Infrared Absorption Research Articles

Operando analysis reveals potential-driven in situ formation of single-Fe-atom electrocatalysts for green production of ammonia

As a sustainable approach for N2 fixation, electrocatalytic N2 reduction reaction (N2RR) to produce ammonia (NH3) is highly desirable with a precise understanding to the structure-activity relationship of electrocatalysts. Here, firstly, we obtain a novel carbon-supported oxygen-coordinated single-Fe-atom catalyst for highly efficient production of ammonia from electrocatalytic N2RR. Based on such new type of N2RR electrocatalyst, by combining operando X-ray absorption spectra (XAS) with density function theory calculation, we reveal significantly that the as-prepared active coordination structure undergoes a potential-driven two-step restructuring, firstly from FeSAO4(OH)1a to FeSAO4(OH)1a'(OH)1b with the adsorption of another -OH on FeSA at open-circuit potential (OCP) of 0.58 VRHE, and subsequently restructuring from FeSAO4(OH)1a'(OH)1b to FeSAO3(OH)1a″ due to the breaking of one Fe-O bond and the dissociation of one -OH at working potentials for final electrocatalytic process of N2RR, thus revealing the first potential-induced insitu formation of the real electrocatalytic active sites to boost the conversion of N2 to NH3. Moreover, the key intermediate of Fe-NNHx was detected experimentally by both operando XAS and insitu attenuated total reflection-surface-enhanced infrared absorption spectra (ATR-SEIRAS), indicating the alternating mechanism followed by N2RR on such catalyst. The results indicate the necessity of considering the potential-induced restructuring of the active sites on all kinds of electrocatalysts for such as highly efficient ammonia production from N2RR. It also paves a new way for a precise understanding to the structure-activity relationship of a catalyst and helps the design of highly efficient catalysts.

Tailoring the Interfacial Water Structure by Electrolyte Engineering for Selective Electrocatalytic Reduction of Carbon Dioxide

Engineering aqueous electrolytes with low amounts of additives to achieve a tunable CO2 reduction product is an underexplored territory in electrocatalysis. Here, we show the enhancement of the Faradaic efficiency (FE) of CO2 reduction to CO on unmodified polycrystalline gold from ∼67 to ∼94% by the addition of up to 15 mol % of N,N-dimethylformamide (DMF) to an aqueous electrolyte. The role of electrolyte structure modification near the electrode–electrolyte interface was studied using in situ surface-enhanced infrared absorption spectroscopy in attenuated total reflection mode (ATR-SEIRAS). In addition to the expected detection of the adsorbed CO (COad) intermediate present on the Au surface, in both the linearly bonded and bridge-bonded forms, we observed changes in the structure of interfacial water induced by the addition of DMF. The changes in the water stretching band and the DMF carbonyl band indicate an increase in the strongly hydrogen-bonded DMF–water pairs with increasingly negative potential near the interface in the presence of DMF. We hold this interfacial water structure modification by DMF responsible for increasing the CO2RR FE and decreasing the competing hydrogen evolution reaction (HER). Furthermore, the suppression of the HER is observed in other electrolytes and also when platinum was used as an electrode and hence can be a potential method for increasing the product selectivity of complex electrocatalytic reactions.

Decoupling absorption and radiative cooling in mid-wave infrared bolometric elements.

We present a spectrally selective, passively cooled mid-wave infrared bolometric absorber engineered to spatially and spectrally decouple infrared absorption and thermal emission. The structure leverages an antenna-coupled metal-insulator-metal resonance for mid-wave infrared normal incidence photon absorption and a long-wave infrared optical phonon absorption feature, aligned closer to peak room temperature thermal emission. The phonon-mediated resonant absorption enables a strong long-wave infrared thermal emission feature limited to grazing angles, leaving the mid-wave infrared absorption feature undisturbed. The two independently controlled absorption/emission phenomena demonstrate decoupling of the photon detection mechanism from radiative cooling and offer a new design approach enabling ultra-thin, passively cooled mid-wave infrared bolometers.

