Investigation of the Dipole Moment Effects of Fluorofunctionalized

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Investigations of dipole moment effects of fluorofunctionalized electrolyte additives in a lithium ion battery Mulugeta Tesemma, Fu Ming Wang, Atetegeb Meazah Haregewoin, Nur Laila Hamidah, Muhammad Hendra Pebrianto, Shawn D Lin, Chorng-Shyan Chern, Quoc-Thai Pham, and Chia-Hung Su ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.8b05635 • Publication Date (Web): 04 Mar 2019 Downloaded from http://pubs.acs.org on March 4, 2019

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ACS Sustainable Chemistry & Engineering

Investigation of the Dipole Moment Effects of Fluorofunctionalized Electrolyte Additives in a Lithium Ion Battery

Mulugeta Tesemma1, Fu-Ming Wang2,3,4,5*, Atetegeb Meazah Haregewoin1, Nur Laila Hamidah2, Muhammad Hendra P.2, Shawn D. Lin1*, Chorng-Shyan Chern1*, QuocThai Pham2, and Chia-Hung Su6

1Department

of Chemical Engineering, National Taiwan University of Science and

Technology, Taipei, Taiwan 2Graduate

Institute of Applied Science and Technology, National Taiwan University of

Science and Technology, Taipei, Taiwan 3Sustainable

Energy Center, National Taiwan University of Science and Technology,

Taipei, Taiwan 4Department

of Chemical Engineering, Chung Yuan Christian University, Taoyuan,

Taiwan 5R&D

Center for Membrane Technology, Chung Yuan Christian University, Taoyuan,

Taiwan 6Graduate

School of Biochemical Engineering, Ming Chi University of Technology,

New-Taipei City, Taiwan

*Correspondence to: 1. Prof. F. -M. Wang,

1 ACS Paragon Plus Environment

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IB 606, 43 Keelung Road, Section 4, Taipei 106, Taiwan, R.O.C. E-mail: [email protected] Tel: +886-2-27303755 Fax: +886-2-27376922

2. Prof. Chorng-Shyan Chern, E2-807, 43 Keelung Road, Section 4, Taipei 106, Taiwan, R.O.C. [email protected]

3. Prof. Shawn D. Lin, T2-512-3, 43 Keelung Road, Section 4, Taipei 106, Taiwan, R.O.C. [email protected]


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Abstract Bismaleimides modified through fluorosubstitution constitute two new electrolyte additives that have been successfully synthesized and used in lithium ion batteries. Fluorosubstitution significantly eliminates the interface impedances of the two electrodes and improves the rate performance of batteries because of the reduced LiF and Li2CO3 content in a solid electrolyte interphase. This study indicates that between the symmetric (two fluorosubstitutions) and asymmetric (one fluorosubstitution) designs of fluorosubstitution in bismaleimide structures, the symmetric design effectively inhibits the direct electrochemical reduction of –C=C– in bismaleimide on a graphite surface and reacts with ethylene carbonate in accordance with the high strength of the dipole moment. A cyclic voltammetry and battery measurements indicate considerable improvements due to the addition of bismaleimide modified through symmetric fluorosubstitution. The morphology of the anode electrode and chemical composition of the solid electrolyte interphase after 20 cycles were examined through scanning electron microscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance. A kinetic analysis of solid electrolyte interphase formation was performed on all electrolyte systems through an electrochemical quartz crystal microbalance. Battery performance demonstrated that the addition of bismaleimide modified through symmetric fluorosubstitution was able to increase the capacity for anode half-cells and c-rate performance for full cells at 2 C by 7% and 164%, respectively. These novel electrolyte additives not only prevented unnecessary compound formations in the solid electrolyte interphase but also enhanced the ionic



diffusivity and reversibility of the electrochemical reaction in the solid electrolyte interphase, cathode electrolyte interphase, and two-electrode surfaces.

Keywords: lithium ion battery, maleimide, dipole moment, stereoscopic coordination, fluorofunctionalized


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Introduction Studies on electrolyte additive developments in lithium ion batteries have received considerable attention because of several functions that improve solid electrolyte interphase (SEI) formation,1-3 cycle life,4 safety,5 rate performance,6 high voltage/ temperature applications,7 nonflammability,8 and use of particular solvents or active materials.9 However, electrolyte additives must satisfy certain criteria for favorable battery performance. Values for the highest occupied molecular orbital and lowest unoccupied molecular orbital (LUMO) are commonly used for evaluating electrolyte additives for use in batteries to predict the reaction potential.10-11 In particular, an electrolyte additive with a relatively low LUMO energy can be used for SEI formation on an anode to prevent solvent intercalation into graphite and enhance the ionic diffusivity of the interface. In addition, the oxidation potential of the electrolyte additive can be calculated using a particular formula involving highest occupied molecular orbital and LUMO values.12 From a practical perspective, the anode electrode operates at a low potential, which results in SEI formation on the anode surface13 through electrochemical reduction of both carbonate solvents and salt in the electrolyte. This is a crucial feature of anodes for highly reversible cycling and long-term stability.14-16 The importance and limitations of the SEI are generally accepted by researchers of lithium ion batteries, primarily because each factor of the SEI, such as high ionic diffusivity,17 compositions of polycarbonate/Li2CO3 during formation,18 and loose/dense structures,19-22 is crucial 5 ACS Paragon Plus Environment


for lithium ion battery performance. However, uncontrolled formation, the effect on the initial capacity, and growth in the subsequent cycling of batteries are still considerable challenges in SEI research.13-16, 23, 24 Recent studies have reported notable results regarding fluorosubstituted compounds for fabricating an SEI on the surface of graphite and Si anode materials. Lin et al. demonstrated that difluorophosphate (LiPO2F2) enables the formation of a new SEI for graphite anode perfection. The results indicated that a suitable addition of LiPO2F2 in the SEI can provide excellent cycling stability for a full-cell system in accordance with the decrease in charge transfer resistance on the anode by lowering the amount of LiF formation.25 Fluoroethylenecarbonate (FEC) has been the most prevalently used electrolyte cosolvent for silicon and graphite materials. According to some studies, FEC has several functions, including forming a barrier against an HF attack,26-29 forming an elastomeric crosslinked network against the volume expansion of lithiation/delithiation cycles,30 and providing superior SEI quality compared with vinylene carbonate.31-32 To understand the distinctness of fluorosubstituted compounds, some studies have attributed battery performance improvements to the formation of two compounds, namely LixPOyFz33-34 and an elastomer matrix obtained from defluorination.35 Zheng et al. presented a high-elasticity SEI film formed within a sodium acrylate coating through in situ uniform polymerization on a graphite surface. They used this flexible polymeric substrate to form a novel pattern for SEI geometry in lithium ion batteries. The results indicate that the discharge capacity and Columbic efficiency of natural graphite with sodium acrylate increased considerably.36 The aforementioned results indicate that fabricating an elastomeric SEI on a graphite or silicone surface is essential because of their compatibility with changes in particle volume during charging and discharging. However, the aforementioned research has


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only discussed the defluorination mechanisms of FEC and has not comprehensively investigated the relationship between the stereoscopic coordination or dipole moment effects of an electrolyte additive structure and the formation of elastomer products. The electron-cloud density distribution, steric number, and dipole moment of molecules are critical for dominating self-polymerization or polymerization with other compounds. In general, molecules with a high polarity can easily attract or repel valence electrons from other compounds and generate reactions through electron transfer. In this study, two novel fluorosubstitution bismaleimides (BMIs) were synthesized to investigate the effects of stereoscopic coordination and dipole moment on defluorination. Studies have demonstrated that BMIs are an excellent electrolyte additive for graphite SEI fabrication because of their high reduction potential and favorable chemical and physical compositions.22,37 The results indicated that BMIs significantly enhance cycle ability and rate capability.22,38-39 Therefore, the characteristics of an elastic SEI film formed by two new fluorosubstituted maleimide structures were studied.

