Development Of New Electrolytes Research Articles

Toward Practical Li–S Batteries: On the Road to a New Electrolyte

AbstractThe lithium–sulfur (Li–S) battery system has attracted considerable attention due to its ultrahigh theoretical energy density and promising applications. However, with the increasing demands on S loading and electrolyte content, practical Li–S batteries still face several serious challenges, such as slow reaction kinetics at the cathode interface, unstable anode interface reactions, and undesirable crosstalk effects between the cathode and anode. Traditional electrolyte systems often struggle to address these challenges under practical conditions, thereby rendering it imperative to establish a new electrolyte system for practical Li–S batteries. This review first discusses the necessity of establishing a new electrolyte and propose specific parameter requirements, such as the electrolyte‐to‐sulfur mass ratio (Em/S). Subsequently, some electrolyte modification strategies proposed by researchers are summarized to address the different challenges associated with practical Li–S batteries. Finally, the combination of different strategies is reviewed, aiming to reveal more effective design approaches that simultaneously address multiple challenges, while providing guidance for establishing a new balanced electrolyte for practical Li–S batteries. This article promotes the development of new electrolytes for practical Li–S batteries and can act as a reference for the development of electrolytes for other secondary batteries.

Computational insights into the structural, thermodynamic and transport properties of CaF2-MgF2 binary fluoride system at high temperatures

The structural, thermodynamic and transport properties of the CaF2-MgF2 molten salt system were investigated with ab initio molecular dynamics (AIMD), system-specific neural network interatomic potentials (NNIPs) and universal PreFerred Potentials (PFP). We trained an NNIP model using AIMD data as input and used this potential to efficiently simulate the interactions within a large supercell in a temperature range of 1273–1773 K. The Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code was employed to validate our trained NNIP model. The Matlantis software with universal PFP is also presented to prove its feasibility for MD calculations and can be considered as a useful alternative simulation tool for higher-order systems where existing potentials are not readily available. We calculated structural and thermodynamic properties including radial distribution function (RDF), angular distribution function (ADF), specific heat capacity, ionic self-diffusivity, and viscosity. Our results indicate that the system exhibited a high degree of structural disorder, with the Ca, Mg, and F ions forming a liquid solution. Using PFP, the positions of the first peak in RDFs for Ca-F and Mg-F pairs are only slightly left-shifted (<0.05 Å), and the estimated viscosity of the melt decreases from 4.613 mPa·s to 1.846 mPa·s with an increase in temperature from 1273 K to 1773 K, in agreement with the NNIP trained specifically for CaF2-MgF2. Our results provide valuable insights into the properties of the CaF2-MgF2 system at high temperatures and serve as predictive models for the development of new electrolytes that could be used for silicon epitaxy by adding silica.

Advancing Metallic Lithium Anodes: A Review of Interface Design, Electrolyte Innovation, and Performance Enhancement Strategies.

Lithium (Li) metal is one of the most promising anode materials for next-generation, high-energy, Li-based batteries due to its exceptionally high specific capacity and low reduction potential. Nonetheless, intrinsic challenges such as detrimental interfacial reactions, significant volume expansion, and dendritic growth present considerable obstacles to its practical application. This review comprehensively summarizes various recent strategies for the modification and protection of metallic lithium anodes, offering insight into the latest advancements in electrode enhancement, electrolyte innovation, and interfacial design, as well as theoretical simulations related to the above. One notable trend is the optimization of electrolytes to suppress dendrite formation and enhance the stability of the electrode-electrolyte interface. This has been achieved through the development of new electrolytes with higher ionic conductivity and better compatibility with Li metal. Furthermore, significant progress has been made in the design and synthesis of novel Li metal composite anodes. These composite anodes, incorporating various additives such as polymers, ceramic particles, and carbon nanotubes, exhibit improved cycling stability and safety compared to pure Li metal. Research has used simulation computing, machine learning, and other methods to achieve electrochemical mechanics modeling and multi-field simulation in order to analyze and predict non-uniform lithium deposition processes and control factors. In-depth investigations into the electrochemical reactions, interfacial chemistry, and physical properties of these electrodes have provided valuable insights into their design and optimization. It systematically encapsulates the state-of-the-art developments in anode protection and delineates prospective trajectories for the technology's industrial evolution. This review aims to provide a detailed overview of the latest strategies for enhancing metallic lithium anodes in lithium-ion batteries, addressing the primary challenges and suggesting future directions for industrial advancement.