N to P-type transition with narrowing optical bandgap and increasing carrier concentration of spin coated Cu doped ZnS thin films for optoelectronic applications

To accomplish the demand of optimized n-type buffer layer in photovoltaic cells; we have studied and analysed various doping compositions of Copper (Cu) into Zinc Sulfide (ZnS) thin films. A series of Cu doped ZnS thin films are fabricated on glass substrate by using spin coating technique at optimized parameters. X-Ray diffraction (XRD) technique revealed that Cu doped ZnS thin films have single phase wurtzite (hexagonal) structure up to 4% doped samples. However, XRD spectra of 6% Cu doped thin films depicted an extra peak of CuS phase that confirmed the secondary phases are formed due to inadequate incorporation of Cu in ZnS structure. Scanning electron microscope (SEM) images showed that the fabricated thin films are compact, dense and homogeneous without voids and cracks on the surface. Energy dispersive X-ray (EDX) analysis indicated that stoichiometric ratio of Zinc to Sulfur is maintained except for 6% Cu doped concentration. Fourier transform infra-red (FTIR) absorption spectrum of thin films series confirmed the presence of ZnS vibrational bonds along with vibrational and stretching bonds of carbon, oxygen and hydrogen at appropriate positions. Cu doped thin films from 0% to 4% exhibited n-type character, while 6% Cu doped ZnS sample unveiled p-type nature may be due to CuS secondary phase's formation. UV–Vis optical spectroscopy revealed that the energy band gap also decreased from 3.64 eV to 3.24 eV with varying Cu concentration from 0% to 6% doped ZnS thin films. The energy band gap of Cu doped ZnS is decreased may be due to the existence of Cu-3d state in the upper part of the valence band.

A viscosity-sensitivity probe for cross-platform multimodal imaging from mitochondria to animal

Viscosity in biological systems is a critical factor for various physiological process, including signal transduction and metabolisms of substance and energy. Abnormal viscosity has been proven as a key feature of many diseases, thereby real-time monitoring of viscosities in cells and in vivo is of great significance for the diagnosis and therapy of related diseases. Up to date, it is still challenging to monitor viscosity cross-platform from organelles to cells to animals with a single probe. Here, we report a benzothiazolium-xanthene probe with rotatable bonds that switch on the optical signals in high viscosity environment. The enhancements of absorption, fluorescence intensity and lifetime signals allow to dynamically monitoring the viscosity change in mitochondria and cells, while near infrared absorption and emission facilitate imaging the viscosity with both fluorescence and photoacoustic imaging in animals. The cross-platform strategy is capable of monitoring the microenvironment with multifunctional imaging across various levels.

Infrared analysis in the aqueous humor of patients with uveitis: Preliminary results

Inflammatory processes affecting the uvea result in a temporary o permanent blurred vision and represent an important cause of visual impairment worldwide. It is often hard to make a precise diagnosis which is dependent on the clinical expertise, diagnostic tests, laboratory investigations in blood and sometimes in the aqueous humor (AH). With the aim of obtaining proof of principle Fourier Transformed Infrared (FT-IR) absorbance spectroscopy was applied to study the molecular composition of 72 AH samples collected in 26 patients with uveitis and in 44 controls. The unsupervised exploration of the internal structure of the dataset by principal component analysis reduced hundreds IR variables to those most representative allowing to obtain the predictive model that distinguished the AH spectra of patients with uveitis from controls. The same result was obtained by unsupervised agglomerative cluster analysis. After labeling the spectra with some clinical information it was observed that most severe uveitis with active processes were grouped separately from chronic and relapsing uveitis and controls. The consistence of prediction models is discussed in the light of supporting etiological diagnosis by machine learning processes. In conclusion, proof of principle has been obtained that the IR spectral pattern of AH may reflect particular uveal diseases.

Recent progress of photodetector based on carbon nanotube film and application in optoelectronic integration

Due to its remarkable electrical and optical capabilities, optoelectronic devices based on the semiconducting single-walled carbon nanotube (s-SWCNT) have been studied extensively in the last two decades. First, s-SWCNT is a direct bandgap semiconductor with a high infrared absorption coefficient and high electron/hole mobility. In addition, as a typical one-dimensional material, there is no lattice mismatch between s-SWCNT and any substrates. Another advantage is that the optoelectronic devices of s-SWCNT can be processed at low temperatures. S-SWCNT has intriguing potential and applications in solar cells, light-emitting diodes (LEDs), photodetectors, and three-dimensional (3D) optoelectronic integration. In recent years, along with the advancement of solution purification technology, the high-purity s-SWCNTs film has laid the foundation for constructing large-area, homogenous, and high-performance optoelectronic devices. In this review, optoelectronic devices based on s-SWCNTs film and related topics are reviewed, including the preparation of high purity s-SWCNTs film, the progress of photodetectors based on the s-SWCNTs film, and challenges of s-SWCNTs film photodetectors.

