Explore the vast range of titles available.

Functional electrolyte is the key to stabilize the highly reductive lithium (Li) metal anode and the high-voltage cathode for longlife, high-energy-density rechargeable Li metal batteries (LMBs). However, fundamental mechanisms on the interactions between reactive electrodes and electrolytes are still not well understood. Recently localized high-concentration electrolytes (LHCEs) are emerging as a promising electrolyte design strategy for LMBs. Here, we use LHCEs as an ideal platform to investigate the fundamental correlation between the reactive characteristics of the inner solvation sheath on electrode surfaces due to their unique solvation structures. The effects of a series of LHCEs with model electrolyte solvents (carbonate, sulfone, phosphate, and ether) on the stability of high-voltage LMBs are systematically studied. The stabilities of electrodes in different LHCEs indicate the intrinsic synergistic effects between the salt and the solvent when they coexist on electrode surfaces. Experimental and theoretical analyses reveal an intriguing general rule that the strong interactions between the salt and the solvent in the inner solvation sheath promote their intermolecular proton/charge transfer reactions, which dictates the properties of the electrode/electrolyte interphases and thus the battery performances.

The structural role of solvation phenomena in bioorganic compounds has been documented sporadically over the last two decades, although they are of fundamental importance in a variety of chemical, physical, and biological processes. NMR chemical shifts depend on the electron densities around the nuclei, which can be influenced by the surrounding environment. Solvent-dependent chemical shift variations, therefore, can provide important structural information on solute–solvent interactions, especially nuclei, which belong to polar groups, such as OH, NH, CONH, COOH, etc. Recent developments in quantum chemical methods for calculating NMR chemical shifts, especially those incorporating explicit solvent effects, and the exponential advances in computer power can provide an excellent methodology for the accurate calculation of chemical shifts in solution. Furthermore, comparison of density functional theory (DFT) calculated activation free energies with NMR experimentally determined values can provide a reliable method for investigating the role of solvents in various atomistic reaction mechanisms. It has been demonstrated that the combined use of NMR and DFT calculations represents the new frontier of our understanding of the role of solvents, at the atomic level, in molecular structures and in catalytic reactions of bioorganic molecules, natural products and model compounds.

The performance of Li batteries is influenced by the Li+ solvation structure, which can be precisely adjusted by the components of the electrolytes. In this review, we overview the strategies for optimizing electrolyte solvation structures from three different perspectives, including anion regulation, binding energy regulation, and additive regulation. These strategies can optimize the composition of the electrode‐electrolyte interface, enhance the anti‐oxidative stability of electrolytes as well as regulate the behaviors of anions, solvents, and Li+ during the cycling process. Moreover, we also provide our insights into these aspects as well as present perspectives on high‐performance Li batteries. In this review, we discuss about the structural regulation chemistry of lithium ion solvation for lithium batteries, from the strategies for optimizing electrolyte solvation structures to perspectives on high‐performance Li batteries.

Lithium-metal batteries with high energy/power densities have significant applications in electronics, electric vehicles, and stationary power plants. However, the unstable lithium-metal-anode/electrolyte interface has induced insufficient cycle life and safety issues. To improve the cycle life and safety, understanding the formation of the solid electrolyte interphase (SEI) and growth of lithium dendrites near the anode/electrolyte interface, regulating the electrodeposition/electrostripping processes of Li + , and developing multiple approaches for protecting the lithium-metal surface and SEI layer are crucial and necessary. This paper comprehensively reviews the research progress in SEI and lithium dendrite growth in terms of their classical electrochemical lithium plating/stripping processes, interface interaction/nucleation processes, anode geometric evolution, fundamental electrolyte reduction mechanisms, and effects on battery performance. Some important aspects, such as charge transfer, the local current distribution, solvation, desolvation, ion diffusion through the interface, inhibition of dendrites by the SEI, additives, models for dendrite formation, heterogeneous nucleation, asymmetric processes during stripping/plating, the host matrix, and in situ nucleation characterization, are also analyzed based on experimental observations and theoretical calculations. Several technical challenges in improving SEI properties and reducing lithium dendrite growth are analyzed. Furthermore, possible future research directions for overcoming the challenges are also proposed to facilitate further research and development toward practical applications. Graphical Abstract

Aqueous rechargeable ammonium-ion batteries (AIBs) possess the characteristics of safety, low cost, environmental friendliness, and fast diffusion kinetics. However, their energy density is often limited due to the low specific capacity of cathode materials and narrow electrochemical stability windows of electrolytes. Herein, high-performance aqueous AIBs were designed by coupling Fe-substituted manganese-based Prussian blue analog (FeMnHCF) cathodes and highly concentrated NH₄CF₃SO₃ electrolytes. In FeMnHCF, Mn3+/Mn2+-N redox reaction at high potential was introduced, and two metal active redox species of Mn and Fe were achieved. To match such FeMnHCF cathodes, highly concentrated NH₄CF₃SO₃ electrolyte was further developed, where NH₄⁺ ion displays low-solvation structure because of the increased coordination number of CF₃SO₃⁻ anions. Furthermore, the water molecules are confined by NH₄⁺ and CF₃SO₃⁻ ions in their solvation sheath, leading to weak interaction between water molecules and thus effectively extending the voltage window of electrolyte. Consequently, the FeMnHCF electrodes present high reversibility during the charge/discharge process. Moreover, owing to a small amount of free water in concentrated electrolyte, the dissolution of FeMnHCF is also inhibited. As a result, the assembled aqueous AIBs exhibit enhanced energy density, excellent rate capability, and stable cycling behavior. This work provides a creative route to construct high-performance aqueous AIBs.