Tight-Binding Modelling of Deep Eutectic Solvent Based Electrolytes

Deep eutectic solvents (DES) have in recent years gained momentum in the development of new electrolytes for lithium-ion batteries (LiBs)1. Due to their easy creation, tuning possibilities, wide electrochemical stability windows, and low vapor pressures, they are not only able to create safer LiB electrolytes as compared to traditional organic electrolytes, but more importantly, they may enable high voltage LIB cells2. One aspect not yet fully understood is the connection between the symmetry and entropy of the DES local structure and their macroscopic properties. Exploring this connection could assist in rational design of more performant electrolytes, including controlled electrochemical properties, by symmetry and entropy tuning.Herein, we have studied in detail a few simple DES electrolytes created using the hydrogen bond donor N-methyl-acetamide (MAc) combined with each of the three different lithium salts: LiBF4, LiDFOB, and LiBOB, in 1:4 molar ratios – as previously shown advantageous 3. We chose these salts as they exhibit pseudospherical (BF4-), asymmetrical linear (DFOB), and symmetric linear (BOB) anion geometries and thus are plausible to introduce local symmetry differences. Molecular dynamic simulations were run using DFTB+ 4 and the xTB method 5, and as a first level geometrical analysis we look at the (partial) coordination and solvation numbers of the lithium ions.

Performance Analysis of Different Types of Solid Electrolytes

The development and interest in environmentally friendly cars nowadays present new challenges to the lithium-ion batteries. With the safety problems caused by the liquid electrolyte in conventional batteries, the development of new electrolytes is becoming increasingly urgent. Based on the existing literature, this paper discusses the following: (1) the advantages and disadvantages of solid-state electrolytes; (2) Requirements for solid electrolytes; (3) Classification and characteristics of solid electrolytes; (4) Properties of different types of electrolytes; (5) Future application and research direction. Performance and possible applications of different solid-state electrolytes are presented in this paper. Specifically, it is found that inorganic solid electrolytes are the best in ion transference number, making them suitable for quick charging batteries. Polymer-based solid electrolytes perform better at electrochemical window, so they can be used to enhance the energy density of batteries. Polyethylene glycol (PEG) based composite solid electrolytes and sulfide solid electrolytes have the highest ionic conductivity, so they are optimum materials for high-rate performance batteries.

Molecular Origin of High Cation Transference in Mixtures of Poly(pentyl malonate) and Lithium Salt

The rational development of new electrolytes for lithium batteries rests on the molecular-level understanding of ion transport. We use molecular dynamics simulations to study the differences between a recently developed promising polymer electrolyte based on poly(pentyl malonate) (PPM) and the well-established poly(ethylene oxide) (PEO) electrolyte; LiTFSI is the salt used in both electrolytes. Cation transference is calculated by tracking the correlated motion of different species. The PEO solvation cage primarily contains 1 chain, resulting in strong correlations between Li+ and the polymer. In contrast, the PPM solvation cage contains multiple chains, resulting in weak correlations between Li+ and the polymer. This difference results in a high cation transference in PPM relative to PEO. Our comparative study suggests possible designs of polymer electrolytes with ion transport properties better than both PPM and PEO. The solvation cage of such a hypothetical polymer electrolyte is proposed based on insights from our simulations.