Reaction-induced iodine adsorption on Cu surfaces facilitates electrocatalytic CO2 reduction.

The electrolyte effect has been key to the electrochemical CO2 reduction reaction (CO2RR) and has received extensive attention in recent years. Here we combined atomic force microscopy, quasi-in situ X-ray photoelectron spectroscopy, and in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) to study the effect of iodine anions on Cu-catalyzed CO2RR in the absence or presence of KI in the KHCO3 solution. Our results suggested that iodine adsorption caused coarsening of the Cu surface and altered its intrinsic activity for CO2RR. As the potential of the Cu catalyst became more negative, there was an increase in surface iodine anion concentration ([I-]), which could be connected to the reaction-enhanced adsorption of I- ions accompanying the increase in CO2RR activity. A linear relationship was observed between [I-] and current density. SEIRAS results further suggested that the presence of KI in the electrolyte strengthened the Cu-CO bond and facilitated the hydrogenation process, enhancing the production of CH4. Our results have thus provided insight into the role of halogen anions and aided in the design of an efficient CO2RR process.

Nitrogen cold plasma treatment stabilizes Cu0/Cu+ electrocatalysts to enhance CO2 to C2 conversion

Cu-based materials are ideal catalysts for CO2 electrocatalytic reduction reaction (CO2RR) into multi-carbon products. However, such reactions require stringent conditions on local environments of catalyst surfaces, which currently are the global pressing challenges. Here, a stabilized activation of Cu0/Cu+-on-Ag interface by N2 cold plasma treatment was developed for improving Faradaic efficiency (FE) of CO2RR into C2 products. The resultant Ag@Cu-CuNx exhibits a C2 FE of 72% with a partial current density of −14.9 mA cm−2 at −1.0 V vs. RHE (reversible hydrogen electrode). Combining density functional theory (DFT) and experimental investigations, we unveiled that Cu0/Cu+ species can be controllably tuned by the incorporation of nitrogen to form CuNx on Ag surface, i.e., Ag@Cu-CuNx. This strategy enhances *CO intermediates generation and accelerates C–C coupling both thermodynamically and kinetically. The intermediates O*C*CO, *COOH, and *CO were detected by in-situ attenuated total internal reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS). The uncovered CO2RR-into-C2 products were carried out along CO2→ *COOH → *CO → O*C*CO → *C2H3O → *C2H4O → C2H5OH (or *C2H3O → *O + C2H4) paths over Ag@Cu-CuNx electrocatalyst. This work provides a new approach to design Cu-based electrocatalysts with high-efficiency, mild condition, and stable CO2RR to C2 products.

Long-wave infrared transparent sulfur polymers enabled by symmetric thiol cross-linker

Infrared (IR) transmissive polymeric materials for optical elements require a balance between their optical properties, including refractive index (n) and IR transparency, and thermal properties such as glass transition temperature (Tg). Achieving both a high refractive index (n) and IR transparency in polymer materials is a very difficult challenge. In particular, there are significant complexities and considerations to obtaining organic materials that transmit in the long-wave infrared (LWIR) region, because of high optical losses due to the IR absorption of the organic molecules. Our differentiated strategy to extend the frontiers of LWIR transparency is to reduce the IR absorption of the organic moieties. The proposed approach synthesized a sulfur copolymer via the inverse vulcanization of 1,3,5-benzenetrithiol (BTT), which has a relatively simple IR absorption because of its symmetric structure, and elemental sulfur, which is mostly IR inactive. This strategy resulted in approximately 1 mm thick windows with an ultrahigh refractive index (nav > 1.9) and high mid−wave infrared (MWIR) and LWIR transmission, without any significant decline in thermal properties. Furthermore, we demonstrated that our IR transmissive material was sufficiently competitive with widely used optical inorganic and polymeric materials.

