Propylene Carbonate-based Electrolyte Research Articles

Dual Functional Propylene Carbonate Co-Solvent for High Performance Aqueous Zinc-Ion Batteries

In response to the global rise in energy demand, extensive research has spurred the development of batteries with high energy density, affordable cost, and safety. The present Li-ion batteries are attractive due to their high energy density, but their cost and geopolitical accessibility of raw materials, along with safety-related issues, have led researchers to shift their attention towards aqueous batteries.1,2 In aqueous systems, zinc metal has been regarded as the most promising candidate due to its high specific capacity, low redox potential of Zn-metal, environmental friendliness, and low cost. However, challenges such as the dendritic growth of zinc, hydrogen evolution, corrosion, structural degradation and dissolution of oxide cathodes, and poor coulombic efficiencies (CEs) limit their scope. To address these issues, various studies demonstrate the usage of organic co-solvents and additives such as DMSO3, DMC4, etc. at different concentrations in the electrolytes. However, the overall efficiency of the battery performance is hindered due to the large amount requirements of these additives.Along this line, we have studied the electrochemical properties of a hybrid water-highly polar propylene carbonate-based electrolyte, which suppresses water-derived parasitic reactions occurring at both the Zn anode and the V2O5 cathode.5 We have observed a significant enhancement in the battery characteristics, such as high coulombic efficiency and stable capacity, merely by tuning the solvation structure of the electrolyte. Upon a small addition of PC (20 wt.%) in 1M Zn(OTf)2 electrolyte, water molecules solvating Zn2+ ions are replaced by carbonate and triflate anions. The solvated Zn-ion species were further electrochemically reduced to form a ZnF2-rich solid electrolyte interphase (SEI), as demonstrated by post-cycling XPS studies. Moreover, the spectroscopy studies suggest the strong interaction of highly basic carbonyl oxygen of PC with water molecules, which in turn suppresses the dissolution of the cathode, enabling exceptional capacities of ∼300 mAh g−1 over 900 cycles at 1 A g−1. We further demonstrate the significance of the dielectric constant and polarity of an additive or cosolvent in the aqueous zinc ion battery electrolyte by contrasting the performance of cyclic propylene carbonate with acyclic dimethyl carbonate.Reference O. Schmidt, A. Hawkes, A. Gambhir, and I. Staffell, Nature Energy, 2, 1–8 (2017)M. M. Thackeray, C. Wolverton, and E. D. Isaacs, Energy Environ. Sci., 5, 7854–7863 (2012)L. Cao ,D. Li, E. Hu, J. Xu, T. Deng, L. Ma, Y. Wang, X. Q. Yang, and C. Wang, J. Am. Chem. Soc., 142, 21404–21409 (2020)Y. Dong, L. Miao, G. Ma, S. Di, Y. Wang, L. Wang, J. Xua, and N. Zhang, Chem. Sci., 12, 5843–5852 (2021)B. Kakoty, R. Vengarathody, S. Mukherji, V. Ahuja, A. Joseph, C. Narayana, S. Balasubramanian, and P. Senguttuvan, J. Mater. Chem. A, 10, 12597–12607 (2022)

Rejuvenating propylene carbonate-based electrolytes by regulating the coordinated structure toward all-climate potassium-ion batteries

In this work, we designed PC-based electrolytes rich in AGGs and CIPs, forming a robust and KF-rich SEI interface and enabling a low desolvation barrier, further alleviating various challenges at all-climate temperatures of PIBs.