Differentiating between Ion Transport and Plating–Stripping Phenomena in Magnesium Battery Electrolytes Using Operando Raman Spectroscopy

Understanding metal plating–stripping and mass transport processes is necessary for the development of new electrolytes for post-lithium energy storage applications. Operando vibrational spectroscopy is a valuable analytical tool for this purpose, enabling structural and chemical changes at electrode–electrolyte interfaces to be probed dynamically, under battery cycling conditions. In this work we apply operando Raman spectroscopy to characterize the behavior of the Mg based “all phenyl complex” [Mg2Cl3]+[AlPh4]− in tetrahydrofuran (THF), an exemplar electrolyte for emerging Mg battery technologies. We demonstrate that the observed electrolyte Raman band intensities vary reversibly with electrochemical cycling due to anion migration in response to the applied electric field, while Mg plating and stripping can be monitored independently through the broad background scattering intensity. Spectral measurements across different sites of the platinum working electrode indicate that the ion transport response is spatially heterogeneous, while the plating and stripping response is ubiquitous.

Exploring the Carbon/Electrolyte Interface in Supercapacitors Operating in Highly Concentrated Aqueous Electrolytes.

The development of superconcentrated or water-in-salt electrolytes (WISEs) has paved a new way toward realizing environmentally friendly, nonflammable batteries and supercapacitors based on aqueous electrolytes. The development of new electrolytes, such as WISEs, needs to be accompanied by further studies of the charging mechanism. This is essential to guide the choice of the electrode/electrolyte pairs for optimizing the performance of WISE-based supercapacitors. Therefore, to optimize the performance of carbon/carbon supercapacitors when using new, superconcentrated electrolytes, we present a detailed investigation of the carbon/electrolyte interface by combining electrochemical measurements with Raman and NMR spectroscopy and mass spectrometry. In particular, NMR provides crucial information about the local environment of electrolyte ions inside the carbon pores of the electrode. The results show that the structure of the electrolyte strongly depends on the concentration of the electrolyte and affects the mechanism of charge storage at the positive and negative electrodes.

Sodium Borates: Expanding the Electrolyte Selection for Sodium‐Ion Batteries

AbstractSodium‐ion batteries (SIBs) are a promising grid‐level storage technology due to the abundance and low cost of sodium. The development of new electrolytes for SIBs is imperative since it impacts battery life and capacity. Currently, sodium hexafluorophosphate (NaPF6) is used as the benchmark salt, but is highly hygroscopic and generates toxic HF. This work describes the synthesis of a series of sodium borate salts, with electrochemical studies revealing that Na[B(hfip)4]⋅DME (hfip=hexafluoroisopropyloxy, OiPrF) and Na[B(pp)2] (pp=perfluorinated pinacolato, O2C2(CF3)4) have excellent electrochemical performance. The [B(pp)2]− anion also exhibits a high tolerance to air and water. Both electrolytes give more stable electrode‐electrolyte interfaces than conventionally used NaPF6, as demonstrated by impedance spectroscopy and cyclic voltammetry. Furthermore, they give greater cycling stability and comparable capacity to NaPF6 for SIBs, as shown in commercial pouch cells.

Sodium Borates: Expanding the Electrolyte Selection for Sodium-Ion Batteries.

Sodium‐ion batteries (SIBs) are a promising grid‐level storage technology due to the abundance and low cost of sodium. The development of new electrolytes for SIBs is imperative since it impacts battery life and capacity. Currently, sodium hexafluorophosphate (NaPF6) is used as the benchmark salt, but is highly hygroscopic and generates toxic HF. This work describes the synthesis of a series of sodium borate salts, with electrochemical studies revealing that Na[B(hfip)4]⋅DME (hfip=hexafluoroisopropyloxy, OiPrF) and Na[B(pp)2] (pp=perfluorinated pinacolato, O2C2(CF3)4) have excellent electrochemical performance. The [B(pp)2]− anion also exhibits a high tolerance to air and water. Both electrolytes give more stable electrode‐electrolyte interfaces than conventionally used NaPF6, as demonstrated by impedance spectroscopy and cyclic voltammetry. Furthermore, they give greater cycling stability and comparable capacity to NaPF6 for SIBs, as shown in commercial pouch cells.