Electro-optic symmetry breaking of BIC modes for tunable infrared emissivity

We present an electro-optic pathway to break symmetry to enable dynamic light-matter interaction in guided-mode resonance grating. Breaking of mirror symmetry allows accessing bounds states in the continuum (BIC) that are otherwise inaccessible. We design an electrically tunable GaAs-based guided-mode resonance grating that exhibits infrared absorption peaks in the longwave IR. The grating consists of GaAs dielectric sandwiched between the top gold contacts and the bottom gold reflector. We analyze the dependence of Q-factors on the choice of the design. We show that by careful design of the structure, a substantial radiative coupling can be obtained with broken symmetry. Our simulations predict that due to the electro-optic properties of GaAs, the application of a voltage across the dielectric allows a change in the refractive index to break the symmetry of the structure and turns the emission peak ON. Reversible refractive index tuning restores symmetry and turns the emission OFF. The concept presents a novel route toward tunable directional absorption and emission.

Circumventing CO2 Reduction Scaling Relations Over the Heteronuclear Diatomic Catalytic Pair.

In the electrochemical CO2 reduction reaction (CO2RR), CO2 activation is always the first step, followed by the subsequent hydrogenation. The catalytic performance of CO2RR is intrinsically restricted by the competition between molecular CO2 activation and CO2 reduction product release. Here, we design a heteronuclear Fe1-Mo1 dual-metal catalytic pair on ordered porous carbon that features a high catalytic performance for driving electrochemical CO2 reduction to CO. Combining real-time near-ambient pressure X-ray photoelectron spectroscopy, operando 57Fe Mössbauer spectroscopy, and in situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy measurements with density functional theory calculations, chemical adsorption of CO2 is observed on the Fe1-Mo1 catalytic pair through a bridge configuration, which prompts the bending of the CO2 molecule for CO2 activation and then facilitates the subsequent hydrogeneration reaction. More importantly, the dynamic adsorption configuration transition from the bridge configuration of CO2 on Fe1-Mo1 to the linear configuration of CO on the Fe1 center results in breaking the scaling relationship in CO2RR, simultaneously promoting the CO2 activation and the CO release.

Atmospheric oxidation of unsaturated hydrofluoroethers initiated by OH radicals

Hydrofluoroethers (HFEs) are perfluorinated chemicals that were developed as alternative for chlorofluorocarbons (CFCs) in various applications. Among notable unsaturated HFEs are perfluoro methyl vinyl ether (PMVE, CF3OCFCF2) and perfluoro ethyl vinyl ether (PEVE, C2F5OCF = CF2). During the implementation of PMVE and PEVE, they spill and release to the atmosphere. Due to the tendency of perfluorinated compounds to have strong infrared absorption features and long atmospheric lifetimes, they are among the most potent greenhouse gases. Thus, it is important to accurately assess their atmospheric sink routes in order to assess their impact on climate change. Herein, we illustrated detailed mechanistic pathways and developed kinetic models with the underlying aim to comprehend the atmospheric fate of the title HFEs and the likely products of decomposition. It was found that the production of main products to stem from the addition of OH radical to the inner carbon-carbon double bond atoms. Atmospheric lifetimes of PMVE and PEVE were calculated to be ∼23 and ∼56 h; respectively. Time-dependent molar yields are acquired for the experimentally major products; namely carbonyl fluoride (CF2O), perfluorinated glyoxal (CFOCFO), perfluorinated methylformates (CF3OCFO and CF3CF2OCFO). Photochemical Ozone Creation Potentials (POCPs) of PMVE and PEVE were calculated to be 1.78 and 1.18, respectively. Obtained results tap into efforts that aim to understand the atmospheric chemistry cycles of perfluorinated chemicals in general.

