Electrolytes For Li-ion Batteries Research Articles

Double-salt electrolyte for Li-ion batteries operated at elevated temperatures

Lithium ion batteries (LIBs) have swept the whole energy storage field. However, the current mainstream lithium batteries are difficult to operate stably at high temperature (>60°C) due to the decomposition of electrolyte and solid electrolyte interphase (SEI), the cathode metal elements dissolution behavior, and potential thermal runaway. Here, We report a double-salt electrolyte with lithium bis(fluorosulfonyl)imide (LiFSI) and lithium difluoro(oxalato)borate (LiDFOB) as electrolyte salt, fluoroethylene carbonate (FEC), and tetra(ethylene glycol) dimethyl ether (TEGDME) as cosolvent, which delivers excellent ionic conductivity, high electrochemical stability and satisfactory ability to impede the dissolution of Fe element under elevated temperature (70°C). In addition, the electrolyte is benefited to form a robust and thermal-resistance solid-electrolyte interface (SEI) layer on the surface of graphite (Gr) anode, which shows improved decomposition temperature (86°C). The assembled thermally stable and high-safety 1300 mAh 18650-type LiFePO4|Gr cell shows high Coulombic efficiency (∼99.7%), improved cycling stability with discharge capacity 871.1 mAh after 200 cycles at 0.5 C and 70°C. This work affords a splendid strategy for address the unstable interface at both cathode and anode for safe high-temperature LIBs.

Polyethylene glycol-grafted cellulose-based gel polymer electrolyte for long-life Li-ion batteries

Recently, highly abundant natural materials have been used in the fields of energy storage because of their environmental friendliness and low cost. However, use of some natural materials like cellulose as host matrices of gel polymer electrolytes (GPEs) is challenging owing to the strong intra- and inter-molecular hydrogen bonding. Herein, a green GPE film was prepared by chemically grafting soft chain-polyethylene glycol (PEG) onto the backbone of cellulose. The introduction of PEG significantly improved the toughness of cellulose from 118 × 103to 270 × 103kJ m−3, as well as raised the wettability in carbonate-based liquid electrolyte solutions from 22.6% to 141.7%. The first cycle coulomb efficiency stayed above 90%. The capacity retention of LiFePO4/Libatteries assembled with the as-obtained GPEreached 80.3% after 300 cycles at 0.2 C. In sum, the as-obtained cellulose-based GPEs look promising to replace separators and liquid electrolytes in Li-ion batteries.

Li-Ion Transport and Solvation of a Li Salt of Weakly Coordinating Polyanions in Ethylene Carbonate/Dimethyl Carbonate Mixtures.

Electrolytes with a high Li-ion transference number (tLi) have attracted significant attention for the improvement of the rapid charge-discharge performance of Li-ion batteries (LIBs). Nonaqueous polyelectrolyte solutions exhibit high tLi upon immobilization of the anion on a polymer backbone. However, the transport properties and Li-ion solvation in these media are not fully understood. Here, we investigated the Li salt of a weakly coordinating polyanion, poly[(4-styrenesulfonyl)(trifluoromethanesulfonyl)amide] (poly(LiSTFSA)), in various ethylene carbonate and dimethyl carbonate mixtures. The highest ionic conductivity was unexpectedly observed for the lowest polar mixture at the highest salt concentration despite the low dissociation degree of poly(LiSTFSA). This was attributed to a unique conduction phenomenon resulting from the faster diffusion of transiently solvated Li ions along the interconnected aggregates of polyanion chains. A Li/LiFePO4 cell using such an electrolyte demonstrated improved rate capability. These results provide insights into a design strategy of nonaqueous liquid electrolytes for LIBs.

Determining the Composition of Carbonate Solvent Systems Used in Lithium-Ion Batteries without Salt Removal

In this work, two methods were investigated for determining the composition of carbonate solvent systems used in lithium-ion (Li-ion) battery electrolytes. One method was based on comprehensive two-dimensional gas chromatography with electron ionization time-of-flight mass spectrometry (GC×GC/EI TOF MS), which often enables unknown compound identification by their electron ionization (EI) mass spectra. The other method was based on comprehensive two-dimensional gas chromatography with flame ionization detection (GC×GC/FID). Both methods were used to determine the concentrations of six different commonly used carbonates in Li-ion battery electrolytes (i.e., ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and vinylene carbonate (VC) in model compound mixtures (MCMs), single-blind samples (SBS), and a commercially obtained electrolyte solution (COES). Both methods were found to be precise (uncertainty < 5%), accurate (error < 5%), and sensitive (limit of detection <0.12 ppm for FID and <2.7 ppm for MS). Furthermore, unlike the previously reported methods, these methods do not require removing lithium hexafluorophosphate salt (LiPF6) from the sample prior to analysis. Removal of the lithium salt was avoided by diluting the electrolyte solutions prior to analysis (1000-fold dilution) and using minimal sample volumes (0.1 µL) for analysis.