Experimental Section Synthesis of fluorosubstitution maleimides The

additives

include

o-phenylenedimaleimide

(MI),

4-flouro-o-

phenylenedimaleimide (1F-MI), and 4,5-diflouro-o-phenylenedimaleimide (2F-MI). 1F-MI and 2F-MI were synthesized in two steps: hydrogenation and dehydration.

Synthesis of 1F-MI Scheme 1 shows the 1F-MI synthesis. A glass reactor (with a feeding pipe) was equipped with a thermometer, mechanical paddle stirrer, and water-cooled condenser. 7 ACS Paragon Plus Environment


In this study, 10 g of 4-flouro-2-nitroaniline, 0.5 g of palladium-activated carbon (10% loading), and 60 mL of ethanol were added into the reactor and stirred. Hydrazine hydrate (8 mL) was added to the feeding pipe. The reaction was maintained until the temperature reached 80°C. After the reaction temperature had been achieved, hydrazine hydrate was added into the reactor by gradually opening the feeding pipe. Subsequently, hydrogenation occurred, with a reaction time of 24 h. The precipitated product was cooled through vacuum filtration, washed with water three times, and dried for 24 h at 60°C in a vacuum oven. The product was recrystallized for further purification before being used. The yield of this reaction was 96.1%. The molecular weight measured in a mass spectrum was 126 g mol−1. Until the compound was completely dissolved, 1 mol of 4-flouro-1,2phenylenediamine was added to 50 mL of acetone for 15 min. Then, 2.1 mol of maleic anhydride and 5 mL of triethylamine were added to the previous solution. The reaction was maintained at 100°C for 60 min, and 0.08 and 2.5 mol of magnesium chloride hexahydrate and acetic anhydride, respectively, were then simultaneously added at a temperature of 150°C for 3 h to close the ring. After the reaction, the mixture was cooled to room temperature and water was added until the precipitated product had formed. The product was washed with water three times and dried for 24 h at 60°C in a vacuum oven. The product was recrystallized for further purification before being used. The yield of this reaction was 85.6%, and 4-fluoro-o-phenylenediamaleimide exhibited a 1H NMR (CDCl3) of δ (ppm) = 7.39–7.35, 7.27, 7.18–7.14, 7.05, 6.81, and 6.79. The molecular weight measured in the mass spectrum was 286 g mol−1.

Synthesis procedure of 2F-MI


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Scheme 1 shows the synthesis of 2F-MI. A glass reactor (with a feeding pipe) was equipped with a thermometer, mechanical paddle stirrer, and water-cooled condenser. Here, 10 g of 4,5-difluoro-nitroaniline, 0.5 g of palladium-activated carbon (10% loading), and 55 mL of ethanol were added to the reactor for stirring. Hydrazine hydrate (8 mL) was added to the feeding pipe. A heterogeneous reaction mixture was maintained until it reached a temperature of 80°C, at which time hydrazine hydrate was added into the reactor by gradually opening the feeding pipe; the hydrogenation process then occurred, with a reaction time of 24 h. The precipitated product was cooled through vacuum filtration, washed with water, and dried for 24 h at 60°C in a vacuum oven. The product was recrystallized for further purification before it was used. The yield of this reaction was 93.2%. The molecular weight measured in the mass spectrum was 144 g mol−1. In this study, 1 mol of 4,5-diflouro-phenylenediamine was added to 50 mL of acetone for 15 min until the compound was completely dissolved. Then, 2.1 mol of maleic anhydride and 5 mL of triethylamine were added to the previous solution. The reaction was maintained at 100°C for 60 min. Next, 0.08 and 2.5 mol of magnesium chloride hexahydrate and acetic anhydride, respectively, were simultaneously added at a temperature of 150°C for 3 h to close the ring. After the reaction, the mixture was cooled to room temperature and water was added until the precipitated product had formed. The product was washed with water three times and dried for 24 h at 60°C in a vacuum oven. The product was recrystallized for further purification before it was used. The yield of this reaction was 88.1.6%, and 4,5-diflouro-phenylenediamaleimide exhibited a 1H NMR (CDCl3) of δ (ppm) = 7.30–7.25, 7.13, 6.81, and 6.40. The molecular weight measured using the mass spectrum was 306 g mol−1.



Electrode and electrolyte preparations A graphite anode comprised 93 wt% of mesocarbonmicrobeads (MCMB-2528, Osaka Gas), 3 wt% KS4 as a conductive additive, and 4 wt% polyvinylidene fluoride (PVDF) as a binder. The cathode material comprised 91 wt% lithium cobalt oxide (LiCoO2L106 LICO Corp., Taiwan) as an active material, 5 wt% KS6, and 4 wt% PVDF. Lithium hexafluorophoshate (LiPF6) of 1.1 M in EC: PC: DEC (3: 2: 5 in volume) mixed solvents; 0.1 wt% MI-based additives were dissolved and mixed in the electrolyte.

Instrumentation The electrochemical stability of electrolytes was measured through cyclic voltammetry (CV) using a Biologic VMP3 from 3 to −0.1 V at a scanning rate of 0.5 mV s−1. CV measurements were performed with a three-electrode Teflon cell that had stainless-steel (304 type) working/counter electrodes (area 1.0 cm2) and a lithium metal reference electrode. The electrolyte filled the space between the working and counter electrodes. Charge and discharge were completed using a charge–discharge instrument (CHG5500C, UBIQ Technology Co. Ltd) at a constant voltage of 0.01–3 V within a 0.2 C/0.2 C condition for the first cycle in the anode half-cell. The c-rate test of the fullcell was charged at a constant current of 0.1 C to 4.2 V and discharged at 0.05, 0.1 C, 0.2 C, 0.5 C, 1 C, and 2 C to 3 V. The N/P (A/C) ratio was 1.05, in which the cathode had 3.5 mAh cm−2 and anode had 3.675 mAh cm−2. The current density of the full-cell test was calculated in accordance with the loading of the cathode, meaning that 0.1 C corresponded to 0.35 mA cm−2. After the cyclability test, the cell was disassembled for X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) measurements.


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Electrochemical impedance spectroscopy (EIS) was performed using a Biologic VMP3 in the frequency range of 100 MHz to 0.01 Hz with an alternative current amplitude of 5 mV at 25°C. All EIS measurements employed an anode half-cell and full cell (CR2032) comprising Li/MCMB and LiCoO2/MCMB electrodes. The riveted refinement of an equivalent circuit model was used to simulate and demonstrate the physical connotations of the semicircles in the EIS spectra. Re, RSEI, and Rct are the electrolyte resistance, bulk resistance of the SEI, and electrochemical charge transfer resistance on the electrode surface, respectively. The morphology of the MCMB electrodes was observed through SEM after a Pt coating was sputtered at accelerating voltages of 5 and 15 kV. The surface composition was determined through XPS (PHI, 1600S). Before performing SEM and XPS, the specimens were disassembled in a glove box, washed with dimethyl carbonate, and dried in a vacuum for 2 h. A three-electrode electrochemical cell setup was used for electrochemical quartz crystal microbalance (EQCM) measurements (QCA922, Seiko). In operando EQCM measurements were obtained using the frequency change in a linear sweep voltammetry process (scanning rate, 0.2 mV s−1; voltage range, OCP to 0.01 V). The frequency changes derived from the experimental results were converted into mass changes using the Sauerbrey equation.40 In this study, 9 MHz Au chips were adopted, and theoretical mass sensitivity (ks) was considered to be 18.31 × 107 Hz g−1 cm−2.

