Reviewing electrochemical stability of ionic liquids-/deep eutectic solvents-based electrolytes in lithium-ion,lithium-metal and post-lithium-ion batteries for green and safe energy

Sustainable energy is the key issue for the environment protection,human activity and economic development.Ionic liquids(ILs)and deep eutectic solvents(DESs)are dogmatically regarded as green and sustainable electrolytes in lithium-ion,lithium-metal(e.g.,lithium-sulphur,lithium-oxygen)and post-lithium-ion(e.g.,sodium-ion,magnesium-ion,and aluminum-ion)batteries.High electrochemical stability of ILs/DESs is one of the prerequisites for green,sustainable and safe energy;while easy electrochemical decomposition of ILs/DESs would be contradictory to the concept of green chemistry by adding the cost,releasing volatile/hazardous by-products and hindering the recyclability.However,(1)are ILs/DESs-based electrolytes really electrochemically stable when they are not used in batteries?(2)are ILs/DESs-based electrolytes really electrochemically stable in real batteries?(3)how to design ILs/DESs-based electrolytes with high electrochemical stability for batteries to achieve sustainability and green development?Up to now,there is no summary on this topic,to the best of our knowledge.Here,we review the effect of chemical structure and non-structural factors on the electrochemical stability of ILs/DESs in simulated conditions.More importantly,electrochemical stability of ILs/DESs in real lithium-ion,lithium-metal and post-lithium-ion batteries is concluded and compared.Finally,the strategies to improve the electrochemical stability of ILs/DESs in lithium-ion,lithium-metal and post-lithium-ion batteries are proposed.This review would provide a guide to design ILs/DESs with high electrochemical stability for lithium-ion,lithium-metal and postlithium-ion batteries to achieve sustainable and green energy.

Green‑Solvent Processed Blade‑Coating Organic Solar Cells with an Efficiency Approaching 19%Enabled by Alkyl‑Tailored Acceptors

Power-conversion-efficiencies(PCEs)of organic solar cells(OSCs)in laboratory,normally processed by spin-coating technology with toxic halogenated solvents,have reached over 19%.However,there is usually a marked PCE drop when the bladecoating and/or green-solvents toward large-scale printing are used instead,which hampers the practical development of OSCs.Here,a new series of N-alkyl-tailored small molecule acceptors named YR-SeNF with a same molecular main backbone are developed by combining selenium-fused central-core and naphthalene-fused endgroup.Thanks to the N-alkyl engineering,NIR-absorbing YR-SeNF series show different crystallinity,packing patterns,and miscibility with polymeric donor.The studies exhibit that the molecular packing,crystallinity,and vertical distribution of active layer morphologies are well optimized by introducing newly designed guest acceptor associated with tailored N-alkyl chains,providing the improved charge transfer dynamics and stability for the PM6:L8-BO:YRSeNF-based OSCs.As a result,a record-high PCE approaching 19%is achieved in the blade-coating OSCs fabricated from a greensolvent o-xylene with high-boiling point.Notably,ternary OSCs offer robust operating stability under maximum-power-point tracking and well-keep>80%of the initial PCEs for even over 400 h.Our alkyl-tailored guest acceptor strategy provides a unique approach to develop green-solvent and blade-coating processed high-efficiency and operating stable OSCs,which paves a way for industrial development.

Effect of Temperature on Extraction of Castor Oil from Castor Seeds Using Potential Green Solvents

Extraction of castor oil from castor seeds was investigated using different green solvents which include d-limonene, p-cymene, α-pinene, ethanol, and furfural at the temperature range of (323 - 413) K. The Soxhlet extraction method was employed to investigate the effect of temperature at atmospheric pressure. The focus of the study was to investigate a potential green solvent that can produce the high yields compared to the traditional solvent (hexane). The results show that at the average time of 3 hours and 30 minutes, the castor oil yield for green solvents were ranked as furfural (47.13%) > ethanol (45.37%) > p-cymene (39.15%) > d-limonene (39.13%) > α-pinene (38.11%). These castor oil yields were obtained at optimum temperatures for each green solvent. The castor oil yields were compared to the yield of hexane (31.36%) at same average time. The green solvents were recovered by using simple distillation, except furfural which was difficult to be recovered.

