Search Results (18)

Lithium metal batteries (LiMBs) have emerged as extremely viable options for next-generation energy storage owing to their elevated energy density and improved theoretical specific capacity relative to traditional lithium batteries. However, safety concerns, such as the flammability of organic liquid electrolytes, have limited their extensive application. In the present study, we utilize molecular dynamics and Density Functional Theory based simulations to investigate the Li interactions in gel polymer electrolytes (GPEs), composed of a 3D cross-linked polymer matrix combined with two different non-flammable electrolytes: 1 M lithium hexafluorophosphate (LiPF₆) in ethylene carbonate (EC)/dimethyl carbonate (DMC) and 1 M lithium bis(fluorosulfonyl)imide (LiFSI) in trimethyl phosphate (TMP) solvents. The findings derived from radial distribution functions, coordination numbers, and interaction energy calculations indicate that Li⁺ exhibits an affinity with solvent molecules and counter-anions over the functional groups on the polymer matrix, highlighting the preeminent influence of electrolyte components in Li⁺ solvation and transport. Furthermore, the second electrolyte demonstrated enhanced binding energies, implying greater ionic stability and conductivity relative to the first system. These findings offer insights into the Li⁺ transport mechanism at the molecular scale in the GPE by suggesting that lithium-ion transport does not occur by hopping between polymer functional groups but by diffusion into the solvent/counter anion system. The information provided in the work allows for the improvement of the design of electrolytes in LiMBs to augment both safety and efficiency. Full article

With the growing dependence on lithium-ion batteries, there is an urgent need to understand the potential developmental toxicity of LiPF₆, a key component of these batteries. Although lithium’s toxicity is well-established, the biological toxicity of LiPF₆ has been minimally explored. This study leverages the zebrafish model to investigate the developmental impact of LiPF₆ exposure. We observed morphological abnormalities, reduced spontaneous movement, and decreased hatching and swim bladder inflation rates in zebrafish embryos, effects that intensified with higher LiPF₆ concentrations. Whole-mount in situ hybridization demonstrated that the specific expression of the swim bladder outer mesothelium marker anxa5b was suppressed in the swim bladder region under LiPF₆ exposure. Transcriptomic analysis disclosed an upregulation of apoptosis-related gene sets. Acridine orange staining further supported significant induction of apoptosis. These findings underscore the environmental and health risks of LiPF₆ exposure and highlight the necessity for improved waste management strategies for lithium-ion batteries. Full article

Here, the time dependence of the interfacial resistance for Li/polyethylene oxide (PEO)-Li(CF₃SO₂)₂N (LiTFSI)-LiPF₆/LiCoO₂ cells was measured to investigate the stabilization effect of LiPF₆ on the interface between a solid polymer electrolyte (SPE) and a 4-volt class cathode, LiCoO₂. Impedance measurements under the applied potentials between 4.1 V and 4.4 V vs. Li/Li⁺ indicated that the addition of LiPF₆ to LiTFSI was effective in improving the stability at high potentials such as 4.4 V vs. Li/Li⁺. In contrast, the resistance of the non-doped PEO-LiTFSI/LiCoO₂ interface increased with time under the lower potential of 4.1 V vs. Li/Li⁺. Fairly good cycle performance was obtained for the LiPF₆-doped cell, even at a cut-off voltage of 4.5 V vs. Li/Li⁺. Full article

Pyrrolidinium-based (Pyr) ionic liquids (ILs) have been proposed as electrolyte components in lithium-ion batteries (LiBs), mainly due to their higher electrochemical stability and wider electrochemical window. Since they are not naturally electroactive, in order to allow their use in LiBs, it is necessary to mix the ionic liquids with lithium salts (Li). Li–PF6, Li–BF4, and Li–TFSI are among the lithium salts more frequently used in LiBs, and each anion, namely PF6 (hexafluorophosphate), BF4 (tetrafluoroborate), and TFSI (bis(trifluoromethanesulfonyl)azanide), has its own solvation characteristics and interaction profile with the pyrrolidinium ions. The size of Pyr cations, the anion size and symmetry, and cation–anion combinations influence the Li-ion solvation properties. In this work, we used molecular dynamics calculations to achieve a comprehensive view of the role of each cation–anion combination and of different fractions of lithium in the solutions to assess their relative advantage for Li-ion battery applications, by comparing the solvation and structural properties of the systems. This is the most-comprehensive work so far to consider pyrrolidinium-based ILs with different anions and different amounts of Li: from it, we can systematically determine the role of each constituent and its concentration on the structural and dynamic properties of the electrolyte solutions. Full article

