Critical Solvation Structures Arrested Active Molecules for Reversible Zn Electrochemistry

Aqueous Zn-ion batteries(AZIBs)have attracted increasing attention in next-generation energy storage systems due to their high safety and economic.Unfortunately,the side reactions,dendrites and hydrogen evolution effects at the zinc anode interface in aqueous electrolytes seriously hinder the application of aqueous zinc-ion batteries.Here,we report a critical solvation strategy to achieve reversible zinc electrochemistry by introducing a small polar molecule acetonitrile to form a“catcher”to arrest active molecules(bound water molecules).The stable solvation structure of[Zn(H_(2)O)_(6)]^(2+)is capable of maintaining and completely inhibiting free water molecules.When[Zn(H_(2)O)_(6)]^(2+)is partially desolvated in the Helmholtz outer layer,the separated active molecules will be arrested by the“catcher”formed by the strong hydrogen bond N-H bond,ensuring the stable desolvation of Zn^(2+).The Zn||Zn symmetric battery can stably cycle for 2250 h at 1 mAh cm^(-2),Zn||V_(6)O_(13) full battery achieved a capacity retention rate of 99.2%after 10,000 cycles at 10 A g^(-1).This paper proposes a novel critical solvation strategy that paves the route for the construction of high-performance AZIBs.

Impact of ethanol on the flotation efficiency of imidazolium ionic liquids as collectors:Insights from dynamic surface tension and solvation analysis

To conduct extensive research on the application of ionic liquids as collectors in mineral flotation,ethanol(EtOH)was used as a solvent to dissolve hydrophobic ionic liquids(ILs)to simplify the reagent regime.Interesting phenomena were observed in which EtOH exerted different effects on the flotation efficiency of two ILs with similar structures.When EtOH was used to dissolve 1-dodecyl-3-methylimidazolium chloride(C12[mim]Cl)and as a collector for pure quartz flotation tests at a concentration of 1×10^(−5)mol·L^(−1),quartz recovery increased from 23.77%to 77.91%compared with ILs dissolved in water.However,quartz recovery of 1-dodecyl-3-methylim-idazolium hexafluorophosphate(C12[mim]PF6)decreased from 60.45%to 24.52%under the same conditions.The conditional experi-ments under 1×10^(−5)mol·L^(−1)ILs for EtOH concentration and under 2vol%EtOH for ILs concentration confirmed this difference.After being affected by EtOH,the mixed ore flotation tests of quartz and hematite showed a decrease in the hematite concentrate grade and re-covery for the C12[mim]Cl collector,whereas the hematite concentrate grade and recovery for the C12[mim]PF6 collector increased.On the basis of these differences and observations of flotation foam,two-phase bubble observation tests were carried out.The EtOH promoted the foam height of two ILs during aeration.It accelerated static froth defoaming after aeration stopped,and the foam of C12[mim]PF6 de-foaming especially quickly.In the discussion of flotation tests and foam observation,an attempt was made to explain the reasons and mechanisms behind the diverse phenomena using the dynamic surface tension effect and solvation effect results from EtOH.The solva-tion effect was verified through Fourier transform infrared(FT-IR),X-ray photoelectron spectroscopy(XPS),and Zeta potential tests.Al-though EtOH affects the adsorption of ILs on the ore surface during flotation negatively,it holds an positive value of inhibiting foam mer-ging during flotation aeration and accelerating the defoaming of static foam.And induce more robust secondary enrichment in the mixed ore flotation of the C12[mim]PF6 collector,facilitating effective mixed ore separation even under inhibitor-free conditions.

Solvation Engineering via Fluorosurfactant Additive Toward Boosted Lithium-Ion Thermoelectrochemical Cells