Achieving a Wider Window Potential in Aqueous Supercapacitors By an Artificial Interface

Devices with high power density which can store energy with a fast rate charge-discharge, the supercapacitors are suitable in different applications where high power is needed. That because it stores charge by fast surface process, i.e. ion adsorption of an electrolyte into the electrochemical double layer at the electrode/electrolyte interface. Nevertheless, in order to extend their autonomy beyond few seconds, its energy density has to be increased. For this aspect, in recent years many teams around the world have set up different strategies as a combination of a carbon electrode with a faradic type electrode (battery electrode or pseudocapacitive) or through the development of new active materials, including the development of new electrolytes. The main significant achievements are more on the active material side. Even though some works have been successful in increasing the cell voltage, thanks to the use of new ionic liquids, they are still room for improvement regarding the increase of the cell voltage.To address this point, we have targeted to obtain an aqueous-based high voltage supercapacitor. Our strategy consists in using an Artificial Interface (ai) by depositing an ionogel onto a carbon electrode, the ai is composed of an inorganic matrix and an ionic liquid, in order to form a passivation layer at the electrode/electrolyte interface; a better electrochemical and thermal stability of this interface is thus expected. The ai has got to be electronically insulating but ionic conductive, limiting or even preventing the transfer of electronic charge to the electrode / electrolyte interface.1,2 First things first, the study have been carried out on glassy carbon where AI has been deposited and the linear sweep voltammetry tests in an aqueous electrolyte based on EMI+ HSO4 - and H2SO4 indicate, in both cases, an increase in the potential window: the onset potential for water reduction is shifted toward more cathodic potentials. Going further, tests in the presence of a redox probe (Ferri-Ferro potassium cyanide) demonstrate the absence of electron transfer at the electrode/electrolyte interface. On the other hand, it appears, thanks to measurements carried out by electrochemical impedance spectroscopy, since within the ai is embedded EMI+ TFSI-, better ionic conduction is obtained when the electrolyte is made of EMI+ HSO4 -, sharing the same cation than the one of ai. As we will be showing, a better transference number is achieved for EMI+ cations than for H+. Figure 1

Reduced Gassing In Lithium-Ion Batteries With Organosilicon Additives

The release of gases through electrolyte decomposition is a problem of prominent concern in the Li-ion battery industry, due to the negative impact of gassing on cell safety and performance. The development of new electrolytes and additives is essential in enabling low-gassing batteries. Organosilicon (OS) molecules, which merge a silane with a Li+ coordinating functionality, have been developed by Silatronix® as additions to conventional carbonate electrolytes, demonstrating critical high thermal and voltage stability to enable next-generation Li-ion batteries. In this study we report performance testing and fundamental mechanistic studies to investigate gassing phenomena in advanced Li-ion chemistries under storage test conditions. Novel organosilicon nitriles developed by Silatronix® as well as common gas reducing additives (i.e. 1,3-propanesultone, succinonitrile) were evaluated in a 4.35 V Graphite/NMC622 (LiNi0.6Mn0.2Co0.2O2) multi-layer pouch cell. Potential synergies between OS materials and these additives were investigated. The dependence of gassing on electrolyte composition and test conditions was investigated, and connections between gassing behavior and electrode surface chemistry are also reported. Key experimental results show that all OS concentrations reduce gas generation during 60 °C storage, and higher OS content provides greater benefit. Overall, we show that organosilicon additives substantially reduce gassing from carbonate-based electrolytes while maintaining cell performance.

An Artificial Interface By Sol-Gel Chemistry to Open the Window of an Aqueous Supercapacitor