Δf = -ks × Δm (Δf, change in frequency; ks, theoretical mass sensitivity; Δm, change in mass)



NMR experiments were performed using a Varian Unity INOVA 500 NMR spectrometer equipped with a Chemagnetics 7.5-mm magic angle spinning probe and a double-tuned wide-line probe. The

13C

chemical shifts were reported relative to the

NMR solvent as an internal standard. D2O was used to extract the SEI that formed on the Au chips after EQCM measurement. The dipole moment of functionalized MI additives was calculated with respect to the vacuum level using density functional theory (DFT) with a nonlocal functional B3LYP and PBEPBE method, in which an aug-cc-pVDZ basis was set using Gaussian 09 software. The LUMO energy values of additives were calculated based on b311B3LYP (6-311 + g(dip)) using Gaussian 09 software. For the ex situ Fourier-transform infrared spectroscopy (FTIR) analysis, measurements were performed inside a glove box in the attenuated total reflectance (ATR) mode using a Bruker Optics spectrometer equipped with a single-reflection ATR sampling accessory. A three-electrode cell suitable for CV measurement was used to perform linear sweep voltammetry on selected potential regions where the reduction of each solvent and MI additive occurred. Thereafter, the working electrode was washed with dimethyl carbonate, dried, and used to record the FTIR spectrum. Because no absorbance band was found in the region between 2000 cm−1 and 2800 cm−1 in any system, the region from 2100 cm−1 to 2750 cm−1 was excluded in all FTIR spectra.

Results and Discussion Cyclic voltammetry analysis of electrolytes A CV analysis was performed to characterize lithium plating/stripping reversible reactions with three electrolyte additives. Figure 1 reveals that the blank electrolyte had the largest reaction area on cathodic and anodic scans. The integral area was obtained 12 ACS Paragon Plus Environment

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by MI > 1F-MI > 2F-MI. The results indicated that blank electrolytes strongly activate lithium ion plating and stripping reactions compared with electrolytes with additives. According to the calculation of the integral area, the irreversible Coulombic efficiency was 52%. Moreover, Fig. 1 displays the clear reaction of EC reduction at 0.8 V, which is consistent with the results of other studies.41-42 The MI additives considerably affect the electrochemical reaction of electrolytes, which may be attributed to the carbonyl group on imide rings. The four electron-withdrawing carbonyl groups strongly attract lithium ions when the additive is dissolved in the electrolyte. The carbonyl groups strongly attract lithium ions, which are used to weaken lithium plating and stripping reactions. In terms of the effect of the fluorosubstitution number, 2F-MI effectively reduces lithium plating and stripping reactions. Figure 1 shows that the EC reaction potential shifts to a range of 0.45–0.55 V, with a delay of approximately 0.35–0.25 V. Furthermore, MI additions considerably increase the activity of EC; this implies a correlated reaction between MI and EC. In this study, fluorosubstitution changed the stereoscopic coordination and dipole moment of MIs, particularly in 2F-MI. According to the DFT calculation (Table 1 and Fig. 2), the dipole moment of 2F-MI (4.764 D) was considerably higher than that of F-MI (3.495 D) and MI (1.961 D) because of a symmetric high electron-withdrawing effect. Studies have demonstrated that EC has a high molecular dipole moment (4.900 D).43 This result indicates that EC molecules were sequentially arranged and followed 2F-MI molecules due to the relatively low reaction potential. Therefore, 2F-MI reduces first at a high potential, and EC follows the reaction at a low potential. The dipole moments of EC and 2F-MI are similar, and charge accumulation on the anode particle surface is low and reduces SEI formation because of the attraction between the electron charges of EC and 2F-MI. However, FMI and MI additives have considerably different dipole moments than EC. Therefore,



charge accumulation on the anode particle surface is high and triggers strong dipole– dipole interactions between EC and the two additives. The high amount of charge on the anode surface induces active SEI formation. Furthermore, all MI additives exhibit specific reduction potentials in an electrochemical window of 2.1–2.4 V, such as MI (2.27 V), 1F-MI (2.31 and 2.35 V), and 2F-MI (2.16 and 2.39 V). The LUMO energies of MI, 1F-MI, and 2F-MI were calculated to be −0.62, −0.72, and −0.69 eV, respectively, which are all lower than the cyclic carbonates (EC and PC). Moreover, the irreversible Coulombic efficiency of MI, 1F-MI, and 2F-MI were 32%, 35%, and 25%, respectively (see table in Fig. 1). The fluorosubstitution additives have two reduction potentials; this is different from MI, which only has one reaction. The intensity of the early (higher) reaction potential was considerably weaker than that of the late (lower) reaction potential on both fluorosubstitution samples. The defluorination reactions of 1F-MI and 2F-MI are expected to be assigned at the early (higher) reaction potential because MI does not have this shoulder reaction. However, the late (lower) reaction potential is therefore assigned to the electrochemical polymerization of -C=C- bonding. According to the results in Fig. 1, 1F-MI provides strong electrochemical polymerization of -C=C- bonding and a weak defluorination reaction. Notably, with symmetrical fluorosubstitution, the 2F-MI effectively decreases both the reactions of electrochemical polymerization of -C=C- bonding and defluorination. Therefore, less SEI may form on the 2F-MI system compared with other systems.

Battery performance and EIS analysis of MCMB half-cells Figure 3a shows the first charge and discharge curves of Li/MCMB metal cells for all electrolyte systems. The results indicate that charge curve tendencies are similar,


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demonstrating that the additives do not affect electrochemical reactions. However, the discharge capacity reveals that the 2F-MI battery provides the highest performance among all of the batteries, including blank (296.1 mAh g−1; 95.6%), MI (305.7 mAh g−1; 95.9%), and 1F-MI (309.2 mAh g−1; 96.1%), exhibiting the highest capacity and Coulombic efficiency of 318.3 mAh g−1 and 97.8%, respectively. Figure 3b presents an EIS analysis of batteries after the first cycle. From the simulation of the equivalent circuit model, Re values in the real part are approximately the same. However, the RSEI values of the 2F-MI battery (3.8 Ω) were the lowest among all of the batteries, including the blank (8.1 Ω), MI (6.3 Ω), and 1F-MI (5.9 Ω) batteries. This result indicates that the 2F-MI additive composed of SEI is highly diffusive and provides a suitable infrastructure for reducing resistive impedance. Moreover, CV results in the unique SEI formation of the 2F-MI system, which causes the lowest charge transfer resistance on the MCMB surface and reduces the resistance of the SEI. Therefore, a high ionic transfer connection can be assumed to be established between the SEI and MCMB surface when 2F-MI is used. Furthermore, the imaginary part illustrates stimulating behaviors for both fluorosubstitution additives. Relevant literature44 indicates that a capacitive impedance in the EIS stores electric charge using a capacitor, whereas the resistive impedance consumes electric charge through chemical reactions. The increased capacitive impedance in the EIS spectrum indicates that the substances or interfaces between electrolyte and electrode surfaces effectively stored electric charges, which can be attributed to distinct chemical and physical compositions. In this study, the SEI formed by two fluorosubstitution additives exhibited low capacitive impedance in the first semicircle, whereas 2F-MI demonstrated the lowest capacitive impedance (2.1 Ω). This result indicates that the SEI affected by 2F-MI stores less electric charge, which demonstrates that lithium ionic