Lithium-ion thermoelectrochemical cell(LTEC), featuring simultaneous energy conversion and storage, has emerged as promising candidate for low-grade heat harvesting. However, relatively poor thermosensitivity and heat-to-current behavior limit the application of LTECs using LiPF_6 electrolyte. Introducing additives into bulk electrolyte is a reasonable strategy to solve such problem by modifying the solvation structure of electrolyte ions. In this work, we develop a dual-salt electrolyte with fluorosurfactant(FS) additive to achieve high thermopower and durability of LTECs during the conversion of low-grade heat into electricity. The addition of FS induces a unique Li~+ solvation with the aggregated double anions through a crowded electrolyte environment,resulting in an enhanced mobility kinetics of Li~+ as well as boosted thermoelectrochemical performances. By coupling optimized electrolyte with graphite electrode, a high thermopower of 13.8 mV K^(-1) and a normalized output power density of 3.99 mW m^(–2) K^(–2) as well as an outstanding output energy density of 607.96 J m^(-2) can be obtained.These results demonstrate that the optimization of electrolyte by regulating solvation structure will inject new vitality into the construction of thermoelectrochemical devices with attractive properties.

Solvation strategies in various electrolytes for advanced zinc metal anode

Aqueous zinc-ion batteries(AZIBs),known for their high safety,low cost,and environmental friendliness,have a wide range of potential applications in large-scale energy storage systems.However,the notorious dendrite growth and severe side reactions on the anode have significantly hindered their further practical development.Recent studies have shown that the solvation chemistry in the electrolyte is not only closely related to the barriers to the commercialization of AZIBs,but have also sparked a number of valuable ideas to address the challenges of AZIBs.Therefore,we systematically summarize and discuss the regulatory mechanisms of solvation chemistry in various types of electrolytes and the influence of the solvation environment on battery performance.The challenges and future directions for solvation strategies based on the electrolyte environment are proposed to improve their performance and expand their application in AZIBs.

Lithium Sulfur Batteries:Insights from Solvation Chemistry to Feasibility Designing Strategies for Practical Applications

Rechargeable lithium-sulfur(Li-S)batteries,featuring high energy density,low cost,and environmental friendliness,have been dubbed as one of the most promising candidates to replace current commercial rechargeable Li-ion batteries.However,their practical deployment has long been plagued by the infamous“shuttle effect”of soluble Li polysulfides(LiPSs)and the rampant growth of Li dendrites.Therefore,it is important to specifically elucidate the solvation structure in the Li-S system and systematically summarize the feasibility strategies that can simultaneously suppress the shuttle effect and the growth of Li dendrites for practical applications.This review attempts to achieve this goal.In this review,we first introduce the importance of developing Li-S batteries and highlight the key challenges.Then,we revisit the working principles of Li-S batteries and underscore the fundamental understanding of LiPSs.Next,we summarize some representative characterization techniques and theoretical calculations applied to characterize the solvation structure of LiPSs.Afterward,we overview feasible designing strategies that can simultaneously suppress the shuttle effect of soluble LiPSs and the growth of Li dendrites.Finally,we conclude and propose personal insights and perspectives on the future development of Li-S batteries.We envisage that this timely review can provide some inspiration to build better Li-S batteries for promoting practical applications.

Modulating the Electrolyte Inner Solvation Structure via Low Polarity Co-solvent for Low-Temperature Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries are regarded as the promising candidates for large-scale energy storage systems owing to low cost and high safety;however,their applications are restricted by their poor low-temperature performance.Herein,a low-temperature electrolyte for low-temperature aqueous zinc-ion batteries is designed by introducing low-polarity diglyme into an aqueous solution of Zn(ClO_(4))_(2).The diglyme disrupts the hydrogenbonding network of water and lowers the freezing point of the electrolyte to-105℃.The designed electrolyte achieves ionic conductivity up to16.18 mS cm^(-1)at-45℃.The diglyme and ClO_(4)^(-)reconfigure the solvated structure of Zn^(2+),which is more favorable for the desolvation of Zn^(2+)at low temperatures.In addition,the diglyme effectively suppresses the dendrites,hydrogen evolution reaction,and by-products of the zinc anode,improving the cycle stability of the battery.At-20℃,a Zn‖Zn symmetrical cell is cycled for 5200 h at 1 mA cm^(-2)and 1 mA h cm^(-2),and a Zn‖polyaniline battery achieves an ultra-long cycle life of 10000 times.This study sheds light on the future design of electrolytes with high ionic conductivity and easy desolvation at low temperatures for rechargeable batteries.