Devices with high power density which can store energy with a fast rate charge-discharge, the supercapacitors are suitable in different applications where high power is needed. That because it stores charge by fast surface process, i.e. ion adsorption of an electrolyte into the electrochemical double layer at the electrode/electrolyte interface. Nevertheless, in order to extend their autonomy beyond few seconds, its energy density has to be increased. For this aspect, in recent years many teams around the world have set up different strategies as a combination of a carbon electrode with a faradic type electrode (battery electrode or pseudocapacitive) or through the development of new active materials, including the development of new electrolytes. The main significant achievements are more on the active material side. Even though some works have been successful in increasing the cell voltage, thanks to the use of new ionic liquids, they are still room for improvement regarding the increase of the cell voltage.To address this point, we have targeted to obtain an aqueous-based high voltage supercapacitor. Our strategy consists in using an Artificial Interface (AI) by depositing an ionogel onto a carbon electrode, the AI is composed of an inorganic matrix and an ionic liquid, in order to form a passivation layer at the electrode/electrolyte interface; a better electrochemical and thermal stability of this interface is thus expected. The AI has got to be electronically insulating but ionic conductive, limiting or even preventing the transfer of electronic charge to the electrode / electrolyte interface.1,2 First things first, the study have been carried out on glassy carbon where AI has been deposited and the linear sweep voltammetry tests in an aqueous electrolyte based on EMI+ HSO4 - and H2SO4 indicate, in both cases, an increase in the potential window: the onset potential for water reduction is shifted toward more cathodic potentials. Going further, tests in the presence of a redox probe (Ferri-Ferro potassium cyanide) demonstrate the absence of electron transfer at the electrode/electrolyte interface. On the other hand, it appears, thanks to measurements carried out by electrochemical impedance spectroscopy, since within the AI is embedded EMI+ TFSI-, better ionic conduction is obtained when the electrolyte is made of EMI+ HSO4 -, sharing the same cation than the one of AI. As we will be showing, a better transference number is achieved for EMI+ cations than for H+ still further works are needed to improve the selectivity of the AI to improve its stability over cycling.1. Z. H. Zhang et al., Sci. Rep., 8, 1–12 (2018).2. M. D. Elola and J. Rodriguez, J. Phys. Chem. C, 123, 3622–3633 (2019).

Eco-friendly NaCl-based electrolyte for electropolishing 316L stainless steel

Abstract Since the environmental and safety issues closely related to the widely used mixture electrolytes of H2SO4 and H3PO4 in electropolishing 316 L stainless steel, the development of new electrolytes, which do not contain any acid is of a great demand. This study is to electropolish 316 L stainless steel in a NaCl-based electrolyte, not containing any acid as the conventionally used electrolytes. The electropolishing effect with the NaCl-based electrolyte is compared with the conventional H2SO4-based electrolyte. The experimental results show that the proposed electrolyte can be used for the electropolishing of 316 L stainless steel to obtain a comparable electropolishing effect with the conventional H2SO4-based electrolyte. Moreover, the NaCl-based electrolyte shows a higher material removal rate than the H2SO4-based electrolyte. It is also found that a brown product generated and covered on the anode electrode surface during the electropolishing with the NaCl-based electrolyte. According to the EDS analysis, it mainly contains dissolved metal elements, Cl and Na element from the used electrolyte. Furthermore, the electropolishing effect can be improved by the ethanol addition in the NaCl-based electrolyte due to the reduced influence of the brown product.

Electrode material–ionic liquid coupling for electrochemical energy storage

The development of new electrolyte and electrode designs and compositions has led to advances in electrochemical energy-storage (EES) devices over the past decade. However, focusing on either the electrode or electrolyte separately is insufficient for developing safer and more efficient EES devices in various working environments, as the energy-storage ability is determined by the ion arrangement and charge and/or electron transfer at the electrode–electrolyte interface. In this Review, we assess the fundamental physicochemical and electrochemical properties at the electrode–electrolyte interfaces in Li-ion batteries and supercapacitors using safe and electrochemically stable ionic-liquid electrolytes. Key reactions and interactions at the electrode–electrolyte interface, as well as geometric constraints and temperature effects, are highlighted. Building on the fundamental understanding of interfacial processes, we suggest potential strategies for designing stable and efficient ionic-liquid-based EES devices with emerging electrode materials. The development of efficient, high-energy and high-power electrochemical energy-storage devices requires a systems-level holistic approach, rather than focusing on the electrode or electrolyte separately. In this Review, we discuss the interfacial reactions and ion transport in ionic-liquid-based Li-ion batteries and supercapacitors, and summarize their impact on device performance.