Intermolecular ═C–H···O═C Hydrogen Bonding and Conformational Preference in Crystalline Poly(butylene 2,5-furandicarboxylate)

Besides maximizing packing efficiency, molecular interactions also play an indispensable role upon conformational ordering for crystallization of long-chain polymers. Herein, structural evolution upon heating of biobased poly(butylene 2,5-furandicarboxylate) (PBF) is followed by temperature-dependent infrared (IR) spectroscopy and wide-angle X-ray diffraction (WAXD) to elucidate the molecular interactions and conformational preference in its crystalline state. By estimating the group distances according to atomic coordinates of its crystal structure, the stronger intermolecular interaction than the van der Waals force is speculated to exist in crystalline PBF, which is fully confirmed by the changes of IR absorptions associated with ═C–H and C═O groups upon heating as an abnormal ═C–H···O═C hydrogen bonding. The combination of temperature-dependent ═C–H band position and crystal lattice expanding supports a good thermostability of this interaction up to melting, fully defining its nature as strong hydrogen bonding rather than the generally reported weak H···O═C bonding in biodegradable polyesters. By further analyzing the confirmational ordering in its crystalline state, it is believed that such intermolecular ═C–H···O═C hydrogen bonding stabilizes the energetically inaccessible syn–syn conformer of 2,5-furandicarboxylic moieties for PBF crystallization.

Constructing Nanocaged Enzymes for Synergistic Catalysis of CO2 Reduction.

Promoting the activity of biological enzymes under in vitro environment is a promising technique for bioelectrocatalytic reactions, such as the conversion of carbon dioxide (CO2 ) into valuable chemicals, which is a promising strategy to address the environmental issue of CO2 in the atmosphere; however, this technique remains challenging. Herein, a nanocage structure for enzyme confinement is synthesized to enable the in situ encapsulation of formate dehydrogenase (FDH) in a porous metal-organic framework, which acts as a coenzyme and boosts the hybrid synergistic catalysis using enzymes. This study reveals that the synthesized FDH@ZIF-8 nanocage-structured hybrid (CSH) catalyst exhibits an improved catalytic ability of the enzymes and increases the hydrophobicity of the electrode and its affinity to CO2 . Thus, CSH can trap CO2 and control its microenvironments. The CSH catalyst boosts the conversion rate of CO2 to formic acid (HCOOH) to 28 times higher than that when using pure FDH. The in situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) spectra indicates that OCHO* is the key intermediate. Density functional theory (DFT) calculations show that CSH has extremely low overpotential and is particularly effective for producing formate. This protection architecture for enzymes considerably promotes their biological application under in vitro environments.

Promoting electrocatalytic CO2 reduction via anchoring quaternary piperidinium cations onto copper electrode

Cation identity in the electrolyte is known to have a critical influence on electrocatalytic CO2 reduction reaction (CO2RR). However, the impact of cation aggregation state at the electrode/electrolyte interface, particularly for organic cations, remains unclear for CO2RR. In this study, we investigated the effect of the organic cation aggregation state, by examining the CO2RR behaviors over a copper (Cu) electrode, before and after the surface modification of a polyelectrolyte (i.e., quaternary ammonia poly (N-methyl-piperidine-co-p-terphenyl) with grafted piperidinium cations), in an aqueous electrolyte with free-moving piperidinium (Pip+) cations. Immobilizing the Pip+ cations on Cu surface was found to effectively promote the CO2RR selectivity. The underlying cause was further explored by in-situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy and electrochemical double-layer capacitance measurements, illustrating that the enhanced CO2RR performance was due to the change in electrode/electrolyte interface properties. These findings would contribute to further optimization of the electrode/electrolyte interface for efficient CO2RR.

Hyphenated DEMS and ATR-SEIRAS techniques for in situ multidimensional analysis of lithium-ion batteries and beyond.

A wide spectrum of state-of-the-art characterization techniques have been devised to monitor the electrode-electrolyte interface that dictates the performance of electrochemical devices. However, coupling multiple characterization techniques to realize in situ multidimensional analysis of electrochemical interfaces remains a challenge. Herein, we presented a hyphenated differential electrochemical mass spectrometry and attenuated total reflection surface enhanced infrared absorption spectroscopy analytical method via a specially designed electrochemical cell that enables a simultaneous detection of deposited and volatile interface species under electrochemical reaction conditions, especially suitable for non-aqueous, electrolyte-based energy devices. As a proof of concept, we demonstrated the capability of the homemade setup and obtained the valuable reaction mechanisms, by taking the tantalizing reactions in non-aqueous lithium-ion batteries (i.e., oxidation and reduction processes of carbonate-based electrolytes on Li1+xNi0.8Mn0.1Co0.1O2 and graphite surfaces) and lithium-oxygen batteries (i.e., reversibility of the oxygen reaction) as model reactions. Overall, we believe that the coupled and complementary techniques reported here will provide important insights into the interfacial electrochemistry of energy storage materials (i.e., in situ, multi-dimensional information in one single experiment) and generate much interest in the electrochemistry community and beyond.