Regulating the Solvation Structure of Li^(+) Enables Chemical Prelithiation of Silicon-Based Anodes Toward High-Energy Lithium-Ion Batteries

The solvation structure of Li^(+) in chemical prelithiation reagent plays a key role in improving the low initial Coulombic efficiency(ICE) and poor cycle performance of silicon-based materials. Never theless, the chemical prelithiation agent is difficult to dope active Li^(+) in silicon-based anodes because of their low working voltage and sluggish Li^(+) diffusion rate. By selecting the lithium–arene complex reagent with 4-methylbiphenyl as an anion ligand and 2-methyltetrahydrofuran as a solvent, the as-prepared micro-sized Si O/C anode can achieve an ICE of nearly 100%. Interestingly, the best prelithium efficiency does not correspond to the lowest redox half-potential(E_(1/2)), and the prelithiation efficiency is determined by the specific influencing factors(E_(1/2), Li^(+) concentration, desolvation energy, and ion diffusion path). In addition, molecular dynamics simulations demonstrate that the ideal prelithiation efficiency can be achieved by choosing appropriate anion ligand and solvent to regulate the solvation structure of Li^(+). Furthermore, the positive effect of prelithiation on cycle performance has been verified by using an in-situ electrochemical dilatometry and solid electrolyte interphase film characterizations.

Air-Stable Binary Hydrated Eutectic Electrolytes with Unique Solvation Structure for Rechargeable Aluminum-Ion Batteries

Aluminum-ion batteries(AIBs)have been highlighted as a potential alternative to lithium-ion batteries for large-scale energy storage due to the abundant reserve,light weight,low cost,and good safety of Al.However,the development of AIBs faces challenges due to the usage of AlCl_(3)-based ionic liquid electrolytes,which are expensive,corrosive,and sensitive to humidity.Here,we develop a low-cost,non-corrosive,and air-stable hydrated eutectic electrolyte composed of aluminum perchlorate nonahydrate and methylurea(MU)ligand.Through optimizing the molar ratio to achieve the unique solvation structure,the formed Al(ClO_4)_(3)·9H_(2)O/MU hydrated deep eutectic electrolyte(AMHEE)with an average coordination number of 2.4 can facilely realize stable and reversible deposition/stripping of Al.When combining with vanadium oxide nanorods positive electrode,the Al-ion full battery delivers a high discharge capacity of 320 mAh g^(-1)with good capacity retention.The unique solvation structure with a low desolvation energy of the AMHEE enables Al^(3+)insertion/extraction during charge/discharge processes,which is evidenced by in situ synchrotron radiation X-ray diffraction.This work opens a new pathway of developing low-cost,safe,environmentally friendly and high-performance electrolytes for practical and sustainable AIBs.

Tailoring Mg^(2+)Solvation Structure in a Facile All-Inorganic[Mg_(x)Li_(y)Cl2_(x+y)·nTHF]Complex Electrolyte for High Rate and Long Cycle-Life Mg Battery

A high-performance all-inorganic magnesium-lithium chloride complex(MLCC)electrolyte is synthesized by a simple room-temperature reaction of LiCl with MgCl_(2) in tetrahydrofuran(THF)solvent.Molecular dynamics simulation,density functional theory calculation,Raman spectroscopy,and nuclear magnetic resonance spectroscopy reveal that the formation of[Mg_(x)Li_(y)Cl_(2x+y)·nTHF]complex solvation structure significantly lowers the coordination number of THF in the first solvation sheath of Mg^(2+),which significantly enhances its de-solvation kinetics.The MLCC electrolyte presents a stable electrochemical window up to 3.1 V(vs Mg/Mg^(2+))and enables reversible cycling of Mg metal deposition/stripping with an outstanding Coulombic efficiency up to 99%at current densities as high as 10 mA cm^(-2).Utilizing the MLCC electrolyte,a Mg/Mo_(6)S_(8) full cell can be cycled for over 10000 cycles with a superior capacity retention of 85 mA h g^(-1) under an ultrahigh rate of 50 C(1 C=128.8 mA g^(-1)).The facile synthesis of highperformance MLCC electrolyte provides a promising solution for future practical magnesium batteries.