Lithium metal batteries are considered a promising technology to implement high energy density rechargeable systems beyond lithium-ion batteries. However, the development of dendritic morphology is the basis of safety and performance issues and represents the main limiting factor for using lithium anodes in commercial rechargeable batteries. In this study, the electrochemical behaviour of Li metal has been investigated in organic carbonate-based electrolytes by electrochemical impedance spectroscopy measurements and deposition/stripping galvanostatic cycling. Low amounts of tetraalkylammonium hexafluorophosphate salts have been added to the electrolytes with the aim of regulating the lithium deposition/stripping process through the electrostatic shielding effect that improves the lithium deposition. The use of NH₄PF₆ also determined good lithium deposition/stripping performance due to the chemical modification of the native solid electrolyte interphase via direct reaction with lithium. Full article

Temperature is a crucial factor for the safe operation of lithium-ion batteries. During operation, the internal temperature rises above the external temperature due to poor inner thermal conductivity. Various sensors have been proposed to detect the internal temperature, including fiber Bragg grating sensors. However, to the authors’ knowledge, there is no detailed description of the encapsulation of the fiber Bragg grating sensor in the literature to shield it from strain. In this study, different encapsulation methods for strain compensation were compared to find the encapsulation material most compatible with the electrolyte. For this, we stored the proposed sensors with different encapsulation methods in ethylene carbonate:ethyl methyl carbonate (EC:EMC) 3:7 with LiPF₆ (lithium hexafluorophosphate) electrolyte and applied temperature changes. After evaluating the sensor encapsulation methods in terms of handling, diameter, uncertainty, usability, and hysteresis behavior, the most suitable sensor encapsulation was found to be a fused silica capillary with polyimide coating. Full article

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

Due to great interest in the development of electric vehicles and other applications, improving the performances of lithium-ion batteries (LIBs) is crucial. Specifically, components of electrolytes for LIBs should be adequately chosen from hundreds of thousands of candidate compounds. In this study, we aimed to evaluate some physical properties expected for combinations of molecules for electrolytes by microscopic simulations. That is, the viscosity, ionic conductivity, degree of dissociation, diffusion coefficient, and conformation of each molecule were analyzed via molecular dynamics (MD) simulations. We aimed to understand how molecular-sized structures and properties collaboratively affect the behavior of electrolytes. The practical models of molecules we used were ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), butylene carbonate (BC), γ-butyrolactone (GBL), γ-valerolactone (GVL), dimethyl carbonate (DMC), ethyl-methyl carbonate (EMC), diethyl carbonate (DEC), and lithium hexafluorophosphate (LiPF₆). Many molecular systems of electrolytes were simulated, in which one molar LiPF₆ was mixed into a single or combined solvent. It was found that small solvent molecules diffused with relative ease, and they contributed to the higher ionic conductivity of electrolytes. It was clarified that the diffusion coefficient of lithium (Li) ions is greatly affected by the surrounding solvent molecules. We can conclude that high-permittivity solvents can be selectively coordinated around Li ions, and Li salts are sufficiently dissociated, even when there is only a small content of high-permittivity solvent. Thus, we can confirm solely by MD simulation that one of the better candidates for solvent molecules, formamide (F), will exhibit higher performance than the current solvents. Full article

All-solid-state batteries (ASSBs) are gaining traction in the arena of energy storage due to their promising results in producing high energy density and long cycle life coupled with their capability of being safe. The key challenges facing ASSBs are low conductivity and slow charge transfer kinetics at the interface between the electrode and the solid electrolyte. Garnet solid-state electrolyte has shown promising results in improving the ion conductivity but still suffers from poor capacity retention and rate performance due to the interfacial resistance between the electrodes. To improve the interfacial resistance, we prepared a composite consisting of Li₇La_2.75Ca_0.25Zr_1.75Nb_0.25O₁₂ (LLCZN) garnet material as the ceramic, polyethylene oxide (PEO) as the polymer, and lithium hexafluorophosphate (LiPF₆) as the salt. These compounds are mixed in a stoichiometric ratio and developed into a very thin disc-shaped solid electrolyte. The LLCZN provides a lithium-ion transport path to enhance the lithium-ion conduction during charging and discharging cycles, while the LiPF₆ contributes more lithium ions via the transport path. The PEO matrix in the composite material aids in bonding the compounds together and creating a large contact area, thereby reducing the issue of large interfacial resistance. FESEM images show the porous nature of the electrolyte which promotes the movement of lithium ions through the electrolyte. The fabricated LLCZN/PEO/LiPF₆ solid-state electrolyte shows outstanding electrochemical stability that remains at 130 mAh g⁻¹ up to 150 charging and discharging cycles at 0.05 mA cm⁻² current. All the specific capacities were calculated based on the mass of the cathode material (LiCoO₂). In addition, the coin cell retains 85% discharge capacity up to 150 cycles with a Coulombic efficiency of approximately 98% and energy efficiency of 90% during the entire cycling process. Full article

