Field Desorption Mass Spectrometry Research Articles

A Mixed Aryl/Amide Complex of Iron(II)

The combined incorporation of a labile and a stabilizing ligand in a metal‐organic precursor is of interest for the synthesis of low valent ligated (hetero)metallic clusters. The heteroleptic aryl/amide iron (II) complex [Fe2(Mes)2(BTSA)2] (1) was synthesized by equimolar mixing of [Fe2(Mes)4] with [Fe2(BTSA)4]. (VT)‐NMR‐, UV‐Vis‐ and SC‐XRD‐analysis combined with DFT calculations revealed a dimeric structure with terminal bis(trimethylsilyl)amide‐ and bridging mesityl‐ligands in solution and as well in the solid phase. The treatment of [Fe2(BTSA)4] with the carbenoid group 13 metallo‐ligand GaCp* is known to yield simply adducts. In contrast, monitoring the reactions of [Fe2(Mes)4] and [Fe2(Mes)2(BTSA)2] (1) with GaCp* by liquid injection field desorption mass spectrometry (LIFDI‐MS) suggest formation of a broader variety of bimetallic Fe‐Ga‐species with iron formally reduced to iron (I) or iron (0). However, the product distribution obtained using the heteroleptic compound 1 indicates combined reactivity of the homoleptic congeners by showing larger species with variations of Fe/Ga ratios towards the formation of Fe/Ga clusters. This blended behavior is assigned to the more labile mesityl ligand and the more stabilizing BTSA‐ligand.

Robust and versatile assembly for emitter positioning, observation, and heating in atmospheric pressure field desorption mass spectrometry.

Atmospheric pressure field desorption (APFD) mass spectrometry (MS) has recently been introduced as a new variant of field desorption (FD) mass spectrometry. The development aimed at providing the basic characteristics of FD-MS in combination with instruments equipped with an atmospheric pressure (AP) interface. Hitherto, APFD has been demonstrated to yield both positive and negative even electron ions of highly polar or ionic compounds as well as to enable the generation of positive molecular ions, M+•, of polycyclic aromatic compounds. The prototype setup for APFD was based on a nano-electrospray ionization (nanoESI) source slightly modified to allow for emitter positioning in front of the AP interface of a Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer. The entrance electrode of the interface was set to negative or positive high voltage with respect to the emitter at ground potential, thereby permitting the formation of positive or negative ions, respectively. This work describes a custom-built device for quicker and more reproducible sample loading on and positioning of field emitters at the entrance electrode of the atmospheric pressure interface of a mass spectrometer. In addition, the device provides means for observation of the emitter during operation and for resistive emitter heating as employed in traditional FD-MS. Emitter heating both speeds up the desorption of the analytes and allows for the desorption/ionization of analytes of higher molecular weight than without emitter heating. In some cases, the signal-to-noise ratio of APFD mass spectra is improved due to higher ion currents effected by compressing the entire process into shorter periods of spectral acquisition. The new setup enables robust and reliable operation in APFD-MS. Moreover, it has been designed as to allow for use on a range of instruments as it can either be used on an FT-ICR mass spectrometer or in combination with a trapped ion mobility-quadrupole-time-of-flight (TIMS-Q-TOF) instrument.

Application of atmospheric pressure field desorption for the analysis of anionic surfactants in commercial detergents

Recent work has shown that field desorption (FD) and field ionization (FI) using activated field emitters may be performed at atmospheric pressure, too. While some limitations apply to atmospheric pressure field desorption (APFD) mass spectrometry (MS), the method can deliver both positive and negative even electron ions of highly polar or ionic compounds. Furthermore, APFD even permits the generation of positive molecular ions of polycyclic aromatic compounds. Here, an application of negative-ion APFD for the analysis of anionic surfactants contained in commercial detergent products for body care, household, and technical uses is presented. The samples include liquid soaps and shower gels, dishwashing liquids, and cooling lubricants. Surfactant solutions in methanol/water or pure methanol at 2–10 µl ml−1 were deposited on commercial 13-µm activated tungsten emitters. The emitters were positioned in front of the atmospheric pressure interface of a Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer by means of a slightly modified nano-electrospray ionization (nanoESI) source. The entrance electrode of the interface was set to positive high voltage with respect to the emitter at ground potential. Under these conditions, negative-ion desorption was achieved. The surfactant anions, organic sulfates and organic sulfonates, were characterized by accurate mass-based formula assignments, and in part, by tandem mass spectrometry. The negative-ion APFD spectra were compared to results by negative-ion electrospray ionization (ESI) either obtained using the FT-ICR mass spectrometer or by using a trapped ion mobility-quadrupole-time-of-flight (TIMS-Q-TOF) instrument when product ions of low m/z needed to be detected in tandem MS.Graphical