Unveiling the molecular mechanism of 1,3,2-dioxathiolane 2,2-dioxide in a propylene carbonate-based battery electrolyte

Propylene carbonate (PC)-based electrolytes are gaining attention as next-generation electrolytes for use in high-voltage and high-temperature environments due to their superior stability at high voltages and their wide operating temperature range. However, commercialization is challenged by the exfoliation of the graphite anode, which is caused by the co-intercalation of PC. Various additives have been devised to address this issue. 1,3,2-dioxathiolane 2,2-dioxide (DTD) exhibits outstanding capacity retention and lifespan characteristics in lithium-ion batteries in which PC-based electrolytes are used, but a molecular-level understanding of its operating mechanism remains elusive. According to our quantum static and dynamics calculations, the Li+ binding energy of DTD is much lower than that of PC, rendering its coordination ability insufficient to compete with PC. As a result, the neutral DTD does not play a role in favoring the desolvation of PC from the solvation structure. However, DTD is reduced prior to PC and shows a strong reduction tendency accompanied by ring-opening. Based on this, DTD in its anionic form participates in the Li+ solvation sheath through a solvent–additive exchange reaction to promote the desolvation of PC. We reveal that the use of the charges of the oxygen atoms bonded to Li+ ions to interpret the Li+–solvent binding energies is inappropriate. Instead, we suggest the electrostatic potential minimum (ESPMin) as a useful and powerful descriptor. This work provides insights into the molecular characteristics and mechanisms of additives that enable PC-based electrolytes, offering guidance for the development of new additives.

Exploring SEI Characteristics in Propylene Carbonate-Based Electrolyte with 2-Isocyanatoethyl Methacrylate at Graphite Electrode

Propylene carbonate (PC) has the advantage of a much lower melting point than ethylene carbonate (EC), but it cannot suppress the exfoliation of graphite layers because of its cointercalation with Li+ before forming a stable solid electrolyte interface (SEI). This paper introduces 2−isocyanatoethyl methacrylate (ICEMA) as an additive in PC−based electrolytes. ICEMA is a bifunctional monomer in which the isocyanate group is linked by the ethyl group to the acrylate group, which reacts through thermal polymerization. The isocyanate moiety is initiated as a radical during the initial charging process to induce electropolymerization and reaction with the PC radical. Radicals propagate through the entire reaction at the electrode to form a stable SEI. The modified interface suppresses the cointercalation of Li+−PC to graphite electrode. In situ Fourier transform infrared effectively showed the polymerization of the isocyanate and active reaction with the PC radical. Consequently, the reaction mechanisms to form the stable SEI in PC−based electrolytes were determined.

Boosting reversible charging of Li-ion batteries at low temperatures by a synergy of propylene carbonate-based electrolyte and defective graphite

Boosting reversible charging of Li-ion batteries at low temperatures by a synergy of propylene carbonate-based electrolyte and defective graphite

Benzochalcodiazole-based donor-acceptor-donor non-symmetric small molecules as dual-functioning electrochromic and electrofluorochromic materials

Bifunctional fluorescent donor-π-acceptor-donor molecules based on the benzoxadiazole (1) or benzothiadiazole (2) have been synthesized and characterized and the effect of chalcogen atom (oxygen vs. sulfur) was investigated. Both dyes exhibited dependence of both emission maxima and fluorescence quantum yield on the solvent polarity. The dyes were found to undergo an electropolymerization reaction when an electrochemical process was carried out in dichloromethane-based electrolyte and no electropolymerization was observed when propylene carbonate-based electrolyte was used. In the propylene-carbonate based electrolyte the fluorophores could be reversibly oxidized with the distinct color change from orange to green in case of 1 and yellow to green for compound 2 and the fluorescence was found to be quenched after electrooxidation. Both color change and quenching of luminescence were found to be reversible. The visible color, strong luminescence in the solid state and electroactivity of the dyes were ideal properties for dual electrochromic and electrofluorochromic applications. The constructed dual-functioning electrochromic and electrofluorochromic device could operate for upwards of 6 h in electrochromic mode, and upwards of 100 min in electrofluorochromic mode. The polymers obtained via electropolymerization were found to exhibit different properties in comparison to monomers.