Biphasic solid electrolytes with homogeneous Li-ion transport pathway enabled by metal–organic frameworks

Solid-state lithium batteries (SSLBs) based on non-flammable inorganic solid electrolytes have been proposed as promising technical solutions to resolve safety issues caused by flammable organic liquid electrolytes of current Li-ion batteries. Biphasic solid electrolytes (BSEs) comprising Li+-conducting oxides and polymers have garnered significant interest for SSLBs because of their mechanical robustness and high Li+ conductivity. However, the non-uniform distribution of oxide particles and polymer species in BSEs may cause inhomogeneous Li+ conduction, thereby resulting in poor interfacial stability with electrodes during repeated charge–discharge cycles. Herein, we report a Li7La3Zr2O12-based BSE with homogeneous Li+ transport pathways achieved by a metal–organic framework (MOF) layer. To regulate and homogenize the Li+ flux across the interface between the BSE and electrode, a free-standing BSE is integrated with the MOF layer. The MOF-integrated BSE forms smooth and uniform interfaces with nanoporous channels in contact with the electrodes, effectively enhancing the interfacial solid–solid contact and facilitating homogeneous Li+ transport. An SSLB with the MOF-BSE membrane shows enhanced cycling stability and rate-capability compared to the battery with bare BSE. This study demonstrates that the proposed electrolyte design provides an effective approach for improving the conducting properties and interfacial stability of BSEs for high-performance and long-cycling SSLBs.

The Use of LiFSI and LiTFSI in LiFePO4/Graphite Pouch Cells to Improve High-Temperature Lifetime

The use of LiPF6 in Li-ion battery electrolytes provides sufficient stability, conductivity, and cost in most applications. However, LiPF6 has also been known to cause degradation in Li-ion cells, primarily from its thermal decomposition or hydrolysis to form acidic species. This work considers the use of imide salts lithium bis(fluorosulfonyl)imide (LiFSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as an alternative to LiPF6 in LiFePO4/Graphite cells. The use of LiFSI or LiTFSI over LiPF6 improved cycling performance both in control electrolyte (no additives) and electrolyte containing 2% vinylene carbonate (VC). However, while metrics from ultra high precision coulometry, isothermal microcalorimetry, and storage experiments all agreed with long-term cycling results for cells with control electrolyte, the opposite was seen with 2VC electrolyte. Pouch bag experiments elucidated information about the origin of parasitic reactions in LFP/Graphite cells, showing that most parasitic reactions originate at the negative electrode. Additionally, pouch bag experiments reveal a more passivating graphite solid electrolyte interphase (SEI) for LiFSI + 2VC electrolyte, agreeing with long term cycling experiments. It is concluded that in control electrolyte, the use of LiFSI limits redox shuttles, Fe dissolution, and SEI decomposition, while in 2VC electrolyte, LiFSI introduces a minor self-discharge reaction that does not impact long-term cycling.

Hydrides compounds for electrochemical applications

Hydrides have been used since a long time for solid-state hydrogen storage and electrochemical nickel-metal hydride batteries. Besides these applications, growing attention has been devoted to their development as anode materials, as well as solid electrolytes for Li-ion and other ion batteries. Herein, we review and summarize the recent advances of hydrides as negative electrodes for Ni- M H and A -ion batteries ( A = Li, Na), and as electrolyte for all solid-state batteries (ASSB). Metallic hydrides such as intergrowth compounds are highlighted as the best compromise up to now for Ni- M H. Regarding anodes of Li-ion batteries, MgH 2 , especially its combination with TiH 2 , provides very promising results. Complex hydrides such as Li-borohydride and related closo-borates and monovalent carborate boron clusters appear to be very attractive as solid electrolytes for Li-based ASSB, whereas closo-hydroborate sodium salts and closo-carboborates are investigated for Na- and Mg-ASSB. Finally, further research directions are foreseen for hydrides in electrochemical applications.