Molecular ion formation on activated field emitters in atmospheric pressure field desorption mass spectrometry

Atmospheric pressure field desorption (APFD) mass spectrometry (MS) has recently been explored as a new contribution to the field of ambient desorption/ionization (ADI). Depending on the selected polarity applied to the field emitter, ionic and polar analytes were demonstrated to deliver positive as well as negative ions. Whereas this recent study solely reported on the formation of even-electron ions of either polarity, the present work on APFD-MS demonstrates the abundant formation of positive molecular ions, M+•, from polycyclic aromatic compounds. Molecular ions were formed on and desorbed from standard 13-µm activated tungsten wire emitters at atmospheric pressure. The commercial field emitters were positioned at about 2 mm distance in front of the atmospheric pressure interface of a Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer and the entrance electrode of the interface was set to –4.5 to –5.5 kV with respect to the emitter. Emitter-disrupting electric discharges did normally not occur under these conditions. The electric field strengths achieved at the dendritic microneedles were sufficient to allow for the abundant formation of M+• ions of various polycyclic aromatic compounds such as benzo[a]pyrene, anthracene, fluoranthene, 1,1,4,4-tetraphenyl-butadiene, and 1-aza-[6]helicene. In case of the extremely basic 1-aza-[6]helicene protonation strongly competed with molecular ion formation and tended to suppress the field ionization process. All molecular ion compositions were assured by accurate mass-based formula assignments.Graphical

Effect of Tar-adsorbing Particles on Tar Components Generated by Lignite Gasification in a Fluidized Bed Gasifier

In a dual fluidized bed gasifier suitable for gasification of lignite, tar is generated as the raw material is gasified because the gasification reaction has at 1073-1173 K, which is a relatively low temperature, and there is a problem such as tar adhering to the piping of the cooling system in the subsequent stage. In this study, in order to reduce tar in the gasification of lignite, porous alumina particles were applied as a tar adsorbent to the upper stage of a laboratory-scale two-stage fluidized bed gasifier, and the gasification characteristics of the produced gas and the tar components were analyzed and its effect was investigated. From the analysis results of tar components using gas chromatograph mass spectrometry (GC/MS) and field desorption mass spectrometry (FD-MS), the tar components obtained under the respective gasification conditions of pyrolysis and steam were almost no difference, and the main components of tar were polycyclic aromatic hydrocarbons without substituents. It was also found that the main components of tar can be sufficiently identified by GC/MS analysis alone. The application of the porous alumina particles increased the gas yields due to the cracking effect of tar. Furthermore, it was confirmed that the gas yields increased under the steam gasification condition rather than pyrolysis condition, and the gasification reactions were promoted by steam. From these results, it is considered that the porous alumina particles are effective in reducing tar, and as a reformer using this, a dual-type reformer capable of using the tar adsorbent for a long period of time is suitable.

From the discovery of field ionization to field desorption and liquid injection field desorption/ionization-mass spectrometry-A journey from principles and applications to a glimpse into the future.