diffusion in the SEI is not interrupted by the high value of capacitive impedance, such as a blank system (3.0 Ω). With the addition of 2F-MI, its high dipole moment effect considerably reduces SEI formation. However, 2F-MI exhibits the highest value (6.9 Ω) in the second semicircle, whereas the blank has a lower value. The interface on the electrode surface formed by 2F-MI has a higher capacitive impedance than the blank. This higher impedance can be attributed to the effects of the high dipole moment and coordination of 2F-MI, in which the electron charges are attracted to each other and move from the MCMB surface to the interface of the 2F-MI and EC molecules. The SEI formed by EC comprises polycarbonates, lithium carbonate, alkyl carbonates, Li2O, LiF, and LiOH.45-46 The aforementioned compounds, including polycarbonates and alkyl carbonate, contain a soft carbon–oxygen channel, which has lone pairs for attracting lithium ions and enhances ionic diffusivity. Therefore, the capacitive impedance is increased using high amounts of polycarbonates and alkyl carbonate formations. The CV result (Fig. 1) indicates an interaction between ECs and MIs, where MIs promptly increase the EC reduction reaction intensity. The lone pairs on the ethereal oxygen of EC may attack the carbonyl carbon of MIs. When the carbonyl group reforms, the bond between the carbonyl carbon and nitrogen is broken, which opens the MI ring and results in the formation of further intermediate polycarbonate and alkyl carbonate compounds. Therefore, electric charges are stored by the aforementioned compounds and prepared for the electrochemical reaction.

Ex situ Fourier-transform infrared spectroscopy analysis of the effect of MI in an electrolyte Figure 4 displays the ex situ FTIR spectra for the effect with 0.1% MI addition in the electrolyte. Table 2 shows peak assignments based on references.47-55 The results


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indicate that the difference spectrum at 2.7 V is almost identical to the open circuit voltage spectrum. The new spectral features at 3355, 1451, 1400, and 1360 cm−1 observed in the difference spectrum at 1.9 V (Fig. 4c) can be attributed to C–O stretching, –N–H deformation, and C–N–C stretching, which indicates the opening of the MI ring. The few peak shifts and slight difference in peak shapes may be attributed to the subtraction effect and presence of DEC in the electrolyte. The FTIR spectra in the low-potential regions (Figs. 4d, 4e, and 4f) were recorded at potentials at which reductions of EC, PC, and DEC were anticipated.42 The spectra primarily comprised bands with peak positions that are comparable to those of the open circuit voltage and 2.7 V spectra; however, the peak shape was slightly different, which may have been because of the subtraction effect. This difference is attributed to the interaction of EC with the reduction products of MI, and a possible interaction mechanism is presented in Scheme 2. The primary radical anion 2 forms when MI accepts an electron, and the anion may attack another MI molecule to form radical anion 4, which can be stabilized through electron delocalization, and radical ion 3 (Scheme 2). However, the lone pairs on ethereal oxygen of EC may attack the carbonyl carbon of anion 3 and form radical anion 6. This may not be observed for PC because of the steric hindrance caused by the presence of an extra methyl group. When the carbonyl group is reformed, the bond between the carbonyl carbon and nitrogen is broken, which opens the MI ring and results in the formation of radical anion 7. Furthermore, radical anion 7 may accept hydrogen from the system through hydrogen abstraction from the CH3– or CH2– group of solvents and form radical anion 8, which is validated by the presence of the –N–H group in the FTIR. The negative charge on carbonyl oxygen attacks carbonyl carbon and forms radical anion 9. This radical anion may attack another MI and form a



polymeric chain-radical anion 11. This reaction of MI as shown in Scheme 2 can form a more compact SEI than that formed through the linear chain polymerization observed in a pure electrolyte system. The satisfactory initial performance of the batteries with the MIs addition in Fig. 3 indicates that products from the reduction in the ring-opening of MIs and subsequent reaction can form passivating layers.

SEM and XPS analysis of the MCMB surface Figure 5 presents the SEM morphology of the MCMB surface after 20 cycles at room temperature. The analysis indicates that the MCMB particle size is approximately 25– 30 µm. After the electrochemical reaction, discovery of the SEI on the MCMB surface in blank, MI, and 1F-MI cases is easier. However, in the 2F-MI system, no considerable SEI formation was observed. Similar to yellow arrow indication, some areas of the MCMB surface are not covered with the SEI. This result confirms that 2F-MI effectively reduces SEI formation through the high dipole moment effect. Additional scientific explanations for minimal SEI formation are provided in subsequent passages. Figure 6 presents the XPS analysis of the MCMB surface after 20 cycles at room temperature. According to relevant literature, Fig. 6a can be divided into several regions. The region for 284–286 eV represents the sp2 carbon structure at 284.4 eV.56-57 Additionally, the region for 286–292 eV presents a –C–O–C bonding of RCH2OCO2Li(alkyl lithium carbonates) at 288 eV, –C–O– bonding of Li2CO3 at 288.5 eV, and –C=O– bonding of RCH2OCO2Li at 289.1 eV, respectively.58-62 Figure 6b presents a region for 527–534 eV that demonstrates Li2O at 527 eV, Li2CO3 or a –C– O–C bonding of RCH2OCO2Li at 531.5 eV, and a –C=O– bonding of RCH2OCO2Li at 532.5 eV.63-65 The O1s spectrum validates the similar results from C1s indicating that the SEI formed from 2F-MI comprises a large amount of Li2CO3 and RCH2OCO2Li on 18 ACS Paragon Plus Environment

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the MCMB surface, which reduces the intensity of sp2 carbon. The results in Figs. 6a and 6b indicate that the blank electrolyte without any additive does not fabricate too much carbonate-based SEI after the cycle test. However, a small amount of Li2O formation was observed in the blank system and may explain the high charge transfer resistance in the results presented in Fig. 3b. Figure 6c shows the region for 681–688 eV that demonstrates LiF at 684.2 eV and an R–F bond at 686.5 eV in the spectrum of F1s.66-67 Relevant studies have indicated that LiF formation is caused by the following three reactions:37,68

H2O + Li+ + e− → LiOH+ (1/2)H2

(I)

LiOH+ Li+ + e−→Li2O+(1/2)H2 (II) Li2O + HF → LiF+ H2O

(III)

After cycling, Li2O reacts with HF, which thickens LiF and increases the internal resistance of the cell, thereby reducing the battery performance. Figure 6c reveals that the blank system exhibits a considerable amount of LiF deposition on the MCMB surface, which is fabricated from the original Li2O formation and can be explained through the EIS result. In addition, LiF may be fabricated from the decomposition of LiPF6 to form LiF and PF5.10,68 By contrast, all MI additives, particularly 2F-MI, have a small amount of LiF, indicating that the SEI has a highly ionic diffusive pathway, and diffusion is uninterrupted. Figure 6d shows the Li1s spectrum, which indicates LiF at 55.3 eV and Li2CO3 at 54.3 eV.64,69 The result is consistent with the F1s spectrum in which the blank exhibits high LiF reserves. The XPS analysis revealed that a compound with a high dipole moment, such as 2F-MI, can become a buffer or an elastomer for



promoting the pathway II reaction of EC on the MCMB surface and form a carbonatebased SEI.42,70