Li+ concentration waves in a liquid electrolyte of Li-ion batteries with porous graphite-based electrodes

Electrolyte solutions function as ionic conductors in Li-ion batteries and inevitably induce concentration gradients during battery operation. It is shown that in addition to these concentration gradients, very specific Li+ concentration waves in the electrolyte are formed in graphite-based porous electrode/Li cells. This phenomenon has been investigated by both simulations and experiments. From the simulations, it has been concluded that the occurring Li+ concentration waves in the electrolyte vary with position and time. Such waves originate from the fluctuations of the reaction distribution inside the porous electrode and depend on both the thermodynamics (open-circuit voltage, OCV) and kinetics (charge transfer reaction heterogeneity). Li+ concentration waves occurring inside the separator region are directly related to the battery output voltage at low current applications. A four-electrode device is used to validate the electrolyte concentration waves experimentally. The electric potential differences between the reference electrodes and counter electrode show regular fluctuations, demonstrating the existence of concentration waves in the electrolyte. The simultaneous appearance of the fluctuations in the potential differences and the transitions from plateaus to slopes in the battery output voltage illustrates the dependency of Li+ concentration waves on the thermodynamics and kinetics of the electrochemical reactions.

A lightweight localized high-concentration ether electrolyte for high-voltage Li-Ion and Li-metal batteries

The emerging localized high-concentration electrolytes (LHCEs) with small salt dosage, low viscosity, and favorable electrode wettability have triggered extensive research interest recently. However, so far, it is still challenging to develop an LHCE that has both superior anode compatibility and high voltage stability, as well as low density and low cost to construct high specific energy batteries. In this work, we propose an anode-compatible and high-voltage (up to 4.7 V) ether-based LHCE by introducing the cost-efficient (~0.385 $ g−1) and lightweight (1.19 g cm−3) benzotrifluoride (BTF) as a diluent (BTF-LHCE). Benefitting from the unique solvation structure and interfacial chemistry of the BTF-LHCE, ultrahigh average Coulombic efficiency (CE) can be achieved in the BTF-LHCE system both for the Si (99.83%) and metallic Li anodes (99.45%). Notably, the assembled Si||NCM622 and Li||NCM622 pouch cell based on our designed BTF-LHCE can realize high cell-level specific energy densities of 257.4 and 349.4 Wh kg−1, respectively, which are among the best values reported. This study provides a promising strategy to develop advanced ether-based electrolytes towards large-scale applications of high-voltage and high-specific-energy battery technologies.

The effect of inorganic nanoparticles on ion conduction in poly(lithium acrylate)-based composite polymer electrolytes for energy storage devices

Recently, considerable researches are conducted to develop promising polymer electrolytes for Li-ion batteries (LIBs). Herein, we prepared poly(lithium acrylate) (PAALi)-based composite polymer electrolytes (CPEs) containing alumina (Al2O3) nanoparticles. The addition of inorganic nanoparticles into the PAALi matrix can not only improve CPE’s ionic conductivity ( at 303 K), but also enhance CPE’s mechanical properties due to the nanoparticles acting as cross-linkers between the PAALi chains. We systematically investigated the influences of inorganic nanoparticle types (pure alumina vs. vinyl functionalized alumina) and contents on ionic conduction and mechanical properties of PAALi-based CPEs.

Local structures and dynamics of interfacial imidazolium-based ionic liquid depending on the electrode potential using electrochemical attenuated total reflectance ultraviolet spectroscopy