The discovery of the ionizing effect of strong electric fields in the order of volts per Ångstrom in the early 1950s eventually led to the development of field ionization-mass spectrometry (FI-MS). Due to the very low ion currents, and thus, limited by the instrumentation of the 1960s, it took some time for the, by then, new technique to become adopted for analytical applications. In FI-MS, volatile or at least vaporizable samples mainly deliver molecular ions, and consequently, mass spectra showing no or at least minor numbers of fragment ion signals. The next major breakthrough was achieved by overcoming the need to evaporate the analyte prior to ionization. This was accomplished in the early 1970s by simply depositing the samples onto the field emitter and led to field desorption-mass spectrometry (FD-MS). With FD-MS, a desorption ionization method had become available that paved the road to the mass spectral analysis of larger molecules of low to high polarity and even of organic salts. In FD-MS, all of these analytes deliver spectra with no or at least few fragment ion peaks. The last milestone was the development of liquid injection field desorption/ionization (LIFDI) in the early 2000s that allows for sample deposition under the exclusion of atmospheric oxygen and water. In addition to sampling under inert conditions, LIFDI also enables more robust and quicker operation than classical FI-MS and FD-MS procedures. The development and applications of FI, FD, and LIFDI had mutual interference with the mass analyzers that were used in combination with these methods. Vice versa, the demand for using these techniques on other than magnetic sector instruments has effectuated their adaptation to different types of modern mass analyzers. The journey started with magnetic sector instruments, almost skipped quadrupole analyzers, encompassed Fourier transform ion cyclotron resonance (FT-ICR) and orthogonal acceleration time-of-flight (oaTOF) analyzers, and finally arrived at Orbitraps. Even interfaces for continuous-flow LIFDI have been realized. Even though being niche techniques to some degree, one may be confident that FI, FD, and LIFDI have a promising future ahead of them. This Account takes you on the journey from principles and applications of the title methods to a glimpse into the future.

Accelerated reactions in field desorption mass spectrometry.

Field desorption mass spectrometry under ambient conditions is used to study solution-phase organic reactions in micro-volumes. Reagent solution is transferred onto the microdendrites of the field emitter, and reaction products are examined online by mass spectrometry. Three reactions, hydrazone formation by phenyl hydrazine and indoline-2,3-dione, the Katritzky reaction between a pyrylium salt and anisidine, and the Hantzsch synthesis of 1,4-dihydropyridine, were investigated, and reaction acceleration was observed to different extents. The increase in rate relative to the corresponding bulk reactions is attributed to solvent evaporation (simple concentration effect) and to the increase of surface-to-volume ratio (enhanced interfacial reactions). A distinguishing feature of this method of reaction acceleration, relative to that based on nano electrospray ionization, is the observation of radical cations and the formation of radical cation products. The study also breaks new ground in using field emitters at atmospheric pressure.

Static and dynamic adhesive properties between continuous basalt fibre cords and NR/SBR matrix tackified by p-octylphenolic resins

The effects of p-octylphenolic resins on the adhesion between continuous basalt fibre (CBF) cords with various surface treatments, i.e., desizing and RFL dipping, and a natural rubber (NR)/styrene-butadiene rubber (SBR) matrix were investigated by adding p-n-octylphenolic and p-t-octylphenolic resins to the rubber matrix, respectively. The structure of the RF resins with various F/R ratios was characterized and probed by field desorption mass spectrometry (FD-MS) and solubility testing. The desized and 2 types of RFL-dipped CBF cords were used to prepare the H-shaped samples with the matrices. The results of H pull-out tests showed that the p-octylphenolic resins could more effectively improve the static adhesion between the CBF cord and the rubber matrix when the cord was coated by the RFL layer with a high F/R ratio. The dynamic adhesive properties were studied with an MTS elastomer testing system, and the results showed that the addition of either resin could significantly improve the interfacial fatigue life of the RFL-coated cord/rubber matrix. The p-t-octylphenolic resin was demonstrated to be more effective due to the branching side chain and higher molecular mass, which resulted in sufficient entanglement between the molecular chain of the matrix and the RFL layer.

Characterization of Charge Reactions of Li-Air Battery Cathodes Studied with Field Ionization Methods