Theoretical Prediction of Freezing Point Depression of Lithium-Ion Battery Electrolytes

Understanding and predicting the freezing point depression of liquid electrolytes is of interest particularly for low-temperature battery applications. We will present a computational methodology to calculate activity coefficients and the freezing point depression of liquid electrolytes relevant to Li-ion batteries. Theoretical expressions for Born solvation, Debye-Huckel ion atmosphere effects and solvent entropy are used with results from classical molecular dynamics simulations and electronic structure methods to calculate the activity coefficients of liquid electrolytes. Using the calculated activity coefficients as well as neat solvent properties, liquidus lines of the studied electrolytes are obtained up to 1 molal. The liquid electrolytes studied include LiPF6 in dimethyl carbonate and LiPF6 in propylene carbonate. It is found that the more significant freezing point depression of the propylene carbonate-based electrolyte versus dimethyl carbonate-based electrolyte originates in large part from the much higher dielectric constant of propylene carbonate versus dimethyl carbonate.

Additives to propylene carbonate-based electrolytes for lithium-ion capacitors

Additives to propylene carbonate-based electrolytes for lithium-ion capacitors

A Theoretical Model for Computing Freezing Point Depression of Lithium-Ion Battery Electrolytes

Reliable prediction of freezing point depression in liquid electrolytes will accelerate the development of improved Li-ion batteries which can operate in low temperature environments. In this work we establish a computational methodology to calculate activity coefficients and liquidus lines for battery-relevant liquid electrolytes. Electronic structure methods are used in conjuction with classical molecular dynamics simulations and theoretical expressions for Born solvation energy, ion-atmosphere effects from Debye-Hückel theory and solvent entropic effects. The framework uses no a priori knowledge beyond neat solvent properties and the concentration of salt. LiPF6 in propylene carbonate (PC), LiPF6 in dimethyl carbonate (DMC) and LiClO4 in DMC are investigated up to 1 molal with accuracy better than 3 °C when compared to experimental freezing point measurements. We find that the difference in freezing point depression between the propylene carbonate-based electrolyte and the dimethyl carbonate electrolytes originates from the difference in the solvent dielectric constant.

High-Mass Loading Hierarchically Porous Activated Carbon Electrode for Pouch-Type Supercapacitors with Propylene Carbonate-Based Electrolyte.

Rational design and development of the electrodes with high-mass loading yet maintaining the excellent electrochemical properties are significant for a variety of electrochemical energy storage applications. In comparison with the slurry-casted electrode, herein, a hierarchically porous activated carbon (HPAC) electrode with higher mass loading (8.3 ± 0.2 mg/cm2) is successfully prepared. The pouch-type symmetric device (1 cell) with the propylene carbonate-based electrolyte shows the rate capability (7.1 F at 1 mA/cm2 and 4.8 F at 10 mA/cm2) and the cycling stability (83% at 12,000 cycles). On the other hand, an initial discharge capacitance of 32.4 F and the capacitance retention of 96% after 30,000 cycles are delivered from a pouch-type symmetric supercapacitor (five cells). The corresponding electrochemical performances are attributed to the fascinating properties of the HPAC and the synergistic features of the resulting electrode.

The compatibility of propylene carbonate-based electrolyte solutions with graphite negative electrodes in lithium-ion batteries

The compatibility of propylene carbonate-based electrolyte solutions with graphite negative electrodes in lithium-ion batteries

Robust Solid-Electrolyte Interphase Enables Near-Theoretical Capacity of Graphite Battery Anode at 0.2 C in Propylene Carbonate-Based Electrolyte.

The formation of a robust solid-electrolyte interphase (SEI) layer at the surface of a graphite anode by electrolyte control is a key technology for high-performance lithium-ion batteries. Although propylene carbonate (PC) offers a lower melting point than ethylene carbonate, its combination with the graphite anode without additive is a worse choice, owing to co-intercalation of PC and Li+ ion into graphite, exfoliation of graphene sheets, and death of the battery. This study reports a graphite anode with an unprecedentedly high initial coulombic efficiency of 94 %, close to theoretical capacity, and excellent capacity retention of 99 % after 100 cycles in a PC-based electrolyte system, even at an unusually high rate of 0.2 C, which is generally attainable only at a very low rate of below 0.05 C in commercial electrolyte. The SEI stabilization for a graphite anode in PC-based electrolyte provides a new avenue for high-energy and high-performance batteries in widened range of working temperatures. A strong correlation between anode-electrolyte interfacial stabilization and highly reversible cycling performance is clearly demonstrated.

