Search Results (58)

Polymer electrolytes (PEs) provide enhanced safety for high–energy–density lithium metal batteries (LMBs), yet their practical application is hampered by intrinsically low ionic conductivity and insufficient electrochemical stability, primarily stemming from suboptimal Li⁺ solvation environments and transport pathways coupled with slow polymer dynamics. Herein, we demonstrate a molecular design strategy to overcome these limitations by regulating the Li⁺ solvation structure through the synergistic interplay of conventional Lewis acid–base coordination and engineered hydrogen bond (H–bond) networks, achieved by incorporating specific H–bond donor functionalities (N,N′–methylenebis(acrylamide), MBA) into the polymer architecture. Computational modeling confirms that the introduced H–bonds effectively modulate the Li⁺ coordination environment, promote salt dissociation, and create favorable pathways for faster ion transport decoupled from polymer chain motion. Experimentally, the resultant polymer electrolyte (MFE, based on MBA) enables exceptionally stable Li metal cycling in symmetric cells (>4000 h at 0.1 mA cm⁻²), endows LFP|MFE|Li cells with long–term stability, achieving 81.0% capacity retention after 1400 cycles, and confers NCM622|MFE|Li cells with cycling endurance, maintaining 81.0% capacity retention after 800 cycles under a high voltage of 4.3 V at room temperature. This study underscores a potent molecular engineering strategy, leveraging synergistic hydrogen bonding and Lewis acid–base interactions to rationally tailor the Li⁺ solvation structure and unlock efficient ion transport in polymer electrolytes, paving a promising path towards high–performance solid–state lithium metal batteries. Full article

It has been demonstrated that the traditional hydrometallurgical method is still economically viable in several industrial applications such as Bayer, Boix, Platsol, Sherrit-Gordon, and so on. The conventional extraction technique of valuable metals from their ores using an aqua medium has several challenges. The following can be listed for the illustration of this: (1) Inorganic acids used during the leaching process have been proven to be non-environmentally friendly and ready to lead to non-selective processes in general, except in rare cases used in alkaline environments. (2) Special linings are required in the reactors used due to the corrosive impact of acids such as HCl and H₂SO_4, especially when leaching at high temperatures, rendering all processes costly. (3) Practically, using inorganic acids while leaching samples containing amorphous silicate phases leads to gel formation. Solvometallurgy overcomes these challenges by substituting the aqueous phase for other polar solvents, such as polar molecular organic or ionic solvents. The advantage of this substitution lies in the ability to manipulate metal ion distribution using solvents with varying solvation properties. This review examines the potential of solvometallurgical processes (solvoleaching) over conventional hydrometallurgy as viable alternatives for metal extraction from sulfide ores. It highlights the key distinctions between hydrometallurgy and solvometallurgy while emphasizing the potential economic and environmental advantages solvometallurgy offers. Full article

The formation of unstable solid electrolyte interphases (SEIs) on the surface of lithium metal anodes poses a significant barrier to the commercialization of lithium metal batteries (LMBs). Rational modulation of solvation structures within the electrolytes emerged as one of the most effective strategies to enhance interfacial stability in LMBs; however, this approach often compromises the structural stability of the bulk electrolyte. Herein, we present an innovative method that improves interface stability without adversely affecting the bulk electrolyte’s structural stability. By employing ZSM molecular sieves as efficient ion channels on the lithium metal anode surface—termed ZSM electrolytes—a more aggregated solvation structure is induced at the lithium metal interface, resulting in an anion-rich interphase. This anion-enriched environment promotes the formation of an SEI derived from anions, thereby enhancing the stability of the lithium metal interface. Consequently, Li||Cu cells utilizing the ZSM electrolyte achieve an average coulombic efficiency (CE) of 98.76% over 700 h. Moreover, LiFePO₄||Li batteries exhibit stable cycling performance exceeding 900 cycles at a current density of 1 C. This design strategy offers robust support for effective interfacial regulation in lithium metal batteries. Full article

Localized high-concentration electrolytes (LHCEs) are promising systems for improving the high-voltage performance and interfacial stability of lithium-metal batteries (LMBs). Unfortunately, they are always challenged by liquid–liquid phase separation during solution preparation. Further investigation is always required when the prepared electrolyte has encountered liquid–liquid phase separation previously. Here, we propose a “cognate cosolvent” strategy to mediate phase-separated LiBF₄/fluoroethylene carbonate (FEC)|ethyl trifluoroacetate (TFAE) mixtures with ethyl acetate (EA), forming effective LiBF₄/FEC/EA/TFAE-based LHCEs (B-LHCEs). Because of their unique solvation structure, the B-LHCEs exhibit high oxidative stability, facilitating Li⁺ transport. The optimized B-LHCEs help single-crystal LiMn_0.8Mn_0.1Co_0.1O₂/Li batteries form robust interphases, improving interfacial stability. As a result, distinct performance can be obtained (4.5 V, 500 cycles, ~90%, 1400, ~70%; 25 C, 128 mAh g⁻¹, 4.7 V, 500, 82.5%). This work turns the “impossible” into an “effective” high-voltage electrolyte design, transcending the previous paradigms of electrolyte investigation and enriching LHCE preparation research. Full article