EQCM and NMR analysis of SEI Figure 7 displays the EQCM results, which reveal the intrinsic electrochemical kinetics of all electrolytes. Figure 7a presents the variation in SEI mass, which slightly increases to 3.1 × 10−6 g at an open circuit potential of 1.13 V in the blank system because of the solvation of an EC-Li+ cluster on a gold electrode.71 The EC electrochemically reacts at the potential of 1.13 V, and the SEI mass considerably increases to 2.7 × 10−5 g until the reaction is complete at 0.85 V. This result indicates that the EC is sensitive to reactions at reduced potentials and forms the SEI because of the reduction in the ringopening of the ethylene group.72 Figure 7b presents the mass change status of the MI reaction, and the results indicate that the SEI mass rapidly increases to 9.1 × 10–6 g when MI self-polymerizes in the range of 2.8–2.1 V. Furthermore, the MI interacts with the EC at potentials greater than 2 V, and the change in the SEI mass increases to 2.6 × 10−5 g until 1.3 V is reached, which validates the promotion of MI with EC in previous ex situ FTIR measurements (Fig. 4). Fluorosubstitutions in Figs. 7c and 7d illustrate a remarkable result regarding symmetric and asymmetric effects. The dipole moment of F-MI is higher than that of MI; however, stereoscopic coordination is critical in dominating the SEI reaction. This result indicates that F-MI self-polymerizes at the two potentials of 2.6 V and 2.3 V, which is consistent with the CV results presented in Fig. 1. Two SEI mass increments of 1.1 × 10–6 and 4.3 × 10–5 g were observed at these two potentials, respectively. In the second reaction, the SEI mass rapidly increases, which indicates that a single fluorosubstitution promotes the self-polymerization of MI. This increase can be attributed to the uneven electron cloud of the asymmetric structure,


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which is used to enhance the dissociation of the EC-Li+ cluster and reinforce SEI formation.73 Moreover, the EC reacts at 1.1 V and the SEI mass does not considerably increase in this potential region, which is similar to the case for MI. In general, if MI is constructed into an ortho position, electron holes are created on two imide rings, and the benzene ring provides electron charges. However, a benzene ring does not substitute any functional group composed solely of protons; therefore, electron charges on the benzene ring are considerably weaker, in contrast to fluorosubstitution, which provides a real-time electron-negativity effect and alters the electron-cloud distribution on the MI structure. This advantage of 1F-MI gradually attracts the ethylene side and not the carbonyl side of EC and results in the ring-opening reaction. Therefore, SEI formation is sensitive because of the uneven electron cloud of the asymmetric structure. Figure 7d shows that the opposite result occurred in the symmetric fluorosubstitution compared with the asymmetric structure. The electrochemical polymerization of 2F-MI was observed at 2.5 and 2.3 V. A smaller increase of approximately 1.1 × 10−6 g was observed in the SEI mass. After the reaction of 2F-MI, the EC reaction was weak, at 1.1 V, indicating the formation of a negligible amount of additional mass. This result indicates that the symmetric structure of 2F-MI effectively inhibits EC decomposition. The SEI only developed through the 2F-MI reaction. As mentioned,74 compounds with a similar dipole moment can demonstrate excellent chemical directionality. In this case, two fluorosubstitutions of 2F-MI attracted the carbonyl group of EC; however, the electron-cloud distribution was even, meaning that the EC had not decomposed. Figures 7e–7g present the 13C NMR results of the SEI, which were extracted using D2O after EQCM measurements (Figs. 7a–7d).75 Fig. 7e indicates that all electrolyte systems demonstrate that the peaks at the full spectrum were prevalently assigned to carbonate solvents, such as 13.5 (PC), 18.1 (DEC), 62.5 (EC), 66.3 (PC), 67.9 (PC), 69.0 (DEC),



154.2 (DEC), 168.3 (EC), and 169.1 (PC) ppm. Relevant studies have indicated that EC, PC, and DEC can be electrochemically decomposed into lithium ethyl decarbonate, lithium propyl dicarbonate, and lithium ethyl carbonate at particular chemical shifts.7678

However, Figs. 7f and 7g show that two additional peaks (16.9 and 57.5 ppm) formed

by three MIs and were not observed in the blank system. A new compound was fabricated that provides high ionic diffusivity.

3.6 EIS analysis and C-rate measurements of a full cell Figure 8 presents the c-rate measurements of LiCoO2/MCMB full cells in all electrolyte systems. The 2F-MI exhibited the highest capacity in different rate tests compared with other electrolytes. The blank exhibited the least favorable capacity because of its high impedance in both the anode and cathode. For measurements from 0.5 C to 2 C, the battery performance of the three MI additives was somewhat varied. This variation can be attributed to results in XPS, EQCM, and EIS, which revealed that 2F-MI provides less SEI but a natural abundance of alkyl carbonate formation for fast ionic movement.

Proposed reaction mechanism of the SEI Figure 9 shows the proposed reaction mechanism of the blank and 2F-MI systems. This graph presents the reaction of the blank electrolyte, wherein several EC molecules solvated single lithium ions and diffused to the MCMB surface during the charging process. When the EC-Li+ cluster approached the MCMB surface, the electron hole of the ethylene group of EC immediately accepted the electron charge from the MCMB and decomposed into Li2CO3, alkyl carbonate, and lithium ethyl decarbonate. This decomposition is attributed to the large dipole moments of EC, which represents an active electron transfer reaction in the EC structure. However, the same process was


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not observed for the 2F-MI additive. The graphical abstract indicates that 2F-MI achieved contact with the MCMB surface earlier than EC because of the high reduction potential. The imide ring contained an electron hole and therefore achieved contact with the MCMB rather than the MI with fluorosubstitution. Fluorosubstitution provides a weak electron-withdrawing function and is maintained at a considerable distance from the MCMB surface. In addition, the self-polymerization of 2F-MI is difficult to achieve because of the limitation of stereoscopic coordination in the ortho position. Therefore, few 2F-MI decomposed, whereas most of the 2F-MI molecules were absorbed on the MCMB surface. Furthermore, the EC-Li+ clusters approached 2F-MI molecules with sequential arrangement because they have a similar dipole moment. Because of the high dipole moment of 2F-MI, the electron charges of fluorosubstitution provided stable neutral charge to the ethylene group of EC, which indicates less decomposition of ECLi+ cluster. Therefore, the SEI almost formed from the little self-polymerization of 2FMI rather than EC. With this difference between the blank and 2F-MI systems, the capacity and rate performance of the battery can be improved with a fluorosubstitution additive.

Conclusion This study synthesized two novel fluorosubstitution MI electrolyte additives that demonstrated excellent battery performance because of the effects of stereoscopic coordination and dipole moment. Symmetrical fluorosubstitution with the aforementioned effects efficiently eliminated LiF and Li2CO3 formation in the SEI and provided high ionic diffusivity of alkyl carbonate. In addition, the SEI, CEI, and interface on the anode and cathode surfaces exhibited the lowest impedance for a high rate performance. This is the first study to investigate electrolyte additives with dipole 23 ACS Paragon Plus Environment


moment and electron-cloud density calculations. The high dipole moment structure can eliminate the requirement for SEI formation, particularly for future applications in Si materials.

Acknowledgments The author is grateful for financial support from the Ministry of Science and Technology of Taiwan, ROC, under grant numbers 105-3113-E-011-002, 105-2628-E011-005-MY3, 105-2811-E-011-017, 106-3113-E-011-001, 106-2923-E-036-002MY3, 106-2923-E-007-005, 107-2923-E-007-001, 107-2119-M-002-033, and 1082923-E-036-001-MY3.