Understanding the Surface Film Formation on Si Electrodes in Lithium Secondary Batteries with Atomic Force Microscopy.

The solid electrolyte interphase formation on the negative electrodes of lithium secondary batteries has been considered as one of the principal issues limiting the performance of batteries. Si is an attractive electrode material for improving energy density of lithium secondary batteries because of its high specific theoretical capacity (4200 mAh g-1). However, solid electrolyte interphase formation on Si-based electrodes have not been clearly understood in spite of its significance. Herein, the solid electrolyte interphase formation on Si electrodes in electrolyte solutions containing ethylene carbonate or propylene carbonate was investigated by using in-situ atomic force microscopy. Large and irreversible capacity fade in SiO electrodes was confirmed in both electrolyte solutions through cyclic voltammetry and charge/discharge testing. The in-situ atomic force microscopy results indicated that the decomposition reaction occurred in the ethylene carbonate-based electrolyte solution at a potential of ~0.68 V, while the lithium alloying reaction occurred below 0.25 V during the first reduction process. The decomposition reaction was more vigorous and occurred at a higher potential in the propylene carbonate-based electrolyte solution, resulting in the formation of a thick solid electrolyte interphase film. These results suggest that the solid electrolyte interphase formation on Si electrodes is strongly influenced by the composition of the electrolyte solution.

Cellulose-Multiwall Carbon Nanotube Fiber Actuator Behavior in Aqueous and Organic Electrolyte.

As both consumers and producers are shifting from fossil-derived materials to other, more sustainable approaches, there is a growing interest in bio-origin and biodegradable polymers. In search of bio-degradable electro-mechanically active materials, cellulose-multi wall carbon nanotube (Cell-CNT) composites are a focus for the development of actuators and sensors. In the current study, our aim was to fabricate Cell-CNT composite fibers and study their electro-mechanical response as linear actuators in aqueous and propylene carbonate-based electrolyte solutions. While the response was (expectedly) strongly solvent dependent, the different solvents also revealed unexpected phenomena. Cell-CNT fibers in propylene carbonate revealed a strong back-relaxation process at low frequencies, and also a frequency dependent response direction change (change of actuation direction). Cell-CNT fibers operated in aqueous electrolyte showed response typical to electrochemical capacitors including expansion at discharging with controllable actuation dependence on charge density. While the response was similarly stable in both electrolyte solution systems, the aqueous electrolytes were clearly favorable for Cell-CNT with 3.4 times higher conductivities, 4.3 times higher charge densities and 11 times higher strain.

Effect of PAMAM Dendrimers on Interactions and Transport of LiTFSI and NaTFSI in Propylene Carbonate-Based Electrolytes.

Poly(amidoamine) (PAMAM)-based electrolytes are prepared by dissolving the PAMAM half-generations G1.5 or G2.5 in propylene carbonate (PC), either with lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) or sodium bis(trifluoromethylsulfonyl)imide (NaTFSI) salts. The solutions, designed for ion battery applications, are studied in terms of ions transport properties. Raman Spectroscopy reveals information about the interactions between cations and PAMAM dendrimers as well as full dissociation of the salts in all solutions. Pulsed-field gradient Nuclear Magnetic Resonance (PFG NMR), measured as a function of both temperature and PAMAM concentration, are obtained for the cation, anion, solvent, and dendrimer molecules using lithium (7Li), sodium (23Na), fluorine (19F), and hydrogen (1H) NMR, respectively. It was found that lithium diffusion is slow compared to the larger TFSI anion and decreases with PAMAM concentration due to interactions between cation and dendrimer. Comparison of conductivities calculated from diffusion coefficients using the Nernst–Einstein equation, with conductivity measurements obtained from Impedance Spectroscopy (IS), shows slightly higher IS conductivities, caused among others by PAMAM conductivity.