Carbon nanowall (CNW) and carbon nanotube (CNT) were prepared as anode materials of lithium-ion batteries. To fabricate a lithium-ion battery, copper (Cu) foil was cleaned using an ultrasonic cleaner in a solvent such as trichloroethylene (TCE) and used as a substrate. CNW and CNT were synthesized on Cu foil using plasma-enhanced chemical vapor deposition (PECVD) and water dispersion, respectively. CNW and CNT were used as anode materials for the lithium-ion battery, while lithium hexafluorophosphate (LiPF₆) was used as an electrolyte to fabricate another lithium-ion battery. For the structural analysis of CNW and CNT, field emission scanning electron microscope (FE-SEM) and Raman spectroscopy analysis were performed. The Raman analysis showed that the carbon nanotube in composite material can compensate for the defects of the carbon nanowall. Cyclic voltammetry (CV) was employed for the electrochemical properties of lithium-ion batteries, fabricated by CNW and CNT, respectively. The specific capacity of CNW and CNT were calculated as 62.4 mAh/g and 49.54 mAh/g. The composite material with CNW and CNT having a specific capacity measured at 64.94 mAh/g, delivered the optimal performance. Full article

Widening the working voltage of lithium-ion batteries is considered as an effective strategy to improve their energy density. However, the decomposition of conventional aprotic electrolytes at high voltage greatly impedes the success until the presence of high concentration electrolytes (HCEs) and the resultant localized HCEs (LHCEs). The unique solvated structure of HCEs/LHCEs endows the involved solvent with enhanced endurance toward high voltage while the LHCEs can simultaneously possess the decent viscosity for sufficient wettability to porous electrodes and separator. Nowadays, most LHCEs use LiFSI/LiTFSI as the salts and β-hydrofluoroethers as the counter solvents due to their good compatibility, yet the LHCE formula of cheap LiPF₆ and high antioxidant α-hydrofluoroethers is seldom investigated. Here, we report a unique formula with 3 mol L⁻¹ LiPF₆ in mixed carbonate solvents and a counter solvent α-substituted fluorine compound (1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether). Compared to a conventional electrolyte, this formula enables dramatic improvement in the cycling performance of LiCoO₂//graphite cells from approximately 150 cycles to 1000 cycles within the range of 2.9 to 4.5 V at 0.5 C. This work provides a new choice and scope to design functional LHCEs for high voltage systems. Full article

This study presents tributyl acetylcitrate (TBAC) as a novel ecofriendly high flash point and high boiling point solvent for electrolytes in lithium-ion batteries. The flash point ($T_{\mathrm{FP}}=217{}^{\circ }$C) and the boiling point ($T_{\mathrm{BP}}=331{}^{\circ }$C) of TBAC are approximately 200 K greater than that of conventional linear carbonate components, such as ethyl methyl carbonate (EMC) or diethyl carbonate (DEC). The melting point ($T_{\mathrm{MP}}=-80{}^{\circ }$C) is more than 100 K lower than that of ethylene carbonate (EC). Furthermore, TBAC is known as an ecofriendly solvent from other industrial sectors. A life cycle test of a graphite/NCM cell with 1 M lithium hexafluorophosphate (LiPF${}_6$) in TBAC:EC:EMC:DEC (60:15:5:20 wt) achieved a coulombic efficiency of above 99% and the remaining capacity resulted in 90 percent after 100 cycles ($C/4$) of testing. As a result, TBAC is considered a viable option for improving the thermal stability of lithium-ion batteries. Full article