Electrode-compatible fluorine-free multifunctional additive regulating solid electrolyte interphase and solvation structure for high-performance lithium-ion batteries

The rapid development and widespread application of lithium-ion batteries(LIBs) have increased demand for high-safety and high-performance LIBs. Accordingly, various additives have been used in commercial liquid electrolytes to severally adjust the solvation structure of lithium ions, control the components of solid electrolyte interphase, or reduce flammability. While it is highly desirable to develop low-cost multifunctional electrolyte additives integrally that address both safety and performance on LIBs, significant challenges remain. Herein, a novel phosphorus-containing organic small molecule, bis(2-methoxyethyl) methylphosphonate(BMOP), was rationally designed to serve as a fluorine-free and multifunctional additive in commercial electrolytes. This novel electrolyte additive is low-toxicity,high-efficiency, low-cost, and electrode-compatible, which shows the significant improvement to both electrochemical performance and fire safety for LIBs through regulating the electrolyte solvation structure, constructing the stable electrode-electrolyte interphase, and suppressing the electrolyte combustion. This work provides a new avenue for developing safer and high-performance LIBs.

Structural regulation chemistry of lithium-ion solvation in nonflammable phosphate-based electrolytes for high interfacial compatibility with graphite anode

With the booming development of lithium-ion batteries,safety has become one of the most primary focuses of current researches.Although there are various approaches to enhance the safety of lithiumion batteries,phosphate-based electrolyte holds the greatest potential for practical application due to their non-flammability.Nonetheless,its compatibility issue with the graphite anode remains a significant obstacle to its widespread use.Herein,an effective method is proposed to improve the compatibility of electrolyte with graphite(Gr)anode by rationally adjusting the proportion of lithium salt and solvent components to optimize the Li^(+)solvation structure.By slightly increasing the Li^(+)/triethyl phosphate(TEP)ratio,TEP alone cannot fully occupy the inner solvation sheath and therefore less polar ethylene carbonate(EC)has to be recruited,and the solvation structure gradually changes from Li^(+)–[TEP]_(4)to Li^(+)–[TEP]_(3)[EC]with the coexistence of EC and TEP.Simultaneously,EC molecules in the Li^(+)–[TEP]_(3)[EC]could be preferentially reduced on graphite compared to the TEP molecules,resulting in the formation of a uniform and durable solid-electrolyte interphase(SEI)layer.Benefiting from the optimized phosphate-based electrolyte,the Gr|Li battery exhibits a capacity retention rate of 96.8%after stable cycling at 0.5 C for 470 cycles which shows a longer cycle life than the battery with carbonate electrolyte(cycling at 0.5 C for 450 cycles).Therefore,this work provides the guidance for designing a non-flammable phosphate-based electrolyte for high-safety and long cycling-life lithium-ion batteries.

Rationalizing Na-ion solvation structure by weakening carbonate solvent coordination ability for high-voltage sodium metal batteries

Commercial carbonate-based electrolytes feature highly reactive activities with alkali metals,yielding low Coulombic efficiencies and poor cycle life in lithium metal batteries,which possess much higher chemical activity in the rising star sodium metal batteries.To be motivated,we have proposed that decreasing the solvent solvation ability in carbonate-based electrolytes stepwise could enable longterm stable cycling of high-voltage sodium metal batteries.As the solvation capacity reduces,more anions are enticed into the solvation sheath of Na^(+),resulting in the formation of the more desirable interphase layers on the surface of the anode and the cathode.The inorganic-dominated interphases allow highly efficient Na^(+)deposition/stripping processes with a lower rate of dead sodium generation,as well as maintain a stable structure of the high-voltage cathode material.Specifically,the assembled Na||Na_(3)V_(2)(PO_(4))_(2)F_(3)battery exhibits an accelerated ion diffusion kinetics and achieves a higher capacity retention of 85.9%with during the consecutive 200 cycles under the high voltage of 4.5 V.It is anticipated that the tactics we have proposed could be applicable in other secondary metal battery systems as well.