In recent years, lithium-air batteries have attracted significant interest due to increased energy density compared to currently available technologies such as lithium-ion batteries. The discharge process involves oxygen reduction to form LiO2, followed by further reduction to Li2O2 1. Meanwhile, oxygen evolution from the discharge deposits occurs during charge. The poor conductivity of Li2O2 2 requires the use of high overpotentials during charge, leading to side reactions that hinder battery performance1. A significant amount of work has been devoted at improving battery performance via cathode3 and electrolyte engineering4. In addition, several experimental and computational studies have attempted to understand the nature of the charge and discharge reactions through the use of electrochemical cells2,4-5. However, the complexity of electrochemical cells makes it difficult to gain fundamental insight of these processes. An alternative involves the use of ultrahigh vacuum (UHV) studies, where the ability to examine the influence of electrode potential on surface reactions is limited. This issue can be resolved by focusing on the effect of electric field on surface reactions since electric field is directly related to electrode potential. An example of a UHV technique is field ionization microscopy (FIM). In FIM, a Pt field emitter tip of approximately 350 Å radius is used as the substrate. The electric field on the surface is easily controllable by biasing the tip at moderate voltages (around 5 kV), to produce fields of up to 5 V/Å6. Reactions are carried out by adsorption of the species of interest (Li, O2, and a solvent representative of the electrolyte) followed by application of a baseline field. Adsorbed reaction products and their morphology can be monitored by FIM and field electron microscopy (FEM). Reaction intermediates and products can be detected by pulsed field desorption time of flight mass spectrometry (PFD-MS). In PFD, reactions products are formed under a base field, followed by desorption when a field pulse is applied. By varying the base field magnitude, pulse repetition frequency, and reaction temperature, it is possible to obtain information such as activation energies and possible reaction steps7. In this work, the kinetics of LiOx consumption in acetonitrile, a low DN solvent, will be studied using PFD and FIM. Namely, the focus of this work will be to characterize the effect of electric field, temperature, and reaction time on the rate of Li2O2 consumption during charge, as well as characterizing the lifetime of the LiO2 intermediate during charge. References Girishkumar, G; McCloskey, B; Luntz, A. C; Swanson, S; Wilcke, W. “Lithium-air battery: Promise and challenges”. Phys. Chem. Lett. 2010, 1, 2193–2203Viswanathan, V; Thygesen, K. S; Hummelshøj, S; Nørskov, J. K; Girishkumar, G; McCloskey, B. D; Luntz, A. C. “Electrical Conductivity in Li2O2 and its role in determining capacity limitations in non-aqueous Li-O2 batteries”. J Chem. Phys. 2011, 135, 214704Kwak, W. J; Lau, K. C; Shin, C. D; Amine, K; Curtiss, L. A; Sun, Y. K. “AMo2C/Carbon Nanotube Composite Cathode for Lithium-Oxygen Batteries with High Energy Efficiency and Long Cycle Life”. ACS Nano. 2015, 9, 4129–4137Laoire, C. O; Mukerjee, S; Abraham, K. M; Plichta, E. J; Hendrickson, M. A. “Influence of Nonaqueous Solvents on the Electrochemistry of Oxygen in the Rechargeable Lithium-Air Battery”. Phys. Chem. C. 2010, 114, 9178–9186Laoire, C. O; Mukerjee, S; Abraham, K. M; Plichta, E. J; Hendrickson, M. A. “Elucidating the Mechanism of Oxygen Reduction for Lithium-Air Battery Applications”. Commun. 2011 , 47, 9438-9440Rothfuss, C. J; Medvedev, V. K; Stuve, E. M. “The influence of the surface electric field on water ionization: a two-step dissociative ionization and desorption mechanism for water ion cluster emission from a platinum field emitter tip”. Surface Science. 2003, 554-555, 133-143Kruse, N. “Surface reaction kinetics on the atomic scale: studies by means of pulsed field desorption mass spectrometry”. Materials Science and Engineering A. 1999, 270, 75-82

Chemistry of Hume-Rothery inspired organometallics: Selective functionalization of [M(ZnCp*)4(ZnCH3)4] (M = Ni, Pd, Pt) with terminal alkynes to yield [M(ZnCp*)4(ZnCCSiiPr)4

The all-zinc coordinated group-8 metal complexes [M(ZnCp*)4(ZnCCSi(iPr)3)4] (M = Ni (1), Pd (2), Pt (3)) were obtained by selective functionalization of the protecting organic ligand shell starting out from the organometallic MZn8-complexes [M(ZnCp*)4(ZnMe)4]. The reaction with excess HCCSi(iPr)3 leads to a stepwise exchange of the methyl to alkynyl groups under liberation of methane over very long reaction times at elevated temperatures. All complexes 1–3 were isolated in pure form an in good yields and were fully characterized by 1H, 13C NMR as well as by liquid injection field desorption (LIFDI) mass spectrometry. In addition, single crystal structure analysis of 1 and 3 were performed showing that the bimetallic dodecahedral [MZn8] core of the starting complexes remains intact in the product complexes.

Identification of diacetonamine from soybean curd residue as a sporulation-inducing factor toward Bacillus spp.