Recently, ionic liquids (ILs) have attracted attention as prospective electrolytes for Li-ion batteries, with safe performance. Herein, the dynamics of the IL at the electrochemical interface, which is the key to the electrochemical reaction, was monitored using attenuated total reflectance far- and deep-ultraviolet (ATR-FUV-DUV) spectroscopy. An original measurement system, which combined an ATR-FUV-DUV spectrometer with a Kretschmann type (fully metal-coated prism) electrochemical setup, was assembled. Spectral measurements and assignments were performed for the 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([EMIM][TFSI])/Pt electrode (∼7 nm) interface. The incident light in the FUV and DUV regions entered a measurement system comprising an [EMIM][TFSI]/Pt electrode/ATR sapphire prism, and the potential-dependent absorption spectra were measured in the 180–450 nm range. This in-situ spectroscopic technique is unique in that the electronic transition spectra of the interfacial IL can be obtained. By switching the applied potentials, temporal spectral changes (i.e. relaxation signals) were tracked at wavelengths of 450 nm and 221 nm, where the direct electronic absorption of the IL was active and inactive, respectively. Comparing these relaxation times, it was revealed that the absorption signal at 221 nm changed more slowly than that at 450 nm. This indicated that the molecular conformations that affected the electronic absorption of the interfacial ILs changed slowly. Considering the surface-normal dipole selection rule for molecules on a metal surface, it is suggested that the slow changes in the molecular conformations can be ascribed to the potential-dependent interfacial orientations of [EMIM]+.

A Review on Green Polymer Binder-based Electrodes and Electrolytes for All Solid-State Li-ion batteries

It is not an exaggerated fact that the whole world relies on the energy storage systems such as Li-ion batteries (LIBs). Li-ion batteries have been widely used in electric vehicles and electronic devices such as laptops, mobile phones, etc. However, the commercial Li-ion batteries have many issues associated with safety and durability including the thermal runaway and the use of toxic solvents during the construction of batteries. In order to highlight the recent developments towards addressing these issues, we have summarized the major impact in replacing the toxic solvents, which are conventionally used to dissolve the binder in the commercial Li-ion batteries, with the aqueous-based binder called green binders. Further, an emphasis has been given on the importance of shifting from flammable liquid electrolytes to non-flammable solid-electrolytes, which essentially suppress the issues such as leakage problems, mechanical failure and fire explosives in LIBs. Even though considerable works have been performed on the development of green-based solid polymer electrolytes, it still needs more effort to overcome the obstacles towards improving the properties of the solid-polymer matrix, which is their low ionic conductivity at low temperatures. Further research in this direction has been highlighted in this review, which involves improving the interfacial contacts in the solid-polymer electrolytes, where the interfacial interaction and conductive mechanisms are yet to be clearly investigated to have the solid-electrolytes with improved electrochemical property.

Micro-Structural Design of Soft Solid Composite Electrolytes With Enhanced Ionic Conductivity

Abstract Electrolyte in a rechargeable Li-ion battery plays a critical role in determining its capacity and efficiency. While the typically used electrolytes in Li-ion batteries are liquid, soft solid electrolytes are being increasingly explored as an alternative due to their advantages in terms of increased stability, safety and potential applications in the context of flexible and stretchable electronics. However, ionic conductivity of solid polymer electrolytes is significantly lower compared to liquid electrolytes. In a recent work, we developed a theoretical framework to model the coupled deformation, electrostatics and diffusion in heterogeneous electrolytes and also established a simple homogenization approach for the design of microstructures to enhance ionic conductivity of composite solid electrolytes. Guided by the insights from the theoretical framework, in this paper, we examine specific microstructures that can potentially yield significant improvement in the effective ionic conductivity. We numerically implement our theory in the open source general purpose finite element package FEniCS to solve the governing equations and present numerical solutions and insights on the effect of microstructure on the enhancement of ionic conductivity. Specifically, we investigate the effect of shape by considering ellipsoidal inclusions. We also propose an easily manufacturable microstructure that increases the ionic conductivity of the composite electrolyte by 40 times, simply by the addition of dielectric columns parallel to the solid electrolyte phase.

Amorphisation-induced electrochemical stability of solid-electrolytes in Li-metal batteries: The case of Li3ClO

Energy storage technologies that can meet the unprecedented demands of a sustainable energy system based on intermittent energy sources require new battery materials. In recent years, new superionic conducting glasses have been discovered that have captured the attention of the community due to their potential use as solid electrolytes for all-solid-state Li-ion batteries. New research is needed to understand the correlations between the non-crystalline structure of glasses and their advanced properties. Here we investigate the structural properties, the electronic structure and the electrochemical stability against Li metal of the high ionic conducting Li 3 ClO glass. We use the stochastic quenching method based on first principles theory to model the amorphous structure of the glass. We characterise the structure by means of radial distribution functions, angle distributions functions, bond lengths and coordination numbers. Our calculations of the electronic structure of Li 3 ClO for both phases, crystalline and amorphous, demonstrate that both materials are good insulators. We assess the electrochemical stability of the electrolyte against Li metal electrode and in particular we analyse the role of amorphisation. Our results show that crystalline Li 3 ClO is not stable against Li metal electrode and that the glass can be made stable if less oxygen is supplied, for instance, by producing an substoichiometric glass. • New superionic Li 3 ClO-based glasses are potential electrolytes for Li-ion batteries. • We assess electrochemical stability of Li 3 ClO (crystal and glass) against Li metal. • Our results show that crystal Li 3 ClO is not stable against Li metal electrode. • On the other hand glass Li 3 ClO can be made stable if less oxygen is supplied. • This work advances the current understanding of glasses for solid state ionics.