Data on the diffusion and migration characteristics of rare earth metal ions in fluoride molten salt systems are crucial for optimizing the electrolytic preparation of rare earth metals and alloys. This study investigated the solubility, conductivity, and density of the (LiF-CaF₂)_eut. system saturated with Nd₂O₃ using the isothermal saturation method, conductivity cell constant variation, and the Archimedes method, respectively. Employing the Hittorf method’s principles, a three-compartment electrolyzer was designed to determine the mobility number of dissolved Nd* (III) ions in the saturated (LiF-CaF₂)_eut.-Nd₂O₃ system. The radial distribution function was computed via ab initio molecular dynamics, and the self-diffusion coefficient of ions in the system was analyzed. Utilizing the Nernst–Einstein equation, the diffusion coefficient of Nd* (III) ions was calculated. The solubility, conductivity, and density of the saturated (LiF-CaF₂)_eut.-Nd₂O₃ system exhibit linear variation within 1173–1473 K. The mobility number of solvated Nd* (III) ions increases linearly with temperature, displaying nonlinear variation with potential within 3.5–4.5 V, and gradually decreases after reaching a maximum of 4.0–4.25 V. The radial distribution function reveals the highest diffusion and mobility barriers for Nd* (III) ions, with solvated O* (II) ions presenting the most significant hindrance. The Nd* (III) ion diffusion coefficients linearly increase with temperature (1123–1373 K) under specific potential conditions (3.5–4.5 V) but exhibit nonlinear changes with potential (3.5–4.5 V) under fixed temperature conditions (1123–1373 K), then decrease after peaking within 4.0–4.5 V. The diffusion coefficients of Nd* (III) ions are sensitive to potential changes. Full article

With the rapid global increase in the use of digital devices and electric vehicles, solid polymer electrolytes (SPEs) have emerged as promising candidates for all-solid-state batteries. They are expected to resolve safety concerns and overcome the limitations of energy density and charging speed associated with traditional Li-ion batteries with liquid electrolytes. However, a limited understanding of ionic conduction mechanisms remains a significant barrier to their further development and practical application. In this study, we employed molecular dynamics simulations using the COMPASS II force field under NPT/NVT ensembles at 298 K to investigate the static and dynamic properties of poly(ethylene carbonate) (PEC) electrolytes at various salt concentrations. Key analyses included the radial distribution function, solvation free energy, and mean-square displacement (MSD) of individual Li cations. Based on their MSD data, Li cations were categorized into “faster” or “slower” groups, corresponding to conductivity levels above or below the average in each model. Our findings reveal that, at higher concentrations, a smaller fraction of faster Li cations contributes disproportionately more than slower Li cations to the overall mobility, highlighting that targeted manipulation of solvation structures could enhance ion transport efficiency in highly concentrated SPEs. Additionally, changes in coordination number and solvation free energy for both faster and slower Li cations suggest the existence of three different solvation patterns as salt concentration increases. These insights provide a deeper understanding of ionic transport and solvation structures in PEC electrolytes, with potential implications for the design of more efficient all-solid-state batteries. Full article

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

In lithium metal batteries, accurately estimating the Li⁺ solvation ability of solvents is essential for effectively modulating the Li⁺ solvation sheath to form a stable interphase and achieve high ionic conductivity. However, previous studies have shown that the theoretically calculated Li⁺ binding energy, commonly used to evaluate solvation ability, exhibits only a moderate correlation with experimentally measured ionic conductivity (R² = 0.68). In this study, to determine the effective theoretical descriptor for evaluating the solvation ability, Li⁺ solvation energy was adopted instead of Li⁺ binding energy, and its correlation with ionic conductivity was compared. Using a sophisticated calculation model that considers the Li⁺ counter anion and solvent, it was demonstrated that the tendency between the calculated Li⁺ solvation energies and experimentally measured ionic conductivities is highly consistent (R² = 0.97). Therefore, Li⁺ solvation energy is suggested as the theoretical descriptor for evaluating solvation ability. All these findings encourage the development of effective molecular design of solvents for lithium metal batteries. Full article