Reference (1) An, S. J.; Li, J.; Daniel, C.; Mohanty, D.; Nagpure, S.; Wood III, D. L. The state of understanding of the lithium-ion-battery graphite solid electrolyte interphase (SEI) and its relationship to formation cycling. Carbon 2016, 105, 52-76. (2) Soto, F. A.; Ma, Y.; Martinez de la Hoz, J. M.; Seminario, J. M.; Balbuena, P. B. Formation and growth mechanisms of solid-electrolyte interphase layers in rechargeable batteries. Chem. Mater. 2015, 27 (23), 7990-8000. (3) Haregewoin, A. M.; Wotango, A. S.; Hwang, B.-J. Electrolyte additives for lithium ion battery electrodes: progress and perspectives. Energy Environ. Sci. 2016, 9 (6), 1955-1988. (4) Yang, G.; Shi, J.; Shen, C.; Wang, S.; Xia, L.; Hu, H.; Luo, H.; Xia, Y.; Liu, Z. Improving the cyclability performance of lithium-ion batteries by introducing lithium difluorophosphate (LiPO2F2) additive. RSC Adv. 2017, 7 (42), 26052-26059. 24 ACS Paragon Plus Environment

Page 24 of 46

Page 25 of 46 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(5) Lithium-Ion Batteries: Advanced Materials and Technologies; Yuan, X., Liu, H., Zhang, J.; 1st ed. CRC press, USA, 2011. (6) Xia, L.; Lee, S.; Jiang, Y.; Xia, Y.; Chen, G. Z.; Liu, Z. Fluorinated electrolytes for li-ion batteries: the lithium difluoro (oxalato) borate additive for stabilizing the solid electrolyte interphase. ACS Omega 2017, 2 (12), 8741-8750. (7) Ren, Y.; Wang, M.; Wang, J.; Cui, Y. Tris (trimethylsilyl) Phosphate as Electrolyte Additive for Lithium‐Ion Batteries with Graphite Anode at Elevated Temperature. Int. J. Electrochem. Sci. 2018, 13 (1), 664-674. (8) Liu, K.; Liu, Y.; Lin, D.; Pei, A.; Cui, Y. Materials for lithium-ion battery safety. Sci. Adv. 2018, 4 (6), eaas9820. (9) Li, J.; Li, H.; Stone, W.; Glazier, S.; Dahn, J. Development of Electrolytes for Single Crystal NMC532/Artificial Graphite Cells with Long Lifetime. J. Electrochem. Soc. 2018, 165 (3), A626-A635. (10) Wang, A.; Kadam, S.; Li, H.; Shi, S.; Qi, Y. Review on modeling of the anode solid electrolyte interphase (SEI) for lithium-ion batteries. npj Comput. Mater. 2018, 4 (1), 15. (11) Gauthier, M.; Carney, T. J.; Grimaud, A.; Giordano, L.; Pour, N.; Chang, H.-H.; Fenning, D. P.; Lux, S. F.; Paschos, O.; Bauer, C. Electrode–electrolyte interface in Liion batteries: Current understanding and new insights. J. Phys. Chem. Lett. 2015, 6 (22), 4653-4672. (12) Okamoto, Y.; Kubo, Y. Ab Initio Calculations of the Redox Potentials of Additives for Lithium-Ion Batteries and Their Prediction through Machine Learning. ACS Omega 2018, 3 (7), 7868-7874. (13) Zhang, S.; Xu, K.; Jow, T. EIS study on the formation of solid electrolyte interface in Li-ion battery. Electrochim. Acta 2006, 51 (8-9), 1636-1640.



(14) Aurbach, D.; Ein‐Eli, Y. The study of Li‐graphite intercalation processes in several electrolyte systems using in situ X‐ray diffraction. J. Electrochem. Soc. 1995, 142 (6), 1746-1752. (15) Ein‐Eli, Y.; McDevitt, S. F.; Aurbach, D.; Markovsky, B.; Schechter, A. Methyl Propyl Carbonate: A Promising Single Solvent for Li‐Ion Battery Electrolytes. J. Electrochem. Soc. 1997, 144 (7), L180-L184. (16) Aurbach, D.; Markovsky, B.; Weissman, I.; Levi, E.; Ein-Eli, Y. On the correlation between surface chemistry and performance of graphite negative electrodes for Li ion batteries. Electrochim. Acta 1999, 45 (1-2), 67-86. (17) Benitez, L.; Seminario, J. M. Ion diffusivity through the solid electrolyte interphase in lithium-ion batteries. J. Electrochem. Soc. 2017, 164 (11), E3159-E3170. (18) Kuwata, H.; Sonoki, H.; Matsui, M.; Matsuda, Y.; Imanishi, N. Surface Layer and Morphology of Lithium Metal Electrodes. Electrochemistry 2016, 84 (11), 854-860. (19) Nie, M.; Chalasani, D.; Abraham, D. P.; Chen, Y.; Bose, A.; Lucht, B. L. Lithium ion battery graphite solid electrolyte interphase revealed by microscopy and spectroscopy. J. Phys. Chem. C 2013, 117 (3), 1257-1267. (20) Ming, J.; Cao, Z.; Wahyudi, W.; Li, M.; Kumar, P.; Wu, Y.; Hwang, J.-Y.; Hedhili, M. N.; Cavallo, L.; Sun, Y.-K. New Insights on Graphite Anode Stability in Rechargeable Batteries: Li Ion Coordination Structures Prevail over Solid Electrolyte Interphases. ACS Energy Lett. 2018, 3 (2), 335-340. (21) Shi, Q.; Liu, W.; Qu, Q.; Gao, T.; Wang, Y.; Liu, G.; Battaglia, V. S.; Zheng, H. Robust solid/electrolyte interphase on graphite anode to suppress lithium inventory loss in lithium-ion batteries. Carbon 2017, 111, 291-298. (22) Wang, F. M.; Yu, M. H.; Cheng, C. S.; Pradanawati, S. A.; Lo, S. C.; Rick, J. Phenylenedimaleimide positional isomers used as lithium ion battery electrolyte


Page 26 of 46

Page 27 of 46 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


additives: Relating physical and electrochemical characterization to battery performance. J. Power Sources 2013, 231, 18-22. (23) Gnanaraj, J.; Thompson, R. W.; DiCarlo, J.; Abraham, K. The role of carbonate solvents on lithium intercalation into graphite. J. Electrochem. Soc. 2007, 154 (3), A185-A191. (24) Zheng, X.; Wang, W.; Huang, T.; Fang, G.; Pan, Y.; Wu, M. Evaluation of di (2, 2, 2-trifluoroethyl) sulfite as a film-forming additive on the MCMB anode of lithiumion batteries. J. Power Sources 2016, 329, 450-455. (25) Ma, L.; Ellis, L.; Glazier, S.; Ma, X.; Dahn, J. Combinations of LiPO2F2 and Other Electrolyte Additives in Li[Ni0.5Mn0.3Co0.2]O2/Graphite Pouch Cells. J. The Electrochem. Soc. 2018, 165 (9), A1718-A1724. (26) Jeong, S.-K.; Inaba, M.; Mogi, R.; Iriyama, Y.; Abe, T.; Ogumi, Z. Surface film formation on a graphite negative electrode in lithium-ion batteries: atomic force microscopy study on the effects of film-forming additives in propylene carbonate solutions. Langmuir 2001, 17 (26), 8281-8286. (27) Ryou, M.-H.; Han, G.-B.; Lee, Y. M.; Lee, J.-N.; Lee, D. J.; Yoon, Y. O.; Park, J.K. Effect of fluoroethylene carbonate on high temperature capacity retention of LiMn2O4/graphite Li-ion cells. Electrochim. Acta 2010, 55 (6), 2073-2077. (28) Tsubouchi, S.; Domi, Y.; Doi, T.; Ochida, M.; Nakagawa, H.; Yamanaka, T.; Abe, T.; Ogumi, Z. Spectroscopic characterization of surface films formed on edge plane graphite in ethylene carbonate-based electrolytes containing film-forming additives. J. Electrochem. Soc. 2012, 159 (11), A1786-A1790. (29) Liao, L.; Zuo, P.; Ma, Y.; An, Y.; Yin, G.; Gao, Y. Effects of fluoroethylene carbonate on low temperature performance of mesocarbon microbeads anode. Electrochim. Acta 2012, 74, 260-266.



