life of the Li metal anode. The cooperation between these components provides a new example of electrolyte optimization for improved LMBs.

Solvent Molecule Cooperation Enhancing Lithium Metal Battery Performance at Both Electrodes.

Developing electrolytes compatible with efficient and reversible cycling of electrodes is critical to the success of rechargeable Li metal batteries (LMBs). The Coulombic efficiencies and cycle lives of LMBs with ethylene carbonate (EC), dimethyl carbonate, ethylene sulfite (ES), and their combinations as electrolyte solvents show that in a binary-solvent electrolyte the extent of electrolyte decomposition on the electrode surface is dependent on the solvent component that dominates the solvation sheath of Li+ . This knowledge led to the development of an EC-ES electrolyte exhibiting high performance for Li||LiFePO4 batteries. Carbonate molecules occupy the solvation sheath and improve the Coulombic efficiencies of both the anode and cathode. Sulfite molecules lead to desirable morphology and composition of the solid electrolyte interphase and extend the cycle life of the Li metal anode. The cooperation between these components provides a new example of electrolyte optimization for improved LMBs.

Comprehensive Understanding of Reduction Mechanisms of Ethylene Sulfite in EC-Based Lithium-Ion Batteries

The reliable electrolyte additives are critically important to satisfy the rapidly increasing demand for electrical energy storage with safety, low cost, long life, and high-energy/power density. A...