Cation⊗3π interactions play a special role in the behaviors of biological molecules and carbon-based materials in aqueous solutions, yet the effects of solvation on these interactions remain poorly understood. This study examines the sequential attachment of water molecules to cation⊗3π systems (cation = Li⁺, Na⁺, K⁺), revealing that solvation influences interaction strengths in opposing ways: solvation of the metal cation decreases the strengths of cation⊗3π interactions, while the solvation of the benzene molecule increases the strengths of cation⊗3π interactions, compared with the strengths of cation⊗3π interactions in the gas phase. The mechanism analyses revealed that in the presence of surrounding water molecules, the stability of cation⊗3π systems is generally enhanced by cation–π, π–π, water–π, and water–ion interactions, while water–water interactions typically have a destabilizing effect. In addition, the primary effect of water molecules at different adsorption sites is to modulate the Coulombic multipole–multipole interactions and the overlap between monomeric charge distributions, thereby influencing the changes in strengths of cation⊗3π interactions. Moreover, AIMD simulations further underscore the practical significance of cation⊗3π interactions. These findings provide valuable insights into the structures and the strengths of cation⊗3π interactions with the effect of solvation. Full article

High-voltage initial anode-free lithium metal batteries (AFLMBs) promise the maximized energy densities of rechargeable lithium batteries. However, the reversibility of the high-voltage cathode and lithium metal anode is unsatisfactory in sustaining their long lifespan. In this research, a concentrated electrolyte comprising dual salts of LiTFSI and LiDFOB dissolved in mixing solvents of dimethyl carbonate (DMC) and fluoroethylene carbonate (FEC) with a LiNO₃ additive was formulated to address this challenge. FEC and LiNO₃ regulate the anion-rich solvation structure and help form a LiF, Li₃N-rich solid electrolyte interphase (SEI) with a high lithium plating/stripping Coulombic efficiency of 98.3%. LiDFOB preferentially decomposes to effectively suppress the side reaction at the high-voltage operation of the Li-rich Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ cathode. Moreover, the large irreversible capacity during the initial charge/discharge cycle of the cathode provides supplementary lithium sources for cycle life extension. Owing to these merits, the as-fabricated AFLMBs can operate stably for 80 cycles even at an ultrahigh voltage of 4.6 V. This study sheds new insights on the formulation of advanced electrolytes for highly reversible high-voltage cathodes and lithium metal anodes and could facilitate the practical application of AFLMBs. Full article

The commercialization of sodium batteries faces many challenges, one of which is the lack of suitable high-quality separators. Herein, we presented a novel natural silkworm cocoon-derived separator (SCS) obtained from the cocoon inner membrane after a simple degumming process. A Na||Na symmetric cell assembled with this separator can be stably cycled for over 400 h under test conditions of 0.5 mA cm⁻²–0.5 mAh cm⁻². Moreover, the Na||SCS||Na₃V₂(PO₄)₃ full cell exhibits an initial capacity of 79.3 mAh g⁻¹ at 10 C and a capacity retention of 93.6% after 1000 cycles, which far exceeded the 57.5 mAh g⁻¹ and 42.1% of the full cell using a commercial glass fiber separator (GFS). The structural origin of this excellent electrochemical performance lies in the fact that cationic functional groups (such as amino groups) on silkworm proteins can de-solvate Na-ions by anchoring the ClO₄⁻ solvent sheath, thereby enhancing the transference number, transport kinetics and deposition/dissolution properties of Na-ions. In addition, the SCS has significantly better mechanical properties and thinness indexes than the commercial GFS, and, coupled with the advantages of being natural, cheap, non-polluting and degradable, it is expected to be used as a commercialized sodium battery separator material. Full article

Asymmetric lithium salts, such as lithium (difluoromethanesulfonyl)(trifluoromethanesulfonyl)imide (LiDFTFSI), have been demonstrated to surpass traditional symmetric lithium salts with improved Li⁺ conductivity and the capacity to generate a stable solid electrolyte interphase (SEI) while maintaining compatibility with an aluminum (Al⁰) current collector. However, the intrinsic reductive mechanism through which LiDFTFSI influences battery performance remains unclear and under debate. Herein, detailed SEI reactions of LiDFTFSI–based electrolytes were investigated by combining density functional theory and molecular dynamics, aiming to clarify the formation process and atomic structure of the SEI. Our results show that asymmetric DFTFSI⁻ weakens the interaction between carbonate solvents and Li⁺, and substantially alters the solvation structure, exhibiting a well-balanced coordination capacity compared to bis(trifluoromethanesulfonyl)imide (TFSI⁻). Nanosecond hybrid molecular dynamics simulation further reveals that preferential decomposition of LiDFTFSI produces sufficient LiF and Li₂O to facilitate a robust SEI. Moreover, abundant F⁻ generated from LiDFTFSI decomposition accumulates on the Al surface and subsequently combines with Al³⁺ from the current collector to form AlF₃, potentially inhibiting corrosion of the current collector. Overall, these findings elucidate how LiDFTFSI regulates the solvation sheath and SEI structure, advancing the development of high-performance electrolytes compatible with current collectors. Full article