(30) Jung, R.; Metzger, M.; Haering, D.; Solchenbach, S.; Marino, C.; Tsiouvaras, N.; Stinner, C.; Gasteiger, H. A. Consumption of fluoroethylene carbonate (FEC) on Si-C composite electrodes for Li-ion batteries. J. Electrochem. Soc. 2016, 163 (8), A1705A1716. (31) Jin, Y.; Kneusels, N.-J. H.; Marbella, L. E.; Castillo-Martínez, E.; Magusin, P. C.; Weatherup, R. S.; Jonsson, E.; Liu, T.; Paul, S.; Grey, C. P. Understanding Fluoroethylene Carbonate and Vinylene Carbonate Based Electrolytes for Si Anodes in Lithium Ion Batteries with NMR Spectroscopy. J. Am. Chem. Soc. 2018, 140 (31), 9854-9867. (32) Michan, A. L.; Parimalam, B. S.; Leskes, M.; Kerber, R. N.; Yoon, T.; Grey, C. P.; Lucht, B. L. Fluoroethylene carbonate and vinylene carbonate reduction: Understanding lithium-ion battery electrolyte additives and solid electrolyte interphase formation. Chem. Mater. 2016, 28 (22), 8149-8159. (33) Markevich, E.; Salitra, G.; Aurbach, D. Fluoroethylene carbonate as an important component for the formation of an effective solid electrolyte interphase on anodes and cathodes for advanced Li-ion batteries. ACS Energy Lett. 2017, 2 (6), 1337-1345. (34) Philippe, B.; Hahlin, M.; Edström, K.; Gustafsson, T.; Siegbahn, H.; Rensmo, H. Photoelectron spectroscopy for lithium battery interface studies. J. Electrochem. Soc. 2016, 163 (2), A178-A191. (35) Winkler, V.; Hanemann, T.; Bruns, M. Comparative surface analysis study of the solid electrolyte interphase formation on graphite anodes in lithium‐ion batteries depending on the electrolyte composition. Surf. Interface Anal. 2017, 49 (5), 361-369. (36) Shi, Q.; Heng, S.; Qu, Q.; Gao, T.; Liu, W.; Hang, L.; Zheng, H. Constructing an elastic solid electrolyte interphase on graphite: a novel strategy suppressing lithium inventory loss in lithium-ion batteries. J. Mater. Chem. A 2017, 5 (22), 10885-10894.


Page 28 of 46

Page 29 of 46 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(37) Wang, F. M.; Cheng, H. M.; Wu, H. C.; Chu, S. Y.; Cheng, C. S.; Yang, C. R. Novel SEI formation of maleimide-based additives and its improvement of capability and cyclicability in lithium ion batteries. Electrochim. Acta 2009, 54 (12), 3344-3351. (38) Hamidah, N. L.; Nugroho, G.; Wang, F. M. Electrochemical analysis of electrolyte additive effect on ionic diffusion for high-performance lithium ion battery. Ionics 2016, 22 (1), 33-41. (39) Li, Y. H.; Lee, M. L.; Wang, F. M.; Yang, C. R.; Chu, P. P.; Pan, J. P. Electrochemical characterization of a branched oligomer as a high-temperature and long-cycle-life additive for lithium-ion batteries. Electrochim. Acta 2012, 85, 72-77. (40) Wang, F. M.; Shieh, D. T.; Cheng, J. H.; Yang, C. R. An investigation of the salt dissociation effects on solid electrolyte interface (SEI) formation using linear carbonate-based electrolytes in lithium ion batteries. Solid State Ionics 2010, 180 (40), 1660-1666. (41) Zhuang, G. V.; Yang, H.; Blizanac, B.; Ross, P. N. A study of electrochemical reduction of ethylene and propylene carbonate electrolytes on graphite using ATRFTIR spectroscopy. Electrochem. Solid-State Lett. 2005, 8 (9), A441-A445. (42) Haregewoin, A. M.; Leggesse, E. G.; Jiang, J. C.; Wang, F. M.; Hwang, B. J.; Lin, S. D. Comparative study on the solid electrolyte interface formation by the reduction of alkyl carbonates in lithium ion battery. Electrochim. Acta 2014, 136, 274-285. (43) Chernyak, Y. Dielectric constant, dipole moment, and solubility parameters of some cyclic acid esters. J. Chem. Eng. Data 2006, 51 (2), 416-418. (44) Westerhoff, U.; Kurbach, K.; Lienesch, F.; Kurrat, M. Analysis of Lithium‐Ion Battery Models Based on Electrochemical Impedance Spectroscopy. Energy Technol. 2016, 4 (12), 1620-1630.



(45) Shkrob, I. A.; Zhu, Y.; Marin, T. W.; Abraham, D. Reduction of carbonate electrolytes and the formation of solid-electrolyte interface (SEI) in lithium-ion batteries. 1. Spectroscopic observations of radical intermediates generated in oneelectron reduction of carbonates. J. Phys. Chem. C 2013, 117 (38), 19255-19269. (46) Shkrob, I. A.; Zhu, Y.; Marin, T. W.; Abraham, D. Reduction of carbonate electrolytes and the formation of solid-electrolyte interface (SEI) in Lithium-Ion Batteries. 2. Radiolytically induced polymerization of ethylene carbonate. J. Phys. Chem. C 2013, 117 (38), 19270-19279. (47) Haregewoin, A. M.; Leggesse E. G.; Jiang, J. C.; Wang, F. M.; Hwang, B. J.; Lin, S. D. Comparative Study on the Solid Electrolyte Interface Formation by the Reduction of Alkyl Carbonates in Lithium ion Battery, Electrochim. Acta 2014, 136, 274-285. (48) Haregewoin, A. M.; Leggesse E. G.; Jiang, J. C.; Wang, F. M.; Hwang, B. J.; Lin, S. D. A combined experimental and theoretical study of surface film formation: Effect of oxygen on the reduction mechanism of propylene carbonate, J. Power Sources 2013, 244, 318-327. (49) Spectrometric Identification of Organic Compounds; Silverstein, R. M., Webster, F. X., Kiemle, D. J.; 8th ed. John Wiley & Sons, USA, 2014. (50) Shen, G.; Anand, M. F.;G.; Levicky, R. X-ray photoelectron spectroscopy and infrared spectroscopy study of maleimide-activated supports for immobilization of oligodeoxyribonucleotides, Nucleic Acids Res. 2004, 32, 5973-5980. (51) Ikezawa, Y.; Ariga, T. In situ FTIR spectra at the Cu electrode/propylene carbonate solution interface, Electrochim. Acta 2007, 52, 2710-2715. (52) Aurbach, D.; Daroux, M. L.; Faguy, P. W.; Yeager, E. Identification of Surface Films Formed on Lithium in Propylene Carbonate Solutions, J. Electrochem. Soc. 1987, 134, 1611-1620.