The use of environmentally sustainable bio-derived solvents in solvent extraction applications——A review

Replacement of volatile organic compounds （VOCs） by greener or more environmentally sustainable solvents is becoming increasingly important due to the increasing health and environmental concerns as well as economic pressures associated with VOCs. Solvents that are derived from biomass, namely bio-derived solvents, are a type of green solvent that have attracted intensive investigations in recent years because of their advantages over con- ventional VOCs, such as low toxicity, biodegradability and renewability. This review aims to summarize the use of bio-derived solvents in solvent extraction applications, with special emphasis given to utilization of biodiesels and terpenes. Compared with the conventional VOCs, the overall performance of these bio-derived solvents is comparable in terms of extraction yields and selectivity for natural product extraction and no difference was found for metal extraction. To date most researchers have focused on laboratory scale thermodynamics studies. Future work is required to develop and test new bio-derived solvents and understand the kinetic performance as well as solvent extraction nilnt nlant studies.

Impact of solvents and surfactants on the self-assembly of nanostructured amine functionalized silica spheres for CO_(2) capture

Macroscopic SiO2 spheres with a homogeneous amine distribution were synthesized by a one-step emulsion based synthesis approach in a flow column reactor. The CO2 adsorption capacity of the nanostructured amine-functionalized silica spheres was studied in absence and presence of H2O. The structural properties were adjusted by varying solvents and surfactants during the synthesis and, at constant amine loadings, were found to be the main factor for influencing the CO2 sorption capacities. Under water-free conditions CO2 is bound to the amino groups via the formation of carbamates, which require two neighboring amino groups to adsorb one CO2 molecule. At constant amine concentrations sorbents with lower surface area allow to establish a higher amine density on the surface, which enhances the CO2 uptake capacities under dry conditions. In presence of H2O the CO2 adsorption changes to 1：1 stoichiometry due to stabilization of carbamates by protonation of H2O and formation of further species such as bicarbonates, which should in principle double the adsorption capacities. Low concentrations of physisorbed H2O（0.3 mmol/g） did not impair the adsorption capacity of the adsorbents for CO2, while at higher water uptakes（0.6 and 1.1 mmol/g） the CO2 uptake is reduced, which could be attributed to capillary condensation of H2O or formation of bulky reaction products blocking inner pores and access to active sites.

Non-Halogenated Solvent-Processed High-Efficiency Polymer Solar Cells:the Role of Diphenyl Ether in Morphology,Light-Trapping,Transport Properties

There is an urgent need to use green non-halogenated solvents to prepare polymer solar cells(PSCs) for industrialization.It is time-consuming but necessary to find a suitable non-halogenated solvent/additive combination for a given donor:acceptor materials system.In this research,we report a non-halogenated binary solvent system toluene/diphenyl ether(DPE) for the PBDTT-DTffBT:PC_(71)BM and PM6:Y6 blending systems that exhibit comparable power conversion efficiency(PCE) to that of devices prepared with halogenated solvents.The nano scale morphology indicates that blending film processed solely with toluene has poor phase segregation and a rough surface,which hinders charge separation and interfacial contact.Besides,the total absorption spectra revealed significant light-trapping losses in the toluene-processed solar cells,resulting in low photocurrent generation.DPE incorporation addresses these issues and significantly improves the short-circuit current density and fill factor.Moreover,non-halogen solvent-processed devices exhibit high hole mobility and low transporting impedance properties.The present study enriches the families of eco-friendly,high-efficiency PSCs fabricated using nonhalogenated solvents.

Characterization of the acidity and basicity of green solvents by NMR techniques

The acidity and basicity of the solvents can influence the reaction outcome notably,and hence the precise measurement of pH is important for reaction.However,not all the pH values of organic solvents can be determined with a classic pH meter straightly.In this research,the acidity and basicity of environmentally friendly green solvents,such as ZnCl_(2) molten salt hydrate,ionic liquids(ILs)and deep eutectic solvents(DESs),were characterized by 31P and 1 H NMR spectroscopy using trimethylphosphine oxide(TMPO)and pyrrole as probe molecules at 298 K.For the ZnCl_(2) molten salt hydrate,the acidic strength of the ZnCl_(2) molten salt hydrate increased with the concentration of ZnCl_(2).By using the ^(1)H-pyrrole NMR approach,it was found that the base strength of amino acid-based ILs follows the order:[Ch][Lys]>[Ch][His].