To realize high-energy-density Li metal batteries at low temperatures, a new electrolyte is needed to solve the high-voltage compatibility and fast lithium-ion de-solvation process. A gel polymer electrolyte with a small-molecular-weight polymer is widely investigated by combining the merits of a solid polymer electrolyte (SPE) and liquid electrolyte (LE). Herein, we present a new gel polymer electrolyte (P-DOL) by the lithium difluoro(oxalate)borate (LiDFOB)-initiated polymerization process using 1,3-dioxolane (DOL) as a monomer solvent. The P-DOL presents excellent ionic conductivity (1.12 × 10⁻⁴ S cm⁻¹) at −20 °C, with an oxidation potential of 4.8 V. The Li‖LiCoO₂ cell stably cycled at 4.3 V under room temperature, with a discharge capacity of 130 mAh g⁻¹ at 0.5 C and a capacity retention rate of 86.4% after 50 cycles. Moreover, a high-Ni-content LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cell can steadily run for 120 cycles at −20 °C, with a capacity retention of 88.4%. The underlying mechanism of high-voltage compatibility originates from the dense and robust B- and F-rich cathode interface layer (CEI) formed at the cathode interface. Our report will shed light on the real application of Li metal batteries under all-climate conditions in the future. Full article

Anion-driven, nanoscale polar–apolar structural organization is investigated in a solvate ionic liquid (SIL) setting by comparing sulfonate-based anions with long and short perfluorinated alkyl chains. Representative SILs are created from 1,2-bis(2-methoxyethoxy)ethane (“triglyme” or “G3”), lithium nonafluoro-1-butanesulfonate, and lithium trifluoromethanesulfonate. Molecular dynamics simulations, density functional theory computations, and vibrational spectroscopy provide insight into the overall liquid structure, cation–solvent interactions, and cation–anion association. Significant competition between G3 and anions for cation-binding sites characterizes the G3–LiC₄F₉SO₃ mixtures. Only 50% of coordinating G3 molecules form tetradentate complexes with Li⁺ in [(G3)₁Li][C₄F₉SO₃]. Moreover, the SIL is characterized by extensive amounts of ion pairing. Based on these observations, [(G3)₁Li][C₄F₉SO₃] is classified as a “poor” SIL, similar to the analogous [(G3)₁Li][CF₃SO₃] system. Even though the comparable basicity of the CF₃SO₃⁻ and C₄F₉SO₃⁻ anions leads to similar SIL classifications, the hydrophobic fluorobutyl groups support extensive apolar domain formation. These apolar moieties permeate throughout [(G3)₁Li][C₄F₉SO₃] and persist even at relatively low dilution ratios of [(G3)₁₀Li][C₄F₉SO₃]. By way of comparison, the CF₃ group is far too short to sustain polar–apolar segregation. This demonstrates how chemically modifying the anions to include hydrophobic groups can impart unique nanoscale organization to a SIL. Moreover, tuning these nano-segregated fluorinated domains could, in principle, control the presence of dimensionally ordered states in these mixtures without changing the coordination of the lithium ions. Full article

Small Li⁺Ar_n clusters are employed in this work as model systems to study microsolvation. Although first and second solvation shells are expected to be the most relevant ones for this type of atomic solvents, it is also interesting to explore larger clusters in order to identify the influence of external atoms on structural and thermodynamic properties. In this work, we perform a global geometry optimization for ${\mathrm{Li}}^{+}$${\mathrm{Ar}}_n$ clusters (with n = 41–100) and parallel tempering Monte Carlo (PTMC) simulations for some selected sizes. The results show that global minimum structures of large clusters always have 6 argon atoms in the first solvation shell while maintaining the number of 14 or 16 argon atoms in the second one. By contrast, third and fourth solvation shells vary significantly the number of argon atoms with the cluster size, and other shells can hardly be assigned due to the reduced influence of ${\mathrm{Li}}^{+}$ on the external argon atoms for large clusters. In turn, PTMC calculations show that the melting of the most external solvation shells of large microsolvation clusters occurs at $T\sim 50\mathrm{K}$, which is independent of cluster size. Structural transitions can be observed between quasi-degenerated structures at low temperatures. Moreover, the present results highlight the fluxional character of the external solvation shells of these large ${\mathrm{Li}}^{+}$${\mathrm{Ar}}_n$ clusters, which may be seen as typical “snowball” structures. Full article