An Artificial Interface (AI) to Open the Window for Aqueous Electrolytes

Devices with high power density which can store energy with a fast rate charge-discharge, the supercapacitors are suitable in different applications where high power is needed. That because it stores charge by fast surface process, i.e. ion adsorption of an electrolyte into the electrochemical double layer at the electrode/electrolyte interface. Nevertheless, in order to extend their autonomy beyond few seconds, its energy density has to be increased. For this aspect, in recent years many teams around the world have set up different strategies as a combination of a carbon electrode with a faradic type electrode (battery electrode or pseudocapacitive) or through the development of new active materials, including the development of new electrolytes. The main significant achievements are more on the active material side. Even though some works have been successful in increasing the cell voltage, thanks to the use of new ionic liquids, they are still room for improvement regarding the increase of the cell voltage.To address this point, we have targeted to obtain an aqueous-based high voltage supercapacitor. Our strategy consists in using an Artificial Interface (AI) by depositing an ionogel onto a carbon electrode, the AI is composed of an inorganic matrix and an ionic liquid, in order to form a passivation layer at the electrode/electrolyte interface; a better electrochemical and thermal stability of this interface is thus expected. The IA has got to be electronically insulating but ionic conductive, limiting or even preventing the transfer of electronic charge to the electrode / electrolyte interface.1,2 First things first, the study have been carried out on glassy carbon where AI has been deposited and the linear sweep voltammetry tests in an aqueous electrolyte based on EMI+ HSO4 - and H2SO4 indicate, in both cases, an increase in the potential window: the onset potential for water reduction is shifted toward more cathodic potentials. Going further, tests in the presence of a redox probe (Ferri-Ferro potassium cyanide) demonstrate the absence of electron transfer at the electrode/electrolyte interface. On the other hand, it appears, thanks to measurements carried out by electrochemical impedance spectroscopy, since within the IA is embedded EMI+ TFSI-, better ionic conduction is obtained when the electrolyte is made of EMI+ HSO4 -, sharing the same cation than the one of IA. As we will be showing, a better transference number is achieved for EMI+ cations than for H+ still further works are needed to improve the selectivity of the IA to improve its stability over cycling.1. Z. H. Zhang et al., Sci. Rep., 8, 1–12 (2018).2. M. D. Elola and J. Rodriguez, J. Phys. Chem. C, 123, 3622–3633 (2019).

Electrochemically Stable, High Transference Number Lithium Bis(malonato)borate Polymer Solution Electrolytes

Implementation of next-generation Li-ion batteries based on high-voltage cathodes requires the development of new electrolytes that are stable over wide electrochemical potential windows. High lith...

Effect of Molecular Structures on the Charge-Discharge Performance for Organic Redox Flow Battery

Power generation systems using natural energy such as solar and wind power that does not generate greenhouse gases such as carbon dioxide have been actively introduced all over the world. In order to use such renewable energy efficiently, an energy storage system is required with introducing the power generation system. Large scale storage batteries are promising as energy storage system and are famous for lithium ion batteries, sodium-sulfur batteries, lead storage batteries and redox flow batteries (RFB).1-3 RFB can be enlarged relatively easily because its capacity (tank) and output (cell) can be designed independently, and has features not found in other secondary batteries. In recent years, development of new electrolyte to replace vanadium RFB has been vigorously promoted. For example, a RFB using titanium-manganese (Ti-Mn) as an electrolyte is expected to have lower cost and higher performance than a vanadium RFB.4,5 In addition, in the case of a RFB using an organic molecule exhibiting redox activity as an electrolyte, because the adjustment of the multi-electron transfer reaction and the redox potential can be achieved by complex formation with metal ions, introduction of various functional groups, and polymerization, in recent years, batteries having high energy density comparable to vanadium RFB have been developed.6-8 In RFB, improvement of the energy density of the electrolyte is one of the most important issues. Here, we designed organic-based active materials with high solubility, and studied their application to RFB for the purpose of improvement of energy density. The viologen units exhibiting high solubility were arranged in a tree-like manner, and water-soluble model compounds containing 3, 5, and 13 molecules of viologen units, respectively, were synthesized. These compounds were confirmed to improve energy efficiency as compared to methyl viologen alone in charge-discharge test. In addition, in the case of compound containing 5 molecules of viologen unit, it has been found that it dissolves to about 1 M equivalent, and the theoretical capacity reaches 134 Ah/L. It is thought that the solubility can be improved by arranging the molecules regularly, which may lead to the improvement of energy density and the advance of the battery performance.