Investigating TEP as a greener alternative to NMP in Ni-rich cathode fabrication

In the past decade,the surging demand for portable electronics,electric vehicles,and stationary energy storage grids has triggered a noticeable rise in the production of Li-ion batteries(LIBs).However,this swift rise is now hindered by relying on the use of N-methyl-2-pyrrolidone(NMP),a repro-toxic solvent,in the current cathode processing of LIBs.To overcome this challenge,here we have investigated triethyl phosphate(TEP) as a greener alternative to NMP.The compatibility with polyvinylidene fluoride(PVDF)binder,the slurry rheology,the electrode morphology and cell performance with Ni-rich cathodes are characterized.The results show that TEP-based samples possess indistinguishable characteristics in all as pects studied when compared with NMP,revealing that TEP is a promising substitute for NMP in processing Ni-rich cathodes.It is anticipated that this green solvent,TEP,will draw attention from industry in the real-world LIB application in the future.

Oriented Organization of Poly(3-Hexylthiophene)for Efficient and Stable Antimony Sulfide Solar Cells

Poly(3-hexylthiophene)(P3HT),as a traditional organic hole-transporting material(HTM),is widely used in thin-film solar cells due to its high charge mobility and good thermal stability.However,the P3HT films obtained by the traditional method are amorphous,which is unfavorable to hole extraction and transport.Here,a low-toxicity solvent 1,2,4-trimethylbenzene(TMB)was used as the solvent instead of the commonly used halogen solvent chlorobenzene(CB)to dissolve P3HT.Thus,the self-assembled nanofibrous P3HT film was prepared and applied as HTM in the newly emerged Sb_(2)S_(3)solar cells.According to the density functional theory calculations,the interface contact between TMB-P3HT and Sb_(2)S_(3)was enhanced via the bonding interaction of S in P3HT and Sb in Sb_(2)S_(3).Through transient absorption spectroscopy characterization,the enhanced interface contact improves the charge extraction ability of TMB-P3HT when compared to the CB-P3HT film.Thus,the TMB-P3HT-based Sb_(2)S_(3)solar cell delivers a power conversion efficiency of 6.21%,which is 9.7%higher than that of the CB-P3HT-based device.Furthermore,the dopant-free TMB-P3HT-based Sb_(2)S_(3)devices exhibit excellent environmental stability compared with Spiro-OMeTAD-based devices.This work demonstrates that the application of P3HT and the solvent engineering of HTM are applicable strategies for developing Sb_(2)S_(3)solar cells with high efficiency and stability.

Low-melting mixture solvents:extension of deep eutectic solvents and ionic liquids for broadening green solvents and green chemistry

Green solvents such as water and ionic liquids(ILs)are pillars of the great mansion of green chemistry and green processing.Initially proposed as a new family of ILs,deep eutectic solvents(DESs)have received fast development in the past two decades.In this contribution,DESs are reviewed critically and the concept is extended to lowmelting mixture solvents(Lo MMSs),which cover all kinds of materials including ionic compounds,molecular compounds,and metals.Six classes of Lo MMSs are proposed as the new classification system and examples are given.Finally,several thermodynamic issues concerning Lo MMSs are discussed.Two new concepts,robustness of Lo MMSs and high-entropy Lo MMSs,are proposed.

High-gravity-assisted green synthesis of rare-earth doped calcium molybdate colloidal nanophosphors

In this work,we report an innovative route for the synthesis of rare-earth doped calcium molybdate(CaMoO4)nanophosphors by using high gravity rotating packed bed(RPB)technology and paraffin liquid as the solvent.The significant intensified mass transfer and micromixing of reactants in the RPB reactor are benefiting for homogeneous doping of rare-earth ions in the host materials,leading to nanophosphors with high quantum efficiency.The use of liquid paraffin as the solvent eliminates the safety risks associated with volatile organic compounds,increasing the potential for clean production of nanophosphors.Under excitation of deep ultraviolet(DUV)light,the CaMoO4:Na+,Eu3+nanophosphors exhibit red emission at peak wavelength of 615 nm and quantum yield of up to 35.01%.The CaMoO4:Na+,Tb3+nanophosphors exhibit green emission at peak wavelength of543 nm with quantum yield of up to 30.66%.The morphologies of the nanophosphors are tunable from nanofibers through nanorods to nanodots and the possible mechanism of controlling the formation of different nanostructures is proposed on the basis of experimental results and theoretical analysis of mesoscience.These nanophosphors are highly dispersible in organic solvents and utilized for fabricating fabrication of flexible,freestanding luminescent films based on silicone resin.We also demonstrate the red LEDs consisting of the hybrid films of CaMoO4:Na+,Eu3+nanoparticles as color-converting phosphors and DUV LEDs as illuminators,offering strong potential for future nanophosphors-basedsolid-state lighting systems.