Under bioassay-guided investigation, a sporulation-inducing factor (SIF) toward Bacillus spp. was searched for in methanol (MeOH) extracts of soybean curd residues, and diacetonamine (1) was identified as the active compound. SIF was first isolated as a monoacetylated derivative (2, 4.1 mg from 655 g soybean curd residues), and its chemical structure was elucidated by field desorption mass spectrometry, electron ionization mass spectrometry, and nuclear magnetic resonance (NMR) analyses. After 48-h incubation, 40 µM diacetonamine hydrochloride (1b) exhibited sporulation-inducing activity with 35% sporulation frequency toward a Bacillus amyloliquefaciens wild-type strain (AHU 2170), whereas 40 µM diacetone acrylamide (3) showed 99% sporulation induction, which was much higher than that of 1b. Although Bacillus megaterium NBRC 15308 was sporulated by the treatment with 400 µM 1b with 36 and 70% sporulation frequency after 72- and 96-h incubation respectively, 3 at the same concentration showed only 2% sporulation after 72-h incubation. Hence, diacetonamine (1) was characterized as a genuine SIF from soybean curd residues, but it was uncertain whether 1 is a natural product or an artifact. Spores of B. amyloliquefaciens induced by 1b survived after treatment with heating at 95 °C for 10 min, also suggesting that 1 is genuine SIF in soybean curd residue. As sporulation induction is likely linked to activation of antibiotic production in some spore-forming Firmicutes bacteria, compound 1 would be a possible chemical tool to develop an effective fermentation technology in Bacillus species.

Thermal polymerization mechanism of thitsiol separated from Gluta usitata

ABSTRACTThitsiol separated from Gluta usitata lacquer sap was polymerized by thermal catalysis, and the dimers were purified by HPLC. The dimer chemical structures were characterized by NMR and field desorption mass spectrometry spectroscopy. Almost all dimers have biphenyl nuclear–nuclear (C–C) structure that is somewhat different to the thitsiol dimer obtained from laccase catalysis. Based on these results, the thermal polymerization mechanism of thitsiol was discussed.

New Approach to Analysis of Tar Components in Syngas Generated by Steam Gasification of Lignite in Fluidized Bed Gasifier

Lignite is a low-rank coal that is not used as a fuel in Japan. However, the effective utilization of this resource could be enabled by production of syngas (hydrogen, carbon monoxide, etc.) from lignite through gasification. Tar in the syngas generated using the fluidized bed gasifier must be removed, and the tar composition should be considered for the design of effective tar removal equipment. A new analysis and analytical methods of the tar were developed herein. Gas chromatograph mass spectrometry (GC/MS) and field desorption mass spectrometry (FD-MS) were used in combination to analyze the tar obtained during steam gasification of lignite at 1123 K using a laboratory-scale fluidized bed gasifier. The low-boiling-point components were previously identified by GC/MS. However, the combined use of GC/MS and FD-MS in the new approach presented herein enabled elucidation of the overall composition of tar, including the high-boiling-point components.

Field Ion Microscopy and Pulsed Field Desorption Mass Spectrometry: Unique Tools for Surface and Subsurface Analysis

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Characterization of Petroleum Heavy Oil Fractions Prepared by Preparatory Liquid Chromatography with Thin-Layer Chromatography, High-Resolution Mass Spectrometry, and Gas Chromatography with an Atomic Emission Detector

In this study, a preparatory-scale fractionation method was developed. To verify the effectiveness of this method, an oil sample was fractionated into five fractions, referred to as saturate, aro1, aro2, polar1, and polar2; these fractions were completely characterized by thin-layer chromatography–flame ionization detection (TLC–FID), field desorption (FD) and (+) atmospheric pressure photoionization (APPI) high-resolution mass spectrometry (HR-MS), and gas chromatography with an atomic emission detector (GC–AED). TLC–FID analysis was used to compare the results obtained by the fractionation method to those obtained from the conventional saturates, aromatics, resins, and asphaltenes (SARA) method. FD–MS was employed to characterize the hydrocarbon class compounds in the saturate and aro1 fractions. As observed from the FD–MS spectra, non-aromatic hydrocarbon compounds were abundant in saturates, while mono- and diaromatic compounds were abundant in the aro1 fraction. This result is in good agreement with ...