Ethylene Carbonate Adsorption and Decomposition on Pristine and Defective ZnO(101̅0) Surfaces: A First-Principles Study

Fundamental understanding of the reactivity between coating material of Li-ion battery cathode and electrolyte is important in order to obtain suitable coating candidates. Herein, we study ethylene carbonate (EC) adsorption and decomposition reactions on pristine, O vacancy- and Zn vacancy-defected ZnO (10-10) by means of first-principles density functional theory (DFT) calculations. Possible decomposition pathways via H-abstraction and EC ring-opening reaction that leads to the generation of CO2 and C2H4 gases are studied from the thermodynamic and kinetic aspects. Firstly, we find that molecular EC preferably adsorbs on both pristine and defective ZnO (1010) via the bonding between its carbonyl oxygen (OC) and surface Zn. Secondly, subsequent decomposition reactions show large tendency of EC to decompose on both pristine and defective ZnO (10-10). This tendency is indicated by the large thermodynamic driving forces to decompose EC that range from -1.5 eV to -2.5 eV on both pristine and defective ZnO (10-10) (calculated with respect to EC gas phase). The large tendency of EC to decompose, however, is hindered by the high activation barriers of the EC decomposition, shown by the lowest activation barrier of 0.96 eV on Zn vacancy defected ZnO (10-10). Our results thus indicate that EC decomposition on ZnO (10-10) is mainly hindered due to its slow rate of decomposition instead of the thermodynamic factors.

Physical properties and compatibility with graphite and lithium metal anodes of non-flammable deep eutectic solvent as a safe electrolyte for high temperature Li-ion batteries

In this study we present the original formulation of a deep eutectic mixture based on lithium imide salt as an electrolyte for Li-ion batteries. The non-flammable liquid mixture obtained by mixing asymmetric lithium (fluorosulfonyl) (trifluoromethanesulfonyl) imide (LiFTFSI) with ethylene carbonate (EC) demonstrates its applicability as a safer electrolyte for Li-ion batteries. By comparison with conventional electrolytes containing the same salt, in 3EC/7EMC and EC/PC/3DMC, the volumetric properties of (EC-LiTFSI, 3/1, w), abbreviated EC-LiTFSI31, reveal the strong nature of the FTFSI−—EC coordination and the non-solvation of Li+, explaining the "stacking" effect observed. Transport properties (viscosity, conductivity and ionicity) are discussed and compared to those of conventional electrolytes, demonstrating that eutectic EC-LiTFSI31 has the typical ionicity of organized media such as ionic liquids or DESs, even if its concentration in salt is similar to that of the conventional electrolyte of 1 mol L−1.The electrochemical evaluation of the compatibility of this original electrolyte with lithium metal and with graphite in Li//Li and Gr//Li half-cells shows that EC-LiTFSI31 does not cause any erratic or asymmetric polarization over time in lithium metal and that it demonstrates very good intercalation and stability during the charge/discharge of graphite. The thermal and electrochemical stability of EC-LiTFSI31 gives a good performance and an outstanding stability of Gr//Li cell cycling at C/20 or C/10 up to 80 °C, during 5 months (100 cycles) without any damage to the battery. This original formulation could prove to be a promising electrolyte for Li-ion battery safety, which remains the main concern of industrialists in the field.

A two-mechanism and multiscale compatible approach for solid state electrolytes of (Li-ion) batteries

All-solid-state batteries are claimed to be the next-generation battery system, in view of their safety accompanied by high energy densities. A new advanced, multiscale compatible, and fully three-dimensional model for solid electrolytes is presented in this note. The response of the electrolyte is profoundly studied theoretically and numerically, analyzing the equilibrium and steady-state behaviors, the limiting factors, as well as the most relevant constitutive parameters according to the sensitivity analysis of the model, the novel model is finally validated in accordance with experimental results.