Development of a flat conical chamber-based non-dispersive infrared CO2 gas sensor with temperature compensation.

In order to accurately monitor CO2 concentration based on the non-dispersive infrared technique, a novel flat conical chamber CO2 gas sensor is proposed and investigated by simulation analysis and experimental verification. First, the optical design software and computational fluid dynamics method are utilized to theoretically investigate the relationship between the energy distribution, absorption efficiency of infrared radiation, and chamber size. The simulation results show that the chamber length has an optimal value of 8cm when the cone angle is 5° and the diameter of the detection surface is 1cm, which makes infrared absorption efficiency optimal. Then, the flat conical chamber CO2 gas sensor system is developed, calibrated, and tested. The experimental results indicate that the sensor can accurately detect CO2 gas concentrations in the range of 0-2000 ppm at 25 °C. It is found that the absolute error of calibration is within 10 ppm, and the maximum repeatability and stability errors are 5.5 and 3.5%, respectively. Finally, the genetic neural network algorithm is presented to compensate for the output concentration of the sensor to solve the problem of temperature drift. Experimental results demonstrate that the relative error of the compensated CO2 concentration is varied from -0.85 to 2.32%, which is significantly reduced. The study has reference significance for the structural optimization of the infrared CO2 gas sensor and the improvement of the measurement accuracy.

Development of Mid-Infrared Absorption Spectroscopy for Gemstone Analysis

Absorption spectroscopy has been widely used in gemstone societies as it enables the identification of the origin and post-treatment of gemstones in a non-destructive way. The infrared (IR) range is critical for studies of gemstones such as corundum, emerald, and diamond. Regarding the corundum sample, absorption peaks related to the -OH bond could be used as an index for heat-treatment detection, and different types of inclusions could be identified by analyzing the IR absorption spectrum. The most widely used method for measuring IR absorptions is Fourier-transform infrared spectroscopy (FTIR), which was designed based on the working of the Michelson interferometer. However, FTIR has a few limitations, such as a long measurement time and difficulty in sample placement, which limits its full automation capability. In this study, a mid-infrared (MIR) spectrometer relying on the upconversion phenomenon of non-linear crystals was used to measure the absorption spectra. Corundum with heat treatment features and/or with different common types of inclusions were measured by both transmission and reflection modes. After comparison with the FTIR spectra captured on the same sample set, the same target peaks could be captured with a shorter measurement time and easier operation. The developed MIR spectrometer could directly measure the absorption spectrum in the 2–4.5 µm (2200–5000 cm−1) range within a few seconds. Meanwhile, as both transmission and reflection modes were available, both loose and mounted gemstones could be measured, supporting the widespread use of this device in large-scale production and its ability to achieve full automation.

Anion-Induced Interfacial Liquid Layers on LiCoO2 in Salt-in-Water Lithium-Ion Batteries.

The incompatibility of lithium intercalation electrodes with water has impeded the development of aqueous Li-ion batteries. The key challenge is protons which are generated by water dissociation and deform the electrode structures through intercalation. Distinct from previous approaches utilizing large amounts of electrolyte salts or artificial solid-protective films, we developed liquid-phase protective layers on LiCoO2 (LCO) using a moderate concentration of 0.5∼3 mol kg-1 lithium sulfate. Sulfate ion strengthened the hydrogen-bond network and easily formed ion pairs with Li+, showing strong kosmotropic and hard base characteristics. Our quantum mechanics/molecular mechanics (QM/MM) simulations revealed that sulfate ion paired with Li+ helped stabilize the LCO surface and reduced the density of free water in the interface region below the point of zero charge (PZC) potential. In addition, in situ electrochemical surface-enhanced infrared absorption spectroscopy (SEIRAS) proved the appearance of inner-sphere sulfate complexes above the PZC potential, serving as the protective layers of LCO. The role of anions in stabilizing LCO was correlated with kosmotropic strength (sulfate > nitrate > perchlorate > bistriflimide (TFSI-)) and explained better galvanostatic cyclability in LCO cells.