Page 30 of 46

Page 31 of 46 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(53) Cheng, Y.; Wang, G.; Yan, M.; Jiang, Z. In situ analysis of interfacial reactions between negative MCMB, lithium electrodes, and gel polymer electrolyte, J. Solid State Electrochem. 2007, 11, 310-316. (54) Aurbach, D.; Chusid, O. In situ FTIR Spectroelectrochemical Studies of Surface Films Formed on Li and Nonactive Electrodes at Low Potentials in Li Salt Solutions Containing CO2, J. Electrochem. Soc. 1993, 140, L155-L157. (55) Pyun, S. In-situ spectroelectrochemical analysis of the passivating surface film formed on a carbon film electrode as a function of the water content in 1 M LiPF6EC/DEC solution, Fresenius' J. Anal. Chem. 1999, 363, 38-45. (56) Bar‐Tow, D.; Peled, E.; Burstein, L. A study of highly oriented pyrolytic graphite as a model for the graphite anode in Li‐Ion batteries. J. Electrochem. Soc. 1999, 146 (3), 824-832. (57) Światowska, J.; Lair, V.; Pereira-Nabais, C.; Cote, G.; Marcus, P.; Chagnes, A. XPS, XRD and SEM characterization of a thin ceria layer deposited onto graphite electrode for application in lithium-ion batteries. Appl. Surf. Sci. 2011, 257 (21), 91109119. (58) Schechter, A.; Aurbach, D.; Cohen, H. X-ray photoelectron spectroscopy study of surface films formed on Li electrodes freshly prepared in alkyl carbonate solutions. Langmuir 1999, 15 (9), 3334-3342. (59) Cheng, C. S.; Liu, W. R.; Wang, F. M. A novel ionic host solid electrolyte interface formation on reduced graphene oxide of lithium ion battery. Electrochim. Acta 2013, 106, 425-431. (60) Anderson, A. M.; Henningson, A.; Siegbahn, H.; Jansson, U.; Edstrom, K. Electrochemically lithiate graphite characterised by photoelectron spectroscopy. J. Power Sources 2003, 119-121, 522-527.



(61) Bryngelsson, H.; Stjerndahl, M.; Gustafsson, T.; Edstrom, K. How dynamic is the SEI? J. Power Sources 2007, 174, 970-975. (62) Lu, M.; Cheng, H.; Yang, Y. A comparsion of solid electrolyte interphse (SEI) on the artificial anode of the aged and cycled commercial lithiu ion cells. Electrochim. Acta 2008, 53, 3539. (63) Morigaki, K. I.; Ohta, A. Analysis of the surface of lithium in organic electrolyte by atomic force microscopy, Fourier transform infrared spectroscopy and scanning auger electron microscopy. J. Power Sources 1998, 76 (2), 159-166. (64) Edström, K.; Herstedt, M.; Abraham, D. P. A new look at the solid electrolyte interphase on graphite anodes in Li-ion batteries. J. Power Sources 2006, 153 (2), 380384. (65) Wang, F. M.; Yu, M. H.; Hsiao, Y. J.; Tsai, Y.; Hwang, B. J.; Wang, Y. Y.; Wan, C. C. Aging effects to solid electrolyte interface (SEI) membrane formation and the performance analysis of lithium ion batteries. Int. J. Electrochem. Sci 2011, 6, 10141026. (66) Zhu, Y.; Casselman, M. D.; Li, Y.; Wei, A.; Abraham, D. P. Perfluoroalkylsubstituted ethylene carbonates: novel electrolyte additives for high-voltage lithiumion batteries. J. Power Sources 2014, 246, 184-191. (67) Sina, M.; Thorpe, R.; Rangan, S.; Pereira, N.; Bartynski, R. A.; Amatucci, G. G.; Cosandey, F. Investigation of SEI layer formation in conversion iron fluoride cathodes by combined STEM/EELS and XPS. J. Phys. Chem. C 2015, 119 (18), 9762-9773. (68) Cheng, C. S.; Wang, F. M.; Rick, J. Aqueous additive for lithium ion batteries: promotes novel solid electrolyte interface (SEI) layer with overall cost reduction. Int. J. Electrochem. Sci 2012, 7, 8676-8687.


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(69) Verma, P.; Maire, P.; Novák, P. A review of the features and analyses of the solid electrolyte interphase in Li-ion batteries. Electrochimica Acta 2010, 55 (22), 6332-6341. (70) Zhang, S. S. A review on electrolyte additives for lithium-ion batteries. J. Power Sources 2006, 162 (2), 1379-1394. (71) Giorgini, M. G.; Futamatagawa, K.; Torii, H.; Musso, M.; Cerini, S. Solvation structure around the Li+ ion in mixed cyclic/linear carbonate solutions unveiled by the Raman noncoincidence effect. J. Phys. Chem. Lett. 2015, 6 (16), 3296-3302. (72) Seo, D. M.; Chalasani, D.; Parimalam, B. S.; Kadam, R.; Nie, M.; Lucht, B. L. Reduction reactions of carbonate solvents for lithium ion batteries. ECS Electrochem. Lett. 2014, 3 (9), A91-A93. (73) Yun, J. H.; Park, S.; Heo, J. H.; Lee, H.-S.; Yoon, S.; Kang, J.; Im, S. H.; Kim, H.; Lee, W.; Kim, B. Enhancement of charge transport properties of small molecule semiconductors by controlling fluorine substitution and effects on photovoltaic properties of organic solar cells and perovskite solar cells. Chem. Sci. 2016, 7 (11), 6649-6661. (74) Pople, J. A.; Gordon, M. Molecular orbital theory of the electronic structure of organic compounds. I. Substituent effects and dipole moments. J. Am. Chem. Soc. 1967, 89 (17), 4253-4261. (75) Leskes, M.; Kim, G.; Liu, T.; Michan, A. L.; Aussenac, F.; Dorffer, P.; Paul, S.; Grey, C. P. Surface-sensitive NMR detection of the solid electrolyte interphase layer on reduced graphene oxide. J. Phys. Chem. Lett. 2017, 8 (5), 1078-1085. (76) Gireaud, L.; Grugeon, S.; Laruelle, S.; Pilard, S.; Tarascon, J.-M. Identification of Li

battery

electrolyte

degradation

products

through

direct

synthesis

and

characterization of alkyl carbonate salts. J. Electrochem. Soc. 2005, 152 (5), A850A857.



(77) Liu, Y. M.; G. Nicolau, B.; Esbenshade, J. L.; Gewirth, A. A. Characterization of the Cathode Electrolyte Interface in Lithium Ion Batteries by Desorption Electrospray Ionization Mass Spectrometry. Anal. Chem. 2016, 88 (14), 7171-7177. (78) Nowak, S.; Winter, M. The Role of Cations on the Performance of Lithium Ion Batteries: A Quantitative Analytical Approach. Acc. Chem. Res. 2018, 51 (2), 265-272.

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The dipole moment of the electrolyte additive plays a critical role in SEI formation, which tends to dominate the cyclic lifespan of battery performance.


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Investigation of the Dipole Moment Effects of Fluorofunctionalized

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