Battery energy storage systems (BESS) are an essential component of renewable electricity infrastructure to resolve the intermittency in the availability of renewable resources. To keep the global temperature rise below 1.5 °C, renewable electricity and electrification of the majority of the sectors are a key proposition of the national and international policies and strategies. Thus, the role of BESS in achieving the climate impact mitigation target is significant. There is an unmet need for a detailed life cycle assessment (LCA) of BESS with lithium-ion batteries being the most promising one. This study conducts a rigorous and comprehensive LCA of lithium-ion batteries to demonstrate the life cycle environmental impact hotspots and ways to improve the hotspots for the sustainable development of BESS and thus, renewable electricity infrastructure. The whole system LCA of lithium-ion batteries shows a global warming potential (GWP) of 1.7, 6.7 and 8.1 kg CO₂ eq kg⁻¹ in change-oriented (consequential) and present with and without recycling credit consideration, scenarios. The GWP hotspot is the lithium-ion cathode, which is due to lithium hexafluorophosphate that is ultimately due to the resource-intensive production system of phosphorous, white, liquid. To compete against the fossil economy, the GWP of BESS must be curbed by 13 folds. To be comparable with renewable energy systems, hydroelectric, wind, biomass, geothermal and solar (4–76 g CO₂ eq kWh⁻¹), 300 folds reduction in the GWP of BESS will be necessary. The areas of improvement to lower the GWP of BESS are as follows: reducing scopes 2–3 emissions from fossil resource use in the material production processes by phosphorous recycling, increasing energy density, increasing lifespan by effective services, increasing recyclability and number of lives, waste resource acquisition for the battery components and deploying multi-faceted integrated roles of BESS. Achieving the above can be translated into an overall avoided GWP of up to 82% by 2040. Full article

Lithium hexafluorophosphate (LiPF₆) is one of the leading electrolytes in lithium-ion batteries, and its usage has increased tremendously in the past few years. Little is known, however, about its potential environmental and biological impacts. In order to improve our understanding of the cytotoxicity of LiPF₆ and the specific cellular response mechanisms to it, we performed a genome-wide screen using a yeast (Saccharomyces cerevisiae) deletion mutant collection and identified 75 gene deletion mutants that showed LiPF₆ sensitivity. Among these, genes associated with mitochondria showed the most enrichment. We also found that LiPF₆ is more toxic to yeast than lithium chloride (LiCl) or sodium hexafluorophosphate (NaPF₆). Physiological analysis showed that a high concentration of LiPF₆ caused mitochondrial damage, reactive oxygen species (ROS) accumulation, and ATP content changes. Compared with the results of previous genome-wide screening for LiCl-sensitive mutants, we found that oxidative phosphorylation-related mutants were specifically hypersensitive to LiPF₆. In these deletion mutants, LiPF₆ treatment resulted in higher ROS production and reduced ATP levels, suggesting that oxidative phosphorylation-related genes were important for counteracting LiPF₆-induced toxicity. Taken together, our results identified genes specifically involved in LiPF₆-modulated toxicity, and demonstrated that oxidative stress and ATP imbalance maybe the driving factors in governing LiPF₆-induced toxicity. Full article

In this work, a method for capillary electrophoresis (CE) hyphenated to a high-resolution mass spectrometer was presented for monitoring the stability of anions in ionic liquids (ILs) and in commonly used lithium ion battery (LIB) electrolytes. The investigated ILs were 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR13TFSI) and 1-methyl-1-propylpyrrolidinium bis(fluorosulfonyl)imide (PYR13FSI). The method development was conducted by adjusting the following parameters: buffer compositions, buffer concentrations, and the pH value. Also the temperature and the voltage applied on the capillary were optimized. The ILs were aged at room temperature and at 60 °C for 16 months each. At both temperatures, no anionic decomposition products of the FSI− and TFSI− anions were detected. Accordingly, the FSI− and TFSI− anions were thermally stable at these conditions. This method was also applied for the investigation of LIB electrolyte samples, which were aged at 60 °C for one month. The LP30 (50/50 wt. % dimethyl carbonate/ethylene carbonate and 1 M lithium hexafluorophosphate) electrolyte was mixed with the additive 1,3-propane sultone (PS) and with one of the following organophosphates (OP): dimethyl phosphate (DMP), diethyl phosphate (DEP), and triethyl phosphate (TEP), to investigate the influence of these compounds on the formation of OPs. Full article