202 流動層ガス化炉を用いた褐炭の水蒸気ガス化における合成ガス中のタール成分の解明(OS1 燃焼,エネルギー変換,熱利用(2),研究討論セッション)

The purpose of this study is to clarify compounds of tar (light tar and heavy tar) in which are produced in a fluidized bed gasifier. The light tar compounds were identified by gas chromatograph mass spectrometer (GC/MS). The results of field desorption mass spectrometry (FD-MS) of tar showed that m/z increased by 24 when adding aromatic-ring to polycyclic aromatic hydrocarbon (PAH). Also, it was found that m/z changed 26 in difference to the bonding position of aromatic-ring with PAH. By applying this law to Benzo[ghi]perylene (M. W. 276), it was found that main compounds of tar were PAH.

Synthesis of Polysilanes Using Mg and Lewis Acid and the Consideration of This Reaction Mechanism

Reduction of dichlorosilanes with Mg metal in the presence of LiCl and Lewis acid such as FeCl2 or ZnCl2 was found to be the highly practical method for the synthesis of polysilanes (PS). This method is so useful and practical that PS can be prepared by stirring dichlorosilanes at room temperature. This method was successfully applied for the synthesis of various types of PS having a linear structure, a cyclic structure and silane-styrene copolymers as another type of PS. The structure of the reaction intermediates was also analyzed. At the initiation stage the results of FD-MS (Field desorption mass spectrometry) and GPC (Gel permeation chromatography) showed that linear oligomers were mainly formed by stepwise reactions, and then the high polymers and cyclic oligomers were formed in parallel.

Characterization of Metal Phthalocyanine Catalysts Using Field Desorption Mass Spectrometry

Metal phthalocyanines are a very important class of compounds due to their ability to activate oxygen, which enables them to become useful chemical reagents and largely-accepted catalysts for many chemical reactions. Phthalocyanines containing metals like iron, cobalt, manganese and vanadium are useful catalysts in many refinery processes. In the petroleum industry mercaptans are oxidized to disulfides by aerobic oxidation in an alkaline medium in the presence of a metal phthalocyanine. A number of analytical techniques have been explored to characterize metal phthalocyanines. In this article, we have for the first time successfully used field desorption mass spectrometry (FDMS) techniques for the characterization simple metal phthalocyanines and substituted metal phthalocyanines. For this purpose metal phthalocyanines were prepared in the laboratory and the conditions were optimized for the characterization of metal phthalocyanines containing cobalt, nickel, copper and zinc by FDMS. This technique was also successfully applied to characterize sulfato, nitro, and chloro substituted phthalocyanines. This technique has been found to be a useful tool for the characterization of phthalocyanines.

Preparation and characterization of a new lacquer based on blending urushiol with thitsiol

AbstractA new lacquer that blends R. vernicifera (Chinese lacquer, urushiol) with Melanorrhea usitata (Thai lacquer, thitsiol) was prepared. The main properties, viscosities, drying times, drying mechanism, and the nature of the lacquer films as a coating material, were examined. In addition, the mechanism of transfer radical reaction that occurred between urushiol and thitsiol is discussed based on the results of two‐dimensional nuclear magnetic resonance (NMR) and field desorption mass spectrometry (FD‐MS) measurements. A blended lacquer with 70% R. vernicifera and 30% M. usitata showed almost the same drying time as 100% R. vernicifera as examined in an automatic drying time recorder but had higher surface smoothness and gloss. Furthermore, the molecular weight distribution, UV resistance, and glass transition temperature (Tg) also were investigated in detail. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Overcharge protection effect and reaction mechanism of cyclohexylbenzene for lithium ion batteries

We studied the relationship between the structure of aromatic compounds and the overcharge protection effect, using cyclohexylbenzene, isopropylbenzene, and toluene as the overcharge protection agents. Cyclohexylbenzene proved to be the most effective overcharge protection agent among these aromatic compounds. The effect is enhanced using a higher concentration of cyclohexylbenzene and elevated temperatures. The reaction product of cyclohexylbenzene was analyzed using field desorption mass spectrometry to elucidate its reaction mechanism. The results suggested that some of the overcharge reaction products of CHB were more reactive than that of IPB, which is consistent with the better suppressing effect on overcharging of the active material in the positive electrode.