Ionic Liquids: Progress and Prospective

Ionic liquids （ILs） are green solvents that have attracted great attention in recent years due to their unique properties. In this paper the latest progresses in both the fundamental studies and applications of ILs have been summarized, with the emphasis on the topics of physical properties, catalytic reactions, and biochemical engineering. The critical problems in the applications of the ILs have been addresses, and the prospective of the ILs were finally predicted.

New process development and process evaluation for capturing CO2 in flue gas from power plants using ionic liquid[emim][Tf2N]

Using the ionic liquid[emim][Tf2N]as a physical solvent,it was found by Aspen Plus simulation that it was possible to attempt to capture CO2 from the flue gas discharged from the coal-fired unit of the power plant.Using the combination of model calculation and experimental determination,the density,isostatic heat capacity,viscosity,vapor pressure,thermal conductivity,surface tension and solubility of[emim][Tf2N]were obtained.Based on the NRTL model,the Henry coefficient and NRTL binary interaction parameters of CO2 dissolved in[emim][Tf2N]were obtained by correlating[emim][Tf2N]with the gas–liquid equilibrium data of CO2.Firstly,the calculated relevant data is imported into Aspen Plus,and the whole process model of the ionic liquid absorption process is established.Then the absorption process is optimized according to the temperature distribution in the absorption tower to obtain a new absorption process.Finally,the density,constant pressure heat capacity,surface tension,thermal conductivity,and viscosity of[emim][Tf2N]were changed to investigate the effect of ionic liquid properties on process energy consumption,solvent circulation and heat exchanger design.The results showed that based on the composition of the inlet gas stream to the absorbers,CO2 with a capture rate of 90%and a mass purity higher than 99.5%was captured.These results indicate that the[emim][Tf2N]could be used as a physical solvent for CO2 capture from coal-fired units.In addition,the results will provide a theoretical basis for the design of new ionic liquids for CO2 capture.

Mild and efficient recovery of lithium-ion battery cathode material by deep eutectic solvents with natural and cheap components

Dissolution of lithium cobalt oxide(LCO)is the key step for the recovery of valuable metals(e.g.,Co and Li)from spent LCO-based lithium-ion batteries(LIBs).However,the dissolution process of LCO either needs toxic solvents,and high temperature,or shows low efficiency.Deep eutectic solvents(DESs)are potential green solvents to dissolve LCO.Here,DESs with polyethylene glycol(PEG)as hydrogen bond acceptor and ascorbic acid(AA)as hydrogen bond donor are found to dissolve LCO with 84.2%Co leaching efficiency at 80℃ and 72 h,which is higher than that from the reported references by common DESs.Furthermore,both DESs components(i.e.,PEG and AA)are cheap,biodegradable,and biocompatible.AA could be easily and abundantly extracted from natural fruits or vegetables.It provides a new guide for the green,mild,and efficient dissolution of LCO aiming at sustainable recovery of spent LIBs.

Host-Guest Strategy Enabling Nonhalogenated Solvent Processing for High-Performance All-Polymer Hosted Solar Cells

The power conversion efficiencies(PCEs)of all-polymer solar cells(all-PSCs),usually processed from low-boiling-point and toxic sol-vents,have reached high values of 18%.However,poor miscibility and uncontrollable crystallinity in polymer blends lead to a nota-ble drop in the PCEs when using green solvents,limiting the practical development of all-PSCs.Herein,a third component(guest)BTO was employed to optimize the miscibility and enhance the crystallinity of PM6/PY2Se-F host film processed from green solvent toluene(TL),which can effectively suppress the excessive aggregation of PY2Se-F and facilitate a nano-scale interpenetrating net-work morphology for exciton dissociation and charge transport.As a result,TL-processed all-polymer hosted solar cells(all-PHSCs)exhibited an impressive PCE of 17.01%.Moreover,the strong molecular interaction between the host and guest molecules also en-hances the thermal stability of the devices.Our host-guest strategy provides a unique approach to developing high-efficiency and stable all-PHSCs processed from green solvents,paving the way for the industrial development of all-PHSCs.