Li^(+)Solvation Mediated Interfacial Kinetic of Alloying Matrix for Stable Li Anodes

Severe lithium(Li)dendrite growth caused by the uneven overpotential deposition is a formidable challenge for high energy density Li metal batteries(LMBs).Herein,we investigate a synergetic interfacial kinetic to regulate Li deposition behavior and stabilize Li metal anode.Through constructing Li alloying matrix with a bi-functional silver(Ag)-Li_(3)N blended interface,fast Li^(+)conductivity and high Li affinity can be achieved simultaneously,resulting in both decreased Li nucleation and mass transfercontrolled overpotentials.Beyond these properties,a more important feature is demonstrated herein;that is,the inward diffusion depth of the Li adatoms inside of the Ag site can be restricted by the Li^(+)solvation structure in a highly coordinating environment.The latter feature can ensure the durability of the operational Ag sites,thereby elongating the Li protection ability of the Ag-Li_(3)N interface greatly.This work provides a deep insight into the synergetic effect of functional alloying structure and Li^(+)solvation mediated interfacial kinetic on Li metal protection.

Electrolyte Solvation Structure Design for High Voltage Zinc-Based Hybrid Batteries

Zinc(Zn)metal anodes have enticed substantial curiosity for large-scale energy storage owing to inherent safety,high specific and volumetric energy capacities of Zn metal anodes.However,the aqueous electrolyte traditionally employed in Zn batteries suffers severe decomposition due to the narrow voltage stability window.Herein,we introduce N-methylformamide(NMF)as an organic solvent and modulate the solvation structure to obtain a stable organic/aqueous hybrid electrolyte for high-voltage Zn batteries.NMF is not only extremely stable against Zn metal anodes but also reduces the free water molecule availability by creating numerous hydrogen bonds,thereby accommodating high-voltage Zn‖LiMn_(2)O_(4)batteries.The introduction of NMF prevented hydrogen evolution reaction and promoted the creation of an Frich solid electrolyte interphase,which in turn hampered dendrite growth on Zn anodes.The Zn‖LiMn_(2)O_(4)full cells delivered a high average Coulombic efficiency of 99.7%over 400 cycles.

Tuning desolvation kinetics of in-situ weakly solvating polyacetal electrolytes for dendrite-free lithium metal batteries

The host structure of polymers significantly influences ion transport and interfacial stability of electrolytes,dictating battery cycle life and safety for solid-state lithium metal batteries.Despite promising properties of ethylene oxide-based electrolytes,their typical clamp-like coordination geometry leads to crowd solvation sheath and overly strong interactions between Li^(+)and electrolytes,rendering difficult dissociation of Li+and unfavorable solid electrolyte interface(SEI).Herein,we explore weakly solvating characteristics of polyacetal electrolytes owing to their alternately changing intervals between–O–coordinating sites in the main chain.Such structural asymmetry leads to unique distorted helical solvation sheath,and can effectively reduce Li^(+)-electrolyte binding and tune Li^(+)desolvation kinetics in the insitu formed polymer electrolytes,yielding anion-derived SEI and dendrite-free Li electrodeposition.Combining with photoinitiated cationic ring-opening polymerization,polyacetal electrolytes can be instantly formed within 5 min at the surface of electrode,with high segmental chain motion and well adapted interfaces.Such in-situ polyacetal electrolytes enabled more than 1300-h of stable lithium electrodeposition and prolonged cyclability over 200 cycles in solid-state batteries at ambient temperatures,demonstrating the vital role of molecular structure in changing solvating behavior and Li deposition stability for high-performance electrolytes.

Solvatochromic Parameters and Preferential Solvation Behavior for Binary Mixtures of 1,3-Dialkylimidazolium Ionic Liquids with Water

Binary mixtures of 1,3-dialkylimidazolium based ionic liquids （ILs） and water were selected as solvent systems to investigate the solute-solvent and solvent-solvent interactions on the preferential solvation of solvatochromic indicators at 25 ℃. Empirical solvatochromic pa- rameters, dipolarity/polarizability （π^＊）, hydrogen-bond donor acidity （α）, hydrogen-bond acceptor basicity （β）, and Reichardt＇s polarity parameters （ET^N） were measured from the ultraviolet-visible spectral shifts of 4-nitroaniline, 4-nitroanisole, and Reichardt＇s dye. The solvent properties of the IL-water mixtures were found to be influenced by IL type and IL mole fraction （XIL）. All these studied systems showed the non-ideal behavior. The max- imum deviation to ideality for the solvatochromic parameters can be obtained in the XIL range from 0.i to 0.3. For most of the binary mixtures, the π^＊ values showed the synergistic effects instead of the ETN, α and β values. The observed synergy extent was dependent on the studied systems, such as the dye indicator and IL type. A preferential solvation model was utilized to gather information on the molecular interactions in the mixtures. The dye indicator was preferentially solvated on the following trend： IL〉IL-water complex〉water.