Hybrid Ionic Liquid Propylene Carbonate-Based Electrolytes for Aluminum–Air Batteries

This study reports on the use of tetrabutylammonium dihydrogen trifluoride (TBAH2F3) ionic liquid-based electrolytes in the aluminum (Al)–air battery system. The conductivity and activation energy ...

Acyclic Acetals in Propylene Carbonate-Based Electrolytes for Advanced and Safer Graphite-Based Lithium Ion Batteries

In this work, we investigate the electrochemical and safety performance of the glyoxalic acyclic acetals, namely 1,1,2,2-tetramethoxyethane (TME) and 1,1,2,2 tetraethoxyethane (TEE) as substituted solvents for linear organic carbonates in propylene carbonate (PC)-based electrolytes in LiNi0.6Mn0.2Co0.2O2∣∣graphite cells. By means of conductivity measurements and under consideration of PC-intercalation suppression, an optimized electrolyte was formulated with excellent thermal properties and electrochemical performance. The optimized electrolyte shows excellent cycling performance at the level of established organic carbonate-based electrolyte consisted ethylene carbonate, ethyl methyl carbonate and with lithium hexafluorophosphate as conducting salt with an extended operating cycling temperature window, good C-rate behavior and promising safety properties, clearly demonstrating the application potential of this new solvent class for lithium ion battery electrolytes.

Governing Role of Solvent on Discharge Activity in Lithium-CO2 Batteries.

Non-aqueous Li-CO2 batteries reported in literature have almost exclusively relied upon glyme-based electrolytes, leading to a hypothesis that they are uniquely active for CO2 discharge. Here, we study the effect of electrolyte composition on CO2 activity to examine whether this is the case. The results indicate that TEGDME-based electrolytes containing moderate concentrations of Li+ salts (roughly within the range of 0.7-2 M examined herein) are most conducive to CO2 activation, especially compared to dimethyl sulfoxide and propylene carbonate-based electrolytes. Through electrochemical, spectroscopic, and computational methods, we determine that glymes have lower desolvation energies for Li+compared toother solvent candidates, whereas high salt concentrations increase the local density of Li+ surrounding CO2 and reduction intermediates. These attributes collectively increase the availability of Li+, crossing a threshold necessary to support CO2 activation. Discharge voltage and reaction rates are also sensitive to the alkali cationidentity, further invoking its key role in enabling or suppressing reactivity.

Tetrahydrothiophene 1-oxide as highly effective co-solvent for propylene carbonate-based electrolytes

Propylene carbonate (PC) together with cyclic sulfur compounds such as tetrahydrothiophene 1-oxide (THT1oxide) as co-solvent and lithium hexafluorophosphate (LiPF6) as conducting salt are introduced as new aprotic liquid electrolytes for lithium-ion batteries. Starting with the single solvent electrolyte LiPF6 in PC, by addition of THT1oxide, the ion transport properties even at temperatures down to −20 °C are improved by the different solvation behavior of Li+ ions due to the high Li+ ion affinity of the sulfinyl (-S=O) group and by the resulting decrease of the Li+ ion complex size. Electrolytes that contain Li+ ion complexes with both PC and THT1oxide molecules in the solvation shell are able to form protective interphase layers on graphite and NCM111 (LiNi1/3Co1/3Mn1/3O2) electrodes that are both permeable for Li+ ions while ensuring good electronic insulation, thus enabling stable cycling in lithium-ion cells with only minor capacity fading. THT1oxide/PC-based electrolytes afford better long-term as well as low temperature cycling behavior compared to established state-of-the-art (SOTA) organic carbonate-based electrolytes. The obtained results allow for the design of new co-solvents for PC and comparable cyclic organic carbonates, and provide a non-toxic and cheap alternative to crown ethers without affecting the Li+ ion transference/transport numbers.

Effect of Counter Anions on Solid Electrolyte Interphase Formation on Graphite Electrodes in Propylene Carbonate-based Electrolyte Solutions

Effect of Counter Anions on Solid Electrolyte Interphase Formation on Graphite Electrodes in Propylene Carbonate-based Electrolyte Solutions