Introducing the potency of new boron-based heterocyclic anion receptor additives to regulate the solvation and transport properties of Li-ions in ethylene carbonate electrolyte of Li-Ion battery: An atomistic molecular dynamics study

Development of new solvent/additive electrolyte is emerging field of research towards the improvement of ion transport and solid-electrolyte-interface formation in Li-ion battery (LIB). We perform extensive atomistic molecular dynamics simulations with LiPF6 in ethylene carbonate (EC) in presence of a new class of boron (B) based heterocyclic anion receptor additives; C2HBNO(NO2)2, and C2HBNS(NO2)2 and their trimers B[C2HBNO(NO2)2]3, and B[C2HBNS(NO2)2]3 to investigate the efficacy of this class of additives in regulating the solvation and transport properties of Li+ ions as compared to the reference LiPF6/EC solution that contained TPFPB, a commonly used B-based additive. Our designed additives in several aspects show their efficacy. Among all, C2HBNS(NO2)2 is found to be the most efficient PF6- trapper that reduces ion pair formation. It promotes diffusion of Li+ and EC, improves the transference number, and reduces viscosity of solution, as compared to TPFPB. Further, it improves the ionic conductivity and drift velocity under a wide range of temperatures and external electric fields, respectively. Some of the computed properties are in agreement with the available experimental results. Our study would facilitate the design and synthesis of this class of additives to open up new possibilities of accelerating the LIB power sources for portable appliances.

Dopant effect on Li+ ion transport in NASICON-type solid electrolyte: Insights from molecular dynamics simulations and experiments

The performance of sodium superionic conductor (NASICON)-type LiZr2(PO4)3 (LZP) solid electrolytes for Li-ion batteries is dependent on their ion transportation properties. Therefore, to achieve high stability, ionic conductivity, and good compatibility with Li, the LZP solid electrolyte has chosen and doped with Al to improve aforesaid properties. Also, the effect of the dopant on various parameters has been investigated via MD simulations and experimentally. In this study, molecular dynamics (MD) simulations were used to investigate the effect of Al doping on the ion transport properties of Li1+xAlxZr2−x(PO4)3 (LAZP, x = 0.0–1.0) solid electrolytes. A facile solid-state reaction was used to synthesize both pristine and Al-doped solid electrolytes and to estimate the effect of doping on the ionic conductivity and ion diffusion in LZP. Computational and experimental results provided strong evidence of improved ion conductivity and diffusion in LZP owing to the presence of the Al dopant. Furthermore, the computational results agreed well with the experimental results, thereby validating the computational model. A maximum ionic conductivity of σLi = 2.77 × 10−5 S cm −1 (for x = 0.2) was obtained. Enhanced ionic conductivity was observed with Al dopants owing to the creation of interstitial Li ions through a reduction in grain boundary resistance. However, a further increase in the amount of dopant reduced the ionic conductivity of LZP owing to Li-ion trapping at the most stable and metastable sites around the Al insertions. Doped LZP solid electrolytes are suitable for use in energy storage devices because of their enhanced ionic conductivity compared to that of pristine LZP.

Functionalized nona-silicide [Si9R3] Zintl clusters: a new class of superhalogens.

Superatoms, due to their various applications in redox and materials chemistry, have been a major topic of study in cluster science. Superhalogens constitute a special class of superatoms that mimic the chemistry of halogens and serve as building blocks of novel materials such as super and hyper salts, perovskite-based solar cells, solid-state electrolytes, and ferroelectric materials. These applications have led to a constant search for new class of superhalogens. In this study, using density functional theory, we show that recently synthesized [Si9{Si (tBu)2H}3] and [Si9{Si (TMS)3}3] Zintl clusters not only behave like halogens but also when functionalized with suitable ligands exhibit superhalogen characteristics. Frontier molecular orbital (FMO) analyses give insights into the electron-accepting nature of the Zintl clusters. Additional bonding techniques such as energy density at the bond critical point (BCP) and adaptive natural density partitioning (AdNDP) gives complementary information about the nature of bonding in Si9-based Zintl clusters. The potential of these Zintl clusters in the synthesis of new electrolytes in Li-ion batteries is also investigated.