Effect of Electrolyte Composition on Performance and Stability of Lithium–Sulfur Batteries

The development of new electrolytes for lithium–sulfur (Li–S) batteries is important. Electrolytes based on 1:1 glyme:Li+ complexes can be locally destroyed to form free glyme during charge/discharge cycles. Free glyme can cause Li2Sx dissolution, which is a major factor in Li–S battery degradation. To decrease the local generation of free glyme, the glyme:Li+ electrolytes with higher proportions of Li salts are developed to control the Li2Sx dissolution into the electrolyte. The chemical solubility of Li2S8 and the charge/discharge properties of Li–S cells are investigated by varying the glyme:Li salt molar ratio. Nonequimolar (high Li salt concentration) glyme:Li salt mixture electrolytes directly suppress the Li2S8 dissolution and improve the charge/discharge properties (cycling and coulombic efficiency) of Li–S cells. The electrolyte composition can control the chemical stability of reactive intermediates at the Li2Sx electrode and provide high‐performance Li–S cells for next‐generation batteries.

Properties of Silicon-Electrolyte Interphase (SEI) – Individual Components

The stabilization of a solid electrolyte interphase (SEI) is one of the great challenges to utilize superior theoretical capacity (about 3,600 mAh g-1, almost 10 times higher than that of graphite) of a silicon (Si) as an anode in a next-generation advanced lithium-ion battery (LIB). A SEI remains a poorly understood and hardly studied topic relative to the research devoted to battery components due to its intrinsic properties of complexity, reactivity and continuous evolution.1 However, the SEI plays a key role in prevention of further electrolyte reduction and desolvation of Li+ ions, which is directly related to electrochemical performance, lifetime and safety of batteries. For example, the unstable SEI on a Si anode leads to initial irreversible capacity losses, poor cycling stability and a limited cycle life.2-4 In this study each ‘individual’ component of SEI on a Si anode was prepared as a thin film, and the physical, electrochemical, mechanical and structural properties of prepared films were characterized using a variety of analytical equipment including electrochemical impedance spectroscopy, operando X-ray photoelectron spectroscopy, atomic force microscope, Fourier-transform infrared spectroscopy, scanning spreading resistance microscopy and time-of-flight secondary ion mass spectrometry. This study can provide a strong guidance to aid in the development of new electrolytes, additives and binders to stabilize SEI layer on a silicon anode by identifying beneficial components and providing mechanical explanation of a variety of reactions and phenomena in a SEI. References M. Gauthier, T. J. Carney, A. Grimaud, L. Giordano, N. Pour, H.-H. Chang, D. P. Fenning, S. F. Lux, O. Paschos, C. Bauer, F. Maglia, S. Lupart, P. Lamp and Y. Shao-Horn, J. Phys. Chem. Lett. 2015, 6, 4653.B. Philippe, R. Dedryvere, M. Gorgoi, H. Rensmo, D. Gonbeau, and K. Edstrom, Chem. Mater. 2013, 25, 394.T. Jaumann, J. Balach, M. Klose, S. Oswald, U. Langklotz, A. Michaelis, J. Eckerta, and L. Giebelera, Phys. Chem. Chem. Phys. 2015, 17, 24956.B. T. Young, D. R. Heskett, C. C. Nguyen, M. Y. Nie, J. C. Woicik, and B. L. Lucht, ACS Appl. Mater. Interface 2015, 7, 20004.