All-climate temperature operation capability and increased energy density have been recognized as two crucial targets, but they are rarely achieved together in rechargeable lithium (Li) batteries. Herein, we demonstrate an electrolyte system by using monodentate dibutyl ether with both low melting and high boiling points as the sole solvent. Its weak solvation endows an aggregate solvation structure and low solubility toward polysulfide species in a relatively low electrolyte concentration (2 mol L−1). These features were found to be vital in avoiding dendrite growth and enabling Li metal Coulombic efficiencies of 99.0%, 98.2%, and 98.7% at 23 °C, −40 °C, and 50 °C, respectively. Pouch cells employing thin Li metal (50 μm) and high-loading sulfurized polyacrylonitrile (3.3 mAh cm−2) cathodes (negative-to-positive capacity ratio = 2) output 87.5% and 115.9% of their room temperature capacity at −40 °C and 50°C, respectively. This work provides solvent-based design criteria for a wide temperature range Li-sulfur pouch cells.

Electrolyte is very critical to the performance of the high-voltage lithium (Li) metal battery (LMB), which is one of the most attractive candidates for the next-generation high-density energystorage systems. Electrolyte formulation and structure determine the physical properties of the electrolytes and their interfacial chemistries on the electrode surfaces. Localized high-concentration electrolytes (LHCEs) outperform state-of-the-art carbonate electrolytes in many aspects in LMBs due to their unique solvation structures. Types of fluorinated cosolvents used in LHCEs are investigated here in searching for the most suitable diluent for high-concentration electrolytes (HCEs). Nonsolvating solvents (including fluorinated ethers, fluorinated borate, and fluorinated orthoformate) added in HCEs enable the formation of LHCEs with high-concentration solvation structures. However, low-solvating fluorinated carbonate will coordinate with Li⁺ ions and form a second solvation shell or a pseudo-LHCE which diminishes the benefits of LHCE. In addition, it is evident that the diluent has significant influence on the electrode/electrolyte interphases (EEIs) beyond retaining the high-concentration solvation structures. Diluent molecules surrounding the high-concentration clusters could accelerate or decelerate the anion decomposition through coparticipation of diluent decomposition in the EEI formation. The varied interphase features lead to significantly different battery performance. This study points out the importance of diluents and their synergetic effects with the conductive salt and the solvating solvent in designing LHCEs. These systematic comparisons and fundamental insights into LHCEs using different types of fluorinated solvents can guide further development of advanced electrolytes for high-voltage LMBs.

Rational electrolyte design is essential for stabilizing high-energy-density lithium (Li) metal batteries but is plagued by poor understanding on the effect of electrolyte component properties on solvation structure and interfacial chemistry. Herein, regulating the solvation structure in localized high-concentration electrolytes (LHCE) by weakening the solvating power of solvents is proposed for high-performance LHCE. 1,3-dimethoxypropane (DMP) solvent has relatively weak solvating power but maintains the high solubility of Li salts, thus impelling the formation of nanometric aggregates where an anion coordinates to more than two Li-ions (referred to AGG- n ) in LHCE. The decomposition of AGG- n increases the LiF content in solid electrolyte interphase (SEI), further enabling uniform Li deposition. The cycle life of Li metal batteries with DMP-based LHCE is 2.1 times (386 cycles) as that of advanced ether-based LHCE under demanding conditions. Furthermore, a Li metal pouch cell of 462 Wh kg −1 undergoes 58 cycles with the DMP-based LHCE pioneeringly. This work inspires ingenious solvating power regulation to design high-performance electrolytes for practical Li metal batteries.

HighlightsThe amphipathic phenylalanine-adsorbed layer contributes to form a nucleophilic–hydrophobic interface that homogenizes Zn2+ flux while repelling H2O molecules from contacting Zn anode.The preferential reduction of phenylalanine (Phe) prior to H2O facilitates in situ formation of an organic–inorganic hybrid solid electrolyte interphase, enhancing the interfacial stability.Benefiting from the triple protection of Phe, the Zn||Zn and Zn||LMO cells display significantly improved electrochemical performances, even at extreme diluted electrolytes.Aqueous Zn2+-ion batteries (AZIBs), recognized for their high security, reliability, and cost efficiency, have garnered considerable attention. However, the prevalent issues of dendrite growth and parasitic reactions at the Zn electrode interface significantly impede their practical application. In this study, we introduced a ubiquitous biomolecule of phenylalanine (Phe) into the electrolyte as a multifunctional additive to improve the reversibility of the Zn anode. Leveraging its exceptional nucleophilic characteristics, Phe molecules tend to coordinate with Zn2+ ions for optimizing the solvation environment. Simultaneously, the distinctive lipophilicity of aromatic amino acids empowers Phe with a higher adsorption energy, enabling the construction of a multifunctional protective interphase. The hydrophobic benzene ring ligands act as cleaners for repelling H2O molecules, while the hydrophilic hydroxyl and carboxyl groups attract Zn2+ ions for homogenizing Zn2+ flux. Moreover, the preferential reduction of Phe molecules prior to H2O facilitates the in situ formation of an organic–inorganic hybrid solid electrolyte interphase, enhancing the interfacial stability of the Zn anode. Consequently, Zn||Zn cells display improved reversibility, achieving an extended cycle life of 5250 h. Additionally, Zn||LMO full cells exhibit enhanced cyclability of retaining 77.3% capacity after 300 cycles, demonstrating substantial potential in advancing the commercialization of AZIBs.