Fluorous Biphase System of C9F18 and Its Use in Esterification

Some apolar organic solvents is miscible with perfluorous nonene to form fluorous biphase systems.Perfluorous nonene could be used as a green solvent in equimolar esterification of carboxylic acids with alcohols without removal of water or ester formed. Perfluorous nonene made the esterification equilibrium to move right and the yields of esterification to enhance in different degrees as compared with that in the absence of perfluorous nonene. After esterification perfluorous nonene is easy to be recovered and recycled.

Over 9% efficiency achieved for all-polymer solar cells processed by a green solvent

Bulk-heterojunction polymer solar cells （PSCs） have at- tracted considerable attention owning to their potential for fabricating flexible, light-weight and large area solar cell panels via high-throughput roll-to-roll technologies. Compared with conventional PSCs comprising small mol- ecule acceptors, such as fullerenes, all-polymer solar cells （all-PSCs） containing blends of p-type/n-type polymers in the photoactive layer provide advantages including easily tunable absorption band, enhanced absorption coefficient,

Host-Guest Active Layer Enabling Annealing-Free,Nonhalogenated Green Solvent Processing for High-Performance Organic Solar Cells

Recent advances in non-fullerene acceptors(NFAs)like Y6 have pushed the power conversion efficiencies(PCEs)of organic solar cells(OSCs)above 19%.However,the harsh fabrication conditions,such as the use of the highly volatile chloroform(CF)solvent and the thermal annealing process,are not suitable for large-area printing technologies and environmental standards.Here,a series of guest molecules,BT2O,BTO,and BT4O,are designed and synthesized with different numbers of oligo ethylene glycol(OEG)repeating units in side chains.All these guest molecules could tune the crystallization kinetics of the annealing-free host-guest active layers by inducing the self-assembly of Y6 in non-halogenated paraxylene(PX)solution.The increasing number of OEG repeating units in guest molecules could enhance the molecular assembly ability but molecular stacking steric hindrance simultaneously.Therefore,BTO with three OEG repeating units blended with PM6:PM7:Y6 delivers the highest PCE of 17.78%.Our results demonstrate controlling the crystallization kinetics via delicate side-chain engineering of guest molecules is an effective way to achieve efficient OSCs in non-halogenated solution.

Revisiting greenness of ionic liquids and deep eutectic solvents

Green solvents are one of the hot topics of green chemistry.Ionic liquids(ILs)and deep eutectic solvents(DESs)are deemed as green solvents to a certain extent,and they have been applied in many areas,such as dissolution,separation,catalysis,electrochemistry and material synthesis.However,the greenness of ILs and DESs should be revisited because more and more evidences have shown that they are not always green.In this perspective,besides the reported merits,the disadvantages and problems of some ILs and DESs,such as instability,volatility,hygroscopicity,toxicity,flammability,regenerability,cost,energy consumption and impurities are discussed.Moreover,13 strategies to avoid the disadvantages of ILs and DESs and to increase the greenness are proposed.Comparison of the greenness of ILs and DESs is further conducted.This perspective provides some new viewpoints on the greenness of ILs and DESs.

Advances in Green-Solvent-Processable All-Polymer Solar Cells

All-polymer solar cells(all-PSCs)have significantly improved long-term stability and mechanical stretchability.The power conversion efficiency(PCE)of all-PSCs has been rapidly improved from∼1%to now over∼17%,driven by rational molecular design,blend morphology optimization,and device engineering.However,most all-PSCs are generally processed with halogenated solvents,hazardous for human health and the global environment.Achieving high-performance all-PSCs with halogen-free solvent processing remains a challenge.This feature article presents recent advances in green-solvent-processable all-PSCs from the material design and morphological control perspective,and further reviews progress in using more environmentally friendly solvents(i.e.,water or alcohol)to achieve genuinely sustainable and environmentally friendly manufacturing all-PSCs.Finally,we provide an outlook on the challenges and opportunities for large-scale manufacturing of green-solvent-processable all-PSCs.