Effects of Non-specific and Specific Solvation on Adsorption of BPTI on Au Surface： Insight from Molecular Dynamics Simulation

Proteins adsorption at solid surfaces are of paramount important for many natural processes. However, the role of specific water in influencing the adsorption process has not been well understood. We used molecular dynamics simulation to study the adsorption of BPTI on Au surface in three water environments （dielectric constant model, partial and full solvation models）. The result shows that a fast and strong adsorption can occur in the dielectric environment, which leads to significant structure changes, as confirmed by great deviation from the crystal structure, largely spreading along the Au surface, rapid lose in all secondary structures and the great number of atoms in contact with the surface. Compared to the dielectric model, slower adsorption and fewer changes in the calculated properties above are observed in the partial solvation system since the specific water layer weakens the adsorption effects. However, in the partial solvation system, the adsorption of polar Au surface causes a significant decrease in the specific hydration around the protein, which still results in large structure changes similar to the dielectric system, but with much less adsorption extent. Enough water molecules in the full solvation system could allow the protein to rotate, and to large extent preserve the protein native structure, thus leading to the slowest and weakest adsorption. On the whole, the effects of non-specific and specific solvation on the protein structure and adsorption dynamics are significantly different, highlighting the importance of the specific water molecule in the protein adsorption.

Structural and Infrared Spectroscopic Study on Solvation of Acetylene by Protonated Water Molecules

The effect of solvation on the conformation of acetylene has been studied by adding one water molecule at a time. Quantum chemical calculations of the n＋ （C2H2）（H2O）n （n=1-5） clusters indicate that the H2O molecules prefer to form the OH...Tr interaction rather than the CH...O interaction. This solvation motif is different from that of neutral （C2H2）（H2O）n （n=1-4） clusters, in which the H2O molecules prefer to form the CH...O and OH...C Hbonds. For the H＋（C2H2）（H2O）n cationic clusters, the first solvation shell consists of one ring structure with two OH...Tr H-bonds and three water molecules, which is completed at n=4. Simulated infrared spectra reveal that vibrational frequencies of OH... H-bonded O-H stretching afford a sensitive probe for exploring the solvation of acetylene by protonated water molecules. Infrared spectra of the H＋ （C2H2）（H2O）n （n=1-5） clusters could be readily measured by the infrared photodissociation technique and thus provide useful information for the understanding of solvation processes.

Spectral Shift of π→π^＊ Transition for p-Nitroaniline Based on a New Expression of Nonequilibrium Solvation Energy

According to the nonequilibrium solvation theory studies, a constrained equilibrium principle is introduced and applied to the derivations of the nonequilibrium solvation energy, and a reasonable expression of the spectral shift of the electronic absorption spectra is deduced. Furthermore, the lowest transition of p-nitroaniline （pNA） in water is investigated by time-dependent density functional theory method. In addition, the details of excited state properties of pNA are discussed. Using our novel expression of the spectral shift, the value of -0.99 eV is obtained for π→π^＊ transition in water, which is in good agreement with the available experimental result of -0.98 eV.

Spectrum Correction in Study of Solvation Dynamics by Fluorescence Non-collinear Optical Parametric Amplification Spectroscopy

Femtosecond time-resolved fluorescence non-collinear optical parametric amplification spec- troscopy can extract the curve of spectral gain from its parametric superfluorescence. This unique spectrum correction method enables fluorescence non-collinear optical parametric amplification spectroscopy acquiring the genuine transient fluorescence spectrum of the studied system. In this work we employ fluorescence non-collinear optical parametric amplification spectroscopy technique to study the solvation dynamics of DCM dye in ethanol solution, and confirm that genuine solvation correlation function and shift of peak frequency can be derived from transient fluorescence spectra after the spectral gain correction. It demonstrates that fluorescence non-collinear optical parametric amplification spectroscopy can benefit the research fields, which focuses on both fluorescence intensity dynamics and fluorescence spectral shape evolution.